Upgrading and Repairing PC

Citation preview

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Contents

Cont ent s at a Glance In trod u ction

1

1 Person al Com p u ter Backgrou n d

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2 PC Com p on en ts, Featu res, an d System Design 15 3 Microp rocessor Typ es an d Sp ecification s 4 Moth erboard s an d Bu ses 5 Mem ory

UPGRADING AND

REPAIRING PCs T enth Anniversary Edition

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6 Power Su p p ly an d Case 7 In p u t Devices

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8 Vid eo Hard ware

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9 Au d io Hard ware

549

10 I/ O In terfaces

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11 Com m u n ication s an d Networkin g 12 Magn etic Storage 13 Op tical Storage 14 Prin ters

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709 823

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15 Portable PCs

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16 Bu ild in g or Up grad in g System s 17 Diagn ostics an d Testin g

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18 Op eratin g System s Software an d Trou blesh ootin g 1031 19 File System s an d Data Recovery

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20 IBM Person al Com p u ter Fam ily Hard ware 1099 21 A Fin al W ord A Ven d or List

Scott Mueller with Craig Zacker

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B Usefu l Hard ware W eb Sites C Glossary

D Tech n ical Referen ce List of Acron ym s

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In d ex of Man u factu rers In d ex

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Upgrading and Repairing PCs Tent h Anniversary Edit ion Co p y ri g h t © 1 9 9 8 b y Qu e ® Co rp o ra t i o n All righ ts reserved . No p art of th is book sh all be rep rod u ced , stored in a retrieval system , or tran sm itted by an y m ean s, electron ic, m ech an ical, p h otocop yin g, record in g, or oth erwise, with ou t written p erm ission from th e p u blish er. No p aten t liability is assu m ed with resp ect to th e u se of th e in form ation con tain ed h erein . Alth ou gh every p recau tion h as been taken in th e p rep aration of th is book, th e p u blish er an d au th or assu m e n o resp on sibility for errors or om ission s. Neith er is an y liability assu m ed for d am ages resu ltin g from th e u se of th e in form ation con tain ed h erein . In tern ation al Stan d ard Book Nu m ber: 0-7897-1636-4 Library of Con gress Catalog Card Nu m ber: 98-84282 Prin ted in th e Un ited States of Am erica First Prin tin g: Sep tem ber 1998 00

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Tradem arks All term s m en tion ed in th is book th at are kn own to be trad em arks or service m arks h ave been ap p rop riately cap italized . Qu e can n ot attest to th e accu racy of th is in form ation . Use of a term in th is book sh ou ld n ot be regard ed as affectin g th e valid ity of an y trad em ark or service m ark.

Execut ive Edit or Jim Min atel

Acquisit ions Edit or Jill Byu s

Developm ent Edit or Rick Ku gh en

Technical Review ers Ken t Easley Tyson Heyn Dou g Klip p ert Carl Larson Pete Len ges Joh n Rou rke Jeff Sloan

Technical Edit ors Deb Fogle Ru ss Jacobs Kevin Lan gston Bob Pierson Pat Regan

M anaging Edit or Th om as F. Hayes

Project Edit or Gin a Brown

Copy Edit or Ju lie McNam ee

Indexer Ch ris Wilcox

Soft w are Developm ent Specialist Joh n Warrin er

Product ion Maribeth Ech ard Joh n Etch ison Ch risty M. Lem asters

Contents

Contents Int roduct ion

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W h at Are th e Main Objectives of Th is Book? W h o Sh ou ld Use Th is Book? W h at Is in Th is Book?

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W h at’s New an d Sp ecial Abou t th e Ten th An n iversary Ed ition Th e Ten th An n iversary Ed ition CD-ROMs 7 A Person al Note

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1 Personal Com put er Background Person al Com p u tin g History

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Th e IBM Person al Com p u ter

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Th e IBM-Com p atible Marketp lace 17 Years Later

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2 PC Com ponent s, Feat ures, and Syst em Design W h at Is a PC? 15 W h o Con trols PC Software? 16 W h o Con trols PC Hard ware? 18 PC 9x Sp ecification s 21 System Typ es

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System Com p on en ts 25 Moth erboard 26 Processor 27 Mem ory (RAM) 27 Case (Ch assis) 27 Power Su p p ly 28 Flop p y Disk Drive 28 Hard Disk Drive 28 CD-ROM Drive 28 Keyboard 29 Mou se 29 Vid eo Card 29 Mon itor (Disp lay) 30

3 M icroprocessor Types and Specificat ions 31 Processor Sp ecification s 31 Processor Sp eed Ratin gs Data Bu s 38

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In tern al Registers 39 Ad d ress Bu s 40 In tern al (Level 1) Cach e 41 Processor Mod es 43 Processor Featu res 47 Processor Man u factu rin g 50 Ph ysical Packagin g 53 Processor Sockets 54 CPU Op eratin g Voltages 72 Heat an d Coolin g Problem s 74 Math Cop rocessors 75 Processor Bu gs 77 Processor Up d ate Featu re 78 In tel Processor Cod en am es 79 In tel-Com p atible Processors AMD Processors 80 Cyrix 81 IDT W in ch ip 82 P-Ratin gs 83

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Processor Typ es 83 P1 (086) First-Gen eration Processors 83 P2 (286) Secon d -Gen eration Processors 85 P3 (386) Th ird -Gen eration Processors 87 P4 (486) Fou rth -Gen eration Processors 92 P5 (586) Fifth -Gen eration Processors 105 Pseu d o-Fifth -Gen eration Processors 126 P6 (686) Sixth -Gen eration Processors 127 Pseu d o-Sixth -Gen eration Processors 152 P7 (786) Seven th -Gen eration Processors 158 Processor Up grad es 161 OverDrive Processors 162 OverDrive Processor In stallation 162 OverDrive Com p atibility Problem s 163 Processor Ben ch m arks 164

4 M ot herboards and Buses 167 Moth erboard Form Factors 167 Baby-AT 167 Fu ll-Size AT 169 LPX 170 ATX 173 NLX 176 Prop rietary Design s 179 Backp lan e System s 180 Moth erboard Com p on en ts 182 Processor Sockets/ Slots 182 Ch ip sets 183

Contents

In tel Ch ip sets 185 In tel’s Early 386/ 486 Ch ip sets 187 Fifth -Gen eration (P5 Pen tiu m Class) Ch ip sets 187 Th ird -Party (Non -In tel) P5 Pen tiu m Class Ch ip sets 194 Sixth -Gen eration (P6 Pen tiu m Pro/ Pen tiu m II Class) Ch ip sets 199 Th ird -Party (Non -In tel) P6 Class Ch ip sets 205 Su p er I/ O Ch ip s 207 BIOS 208 Up grad in g th e ROM BIOS 215 BIOS Error Messages 222 Moth erboard CMOS RAM Ad d resses 224 Moth erboard In terface Con n ectors 228 System Bu s Fu n ction s an d Featu res Th e Processor Bu s 234 Th e Mem ory Bu s 237 Th e Need for Exp an sion Slots

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Typ es of I/ O Bu ses 238 Th e ISA Bu s 239 Th e Micro Ch an n el Bu s 245 Th e EISA Bu s 246 Local Bu ses 250 VESA Local Bu s 252 Th e PCI Bu s 256 Accelerated Grap h ics Port (AGP)

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System Resou rces 270 In terru p ts (IRQs) 270 DMA Ch an n els 275 I/ O Port Ad d resses 277 Resolvin g Resou rce Con flicts 281 Resolvin g Con flicts Man u ally 281 Usin g a System -Con figu ration Tem p late 283 System Resou rce Map 284 System Resou rce Map 285 Head in g Off Problem s: Sp ecial Board s 287 Plu g-an d -Play System s 290 Kn owin g W h at to Look For (Selection Criteria) Docu m en tation 297 Usin g Correct Sp eed -Rated Parts 298

5 M em ory 301 Mem ory Basics

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Typ es of Mem ory 303 ROM 304 Mask ROM 306 PROM 306

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EPROM 308 EEPROM/ Flash ROM DRAM 311

309

Mem ory Sp eed s 312 Fast Page Mod e (FPM) DRAM EDO RAM 315 Bu rst EDO 316 SDRAM 316

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Fu tu re DRAM Mem ory Tech n ologies RDRAM 317 DDR SDRAM 318 Cach e Mem ory—SRAM

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Ph ysical Mem ory 323 SIMMs an d DIMMs 324 SIMM Pin ou ts 329 Ph ysical RAM Cap acity an d Organ ization Mem ory Ban ks 338 RAM Ch ip Sp eed 340 Gold Versu s Tin 340 Mem ory Reliability 344

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In stallin g Mem ory Up grad es 352 Up grad e Op tion s an d Strategies 352 Selectin g an d In stallin g Moth erboard Mem ory with Ch ip s, SIMMs, or DIMMs 353 Rep lacin g SIMMS an d DIMMs with High er Cap acity 353 Ad d in g Ad ap ter Board s 354 In stallin g Mem ory 354 Th e System Logical Mem ory Layou t 359 Con ven tion al (Base) Mem ory 360 Up p er Mem ory Area (UMA) 360 Exten d ed Mem ory 376 Exp an d ed Mem ory 379 Preven tin g ROM BIOS Mem ory Con flicts an d Overlap 380 ROM Sh ad owin g 381 Total In stalled Mem ory Versu s Total Usable Mem ory 382 Ad ap ter Mem ory Con figu ration an d Op tim ization 385 Takin g Ad van tage of Un u sed Up p er Mem ory 387

6 Pow er Supply and Case

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Power Su p p ly Fu n ction an d Op eration 391 Power Su p p ly Form Factors 393 Power Su p p ly Con n ectors 403 Th e Power_Good Sign al 409 Power Su p p ly Load in g 410 Power-Su p p ly Ratin gs 412 Power Su p p ly Sp ecification s 414

Contents

Power Su p p ly Certification s 417 Power-Use Calcu lation s 417 Leave It On or Tu rn It Off?

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Power Man agem en t 423 En ergy Star System s 423 Ad van ced Power Man agem en t Power Su p p ly Problem s

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Power Su p p ly Trou blesh ootin g 426 Digital Mu lti-Meters 428 Sp ecialized Test Eq u ip m en t 430 Rep airin g th e Power Su p p ly

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Obtain in g Rep lacem en t Un its 433 Decid in g on a Power Su p p ly 433 Sou rces for Rep lacem en t Power Su p p lies

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Usin g Power-Protection System s 435 Su rge Su p p ressors (Protectors) 437 Ph on e Lin e Su rge Protectors 438 Lin e Con d ition ers 438 Backu p Power 438 RTC/ NVRAM Batteries

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7 Input Devices 445 Keyboard s 445 Typ es of Keyboard s 445 Com p atibility 453 Nu m Lock 454 Keyboard Tech n ology 454 Keyboard Trou blesh ootin g an d Rep air Referen ce Material 479 Mice

480 Mou se In terface Typ es 482 Mou se Calibration 484 Mou se Trou blesh ootin g 487 Microsoft In telliMou se 490 TrackPoin t II/ III 491 Glid ep oin t 495

Gam e Ad ap ter (Joystick) In terface

8 Video Hardw are

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Mon itors 499 Disp lay Tech n ologies 500 Mon och rom e Versu s Color Th e Righ t Size 504 Mon itor Resolu tion 505 Dot Pitch 506

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In terlaced Versu s Non in terlaced En ergy an d Safety 507 Mon itor Bu yin g Criteria 509

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Vid eo Disp lay Ad ap ters 513 Obsolete Disp lay Ad ap ters 514 VGA Ad ap ters an d Disp lays 517 XGA an d XGA-2 519 Su p er VGA (SVGA) 521 VESA SVGA Stan d ard s 523 Vid eo Ad ap ter Com p on en ts 525 Vid eo Card s for Mu ltim ed ia 535 3D Grap h ics Accelerators 543 Ad ap ter an d Disp lay Trou blesh ootin g

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9 Audio Hardw are 549 Au d io Ad ap ter Ap p lication s 549 Gam es 551 Mu ltim ed ia 551 Sou n d Files 552 MIDI Files 553 Presen tation s 556 Record in g 557 Voice An n otation 558 Voice Recogn ition 559 Con feren cin g 560 Proofread in g 560 Au d io CDs 560 Sou n d Mixer 561 Is an Au d io Ad ap ter Necessary? 561 Au d io Ad ap ter Con cep ts an d Term s Th e Natu re of Sou n d 562 Gam e Stan d ard s 563 Freq u en cy Resp on se 563 Sam p lin g 564 8-Bit Versu s 16-Bit 564

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Au d io Ad ap ter Featu res 565 Con n ectors 565 Volu m e Con trol 567 Syn th esis 568 Data Com p ression 568 Mu lti-Pu rp ose Digital Sign al Processors 569 CD-ROM Con n ectors 569 Sou n d Drivers 570 Ch oosin g an Au d io Ad ap ter 570 Con su m er or Prod u cer? 570 Com p atibility 571 Bu n d led Software 571

Contents

Au d io Ad ap ter In stallation 571 In stallin g th e Sou n d Card 572 Usin g You r Stereo In stead of Sp eakers

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Trou blesh ootin g Sou n d Card Problem s 574 Hard ware (Resou rce) Con flicts 574 Oth er Sou n d Card Problem s 576 Sp eakers

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Microp h on es

10 I/ O Int erfaces

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Serial an d Parallel Ports 583 Serial Ports 583 Testin g Serial Ports 591 Parallel Ports 593 Parallel-Port Con figu ration Testin g Parallel Ports 600

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Serial an d Parallel Port Rep lacem en ts USB (Un iversal Serial Bu s) 601 FireW ire (IEEE 1394) 604

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Storage Device In terfaces 605 Th e ST-506/ 412 In terface 607 Th e ESDI In terface 609 Th e IDE In terface 610 IDE Origin s 612 IDE Bu s Version s 613 ATA IDE 614 Th e ATA Sp ecification 614 ATA IDE Drive Categories 618 ATA-2 an d ATA-3 (En h an ced IDE) ATA-4 625 Obsolete IDE Version s 626

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Sm all Com p u ter System In terface (SCSI) 626 ANSI SCSI stan d ard s 628 Sin gle-en d ed or Differen tial SCSI 630 SCSI-1 an d SCSI-2 631 SCSI-3 633 SCSI Cables an d Con n ectors 634 SCSI Cable an d Con n ector Pin ou ts 634 SCSI Drive Con figu ration 640 Plu g-an d -Play (Pn P) SCSI 644 SCSI Con figu ration Tip s 645 IDE Versu s SCSI 646 SCSI Hard Disk Evolu tion an d Con stru ction 646 Perform an ce 651 SCSI Versu s IDE: Ad van tages an d Lim itation s 652 Recom m en d ed SCSI Host Ad ap ters 653

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11 Com m unicat ions and Net w orking Asyn ch ron ou s Mod em s 656 Mod em Stan d ard s 658 56K Mod em s 667 Mod em Recom m en d ation s

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In tegrated Services Digital Network (ISDN) ISDN Services 671 ISDN Hard ware 672

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Leased Lin es 673 T-1 Con n ection s 673 T-3 Con n ection s 673 CATV Networks 673 Cable Mod em s 674 CATV Ban d wid th 674 CATV Secu rity 675 CATV Perform an ce 675 Direct Cable Con n ection s 676 Nu ll Mod em Cables 676 Direct Con n ect Software 677 Local Area Networks 678 Networkin g Basics 678 LAN Hard ware Com p on en ts 684 Data Lin k Layer Protocols 699 High -Sp eed Networkin g Tech n ologies 100Mbp s Eth ern et 704 Asyn ch ron ou s Tran sfer Mod e 705 Up p er-Layer Protocols 706 TCP/ IP

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12 M agnet ic St orage

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Prin cip les of Magn etic Storage 709 Data En cod in g Sch em es 712 En cod in g Sch em e Com p arison s 716 PRML (Partial-Resp on se, Maxim u m -Likelih ood ) 718 Cap acity Measu rem en ts 718 Hard Disk Drives 719 Defin ition of a Hard Disk 719 Hard Disk Drive Op eration 720 Basic Hard Disk Drive Com p on en ts Hard Disk Featu res 754 Hard Disk In stallation Proced u res 761 Drive Con figu ration 762 Host Ad ap ter Con figu ration 762 Ph ysical In stallation 764 System Con figu ration 765

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Form attin g 767 Hard Disk Drive Trou blesh ootin g an d Rep air

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Flop p y Disk Drives 770 Develop m en t of th e Flop p y Disk Drive 771 Drive Com p on en ts 771 Disk Ph ysical Sp ecification s an d Op eration 778 Typ es of Flop p y Disk Drives 782 An alyzin g Flop p y Disk Con stru ction 787 Drive-In stallation Proced u res 793 Rep airin g Flop p y Disk Drives 793 Rem ovable Storage Drives 796 Typ es of Rem ovable Med ia Drives Magn etic Med ia Drives 797

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Tap e Drives 804 Th e Origin s of Tap e Backu p Stan d ard s 806 Th e QIC Stan d ard s 807 Oth er High -Cap acity Tap e Drive Stan d ard s 812 Ch oosin g a Tap e Backu p Drive 816 Tap e Drive In stallation Issu es 819 Tap e Drive Backu p Software 820

13 Opt ical St orage

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W h at Is CD-ROM? 823 CDs: A Brief History 824 CD-ROM Tech n ology 824 In sid e Data CDs 826 W h at Typ es of Drives Are Available? 828 CD-ROM Drive Sp ecification s 829 In terface 832 Load in g Mech an ism 835 Oth er Drive Featu res 837 CD-ROM Disc an d Drive Form ats 838 Data Stan d ard : ISO 9660 839 High Sierra Form at 839 CD-DA (Digital Au d io) 840 CD-ROM XA or Exten d ed Arch itectu re Mixed -Mod e CDs 843 Ph otoCD 844 W ritable CD-ROM Drives CD-R 847 CD-RW 849

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DVD (Digital Versatile Disc) 851 DVD History 851 DVD Sp ecification s 851 DVD Stan d ard s 853

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In stallin g an Op tical Drive 854 Avoid in g Con flict: Get You r Card s in Ord er 854 Drive Con figu ration 855 Extern al (SCSI) Drive Hook-Up 856 In tern al Drive In stallation 858 Ribbon Cable an d Card Ed ge Con n ector 858 SCSI Ch ain s: In tern al, Extern al, a Little of Both 860 CD-ROM Software on You r PC 862 Software Load in g 865 CD-ROM in Microsoft W in d ows 3.x 866 Op tical Drives in W in d ows 9x an d W in d ows NT 4.0 Trou blesh ootin g CD-ROMs

867

14 Print ers 869 Prin ter Tech n ology 869 Prin t Resolu tion 870 Page Descrip tion Lan gu ages (PDL) Escap e Cod es 877 Prin ter Mem ory 877 Fon ts 878 Prin ter Drivers 881

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How Prin ters W ork 882 Laser Prin ters 882 In kjet Prin ters 887 Dot Matrix Prin ters 889 Color Prin tin g 890 Color In kjet Prin ters 892 Color Laser Prin ters 892 Dye Su blim ation Prin ters 893 Th erm al W ax Tran sfer Prin ters 893 Ch oosin g a Prin ter Typ e 893 How Man y Prin ters? 893 Com bin ation Devices 894 Prin t Sp eed 894 Pap er Typ es 895 Cost of Con su m ables 895 In stallin g Prin ter Su p p ort 896 DOS Drivers 897 W in d ows Drivers 897 Preven tive Main ten an ce 902 Laser an d In kjet Prin ters 902 Dot Matrix Prin ters 902 Ch oosin g th e Best Pap er 903 Com m on Prin tin g Problem s 903 Prin ter Hard ware Problem s 904 Con n ection Problem s 906

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Contents

Driver Problem s 907 Ap p lication Problem s 908

15 Port able PCs 909 Form Factors 909 Lap top s 910 Notebooks 910 Su bn otebooks 910 Portable System Design s

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Up grad in g an d Rep airin g Portables Portable System Hard ware 913 Disp lays 913 Processors 918 Mobile Processor Packagin g Ch ip sets 929 Mem ory 930 Hard Disk Drives 931 Rem ovable Med ia 931 PC Card s 932 Keyboard s 937 Poin tin g Devices 938 Batteries 939

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Perip h erals 942 Extern al Disp lays 942 Dockin g Station s 944 Con n ectivity 945

16 Building or Upgrading Syst em s 947 System Com p on en ts 948 Case an d Power Su p p ly 949 Moth erboard 950 Flop p y Disk an d Rem ovable Drives 961 Hard Disk Drive 962 CD-ROM Drive 963 Keyboard an d Poin tin g Device (Mou se) 964 Vid eo Card an d Disp lay 965 Sou n d Card an d Sp eakers 966 USB Perip h erals 966 Accessories 966 Hard ware an d Software Resou rces 968 System Assem bly an d Disassem bly 968 Assem bly Prep aration 969 Moth erboard In stallation 972 Disassem bly Prep aration 979 Sou rces an d Su p p liers

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17 Diagnost ics, Test ing, and M aint enance 983 Diagn ostics Software 983 Th e Power-On Self Test (POST) 984 Hard ware Diagn ostics 989 Gen eral-Pu rp ose Diagn ostics Program s 991 Op eratin g System Diagn ostics 995 PC Main ten an ce Tools 999 Han d Tools 1000 A W ord Abou t Hard ware 1004 Sold erin g an d Desold erin g Tools Test Eq u ip m en t 1007

1005

Preven tive Main ten an ce 1011 Active Preven tive Main ten an ce Proced u res 1012 Passive Preven tive Main ten an ce Proced u res 1024

18 Operat ing Syst em s Soft w are and Troubleshoot ing 1031 Disk Op eratin g System (DOS) 1031 Op eratin g System Basics 1031 Th e System ROM BIOS 1033 DOS Com p on en ts 1035 IO.SYS (or IBMBIO.COM) 1035 MSDOS.SYS (or IBMDOS.COM) 1036 Th e Sh ell or Com m an d Processor (COMMAND.COM) 1036 DOS Com m an d File Search Proced u re 1037 DOS Version s 1039 Poten tial DOS Up grad e Problem s 1040 Th e Boot Process 1042 How DOS Load s an d Starts 1042 File Man agem en t 1048 In terfacin g to Disk Drives 1049 W in d ows 3.1 1053 16-bit W in d ows Version s 1054 Load in g W in d ows 3.1 1055 Core W in d ows Files 1056 32-bit Disk Access 1057 W in d ows 9x 1058 W in d ows 9x an d DOS Com p ared Version s 1060 W in d ows 9x Arch itectu re 1060 FAT32 1061 W in d ows NT Version s W in d ows W in d ows

1062 1063 NT Startu p 1063 NT Com p on en ts 1063

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19 File Syst em s and Dat a Recovery

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FAT Disk Stru ctu res 1065 Master Partition Boot Sector 1067 Volu m e Boot Sectors 1071 Root Directory 1073 File Allocation Tables (FATs) 1076 Clu sters (Allocation Un its) 1077 Th e Data Area 1079 Diagn ostic Read -an d -W rite Cylin d er VFAT an d Lon g File Nam es

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FAT32 1082 FAT32 Clu ster Sizes 1083 FAT Mirrorin g 1084 Creatin g FAT32 Partition s 1084 Con vertin g FAT16 to FAT32 1085 FAT File System Errors 1086 Lost Clu sters 1086 Cross-Lin ked Files 1087 In valid Files or Directories FAT Errors 1087

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FAT File System Utilities 1088 Th e CHKDSK Com m an d 1088 CHKDSK Op eration 1090 Th e RECOV ER Com m an d 1091 SCANDISK 1091 Disk Defragm en tation 1093 Th ird -Party Program s 1094 NTFS 1095 NTFS Arch itectu re 1096 NTFS Com p atibility 1096 Creatin g NTFS Drives 1097 NTFS Tools 1097

20 IBM Personal Com put er Fam ily Hardw are System -Un it Featu res by Mod el

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An In trod u ction to th e PC (5150) 1101 PC Mod els an d Featu res 1103 PC BIOS Version s 1104 PC Tech n ical Sp ecification s 1105 An In trod u ction to th e PC Con vertible (5140) 1110 PC Con vertible Sp ecification s an d High ligh ts 1112 PC Con vertible Mod els an d Featu res 1113 An In trod u ction to th e XT (5160) 1115 XT Mod els an d Featu res 1117 XT BIOS Version s 1119 XT Tech n ical Sp ecification s 1120

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An In trod u ction to th e Portable PC

1125

An In trod u ction to th e AT 1129 AT Mod els an d Featu res 1132 AT BIOS Version s 1136 AT Tech n ical Sp ecification s 1140 An In trod u ction to th e XT Mod el 286 1145 XT Mod el 286 Mod els an d Featu res 1147 XT Mod el 286 Tech n ical Sp ecification s 1148

21 A Final W ord

1153

Man u als (Docu m en tation ) 1154 Basic System Docu m en tation 1156 Com p on en t an d Perip h eral Docu m en tation 1158 Ch ip an d Ch ip set Docu m en tation 1160 Man u factu rer System -Sp ecific Docu m en tation 1163 Magazin es

1163

On lin e Resou rces Sem in ars

1165

Mach in es

1165

Th e Ap p en d ixes

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Com p TIA A+ Core Exam in ation Objective Map 1167 1.0 In stallation , Con figu ration , an d Up grad in g 1167 2.0 Diagn osin g an d Trou blesh ootin g 1170 3.0 Safety an d Preven tive Main ten an ce 1170 4.0 Moth erboard / Processors/ Mem ory 1171 5.0 Prin ters 1173 6.0 Portable System s 1174 7.0 Basic Networkin g 1174 8.0 Cu stom er Satisfaction 1175 In Con clu sion

A Vendor List

1175

1177

#1-PC Diagn ostics Com p an y (Th e ESD Division of W in d sor Tech n ologies, In c.) 1178 3Com Corp . 1178 3D Labs 1178 3Dfx 1178 3M Data Storage Prod u cts Division 1179 Aavid Th erm al Tech n ologies, In c. 1179 ABIT Com p u ter (USA) Corp oration 1179 Accu rite Tech n ologies, In c. 1179 Acer Am erica Corp . 1179 Acer Laboratories, In c. (ALi) 1179 Acm e Electric/ Electron ics Division 1179 Ad ap tec 1180

Contents

Ad obe System s, In c. 1180 ADP Hollan d er Com p an y 1180 Ad van ced Digital In form ation Corp oration 1180 Ad van ced In tegration Research (AIR) 1180 Ad van ced Logic Research (ALR) 1180 Ad van ced Micro Devices (AMD) 1181 Ad van ced Person al System s 1181 Aeron ics, In c. 1181 AIW A Am erica, In c. Com p u ter System s Division 1181 AllMicro, In c. (Pu rch ased by ForeFron t Direct) 1181 Alloy Com p u ter Prod u cts 1181 ALPS Electric 1181 Altex Electron ics, In c. 1182 Am d ek Corp oration (A Division of W yse Tech n ology) 1182 Am erica On lin e 1182 Am erican Megatren d s, In c. (AMI) 1182 Am erican Nation al Stan d ard s In stitu te (ANSI) 1182 Am erican Power Con version (APC) 1182 AMP, In c. 1182 An d rom ed a Research 1183 An n abooks/ An n asoft System s 1183 An vil Cases 1183 Ap p le Com p u ter, In c. 1183 Arco Com p u ter Prod u cts, In c. 1183 Arrow Electron ic 1183 Arrowfield In tern ation al, In c. 1183 Association of Sh areware Profession als (ASP) 1184 AST Research , In c. 1184 Astec Am erica, In c. 1184 Asu s Com p u ter In tern ation al (ASUStek) 1184 AT&T Nation al Parts Sales Cen ter/ Lu cen t Tech n ologies 1184 ATI Tech n ologies, In c. 1184 Au tod esk, In c. 1184 Au totim e Corp oration 1185 Award Software In tern ation al, In c. 1185 AZ-COM, In c. 1185 Beld en W ire an d Cable 1185 Berksh ire Prod u cts 1185 Best Power (Division of Gen eral Sign al Power) 1185 Bitstream , In c. 1185 Black Box Corp oration 1186 Boca Research , In c. 1186 Borlan d In tern ation al (Now In p rise) 1186 Bose Corp . 1186 Boston Com p u ter Exch an ge 1186 Brooktree Corp oration (Pu rch ased by Rockwell) 1186 Bu erg, Vern on D. 1186

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Byte In form ation Exch an ge (BIX) 1186 Byte Magazine/ McGraw-Hill 1187 Byte Ru n n er Tech n ologies 1187 Cables to Go (CTG) 1187 CAIG Laboratories 1187 Cal-Abco 1187 Can on USA, In c. 1187 Casio, In c. 1187 Cen ton Electron ics, In c. 1187 Ch em tron ics, In c. 1188 Ch erry Electrical Prod u cts 1188 Ch icago Case Com p an y 1188 Ch ilton Book Com p an y 1188 Ch in on Am erica, In c. 1188 Ch ip s an d Tech n ologies, In c. 1188 Ch rysler Motors Service Pu blication s 1188 CI Design Com p an y 1188 CIE Am erica 1189 Cirru s Logic, In c. 1189 Citizen Am erica Corp oration 1189 CMD Tech n ology, In c. 1189 Colorad o Mem ory System s, In c. 1189 Colu m bia Data Prod u cts 1189 Com p aq Com p u ter Corp oration 1189 Com p TIA (Com p u tin g Tech n ology In d u stry Association ) 1189 Com p ton ’s New Med ia, In c. (A Division of Softkey In tern ation al, In c.) 1190 Com p USA, In c. 1190 Com p u Serve In form ation Service (CIS) 1190 Com p u ter Com p on en t Sou rce, In c. 1190 Com puter Design Magazine 1190 Com p u ter Discou n t W areh ou se (CDW ) 1190 Com puter Graphics W orld Magazine 1190 Com puter Hotline Magazine 1191 Com p u ter Library 1191 Com puter Reseller News 1191 Com puter Retail W eek Magazine 1191 Com puter Shopper Magazine 1191 Com puter Technology Review Magazine 1191 Com tech Pu blish in g Ltd . 1191 Con n ector Resou rces Un lim ited (CRU) 1192 Con n er Perip h erals, In c. 1192 Corel System s, In c. 1192 Creative Labs, In c. 1192 CS Electron ics 1192 CST 1192 CTX In tern ation al, In c. 1192

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Cu rtis Com p u ter Prod u cts 1193 CyberMed ia 1193 Cyp ress Sem icon d u ctor Corp oration 1193 Cyrix Corp oration 1193 D.W . Electroch em icals, Ltd . 1193 DakTech 1193 Da-Lite Screen Co. 1193 Dallas Sem icon d u ctor 1193 Dam ark In tern ation al, In c. 1194 Darkh orse System s, In c. 1194 Data Base Advisor Magazine 1194 Data Com m unications Magazine 1194 Data Dep ot 1194 Data Exch an ge Corp oration 1194 Data Retrieval Services, In c. 1195 Data Tech n ology Corp oration (DTC) 1195 Datastorm Tech n ologies, In c. (Pu rch ased by Qu arterd eck Corp oration ) 1195 Dell Com p u ter Corp oration 1195 DiagSoft, In c. 1195 Diam on d Flower, In c. (DFI) 1195 Diam on d Mu ltim ed ia System s, In c. 1196 Digi-Key Corp oration 1196 Distribu ted Processin g Tech . (DPT) 1196 Diversified Tech n ology 1196 Dolch Com p u ter System s 1196 DTK Com p u ter, In c. 1196 Du kan e Corp oration 1196 Du racell, In c. 1197 Ed m u n d Scien tific 1197 Electrocu tion 1197 Electronic Buyers’ News 1197 Electronic Engineering Tim es Magazine 1197 Electronic Products Magazine 1197 Electroservice Laboratories 1197 Elitegrou p Com p u ter System s, In c. 1198 En d l Pu blication s 1198 Ep son Am erica, In c. (OEM Division ) 1198 Everex System s, In c. 1198 Exabyte Corp oration 1198 Extron Electron ics 1198 Fan tasy Prod u ction s (A Division of Fortn er & Associates) 1198 FCI Electron ics - Am erica 1199 Fed co Electron ics, In c. 1199 Fessen d en Tech n ologies 1199 First In tern ation al Com p u ter, In c. (FIC) 1199 Flu ke, Joh n Man u factu rin g Com p an y, In c. 1199

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Folio Corp oration 1199 ForeFron t Direct 1199 Fu jitsu Com p u ter Prod u cts of Am erica, In c. 1200 Fu tu re Dom ain Corp oration (Pu rch ased by Ad ap tec) 1200 Gateway 2000 1200 Gazelle/ GTM Software 1200 Giga-Byte Tech n ology Co., Ltd . 1200 GigaTren d , In c. 1200 Global En gin eerin g Docu m en ts 1200 Globe Man u factu rin g, In c. 1201 Gold en Bow System s 1201 Gold Star Tech n ology, In c. 1201 GRACE Sp ecialty Polym ers/ W R GRACE, Em erson & Cu m in g, In c. 1201 GSI, In c. 1201 Hau p p au ge Com p u ter W orks, In c. 1201 Hayes Microcom p u ter Prod u cts 1201 Heath kit Ed u cation System s 1202 Helm , In c. 1202 Hewlett-Packard Com p an y 1202 Hewlett-Packard (Disk Mem ory Division ) 1202 Hewlett-Packard (Storage Division ) 1202 Hitach i Am erica, Ltd . (Sem icon d u ctor & IC Division ) 1202 Hyp ertech 1202 Hyu n d ai Electron ics Am erica 1203 IBM Fu llfilm en t Cen ter 1203 IBM Microelectron ics 1203 IBM Nation al Pu blication s 1203 IBM OEM Division 1203 IBM Parts Ord er Cen ter 1203 IBM PC Com p an y 1203 IBM PC Direct 1203 IBM Personal System s Technical Solutions Magazin e 1204 Illin ois Lock 1204 In form ation Access Com p an y 1204 InfoW orld Magazin e 1204 In lin e, In c. 1204 In n erworks Tech n ology, In c. 1204 In tegrated Device Tech n ology, In c. 1204 In tel Corp oration 1204 In tel PC an d LAN En h an cem en t Prod u ct Division 1205 In tern ation al Electron ic Research Corp . (IERC) 1205 Iom ega Corp oration 1205 IX Micro Solu tion s, In c. 1205 J. Bon d Com p u ter System s 1205 Jam eco Com p u ter Prod u cts 1205 JC W h itn ey & Com p an y 1205 JDR Microd evices 1205

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Jen sen Tools, In c. 1206 JTS Corp oration 1206 JVC In form ation Prod u cts 1206 Ken sin gton Tech n ology Grou p 1206 Key Tron ic Corp oration 1206 Kin gston Tech n ology Corp oration 1206 Labcon co Corp oration 1206 Labtec En terp rises, In c. 1206 Lan tron ix 1207 Laser Magn etic Storage 1207 Learn Key, In c. 1207 Lexm ark 1207 Libi In d u stries, Ltd . 1207 Liebert 1207 Liu ski In tern ation al 1207 Lon gsh in e Microsystem s, In c. 1207 Lotu s Develop m en t Corp oration (A Division of IBM) LSI Logic, In c. 1208 Ma Laboratories, In c. 1208 Macworld Com m u n ication s, In c. 1208 MAG In n oVision 1208 MAGNI System s, In c. 1208 Map In fo Corp oration 1208 Matrox Grap h ics, In c. 1208 Maxell Corp oration of Am erica 1209 Maxi Switch , In c. 1209 Maxop tix Corp oration 1209 Maxtor Corp oration 1209 McAfee Associates 1209 McKen zie Tech n ology 1209 Megah ertz Corp oration (A Division of 3Com ) 1209 Merisel 1210 Meritec 1210 Merritt Com p u ter Prod u cts, In c. 1210 Meth od e Electron ics, In c. 1210 Micro 2000, In c. 1210 Micro Accessories, In c. 1210 Micro Ch an n el Develop ers Association 1210 Micro Com p u ter Cable Com p an y, In c. 1211 Micro Design In tern ation al (MDI) 1211 Micro Firm ware, In c. 1211 Micro Hou se In tern ation al 1211 Micro In d u stries Corp oration 1211 Micro Solu tion s, In c. 1211 Micro Solu tion s, In c. 1212 Micro W areh ou se 1212 Microcom , In c. 1212 MicroData Corp oration 1212

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Micrografx, In c. 1212 Micron Tech n ologies (Paren t Com p an y of Micron Electron ics an d Micron Cu stom Man u factu rin g) 1212 Micron ics Com p u ters, In c. 1212 Microp olis Corp oration 1213 Microp rocessors Un lim ited , In c. 1213 Microsoft Corp oration 1213 Micro-Star In tern ation al 1213 MicroSystem s Develop m en t, In c. 1213 Microtest En terp rises 1213 MicroW ay, In c. 1213 Min i Micro Su p p ly 1214 Mitsu bish i Com p u ters, Ltd . 1214 Mitsu bish i Electron ics Am erica, In c. 1214 Mitsu m i Electron ics Corp oration 1214 Molex, In c. 1214 Mosel Vitelic 1214 Motor Magazine 1214 Motorola, In c. 1215 Mou n tain Network Solu tion s, In c. (Su bsid iary of NCE Star Solu tion s) 1215 Mu eller Tech n ical Research 1215 Mu stan g Software 1215 Mylex Corp oration 1215 Myod a Com p u ter Cen ters 1215 Nation al Sem icon d u ctor Corp oration 1215 NCR Microelectron ics 1216 NEC Electron ics, In c. 1216 NEC Tech n ologies, In c. 1216 Newark Electron ics 1216 NexGen , In c. (A Division of AMD) 1216 Novell, In c. 1216 Nu m ber Nin e Visu al Tech n ology Corp oration 1216 n Vid ia Corp oration 1217 Oak Tech n ology, In c. 1217 Ocean In form ation System s 1217 OEM Magazine 1217 Okid ata 1217 Olivetti 1217 On track Data In tern ation al, In c. (Form erly On track Com p u ter System s) 1217 Op ti, In c. 1217 Orch id Tech n ology (A Division of Micron ics) 1218 Pacific Data Prod u cts 1218 Packard Bell 1218 Palo Alto Design Grou p 1218 Pan ason ic Com m u n ication s & System s 1218 Pan ason ic In d u strial Co. 1218

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Parallel Tech n ologies, In c. 1218 PARTS NOW !, In c. 1219 PC & MAC Con n ection 1219 PC Magazine 1219 PC Portable Man u factu rer, In c. 1219 PC Power & Coolin g, In c. 1219 PC W eek Magazin e 1219 PC W orld Magazin e 1219 PCI Sp ecial In terest Grou p 1220 PCMCIA—Person al Com p u ter Mem ory Card In tern ation al Association 1220 Ph ilip s Con su m er Electron ics 1220 Ph oen ix Tech n ologies, Ltd . 1220 Pivar Com p u tin g Services, In c. 1220 PKW are, In c. 1220 Plextor 1221 PlugIn Datam ation 1221 PowerQu est Corp oration 1221 Practical En h an ced Logic 1221 Precision Plastics 1221 Processor Magazine 1221 Pu blic Software Library 1221 Qlogic Corp oration 1222 Qu alitas, In c. 1222 Qu an tu m Corp oration 1222 Qu arterd eck Corp oration 1222 Qu arter-In ch Cartrid ge Drive Stan d ard s, In c. (QIC) 1222 Qu e Corp oration 1222 Rad io Sh ack (A Division of Tan d y Corp oration ) 1222 Ram tron In tern ation al Corp oration 1223 Ran ch o Tech n ology, In c. 1223 Ren d ition 1223 Rip -Tie Com p an y 1223 Rockwell Sem icon d u ctor System s 1223 Rolan d Corp oration U.S. 1223 Rosen th al En gin eerin g 1223 Ru p p Tech n ology Corp oration (Retail Location s – Mobilscap e) 1224 S3, In c. 1224 Safeware In su ran ce Agen cy, In c. 1224 Sam s 1224 Sam su n g Sem icon d u ctor, In c. 1224 Seagate Software 1224 Seagate Software Storage Man agem en t Grou p (Form erly Sytron ) 1224 Seagate Tech n ology 1225 Sen core 1225 Service News Magazin e 1225

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SGS-Th om son Microelectron ics, In c. 1225 Sh arp Electron ics Corp oration 1225 Sh arp Microelectron ics Grou p 1225 Sigm a Data 1226 Silicon In tegrated System s Corp . (SiS) 1226 Silicon Valley Research 1226 Sim p le Tech n ology 1226 SL W aber 1226 Sm art Cable In c. 1226 SofTou ch System s, In c. 1226 Sola Heavy Du ty Electric (Acq u ired by Best Power, a Division of Gen eral Sign al Power) 1227 SONERA Tech n ologies 1227 Son y Corp oration of Am erica 1227 SOYO Tek, In c. 1227 Sp ecialized Prod u cts Com p an y 1227 Sp ragu e Magn etics, In c. 1227 Stac In corp orated 1227 Stan d ard Microsystem s Corp oration (SMSC) 1228 SMC Networks, In c. (Form erly a Division W ith in Stan d ard Microsystem s Corp .) 1228 Star Micron ics Am erica, In c. 1228 STB System s, In c. 1228 Storage Dim en sion s, In c. 1228 Su n Moon Star 1228 Su p erm icro Com p u ter, In c. 1228 Su p erp ower Su p p ly, In c. 1228 Sym an tec Corp oration 1229 SyQu est Tech n ology 1229 Tad iran 1229 Tan d y Corp oration 1229 Tatu n g Com p an y of Am erica, In c. 1229 TDK Corp oration of Am erica 1229 Teac Am erica, In c. 1229 Tech Data Corp oration 1230 Tech Sp ray, In c. 1230 Tecm ar Tech n ologies, In c. 1230 Tekram Tech n ologies 1230 Test and Measurem ent W orld Magazin e 1230 Texas In stru m en ts, In c. 1230 Th e Learn in g Com p an y 1230 Th erm alloy, In c. 1231 Tosh iba Am erica, In c. 1231 Tou ch Ston e Software Corp oration 1231 Trace Research an d Develop m en t Cen ter 1231 Travelin g Software, In c. 1231 Trid en t Microsystem s 1231 Trin iTech , In c. 1232

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Trip p Lite Man u factu rin g 1232 TTI Tech n ologies 1232 Twin h ead Corp oration 1232 Tyan Com p u ter Corp oration 1232 Ultra-X, In c. 1232 Un d erwriters Laboratories, In c. 1232 Un icom p , In c. 1233 Un icore Software, In c. 1233 UNISYS 1233 U.S. Robotics, In c. (Merged with 3Com ) 1233 V Com m u n ication s, In c. 1233 Varta Batteries, In c. 1233 Verbatim Corp oration 1233 VESA Stan d ard s 1234 VIA Tech n ologies, In c. 1234 ViewSon ic 1234 Visiflex Seals 1234 VLSI Tech n ology, In c. 1234 Volp e, Han k 1234 W allin g Com p an y 1234 W an g Laboratories, In c. 1234 W atergate Software 1235 W ave Tech 1235 W estern Digital Corp oration 1235 W in bon d (Form erly Sym p h on y Laboratories) 1235 W ord Perfect (A Division of Corel Software) 1235 W yse Tech n ology 1235 Xerox Corp oration 1235 Xircom 1235 Y-E Data Am erica, In c. 1236 ZD Com d ex an d Foru m s 1236 Zen ith Data System s 1236 Zeos In tern ation al, Ltd . (Pu rch ased by Micron Electron ics) 1236 Ven d ors by Prod u ct or Service Category 1236 Au d io Ad ap ters (Sou n d Card s) 1236 Batteries 1236 BIOS 1236 Books, Magazin es, Docu m en tation 1236 Cables an d Con n ectors 1237 Cases 1237 CD-ROM Drives an d Med ia 1237 Ch ip sets 1237 Diagn ostics Software an d Hard ware 1238 Distribu tors 1238 Flop p y Drives 1238 Grap h ics Ad ap ters 1239

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Hard Disk Drives an d Drive Con trollers 1239 Hard ware (Screws, Mou n tin g Brackets, an d So On ) 1239 Keyboard s 1240 Mem ory 1240 Mice 1240 Miscellan eou s 1240 Mod em s 1241 Mon itors an d Disp lay Devices 1241 Moth erboard s 1241 Networkin g 1242 On lin e Services 1242 Op tical Drives an d Med ia 1242 Power Protection an d UPS 1242 Power Su p p lies 1242 Prin ters, Prin ter Parts, an d Su p p lies 1242 Processors an d Processor Up grad es 1243 RAID 1243 Rem ovable Med ia 1243 Rep air Services 1243 Retail an d Direct Mail 1243 SCSI Accessories 1243 Software 1243 Sp eakers 1244 Stan d ard s Bod ies an d Organ ization s 1244 Su p p lies (Ch em icals, Clean ers, an d So On ) 1244 System s (Desktop , Server, an d Mobile) 1244 Tap e Drives an d Med ia 1245

B Useful Hardw are W eb Sit es 1247 C Glossary 1251 D Technical Reference

1325

Gen eral In form ation 1325 ASCII Ch aracter Cod e Ch arts 1325 Hexad ecim al/ ASCII Con version s 1326 EBCDIC Ch aracter Cod es 1334 Metric System (SI) Prefixes 1341 U.S.—Metric Un its of Len gth Con version s Powers of 2 1342 Electrom agn etic Sp ectru m 1343 Mod em Con trol Cod es

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Hard Disk Drives 1352 Hard Drive Param eters 1353 ROM BIOS Hard Drive Param eters 1405

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DOS Com m an d Referen ce 1413 DOS Com m an d s Fou n d in DOS 6.22, W in d ows 95, an d W in d ows 98 1413 DOS 6.22 Com m an d s Not In stalled by W in d ows 95/ 98 bu t Available on th e CD-ROM 1416 DOS 6.22 Com m an d s Not Available in W in d ows 95 or W in d ows 98 1417

List of Acronym s 1419 Index of M anufact urers 1425 Index

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To m y wife Lynn: W ow! It’s been 10 years for us and for this book… Happy Anniversary!

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About the Author Sc o t t Mu e l l e r is p resid en t of Mu eller Tech n ical Research , an in tern ation al p erson al com p u ter research an d corp orate train in g firm . Sin ce 1982, MTR h as sp ecialized in th e in d u stry’s lon gest ru n n in g, m ost in -d ep th , accu rate, an d effective corp orate tech n ical train in g sem in ars, m ain tain in g a clien t list th at in clu d es Fortu n e 500 com p an ies, U.S. an d foreign govern m en ts, m ajor software an d h ard ware corp oration s, an d PC en th u siasts an d en trep ren eu rs. His sem in ars h ave been p resen ted to th ou san d s of PC p rofession als th rou gh ou t th e world . Scott Mu eller h as d evelop ed an d p resen ted p erson al com p u ter train in g cou rses in all areas of PC h ard ware an d software. He is an exp ert in PC h ard ware, op eratin g system s, d ata-recovery tech n iq u es, an d local area n etworks. For m ore in form ation abou t a cu stom com p u ter train in g sem in ar for you r organ ization , con tact: Mu eller Tech n ical Research 21 Sp rin g Lan e Barrin gton Hills, IL 60010 Ph on e: (847) 854-6794 Fax: (847) 854-6795 In tern et: sc o t t m u e l l e r@c o m p u se rv e .c o m W eb: w w w .m -t r.c o m Scott h as m an y p op u lar books, articles, an d cou rse m aterials to h is cred it, in clu d in g Upgrading and Repairing PCs, wh ich h as sold m ore th an 1.5 m illion cop ies, m akin g it by far th e m ost p op u lar PC h ard ware book on th e m arket. His two-h ou r vid eo titled “Your PC— The Inside Story” is available th rou gh Learn Key, In c. For ord erin g in form ation , con tact: Learn Key, In c. 1845 W est Su n set Bou levard St. George, UT 84770 Toll Free: (800) 937-3279 Ph on e: (801) 674-9733 Fax: (801) 674-9734

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If you h ave q u estion s abou t PC h ard ware, su ggestion s for th e n ext version of th is book, or an y com m en ts in gen eral, sen d th em to Scott via e-m ail at sc o t t m u e l l e r@c o m p u se rv e .c o m . Corresp on d en ce th rou gh stan d ard m ail takes h im m u ch lon ger to an swer! W h en h e is n ot workin g on PC-related books or teach in g sem in ars, Scott can u su ally be fou n d in th e garage workin g on h is LT4-p owered 1994 Im p ala SS, LT4-p owered 1995 Cap rice 9C1 (p olice p ackage), or Bu ick Tu rbo V6-p owered 1989 Tran s Am , as well as variou s oth er p erform an ce car-related p rojects. He can also be fou n d testin g th e veh icles at th e local d rag strip , or sh owin g th em off at car sh ows or th e local cru ise/ d rive-in scen e. About the Contributing Author: Cra i g Za c k e r is a writer an d ed itor an d h as worked as an ad m in istrator of Novell NetW are n etworks an d as a PC su p p ort tech n ician wh ile op eratin g a freelan ce d esktop p u blish in g bu sin ess. Craig worked exten sively on th e in tegration of W in d ows NT in to existin g NetW are in tern etworks, an d was em p loyed as a tech n ical writer, con ten t p rovid er, an d W ebm aster for th e on lin e services grou p of a large software com p an y. Craig h as au th ored or con tribu ted to m an y books on op eratin g system s an d n etworkin g top ics, an d h as p u blish ed articles in top in d u stry p u blication s in clu d in g W indows NT Magazine, for wh ich h e is a con tribu tin g ed itor. He can be con tacted th rou gh h is W eb site at h t t p :/ / w w w .z a c k e r.c o m , or at c ra i g @z a c k e r.c o m . Qu e an d Scott wou ld like to th an k Craig for u p d atin g several ch ap ters for th is ed ition , an d for writin g Ch ap ter 14, “Prin ters.”

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Acknowledgments Th is Tenth Anniversary Edition is th e p rod u ct of a great d eal of ad d ition al research an d d evelop m en t over th e p reviou s ed ition s. Several p eop le h ave h elp ed m e with both th e research an d p rod u ction of th is book. I wou ld like to th an k th e followin g p eop le: First, a very sp ecial th an ks to m y wife an d p artn er, Lyn n . Th is book con tin u es to be an in cred ible bu rd en on both ou r bu sin ess an d fam ily life, an d sh e h as p u t u p with a lot! Lyn n is excellen t at d ealin g with th e m an y com p an ies we h ave to con tact for p rod u ct in form ation an d research . Sh e is th e backbon e of MTR. Th an ks to Lisa Carlson of Mu eller Tech n ical Research for h elp in g with p rod u ct research an d office m an agem en t. Sh e h as fan tastic organ ization al skills th at h ave been a trem en d ou s h elp in m an agin g all th e in form ation th at com es in to an d goes ou t of th is office. Th an ks to Joh n Rou rke, wh o n ot on ly teach es m an y of th e MTR sem in ars, bu t is also th e d esign er an d creator of th e Discovery card —wh ich is th e first card on th e m arket for trou blesh ootin g IRQ an d DMA con flicts. Th an ks to all th e com p an ies wh o h ave p rovid ed h ard ware, software, an d research in form ation th at h as been h elp fu l in d evelop in g th is book. Th an ks to David Mean s for feed back from th e tren ch es abou t variou s p rod u cts an d esp ecially d ata-recovery in form ation . Th an ks to Seth W alker at In tel for all h is assistan ce. I wou ld like to offer a sp ecial th an ks to th e p eop le at Qu e wh o h ave m ad e th is book p ossible. Th an ks also to all th e ed itors an d staff wh o work so h ard to get th ese books ou t! Th an ks to all th e read ers wh o h ave e-m ailed m e with su ggestion s con cern in g th is book; I welcom e all you r com m en ts. A sp ecial th an ks to Pau l Reid wh o always h as m an y su ggestion s to offer for im p rovin g th e book an d m akin g it m ore accu rate.

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Fin ally, I wou ld like to th an k th e m ore th an ten th ou san d p eop le wh o h ave atten d ed m y sem in ars; you m ay n ot realize h ow m u ch I learn from each of you an d you r q u estion s! Th an ks also to th ose of you on th e In tern et an d Com p u Serve foru m s with both q u estion s an d an swers, from wh ich I h ave also learn ed a great d eal. Scott Mueller, July 1998

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About t he Technical Review ers Ke n t Ea sl e y is a lectu rer in com p u ter scien ce an d m ath em atics at Su l Ross State Un iversity. He teach es in trod u ctory com p u ter scien ce, n etworkin g, an d p rogram m in g with Visu al Basic. Ken t is th e n etwork ad m in istrator for th e d ep artm en t’s W in d ows NT n etwork. He also teach es m ath em atics. Ken t h as two Masters’ d egrees: Library an d In form ation Scien ce, an d Math em atics an d Com p u ter Scien ce. He h as exp erien ce as a referen ce an d system s librarian . Ken t began teach in g at Su l Ross in 1996 after earn in g h is secon d Master’s d egree in Com p u ter Scien ce an d Math em atics. He is also a Microsoft Certified Profession al. Ty so n H e y n is m an ager of p rod u ct an d tech n ology com m u n ication s for Seagate Tech n ology, In c. He d ed icates m ost of h is tim e to h igh -en d storage p rod u cts an d tech n ologies, in clu d in g Seagate’s Ch eetah an d Barracu d a d isc d rives. Prior to Seagate, Tyson served with in an in d u stry sales fu n ction an d freelan ced h is writin gs. A resid en t of San ta Cru z, CA, an d based at th e com p an y’s Scotts Valley h ead q u arters, Heyn h as an exten sive h istory with p erson al com p u tin g, an d with p u blish ed in d u stry works d atin g back as far as 1989. He h as stu d ied Com p u ter En gin eerin g an d Bu sin ess Econ om ics at Un iversity of Californ ia, San ta Cru z, an d Ch u rch Lead ersh ip at Beth an y Bible College. He can be con tacted at t y so n h e y n @a o l .c o m . D o u g Kl i p p e rt is an in d ep en d en t con tract train er livin g in Tacom a, W ash in gton . He is a Microsoft Certified Solu tion s En gin eer an d an exp ert Microsoft Office User Sp ecialist in W ord 97, Excel 97, an d PowerPoin t 97. Dou g is th e Cred it Man ager for a Pu blic Utility an d h as a B.A. in Accou n tin g an d an MBA. Ca rl La rso n is a p rod u ct lin e m an ager for th e P6 fam ily of m icrop rocessors in In tel’s Mircrop rocessor Prod u cts Grou p . Carl join ed In tel in 1990n as th e Prod u ct Marketin g En gin eer for th e In tel386 DX m icrop rocessor. Sin ce th en Larson h as h eld a variety of p rod u ct m arketin g p osition s, in clu d in g p erform an ce m arketin g, p ricin g an d d em an d forecastin g, an d In tel 486 fam ily p rod u ct m an agem en t. In 1994 Carl becam e th e m an ager of In tel’s p ricin g d ep artm en t. Sin ce 1996 Carl h as been a p rod u ct lin e m an ager for th e P6 fam ily of m icrop rocessors in clu d in g th e Pen tiu m II Xeon , Pen tiu m II, an d

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Celeron p rocessors. Larson grad u ated from th e Un iversity of Illin ois in 1985 with a B.S. in Electrical En gin eerin g an d received a Master of Man agem en t d egree from th e Kellogg Sch ool of Man agem en t at North western Un iversity. P e t e Le n g e s is a Tech n ical Software In stru ctor for New Horizon s Com p u ter Learn in g Cen ters, on e of th e world ’s largest software train in g in tegrators. He is an A+ Certified Tech n ician with a sp ecialty in Microsoft Op eratin g System s as well as an MCT (Microsoft Certified Train er) an d MCP (Microsoft Certified Profession al). He cu rren tly con d u cts both h ard ware an d software classes at th e In d ian ap olis facility an d also assists in th e everyd ay m an agem en t of h is com p an y’s LAN/ W AN. Jo h n P . Ro u rk e is p resid en t of Allied Com p u ter Prod u cts, In c., a m an u factu rer of com p u ter d iagn ostic h ard ware an d software, an d also serves on th e board of d irectors of several oth er PC tech n ology com p an ies. W ith over 18 years in th e PC in d u stry, h e cu rren tly travels across North Am erica an d Eu rop e givin g sem in ars in PC trou blesh ootin g, d ata recovery, an d in tern etworkin g. He is also in volved with writin g an d d eliverin g cou rsework in A+ Certification an d ISO-9000 cu rricu la. Joh n can be reach ed via e-m ail at jo h n @a l l i e d -c o m p u t e r.c o m . Je f f Sl o a n m an ages th e BIOS for Dim en sion d esktop lin e of bu sin ess for Dell Com p u ters. Prior to h is m ove to Dell, h e worked at IBM for 15 1/ 2 years. He sp en t eigh t of th ose 15 years in PS/ 2 BIOS d evelop m en t an d p roblem d eterm in ation swat team . Jeff h as a BS in com p u ter scien ce from th e Un iversity of Pittsbu rgh in 1979. Jeff is cu rren tly workin g on an MS d egree in com p u ter scien ce at Sou th west Texas State Un iversity. Jeff h as tech n ically ed ited fou r MCP books, in clu d in g two Peter Norton h ard ware books.

Contents

Tell Us W hat You Think! As th e read er of th is book, you are ou r m ost im p ortan t critic an d com m en tator. W e valu e you r op in ion an d wan t to kn ow wh at we’re d oin g righ t, wh at we cou ld d o better, wh at areas you ’d like to see u s p u blish in , an d an y oth er word s of wisd om you ’re willin g to p ass ou r way. As th e Execu tive Ed itor for th e Gen eral Desktop Ap p lication s team at Macm illan Com p u ter Pu blish in g, I welcom e you r com m en ts. You can fax, e-m ail, or write m e d irectly to let m e kn ow wh at you d id or d id n ’t like abou t th is book—as well as wh at we can d o to m ake ou r books stron ger. W e are also very in terested in an y feed back you can p rovid e th rou gh th e su rvey at th e en d of th is book. W hile I cannot help you with technical problem s related to the topics covered in this book, Scott Mueller welcom es your technical questions. The best way to reach him is by em ail at s co t t m u eller @co m p u s er ve.co m . W h en you write, p lease be su re to in clu d e th is book’s title an d au th or as well as you r n am e an d p h on e or fax n u m ber. I will carefu lly review you r com m en ts an d sh are th em with th e au th or an d ed itors wh o worked on th e book. Fax:

317-817-7070

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h a rd w a re @m c p .c o m

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Gen eral Desktop Ap p lication s Macm illan Com p u ter Pu blish in g 201 W est 103rd Street In d ian ap olis, IN 46290 USA

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Introduction

Introduction W elcom e to Upgrading and Repairing PCs, Tenth Anniversary Edition. Th is book is for p eop le wh o wan t to u p grad e, rep air, m ain tain , an d trou blesh oot com p u ters. It covers th e fu ll ran ge of PC-com p atible system s from th e old est 8-bit m ach in es to th e latest in h igh en d 64-bit workstation s. In ad d ition , th is book covers state-of-th e-art h ard ware an d accessories th at m ake th e m ost m od ern p erson al com p u ters easier, faster, an d m ore p rod u ctive to u se. Hard ware coverage in clu d es all th e In tel an d In tel-com p atible p rocessors th rou gh th e Pen tiu m , Pen tiu m Pro, an d Pen tiu m II CPU ch ip s; n ew cach e an d m ain m em ory tech n ology; PCI local bu s tech n ology; CD-ROM d rives; tap e backu p s; sou n d board s; PC-Card an d Card bu s d evices for lap top s; IDE an d SCSI-in terface d evices; larger an d faster h ard d rives; an d n ew vid eo ad ap ter an d d isp lay cap abilities. Th e com p reh en sive coverage of th e PC-com p atible p erson al com p u ter in th is book h as con sisten tly won acclaim sin ce d ebu tin g as th e first book of its kin d on th e m arket in 1988. Now with th e release of th is Ten th An n iversary Ed ition , Upgrading and Repairing PCs con tin u es its p lace as n ot on ly th e best-sellin g book of its typ e, bu t also th e m ost com p reh en sive an d easily u sed referen ce on even th e m ost m od ern system —th ose based on cu ttin g-ed ge h ard ware an d software. Th e book exam in es PCs in d ep th , ou tlin es th e d ifferen ces am on g th em , an d p resen ts op tion s for con figu rin g each system at th e tim e you p u rch ase it. Section s of th is book p rovid e d etailed in form ation abou t each in tern al com p on en t of a p erson al com p u ter system , from th e p rocessor to th e keyboard an d vid eo d isp lay. Th is book exam in es th e op tion s available in m od ern , h igh -p erform an ce PC con figu ration s, an d h ow to u se th em to you r ad van tage; it focu ses on m u ch of th e h ard ware an d software available tod ay an d sp ecifies th e op tim u m con figu ration s for ach ievin g m axim u m ben efit for th e tim e an d m on ey you sp en d . At a glan ce, h ere are th e m ajor system com p on en ts an d p erip h erals covered in th is ed ition of Upgrading and Repairing PCs: ■ Pen tiu m II, Pen tiu m Pro, Pen tiu m , 486, an d earlier cen tral p rocessin g u n it (CPU) ch ip s an d “clon e” p rocessors from AMD, Cyrix, an d oth er ven d ors. ■ Th e latest p rocessor u p grad e socket an d slot sp ecification s. ■ New m oth erboard d esign s, in clu d in g th e ATX an d NLX form factors. ■ Th e latest ch ip sets for cu rren t p rocessor fam ilies.

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■ Sp ecial bu s arch itectu res an d d evices, in clu d in g h igh -sp eed PCI (Perip h eral Com p on en t In tercon n ect), AGP (Accelerated Grap h ics Port), an d th e 100MHz p rocessor bu s. ■ Bu s resou rces th at often con flict su ch as In terru p t ReQu est (IRQ) lin es, Direct Mem ory Access (DMA) ch an n els, an d In p u t Ou tp u t (I/ O) p ort ad d resses. ■ Plu g-an d -Play arch itectu re. ■ Larger, faster h ard d rives an d h ard d rive in terfaces an d tech n ologies, in clu d in g n ew IDE sp ecification s su ch as ATA-3 an d ATA-4 an d th e latest on all th e variation s of SCSI. ■ Flop p y d rives an d oth er rem ovable storage d evices su ch as Zip an d LS-120 d rives, tap e d rives, an d record able CDs. ■ In creasin g system m em ory cap acity with SIMM an d DIMM m od u les an d in creasin g system reliability with ECC RAM. ■ New typ es of m em ory, in clu d in g Syn ch ron ou s Pip elin e Bu rst cach e, EDO RAM, Bu rst EDO, Syn ch ron ou s DRAM, an d RAMBUS. ■ Large-screen Su p er VGA m on itors, h igh -sp eed grap h ics ad ap ters, an d 3D grap h ics accelerators. ■ Perip h eral d evices su ch as sou n d card s, m od em s, DVD d rives, an d n etwork in terface card s. ■ PC-Card an d Card bu s d evices for lap top s. ■ Laser an d d ot m atrix p rin ter featu res, m ain ten an ce, an d rep air. ■ How all th ese com p on en ts in teract with tod ay’s p op u lar op eratin g system s. Th is book also sh ows you h ow to trou blesh oot th e kin d of h ard ware p roblem s th at can m ake PC u p grad in g an d rep airin g d ifficu lt. Trou blesh ootin g coverage in clu d es IRQ , DMA ch an n el, an d I/ O p ort ad d ressees, as well as m em ory ad d ress con flicts. Th is book tells you h ow to avoid p roblem s with th ese system resou rces, an d h ow to m ake in stallin g a n ew ad ap ter board in you r com p u ter a sim p le Plu g-an d -Play op eration . Th is book also focu ses on software p roblem s, startin g with th e basics of h ow DOS or W in d ows works with you r system h ard ware to start u p you r system . You also learn h ow to trou blesh oot an d avoid p roblem s in volvin g system h ard ware, th e op eratin g system , an d ap p lication s software. Th is book is th e resu lt of years of research an d d evelop m en t in th e p rod u ction of m y PC h ard ware, op eratin g system , an d d ata recovery sem in ars. Sin ce 1982, I h ave p erson ally tau gh t (an d still teach ) th ou san d s of p eop le abou t PC trou blesh ootin g, u p grad in g, m ain ten an ce, rep air, an d d ata recovery. Th is book rep resen ts th e cu lm in ation of m an y years of field exp erien ce an d kn owled ge cu lled from th e exp erien ces of th ou san d s of oth ers. W h at origin ally started ou t as a sim p le cou rse workbook h as over th e years grown in to a com p lete referen ce on th e su bject. Now you can ben efit from th is exp erien ce an d research .

Introduction

W hat Are t he M ain Object ives of This Book? Upgrading and Repairing PCs focu ses on several objectives. Th e p rim ary objective is to h elp you learn h ow to m ain tain , u p grad e, an d rep air you r PC system . To th at en d , Upgrading and Repairing PCs h elp s you fu lly u n d erstan d th e fam ily of com p u ters th at h as grown from th e origin al IBM PC, in clu d in g all PC-com p atible system s. Th is book d iscu sses all areas of system im p rovem en t su ch as flop p y d isks, h ard d isks, cen tral p rocessin g u n its, an d p ower-su p p ly im p rovem en ts. Th e book d iscu sses p rop er system an d com p on en t care; it sp ecifies th e m ost failu re-p ron e item s in d ifferen t PC system s, an d tells you h ow to locate an d id en tify a failin g com p on en t. You ’ll learn abou t p owerfu l d iagn ostics h ard ware an d software th at en able a system to h elp you d eterm in e th e cau se of a p roblem an d h ow to rep air it. Th e PC-com p atible m icrocom p u ter fam ily is m ovin g forward rap id ly in p ower an d cap abilities. Processor p erform an ce in creases with every n ew ch ip d esign . Upgrading and Repairing PCs h elp s you gain an u n d erstan d in g of each of th e CPU ch ip s u sed in PC-com p atible com p u ter system s. Th is book covers th e im p ortan t d ifferen ces between m ajor system arch itectu res from th e origin al In d u stry Stan d ard Arch itectu re (ISA) to th e latest in PCI an d AGP system s. Upgrading and Repairing PCs covers each of th ese system arch itectu res an d th eir ad ap ter board s to h elp you m ake d ecision s abou t wh ich kin d of system you m ay wan t to bu y in th e fu tu re, an d to h elp you u p grad e an d trou blesh oot su ch system s. Th e am ou n t of storage sp ace available to m od ern PCs is in creasin g geom etrically. Upgrading and Repairing PCs covers storage op tion s ran gin g from larger, faster h ard d rives to state-of-th e-art storage d evices. In ad d ition , th is book p rovid es d etailed in form ation on u p grad in g an d trou blesh ootin g system RAM. W h en you fin ish read in g th is book, you sh ou ld h ave th e kn owled ge to u p grad e, trou blesh oot, an d rep air alm ost all system s an d com p on en ts.

W ho Should Use This Book? Upgrading and Repairing PCs is d esign ed for p eop le wh o wan t a th orou gh u n d erstan d in g of h ow th eir PC system s work. Each section fu lly exp lain s com m on an d n ot-so com m on p roblem s, wh at cau ses p roblem s, an d h ow to h an d le p roblem s wh en th ey arise. You will gain an u n d erstan d in g of d isk con figu ration an d in terfacin g, for exam p le, th at can im p rove you r d iagn ostics an d trou blesh ootin g skills. You ’ll d evelop a feel for wh at goes on in a system so th at you can rely on you r own ju d gm en t an d observation s an d n ot som e table of can n ed trou blesh ootin g step s. Th is book is for p eop le wh o are tru ly in terested in th eir system s an d h ow th ey op erate. Upgrading and Repairing PCs is written for p eop le wh o will select, in stall, con figu re, m ain tain , an d rep air system s th ey or th eir com p an ies u se. To accom p lish th ese tasks, you n eed a level of kn owled ge m u ch h igh er th an th at of an average system u ser. You m u st

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Introduction

kn ow exactly wh ich tool to u se for a task an d h ow to u se th e tool correctly. Th is book can h elp you ach ieve th is level of kn owled ge.

W hat Is in This Book? Ch ap ters 1 an d 2 of th is book serve p rim arily as an in trod u ction . Ch ap ter 1, “Person al Com p u ter Backgrou n d ,” begin s with an in trod u ction to th e d evelop m en t of th e origin al IBM PC an d PC-com p atibles. Ch ap ter 2, “PC Com p on en ts, Featu res, an d System Design ,” p rovid es in form ation abou t th e d ifferen t typ es of system s you en cou n ter an d wh at sep arates on e typ e of system from an oth er, in clu d in g th e typ es of system bu s th at d ifferen tiate system s. Ch ap ter 2 also p rovid es an overview of th e typ es of PC system s th at h elp bu ild a fou n d ation of kn owled ge essen tial for th e rem ain d er of th e book. Ch ap ters 3–6 cover th e p rim ary system com p on en ts of a PC. Ch ap ter 3, “Microp rocessor Typ es an d Sp ecification s,” goes in to d etail abou t th e cen tral p rocessin g u n it (CPU), or m ain p rocessor, in clu d in g th ose from In tel an d oth er com p an ies. Ch ap ter 4, “Moth erboard s an d Bu ses,” covers th e m oth erboard , ch ip sets, m oth erboard com p on en ts, an d bu ses in d etail. Ch ap ter 5, “Mem ory,” gives a d etailed d iscu ssion of PC m em ory. Ch ap ter 6, “Power Su p p ly an d Case,” is a d etailed in vestigation of th e p ower su p p ly, wh ich rem ain s th e p rim ary cau se for PC system p roblem s an d failu res. Ch ap ters 7–11 are abou t in p u t/ ou tp u t h ard ware begin n in g with Ch ap ter 7, “In p u t Devices.” Th is ch ap ter in clu d es coverage of keyboard s, p oin tin g d evices, an d th e gam e p ort. Ch ap ter 8, “Vid eo Hard ware,” d iscu sses vid eo d isp lay h ard ware, in clu d in g vid eo ad ap ters an d m on itors. Ch ap ter 9, “Au d io Hard ware,” focu ses on au d io h ard ware in clu d in g sou n d board s an d sp eaker system s. Ch ap ter 10, “I/ O In terfaces,” d iscu sses in p u t an d ou tp u t at th e system h ard ware level in clu d in g serial an d p arallel p orts, USB, FireW ire, an d all th e m ajor d rive in terfaces su ch as IDE an d SCSI. Ch ap ter 11, “Com m u n ication s an d Networkin g,” is a d etailed d iscu ssion of com m u n ication s an d n etworkin g h ard ware, wh ile Ch ap ters 12 an d 13 are abou t m ass storage system s. Ch ap ter 12, “Magn etic Storage,” covers all th e typ es of m agn etic storage an d covers flop p y d rives, h ard d rives, tap e d rives, an d all varieties of d rive con trollers. Sp ecial coverage is given to p op u lar n ew m agn etic storage typ es su ch as Zip an d LS-120 d rives. Ch ap ter 12 also d etails th e in stallation req u irem en ts an d p roced u res for d rives. Th is in form ation is in valu able wh en you in stall d rives as eith er rep lacem en ts or u p grad es in a system , an d if you trou blesh oot an d rep air m alfu n ction in g d rives. Ch ap ter 13, “Op tical Storage,” is abou t op tical d rives th at you p robably see m ost often as CD-ROM d rives, bu t it also covers CD record ers, rewritable CDs, an d oth er op tical tech n ologies. Ch ap ter 14, “Prin ters,” is n ew to th is ed ition . It covers variou s p rin ter typ es an d lan gu ages, p rin ter u p grad es, p reven tive m ain ten an ce, rep air, an d th e ever trou blesom e issu e of p rin ter d rivers. Ch ap ter 15, “Portable PCs,” covers p ortable system s in clu d in g lap top an d n otebook system s. It also focu ses on all th e tech n ology u n iq u e an d p ecu liar to p ortable system s su ch as m obile p rocessors, d isp lay, battery, an d oth er tech n ologies. Ch ap ter 16, “Bu ild in g or Up grad in g System s,” focu ses on bu yin g or bu ild in g a PCcom p atible system as well as system u p grad es an d im p rovem en ts. Th is in form ation is

Introduction

u sefu l esp ecially if you m ake p u rch asin g d ecision s, an d also serves as a gen eral gu id elin e for featu res th at m ake a certain com p atible com p u ter a good or bad ch oice. Th e m ore ad ven tu rou s can u se th is in form ation to assem ble th eir own cu stom system from scratch . Ph ysical d isassem bly an d assem bly p roced u res are also d iscu ssed in th is ch ap ter. Ch ap ter 17, “Diagn ostics, Testin g, an d Main ten an ce,” covers d iagn ostic an d testin g tools an d p roced u res. Ch ap ter 18, “Op eratin g System s Software an d Trou blesh ootin g,” covers op eratin g system software an d trou blesh ootin g. Ch ap ter 19, “File System s an d Data Recovery,” is a su bstan tially n ew ch ap ter coverin g file system s an d d ata recovery. Ch ap ter 20, “IBM Person al Com p u ter Fam ily Hard ware,” covers in con sid erable d ep th th e origin al classic IBM PC, XT, an d AT com p u ters. All m od ern com p atibles are based on th ese system s, so th is in form ation can serve as a u sefu l referen ce. Th is in form ation is u sefu l n ot on ly for su p p ortin g actu al IBM eq u ip m en t, bu t also for PC-com p atible system s n ot su p p lied with exten sive d ocu m en tation . You learn h ow to com p are system s with th e origin al IBM stan d ard , an d see h ow far we h ave com e sin ce th ese origin al corn erston e system s were in trod u ced . Ch ap ter 21, “A Fin al W ord ,” offers closu re by tyin g all th e tech n ologies togeth er, an d p rovid in g su ggestion s on ad d ition al p laces to fin d in form ation . Ap p en d ix A, “Ven d or List,” p rovid es an extrem ely well-d etailed ven d or list u sefu l for fin d in g su p p liers an d ven d ors of n ecessary h ard ware an d software. Ap p en d ix B, “Usefu l Hard ware W eb Sites,” lists som e u sefu l W eb sites th at are n ot affiliated with a sp ecific ven d or in th e ven d or list. Ap p en d ix C, “Glossary,” is an in form ative glossary. Ap p en d ix D, “Tech n ical Referen ce,” p rovid es a PC tech n ical referen ce section , in clu d in g a variety of tech n ical in form ation tables. Upgrading and Repairing PCs offers coverage of n ot on ly th e fu ll bread th of PC-com p atible h ard ware, bu t also featu res a great d eal of in -d ep th coverage of each sp ecific top ic. Th is book is valu able as a referen ce tool for u n d erstan d in g h ow variou s com p on en ts in a system in teract an d op erate, an d as a gu id e to rep airin g an d servicin g p roblem s you en cou n ter. I th in k you will fin d Upgrading and Repairing PCs to be far m ore th an ju st a rep air m an u al.

W hat ’s New and Special About t he Tenth Anniversary Edition Th is ed ition of th e book is m u ch m ore th an ju st a celebration of m y ten years of work writin g th is book for Qu e. Man y of you wh o are read in g th is h ave p u rch ased on e or m ore of th e p reviou s ed ition s. An d based on you r letters, e-m ails, an d oth er corresp on d en ce, I kn ow th at as m u ch as you valu e each n ew ed ition , you wan t to kn ow wh at n ew in form ation I’m brin gin g you . So, h ere is a sh ort list of th e m ajor im p rovem en ts to th is ed ition : ■ As th e PC in d u stry h as m oved fu rth er away from “IBM com p atible” th in kin g an d n om en clatu re, th is ed ition is d oin g th e sam e. Th is ch an ge sh ows u p m ost visibly in Ch ap ter 2 wh ere I d iscu ss wh o con trols PC h ard ware n ow bu t is also reflected

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su btlety th rou gh ou t th e rest of th e book as an y rem ain in g referen ces to sp ecific IBM m od els an d com p atibility h ave been u p d ated to refer to system typ es an d fam ilies th at are com m on to all PC ven d ors. ■ Th e u p d atin g of Ch ap ter 3, “Microp rocessor Typ es an d Sp ecification s,” in volved a m ajor reorgan ization of th e ch ap ter an d ad d in g som e 50 p ages of n ew coverage. Th e n ew organ ization looks at all th e relevan t p rocessors (an d cop rocessors an d p rocessor u p grad es) in term s of th e fam ily of p rocessor th ey belon g to. Th e coverage of In tel Pen tiu m , Pen tiu m Pro, an d Pen tiu m II p rocessors h as been stren gth en ed with u p -to-d ate listin gs of step p in gs, p rocessors from AMD, Cyrix, an d oth er ven d ors h ave been given m ore coverage, an d cu ttin g-ed ge featu res su ch as Du al In d ep en d en t Bu s (DIB) Arch itectu re are exp lain ed in m ore d etail. I h op e th at you will like th e su bstan tial ad d ition s of illu stration s an d p h otograp h s to better sh ow item s su ch as socket typ es, p rocessor featu res, an d m arkin gs. ■ Ch ap ter 4, “Moth erboard s an d Bu ses,” takes th e n ew ap p roach of coverin g th e m oth erboard s an d th e bu ses fou n d on th e m oth erboard s togeth er as on e top ic. In ad d ition , you will fin d exten sive n ew coverage of Pen tiu m , Pen tiu m Pro, an d Pen tiu m II ch ip sets, wh ich form th e basis of all m od ern m oth erboard s. Th is ch ap ter in clu d es coverage of th e featu res, cap abilities, an d lim itation s of th e ch ip sets in com m on u se tod ay. ■ Ch ap ter 5, “Mem ory,” h as been reorgan ized to begin by lookin g at typ es of m em ory an d h ow th ey are in stalled first. All of th e m ore recen t typ es of m em ory in clu d in g EDO RAM an d SDRAM are exp lain ed in m ore d etail in th is ed ition . You ’ll also fin d an swers to often asked q u estion s relatin g m em ory sp eed to p rocessor sp eed an d a m ore th orou gh exp lan ation of wh y error ch eckin g is still an im p ortan t m em ory featu re. Th is ch ap ter also featu res m an y n ew illu stration s to m ake it easier to id en tify SIMM an d SIMM typ es an d h ow to in sert th em . ■ Ch ap ter 10, “I/ O In terfaces,” rep resen ts a m ajor reorgan ization for th e book. In th is ch ap ter, you will n ow fin d in form ation abou t an y stan d ard in p u t an d ou tp u t in terface on th e PC. Th is in clu d es everyth in g from stan d ard serial an d p arallel p orts to ATA (IDE), SCSI, USB, an d FireW ire. ■ Ch ap ter 12, “Magn etic Storage,” takes wh at u sed to be th ree sep arate ch ap ters abou t flop p y d rives, h ard d isk d rives, an d d rive in stallation an d treats th is as p art of th e larger top ic of m agn etic storage. Everyth in g abou t m agn etic storage is covered h ere. ■ Ch ap ter 14, “Prin ters,” is n ew to th is ed ition . I th an k th e m an y read ers wh o h ave su ggested th is recen tly (as well as th eir m an y oth er su ggestion s) h elp in g to m ake th is a reality. ■ Ch ap ters 17, “Diagn ostics, Testin g, an d Main ten an ce,” an d 18, “Op eratin g System s Software an d Trou blesh ootin g,” both h ave m u ch n ew an d d ifferen t coverage. Mu ch of th is is a reflection of n ewer op eratin g system s su ch as W in d ows 98. Th e fact th at trou blesh ootin g an d con figu ration tools are less d ep en d en t on h ard ware system ven d ors (su ch as IBM or Com p aq ) an d m ore gen erally are th ird -p arty software tools n ecessitates a n ew way to look at setu p an d testin g.

Introduction

■ Ch ap ter 19, “File System s an d Data Recovery,” is su bstan tially n ew for th is ed ition . ■ Ch ap ter 21, “A Fin al W ord ,” looks at th e n ew A+ certification exam . Alth ou gh th ose are th e m ajor ch an ges to th e core of th e book, every ch ap ter h as seen su bstan tial u p d ates. I can say with ou t h esitation th at th is ed ition rep resen ts th e m ost m ajor overh au l of th is book sin ce th e origin al ed ition . In ad d ition to th ose u p d ates to th e core ch ap ters, you m ay also be in terested in th ese m ajor ch an ges to th e ap p en d ixes: ■ Alth ou gh th ere will always be som e ven d or with a n ew p h on e n u m ber or ad d ress, we h ave ch ecked every ven d or’s con tact in form ation for Ap p en d ix A, “Ven d or List.” As always, if you n otice an y of th ese th at h ave ch an ged , con tact m e at th e em ail ad d ress listed in m y biograp h y an d let m e kn ow th e ch an ge. ■ Ap p en d ix B, “Usefu l Hard ware W eb Sites,” is n ew to th is ad d ition , listin g W eb sites th at are of in terest th at aren ’t related to an y of th e sp ecific ven d ors listed in Ap p en d ix A. ■ Ap p en d ix C, “Glossary,” h as been greatly exp an d ed . Over 100 n ew term s are listed in th is ed ition to m ake it easier to look u p an d u n d erstan d th e ever-growin g tech n ical lan gu age of th e PC field . ■ By p op u lar d em an d , th e tech n ical referen ce th at was cu t from th e p reviou s ed ition h as been ad d ed back. You ’ll fin d all n ew tables of m od ern h ard d rive p aram eters, u p d ated BIOS error cod es, an d m u ch m ore to m ake th is a valu able referen ce. ■ If you h ave trou ble keep in g track of th e m ean in gs of abbreviation s an d acron ym s, I h op e you ’ll m ake exten sive u se of th e n ew listin g of th ese alon g with th eir exp an d ed m ean in g. ■ W e’ve ad d ed a n ew in d ex of ven d ors to m ake it easy to fin d referen ces to p rod u cts an d tech n ologies by ven d or. ■ Th e m ain in d ex of th e book is su bstan tially im p roved . Alth ou gh I’m su re m ost of you d on ’t “read ” th e in d ex, you can tell a good on e from a bad on e based on wh eth er you can fin d wh at you are lookin g for in th e book from th e in d ex. Th an ks to a n ew in d exin g p rocess at Qu e, th is in d ex is m ore d etailed an d com p reh en sive th an an y of th e ed ition s th at p reced ed it. The Tent h Anniversary Edit ion CD-ROM s As if everyth in g in clu d ed in th e p rin ted book isn ’t en ou gh , th is ed ition con tain s two alln ew CD-ROMs. W h eth er or n ot you h ave ever p u rch ased a p reviou s ed ition of th is book with a CD-ROM, you ’ll fin d th e n ew con ten t on th ese CDs to be a valu able treat to su p p lem en t th e book. Here is an overview of th e con ten t of th e CDs: ■ On e of th e h ard est th in gs to d o in su p p ortin g h ard ware is fin d in g d ocu m en tation for legacy system s. Th an ks to Micro Hou se, th at d oesn ’t h ave to stop you an y m ore. Th e CDs with th is book con tain a p ortion of Micro Hou se’s Su p p ort Sou rce Hard ware m od u le. Th is fu lly search able electron ic d atabase in clu d es tech n ical d ocu m en tation sh owin g con figu ration , an d d iagram s for tod ay’s m ost p op u lar PC

7

8

Introduction

p rod u cts. Th e p ortion in clu d ed with th is book in clu d es d rive p aram eters for over 3,600 h ard d rives an d con figu ration an d setu p in form ation for over 100 m od els each of m od em s, NICs, h ard d rive, d rive con trollers, an d m oth erboard s. Th e Su p p ort Sou rce en gin e also lin ks you to th eir Tech Crawler, wh ich is a W eb-based search en gin e tu n ed to in d ex an d search 1,200 h ard ware-related W eb sites an d th eir FCC ID locator, wh ich h elp s you locate th e com p an y wh o m an u factu red an y PC p rod u ct by en terin g th e FCC ID n u m ber fou n d on th e p rod u ct. ■ Are you th in kin g abou t takin g A+ certification classes or testin g to im p rove you r p rofession al stan d in g? Th e CD con tain s a tu torial p rep arin g you for th e n ew A+ core exam m od u le. As A+ certification is rap id ly becom in g a criterion for em p loym en t in th is in d u stry, th ose of you lookin g at a career workin g with PCs will fin d th is essen tial. Note th at Upgrading and Repairing PCs h as always been th e m ost wid ely u sed an d recom m en d ed referen ce in p rep arin g for th e A+ certification tests, an d n ow it will be even m ore u sefu l! ■ A n ew collection of d igital vid eos sh owin g key excerp ts from m y sem in ars an d d em on stration s of h ard ware p roced u res th at ju st can ’t be sh own in th e p rin ted book. ■ A collection of u tilities from Micro Hou se h igh ligh ted by th eir Im age Cast LE. Th is p rogram m akes it a sn ap to d u p licate en tire h ard d rives (m akin g u p to th ree sim u ltan eou s cop ies) an d is a m u st-h ave for an yon e con figu rin g PCs for en d -u ser u se.

A Personal Not e I am so excited abou t all th e n ew ch an ges in th is ed ition , I can h ard ly wait for everybod y to see it. I an d everybod y else at Qu e h ave worked h ard to m ake th is th e best ed ition ever. I am so gratefu l to everybod y wh o h as h elp ed m e with th is book over th e last 10 years as well as all of th e loyal read ers wh o h ave been read in g th is book, m an y of you sin ce th e first ed ition cam e ou t. I h ave h ad p erson al con tact with m an y th ou san d s of you in th e sem in ars I h ave been teach in g sin ce 1982, an d all I can say is I en joy you r com m en ts an d even criticism s trem en d ou sly. Usin g th is book in a teach in g en viron m en t h as been a m ajor factor in its d evelop m en t. Som e of you m ay be in terested to kn ow th at I origin ally began writin g th is book all th e way back in 1985; back th en it was u sed exclu sively in m y PC h ard ware sem in ars before bein g p u blish ed by Qu e in 1988. I ju st realized th at I h ave been writin g an d rewritin g th is book alm ost con tin u ou sly for m ore th an 13 years! In th e m ore th an 10 years sin ce it was first p u blish ed , Upgrading and Repairing PCs h as p roven to be n ot on ly th e first bu t absolu tely th e best book of its kin d on th e m arket, an d n ow with th e n ew Tenth Anniversary Edition, it is even better th an ever. You r com m en ts, su ggestion s, an d su p p ort h ave h elp ed th is book to becom e th e best PC h ard ware book on th e m arket. I look forward to h earin g you r com m en ts after you see th is excitin g n ew ed ition . Scott

Chapter 1

1

Personal Computer Background

Man y d iscoveries an d in ven tion s h ave d irectly an d in d irectly con tribu ted to th e d evelop m en t of th e p erson al com p u ter. Exam in in g a few im p ortan t d evelop m en tal lan d m arks can h elp brin g th e en tire p ictu re in to focu s.

Personal Com put ing Hist ory A m od ern d igital com p u ter is largely a collection of electron ic switch es. Th ese switch es are u sed to rep resen t an d con trol th e rou tin g of d ata elem en ts called binary digits (or bits). Becau se of th e on or off n atu re of th e bin ary in form ation an d sign al rou tin g u sed by th e com p u ter, an efficien t electron ic switch was req u ired . Th e first electron ic com p u ters u sed vacu u m tu bes as switch es, an d alth ou gh th e tu bes worked , th ey h ad m an y p roblem s. Th e tu be was in efficien t as a switch . It con su m ed a great d eal of electrical p ower an d gave off en orm ou s h eat—a sign ifican t p roblem in th e earlier system s. Prim arily becau se of th e h eat th ey gen erated , tu bes were n otoriou sly u n reliable—on e failed every cou p le of h ou rs or so in th e larger system s. Th e in ven tion of th e tran sistor, or sem icon d u ctor, was on e of th e m ost im p ortan t d evelop m en ts lead in g to th e p erson al com p u ter revolu tion . Th e tran sistor was in ven ted in 1948 by Bell Laboratories en gin eers Joh n Bard een , W alter Brattain , an d W illiam Sh ockley. Th e tran sistor, wh ich essen tially fu n ction s as a solid -state electron ic switch , rep laced th e m u ch less su itable vacu u m tu be. Becau se th e tran sistor was so m u ch sm aller an d con su m ed sign ifican tly less p ower, a com p u ter system bu ilt with tran sistors was m u ch sm aller, faster, an d m ore efficien t th an a com p u ter system bu ilt with vacu u m tu bes. Th e con version to tran sistors began th e tren d toward m in iatu rization th at con tin u es to th is d ay. Tod ay’s sm all lap top (or p alm top ) PC system s, wh ich ru n on batteries, h ave m ore com p u tin g p ower th an m an y earlier system s th at filled room s an d con su m ed h u ge am ou n ts of electrical p ower.

9

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Chapter 1—Personal Computer Background

In 1959, en gin eers at Texas In stru m en ts in ven ted th e integrated circuit (IC), a sem icon d u ctor circu it th at con tain s m ore th an on e tran sistor on th e sam e base (or su bstrate m aterial) an d con n ects th e tran sistors with ou t wires. Th e first IC con tain ed on ly six tran sistors. By com p arison , th e In tel Pen tiu m Pro m icrop rocessor u sed in m an y of tod ay’s h igh -en d system s h as m ore th an 5.5 m illion tran sistors, an d th e in tegral cach e bu ilt in to som e of th ese ch ip s con tain s as m an y as an ad d ition al 32 m illion tran sistors! Tod ay, m an y ICs h ave tran sistor cou n ts in th e m u ltim illion ran ge. In 1969, In tel in trodu ced a 1Kbit m em ory ch ip, wh ich was m u ch larger th an an yth in g else available at th e tim e. (1Kbit equ als 1,024 bits, an d a byte equ als 8 bits. Th is ch ip, th erefore, stored on ly 128 bytes—n ot m u ch by today’s stan dards.) Becau se of In tel’s su ccess in ch ip m an u factu rin g an d design , Bu sicom p, a Japan ese calcu lator m an u factu rin g com pan y, asked In tel to produ ce 12 differen t logic ch ips for on e of its calcu lator design s. Rath er th an produ ce 12 separate ch ips, In tel en gin eers in clu ded all th e fu n ction s in a sin gle ch ip. In ad d ition to in corp oratin g all th e fu n ction s an d cap abilities of th e 12-ch ip d esign in to on e m u ltip u rp ose ch ip , th e en gin eers d esign ed th e ch ip to be con trolled by a p rogram th at cou ld alter th e fu n ction of th e ch ip . Th e ch ip was gen eric in n atu re, m ean in g it cou ld fu n ction in d esign s oth er th an calcu lators. Previou s d esign s were h ard -wired for on e p u rp ose, with bu ilt-in in stru ction s; th is ch ip wou ld read from m em ory a variable set of in stru ction s th at wou ld con trol th e fu n ction of th e ch ip . Th e id ea was to d esign alm ost an en tire com p u tin g d evice on a sin gle ch ip th at cou ld p erform d ifferen t fu n ction s, d ep en d in g on wh at in stru ction s it was given . Th e first m icrop rocessor—th e In tel 4004, a 4-bit p rocessor—was in trod u ced in 1971. Th e ch ip op erated on 4 bits of d ata at a tim e. Th e su ccessor to th e 4004 ch ip was th e 8008 8-bit m icrop rocessor, in trod u ced in 1972. In 1973, som e of th e first m icrocom p u ter kits based on th e 8008 ch ip were d evelop ed . Th ese kits were little m ore th an d em on stration tools an d d id little excep t blin k ligh ts. In late 1973, In tel in trod u ced th e 8080 m icrop rocessor, wh ich was 10 tim es faster th an th e earlier 8008 ch ip an d ad d ressed 64K of m em ory. Th is was th e breakth rou gh th e p erson al com p u ter in d u stry h ad been seekin g. MITS in trod u ced th e Altair kit in a cover story in th e Jan u ary 1975 issu e of Popular Electronics m agazin e. Th e Altair kit, con sid ered to be th e first p erson al com p u ter, in clu d ed an 8080 p rocessor, a p ower su p p ly, a fron t p an el with a large n u m ber of ligh ts, an d 256 bytes (n ot kilobytes) of m em ory. Th e kit sold for $395 an d h ad to be assem bled . Th e com p u ter in clu d ed an op en arch itectu re bu s (slots) th at p rom p ted variou s ad d -on s an d p erip h erals from afterm arket com p an ies. Th e n ew p rocessor in sp ired oth er com p an ies to write p rogram s, in clu d in g th e CP/ M (Con trol Program for Microp rocessors) op eratin g system an d th e first version of th e Microsoft BASIC (Begin n ers All-p u rp ose Sym bolic In stru ction Cod e) p rogram m in g lan gu age. IBM in trod u ced wh at can be called its first personal com puter in 1975. Th e Mod el 5100 h ad 16K of m em ory, a bu ilt-in 16-lin e by 64-ch aracter d isp lay, a bu ilt-in BASIC lan gu age in terp reter, an d a bu ilt-in DC-300 cartrid ge tap e d rive for storage. Th e system ’s $9,000

The IBM Personal Computer

p rice p laced it ou t of th e m ain stream p erson al com p u ter m arketp lace, wh ich was d om in ated by exp erim en ters (affection ately referred to as hackers) wh o bu ilt low-cost kits ($500 or so) as a h obby. Obviou sly, th e IBM system was n ot in com p etition for th is lowcost m arket an d d id n ot sell well. Th e Mod el 5100 was su cceed ed by th e 5110 an d 5120 before IBM in trod u ced wh at we kn ow as th e IBM Person al Com p u ter (Mod el 5150). Alth ou gh th e 5100 series p reced ed th e IBM PC, th e old er system s an d th e 5150 IBM PC h ad n oth in g in com m on . Th e PC IBM tu rn ed ou t was m ore closely related to th e IBM System / 23 DataMaster, an office com p u ter system in trod u ced in 1980. In fact, m an y of th e en gin eers wh o d evelop ed th e PC at IBM h ad origin ally worked on th e DataMaster. In 1976, a n ew com p an y called Ap p le Com p u ter in trod u ced th e Ap p le I, wh ich sold for $695. Th is system con sisted of a m ain circu it board screwed to a p iece of p lywood . A case an d p ower su p p ly were n ot in clu d ed . On ly a few of th ese com p u ters were m ad e, an d th ey rep orted ly h ave sold to collectors for m ore th an $20,000. Th e Ap p le II, in trod u ced in 1977, h elp ed set th e stan d ard for n early all th e im p ortan t m icrocom p u ters to follow, in clu d in g th e IBM PC. Th e m icrocom pu ter world was dom in ated in 1980 by two types of com pu ter system s. On e type, th e Apple II, claim ed a large followin g of loyal u sers an d a gigan tic software base th at was growin g at a fan tastic rate. Th e oth er type, CP/ M system s, con sisted n ot of a sin gle system bu t of all th e m an y system s th at evolved from th e origin al MITS Altair. Th ese system s were com patible with on e an oth er an d were distin gu ish ed by th eir u se of th e CP/ M operatin g system an d expan sion slots, wh ich followed th e S-100 (for slots with 100 pin s) stan dard. All th ese system s were bu ilt by a variety of com pan ies an d sold u n der variou s n am es. For th e m ost part, h owever, th ese com pan ies u sed th e sam e software an d plu g-in h ardware. It is in terestin g to n ote th at n on e of th ese system s were PC-com patible, or Maccom patible, th e two prim ary stan dards in place today.

The IBM Personal Com put er At th e en d of 1980, IBM d ecid ed to tru ly com p ete in th e rap id ly growin g low-cost p erson al com p u ter m arket. Th e com p an y establish ed wh at was called th e En try System s Division , located in Boca Raton , Florid a, to d evelop th e n ew system . Th is sm all grou p con sisted of 12 en gin eers an d d esign ers u n d er th e d irection of Don Estrid ge. Th e team ’s ch ief d esign er was Lewis Eggebrech t. Th e d ivision d evelop ed IBM’s first real PC (IBM con sid ered th e 5100 system , d evelop ed in 1975, to be an in telligen t p rogram m able term in al rath er th an a gen u in e com p u ter, even th ou gh it tru ly was a com p u ter). Nearly all th ese en gin eers h ad been m oved to th e n ew d ivision from th e System / 23 DataMaster p roject, wh ich in 1980 in trod u ced a sm all office com p u ter system th at was th e closest p red ecessor to th e IBM PC. Mu ch of th e PC’s d esign was in flu en ced by th e DataMaster’s d esign . In th e DataMaster’s sin gle-p iece d esign , th e d isp lay an d keyboard were in tegrated in to th e u n it. Becau se th ese featu res were lim itin g, th ey becam e extern al u n its on th e PC, alth ou gh th e PC keyboard layou t an d electrical d esign s were cop ied from th e DataMaster.

11

12

Chapter 1—Personal Computer Background

Several oth er p arts of th e IBM PC system also were cop ied from th e DataMaster, in clu d in g th e exp an sion bu s (or in p u t/ ou tp u t slots), wh ich in clu d ed n ot on ly th e sam e p h ysical 62-p in con n ector, bu t also alm ost id en tical p in sp ecification s. Th is cop yin g was p ossible becau se th e PC u sed th e sam e in terru p t con troller as th e DataMaster an d a sim ilar d irect m em ory access (DMA) con troller. Also, exp an sion card s alread y d esign ed for th e DataMaster cou ld easily be red esign ed to fu n ction in th e PC. Th e DataMaster u sed an In tel 8085 CPU, wh ich h ad a 64K ad d ress lim it, an d an 8-bit in tern al an d extern al d ata bu s. Th is arran gem en t p rom p ted th e PC d esign team to u se th e In tel 8088 CPU, wh ich offered a m u ch larger (1M) m em ory ad d ress lim it, an d an in tern al 16-bit d ata bu s, bu t on ly an 8-bit extern al d ata bu s. Th e 8-bit extern al d ata bu s an d sim ilar in stru ction set allowed th e 8088 to be easily in terfaced in to th e earlier DataMaster d esign s. Estrid ge an d th e d esign team rap id ly d evelop ed th e d esign an d sp ecification s for th e n ew system . In ad d ition to borrowin g from th e System / 23 DataMaster, th e team stu d ied th e m arketp lace, wh ich also h ad en orm ou s in flu en ce on th e IBM PC’s d esign . Th e d esign ers looked at th e p revailin g stan d ard s, learn ed from th e su ccess of th ose system s, an d in corp orated in to th e n ew PC all th e featu res of th e p op u lar system s—an d m ore. W ith th e p aram eters for d esign m ad e obviou s by th e m arket, IBM p rod u ced a system th at filled its n ich e in th e m arket. IBM brou gh t its system from id ea to d elivery in on e year by u sin g existin g d esign s an d p u rch asin g as m an y com p on en ts as p ossible from ou tsid e ven d ors. Th e En try System s Division was gran ted au ton om y from IBM’s oth er d ivision s an d cou ld tap resou rces ou tsid e th e com p an y, rath er th an go th rou gh th e bu reau cratic p roced u res th at req u ired exclu sive u se of IBM resou rces. IBM con tracted ou t th e PC’s lan gu ages an d op eratin g system to a sm all com p an y n am ed Microsoft. Th at d ecision was th e m ajor factor in establish in g Microsoft as th e d om in an t force in PC software tod ay.

Not e It is interesting to note that IBM had originally contacted Digital Research (the company that created CP/ M , then the most popular personal computer operating system) to have them develop an operating system for the new IBM PC, but they were leery of working with IBM , and especially balked at the nondisclosure agreement IBM wanted them to sign. M icrosoft jumped on the opportunity left open by Digital Research, and as a result has become one of the largest software companies in the world. IBM ’s use of outside vendors in developing the PC was an open invitation for the aftermarket to jump in and support the system—and it did.

On W edn esday, Au gu st 12, 1981, a n ew stan dard was establish ed in th e m icrocom pu ter in du stry with th e debu t of th e IBM PC. Sin ce th en , h u n dreds of m illion s of PC-com patible system s h ave been sold, as th e origin al PC h as grown in to an en orm ou s fam ily of com pu ters an d periph erals. More software h as been written for th is com pu ter fam ily th an for an y oth er system on th e m arket.

The IBM -Compatible M arketplace 17 Years Later

The IBM -Com pat ible M arket place 17 Years Lat er In th e m ore th an 17 years sin ce th e origin al IBM PC was in trod u ced , m an y ch an ges h ave occu rred . Th e IBM-com p atible com p u ter, for exam p le, ad van ced from a 4.77MHz 8088based system to 300MHz or faster Pen tiu m II-based system s—n early 2,000 tim es faster th an th e origin al IBM PC (in actu al p rocessin g sp eed , n ot ju st clock sp eed ). Th e origin al PC h ad on ly on e or two sin gle-sid ed flop p y d rives th at stored 160K each u sin g DOS 1.0, wh ereas m od ern system s easily can h ave 10G (10 billion bytes) or m ore of h ard d isk storage. A ru le of th u m b in th e com p u ter in d u stry is th at available p rocessor p erform an ce an d d isk-storage cap acity at least d ou ble every two to th ree years. Sin ce th e begin n in g of th e PC in d u stry, th is p attern h as sh own n o sign of ch an gin g. In ad d ition to p erform an ce an d storage cap acity, an oth er m ajor ch an ge sin ce th e origin al IBM PC was in trod u ced is th at IBM is n ot th e on ly m an u factu rer of “PC-com p atible” system s. IBM origin ated th e PC-com p atible stan d ard , of cou rse, an d it con tin u es to set stan d ard s th at com p atible system s follow, bu t th e com p an y d oes n ot d om in ate th e PC m arket as it on ce d id . More often th an n ot, n ew stan d ard s in th e PC in d u stry are d evelop ed by com p an ies an d organ ization s oth er th an IBM. Tod ay, it is In tel an d Microsoft wh o are p rim arily resp on sible for d evelop in g an d exten d in g th e PC h ard ware an d software stan d ard s, resp ectively. Som e h ave even taken to callin g PCs “W in tel” system s, owin g to th e d om in an ce of th ose two com p an ies. ◊◊ See “ Who Controls PC Software,” p. 16

◊◊ See “ Who Controls PC Hardware,” p. 18

Even so, th ere are literally h u n d red s of system m an u factu rers p rod u cin g com p u ters th at are fu lly PC-com p atible, n ot to m en tion th e th ou san d s of p erip h eral m an u factu rers wh ose com p on en ts exp an d an d en h an ce PC-com p atible system s. PC-com p atible system s h ave th rived , n ot on ly becau se com p atible h ard ware can be assem bled easily, bu t also becau se th e p rim ary op eratin g system was available n ot from IBM bu t from a th ird p arty (Microsoft). Th e core of th e system software is th e BIOS (Basic In p u t/ Ou tp u t System ), an d th is was also available from th ird -p arty com p an ies su ch as AMI, Award , Ph oen ix, an d oth ers. Th is situ ation allowed oth er m an u factu rers to licen se th e op eratin g system an d BIOS software an d to sell th eir own com p atible system s. Th e fact th at DOS borrowed th e fu n ction ality an d u ser in terface from both CP/ M an d UNIX p robably h ad a lot to d o with th e am ou n t of software th at becam e available. Later, with th e su ccess of W in d ows, th ere wou ld be even m ore reason s for software d evelop ers to write p rogram s for PC-com p atible system s. On e of th e reason s wh y Ap p le Macin tosh system s will likely n ever en joy th e su ccess of PC-com p atibles is th at Ap p le con trols all th e software (BIOS an d OS), an d u n til recen tly

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Chapter 1—Personal Computer Background

h ad n ot licen sed an y of it to oth er com p an ies for u se in com p atible system s. Ap p le n ow seem s to recogn ize th is flawed stan ce becau se th ey h ave begu n to licen se th is software. However, it seem s too late for th em to effectively com p ete with th e PC-com p atible ju ggern au t. It is fortu n ate for th e com p u tin g p u blic as a wh ole th at IBM created a m ore op en an d exten d ible stan d ard . Th e com p etition am on g m an u factu rers an d ven d ors of PC-com p atible system s is th e reason wh y su ch system s offer so m u ch p erform an ce an d so m an y cap abilities for th e m on ey. Th e IBM-com p atible m arket con tin u es to th rive an d p rosp er. New tech n ology con tin u es to be in tegrated in to th ese system s, en ablin g th em to grow with th e tim es. Th ese system s offer a h igh valu e for th e m on ey an d h ave p len ty of software available to ru n on th em . It’s a safe bet th at PC-com p atible system s will d om in ate th e p erson al com p u ter m arketp lace for th e n ext 15 to 20 years.

Chapter 2

2

PC Components, Features, and System Design

Th is ch ap ter d efin es wh at a “PC” really is an d th en con tin u es by d efin in g th e typ es of PCs on th e m arket. In ad d ition , th e ch ap ter gives an overview of th e com p on en ts fou n d in a m od ern PC.

W hat Is a PC? I n orm ally ask th e q u estion , “W h at is a PC?” wh en I begin on e of m y PC h ard ware sem in ars. Of cou rse, m ost p eop le im m ed iately an swer th at PC stan d s for p erson al com p u ter, wh ich in fact it d oes. Most wou ld d efin e a p erson al com p u ter as an y sm all com p u ter system p u rch ased an d u sed by an in d ivid u al. Un fortu n ately, th at d efin ition is n ot n early p recise or accu rate en ou gh for ou r p u rp oses. I wou ld agree th at a PC is a p erson al com p u ter, bu t certain ly n ot all p erson al com p u ters are PCs. For exam p le, an Ap p le Macin tosh system is clearly a p erson al com p u ter, bu t n obod y I kn ow wou ld call a Mac a PC, least of all Mac u sers! For th e tru e d efin ition of wh at a PC is, you m u st look d eep er. Callin g som eth in g a PC im p lies th at it is som eth in g m u ch m ore sp ecific th an ju st an y p erson al com p u ter. On e th in g it im p lies is an origin in th e first IBM PC from 1981. In fact, I’ll go so far as to say IBM literally invented th e PC; th at is, th ey d esign ed an d created th e first on e. However, it is also clear th at IBM d id n ot in ven t th e p erson al com p u ter. (Th e h istorical origin s of th e p erson al com p u ter are in th e MITS Altair in trod u ced in 1975.) Som e p eop le wou ld take th is fu rth er an d d efin e a PC as an y p erson al com p u ter th at is “IBM com p atible.” In fact, m an y years back we u sed to call PCs eith er IBM com p atibles or IBM clon es, in essen ce p ayin g h om age to th e origin s of th e PC at IBM. Th e reality is th at alth ou gh IBM clearly d esign ed an d created th e first PC in 1981, an d con trolled th e d evelop m en t an d evolu tion of th e PC stan d ard for several years th ereafter, IBM is n o lon ger in con trol of th e PC stan d ard . IBM lost con trol of th e PC stan d ard in 1987 wh en th ey in trod u ced th eir PS/ 2 lin e

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Chapter 2—PC Components, Features, and System Design

of system s. Up u n til th en , oth er com p an ies p rod u cin g PCs literally cop ied IBM’s system s righ t d own to th e ch ip s, con n ectors, an d sh ap es (form factors) of th e board s, wh ile after 1987 IBM aban d on ed m an y of th e stan d ard s th ey created in th e first p lace. Th at’s wh y I h ave refrain ed from u sin g th e d esign ation “IBM com p atible” wh en referrin g to PCs. If a PC is n o lon ger an IBM com p atible, th en wh at is it? Th e real q u estion seem s to be— W h o is in con trol of th e PC stan d ard tod ay? Th at q u estion is best broken d own in to two p arts. First, wh o is in con trol of PC software an d secon d , wh o is in con trol of PC h ard ware? W ho Cont rols PC Soft w are? Most p eop le d on ’t even h esitate for a sp lit secon d wh en I ask th at q u estion in m y sem in ars; th ey im m ed iately resp on d “Microsoft!” I d on ’t th in k th ere is an y argu m en t with th at an swer. Tod ay Microsoft clearly con trols th e op eratin g system s u sed on PCs, wh ich h as m igrated from th e origin al MS-DOS to W in d ows 95/ 98 an d W in d ows NT. Microsoft h as u sed th eir con trol of th e PC op eratin g system as leverage to also con trol oth er typ es of PC software, su ch as u tilities an d ap p lication s. For exam p le, m an y u tility p rogram s th at were origin ally offered by in d ep en d en t com p an ies su ch as d isk cach ein g, d isk com p ression , d efragm en tation , an d even calcu lators an d n otep ad s are n ow bu n d led (in clu d ed with ) in W in d ows. Th ey h ave even bu n d led ap p lication s like W eb browsers, in su rin g an au tom atic in stalled base for th ese ap p lication s, m u ch to th e d ism ay of com p an ies p rod u cin g com p etin g version s. Microsoft h as also leveraged th eir con trol of th e op eratin g system to in tegrate n etworkin g software an d ap p lication s su ites m ore seam lessly in to th e op eratin g system th an oth ers. Th at’s wh y th ey n ow d om in ate m ost of th e PC world , from word p rocessors to sp read sh eets to d atabase p rogram s. In th e early d ays of th e PC wh en IBM was in con trol of th e PC h ard ware stan d ard , th ey h ired Microsoft to p rovid e m ost of th e software for th e PC. IBM d evelop ed th e h ard ware, wrote th e BIOS (Basic In p u t Ou tp u t System ), an d h ired Microsoft to d evelop th e Disk Op eratin g System (DOS) an d several oth er p rogram s an d u tilities for IBM. In wh at wou ld later be viewed as th e m ost costly bu sin ess m istake in h istory, IBM failed to secu re exclu sive righ ts to DOS, eith er by p u rch asin g it ou trigh t or by an exclu sive licen se agreem en t. In stead , IBM licen sed it n on -exclu sively from Microsoft, wh ich su bseq u en tly allowed Microsoft to sell th e sam e MS-DOS cod e d evelop ed for IBM to an y oth er com p an y wh o was in terested . In retrosp ect, th at sin gle con tractu al error m ad e Microsoft in to th e d om in an t software com p an y it is tod ay, an d su bseq u en tly cau sed IBM to lose con trol of th e very PC stan d ard th ey h ad created . ◊◊ See “ BIOS,” p. 208

Th e reason IBM lost con trol of th is stan d ard is th at software en joys cop yrigh t p rotection , wh ile h ard ware can on ly be p rotected by p aten ts, wh ich are d ifficu lt an d tim e con su m in g to get an d wh ich also exp ire after 17 years. To p aten t som eth in g req u ires th at it be a u n iq u e an d su bstan tially n ew d esign , wh ile th e IBM PC was d esign ed u sin g p reviou sly

What Is a PC?

existin g p arts th at an ybod y cou ld p u rch ase! In fact m ost of th e im p ortan t p arts for th e origin al PC cam e from In tel, su ch as th e 8088 Processor, 8284 clock gen erator, 8253/ 54 tim er, 8259 in terru p t con troller, 8237 DMA (Direct Mem ory Access) con troller, 8255 p erip h eral in terface, an d th e 8288 bu s con troller. Th ese are th e ch ip s th at m ad e u p th e h eart of th e origin al PC. Becau se th e d esign of th e origin al PC was n ot p aten table, an ybod y cou ld d u p licate th e h ard ware of th e IBM PC. All th ey h ad to d o was p u rch ase th e sam e ch ip s from th e sam e m an u factu rers an d su p p liers as IBM d id , an d d esign a n ew m oth erboard with a sim ilar circu it. To aid in th is, IBM even p u blish ed com p lete sch em atic d iagram s of th eir m oth erboard s an d all th eir ad ap ter card s in very d etailed an d easily available Tech n ical Referen ce m an u als. I h ave several of th ese early IBM m an u als an d still refer to th em from tim e to tim e for sp ecific com p on en t-level PC d esign in form ation . Th e d ifficu lt p art in cop yin g th e IBM PC was th e software, wh ich is p rotected by cop yrigh t law. Ph oen ix Software was am on g th e first to d evelop a legal m eth od arou n d th is p roblem , th u s en ablin g th em to fu n ction ally d u p licate (bu t n ot cop y) software su ch as th e BIOS. Th ey h ired two team s of software en gin eers, th e secon d of wh ich h ad to be sp ecially screen ed to con sist on ly of p eop le wh o h ad n ever seen or stu d ied th e IBM BIOS cod e. Th e first team d id stu d y th e IBM BIOS, an d wrote as com p lete a d escrip tion of wh at it d id as p ossible. Th e secon d team read th e d escrip tion written by th e first team , an d set ou t to write from scratch a n ew BIOS th at d id everyth in g th e first team d escribed . Th e en d resu lt was a n ew BIOS written from scratch with cod e th at, alth ou gh n ot id en tical to IBM’s, wou ld h ave exactly th e sam e fu n ction ality. Ph oen ix called th is a “clean room ” ap p roach to reverse en gin eerin g software, an d it can escap e an y legal attack. Becau se IBM’s origin al PC BIOS con sisted of on ly 8K worth of cod e an d h ad lim ited fu n ction ality, d u p licatin g it th rou gh th e clean room ap p roach was n ot very d ifficu lt. As th e IBM BIOS evolved , oth er BIOS com p an ies fou n d it relatively easy to keep in step with an y ch an ges IBM wou ld m ake. Discou n tin g th e POST (PowerOn Self Test) p ortion of th e BIOS, m ost BIOSes even tod ay h ave on ly abou t 32K of active cod e. Tod ay n ot on ly Ph oen ix, bu t oth ers su ch as Award , AMI, an d Microid Research are p rod u cin g BIOS software for PC system m an u factu rers. After th e h ard ware an d th e BIOS of th e IBM PC were d u p licated , all th at was n eed ed to p rod u ce a fu lly IBM-com p atible system was DOS. Reverse en gin eerin g DOS even with th e clean room ap p roach wou ld h ave been a d au n tin g task, becau se DOS is m u ch larger th an th e BIOS, an d con sists of m an y m ore p rogram s an d fu n ction s. Also, th e op eratin g system h as evolved an d ch an ged m ore often th an th e BIOS, wh ich by com p arison h as rem ain ed relatively con stan t. Th is m ean s th at th e on ly way to get DOS on an IBM com p atible wou ld be to licen se it. Th is is wh ere Microsoft com es in . Becau se IBM (wh o h ired Microsoft to write DOS in th e first p lace) d id n ot force Microsoft to sign an exclu sive licen se agreem en t, Microsoft was free to sell th e sam e DOS to an ybod y. W ith a licen sed cop y of MS-DOS, th e last p iece was in p lace an d th e flood gates were op en for IBMcom p atible system s to be p rod u ced wh eth er IBM liked it or n ot.

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Chapter 2—PC Components, Features, and System Design

In retrosp ect, th is is exactly wh y th ere are n o clon es or com p atibles of th e Ap p le Macin tosh system . It is n ot th at Mac system s can n ot be d u p licated ; in fact, th e Mac h ard ware is fairly sim p le an d easy to p rod u ce u sin g off-th e-sh elf p arts. Th e real p roblem is th at Ap p le own s th e MAC OS, an d becau se th ey h ave seen fit n ot to licen se it, n o oth er com p an y can sell an Ap p le-com p atible system . Also, th e Mac BIOS an d OS are very tigh tly in tegrated ; th eir BIOS is very large, com p lex, an d is essen tially a p art of th e OS. Th is h as allowed both th eir BIOS an d OS to escap e an y clean room d u p lication efforts, so with ou t th eir blessin g (licen sin g), n o Mac clon es are likely to ever exist. Becau se IBM d id n ot own DOS (or W in d ows) bu t licen sed it n on -exclu sively from Microsoft, an ybod y else wh o wan ted to p u t MS-DOS or W in d ows on th eir system cou ld licen se th e cod e from Microsoft. Th is allowed an y com p an y wh o wan ted to d evelop an IBM-com p atible system to circu m ven t IBM com p letely, an d p rod u ce a fu n ction ally id en tical m ach in e wh eth er IBM liked it or n ot. Becau se p eop le d esire backward com p atibility, wh en on e com p an y con trols th e op eratin g system , th ey n atu rally con trol all th e software th at goes arou n d it, in clu d in g everyth in g from d rivers to ap p lication p rogram s. As lon g as we u se PCs with Microsoft op eratin g system s, th ey will h ave th e u p p er h an d in con trollin g PC software. W ho Cont rols PC Hardw are? Alth ou gh it is clear th at Microsoft h as always con trolled PC software by virtu e of th eir con trol over th e PC op eratin g system , wh at abou t h ard ware? It is easy to see th at IBM con trolled th e PC h ard ware stan d ard u p th rou gh 1987. After all, IBM in ven ted th e core PC m oth erboard d esign , exp an sion bu s slot arch itectu re (8/ 16-bit ISA bu s), serial an d p arallel p ort d esign , vid eo card d esign th rou gh VGA an d XGA stan d ard s, flop p y an d h ard d isk in terface an d con troller d esign s, p ower su p p ly d esign , keyboard in terface an d d esign , m ou se in terface, an d even th e p h ysical sh ap es (form factors) of everyth in g from th e m oth erboard to th e exp an sion card s, p ower su p p lies, an d system ch assis. All th ese p re1987 IBM d esign featu res are still in flu en cin g m od ern system s tod ay. Bu t th e real q u estion is wh at com p an y h as been resp on sible for creatin g an d in ven tin g n ew PC h ard ware d esign s, in terfaces, an d stan d ard s? W h en I ask th at q u estion , I n orm ally see som e h esitation in th e resp on se—som e p eop le say Microsoft (bu t th ey con trol th e software n ot th e h ard ware), som e say Com p aq or n am e a few oth er big n am e system m an u factu rers, an d a few su rm ise th e correct an swer—In tel. I can see wh y m an y p eop le d on ’t im m ed iately realize th is, I m ean h ow m an y p eop le actu ally own an In tel PC? No, n ot ju st on e th at says “in tel in sid e” on it (wh ich refers on ly to th e system h avin g an In tel p rocessor), bu t I m ean a system th at was d esign ed an d bu ilt by In tel or even p u rch ased th rou gh th em . Believe it or n ot, I wou ld say th at m ost p eop le tod ay do h ave In tel PCs! Certain ly th at d oes n ot m ean th at th ey p u rch ased th eir system s from In tel, becau se it is well kn own th at In tel d oes n ot sell com p lete PCs. You can n ot cu rren tly ord er a system from In tel, n or p u rch ase an In tel bran d system from som ebod y else. W h at I am talkin g abou t is th e m oth erboard . In m y op in ion , th e sin gle m ost im p ortan t p art in a system is

What Is a PC?

th e m oth erboard , an d I’d say th at wh oever m ad e you r m oth erboard sh ou ld be con sid ered th e legitim ate m an u factu rer of you r system . ◊◊ See “ M otherboards” p. 167

Th e top tier system m an u factu rers d o m ake th eir own m oth erboard s. Accord in g to Com puter Reseller News m agazin e, th e top th ree d esktop system s m an u factu rers for th e last several years h ave con sisten tly been Com p aq , Packard Bell, an d IBM. Th ese com p an ies d o d esign an d m an u factu re th eir own m oth erboard s, an d m an y oth er system com p on en ts. In som e cases th ey even d esign th eir own ch ip s an d ch ip set com p on en ts for th eir own board s. Alth ou gh sales are h igh for th ese in d ivid u al com p an ies, th ere is a larger overall segm en t of th e m arket th at can be called th e secon d tier. In th e secon d tier we fin d com p an ies wh o d o n ot really m an u factu re system s bu t assem ble th em . Th at is, th ey p u rch ase m oth erboard s, cases, p ower su p p lies, d isk d rives, p erip h erals, an d so on , an d assem ble an d m arket th e com p on en ts togeth er as com p lete system s. Dell, Gateway, an d Micron are som e of th e larger system assem blers tod ay, bu t th ere are h u n d red s m ore wh o can be listed . In overall total volu m e, th is en d s u p bein g th e largest segm en t of th e PC m arketp lace tod ay. W h at is in terestin g abou t th e secon d tier system s is th at with very few excep tion s, you an d I can p u rch ase th e sam e m oth erboard s an d oth er com p on en ts an y of th e secon d tier m an u factu rers can (alth ou gh we will p ay m ore th an th ey d o). W e can also assem ble a virtu ally id en tical system from scratch ou rselves, bu t th at is a story for an oth er ch ap ter, an d is covered in Ch ap ter 16, “Bu ild in g or Up grad in g System s.” If Gateway, Dell, Micron , an d oth ers d o n ot m an u factu re th eir own m oth erboard s, th en wh o d oes? You gu essed it—In tel. Not on ly d o th ose sp ecific com p an ies u se p retty m u ch exclu sively In tel m oth erboard s, if you ch eck arou n d you ’ll fin d tod ay th at m ost of th e system s on th e m arket in th e secon d tier com e with In tel m oth erboard s. I ju st ch ecked a review of 10 Pen tiu m II system s in th e cu rren t Com puter Shopper m agazin e, an d I’m n ot kid d in g, eigh t ou t of th e 10 system s th ey evalu ated h ad In tel m oth erboard s. In fact, th ose eigh t u sed th e exact sam e In tel m oth erboard . Th at m ean s th at th ese system s d iffer on ly in th e cosm etics of th e exterior case assem bly an d by wh at vid eo card , d isk d rives, keyboard s, an d so on th e assem bler u sed th at week. Th e oth er two system s in th e review h ad board s from m an u factu rers oth er th an In tel, bu t even th ose board s u sed In tel Pen tiu m II p rocessors an d In tel m oth erboard ch ip sets, wh ich togeth er com p rise m ore th an 90% of th e m oth erboard cost. ◊◊ See “ Pentium II,” p. 140 ◊◊ See “ Chipsets,” p. 183

How an d wh en d id th is h ap p en ? Of cou rse, In tel h as always been th e d om in an t PC p rocessor su p p lier sin ce IBM ch ose th e In tel 8088 CPU in th e origin al IBM PC in 1981. By con trollin g th e p rocessor th ey n atu rally h ad con trol of th e ch ip s n eed ed to in tegrate

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Chapter 2—PC Components, Features, and System Design

th eir p rocessors in to system d esign s. Th is n atu rally led In tel in to th e ch ip set bu sin ess. Th ey started th eir ch ip set bu sin ess in 1989 with th e 82350 EISA (Exten d ed In d u stry Stan d ard Arch itectu re) ch ip set, an d by 1993 h ad becom e th e largest volu m e m ajor m oth erboard ch ip set su p p lier. Now I im agin e th em sittin g th ere th in kin g th at th ey m ake th e p rocessor, an d n ow all th e oth er ch ip s n eed ed to p rod u ce a m oth erboard , so wh y n ot ju st elim in ate th e m id d le m an an d m ake th e en tire m oth erboard too? Th e an swer to th is, an d a real tu rn in g p oin t in th e in d u stry, cam e abou t in 1994 wh en In tel becam e th e largest-volu m e m oth erboard m an u factu rer in th e world . An d th ey h ave rem ain ed solid ly on top ever sin ce. Th ey d on ’t ju st lead in th is category by an y sm all m argin ; in fact, d u rin g 1996 In tel m ad e m ore m oth erboard s th an th e n ext five largest m oth erboard m an u factu rers com bined, with sales of m ore th an 20 m illion board s worth m ore th an $2 billion ! Th ese board s en d u p in th e variou s system assem bler bran d PCs you an d I bu y, m ean in g th at m ost of u s are n ow essen tially p u rch asin g In tel-m an u factu red system s, n o m atter wh o actu ally wield ed th e screwd river. W ith ou t a d ou bt, In tel con trols th e PC h ard ware stan d ard becau se th ey con trol th e PC m oth erboard . Th ey m ake n ot on ly th e vast m ajority of m oth erboard s bein g u sed in system s tod ay, bu t th ey also su p p ly th e vast m ajority of p rocessors an d m oth erboard ch ip sets to oth er m oth erboard m an u factu rers. Th is m ean s th at even if you d on ’t h ave an actu al In tel m oth erboard , th e m oth erboard you d o h ave p robably h as an In tel p rocessor an d / or ch ip set. In tel also h as a h an d in settin g several of th e m ore recen t PC h ard ware stan d ard s. It was In tel wh o origin ally created th e PCI (Perip h eral Com p on en t In tercon n ect) local bu s in terface an d th e n ew AGP (Accelerated Grap h ics Port) in terface for h igh p erform an ce vid eo card s. In tel d esign ed th e ATX m oth erboard form factor th at rep laces th e (som ewh at lon g in th e tooth ) IBM-d esign ed Baby-AT form factor u sed sin ce th e early ’80s. In tel also created th e NLX m oth erboard form factor to rep lace th e p rop rietary an d lim ited LPX d esign u sed by m an y lower-cost system s, wh ich fin ally brou gh t m oth erboard u p grad eability to th ose system s. In tel also created th e DMI (Desktop Man agem en t In terface) for m on itorin g system h ard ware fu n ction s, an d th e DPMA (Dyn am ic Power Man agem en t Arch itectu re) an d APM (Ad van ced Power Man agem en t) stan d ard s for m an agin g p ower u sage in th e PC. It was In tel wh o h as p u sh ed for ad van cem en ts in m oth erboard ch ip sets, su p p ortin g n ew typ es of m em ory, su ch as EDO (Exten d ed Data Ou t), SDRAM (Syn ch ron ou s Dyn am ic RAM), an d RDRAM (Ram bu s Dyn am ic RAM); n ew an d faster bu s in terfaces; an d faster m em ory access. Th ey are also h avin g a m ajor effect in th e p ortable m arket, brin gin g ou t sp ecial low-p ower p rocessors, ch ip sets, an d m obile m od u les (com bin in g p rocessor an d ch ip set togeth er on a d au gh ter board ) to ease p ortable system d esign an d im p rove fu n ction ality an d p erform an ce. It d oesn ’t take m u ch to see th at In tel is clearly in as m u ch con trol of th e PC h ard ware stan d ard as Microsoft is in con trol of th e PC software stan d ard . W h oever con trols th e op eratin g system con trols th e software for th e PC, an d wh oever con trols th e p rocessor, an d th erefore th e m oth erboard , con trols th e h ard ware. Becau se it

System Types

seem s to be a Microsoft an d In tel com bin ation for th e software an d h ard ware con trol in th e PC tod ay, it is n o won d er th e m od ern PC is often called a W in tel system . PC 9x Specificat ions Even th ou gh In tel h as fu ll con trol of PC h ard ware, Microsoft recogn izes th eir p ower over th e PC from th e op eratin g system p ersp ective an d h as been releasin g a series of d ocu m en ts called th e “PC 9x Design Gu id es” as a set of stan d ard sp ecification s to gu id e both h ard ware an d software d evelop ers creatin g p rod u cts th at work with W in d ows. Th e req u irem en ts in th ese gu id es are p art of Microsoft’s “Design ed for W in d ows” logo req u irem en t. In oth er word s, if you p rod u ce eith er a h ard ware or software p rod u ct an d you wan t th e official “Design ed for W in d ows” logo to be on you r box, th en you r p rod u ct h as to m eet th e PC 9x m in im u m req u irem en ts. Th e d ocu m en ts p rod u ced so far are th e followin g: ■ Hardware Design Guide for Microsoft W indows 95 ■ Hardware Design Guide Supplem ent for PC 95 ■ PC 97 Hardware Design Guide ■ PC 98 System Design Guide ■ PC 99 System Design Guide All of th ese are available for d own load from Microsoft’s W eb site an d h ave also been available as books from Microsoft Press. Th ese system d esign gu id es p resen t in form ation for en gin eers wh o bu ild p erson al com p u ters, exp an sion card s, an d p erip h eral d evices th at will be u sed with W in d ows 95, 98, an d NT op eratin g system s. Th e req u irem en ts an d recom m en d ation s for PC d esign in th ese gu id es form th e basis for req u irem en ts for th e “Design ed for Microsoft W in d ows” logo p rogram for h ard ware th at Microsoft sp on sors. Th ese gu id es in clu d e req u irem en ts for basic (d esktop an d m obile) system s, workstation s, an d even en tertain m en t PCs. Th ey also ad d ress Plu g-an d -Play d evice con figu ration an d p ower m an agem en t in PC system s, req u irem en ts for u n iversal serial bu s (USB) an d IEEE 1394, an d n ew d evices su p p orted u n d er W in d ows, in clu d in g n ew grap h ics an d vid eo d evice cap abilities, DVD, scan n ers an d d igital cam eras, an d oth er d evices.

Syst em Types W e can break PCs d own in to m an y d ifferen t categories. I like to break th em d own two d ifferen t ways—on e by th e typ e of software th ey can ru n , th e oth er by th e m oth erboard h ost bu s, or p rocessor bu s d esign an d wid th . Becau se th is book con cen trates m ain ly on h ard ware, let’s look at th at first. W h en a p rocessor read s d ata, th e d ata m oves in to th e p rocessor via th e p rocessor’s extern al d ata bu s con n ection . Th e p rocessor’s d ata bu s is d irectly con n ected to th e p rocessor

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h ost bu s on th e m oth erboard . Th e p rocessor d ata bu s or h ost bu s is also som etim es referred to as th e local bu s becau se it is local to th e p rocessor th at is con n ected d irectly to it. An y oth er d evices con n ected to th e h ost bu s essen tially ap p ear as if th ey are d irectly con n ected to th e p rocessor as well. If th e p rocessor h as a 32-bit d ata bu s, th en th e m oth erboard m u st be wired to h ave a 32-bit p rocessor h ost bu s. Th is wou ld m ean th at th e system cou ld m ove 32-bits worth of d ata in to or ou t of th e p rocessor in a sin gle cycle. Differen t p rocessors h ave d ifferen t d ata bu s wid th s, an d th e m oth erboard s d esign ed to accep t th em wou ld req u ire a p rocessor h ost bu s with a m atch in g wid th . Table 2.1 lists all th e In tel p rocessors an d th eir d ata bu s wid th s. Table 2.1

Int el Processors and Their Dat a Bus W idt hs

Processor

Dat a Bus W idt h

8088

8-bit

8086

16-bit

286

16-bit

386SX

16-bit

386SL

16-bit

386DX

32-bit

486SX

32-bit

486SX2

32-bit

487SX

32-bit

486DX

32-bit

486DX2

32-bit

486DX4

32-bit

486Pentium OD

32-bit

Pentium 60/ 66

64-bit

Pentium 75-200

64-bit

Pentium M M X

64-bit

Pentium Pro

64-bit

Pentium II

64-bit

A com m on m iscon cep tion arises wh en d iscu ssin g p rocessor wid th s. Alth ou gh th e Pen tiu m p rocessors all h ave 64-bit d ata bu s wid th s, th eir in tern al registers are on ly 32 bits wid e an d th ey p rocess 32-bit com m an d s an d in stru ction s. Th u s, from a software p oin t-of-view, all ch ip s from th e 386 to th e Pen tiu m II h ave 32-bit registers an d execu te 32-bit in stru ction s. From th e electron ic or p h ysical p ersp ective, th ese 32-bit software cap able p rocessors h ave been available in p h ysical form s with 16-bit (386SX), 32-bit (386DX, 486), an d 64-bit (Pen tiu m ) d ata bu s wid th s. Th e d ata bu s wid th is th e m ajor factor in m oth erboard an d m em ory system d esign as th at d ictates h ow m an y bits m ove in an d ou t of th e ch ip in on e cycle.

System Types

Th e fu tu re P7 p rocessor, cod e-n am ed Merced , will h ave a n ew 64-bit in stru ction set bu t will also p rocess th e sam e 32-bit in stru ction s as 386 th rou gh Pen tiu m p rocessors d o. It is n ot kn own wh eth er Merced will h ave a 64-bit d ata bu s like th e Pen tiu m or wh eth er it will in clu d e a 128-bit d ata bu s as som e su sp ect. ◊◊ See “ Processor Specifications,” p. 31

From Table 2.1 you can see th at 486 system s h ave a 32-bit p rocessor bu s, wh ich wou ld m ean th at an y 486 m oth erboard wou ld h ave a 32-bit p rocessor h ost bu s. Pen tiu m p rocessors, wh eth er th ey are th e origin al Pen tiu m , Pen tiu m MMX, Pen tiu m Pro, or even th e Pen tiu m II, all h ave 64-bit d ata bu sses, wh ich m ean s th at Pen tiu m m oth erboard s h ave a 64-bit p rocessor h ost bu s. You can n ot p u t a 64-bit p rocessor on a 32-bit m oth erboard , wh ich is on e reason th at 486 m oth erboard s can n ot accep t tru e Pen tiu m p rocessors. As you can see from th is table we can break system s d own in to th e followin g h ard ware categories: ■ 8-bit ■ 16-bit ■ 32-bit ■ 64-bit W h at is in terestin g is th at besid es th e bu s wid th , th e 16-bit th rou gh 64-bit system s are rem arkably sim ilar in basic d esign an d arch itectu re. Th e old er 8-bit system s are very d ifferen t, h owever. Th is gives u s two basic system typ es, or classes, of h ard ware: ■ 8-bit (PC/ XT-class) system s ■ 16/ 32/ 64-bit (AT-class) system s PC stan d s for personal com puter, X T stan d s for an eX Tended PC, an d AT stan d s for an advanced technology PC. Th e term s PC, X T, an d AT as u sed h ere are taken from th e origin al IBM system s of th ose n am es. Th e XT basically was a PC system th at in clu d ed a h ard d isk for storage in ad d ition to th e flop p y d rive(s) fou n d in th e basic PC system . Th ese system s h ad an 8-bit 8088 p rocessor an d an 8-bit In d u stry Stan d ard Arch itectu re (ISA) Bu s for system exp an sion . Th e bus is th e n am e given to exp an sion slots in wh ich ad d ition al p lu g-in circu it board s can be in stalled . Th e 8-bit d esign ation com es from th e fact th at th e ISA Bu s fou n d in th e PC/ XT class system s can sen d or receive on ly 8 bits of d ata in a sin gle cycle. Th e d ata in an 8-bit bu s is sen t alon g eigh t wires sim u ltan eou sly, in p arallel. ◊◊ See “ The ISA Bus,” p. 233

16-bit an d greater system s are said to be AT-class, wh ich in d icates th at th ey follow certain stan d ard s an d follow th e basic d esign first set forth in th e origin al IBM AT system .

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AT is th e d esign ation IBM ap p lied to system s th at first in clu d ed m ore ad van ced 16-bit (an d later, 32- an d 64-bit) p rocessors an d exp an sion slots. AT-class system s m u st h ave an y p rocessor th at is com p atible with In tel 286 or h igh er p rocessors (in clu d in g th e 386, 486, Pen tiu m , Pen tiu m Pro, an d Pen tiu m II p rocessors) an d m u st h ave a 16-bit or greater system bu s. Th e system bu s arch itectu re is cen tral to th e AT system d esign alon g with th e basic m em ory arch itectu re, In terru p t ReQu est (IRQ), DMA (Direct Mem ory Access), an d I/ O p ort ad d ress d esign . All AT-class system s are sim ilar in th e way th ese resou rces are allocated an d h ow th ey fu n ction . Th e first AT-class system s h ad a 16-bit version of th e ISA Bu s, wh ich is an exten sion of th e origin al 8-bit ISA Bu s fou n d in th e PC/ XT-class system s. Even tu ally, several exp an sion slot or bu s d esign s were d evelop ed for AT-class system s, in clu d in g th ose in th e followin g list: ■ 16-bit ISA bu s ■ 16/ 32-bit Exten d ed ISA (EISA) bu s ■ 16/ 32-bit PS/ 2 Micro Ch an n el Arch itectu re (MCA) bu s ■ 16-bit PC-Card (PCMCIA) bu s ■ 32-bit Card bu s (PCMCIA) bu s ■ 32-bit VESA Local (VL) bu s ■ 32/ 64-bit Perip h eral Com p on en t In tercon n ect (PCI) bu s ■ 32-bit Accelerated Grap h ics Port (AGP) A system with an y of th ese typ es of exp an sion slots is by d efin ition an AT-class system , regard less of th e actu al In tel or In tel-com p atible p rocessor u sed . AT-typ e system s with 386 or h igh er p rocessors h ave sp ecial cap abilities n ot fou n d in th e first gen eration of 286-based ATs. Th e 386 an d h igh er system s h ave d istin ct cap abilities regard in g m em ory ad d ressin g, m em ory m an agem en t, an d p ossible 32- or 64-bit wid e access to d ata. Most system s with 386DX or h igh er ch ip s also h ave 32-bit bu s arch itectu res to take fu ll ad van tage of th e 32-bit d ata tran sfer cap abilities of th e p rocessor. Most PC system s tod ay in corp orate 16-bit ISA slots for backward com p atibility an d lower fu n ction ad ap ters, an d PCI slots for tru ly h igh p erform an ce ad ap ters. Most p ortable system s u se PC-Card an d Card bu s slots in th e p ortable u n it, an d ISA an d PCI slots in op tion al d ockin g station s. Ch ap ter 4, “Moth erboard s an d Bu ses,” con tain s a great d eal of in -d ep th in form ation on th ese an d oth er PC system bu ses, in clu d in g tech n ical in form ation su ch as p in ou ts, p erform an ce sp ecification s, an d bu s op eration an d th eory. Table 2.2 su m m arizes th e p rim ary d ifferen ces between th e old er 8-bit (PC/ XT) system s an d a m od ern AT system . Th is in form ation d istin gu ish es between th ese system s an d in clu d es all IBM an d com p atible m od els.

System Components

Table 2.2

Differences Bet w een PC/ XT and AT Syst em s

Syst em At t ribut es

( 8-bit ) PC/ XT Type

( 16/ 32/ 64-bit ) AT Type

Supported processors

All x86 or x88

286 or higher

Processor modes

Real

Real/ Protected/ Virtual Real

Software supported

16-bit only

16- or 32-bit

Bus slot width

8-bit

16/ 32/ 64-bit

Slot type

ISA only

ISA, EISA, M CA, PC-Card, Cardbus, VL-Bus, PCI

Hardware interrupts

8 (6 usable)

16 (11 usable)

DM A channels

4 (3 usable)

8 (7 usable)

M aximum RAM

1M

16M / 4G or more

Floppy controller speed

250 Kbit/ sec

250/ 300/ 500/ 1,000 Kbit/ sec

Standard boot drive

360K or 720K

1.2M / 1.44M / 2.88M

Keyboard interface

Unidirectional

Bidirectional

CM OS memory/ clock

None standard

M C146818-compatible

Serial-port UART

8250B

16450/ 16550A

Th e easiest way to id en tify a PC/ XT (8-bit) system is by th e 8-bit ISA exp an sion slots. No m atter wh at p rocessor or oth er featu res th e system h as, if all th e slots are 8-bit ISA, th en th e system is a PC/ XT. AT (16-bit p lu s) system s can be sim ilarly id en tified by h avin g 16bit or greater slots of an y typ e. Th ese cou ld be ISA, EISA, MCA, PC-Card (form erly PCMCIA), Card bu s, VL-Bu s, or PCI. Usin g th is in form ation , you can p rop erly categorize virtu ally an y system as a PC/ XT typ e or an AT typ e. Th ere really h ave been n o PC/ XT typ e (8-bit) system s m an u factu red for m an y years. Un less you are in a com p u ter m u seu m , virtu ally every system you wou ld en cou n ter tod ay is based on th e AT typ e d esign .

Syst em Com ponent s A m od ern PC is both sim p le an d com p licated . It is sim p le in th e sen se th at over th e years m an y of th e com p on en ts u sed to con stru ct a system h ave becom e in tegrated with oth er com p on en ts in to fewer an d fewer actu al p arts. It is com p licated in th e sen se th at each p art in a m od ern system p erform s m an y m ore fu n ction s th an th e sam e typ es of p arts in old er system s. In th is section , we briefly exam in e all th e com p on en ts in a m od ern PC system . Each of th ese com p on en ts will be exp an d ed on in later ch ap ters. Here are th e com p on en ts n eed ed to assem ble a basic m od ern PC system : ■ Moth erboard ■ Processor ■ Mem ory (RAM)

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Chapter 2—PC Components, Features, and System Design

■ Case (ch assis) ■ Power su p p ly ■ Flop p y d rive ■ Hard d isk ■ CD-ROM d rive ■ Keyboard ■ Mou se ■ Vid eo card ■ Mon itor (d isp lay) ■ Sou n d card ■ Sp eakers M ot herboard Th e m oth erboard is th e core of th e system . It really is th e PC, everyth in g else is con n ected to it, an d it con trols everyth in g in th e system . Moth erboard s are available in several d ifferen t sh ap es or form factors. Th e m oth erboard u su ally con tain s th e followin g in d ivid u al com p on en ts: ■ Processor socket (or slot) ■ Processor voltage regu lators ■ Moth erboard ch ip set ■ Level 2 cach e ■ Mem ory SIMM or DIMM sockets ■ Bu s slots ■ ROM BIOS ■ Clock/ CMOS battery ■ Su p er I/ O ch ip Th e ch ip set con tain s all th e p rim ary circu itry th at m akes u p th e m oth erboard , in essen ce th e ch ip set is th e m oth erboard . Th e ch ip set con trols th e CPU or p rocessor bu s, th e L2 cach e an d m ain m em ory, th e PCI (Perip h eral Com p on en t In tercon n ect) bu s, th e ISA (In d u stry Stan d ard Arch itectu re) bu s, system resou rces, an d m ore. If th e p rocessor rep resen ts th e en gin e of you r system , th en th e ch ip set rep resen ts th e ch assis in wh ich th e en gin e is in stalled . As su ch , th e ch ip set d ictates th e p rim ary featu res an d sp ecification s of you r m oth erboard , in clu d in g wh at typ es of p rocessors, m em ory, exp an sion card s, d isk d rives, an d so on . th e system su p p orts. Th e ROM BIOS con tain s th e in itial POST (Power-On Self Test) p rogram , bootstrap load er (wh ich load s th e op eratin g system ), d rivers for item s bu ilt-in to th e board (th e actu al

System Components

BIOS cod e), an d u su ally a system setu p p rogram (often called CMOS setu p or BIOS setu p ) for con figu rin g th e system . Moth erboard s are covered in d etail in Ch ap ter 4. Processor Th e p rocessor is often th ou gh t of as th e “en gin e” of th e com p u ter. Also called th e CPU (Cen tral Processin g Un it), it is th e sin gle m ost im p ortan t ch ip in th e system , as it is th e p rim ary circu it th at carries ou t th e p rogram in stru ction s of wh atever software is bein g ru n . Mod ern p rocessors con tain literally m illion s of tran sistors etch ed on to a tin y sq u are of silicon called a d ie, wh ich is abou t th e size of you r th u m bn ail. Th e p rocessor h as th e d istin ction of bein g on e of th e m ost exp en sive p arts of m ost com p u ters, even th ou gh it is on e of th e sm allest p arts. In m ost m od ern system s, th e p rocessor costs from two to ten tim es th e cost of th e m oth erboard it is p lu gged in to. Microp rocessors are covered in d etail in Ch ap ter 3, “Microp rocessor Typ es an d Sp ecification s.” M em ory ( RAM ) Th e system m em ory is often called RAM for Ran d om Access Mem ory. Th is is th e p rim ary m em ory th at h old s all th e p rogram s an d d ata th e p rocessor is u sin g at a given tim e. RAM req u ires p ower to m ain tain storage, so wh en you tu rn off th e com p u ter everyth in g in RAM is cleared , an d wh en you tu rn it back on th e m em ory m u st be reload ed with p rogram s for th e p rocessor to ru n . Th e in itial p rogram s for th e p rocessor com e from a sp ecial typ e of m em ory called ROM (Read On ly Mem ory), wh ich can n ot n orm ally be erased . Th is con tain s in stru ction s to get th e system to load an op eratin g system an d oth er p rogram s from on e of th e d isk d rives in to th e m ain m em ory so th at th e system can be ru n n in g n orm ally an d p erform u sefu l work. Newer op eratin g system s allow several p rogram s to ru n at on e tim e, with each p rogram or d ata file load ed u sin g som e of th e m em ory. Gen erally, th e m ore m em ory you r system h as, th e m ore p rogram s you can ru n sim u ltan eou sly. Mem ory is n orm ally p u rch ased an d in stalled in a m od ern system in SIMM (Sin gle In lin e Mem ory Mod u le) or DIMM (Du al In lin e Mem ory Mod u le) form . Form erly very exp en sive, m ore recen tly m em ory p rices h ave d rop p ed , sign ifican tly red u cin g th e cost of m em ory as com p ared to oth er p arts of th e system . Even so, th e cost of th e recom m en d ed am ou n t of m em ory for a given system is u su ally eq u al or greater th an th at of th e m oth erboard . Mem ory is covered in d etail in Ch ap ter 5, “Mem ory.” Case ( Chassis) Th e case is th e fram e or ch assis th at h ou ses th e m oth erboard , p ower su p p ly, d isk d rives, ad ap ter card s, an d an y oth er p h ysical com p on en ts in th e system . Th ere are several d ifferen t styles of cases available, from sm all or slim version s th at sit h orizon tally on a d esktop to h u ge tower typ es th at stan d vertically on th e floor, an d even som e th at are d esign ed to be rackm ou n ted for in d u strial u se. In ad d ition to th e p h ysical styles, d ifferen t cases are d esign ed to accep t d ifferen t form factor m oth erboard s an d p ower su p p lies. Som e cases h ave featu res th at m ake in stallin g or rem ovin g com p on en ts easy, su ch as a

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Chapter 2—PC Components, Features, and System Design

screwless d esign th at req u ires n o tools to d issasem ble, sid e op en p an els or trays allowin g easy m oth erboard access, rem ovable cages or brackets th at give easy access to d isk d rives, an d so on . Som e cases in clu d e ad d ition al coolin g fan s for h eavy-d u ty system s, an d som e are even available with air filters to en su re th e in terior rem ain s clean an d d u st free. Most cases in clu d e a p ower su p p ly, h owever, you can also p u rch ase bare cases an d p ower su p p lies sep arately. Th e case is covered in d etail in Ch ap ter 6, “Power Su p p ly an d Case.” Pow er Supply Th e p ower su p p ly is wh at feed s electrical p ower to every sin gle p art in th e PC. As su ch it h as a very im p ortan t job, yet it is on e of th e least glam orou s p arts of th e system , so it receives little atten tion . Un fortu n ately, th is often m ean s it is on e of th e com p on en ts th at is m ost skim p ed on wh en con stru ctin g a system . Th e m ain fu n ction of th e su p p ly is to con vert th e 110v AC wall cu rren t in to th e 3.3v, 5v, an d 12v p ower th at th e system req u ires for op eration . Th e p ower su p p ly is covered in d etail in Ch ap ter 6. Floppy Disk Drive Th e flop p y d rive is a sim p le, in exp en sive, low-cap acity, rem ovable, m ed ia m agn etic storage d evice. For m an y years flop p y d isks were th e p rim ary m ed ia for software d istribu tion an d system backu p . W ith th e ad ven t of CD-ROM an d DVD-ROM d iscs as th e p rim ary m eth od of in stallin g or load in g n ew software in a system , an d in exp en sive h igh -cap acity tap e d rives for backu p , th e flop p y d rive is n ot u sed often in m ost m od ern system s, excep t p erh ap s by a system bu ild er, in staller, or tech n ician . Becau se th e flop p y d rive is th e first d evice a PC attem p ts to boot from , it is still th e p rim ary m eth od to load in itial op eratin g system s startu p software as well as core h ard ware d iagn ostics. Recen tly som e ad van cem en ts in tech n ology h ave created n ew typ es of flop p y d rives with as m u ch as 120M or m ore of storage, m akin g th e d rive m u ch m ore u sable for tem p orary backu p s or for m ovin g files from system to system . Flop p y d isk d rives are covered in d etail in Ch ap ter 12, “Magn etic Storage.” Hard Disk Drive Th e h ard d isk is th e p rim ary arch ival storage m em ory for th e system . It is u sed to con tain cop ies of all p rogram s an d d ata n ot cu rren tly active in m ain m em ory. A h ard d rive is so n am ed becau se it con sists of sp in n in g p latters of alu m in u m or ceram ic th at are coated with a m agn etic m ed ia. Th e p latters com e in variou s sizes, an d by th e d en sity, size, an d n u m ber of p latters, h ard d rives can be created with m an y d ifferen t storage cap acities. Most d esktop system s tod ay u se d rives with 3 1/ 2-in ch p latters, wh ile m ost lap top or n otebook com p u ters u se 2 1/ 2-in ch p latter d rives. Hard d isk d rives are also covered in d etail in Ch ap ter 12. CD-ROM Drive CD- (Com p act Disc) an d DVD- (Digital Versatile Disc) ROM (Read On ly Mem ory) d rives are relatively h igh -cap acity, rem ovable, m ed ia op tical d rives. Th ey are p rim arily a

System Components

read -on ly m ed iu m , wh ich m ean s th e d rives can on ly read in form ation , an d th e d ata on th e d iscs can n ot be altered or rewritten . Th ere are writeable or rewriteable version s of th e d iscs an d d rives available, bu t th ese are m u ch m ore exp en sive th an th eir read -on ly cou n terp arts an d th erefore are n ot stan d ard in m ost PCs. CD-ROM an d DVD-ROM are th e m ost p op u lar m ed ia for d istribu tin g software or large am ou n ts of d ata, becau se th ey are in exp en sive wh en p rod u ced in q u an tity an d th ey can h old a great d eal of in form ation . CD-ROM d rives are covered in d etail in Ch ap ter 13, “Op tical Storage.” Keyboard Th e keyboard is th e p rim ary d evice on a PC u sed by a h u m an bein g to com m u n icate with an d to con trol a system . Keyboard s are available in m an y d ifferen t lan gu ages, layou ts, sizes, sh ap es, an d with n u m erou s sp ecial featu res or ch aracteristics. On e of th e best featu res of th e PC as d esign ed by IBM is th at it was on e of th e first p erson al com p u ters to u se a d etach ed keyboard . Most system s p rior to th e PC h ad th e keyboard as an in tegral p art of th e system ch assis, wh ich severely lim ited flexibility. Becau se th e PC u ses a d etach ed keyboard with a stan d ard ized con n ector an d sign al d esign , in m ost cases it is p ossible to con n ect an y PC-com p atible keyboard you like to you r system . Th is gives you th e freed om to ch oose th e on e th at su its you best. Keyboard s are covered in d etail in Ch ap ter 7, “In p u t Devices.” M ouse W ith th e ad ven t of com p u ter op eratin g system s th at u sed a Grap h ical User In terface (GUI), it becam e n ecessary to h ave a d evice th at en abled a u ser to p oin t at or select item s sh own on th e screen . W h ile th ere are m an y d ifferen t typ es of p oin tin g d evices on th e m arket tod ay, th e first an d m ost p op u lar d evice is th e m ou se. By m ovin g th e m ou se across a d esk or tabletop , a corresp on d in g p oin ter can be m oved across th e com p u ter screen , allowin g item s to be m ore easily selected or m an ip u lated th an by u sin g a keyboard alon e. Stan d ard m ice as u sed on PCs h ave two bu tton s, on e u sed for selectin g item s u n d er th e p oin ter an d th e oth er for activatin g m en u s. Mice are also available with a th ird bu tton , wh eel, or stick th at can be u sed to scroll th e d isp lay or for oth er sp ecial fu n ction s. Th e m ou se is covered in d etail in Ch ap ter 7. Video Card Th e vid eo card con trols th e in form ation you see on th e m on itor. All vid eo card s h ave fou r basic p arts—a vid eo ch ip or ch ip set, Vid eo RAM, a DAC (Digital to An alog Con verter), an d a BIOS. Th e vid eo ch ip is wh at actu ally con trols th e in form ation on th e screen by writin g d ata to th e vid eo RAM. Th e DAC read s th e vid eo RAM an d con verts th e d igital d ata th ere in to an alog sign als to d rive th e m on itor. Th e BIOS h old s th e p rim ary vid eo d river th at allows th e d isp lay to fu n ction d u rin g boot tim e an d at a DOS p rom p t in basic text m od e. More en h an ced d rivers are th en u su ally load ed from d isk to en able ad van ced vid eo m od es for W in d ows or ap p lication s software. Vid eo card s are covered in d etail in Ch ap ter 8, “Vid eo Hard ware.”

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Chapter 2—PC Components, Features, and System Design

M onit or ( Display) In m ost system s, th e m on itor is h ou sed in its own p rotective case, sep arate from th e system case an d ch assis. In p ortable system s an d som e low-cost PCs, th e m on itor is bu ilt in to th e system case. Mon itors are gen erally classified by th ree criteria—d iagon al size in in ch es, resolu tion in p ixels, an d refresh rate in h ertz (Hz). Desktop m on itors u su ally ran ge from 14" to 21" d iagon al m easu re (alth ou gh as you will see in Ch ap ter 8, th e actu al viewable area is sm aller th an th e ad vertised m easu re) an d LCD m on itors in p ortable system s ran ge from 11" to 14". Resolu tion ran ges from 640×480 p ixels (h orizon tal m easu rem en t first, th en vertical) to 1600×1200 p ixels. Each p ixel in th e m on itor is m ad e u p of a trio of d ots, on e each for th e colors red , blu e, an d green . An average m on itor is cap able of refresh in g 60 tim es p er secon d (60 Hz) wh ile h igh er q u ality m on itors m ay refresh at 100 Hz. Th e refresh rate m easu res h ow often th e d isp lay of th e screen is red rawn from th e con ten ts of th e vid eo ad ap ter m em ory. Both resolu tion an d refresh rate of th e m on itor are tied to th e cap ability of th e system vid eo ad ap ter. Most m on itors are cap able of su p p ortin g several d ifferen t resolu tion s an d refresh rates (with th e com m on excep tion of LCD screen s in p ortables). Mon itors are covered in d etail in Ch ap ter 8.

Chapter 3

3

M icroprocessor Types and Specifications

Th e brain or en gin e of th e PC is th e p rocessor (som etim es called m icrop rocessor), or Central Processing Unit (CPU). Th e CPU p erform s th e system ’s calcu latin g an d p rocessin g. Th e p rocessor is easily th e m ost exp en sive sin gle com p on en t in th e system , costin g u p to fou r or m ore tim es greater th an th e m oth erboard it p lu gs in to. In tel is gen erally cred ited with in ven tin g th e m icrop rocessor in 1971 an d th ey h ave alm ost total con trol over th at m arket tod ay, at least for PC system s. Th is m ean s th at all PC-com p atible system s u se eith er In tel p rocessors or p rocessors from a h an d fu l of com p etitors (su ch as AMD or Cyrix).

Th e followin g section s cover th e d ifferen t typ es of p rocessor ch ip s th at h ave been u sed in p erson al com p u ters sin ce th e first PC was in trod u ced alm ost two d ecad es ago. Th ese section s p rovid e a great d eal of tech n ical d etail abou t th ese ch ip s an d exp lain wh y on e typ e of CPU ch ip can d o m ore work th an an oth er in a given p eriod of tim e.

Processor Specificat ions Man y con fu sin g sp ecification s often are q u oted in d iscu ssion s of p rocessors. Th e followin g section s d iscu ss som e of th ese sp ecification s, in clu d in g th e d ata bu s, ad d ress bu s, an d sp eed . Th e n ext section in clu d es a table th at lists th e sp ecification s of virtu ally all PC p rocessors. Processors can be id en tified by two m ain p aram eters: h ow wide th ey are an d h ow fast th ey are. Th e sp eed of a p rocessor is a fairly sim p le con cep t. Sp eed is cou n ted in m egah ertz (MHz), wh ich m ean s m illion s of cycles p er secon d , an d faster is better! Th e wid th of a p rocessor is a little m ore com p licated to d iscu ss becau se th ere are th ree m ain sp ecification s in a p rocessor th at are exp ressed in wid th . Th ey are ■ Data in p u t an d ou tp u t bu s ■ In tern al registers ■ Mem ory ad d ress bu s

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Chapter 3—M icroprocessor Types and Specifications

Table 3.1 lists th e p rim ary sp ecification s for th e In tel fam ily of p rocessors u sed in IBM an d com p atible PCs. Th e followin g section s exp lain th ese sp ecification s in d etail. Note th at th e Pen tiu m II p rocessor in clu d es 512K of 1/ 2-core sp eed L2 cach e on th e p rocessor card . Th e tran sistor cou n t figu res d o n ot in clu d e th e stan d ard 256K or 512K Level 2 cach e bu ilt in to th e Pen tiu m Pro an d Pen tiu m II CPU p ackages. Th e L2 cach e con tain s an ad d ition al 15.5 (256K), 31 (512K), or op tion ally 62 m illion (1M) tran sistors! Table 3.1

Int el Processor Specificat ions

Processor

CPU Clock

Volt age

Int ernal Regist er Size

8088

1x

5v

16-bit

Dat a I/ O Bus W idt h

M em ory Address Bus W idt h

M axim um M em ory

8-bit

20-bit

1M

8086

1x

5v

16-bit

16-bit

20-bit

1M

286

1x

5v

16-bit

16-bit

24-bit

16M

386SX

1x

5v

32-bit

16-bit

24-bit

16M

386SL

1x

3.3v

32-bit

16-bit

24-bit

16M

386DX

1x

5v

32-bit

32-bit

32-bit

4G

486SX

1x

5v

32-bit

32-bit

32-bit

4G

486SX2

2x

5v

32-bit

32-bit

32-bit

4G

487SX

1x

5v

32-bit

32-bit

32-bit

4G

486DX

1x

5v

32-bit

32-bit

32-bit

4G

486SL2

1x

3.3v

32-bit

32-bit

32-bit

4G

486DX2

2x

5v

32-bit

32-bit

32-bit

4G

486DX4

2-3x

3.3v

32-bit

32-bit

32-bit

4G

486Pentium OD

2.5x

5v

32-bit

32-bit

32-bit

4G

Pentium 60/ 66

1x

5v

32-bit

64-bit

32-bit

4G

Pentium 75-200

1.5-3x

3.3v3

32-bit

64-bit

32-bit

4G

Pentium M M X

1.5-3x

1.8-2.8v

32-bit

64-bit

32-bit

4G

Pentium Pro

2-3x

3.3v

32-bit

64-bit

36-bit

64G

Pentium II M M X

3.5-5x

1.8-2.8v

32-bit

64-bit

36-bit

64G

Pentium II Celeron

3.5-5x

1.8-2.8v

32-bit

64-bit

36-bit

64G

PII Celeron 300A+

3.5-5x

1.8-2.8v

32-bit

64-bit

36-bit

64G

Pentium II Xeon

3.5-5x

1.8-2.8v

32-bit

64-bit

36-bit

64G

FPU = Floating-Point Unit (internal m ath coprocessor) W T = W rite-Through cache (caches reads only) W B = W rite-Back cache (caches both reads and writes) 1 The 386SL contains an integral-cache controller, but the cache m em ory m ust be provided outside the chip. 2 Intel later m arketed SL Enhanced versions of the SX , DX , and DX 2 processors. These processors were available in both 5v and 3.3v versions and included power-m anagem ent capabilities.

Processor Specifications

Processor Speed Rat ings A com m on m isu n d erstan d in g abou t p rocessors is th eir d ifferen t sp eed ratin gs. Th is section covers p rocessor sp eed in gen eral an d th en p rovid es m ore sp ecific in form ation abou t In tel p rocessors.

3

Level 1 Cache

L1 Cache Type

Level 2 Cache

L2 Cache Speed

Int egral FPU

No. of Transist ors

Dat e Int roduced

-

-

-

-

-

29,000

June ’79

-

-

-

-

-

29,000

June ’78

-

-

-

-

-

134,000

Feb. ’82

-

-

-

-

-

275,000

June ’88

0K1

WT

-

-

-

855,000

Oct. ’90

-

-

-

-

-

275,000

Oct. ’85

8K

WT

-

-

-

1,185,000

April ’91

8K

WT

-

-

-

1,185,000

April ’94

8K

WT

-

-

Yes

1,200,000

April ’91

8K

WT

-

-

Yes

1,200,000

April ’89

8K

WT

-

-

Opt.

1,400,000

Nov. ’92

8K

WT

-

-

Yes

1,100,000

M arch ’92

16K

WT

-

-

Yes

1,600,000

Feb. ’94

2x16K

WB

-

-

Yes

3,100,000

Jan. ’95

2x8K

WB

-

-

Yes

3,100,000

M arch ’93

2x8K

WB

-

-

Yes

3,300,000

Oct. ’94

2x16K

WB

-

-

Yes

4,100,000

Jan. ‘97 Nov. ’95

4

2x8K

WB

256K

Core

Yes

5,500,000

2x16K

WB

512K

1/ 2 Core

Yes

7,500,000

M ay ’97

2x16K

WB

0K

-

Yes

7,500,000

April ’98

2x16K

WB

128K

Core

Yes

7,500,000

April ‘98

2x16K

WB

512K/ 1M / 2M

Core

Yes

7,500,000

April ’98

There are several different voltage variations of Pentium processors, including what Intel calls V RE (3.5v), STD (3.3v), and newer 3.1v, 2.8v, 2.5v, 2.1v, and 1.8v versions. 4 There are versions of the Pentium Pro processor with 256K, 512K, or 1M of full core speed L2 cache in a separate die within the chip.

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Chapter 3—M icroprocessor Types and Specifications

A com p u ter system ’s clock sp eed is m easu red as a freq u en cy, u su ally exp ressed as a n u m ber of cycles p er secon d . A crystal oscillator con trols clock sp eed s, u sin g a sliver of q u artz in a sm all tin con tain er. As voltage is ap p lied to th e q u artz, it begin s to vibrate (oscillate) at a h arm on ic rate d ictated by th e sh ap e an d size of th e crystal (sliver). Th e oscillation s em an ate from th e crystal in th e form of a cu rren t th at altern ates at th e h arm on ic rate of th e crystal. Th is altern atin g cu rren t is th e clock sign al. A typ ical com p u ter system ru n s m illion s of th ese cycles p er secon d , so sp eed is m easu red in m egah ertz. (On e h ertz is eq u al to on e cycle p er secon d .)

Not e The hertz was named for the German physicist Heinrich Rudolf Hertz. In 1885, Hertz confirmed the electromagnetic theory, which states that light is a form of electromagnetic radiation and is propagated as waves.

A sin gle cycle is th e sm allest elem en t of tim e for th e p rocessor. Every action req u ires at least on e cycle an d u su ally m u ltip le cycles. To tran sfer d ata to an d from m em ory, for exam p le, a m od ern p rocessor su ch as th e Pen tiu m II n eed s a m in im u m of th ree cycles to set u p th e first m em ory tran sfer, an d th en on ly a sin gle cycle p er tran sfer for th e n ext th ree to six con secu tive tran sfers. Th e extra cycles on th e first tran sfer are n orm ally called wait states. A wait state is a clock tick in wh ich n oth in g h ap p en s. Th is en su res th at th e p rocessor isn ’t gettin g ah ead of th e rest of th e com p u ter. ◊◊ See “ SIM M s and DIM M s,” p. 324

Th e tim e req u ired to execu te in stru ction s also varies. Th e origin al 8086 an d 8088 p rocessors take an average of 12 cycles to execu te a sin gle in stru ction . Th e 286 an d 386 p rocessors im p rove th is rate to abou t 4.5 cycles p er in stru ction ; th e 486 d rop s th e rate fu rth er to abou t two cycles p er in stru ction . Th e Pen tiu m arch itectu re in clu d es twin in stru ction p ip elin es an d oth er im p rovem en ts th at p rovid e for op eration at on e or two in stru ction s p er cycle, wh ile th e Pen tiu m Pro an d Pen tiu m II can execu te as m an y as th ree or m ore in stru ction s p er cycle. Differen t in stru ction execu tion tim es (in cycles) m ake it d ifficu lt to com p are system s based p u rely on clock sp eed , or n u m ber of cycles p er secon d . How can two p rocessors th at ru n at th e sam e clock rate p erform d ifferen tly, with on e ru n n in g “faster” th an th e oth er? Th e an swer is sim p le: efficien cy. Th e m ain reason wh y th e 486 is fast com p ared to a 386 is th at it execu tes twice as m an y in stru ction s in th e sam e n u m ber of cycles. Th e sam e th in g is tru e for a Pen tiu m ; it execu tes abou t twice as m an y in stru ction s in a given n u m ber of cycles as a 486. Th u s, a 133MHz 486 (su ch as th e AMD 5x86-133) is n ot even as fast as a 75MHz Pen tiu m ! Th at is becau se Pen tiu m m egah ertz are worth abou t d ou ble wh at 486 m egah ertz are worth . Th e Pen tiu m II is abou t 50% faster th an an eq u ivalen t Pen tiu m at a given clock sp eed becau se it can execu te abou t th at m an y m ore in stru ction s in th e sam e n u m ber of cycles.

Processor Specifications

Com p arin g relative p rocessor p erform an ce, you can see th at a 500MHz Pen tiu m II is abou t eq u al to a (th eoretical) 750MHz Pen tiu m , wh ich is abou t eq u al to a 1400MHz 486, wh ich is abou t eq u al to a 2800MHz 386 or 286, wh ich is abou t eq u al to a 5600MHz 8088. Con sid erin g th at th e origin al PC’s 8088 ran at on ly 4.77MHz, we h ave system s tod ay th at are com p aratively m ore th an 1,000 tim es faster. As you can see, you h ave to be carefu l in com p arin g system s based on p u re MHz alon e; m an y oth er factors affect system p erform an ce. Evalu atin g CPU p erform an ce can be tricky. CPUs with d ifferen t in tern al arch itectu res d o th in gs d ifferen tly an d m ay be relatively faster at certain th in gs, slower at oth ers. To fairly com p are d ifferen t CPUs at d ifferen t clock sp eed s, In tel h as d evised a sp ecific series of ben ch m arks th at can be ru n again st In tel ch ip s to p rod u ce a relative gau ge of p erform an ce. It h as recen tly been u p d ated to reflect p erform an ce on 32-bit system s, an d is called th e iCOMP 2.0 (in tel COm p arative Microp rocessor Perform an ce) in d ex. Table 3.2 sh ows th e relative p ower, or iCOMP 2.0 in d ex, for several p rocessors. Table 3.2

Int el iCOM P 2.0 Index Rat ings

Processor

iCOM P 2.0 Index

Pentium 75

67

Pentium 100

90

Pentium 120

100

Pentium 133

111

Pentium 150

114

Pentium 166

127

Pentium 200

142

Pentium-M M X 166

160

Pentium-M M X 200

182

Pentium-M M X 233

203

Pentium Pro 180

197

Pentium Pro 200

220

Pentium II 233

267

Pentium II 266

303

Pentium II 300

332

Pentium II 333

366

Pentium II 350

386

Pentium II 400

440

The iCOMP 2.0 index is derived from several independent benchm arks and is a stable indication of relative processor perform ance. The benchm arks balance integer with floating point and m ultim edia perform ance.

Processor Speeds and M arkings Versus M ot herboard Speed. An oth er con fu sin g factor wh en com p arin g p rocessor p erform an ce is th at virtu ally all m od ern p rocessors sin ce th e 486DX2 ru n at som e m u ltip le of th e m oth erboard sp eed . For exam p le, a Pen tiu m II 333 ru n s at a m u ltip le of five tim es th e m oth erboard sp eed of 66MHz, wh ile

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36

Chapter 3—M icroprocessor Types and Specifications

a Pen tiu m II 400 ru n s at fou r tim es th e m oth erboard sp eed of 100MHz. Most m oth erboard s ru n at 66MHz becau se th at is all In tel su p p orted with th eir p rocessors u n til early ’98 or th ey th en released p rocessors an d ch ip sets d esign ed to ru n on 100MHz m oth erboard s. Cyrix h as a few p rocessors d esign ed to ru n on 75MHz m oth erboard s, an d m an y Pen tiu m m oth erboard s are cap able of ru n n in g th at sp eed as well. Norm ally, you can set th e m oth erboard sp eed an d m u ltip lier settin g via ju m p ers or oth er con figu ration m ech an ism (su ch as CMOS setu p ) on th e m oth erboard . Mod ern system s u se a variable-freq u en cy syn th esizer circu it u su ally fou n d in th e m ain m oth erboard ch ip set to con trol th e m oth erboard an d CPU sp eed . Most Pen tiu m m oth erboard s will h ave th ree or fou r sp eed settin gs. Th e p rocessors u sed tod ay are available in a variety of version s th at ru n at d ifferen t freq u en cies based on a given m oth erboard sp eed . For exam p le, m ost of th e Pen tiu m ch ip s ru n at a sp eed th at is som e m u ltip le of th e tru e m oth erboard sp eed . For exam p le, Pen tiu m p rocessors an d m oth erboard s ru n at th e sp eed s sh own in Table 3.3. Table 3.3

Int el Processor and M ot herboard Speeds

CPU Type/ Speed

CPU Clock

M ot herboard Speed

Pentium 60

1x

60

Pentium 66

1x

66

Pentium 75

1.5x

50

Pentium 90

1.5x

60

Pentium 100

1.5x

66

Pentium 120

2x

60

Pentium 133

2x

66

Pentium 150

2.5x

60

Pentium/ Pentium Pro/ M M X 166

2.5x

66

Pentium/ Pentium Pro 180

3x

60

Pentium/ Pentium Pro/ M M X 200

3x

66

Pentium-M M X/ Pentium II 233

3.5x

66

Pentium-M M X(M obile)/ Pentium-II

266 4x

66

Pentium II 300

4.5x

66

Pentium II 333

5x

66

Pentium II 350

3.5x

100

Pentium II 400

4x

100

Pentium II 450

4.5x

100

If all oth er variables are eq u al—in clu d in g th e typ e of p rocessor, th e n u m ber of wait states (em p ty cycles) ad d ed to d ifferen t typ es of m em ory accesses, an d th e wid th of th e d ata bu s—you can com p are two system s by th eir resp ective clock rates. However, th e con stru ction an d d esign of th e m em ory su bsystem can h ave an en orm ou s effect on a system ’s fin al execu tion sp eed .

Processor Specifications

In bu ild in g a p rocessor, a m an u factu rer tests it at d ifferen t sp eed s, tem p eratu res, an d p ressu res. After th e p rocessor is tested , it receives a stam p in d icatin g th e m axim u m safe sp eed at wh ich th e u n it will op erate u n d er th e wid e variation of tem p eratu res an d p ressu res en cou n tered in n orm al op eration . Th e ratin g system u su ally is sim p le. For exam p le, th e top of th e p rocessor in on e of m y system s is m arked like th is: A80486DX2–66 Th e A is In tel’s in d icator th at th is ch ip h as a Ceram ic Pin Grid Array form factor, or an in d ication of th e p h ysical p ackagin g of th e ch ip . Th e 80486DX2 is th e p art n u m ber, wh ich id en tifies th is p rocessor as a clock-d ou bled 486DX p rocessor. Th e –66 at th e en d in d icates th at th is ch ip is rated to ru n at a m axim u m sp eed of 66MHz. Becau se of th e clock d ou blin g, th e m axim u m m oth erboard sp eed is 33MHz. Th is ch ip wou ld be accep table for an y ap p lication in wh ich th e ch ip ru n s at 66MHz or slower. For exam p le, you cou ld u se th is p rocessor in a system with a 25MHz m oth erboard , in wh ich case th e p rocessor wou ld h ap p ily ru n at 50MHz. Most 486 m oth erboard s also h ave a 40MHz settin g, in wh ich case th e DX2 wou ld ru n at 80MHz in tern ally. Becau se th is is 14MHz beyon d its rated sp eed , m an y wou ld n ot work; or if th ey worked at all, it wou ld be on ly for a sh ort tim e. On th e oth er h an d , I h ave fou n d th at m ost of th e n ewer ch ip s m arked with –66 ratin gs seem to ru n fin e (albeit som ewh at h otter) at th e 40/ 80MHz settin gs. Th is is called overclocking an d can en d u p bein g a sim p le, cost-effective way to sp eed u p you r system . However, I wou ld n ot recom m en d th is for m ission -critical ap p lication s wh ere th e system reliability is of th e u tm ost im p ortan ce; a system p u sh ed beyon d sp ecification like th is can often exh ibit erratic beh avior u n d er stress.

Not e One good source of online overclocking information is located at ht t p:/ / w w w .sysopt .com . It includes, among other things, fairly thorough overclocking FAQs, and an ongoing survey of users who have successfully (and sometimes unsuccessfully) overclocked their CPUs.

Som etim es, h owever, th e m arkin gs d on ’t seem to in d icate th e sp eed d irectly. In th e old er 8086, for exam p le, –3 tran slates to 6MHz op eration . Th is m arkin g sch em e is m ore com m on in som e of th e old er ch ip s, wh ich were m an u factu red before som e of th e m arkin g stan d ard s u sed tod ay were stan d ard ized . A m ore m od ern exam p le wou ld be th e Cyrix/ IBM 6x86 p rocessors, wh ich u se a PR (Perform an ce Ratin g) scale th at is n ot eq u al to th e tru e clock sp eed in m egah ertz. For exam p le, th e Cyrix/ IBM 6x86MX-PR200 actu ally ru n s at 166MHz (2.5 × 66MHz). Th is is a little m islead in g—you m u st set u p th e m oth erboard as if a 166MHz p rocessor were bein g in stalled , n ot th e 200MHz you m igh t su sp ect. A m an u factu rer som etim es p laces th e CPU u n d er a h eat sin k, wh ich can p reven t you from read in g th e ratin g p rin ted on th e ch ip . (A heat sink is a m etal d evice th at d raws h eat away from an electron ic d evice.) Fortu n ately, m ost CPU m an u factu rers are p lacin g m arks

37

38

Chapter 3—M icroprocessor Types and Specifications

on th e top an d bottom of th e p rocessor. If th e h eat sin k is d ifficu lt to rem ove from th e ch ip , you can take th e h eat sin k an d ch ip ou t of th e socket togeth er an d read th e m arkin gs on th e bottom of th e p rocessor to d eterm in e wh at you h ave. Most p rocessors ru n n in g at 50MHz an d later sh ou ld h ave a h eat sin k in stalled to p reven t th e p rocessor from overh eatin g. Dat a Bus Perh ap s th e m ost com m on way to d escribe a p rocessor is by th e wid th of th e p rocessor’s extern al d ata bu s. Th is d efin es th e n u m ber of d ata bits th at can be m oved in to or ou t of th e p rocessor in on e cycle. A bus is sim p ly a series of con n ection s th at carry com m on sign als. Im agin e ru n n in g a p air of wires from on e en d of a bu ild in g to an oth er. If you con n ect a 110v AC p ower gen erator to th e two wires at an y p oin t an d p lace ou tlets at con ven ien t location s alon g th e wires, you h ave con stru cted a p ower bu s. No m atter wh ich ou tlet you p lu g th e wires in to, you h ave access to th e sam e sign al, wh ich in th is exam p le is 110v AC p ower. An y tran sm ission m ed iu m th at h as m ore th an on e ou tlet at each en d can be called a bu s. A typ ical com p u ter system h as several in tern al an d extern al bu ses. Th e p rocessor bu s d iscu ssed m ost often is th e extern al data bus–th e bu n d le of wires (or p in s) u sed to sen d an d receive d ata. Th e m ore sign als th at can be sen t at th e sam e tim e, th e m ore d ata can be tran sm itted in a sp ecified in terval an d , th erefore, th e faster th e bu s. A wid er d ata bu s is like h avin g a h igh way with m ore lan es, wh ich allows for greater th rou gh p u t. Data in a com p u ter is sen t as d igital in form ation con sistin g of a tim e in terval in wh ich a sin gle wire carries 5v to sign al a 1 d ata bit, or 0v to sign al a 0 d ata bit. Th e m ore wires you h ave, th e m ore in d ivid u al bits you can sen d in th e sam e tim e in terval. A ch ip su ch as th e 286 or 386SX, wh ich h as 16 wires for tran sm ittin g an d receivin g su ch d ata, h as a 16-bit d ata bu s. A 32-bit ch ip , su ch as th e 386DX an d 486, h as twice as m an y wires d ed icated to sim u ltan eou s d ata tran sm ission as a 16-bit ch ip ; a 32-bit ch ip can sen d twice as m u ch in form ation in th e sam e tim e in terval as a 16-bit ch ip . Mod ern p rocessors su ch as th e Pen tiu m series h ave 64-bit extern al d ata bu ses. Th is m ean s th at Pen tiu m p rocessors in clu d in g th e origin al Pen tiu m , Pen tiu m Pro, an d Pen tiu m II can all tran sfer 64 bits of d ata at a tim e to an d from th e system m em ory. A good way to u n d erstan d th is flow of in form ation is to con sid er a h igh way an d th e traffic it carries. If a h igh way h as on ly on e lan e for each d irection of travel, on ly on e car at a tim e can m ove in a certain d irection . If you wan t to in crease traffic flow, you can ad d an oth er lan e so th at twice as m an y cars p ass in a sp ecified tim e. You can th in k of an 8-bit ch ip as bein g a sin gle-lan e h igh way becau se on e byte flows th rou gh at a tim e. (On e byte eq u als eigh t in d ivid u al bits.) Th e 16-bit ch ip , with two bytes flowin g at a tim e, resem bles a two-lan e h igh way. You m ay h ave fou r lan es in each d irection to m ove a large n u m ber of au tom obiles. Th is stru ctu re corresp on d s to a 32-bit d ata bu s, wh ich h as th e cap ability to m ove fou r bytes of in form ation at a tim e. Takin g th is fu rth er, a 64-bit d ata bu s is like h avin g an 8-lan e h igh way m ovin g d ata in an d ou t of th e ch ip !

Processor Specifications

Ju st as you can d escribe a h igh way by its lan e wid th , you can d escribe a ch ip by th e wid th of its d ata bu s. W h en you read an ad vertisem en t th at d escribes a 32-bit or 64-bit com p u ter system , th e ad u su ally refers to th e CPU’s d ata bu s. Th is n u m ber p rovid es a rou gh id ea of th e ch ip ’s p erform an ce p oten tial (an d , th erefore, th e system ). Perh ap s th e m ost im p ortan t ram ification of th e d ata bu s in a ch ip is th at th e wid th of th e d ata bu s also d efin es th e size of a ban k of m em ory. Th is m ean s th at a 32-bit p rocessor, su ch as th e 486 class ch ip s, read s an d writes m em ory 32 bits at a tim e. Pen tiu m class p rocessors, in clu d in g th e Pen tiu m II, read an d write m em ory 64 bits at a tim e. Becau se stan d ard 72-p in SIMMs (Sin gle In lin e Mem ory Mod u les) are on ly 32 bits wid e, th ey m u st be in stalled on e at a tim e in m ost 486 class system s th ey’re in stalled two at a tim e in m ost Pen tiu m class system s. Newer DIMMs (Du al In lin e Mem ory Mod u les) are 64 bits wid e, so th ey are in stalled on e at a tim e in Pen tiu m class system s. Each DIMM is eq u al to a com p lete ban k of m em ory in Pen tiu m system s, wh ich m akes system con figu ration easy—th ey can th en be in stalled or rem oved on e at a tim e. Th is in form ation is d iscu ssed in m ore d etail in Ch ap ter 5, “Mem ory.” ◊◊ See “ M emory Banks,” p. 338

Int ernal Regist ers Th e size of th e in tern al registers in d icate h ow m u ch in form ation th e p rocessor can operate on at on e tim e, an d h ow it m oves d ata arou n d in tern ally with in th e ch ip . Th e register size is essen tially th e in tern al d ata bu s size. A register is a h old in g cell with in th e p rocessor; for exam p le, th e p rocessor can ad d n u m bers in two d ifferen t registers, storin g th e resu lt in a th ird register. Th e register size d eterm in es th e size of d ata th e p rocessor can op erate on . Th e register size also d escribes th e typ e of software or com m an d s an d in stru ction s a ch ip can ru n . Th at is, p rocessors with 32-bit in tern al registers can ru n 32-bit in stru ction s th at are p rocessin g 32-bit ch u n ks of d ata, bu t p rocessors with 16-bit registers can n ot. Most ad van ced p rocessors tod ay—ch ip s from th e 386 to th e Pen tiu m II—u se 32-bit in tern al registers an d can th erefore ru n th e sam e 32-bit op eratin g system s an d software. Som e p rocessors h ave an in tern al d ata bu s (m ad e u p of d ata p ath s an d storage u n its called registers) th at is larger th an th e extern al d ata bu s. Th e 8088 an d 386SX are exam p les of th is stru ctu re. Each ch ip h as an in tern al d ata bu s twice th e wid th of th e extern al bu s. Th ese d esign s, wh ich som etim es are called hybrid designs, u su ally are low-cost version s of a “p u re” ch ip . Th e 386SX, for exam p le, can p ass d ata arou n d in tern ally with a fu ll 32-bit register size; for com m u n ication s with th e ou tsid e world , h owever, th e ch ip is restricted to a 16-bit–wid e d ata p ath . Th is d esign en ables a system s d esign er to bu ild a lower-cost m oth erboard with a 16-bit bu s d esign an d still m ain tain software an d in stru ction set com p atibility with th e fu ll 32-bit 386.

39

40

Chapter 3—M icroprocessor Types and Specifications

In tern al registers often are larger th an th e d ata bu s, wh ich m ean s th at th e ch ip req u ires two cycles to fill a register before th e register can be op erated on . For exam p le, both th e 386SX an d 386DX h ave in tern al 32-bit registers, bu t th e 386SX h as to “in h ale” twice (figu ratively) to fill th em , wh ereas th e 386DX can d o th e job in on e “breath .” Th e sam e th in g wou ld h ap p en wh en th e d ata is p assed from th e registers back ou t to th e system bu s. Th e Pen tiu m is an exam p le of th is typ e of d esign . All Pen tiu m s h ave a 64-bit d ata bu s an d 32-bit registers—a stru ctu re th at m ay seem to be a p roblem u n til you u n d erstan d th at th e Pen tiu m h as two in tern al 32-bit p ip elin es for p rocessin g in form ation . In m an y ways, th e Pen tiu m is like two 32-bit ch ip s in on e. Th e 64-bit d ata bu s p rovid es for very efficien t fillin g of th ese m u ltip le registers. Mu ltip le p ip elin es are called superscalar architecture. See th e section on th e Pen tiu m p rocessor for m ore in form ation on su p erscalar arch itectu re. More ad van ced sixth -gen eration p rocessors su ch as th e Pen tiu m Pro an d Pen tiu m II h ave as m an y as six in tern al p ip elin es for execu tin g in stru ction s. Alth ou gh som e of th ese in tern al p ip es are d ed icated to sp ecial fu n ction s, th ese p rocessors can still execu te as m an y as th ree in stru ction s in on e clock cycle. Address Bus Th e address bus is th e set of wires th at carry th e ad d ressin g in form ation u sed to d escribe th e m em ory location to wh ich th e d ata is bein g sen t, or from wh ich th e d ata is bein g retrieved . As with th e d ata bu s, each wire in an ad d ress bu s carries a sin gle bit of in form ation . Th is sin gle bit is a sin gle d igit in th e ad d ress. Th e m ore wires (d igits) u sed in calcu latin g th ese ad d resses, th e greater th e total n u m ber of ad d ress location s. Th e size (or wid th ) of th e ad d ress bu s in d icates th e m axim u m am ou n t of RAM th at a ch ip can ad d ress. Th e h igh way an alogy can be u sed to sh ow h ow th e ad d ress bu s fits in . If th e d ata bu s is th e h igh way an d th e size of th e d ata bu s is eq u ivalen t to th e n u m ber of lan es, th e ad d ress bu s relates to th e h ou se n u m ber or street ad d ress. Th e size of th e ad d ress bu s is eq u ivalen t to th e n u m ber of d igits in th e h ou se ad d ress n u m ber. For exam p le, if you live on a street in wh ich th e ad d ress is lim ited to a two-d igit (base 10) n u m ber, n o m ore th an 100 d istin ct ad d resses (00 to 99) can exist for th at street (10 to th e p ower of 2). Ad d an oth er d igit, an d th e n u m ber of available ad d resses in creases to 1,000 (000 to 999), or 10 to th e th ird p ower. Com p u ters u se th e bin ary (base 2) n u m berin g system , so a two-d igit n u m ber p rovid es on ly fou r u n iq u e ad d resses (00, 01, 10, an d 11) calcu lated as 2 to th e p ower of 2; a th reed igit n u m ber p rovid es on ly eigh t ad d resses (000 to 111), wh ich is 2 to th e 3rd p ower. For exam p le, th e 8086 an d 8088 p rocessors u se a 20-bit ad d ress bu s th at calcu lates as a m axim u m of 2 to th e 20th p ower or 1,048,576 bytes (1M) of ad d ress location s. Table 3.4 d escribes th e m em ory-ad d ressin g cap abilities of In tel p rocessors.

Processor Specifications

Table 3.4

Int el Processor M em ory-Addressing Capabilit ies

Processor Fam ily

Address Bus

Byt es

Kilobyt es

M egabyt es

Gigabyt es

8088/ 8086

20-bit

1,048,576

1,024

1

-

286/ 386SX

24-bit

16,777,216

16,384

16

-

386DX/ 486/ Pentium

32-bit

4,294,967,296

4,194,304

4,096

4

Pentium Pro/ II

36-bit

68,719,476,736

67,108,864

65,536

64

Th e d ata bu s an d ad d ress bu s are in d ep en d en t, an d ch ip d esign ers can u se wh atever size th ey wan t for each . Usu ally, h owever, ch ip s with larger d ata bu ses h ave larger ad d ress bu ses. Th e sizes of th e bu ses can p rovid e im p ortan t in form ation abou t a ch ip ’s relative p ower, m easu red in two im p ortan t ways. Th e size of th e d ata bu s is an in d ication of th e ch ip ’s in form ation -m ovin g cap ability, an d th e size of th e ad d ress bu s tells you h ow m u ch m em ory th e ch ip can h an d le. Int ernal ( Level 1) Cache All m od ern p rocessors startin g with th e 486 fam ily in clu d e an in tegrated (Level 1) cach e con troller. Th at con troller h as 8K (or m ore) bu ilt-in fu ll core-sp eed cach e m em ory. Th is cach e basically is an area of very fast m em ory bu ilt in to th e p rocessor an d is u sed to h old som e of th e cu rren t workin g set of cod e an d d ata. Cach e m em ory can be accessed with n o wait states becau se it can fu lly keep u p with th e sp eed of th e p rocessor core. Usin g cach e m em ory red u ces a trad ition al system bottlen eck becau se system RAM often is m u ch slower th an th e CPU. Th is p reven ts th e p rocessor from h avin g to wait for cod e an d d ata from m u ch slower m ain m em ory, th erefore im p rovin g p erform an ce. W ith ou t th e Level 1 (L1) cach e, a p rocessor freq u en tly wou ld be forced to wait u n til system m em ory cau gh t u p . L1 cach e is even m ore im p ortan t in m od ern p rocessors becau se it is often th e on ly m em ory in th e en tire system th at can tru ly keep u p with th e ch ip . Most m od ern p rocessors are clock m u ltip lied , wh ich m ean s th ey are ru n n in g at a sp eed th at is really a m u ltip le of th e m oth erboard th ey are p lu gged in to. Th e Pen tiu m II 333MHz, for exam p le, ru n s at a very h igh m u ltip le of five tim es th e tru e m oth erboard sp eed of 66MHz. Becau se th e m ain m em ory is p lu gged in to th e m oth erboard , it can also ru n at on ly 66MHz m axim u m . Th e on ly 333MHz m em ory in su ch a system is th e L1 cach e bu ilt in to th e p rocessor core. In th is exam p le, th e Pen tiu m II 333MHz p rocessor h as 32K of in tegrated L1 cach e in two sep arate 16K blocks. ◊◊ See “ M emory Speeds,” p. 312

If th e d ata th at th e p rocessor wan ts is alread y in th e in tern al cach e, th e CPU d oes n ot h ave to wait. If th e d ata is n ot in th e cach e, th e CPU m u st fetch it from th e Level 2 cach e or (in less sop h isticated system d esign s) from th e system bu s, m ean in g m ain m em ory d irectly.

41

42

Chapter 3—M icroprocessor Types and Specifications

Th e organ ization of th e cach e m em ory in th e 486 an d Pen tiu m fam ily is called a four-way set associative cache, wh ich m ean s th at th e cach e m em ory is sp lit in to fou r blocks. Each block also is organ ized as 128 or 256 lin es of 16 bytes each . To u n d erstan d h ow a fou r-way set associative cach e works, con sid er a sim p le exam p le. In th e sim p lest cach e d esign , th e cach e is set u p as a sin gle block in to wh ich you can load th e con ten ts of a corresp on d in g block of m ain m em ory. Th is p roced u re is sim ilar to u sin g a bookm ark to locate th e cu rren t p age of a book th at you are read in g. If m ain m em ory eq u ates to all th e p ages in th e book, th e bookm ark in d icates wh ich p ages are h eld in cach e m em ory. Th is p roced u re works if th e req u ired d ata is located with in th e p ages m arked with th e bookm ark, bu t it d oes n ot work if you n eed to refer to a p reviou sly read p age. In th at case, th e bookm ark is of n o u se. An altern ative ap p roach is to m ain tain m u ltip le bookm arks to m ark several p arts of th e book sim u ltan eou sly. Ad d ition al h ard ware overh ead is associated with h avin g m u ltip le bookm arks, an d you also h ave to take tim e to ch eck all th e bookm arks to see wh ich on e m arks th e p ages of d ata you n eed . Each ad d ition al bookm ark ad d s to th e overh ead , bu t also in creases you r ch an ce of fin d in g th e d esired p ages. If you settle on m arkin g fou r areas in th e book, you h ave essen tially con stru cted a fou rway set associative cach e. Th is tech n iq u e sp lits th e available cach e m em ory in to fou r blocks, each of wh ich stores d ifferen t lin es of m ain m em ory. Mu ltitaskin g en viron m en ts, su ch as W in d ows, are good exam p les of en viron m en ts in wh ich th e p rocessor n eed s to op erate on d ifferen t areas of m em ory sim u ltan eou sly an d in wh ich a fou r-way cach e wou ld im p rove p erform an ce greatly. Th e con ten ts of th e cach e m u st always be in syn c with th e con ten ts of m ain m em ory to en su re th at th e p rocessor is workin g with cu rren t d ata. For th is reason , th e in tern al cach e in th e 486 fam ily is a W rite-Through cache. W rite-Th rou gh m ean s th at wh en th e p rocessor writes in form ation ou t to th e cach e, th at in form ation is au tom atically written th rou gh to m ain m em ory as well. By com p arison , th e Pen tiu m an d later ch ip s h ave an in tern al W rite-Back cache, wh ich m ean s th at both read s an d writes are cach ed , fu rth er im p rovin g p erform an ce. Even th ou gh th e in tern al 486 cach e is W rite-Th rou gh , th e system can em p loy an extern al W rite-Back cach e for in creased p erform an ce. In ad d ition , th e 486 can bu ffer u p to fou r bytes before actu ally storin g th e d ata in RAM, im p rovin g efficien cy in case th e m em ory bu s is bu sy. Th e cach e con troller bu ilt in to th e p rocessor also is resp on sible for watch in g th e m em ory bu s wh en altern ate p rocessors, kn own as busm asters, are in con trol of th e system . Th is p rocess of watch in g th e bu s is referred to as Bus Snooping. If a bu sm aster d evice writes to an area of m em ory th at also is stored in th e p rocessor cach e cu rren tly, th e cach e con ten ts an d m em ory n o lon ger agree. Th e cach e con troller th en m arks th is d ata as in valid an d reload s th e cach e d u rin g th e n ext m em ory access, p reservin g th e in tegrity of th e system .

Processor Specifications

A secon d ary extern al L2 cach e of extrem ely fast static RAM (SRAM) ch ip s also is u sed in m ost 486 an d Pen tiu m -based system s. It fu rth er red u ces th e am ou n t of tim e th at th e CPU m u st sp en d waitin g for d ata from system m em ory. Th e fu n ction of th e secon d ary p rocessor cach e is sim ilar to th at of th e on board cach e. Th e secon d ary p rocessor cach e h old s in form ation th at is m ovin g to th e CPU, th ereby red u cin g th e tim e th at th e CPU sp en d s waitin g an d in creasin g th e tim e th at th e CPU sp en d s p erform in g calcu lation s. Fetch in g in form ation from th e secon d ary p rocessor cach e rath er th an from system m em ory is m u ch faster becau se of th e SRAM ch ip s’ extrem ely fast sp eed —15 n an osecon d s (n s) or less. Pen tiu m system s in corp orate th e secon d ary cach e on th e m oth erboard , wh ile Pen tiu m Pro an d Pen tiu m II system s h ave th e secon d ary cach e in sid e th e p rocessor p ackage. By m ovin g th e L2 cach e in to th e p rocessor, th ey are able to ru n it at sp eed s h igh er th an th e m oth erboard —u p to as fast as th e p rocessor core. As clock sp eed s in crease, cycle tim e d ecreases. Most SIMM m em ory u sed tod ay in Pen tiu m an d earlier system s was 60n s, wh ich works ou t to be on ly abou t 16MHz! Stan d ard m oth erboard sp eed tod ay is 66MHz or 100MHz, an d p rocessors are available at 450MHz or m ore. Newer system s d on ’t u se cach e on th e m oth erboard an y lon ger, as th e faster SDRAM u sed in m od ern Pen tiu m II system s can keep u p with th e m oth erboard sp eed . Table 3.5 illu strates th e n eed for an d fu n ction of Level 1 (in tern al) an d Level 2 (extern al) cach e in m od ern system s. Table 3.5

CPU Speeds Relat ive t o Cache, SIM M / DIM M , and M ot herboard

CPU Type:

486 DX4

Pent ium

CPU speed:

100M Hz

233M Hz

Pent ium Pro

Pent ium II ( ’97) Pent ium II ( ’98)

200M Hz

333M Hz

450M Hz

L1 cache speed: 10ns (100M Hz) 4ns (233M Hz)

5ns (200M Hz)

3ns (333M Hz)

2ns (450M Hz)

L2 cache speed: 30ns (33M Hz)

15ns (66M Hz)

5ns (200M Hz)

6ns (167M Hz)

4ns (225M Hz)

M otherboard speed:

33M Hz

66M Hz

66M Hz

66M Hz

100M Hz

SIM M / DIM M speed:

60ns (16M Hz)

60ns (16M Hz)

60ns (16M Hz)

15ns (66M Hz)

10ns (100M Hz)

SIM M / DIM M type:

FPM

FPM / EDO

FPM / EDO

SDRAM

SDRAM

As you can see, h avin g two levels of cach e between th e very fast CPU an d th e m u ch slower m ain m em ory h elp s m in im ize an y wait states th e p rocessor m igh t h ave to en d u re. Th is allows th e p rocessor to keep workin g closer to its tru e sp eed . Processor M odes All In tel 32-bit an d later p rocessors, from th e 386 on u p , can ru n in several m od es. Processor m od es refer to th e variou s op eratin g en viron m en ts an d affect th e in stru ction s an d cap abilities of th e ch ip . Th e p rocessor m od e con trols h ow th e p rocessor sees an d m an ages th e system m em ory an d th e tasks th at u se it.

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Chapter 3—M icroprocessor Types and Specifications

Th ree d ifferen t m od es of op eration p ossible are ■ Real m od e ■ Protected m od e ■ Virtu al Real m od e (Real with in Protected ) Th e origin al IBM PC in clu d ed an 8088 p rocessor th at cou ld execu te 16-bit in stru ction s u sin g 16-bit in tern al registers, an d cou ld ad d ress on ly 1M of m em ory u sin g 20 ad d ress lin es. All origin al PC software was created to work with th is ch ip , an d was d esign ed arou n d th e 16-bit in stru ction set an d 1M m em ory m od el. For exam p le, DOS an d all DOS software, W in d ows 1.x th rou gh 3.x, an d all W in d ows 1.x th rou gh 3.x ap p lication s are written u sin g 16-bit in stru ction s. Th ese 16-bit op eratin g system s an d ap p lication s are d esign ed to ru n on an origin al 8088 p rocessor. √√ See “ Internal Registers,” p. 39 √√ See “ Address Bus,” p. 40

Later p rocessors like th e 286 cou ld also ru n th e sam e 16-bit in stru ction s as th e origin al 8088, bu t m u ch faster. In oth er word s, th e 286 was fu lly com p atible with th e origin al 8088 an d cou ld ru n all 16-bit software ju st th e sam e as an 8088, bu t, of cou rse, th at software wou ld ru n faster. Th e 16-bit in stru ction m od e of th e 8088 an d 286 p rocessors h as becom e kn own as real m ode. All software ru n n in g in real m od e m u st u se on ly 16-bit in stru ction s an d live with in th e 20-bit (1M) m em ory arch itectu re it su p p orts. Software of th is typ e is n orm ally sin gle-taskin g, wh ich m ean s th at on ly on e p rogram can ru n at a tim e. Th ere is n o bu ilt-in p rotection to keep on e p rogram from overwritin g an oth er p rogram or even th e op eratin g system in m em ory, wh ich m ean s th at if m ore th an on e p rogram is ru n n in g, it is p ossible for on e of th em to brin g th e en tire system to a crash in g h alt. Th en cam e th e 386, wh ich was th e PC in d u stry’s first 32-bit p rocessor. Th is ch ip cou ld ru n an en tirely n ew 32-bit in stru ction set. To fu lly take ad van tage of th e 32-bit in stru ction set you n eed a 32-bit op eratin g system an d a 32-bit ap p lication . Th is n ew 32-bit m od e was referred to as protected m ode, wh ich allu d es to th e fact th at software p rogram s ru n n in g in th at m od e are p rotected from overwritin g on e an oth er in m em ory. Su ch p rotection h elp s m ake th e system m u ch m ore crash p roof, as an erran t p rogram can n ot very easily d am age oth er p rogram s or th e op eratin g system . In ad d ition , a crash ed p rogram can sim p ly be term in ated , wh ile th e rest of th e system con tin u es to ru n u n affected . Kn owin g th at n ew op eratin g system s an d ap p lication s to take ad van tage of th e 32-bit p rotected m od e wou ld take som e tim e to d evelop , In tel wisely bu ilt in a backward com p atible real m od e in to th e 386. Th at allowed it to ru n u n m od ified 16-bit op eratin g system s an d ap p lication s. It ran th em q u ite well, m u ch faster th an an y p reviou s ch ip . For m ost p eop le, th at was en ou gh ; th ey d id n ot n ecessarily wan t an y n ew 32-bit software— th ey ju st wan ted th eir existin g 16-bit software to ru n faster. Un fortu n ately, th at m ean t th at th e ch ip was n ever ru n n in g in th e 32-bit p rotected m od e, an d all th e featu res of th at cap ability were bein g ign ored .

Processor Specifications

W h en a h igh -p owered p rocessor like a Pen tiu m II is ru n n in g in real m od e, it acts like a “Tu rbo 8088.” Tu rbo 8088 m ean s th at th e p rocessor h as th e ad van tage of sp eed in ru n n in g an y 16-bit p rogram s; it oth erwise can u se on ly th e 16-bit in stru ction s an d access m em ory with in th e sam e 1M m em ory m ap of th e origin al 8088. Th is m ean s if you h ave a 64M Pen tiu m II system ru n n in g W in d ows 3.x or DOS, you are effectively u sin g on ly th e first m egabyte of m em ory, leavin g th e oth er 63M largely u n u sed ! New op eratin g system s an d ap p lication s th at ran in th e 32-bit p rotected m od e of th e m od ern p rocessors were n eed ed . Bein g stu bborn , we resisted all th e in itial attem p ts at gettin g u s switch ed over to a 32-bit en viron m en t. It seem s th at as a u ser com m u n ity, we are very resistan t to ch an ge an d wou ld be con ten t with ou r old er software ru n n in g faster rath er th an ad op tin g n ew software with n ew featu res. I’ll be th e first on e to ad m it th at I was on e of th ose stu bborn u sers m yself! Du e to th is resistan ce, 32-bit op eratin g system s su ch as UNIX, OS/ 2, an d even W in d ows NT h ave h ad a very h ard tim e gettin g an y m arket sh are in th e PC m arketp lace. Ou t of th ose, W in d ows NT is th e on ly on e th at will likely be close to m ain stream , an d th at is on ly becau se Microsoft h as coerced u s in th at d irection with W in d ows 95 an d 98. W in d ows 3.x was th e last fu ll 16-bit op eratin g system . In fact, it was n ot a com p lete op eratin g system becau se it ran on top of DOS. Microsoft realized h ow stu bborn th e in stalled base of PC u sers was, so it d evelop ed W in d ows 95 as a brid ge to a fu ll 32-bit world . W in d ows 95 is a m ostly 32-bit op eratin g system , bu t it retain s en ou gh 16-bit cap ability to fu lly ru n ou r old 16-bit ap p lication s. W in d ows 95 cam e ou t in Au gu st of ’95, a fu ll 10 years later th an th e in trod u ction of th e first 32-bit PC p rocessor! It h as taken u s on ly 10 years to m igrate to software th at can fu lly u se th e p rocessors we h ave in fron t of u s. Th e key to th e backward com p atibility of th e W in d ows 95 32-bit en viron m en t is th e th ird m od e in th e p rocessor: virtual real m od e. Virtu al real is essen tially a virtu al real m od e 16-bit en viron m en t th at ru n s in sid e 32-bit p rotected m od e. W h en you ru n a DOS p rom p t win d ow in sid e W in d ows 95/ 98, you h ave created a virtu al real m od e session . Becau se p rotected m od e allows tru e m u ltitaskin g, you can actu ally h ave several real m od e session s ru n n in g, each with its own software ru n n in g on a virtu al PC. Th is can all ru n sim u ltan eou sly, even wh ile oth er 32-bit ap p lication s are ru n n in g. Note th at an y p rogram ru n n in g in a virtu al real m od e win d ow can access u p to on ly 1M of m em ory, wh ich th at p rogram will believe is th e first an d on ly m egabyte of m em ory in th e system . In oth er word s, if you ru n a DOS ap p lication in a virtu al real win d ow, it will h ave a 640K lim itation on m em ory u sage. Th at is becau se th ere is on ly 1M of total RAM in a 16-bit en viron m en t, an d th e u p p er 384K is reserved for system u se. Th e virtu al real win d ow fu lly em u lates an 8088 en viron m en t, so th at asid e from sp eed , th e software ru n s as if it were on an origin al real-m od e-on ly PC. Each virtu al m ach in e gets its own 1M ad d ress sp ace, an im age of th e real h ard ware BIOS rou tin es, an d em u lation of all oth er registers an d featu res fou n d in real m od e.

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Chapter 3—M icroprocessor Types and Specifications

Virtu al real m od e is u sed wh en you u se a DOS win d ow or ru n a DOS or W in d ows 3.x 16-bit p rogram in W in d ows 95/ 98. W h en you start a DOS ap p lication , W in d ows 95 creates a virtu al DOS m ach in e u n d er wh ich it can ru n . On e in terestin g th in g to n ote is th at all In tel p rocessors p ower u p in real m od e. If you load a 32-bit op eratin g system , it will au tom atically switch th e p rocessor in to 32-bit m od e an d take con trol from th ere. Som e DOS an d W in d ows 3.x ap p lication s m isbeh ave, wh ich m ean s th ey d o th in gs th at even virtu al real m od e will n ot su p p ort. Diagn ostics software is a p erfect exam p le of th is. Su ch software will n ot ru n p rop erly in a real-m od e (virtu al real) win d ow u n d er W in d ows 95/ 98 or NT. In th at case, you can still ru n you r Pen tiu m II in th e origin al n o-frills real m od e by in terru p tin g th e boot p rocess an d com m an d in g th e system to boot p lain DOS. Th is is accom p lish ed on m ost W in d ows 95/ 98/ NT system s by p ressin g th e F8 key wh en you see th e p rom p t “Startin g W in d ows…” on th e screen . You will th en see th e Startu p m en u ; you can select on e of th e Com m an d Prom p t ch oices, wh ich tell th e system to boot p lain 16-bit real-m od e DOS. Th e ch oice of “Safe m od e com m an d p rom p t” is best if you are goin g to ru n tru e h ard ware d iagn ostics, wh ich d o n ot n orm ally ru n in p rotected m od e an d sh ou ld be ru n with a m in im u m of d rivers an d oth er software load ed . Alth ou gh real m od e is u sed by DOS an d “stan d ard ” DOS ap p lication s, th ere are sp ecial p rogram s available th at “exten d ” DOS an d allow access to exten d ed m em ory (over 1M). Th ese are som etim es called DOS extenders an d are u su ally in clu d ed as a p art of an y DOS or W in d ows 3.x software th at u ses th em . Th e p rotocol th at d escribes h ow to m ake DOS work in p rotected m od e is called DPMI (DOS p rotected m od e in terface). DPMI was u sed by W in d ows 3.x to access exten d ed m em ory for u se with W in d ows 3.x ap p lication s. It allowed th em to u se m ore m em ory even th ou gh th ey were still 16-bit p rogram s. DOS exten d ers are esp ecially p op u lar in DOS gam es, becau se it allows th em to access m u ch m ore of th e system m em ory th an th e stan d ard 1M m ost real-m od e p rogram s can ad d ress. Th ese DOS exten d ers work by switch in g th e p rocessor in an d ou t of real m od e, or in th e case of th ose th at ru n u n d er W in d ows, th ey u se th e DPMI in terface bu ilt in to W in d ows, allowin g th em to sh are a p ortion of th e system ’s exten d ed m em ory. An oth er excep tion in real m od e is th at th e first 64K of exten d ed m em ory is actu ally accessible to th e PC in real m od e, d esp ite th e fact th at it’s n ot su p p osed to be p ossible. Th is is th e resu lt of a bu g in th e origin al IBM AT with resp ect to th e 21st m em ory ad d ress lin e, kn own as A20 (A0 is th e first ad d ress lin e). By m an ip u latin g th e A20 lin e, real-m od e software can gain access to th e first 64K of exten d ed m em ory—th e first 64K of m em ory p ast th e first m egabyte. Th is area of m em ory is called th e high m em ory area (HMA). ◊◊ See “ High M emory Area (HM A) and the A20 Line,” p. 378

Processor Specifications

Processor Feat ures Mod ern PC p rocessors h ave several d ifferen t featu res th at are d escribed in th e followin g section s. Th e m ost n otable are: ■ SMM (p ower m an agem en t) ■ Su p erscalar execu tion ■ MMX tech n ology ■ Dyn am ic execu tion ■ Du al In d ep en d en t bu s (DIB) arch itectu re SM M ( Pow er M anagem ent ) . Sp u rred on p rim arily by th e goal of p u ttin g faster an d m ore p owerfu l p rocessors in lap top com p u ters, In tel h as created p ower m an agem en t circu itry. Th is circu itry en ables p rocessors to con serve en ergy u se an d len gth en battery life. Th is was in trod u ced in itially in th e In tel 486SL p rocessor, wh ich is an en h an ced version of th e 486DX p rocessor. Su bseq u en tly, th e p ower-m an agem en t featu res were u n iversalized an d in corp orated in to all Pen tiu m an d later p rocessors. Th is featu re set is called SMM, wh ich stan d s for System Man agem en t Mod e. SMM circu itry is in tegrated in to th e p h ysical ch ip bu t op erates in d ep en d en tly to con trol th e p rocessor’s p ower u se based on its activity level. It allows th e u ser to sp ecify tim e in tervals after wh ich th e CPU will be p artially or fu lly p owered d own . It also su p p orts th e su sp en d / resu m e featu re th at allows for in stan t p ower on an d p ower off, u sed m ostly with lap top PCs. Th ese settin gs are n orm ally con trolled via system BIOS settin gs. Superscalar Execut ion. Th e fifth -gen eration Pen tiu m an d n ewer p rocessors featu re m u ltip le in tern al in stru ction execu tion p ip elin es, wh ich en able th em to execu te m u ltip le in stru ction s at th e sam e tim e. Th e 486 an d all p reced in g ch ip s can p erform on ly a sin gle in stru ction at a tim e. In tel calls th e cap ability to execu te m ore th an on e in stru ction at a tim e superscalar technology. Th is tech n ology p rovid es ad d ition al p erform an ce com p ared with th e 486. Su p erscalar arch itectu re u su ally is associated with h igh -ou tp u t RISC (Red u ced In stru ction Set Com p u ter) ch ip s. Th e Pen tiu m is on e of th e first CISC (Com p lex In stru ction Set Com p u ter) ch ip s to be con sid ered su p erscalar. Th is is n ow a stan d ard featu re of all fifth gen eration an d n ewer PC p rocessors. M M X Technology. MMX tech n ology is n am ed for Mu lti-Med ia eXten sion s, or Matrix Math eXten sion s, d ep en d in g on wh om you ask. In tel states th at it is actu ally n ot an acron ym an d stan d s for n oth in g sp ecial; h owever, th e in tern al origin s are p robably on e of th e p reced in g. MMX tech n ology was in trod u ced in th e later fifth -gen eration Pen tiu m p rocessors (see Figu re 3.1) as a kin d of ad d -on th at im p roves vid eo com p ression / d ecom p ression , im age m an ip u lation , en cryp tion , an d I/ O p rocessin g—all of wh ich are u sed in a variety of tod ay’s software.

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Chapter 3—M icroprocessor Types and Specifications

FIG. 3.1 An In tel Pen tiu m MMX ch ip sh own from th e top an d bottom (exp osin g th e d ie). Photograph used by perm ission of Intel Corporation.

MMX con sists of two m ain p rocessor arch itectu ral im p rovem en ts. Th e first is very basic; all MMX ch ip s h ave a larger in tern al L1 cach e th an th eir n on -MMX cou n terp arts. Th is im p roves th e p erform an ce of an y an d all software ru n n in g on th e ch ip , regard less of wh eth er it actu ally u ses th e MMX-sp ecific in stru ction s. Th e oth er p art of MMX is th at it exten d s th e p rocessor in stru ction s set with 57 n ew com m an d s or in stru ction s, as well as a n ew in stru ction cap ability called Sin gle In stru ction , Mu ltip le Data (SIMD). Mod ern m u ltim ed ia an d com m u n ication ap p lication s often u se rep etitive loop s th at, wh ile occu p yin g 10% or less of th e overall ap p lication cod e, can accou n t for u p to 90% of th e execu tion tim e. SIMD en ables on e in stru ction to p erform th e sam e fu n ction on m u ltip le p ieces of d ata, sim ilar to a teach er tellin g an en tire class to “sit d own ,” rath er th an ad d ressin g each stu d en t on e at a tim e. SIMD allows th e ch ip to red u ce p rocessorin ten sive loop s com m on with vid eo, au d io, grap h ics, an d an im ation . In tel also ad d ed 57 n ew in stru ction s sp ecifically d esign ed to m an ip u late an d p rocess vid eo, au d io, an d grap h ical d ata m ore efficien tly. Th ese in stru ction s are orien ted to th e h igh ly p arallel an d often rep etitive seq u en ces often fou n d in m u ltim ed ia op eration s. Highly parallel refers to th e fact th at th e sam e p rocessin g is d on e on m an y d ifferen t d ata p oin ts, su ch as wh en m od ifyin g a grap h ic im age. In tel h as licen sed th e MMX cap abilities to com p etitors su ch as AMD an d Cyrix, wh o were th en able to u p grad e th eir own In tel-com p atible p rocessors with MMX tech n ology. Dynam ic Execut ion. First u sed in th e P6 or sixth -gen eration p rocessors, Dyn am ic Execu tion is an in n ovative com bin ation of th ree p rocessin g tech n iq u es d esign ed to h elp th e p rocessor m an ip u late d ata m ore efficien tly. Th ose tech n iq u es are m u ltip le bran ch p red iction , d ata flow an alysis, an d sp ecu lative execu tion . Dyn am ic execu tion en ables th e p rocessor to be m ore efficien t by m an ip u latin g d ata in a m ore logically ord ered fash ion rath er th an sim p ly p rocessin g a list of in stru ction s.

Processor Specifications

Th e way software is written can d ram atically in flu en ce a p rocessor’s p erform an ce. For exam p le, p erform an ce will be ad versely affected if th e p rocessor is freq u en tly req u ired to stop wh at it is d oin g an d ju m p or bran ch to a p oin t elsewh ere in th e p rogram . Delays also occu r wh en th e p rocessor can n ot p rocess a n ew in stru ction u n til th e cu rren t in stru ction is com p leted . Dyn am ic execu tion allows th e p rocessor to n ot on ly d yn am ically p red ict th e ord er of in stru ction s, bu t execu te th em ou t of ord er in tern ally, if n ecessary, for an im p rovem en t in sp eed . Dyn am ic execu tion con sists of th e followin g: Multiple Branch Prediction. Pred icts th e flow of th e p rogram th rou gh several bran ch es. Usin g a sp ecial algorith m , th e p rocessor can an ticip ate ju m p s or bran ch es in th e in stru ction flow. It u ses th is to p red ict wh ere th e n ext in stru ction s can be fou n d in m em ory with an accu racy of 90% or greater. Th is is p ossible becau se wh ile th e p rocessor is fetch in g in stru ction s, it is also lookin g at in stru ction s fu rth er ah ead in th e p rogram . Data Flow Analysis. An alyzes an d sch ed u les in stru ction s to be execu ted in an op tim al seq u en ce, in d ep en d en t of th e origin al p rogram ord er. Th e p rocessor looks at d ecod ed software in stru ction s an d d eterm in es wh eth er th ey are available for p rocessin g or are in stead d ep en d en t on oth er in stru ction s to be execu ted first. Th e p rocessor th en d eterm in es th e op tim al seq u en ce for p rocessin g an d execu tes th e in stru ction s in th e m ost efficien t m an n er. Speculative Execution. In creases p erform an ce by lookin g ah ead of th e p rogram cou n ter an d execu tin g in stru ction s th at are likely to be n eed ed later. Becau se th e software in stru ction s bein g p rocessed are based on p red icted bran ch es, th e resu lts are stored in a p ool for later referral. If th ey are to be execu ted by th e resu ltan t p rogram flow, th e alread y com p leted in stru ction s are retired an d th e resu lts are com m itted to th e p rocessor’s m ain registers in th e origin al p rogram execu tion ord er. Th is tech n iq u e essen tially allows th e p rocessor to com p lete in stru ction s in ad van ce an d th en grab th e alread y com p leted resu lts wh en n ecessary. Dyn am ic execu tion is on e of th e h allm arks of all sixth -gen eration p rocessors. Dual Independent Bus ( DIB) Archit ect ure. Th e Du al In d ep en d en t Bu s (DIB) arch itectu re was first im p lem en ted in th e first sixth -gen eration p rocessor. DIB was created to im p rove p rocessor bu s ban d wid th an d p erform an ce. Havin g two (d u al) in d ep en d en t d ata I/ O bu ses en ables th e p rocessor to access d ata from eith er of its bu ses sim u ltan eou sly an d in p arallel, rath er th an in a sin gu lar seq u en tial m an n er (as in a sin gle-bu s system ). Th e secon d or backsid e bu s in a p rocessor with DIB is u sed for th e L2 cach e, allowin g it to ru n at m u ch greater sp eed s th an if it were to sh are th e m ain p rocessor bu s. Two bu ses m ake u p th e Du al In d ep en d en t Bu s arch itectu re: th e L2 cach e bu s an d th e p rocessor-to-m ain -m em ory, or system , bu s. Th e P6 Pen tiu m Pro an d Pen tiu m II p rocessors can u se both bu ses sim u ltan eou sly, elim in atin g a bottlen eck th ere. Th e Du al In d ep en d en t Bu s arch itectu re en ables th e L2 cach e of th e 400MHz Pen tiu m II p rocessor, for exam p le, to ru n m ore th an th ree tim es as fast as th e L2 cach e of old er Pen tiu m

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Chapter 3—M icroprocessor Types and Specifications

p rocessors. Becau se th e backsid e or L2 cach e bu s is cou p led to th e sp eed of th e p rocessor core, as th e freq u en cy of fu tu re Pen tiu m II p rocessors in creases, so will th e sp eed of th e L2 cach e. Th e key to im p lem en tin g DIB is to m ove th e L2 cach e m em ory off of th e m oth erboard an d in to th e p rocessor p ackage. Th is allows th e L2 cach e to ru n at sp eed s m ore like th e L1 cach e, m u ch faster th an th e m oth erboard m em ory. To m ove th e cach e in to th e p rocessor, m od ification s h ad to be m ad e to th e CPU socket. Th e on ly socket-based p rocessor th at su p p orts DIB is th e Pen tiu m Pro, wh ich p lu gs in to Socket 8. In th e Pen tiu m Pro, th e L1 cach e is d irectly on th e p rocessor d ie (as with all 486 an d h igh er p rocessors), an d th e L2 cach e is con tain ed with in th e ch ip p ackage bu t on sep arate d ie(s). Th is, u n fortu n ately, m ad e th e ch ip exp en sive an d d ifficu lt to p rod u ce, alth ou gh it d id m ean th at th e L2 cach e ran at fu ll p rocessor sp eed . Th e Pen tiu m II ad op ted a less exp en sive an d easier-to-m an u factu re ap p roach . By p lacin g th e p rocessor an d L2 cach e as sep arate ch ip s in sid e a cartrid ge, th ey n ow h ave a CPU m od u le th at is easier an d less exp en sive to m ake. Th e Sin gle Ed ge Con tact (SEC) cartrid ge is an in n ovative—if a bit u n wield y—p ackage d esign th at in corp orates th e backsid e bu s an d L2 cach e in tern ally. Usin g th e SEC d esign , th e core an d L2 cach e are fu lly en closed in a p lastic an d m etal cartrid ge. Th ese su bcom p on en ts are su rface m ou n ted d irectly to a su bstrate (or base) in sid e th e cartrid ge to en able h igh -freq u en cy op eration . Th e SEC cartrid ge tech n ology allows th e u se of wid ely available, h igh -p erform an ce in d u stry stan d ard Bu rst Static RAMs (BSRAMs) for th e d ed icated L2 cach e. Th is greatly red u ces th e cost com p ared to th e p rop rietary cach e ch ip s u sed in sid e th e CPU p ackage in th e Pen tiu m Pro. Most Pen tiu m IIs ru n th e L2 cach e at exactly 1/ 2-core sp eed , bu t th at can easily be scaled u p or d own in fu tu re Pen tiu m II p rocessors. Also, m ost h ave 512K of L2 cach e in tern ally, bu t th at can be easily ch an ged in th e fu tu re becau se In tel is n ow u sin g off-th e-sh elf cach e ch ip s in th e p rocessor cartrid ge. In tel will m ake Pen tiu m IIs with an ywh ere from n o L2 cach es to m u ltip le m egabytes. Th e Pen tiu m II SEC p rocessor con n ects to a m oth erboard via a sin gle-ed ge con n ector in stead of th e m u ltip le p in s u sed in existin g Pin Grid Array socket p ackages. DIB also allows th e system bu s to p erform m u ltip le sim u ltan eou s tran saction s (in stead of sin gu lar seq u en tial tran saction s), acceleratin g th e flow of in form ation with in th e system an d boostin g p erform an ce. Overall Du al In d ep en d en t Bu s arch itectu re offers u p to th ree tim es th e ban d wid th p erform an ce over a sin gle-bu s arch itectu re p rocessor. Processor M anufact uring Processors are m an u factu red p rim arily from silicon , th e m ost com m on elem en t on earth . Silicon is th e p rim ary in gred ien t in beach san d (silicon d ioxid e); h owever, in th at form it isn ’t p u re en ou gh to be u sed in ch ip s. To be m ad e in to ch ip s, raw silicon is p u rified , m elted d own , an d th en allowed to solid ify in to large cylin d rical crystals called boules. Each bou le is cu rren tly abou t 8 in ch es in d iam eter an d over 50 in ch es lon g an d weigh s h u n d red s of p ou n d s. Th e bou le is th en grou n d in to a p erfect 200-m m -d iam eter cylin d er (th e cu rren t stan d ard ), often with a flat

Processor Specifications

cu t on on e sid e for p osition in g accu racy an d h an d lin g. Each bou le is th en cu t with a h igh -p recision d iam on d saw in to over a th ou san d circu lar wafers less th an a m illim eter th ick each . Each wafer is p olish ed to a m irror-sm ooth su rface. Ch ip s are m an u factu red u sin g a p rocess called photolithography. Th rou gh th is p h otograp h ic p rocess, tran sistors an d circu it an d sign al p ath ways are created in sem icon d u ctors by d ep ositin g d ifferen t layers of variou s m aterials on th e ch ip , on e after th e oth er. W h ere two sp ecific circu its in tersect, a tran sistor or switch can be form ed . Th e p h otolith ograp h ic p rocess starts by coatin g th e wafer with a layer of sp ecially d op ed sem icon d u ctor m aterial, coverin g th at layer with a p h otoresist ch em ical, an d th en p rojectin g th e im age of th e ch ip on to th e n ow ligh t-sen sitive su rface. Doping is th e term u sed to d escribe ch em ical im p u rities ad d ed to silicon (wh ich is n atu rally a n on -con d u ctor), creatin g a m aterial with sem icon d u ctor p rop erties. Th e p rojector u ses a sp ecially created m ask, wh ich is essen tially a m ap of th at p articu lar layer of th e ch ip . Th e Pen tiu m II cu rren tly h as fou r in d ivid u al layers, alth ou gh oth er m od ern p rocessors m ay h ave six or m ore layers. Each p rocessor d esign req u ires as m an y m asks as layers to p rod u ce th e ch ip s. As th e ligh t p asses th rou gh th e first m ask, it is focu sed on th e wafer su rface, im p rin tin g it with th e im age of th at layer of th e ch ip . Each ch ip im age is called a die. A d evice called a stepper th en m oves th e wafer over a sm all am ou n t an d th e sam e m ask is u sed to im p rin t an oth er ch ip d ie im m ed iately n ext to th e p reviou s on e. After th e en tire wafer is im p rin ted with ch ip s, a cau stic solu tion wash es away th e areas wh ere th e ligh t stru ck th e p h otoresist, leavin g th e m ask im p rin ts of th e in d ivid u al ch ip vias (in tercon n ection s between layers) an d circu it p ath ways. Th en , an oth er layer of sem icon d u ctor m aterial is d ep osited on th e wafer with m ore p h otoresist on top , an d th e n ext m ask is u sed to p rod u ce th e n ext layer of circu itry. Usin g th is m eth od , th e layers of each ch ip are bu ilt on e on top of th e oth er, u n til th e ch ip s are com p leted . A com p leted circu lar wafer will h ave as m an y ch ip s im p rin ted on it as can p ossibly fit. Becau se each ch ip is n orm ally sq u are or rectan gu lar, th ere are som e u n u sed p ortion s at th e ed ges of th e wafer, bu t every attem p t is m ad e to u se every sq u are m illim eter of su rface. Th e stan d ard wafer size u sed in th e in d u stry tod ay is 200m m in d iam eter, or ju st u n d er 8 in ch es. Th is resu lts in a wafer of abou t 31,416 sq u are m illim eters. Th e cu rren t Pen tiu m II 300MHz p rocessor is m ad e u p of 7.5 m illion tran sistors u sin g a 0.35 m icron (m illion th of a m eter) p rocess. Th is p rocess resu lts in a d ie of exactly 14.2m m on each sid e, wh ich is 202 sq u are m illim eters of area. Th is m ean s th at abou t 150 total Pen tiu m II 300MHz ch ip s on th e .35 m icron p rocess can be m ad e from a sin gle 200m m -d iam eter wafer. Th e tren d in th e in d u stry is to go to both larger wafers an d a sm aller ch ip d ie p rocess. Process refers to th e size of th e in d ivid u al circu its an d tran sistors on th e ch ip . For exam p le, th e Pen tiu m II 333MHz is m ad e on a n ewer an d sm aller .25 m icron p rocess, wh ich red u ces th e total ch ip d ie size to on ly 10.2m m on each sid e, or a total ch ip area of 104 sq u are m illim eters. On th e sam e 200m m (8-in ch ) wafer as before, In tel can m ake

51

52

Chapter 3—M icroprocessor Types and Specifications

abou t 300 Pen tiu m II ch ip s u sin g th is p rocess, or d ou ble th e am ou n t over th e larger .35 m icron p rocess 300MHz version . Th e tren d in wafers is to m ove from th e cu rren t 200m m (8-in ch ) d iam eter to a bigger, 300m m (12-in ch ) d iam eter wafer. Th is will in crease su rface area d ram atically over th e sm aller 200m m d esign , an d boost ch ip p rod u ction to abou t 675 ch ip s p er wafer. In tel an d oth er m an u factu rers exp ect to h ave 300m m wafer p rod u ction in p lace ju st after th e year 2000. After th at h ap p en s, ch ip p rices sh ou ld d rop d ram atically as th e su p p ly in creases. Note th at all th e ch ip s on each wafer will n ot be good , esp ecially as a n ew p rod u ction lin e starts. As th e m an u factu rin g p rocess for a given ch ip or p rod u ction lin e is p erfected , m ore an d m ore of th e ch ip s will be good . Th e ratio of good to bad ch ip s on a wafer is called th e yield. Yield s well u n d er 50% are com m on wh en a n ew ch ip starts p rod u ction ; h owever, by th e en d of a given ch ip ’s life, th e yield s are n orm ally in th e 90% ran ge. Most ch ip m an u factu rers gu ard th eir yield figu res an d are very secretive abou t th em , as kn owled ge of yield p roblem s can give th eir com p etitors an ed ge. A low yield cau ses p roblem s both in th e cost p er ch ip an d in d elivery d elays to th eir cu stom ers. If a com p an y h as sp ecific kn owled ge of com p etitors’ im p rovin g yield s, th ey can set p rices or sch ed u le p rod u ction to get h igh er m arket sh are at a critical p oin t. For exam p le, AMD was p lagu ed by low-yield p roblem s d u rin g ’97 an d ’98, wh ich cost th em sign ifican t m arket sh are an d was ru m ored to cau se th e d ep artu re of th eir p rim ary ch ip d esign er, Vin h od Dah m . Th ey h ave been solvin g th e p roblem s, bu t th ey also sign ed u p with IBM Microelectron ics to m an u factu re som e of th eir p rocessors for th em . IBM is well-kn own as a lead er in ch ip m an u factu rin g tech n ologies, with ch ip p rod u ction p lan ts (called fabs) th at are secon d to n on e in term s of q u ality an d p rod u ction cap ability. After a wafer is com p lete, a sp ecial fixtu re tests each of th e ch ip s on th e wafer an d m arks th e bad on es to be sep arated ou t later. Th e ch ip s are th en cu t from th e wafer u sin g eith er a h igh -p owered laser or d iam on d saw. After bein g cu t from th e wafers, th e in d ivid u al d ie are th en retested , p ackaged , an d retested again . Th e p ackagin g p rocess is also referred to as bonding, becau se th e d ie is p laced in to a ch ip h ou sin g wh ere a sp ecial m ach in e bon d s fin e gold wires between th e d ie an d th e p in s on th e ch ip . Th e p ackage is th e con tain er for th e ch ip d ie, an d it essen tially seals it from th e en viron m en t. After th e ch ip s are bon d ed an d p ackaged , fin al testin g is d on e to d eterm in e both p rop er fu n ction an d rated sp eed . Differen t ch ip s in th e sam e batch will often ru n at d ifferen t sp eed s. Sp ecial test fixtu res ru n each ch ip at d ifferen t p ressu res, tem p eratu res, an d sp eed s, lookin g for th e p oin t at wh ich th e ch ip stop s workin g. At th is p oin t, th e m axim u m su ccessfu l sp eed is n oted an d th e fin al ch ip s are sorted in to bin s with th ose th at tested at a sim ilar sp eed . For exam p le, th e Pen tiu m II 233, 266, an d 300 are all exactly th e sam e ch ip m ad e u sin g th e sam e d ie. Th ey were sorted at th e en d of th e m an u factu rin g cycle by sp eed . On e in terestin g th in g abou t th is is th at as a m an u factu rer gain s m ore exp erien ce an d p erfects a p articu lar ch ip assem bly lin e, th e yield of th e h igh er-sp eed version s goes way

Processor Specifications

u p . Th is m ean s th at ou t of a wafer of 150 total ch ip s, p erh ap s m ore th an 100 of th em ch eck ou t at 300MHz, wh ile on ly a few won ’t ru n at th at sp eed . Th e p arad ox is th at In tel sells a lot m ore of th e lower-p riced 233 an d 266 ch ip s, so th ey will ju st d ip in to th e bin of 300MHz p rocessors an d label th em as 233 or 266 ch ip s an d sell th em th at way. Peop le began d iscoverin g th at m an y of th e lower-rated ch ip s wou ld actu ally ru n at sp eed s m u ch h igh er th an th ey were rated , an d th e bu sin ess of overclockin g was born . Overclockin g d escribes th e op eration of a ch ip at a sp eed h igh er th an it was rated for. In m an y cases, p eop le h ave su ccessfu lly accom p lish ed th is becau se, in essen ce, th ey h ad a h igh er-sp eed p rocessor alread y—it was m arked with a lower ratin g on ly becau se it was sold as th e slower version . In tel h as seen fit to p u t a stop to th is by bu ild in g overclock p rotection in to m ost of th eir n ewer ch ip s. Th is is u su ally d on e in th e bon d in g p rocess, wh ere th e ch ip s are in ten tion ally altered so th ey won ’t ru n at an y sp eed s h igh er th an th ey are rated . Norm ally th is in volves ch an gin g th e Bu s Freq u en cy (BF) p in s on th e ch ip , wh ich con trol th e in tern al m u ltip liers th e ch ip u ses. Even so, en terp risin g in d ivid u als h ave fou n d ways to ru n th eir m oth erboard s at bu s sp eed s h igh er th an n orm al, so even th ou gh th e ch ip won ’t allow a h igh er m u ltip lier, you can still ru n it at a sp eed h igh er th an it was d esign ed . I recen tly in stalled a 200MHz Pen tiu m p rocessor in a system , wh ich is su p p osed to ru n at a 3x m u ltip lier based off a 66MHz m oth erboard sp eed . I tried ch an gin g th e m u ltip lier to 3.5x bu t th e ch ip refu sed to go an y faster; in fact, it ran at th e sam e or lower sp eed th an before. Th is is a su re sign of overclock p rotection in sid e. My m oth erboard in clu d ed a ju m p er settin g for an u n au th orized sp eed of 75MHz, wh ich wh en m u ltip lied by 3x resu lted in an actu al p rocessor sp eed of 225MHz. Th is worked like a ch arm an d th e system is n ow ru n n in g fast an d clean . Note th at I am n ot n ecessarily recom m en d in g overclockin g for everybod y; in fact, I n orm ally d on ’t recom m en d it at all for an y im p ortan t system s. If you h ave a system you wan t to fool arou n d with , it is in terestin g to try. Like m y cars, I always seem to wan t to h otrod m y com p u ters! Physical Packaging Processors com e in m an y p h ysical p ackages, bu t th e m ost com m on are Pin Grid Array (PGA), Tap e Carrier Package (TCP), an d Sin gle Ed ge Cartrid ge (SEC) d esign s. Th e followin g section s exp lain th e PGA an d SEC p ackages, wh ich are u sed in d esktop system s. TCP is covered in Ch ap ter 15, alon g with th e oth er coverage of tech n ologies sp ecific to m obile com p u tin g. ◊◊ See “ Tape Carrier Packaging,” p. 923, and “ M obile M odule,” p. 926

PGA. PGA p ackagin g h as been th e m ost com m on ch ip p ackage u sed u n til recen tly. It was u sed startin g with th e 286 p rocessor all th e way back in th e ’80s an d is still u sed tod ay for Pen tiu m an d Pen tiu m Pro p rocessors. PGA takes its n am e from th e fact th at th e ch ip h as a grid -like array of p in s on th e bottom of th e p ackage. PGA ch ip s are in serted in to sockets, wh ich are often of a ZIF (Zero In sertion Force) d esign . A ZIF socket h as a lever to allow for easy in stallation an d rem oval of th e ch ip .

53

54

Chapter 3—M icroprocessor Types and Specifications

Most Pen tiu m p rocessors u se a variation on th e regu lar PGA called SPGA (Staggered Pin Grid Array), wh ere th e p in s are staggered on th e u n d ersid e of th e ch ip rath er th an in stan d ard rows an d colu m n s. Th is was d on e to m ove th e p in s closer togeth er an d d ecrease th e overall size of th e ch ip wh en a large n u m ber of p in s is req u ired . Figu re 3.2 sh ows a Pen tiu m Pro th at u ses th e d u al-p attern SPGA (on th e righ t) n ext to an old er Pen tiu m 66 th at u ses th e regu lar PGA. Note th at th e top h alf of th e Pen tiu m Pro sh own h ere h as ad d ition al p in s staggered am on g th e oth er rows an d colu m n s.

FIG. 3.2 PGA on Pen tiu m 66 (left) an d d u al-p attern SPGA on Pen tiu m Pro (righ t). Single Edge Cart ridge ( SEC) . Aban d on in g th e ch ip -in -a-socket ap p roach u sed by virtu ally all p rocessors u n til th is p oin t, th e Pen tiu m II ch ip is ch aracterized by its Sin gle Ed ge Con tact (SEC) cartrid ge d esign . Th e p rocessor, alon g with several L2 cach e ch ip s, is m ou n ted on a sm all circu it board (m u ch like an oversized m em ory SIMM), wh ich is th en sealed in a m etal an d p lastic cartrid ge. Th e cartrid ge is th en p lu gged in to th e m oth erboard th rou gh an ed ge con n ector called Slot 1, wh ich looks very m u ch like an ad ap ter card slot. Slot 1 is th e con n ection to th e m oth erboard , an d h as 242 p in s. Th e Slot 1 d im en sion s are sh own in Figu re 3.3. Th e SEC cartrid ge p rocessor is p lu gged in to slot 1 an d secu red with a p rocessor-reten tion m ech an ism , wh ich is a bracket th at h old s it in p lace. Th ere m ay also be a reten tion m ech an ism or su p p ort for th e p rocessor h eat sin k. Figu re 3.4 sh ows th e p arts of th e cover th at m ake u p th e SEC p ackage. Note th e large th erm al p late u sed to aid in d issip atin g th e h eat from th is p rocessor. Th e m ain reason for goin g to th is p ackage was to be able to m ove th e L2 cach e m em ory off of th e m oth erboard an d on to th e p rocessor in an econ om ical an d scalable way. Usin g th e SEC d esign , In tel can easily offer Pen tiu m II p rocessors with m ore or less cach e an d faster or slower cach e. Processor Socket s In tel h as created a set of socket d esign s—Socket 1 th rou gh Socket 8—u sed for th eir ch ip s from th e 486 th rou gh th e Pen tiu m Pro. Each socket is d esign ed to su p p ort a d ifferen t ran ge of origin al an d u p grad e p rocessors. Table 3.6 sh ows th e sp ecification s of th ese sockets.

1.27 .050

2.54±.127 .100±.005

4.75 .187

R 0.25 .010

2.00±.127 .079±.005 76.13 (MIN) 2.997 (MIN)

73 CONTACT PAIRS

72.00 2.832 2.50 .098

132.87±.25 5.231±.010

1.78±.03 .070±.001

2.50 .098

51.13 (MIN) 2.013 (MIN)

48 CONTACT PAIRS

47.00 1.850

.94 .037

9.50±.25 .374±.010

1.88±.10 .074±.004

Processor Specifications

FIG. 3.3 Pen tiu m II Processor Slot 1 d im en sion s (m etric/ En glish ).

55

Left

Left Latch

FIG. 3.4 Pen tiu m II Processor SEC p ackage p arts. Right Latch

Cover Side View

Cover

Top View

Right

Right Side

Right

Skirt

Thermal Plate Side View

Thermal Plate

Left

56 Chapter 3—M icroprocessor Types and Specifications

Processor Specifications

Table 3.6

Int el 486/ Pent ium CPU Socket Types and Specificat ions

Socket Num ber

No. of Pins

Pin Layout

Volt age

Support ed Processors

Socket 1

169

17×17 PGA

5v

SX/ SX2, DX/ DX2*, DX4 OverDrive

Socket 2

238

19×19 PGA

5v

SX/ SX2, DX/ DX2*, DX4 OverDrive, 486 Pentium OverDrive

Socket 3

237

19×19 PGA

5v/ 3.3v

SX/ SX2, DX/ DX2, DX4, 486 Pentium OverDrive

Socket 4

273

21×21 PGA

5v

Pentium 60/ 66, Pentium 60/ 66 OverDrive

Socket 5

320

37×37 SPGA

3.3v

Pentium 75-133, Pentium 75+ OverDrive

Socket 6**

235

19 ×19 PGA

3.3v

DX4, 486 Pentium OverDrive

Socket 7

321

37×37 SPGA

VRM

Pentium 75-300, Pentium 75+ OverDrive

Socket 8

387

Dual pattern SPGA

VRM

Pentium Pro

Slot 1

242

Slot

VRM

Pentium II

*DX 4 also can be supported with the addition of an afterm arket 3.3v voltage-regulator adapter. **Socket 6 was a paper standard only and was never actually im plem ented in any system s. PGA = Pin Grid Array SPGA = Staggered Pin Grid Array V RM = V oltage Regulator Module

Sockets 1, 2, 3, an d 6 are 486 p rocessor sockets an d are sh own togeth er in Figu re 3.5 so you can see th e overall size com p arison s an d p in arran gem en ts between th ese sockets. Sockets 4, 5, 7, an d 8 are Pen tiu m an d Pen tiu m Pro p rocessor sockets an d are also sh own togeth er in Figu re 3.6 so you can see th e overall size com p arison s an d p in arran gem en ts between th ese sockets. More d etailed d rawin gs of each socket are in clu d ed th rou gh ou t th e rem ain d er of th is section with th e d etailed d escrip tion s of th e sockets. Th e origin al OverDrive socket, n ow officially called Socket 1, is a 169-p in PGA socket. Moth erboard s th at h ave th is socket can su p p ort an y of th e 486SX, DX, an d DX2 p rocessors, an d th e DX2/ OverDrive version s. Th is typ e of socket is fou n d on m ost 486 system s th at origin ally were d esign ed for OverDrive u p grad es. Figu re 3.7 sh ows th e p in ou t of Socket 1. Socket 1

Socket 2

FIG. 3.5 486 Processor Sockets.

Socket 3

Socket 6

57

58

Chapter 3—M icroprocessor Types and Specifications

Socket 4

Socket 5

Socket 7

Socket 8

FIG. 3.6 Pen tiu m an d Pen tiu m Pro Processor Sockets.

17 16 15 14 13 12 11 10

9

8

7

6

5

4

3

2

1

A6

VSS

A10

VSS

VSS

VSS

VSS

VSS

A12

VSS

A14

NC

A23

A26

A27

NC BLAST# A3

VCC

A8

A11

VCC

VCC

VCC

VCC

A15

VCC

A18

VSS

VCC

A25

A28

ADS#

A4

S

S

R

R PCHK# PLOCK# BREQ A2

A7

A5

A9

A13

A16

A20

A22

A24

A21

A19

A17

VSS

A31

A30

A29

D0

DPO

D1

D2

Q VSS

VCC HLDA

Q P

P W/R# M/10# LOCK#

N

N VSS

VCC

D/C#

D4

VCC

VSS

VSS

VCC

PWT

D7

D6

VSS

VSS

VCC BEO#

D14

VCC

VSS

M

M L

L K

K

Socket 1

PCD

BE1# BE2#

D16

D5

VSS

VCC BRDY#

DP2

D3

VSS

VSS

VCC

D12

VCC

VSS

D15

D8

DP1

D10

VCC

VSS

J H

VCC

J

NC

H G

G BE3# RDY# KEN#

F

F VSS

VCC HOLD

E

E BOFF# BS8# A20M#

KEY

D17

D13

D9

NC

NC

NC

NC

D30

D28

D26

D27

VCC

VCC

CLK

D18

D11

NC

NC

VCC

NC

VCC

D31

VCC

D25

VSS

VSS

VSS

D21

D19

AHOLD INTR IGNNE# NC FERR# NC

VSS

NC

VSS

D29

VSS

D24

DP3

D23

NC

D22

D20

9

8

7

6

5

4

3

2

1

D

D BS16# RESET FLUSH # NC

C

C EADS# NC

NMI

UP#

B

B A

17 16 15 14 13 12 11 10

A

FIG. 3.7 In tel Socket 1 p in ou t. Th e origin al DX p rocessor d raws a m axim u m 0.9 am p s of 5v p ower in 33MHz form (4.5 watts) an d a m axim u m 1 am p in 50MHz form (5 watts). Th e DX2 p rocessor or OverDrive p rocessor d raws a m axim u m 1.2 am p s at 66MHz (6 watts). Th is m in or in crease in p ower req u ires on ly a p assive h eat sin k con sistin g of alu m in u m fin s th at are glu ed to th e p rocessor with th erm al tran sfer ep oxy. Passive h eat sin ks d on ’t h ave an y m ech an ical com p on en ts like fan s. Heat sin ks with fan s or oth er d evices th at u se p ower are called active h eat sin ks. OverDrive p rocessors rated at 40MHz or less d o n ot h ave h eat sin ks. W h en th e DX2 p rocessor was released , In tel alread y was workin g on th e n ew Pen tiu m p rocessor. Th e com p an y wan ted to offer a 32-bit, scaled -d own version of th e Pen tiu m as

Processor Specifications

an u p grad e for system s th at origin ally cam e with a DX2 p rocessor. Rath er th an ju st in creasin g th e clock rate, In tel created an all n ew ch ip with en h an ced cap abilities d erived from th e Pen tiu m . Th e ch ip , called th e Pen tiu m OverDrive Processor, p lu gs in to a p rocessor socket with th e Socket 2 or Socket 3 d esign . Th ese sockets will h old an y 486 SX, DX, or DX2 p rocessor, as well as th e Pen tiu m OverDrive. Becau se th is ch ip is essen tially a 32-bit version of th e (n orm ally 64-bit) Pen tiu m ch ip , m an y h ave taken to callin g it a Pentium -SX . It is available in 25/ 63MHz an d 33/ 83MHz version s. Th e first n u m ber in d icates th e base m oth erboard sp eed , wh ile th e secon d n u m ber in d icates th e actu al op eratin g sp eed of th e Pen tiu m OverDrive ch ip . As you can see, it is a clock-m u ltip lied ch ip th at ru n s at 2.5 tim es th e m oth erboard sp eed . Figu re 3.8 sh ows th e p in ou t con figu ration of th e official Socket 2 d esign .

A

B

C

D

E

F

G

H

J

K

L

M

N

P

Q

R

S

T

U

NC

RES

VSS

VCC

VSS

INIT

VSS

VSS

VCC

VCC

VCC

VSS

VSS

RES

VSS

VCC

VSS

RES

RES

RES AHOLD EADS# BS16# BOFF# VSS

BE3#

VSS

VSS

PCD

VSS

VSS

VSS

W/R#

VSS PCHK# INC

VSS

RDY#

VCC

VCC

BE1#

VCC

VCC

VCC M/10# VCC PLOCK# BLAST# A4

VSS

A3

A6

VCC

19

19

18 ADS# RES

17 16

RES RESET BS8#

VCC

VCC IGNNE# NMI FLUSH# A20M# HOLD KEN# STPCLK# BRDY# BE2# BE0# PWT

D/C# LOCK# HLDA BREQ

VSS

15 14 13 12 11 10

INC

PLUG PLUG PLUG

PLUG PLUG PLUG

A2

VCC

VSS

VSS

NC

PLUG

PLUG

A7

A8

A10

VSS

INC SMIACT# PLUG

PLUG

A5

A11

VSS

VSS

VCC

VSS

VSS

UP#

VSS

INC

5 4 3 2

14

VSS

VSS

VCC

INC

A9

VCC

INC

SMI#

INC

A13

VCC

VSS

VCC

VCC

VSS

VCC

D30

A16

VCC

VSS

VCC

VCC

D29

D31

D28

A20

VCC

VSS

VCC

VSS

VSS

VCC

D26

A22

A15

A12

VSS

RES

D24

D25

D27

PLUG

PLUG

A24

VCC

VSS

VSS

RES

DP3

VSS

VCC

PLUG

PLUG

A21

A18

A14

VSS

VSS

D23

VSS

VCC

PLUG PLUG PLUG

A19

VSS

INC

VSS

Socket 2

8

6

16 15

RES

VSS FERR# INC

9

7

18 17

INTR

KEY PLUG PLUG

VCC

RES

VSS

CLK

D17

D10

D15

D12

DP2

D16

D14

D7

D4

DP0

A30

A17

VCC

A23

VCC

VSS

D22

D21

D18

D13

VCC

D8

VCC

D3

D5

VCC

D6

VCC

D1

A29

VSS

A25

A26

VSS

D19

D11

D9

VSS

DP1

VSS

VSS

VCC

VSS

VSS

VSS

D2

D0

A31

A28

A27

RES

VSS

VCC

VSS

RES

RES

VSS

VCC

VCC

VCC

VSS

RES

RES

VSS

VCC

VSS

RES

RES

C

D

E

F

G

H

J

K

L

M

N

P

Q

R

S

T

U

PLUG

D20

1

13 12 11 10 9 8 7 6 5 4 3 2 1

PLUG PLUG

A

B

FIG. 3.8 238-p in In tel Socket 2 con figu ration . Notice th at alth ou gh th e n ew ch ip for Socket 2 is called Pen tiu m OverDrive, it is n ot a fu ll-scale (64-bit) Pen tiu m . In tel released th e d esign of Socket 2 a little p rem atu rely an d fou n d th at th e ch ip ran too h ot for m an y system s. Th e com p an y solved th is p roblem by ad d in g a sp ecial active h eat sin k to th e Pen tiu m OverDrive p rocessor. Th is active h eat sin k is a com bin ation of a stan d ard h eat sin k an d a bu ilt-in electric fan . Un like th e afterm arket glu e-on or clip -on fan s for p rocessors th at you m ay h ave seen , th is on e actu ally d raws 5v p ower d irectly from th e socket to d rive th e fan . No extern al con n ection to d isk d rive cables or th e p ower su p p ly is req u ired . Th e fan / h eat sin k assem bly clip s an d p lu gs d irectly in to th e p rocessor, p rovid in g for easy rep lacem en t sh ou ld th e fan ever fail.

59

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Chapter 3—M icroprocessor Types and Specifications

An oth er req u irem en t of th e active h eat sin k is ad d ition al clearan ce—n o obstru ction s for an area abou t 1.4 in ch es off th e base of th e existin g socket to allow for h eat-sin k clearan ce. Th e Pen tiu m OverDrive u p grad e will be d ifficu lt or im p ossible in system s th at were n ot d esign ed with th is featu re. An oth er p roblem with th is p articu lar u p grad e is p ower con su m p tion . Th e 5v Pen tiu m OverDrive p rocessor will d raw u p to 2.5 am p s at 5v (in clu d in g th e fan ) or 12.5 watts, wh ich is m ore th an d ou ble th e 1.2 am p s (6 watts) d rawn by th e DX2 66 p rocessor. In tel d id n ot p rovid e th is in form ation wh en it establish ed th e socket d esign , so th e com p an y set u p a testin g facility to certify system s for th erm al an d m ech an ical com p atibility with th e Pen tiu m OverDrive u p grad e. For th e greatest p eace of m in d , en su re th at you r system is certified com p atible before you attem p t th is u p grad e.

Not e See Intel’s Web site at ht t p:/ / w w w .int el.com for a comprehensive list of certified OverDrivecompatible systems.

Figu re 3.9 sh ows th e d im en sion s of th e Pen tiu m OverDrive p rocessor an d th e active h eat sin k/ fan assem bly.

Required Airspace

0.20"

1.963" 1.840"

0.40" 1.370" OverDrive Processor Active Fan/Heat Sink Unit Adhesive OverDrive Processor PGA Package

0.800" 0.970" 0.010"

0.160"

FIG. 3.9 Th e p h ysical d im en sion s of th e In tel Pen tiu m OverDrive p rocessor an d active h eat sin k. Becau se of p roblem s with th e origin al Socket 2 sp ecification an d th e en orm ou s h eat th e 5v version of th e Pen tiu m OverDrive p rocessor gen erates, In tel cam e u p with an im p roved d esign . Th e n ew p rocessor is th e sam e as th e p reviou s Pen tiu m OverDrive p rocessor, with th e excep tion th at it ru n s on 3.3v an d d raws a m axim u m 3.0 am p s of 3.3v (9.9 watts) an d 0.2 am p of 5v (1 watt) to ru n th e fan , for a total 10.9 watts. Th is con figu ration p rovid es a sligh t m argin over th e 5v version of th is p rocessor. Th e fan will be easy to rem ove from th e OverDrive p rocessor for rep lacem en t, sh ou ld it ever fail.

Processor Specifications

In tel h ad to create a n ew socket to su p p ort both th e DX4 p rocessor, wh ich ru n s on 3.3v, an d th e 3.3v Pen tiu m OverDrive p rocessor. In ad d ition to th e n ew 3.3v ch ip s, th is n ew socket su p p orts th e old er 5v SX, DX, DX2, an d even th e 5v Pen tiu m OverDrive ch ip . Th e d esign , called Socket 3, is th e m ost flexible u p grad able 486 d esign . Figu re 3.10 sh ows th e p in ou t sp ecification of Socket 3.

A

B

C

D

E

F

G

H

J

K

L

M

N

P

Q

R

S

T

U

NC

RES

VSS

VCC

VSS

INIT

VSS

VSS

VCC

VCC

VCC

VSS

VSS

RES

VSS

VCC

VSS

RES

RES

RES AHOLD EADS# BS16# BOFF# VSS

BE3#

VSS

VSS

PCD

VSS

VSS

VSS

W/R#

VSS PCHK# INC

VSS

RDY#

VCC

VCC

BE1#

VCC

VCC

VCC M/10# VCC PLOCK# BLAST# A4

VSS

19

19

18 ADS# RES

17 16

17 INTR

RES RESET BS8#

VCC

VCC IGNNE# NMI FLUSH# A20M# HOLD KEN# STPCLK# BRDY# BE2# BE0# PWT

D/C# LOCK# HLDA BREQ

A3

A6

VCC

VSS

PLUG PLUG PLUG

A2

VCC

VSS

VSS

A8

A10

VSS

15 14 13 12 11 10

UP#

VSS FERR# INC

INC

PLUG PLUG PLUG

NC

PLUG

PLUG

A7

PLUG

5 4 3 2

14

VSS

INC

INC SMIACT# PLUG

A5

A11

VSS

VSS

VSS

VSS

VCC

INC

A9

VCC

VSS

VSS

VCC

INC

SMI#

INC

A13

VCC

VSS

VCC

VCC

VSS

VCC

D30

A16

VCC

VSS

VCC

VCC

VSS

VCC

Socket 3

VCC

D29

D31

D28

A20

VSS

VSS

VCC

D26

A22

A15

A12

VSS

RES

D24

D25

D27

PLUG

PLUG

A24

VCC

VSS

VSS

RES

DP3

VSS

VCC

PLUG

PLUG

A21

A18

A14

VSS

VSS

D23

VSS

VCC

KEY PLUG PLUG

PLUG PLUG PLUG

A19

VSS

INC

VSS

VCC

RES

VSS

CLK

D17

D10

D15

D12

DP2

D16

D14

D7

D4

DP0

A30

A17

VCC

A23

VCC

PLUG D22

D21

D18

D13

VCC

D8

VCC

D3

D5

VCC

D6

VCC

D1

A29

VSS

A25

A26

VSS

PLUG

D19

D11

D9

VSS

DP1

VSS

VSS

VCC

VSS

VSS

VSS

D2

D0

A31

A28

A27

RES

KEY PLUG PLUG VCC

VSS

RES

RES

VSS

VCC

VCC

VCC

VSS

RES

RES

VSS

VCC

VSS

RES

RES

E

F

G

H

J

K

L

M

N

P

Q

R

S

T

U

8

6

16 15

RES

9

7

18

D20

1

13 12 11 10 9 8 7 6 5 4 3 2 1

A

B

C

D

FIG. 3.10 237-p in In tel Socket 3 con figu ration . Notice th at Socket 3 h as on e ad d ition al p in an d several oth ers p lu gged com p ared with Socket 2. Socket 3 p rovid es for better keyin g, wh ich p reven ts an en d u ser from accid en tally in stallin g th e p rocessor in an im p rop er orien tation . On e seriou s p roblem exists, h owever: Th is socket can n ot au tom atically d eterm in e th e typ e of voltage th at will be p rovid ed to it. A ju m p er is likely to be ad d ed on th e m oth erboard n ear th e socket to en able th e u ser to select 5v or 3.3v op eration .

Caut ion Because this jumper must be manually set, however, a user could install a 3.3v processor in this socket when it is configured for 5v operation. This installation will instantly destroy a very expensive chip when the system is powered on. It will be up to the end user to make sure that this socket is properly configured for voltage, depending on which type of processor is installed. If the jumper is set in 3.3v configuration and a 5v processor is installed, no harm will occur, but the system will not operate properly unless the jumper is reset for 5v.

61

62

Chapter 3—M icroprocessor Types and Specifications

Th e origin al Pen tiu m p rocessor 60MHz an d 66MHz version s h ad 273 p in s an d wou ld p lu g in to a 273-p in Pen tiu m p rocessor socket—a 5v-on ly socket, becau se all th e origin al Pen tiu m p rocessors ru n on 5v. Th is socket will accep t th e origin al Pen tiu m 60MHz or 66MHz p rocessor, an d th e OverDrive p rocessor. Figu re 3.11 sh ows th e p in ou t sp ecification of Socket 4.

1 A B C D E F G H J K L M N

INV

2

3

4

6

7

8

9

10 11 12 13 14 15 16 17 18 19 20 21 A

VCC

VCC

VCC

VCC

DP2

D23

VCC

VCC

VCC

VCC

VCC

VCC

VCC

VCC

DP5

D43

D45

D6

VSS

VSS

VSS

VSS

D17

D24

VSS

VSS

VSS

VSS

VSS

VSS

VSS

VSS

D41

D47

D48

B

VCC IERR# PM1/BP1 D4

DP1

D18

D22

D25

D29

D31

D26

D9

D10

D12

D19

D21

D33

D36

D34

D50

D52

C

D16

D20

DP3

D27

D32

D28

D30

D14

D40

D39

D37

D35

DP4

D38

D42

D44

Plug

D46

DP6

D54

DP7

D51

D49

D57

VCC

IV

M/10# EWBE# VCC

5

BP2

BP3

VCC PMO/BPO D0

D13

D15

VCC

VSS

D1

D2

D11

VCC

VSS

D3

D8

VSS

VCC

VSS FERR# DPO

VSS

IU

D5

D7

VCC

KEN# CACHE#

D53

D55

VSS

D63

D59

VSS

D56

D58

D62

VSS

VCC

VCC

D61

VSS

VCC

RESET D60

VSS

VCC

VSS WB/WT# EADS# HITM#

PEN# FRCMC# VSS

VCC

VSS

VSS

CLK

NA# BOFF#

Socket 4

VSS AHOLD NC BRDY#

D E F G H J K L M N

VCC

VSS

W/R#

NC

INTR

NMI

VSS

VCC

P

VCC

VSS

AP

ADS#

SMI#

TMS

VSS

VCC

P

Q

VCC VSS

HLDA BE1#

VCC

NC

VSS

VCC

Q

R

VCC

VSS PCHK# SCYC

R/S#

NC

VSS

VCC

R

S

VCC

VSS

NC IGNNE# TDO

S

T

VCC VSS BUSCHK# TCK SMIACT# BE4#

U

VCC FLUSH# PRDY BE0# A20M# BE2# BE6#

V

BE3# BREQ LOCK# D/C# HOLD

A28

VSS

VSS

VSS

VSS

VSS

VSS

VSS

VSS

VSS

VSS

W

BE7# HIT# APCHK# PCD

A30

VCC

VCC

VCC

VCC

VCC

VCC

VCC

VCC

VCC

VCC

VCC

5

6

7

8

9

1

2

PWT BE5#

3

4

Plug

Plug TRST# BT2

BT0

A26

A19

A17

A15

A13

A11

A9

A7

A3

NC

IBT

INIT

TDI

T

A24

A22

A20

A18

A16

A14

A12

A10

A8

A6

A5

A25

A23

A21

U

VSS

VSS

A31

A29

A27

V

VCC

VCC

A4

BT3

BT1

W

10 11 12 13 14 15 16 17 18 19 20 21

FIG. 3.11 273-p in In tel Socket 4 con figu ration . Som ewh at am azin gly, th e origin al Pen tiu m 66MHz p rocessor con su m es u p to 3.2 am p s of 5v p ower (16 watts), n ot in clu d in g p ower for a stan d ard active h eat sin k (fan ), wh ereas th e 66MHz OverDrive p rocessor th at rep laced it con su m es a m axim u m 2.7 am p s (13.5 watts), in clu d in g abou t 1 watt to d rive th e fan . Even th e origin al 60MHz Pen tiu m p rocessor con su m es u p to 2.91 am p s at 5v (14.55 watts). It m ay seem stran ge th at th e rep lacem en t p rocessor, wh ich is twice as fast, con su m es less p ower th an th e origin al, bu t th is h as to d o with th e m an u factu rin g p rocesses u sed for th e origin al an d OverDrive p rocessors. Alth ou gh both p rocessors will ru n on 5v, th e origin al Pen tiu m p rocessor was created with a circu it size of 0.8 m icron , m akin g th at p rocessor m u ch m ore p ower-h u n gry th an th e n ewer 0.6-m icron circu its u sed in th e OverDrive an d th e oth er Pen tiu m p rocessors. Sh rin kin g th e circu it size is on e of th e best ways to d ecrease p ower con su m p tion . Alth ou gh th e OverDrive p rocessor for Pen tiu m -based system s will d raw less p ower th an th e origin al p rocessor, ad d ition al clearan ce m ay h ave to be allowed for th e active h eat sin k

Processor Specifications

assem bly th at is m ou n ted on top . As in oth er OverDrive p rocessors with bu ilt-in fan s, th e p ower to ru n th e fan will be d rawn d irectly from th e ch ip socket, so n o sep arate p ower-su p p ly con n ection is req u ired . Also, th e fan will be easy to rep lace sh ou ld it ever fail. W h en In tel red esign ed th e Pen tiu m p rocessor to ru n at 75, 90, an d 100MHz, th e com p an y wen t to a 0.6-m icron m an u factu rin g p rocess an d 3.3v op eration . Th is ch an ge resu lted in lower p ower con su m p tion : on ly 3.25 am p s at 3.3v (10.725 watts). Th erefore, th e 100MHz Pen tiu m p rocessor can u se far less p ower th an even th e origin al 60MHz version . Th e n ewest 120 an d h igh er Pen tiu m , Pen tiu m Pro, an d Pen tiu m II ch ip s u se an even sm aller d ie 0.35-m icron p rocess. Th is resu lts in even lower p ower con su m p tion an d allows th e extrem ely h igh clock rates with ou t overh eatin g. Th e Pen tiu m 75 an d h igh er p rocessors actu ally h ave 296 p in s, alth ou gh th ey p lu g in to th e official In tel Socket 5 d esign , wh ich calls for a total 320 p in s. Th e ad d ition al p in s are u sed by th e Pen tiu m OverDrive for Pen tiu m p rocessors. Th is socket h as th e 320 p in s con figu red in a Staggered Pin Grid Array, in wh ich th e in d ivid u al p in s are staggered for tigh ter clearan ce. Several OverDrive p rocessors for existin g Pen tiu m s are cu rren tly available. If you h ave a first-gen eration Pen tiu m 60 or 66 with a Socket 4, you can p u rch ase a stan d ard Pen tiu m OverDrive ch ip th at effectively d ou bles th e sp eed of you r old p rocessor. An OverDrive ch ip with MMX tech n ology is available for secon d -gen eration 75MHz, 90MHz, an d 100MHz Pen tiu m s u sin g Socket 5 or Socket 7. Processor sp eed s after u p grad e are 125MHz for th e Pen tiu m 75, 150MHz for th e Pen tiu m 90, an d 166MHz for th e Pen tiu m 100. MMX greatly en h an ces p rocessor p erform an ce, p articu larly u n d er m u ltim ed ia ap p lication s, an d is d iscu ssed in th e section “Pen tiu m -MMX Processors” in th is ch ap ter. Figu re 3.12 sh ows th e stan d ard p in ou t for Socket 5. Th e Pen tiu m OverDrive for Pen tiu m Processors h as an active h eat sin k (fan ) assem bly th at d raws p ower d irectly from th e ch ip socket. Th e ch ip req u ires a m axim u m 4.33 am p s of 3.3v to ru n th e ch ip (14.289 watts) an d 0.2 am p of 5v p ower to ru n th e fan (1 watt), wh ich m ean s total p ower con su m p tion of 15.289 watts. Th is is less p ower th an th e origin al 66MHz Pen tiu m p rocessor req u ires, yet it ru n s a ch ip th at is as m u ch as fou r tim es faster! Th e last 486 socket was created esp ecially for th e DX4 an d th e 486 Pen tiu m OverDrive Processor. Socket 6 is a sligh tly red esign ed version of Socket 3, wh ich h as an ad d ition al two p in s p lu gged for p rop er ch ip keyin g. Socket 6 h as 235 p in s an d will accep t on ly 3.3v 486 or OverDrive p rocessors. Th is m ean s th at Socket 6 will accep t on ly th e DX4 an d th e 486 Pen tiu m OverDrive Processor. Becau se th is socket p rovid es on ly 3.3v, an d becau se th e on ly p rocessors th at p lu g in to it are d esign ed to op erate on 3.3v, th ere’s n o ch an ce th at d am agin g p roblem s will occu r, like th ose with th e Socket 3 d esign . In p ractice, Socket 6 h as seen very lim ited u se. Figu re 3.13 sh ows th e Socket 6 p in ou t.

63

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Chapter 3—M icroprocessor Types and Specifications

1 2

3

PLUG

VSS

4 5 6 D41

7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 VCC

VCC

VCC

VCC

VCC

VCC

VCC

VCC

VCC

VCC

VCC

VCC

D22

D18

D15

NC

A

A VCC

B C

INC

D47

E

D52

J L

VCC

N

R S

W Y Z AA

VCC

AE

AJ AL AM AN

VSS

DP3

VCC

NC

D30 VSS

D25

DP2

D28 VCC

D24

D26 VSS

VSS

D23 NC

D20 D21

D19 VCC

D16 D17

DP1 VSS

EWBE#

VSS

D58

PICD0

D60

VCC

DP7

TDO

NC

BF

INIT

1 2

A23 A21

PLUG

ADS# DC#

PWT

A27 PLUG

VSS

HIT#

VSS

A20M#

HITM# BUSCHK# BE0#

EADS#

W/R#

VCC5

INC

3

4 5 6

VSS

FLUSH#

VCC

BE1#

BE2#

VSS VCC

VSS

BE3#

BE4# VSS

VCC

NC BE5#

BE6# VSS

VCC

VSS BE7#

SCYC VSS

VCC

CLK

VCC

NC

VSS VCC

VSS

RESET A20 VSS VCC

NC

VSS

A17 A18

VSS VCC

VSS

A19

A15 A16

VSS VCC

VCC A13

A14 VSS

VCC

A12 VSS

VCC

VSS A9 A11 VSS

VCC

A8 A10

AB AD

A22 VSS A28 A3

A4 A6

AC

VCC

A25 A29

A7

VCC

VSS

A26

A31 A5

AE AF AG AH AJ AK

VSS A30

NC

Y Z AA

VCC

A24

W

VCC

VSS NC

U

X

VSS RS#

INTR

PCD

VCC

VSS

SMI# NMI

R S

V

VSS

IGNNE#

Q

T VCC

FRCMC# VCC PEN#

PRDY

LOCK#

HLDA

ADSC# VCC5

NC NC

NA#

PCHK#

AP

VCC VSS

VSS

STPCLK# VSS

PBREO# APCHK#

INC

NC VCC

N P

VSS

NC

VCC

Socket 5

J L M

VCC VSS

NC

HOLD

VSS

VSS TDI

G H K

VCC

TRST# CPUTYP VCC

INV

SMIACT#

VCC VSS

TCK

E F

VSS

PICD1

TMS

PBGNT#

VSS

VCC

VCC

D2

D0

C D

D4 D1

PICCLK

KEN#

PHITM#

BREQ

D6 D5

D3

PLUG

B D9

DP0

D7

PLUG

BOFF#

VSS

VCC

D8

BRDY#

VSS

VCC

D10

D12

PHIT# WB/WT#

VCC

D11

D14

BP3

BRDYC#

VCC

D13

AHOLD

VSS

AK

VSS

D33

D27

VSS

MI/O#

VSS VCC

AD AF AG AH

BP2

CACHE#

VSS

AB AC

D42

D35

D29

VSS

PM1BP1

VSS VCC

X

D37

D31

VSS

PM0BP0 FERR#

VCC

V

D39

D32

VSS

IERR#

VSS

T U

D40

D34

VSS

D62 D63

VCC

D36

VSS

D59 D61

VSS

P Q

D57

VCC

VSS

DP5

D56

VSS

M

VSS

D53

VSS VCC

VSS D38

D46

D51 D55

VSS

K

D44 D49

DP6 VCC

VSS DP4

D48

D54

F

VSS D45

D50

D

G H

D43

AL AM

VSS

AN

7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

Socket 5

FIG. 3.12 320-p in In tel Socket 5 con figu ration . Socket 7 is essen tially th e sam e as Socket 5 with on e ad d ition al key p in in th e op p osite in sid e corn er of th e existin g key p in . Socket 7, th erefore, h as 321 p in s total in a 21×21 SPGA arran gem en t. Th e real d ifferen ce with Socket 7 is n ot th e socket, bu t with th e com p an ion VRM (Voltage Regu lator Mod u le) th at m u st accom p an y it. Th e VRM is a sm all circu it board . Th e VRM con tain s all th e voltage regu lation circu itry u sed to d rop th e 5v p ower su p p ly sign al to th e correct voltage for th e p rocessor. Th e VRM was im p lem en ted for several good reason s. On e is th at voltage regu lators ten d to ru n h ot an d are very failu re-p ron e. Sold erin g th ese circu its on th e m oth erboard , as h as been d on e with th e Pen tiu m Socket 5 d esign , m akes it very likely th at a failu re of th e regu lator will req u ire a com p lete m oth erboard rep lacem en t. Alth ou gh tech n ically th e regu lator cou ld be rep laced , m an y are su rface-m ou n t sold ered , wh ich wou ld m ake th e wh ole p roced u re very tim e-con su m in g an d exp en sive. Besid es, in th is d ay an d age, wh en th e top -of-th e-lin e m oth erboard s are worth on ly $250 (less th e p rocessor an d an y m em ory), it is ju st n ot cost-effective to service th em . Havin g a rep laceable VRM p lu gged in to a socket will m ake it easy to rep lace th e regu lators sh ou ld th ey ever fail.

Processor Specifications

A

B

C

D

E

F

G

H

J

K

L

M

N

P

Q

R

S

T

U

VSS

VCC

VSS

INIT

VSS

VSS

VCC

VCC

VCC

VSS

VSS

RES

VSS

VCC

VSS

RES

RES

RES AHOLD EADS# BS16# BOFF# VSS

BE3#

VSS

VSS

PCD

VSS

VSS

VSS

W/R#

VSS PCHK# INC

VSS

RDY#

VCC

VCC

BE1#

VCC

VCC

VCC M/10# VCC PLOCK# BLAST# A4

VSS

A3

A6

VCC

19

19 PLUG RES

18 ADS# RES

17 16

RES RESET BS8#

VCC

VCC IGNNE# NMI FLUSH# A20M# HOLD KEN# STPCLK# BRDY# BE2# BE0# PWT

D/C# LOCK# HLDA BREQ

VSS

15 14 13 12 11 10

INC

PLUG PLUG PLUG

PLUG PLUG PLUG

A2

VCC

VSS

VSS

NC

PLUG

PLUG

A7

A8

A10

VSS

INC SMIACT# PLUG

PLUG

A5

A11

VSS

VSS

VCC

VSS

VSS

UP#

VSS

INC

5 4 3 2

14

VSS

VSS

VCC

INC

A9

VCC

INC

SMI#

INC

A13

VCC

VSS

VCC

VCC

VSS

VCC

D30

A16

VCC

VSS

VCC

VCC

D29

D31

D28

A20

VCC

VSS

VCC

VSS

VSS

VCC

D26

A22

A15

A12

VSS

RES

D24

D25

D27

PLUG

PLUG

A24

VCC

VSS

VSS

RES

DP3

VSS

VCC

PLUG

PLUG

A21

A18

A14

VSS

VSS

D23

VSS

VCC PLUG PLUG PLUG

PLUG PLUG PLUG

A19

VSS

INC

VSS

A23

VCC

Socket 6

8

6

16 15

RES

VSS FERR# INC

9

7

18 17

INTR

CLK

D17

D10

D15

D12

DP2

D16

D14

D7

D4

DP0

A30

A17

VCC

D18

D13

VCC

D8

VCC

D3

D5

VCC

D6

VCC

D1

A29

VSS

A25

A26

VSS

D11

D9

VSS

DP1

VSS

VSS

VCC

VSS

VSS

VSS

D2

D0

A31

A28

A27

RES

KEY PLUG PLUG VCC

VSS

RES

RES

VSS

VCC

VCC

VCC

VSS

RES

RES

VSS

VCC

VSS

RES

RES

E

F

G

H

J

K

L

M

N

P

Q

R

S

T

U

VCC

RES

PLUG D22 PLUG

D20

VSS D21 D19

1

13 12 11 10 9 8 7 6 5 4 3 2 1

A

B

C

D

FIG. 3.13 235-p in In tel Socket 6 con figu ration . Alth ou gh rep laceability is n ice, th e m ain reason beh in d th e VRM d esign is th at In tel is bu ild in g n ew Pen tiu m p rocessors to ru n on a variety of voltages. In tel h as several d ifferen t version s of th e Pen tiu m , Pen tiu m -MMX, Pen tiu m Pro, an d Pen tiu m II p rocessors th at ru n on 3.3v (called V R), 3.465v (called V RE), an d 3.1v, 2.8v, an d 2.45v. Becau se of th is, m ost n ewer m oth erboard s are eith er in clu d in g VRM sockets or bu ild in g ad ap table VRMs righ t in to th e m oth erboard . In oth er word s, if you wan t to p u rch ase a Pen tiu m board th at can be u p grad ed to th e n ext gen eration of even h igh er-sp eed Pen tiu m p rocessors, look for a system with a Socket 7 an d an in tegrated VRM su p p ortin g d ifferen t voltage selection s. Figu re 3.14 sh ows th e Socket 7 p in ou t. Socket 8 is a sp ecial SPGA socket featu rin g a wh op p in g 387 p in s! Th is was sp ecifically d esign ed for th e Pen tiu m Pro p rocessor with th e in tegrated L2 cach e. Th e ad d ition al p in s are to allow th e ch ip set to con trol th e L2 cach e th at is in tegrated in th e sam e p ackage as th e p rocessor. Figu re 3.15 sh ows th e Socket 8 p in ou t.

65

66

Chapter 3—M icroprocessor Types and Specifications

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 A VSS D41 VCC2 VCC2 VCC2 VCC2 VCC2 VCC2 VCC3 VCC3 VCC3 VCC3 VCC3 VCC3 D22 D18 D15 NC B VCC2 D43 VSS VSS VSS VSS VSS VSS VSS VSS VSS VSS VSS VSS D20 D16 D13 D11 C INC D47 D45 DP4 D38 D36 D34 D32 D31 D29 D27 D25 DP2 D24 D21 D17 D14 D10 D9 D D50 D48 D44 D40 D39 D37 D35 D33 DP3 D30 D28 D26 D23 D19 DP1 D12 D8 DP0 E D54 D52 D49 D46 D42 VSS VSS VCC2 NC VSS VCC3 VSS NC VCC3 VSS VSS D 7 D 6 VCC3 F DP6 D51 DP5 D5 D4 G VCC2 D55 D53 D3 D1 VCC3 H VSS D56 PICCLK VSS J VCC2 D57 D58 PICD0 D2 VCC3 K VSS D59 D0 VSS L VCC2 D61 D60 VCC3 PICD1 VCC3 M VSS D52 TCK VSS N VCC2 D63 DP7 TD0 TDI VCC3 P VSS IERR# TMS# VSS Q VCC2 PM0BP0 FERR# TRST# CPUTYP VCC3 R VSS PM1BP1 NC VSS S VCC2 BP2 BP3 NC NC VCC3 T VSS M/0# VCC3 VSS U VCC2 CACHE# INV VCC3 VSS VCC3 V VSS AHOLD STPCLK# VSS W VCC2 EWBE# KEN# NC NC VCC3 X VSS BRDY# BF1 VSS Y VCC2 BRDYC# NA# BF FRCMC# VCC3 Z VSS B0FF# PEN# VSS AA VCC2 PHIT# WB/WT# INIT IGNNE# VCC3 AB VSS HOLD SMI# VSS AC VCC2 PHITM# PRDY NMI RS# VCC3 AD VSS PBGNT# INTR VSS AE VCC2 PBREQ# APCHK# A23 D/P# VCC3 AF VSS PCHK# A21 VSS AG VCC2 SMIACT# PCD A27 A24 VCC3 AH VSS LOCK# KEY A26 A22 AJ BREQ HLDA ADS# VSS VSS VCC2 VSS NC VSS VCC3 VSS NC VSS VSS VCC3 VSS A31 A25 VSS AK AP D/C# HIT# A20M# BE1# BE3# BE5# BE7# CLK RESET A19 A17 A15 A13 A9 A5 A29 A28 AL VCC2DET PWT HITM# BUSCHK# BE0# BE2# BE4# BE6# SCYC NC A20 A18 A16 A14 A12 A11 A7 A3 VSS AM ADSC# EADS# W/R# VSS VSS VSS VSS VSS VSS VSS VSS VSS VSS VSS VSS A8 A4 A30 AN VCCS VCCS INC FLUSH# VCC2 VCC2 VCC2 VCC2 VCC2 VCC2 VCC3 VCC3 VCC3 VCC3 VCC3 A10 A6 NC VSS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚

˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚ ˚

FIG. 3.14 Socket 7 (Pen tiu m ) Pin ou t—top view. 47 45 43 41 39 37 35 33 31 29 27 25 23 21 19 17 15 13 11 9 7 5 3 1 BC BA AY AW AU AS AQ AN AL AJ AG AF AE AC AB AA Y X W U T S Q P N L K J G F E C B A

ew

op

Vi

T

2H2O

BC BA AY AW AU AS AQ AN AL AJ AG AF AE AC AB AA Y X W U T S Q P N L K J G F E C B A

46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 47 45 43 41 39 37 35 33 31 29 27 25 23 21 19 17 15 13 11 9 7 5 3 1

FIG. 3.15 Socket 8 (Pen tiu m Pro) Pin ou t sh owin g p ower p in location s.

VccS VccP Vss Vcc5 Other

A B C D E F G H J K L M N P Q R S T U V W X Y Z AA AB AC AD AE AF AG AH AJ AK AL AM AN

Processor Specifications

Zero Insert ion Force ( ZIF) Socket s. W h en In tel created th e Socket 1 sp ecification , th ey realized th at if u sers were goin g to u p grad e p rocessors, th ey h ad to m ake th e p rocess easier. Th ey fou n d th at it typ ically takes 100 p ou n d s of in sertion force to in stall a ch ip in a stan d ard 169-p in screw m ach in e socket 1. W ith th is m u ch force in volved , you easily cou ld d am age eith er th e ch ip or socket d u rin g rem oval or rein stallation . Becau se of th is, som e m oth erboard m an u factu rers began u sin g Low In sertion Force (LIF) sockets, wh ich typ ically req u ired on ly 60 p ou n d s of in sertion force for a 169-p in ch ip . W ith th e LIF or stan d ard socket, I u su ally ad vise rem ovin g th e m oth erboard —th at way you can su p p ort th e board from beh in d wh en you in sert th e ch ip . Pressin g d own on th e m oth erboard with 60 to 100 p ou n d s of force can crack th e board if it is n ot su p p orted p rop erly. A sp ecial tool is also req u ired to rem ove a ch ip from on e of th ese sockets. As you can im agin e, even th e low in sertion force was relative, an d a better solu tion was n eed ed if th e average p erson was goin g to ever rep lace th eir CPU. Man u factu rers began in sertin g sp ecial Zero In sertion Force (ZIF) sockets in th eir later Socket 1 m oth erboard d esign s. Sin ce th en , virtu ally all p rocessor sockets h ave been of th e ZIF d esign . Note, h owever, th at a given Socket X sp ecification h as n oth in g to d o with wh eth er it is ZIF, LIF, or stan d ard ; th e socket sp ecification covers on ly th e p in arran gem en t. Th ese d ays, n early all m oth erboard m an u factu rers are u sin g ZIF sockets. Th ese sockets alm ost elim in ate th e risk in volved in u p grad in g becau se n o in sertion force is n ecessary to in stall th e ch ip . Most ZIF sockets are h an d le-actu ated ; you sim p ly lift th e h an d le, d rop th e ch ip in to th e socket, an d th en close th e h an d le. Th is d esign m akes rep lacin g th e origin al p rocessor with th e u p grad e p rocessor an easy task. Slot 1. Slot 1 is u sed by th e SEC (Sin gle Ed ge Cartrid ge) d esign u sed with th e Pen tiu m II p rocessors. In sid e th e cartrid ge is a su bstrate card th at in clu d es th e p rocessor an d L2 cach e. Un like th e Pen tiu m Pro, th e L2 cach e is m ou n ted on th e circu it board an d n ot with in th e sam e ch ip p ackage as th e p rocessor. Th is allows In tel to u se afterm arket SRAM ch ip s in stead of m akin g th em in tern ally, an d also allows th em to m ake Pen tiu m II p rocessors with d ifferen t am ou n ts of cach e easily. For exam p le, th e Celeron version s of th e Pen tiu m II h ave n o L2 cach e, wh ile oth er fu tu re version s will h ave m ore th an th e stan d ard 512K in clu d ed in m ost Pen tiu m II p rocessors. Figu re 3.16 sh ows th e Slot 1 con n ector d im en sion s an d p in layou t.

67

FIG. 3.16 Slot 1 con n ector d im en sion s an d p in layou t. 2.00±.127 .079±.005 76.13 (MIN) 2.997 (MIN)

B73

4.75 .187

73 CONTACT PAIRS

72.00 2.832 2.50 .098

1.78±.03 .070±.001

2.50 .098

51.13 (MIN) 2.013 (MIN)

48 CONTACT PAIRS

47.00 1.850

9.50±.25 .374±.010

1.88±.10 .074±.004

.94 .037

B141

1.27 .050

2.54±.127 .100±.005

R 0.25 .010

B74

132.87±.25 5.231±.010

68 Chapter 3—M icroprocessor Types and Specifications

B1

A141

A74

A73

A1

Processor Specifications

Table 3.7 lists th e n am es of each of th e p in s in th e Slot 1 con n ector. Table 3.7

Signal List ing in Order by Pin Num ber

Pin No.

Pin Nam e

Pin No.

Pin Nam e

A1 A2

VCC_VTT

B1

EM I

GND

B2

FLUSH#

A3

VCC_VTT

B3

SM I#

A4

IERR#

B4

INIT#

A5

A20M #

B5

VCC_VTT

A6

GND

B6

STPCLK#

A7

FERR#

B7

TCK

A8

IGNNE#

B8

SLP#

A9

TDI

B9

VCC_VTT

A10

GND

B10

TM S

A11

TDO

B11

TRST#

A12

PWRGOOD

B12

Reserved

A13

TESTHI

B13

VCC_CORE

A14

GND

B14

Reserved

A15

THERM TRIP#

B15

Reserved

A16

Reserved

B16

LINT[1]/ NM I

A17

LINT[0]/ INTR

B17

VCC_CORE

A18

GND

B18

PICCLK

A19

PICD[0]

B19

BP#[2]

A20

PREQ#

B20

Reserved

A21

BP#[3]

B21

BSEL#

A22

GND

B22

PICD[1]

A23

BPM #[0]

B23

PRDY#

A24

BINIT#

B24

BPM #[1]

A25

DEP#[0]

B25

VCC_CORE

A26

GND

B26

DEP#[2]

A27

DEP#[1]

B27

DEP#[4]

A28

DEP#[3]

B28

DEP#[7]

A29

DEP#[5]

B29

VCC_CORE

A30

GND

B30

D#[62]

A31

DEP#[6]

B31

D#[58]

A32

D#[61]

B32

D#[63]

A33

D#[55]

B33

VCC_CORE

A34

GND

B34

D#[56]

A35

D#[60]

B35

D#[50]

A36

D#[53]

B36

D#[54] (continues)

69

70

Chapter 3—M icroprocessor Types and Specifications

Table 3.7

Signal List ing in Order by Pin Num ber Cont inued

Pin No.

Pin Nam e

Pin No.

Pin Nam e

A37

D#[57]

B37

VCC_CORE

A38

GND

B38

D#[59]

A39

D#[46]

B39

D#[48]

A40

D#[49]

B40

D#[52]

A41

D#[51]

B41

EM I

A42

GND

B42

D#[41]

A43

D#[42]

B43

D#[47]

A44

D#[45]

B44

D#[44]

A45

D#[39]

B45

VCC_CORE

A46

GND

B46

D#[36]

A47

Reserved

B47

D#[40]

A48

D#[43]

B48

D#[34]

A49

D#[37]

B49

VCC_CORE

A50

GND

B50

D#[38]

A51

D#[33]

B51

D#[32]

A52

D#[35]

B52

D#[28]

A53

D#[31]

B53

VCC_CORE

A54

GND

B54

D#[29]

A55

D#[30]

B55

D#[26]

A56

D#[27]

B56

D#[25]

A57

D#[24]

B57

VCC_CORE

A58

GND

B58

D#[22]

A59

D#[23]

B59

D#[19]

A60

D#[21]

B60

D#[18]

A61

D#[16]

B61

EM I

A62

GND

B62

D#[20]

A63

D#[13]

B63

D#[17]

A64

D#[11]

B64

D#[15]

A65

D#[10]

B65

VCC_CORE

A66

GND

B66

D#[12]

A67

D#[14]

B67

D#[7]

A68

D#[9]

B68

D#[6]

A69

D#[8]

B69

VCC_CORE

A70

GND

B70

D#[4]

A71

D#[5]

B71

D#[2]

A72

D#[3]

B72

D#[0]

A73

D#[1]

B73

VCC_CORE

A74

GND

B74

RESET#

Processor Specifications

Pin No.

Pin Nam e

Pin No.

Pin Nam e

A75

BCLK

B75

BR1#

A76

BR0#

B76

FRCERR

A77

BERR#

B77

VCC_CORE

A78

GND

B78

A#[35]

A79

A#[33]

B79

A#[32]

A80

A#[34]

B80

A#[29]

A81

A#[30]

B81

EM I

A82

GND

B82

A#[26]

A83

A#[31]

B83

A#[24]

A84

A#[27]

B84

A#[28]

A85

A#[22]

B85

VCC_CORE

A86

GND

B86

A#[20]

A87

A#[23]

B87

A#[21]

A88

Reserved

B88

A#[25]

A89

A#[19]

B89

VCC_CORE

A90

GND

B90

A#[15]

A91

A#[18]

B91

A#[17]

A92

A#[16]

B92

A#[11]

A93

A#[13]

B93

VCC_CORE

A94

GND

B94

A#[12]

A95

A#[14]

B95

A#[8]

A96

A#[10]

B96

A#[7]

A97

A#[5]

B97

VCC_CORE

A98

GND

B98

A#[3]

A99

A#[9]

B99

A#[6]

A100

A#[4]

B100

EM I

A101

BNR#

B101

SLOTOCC#

A102

GND

B102

REQ#[0]

A103

BPRI#

B103

REQ#[1]

A104

TRDY#

B104

REQ#[4]

A105

DEFER#

B105

VCC_CORE

A106

GND

B106

LOCK#

A107

REQ#[2]

B107

DRDY#

A108

REQ#[3]

B108

RS#[0]

A109

HITM #

B109

VCC5

A110

GND

B110

HIT#

A111

DBSY#

B111

RS#[2]

A112

RS#[1]

B112

Reserved (continues)

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Chapter 3—M icroprocessor Types and Specifications

Table 3.7

Signal List ing in Order by Pin Num ber Cont inued

Pin No.

Pin Nam e

Pin No.

Pin Nam e

A113

Reserved

B113

VCC_L2

A114

GND

B114

RP#

A115

ADS#

B115

RSP#

A116

Reserved

B116

AP#[1]

A117

AP#[0]

B117

VCC_L2

A118

GND

B118

AERR#

A119

VID[2]

B119

VID[3]

A120

VID[1]

B120

VID[0]

A121

VID[4]

B121

VCC_L2

CPU Operat ing Volt ages On e tren d clear to an ybod y th at h as followed p rocessor d esign is th at th e op eratin g voltages h ave gon e lower an d lower. Th e ben efits of lower voltage are th reefold , th e m ost obviou s bein g th at with lower voltage com es lower overall p ower con su m p tion . By con su m in g less p ower, th e system is less exp en sive to ru n , bu t m ore im p ortan tly for p ortable or m obile system s, it ru n s m u ch lon ger on existin g battery tech n ology. Th e em p h asis on battery op eration h as d riven m an y of th e ad van ces in lowerin g p rocessor voltage, becau se th is h as a great effect on battery life. Th e secon d ben efit is th at with less voltage an d th erefore less p ower con su m p tion , th ere is less h eat p rod u ced . Processors th at ru n cooler can be p acked in to system s m ore tigh tly an d will last lon ger. Th e th ird ben efit is th at a p rocessor ru n n in g cooler on less p ower can be m ad e to ru n faster. Lowerin g th e voltage h as been on e of th e key factors in allowin g th e clock rates of p rocessors to go h igh er an d h igh er. Un til th e release of th e m obile Pen tiu m an d both d esktop an d m obile Pen tiu m MMX, m ost p rocessors u sed a sin gle voltage level to p ower both th e core as well as ru n th e in p u t/ ou tp u t circu its. Origin ally m ost p rocessors ran both th e core an d I/ O circu its at 5 volts, wh ich later was red u ced to 3.5 or 3.3 volts to lower p ower con su m p tion . W h en a sin gle voltage is u sed for both th e in tern al p rocessor core p ower as well as th e extern al p rocessor bu s an d I/ O sign als, th e p rocessor is said to h ave a single or unified power plane design. W h en origin ally d esign in g a version of th e Pen tiu m p rocessor for m obile or p ortable com p u ters, In tel cam e u p with a sch em e to d ram atically red u ce th e p ower con su m p tion , wh ile still rem ain in g com p atible with th e existin g 3.3v ch ip sets, bu s logic, m em ory, an d oth er com p on en ts. Th e resu lt was a dual-plane or split-plane power design wh ere th e p rocessor core ran off of a lower voltage wh ile th e I/ O circu its rem ain ed at 3.3v. Th is was origin ally called Voltage Red u ction Tech n ology (VRT) an d first d ebu ted in th e Mobile Pen tiu m p rocessors released in 1996. Later th is d u al-p lan e p ower d esign also ap p eared in d esktop p rocessors like th e Pen tiu m MMX, wh ich u sed 2.8v to p ower th e core, an d 3.3v

Processor Specifications

for th e I/ O circu its. Now m ost recen t p rocessors wh eth er for m obile or d esktop u se featu re a d u al-p lan e p ower d esign . Som e of th e m ore recen t Mobile Pen tiu m II p rocessors ru n on as little as 1.6v for th e core, wh ile still m ain tain in g com p atibility with 3.3v com p on en ts for I/ O. Kn owin g th e p rocessor voltage req u irem en ts is n ot a big issu e with Pen tiu m Pro (Socket 8) or Pen tiu m II (Slot 1 or Slot 2) p rocessors, becau se th ese sockets an d slots h ave sp ecial Voltage ID (VID) p in s wh ich th e p rocessor u ses to sign al to th e m oth erboard th e exact voltage req u irem en ts. Th is en ables th e voltage regu lators bu ilt in to th e m oth erboard to be au tom atically set to th e correct voltage levels by m erely in stallin g th e p rocessor. Un fortu n ately th is au tom atic voltage settin g featu re is n ot available on Socket 7 an d earlier m oth erboard an d p rocessor d esign s. Th is m ean s you m u st n orm ally set ju m p ers or oth erwise con figu re th e m oth erboard accord in g to th e voltage req u irem en ts of th e p rocessor you are in stallin g. Pen tiu m (Socket 4, 5 or 7) p rocessors h ave ru n on a n u m ber of voltages, bu t th e latest MMX version s are all 2.8v, excep t for m obile Pen tiu m p rocessors wh ich are as low as 1.8v. Table 3.8 lists th e voltage settin gs u sed by In tel Pen tiu m (n on MMX) p rocessors th at u se a sin gle p ower p lan e. Th is m ean s th at both th e CPU core an d th e I/ O p in s ru n at th e sam e voltage. Table 3.8 Single-Plane Pent ium Processor Volt ages Nam e

Socket Type

Com m ent

Nom inal Volt age

Accept able Range

+5v

Socket 4

Power supply

5.000v

4.750v–5.250v

STD (3.3v)

Socket 5 or 7

Standard

3.300v

3.135v–3.600v

VR (3.3v)

Socket 5 or 7

Voltage Reduced

3.380v

3.300v–3.465v

VRE (3.5v)

Socket 5 or 7

VR Extended

3.500v

3.400v–3.600v

Table 3.9 sh ows th e voltage settin gs req u ired by p rocessors th at u se a d u al-p lan e (sp lit voltage) wh ere th e voltage in d icated is th e core req u irem en t. All I/ O p in s on d u al p lan e p rocessors are 3.3v. Note th at d u al-p lan e p rocessors are su p p orted on ly in Socket 7 p rocessor sockets. Table 3.9 Dual-Plane Pent ium Processor Volt ages ( Socket 7 only) Nam e Range

Com m ent

Nom inal Volt age

Accept able

M M X (2.8v)

Intel M M X

2.800v

2.700v–2.900v

2.9v

AM D K6 M odel 6

2.800v

2.700v–2.900v

3.2v

AM D K6 M odel 6

2.800v

2.700v–2.900v

2.2v

AM D K6 M odel 7

2.800v

2.700v–2.900v

M M X (2.8v)

Cyrix 6x86M X

2.800v

2.700v–2.900v

M M X (2.8v)

Cyrix 6x86L

2.800v

2.700v–2.900v (continues)

73

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Chapter 3—M icroprocessor Types and Specifications

Table 3.9 Dual-Plane Pent ium Processor Volt ages ( Socket 7 only) Cont inued Nam e Range

Com m ent

Nom inal Volt age

Accept able

STD (3.3v)

Cyrix 6x86

3.300v

3.135v–3.600v

VRE (3.5v)

Cyrix 6x86

3.500v

3.400v–3.600v

Norm ally th e accep table ran ge is p lu s or m in u s 5% from th e n om in al in ten d ed settin g. Most Socket 7 an d later Pen tiu m m oth erboard s su p p ly several voltages (su ch as 2.5V, 2.7V, 2.8V, an d 2.9V) for com p atibility with fu tu re d evices. A voltage regu lator bu ilt in to th e m oth erboard con verts th e p ower su p p ly voltage in to th e d ifferen t levels req u ired by th e p rocessor core. Ch eck th e d ocu m en tation for you r m oth erboard an d p rocessor to fin d th e ap p rop riate settin gs. Th e Pen tiu m Pro an d Pen tiu m II p rocessors au tom atically d eterm in e th eir voltage settin gs by con trollin g th e m oth erboard -based voltage regu lator th rou gh bu ilt-in Voltage ID (VID) p in s. Th ose are exp lain ed in m ore d etail in th e Pen tiu m Pro an d Pen tiu m II section s. Heat and Cooling Problem s Heat can be a p roblem in an y h igh -p erform an ce system . Th e h igh er-sp eed p rocessors n orm ally con su m e m ore p ower an d th erefore gen erate m ore h eat. If you r system is based on an y of th e 66MHz or faster p rocessors, you m u st d issip ate th e extra th erm al en ergy; th e fan in sid e you r com p u ter case m ay n ot be able to h an d le th e load . To cool a system in wh ich p rocessor h eat is a p roblem , you can bu y (for less th an $5 in m ost cases) a sp ecial attach m en t for th e CPU ch ip called a heat sink, wh ich d raws h eat away from th e CPU ch ip . Man y ap p lication s m ay n eed on ly a larger stan d ard h eat sin k with ad d ition al or lon ger fin s for a larger coolin g area. Several h eat-sin k m an u factu rers are listed in Ap p en d ix A, “Ven d or List.” Two m ain typ es of h eat sin ks on th e m arket are active an d p assive. Active h eat sin ks u se a fan or oth er electric coolin g d evice, wh ich req u ire p ower to ru n . Th e fan typ e is m ost com m on bu t som e u se a p eltier coolin g d evice, wh ich is basically a solid -state refrigerator. Active h eat sin ks req u ire p ower an d n orm ally p lu g in to a d isk d rive-p ower con n ector or sp ecial 12v fan p ower con n ectors on th e m oth erboard . If you d o get a fan typ e h eat sin k, be aware th at th ere are som e of very p oor q u ality on th e m arket. Th e bad on es h ave m otors th at u se sleeve bearin gs, th at freeze u p after a very sh ort life. I on ly recom m en d fan s with ball-bearin g m otors wh ich will last abou t 10 tim es lon ger th an th e sleevebearin g typ es. Of cou rse, th ey cost m ore, bu t on ly abou t twice as m u ch , wh ich m ean s you ’ll save m on ey in th e lon g ru n . Th e p assive-typ e h eat sin ks are 100% reliable, as th ey h ave n o m ech an ical com p on en ts to fail. Th ey are basically an alu m in u m -fin n ed rad iator th at d issip ates h eat th rou gh con vection . Passive typ es d on ’t work well u n less th ere is som e airflow across th e fin s, n orm ally p rovid ed by th e p ower su p p ly fan or an extra fan in th e case. If you r case or p ower su p p ly is p rop erly d esign ed , you can u se a less exp en sive p assive h eat sin k in stead of an active on e.

Processor Specifications

Most of th e n ewer system s on th e m arket u se an im p roved m oth erboard form factor (sh ap e) d esign called ATX . System s m ad e from th is typ e of m oth erboard an d case allow for im p roved coolin g of th e p rocessor d u e to its bein g rep osition ed in th e case n ear th e p ower su p p ly. Also, th e p ower su p p ly fan in m ost ATX system s is d esign ed to blow cool air d irectly on th e ch ip , allowin g for a p assive (n o fan ) h eat sin k to be u sed . ◊◊ See “ ATX Style,” p. 398 ◊◊ See “ ATX,” p. 173

M at h Coprocessors Th e n ext several section s cover th e floatin g-p oin t u n it con tain ed in th e p rocessor, wh ich was form erly a sep arate extern al m ath cop rocessor in th e 386 an d old er ch ip s. Old er cen tral p rocessin g u n its d esign ed by In tel (an d clon ed by oth er com p an ies) u sed an extern al m ath -cop rocessor ch ip . However, wh en In tel in trod u ced th e 486DX, th ey in clu d ed a bu ilt-in m ath cop rocessor, an d every p rocessor bu ilt by In tel (an d AMD an d Cyrix, for th at m atter) sin ce th en in clu d es a m ath cop rocessor. Cop rocessors p rovid e h ard ware for floatin g-p oin t m ath , wh ich oth erwise wou ld create an excessive d rain on th e m ain CPU. Math ch ip s sp eed you r com p u ter’s op eration on ly wh en you are ru n n in g software d esign ed to take ad van tage of th e cop rocessor. Math ch ip s (as cop rocessors som etim es are called ) can p erform h igh -level m ath em atical op eration s—lon g d ivision , trigon om etric fu n ction s, roots, an d logarith m s, for exam p le— at 10 to 100 tim es th e sp eed of th e corresp on d in g m ain p rocessor. Th e op eration s p erform ed by th e m ath ch ip are all op eration s th at m ake u se of n on in teger n u m bers (n u m bers th at con tain d igits after th e d ecim al p oin t). Th e n eed to p rocess n u m bers in wh ich th e d ecim al is n ot always th e last ch aracter lead s to th e term floating point becau se th e d ecim al (p oin t) can m ove (float), d ep en d in g on th e op eration . Th e in teger u n its in th e p rim ary CPU work with in teger n u m bers, so th ey p erform ad d ition , su btraction , an d m u ltip lication op eration s. Th e p rim ary CPU is d esign ed to h an d le su ch com p u tation s; th ese op eration s are n ot offload ed to th e m ath ch ip . Th e in stru ction set of th e m ath ch ip is d ifferen t from th at of th e p rim ary CPU. A p rogram m u st d etect th e existen ce of th e cop rocessor an d th en execu te in stru ction s written exp licitly for th at cop rocessor; oth erwise, th e m ath cop rocessor d raws p ower an d d oes n oth in g else. Fortu n ately, m ost m od ern p rogram s th at can ben efit from th e u se of th e cop rocessor correctly d etect an d u se th e cop rocessor. Th ese p rogram s u su ally are m ath in ten sive: sp read sh eet p rogram s, d atabase ap p lication s, statistical p rogram s, an d grap h ics p rogram s, su ch as com p u ter-aid ed d esign (CAD) software. W ord p rocessin g p rogram s d o n ot ben efit from a m ath ch ip an d th erefore are n ot d esign ed to u se on e. Table 3.10 su m m arizes th e cop rocessors available for th e In tel fam ily of p rocessors. Table 3.10

M at h Coprocessor Sum m ary

Processor

Coprocessor

8086

8087

8088

8087 (continues)

75

76

Chapter 3—M icroprocessor Types and Specifications

Table 3.10

M at h Coprocessor Sum m ary Cont inued

Processor

Coprocessor

80286

80287

80386SX

80387SX

80386SL

80387SX

80386SLC

80387SX

80486SLC

80387SX

80486SLC2

80387SX

80386DX

80387DX

80486SX

80487SX, DX2/ OverDrive*

80487SX*

Built-in FPU

80486SX2

DX2/ OverDrive**

80486DX

Built-in FPU

80486DX2

Built-in FPU

80486DX4

Built-in FPU

Pentium/ Pentium-M M X

Built-in FPU

Pentium Pro

Built-in FPU

Pentium II

Built-in FPU

FPU = Floating-Point Unit *The 487SX chip is a m odified pinout 486DX chip with the m ath coprocessor enabled. W hen you plug in a 487SX chip, it disables the 486SX m ain processor and takes over all processing. **The DX 2/OverDrive is equivalent to the SX 2 with the addition of a functional FPU.

W ith in each 8087 grou p , th e m axim u m sp eed of th e m ath ch ip s varies. A su ffix d igit after th e m ain n u m ber, as sh own in Table 3.11, in d icates th e m axim u m sp eed at wh ich a system can ru n a m ath ch ip . Table 3.11

M axim um M at h Chip Speeds

Part

Speed

8087

5M Hz

8087-3

5M Hz

8087-2

8M Hz

8087-1

10M Hz

80287

6M Hz

80287-6

6M Hz

80287-8

8M Hz

80287-10

10M Hz

Th e 387 m ath cop rocessors, an d th e 486 or 487 an d Pen tiu m p rocessors, always in d icate th eir m axim u m sp eed ratin g in MHz in th e p art-n u m ber su ffix. A 486DX2-66, for exam p le, is rated to ru n at 66MHz. Som e p rocessors in corp orate clock m u ltip lication , wh ich m ean s th at th ey m ay ru n at d ifferen t sp eed s com p ared with th e rest of th e system .

Processor Specifications

Tip The performance increase in programs that use the math chip can be dramatic—usually, a geometric increase in speed occurs. If the primary applications that you use can take advantage of a math coprocessor, you should upgrade your system to include one.

Most system s th at u se th e 386 or earlier processors are socketed for a m ath coprocessor as an option , bu t th ey do n ot in clu de a coprocessor as stan dard equ ipm en t. A few system s on th e m arket don ’t even h ave a socket for th e coprocessor becau se of cost an d size con sideration s. Th ese system s are u su ally low-cost or portable system s, su ch as older laptops, th e IBM PS/ 1, an d th e PCjr. For m ore specific in form ation abou t m ath coprocessors, see th e discu ssion s of th e specific ch ips—8087, 287, 387, an d 487SX—in th e later section s. Table 3.12 sh ows som e of th e specification s of th e variou s m ath coprocessors. Table 3.12

Int el M at h Coprocessor Specificat ions

Pow er Case M inim um Case M axim um No. of Dat e Nam e Consum pt ion Tem perat ure Tem perat ure Transist ors Int roduced 8087

3 watts

0°C, 32°F

85°C, 185°F

45,000

1980

287

3 watts

0°C, 32°F

85°C, 185°F

45,000

1982

287XL

1.5 watts

0°C, 32°F

85°C, 185°F

40,000

1990

387SX

1.5 watts

0°C, 32°F

85°C, 185°F

120,000

1988

387DX 1.5 watts

0°C, 32°F

85°C, 185°F

120,000

1987

Most often , you can learn wh at CPU an d m ath cop rocessor are in stalled in a p articu lar system by ch eckin g th e m arkin gs on th e ch ip . Processor Bugs Processor m an u factu rers u se sp ecialized eq u ip m en t to test th eir own p rocessors, bu t you h ave to settle for a little less. Th e best p rocessor-testin g d evice to wh ich you h ave access is a system th at you kn ow is fu n ction al; you th en can u se th e d iagn ostics available from variou s u tility software com p an ies or you r system m an u factu rer to test th e m oth erboard an d p rocessor fu n ction s. Com p an ies su ch as Diagsoft, Sym an tec, Micro 2000, Trin itech , Data Dep ot, an d oth ers offer sp ecialized d iagn ostics software th at can test th e system , in clu d in g th e p rocessor. If you d on ’t wan t to p u rch ase th is kin d of software, you can p erform a q u ick-an d -d irty p rocessor evalu ation by u sin g th e d iagn ostics p rogram su p p lied with you r system . Becau se th e p rocessor is th e brain of a system , m ost system s d on ’t fu n ction with a d efective on e. If a system seem s to h ave a d ead m oth erboard , try rep lacin g th e p rocessor with on e from a fu n ction in g m oth erboard th at u ses th e sam e CPU ch ip . You m ay fin d th at th e p rocessor in th e origin al board is th e cu lp rit. If th e system con tin u es to p lay d ead , h owever, th e p roblem is elsewh ere. A few system p roblem s are bu ilt in at th e factory, alth ou gh th ese bu gs or d esign d efects are rare. By learn in g to recogn ize th ese p roblem s, you m ay avoid u n n ecessary rep airs or rep lacem en ts. Each p rocessor section d escribes several kn own d efects in th at gen eration

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Chapter 3—M icroprocessor Types and Specifications

of p rocessors. For m ore in form ation on th ese bu gs an d d efects, con tact th e p rocessor m an u factu rer. Processor Updat e Feat ure All p rocessors can con tain d esign d efects or errors. Man y tim es, th e effects of an y given bu g can be avoid ed by im p lem en tin g h ard ware or software workarou n d s. In tel d ocu m en ts th ese bu gs an d workarou n d s well for th eir p rocessors in th eir p rocessor Sp ecification Up d ate m an u als; th is m an u al is available from th eir W eb site. Most of th e oth er p rocessor m an u factu rers also h ave bu lletin s or tip s on th eir W eb sites listin g an y p roblem s or sp ecial fixes or p atch es for th eir ch ip s. Previou sly, th e on ly way to fix a p rocessor bu g was to work arou n d it or rep lace th e ch ip with on e th at h ad th e bu g fixed . Now, a n ew featu re bu ilt in to th e In tel P6 p rocessors, in clu d in g th e Pen tiu m Pro an d Pen tiu m II, can allow m an y bu gs to be fixed by alterin g th e m icrocod e in th e p rocessor. Th ese p rocessors in corp orate a n ew featu re called reprogram m able m icrocode, wh ich allows certain typ es of bu gs to be worked arou n d via m icrocod e u p d ates. Th e m icrocod e u p d ates resid e in th e system ROM BIOS an d are load ed in to th e p rocessor by th e system BIOS d u rin g th e Power-On Self Test, or POST. Each tim e th e system is rebooted , th e fix cod e is reload ed en su rin g th at it will h ave th e bu g fix in stalled an ytim e th e p rocessor is op eratin g. Th e easiest m eth od for ch eckin g th e m icrocod e u p d ate is to u se th e Pen tiu m Pro an d Pen tiu m II Processor Up d ate Utility, wh ich is d evelop ed an d su p p lied by In tel. Th is u tility can verify wh eth er th e correct u p d ate is p resen t for all Pen tiu m Pro p rocessor-based m oth erboard s. Th e u tility d isp lays th e p rocessor step p in g an d version of th e m icrocod e u p d ate. To in stall a n ew m icrocod e u p d ate, h owever, th e m oth erboard BIOS m u st con tain th e rou tin es to su p p ort th e m icrocod e u p d ate, wh ich virtu ally all Pen tiu m Pro an d Pen tiu m II BIOSs d o h ave. Th e In tel Processor Up d ate Utility d eterm in es wh eth er th e cod e is p resen t in th e BIOS, com p ares th e p rocessor step p in g with th e m icrocod e u p d ate cu rren tly load ed , an d in stalls th e n ew u p d ate, if n eed ed . Use of th is u tility with m oth erboard s con tain in g th e BIOS m icrocod e u p d ate rou tin e allows ju st th e m icrocod e u p d ate d ata to be ch an ged ; th e rest of th e BIOS is u n ch an ged . A version of th e u p d ate u tility is p rovid ed with all In tel boxed p rocessors. Th e term boxed processors refers to p rocessors p ackaged for u se by system in tegrators, th at is, p eop le wh o bu ild system s. If you wan t th e m ost cu rren t version of th is u tility, you h ave to con tact an In tel p rocessor d ealer to d own load it. In tel on ly su p p lies it to th eir d ealers. Note th at if th e BIOS in you r m oth erboard d oes n ot in clu d e th e p rocessor m icrocod e u p d ate rou tin e, you sh ou ld get a com p lete system BIOS u p grad e from th e m oth erboard ven d or. W h en you are bu ild in g a system with a Pen tiu m Pro or Pen tiu m II p rocessor, you m u st u se th e Processor Up d ate Utility to ch eck th at th e System BIOS con tain s m icrocod e u p d ates th at are sp ecific to p articu lar silicon step p in g of th e p rocessor you are in stallin g. In oth er word s, you m u st en su re th at th e u p d ate m atch es th e p rocessor step p in g bein g u sed . Table 3.13 con tain s th e cu rren t m icrocod e u p d ate revision for each p rocessor step p in g. Th ese u p d ate revision s are con tain ed in th e m icrocod e u p d ate d atabase file th at com es

Processor Specifications

with th e Pen tiu m Pro p rocessor an d Pen tiu m II p rocessor u p d ate u tility. Processor step p in gs are listed in th e section s on th e Pen tiu m , Pen tiu m Pro, an d Pen tiu m II p rocessors later in th is ch ap ter. Table 3.13 Processor St eppings ( Revisions) and M icrocode Updat e Revisions Support ed by t he Updat e Dat abase File PEP6.PDB St epping Signat ure

M icrocode Updat e Revision Required

Processor

St epping

Pentium Pro Processor

C0

0x612

0xC6

Pentium Pro Processor

sA0

0x616

0xC6

Pentium Pro Processor

sA1

0x617

0xC6

Pentium Pro Processor

sB1

0x619

0xD1

Pentium II Processor

C0

0x633

0x32

Pentium II Processor

C1

0x634

0x33

Pentium II Processor

dA0

0x650

0x15

Usin g th e p rocessor u p d ate u tility (CHECKUP3.EXE), a system bu ild er can easily verify th at th e correct m icrocod e u p d ate is p resen t in all system s based on th e Pen tiu m Pro an d Pen tiu m II p rocessors. For exam p le, if a system con tain s a p rocessor with step p in g C1 an d step p in g sign atu re 0x634, th e BIOS sh ou ld con tain th e m icrocod e u p d ate revision 0x33. Th e p rocessor u p d ate u tility id en tifies th e p rocessor step p in g, sign atu re, an d m icrocod e u p d ate revision th at is cu rren tly in u se. If a n ew m icrocod e u p d ate n eed s to be in stalled in th e system BIOS, th e system BIOS m u st con tain th e In tel-d efin ed p rocessor u p d ate rou tin es so th e p rocessor u p d ate u tility can p erm an en tly in stall th e latest u p d ate. Oth erwise, a com p lete system BIOS u p grad e is req u ired from th e m oth erboard m an u factu rer. It is recom m en d ed th at th e Processor Up d ate Utility be ru n after u p grad in g a m oth erboard BIOS an d before in stallin g th e op eratin g system wh en bu ild in g a system based on th e Pen tiu m Pro p rocessor or Pen tiu m II p rocessor. Th e u tility is easy to u se an d execu tes in ju st a few secon d s. Becau se th e u p d ate u tility m ay n eed to load n ew cod e in to you r BIOS, en su re th at an y ju m p er settin gs on th e m oth erboard are p laced in th e “en able flash u p grad e” p osition . Th is en ables writin g to th e flash m em ory. After ru n n in g th e u tility, tu rn off p ower to th e system an d reboot—d o n ot warm boot— to en su re th at th e n ew u p d ate is correctly in itialized in th e p rocessor. Also en su re th at all ju m p ers, su ch as an y flash u p grad e ju m p ers an d so on , are retu rn ed to th eir n orm al p osition . Int el Processor Codenam es In tel h as always u sed cod en am es wh en talkin g abou t fu tu re p rocessors. Th e cod en am es are n orm ally n ot su p p osed to becom e p u blic, bu t often th ey d o. Th ey can be often fou n d in m agazin e articles talkin g abou t fu tu re gen eration p rocessors. Som etim es, th ey even ap p ear in m oth erboard m an u als becau se th e m an u als are written before th e p rocessors are officially in trod u ced . Table 3.14 lists In tel p rocessor cod en am es for referen ce.

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Table 3.14

Int el Processors and Codenam es

Codenam e

Processor

P4

486DX

P4S

486SX

P23

486SX

P23S

487SX

P23N

487SX

P23T

486 OverDrive for the 80486 (169-pin PGA)

P4T

486 OverDrive for the 486 (168-pin PGA)

P24

486DX2

P24S

486DX2

P24D

486DX2WB (Write Back)

P24C

486DX4

P24CT

486DX4WB (Write Back)

P5

Pentium 60 or 66M Hz, Socket 4, 5v

P24T

486 Pentium OverDrive, 63 or 83M Hz, Socket 3

P54C

Classic Pentium 75-200M Hz, Socket 5/ 7, 3.3v

P55C

Pentium M M X 166-266M Hz, Socket 7, 2.8v

P54CTB

Pentium M M X OverDrive 125+, Socket 5/ 7, 3.3v

Tillamook

M obile Pentium M M X 0.25 micron, 166-266M Hz, 1.8v

P6

Pentium Pro, Socket 8

Klamath

Pentium II, slot 1

Deschutes

Pentium II, 0.25 micron, slot 1 or 2

Covington

Pentium II, low-end Deschutes, no L2 cache

M endocino

Pentium II, low-end Deschutes, 300 M Hz, 128K L2 cache

Katmai

Pentium II, M M X2

Willamette

Pentium II, improved Katmai

M erced

P7, First IA-64 processor

Int el-Com pat ible Processors Several com p an ies—m ain ly AMD an d Cyrix—h ave d evelop ed p rocessors th at are com p atible with In tel p rocessors. Th ese ch ip s are fu lly In tel-com p atible, wh ich m ean s th at th ey em u late every p rocessor in stru ction in th e In tel ch ip s. Most of th e ch ip s are p in com p atible, wh ich m ean s th at th ey can be u sed in an y system d esign ed to accep t an In tel p rocessor; oth ers req u ire a cu stom m oth erboard d esign . An y h ard ware or software th at works on In tel-based PCs will work on PCs m ad e with th ese th ird -p arty CPU ch ip s. A n u m ber of com p an ies cu rren tly offer In tel-com p atible ch ip s, an d I will d iscu ss som e of th e m ost p op u lar on es h ere. AM D Processors Ad van ced Micro Devices (AMD) h as becom e a m ajor p layer in th e Pen tiu m -com p atible ch ip m arket with th eir own lin e of In tel-com p atible p rocessors. AMD ran in to trou ble with In tel several years ago becau se th eir 486-clon e ch ip s u sed actu al In tel m icrocod e.

Intel-Compatible Processors

Th ese d ifferen ces h ave been settled an d AMD n ow h as a five-year cross-licen se agreem en t with In tel. In 1996, AMD fin alized a d eal to absorb NexGen , an oth er m aker of In telcom p atible CPUs. AMD cu rren tly offers a wid e variety of CPUs, from 486 u p grad es to th e MMX-cap able K6. Th e followin g table lists th e basic p rocessors offered by AMD an d th eir In tel socket. CPU

Clock Speed

Socket

Am486DX4-100

100

Socket 1,2,3

Am486DX4-120

120

Socket 1,2,3

Am5x86

133

Socket 1,2,3

K5 PR75

75

Socket 5,7

K5 PR90

90

Socket 5,7

K5 PR100

100

Socket 5,7

K5 PR120

90

Socket 5,7

K5 PR133

100

Socket 5,7

K5 PR166

116.66

Socket 5,7

K6-166 M M X

166

Socket 7

K6-200 M M X

200

Socket 7

K6-233 M M X

233

Socket 7

K6-266 M M X

266

Socket 7

K6-300 M M X

300

Socket 7

Notice in th e table th at for th e K5 PR120 th rou gh PR166 th e m od el d esign ation d oes n ot m atch th e CPU clock sp eed . Th is is called a PR ratin g in stead an d is fu rth er d escribed later in th e ch ap ter. Th e later K5 ch ip s ben efit from im p roved d esign , so th ey ru n faster at a given clock sp eed . Th e m od el d esign ation s are m ean t to rep resen t p erform an ce com p arable with an eq u ivalen t Pen tiu m -based system . AMD ch ip s, p articu larly th e n ew K6, h ave typ ically fared well in p erform an ce com p arison s, an d u su ally h ave a m u ch lower cost. Th ere is m ore in form ation on th e resp ective AMD ch ip s in th e section s for each d ifferen t typ e of p rocessor. Cyrix Cyrix h as becom e an even larger p layer in th e m arket sin ce bein g p u rch ased by Nation al Sem icon d u ctor in Novem ber of 1997. Prior to th at, th ey h ad been a fabless com p an y, m ean in g th ey h ave n o ch ip -m an u factu rin g cap ability. All th e Cyrix ch ip s are m an u factu red for th em by IBM. Cu rren tly, IBM still m an u factu res th e bu lk of Cyrix p rocessors; h owever, Nation al Sem icon d u ctor will likely be assu m in g som e, if n ot all, th is p rod u ction even tu ally. Like In tel, Cyrix h as begu n to lim it its selection of available CPUs to on ly th e latest tech n ology. Cyrix is cu rren tly focu sin g on th e Pen tiu m m arket with th e M1 (6x86) an d M2 (6x86MX) p rocessors. Th e 6x86 h as d u al in tern al p ip elin es an d a sin gle, u n ified 16K in tern al cach e. It offers sp ecu lative an d ou t-of-ord er in stru ction execu tion , m u ch like th e In tel Pen tiu m Pro p rocessor. Th e 6x86MX ad d s MMX tech n ology to th e CPU. Th e ch ip is Socket 7 com p atible, bu t som e req u ire m od ified ch ip sets an d n ew m oth erboard d esign s. Table 3.15 lists Cyrix M1 p rocessors an d bu s sp eed s.

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Table 3.15

Cyrix Processor Rat ings Versus Act ual Speeds

CPU Type/ Speed

Clock Speed

CPU Clock

M ot herboard Speed

6x86-PR120

100

2x

50

6x86-PR133

110

2x

55*

6x86-PR150

120

2x

60

6x86-PR166

133

2x

66

6x86-PR200

150

2x

75**

6x86M X-PR166

150

2.5x

60

6x86M X-PR200

166

2.5x

66

6x86M X-PR233

188

2.5x

75**

*Not all m otherboards support a 55MHz bus speed. **This 75MHz bus speed requires a special m otherboard and chipset.

Th e 6x86MX featu res 64K of u n ified L1 cach e an d m ore th an d ou ble th e p erform an ce of th e p reviou s 6x86 CPUs. Th e 6x86MX is offered in clock sp eed s ran gin g from 180 to 225MHz, an d like th e 6x86, it is Socket 7-com p atible. All Cyrix ch ip s are m an u factu red by IBM, wh o also m arkets th e clon e ch ip s u n d er its own n am e. Note th at later version s of th e 6x86MX ch ip h ave been ren am ed th e MII to d eliberately in voke com p arison s with th e Pen tiu m II, in stead of th e regu lar Pen tiu m p rocessor. Th e MII ch ip s are n ot red esign ed ; th ey are, in fact, th e sam e 6x86MX ch ip s as before, on ly ru n n in g at h igh er clock rates. Th e first ren am ed 6x86MX ch ip is th e MII 300, wh ich actu ally ru n s at on ly 233MHz on a 66MHz Socket 7 m oth erboard . Th ere is also an MII 333, wh ich will ru n at a 250MHz clock sp eed on n ewer 100MHz Socket 7 m oth er-board s. Cyrix also h as m ad e an attem p t at cap tu rin g even m ore of th e low-en d m arket th an th ey alread y h ave by in trod u cin g a p rocessor called th e Med iaGX. Th is is a low-p erform an ce cross between a 486 an d a Pen tiu m com bin ed with a cu stom m oth erboard ch ip set in a two-ch ip p ackage. Th ese two ch ip s con tain everyth in g n ecessary for a m oth erboard excep t th e Su p er I/ O ch ip , an d m ake very low-cost PCs p ossible. Exp ect to see th e Med iaGX p rocessors on th e lowest-en d , virtu ally d isp osable-typ e PCs. Later version s of th ese ch ip s will in clu d e m ore m u ltim ed ia an d even n etwork su p p ort. IDT W inchip An oth er recen t offerin g in th e ch ip m arket is from In tegrated Device Tech n ology (IDT). A lon gtim e ch ip m an u factu rer wh o was m ore well-kn own for m akin g SRAM (cach e m em ory) ch ip s, IDT acq u ired Cen tau r Tech n ology, wh o h ad d esign ed a ch ip called th e C6 W in ch ip . Now with IDT’s m an u factu rin g cap ability, th e C6 p rocessor becam e a reality. Featu rin g a very sim p le d esign , th e C6 W in ch ip is m ore like a 486 th an a Pen tiu m . It d oes n ot h ave th e su p erscalar (m u ltip le in stru ction p ip elin es) of a Pen tiu m , op tin g for a sin gle h igh -sp eed p ip elin e, in stead . In tern ally, it seem s th e C6 h as little in com m on with oth er fifth - an d sixth -gen eration x86 p rocessors. Even so, accord in g to Cen tau r, it closely m atch es th e p erform an ce of a Pen tiu m MMX wh en ru n n in g th e W in ston e 97 bu sin ess ben ch m ark, alth ou gh th at ben ch m ark d oes n ot focu s on m u ltim ed ia p erform an ce. It

Processor Types

also h as a m u ch sm aller d ie (88 m m 2) th an a typ ical Pen tiu m , wh ich m ean s it sh ou ld cost sign ifican tly less to m an u factu re. Th e C6 h as two large in tern al cach es (32K each for in stru ction s an d d ata), an d will ru n at 180, 200, 225, an d 240MHz. Th e p ower con su m p tion is very low—14W m axim u m at 200MHz for th e d esktop ch ip , an d 7.1 to 10.6W for th e m obile ch ip s. Th is p rocessor will likely h ave som e su ccess in th e low-en d m arket. P-Rat ings To m ake it easier to u n d erstan d p rocessor p erform an ce, th e P-ratin g system was join tly d evelop ed by Cyrix, IBM Microelectron ics, SGS-Th om son Microelectron ics, an d Ad van ced Micro Devices. Th is n ew ratin g, titled th e P (Perform an ce) ratin g, eq u ates d elivered p erform an ce of m icrop rocessor to th at of an In tel Pen tiu m . To d eterm in e a sp ecific P-ratin g, Cyrix an d AMD u se ben ch m arks su ch as W in ston e 9x. W in ston e 9x is a wid ely u sed , in d u stry-stan d ard ben ch m ark th at ru n s a n u m ber of W in d ows-based software ap p lication s. Th e id ea is fin e, bu t in som e cases it can be m islead in g. A sin gle or even a grou p of ben ch m arks can n ot tell th e wh ole story on system or p rocessor p erform an ce. In m ost cases, th e com p an ies sellin g PR-rated p rocessors h ave p eop le believin g th at th ey are really ru n n in g at th e sp eed in d icated on th e ch ip . For exam p le, a Cyrix/ IBM 6x86MXPR200 d oes n ot really ru n at 200MHz; in stead , it ru n s at 166MHz. I gu ess th e id ea is th at it “feels” like 200MHz, or com p ares to som e In tel p rocessor ru n n in g at 200MHz (wh ich on e?). I am n ot in favor of th e P- or PR-ratin g system an d p refer to ju st rep ort th e p rocessor’s tru e sp eed in MHz. If it h ap p en s to be 166 bu t ru n s faster th an m ost oth er 166 p rocessors, so be it—bu t I d on ’t like to n u m ber it based on som e com p arison like th at. Th e Ziff-Davis W in ston e ben ch m ark is u sed becau se it is a real-world , ap p lication -based ben ch m ark th at con tain s th e m ost p op u lar software ap p lication s (based on m arket sh are) th at ru n on a Pen tiu m p rocessor. W in ston e also is a wid ely u sed ben ch m ark, an d is freely d istribu ted an d available.

Processor Types Kn owin g th e p rocessors u sed in a system can be very h elp fu l in u n d erstan d in g th e cap abilities of th e system , an d in servicin g it. To fu lly u n d erstan d th e cap abilities of a system an d p erform an y typ e of servicin g, you m u st kn ow at least th e typ e of p rocessor th at th e system u ses. P1 ( 086) First -Generat ion Processors 8088 and 8086 Processors. In tel in trod u ced a revolu tion ary n ew p rocessor called th e 8086 back in Ju n e of 1978. Th e 8086 was on e of th e first 16-bit p rocessor ch ip s on th e m arket; at th e tim e virtu ally all oth er p rocessors were 8-bit d esign s. Th e 8086 h ad 16-bit in tern al registers an d cou ld ru n a n ew class of software u sin g 16-bit in stru ction s. It also h ad a 16-bit extern al d ata p ath , wh ich m ean t it cou ld tran sfer d ata to m em ory 16 bits at a tim e.

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Th e ad d ress bu s was 20 bits wid e, wh ich m ean t th at th e 8086 cou ld ad d ress a fu ll 1M (2 to th e 20th p ower) of m em ory. Th is was in stark con trast to m ost oth er ch ip s of th at tim e th at h ad 8-bit in tern al registers, an 8-bit extern al d ata bu s, an d a 16-bit ad d ress bu s allowin g a m axim u m of on ly 64K of RAM (2 to th e 16th p ower). Un fortu n ately, m ost of th e p erson al com p u ter world at th e tim e was u sin g 8-bit p rocessors, wh ich ran 8-bit CP/ M (Con trol Program for Microp rocessors) op eratin g system s an d software. Th e board an d circu it d esign s at th e tim e were largely 8-bit as well. Bu ild in g a fu ll 16-bit m oth erboard an d m em ory system wou ld be costly, p ricin g su ch a com p u ter ou t of th e m arket. Th e cost was h igh becau se th e 8086 n eed ed a 16-bit d ata bu s rath er th an a less exp en sive 8-bit bu s. System s available at th at tim e were 8-bit, an d slow sales of th e 8086 in d icated to In tel th at p eop le weren ’t willin g to p ay for th e extra p erform an ce of th e fu ll 16-bit d esign . In resp on se, In tel in trod u ced a kin d of crip p led version of th e 8086, called th e 8088. Th e 8088 essen tially d eleted 8 of th e 16 bits on th e d ata bu s, m akin g th e 8088 an 8-bit ch ip as far as d ata in p u t an d ou tp u t were con cern ed . However, becau se it retain ed th e fu ll 16-bit in tern al registers an d th e 20-bit ad d ress bu s, th e 8088 ran 16-bit software an d was able to ad d ress a fu ll 1M of RAM. For th ese reason s, IBM selected th e 8-bit 8088 ch ip for th e origin al IBM PC. Years later, th ey were criticized for u sin g th e 8-bit 8088 in stead of th e 16-bit 8086. In retrosp ect, it was a very wise d ecision . IBM even covered u p th e p h ysical d esign in th eir ad s, wh ich at th e tim e in d icated th eir n ew PC h ad a “h igh -sp eed 16-bit m icrop rocessor.” Th ey cou ld say th at becau se th e 8088 still ran th e sam e p owerfu l 16-bit software th e 8086 ran , ju st a little m ore slowly. In fact, p rogram m ers u n iversally th ou gh t of th e 8088 as a 16-bit ch ip becau se th ere was virtu ally n o way a p rogram cou ld d istin gu ish an 8088 from an 8086. Th is allowed IBM to d eliver a PC cap able of ru n n in g a n ew gen eration of 16-bit software, wh ile retain in g a m u ch less exp en sive 8-bit d esign for th e h ard ware. Becau se of th is, th e IBM PC was actu ally p riced less at its in trod u ction th an th e m ost p op u lar PC of th e tim e, th e Ap p le II. For th e trivia bu ffs ou t th ere, th e IBM PC listed for $1,265 an d in clu d ed on ly 16K of RAM, wh ile a sim ilarly con figu red Ap p le II cost $1,355. Th e origin al IBM PC u sed th e In tel 8088. Th e 8088 was in trod u ced in Ju n e of 1979 bu t th e IBM PC d id n ot ap p ear u n til Au gu st of 1981. Back th en , th ere was often a sign ifican t lag tim e between th e in trod u ction of a n ew p rocessor an d system s wh ich in corp orated it. Th at is u n like tod ay, wh en n ew p rocessors an d system s u sin g th em are often released on th e sam e d ay. Th e 8088 in th e IBM PC ran at 4.77MHz, or 4,770,000 cycles (essen tially com p u ter h eartbeats) p er secon d . Each cycle rep resen ts a u n it of tim e to th e system , with d ifferen t in stru ction s or op eration s req u irin g on e or m ore cycles to com p lete. Th e average in stru ction on th e 8088 took 12 cycles to com p lete. Com p u ter u sers som etim es won d er wh y a 640K con ven tion al-m em ory barrier exists if th e 8088 ch ip can ad d ress 1M of m em ory. Th e con ven tion al-m em ory barrier exists becau se IBM reserved 384K of th e u p p er p ortion of th e 1,024K (1M) ad d ress sp ace of th e 8088 for u se by ad ap ter card s an d system BIOS. Th e lower 640K is th e con ven tion al m em ory in wh ich DOS an d software ap p lication s execu te.

Processor Types

80186 and 80188 Processors. After In tel p rod u ced th e 8086 an d 8088 ch ip s, it tu rn ed its sigh ts toward p rod u cin g a m ore p owerfu l ch ip with an in creased in stru ction set. Th e com p an y’s first efforts alon g th is lin e—th e 80186 an d 80188—were u n su ccessfu l. Bu t in corp oratin g system com p on en ts in to th e CPU ch ip was an im p ortan t id ea for In tel becau se it led to faster, better ch ip s, su ch as th e 286. Th e relation sh ip between th e 80186 an d 80188 is th e sam e as th at of th e 8086 an d 8088; on e is a sligh tly m ore ad van ced version of th e oth er. Com p ared CPU to CPU, th e 80186 is alm ost th e sam e as th e 8088 an d h as a fu ll 16-bit d esign . Th e 80188 (like th e 8088) is a h ybrid ch ip th at com p rom ises th e 16-bit d esign with an 8-bit extern al com m u n ication s in terface. Th e ad van tage of th e 80186 an d 80188 is th at th ey com bin e on a sin gle ch ip 15 to 20 of th e 8086–8088 series system com p on en ts, a fact th at can greatly red u ce th e n u m ber of com p on en ts in a com p u ter d esign . Th e 80186 an d 80188 ch ip s were u sed for h igh ly in telligen t p erip h eral ad ap ter card s of th at age, su ch as n etwork ad ap ters. 8087 Coprocessor. In tel in trod u ced th e 8086 p rocessor in 1976. Th e m ath cop rocessor th at was p aired with th e ch ip —th e 8087—often was called th e n u m eric d ata p rocessor (NDP), th e m ath cop rocessor, or sim p ly th e m ath ch ip . Th e 8087 is d esign ed to p erform h igh -level m ath op eration s at m an y tim es th e sp eed of th e m ain p rocessor. Th e p rim ary ad van tage of u sin g th is ch ip is th e in creased execu tion sp eed in n u m ber-cru n ch in g p rogram s, su ch as sp read sh eet ap p lication s. P2 ( 286) Second-Generat ion Processors 286 Processors. Th e In tel 80286 (n orm ally abbreviated as 286) p rocessor d id n ot su ffer from th e com p atibility p roblem s th at d am n ed th e 80186 an d 80188. Th e 286 ch ip , first in trod u ced in 1981, is th e CPU beh in d th e origin al IBM AT. Oth er com p u ter m akers m an u factu red wh at cam e to be kn own as IBM clon es, m an y of th ese m an u factu rers callin g th eir system s AT-com p atible or AT-class com p u ters. W h en IBM d evelop ed th e AT, it selected th e 286 as th e basis for th e n ew system becau se th e ch ip p rovid ed com p atibility with th e 8088 u sed in th e PC an d th e XT. Th at m ean s th at software written for th ose ch ip s sh ou ld ru n on th e 286. Th e 286 ch ip is m an y tim es faster th an th e 8088 u sed in th e XT, an d it offered a m ajor p erform an ce boost to PCs u sed in bu sin esses. Th e p rocessin g sp eed , or th rou gh p u t, of th e origin al AT (wh ich ran at 6MHz) was five tim es greater th an th at of th e PC ru n n in g at 4.77MHz. Th e d ie for th e 286 is sh own in Figu re 3.17. 286 system s are faster th an th eir p red ecessors for several reason s. Th e m ain reason is th at 286 p rocessors are m u ch m ore efficien t in execu tin g in stru ction s. An average in stru ction takes 12 clock cycles on th e 8086 or 8088, bu t an average 4.5 cycles on th e 286 p rocessor. Ad d ition ally, th e 286 ch ip can h an d le u p to 16 bits of d ata at a tim e th rou gh an extern al d ata bu s twice th e size of th e 8088. Th e 286 ch ip h as two m od es of op eration : real m od e an d p rotected m od e. Th e two m od es are d istin ct en ou gh to m ake th e 286 resem ble two ch ip s in on e. In real m od e, a 286 acts essen tially th e sam e as an 8086 ch ip an d is fu lly object-cod e com p atible with th e 8086 an d 8088. (A p rocessor with object-cod e com p atibility can ru n p rogram s written for an oth er p rocessor with ou t m od ification an d execu te every system in stru ction in th e sam e m an n er.)

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FIG. 3.17 286 Processor d ie. Photograph used by perm ission of Intel Corporation. In th e p rotected m od e of op eration , th e 286 was tru ly som eth in g n ew. In th is m od e, a p rogram d esign ed to take ad van tage of th e ch ip ’s cap abilities believes th at it h as access to 1G of m em ory (in clu d in g virtu al m em ory). Th e 286 ch ip , h owever, can ad d ress on ly 16M of h ard ware m em ory. A sign ifican t failin g of th e 286 ch ip is th at it can n ot switch from p rotected m od e to real m od e with ou t a h ard ware reset (a warm reboot) of th e system . (It can , h owever, switch from real m od e to p rotected m od e with ou t a reset.) A m ajor im p rovem en t of th e 386 over th e 286 is th at software can switch th e 386 from real m od e to p rotected m od e, an d vice versa. See th e Processor Mod es section earlier in th is ch ap ter for m ore in form ation . On ly a sm all am ou n t of software th at took ad van tage of th e 286 ch ip was sold u n til W in d ows 3.0 offered Stan d ard Mod e for 286 com p atibility; by th at tim e, th e h ottestsellin g ch ip was th e 386. Still, th e 286 was In tel’s first attem p t to p rod u ce a CPU ch ip th at su p p orted m u ltitaskin g, in wh ich m u ltip le p rogram s ru n at th e sam e tim e. Th e 286 was d esign ed so th at if on e p rogram locked u p or failed , th e en tire system d id n ’t n eed a warm boot (reset) or cold boot (p ower off or on ). Th eoretically, wh at h ap p en ed in on e area of m em ory d id n ’t affect oth er p rogram s. Before m u ltitasked p rogram s cou ld be “safe” from on e an oth er, h owever, th e 286 ch ip (an d su bseq u en t ch ip s) n eed ed an op eratin g system th at works coop eratively with th e ch ip to p rovid e su ch p rotection . 80287 Coprocessor. Th e 80287, in tern ally, is th e sam e m ath ch ip as th e 8087, alth ou gh th e p in s u sed to p lu g th em in to th e m oth erboard are d ifferen t. Both th e 80287 an d th e 8087 op erate as th ou gh th ey were id en tical. In m ost system s, th e 80286 in tern ally d ivid es th e system clock by two to d erive th e p rocessor clock. Th e 80287 in tern ally d ivid es th e system -clock freq u en cy by th ree. For th is

Processor Types

reason , m ost AT-typ e com p u ters ru n th e 80287 at on e th ird th e system clock rate, wh ich also is two th ird s th e clock sp eed of th e 80286. Becau se th e 286 an d 287 ch ip s are asyn ch ron ou s, th e in terface between th e 286 an d 287 ch ip s is n ot as efficien t as with th e 8088 an d 8087. In su m m ary, th e 80287 an d th e 8087 ch ip s p erform abou t th e sam e at eq u al clock rates. Th e origin al 80287 is n ot better th an th e 8087 in an y real way—u n like th e 80286, wh ich is su p erior to th e 8086 an d 8088. In m ost AT system s, th e p erform an ce gain th at you realize by ad d in g th e cop rocessor is m u ch less su bstan tial th an th e sam e typ e of u p grad e for PC- or XT-typ e system s, or for th e 80386. 286 Processor Problem s. After you rem ove a m ath cop rocessor from an AT-typ e system , you m u st reru n you r com p u ter’s Setu p p rogram . Som e AT-com p atible SETUP p rogram s d o n ot p rop erly u n set th e m ath -cop rocessor bit. If you receive a POST error m essage becau se th e com p u ter can n ot fin d th e m ath ch ip , you m ay h ave to u n p lu g th e battery from th e system board tem p orarily. All SETUP in form ation will be lost, so be su re to write d own th e h ard d rive typ e, flop p y d rive typ e, an d m em ory an d vid eo con figu ration s before u n p lu ggin g th e battery. Th is in form ation is critical in recon figu rin g you r com p u ter correctly. P3 ( 386) Third-Generat ion Processors 386 Processors. Th e In tel 80386 (n orm ally abbreviated as 386) cau sed q u ite a stir in th e PC in d u stry becau se of th e vastly im p roved p erform an ce it brou gh t to th e p erson al com p u ter. Com p ared with 8088 an d 286 system s, th e 386 ch ip offered greater p erform an ce in alm ost all areas of op eration . Th e 386 is a fu ll 32-bit p rocessor op tim ized for h igh -sp eed op eration an d m u ltitaskin g op eratin g system s. In tel in trod u ced th e ch ip in 1985, bu t th e 386 ap p eared in th e first system s in late 1986 an d early 1987. Th e Com p aq Deskp ro 386 an d system s m ad e by several oth er m an u factu rers in trod u ced th e ch ip ; som ewh at later, IBM u sed th e ch ip in its PS/ 2 Mod el 80. Th e 386 ch ip rose in p op u larity for several years, wh ich p eaked arou n d 1991. Obsolete 386 p rocessor system s are m ostly retired or scrap p ed , h avin g been p assed d own th e u ser ch ain . If th ey are in op eratin g con d ition , th ey can be u sefu l for ru n n in g old DOS or W in d ows 3.x-based ap p lication s, wh ich th ey can d o q u ite n icely. Th e 386 can execu te th e real-m od e in stru ction s of an 8086 or 8088, bu t in fewer clock cycles. Th e 386 was as efficien t as th e 286 in execu tin g in stru ction s, wh ich m ean s th at th e average in stru ction took abou t 4.5 clock cycles. In raw p erform an ce, th erefore, th e 286 an d 386 actu ally seem ed to be at alm ost eq u al clock rates. Man y 286 system m an u factu rers were tou tin g th eir 16MHz an d 20MHz 286 system s as bein g ju st as fast as 16MHz an d 20MHz 386 system s, an d th ey were righ t! Th e 386 offered greater p erform an ce in oth er ways, m ain ly d u e to ad d ition al software cap ability (m od es) an d a greatly en h an ced Mem ory Man agem en t Un it (MMU). Th e d ie for th e 386 is sh own in Figu re 3.18. Th e 386 can switch to an d from p rotected m od e u n d er software con trol with ou t a system reset, a cap ability th at m akes u sin g p rotected m od e m ore p ractical. In ad d ition , th e 386 h as a n ew m od e, called virtu al real m od e, wh ich en ables several real-m od e session s to ru n sim u ltan eou sly u n d er p rotected m od e.

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Th e p rotected m od e of th e 386 is fu lly com p atible with th e p rotected m od e of th e 286. Th e p rotected m od e for both ch ip s often is called th eir native m ode of operation, becau se th ese ch ip s are d esign ed for ad van ced op eratin g system s su ch as OS/ 2 an d W in d ows NT, wh ich ru n on ly in p rotected m od e. In tel exten d ed th e m em ory-ad d ressin g cap abilities of 386 p rotected m od e with a n ew MMU th at p rovid ed ad van ced m em ory p agin g an d p rogram switch in g. Th ese featu res were exten sion s of th e 286 typ e of MMU, so th e 386 rem ain ed fu lly com p atible with th e 286 at th e system -cod e level. Th e 386 ch ip ’s virtu al real m od e was n ew. In virtu al real m od e, th e p rocessor cou ld ru n with h ard ware m em ory p rotection wh ile sim u latin g an 8086’s real-m od e op eration . Mu ltip le cop ies of DOS an d oth er op eratin g system s, th erefore, cou ld ru n sim u ltan eou sly on th is p rocessor, each in a p rotected area of m em ory. If th e p rogram s in on e segm en t crash ed , th e rest of th e system was p rotected . Software com m an d s cou ld reboot th e blown p artition . Nu m erou s variation s of th e 386 ch ip exist, som e of wh ich are less p owerfu l an d som e of wh ich are less p ower-h u n gry. Th e followin g section s cover th e m em bers of th e 386-ch ip fam ily an d th eir d ifferen ces.

FIG. 3.18 386 Processor d ie. Photograph used by perm ission of Intel Corporation. 386DX Processors. Th e 386DX ch ip was th e first of th e 386-fam ily m em bers th at In tel in trod u ced . Th e 386 is a fu ll 32-bit p rocessor with 32-bit in tern al registers, a 32-bit in tern al d ata bu s, an d a 32-bit extern al d ata bu s. Th e 386 con tain s 275,000 tran sistors in a

Processor Types

VLSI (Very Large Scale In tegration ) circu it. Th e ch ip com es in a 132-p in p ackage an d d raws ap p roxim ately 400 m illiam p eres (m a), wh ich is less p ower th an even th e 8086 req u ires. Th e 386 h as a sm aller p ower req u irem en t becau se it is m ad e of CMOS (Com p lem en tary Metal Oxid e Sem icon d u ctor) m aterials. Th e CMOS d esign en ables d evices to con su m e extrem ely low levels of p ower. Th e In tel 386 ch ip was available in clock sp eed s ran gin g from 16MHz to 33MHz; oth er m an u factu rers, p rim arily AMD an d Cyrix, offered com p arable version s with sp eed s u p to 40MHz. Th e 386DX can ad d ress 4G of p h ysical m em ory. Its bu ilt-in virtu al m em ory m an ager en ables software d esign ed to take ad van tage of en orm ou s am ou n ts of m em ory to act as th ou gh a system h as 64T of m em ory. (A terabyte— T—is 1,099,511,627,776 bytes of m em ory.) 386SX Processors. Th e 386SX was d esign ed for system s d esign ers wh o were lookin g for 386 cap abilities at 286-system p rices. Like th e 286, th e 386SX is restricted to on ly 16 bits wh en com m u n icatin g with oth er system com p on en ts, su ch as m em ory. In tern ally, h owever, th e 386SX is id en tical to th e DX ch ip ; th e 386SX h as 32-bit in tern al registers, an d can th erefore ru n 32-bit software. Th e 386SX u ses a 24-bit m em ory-ad d ressin g sch em e like th at of th e 286, rath er th an th e fu ll 32-bit m em ory ad d ress bu s of th e stan d ard 386. Th e 386SX, th erefore, can ad d ress a m axim u m 16M of p h ysical m em ory rath er th an th e 4G of p h ysical m em ory th at th e 386DX can ad d ress. Before it was d iscon tin u ed , th e 386SX was available in clock sp eed s ran gin g from 16 to 33MHz. Th e 386SX sign aled th e en d of th e 286 becau se of th e 386SX ch ip’s su perior MMU an d th e addition of th e virtu al real m ode. Un der a software m an ager su ch as W in dows or OS/ 2, th e 386SX can ru n n u m erou s DOS program s at th e sam e tim e. Th e capability to ru n 386specific software is an oth er im portan t advan tage of th e 386SX over an y 286 or older design . For exam ple, W in dows 3.1 ru n s n early as well on a 386SX as it does on a 386DX.

Not e One common fallacy about the 386SX is that you can plug one into a 286 system and give the system 386 capabilities. This is not true; the 386SX chip is not pin-compatible with the 286 and does not plug into the same socket. Several upgrade products, however, have been designed to adapt the chip to a 286 system. In terms of raw speed, converting a 286 system to a 386 CPU chip results in little performance gain—286 motherboards are built with a restricted 16-bit interface to memory and peripherals. A 16M Hz 386SX is not markedly faster than a 16M Hz 286, but it does offer improved memory-management capabilities on a motherboard designed for it, and the capability to run 386-specific software.

386SL Processors. Th e 386SL is an oth er variation on th e 386 ch ip. Th is low-power CPU h ad th e sam e capabilities as th e 386SX, bu t it was design ed for laptop system s in wh ich low power con su m ption was n eeded. Th e SL ch ips offer special power-m an agem en t featu res th at were im portan t to system s th at ran on batteries. Th e SL ch ip offered several sleep m odes to con serve power.

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Th e ch ip in clu d ed an exten d ed arch itectu re th at con tain ed a System Managem ent Interrupt (SMI ), wh ich p rovid ed access to th e p ower-m an agem en t featu res. Also in clu d ed in th e SL ch ip was sp ecial su p p ort for LIM (Lotu s In tel Microsoft) exp an d ed m em ory fu n ction s an d a cach e con troller. Th e cach e con troller was d esign ed to con trol a 16–64K extern al p rocessor cach e. Th ese extra fu n ction s accou n t for th e h igh er tran sistor cou n t in th e SL ch ip s (855,000) com p ared with even th e 386DX p rocessor (275,000). Th e 386SL was available in 25MHz clock sp eed . In tel offered a com p an ion to th e 386SL ch ip for lap top s called th e 82360SL I/ O su bsystem . Th e 82360SL p rovid ed m an y com m on p erip h eral fu n ction s, su ch as serial an d p arallel p orts, a d irect m em ory access (DMA) con troller, an in terru p t con troller, an d p ower-m an agem en t logic for th e 386SL p rocessor. Th is ch ip su bsystem worked with th e p rocessor to p rovid e an id eal solu tion for th e sm all size an d low p ower-con su m p tion req u irem en ts of p ortable an d lap top system s. 80387 Coprocessor. Alth ou gh th e 80387 ch ip s ran asyn ch ron ou sly, 386 system s were d esign ed so th at th e m ath ch ip ru n s at th e sam e clock sp eed as th e m ain CPU. Un like th e 80287 cop rocessor, wh ich was m erely an 8087 with d ifferen t p in s to p lu g in to th e AT m oth erboard , th e 80387 cop rocessor was a h igh -p erform an ce m ath ch ip d esign ed sp ecifically to work with th e 386. All 387 ch ip s u sed a low p ower-con su m p tion CMOS d esign . Th e 387 cop rocessor h ad two basic d esign s: th e 387DX cop rocessor, wh ich was d esign ed to work with th e 386DX p rocessor, an d th e 387SX cop rocessor, wh ich was d esign ed to work with th e 386SX, SL, or SLC p rocessors. In tel origin ally offered several sp eed s for th e 387DX cop rocessor. Bu t wh en th e com p an y d esign ed th e 33MHz version , a sm aller m ask was req u ired to red u ce th e len gth s of th e sign al p ath ways in th e ch ip . Th is in creased th e p erform an ce of th e ch ip by rou gh ly 20%.

Not e Because Intel lagged in developing the 387 coprocessor, some early 386 systems were designed with a socket for a 287 coprocessor. Performance levels associated with that union, however, leave much to be desired.

In stallin g a 387DX is easy, bu t you m u st be carefu l to orien t th e ch ip in its socket p rop erly; oth erwise, th e ch ip will be d estroyed . Th e m ost com m on cau se of bu rn ed p in s on th e 387DX is in correct in stallation . In m an y system s, th e 387DX was orien ted d ifferen tly from oth er large ch ip s. Follow th e m an u factu rer’s in stallation in stru ction s carefu lly to avoid d am agin g th e 387DX; In tel’s warran ty d oes n ot cover ch ip s th at are in stalled in correctly. Several m an u factu rers d evelop ed th eir own version s of th e In tel 387 cop rocessors, som e of wh ich were tou ted as bein g faster th an th e origin al In tel ch ip s. Th e gen eral com p atibility record of th ese ch ip s was very good .

Processor Types

W eit ek Coprocessors. In 1981, several In tel en gin eers form ed th e W eitek Corp oration . W eitek d evelop ed m ath cop rocessors for several system s, in clu d in g th ose based on Motorola p rocessor d esign s. In tel origin ally con tracted W eitek to d evelop a m ath cop rocessor for th e In tel 386 CPU, becau se In tel was beh in d in its own d evelop m en t of th e 387 m ath cop rocessor. Th e resu lt was th e W eitek 1167, a cu stom m ath cop rocessor th at u ses a p rop rietary W eitek in stru ction set, wh ich is in com p atible with th e In tel 387. To u se th e W eitek cop rocessor, you r system m u st h ave th e req u ired ad d ition al socket, wh ich was d ifferen t from th e stan d ard In tel cop rocessor sockets. 80386 Bugs. Som e early 16MHz In tel 386DX p rocessors h ad a sm all bu g th at ap p eared as a software p roblem . Th e bu g, wh ich ap p aren tly was in th e ch ip ’s 32-bit m u ltip ly rou tin e, m an ifested itself on ly wh en you ran tru e 32-bit cod e in a p rogram su ch as OS/ 2 2.x, UNIX/ 386, or W in d ows in En h an ced m od e. Som e sp ecialized 386 m em ory-m an agem en t software system s also m ay in voke th is su btle bu g, bu t 16-bit op eratin g system s (su ch as DOS an d OS/ 2 1.x) p robably will n ot. Th e bu g u su ally cau ses th e system to lock u p . Diagn osin g th is p roblem can be d ifficu lt becau se th e p roblem gen erally is in term itten t an d software-related . Ru n n in g tests to fin d th e bu g is d ifficu lt; on ly In tel, with p rop er test eq u ip m en t, can d eterm in e wh eth er you r ch ip h as a bu g. Som e p rogram s can d iagn ose th e p roblem an d id en tify a d efective ch ip , bu t th ey can n ot id en tify all d efective ch ip s. If a p rogram in d icates a bad ch ip , you certain ly h ave a d efective on e; if th e p rogram p asses th e ch ip , you still m ay h ave a d efective on e. In tel req u ested th at its 386 cu stom ers retu rn p ossibly d efective ch ip s for screen in g, bu t m an y ven d ors d id n ot retu rn th em . In tel tested retu rn ed ch ip s an d rep laced d efective on es. Th e d efective ch ip s later were sold to bargain liq u id ators or system s h ou ses th at wan ted ch ip s th at wou ld n ot ru n 32-bit cod e. Th e d efective ch ip s were stam p ed with a 16-bit SW On ly logo, in d icatin g th at th ey were au th orized to ru n on ly 16-bit software. Ch ip s th at p assed th e test, an d all su bseq u en t ch ip s p rod u ced as bu g-free, were m arked with a d ou ble-sigm a cod e (ΣΣ). 386DX ch ip s th at are n ot m arked with eith er of th ese d esign ation s h ave n ot been tested by In tel an d m ay be d efective. Th e followin g m arkin g in d icates th at a ch ip h as n ot yet been screen ed for th e d efect; it m ay be eith er good or bad . 80386-16 Th e followin g m arkin g in d icates th at th e ch ip h as been tested an d h as th e 32-bit m u ltip ly bu g. Th e ch ip works with 16-bit software (su ch as DOS) bu t n ot with 32-bit, 386sp ecific software (su ch as W in d ows or OS/ 2). 80386-16 16-bit SW On ly Th e followin g m ark on a ch ip in d icates th at it h as been tested as d efect-free. Th is ch ip fu lfills all th e cap abilities p rom ised for th e 80386.

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80386-16 ΣΣ Th is p roblem was d iscovered an d corrected before In tel officially ad d ed DX to th e p art n u m ber. So if you h ave a ch ip labeled as 80386DX or 386DX, it d oes n ot h ave th is p roblem . An oth er p roblem with th e 386DX can be stated m ore sp ecifically. W h en 386-based version s of XENIX or oth er UNIX im p lem en tation s are ru n on a com p u ter th at con tain s a 387DX m ath cop rocessor, th e com p u ter locks u p u n d er certain con d ition s. Th e p roblem d oes n ot occu r in th e DOS en viron m en t, h owever. For th e locku p to occu r, all th e followin g con d ition s m u st be in effect: ■ Dem an d p age virtu al m em ory m u st be active. ■ A 387DX m u st be in stalled an d in u se. ■ DMA (d irect m em ory access) m u st occu r. ■ Th e 386 m u st be in a wait state. W h en all th ese con d ition s are tru e at th e sam e in stan t, th e 386DX en d s u p waitin g for th e 387DX, an d vice versa. Both p rocessors will con tin u e to wait for each oth er in d efin itely. Th e p roblem is in certain version s of th e 386DX, n ot in th e 387DX m ath cop rocessor. In tel p u blish ed th is p roblem (Errata 21) im m ed iately after it was d iscovered to in form its OEM cu stom ers. At th at p oin t, it becam e th e resp on sibility of each m an u factu rer to im p lem en t a fix in its h ard ware or software p rod u ct. Som e m an u factu rers, su ch as Com p aq an d IBM, resp on d ed by m od ifyin g th eir m oth erboard s to p reven t th ese locku p s from occu rrin g. Th e Errata 21 p roblem occu rs on ly in th e B Step p in g version of th e 386DX an d n ot in th e later, D Step p in g version . You can id en tify th e D Step p in g version of th e 386DX by th e letters DX in th e p art n u m ber (for exam p le, 386DX-20). If DX is p art of th e ch ip ’s p art n u m ber, th e ch ip d oes n ot h ave th is p roblem . P4 ( 486) Fourt h-Generat ion Processors 486 Processors. In th e race for m ore sp eed , th e In tel 80486 (n orm ally abbreviated as 486) was an oth er m ajor leap forward . Th e ad d ition al p ower available in th e 486 fu eled trem en d ou s growth in th e software in d u stry. Ten s of m illion s of cop ies of W in d ows, an d m illion s of cop ies of OS/ 2, h ave been sold largely becau se th e 486 fin ally m ad e th e GUI of W in d ows an d OS/ 2 a realistic op tion for p eop le wh o work on th eir com p u ters every d ay. Fou r m ain featu res m ake a given 486 p rocessor rou gh ly twice as fast as an eq u ivalen t MHz 386 ch ip . Th ese featu res are ■ Reduced instruction-execution tim e. A sin gle in stru ction in th e 486 takes an average of on ly two clock cycles to com p lete, com p ared with an average of m ore th an fou r

Processor Types

cycles on th e 386. Clock-m u ltip lied version s su ch as th e DX2 an d DX4 fu rth er red u ced th is to abou t two cycles p er in stru ction . ■ Internal (Level 1) cache. Th e bu ilt-in cach e h as a h it ratio of 90–95%, wh ich d escribes h ow often zero-wait-state read op eration s will occu r. Extern al cach es can im p rove th is ratio fu rth er. ■ Burst-m ode m em ory cycles. A stan d ard 32-bit (4-byte) m em ory tran sfer takes two clock cycles. After a stan d ard 32-bit tran sfer, m ore d ata u p to th e n ext 12 bytes (or th ree tran sfers) can be tran sferred with on ly on e cycle u sed for each 32-bit (4-byte) tran sfer. Th u s, u p to 16 bytes of con tigu ou s, seq u en tial m em ory d ata can be tran sferred in as little as five cycles in stead of eigh t cycles or m ore. Th is effect can be even greater wh en th e tran sfers are on ly 8 bits or 16 bits each . ◊◊ See “ Burst EDO,” p. 316

■ Built-in (synchronous) enhanced m ath coprocessor (som e versions). Th e m ath cop rocessor ru n s syn ch ron ou sly with th e m ain p rocessor an d execu tes m ath in stru ction s in fewer cycles th an p reviou s d esign s d id . On average, th e m ath cop rocessor bu ilt in to th e DX-series ch ip s p rovid es two to th ree tim es greater m ath p erform an ce th an an extern al 387 ch ip . Th e 486 ch ip is abou t twice as fast as th e 386, wh ich m ean s th at a 386DX-40 is abou t as fast as a 486SX-20. Th is m ad e th e 486 a m u ch m ore d esirable op tion , p rim arily becau se it cou ld m ore easily be u p grad ed to a DX2 or DX4 p rocessor at a later tim e. You can see wh y th e arrival of th e 486 rap id ly killed off th e 386 in th e m arketp lace. Before th e 486, m an y p eop le avoid ed GUIs becau se th ey d id n ’t h ave tim e to sit arou n d waitin g for th e h ou rglass, wh ich in d icates th at th e system is p erform in g beh in d -th escen es op eration s th at th e u ser can n ot in terru p t. Th e 486 ch an ged th at situ ation . Man y p eop le believe th at th e 486 CPU ch ip sp awn ed th e wid esp read accep tan ce of GUIs. W ith th e release of its faster Pen tiu m CPU ch ip , In tel began to cu t th e p rice of th e 486 lin e to en tice th e in d u stry to sh ift over to th e 486 as th e m ain stream system . In tel later d id th e sam e th in g with its Pen tiu m ch ip s, sp ellin g th e en d of th e 486 lin e. Th e 486 is n ow offered by In tel on ly for u se in em bed d ed m icrop rocessor ap p lication s, u sed p rim arily in exp an sion card s. Most of th e 486 ch ip s were offered in a variety of m axim u m sp eed ratin gs, varyin g from 16MHz all th e way u p to 120MHz. Ad d ition ally, 486 p rocessors h ave sligh t d ifferen ces in overall p in con figu ration s. Th e DX, DX2, an d SX p rocessors h ave a virtu ally id en tical 168-p in con figu ration , wh ereas th e OverDrive ch ip s h ave eith er th e stan d ard 168-p in con figu ration or a sp ecially m od ified 169-p in OverDrive (som etim es also called 487SX) con figu ration . If you r m oth erboard h as two sockets, th e p rim ary on e likely su p p orts th e stan d ard 168-p in con figu ration , an d th e secon d ary (OverDrive) socket su p p orts th e 169p in OverDrive con figu ration . Most n ewer m oth erboard s with a sin gle ZIF socket su p p ort an y of th e 486 p rocessors excep t th e DX4. Th e DX4 is d ifferen t becau se it req u ires 3.3v to op erate in stead of 5v, like m ost oth er ch ip s u p to th at tim e.

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A p rocessor rated for a given sp eed always fu n ction s at an y of th e lower sp eed s. A 100MHz-rated 486DX4 ch ip , for exam p le, ru n s at 75MHz if it is p lu gged in to a 25MHz m oth erboard . Note th at th e DX2/ OverDrive p rocessors op erate in tern ally at two tim es th e m oth erboard clock rate, wh ereas th e DX4 p rocessors op erate at two, two-an d -a-h alf, or th ree tim es th e m oth erboard clock rate. Table 3.16 sh ows th e d ifferen t sp eed com bin ation s th at can resu lt from u sin g th e DX2 or DX4 p rocessors with d ifferen t m oth erboard clock sp eed s. Table 3.16 Int el DX2 and DX4 Operat ing Speeds Versus M ot herboard Clock Speeds DX2 Processor speed

DX4 ( 2×m ode) Speed

DX4 ( 2.5×m ode) Speed

DX4 ( 3×m ode) Speed

16M Hz M otherboard

32M Hz

32M Hz

40M Hz

48M Hz

20M Hz M otherboard

40M Hz

40M Hz

50M Hz

60M Hz

25M Hz M otherboard

50M Hz

50M Hz

63M Hz

75M Hz

33M Hz M otherboard

66M Hz

66M Hz

83M Hz

100M Hz

40M Hz M otherboard

80M Hz

80M Hz

100M Hz

120M Hz

50M Hz M otherboard

N/ A

100M Hz

N/ A

N/ A

Th e in tern al core sp eed of th e DX4 p rocessor is con trolled by th e CLKMUL (Clock Mu ltip lier) sign al at p in R-17 (Socket 1) or S-18 (Socket 2, 3, or 6). Th e CLKMUL in p u t is sam p led on ly d u rin g a reset of th e CPU, an d d efin es th e ratio of th e in tern al clock to th e extern al bu s freq u en cy CLK sign al at p in C-3 (Socket 1) or D-4 (Socket 2, 3, or 6). If CLKMUL is sam p led low, th e in tern al core sp eed will be two tim es th e extern al bu s freq u en cy. If d riven h igh or left floatin g (m ost m oth erboard s wou ld leave it floatin g), trip le sp eed m od e is selected . If th e CLKMUL sign al is con n ected to th e BREQ (Bu s Req u est) ou tp u t sign al at p in Q-15 (Socket 1) or R-16 (Socket 2, 3, or 6), th e CPU in tern al core sp eed will be 2.5 tim es th e CLK sp eed . To su m m arize, h ere is h ow th e socket h as to be wired for each DX4 sp eed selection : CPU Speed

CLKM UL ( Sam pled Only at CPU Reset )

2x

Low

2.5x

Connected to BREQ

3x

High or Floating

You will h ave to d eterm in e h ow you r p articu lar m oth erboard is wired an d wh eth er it can be ch an ged to alter th e CPU core sp eed in relation to th e CLK sign al. In m ost cases, th ere wou ld be on e or two ju m p ers on th e board n ear th e p rocessor socket. Th e m oth erboard d ocu m en tation sh ou ld cover th ese settin gs if th ey can be ch an ged .

Processor Types

On e in terestin g cap ability h ere is to ru n th e DX4-100 ch ip in a d ou bled m od e with a 50MHz m oth erboard sp eed . Th is wou ld give you a very fast m em ory bu s, alon g with th e sam e 100MHz p rocessor sp eed , as if you were ru n n in g th e ch ip in a 33/ 100MHz trip led m od e.

Not e One caveat is that if your motherboard has VL-Bus slots, they will have to be slowed down to 33 or 40M Hz to operate properly.

Man y VL-Bu s m oth erboard s can ru n th e VL-Bu s slots in a bu ffered m od e, ad d wait states, or even selectively ch an ge th e clock on ly for th e VL-Bu s slots to keep th em com p atible. In m ost cases, th ey will n ot ru n p rop erly at 50MHz. Con su lt you r m oth erboard —or even better, you r ch ip set d ocu m en tation —to see h ow you r board is set u p .

Caut ion If you are upgrading an existing system, be sure that your socket will support the chip that you are installing. In particular, if you are putting a DX4 processor in an older system, you need some type of adapter to regulate the voltage down to 3.3v. If you put the DX4 in a 5v socket, you will destroy the chip! See the earlier section on processor sockets for more information.

Th e 486-p rocessor fam ily is d esign ed for greater p erform an ce th an p reviou s p rocessors becau se it in tegrates form erly extern al d evices, su ch as cach e con trollers, cach e m em ory, an d m ath cop rocessors. Also, 486 system s were th e first d esign ed for tru e p rocessor u p grad ability. Most 486 system s can be u p grad ed by sim p le p rocessor ad d ition s or swap s th at can effectively d ou ble th e sp eed of th e system . 4 8 6 D X P ro c e sso rs. Th e origin al In tel 486DX p rocessor was in trod u ced on Ap ril 10, 1989, an d system s u sin g th is ch ip first ap p eared d u rin g 1990. Th e first ch ip s h ad a m axim u m sp eed ratin g of 25MHz; later version s of th e 486DX were available in 33MHz- an d 50MHz-rated version s. Th e 486DX origin ally was available on ly in a 5v, 168-p in PGA version , bu t n ow is also available in 5v, 196-p in PQFP (Plastic Qu ad Flat Pack) an d 3.3v, 208-p in SQFP (Sm all Qu ad Flat Pack). Th ese latter form factors are available in SL En h an ced version s, wh ich are in ten d ed p rim arily for p ortable or lap top ap p lication s in wh ich savin g p ower is im p ortan t. Two m ain featu res sep arate th e 486 p rocessor from old er p rocessors: ■ Th e 486DX in tegrates fu n ction s su ch as th e m ath cop rocessor, cach e con troller, an d cach e m em ory in to th e ch ip . ■ Th e 486 also was d esign ed with u p grad ability in m in d ; d ou ble-sp eed OverDrive are u p grad es available for m ost system s. Th e 486DX p rocessor is fabricated with low-p ower CMOS (Com p lem en tary Metal Oxid e Sem icon d u ctor) tech n ology. Th e ch ip h as a 32-bit in tern al register size, a 32-bit extern al d ata bu s, an d a 32-bit ad d ress bu s. Th ese d im en sion s are eq u al to th ose of th e 386DX p rocessor. Th e in tern al register size is wh ere th e “32-bit” d esign ation u sed in

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ad vertisem en ts com es from . Th e 486DX ch ip con tain s 1.2 m illion tran sistors on a p iece of silicon n o larger th an you r th u m bn ail. Th is figu re is m ore th an fou r tim es th e n u m ber of com p on en ts on 386 p rocessors an d sh ou ld give you a good in d ication of th e 486 ch ip ’s relative p ower. Th e d ie for th e 486 is sh own in Figu re 3.19.

FIG. 3.19 486 Processor d ie. Photograph used by perm ission of Intel Corporation. Th e stan d ard 486DX con tain s a p rocessin g u n it, a Floatin g-Poin t Un it (m ath cop rocessor), a m em ory-m an agem en t u n it, an d a cach e con troller with 8K of in tern alcach e RAM. Du e to th e in tern al cach e an d a m ore efficien t in tern al p rocessin g u n it, th e 486 fam ily of p rocessors can execu te in d ivid u al in stru ction s in an average of on ly two p rocessor cycles. Com p are th is figu re with th e 286 an d 386 fam ilies, both of wh ich execu te an average 4.5 cycles p er in stru ction . Com p are it also with th e origin al 8086 an d 8088 p rocessors, wh ich execu te an average 12 cycles p er in stru ction . At a given clock rate (MHz), th erefore, a 486 p rocessor is rou gh ly twice as efficien t as a 386 p rocessor; a 16MHz 486SX is rou gh ly eq u al to a 33MHz 386DX system ; an d a 20MHz 486SX is eq u al to a 40MHz 386DX system . An y of th e faster 486s are way beyon d th e 386 in p erform an ce. Th e 486 is fu lly in stru ction -set–com p atible with p reviou s In tel p rocessors, su ch as th e 386, bu t offers several ad d ition al in stru ction s (m ost of wh ich h ave to d o with con trollin g th e in tern al cach e).

Processor Types

Like th e 386DX, th e 486 can ad d ress 4G of p h ysical m em ory an d m an age as m u ch as 64T of virtu al m em ory. Th e 486 fu lly su p p orts th e th ree op eratin g m od es in trod u ced in th e 386: real m od e, p rotected m od e, an d virtu al real m od e. ■ In real m od e, th e 486 (like th e 386) ru n s u n m od ified 8086-typ e software. ■ In p rotected m od e, th e 486 (like th e 386) offers sop h isticated m em ory p agin g an d p rogram switch in g. ■ In virtu al real m od e, th e 486 (like th e 386) can ru n m u ltip le cop ies of DOS or oth er op eratin g system s wh ile sim u latin g an 8086’s real-m od e op eration . Un d er an op eratin g system su ch as W in d ows or OS/ 2, th erefore, both 16-bit an d 32-bit p rogram s can ru n sim u ltan eou sly on th is p rocessor with h ard ware m em ory p rotection . If on e p rogram crash es, th e rest of th e system is p rotected , an d you can reboot th e blown p ortion th rou gh variou s m ean s, d ep en d in g on th e op eratin g software. Th e 486DX series h as a bu ilt-in m ath cop rocessor th at som etim es is called an MCP (m ath cop rocessor) or FPU (Floatin g-Poin t Un it). Th is series is u n like p reviou s In tel CPU ch ip s, wh ich req u ired you to ad d a m ath cop rocessor if you n eed ed faster calcu lation s for com p lex m ath em atics. Th e FPU in th e 486DX series is 100% software-com p atible with th e extern al 387 m ath cop rocessor u sed with th e 386—bu t it d elivers m ore th an twice th e p erform an ce. It ru n s in syn ch ron ization with th e m ain p rocessor an d execu tes m ost in stru ction s in h alf as m an y cycles as th e 386. 4 8 6 SL. Th e 486SL was a sh ort-lived , stan d alon e ch ip . Th e SL en h an cem en ts an d featu res becam e available in virtu ally all th e 486 p rocessors (SX, DX, an d DX2) in wh at are called SL En h an ced version s. SL En h an cem en t refers to a sp ecial d esign th at in corp orates sp ecial p ower-savin g featu res. Th e SL En h an ced ch ip s origin ally were d esign ed to be in stalled in lap top or n otebook system s th at ru n on batteries, bu t th ey fou n d th eir way in to d esktop system s, as well. Th e SL En h an ced ch ip s featu red sp ecial p ower-m an agem en t tech n iq u es, su ch as sleep m od e an d clock th rottlin g, to red u ce p ower con su m p tion wh en n ecessary. Th ese ch ip s were available in 3.3v version s, as well. In tel d esign ed a p ower-m an agem en t arch itectu re called System Managem ent Mode (SMM ). Th is m od e of op eration is totally isolated an d in d ep en d en t from oth er CPU h ard ware an d software. SMM p rovid es h ard ware resou rces su ch as tim ers, registers, an d oth er I/ O logic th at can con trol an d p ower d own m obile-com p u ter com p on en ts with ou t in terferin g with an y of th e oth er system resou rces. SMM execu tes in a d ed icated m em ory sp ace called System Man agem en t Mem ory, wh ich is n ot visible an d d oes n ot in terfere with op eratin g-system an d ap p lication software. SMM h as an in terru p t called System Managem ent Interrupt (SMI ), wh ich services p ower-m an agem en t even ts an d is in d ep en d en t from , an d h igh er p riority th an , an y of th e oth er in terru p ts. SMM p rovid es p ower m an agem en t with flexibility an d secu rity th at were n ot available p reviou sly. For exam p le, an SMI occu rs wh en an ap p lication p rogram tries to access a p erip h eral d evice th at is p owered d own for battery savin gs, wh ich p owers u p th e p erip h eral d evice an d re-execu tes th e I/ O in stru ction au tom atically.

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In tel also d esign ed a featu re called su sp en d / resu m e in th e SL p rocessor. Th e system m an u factu rer can u se th is featu re to p rovid e th e p ortable-com p u ter u ser with in stan ton -an d -off cap ability. An SL system typ ically can resu m e (in stan t on ) in on e secon d from th e su sp en d state (in stan t off) to exactly wh ere it left off. You d o n ot n eed to reboot, load th e op eratin g system , load th e ap p lication p rogram , an d th en load th e ap p lication d ata. Sim p ly p u sh th e su sp en d / resu m e bu tton an d th e system is read y to go. Th e SL CPU was d esign ed to con su m e alm ost n o p ower in th e su sp en d state. Th is featu re m ean s th at th e system can stay in th e su sp en d state p ossibly for weeks an d yet start u p in stan tly righ t wh ere it left off. An SL system can keep workin g d ata in n orm al RAM m em ory safe for a lon g tim e wh ile it is in th e su sp en d state, bu t savin g to a d isk still is p ru d en t. 4 8 6 SX. Th e 486SX, in trod u ced in Ap ril 1991, was d esign ed to be sold as a lower-cost version of th e 486. Th e 486SX is virtu ally id en tical to th e fu ll DX p rocessor, bu t th e ch ip d oes n ot in corp orate th e FPU or m ath cop rocessor p ortion . As you read earlier in th is ch ap ter, th e 386SX was a scaled -d own (som e p eop le wou ld say crip p led ) 16-bit version of th e fu ll-blown 32-bit 386DX. Th e 386SX even h ad a com p letely d ifferen t p in ou t an d was n ot in terch an geable with th e m ore p owerfu l DX version . Th e 486SX, h owever, is a d ifferen t story. Th e 486SX is, in fact, a fu ll-blown 32-bit 486 p rocessor th at is basically p in -com p atible with th e DX. A few p in fu n ction s are d ifferen t or rearran ged , bu t each p in fits in to th e sam e socket. Th e 486SX ch ip is m ore a m arketin g q u irk th an n ew tech n ology. Early version s of th e 486SX ch ip actu ally were DX ch ip s th at sh owed d efects in th e m ath -cop rocessor section . In stead of bein g scrap p ed , th e ch ip s sim p ly were p ackaged with th e FPU section d isabled an d sold as SX ch ip s. Th is arran gem en t lasted for on ly a sh ort tim e; th ereafter, SX ch ip s got th eir own m ask, wh ich is d ifferen t from th e DX m ask. (A m ask is th e p h otograp h ic blu ep rin t of th e p rocessor an d is u sed to etch th e in tricate sign al p ath ways in to a silicon ch ip .) Th e tran sistor cou n t d rop p ed to 1.185 m illion (from 1.2 m illion ) to reflect th is n ew m ask. Th e 486SX ch ip is twice as fast as a 386DX with th e sam e clock sp eed . In tel m arketed th e 486SX as bein g th e id eal ch ip for n ew com p u ter bu yers, becau se fewer en try-level p rogram s of th at d ay u sed m ath -cop rocessor fu n ction s. Th e 486SX was n orm ally available in 16, 20, 25, an d 33MHz-rated sp eed s, an d th ere was also a 486 SX/ 2 th at ran at u p to 50 or 66MHz. Th e 486SX n orm ally com es in a 168-p in version , alth ou gh oth er su rface-m ou n t version s are available in SL En h an ced m od els. Desp ite wh at In tel’s m arketin g an d sales in form ation im p lies, n o tech n ical p rovision exists for ad d in g a sep arate m ath cop rocessor to a 486SX system ; n eith er is a sep arate m ath cop rocessor ch ip available to p lu g in . In stead , In tel wan ted you to ad d a n ew 486 p rocessor with a bu ilt-in m ath u n it an d d isable th e SX CPU th at alread y was on th e m oth erboard . If th is situ ation sou n d s con fu sin g, read on , becau se th is top ic brin gs you to th e m ost im p ortan t asp ect of 486 d esign : u p grad ability.

Processor Types

4 8 7 SX. Th e 487SX m ath cop rocessor, as In tel calls it, really is a com p lete 25MHz 486DX CPU with an extra p in ad d ed an d som e oth er p in s rearran ged . W h en th e 487SX is in stalled in th e extra socket p rovid ed in a 486SX-CPU-based system , th e 487SX tu rn s off th e existin g 486SX via a n ew sign al on on e of th e p in s. Th e extra key p in actu ally carries n o sign al itself an d exists on ly to p reven t im p rop er orien tation wh en th e ch ip is in stalled in a socket. Th e 487SX takes over all CPU fu n ction s from th e 486SX an d also p rovid es m ath cop rocessor fu n ction ality in th e system . At first glan ce, th is setu p seem s rath er stran ge an d wastefu l, so p erh ap s fu rth er exp lan ation is in ord er. Fortu n ately, th e 487SX tu rn ed ou t sim p ly to be a stop gap m easu re wh ile In tel p rep ared its real su rp rise: th e OverDrive p rocessor. Th e DX2/ OverDrive sp eed -d ou blin g ch ip s, wh ich are d esign ed for th e 487SX 169-p in socket, h ave th e sam e p in ou t as th e 487SX. Th ese u p grad e ch ip s are in stalled in exactly th e sam e way as th e 487SX; th erefore, an y system th at su p p orts th e 487SX also su p p orts th e DX2/ OverDrive ch ip s. Alth ou gh in m ost cases you can u p grad e a system by rem ovin g th e 486SX CPU an d rep lacin g it with a 487SX (or even a DX or DX2/ OverDrive), In tel origin ally d iscou raged th is p roced u re. In stead , In tel recom m en d ed th at PC m an u factu rers in clu d e a d ed icated u p grad e (OverDrive) socket in th eir system s, becau se several risks were in volved in rem ovin g th e origin al CPU from a stan d ard socket. (Th e followin g section elaborates on th ose risks.) Now In tel recom m en d s—or even in sists on —th e u se of a sin gle p rocessor socket of a ZIF d esign , wh ich m akes u p grad in g an easy task p h ysically. Very few early 486 system s h ad a socket for th e W eitek 4167 cop rocessor ch ip for 486 system s th at existed in Novem ber 1989. D X2 / Ov e rD ri v e a n d D X4 P ro c e sso rs. On March 3, 1992, In tel in trodu ced th e DX2 speed-dou blin g processors. On May 26, 1992, In tel an n ou n ced th at th e DX2 processors also wou ld be available in a retail version called OverDrive. Origin ally, th e OverDrive version s of th e DX2 were available on ly in 169-pin version s, wh ich m ean t th at th ey cou ld be u sed on ly with 486SX system s th at h ad sockets con figu red to su pport th e rearran ged pin con figu ration . On Sep tem ber 14, 1992, In tel in trod u ced 168-p in OverDrive version s for u p grad in g 486DX system s. Th ese p rocessors cou ld be ad d ed to existin g 486 (SX or DX) system s as an u p grad e, even if th ose system s d id n ot su p p ort th e 169-p in con figu ration . W h en you u se th is p rocessor as an u p grad e, you sim p ly in stall th e n ew ch ip in you r system , wh ich su bseq u en tly ru n s twice as fast. Th e DX2/ OverDrive p rocessors ru n in tern ally at twice th e clock rate of th e h ost system . If th e m oth erboard clock is 25MHz, for exam p le, th e DX2/ OverDrive ch ip ru n s in tern ally at 50MHz; likewise, if th e m oth erboard is a 33MHz d esign , th e DX2/ OverDrive ru n s at 66MHz. Th e DX2/ OverDrive sp eed d ou blin g h as n o effect on th e rest of th e system ; all com p on en ts on th e m oth erboard ru n th e sam e as th ey d o with a stan d ard 486 p rocessor. Th erefore, you d o n ot h ave to ch an ge oth er com p on en ts (su ch as m em ory) to accom m od ate th e d ou ble-sp eed ch ip . Th e DX2/ OverDrive ch ip s h ave been available in several sp eed s. Th ree d ifferen t sp eed -rated version s h ave been offered :

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■ 40MHz DX2/ OverDrive for 16MHz or 20MHz system s ■ 50MHz DX2/ OverDrive for 25MHz system s ■ 66MHz DX2/ OverDrive for 33MHz system s Notice th at th ese ratin gs in d icate th e m axim u m sp eed at wh ich th e ch ip is cap able of ru n n in g. You cou ld u se a 66MHz-rated ch ip in p lace of th e 50MHz- or 40MHz-rated p arts with n o p roblem , alth ou gh th e ch ip will ru n on ly at th e slower sp eed s. Th e actu al sp eed of th e ch ip is d ou ble th e m oth erboard clock freq u en cy. W h en th e 40MHz DX2/ OverDrive ch ip is in stalled in a 16MHz 486SX system , for exam p le, th e ch ip will fu n ction on ly at 32MHz—exactly d ou ble th e m oth erboard sp eed . In tel origin ally stated th at n o 100MHz DX2/ OverDrive ch ip wou ld be available for 50MHz system s—wh ich tech n ically h as n ot been tru e, becau se th e DX4 cou ld be set to ru n in a clock-d ou bled m od e an d u sed in a 50MHz m oth erboard (see th e d iscu ssion of th e DX4 p rocessor in th is section ). Th e on ly p art of th e DX2 ch ip th at d oesn ’t ru n at d ou ble sp eed is th e bu s in terface u n it, a region of th e ch ip th at h an d les I/ O between th e CPU an d th e ou tsid e world . By tran slatin g between th e d ifferin g in tern al an d extern al clock sp eed s, th e bu s in terface u n it m akes sp eed d ou blin g tran sp aren t to th e rest of th e system . Th e DX2 ap p ears to th e rest of th e system to be a regu lar 486DX ch ip , bu t on e th at seem s to execu te in stru ction s twice as fast. DX2/ OverDrive ch ip s are based on th e 0.8-m icron circu it tech n ology th at was first u sed in th e 50MHz 486DX. Th e DX2 con tain s 1.1 m illion tran sistors in a th ree-layer form . Th e in tern al 8K cach e, in teger, an d Floatin g-Poin t Un its all ru n at d ou ble sp eed . Extern al com m u n ication with th e PC ru n s at n orm al sp eed to m ain tain com p atibility. Besid es u p grad in g existin g system s, on e of th e best p arts of th e DX2 con cep t was th e fact th at system d esign ers cou ld in trod u ce very fast system s by u sin g ch eap er m oth erboard d esign s, rath er th an th e m ore costly d esign s th at wou ld su p p ort a straigh t h igh -sp eed clock. Th is m ean s th at a 50MHz 486DX2 system was m u ch less exp en sive th an a straigh t 50MHz 486DX system . Th e system board in a 486DX-50 system op erates at a tru e 50MHz. Th e 486DX2 CPU in a 486DX2-50 system op erates in tern ally at 50MHz, bu t th e m oth erboard op erates at on ly 25MHz. You m ay be th in kin g th at a tru e 50MHz DX-p rocessor–based system still wou ld be faster th an a sp eed -d ou bled 25MHz system , an d th is gen erally is tru e, bu t th e d ifferen ces in sp eed actu ally are very sligh t—a real testam en t to th e in tegration of th e 486 p rocessor an d esp ecially to th e cach e d esign . W h en th e p rocessor h as to go to system m em ory for d ata or in stru ction s, for exam p le, it h as to d o so at th e slower m oth erboard op eratin g freq u en cy (su ch as 25MHz). Becau se th e 8K in tern al cach e of th e 486DX2 h as a h it rate of 90–95%, h owever, th e CPU h as to access system m em ory on ly 5–10% of th e tim e for m em ory read s. Th erefore, th e p erform an ce of th e DX2 system can com e very close to th at of a tru e 50MHz DX system an d cost m u ch less. Even th ou gh th e m oth erboard ru n s on ly at 33.33MHz, a system with a DX2 66MHz p rocessor en d s u p bein g faster th an a tru e 50MHz DX system , esp ecially if th e DX2 system h as a good Level 2 cach e.

Processor Types

Man y 486 m oth erboard d esign s also in clu d e a secon d ary cach e th at is extern al to th e cach e in tegrated in to th e 486 ch ip . Th is extern al cach e allows for m u ch faster access wh en th e 486 ch ip calls for extern al-m em ory access. Th e size of th is extern al cach e can vary an ywh ere from 16K to 512K or m ore. W h en you ad d a DX2 p rocessor, an extern al cach e is even m ore im p ortan t for ach ievin g th e greatest p erform an ce gain . Th is cach e greatly red u ces th e wait states th at th e p rocessor will h ave to ad d wh en writin g to system m em ory or wh en a read cau ses an in tern al-cach e m iss. For th is reason , som e system s p erform better with th e DX2/ OverDrive p rocessors th an oth ers, u su ally d ep en d in g on th e size an d efficien cy of th e extern al-m em ory cach e system on th e m oth erboard . System s th at h ave n o extern al cach e will still en joy a n ear-d ou blin g of CPU p erform an ce, bu t op eration s th at in volve a great d eal of m em ory access will be slower. Th is brin gs u s to th e DX4 p rocessor. Alth ou gh th e stan d ard DX4 tech n ically was n ot sold as a retail p art, it cou ld be p u rch ased from several ven d ors, alon g with th e 3.3v voltage ad ap ter n eed ed to in stall th e ch ip in a 5v socket. Th ese ad ap ters h ave ju m p ers th at en able you to select th e DX4 clock m u ltip lier an d set it to 2x, 2.5x, or 3x m od e. In a 50MHz DX system , you cou ld in stall a DX4/ voltage-regu lator com bin ation set in 2x m od e for a m oth erboard sp eed of 50MHz an d a p rocessor sp eed of 100MHz! Alth ou gh you m ay n ot be able to take ad van tage of certain VL-Bu s ad ap ter card s, you will h ave on e of th e fastest 486-class PCs available. In tel also sold a sp ecial DX4 OverDrive p rocessor th at in clu d ed a bu ilt-in voltage regu lator an d h eat sin k th at are sp ecifically d esign ed for th e retail m arket. Th e DX4 OverDrive ch ip is essen tially th e sam e as th e stan d ard 3.3v DX4 with th e m ain excep tion th at it ru n s on 5v becau se it in clu d es an on -ch ip regu lator. Also, th e DX4 OverDrive ch ip will ru n on ly in th e trip led sp eed m od e, an d n ot th e 2x or 2.5x m od es of th e stan d ard DX4 p rocessor.

Not e As of this writing, Intel has discontinued all 486 and DX2/ DX4/ OverDrive processors, including the so-called Pentium OverDrive Processor.

P e n t i u m Ov e rD ri v e f o r 4 8 6 SX2 a n d D X2 Sy st e m s. Th e Pen tiu m OverDrive Processor becam e available in 1995. An OverDrive ch ip for 486DX4 system s h ad been p lan n ed , bu t p oor m arketp lace p erform an ce of th e SX2/ DX2 ch ip m ean t th at it n ever saw th e ligh t of d ay. On e th in g to keep in m in d abou t th e 486 Pen tiu m OverDrive ch ip is th at alth ou gh it is in ten d ed p rim arily for SX2 an d DX2 system s, it sh ou ld work in an y u p grad able 486SX or DX system th at h as a Socket 2 or Socket 3. If in d ou bt, ch eck In tel’s on lin e u p grad e gu id e for com p atibility. Th e Pen tiu m OverDrive Processor is d esign ed for system s th at h ave a p rocessor socket th at follows th e In tel Socket 2 sp ecification . Th is p rocessor also will work in system s th at h ave a Socket 3 d esign , alth ou gh you sh ou ld en su re th at th e voltage is set for 5v rath er th an 3.3v. Th e Pen tiu m OverDrive ch ip in clu d es a 32K in tern al Level 1 cach e, an d th e sam e su p erscalar (m u ltip le in stru ction p ath ) arch itectu re of th e real Pen tiu m ch ip .

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Besid es a 32-bit Pen tiu m core, th ese p rocessors featu re in creased clock-sp eed op eration d u e to in tern al clock m u ltip lication , an d in corp orate an in tern al W rite-Back cach e (stan d ard with th e Pen tiu m ). If th e m oth erboard su p p orts th e W rite-Back cach e fu n ction , in creased p erform an ce will be realized . Un fortu n ately, m ost m oth erboard s, esp ecially old er on es with th e Socket 2 d esign , on ly su p p ort W rite-Th rou gh cach e. Most tests of th ese OverDrive ch ip s sh ow th em to be on ly sligh tly ah ead of th e DX4-100, an d beh in d th e DX4-120 an d tru e Pen tiu m 60, 66, or 75. Un fortu n ately, th ese are th e on ly solu tion s still offered by In tel for u p grad in g th e 486. Based on th e relative afford ability tod ay of low-en d “real” Pen tiu m s, it seem s h ard n ot to ju stify m akin g th e step u p to a m ore m od ern system . I wou ld n ot recom m en d th e 486 Pen tiu m OverDrive ch ip s as a viable solu tion for th e fu tu re. “Vacancy”—Secondary OverDrive Socket s. Perh ap s you saw th e In tel ad vertisem en ts—both p rin t an d television —th at featu red a 486SX system with a n eon Vacan cy sign p oin tin g to an em p ty socket n ext to th e CPU ch ip . Un fortu n ately, th ese ad s were n ot very in form ative, an d th ey m ad e it seem th at on ly system s with th e extra socket cou ld be u p grad ed . I was worried wh en I first saw th ese ad s becau se I h ad ju st p u rch ased a 486DX system , an d th e ad vertisem en ts im p lied th at on ly 486SX system s with th e em p ty OverDrive socket were u p grad able. Th is, of cou rse, was n ot tru e, bu t th e In tel ad vertisem en ts su rely d id n ot com m u n icate th at fact very well. I later fou n d th at u p grad ability d oes n ot d ep en d on h avin g an extra OverDrive socket in th e system an d th at virtu ally an y 486SX or DX system can be u p grad ed . Th e secon d ary OverDrive socket was d esign ed sim p ly to m ake u p grad in g easier an d m ore con ven ien t. Even in system s th at h ave th e secon d socket, you can actu ally rem ove th e p rim ary SX or DX CPU an d p lu g th e OverDrive p rocessor d irectly in to th e m ain CPU socket, rath er th an in to th e secon d ary OverDrive socket. In th at case, you wou ld h ave an u p grad ed system with a sin gle fu n ction in g CPU in stalled ; you cou ld rem ove th e old CPU from th e system an d sell it or trad e it in for a refu n d . Un fortu n ately, In tel d oes n ot offer a trad e-in or core-ch arge p olicy; it sim p ly d oes n ot wan t you r old ch ip . For th is reason , som e p eop le saw th e OverDrive socket as bein g a way for In tel to sell m ore CPUs. Som e valid reason s exist, h owever, to u se th e OverDrive socket an d leave th e origin al CPU in stalled . On e reason is th at m an y PC m an u factu rers void th e system warran ty if th e CPU h as been rem oved from th e system . Also, m ost m an u factu rers req u ire th at th e system be retu rn ed with on ly th e origin al p arts wh en system s are serviced ; you m u st rem ove all ad d -in card s, m em ory m od u les, u p grad e ch ip s, an d sim ilar item s before sen d in g th e system in for servicin g. If you rep lace th e origin al CPU wh en you in stall th e u p grad e, retu rn in g th e system to its origin al con d ition will be m u ch m ore d ifficu lt. An oth er reason for u sin g th e u p grad e socket is th at th e system will n ot fu n ction if th e m ain CPU socket is d am aged wh en you rem ove th e origin al CPU or in stall th e u p grad e p rocessor. By con trast, if a secon d ary u p grad e socket is d am aged , th e system still sh ou ld work with th e origin al CPU.

Processor Types

80487 Upgrade. Th e In tel 80486 p rocessor was in trod u ced in late 1989, an d system s u sin g th is ch ip ap p eared d u rin g 1990. Th e 486DX in tegrated th e m ath cop rocessor in to th e ch ip . Th e 486SX began life as a fu ll-fled ged 486DX ch ip , bu t In tel actu ally d isabled th e bu ilt-in m ath cop rocessor before sh ip p in g th e ch ip . As p art of th is m arketin g sch em e, In tel m arketed wh at it called a 487SX m ath cop rocessor. Moth erboard m an u factu rers in stalled an In tel-d esign ed socket for th is so-called 487 ch ip . In reality, h owever, th e 487SX m ath ch ip was a sp ecial 486DX ch ip with th e m ath cop rocessor en abled . W h en you p lu gged th is ch ip in to you r m oth erboard , it d isabled th e 486SX ch ip an d gave you th e fu n ction al eq u ivalen t of a fu ll-fled ged 486DX system . AM D 486 ( 5x86) . AMD m akes a lin e of 486-com p atible ch ip s th at in stall in to stan d ard 486 m oth erboard s. In fact, AMD m akes th e fastest 486 p rocessor available, wh ich th ey call th e Am 5x86(TM)-P75. Th e n am e is a little m islead in g, as th e 5x86 p art m akes som e p eop le th in k th at th is is a fifth -gen eration Pen tiu m -typ e p rocessor. In reality, it is a fast clock-m u ltip lied (4x clock) 486 th at ru n s at fou r tim es th e sp eed of th e 33MHz 486 m oth erboard you p lu g it in to. Th e 5x85 offers h igh -p erform an ce featu res su ch as a u n ified 16K write-back cach e an d 133MHz core clock sp eed , an d is ap p roxim ately com p arable to a Pen tiu m 75, wh ich is wh y it is d en oted with a P-75 in th e p art n u m ber. It is th e id eal ch oice for cost-effective 486 u p grad es, wh ere ch an gin g th e m oth erboard is d ifficu lt or im p ossible. Not all m oth erboard s su p p ort th e 5x86. Th e best way to verify th at you r m oth erboard su p p orts th e ch ip is by ch eckin g with th e d ocu m en tation th at cam e with th e board . Look for key word s su ch as “Am 5X86,” “AMD-X5,” “clock-q u ad ru p led ,” “133MHz,” or oth er sim ilar word in g. An oth er good way to d eterm in e wh eth er you r m oth erboard su p p orts th e AMD 5x86 is to look for it in th e listed m od els on AMD’s W eb site. Th ere are a few th in gs to n ote wh en in stallin g a 5x86 p rocessor in to a 486 m oth erboard : ■ Th e op eratin g voltage for th e 5x86 is 3.45v +/ - 0.15v. Not all m oth erboard s m ay h ave th is settin g, bu t m ost th at in corp orate a Socket 3 d esign sh ou ld . If you r 486 m oth erboard is a Socket 1 or 2 d esign , you can n ot u se th e 5x86 p rocessor d irectly. Th e 3.45 volt p rocessor will n ot op erate in a 5-volt socket an d m ay be d am aged . To con vert a 5-volt m oth erboard to 3.45 volts, ad ap ters can be p u rch ased from several ven d ors in clu d in g Kin gston , Evergreen , an d AMP. In fact, Kin gston an d Evergreen sell th e 5x86 com p lete with a voltage regu lator ad ap ter attach ed in an easy-toin stall p ackage. Th ese version s are id eal for old er 486 m oth erboard s th at d on ’t h ave a Socket 3 d esign . ■ It is gen erally better to p u rch ase a n ew m oth erboard with Socket 3 th an to bu y on e of th ese ad ap ters; h owever, 486 m oth erboard s are h ard to fin d th ese d ays, an d you r old board m ay be in a p rop rietary form factor for wh ich it is im p ossible to fin d a rep lacem en t. Bu yin g a n ew m oth erboard is also better th an u sin g an ad ap ter becau se th e old er BIOS m ay n ot u n d erstan d th e req u irem en ts of th e p rocessor as far as sp eed is con cern ed . BIOS u p d ates are often req u ired with old er board s.

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■ Most Socket 3 m oth erboard s h ave ju m p ers, allowin g you to set th e voltage m an u ally. Som e board s d on ’t h ave ju m p ers, bu t h ave voltage au tod etect in stead . Th ese system s ch eck th e VOLDET p in (p in S4) on th e m icrop rocessor wh en th e system is p owered on . ■ Th e VOLDET p in is tied to grou n d (Vss) in tern ally to th e m icrop rocessor. If you can n ot fin d an y ju m p ers for settin g voltage, you can ch eck th e m oth erboard as follows: Switch th e PC off, rem ove th e m icrop rocessor, con n ect p in S4 to a Vss p in on th e ZIF socket, p ower on , an d ch eck an y Vcc p in with a voltm eter. Th is sh ou ld read 3.45 (± 0.15) volts. See th e p reviou s section on CPU sockets for th e p in ou t. ■ Th e 5x86 req u ires a 33MHz m oth erboard sp eed , so be su re th e board is set to th at freq u en cy. Th e 5x86 op erates at an in tern al sp eed of 133MHz. Th erefore, th e ju m p ers m u st be set for “clock-q u ad ru p led ” or “4X Clock” m od e. By settin g th e ju m p ers correctly on th e m oth erboard , th e CLKMUL p in (p in R17) on th e p rocessor will be con n ected to grou n d (Vss). If th ere is n o 4x clock settin g, th e stan d ard DX2 2x clock settin g sh ou ld work. ■ Som e m oth erboard s h ave ju m p ers th at con figu re th e in tern al cach e in eith er W riteBack (W B) or W rite-Th rou gh (W T) m od e. Th ey d o th is by p u llin g th e W B/ W T p in (p in B13) on th e m icrop rocessor to logic High (Vcc) for W B, or to grou n d (Vss) for W T. For best p erform an ce, con figu re you r system in W B m od e; h owever, reset th e cach e to W T m od e if th ere are p roblem s ru n n in g ap p lication s or th e flop p y d rive d oesn ’t work righ t (DMA con flicts). ■ Th e 5x86 ru n s h ot, so a h eat sin k is req u ired ; it n orm ally m u st h ave a fan . In ad d ition to th e 5x86, th e AMD En h an ced 486 p rod u ct lin e in clu d es 80MHz, 100MHz, an d 120MHz CPUs. Th ese are th e A80486DX2-80SV8B (40MHz x 2), A80486DX4100SV8B (33MHz x 3), an d th e A80486DX4-120SV8B (40MHz x 3). Cyrix/ TI 486. Th e Cyrix 486DX2/ DX4 p rocessors were available in 100MHz, 80MHz, 75MHz, 66MHz, an d 50MHz version s. Like th e AMD 486 ch ip s, th e Cyrix version s are fu lly com p atible with In tel’s 486 p rocessors an d work in m ost 486 m oth erboard s. Th e Cx486DX2/ DX4 in corp orates an 8K write-back cach e, an in tegrated Floatin g-Poin t Un it, ad van ced p ower m an agem en t, an d SMM, an d was available in 3.3v version s.

Not e TI originally made all the Cyrix-designed 486 processors, and under their agreement they also sold them under the TI name. Eventually, TI and Cyrix had a falling out, and now IBM makes most of the Cyrix chips, although that may change since National Semiconductor has purchased Cyrix.

Processor Types

P5 ( 586) Fift h-Generat ion Processors Pent ium . On October 19, 1992, In tel an n ou n ced th at th e fifth gen eration of its com p atible m icrop rocessor lin e (cod e-n am ed P5) wou ld be n am ed th e Pen tiu m p rocessor rath er th an th e 586, as everybod y h ad been assu m in g. Callin g th e n ew ch ip th e 586 wou ld h ave been n atu ral, bu t In tel d iscovered th at it cou ld n ot trad em ark a n u m ber d esign ation , an d th e com p an y wan ted to p reven t oth er m an u factu rers from u sin g th e sam e n am e for an y clon e ch ip s th at th ey m igh t d evelop . Th e actu al Pen tiu m ch ip sh ip p ed on March 22, 1993. System s th at u se th ese ch ip s were on ly a few m on th s beh in d . Th e Pen tiu m is fu lly com p atible with p reviou s In tel p rocessors, bu t it also d iffers from th em in m an y ways. At least on e of th ese d ifferen ces is revolu tion ary: Th e Pen tiu m featu res twin d ata p ip elin es, wh ich en able it to execu te two in stru ction s at th e sam e tim e. Th e 486 an d all p reced in g ch ip s can p erform on ly a sin gle in stru ction at a tim e. In tel calls th e cap ability to execu te two in stru ction s at th e sam e tim e superscalar technology. Th is tech n ology p rovid es ad d ition al p erform an ce com p ared with th e 486. Th e stan d ard 486 ch ip can execu te a sin gle in stru ction in an average of two clock cycles—cu t to an average of on e clock cycle with th e ad ven t of in tern al clock m u ltip lication u sed in th e DX2 an d DX4 p rocessors. W ith su p erscalar tech n ology, th e Pen tiu m can execu te m an y in stru ction s at a rate of two in stru ction s p er cycle. Su p erscalar arch itectu re u su ally is associated with h igh -ou tp u t RISC (Red u ced In stru ction Set Com p u ter) ch ip s. Th e Pen tiu m is on e of th e first CISC (Com p lex In stru ction Set Com p u ter) ch ip s to be con sid ered su p erscalar. Th e Pen tiu m is alm ost like h avin g two 486 ch ip s u n d er th e h ood . Table 3.17 sh ows th e Pen tiu m p rocessor sp ecification s. Table 3.17

Pent ium Processor Specificat ions

Introduced:

M arch 22, 1993 (first generation); M arch 7, 1994 (second generation)

M aximum rated speeds:

60, 66M Hz (first generation); 75, 90, 100, 120, 133, 150, 166, 200M Hz (second generation)

CPU clock multiplier:

1x (first generation), 1.5x–3x (second generation)

Register size:

32-bit

External data bus:

64-bit

M emory address bus:

32-bit

M aximum memory:

4G

Integral-cache size:

8K code, 8K data

Integral-cache type:

2-Way Set Associative, Write-Back Data

Burst-mode transfers:

Yes

Number of transistors:

3.1 million

Circuit size:

0.8 micron (60/ 66M Hz), 0.6 micron (75–100M Hz), 0.35 micron (120M Hz and up)

External package:

273-pin PGA, 296-pin SPGA, Tape Carrier

M ath coprocessor:

Built-in FPU (Floating-Point Unit) (continues)

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Table 3.17

Pent ium Processor Specificat ions Cont inued

Power management:

SM M (System M anagement M ode), enhanced in second generation

Operating voltage:

5v (first generation), 3.465v, 3.3v, 3.1v, 2.9v (second generation)

PGA = Pin Grid Array SPGA = Staggered Pin Grid Array

Th e two in stru ction p ip elin es with in th e ch ip are called th e u - an d v-p ip es. Th e u-pipe, wh ich is th e p rim ary p ip e, can execu te all in teger an d floatin g-p oin t in stru ction s. Th e v-pipe is a secon d ary p ip e th at can execu te on ly sim p le in teger in stru ction s an d certain floatin g-p oin t in stru ction s. Th e p rocess of op eratin g on two in stru ction s sim u ltan eou sly in th e d ifferen t p ip es is called pairing. Not all seq u en tially execu tin g in stru ction s can be p aired , an d wh en p airin g is n ot p ossible, on ly th e u -p ip e is u sed . To op tim ize th e Pen tiu m ’s efficien cy, you can recom p ile software to allow m ore in stru ction s to be p aired . Th e Pen tiu m is 100% software-com p atible with th e 386 an d 486, an d alth ou gh all cu rren t software will ru n m u ch faster on th e Pen tiu m , m an y software m an u factu rers wan t to recom p ile th eir ap p lication s to exp loit even m ore of th e Pen tiu m ’s tru e p ower. In tel h as d evelop ed n ew com p ilers th at will take fu ll ad van tage of th e ch ip ; th e com p an y will licen se th e tech n ology to com p iler firm s so th at software d evelop ers can take ad van tage of th e Pen tiu m ’s su p erscalar (p arallel p rocessin g) cap ability. Th is op tim ization rap id ly started to ap p ear in th e software on th e m arket. Op tim ized software im p roved p erform an ce by allowin g m ore in stru ction s to execu te sim u ltan eou sly in both p ip es. Th e Pen tiu m p rocessor h as a Bran ch Target Bu ffer (BTB), wh ich em p loys a tech n iq u e called branch prediction. It m in im izes stalls in on e or m ore of th e p ip es cau sed by d elays in fetch in g in stru ction s th at bran ch to n on lin ear m em ory location s. Th e BTB attem p ts to p red ict wh eth er a p rogram bran ch will be taken an d th en fetch es th e ap p rop riate in stru ction s. Th e u se of bran ch p red iction en ables th e Pen tiu m to keep both p ip elin es op eratin g at fu ll sp eed . Figu re 3.20 sh ows th e in tern al arch itectu re of th e Pen tiu m p rocessor. Th e Pen tiu m h as a 32-bit ad d ress bu s wid th , givin g it th e sam e 4G m em ory-ad d ressin g cap abilities as th e 386DX an d 486 p rocessors. Bu t th e Pen tiu m exp an d s th e d ata bu s to 64 bits, wh ich m ean s th at it can m ove twice as m u ch d ata in to or ou t of th e CPU, com p ared with a 486 of th e sam e clock sp eed . Th e 64-bit d ata bu s req u ires th at system m em ory be accessed 64 bits wid e, wh ich m ean s th at each ban k of m em ory is 64 bits. On m ost m oth erboard s, m em ory is in stalled via SIMMs (Sin gle In lin e Mem ory Mod u les) or DIMMs (Du al In lin e Mem ory Mod u les). SIMMs are available in 8-bit-wid e an d 32-bitwid e version s, wh ile DIMMs are 64 bits wid e. Th ere are also version s with ad d ition al bits for p arity or ECC (Error Correctin g Cod e) d ata. Most Pen tiu m system s u se th e 32-bitwid e SIMMs—two of th ese SIMMs p er ban k of m em ory. Most Pen tiu m m oth erboard s h ave at least fou r of th ese 32-bit SIMM sockets, p rovid in g for a total of two ban ks of m em ory. Th e n ewest Pen tiu m system s an d m ost Pen tiu m II system s tod ay u se DIMMs, wh ich are 64 bits wid e—ju st like th e p rocessor’s extern al d ata bu s so on ly on e DIMM is

Processor Types

u sed p er ban k. Th is m akes in stallin g or u p grad in g m em ory m u ch easier becau se DIMMs can go in on e at a tim e an d d on ’t h ave to be m atch ed u p in p airs.

Control

DP Logic

Branch Prefetch TLB Code Cache Target 8 KBytes Buffer Address 256 Instruction Pointer

64-Bit Data Bus 32-Bit Address Bus

Control ROM

Prefetch Buffers Instruction Decode

Branch Verif. & Target Addr Bus Unit

Control Unit Page Unit Address Generate (U Pipeline)

Control

Address Generate (V Pipeline)

Floating Point Unit Control Register File

Integer Register File 64-Bit 64 Data Bus

ALU (U Pipeline)

Divide Barrel Shifter

Control

80

Multiply 80 32 32

APIC

Add

32 32-Bit Addr. Bus

Data

ALU (V Pipeline)

32

TLB

Data Cache 8 KBytes

32 32 32

FIG. 3.20 Pen tiu m p rocessor in tern al arch itectu re. ◊◊ See “ SIM M s and DIM M s,” p. 324, and “ M emory Banks,“ p. 338

Even th ou gh th e Pen tiu m h as a 64-bit d ata bu s th at tran sfers in form ation 64 bits at a tim e in to an d ou t of th e p rocessor, th e Pen tiu m h as on ly 32-bit in tern al registers. As in stru ction s are bein g p rocessed in tern ally, th ey are broken d own in to 32-bit in stru ction s an d d ata elem en ts, an d p rocessed in m u ch th e sam e way as in th e 486. Som e p eop le th ou gh t th at In tel was m islead in g th em by callin g th e Pen tiu m a 64-bit p rocessor, bu t 64-bit tran sfers d o in d eed take p lace. In tern ally, h owever, th e Pen tiu m h as 32-bit registers th at are fu lly com p atible with th e 486. Th e Pen tiu m h as two sep arate in tern al 8K cach es, com p ared with a sin gle 8K or 16K cach e in th e 486. Th e cach e-con troller circu itry an d th e cach e m em ory are em bed d ed in th e CPU ch ip . Th e cach e m irrors th e in form ation in n orm al RAM by keep in g a cop y of th e d ata an d cod e from d ifferen t m em ory location s. Th e Pen tiu m cach e also can h old

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in form ation to be written to m em ory wh en th e load on th e CPU an d oth er system com p on en ts is less. (Th e 486 m akes all m em ory writes im m ed iately.) Th e sep arate cod e an d d ata cach es are organ ized in a two-way set associative fash ion , with each set sp lit in to lin es of 32 bytes each . Each cach e h as a d ed icated Tran slation Lookasid e Bu ffer (TLB), wh ich tran slates lin ear ad d resses to p h ysical ad d resses. You can con figu re th e d ata cach e as W rite-Back or W rite-Th rou gh on a lin e-by-lin e basis. W h en you u se th e W rite-Back cap ability, th e cach e can store write op eration s an d read s, fu rth er im p rovin g p erform an ce over read -on ly W rite-Th rou gh m od e. Usin g W rite-Back m od e resu lts in less activity between th e CPU an d system m em ory—an im p ortan t im p rovem en t, becau se CPU access to system m em ory is a bottlen eck on fast system s. Th e cod e cach e is an in h eren tly write-p rotected cach e becau se it con tain s on ly execu tion in stru ction s an d n ot d ata, wh ich is u p d ated . Becau se bu rst cycles are u sed , th e cach e d ata can be read or written very q u ickly. System s based on th e Pen tiu m can ben efit greatly from secon d ary p rocessor cach es (Level 2), wh ich u su ally con sist of u p to 512K or m ore of extrem ely fast (15n s or less) Static RAM (SRAM) ch ip s. W h en th e CPU fetch es d ata th at is n ot alread y available in its in tern al p rocessor (Level 1) cach e, wait states slow th e CPU. If th e d ata alread y is in th e secon d ary p rocessor cach e, h owever, th e CPU can go ah ead with its work with ou t p au sin g for wait states. Th e Pen tiu m u ses a BiCMOS (Bip olar Com p lem en tary Metal Oxid e Sem icon d u ctor) p rocess an d su p erscalar arch itectu re to ach ieve th e h igh level of p erform an ce exp ected from th e ch ip . BiCMOS ad d s abou t 10% to th e com p lexity of th e ch ip d esign , bu t ad d s abou t 30–35% better p erform an ce with ou t a size or p ower p en alty. All Pen tiu m p rocessors are SL En h an ced , m ean in g th at th ey in corp orate th e SMM to p rovid e fu ll con trol of p ower-m an agem en t featu res, wh ich h elp s red u ce p ower con su m p tion . Th e secon d -gen eration Pen tiu m p rocessors (75MHz an d faster) in corp orate a m ore ad van ced form of SMM th at in clu d es p rocessor clock con trol. Th is allows you to th rottle th e p rocessor u p or d own to con trol p ower u se. You can even stop th e clock with th ese m ore ad van ced Pen tiu m p rocessors, p u ttin g th e p rocessor in a state of su sp en sion th at req u ires very little p ower. Th e secon d -gen eration Pen tiu m p rocessors ru n on 3.3v p ower (in stead of 5v), red u cin g p ower req u irem en ts an d h eat gen eration even fu rth er. Man y cu rren t m oth erboard s su p p ly eith er 3.465v or 3.3v. Th e 3.465v settin g is called V RE (V oltage Reduced Extended ) by In tel an d is req u ired by som e version s of th e Pen tiu m , p articu larly som e of th e 100MHz version s. Th e stan d ard 3.3v settin g is called STD (Standard ), wh ich m ost of th e secon d -gen eration Pen tiu m s u se. STD voltage m ean s an yth in g in a ran ge from 3.135v to 3.465v with 3.3v n om in al. Th ere is also a sp ecial 3.3v settin g called V R (V oltage Reduced ), wh ich red u ces th e ran ge from 3.300v to 3.465v with 3.38v n om in al. Som e of th e p rocessors req u ire th is n arrower sp ecification , wh ich m ost m oth erboard s p rovid e. Here is a su m m ary:

Processor Types

Volt age Specificat ion

Nom inal

Tolerance

M inim um

M axim um

STD (Standard)

3.30v

±0.165

3.135v

3.465v

VR (Voltage Reduced)

3.38v

±0.083

3.300v

3.465v

VRE (VR Extended)

3.50v

±0.100

3.400v

3.600v

For even lower p ower con su m p tion , In tel h as in trod u ced sp ecial Pen tiu m p rocessors with Voltage Red u ction Tech n ology in th e 75 to 266MHz fam ily; th e p rocessors are in ten d ed for m obile com p u ter ap p lication s. Th ey d o n ot u se a con ven tion al ch ip p ackage an d are in stead m ou n ted u sin g a n ew form at called Tape Carrier Packaging (TCP). Th e tap e carrier p ackagin g d oes n ot en case th e ch ip in ceram ic or p lastic as with a con ven tion al ch ip p ackage, bu t in stead covers th e actu al p rocessor d ie d irectly with a th in , p rotective p lastic coatin g. Th e en tire p rocessor is less th an 1m m th ick, or abou t h alf th e th ickn ess of a d im e, an d weigh s less th an 1 gram . Th ey are sold to system m an u factu rers in a roll th at looks very m u ch like a film strip . Th e TCP p rocessor is d irectly affixed (sold ered ) to th e m oth erboard by a sp ecial m ach in e, resu ltin g in a sm aller p ackage, lower h eigh t, better th erm al tran sfer, an d lower p ower con su m p tion . Sp ecial sold er p lu gs on th e circu it board located d irectly u n d er th e p rocessor d raw h eat away an d p rovid e better coolin g in th e tigh t con fin es of a typ ical n otebook or lap top system —n o coolin g fan s are req u ired . For m ore in form ation on m obile p rocessors an d system s, see Ch ap ter 15, “Portable PCs.” Th e Pen tiu m , like th e 486, con tain s an in tern al m ath cop rocessor or FPU. Th e FPU in th e Pen tiu m h as been rewritten an d p erform s sign ifican tly better th an th e FPU in th e 486, yet it is fu lly com p atible with th e 486 an d 387 m ath cop rocessor. Th e Pen tiu m FPU is estim ated at 2 to as m u ch as 10 tim es faster th an th e FPU in th e 486. In ad d ition , th e two stan d ard in stru ction p ip elin es in th e Pen tiu m p rovid e two u n its to h an d le stan d ard in teger m ath . (Th e m ath cop rocessor h an d les on ly m ore com p lex calcu lation s.) Oth er p rocessors, su ch as th e 486, h ave on ly a sin gle-stan d ard execu tion p ip e an d on e in tegerm ath u n it. In terestin gly, th e Pen tiu m FPU con tain s a flaw th at received wid esp read p u blicity. See th e d iscu ssion in th e section “Pen tiu m Defects” later in th is ch ap ter. Fi rst -Ge n e ra t i o n P e n t i u m P ro c e sso r. Th e Pen tiu m h as been offered in th ree basic d esign s, each with several version s. Th e first-gen eration d esign , wh ich is n o lon ger available, cam e in 60 an d 66MHz p rocessor sp eed s. Th is d esign u sed a 273-p in PGA form factor an d ran on 5v p ower. In th is d esign , th e p rocessor ran at th e sam e sp eed as th e m oth erboard —in oth er word s, a 1x clock is u sed . Th e first-gen eration Pen tiu m was created th rou gh an 0.8-m icron BiCMOS p rocess. Un fortu n ately, th is p rocess, com bin ed with th e 3.1 m illion tran sistor cou n t, resu lted in a d ie th at was overly large an d com p licated to m an u factu re. As a resu lt, red u ced yield s kep t th e ch ip in sh ort su p p ly; In tel cou ld n ot m ake th em fast en ou gh . Th e 0.8-m icron p rocess was criticized by oth er m an u factu rers, in clu d in g Motorola an d IBM, wh ich h ad been

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u sin g 0.6-m icron tech n ology for th eir m ost ad van ced ch ip s. Th e h u ge d ie an d 5v op eratin g voltage cau sed th e 66MHz version s to con su m e u p to an in cred ible 3.2 am p s or 16 watts of p ower, resu ltin g in a trem en d ou s am ou n t of h eat—an d p roblem s in som e system s th at d id n ot em p loy con servative d esign tech n iq u es. Fortu n ately, ad d in g a fan to th e p rocessor wou ld solve m ost coolin g p roblem s, as lon g as th e fan kep t ru n n in g. Mu ch of th e criticism leveled at In tel for th e first-gen eration Pen tiu m was ju stified . Som e p eop le realized th at th e first-gen eration d esign was ju st th at; th ey kn ew th at n ew Pen tiu m version s, m ad e in a m ore ad van ced m an u factu rin g p rocess, were com in g. Man y of th ose p eop le ad vised again st p u rch asin g an y Pen tiu m system u n til th e secon d gen eration version becam e available.

Tip A cardinal rule of computing is never to buy the first generation of any processor. Although you can wait forever because something better always will be on the horizon, a little waiting is worthwhile in some cases.

If you d o h ave on e of th ese first-gen eration Pen tiu m s, d o n ot d esp air. As with p reviou s 486 system s, In tel offers OverDrive u p grad e ch ip s th at effectively d ou ble th e p rocessor sp eed of you r Pen tiu m 60 or 66. Th ese are a sin gle-ch ip u p grad e, m ean in g th ey rep lace you r existin g CPU. Becau se su bseq u en t Pen tiu m s are in com p atible with th e Pen tiu m 60/ 66 Socket 4 arran gem en t, th ese OverDrive ch ip s were th e on ly way to u p grad e an existin g first-gen eration Pen tiu m with ou t rep lacin g th e m oth erboard . Rath er th an u p grad in g th e p rocessor with on e on ly twice as fast, you sh ou ld really con sid er a com p lete m oth erboard rep lacem en t, wh ich wou ld accep t a n ewer d esign p rocessor th at wou ld p oten tially be m an y tim es faster. Se c o n d -Ge n e ra t i o n P e n t i u m P ro c e sso r. In tel an n ou n ced th e secon d -gen eration Pen tiu m on March 7, 1994. Th is n ew p rocessor was in trod u ced in 90 an d 100MHz version s, with a 75MHz version n ot far beh in d . Even tu ally, 120, 133, 150, 166, an d 200MHz version s were also in trod u ced . Th e secon d -gen eration Pen tiu m u ses 0.6-m icron (75/ 90/ 100MHz) BiCMOS tech n ology to sh rin k th e d ie an d red u ce p ower con su m p tion . Th e n ewer, faster 120 MHz (an d h igh er) secon d -gen eration version s in corp orate an even sm aller d ie bu ilt on a 0.35-m icron BiCMOS p rocess. Th ese sm aller d ies are n ot ch an ged from th e 0.6-m icron version s; th ey are basically a p h otograp h ic red u ction of th e P54C d ie. Th e d ie for th e Pen tiu m is sh own in Figu re 3.21. Ad d ition ally, th ese n ew p rocessors ru n on 3.3v p ower. Th e 100MHz version con su m es a m axim u m 3.25 am p s of 3.3v p ower, wh ich eq u als on ly 10.725 watts. Fu rth er u p th e scale, th e 150MHz ch ip u ses 3.5 am p s of 3.3v p ower (11.6 watts); th e 166MHz u n it d raws 4.4 am p s (14.5 watts); an d th e 200MHz p rocessor u ses 4.7 am p s (15.5 watts). Th e secon d -gen eration Pen tiu m p rocessors com e in a 296-p in SPGA form factor th at is p h ysically in com p atible with th e first-gen eration version s. Th e on ly way to u p grad e from th e first gen eration to th e secon d is to rep lace th e m oth erboard . Th e secon d -gen eration

Processor Types

Pen tiu m p rocessors also h ave 3.3 m illion tran sistors—m ore th an th e earlier ch ip s. Th e extra tran sistors exist becau se ad d ition al clock-con trol SL en h an cem en ts were ad d ed , as were an on -ch ip Ad van ced Program m able In terru p t Con troller (APIC) an d d u al-p rocessor in terface. Th e APIC an d d u al-p rocessor in terface are resp on sible for orch estratin g d u al-p rocessor con figu ration s in wh ich two secon d -gen eration Pen tiu m ch ip s can p rocess on th e sam e m oth erboard sim u ltan eou sly. Man y of th e Pen tiu m m oth erboard s d esign ed for file servers com e with d u al Socket 7 sp ecification sockets, wh ich fu lly su p p ort th e m u ltip rocessin g cap ability of th e n ew ch ip s. Software su p p ort for wh at u su ally is called Sym m etric Mu lti-Processin g (SMP) is bein g in tegrated in to op eratin g system s su ch as W in d ows NT an d OS/ 2.

FIG. 3.21 Pen tiu m Processor d ie. Photograph used by perm ission of Intel Corporation. Th e secon d -gen eration Pen tiu m p rocessors u se clock-m u ltip lier circu itry to ru n th e p rocessor at sp eed s faster th an th e bu s. Th e 150MHz Pen tiu m p rocessor, for exam p le, can ru n at 2.5 tim es th e bu s freq u en cy, wh ich n orm ally is 60MHz. Th e 200MHz Pen tiu m p rocessor can ru n at a 3x clock in a system u sin g a 66MHz bu s sp eed .

Not e Some Pentium systems support 75M Hz or even up to 100M Hz with newer motherboard and chipset designs.

111

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Chapter 3—M icroprocessor Types and Specifications

Virtu ally all Pen tiu m m oth erboard s h ave th ree sp eed settin gs: 50, 60, an d 66MHz. Pen tiu m ch ip s are available with a variety of in tern al clock m u ltip liers th at cau se th e p rocessor to op erate at variou s m u ltip les of th ese m oth erboard sp eed s. Table 3.18 lists th e sp eed s of cu rren tly available Pen tiu m p rocessors an d m oth erboard s. Table 3.18

Pent ium CPU and M ot herboard Speeds

CPU Type/ Speed

CPU Clock

M ot herboard Speed

Pentium 75

1.5x

50

Pentium 90

1.5x

60

Pentium 100

1.5x

66

Pentium 120

2x

60

Pentium 133

2x

66

Pentium 150

2.5x

60

Pentium 166

2.5x

66

Pentium 200

3x

66

Pentium 233

3.5x

66

Pentium 266

4x

66

Th e Core-to-Bu s freq u en cy ratio or clock m u ltip lier is con trolled in a Pen tiu m p rocessor by two p in s on th e ch ip labeled BF1 an d BF2. Table 3.19 sh ows h ow th e state of th e BFx p in s will affect th e clock m u ltip lication in th e Pen tiu m p rocessor. Table 3.19

Pent ium BFx Pins and Clock M ult ipliers

BF1

BF2

Clock M ult iplier

Bus Speed ( M Hz)

Core Speed ( M Hz)

0

1

3x

66

200

0

1

3x

60

180

0

1

3x

50

150

0

0

2.5x

66

166

0

0

2.5x

60

150

0

0

2.5x

50

125

1

0

2x/ 4x

66

133/ 266*

1

0

2x

60

120

1

0

2x

50

100

1

1

1.5x/ 3.5x

66

100/ 233*

1

1

1.5x

60

90

1

1

1.5x

50

75

*The 233 and 266MHz processors have m odified the 1.5x and 2x m ultipliers to 3.5x and 4x, respectively.

Not all ch ip s su p p ort all th e Bu s Freq u en cy (BF) p in s or com bin ation s of settin gs. In oth er word s, som e of th e Pen tiu m p rocessors will op erate on ly at sp ecific com bin ation s of th ese settin gs, or m ay even be fixed at on e p articu lar settin g. Man y of th e n ewer

Processor Types

m oth erboard s h ave ju m p ers or switch es th at allow you to con trol th e BF p in s an d th erefore alter th e clock m u ltip lier ratio with in th e ch ip . In th eory, you cou ld ru n a 75MHzrated Pen tiu m ch ip at 133MHz by ch an gin g ju m p ers on th e m oth erboard . Th is is called overclocking, an d is d iscu ssed in th e “Processor Sp eed Ratin gs” section of th is ch ap ter. W h at In tel h as d on e to d iscou rage overclockers in its m ost recen t Pen tiu m s is d iscu ssed n ear th e en d of th e “Processor Man u factu rin g” section of th is ch ap ter. A sin gle-ch ip OverDrive u p grad e is cu rren tly offered for secon d -gen eration Pen tiu m s. Th ese OverDrive ch ip s are fixed at a 3x m u ltip lier; th ey rep lace th e existin g Socket 5 or 7 CPU, in crease p rocessor sp eed u p to 200MHz (with a 66MHz m oth erboard sp eed ), an d ad d MMX cap ability, as well. Sim p ly stated , th is m ean s th at a Pen tiu m 100, 133, or 166 system eq u ip p ed with th e OverDrive ch ip will h ave a p rocessor sp eed of 200MHz. Perh ap s th e best featu re of th ese Pen tiu m OverDrive ch ip s is th at th ey in corp orate MMX tech n ology. MMX p rovid es greatly en h an ced p erform an ce wh ile ru n n in g th e m u ltim ed ia ap p lication s th at are becom in g so p op u lar tod ay. If you h ave a Socket 7 m oth erboard , th en you m ay n ot n eed th e sp ecial OverDrive version s of th e Pen tiu m p rocessor th at h ave bu ilt-in voltage regu lators. In stead , you can p u rch ase a stan d ard Pen tiu m or Pen tiu m -com p atible ch ip an d sim p ly rep lace th e existin g p rocessor with it. You will h ave to be su re to set th e m u ltip lier an d voltage settin gs so th at th ey are correct for th e n ew p rocessor. Pent ium -M M X Processors. A th ird gen eration of Pen tiu m p rocessors (cod e-n am ed P55C) was released in Jan u ary 1997, wh ich in corp orates wh at In tel calls MMX technology in to th e secon d -gen eration Pen tiu m d esign . Th ese Pen tiu m -MMX p rocessors are available in clock rates of 66/ 166MHz, 66/ 200MHz, an d 66/ 233MHz, an d a m obile-on ly version , wh ich is 66/ 266MHz. Th e MMX p rocessors sh are m u ch in com m on with oth er secon d -gen eration Pen tiu m s, in clu d in g su p erscalar arch itectu re, m u ltip rocessor su p p ort, on -ch ip local APIC con troller, an d p ower-m an agem en t featu res. New featu res in clu d e a p ip elin ed MMX u n it, 16K cod e, W rite-Back cach e (versu s 8K in earlier Pen tiu m s), an d 4.5 m illion tran sistors. Pen tiu m -MMX ch ip s are p rod u ced on an en h an ced 0.35-m icron CMOS silicon p rocess th at allows for a lower 2.8v voltage level. Th e n ewer m obile 233MHz an d 266MHz p rocessors are bu ilt on a 0.25 m icron p rocess an d ru n on on ly 1.8 volts. W ith th is n ewer tech n ology, th e 266 p rocessor actu ally u ses less p ower th an th e n on -MMX 133. To u se th e Pen tiu m -MMX, th e m oth erboard m u st be able to su p p ly th e lower (2.8v or less) voltage th ese p rocessors u se. To allow a m ore u n iversal m oth erboard solu tion with resp ect to th ese ch an gin g voltages, In tel h as com e u p with th e Socket 7 with VRM. Th e VRM is a socketed m od u le th at p lu gs in n ext to th e p rocessor an d su p p lies th e correct voltage. Becau se th e m od u le is easily rep laced , it is easy to recon figu re a m oth erboard to su p p ort an y of th e voltages req u ired by th e n ewer Pen tiu m p rocessors. Of cou rse, lower voltage is n ice, bu t MMX is wh at th is ch ip is really all abou t. MMX tech n ology was d evelop ed by In tel as a d irect resp on se to th e growin g im p ortan ce an d in creasin g d em an d s of m u ltim ed ia an d com m u n ication ap p lication s. Man y su ch ap p lication s ru n rep etitive loop s of in stru ction s th at take vast am ou n ts of tim e to execu te. As a

113

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Chapter 3—M icroprocessor Types and Specifications

resu lt, MMX in corp orates a p rocess In tel calls Single Instruction Multiple Data (SIMD), wh ich allows on e in stru ction to p erform th e sam e fu n ction on m an y p ieces of d ata. Fu rth erm ore, 57 n ew in stru ction s th at are d esign ed sp ecifically to h an d le vid eo, au d io, an d grap h ics d ata h ave been ad d ed to th e ch ip . If you wan t m axim u m fu tu re u p grad ability to th e MMX Pen tiu m s, m ake su re th at you r Pen tiu m m oth erboard in clu d es 321-p in p rocessor sockets th at fu lly m eet th e In tel Socket 7 sp ecification . Th ese wou ld also in clu d e th e VRM (Voltage Regu lator Mod u le) socket. If you h ave d u al sockets, you can ad d a secon d Pen tiu m p rocessor to take ad van tage of SMP (Sym m etric Mu lti-Processin g) su p p ort in som e n ewer op eratin g system s. Also m ake su re th at an y Pen tiu m m oth erboard you bu y can be ju m p ered or recon figu red for both 60 an d 66MHz op eration . Th is will en able you to take ad van tage of fu tu re Pen tiu m OverDrive p rocessors th at will su p p ort th e h igh er m oth erboard clock sp eed s. Th ese sim p le recom m en d ation s will en able you to p erform several d ram atic u p grad es with ou t ch an gin g th e en tire m oth erboard . Pent ium Defect s. Probably th e m ost fam ou s p rocessor bu g in h istory is th e n ow legen d ary flaw in th e Pen tiu m FPU. It h as often been called th e FDIV bu g, becau se it affects p rim arily th e FDIV (Floatin g-Poin t Divid e) in stru ction , alth ou gh several oth er in stru ction s th at u se d ivision are also affected . In tel officially refers to th is p roblem as Errata No. 23, titled “Sligh t p recision loss for floatin g-p oin t d ivid es on sp ecific op eran d p airs.” Th e bu g h as been fixed in th e D1 or later step p in gs of th e 60/ 66MHz Pen tiu m p rocessors, as well as th e B5 an d later step p in gs of th e 75/ 90/ 100MHz p rocessors. Th e 120MHz an d h igh er p rocessors are m an u factu red from later step p in gs, wh ich d o n ot in clu d e th is p roblem . Th ere are tables listin g all th e d ifferen t variation s of Pen tiu m p rocessors an d step p in gs an d h ow to id en tify th em later in th is ch ap ter. Th is bu g cau sed a trem en d ou s fervor wh en it first was rep orted on th e In tern et by a m ath em atician in October, 1994. W ith in a few d ays, n ews of th e d efect h ad sp read n ation wid e, an d even p eop le wh o d id n ot h ave com p u ters h ad h eard abou t it. Th e Pen tiu m wou ld in correctly p erform floatin g-p oin t d ivision calcu lation s with certain n u m ber com bin ation s, with errors an ywh ere from th e th ird d igit on u p . By th e tim e th e bu g was p u blicly d iscovered ou tsid e of In tel, th ey h ad alread y in corp orated th e fix in to th e n ext step p in g of both th e 60/ 66MHz an d th e 75/ 90/ 100MHz Pen tiu m p rocessor, alon g with th e oth er correction s th ey h ad m ad e. After th e bu g was m ad e p u blic an d In tel ad m itted to alread y kn owin g abou t it, a fu ry eru p ted . As p eop le began ch eckin g th eir sp read sh eets an d oth er m ath calcu lation s, m an y d iscovered th at th ey h ad also en cou n tered th is p roblem an d d id n ot kn ow it. Oth ers wh o h ad n ot en cou n tered th e p roblem h ad th eir faith in th e core of th eir PCs very sh aken . Peop le h ad com e to p u t so m u ch tru st in th e PC th at th ey h ad a h ard tim e com in g to term s with th e fact th at it m igh t n ot even be able to d o m ath correctly! On e in terestin g resu lt of th e fervor su rrou n d in g th is d efect is th at p eop le are less likely to im p licitly tru st th eir PCs, an d are th erefore d oin g m ore testin g an d evalu atin g of im p ortan t resu lts. Th e bottom lin e is th at if you r in form ation an d calcu lation s are im p ortan t en ou gh , you sh ou ld im p lem en t som e resu lts tests. In lookin g for p roblem s with m ath ,

Processor Types

several p rogram s were fou n d to h ave p roblem s. For exam p le, a bu g was d iscovered in th e yield fu n ction of Excel 5.0 th at som e were attribu tin g to th e Pen tiu m p rocessor. In th is case, th e p roblem tu rn ed ou t to be th e software, wh ich h as been corrected in later version s (5.0c an d later). In tel fin ally d ecid ed th at in th e best in terest of th e con su m er an d th eir p u blic im age, th ey wou ld begin a lifetim e rep lacem en t warran ty on th e affected p rocessors. Th is m ean s th at if you ever en cou n ter on e of th e Pen tiu m p rocessors with th e Errata 23 Floatin gPoin t bu g, th ey will rep lace th e p rocessor with an eq u ivalen t on e with ou t th is p roblem . Norm ally, all you h ave to d o is call In tel an d ask for th e rep lacem en t. Th ey will sh ip you a n ew p art m atch in g th e ratin gs of th e on e you are rep lacin g in an overn igh t sh ip p in g box. Th e rep lacem en t is free, in clu d in g all sh ip p in g ch arges. You m erely rem ove you r old p rocessor, rep lace it with th e n ew on e, an d p u t th e old on e back in th e box. Th en you call th e overn igh t service wh o will p ick it u p an d sen d it back. In tel will take a cred it card n u m ber wh en you first call for th e rep lacem en t on ly to en su re th at th e origin al d efective ch ip is retu rn ed . As lon g as th ey get th e origin al CPU back with in a sp ecified am ou n t of tim e, th ere will be n o ch arges to you . In tel h as in d icated th at th ese d efective p rocessors will be d estroyed an d will n ot be rem arketed or resold in an oth er form . Te st i n g f o r t h e FP U Bu g . Testin g a Pen tiu m for th is bu g is relatively easy. All you h ave to d o is execu te on e of th e test d ivision cases cited h ere an d see if you r an swer com p ares to th e correct resu lt. Th e d ivision calcu lation can be d on e in a sp read sh eet (su ch as Lotu s 123, Microsoft Excel, or an y oth er), in th e Microsoft W in d ows bu ilt-in calcu lator, or in an y oth er calcu latin g p rogram th at u ses th e FPU. Make su re th at for th e p u rp oses of th is test th e FPU h as n ot been d isabled . Th at wou ld n orm ally req u ire som e sp ecial com m an d or settin g sp ecific to th e ap p lication , an d wou ld , of cou rse, en su re th at th e test cam e ou t correct, n o m atter wh eth er th e ch ip is flawed or n ot. Th e m ost severe Pen tiu m floatin g-p oin t errors occu r as early as th e th ird sign ifican t d igit of th e resu lt. Here is an exam p le of on e of th e m ore severe in stan ces of th e p roblem : 962,306,957,033 / 11,010,046 = 87,402.6282027341 (correct an swer) 962,306,957,033 / 11,010,046 = 87,399.5805831329 (flawed Pen tiu m ) Note th at you r p articu lar calcu lator p rogram m ay n ot sh ow th e an swer to th e n u m ber of d igits sh own h ere. Most sp read sh eet p rogram s lim it d isp layed resu lts to 13 or 15 sign ifican t d igits. As you can see, in th e p reviou s case th e error tu rn s u p in th e th ird m ost sign ifican t d igit of th e resu lt. In an exam in ation of over 5,000 in teger p airs in th e 5- to 15-d igit ran ge fou n d to p rod u ce Pen tiu m floatin g-p oin t d ivision errors, errors begin n in g in th e sixth sign ifican t d igit were th e m ost likely to occu r. Here is an oth er d ivision p roblem th at will com e ou t in correctly on a Pen tiu m with th is flaw:

115

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Chapter 3—M icroprocessor Types and Specifications

4,195,835 / 3,145,727 = 1.33382044913624100 (correct an swer) 4,195,835 / 3,145,727 = 1.33373906890203759 (flawed Pen tiu m ) Th is on e sh ows an error in th e fifth sign ifican t d igit. A variation on th e p reviou s calcu lation can be p erform ed as follows: x = 4,195,835 y = 3,145,727 z = x – (x/ y)*y 4,195,835 – (4,195,835 / 3,145,727) * 3,145,727 = 0 (correct an swer) 4,195,835 – (4,195,835 / 3,145,727) * 3,145,727 = 256 (flawed Pen tiu m ) W ith an exact com p u tation , th e an swer h ere sh ou ld be zero. In fact, you will get zero on m ost m ach in es, in clu d in g th ose u sin g In tel 286, 386, an d 486 ch ip s. Bu t, on th e Pen tiu m , th e an swer is 256! Here is on e m ore calcu lation you can try: 5,505,001 / 294,911 = 18.66665197 (correct an swer) 5,505,001 / 294,911 = 18.66600093 (flawed Pen tiu m ) Th is on e rep resen ts an error in th e sixth sign ifican t d igit. Th ere are several workarou n d s for th is bu g, bu t th ey extract a p erform an ce p en alty. Becau se In tel h as agreed to rep lace an y Pen tiu m p rocessor with th is flaw u n d er a lifetim e warran ty rep lacem en t p rogram , th e best workarou n d is a free rep lacem en t! P o w e r Ma n a g e m e n t Bu g s. Startin g with th e secon d -gen eration Pen tiu m p rocessors, In tel ad d ed fu n ction s th at allow th ese CPUs to be in stalled in en ergy-efficien t system s. Th ese are u su ally called En ergy Star system s becau se th ey m eet th e sp ecification s im p osed by th e EPA En ergy Star p rogram , bu t th ey are also u n officially called “Green PCs” by m an y u sers. Un fortu n ately, th ere h ave been several bu gs with resp ect to th ese fu n ction s, cau sin g th em to eith er fail or be d isabled . Th ese bu gs are in som e of th e fu n ction s in th e p owerm an agem en t cap abilities accessed th rou gh SMM. Th ese p roblem s are ap p licable on ly to th e secon d -gen eration 75/ 90/ 100MHz p rocessors. Th at’s becau se th e first-gen eration 60/ 66MHz p rocessors d o n ot h ave SMM or p ower-m an agem en t cap abilities, an d all h igh er-sp eed (120MHz an d u p ) p rocessors h ave th e bu gs fixed . Most of th e p roblem s are related to th e STPCLK# p in an d th e HALT in stru ction . If th is con d ition is in voked by th e ch ip set, th e system will h an g. For m ost system s, th e on ly workarou n d for th is p roblem is to sim p ly d isable th e p ower-savin g m od es, su ch as su sp en d or sleep . Un fortu n ately, th is m ean s th at you r green PC won ’t be so green an ym ore! Th e best way to rep air th e p roblem is to rep lace th e p rocessor with a later step p in g

Processor Types

version th at d oes n ot h ave th e bu g. Th ese bu gs affect th e B1 step p in g version of th e 75/ 90/ 100MHz Pen tiu m s, an d were fixed in th e B3 an d later step p in g version s. Pent ium Processor M odels and St eppings. W e kn ow th at like software, n o p rocessor is tru ly ever p erfect. From tim e to tim e, th e m an u factu rers will gath er u p wh at p roblem s th ey h ave fou n d an d p u t in to p rod u ction a n ew stepping, wh ich con sists of a n ew set of m asks th at in corp orate th e correction s. Each su bseq u en t step p in g is better an d m ore refin ed th an th e p reviou s on es. Alth ou gh n o m icrop rocessor is ever p erfect, th ey com e closer to p erfection with each step p in g. In th e life of a typ ical m icrop rocessor, a m an u factu rer m ay go th rou gh h alf a d ozen or m ore su ch step p in gs. Table 3.20 sh ows all th e version s of th e Pen tiu m p rocessor Mod el 1 (60/ 66MHz version ) in d icatin g th e variou s step p in gs th at h ave been available. Table 3.20

Pent ium Processor M odel 1 ( 60/ 66M Hz Version) St eppings

Type

Fam ily

M odel

St epping

M fg. St epping Speed

Com m ent s Specificat ion Num ber

0

5

1

3

B1

50

Q0399

0

5

1

3

B1

60

Q0352

0

5

1

3

B1

60

Q0400

ES

0

5

1

3

B1

60

Q0394

ES,HS

0

5

1

3

B1

66

Q0353

5v1

0

5

1

3

B1

66

Q0395

ES,HS,5v1

0

5

1

3

B1

60

Q0412

0

5

1

3

B1

60

SX753

0

5

1

3

B1

66

Q0413

0

5

1

3

B1

66

SX754

5v2

0

5

1

5

C1

60

Q0466

HS

0

5

1

5

C1

60

SX835

HS

0

5

1

5

C1

60

SZ949

HS,BOX

0

5

1

5

C1

66

Q0467

HS,5v2

0

5

1

5

C1

66

SX837

HS,5v2

0

5

1

5

C1

66

SZ950

HS,BOX,5v2

0

5

1

7

D1

60

Q0625

HS

0

5

1

7

D1

60

SX948

HS

0

5

1

7

D1

60

SX974

HS,5v3

0

5

1

7

D1

60

-*

HS,BOX

0

5

1

7

D1

66

Q0626

HS,5v2

0

5

1

7

D1

66

SX950

HS,5v2

0

5

1

7

D1

66

Q0627

HS,5v3

0

5

1

7

D1

66

SX949

HS,5v3

0

5

1

7

D1

66

-*

HS,BOX,5v2

ES

5v2

117

118

Chapter 3—M icroprocessor Types and Specifications

Tables 3.21, 3.22, 3.23, an d 3.24 sh ow all th e d ifferen t variation s of Pen tiu m 75/ 90/ 100/ 120/ 133/ 150/ 166/ 200/ 233/ 266MHz, classic, an d MMX p rocessors. Table 3.21 lists classic (n on -MMX) d esktop m od els. Table 3.22 lists MMX d esktop m od els. Exp lan ation s of all th e sp ecification s an d th e com m en ts in th e com m en ts colu m n follow Table 3.23, th e listin g of Pen tiu m OverDrive m od els. Table 3.21

Pent ium Processor Versions and St eppings

Type

Fam ily M odel St epping

Core St epping

Speed ( M Hz) Core-Bus

S-Spec

Com m ent s

0

5

2

1

B1

75-50

Q0540

ES

2

5

2

1

B1

75-50

Q0541

ES

0

5

2

1

B1

90-60

Q0542

STD

0

5

2

1

B1

90-60

Q0613

VR

2

5

2

1

B1

90-60

Q0543

DP

0

5

2

1

B1

100-66

Q0563

STD

0

5

2

1

B1

100-66

Q0587

VR

0

5

2

1

B1

100-66

Q0614

VR

0

5

2

1

B1

90-60

SX879

STD

0

5

2

1

B1

90-60

SX885

STD, M D

0

5

2

1

B1

90-60

SX909

VR

2

5

2

1

B1

90-60

SX874

DP,STD

0

5

2

1

B1

100-66

SX886

STD, M D

0

5

2

1

B1

100-66

SX910

VR, M D

0

5

2

2

B3

90-60

Q0628

STD

0/ 2

5

2

2

B3

90-60

Q0611

STD

0/ 2

5

2

2

B3

90-60

Q0612

VR

0

5

2

2

B3

100-66

Q0677

VRE

0

5

2

2

B3

90-60

SX923

STD

0

5

2

2

B3

90-60

SX922

VR

0

5

2

2

B3

90-60

SX921

STD

2

5

2

2

B3

90-60

SX942

DP,STD DP,VR

2

5

2

2

B3

90-60

SX943

2

5

2

2

B3

90-60

SX944

DP,M D

0

5

2

2

B3

90-60

SZ951

BOX,STD

0

5

2

2

B3

100-66

SX960

VRE, M D

0/ 2

5

2

4

B5

75-50

Q0666

STD

0/ 2

5

2

4

B5

90-60

Q0653

STD

0/ 2

5

2

4

B5

90-60

Q0654

VR

0/ 2

5

2

4

B5

90-60

Q0655

STD, M D

0/ 2

5

2

4

B5

100-66

Q0656

STD, M D

0/ 2

5

2

4

B5

100-66

Q0657

VR, M D

Processor Types

Type

Fam ily M odel St epping

Core St epping

Speed ( M Hz) Core-Bus

0/ 2

5

2

4

B5

100-66

Q0658

VRE, M D

0

5

2

4

B5

120-60

Q0707

VRE

S-Spec

Com m ent s

0

5

2

4

B5

120-60

Q0708

STD

0/ 2

5

2

4

B5

75-50

SX961

STD

0/ 2

5

2

4

B5

75-50

SZ977

BOX,STD

0/ 2

5

2

4

B5

90-60

SX957

STD

0/ 2

5

2

4

B5

90-60

SX958

VR

0/ 2

5

2

4

B5

90-60

SX959

STD, M D

0/ 2

5

2

4

B5

90-60

SZ978

BOX,STD

0/ 2

5

2

4

B5

100-66

SX962

VRE, M D

0/ 2

5

2

5

C2

75-50

Q0700

STD

0/ 2

5

2

5

C2

75-50

Q0749

STD, M D

0/ 2

5

2

5

C2

90-60

Q0699

STD

0/ 2

5

2

5

C2

100-50/ 66

Q0698

VRE, M D

0/ 2

5

2

5

C2

100-50/ 66

Q0697

STD

0

5

2

5

C2

120-60

Q0711

VRE, M D

0

5

2

5

C2

120-60

Q0732

VRE, M D

0

5

2

5

C2

133-66

Q0733

STD, M D

0

5

2

5

C2

133-66

Q0751

STD, M D

0

5

2

5

C2

133-66

Q0775

VRE, M D

0/ 2

5

2

5

C2

75-50

SX969

STD

0/ 2

5

2

5

C2

75-50

SX998

STD, M D

0/ 2

5

2

5

C2

75-50

SZ994

BOX,STD

0/ 2

5

2

5

C2

75-50

SU070

BOXF,STD

0/ 2

5

2

5

C2

90-60

SX968

STD

0/ 2

5

2

5

C2

90-60

SZ995

BOX,STD

0/ 2

5

2

5

C2

90-60

SU031

BOXF,STD

0/ 2

5

2

5

C2

100-50/ 66

SX970

VRE, M D

0/ 2

5

2

5

C2

100-50/ 66

SX963

STD

0/ 2

5

2

5

C2

100-50/ 66

SZ996

BOX,STD

0/ 2

5

2

5

C2

100-50/ 66

SU032

BOXF,STD

0

5

2

5

C2

120-60

SK086

VRE, M D

0

5

2

5

C2

120-60

SX994

VRE, M D

0

5

2

5

C2

120-60

SU033

BOXF,VRE, M D

0

5

2

5

C2

133-66

SK098

STD, M D

0/ 2

5

2

B

cB1

120-60

Q0776

STD,No,STP

0/ 2

5

2

B

cB1

133-66

Q0772

STD,No,STP

0/ 2

5

2

B

cB1

133-66

Q0773

STD,STP (continues)

119

120

Chapter 3—M icroprocessor Types and Specifications

Table 3.21

Pent ium Processor Versions and St eppings Cont inued

Type

Fam ily M odel St epping

Core St epping

Speed ( M Hz) Core-Bus

S-Spec

Com m ent s

0/ 2

5

2

B

cB1

133-66

Q0774

VRE,No,STP, MD

0/ 2

5

2

B

cB1

120-60

SK110

STD,No,STP

0/ 2

5

2

B

cB1

133-66

SK106

STD,No,STP

0/ 2

5

2

B

cB1

133-66

S106J

STD,No,STP

0/ 2

5

2

B

cB1

133-66

SK107

STD,STP

0/ 2

5

2

B

cB1

133-66

SU038

BOXF,STD, No,STP

0/ 2

5

2

C

cC0

133-66

Q0843

STD,No

0/ 2

5

2

C

cC0

133-66

Q0844

STD

0/ 2

5

2

C

cC0

150-60

Q0835

STD

0/ 2

5

2

C

cC0

150-60

Q0878

STD,PPGA

0/ 2

5

2

C

cC0

150-60

SU122

BOXF,STD

0/ 2

5

2

C

cC0

166-66

Q0836

VRE,No

0/ 2

5

2

C

cC0

166-66

Q0841

VRE

0/ 2

5

2

C

cC0

166-66

Q0886

VRE,PPGA

0/ 2

5

2

C

cC0

166-66

Q0890

VRE,PPGA

0

5

2

C

cC0

166-66

Q0949

VRE,PPGA

0/ 2

5

2

C

cC0

200-66

Q0951F

VRE,PPGA

0

5

2

C

cC0

200-66

Q0951

VRE,PPGA

0

5

2

C

cC0

200-66

SL25H

BOXF,VRE, PPGA

0/ 2

5

2

C

cC0

120-60

SL22M

BOXF,STD

0/ 2

5

2

C

cC0

120-60

SL25J

BOX,STD

0/ 2

5

2

C

cC0

120-60

SY062

STD

0/ 2

5

2

C

cC0

133-66

SL22Q

BOXF,STD

0/ 2

5

2

C

cC0

133-66

SL25L

BOX,STD

0/ 2

5

2

C

cC0

133-66

SY022

STD

0/ 2

5

2

C

cC0

133-66

SY023

STD,No

0/ 2

5

2

C

cC0

133-66

SU073

BOXF,STD,No

0/ 2

5

2

C

cC0

150-60

SY015

STD

0/ 2

5

2

C

cC0

150-60

SU071

BOXF,STD

0/ 2

5

2

C

cC0

166-66

SL24R

VRE,No,M AXF

0/ 2

5

2

C

cC0

166-66

SY016

VRE,No

0/ 2

5

2

C

cC0

166-66

SY017

VRE

0/ 2

5

2

C

cC0

166-66

SU072

BOXF,VRE,No

0

5

2

C

cC0

166-66

SY037

VRE,PPGA

0/ 2

5

2

C

cC0

200-66

SY044

VRE,PPGA

Processor Types

Type

Fam ily M odel St epping

Core St epping

Speed ( M Hz) Core-Bus

S-Spec

Com m ent s

0

5

2

C

cC0

200-66

SY045

BOXUF,VRE, PPGA

0

5

2

C

cC0

200-66

SU114

BOX,VRE, PPGA

0

5

2

C

cC0

200-66

SL24Q

VRE,PPGA,No, M AXF

0/ 2

5

2

6

E0

75-50

Q0837

STD

0/ 2

5

2

6

E0

90-60

Q0783

STD

0/ 2

5

2

6

E0

100-50/ 66

Q0784

STD

0/ 2

5

2

6

E0

120-60

Q0785

VRE

0/ 2

5

2

6

E0

75-50

SY005

STD

0/ 2

5

2

6

E0

75-50

SU097

BOX,STD

0/ 2

5

2

6

E0

75-50

SU098

BOXF,STD

0/ 2

5

2

6

E0

90-60

SY006

STD

0/ 2

5

2

6

E0

100-50/ 66

SY007

STD

0/ 2

5

2

6

E0

100-50/ 66

SU110

BOX,STD

0/ 2

5

2

6

E0

100-50/ 66

SU099

BOXF,STD

0/ 2

5

2

6

E0

120-60

SY033

STD

0/ 2

5

2

6

E0

120-60

SU100

BOXF,STD

Table 3.22

Pent ium M M X Processor Versions and St eppings

Type

Fam ily M odel St epping

Core St epping

Core Speed ( M Hz)

S-Spec

Com m ent s

0/ 2

5

4

4

xA3

150

Q020

ES,PPGA

0/ 2

5

4

4

xA3

166

Q019

ES,PPGA

0/ 2

5

4

4

xA3

200

Q018

ES,PPGA

0/ 2

5

4

4

xA3

166

SL23T

BOXF,SPGA

0/ 2

5

4

4

xA3

166

SL23R

BOX,PPGA

0/ 2

5

4

4

xA3

166

SL25M

BOXF,PPGA

0/ 2

5

4

4

xA3

166

SY059

PPGA

0/ 2

5

4

4

xA3

166

SL2HU

BOX,SPGA

0/ 2

5

4

4

xA3

166

SL239

SPGA

0/ 2

5

4

4

xA3

166

SL26V

SPGA,M AXF

0/ 2

5

4

4

xA3

166

SL26H

PPGA,M AXF

0/ 2

5

4

4

xA3

200

SL26J

BOXUF,PPGA, M AXF

0/ 2

5

4

4

xA3

200

SY060

PPGA (continues)

121

122

Chapter 3—M icroprocessor Types and Specifications

Table 3.22

Pent ium M M X Processor Versions and St eppings Cont inued

Type

Fam ily M odel St epping

Core St epping

Core Speed ( M Hz)

S-Spec

Com m ent s

0/ 2

5

4

4

xA3

200

SL26Q

BOX,PPGA, M AXF

0/ 2

5

4

4

xA3

200

SL274

BOXF,PPGA, M AXF

0/ 2

5

4

4

xA3

200

SL23S

BOX,PPGA

0/ 2

5

4

4

xA3

200

SL25N

BOXF,PPGA

0/ 2

5

4

3

xB1

166

Q125

ES,PPGA

0/ 2

5

4

3

xB1

166

Q126

ES,SPGA

0/ 2

5

4

3

xB1

200

Q124

ES,PPGA

0/ 2

5

4

3

xB1

233

Q140

ES,PPGA

0/ 2

5

4

3

xB1

166

SL27H

PPGA

0/ 2

5

4

3

xB1

166

SL27K

SPGA

0/ 2

5

4

3

xB1

166

SL2HX

BOX,SPGA

0/ 2

5

4

3

xB1

166

SL23X

BOXF,SPGA

0/ 2

5

4

3

xB1

166

SL2FP

BOX,PPGA

0/ 2

5

4

3

xB1

166

SL23V

BOXF,PPGA

0/ 2

5

4

3

xB1

200

SL27J

PPGA

0/ 2

5

4

3

xB1

200

SL2FQ

BOX,PPGA

0/ 2

5

4

3

xB1

200

SL23W

BOXF,PPGA

0/ 2

5

4

3

xB1

233

SL27S

PPGA

0/ 2

5

4

3

xB1

233

SL2BM

BOX,PPGA

0/ 2

5

4

3

xB1

233

SL293

BOXF,PPGA

All the Pentium MMX Processors listed in the table run on a 66MHz bus except for m odel that runs on a 60MHz bus.

Table 3.23 sh ows all th e version s of th e Pen tiu m OverDrive p rocessors, in d icatin g th e variou s step p in gs th at h ave been available. Note th at th e Typ e 1 ch ip s in th is table are 486 Pen tiu m OverDrive p rocessors, wh ich are d esign ed to rep lace 486 ch ip s in system s with Socket 2 or 3. Th e oth er OverDrive p rocessors are d esign ed to rep lace existin g Pen tiu m p rocessors in Socket 4 or 5/ 7. Table 3.23

Pent ium OverDrive St eppings

M fg. Type Fam ily M odel St epping St epping Speed

Spec. Num ber Product

Version

1

5

3

1

B1

63

SZ953

PODP5v63

1.0

1

5

3

1

B2

63

SZ990

PODP5v63

1.1

1

5

3

2

C0

83

SU014

PODP5v83

2.1

0

5

1

A

tA0

133

SU082

PODP5v133

1.0

Processor Types

M fg. Type Fam ily M odel St epping St epping Speed

Spec. Num ber Product

Version

0

5

2

C

aC0

125

SU081

PODP3v125

1.0

0

5

2

C

aC0

150

SU083

PODP3v150

1.0

0

5

2

C

aC0

166

SU084

PODP3v166

1.0

1

5

4

4

oxA3

125/ 50, SL24V 150/ 60

PODPM T60X150 1.0

1

5

4

4

oxA3

166/ 66

SL24W

PODPM T66X166 1.0

1

5

4

3

oxB1

180/ 60

SL2FE

PODPM T60X180 2.0

1

5

4

3

oxB1

200/ 66

SL2FF

PODPM T66X200 2.0

Th e followin g list exp lain s all th e en tries in th e Com m en ts colu m n s of th ese tables. ES = En gin eerin g Sam p le. Th ese ch ip s were n ot sold th rou gh n orm al ch an n els bu t were d esign ed for d evelop m en t an d testin g p u rp oses. HS = Heat Sp read er Package. Th is in d icates a ch ip with a m etal p late on th e top , wh ich is u sed to sp read h eat away from th e cen ter p art of th e ch ip . Th e h eat sp read er h elp s th e ch ip ru n cooler; h owever, m ost later ch ip s u se a sm aller, m ore p owerfu l, m ore efficien t d ie, an d In tel h as been able to elim in ate th e h eat sp read er from th ese. DP = Du al Processor version wh ere Typ e 0 is Prim ary on ly, Typ e 2 is Secon d ary on ly, an d Typ e 0 or 2 is eith er. MD = Min im u m Delay tim in g restriction s on several p rocessor sign als. STD = Stan d ard voltage ran ge. Th e ran ge for th e C2 an d su bseq u en t step p in gs of th e Pen tiu m p rocessor is 3.135V to 3.6V. Th e voltage ran ge for B-step p arts rem ain s at 3.135V–3.465V. Note th at all E0-step p rod u ction p arts are stan d ard voltage. VR = Voltage Red u ced (3.300v to 3.465v). VRE = VR an d Exten d ed (3.45v to 3.60v). VRT = Voltage Red u ction Tech n ology. TCP = Tap e Carrier Package. BOX = A retail boxed p rocessor with a stan d ard p assive h eat sin k. BOXF = A retail boxed p rocessor with an active (fan -cooled ) h eat sin k. Th e absen ce of a p ackage typ e in th e com m en ts colu m n m ean s th e p rocessor is SPGA by d efau lt. 2.285v = Th is is a m obile Pen tiu m p rocessor with MMX tech n ology with a core op eratin g voltage of 2.285v – 2.665v. MAXF = Th e p art m ay ru n on ly at th e m axim u m sp ecified freq u en cy. Sp ecifically, a 200-MHz m ay be ru n at 200MHz +0/ –5 MHz (195 – 200MHz) an d a 166-MHz m ay be ru n at 166MHz +0/ –5MHz (161 – 166MHz).

123

124

Chapter 3—M icroprocessor Types and Specifications

BOXUF = Th is p art also sh ip s as a boxed p rocessor with an u n attach ed fan h eat sin k. 1.8v = Th is is a m obile Pen tiu m p rocessor with MMX tech n ology with a core op eratin g voltage of 1.665v – 1.935v an d an I/ O op eratin g voltage of 2.375v – 2.625v. 2.2v = Th is is a m obile Pen tiu m p rocessor with MMX tech n ology with a core op eratin g voltage of 2.10v – 2.34v. 2.0v = Th is is a m obile Pen tiu m Processor with MMX tech n ology with a core op eratin g voltage of 1.850v – 2.150v an d an I/ O op eratin g voltage of 2.375v – 2.625v. STP = Th e cB1 step p in g is logically eq u ivalen t to th e C2-step , bu t on a d ifferen t m an u factu rin g p rocess. Th e m cB1 step is logically eq u ivalen t to th e cB1 step (excep t it d oes n ot su p p ort DP, APIC, or FRC). Th e m cB1, m A1, m A4, an d m cC0-step s also u se In tel’s VRT (Voltage Red u ction Tech n ology), an d are available in th e TCP an d / or SPGA p ackage, p rim arily to su p p ort m obile ap p lication s. Th e m xA3 is logically eq u ivalen t to th e xA3 step p in g (excep t it d oes n ot su p p ort DP or APIC). NO = Mean s th at p art m eets th e sp ecification s bu t is n ot tested to su p p ort 82498/ 82493 an d 82497/ 82492 cach e tim in gs. * = Th ese ch ip s h ave n o Sp ecification n u m ber. In th ese tables, th e p rocessor Typ e h ead in g refers to th e d u al p rocessor cap abilities of th e Pen tiu m . Version s in d icated with a Typ e 0 can be u sed on ly as a p rim ary p rocessor, wh ile th ose m arked as Typ e 2 can be u sed on ly as th e secon d ary p rocessor in a p air. If th e p rocessor is m arked as Typ e 0/ 2, it can serve as th e p rim ary or secon d ary p rocessor, or both . Th e Fam ily d esign ation for all Pen tiu m s is 5 (for 586), wh ile th e m od el in d icates th e p articu lar revision . Mod el 1 in d icates th e first-gen eration 60/ 66MHz version , wh ile Mod el 2 or later in d icates th e secon d -gen eration 75+MHz version . Th e step p in g n u m ber is th e actu al revision of th e p articu lar m od el. Th e fam ily, m od el, an d step p in g n u m ber can be read by software su ch as th e In tel CPUID p rogram . Th ese also corresp on d to a p articu lar Man u factu rer Step p in g cod e, wh ich is h ow In tel d esign ates th e ch ip s in -h ou se. Th ese are u su ally an alp h an u m eric cod e. For exam p le, step p in g 5 of th e Mod el 2 Pen tiu m is also kn own as th e C2 step p in g in sid e In tel. Man u factu rin g step p in g cod es th at begin with an m in d icate a m obile p rocessor. Most Pen tiu m p rocessors com e in a stan d ard Ceram ic Pin Grid Array (CPGA) p ackage; h owever, th e m obile p rocessors also u se th e Tap e Carrier Package (TCP). Now th ere is also a Plastic Pin Grid Array (PPGA) p ackage bein g u sed to red u ce cost. To d eterm in e th e sp ecification s of a given p rocessor, you n eed to look u p th e S-sp ec n u m ber in th e table of p rocessor sp ecification s. To fin d you r S-sp ec n u m ber, you h ave to read it off of th e ch ip d irectly. It can be fou n d p rin ted on both th e top an d bottom of th e ch ip . If you r h eat sin k is glu ed on , rem ove th e ch ip an d h eat sin k from th e socket as a u n it an d read th e n u m bers from th e bottom of th e ch ip . Th en you can look u p th e S-sp ec n u m ber in th e table; it will tell you th e sp ecification s of th at p articu lar p rocessor.

Processor Types

In tel is in trod u cin g n ew ch ip s all th e tim e, so visit th eir W eb site an d search for th e Pen tiu m p rocessor “Qu ick Referen ce Gu id e” in th e d evelop er p ortion of th eir site. Th ere you will fin d a com p lete listin g of all cu rren t p rocessor sp ecification s by S-sp ec n u m ber. On e in terestin g item to n ote is th at th ere are several su btly d ifferen t voltages req u ired by d ifferen t Pen tiu m p rocessors. Table 3.24 su m m arizes th e d ifferen t p rocessors an d th eir req u ired voltages: Table 3.24

Pent ium Processor Volt ages

M odel

St epping

Volt age spec.

Volt age range

1

-

Std.

4.75–5.25v

1

-

5v1

4.90–5.25v

1

-

5v2

4.90–5.40v

1

-

5v3

5.15–5.40v

2+

B1-B5

Std.

3.135–3.465v

2+

C2+

Std.

3.135–3.600v

2+

-

VR

3.300–3.465v

2+

B1-B5

VRE

3.45–3.60v

2+

C2+

VRE

3.40–3.60v

4+

-

MMX

2.70–2.90v

4

3

M obile

2.285–2.665v

4

3

M obile

2.10–2.34v

8

1

M obile

1.850–2.150v

8

1

M obile

1.665–1.935v

Man y of th e n ewer Pen tiu m m oth erboard s h ave ju m p ers th at allow for ad ju stm en ts to th e d ifferen t voltage ran ges. If you are h avin g p roblem s with a p articu lar p rocessor, it m ay n ot be m atch ed correctly to you r m oth erboard voltage ou tp u t. If you are p u rch asin g an old er, u sed Pen tiu m system tod ay, I wou ld recom m en d u sin g on ly Mod el 2 (secon d gen eration ) or later version p rocessors th at are available in 75MHz or faster sp eed s. I wou ld d efin itely wan t step p in g C2 or later. Virtu ally all th e im p ortan t bu gs an d p roblem s were fixed in th e C2 an d later releases. Th e n ewer Pen tiu m p rocessors h ave n o seriou s bu gs to worry abou t. AM D-K5. Th e AMD-K5 is a Pen tiu m -com p atible p rocessor d evelop ed by AMD an d available as th e PR75, PR90, PR100, PR120, PR133, an d PR-166. Becau se it is d esign ed to be p h ysically an d fu n ction ally com p atible, an y m oth erboard th at p rop erly su p p orts th e In tel Pen tiu m sh ou ld su p p ort th e AMD-K5. However, a BIOS u p grad e m ay be req u ired to p rop erly recogn ize th e AMD-K5. AMD keep s a list of m oth erboard s th at h ave been tested for com p atibility. Th e K5 h as th e followin g ad van ced featu res: ■ 16K in stru ction cach e, 8K write-back d ata cach e

125

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■ Dyn am ic execu tion —bran ch p red iction with sp ecu lative execu tion ■ 5-stage RISC-like p ip elin e with 6 p arallel fu n ction al u n its ■ High -p erform an ce Floatin g-Poin t Un it ■ Pin -selectable clock m u ltip les of 1.5x an d 2x Th e K5 is sold u n d er th e P-ratin g system , wh ich m ean s th at th e n u m ber on th e ch ip d oes n ot in d icate tru e clock sp eed , on ly ap p aren t sp eed wh en ru n n in g certain ap p lication s. Th e actu al bu s sp eed an d clock m u ltip lier breakd own s are as follows: P-Rat ing

Clock

M ult iplier

True CPU speed

PR-75

50M Hz

1.5x

75M Hz

PR-90

60M Hz

1.5x

90M Hz

PR-100

66M Hz

1.5x

100M Hz

PR-120

60M Hz

1.5x

90M Hz

PR-133

66M Hz

1.5x

100M Hz

PR-166

66M Hz

1.75x

117M Hz

Not e The 1.75 multiplier setting is achieved by setting the motherboard for 2.5.

Note th at several of th ese p rocessors d o n ot ru n at th eir ap p aren t rated sp eed . For exam p le, th e PR-166 version actu ally ru n s at on ly 117 tru e MHz. Som etim es th is can con fu se th e system BIOS, wh ich m ay rep ort th e tru e sp eed rath er th an th e P-ratin g, wh ich com p ares th e ch ip again st an In tel Pen tiu m of th at sp eed . AMD claim s th at d u e to arch itectu re en h an cem en ts over th e Pen tiu m , th ey d o n ot n eed to ru n th e sam e clock freq u en cy to ach ieve th at sam e p erform an ce. Even with su ch im p rovem en ts, AMD m arkets th e K5 as a fifth -gen eration p rocessor, ju st like th e Pen tiu m . Th e AMD-K5 op erates at 3.52 volts (VRE Settin g). Som e old er m oth erboard s d efau lt to 3.3 volts, wh ich is below sp ecification for th e K5 an d cou ld cau se erratic op eration . Pseudo-Fift h-Generat ion Processors Th ere is at least on e p rocessor th at, wh ile gen erally regard ed as a fifth -gen eration p rocessor, lacks m an y of th e fu n ction s of th at class of ch ip —th e IDT Cen tau r C6 W in ch ip . Tru e fifth -gen eration ch ip s wou ld h ave m u ltip le in tern al p ip elin es, wh ich is called superscalar architecture, allowin g m ore th an on e in stru ction to be p rocessed at on e tim e. Th ey wou ld also featu re bran ch p red iction , an oth er fifth -gen eration ch ip featu re. As it lacks th ese featu res, th e C6 is m ore closely related to a 486; h owever, th e p erform an ce levels an d th e p in ou t p u t it firm ly in th e class with Pen tiu m p rocessors. It h as tu rn ed ou t to be an id eal Pen tiu m Socket 7-com p atible p rocessor for low-en d system s. IDT Cent aur C6 W inchip. Th e C6 p rocessor is a recen t offerin g from Cen tau r, a su bsid iary of IDT (In tegrated Device Tech n ologies). It is Socket 7-com p atible with In tel’s

Processor Types

Pen tiu m , in clu d es MMX exten sion s, an d is available at clock sp eed s of 180, 200, 225, an d 240MHz. Pricin g is below In tel on th e Pen tiu m MMX. Cen tau r is led by Glen n Hen ry, wh o sp en t m ore th an two d ecad es as a com p u ter arch itect at IBM an d six years as ch ief tech n ology officer at Dell Com p u ter Corp . Th e com p an y is a wh olly own ed su bsid iary of In tegrated Device Tech n ology (IDT), a well-establish ed sem icon d u ctor m an u factu rer well-kn own for SRAM an d oth er com p on en ts. As a m an u factu rer, IDT own s its own fabs (sem icon d u ctor m an u factu rin g p lan ts), wh ich will h elp keep costs low on th e C6 W in ch ip . Th eir exp ertise in SRAM m an u factu rin g m ay be ap p lied in n ew version s of th e C6, wh ich in tegrate on board L2 cach e in th e sam e p ackage as th e core p rocessor, sim ilar to th e Pen tiu m Pro. Th e C6 h as 32K each of in stru ction an d data cach e, ju st like AMD’s K6 an d Cyrix’s 6x86MX, yet it h as on ly 5.4 m illion tran sistors, com pared with th e AMD ch ip’s 8.8 m illion an d th e Cyrix ch ip’s 6.5 m illion . Th is allows for a very sm all processor die, wh ich also redu ces power con su m ption . Cen tau r ach ieved th is sm all size with a stream lin ed design . Un like com petitor ch ips, th e C6 is n ot su perscalar—it issu es on ly on e in stru ction per clock cycle like th e 486. However, with large cach es, an efficien t m em ory-m an agem en t u n it, an d carefu l perform an ce optim ization of com m on ly u sed in stru ction s, th e C6 ach ieves perform an ce th at’s com parable to a Pen tiu m . An oth er ben efit of th e C6’s sim ple design is low power con su m ption —low en ou gh for n otebook PCs. Neith er AMD n or Cyrix h as a processor with power con su m ption low en ou gh for m ost laptop design s. To keep th e d esign sim p le, Cen tau r com p rom ised on floatin g-p oin t an d MMX sp eed an d focu sed in stead on typ ical ap p lication p erform an ce. As a resu lt, th e ch ip ’s p erform an ce trails th e oth er com p etitors’ on som e m u ltim ed ia ap p lication s an d gam es. IDT in d icates th at faster floatin g-p oin t an d MMX p erform an ce will be available in an en h an ced version d u e ou t in m id -’98. P6 ( 686) Sixt h-Generat ion Processors Th e P6 (686) p rocessors rep resen t a n ew gen eration with featu res n ot fou n d in th e p reviou s gen eration u n its. Th e two m ain p rocessors in th e P6 class are th e Pen tiu m Pro an d Pen tiu m II. Desp ite th eir con servative n am es, th ey are m ore th an ju st en h an ced P5 Pen tiu m p rocessors. Th e m ain n ew featu re in th e fifth -gen eration Pen tiu m p rocessors was th e su p erscalar arch itectu re, wh ere two in stru ction execu tion u n its cou ld execu te in stru ction s sim u ltan eou sly in p arallel. Later fifth -gen eration ch ip s also ad d ed MMX tech n ology to th e m ix, as well. So th en wh at d id In tel ad d in th e sixth -gen eration to ju stify callin g it a wh ole n ew gen eration of ch ip ? Besid es m an y m in or im p rovem en ts, th e real key featu res of all sixth -gen eration p rocessors are Dyn am ic Execu tion an d th e Du al In d ep en d en t Bu s (DIB) arch itectu re, p lu s a greatly im p roved su p erscalar d esign . Dyn am ic Execu tion en ables th e p rocessor to execu te m ore in stru ction s on p arallel, so th at tasks are com p leted m ore q u ickly. Th is tech n ology in n ovation is com p rised of th ree m ain elem en ts:

127

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■ Mu ltip le bran ch p red iction , to p red ict th e flow of th e p rogram th rou gh several bran ch es ■ Dataflow an alysis, wh ich sch ed u les in stru ction s to be execu ted wh en read y, in d ep en d en t of th eir ord er in th e origin al p rogram ■ Sp ecu lative execu tion , wh ich in creases th e rate of execu tion by lookin g ah ead of th e p rogram cou n ter an d execu tin g in stru ction s th at are likely to be n eed ed Bran ch p red iction is a featu re form erly fou n d on ly in h igh -en d m ain fram e p rocessors. It allows th e p rocessor to keep th e in stru ction p ip elin e fu ll wh ile ru n n in g at a h igh rate of sp eed . A sp ecial fetch / d ecod e u n it in th e p rocessor u ses a h igh ly op tim ized bran ch p red iction algorith m to p red ict th e d irection an d ou tcom e of th e in stru ction s bein g execu ted th rou gh m u ltip le levels of bran ch es, calls, an d retu rn s. It is like a ch ess p layer workin g ou t m u ltip le strategies in ad van ce of gam e p lay by p red ictin g th e op p on en t’s strategy several m oves in to th e fu tu re. By p red ictin g th e in stru ction ou tcom e in ad van ce, th e in stru ction s can be execu ted with n o waitin g. Dataflow an alysis stu d ies th e flow of d ata th rou gh th e p rocessor to d etect an y op p ortu n ities for ou t-of-ord er in stru ction execu tion . A sp ecial d isp atch / execu te u n it in th e p rocessor m on itors m an y in stru ction s an d can execu te th ese in stru ction s in an ord er th at op tim izes th e u se of th e m u ltip le su p erscalar execu tion u n its. Th e resu ltin g ou t-of-ord er execu tion of in stru ction s can keep th e execu tion u n its bu sy even wh en cach e m isses an d oth er d ata d ep en d en t in stru ction s m igh t oth erwise h old th in gs u p . Sp ecu lative execu tion is th e p rocessor’s cap ability to execu te in stru ction s in ad van ce of th e actu al p rogram cou n ter. Th e p rocessor’s d isp atch / execu te u n it u ses d ataflow an alysis to execu te all available in stru ction s in th e in stru ction p ool an d store th e resu lts in tem p orary registers. A retirem en t u n it th en search es th e in stru ction p ool for com p leted in stru ction s th at are n o lon ger d ata d ep en d en t on oth er in stru ction s to ru n or wh ich h ave u n resolved bran ch p red iction s. If an y su ch com p leted in stru ction s are fou n d , th e resu lts are com m itted to m em ory by th e retirem en t u n it or th e ap p rop riate stan d ard In tel Arch itectu re in th e ord er th ey were origin ally issu ed . Th ey are th en retired from th e p ool. Dyn am ic Execu tion essen tially rem oves th e con strain t an d d ep en d en cy on lin ear in stru ction seq u en cin g. By p rom otin g ou t-of-ord er in stru ction execu tion , it can keep th e in stru ction u n its workin g rath er th an waitin g for d ata from m em ory. Even th ou gh in stru ction s can be p red icted an d execu ted ou t of ord er, th e resu lts are com m itted in th e origin al ord er so as n ot to d isru p t or ch an ge p rogram flow. Th is allows th e P6 to ru n existin g In tel Arch itectu re software exactly as th e P5 (Pen tiu m ) an d p reviou s p rocessors d id , ju st a wh ole lot m ore q u ickly! Th e oth er m ain P6 arch itectu re featu re is kn own as th e Du al In d ep en d en t Bu s. Th is refers to th e fact th at th e p rocessor h as two d ata bu ses, on e for th e system (m oth erboard ) an d th e oth er ju st for cach e. Th is allows th e cach e m em ory to ru n at sp eed s p reviou sly n ot p ossible. Previou s P5 gen eration p rocessors h ave on ly a sin gle m oth erboard h ost p rocessor bu s, an d all d ata, in clu d in g cach e tran sfers, m u st flow th rou gh it. Th e m ain p roblem with

Processor Types

th at is th e cach e m em ory was restricted to ru n n in g at m oth erboard bu s sp eed , wh ich was 66MHz u n til recen tly an d h as n ow m oved to 100MHz. W e h ave cach e m em ory tod ay th at can ru n 500MHz or m ore, an d m ain m em ory (SDRAM) th at ru n s at 66 an d 100MHz, so a m eth od was n eed ed to get faster m em ory closer to th e p rocessor. Th e solu tion was to essen tially bu ild in wh at is called a backsid e bu s to th e p rocessor, oth erwise kn own as a d ed icated cach e bu s. Th e L2 cach e wou ld th en be con n ected to th is bu s an d cou ld ru n at an y sp eed . Th e first im p lem en tation of th is was in th e Pen tiu m Pro, wh ere th e L2 cach e was bu ilt righ t in to th e p rocessor p ackage an d ran at th e fu ll core p rocessor sp eed . Later, th at p roved to be too costly, so th e L2 cach e was m oved ou tsid e of th e p rocessor p ackage an d on to a cartrid ge m od u le, wh ich we n ow kn ow as th e Pen tiu m II. W ith th at d esign , th e cach e bu s cou ld ru n at an y sp eed , with th e first u n its ru n n in g th e cach e at h alf-p rocessor sp eed . By h avin g th e cach e on a backsid e bu s d irectly con n ected to th e p rocessor, th e sp eed of th e cach e is scalable to th e p rocessor. In cu rren t PC arch itectu re—66MHz Pen tiu m s all th e way th rou gh th e 333MHz Pen tiu m IIs—th e m oth erboard ru n s at a sp eed of 66MHz. Newer Pen tiu m II system s ru n a 100MHz m oth erboard bu s an d h ave clock sp eed s of 350MHz an d h igh er. If th e cach e were restricted to th e m oth erboard as is th e case with Socket 7 (P5 p rocessor) d esign s, th en th e cach e m em ory wou ld h ave to rem ain at 66MHz even th ou gh th e p rocessor was ru n n in g as fast as 333MHz; with n ewer board s th e cach e wou ld be stu ck at 100MHz, wh ile th e p rocessor ran as fast as 500MHz or m ore. W ith th e Du al In d ep en d en t Bu s (DIB) d esign in th e P6 p rocessors, as th e p rocessor ru n s faster, at h igh er m u ltip les of th e m oth erboard sp eed , th e cach e wou ld in crease by th e sam e am ou n t th at th e p rocessor sp eed in creases. Th e cach e on th e DIB is cou p led to p rocessor sp eed , so th at d ou blin g th e sp eed of th e p rocessor also d ou bles th e sp eed of th e cach e. Th e Du al In d ep en d en t Bu s arch itectu re is n ecessary to h ave d ecen t p rocessor p erform an ce in th e 300MHz an d beyon d ran ge. Old er Socket 7 (P5 p rocessor) d esign s will n ot be able to m ove u p to th ese h igh er sp eed s with ou t su fferin g a trem en d ou s p erform an ce p en alty d u e to th e slow m oth erboard -bou n d L2 cach e. Th at is wh y In tel is n ot d evelop in g an y Pen tiu m (P5 class) p rocessors beyon d 266MHz; h owever, th e P6 p rocessors will be available in sp eed s of u p to 500MHz or m ore. Fin ally, th e P6 arch itectu re u p grad es th e su p erscalar arch itectu re of th e P5 p rocessors by ad d in g m ore in stru ction execu tion u n its, an d by breakin g d own th e in stru ction s in to sp ecial m icro-op s. Th is is wh ere th e CISC (Com p lex In stru ction Set Com p u ter) in stru ction s are broken d own in to m ore RISC (Red u ced In stru ction Set Com p u ter) com m an d s. Th e RISC-level com m an d s are sm aller an d easier for th e p arallel in stru ction u n its to execu te m ore efficien tly. W ith th is d esign , In tel h as brou gh t th e ben efits of a RISC p rocessor—h igh -sp eed d ed icated in stru ction execu tion —to th e CISC world . Note th at th e P5 h ad on ly two in stru ction u n its, wh ile th e P6 h as at least six sep arate d ed icated in stru ction u n its. It is said to be th ree-way su p erscalar, becau se th e m u ltip le in stru ction u n its can execu te u p to th ree in stru ction s in on e cycle. Oth er im p rovem en ts in efficien cy also are in clu d ed in th e P6 arch itectu re: bu ilt-in m u ltip rocessor su p p ort, en h an ced error d etection an d correction circu itry, an d op tim ization for 32-bit software.

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Rath er th an ju st bein g a faster Pen tiu m , th e Pen tiu m Pro, Pen tiu m II, an d oth er sixth gen eration p rocessors h ave m an y featu re an d arch itectu ral im p rovem en ts. Th e core of th e ch ip is very RISC (Red u ced In stru ction Set Com p u ter)-like, wh ile th e extern al in stru ction in terface is classic In tel CISC (Com p lex In stru ction Set Com p u ter). By breakin g d own th e CISC in stru ction s in to several d ifferen t RISC in stru ction s an d ru n n in g th em d own p arallel execu tion p ip elin es, th e overall p erform an ce is in creased . Com p ared to a Pen tiu m at th e sam e clock sp eed , th e P6 p rocessors are faster—as lon g as you ’re ru n n in g 32-bit software. Th e P6 Dyn am ic Execu tion is op tim ized for p erform an ce p rim arily wh en ru n n in g 32-bit software su ch as W in d ows NT. If you are u sin g 16-bit software, su ch as W in d ows 95 or 98 (wh ich op erate p art tim e in a 16-bit en viron m en t) an d m ost old er ap p lication s, th e P6 will n ot p rovid e as m arked a p erform an ce im p rovem en t over sim ilarly sp eed -rated Pen tiu m an d Pen tiu m -MMX p rocessors. Th at’s becau se th e d yn am ic execu tion cap ability will n ot be fu lly exp loited . Becau se of th is, W in d ows NT is often regard ed as th e m ost d esirable op eratin g system for u se with Pen tiu m Pro/ II p rocessors. W h ile th is is n ot exactly tru e (a Pen tiu m Pro/ II will ru n ju st fin e u n d er W in d ows 95/ 98), W in d ows NT d oes take better ad van tage of th e P6’s cap abilities. Note th at it is really n ot so m u ch th e op eratin g system , bu t wh ich ap p lication s you u se. Software d evelop ers can take step s to gain th e fu ll ad van tages of th e sixth -gen eration p rocessors. Th is in clu d es u sin g m od ern com p ilers th at can im p rove p erform an ce for all cu rren t In tel p rocessors, writin g 32-bit cod e wh ere p ossible an d m akin g cod e as p red ictable as p ossible to take ad van tage of th e p rocessor’s “Dyn am ic Execu tion ” m u ltip le bran ch p red iction cap abilities. Pent ium Pro Processor. In tel’s su ccessor to th e Pen tiu m is called th e Pentium Pro. Th e Pen tiu m Pro was th e first ch ip in th e P6 or sixth -gen eration p rocessor fam ily. It was in trod u ced in Sep tem ber of 1995, an d becam e wid ely available in 1996. Th e ch ip is a 387p in u n it th at resid es in Socket 8, so it is n ot p in -com p atible with earlier Pen tiu m s. Th e n ew ch ip is u n iq u e am on g p rocessors as it is con stru cted in a Mu lti-Ch ip Mod u le (MCM) p h ysical form at, wh ich In tel is callin g a Dual Cavity PGA (Pin Grid Array) p ackage. In sid e th e 387-p in ch ip carrier are two d ies. On e con tain s th e actu al Pen tiu m Pro p rocessor (sh own in Figu re 3.22), an d th e oth er a 256K (th e Pen tiu m Pro with 256K cach e is sh own in Figu re 3.23), 512K, or 1M (th e Pen tiu m Pro with 1M cach e is sh own in Figu re 3.24) L2 cach e. Th e p rocessor d ie con tain s 5.5 m illion tran sistors, th e 256K cach e d ie con tain s 15.5 m illion tran sistors, an d th e 512K cach e d ie(s) h ave 31 m illion tran sistors each , for a p oten tial total of n early 68 m illion tran sistors in a Pen tiu m Pro with 1M of in tern al cach e! A Pen tiu m Pro with 1M cach e h as two 512K cach e d ie an d a stan d ard P6 p rocessor d ie. Th e m ain p rocessor d ie in clu d es a 16K sp lit L1 cach e with an 8K two-way set associative cach e for p rim ary in stru ction s, an d an 8K fou r-way set associative cach e for d ata. An oth er sixth -gen eration p rocessor featu re fou n d in th e Pen tiu m Pro is th e Du al In d ep en d en t Bu s (DIB) arch itectu re, wh ich ad d resses th e m em ory ban d wid th lim itation s of p reviou s-gen eration p rocessor arch itectu res. Two bu ses m ake u p th e Du al In d ep en d en t Bu s arch itectu re: th e L2 cach e bu s (con tain ed en tirely with in th e p rocessor p ackage) an d th e p rocessor-to-m ain -m em ory system bu s. Th e sp eed of th e d ed icated L2 cach e bu s on

Processor Types

th e Pen tiu m Pro is eq u al to th e fu ll core sp eed of th e p rocessor. Th is was accom p lish ed by em bed d in g th e cach e ch ip s d irectly in to th e Pen tiu m Pro p ackage. Th e DIB p rocessor bu s arch itectu re ad d resses p rocessor-to-m em ory bu s ban d wid th lim itation s. It offers u p to th ree tim es th e p erform an ce ban d wid th of th e sin gle-bu s, “Socket 7” gen eration p rocessors, su ch as th e Pen tiu m .

FIG. 3.22 Pen tiu m Pro Processor d ie. Photograph used by perm ission of Intel Corporation.

FIG. 3.23 Pen tiu m Pro Processor with 256K L2 cach e (left). Photograph used by perm ission of Intel Corporation.

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Chapter 3—M icroprocessor Types and Specifications

FIG. 3.24 Pen tiu m Pro Processor with 1M L2 cach e (cen ter an d righ t). Photograph used by perm ission of Intel Corporation.

Table 3.25 sh ows Pen tiu m Pro p rocessor sp ecification s. Table 3.26 sh ows th e sp ecification s for each m od el with in th e Pen tiu m Pro fam ily, as th ere are m an y variation s from m od el to m od el. Table 3.25

Pent ium Pro Fam ily Processor Specificat ions

Int roduced:

Sept em ber 1995

M aximum rated speeds:

150, 166, 180, 200M Hz

CPU clock multiplier:

2.5x, 3x

Internal Registers:

32-bit

External Data Bus:

64-bit

M emory Address Bus:

36-bit

Addressable memory:

64G

Virtual memory:

64T

Integral L1-cache size:

8K code, 8K data (16K total)

Integrated L2-cache bus:

64-bit, full core-speed

Socket/ Slot:

Socket 8

Physical Package:

387-pin Dual Cavity Pin Grid Array

Package dimensions:

2.46 (6.25cm) x 2.66 (6.76cm)

M ath coprocessor:

Built-in FPU (Floating-Point Unit)

Power management:

SM M (System M anagement M ode)

Operating voltage:

3.1v or 3.3v

Processor Types

Table 3.26

Pent ium Pro Processor Specificat ions by Processor M odel

Pent ium Pro Processor ( 200M Hz) w it h 1M Int egrat ed Level 2 Cache Introduction date:

August 18, 1997

Clock speeds:

200M Hz (66M Hz x 3)

Number of transistors:

5.5 million (0.35 micron process), plus 62 million in 1M L2 cache (0.35 micron)

Cache M emory:

8Kx2 (16K) L1, 1M core-speed L2

Die Size:

0.552 inches per side (14.0mm)

Pent ium Pro Processor ( 200M Hz) Introduction date:

November 1, 1995

Clock speeds:

200M Hz (66M Hz x 3)

iCOM P Index 2.0 rating:

220

Number of transistors:

5.5 million (0.35 micron process), plus 15.5 million in 256K L2 cache (0.6 micron), or 31 million in 512K L2 cache (0.35 micron)

Cache M emory:

8Kx2 (16K) L1, 256K or 512K core-speed L2

Die Size:

0.552 inches per side (14.0mm)

Pent ium Pro Processor ( 180M Hz) Introduction date:

November 1, 1995

Clock speeds:

180M Hz (60M Hz x 3)

iCOM P Index 2.0 rating:

197

Number of transistors:

5.5 million (0.35 micron process), plus 15.5 million in 256K L2 cache (0.6 micron)

Cache M emory:

8Kx2 (16K) L1, 256K core-speed L2

Die Size:

0.552 inches per side (14.0mm)

Pent ium Pro Processor ( 166M Hz) Introduction date:

November 1, 1995

Clock speeds:

166M Hz (66M Hz x 2.5)

Number of transistors:

5.5 million (0.35 micron process), plus 31 million in 512K L2 cache (0.35 micron)

Cache M emory:

8Kx2 (16K) L1, 512K core-speed L2

Die Size:

0.552 inches per side (14.0mm)

Pent ium Pro Processor ( 150M Hz) Introduction date:

November 1, 1995

Clock speeds:

150M Hz (60M Hz x 2.5)

Number of transistors:

5.5 million (0.6 micron process), plus 15.5 million in 256K L2 cache (0.6 micron)

Cache M emory:

8Kx2 (16K) L1, 256K core-speed L2

Die Size:

0.691 inches per side (17.6mm)

As you saw in Table 3.2, perform an ce com parison s on th e iCOMP 2.0 In dex rate a classic Pen tiu m 200MHz at 142, wh ereas a Pen tiu m Pro 200MHz scores an im pressive 220. Ju st for

133

134

Chapter 3—M icroprocessor Types and Specifications

com parison , n ote th at a Pen tiu m MMX 200MHz falls righ t abou t in th e m iddle in regards to perform an ce at 182. Keep in m in d th at u sin g a Pen tiu m Pro with an y 16-bit software application s will n u llify m u ch of th e perform an ce gain sh own by th e iCOMP 2.0 ratin g. Like th e Pen tiu m before it, th e Pen tiu m Pro ru n s clock m u ltip lied on a 66MHz m oth erboard . Th e followin g table lists sp eed s for Pen tiu m Pro p rocessors an d m oth erboard s. CPU Type/ Speed

CPU Clock

M ot herboard Speed

Pentium Pro 150

2.5x

60

Pentium Pro 166

2.5x

66

Pentium Pro 180

3x

60

Pentium Pro 200

3x

66

Th e in tegrated L2 cach e is on e of th e really ou tstan d in g featu res of th e Pen tiu m Pro. By bu ild in g th e L2 cach e in to th e CPU an d gettin g it off th e m oth erboard , th ey can n ow ru n th e cach e at fu ll p rocessor sp eed rath er th an th e slower 60 or 66MHz m oth erboard bu s sp eed s. In fact, th e L2 cach e featu res its own in tern al 64-bit backsid e bu s, wh ich d oes n ot sh are tim e with th e extern al 64-bit fron tsid e bu s u sed by th e CPU. Th e in tern al registers an d d ata p ath s are still 32-bit, as with th e Pen tiu m . By bu ild in g th e L2 cach e in to th e system , m oth erboard s can be ch eap er becau se th ey n o lon ger req u ire sep arate cach e m em ory. Som e board s m ay still try to in clu d e cach e m em ory in th eir d esign , bu t th e gen eral con sen su s is th at Level 3 cach e (as it wou ld be called ) wou ld offer less im p rovem en t with th e Pen tiu m Pro th an with th e Pen tiu m . On e of th e featu res of th e bu ilt-in L2 cach e is th at m u ltip rocessin g is greatly im p roved . Rath er th an ju st SMP, as with th e Pen tiu m , th e Pen tiu m Pro su p p orts a n ew typ e of m u ltip rocessor con figu ration called th e Multi-Processor Specification (MPS 1.1). Th e Pen tiu m Pro with MPS allows con figu ration s of u p to fou r p rocessors ru n n in g togeth er. Un like oth er m u ltip rocessor con figu ration s, th e Pen tiu m Pro avoid s cach e coh eren cy p roblem s becau se each ch ip m ain tain s a sep arate L1 an d L2 cach e in tern ally. Pen tiu m Pro-based m oth erboard s are p retty m u ch exclu sively PCI an d ISA bu s-based , an d In tel is p rod u cin g th eir own ch ip sets for th ese m oth erboard s. Th e first ch ip set was th e 450KX/ GX (cod e-n am ed Orion ), wh ile th e m ost recen t ch ip set for u se with th e Pen tiu m Pro is th e 440LX (Natom a). Du e to th e greater coolin g an d sp ace req u irem en ts, In tel d esign ed th e n ew ATX m oth erboard form factor to better su p p ort th e Pen tiu m Pro an d oth er fu tu re p rocessors, like th e Pen tiu m II. Even so, th e Pen tiu m Pro can be fou n d in all typ es of m oth erboard d esign s; ATX is n ot m an d atory. ◊◊ See “ M otherboard Form Factors,” p. 167, and “ Sixth-Generation (P6 Pentium Pro / Pentium II Class) Chipsets,“ p. 199

Som e Pen tiu m Pro system m an u factu rers h ave been tem p ted to stick with th e Baby-AT form factor. Th e big p roblem with th e stan d ard Baby-AT form factor is keep in g th e CPU

Processor Types

p rop erly cooled . Th e m assive Pen tiu m Pro p rocessor con su m es m ore th an 25 watts an d gen erates an ap p reciable am ou n t of h eat. Fou r sp ecial Voltage Id en tification (VID) Pin s are on th e Pen tiu m Pro p rocessor. Th ese p in s can be u sed to su p p ort au tom atic selection of p ower su p p ly voltage. Th is m ean s th at a Pen tiu m Pro m oth erboard d oes n ot h ave voltage regu lator ju m p er settin gs like m ost Pen tiu m board s, wh ich greatly eases th e setu p an d in tegration of a Pen tiu m Pro system . Th ese p in s are n ot actu ally sign als, bu t are eith er an op en circu it in th e p ackage or a sh ort circu it to voltage. Th e seq u en ce of op en s an d sh orts d efin e th e voltage req u ired by th e p rocessor. In ad d ition to allowin g for au tom atic voltage settin gs, th is featu re h as been d esign ed to su p p ort voltage sp ecification variation s on fu tu re Pen tiu m Pro p rocessors. Th e VID p in s are n am ed VID0 th rou gh VID3 an d th e d efin ition of th ese p in s is sh own in Table 3.27. A 1 in th is table refers to an op en p in an d 0 refers to a sh ort to grou n d . Th e voltage regu lators on th e m oth erboard sh ou ld su p p ly th e voltage th at is req u ested or d isable itself. Table 3.27

Pent ium Pro Volt age Ident ificat ion Definit ion

VID[3:0]

Volt age Set t ing

VID[3:0]

Volt age Set t ing

0000

3.5

1000

2.7

0001

3.4

1001

2.6

0010

3.3

1010

2.5

0011

3.2

1011

2.4

0100

3.1

1100

2.3

0101

3.0

1101

2.2

0110

2.9

1110

2.1

0111

2.8

1111

No CPU Present

Most Pen tiu m Pro p rocessors ru n at 3.3v, bu t a few ru n at 3.1v. Alth ou gh th ose are th e on ly version s available n ow, su p p ort for a wid er ran ge of VID settin gs will ben efit th e system in m eetin g th e p ower req u irem en ts of fu tu re Pen tiu m Pro p rocessors. Note th at th e 1111 (or all op en s) ID can be u sed to d etect th e absen ce of a p rocessor in a given socket. Th e Pen tiu m Pro n ever d id becom e very p op u lar on th e d esktop , bu t h as fou n d a n ich e in file server ap p lication s d u e p rim arily to th e fu ll core-sp eed h igh -cap acity in tern al L2 cach e. It is exp ected th at In tel will in trod u ce on ly on e or two m ore variation s of th e Pen tiu m Pro, p rim arily as u p grad e p rocessors for th ose wh o wan t to in stall a faster CPU in th eir existin g Pen tiu m Pro m oth erboard . In m ost cases, it wou ld be wiser to in stall a n ew Pen tiu m II m oth erboard in stead . Th e followin g tables list th e u n iq u e sp ecification s of th e d ifferen t m od els of th e Pen tiu m Pro. As with oth er p rocessors, th e Pen tiu m Pro h as been available in a n u m ber of d ifferen t revision s an d step p in gs. Th e followin g table sh ows all th e version s of th e Pen tiu m Pro. Th ey can be id en tified by th e Sp ecification n u m ber p rin ted on th e top an d bottom of th e ch ip .

135

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Type

Fam ily

M odel

St epping

M fg. St epping

0

6

1

1

B0

0

6

1

1

B0

0

6

1

1

B0

0

6

1

1

B0

0

6

1

1

B0

0

6

1

1

B0

0

6

1

1

B0

0

6

1

2

C0

0

6

1

2

C0

0

6

1

2

C0

0

6

1

2

C0

0

6

1

6

sA0 2

0

6

1

6

sA0 2

0

6

1

6

sA0 2

0

6

1

6

sA0 2

0

6

1

6

sA0 2

0

6

1

6

sA0 2

0

6

1

6

sA0 2

0

6

1

6

sA0 2

0

6

1

6

sA0 2

0

6

1

6

sA0 2

0

6

1

6

sA0 2

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

Processor Types

L2 Size/ St epping

Speed Core/ Bus

Spec.

Volt age ( +/ -5% )

Not es

256/ a

133/ 66

Q0812

3.1V

3,4

256/ a

150/ 60

Q0813

3.1V

3,4

256/ a

133/ 66

Q0815

3.1V

3,4

256/ a

150/ 60

Q0816

3.1V

3,4

256/ a

150/ 60

SY002

3.1V

3

256/ a

150/ 60

SY011

3.1V

256/ a

150/ 60

SY014

3.1V

256/ a

150/ 60

Q0822

3.1V

3,4

256/ a

150/ 60

Q0825

3.1V

4

256/ a

150/ 60

Q0826

3.1V

4

256/ a

150/ 60

SY010

3.1V

256/ a

180/ 60

Q0858

3.3V

4

256/ a

200/ 66

Q0859

3.3V

4

256/ a

180/ 60

Q0860

3.3V

4,5

256/ a

200/ 66

Q0861

3.3V

4,5

512/ Pre 6

166/ 66

Q0864

3.3V

4

512/ Pre 6

200/ 66

Q0865

3.3V

4

256/ a

180/ 60

Q0873

3.3V

4

256/ a

200/ 66

Q0874

3.3V

4

256/ a

180/ 60

Q0910

3.3V

256/ a

180/ 60

SY012

3.3V

256/ a

200/ 66

SY013

3.3V

256/ a

200/ 66

Q076

3.3V

7

256/ a

180/ 60

Q0871

3.3V

4

256/ a

200/ 66

Q0872

3.3V

4

256/ a

180/ 60

Q0907

3.3V

4

256/ a

200/ 66

Q0908

3.3V

4

256/ b

200/ 66

Q0909

3.3V

4

512/ Pre 6

166/ 66

Q0918

3.3V

4

512/ Pre 6

200/ 66

Q0920

3.3V

4

512/ Pre 6

200/ 66

Q0924

3.3V

4

512/ a

166/ 66

Q0929

3.3V

4

512/ a

200/ 66

Q932

3.3V

4

512/ b

166/ 66

Q935

3.3V

4

512/ b

200/ 66

Q936

3.3V

4

256/ a

200/ 66

SL245

3.5V

7

256/ a

200/ 66

SL247

3.5V

7

256/ b

180/ 60

SU103

3.3V

8 (continues)

137

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Chapter 3—M icroprocessor Types and Specifications

Type

Fam ily

M odel

St epping

M fg. St epping

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

7

sA1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

0

6

1

9

sB1

NOTES: 1. L2 Cache Stepping refers to the silicon revision of the 256-K, 512-K, or 1M on-chip L2 cache. The a designation refers to the first production steppings, the b to the second production steppings, and so on. 2. The sA0 stepping is logically equivalent to the C0 stepping, but on a different m anufacturing process. 3. The V ID pins are not supported on these parts. 4. These are engineering sam ples only, provided under a Pentium Pro processor nondisclosure loan agreem ent. 5. The V ID pins are functional but not tested on these parts. 6. These sam ple parts are equipped with a preproduction 512-K L2 cache.

Processor Types

L2 Size/ St epping

Speed Core/ Bus

Spec.

Volt age ( +/ -5% )

Not es

256/ b

200/ 66

256/ b

180/ 60

SU104

3.3V

8

SY031

3.3V

256/ b

200/ 66

SY032

3.3V

512/ a

166/ 66

SY034

3.3V

256/ a

180/ 60

SY039

3.3V

256/ b

200/ 66

SY040

3.3V

512/ b

166/ 66

SY047

3.3V

512/ b

200/ 66

SY048

3.3V

512/ b

166/ 66

Q008

3.3V

4

512/ b

166/ 66

Q009

3.3V

4

512/ b

200/ 66

Q010

3.3V

4

512/ b

200/ 66

Q011

3.3V

4

256/ b

180/ 60

Q033

3.3V

4

256/ b

200/ 66

Q034

3.3V

4

256/ b

180/ 60

Q035

3.3V

4

256/ b

200/ 66

Q036

3.3V

4

256/ b

200/ 66

Q083

3.5V

7

256/ b

200/ 66

Q084

3.5V

7

256/ b

180/ 60

SL22S

3.3V

256/ b

200/ 66

SL22T

3.3V

256/ b

180/ 60

SL22U

3.3V

256/ b

200/ 66

SL22V

3.3V

512/ b

166/ 66

SL22X

3.3V

512/ b

200/ 66

SL22Z

3.3V

256/ b

180/ 60

SL23L

3.3V

8

256/ b

200/ 66

SL23M

3.3V

8

256/ b

200/ 66

SL254

3.5V

7

256/ b

200/ 66

SL255

3.5V

7

512/ b

166/ 66

SL2FJ

3.3V

8

1024/ g

200/ 66

SL259

3.3V

1024/ g

200/ 66

SL25A

3.3V

7. These com ponents have additional specification changes associated with them : a. Prim ary V oltage = 3.5V b. Max Therm al Design Power = 39.4W @ 200MHz, 256K L2 c. Max Current = 11.9A d. The V ID pins are not supported on these parts. 8. This is a boxed Pentium Pro processor with an unattached fan heat sink. 9. This part also ships as a boxed processor with an unattached fan heat sink.

9

139

140

Chapter 3—M icroprocessor Types and Specifications

Pent ium II. In tel revealed its latest P6 fam ily p rocessor in May 1997, wh en it p u lled th e wrap s off th e Pen tiu m II. Prior to its official u n veilin g, th e Pen tiu m II p rocessor was p op u larly referred to by its cod e n am e “Klam ath ,” an d was su rrou n d ed by m u ch sp ecu lation th rou gh ou t th e in d u stry. Th e Pen tiu m II is essen tially th e sam e sixth -gen eration p rocessor as th e Pen tiu m Pro with MMX tech n ology ad d ed (d ou ble th e L1 cach e an d 57 n ew MMX in stru ction s); h owever, th ere are a few twists to th e d esign . Th e Pen tiu m II p rocessor d ie is sh own in Figu re 3.25.

FIG. 3.25 Pen tiu m II Processor d ie. Photograph used by perm ission of Intel Corporation. From a p h ysical stan d p oin t, it is tru ly som eth in g n ew. Aban d on in g th e ch ip in a socket ap p roach u sed by virtu ally all p rocessors u p u n til th is p oin t, th e Pen tiu m II ch ip is ch aracterized by its Sin gle Ed ge Con tact (SEC) cartrid ge d esign . Th e p rocessor, alon g with several L2 cach e ch ip s, is m ou n ted on a sm all circu it board (m u ch like an oversized m em ory SIMM) as sh own in Figu re 3.26, wh ich is th en sealed in a m etal an d p lastic cartrid ge. Th e cartrid ge is th en p lu gged in to th e m oth erboard th rou gh an ed ge con n ector called Slot 1, wh ich looks very m u ch like an ad ap ter card slot. By u sin g sep arate ch ip s m ou n ted on a circu it board , In tel can bu ild th e Pen tiu m II m u ch less exp en sively th an th e m u ltip le d ie with in a p ackage u sed in th e Pen tiu m Pro. Th ey can also u se cach e ch ip s from oth er m an u factu rers, an d m ore easily vary th e am ou n t of cach e in fu tu re p rocessors com p ared to th e Pen tiu m Pro d esign .

Processor Types

FIG. 3.26 Pen tiu m II Processor Board (in sid e SEC cartrid ge). Photograph used by perm ission of Intel Corporation.

At p resen t, In tel is offerin g Pen tiu m II p rocessors with th e followin g sp eed s: CPU Type/ Speed

CPU Clock

M ot herboard Speed

Pentium II 233M Hz

3.5x

66M Hz

Pentium II 266M Hz

4x

66M Hz

Pentium II 300M Hz

4.5x

66M Hz

Pentium II 333M Hz

5x

66M Hz

Pentium II 350M Hz

3.5x

100M Hz

Pentium II 400M Hz

4x

100M Hz

Pentium II 450M Hz

4.5x

100M Hz

Th e Pen tiu m II p rocessor core h as 7.5 m illion tran sistors an d is based on In tel’s ad van ced P6 arch itectu re. Th e Pen tiu m II started ou t u sin g .35-m icron p rocess tech n ology, alth ou gh th e 333MHz an d faster Pen tiu m IIs are based on 0.25-m icron tech n ology. Th is en ables a sm aller d ie, allowin g in creased core freq u en cies an d red u ced p ower con su m p tion . At 333MHz, th e Pen tiu m II p rocessor d elivers a 75–150% p erform an ce boost, com p ared to th e 233MHz Pen tiu m p rocessor with MMX tech n ology, an d ap p roxim ately 50% m ore p erform an ce on m u ltim ed ia ben ch m arks. Th ese are very fast p rocessors, at least for n ow. As sh own in Table 3.2, th e iCOMP 2.0 In d ex ratin g for th e Pen tiu m II 266MHz ch ip is m ore th an twice as fast as a classic Pen tiu m 200MHz. Asid e from sp eed , th e best way to th in k of th e Pen tiu m II is as a Pen tiu m Pro with MMX tech n ology in stru ction s an d a sligh tly m od ified cach e d esign . It h as th e sam e m u ltip rocessor scalability as th e Pen tiu m Pro, as well as th e in tegrated L2 cach e. Th e 57 n ew m u ltim ed ia-related in stru ction s carried over from th e MMX p rocessors an d th e cap ability to p rocess rep etitive loop com m an d s m ore efficien tly are also in clu d ed . Also in clu d ed as

141

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Chapter 3—M icroprocessor Types and Specifications

a p art of th e MMX u p grad e is d ou ble th e in tern al L1 cach e from th e Pen tiu m Pro (from 16K total to 32K total in th e Pen tiu m II). Th e origin al Pen tiu m II p rocessors were m an u factu red u sin g a 0.35-m icron p rocess. More recen t m od els, startin g with th e 333MHz version , h ave been m an u factu red u sin g a n ewer 0.25 m icron p rocess. In tel is con sid erin g goin g to a 0.18-m icron p rocess in th e fu tu re. By goin g to th e sm aller p rocess, p ower d raw is greatly red u ced . Maxim u m p ower u sage for th e Pen tiu m II is sh own in th e followin g table. Core Speed

Pow er Draw

Process

Volt age

400M Hz

27.9w

0.25 micron

2.0v

350M Hz

24.5w

0.25 micron

2.0v

333M Hz

23.7w

0.25 micron

2.0v

300M Hz

43.0w

0.35 micron

2.8v

266M Hz

38.2w

0.35 micron

2.8v

233M Hz

34.8w

0.35 micron

2.8v

You can see th at th e n ewer 400MHz version of th e Pen tiu m II actu ally u ses less p ower th an th e origin al 233MHz version ! Th is was accom p lish ed by u sin g th e sm aller 0.25m icron p rocess an d ru n n in g th e p rocessor on a lower voltage of on ly 2.0v. Fu tu re Pen tiu m II p rocessors will u se th e 0.25 an d 0.18-m icron p rocesses an d 2.0v an d lower voltages to con tin u e th is tren d . Th e Pen tiu m II in clu d es Dyn am ic Execu tion , wh ich d escribes u n iq u e p erform an ceen h an cin g d evelop m en ts by In tel, first in trod u ced in th e Pen tiu m Pro p rocessor. Major featu res of Dyn am ic Execu tion in clu d e Mu ltip le Bran ch Pred iction , wh ich sp eed s execu tion by p red ictin g th e flow of th e p rogram th rou gh several bran ch es; Dataflow An alysis, wh ich an alyzes an d m od ifies th e p rogram ord er to execu te in stru ction s wh en read y; an d Sp ecu lative Execu tion , wh ich looks ah ead of th e p rogram cou n ter an d execu tes in stru ction wh ich are likely to be n eed ed . Th e Pen tiu m II p rocessor exp an d s on th ese cap abilities in sop h isticated an d p owerfu l n ew ways to d eliver even greater p erform an ce gain s. Like th e Pen tiu m Pro, th e Pen tiu m II also in clu d es DIB arch itectu re. Th e term Dual Independent Bus com es from th e existen ce of two in d ep en d en t bu ses on th e Pen tiu m II p rocessor—th e L2 cach e bu s an d th e p rocessor-to-m ain -m em ory system bu s. Th e Pen tiu m II p rocessor can u se both bu ses sim u ltan eou sly, th u s gettin g as m u ch as 2X m ore d ata in an d ou t of th e Pen tiu m II p rocessor th an a sin gle-bu s arch itectu re p rocessor. Th e DIB arch itectu re en ables th e L2 cach e of th e 333MHz Pen tiu m II p rocessor to ru n 2.5 tim es as fast as th e L2 cach e of Pen tiu m p rocessors. As th e freq u en cy of fu tu re Pen tiu m II p rocessors in creases, so will th e sp eed of th e L2 cach e. Also, th e p ip elin ed system bu s en ables sim u ltan eou s p arallel tran saction s in stead of sin gu lar seq u en tial tran saction s. Togeth er, th ese Du al In d ep en d en t Bu s arch itectu re im p rovem en ts offer u p to th ree tim es th e ban d wid th p erform an ce over a sin gle-bu s arch itectu re as with th e regu lar Pen tiu m .

Processor Types

Table 3.28 sh ows th e gen eral Pen tiu m II p rocessor sp ecification s. Table 3.29 sh ows th e sp ecification s th at vary by m od el for th e m od els th at h ave been in trod u ced to d ate. Table 3.28

Pent ium II General Processor Specificat ions

Bus Speeds:

66M Hz, 100M Hz

CPU clock multiplier:

3.5x,4x,4.5x,5x

CPU Speeds:

233M Hz, 266M Hz, 300M Hz, 333M Hz, 350M Hz, 400M Hz, 450M Hz

Cache M emory:

16Kx2 (32K) L1, 512K 1/ 2-speed L2

Internal Registers:

32-bit

External Data Bus:

64-bit System Bus w/ ECC; 64-bit Cache Bus w/ optional ECC

M emory Address Bus:

36-bit

Addressable M emory:

64G

Virtual M emory:

64T

Physical package:

Single Edge Contact Cartridge (S.E.C.), 242 pins

Package Dimensions:

5.505-inches (12.82cm) ×2.473 inches (6.28cm)×0.647 inches (1.64cm)

M ath coprocessor:

Built-in FPU (Floating-Point Unit)

Power management:

SM M (System M anagement M ode)

Table 3.29

Pent ium II Specificat ions by M odel

Pent ium II M M X Processor ( 350 and 400M Hz) Introduction date:

April 15, 1998

Clock speeds:

350M Hz (100M Hz x 3.5) and 400M Hz (100M Hz x 4)

iCOM P Index 2.0 rating:

86 (350M Hz) and 440 (400M Hz)

Number of transistors:

7.5 million (0.25 micron process), plus 31 million in 512K L2 cache

Cacheable RAM :

4GB

Operating voltage:

2.0v

Slot:

Slot 2

Die Size:

0.400 inches per side (10.2mm)

Pent ium II M M X Processor ( 333M Hz) Introduction date:

January 26, 1998

Clock speeds:

333M Hz (66M Hz x 5)

iCOM P Index 2.0 rating:

366

Number of transistors:

7.5 million (0.25 micron process), plus 31 million in 512K L2 cache

Cacheable RAM :

512M B

Operating voltage:

2.0v

Slot:

Slot 1

Die Size:

0. 400 inches per side (10.2mm) (continues)

143

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Chapter 3—M icroprocessor Types and Specifications

Table 3.29

Pent ium II Specificat ions by M odel Cont inued

Pent ium II M M X Processor ( 300M Hz) Introduction date:

M ay 7, 1997

Clock speeds:

300M Hz (66M Hz x 4.5)

iCOM P Index 2.0 rating:

332

Number of transistors:

7.5 million (0.35 micron process), plus 31 million in 512K L2 cache

Cacheable RAM :

512M B

Die Size:

0. 560 inches per side (14.2mm)

Pent ium II M M X Processor ( 266M Hz) Introduction date:

M ay 7, 1997

Clock speeds:

266M Hz (66M Hz x 4)

iCOM P Index 2.0 rating:

303

Number of transistors:

7. 5 million (0.35 micron process), plus 31 million in 512K L2 cache

Cacheable RAM :

512M B

Slot:

Slot 1

Die Size:

0.560 inches per side (14.2mm)

Pent ium II M M X Processor ( 233M Hz) Introduction date:

M ay 7, 1997

Clock speeds:

233M Hz (66M Hz x 3.5)

iCOM P Index 2.0 rating:

267

Number of transistors:

7.5 million (0.35 micron process), plus 31 million in 512K L2 cache

Cacheable RAM :

512M B

Slot:

Slot 1

Die Size:

0.560 inches per side (14.2mm)

As you can see from th e table, th e Pen tiu m II can h an d le u p to 64G of p h ysical m em ory. Like th e Pen tiu m Pro, th e CPU in corp orates Du al In d ep en d en t Bu s arch itectu re. Th is m ean s th e ch ip h as two in d ep en d en t bu ses: on e for accessin g th e L2 cach e, th e oth er for accessin g m ain m em ory. Th ese d u al bu ses can op erate sim u ltan eou sly, greatly acceleratin g th e flow of d ata with in th e system . Th e L1 cach e always ru n s at fu ll core sp eed s becau se it is m ou n ted d irectly on th e p rocessor d ie. Th e L2 cach e in th e Pen tiu m II n orm ally ru n s at 1/ 2-core sp eed , wh ich saves m on ey an d allows for less exp en sive cach e ch ip s to be u tilized . For exam p le, in a 333MHz Pen tiu m II, th e L1 cach e ru n s at a fu ll 333MHz, wh ile th e L2 cach e ru n s at 167MHz. Even th ou gh th e L2 cach e is n ot at fu ll core sp eed as it was with th e Pen tiu m Pro, th is is still far su p erior to h avin g cach e m em ory on th e m oth erboard ru n n in g at th e 66MHz m oth erboard sp eed of m ost Socket 7 Pen tiu m d esign s. In tel claim s th at th e Du al In d ep en d en t Bu s arch itectu re in th e Pen tiu m II allows u p to th ree tim es th e ban d wid th of n orm al sin gle-bu s p rocessors like th e origin al Pen tiu m .

Processor Types

By rem ovin g th e cach e from th e p rocessor’s in tern al p ackage an d u sin g extern al ch ip s m ou n ted on a su bstrate an d en cased in th e cartrid ge d esign , In tel can n ow u se m ore cost-effective cach e ch ip s an d m ore easily scale th e p rocessor u p to h igh er sp eed s. Th e Pen tiu m Pro was lim ited in sp eed to 200MHz, largely d u e to th e in ability to fin d afford able cach e m em ory th at ru n s an y faster. By ru n n in g th e cach e m em ory at 1/ 2-core sp eed , th e Pen tiu m II can ru n u p to 400MHz wh ile still u sin g 200MHz rated cach e ch ip s. To offset th e 1/ 2-core sp eed cach e u sed in th e Pen tiu m II, In tel d ou bled th e basic am ou n t of in tegrated L2 cach e from 256K stan d ard in th e Pro to 512K stan d ard in th e Pen tiu m II. Note th at th e tag-RAM in clu d ed in th e L2 cach e will allow u p to 512MB of m ain m em ory to be cach eable in PII p rocessors from 233MHz to 333MHz. Th e 350MHz, 400MHz, an d faster version s in clu d e an en h an ced tag-RAM th at allows u p to 4G of m ain m em ory to be cach eable. Th is is very im p ortan t if you ever p lan on ad d in g m ore th an 512M of m em ory. In th at case, you wou ld d efin itely wan t th e 350MHz or faster version ; oth erwise, m em ory p erform an ce wou ld su ffer. Th e system bu s of th e Pen tiu m II p rovid es “glu eless” su p p ort for u p to two p rocessors. Th is en ables low-cost, two-way sym m etric m u ltip rocessin g with ou t extra extern al ch ip s, p rovid in g a sign ifican t p erform an ce boost for m u ltitaskin g op eratin g system s an d m u ltith read ed ap p lication s. Fu tu re ch ip sets will be able to “glu e” fou r or m ore PII p rocessors in to a u n ified m u ltip rocessor system , p rim arily for file server u se. Version s of th e Pen tiu m II are available with ECC (Error Correction Cod e) fu n ction ality on th e L2 cach e bu s. Th ese are d esign ed esp ecially for servers or oth er m ission -critical system u se wh ere reliability an d d ata in tegrity are im p ortan t. All Pen tiu m IIs also in clu d e p arity-p rotected ad d ress/ req u est an d resp on se system bu s sign als with a retry m ech an ism for h igh d ata in tegrity an d reliability. To in stall th e Pen tiu m II in a system , a sp ecial p rocessor-reten tion m ech an ism is req u ired . Th is con sists of a m ech an ical su p p ort th at attach es to th e m oth erboard an d secu res th e Pen tiu m II p rocessor in slot 1 to p reven t sh ock an d vibration d am age. Reten tion m ech an ism s sh ou ld be p rovid ed by th e m oth erboard m an u factu rer. (For exam p le, th e In tel Boxed AL440FX an d DK440LX m oth erboard s in clu d e a reten tion m ech an ism , p lu s oth er im p ortan t system in tegration com p on en ts.) Th e Pen tiu m II can gen erate a sign ifican t am ou n t of h eat th at m u st be d issip ated . Th is is accom p lish ed by in stallin g a h eat sin k on th e p rocessor. Man y of th e Pen tiu m II p rocessors will u se an active h eat sin k th at in corp orates a fan . Un like h eat sin k fan s for p reviou s In tel boxed p rocessors, th e Pen tiu m II fan s d raw p ower from a th ree-p in p ower h ead er on th e m oth erboard . Most m oth erboard s p rovid e several fan con n ectors to su p p ly th is p ower. Sp ecial h eat sin k su p p orts are n eed ed to fu rn ish m ech an ical su p p ort between th e fan h eat sin k an d su p p ort h oles on th e m oth erboard . Norm ally, a p lastic su p p ort is in serted in to th e h eat sin k h oles in th e m oth erboard n ext to th e CPU, before in stallin g th e CPU/ h eat sin k p ackage. Most fan h eat sin ks h ave two com p on en ts: a fan in a p lastic sh rou d an d a m etal h eat sin k. Th e h eat sin k is attach ed to th e p rocessor’s th erm al p late an d

145

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Chapter 3—M icroprocessor Types and Specifications

sh ou ld n ot be rem oved . Th e fan can be rem oved an d rep laced if n ecessary, for exam p le, if it h as failed . Figu re 3.27 sh ows th e SEC assem bly with fan , p ower con n ectors, m ech an ical su p p orts, an d th e slot an d su p p ort h oles on th e m oth erboard . Heat Sink Support Mechanism Single Edge Contact (S.E.C.) cartridge Fan

Shroud Covering Heat Sink Fins

Cable

Fan Power Connector

Heat Sink Retention Mechanism

Slot 1 Connector

Retention Mechanism Attach Mount Heat Sink Support Holes

FIG. 3.27 Pen tiu m II Processor an d Heat Sin k Assem bly. Th e followin g tables sh ow th e sp ecification s u n iq u e to certain version s of th e Pen tiu m II p rocessor. To id en tify exactly wh ich Pen tiu m II p rocessor you h ave an d wh at its cap abilities are, ju st look at th e sp ecification n u m ber p rin ted on th e SEC cartrid ge. You will fin d th e sp ecification n u m ber in th e d yn am ic m ark area on th e top of th e p rocessor m od u le. See Figu re 3.28 to locate th ese m arkin gs.

Processor Types

2-D Matrix Mark

intel pentium II with MMX™ technology ®

®

P R O C E S S O R

iCOMP® 2.0 index=YYY SZNNN/XYZ ORDER CODE XXXXXXXX-NNNN

Logo

Product Name

intel

Dynamic Mark Area

pentium ® II

®

Dynamic Mark Area

P R O C E S S O R

with MMX™ technology

m c '94 '96

Trademark

pentium ® II P R O C E S S O R

!

intel

Hologram Location

®

Logo

Product Name

FIG. 3.28 Pen tiu m II Sin gle Ed ge Con tact Cartrid ge. After you h ave located th e sp ecification n u m ber (actu ally, it is an alp h an u m eric cod e), th en you can look it u p in Table 3.30 to see exactly wh ich p rocessor you h ave. For exam p le, a sp ecification n u m ber of SL2KA id en tifies th e p rocessor as a Pen tiu m II 333MHz ru n n in g on a 66MHz system bu s, with an ECC L2 cach e, an d th at th is p rocessor ru n s on on ly 2.0 volts. Th e step p in g is also id en tified , an d by lookin g in th e Pentium II Specification Update Manual p u blish ed by In tel, you cou ld figu re ou t exactly wh ich bu gs were fixed in th at revision .

147

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Chapter 3—M icroprocessor Types and Specifications

Table 3.30

Basic Pent ium II Processor Ident ificat ion Inform at ion

Type

Fam ily

M odel

St epping

Core St epping

L2 Size ( K)

0

6

3

3

C0

512

0

6

3

3

C0

512

0

6

3

3

C0

512

0

6

3

3

C0

512

0

6

3

3

C0

512

0

6

3

3

C0

512

0

6

3

3

C0

512

0

6

3

3

C0

512

0

6

3

3

C0

512

0

6

3

4

C1

512

0

6

3

4

C1

512

0

6

3

4

C1

512

0

6

3

4

C1

512

0

6

3

4

C1

512

0

6

3

4

C1

512

0

6

3

4

C1

512

0

6

3

4

C1

512

0

6

3

4

C1

512

0

6

5

0

dA0

512

0

6

5

0

dA0

512

0

6

5

1

dA1

512

0

6

5

1

dA1

512

0

6

5

1

dA1

512

0

6

5

1

dA1

512

0

6

5

1

dA1

512

0

6

5

1

dA1

512

Core processor voltage is 2.8v +100/-70m v for all Pentium II processors unless indicated otherwise. 2.0v = Core processor voltage (V cc_CORE) is 2.0v +100/-70m v for these Pentium II processors. The allowed processor tem perature range for all Pentium II processors is 5°C–75°C unless indicated otherwise. 72°C = Allowed processor tem perature range 5°C–72°C.

Processor Types

TagRAM / st epping

S-Spec

ECC/ Non-ECC

Speed( M Hz) Core/ Bus

T6/ B0

SL264

non-ECC

233/ 66

T6/ B0

SL265

non-ECC

266/ 66

T6/ B0

SL268

ECC

233/ 66

T6/ B0

SL269

ECC

266/ 66

T6/ B0

SL28K

non-ECC

233/ 66

Not es

2.0v

T6/ B0

SL28L

non-ECC

266/ 66

2.0v

T6/ B0

SL28R

ECC

300/ 66

72°C

T6/ B0

SL2M Z

ECC

300/ 66

72°C, 2.0v

T6/ B0

SL2PV

ECC

266/ 66

2.0v

T6/ B0

SL2HA

ECC

300/ 66

72°C

T6/ B0

SL2HC

non-ECC

266/ 66

T6/ B0

SL2HD

non-ECC

233/ 66

T6/ B0

SL2HE

ECC

266/ 66

T6/ B0

SL2HF

ECC

233/ 66

T6/ B0

SL2QA

non-ECC

233/ 66

T6/ B0

SL2QB

non-ECC

266/ 66

BOXF

T6/ B0

SL2QC

ECC

300/ 66

72°C, BOXF

T6/ B0

SL2QD

ECC

266/ 66

BOXF

T6P/ A3

SL2KA

ECC

333/ 66

2.0v, 65°C

T6P/ A3

SL2QF

ECC

333/ 66

BOXF,2.0v,65°C

T6P-e/ A0

SL2QH

ECC

333/ 66

BOXF,2.0v,4GB

T6P-e/ A0

SL2S5

ECC

333/ 66

2.0v,4GB

T6P-e/ A0

SL2S6

ECC

350/ 100

2.0v,4GB

T6P-e/ A0

SL2S7

ECC

400/ 100

2.0v,4GB

T6P-e/ A0

SL2SF

ECC

350/ 100

BOXF,2.0v,4GB

T6P-e/ A0

SL2SH

ECC

400/ 100

BOXF,2.0v,4GB

BOXF

65°C = Allowed processor tem perature range 5°C–65°C. BOX F = This is a boxed Pentium II processor with an attached fan heat sink. 4G = These processors have an enhanced L2 cache, which can cache up to 4G of m ain m em ory standard PII processors can only cache up to 512MB of m ain m em ory.

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Chapter 3—M icroprocessor Types and Specifications

Pen tiu m II m oth erboard s h ave an on board voltage regu lator circu it th at is d esign ed to p ower th e CPU. Cu rren tly, th ere are Pen tiu m II p rocessors th at ru n at several d ifferen t voltages, so th e regu lator m u st be set to su p p ly th e correct voltage for th e sp ecific p rocessor you are in stallin g. As with th e Pen tiu m Pro an d u n like th e old er Pen tiu m , th ere are n o ju m p ers or switch es to set; th e voltage settin g is h an d led com p letely au tom atically th rou gh th e Voltage ID (VID) p in s on th e p rocessor cartrid ge. Table 3.31 sh ows th e relation sh ip between th e p in s an d th e selected voltage. Table 3.31

Pent ium II Volt age ID Definit ion

Processor Pins VID4

VID3

VID2

VID1

VID0

Volt age

0

1

1

1

1

Reserved

0

1

1

1

0

Reserved

0

1

1

0

1

Reserved

0

1

1

0

0

Reserved

0

1

0

1

1

Reserved

0

1

0

1

0

Reserved

0

1

0

0

1

Reserved

0

1

0

0

0

Reserved

0

0

1

1

1

Reserved

0

0

1

1

0

Reserved

0

0

1

0

1

1.80

0

0

1

0

0

1.85

0

0

0

1

1

1.90

0

0

0

1

0

1.95

0

0

0

0

1

2.00

0

0

0

0

0

2.05

1

1

1

1

1

No CPU

1

1

1

1

0

2.1

1

1

1

0

1

2.2

1

1

1

0

0

2.3

1

1

0

1

1

2.4

1

1

0

1

0

2.5

1

1

0

0

1

2.6

1

1

0

0

0

2.7

1

0

1

1

1

2.8

1

0

1

1

0

2.9

1

0

1

0

1

3.0

1

0

1

0

0

3.1

1

0

0

1

1

3.2

Processor Types

VID4

VID3

VID2

VID1

VID0

Volt age

1

0

0

1

0

3.3

1

0

0

0

1

3.4

1

0

0

0

0

3.5

0 = Processor pin connected to V ss. 1 = Open on processor.

To en su re th e system is read y for all Pen tiu m II p rocessor variation s, th e valu es in BOLD m u st be su p p orted . Most Pen tiu m II p rocessors ru n at 2.8v, with som e n ewer on es at 2.0v. Th e Pen tiu m II Mobile Mod u le is a Pen tiu m II for n otebooks th at in clu d es th e North Brid ge of th e h igh -p erform an ce 440BX ch ip set. Th is is th e first ch ip set on th e m arket th at allows 100MHz p rocessor bu s op eration , alth ou gh th at is cu rren tly n ot su p p orted in th e m obile version s. Th e 440BX ch ip set was released at th e sam e tim e as th e 350 an d 400MHz version s of th e Pen tiu m II; it is th e recom m en d ed m in im u m ch ip set for an y n ew Pen tiu m II m oth erboard p u rch ases. ◊◊ See “ M obile Pentium II,” p. 919

Pent ium II Fut ure. Th ere are several n ew d evelop m en ts on target for th e Pen tiu m II p rocessors. Th ere will be h igh er-en d , faster version s an d “SX” typ e low-en d version s com in g ou t (Celeron ). In tel’s goal is to sp read th e Pen tiu m II lin e to cover everyth in g from th e least exp en sive h om e system s to th e m ost exp en sive top -of-th e-lin e server system s, an d everyth in g in between , in clu d in g lap top s, n otebooks, an d p ortables. ’98 will be kn own as th e year th e Pen tiu m d ied , as In tel stop s p rod u ction an d m oves th e Pen tiu m II in to fill th e role of th e lower-en d system s. Pen tiu m II p rocessors at 333MHz an d u p were th e first m em bers of th e Pen tiu m II p rocessor fam ily to be based on th e “Desch u tes” core (0.25-m icron tech n ology). Desch u tes is th e in tern al cod e n am e for Pen tiu m II p rocessors u sin g th e 0.25-m icron p rocess tech n ology first seen on th e m obile Pen tiu m p rocessors. Th e n am e com es from a river in Oregon . Pen tiu m II p rocessors for Slot 1 ru n n in g at 450 an d 500MHz with a 100MHz system bu s for d esktop s an d en try-level servers an d workstation s will also be an n ou n ced in th e latter p art of ’98. All Pen tiu m II p rocessors for Slot 1 are cap able of on e- an d two-way p rocessin g. For th e Basic PC m arket segm en t (PCs p riced at u n d er $1,000), th e Pen tiu m II p rocessor fam ily in clu d es a version with n o L2 cach e, a 66MHz system bu s, an d op eratin g freq u en cies of at least 266MHz. Th ese are th e Celeron p rocessors, wh ich were released in early ’98, an d are based on th e Slot 1 form factor. Version s of th e Celeron PC th at in corp orate u p to a 256K L2 cach e resid en t on th e p rocessor (also referred to as “on -d ie”) will be available in th e secon d h alf of ’98.

151

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Chapter 3—M icroprocessor Types and Specifications

New Pen tiu m II Xeon p rocessors are com in g d u rin g m id -’98 for m id -ran ge to h igh -en d servers, an d workstation s are d esign ed with larger L2 cach e sizes, a fu ll-sp eed L2 cach e bu s, an d in creased cach eable ad d ress sp ace. Th e first Pen tiu m II Xeon p rocessor fam ily m em bers for Slot 2 will offer a clock sp eed of 400MHz an d a 100MHz system bu s. A Pen tiu m II Xeon p rocessor for Slot 2 will also be available at 450MHz by th e en d of th e year. L2 cach e sizes will start at 512KB an d are p lan n ed for u p to 1M an d 2M for th e Slot 2 version s. Pen tiu m II p rocessors for Slot 2 will offer glu eless (m ean in g n o extern al cu stom ch ip s) su p p ort for u p to fou r-way m u ltip rocessin g. Note th at th e Slot 2 Xeon p rocessors d o n ot rep lace th e Slot 1 p rocessors. Pen tiu m II Xeon p rocessors for Slot 2 will be targeted at th e m id -ran ge to h igh -en d server an d workstation m arket segm en ts, offerin g larger, fu ll-sp eed L2 cach es an d fou r-way m u ltip rocessor su p p ort. Pen tiu m II p rocessors for Slot 1 will con tin u e to be th e p rocessor u sed in th e bu sin ess an d h om e d esktop m arket segm en ts, an d for en try-level servers an d workstation s (sin gle an d d u al p rocessor system s). Notebook PCs got th eir first m obile version s of th e Pen tiu m II in th e first h alf of ’98. Th e Pen tiu m II p rocessor for m obile PCs com es in both Mobile m od u le an d Mobile cartrid ge form factors. Th e p ower con su m p tion of th e n ew Pen tiu m II p rocessors for m obile u se is com p arable to tod ay’s m obile Pen tiu m p rocessor with MMX tech n ology. Exp ect Mobile PII p rocessors at 300MHz an d beyon d by th e en d of ’98. Pseudo-Sixt h-Generat ion Processors Th ese are a class of p rocessor, th at featu re m an y sixth -gen eration cap abilities, bu t are in stead d esign ed for fifth -gen eration system s. Th ese p rocessors are n ot q u ite fu ll P6 level, becau se th ey lack th e DIB arch itectu re, wh ich is on e of th e key elem en ts of a tru e sixth gen eration p rocessor. Th e lack of DIB cap ability is tied to th eir backward com p atibility with th e Pen tiu m p rocessor. Design ed p rim arily as Pen tiu m rep lacem en ts, th ese p seu d oP6 p rocessors p lu g in to a P5 (Pen tiu m ) p rocessor socket an d as su ch are lim ited to Pen tiu m -class m oth erboard s. Th is lim its cach e an d m em ory p erform an ce to th at of th e fifth -gen eration p rocessors. Nexgen Nx586. Nexgen was fou n d ed by Vin od Dah m , wh o was on e of th e origin al arch itects of th e Pen tiu m p rocessor at In tel. At Nexgen , h e created th e Nx586, a p rocessor th at was fu n ction ally th e sam e as th e Pen tiu m bu t n ot p in com p atible. As su ch , it was always su p p lied with a m oth erboard ; in fact, it was n orm ally sold ered in . Nexgen d id n ot m an u factu re th e ch ip s or th e m oth erboard s th ey cam e in ; for th at th ey h ired IBM Microelectron ics. Later Nexgen was bou gh t by AMD, an d th e d esign of th e Nx586 was com bin ed with th e AMD K5 to create th e m ore p owerfu l AMD K6 p rocessor. Th e Nx586 h ad all th e stan d ard fifth -gen eration p rocessor featu res, su ch as su p erscalar execu tion with two in tern al p ip elin es an d a h igh p erform an ce in tegral Level 1 cach e with sep arate cod e an d d ata cach es. On e ad van tage was th at th e Nx586 in clu d es sep arate 16K in stru ction an d 16K d ata cach es com p ared to 8K each for th e Pen tiu m . Th ese cach es keep key in stru ction an d d ata close to th e p rocessin g en gin es to in crease overall system p erform an ce.

Processor Types

Th e Nx586 also in clu d ed bran ch p red iction cap abilities, wh ich are on e of th e h allm arks of a sixth -gen eration p rocessor. Bran ch p red iction m ean s th e p rocessor h as in tern al fu n ction s to p red ict p rogram flow to op tim ize th e in stru ction execu tion . Th e Nx586 p rocessor also featu red a RISC (Red u ced In stru ction Set Com p u ter) core. A tran slation u n it d yn am ically tran slates x86 in stru ction s in to RISC86 in stru ction s. Th ese RISC86 in stru ction s were sp ecifically d esign ed with d irect su p p ort for th e x86 arch itectu re wh ile obeyin g RISC p erform an ce p rin cip les. Th ey are th u s sim p ler an d easier to execu te th an th e com p lex x86 in stru ction s. Th is typ e of cap ability is an oth er featu re n orm ally fou n d on ly in P6 class p rocessors. Th e Nx586 was d iscon tin u ed after th e m erger with AMD an d th e featu res in it were m erged with th e AMD-K5 to create th e AMD-K6. AM D-K6. Th e AMD-K6 p rocessor is a h igh -p erform an ce p seu d o-sixth -gen eration p rocessor th at is p h ysically in stallable in a P5 (Pen tiu m ) m oth erboard . It d elivers p erform an ce levels som ewh ere between th e Pen tiu m an d Pen tiu m II p rocessor d u e to its u n iq u e h ybrid d esign . Becau se it is d esign ed to in stall in Socket 7, wh ich is a fifth -gen eration p rocessor socket an d m oth erboard d esign , it can n ot p erform q u ite as a tru e sixth -gen eration ch ip becau se th e Socket 7 arch itectu re severely lim its cach e an d m em ory p erform an ce. However, with th is p rocessor, AMD is givin g In tel a lot of com p etition in th e low- to m id -ran ge m arket, wh ere th e Pen tiu m is still p op u lar. Th e K6 p rocessor con tain s an in d u stry-stan d ard , h igh -p erform an ce im p lem en tation of th e n ew m u ltim ed ia in stru ction set (MMX), en ablin g a h igh level of m u ltim ed ia p erform an ce. AMD d esign ed th e K6 p rocessor to fit th e low-cost, h igh -volu m e Socket 7 in frastru ctu re. Th is en ables PC m an u factu rers an d resellers to sp eed tim e to m arket an d d eliver system s with an easy u p grad e p ath for th e fu tu re. AMD’s state-of-th e-art m an u factu rin g facility in Au stin , Texas (Fab 25), m akes th e AMD-K6 p rocessor u sin g AMD’s 0.35-m icron , five-m etal layer p rocess tech n ology. Newer version s are bein g m igrated to 0.25 m icron to in crease p rod u ction q u an tities d u e to red u ced d ie size, as well as to red u ce p ower con su m p tion . AMD-K6 Processor tech n ical featu res in clu d e: ■ Sixth -gen eration in tern al d esign , fifth -gen eration extern al in terface ■ In tern al RISC core, tran slates x86 to RISC in stru ction s ■ Su p erscalar p arallel execu tion u n its (seven ) ■ Dyn am ic execu tion ■ Bran ch p red iction ■ Sp ecu lative execu tion ■ Large 64K L1 cach e (32K in stru ction cach e p lu s 32K writeback d u al-p orted d ata cach e) ■ Bu ilt-in floatin g-p oin t u n it (FPU)

153

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■ In d u stry-stan d ard MMX in stru ction su p p ort ■ System Man agem en t Mod e (SMM) ■ Ceram ic Pin Grid Array (CPGA) Socket 7 d esign ■ Man u factu red u sin g a 0.35-m icron an d 0.25-m icron , five-layer d esign Th e AMD-K6 p rocessor arch itectu re is fu lly x86 bin ary cod e com p atible, wh ich m ean s it ru n s all In tel software, in clu d in g MMX in stru ction s. To m ake u p for th e lower L2 cach e p erform an ce of th e Socket 7 d esign , AMD h as beefed u p th e in tern al L1 cach e to 64K total, twice th e size of th e Pen tiu m II. Th is, p lu s th e d yn am ic execu tion cap ability, allows th e K6 to ou tp erform th e Pen tiu m an d com e close to th e Pen tiu m II in p erform an ce for a given clock rate. Both th e AMD-K5 an d AMD-K6 p rocessors are Socket 7 bu s-com p atible. However, certain m od ification s m ay be n ecessary for p rop er voltage settin g an d BIOS revision s. To en su re reliable op eration of th e AMD-K6 p rocessor, th e m oth erboard m u st m eet sp ecific voltage req u irem en ts. Th e AMD-K6-166, 200MHz op erates at 2.9v Core/ 3.3v I/ O, wh ile th e AMD-K6-233MHz at 3.2v Core/ 3.3v I/ O. Most old er sp lit-voltage m oth erboard s d efau lt to 2.8v Core/ 3.3v I/ O, wh ich is below sp ecification for th e AMD-K6 an d cou ld cau se erratic op eration . To work p rop erly, th e m oth erboard m u st h ave Socket 7 with a d u al-p lan e voltage regu lator su p p lyin g 2.9v or 3.2v (233MHz) to th e CPU core voltage (Vcc2) an d 3.3v for th e I/ O (Vcc3). Th e voltage regu lator m u st be cap able of su p p lyin g u p to 7.5A (9.5A for th e 233MHz) to th e p rocessor. W h en u sed with a 200MHz or slower p rocessor, th e voltage regu lator m u st m ain tain th e core voltage with in 145 m V of n om in al (2.9V+/ -145 m V). W h en u sed with a 233MHz p rocessor, th e voltage regu lator m u st m ain tain th e core voltage with in 100 m V of n om in al (3.2V+/ -100 m V). If th e m oth erboard h as a p oorly d esign ed voltage regu lator th at can n ot m ain tain th is p erform an ce, u n reliable op eration m ay resu lt. If th e CPU voltage exceed s th e absolu te m axim u m voltage ran ge, th e p rocessor m ay be p erm an en tly d am aged . Also n ote th at th e K6 can ru n h ot. En su re you r h eat sin k is secu rely fitted to th e p rocessor an d th e th erm ally con d u ctive grease or p ad is p rop erly ap p lied . Th e m oth erboard m u st h ave an AMD-K6 p rocessor-read y BIOS with su p p ort for th e K6 bu ilt in . Award h as th at su p p ort in th eir March 1, 1997 or later BIOS, AMI h ad K6 su p p ort in an y of th eir BIOS with CPU Mod u le 3.31 or later, an d Ph oen ix su p p orts th e K6 in version 4.0, release 6.0, or release 5.1 with bu ild d ates of 4/ 7/ 97 or later. Becau se th ese sp ecification s can be fairly com p licated , AMD keep s a list of m oth erboard s th at h ave been verified to work with th e AMD-K6 p rocessor on th eir W eb site. All th e m oth erboard s on th at list h ave been tested to work p rop erly with th e AMD K6, so u n less th ese req u irem en ts can be verified elsewh ere, it is recom m en d ed th at you on ly u se a m oth erboard from th at list with th e AMD-K6 p rocessor. Th e m u ltip lier, bu s sp eed , an d voltage settin gs for th e K6 are sh own in Table 3.32. You can id en tify wh ich AMD K6 you h ave by lookin g at th e m arkin gs on th is ch ip as sh own in Figu re 3.29.

Processor Types

Table 3.32

AM D K6 Speeds and Volt ages

CPU Speed

M ult iplier

Bus Speed

Volt age

166M Hz

2.5x

66M Hz

2.9v Core/ 3.3v I/ O

200M Hz

3.0x

66M Hz

2.9v Core/ 3.3v I/ O

233M Hz

3.5x

66M Hz

3.2v Core/ 3.3v I/ O

266M Hz

4.0x

66M Hz

2.2v Core/ 3.3v I/ O

320303M Hz

43.5x

66M Hz

23.2v Core/ 3.435vv I/ O

Old er m oth erboard s ach ieve th e 3.5x settin g by settin g ju m p ers for 1.5x. Th e 1.5x settin g for old er m oth erboard s eq u ates to a 3.5x settin g for th e AMD-K6 an d n ewer In tel p arts.

Name Voltage Major Revision Date Code Copyright

AMD

OPN AMD-K6-233APR

AMD-K6™ AMD-K6-233APR 3.3V CORE/3.3V I/O C 9710APB m c 1997 AMD

Designed for

Microsoft™ Windows™95

MALAY

I

AAAAA

Microsoft Logo

Top Mark

Case Temperature R=0˚C-70˚C Operating Voltage P=3.2V-3.4V (Core) /3.3135V-3.6V (I/O) Package Type A=321-pin CPGA Performance Rating -233 Family Core AMD-K6

FIG. 3.29 AMD K6 p rocessor m arkin gs. Un like Cyrix an d som e of th e oth er In tel com p etitors, AMD is a m an u factu rer an d a d esign er. Th is m ean s th ey d esign an d bu ild th eir ch ip s in th eir own fabs. Th e K6 h as 8.8 m illion tran sistors an d is bu ilt on a 0.35-m icron , five-layer p rocess. Th e d ie is 12.7m m on each sid e or abou t 162 sq u are m m . Like In tel, AMD is m igratin g to 0.25-m icron p rocess tech n ology an d beyon d . Th is will en able even h igh er yield s an d greater n u m bers of p rocessors. AMD h as recen tly won con tracts with In tel an d oth er h igh -en d system su p p liers, wh ich will give th em an ed ge on th e oth er In tel com p etitors. AMD h as d elivered m ore th an 50 m illion W in d ows-com p atible CPUs in th e last five years. Cyrix M ediaGX. Th e Cyrix Med iaGX is d esign ed for low-en d su b-$1,000 retail store system s th at m u st be h igh ly in tegrated an d low p riced . Th e Med iaGX in tegrates th e sou n d , grap h ics, an d m em ory con trol by p u ttin g th ese fu n ction s d irectly with in th e p rocessor. W ith all th ese fu n ction s p u lled “on ch ip ,” Med iaGX-based PCs are p riced lower th an oth er system s with sim ilar featu res. Th e Med iaGX p rocessor in tegrates th e PCI in terface, cou p led with au d io, grap h ics, an d m em ory con trol fu n ction s, righ t in to th e p rocessor u n it. As su ch , a system with th e Med iaGX d oesn ’t req u ire a costly grap h ics or sou n d card . Not on ly th at, bu t on th e m oth erboard level, th e Med iaGX an d its com p an ion ch ip rep lace th e p rocessor, North an d Sou th Brid ge ch ip s, th e m em ory con trol h ard ware, an d L2 cach e fou n d on com p etitive Pen tiu m board s. Fin ally, th e sim p lified PC d esign of th e Med iaGX, alon g with its

155

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Chapter 3—M icroprocessor Types and Specifications

low-p ower an d low-h eat ch aracteristics, allow th e OEM PC m an u factu rer to d esign a system in a sm aller form factor with a red u ced p ower-su p p ly req u irem en t. Th e Med iaGX p rocessor is n ot a Socket 7 p rocessor; in fact, it d oes n ot go in a socket at all—it is p erm an en tly sold ered in to its m oth erboard . Becau se of th e p rocessor’s h igh level of in tegration , m oth erboard s su p p ortin g Med iaGX p rocessors an d its com p an ion ch ip (Cx5510) are of a d ifferen t d esign th an con ven tion al Pen tiu m board s. As su ch , a system with th e Med iaGX p rocessor is m ore of a d isp osable system th an an u p grad able. On e will n ot be able to easily u p grad e m ost com p on en ts in th e system , bu t th at is often n ot im p ortan t in th e very low-en d m arket. If u p grad ability is im p ortan t, th en look elsewh ere. On th e oth er h an d , if you n eed th e lowest-p riced system p ossible, on e with th e Med iaGX m igh t fill th e bill. Th e Med iaGX is fu lly W in d ows-com p atible an d will ru n th e sam e software as an eq u ivalen t Pen tiu m . A u ser can exp ect a Med iaGX system to p rovid e eq u ivalen t p erform an ce as a given Pen tiu m system at th e sam e m egah ertz. Th e d ifferen ce with th e Med iaGX is th at th is p erform an ce level is ach ieved at a m u ch lower cost. Becau se th e Med iaGX p rocessor is sold ered in to th e m oth erboard an d req u ires a cu stom ch ip set, it is on ly sold in a com p lete m oth erboard form . Th ere is also an im p roved MMX-en h an ced Med iaGX p rocessor th at featu res MPEG1 su p p ort, Microsoft PC97 com p lian ce for Plu g-an d -Play access, in tegrated gam e p ort con trol, an d AC97 au d io com p lian ce. It su p p orts W in d ows 95 an d DOS-based gam es, an d MMX software as well. Su ch system s will also in clu d e two u n iversal serial bu s (USB) p orts, wh ich will accom m od ate th e n ew gen eration of USB p erip h erals su ch as p rin ters, scan n ers, joysticks, cam eras, an d m ore. Th e Med iaGX p rocessor is offered at 166 an d 180MHz, wh ile th e MMX-en h an ced Med iaGX p rocessor is available at 200MHz with h igh er m egah ertz sp eed s available later in ’98. Com p aq is u sin g th e MMX-en h an ced Med iaGX p rocessor in its Presario 1220 n otebook PCs, wh ich is a m ajor con tract win for Cyrix. Oth er retailers an d resellers are offerin g low-en d , low-cost system s in retail stores n ation wid e. Cyrix/ IBM 6x86 and 6x86M X. Th e Cyrix 6x86 p rocessor fam ily con sists of th e n owd iscon tin u ed 6x86 an d th e n ewer 6x86MX p rocessors. Th ey are sim ilar to th e AMD-K5 an d K6 in th at th ey offer sixth -gen eration in tern al d esign s in a fifth -gen eration P5 Pen tiu m com p atible Socket 7 exterior. Th e Cyrix 6x86 an d 6x86MX (ren am ed MII) p rocessors in corp orate two op tim ized su p erp ip elin ed in teger u n its an d an on -ch ip Floatin g-Poin t Un it. Th ese p rocessors in clu d e th e d yn am ic execu tion cap ability th at is th e h allm ark of a sixth -gen eration CPU d esign . Th is in clu d es bran ch p red iction an d sp ecu lative execu tion . Th e 6x86MX/ MII p rocessor is com p atible with MMX tech n ology to ru n th e latest MMX gam es an d m u ltim ed ia software. W ith its en h an ced m em ory-m an agem en t u n it, a 64K

Processor Types

in tern al cach e, an d oth er ad van ced arch itectu ral featu res, th e 6x86MX p rocessor ach ieves h igh er p erform an ce an d offers better valu e th an com p etitive p rocessors. Featu res an d ben efits of th e 6x86 p rocessors in clu d e: ■ Superscalar Architecture. Two p ip elin es to execu te m u ltip le in stru ction s in p arallel. ■ Branch Prediction. Pred icts with h igh accu racy th e n ext in stru ction s n eed ed . ■ Speculative Execution. Allows th e p ip elin es to con tin u ou sly execu te in stru ction s followin g a bran ch with ou t stallin g th e p ip elin es. ■ Out-of-Order Com pletion. Lets th e faster in stru ction exit th e p ip elin e ou t of ord er, savin g p rocessin g tim e with ou t d isru p tin g p rogram flow. Th e 6x86 in corp orates two cach es: a 16-K d u al-p orted u n ified cach e an d a 256-byte in stru ction lin e cach e. Th e u n ified cach e is su p p lem en ted with a sm all q u arter-K sized h igh -sp eed , fu lly associative in stru ction lin e cach e. Th e im p roved 6x86MX d esign q u ad ru p les th e in tern al cach e size to 64K, wh ich sign ifican tly im p roves p erform an ce. Th e 6x86MX also in clu d es th e 57 MMX in stru ction s th at sp eed u p th e p rocessin g of certain com p u tin g-in ten sive loop s fou n d in m u ltim ed ia an d com m u n ication ap p lication s. All 6x86 p rocessors featu re su p p ort for System Man agem en t Mod e (SMM). Th is p rovid es an in terru p t th at can be u sed for system p ower m an agem en t or software tran sp aren t em u lation of I/ O p erip h erals. Ad d ition ally, th e 6x86 su p p orts a h ard ware in terface th at allows th e CPU to be p laced in to a low-p ower su sp en d m od e. Th e 6x86 is com p atible with x86 software an d all p op u lar x86 op eratin g system s, in clu d in g W in d ows 95/ 98, W in d ows, W in d ows NT, OS/ 2, DOS, Solaris, an d UNIX. Ad d ition ally, th e 6x86 p rocessor h as been certified W in d ows 95 com p atible by Microsoft. As with th e AMD-K6, th ere are som e u n iq u e m oth erboard req u irem en ts for th e 6x86 p rocessors. Cyrix m ain tain s a list of recom m en d ed m oth erboard s on th eir W eb site th at sh ou ld be con su lted if you are con sid erin g in stallin g on e of th ese ch ip s in a board . W h en in stallin g or con figu rin g a system with th e 6x86 p rocessors, you h ave to set th e correct m oth erboard bu s sp eed an d m u ltip lier settin gs. Th e Cyrix p rocessors are n u m bered based on a P-ratin g scale, wh ich is n ot th e sam e as th e tru e m egah ertz clock sp eed of th e p rocessor. Th e followin g table sh ows th e correct an d tru e sp eed settin gs for th e Cyrix 6x86 p rocessors:

157

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Chapter 3—M icroprocessor Types and Specifications

Processor/ P-rat ing

Bus Speed

M ult iplier

Act ual Speed

6x86-PR120+

50M Hz

2x

100M Hz

6x86-PR133+

55M Hz

2x

110M Hz

6x86-PR150+

60M Hz

2x

120M Hz

6x86-PR166+

66M Hz

2x

133M Hz

6x86-PR200+

75M Hz

2x

150M Hz

6x86M X-PR166

60M Hz

2.5x

150M Hz

6x86M X-PR200

66M Hz

2.5x

166M Hz

6x86M X-PR233

75M Hz

2.5x

188M Hz

6x86M X-PR233

66M Hz

3.0x

200M Hz

6x86M X-PR266

75M Hz

3.0x

225M Hz

6x86M X-PR266

66M Hz

3.5x

233M Hz

6x86M X-PR300

75M Hz

3.5x

263M Hz

6x86M X-PR300

66M Hz

4.0x

266M Hz

Note th at d u e to th e u se of th e P-ratin g system , th e actu al sp eed of th e ch ip is n ot th e sam e n u m ber at wh ich it is ad vertised . For exam p le, th e 6x86MX-PR300 is n ot a 300MHz ch ip ; it actu ally ru n s at on ly 263MHz or 266MHz, d ep en d in g on exactly h ow th e m oth erboard bu s sp eed an d CPU clock m u ltip liers are set. Cyrix says it ru n s as fast as a 300MHz Pen tiu m , h en ce th e P-ratin g. Person ally, I wish th ey wou ld ju st label th e ch ip s at th e correct sp eed , an d th en say th at it ru n s faster th an a Pen tiu m at th e sam e sp eed . To in stall th e 6x86 p rocessors in a m oth erboard , you also h ave to set th e correct voltage. Norm ally, th e m arkin gs on top of th e ch ip in d icate wh ich voltage settin g is ap p rop riate. Variou s version s of th e 6x86 ru n at 3.52v (u se VRE settin g), 3.3v (VR settin g), or 2.8v (MMX) settin gs. Th e MMX version s u se th e stan d ard sp lit-p lan e 2.8v core 3.3v I/ O settin gs. P7 ( 786) Sevent h-Generat ion Processors W h at is com in g after th e Pen tiu m II? Th e n ext p rocessor is cod e-n am ed eith er P7 or Merced . In tel h as in d icated th at th e n ew 64-bit Merced p rocessor will be available in sam p le volu m es in 1999, with p lan n ed p rod u ction volu m es m ovin g from 1999 to m id -2000. Th e Merced p rocessor will be th e first p rocessor in In tel’s IA-64 (In tel Arch itectu re 64-bit) p rod u ct fam ily, an d will in corp orate in n ovative p erform an ce-en h an cin g arch itectu re tech n iq u es, su ch as p red ication an d sp ecu lation . M erced. Th e m ost cu rren t gen eration of p rocessor is th e P6, wh ich was first seen in th e Pen tiu m Pro in trod u ced in Novem ber of 1995, an d m ost recen tly fou n d in th e latest Pen tiu m II p rocessors. Obviou sly, th en , th e n ext gen eration p rocessor from In tel will be called th e P7.

Processor Types

Alth ou gh th e Merced p rocessor p rogram is still far from bein g released , th e p rogram h as m ad e con sid erable p rogress to d ate accord in g to In tel, in clu d in g: ■ Defin ition of th e 64-bit in stru ction set arch itectu re with Hewlett-Packard . ■ Com p letion of th e fu n d am en tal m icroarch itectu re d esign . ■ Com p letion of fu n ction al m od el an d in itial p h ysical layou t. ■ Com p letion of m ech an ical an d th erm al d esign an d valid ation with system ven d ors. ■ Sp ecification s com p lete an d d esign s u n d erway for ch ip set an d oth er system com p on en ts. ■ Progress on 64-bit com p iler d evelop m en t an d IA-64 software d evelop m en t kits. ■ Real-tim e software em u lation cap ability to sp eed th e d evelop m en t of IA-64 op tim ized software. ■ Mu ltip le op eratin g system s ru n n in g in Merced sim u lation en viron m en t. ■ All req u ired p latform com p on en ts p lan n ed for align m en t with 1999 Merced p rocessor sam p les for in itial system assem bly an d testin g. In tel’s IA-64 p rod u ct fam ily is exp ected to exp an d th e cap abilities of th e In tel arch itectu re to ad d ress th e h igh -p erform an ce server an d workstation m arket segm en ts. A variety of in d u stry p layers—am on g th em lead in g workstation an d server-system m an u factu rers, lead in g op eratin g system ven d ors, an d d ozen s of in d ep en d en t software ven d ors—h ave alread y p u blicly com m itted th eir su p p ort for th e Merced p rocessor an d th e IA-64 p rod u ct fam ily. As with p reviou s n ew p rocessor in trod u ction s, th e P7 will n ot rep lace th e P6 or P5, at least n ot at first. It will featu re an all-n ew d esign th at will be in itially exp en sive an d will be fou n d on ly in th e h igh est en d system s su ch as file servers or workstation s. In tel exp ects th e P7 will becom e th e m ain stream p rocessor by th e year 2004 an d th at th e P6 will likely be fou n d in low-en d system s on ly. In tel is alread y d evelop in g an even m ore ad van ced P7 p rocessor, d u e to sh ip in 2001, th at will be sign ifican tly faster th an Merced . In tel an d Hewlett-Packard began join tly workin g on th e P7 p rocessor in 1994. It was th en th at th ey began a collaboration on wh at will even tu ally becom e In tel’s n ext-gen eration CPU. Alth ou gh we d on ’t kn ow exactly wh at th e n ew CPU will be like, In tel h as begu n slowly releasin g in form ation abou t th e n ew p rocessor to p rep are th e in d u stry for its even tu al release. In October of 1997, m ore th an th ree years after th ey first d isclosed th eir p lan to work togeth er on a n ew m icrop rocessor arch itectu re, In tel an d HP officially an n ou n ced som e of th e n ew p rocessor’s tech n ical d etails.

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Th e first ch ip to im p lem en t th e P7 arch itectu re won ’t sh ip u n til 1999. Merced will be th e first m icrop rocessor th at will be based on th e 64-bit, n ext-gen eration In tel Arch itectu re64 (IA-64) sp ecification . IA-64 is a com p letely d ifferen t p rocessor d esign , wh ich will u se a con cep t called Very Lon g In stru ction W ord s (VLIW ), in stru ction p red iction , bran ch elim in ation , sp ecu lative load in g, an d oth er ad van ced p rocesses for en h an cin g p arallelism from p rogram cod e. Th e n ew ch ip will featu re elem en ts of both CISC an d RISC d esign . Th ere is also a n ew arch itectu re In tel calls Exp licitly Parallel In stru ction Com p u tin g (EPIC), wh ich will let th e p rocessor execu te p arallel in stru ction s—several in stru ction s at th e sam e tim e. In th e P7, th ree in stru ction s will be en cod ed in on e 128-bit word , so th at each in stru ction h as a few m ore bits th an tod ay’s 32-bit in stru ction s. Th e extra bits let th e ch ip ad d ress m ore registers an d tell th e p rocessor wh ich in stru ction s to execu te in p arallel. Th is ap p roach sim p lifies th e d esign of p rocessors with m an y p arallel-execu tion u n its an d sh ou ld let th em ru n at h igh er clock rates. In oth er word s, besid es bein g able to execu te several in stru ction s in p arallel with in th e ch ip , th e P7 will h ave th e cap ability to be lin ked to oth er P7 ch ip s in a p arallel p rocessin g en viron m en t. Besid es h avin g n ew featu res an d ru n n in g a com p letely n ew 64-bit in stru ction set, In tel an d HP p rom ise fu ll backward com p atibility between th e Merced , th e cu rren t 32-bit In tel x86 software, an d even HP’s own PA-RISC software. Th e P7 will in corp orate th ree d ifferen t kin d s of p rocessors in on e an d th erefore be able to ru n ad van ced IA-64 p arallelp rocessin g software an d IA-32 W in d ows an d HP-RISC UNIX p rogram s at th e sam e tim e. In th is way, Merced will su p p ort 64-bit in stru ction s wh ile retain in g com p atibility with tod ay’s 32-bit ap p lication s. Th is backward com p atibility will be a p owerfu l sellin g p oin t. To u se th e IA-64 in stru ction s, p rogram s will h ave to be recom p iled for th e n ew in stru ction set. Th is is sim ilar to wh at h ap p en ed in 1985, wh en In tel in trod u ced th e 80386, th e first 32-bit PC p rocessor. Th e 386 was to give IBM an d Microsoft a p latform for an ad van ced 32-bit op eratin g system th at tap p ed th is n ew p ower. To en su re im m ed iate accep tan ce, th e 386 an d fu tu re 32-bit p rocessors still ran 16-bit cod e. To take ad van tage of th e 32-bit cap ability first fou n d in th e 386, n ew software wou ld h ave to be written . Un fortu n ately, software evolves m u ch m ore slowly th an h ard ware. It took Microsoft a fu ll 10 years after th e 386 d ebu ted to release W in d ows 95, th e first m ain stream 32-bit op eratin g system for In tel p rocessors. In tel claim s th at won ’t h ap p en with th e P7: Microsoft h as alread y begu n workin g on a 64-bit version of W in d ows NT for Merced . Desp ite th at, it will likely take several years before th e software m arket sh ifts to 64-bit op eratin g system s an d software. Th e in stalled base of 32-bit p rocessors is sim p ly too great, an d th e backward -com p atible 32-bit m od e of th e P7 will allow it to ru n 32-bit software very well, becau se it will be d on e in th e h ard ware rath er th an th rou gh software em u lation .

Processor Upgrades

Merced will u se 0.18-m icron tech n ology, wh ich is on e gen eration beyon d th e 0.25m icron p rocess u sed tod ay. Th is will allow th em to p ack m an y m ore tran sistors in th e sam e sp ace. Early p red iction s h ave th e Merced sp ortin g between 10 an d 12 m illion tran sistors! In tel’s in itial goal with IA-64 is to d om in ate th e workstation an d server m arkets, com p etin g with ch ip s su ch as th e Digital Alp h a, Su n Sp arc, an d Motorola PowerPC. Microsoft will p rovid e a version of W in d ows NT th at ru n s on th e P7, an d Su n p lan s to p rovid e a version of Solaris, its UNIX op eratin g-system software, to su p p ort Merced as well. NCR h as alread y an n ou n ced th at it will bu ild Merced -p owered system s th at u se Solaris.

Processor Upgrades Sin ce th e 486, p rocessor u p grad es h ave been relatively easy for m ost system s. W ith th e 486 an d later p rocessors, In tel d esign ed in th e cap ability to u p grad e by d esign in g stan d ard sockets th at wou ld take a variety of p rocessors. Th u s, if you h ave a m oth erboard with Socket 3, you can p u t virtu ally an y 486 p rocessor in it; if you h ave a Socket 7 m oth erboard , it sh ou ld be able to accep t virtu ally an y Pen tiu m p rocessor. To m axim ize you r m oth erboard , you can alm ost always u p grad e to th e fastest p rocessor you r p articu lar board will su p p ort. Norm ally, th at can be d eterm in ed by th e typ e of socket on th e m oth erboard . Table 3.33 lists th e fastest p rocessor u p grad e solu tion for a given p rocessor socket. Table 3.33

M axim um Processor Speeds by Socket

Socket Type

Fast est Processor Support ed

Socket 1

5x86-133M Hz with 3.3v adapter

Socket 2

5x86-133M Hz with 3.3v adapter

Socket 3

5x86-133M Hz

Socket 4

Pentium OverDrive 133M Hz

Socket 5

Pentium M M X 233M Hz or AM D K6 with 2.8v adapter

Socket 7

Pentium M M X 233M Hz, AM D K6

Socket 8

Pentium Pro OverDrive

Slot 1

Pentium II 333M Hz (66M Hz bus)

Slot 1

Pentium II 450M Hz (100M Hz bus)

Slot 2

Pentium II Xeon 450M Hz (100M Hz bus)

For exam p le, if you r m oth erboard h as a Pen tiu m Socket 5, th en you can in stall a Pen tiu m MMX 233MHz p rocessor with a 2.8v voltage regu lator ad ap ter, or op tion ally an AMD K6, also with a voltage regu lator ad ap ter. If you are lu cky en ou gh to h ave Socket 7, th en you r m oth erboard sh ou ld be able to su p p ort th e lower voltage Pen tiu m MMX or AMD K6 d irectly with ou t an y ad ap ters. Rath er th an p u rch asin g p rocessors an d ad ap ters sep arately, I n orm ally recom m en d you p u rch ase th em togeth er in a m od u le from com p an ies su ch as Kin gston or Evergreen (see Ap p en d ix A).

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Up grad in g th e p rocessor can in som e cases d ou ble th e p erform an ce of a system , su ch as if you were goin g from a Pen tiu m 100 to an MMX 233. However, if you alread y h ave a Pen tiu m 233, th en you alread y h ave th e fastest p rocessor th at goes in th at socket. In th at case, you really sh ou ld look in to a com p lete m oth erboard ch an ge, wh ich wou ld let you u p grad e to a Pen tiu m II p rocessor at th e sam e tim e. If you r ch assis d esign is n ot p rop rietary an d you r system u ses an in d u stry stan d ard Baby AT or ATX m oth erboard d esign , I n orm ally recom m en d ch an gin g th e m oth erboard an d p rocessor rath er th an tryin g to fin d an u p grad e p rocessor th at will work with you r existin g board . OverDrive Processors In tel h as stated th at all its fu tu re p rocessors will h ave OverDrive version s available for u p grad in g at a later d ate. Often th ese are rep ackaged version s of th e stan d ard p rocessors, som etim es in clu d in g n ecessary voltage regu lators an d fan s. Usu ally th ey are m ore exp en sive th an oth er solu tion s, bu t th ey are worth a look. OverDrive Processor Inst allat ion You can u p grad e m an y system s with an OverDrive p rocessor. Th e m ost d ifficu lt asp ect of th e in stallation is sim p ly h avin g th e correct OverDrive p rocessor for you r system . Cu rren tly, 486 Pen tiu m OverDrive p rocessors are available for rep lacin g 486SX an d 486DX p rocessors. Pen tiu m an d Pen tiu m -MMX OverDrive p rocessors are also available for som e Pen tiu m p rocessors. Un fortu n ately, In tel n o lon ger offers u p grad e ch ip s for 168-p in socket board s. Th e followin g table lists th e cu rren t OverDrive p rocessors offered by In tel. Processor Designat ion

Replaces

Socket

Heat Sink

486 Pentium OverDrive

486SX/ DX/ SX2/ DX2

Socket 2 or 3

Active

120/ 133 Pentium OverDrive

Pentium 60/ 66

Socket 4

Active

200M Hz Pentium OverDrive with M M X

Pentium 75/ 90/ 100

Socket 5/ 7

Active

Up grad es th at u se th e n ewer OverDrive ch ip s for Sockets 2–7 are likely to be m u ch easier becau se th ese ch ip s alm ost always go in to a ZIF socket an d th erefore req u ire n o tools. In m ost cases, sp ecial con figu ration p in s in th e socket an d on th e n ew OverDrive ch ip s take care of an y ju m p er settin gs for you . In som e cases, h owever, you m ay h ave to set som e ju m p ers on th e m oth erboard to con figu re th e socket for th e n ew p rocessor. If you h ave an SX system , you also will h ave to ru n you r system ’s Setu p p rogram becau se you m u st in form th e CMOS m em ory th at a m ath cop rocessor is p resen t. (Som e DX system s also req u ire you to ru n th e setu p p rogram .) In tel p rovid es a u tility d isk th at in clu d es a test p rogram to verify th at th e n ew ch ip is in stalled an d fu n ction in g correctly. After verifyin g th at th e in stallation fu n ction s correctly, you h ave n oth in g m ore to d o. You d o n ot n eed to recon figu re an y of th e software on you r system for th e n ew ch ip . Th e on ly d ifferen ce th at you sh ou ld n otice is th at everyth in g works n early twice as fast as it d id before th e u p grad e.

Processor Upgrades

OverDrive Com pat ibilit y Problem s Alth ou gh you can u p grad e m an y old er 486SX or 486DX system s with th e OverDrive p rocessors, som e excep tion s exist. Fou r factors can m ake an OverDrive u p grad e d ifficu lt or im p ossible: ■ BIOS rou tin es th at u se CPU-d ep en d en t tim in g loop s ■ Lack of clearan ce for th e OverDrive h eat sin k (25MHz an d faster) ■ In ad eq u ate system coolin g ■ A 486 CPU th at is sold ered in rath er th an socketed In som e rare cases, p roblem s m ay occu r in system s th at sh ou ld be u p grad able bu t are n ot. On e of th ese p roblem s is related to th e ROM BIOS. A few 486 system s h ave a BIOS th at regu lates h ard ware op eration s by u sin g tim in g loop s based on h ow lon g it takes th e CPU to execu te a series of in stru ction s. W h en th e CPU su d d en ly is ru n n in g twice as fast, th e p rescribed tim in g in terval is too sh ort, resu ltin g in im p rop er system op eration or even h ard ware locku p s. Fortu n ately, you u su ally can solve th is p roblem by u p grad in g th e system ’s BIOS. In tel offers BIOS u p d ates with th e OverDrive p rocessors it sells. An oth er p roblem is related to p h ysical clearan ce. All OverDrive ch ip s h ave h eat sin ks glu ed or fasten ed to th e top of th e ch ip . Th e h eat sin k can ad d 0.25 to 1.2 in ch es to th e top of th e ch ip . Th is extra h eigh t can in terfere with oth er com p on en ts in th e system , esp ecially in sm all d esktop system s an d p ortables. Solu tion s to th is p roblem m u st be d eterm in ed on a case-by-case basis. You can som etim es relocate an exp an sion card or d isk d rive, or even m od ify th e ch assis sligh tly to in crease clearan ce. In som e cases, th e in terferen ce can n ot be resolved , leavin g you on ly th e op tion of ru n n in g th e ch ip with ou t th e h eat sin k. Need less to say, rem ovin g th e glu ed -on h eat sin k will at best void th e warran ty p rovid ed by In tel an d will at worst d am age th e ch ip or th e system d u e to overh eatin g. I d o n ot recom m en d rem ovin g th e h eat sin k. Th e OverDrive ch ip s can gen erate u p to twice th e h eat of th e ch ip s th at th ey rep lace. Even with th e active h eat sin k/ fan bu ilt in to th e faster OverDrive ch ip s, som e system s d o n ot h ave en ou gh airflow or coolin g cap ability to keep th e OverDrive ch ip with in th e p rescribed safe op eratin g-tem p eratu re ran ge. Sm all d esktop system s or p ortables are m ost likely to h ave coolin g p roblem s. Un fortu n ately, on ly p rop er testin g can in d icate wh eth er a system will h ave a h eat p roblem . For th is reason , In tel h as been ru n n in g an exten sive test p rogram to certify system s th at are p rop erly d esign ed to h an d le an OverDrive u p grad e. Fin ally, som e system s h ave a p rop rietary d esign th at p reclu d es th e u se of th e OverDrive p rocessor. Th is wou ld , for exam p le, in clu d e virtu ally all p ortable, lap top , or n otebook com p u ters th at h ave th eir p rocessor sold ered in to th e m oth erboard . Som e of th e n ewer on es u se th e In tel Mobile Mod u le, wh ich is p oten tially u p grad able. To clarify wh ich system s are tested to be u p grad able with ou t p roblem s, In tel h as com p iled an exten sive list of com p atible system s. To d eterm in e wh eth er a PC is u p grad able

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with an OverDrive p rocessor, con tact In tel via its FaxBack system (see th e ven d or list in Ap p en d ix A) an d ask for th e OverDrive Processor Com p atibility Data d ocu m en ts. Th e in form ation is also available on In tel’s W eb site. Th ese d ocu m en ts list th e system s th at h ave been tested with th e OverDrive p rocessors an d in d icate wh ich oth er ch an ges you m ay h ave to m ake for th e u p grad e to work (for exam p le, a n ewer ROM BIOS or Setu p p rogram ).

Not e If your system is not on the list, the warranty on the OverDrive processor is void. Intel recommends OverDrive upgrades only for systems that are in the compatibility list. The list also includes notes about systems that may require a ROM upgrade, a jumper change, or perhaps a new setup disk.

After u p grad in g you r system , I su ggest ru n n in g a d iagn ostic p rogram su ch as th e Norton Utilities to verify th at th e n ew p rocessor is ru n n in g correctly. ◊◊ See “ Norton Utilities Diagnostics,” p. 993

Processor Benchm arks Peop le love to kn ow h ow fast (or slow) th eir com p u ters are. W e h ave always been in terested in sp eed ; it is h u m an n atu re. To h elp u s with th is q u est, variou s ben ch m ark test p rogram s can be u sed to m easu re d ifferen t asp ects of p rocessor an d / or system p erform an ce. Alth ou gh n o sin gle n u m erical m easu rem en t can com p letely d escribe th e p erform an ce of a com p lex d evice like a p rocessor or a com p lete PC, ben ch m arks can be u sefu l tools for com p arin g d ifferen t com p on en ts an d system s. However, th e on ly tru ly accu rate way to m easu re you r system ’s p erform an ce is to test th e system u sin g th e actu al software ap p lication s you u se. Th ou gh you th in k you m ay be testin g on e com p on en t of a system , often oth er p arts of th e system can h ave an effect. It is in accu rate to com p are system s with d ifferen t p rocessors, for exam p le, if th ey also h ave d ifferen t am ou n ts or typ es of m em ory, d ifferen t h ard d isks, vid eo card s, an d so on . All th ese th in gs an d m ore will skew th e test resu lts. Ben ch m arks can n orm ally be d ivid ed in to two kin d s: com p on en t or system tests. Com p on en t ben ch m arks m easu re th e p erform an ce of sp ecific p arts of a com p u ter system , su ch as a p rocessor, h ard d isk, vid eo card , or CD-ROM d rive, wh ile system ben ch m arks typ ically m easu re th e p erform an ce of th e en tire com p u ter system ru n n in g a given ap p lication or test su ite. Ben ch m arks are, at m ost, on ly on e kin d of in form ation th at you m ay u se d u rin g th e u p grad in g or p u rch asin g p rocess. You are best served by testin g th e system u sin g you r own set of software op eratin g system s an d ap p lication s, an d in th e con figu ration you will be ru n n in g.

Processor Upgrades

Th ere are several com p an ies th at sp ecialize in ben ch m ark tests an d software. Th e followin g table lists th e com p an y an d th e ben ch m arks th ey are kn own for. You can con tact th ese com p an ies via th e in form ation in th e ven d or list in Ap p en d ix A. Com pany

Benchm arks Published

Benchm ark Type

Intel

iCOM P index 2.0

Processor

Intel

iCOM P index 2.0 Intel M edia Benchmark

System

Business Applications Performance Corporation (BAPCo)

SYSmark/ NT

System

Business Applications Performance Corporation for Windows (BAPCo)

SYSmark/ NT, SYSmark95

System

Standard Performance Evaluation Corporation (SPEC)

SPECint95

Processor

Standard Performance Evaluation Corporation (SPEC)

SPECint95, SPECfp95

Processor

Ziff-Davis Benchmark Operation

CPUmark32

Processor

Ziff-Davis Benchmark Operation

Winstone 98

System

Ziff-Davis Benchmark Operation

WinBench 98

System

Ziff-Davis Benchmark Operation

CPUmark32, Winstone 98, WinBench 98, 3D WinBench 98

System

Symantec Corporation

Norton SI32

Processor

Symantec Corporation

Norton SI32, Norton M ultimedia Benchmark

System

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4

Chapter 4

M otherboards and Buses

W ith ou t a d ou bt, th e m ost im p ortan t com p on en t in a PC system is th e m ain board or m oth erboard . Som e com p an ies refer to th e m oth erboard as a system board or p lan ar. Th e term s m otherboard, m ain board, system board, an d planar are in terch an geable. In th is ch ap ter, we will exam in e th e d ifferen t typ es of m oth erboard s available an d th ose com p on en ts u su ally con tain ed on th e m oth erboard an d m oth erboard in terface con n ectors.

M ot herboard Form Fact ors Th ere are several com m on form factors u sed for PC m oth erboard s. Th e form factor refers to th e p h ysical d im en sion s an d size of th e board , an d d ictates wh at typ e of case th e board will fit in to. Som e are tru e stan d ard s (m ean in g th at all board s with th at form factor are in terch an geable), wh ile oth ers are n ot stan d ard ized en ou gh to allow for in terch an geability. Un fortu n ately th ese n on stan d ard form factors p reclu d e an y easy u p grad e, wh ich gen erally m ean s th ey sh ou ld be avoid ed . Th e PC m oth erboard form factors gen erally available in clu d e th e followin g: ■ Baby-AT

■ NLX

■ Fu ll-size AT

■ Backp lan e System s

■ LPX

■ Prop rietary Design s

■ ATX Baby-AT Th e first p op u lar PC m oth erboard was, of cou rse, th e origin al IBM PC released in 1981. Figu re 20.3 sh ows h ow th is board looked . IBM followed th e PC with th e XT m oth erboard in 1983, wh ich h ad th e sam e basic sh ap e as th e PC board , bu t it h ad eigh t slots in stead of on ly five, an d th e slots were sp aced 0.8 in ch ap art in stead of 1 in ch ap art as in th e PC (see Figu re 20.6). Th e XT also d eleted th e weird cassette p ort in th e back, wh ich was su p p osed to be u sed to save BASIC p rogram s on cassette tap e in stead of th e m u ch m ore exp en sive (at th e tim e) flop p y d rive.

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Chapter 4—M otherboards and Buses

◊◊ See “ An Introduction to the PC (5150),” p. 1101 ◊◊ See “ An Introduction to the XT (5160),” p. 1115

Th e m in or d ifferen ces in th e slot p osition s an d th e n ow lon esom e keyboard con n ector on th e back req u ired a m in or red esign of th e case. Th is m oth erboard becam e very p op u lar an d m an y oth er PC m oth erboard m an u factu rers of th e d ay cop ied IBM’s XT d esign an d p rod u ced sim ilar board s. By th e tim e m ost of th ese clon es or com p atible system s cam e ou t, IBM h ad released th eir AT system , wh ich in itially u sed a larger form factor m oth erboard . Du e to th e ad van ces in circu it m in iatu rization , th ese com p an ies fou n d th ey cou ld fit all th e ad d ition al circu its fou n d on th e 16-bit AT m oth erboard in to th e XT m oth erboard form factor. Rath er th an call th ese board s XT-sized , wh ich m ay h ave m ad e p eop le th in k th ey were 8-bit d esign s, th ey referred to th em as Baby-AT, wh ich en d ed u p m ean in g an XT-sized board with AT m oth erboard d esign featu res (16-bit or greater). Th u s, th e Baby-AT form factor is essen tially th e sam e as th e origin al IBM XT m oth erboard . Th e on ly d ifferen ce is a sligh t m od ification in on e of th e screw h ole p osition s to fit in to an AT-style case (see Figu re 4.1). Th ese m oth erboard s also h ave sp ecific p lacem en t of th e keyboard an d slot con n ectors to m atch th e h oles in th e case. Note th at virtu ally all fu ll-size AT an d Baby-AT m oth erboard s u se th e stan d ard 5-p in DIN typ e con n ector for th e keyboard . Baby-AT m oth erboard s can be u sed to rep lace fu ll-sized AT m oth erboard s an d will fit in to a n u m ber of d ifferen t case d esign s. Becau se of th eir flexibility, from 1983 in to early 1996 th e Baby-AT form factor was th e m ost p op u lar m oth erboard typ e. Startin g in m id -1996, Baby-AT h as been rep laced by th e su p erior ATX m oth erboard d esign , wh ich is n ot d irectly in terch an geable. Most n ew system s sold sin ce 1996 h ave u sed th e im p roved ATX d esign an d Baby-AT is gettin g h ard er an d h ard er to com e by. Figu re 4.1 sh ows th e d im en sion s an d layou t of a Baby-AT m oth erboard . ◊◊ See “ Power Supply Form Factors,” p. 393

An y case th at accep ts a fu ll-sized AT m oth erboard will also accep t a Baby-AT d esign . Sin ce its d ebu t in th e IBM XT m oth erboard in 1983 lastin g well in to 1996, th e Baby-AT m oth erboard form factor h as been by far th e m ost p op u lar d esign . I can get a PC m oth erboard with virtu ally an y p rocessor from th e origin al 8088 to th e fastest Pen tiu m II in th is d esign . As su ch , system s with Baby-AT m oth erboard s are virtu ally by d efin ition u p grad able system s. Becau se an y Baby-AT m oth erboard can be rep laced with an y oth er Baby-AT m oth erboard , th is is an in terch an geable d esign . Un til 1996 I h ad recom m en d ed to m ost p eop le th at th ey m ake su re an y PC system th ey p u rch ased h ad a Baby-AT m oth erboard . Th ey wou ld som etim es say, “I’ve n ever h eard of th at bran d before.” “Of cou rse,” I’d tell th em , “th at’s n ot a bran d , bu t a sh ap e!” Th e p oin t bein g th at if th ey h ad a Baby-AT board in th eir system , wh en a year or so goes by an d th ey lon ged for som eth in g faster, it wou ld be easy an d in exp en sive to p u rch ase a

M otherboard Form Factors

n ewer board with a faster p rocessor an d sim p ly swap it in . If th ey p u rch ased a system with a p rop rietary or sem i-p rop rietary board , th ey wou ld be ou t of lu ck wh en it cam e tim e to u p grad e, becau se th ey h ad a d isp osable PC. Disp osable PCs m ay be ch eap er in itially, bu t th ey are u su ally m u ch m ore exp en sive in th e lon g ru n becau se th ey can ’t easily or in exp en sively be u p grad ed or rep aired . 3.75" .40"

.65" 6.50"

6.00"

8.35"

13.04"

.45" .34" 5.55" 8.57"

FIG. 4.1 Baby-AT m oth erboard form factor. Th e easiest way to id en tify a Baby-AT form factor system with ou t op en in g it is to look at th e rear of th e case. In a Baby-AT m oth erboard , th e card s p lu g d irectly in to th e board at a 90-d egree an gle; in oth er word s, th e slots in th e case for th e card s are p erp en d icu lar to th e m oth erboard . Also, th e Baby-AT m oth erboard h as on ly on e visible con n ector d irectly attach ed to th e board , wh ich is th e keyboard con n ector. Norm ally th is con n ector is th e fu ll-sized 5-p in DIN typ e con n ector, alth ou gh som e Baby-AT system s will u se th e sm aller 6-p in m in -DIN con n ector (som etim es called a PS/ 2 typ e con n ector) an d m ay even h ave a m ou se con n ector. All oth er con n ectors will be m ou n ted on th e case or on card ed ge brackets an d attach ed to th e m oth erboard via cables. ◊◊ See “ Keyboard/ M ouse Interface Connectors,” p. 470

Full-Size AT Th e fu ll-size AT m oth erboard m atch es th e origin al IBM AT m oth erboard d esign . Th is allows for a very large board of u p to 12 in ch es wid e by 13.8 in ch es d eep . IBM n eed ed

169

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m ore room for ad d ition al circu its wh en th ey m igrated from th e 8-bit arch itectu re of th e PC/ XT to th e 16-bit arch itectu re of th e AT, so th ey basically took an XT board an d exten d ed it in two d irection s (see Figu res 20.11 an d 20.12). Th e board was red esign ed sligh tly a year after in trod u ction by m akin g it sligh tly sm aller. Th en it was red esign ed again as IBM sh ran k it d own to XT-size in a system th ey called th e XT-286 (see Figu re 20.14). Th e XT-286 board size was ad op ted by m ost PCcom p atible m an u factu rers an d becam e kn own as Baby-AT. ◊◊ See “ An Introduction to the AT,” p. 1129 ◊◊ See “ An Introduction to the XT M odel 286,” p. 1145

Th e keyboard con n ector an d slot con n ectors in th e fu ll-sized AT board s still con form ed to th e sam e sp ecific p lacem en t req u irem en ts to fit th e h oles in th e XT cases alread y in u se, bu t a larger case was still req u ired to fit th e larger board . Du e to th e larger size of th e board , a fu ll-size AT m oth erboard will fit in to fu ll-size AT d esktop or Tower cases on ly. Becau se th ese m oth erboard s will n ot fit in to th e sm aller Baby-AT or Min i-Tower cases, an d becau se of ad van ces in com p on en t m in iatu rization , th ey are n o lon ger bein g p rod u ced by m ost m oth erboard m an u factu rers, excep t in som e cases for d u al p rocessor server ap p lication s. Note th at you can always rep lace a fu ll-size AT m oth erboard with a Baby-AT board , bu t th e op p osite is n ot tru e u n less th e case is large en ou gh to accom m od ate th e fu ll-size AT d esign . LPX Th e LPX an d Min i-LPX form factor board s are a sem i-p rop rietary d esign origin ally d evelop ed by W estern Digital for som e of th eir m oth erboard s back in 1987. Alth ou gh th ey n o lon ger p rod u ce PC m oth erboard s, th e form factor lives on an d h as been d u p licated by m an y oth er m oth erboard m an u factu rers. Un fortu n ately, becau se th e sp ecification s were n ever laid ou t in exact d etail—esp ecially with regard to th e bu s-riser p ortion of th e d esign —th ese board s are term ed sem i-p rop rietary an d are not in terch an geable between m an u factu rers. Th is m ean s th at if you h ave a system with an LPX board , you h ave a system th at you can n ot u p grad e or rep lace th e m oth erboard with som eth in g better. In oth er word s, you h ave a d isp osable PC, som eth in g I wou ld n ever recom m en d an ybod y p u rch ase. Most p eop le are n ot aware of th e sem i-p rop rietary n atu re of th e d esign of th ese board s, an d th ey are extrem ely p op u lar in wh at I call “retail store” PCs. Th is wou ld in clu d e p rim arily th e Com p aq an d Packard Bell system s, an d an y oth ers wh o u se th is form factor. Th ese board s are m ost often u sed in th e Low Profile or Slim lin e case system s, bu t can also be fou n d in tower cases, too. Th ese are often lower-cost system s su ch as th ose sold at retail electron ics su p erstores. Du e to th eir p rop rietary n atu re, I recom m en d stayin g away from an y system th at u ses an LPX m oth erboard .

M otherboard Form Factors

Th e LPX board s are ch aracterized by several d istin ctive featu res. Th e m ost n oticeable is th at th e exp an sion slots are m ou n ted on a bu s riser card th at p lu gs in to th e m oth erboard . Exp an sion card s m u st p lu g sid eways in to th e riser card . Th is sid eways p lacem en t allows for th e low p rofile case d esign . Slots will be located on on e or both sid es of th e riser card d ep en d in g on th e system an d case d esign . An oth er d istin gu ish in g featu re of th e LPX d esign is th e stan d ard p lacem en t of con n ectors on th e back of th e board . An LPX board will h ave a row of con n ectors for vid eo (VGA 15-p in ), p arallel (25-p in ), two serial p orts (9-p in each ), an d m in i-DIN PS/ 2 style m ou se an d keyboard con n ectors. All of th ese con n ectors are m ou n ted across th e rear of th e m oth erboard an d p rotru d e th rou gh a slot in th e case. Som e LPX m oth erboard s m ay h ave ad d ition al con n ectors for oth er in tern al p orts su ch as Network or SCSI ad ap ters. Figu re 4.2 sh ows th e stan d ard form factors for th e LPX an d Min i-LPX m oth erboard s u sed in m an y system s tod ay. 13.0

11.375

5.875

0.375

0.219

0.0 0.0

9.0 0.35

3.906

7.500 8.8125

FIG. 4.2 LPX m oth erboard d im en sion . I am often asked , “How can I tell if a system h as an LPX board before I p u rch ase it?” Fortu n ately, th is is easy an d you d on ’t even h ave to op en th e system u p or rem ove th e cover. LPX m oth erboard s h ave a very d istin ctive d esign with th e bu s slots on a riser card th at p lu gs in to th e m oth erboard . Th is m ean s th at an y card slots will be p arallel to th e m oth erboard , becau se th e card s stick ou t sid eways from th e riser. Lookin g at th e back of a system , you sh ou ld be able to tell wh eth er th e card slots are p arallel to th e m oth erboard . Th is im p lies a bu s riser card is u sed , wh ich also n orm ally im p lies th at th e system

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is an LPX d esign . An oth er riser card d esign is called NLX—th e d ifferen tiatin g factors are th at LPX p u ts th e riser in th e m id d le of th e m oth erboard wh ile NLX h as th e riser to th e sid e (th e m oth erboard actu ally p lu gs in to th e riser in NLX). Also, th e LPX d esign h as on ly a sin gle row of con n ectors alon g th e bottom of th e board , wh ile th e NLX d esign h as h alf sin gle-row an d h alf d ou ble-row con n ectors. See th e section on NLX m oth erboard s later in th is ch ap ter for m ore in form ation on NLX. Th at is n ot th e on ly featu re you sh ou ld look for; th e oth er is th at LPX board s h ave a u n iq u e con n ector arran gem en t. Th ey h ave a row of bu ilt-in con n ectors alon g th e back of th e board , wh ich clearly d istin gu ish es th em from oth er m oth erboard d esign s. See Figu re 4.3 for an exam p le of th e con n ectors on th e back of an LPX board .

Line Out

PS/2 Keyboard

Mic In

Line Out

Serial Port 2

Parallel Port

Video

Serial Port 1

USB 1 USB 2

Parallel Port

Video

PS/2 Mouse

PS/2 Keyboard

Mic In

Serial Port 1

PS/2 Mouse

FIG. 4.3 LPX m oth erboard back p an el con n ectors.

M otherboard Form Factors

Havin g con n ectors alon g th e rear of th e board p reven ts exp an sion card s from bein g p lu gged in to th e m oth erboard ; th at is wh y a riser card d esign was em p loyed for exp an sion . Th e bu ilt-in con n ectors were th e on e good id ea from LPX th at was u sefu l bu t was n ot fou n d in th e Baby-AT d esign . W h at we n eed ed was a stan d ard an d fu lly in terch an geable (n on -p rop rietary) m oth erboard d esign th at fixed th e sh ortcom in gs of th e Baby-AT d esign , su ch as h avin g con n ectors in th e rear for th e bu ilt-in m oth erboard featu res. W e fin ally got wh at we wan ted in 1996 with th e ad ven t of th e ATX m oth erboard form factor. ATX Th e ATX form factor is a recen t evolu tion in m oth erboard form factors. ATX is a com bin ation of th e best featu res of th e Baby-AT an d LPX m oth erboard d esign s, with m an y n ew en h an cem en ts an d featu res th rown in . Th e ATX form factor is essen tially a Baby-AT m oth erboard tu rn ed sid eways in th e ch assis, alon g with a m od ified p ower su p p ly location an d con n ector. Th e m ost im p ortan t th in g to kn ow in itially abou t th e ATX form factor is th at it is p h ysically in com p atible with eith er th e p reviou s Baby-AT or LPX d esign s. In oth er word s, a d ifferen t case an d p ower su p p ly are req u ired to m atch th e ATX m oth erboard . Th ese n ew case an d p ower su p p ly d esign s h ave becom e com m on , an d can be fou n d in m an y n ew system s. Th e official ATX sp ecification was in itially released by In tel in Ju ly 1995, an d h as been written as an op en sp ecification for th e in d u stry. Th ese board s d id n ’t h it th e m arket in force u n til m id -1996 wh en th ey rap id ly began rep lacin g Baby-AT board s in n ew system s. Th e latest revision of th e sp ecification is Version 2.01, p u blish ed in Febru ary 1997. In tel h as p u blish ed d etailed sp ecification s so oth er m an u factu rers can u se th e ATX d esign in th eir system s. Cu rren tly, ATX is by far th e m ost p op u lar m oth erboard form factor, an d it is th e on e I recom m en d m ost p eop le get in th eir system s tod ay. An ATX system will be u p grad able for m an y years to com e, exactly like Baby-AT was in th e p ast. ATX im p roves on th e Baby-AT an d LPX m oth erboard d esign s in several m ajor areas: ■ Built-in double high external I/O connector panel. Th e rear p ortion of th e m oth erboard in clu d es a stacked I/ O con n ector area th at is 6.25 in ch es wid e by 1.75 in ch es tall. Th is allows extern al con n ectors to be located d irectly on th e board an d n egates th e n eed for cables ru n n in g from in tern al con n ectors to th e back of th e case as with Baby-AT d esign s. ■ Single keyed internal power supply connector. Th is is a boon for th e average en d u ser, wh o always h ad to worry abou t in terch an gin g th e Baby-AT p ower su p p ly con n ectors an d su bseq u en tly blowin g th e m oth erboard ! Th e ATX sp ecification in clu d es a sin gle keyed an d sh rou d ed p ower con n ector th at is easy to p lu g in , an d wh ich can n ot be in stalled in correctly. Th is con n ector also featu res p in s for su p p lyin g 3.3v to th e m oth erboard , wh ich m ean s th at ATX m oth erboard s will n ot req u ire bu ilt-in voltage regu lators th at are su scep tible to failu re.

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◊◊ See “ Power Supply Connectors,” p. 403

■ Relocated CPU and m em ory. Th e CPU an d m em ory m od u les are relocated so th ey can n ot in terfere with an y bu s exp an sion card s, an d th ey can easily be accessed for u p grad e with ou t rem ovin g an y of th e in stalled bu s ad ap ters. Th e CPU an d m em ory are relocated n ext to th e p ower su p p ly, wh ich h as a sin gle fan blowin g air across th em , th u s elim in atin g th e n eed for often in efficien t an d failu re-p ron e CPU coolin g fan s. Th ere is room for a large p assive h eat sin k above th e CPU, as well.

Not e Note that systems from smaller vendors may still include CPU fans even in ATX systems, as Intel supplies processors with attached high-quality (ball bearing) fans for CPUs sold to smaller vendors. These are so-called “ boxed” processors as they are sold in single-unit box quantities instead of pallets of 100 or more raw CPUs that are sold to the larger vendors. Intel includes the fan as insurance because smaller vendors and system assemblers lack the engineering knowledge necessary to perform thermal analysis, temperature measurements, and the testing required to select the properly sized passive heat sink. By putting a fan on these “ boxed” processors, Intel is covering their bases as the fan will ensure adequate CPU cooling. Larger vendors have the engineering talent to select the proper passive heat sink, thus reducing the cost of the system as well as increasing reliability.

■ Relocated internal I/O connectors. Th e in tern al I/ O con n ectors for th e flop p y an d h ard d isk d rives are relocated to be n ear th e d rive bays an d ou t from u n d er th e exp an sion board slot an d d rive bay areas. Th is m ean s th at in tern al cables to th e d rives can be m u ch sh orter, an d accessin g th e con n ectors will n ot req u ire card or d rive rem oval. ■ Im proved cooling. Th e CPU an d m ain m em ory are p osition ed so th ey can be cooled d irectly by th e p ower su p p ly fan , elim in atin g th e n eed for sep arate case or CPU coolin g fan s. Also as recom m en d ed (bu t n ot req u ired ) in th e ATX sp ecification , ATX p ower su p p ly fan s blow into th e system ch assis, th u s p ressu rizin g th e system wh ich greatly m in im izes d u st an d d irt in tru sion . If d esired , an air filter can be easily ad d ed to th e air in take ven ts on th e p ower su p p ly, creatin g a system th at is even m ore im m u n e to d irt or d u st in th e en viron m en t. ■ Lower cost to m anufacture. Th e ATX sp ecification s elim in ates th e n eed for th e rat’s n est of cables to extern al p ort con n ectors fou n d on Baby-AT m oth erboard s, ad d ition al CPU or ch assis coolin g fan s, or on board 3.3v voltage regu lators; u ses a sin gle p ower su p p ly con n ector; an d allows for sh orter in tern al d rive cables. Th ese all con sp ire to greatly red u ce n ot on ly th e cost of th e m oth erboard , bu t also sign ifican tly red u ce th e cost of a com p lete system —in clu d in g th e case an d p ower su p p ly. Figu re 4.4 sh ows th e n ew ATX system layou t an d ch assis featu res. Notice h ow virtu ally th e en tire m oth erboard is clear of th e d rive bays, an d h ow th e d evices su ch as CPU, m em ory, an d in tern al d rive con n ectors are easy to access an d d o n ot in terfere with th e

M otherboard Form Factors

bu s slots. Also n otice th e p ower su p p ly orien tation an d th e sin gle p ower su p p ly fan th at blows in to th e case d irectly over th e h igh h eat, coolin g item s su ch as th e CPU an d m em ory. Double high expandable I/O

Single chassis fan

Power Supply Processor

CPU located near PSU

Full length slots

Single power connector

3 1/2" Bay Floppy/IDE connectors close to peripheral bays

5 1/4" Bay Easy to access SIMM memory

FIG. 4.4 ATX system ch assis layou t an d featu res. Th e ATX m oth erboard is basically a Baby-AT d esign rotated sid eways. Th e exp an sion slots are n ow p arallel to th e sh orter sid e d im en sion an d d o n ot in terfere with th e CPU, m em ory, or I/ O con n ector sockets. In ad d ition to a fu ll-sized ATX layou t, In tel also h as sp ecified a m in i-ATX d esign wh ich will fit in to th e sam e case. Alth ou gh th e case h oles are sim ilar to th e Baby-AT case, cases for th e two form ats are gen erally n ot com p atible. Th e p ower su p p lies wou ld req u ire a con n ector ad ap ter to be in terch an geable, bu t th e basic ATX p ower su p p ly d esign is sim ilar to th e stan d ard Slim lin e p ower su p p ly. Th e ATX an d m in i-ATX m oth erboard d im en sion s are sh own in Figu re 4.5. Clearly, th e ad van tages of th e ATX form factor m ake it th e best ch oice for n ew system s. For backward com p atibility, you can still fin d Baby-AT board s for u se in u p grad in g old er system s, bu t th e ch oices are becom in g slim m er every d ay. I wou ld n ever recom m en d bu ild in g or p u rch asin g a n ew system with a Baby-AT m oth erboard , as you will severely lim it you r fu tu re u p grad e p ossibilities. In fact, I h ave been recom m en d in g on ly ATX system s for n ew system p u rch ases sin ce late ’96 an d will p robably con tin u e to d o so for th e n ext several years. Th e best way to tell wh eth er you r system h as an ATX-board d esign with ou t rem ovin g th e lid is to look at th e back of th e system . Th ere are two d istin gu ish in g featu res th at id en tify ATX. On e is th at th e exp an sion board s p lu g d irectly in to th e m oth erboard ; th ere is n o riser card like with LPX or NLX. Th u s, th e slots will be p erp en d icu lar to th e p lan e of th e m oth erboard . Also, ATX board s h ave a u n iq u e d ou ble-h igh con n ector area for all th e bu ilt-in con n ectors on th e m oth erboard (see Figu re 4.6). Th is will be fou n d ju st to th e sid e of th e bu s slot area, an d can be u sed to easily id en tify an ATX board .

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5.196 .812 PIN I ISA TO PIN I PCI SHARED SLOT

.800 TYP. BETWEEN CONNECTORS Datum 0,0

.500

6.250 REAR 1/10 WINDOW IN CHASSIS

.400 .600

.900

1.225

ACCESSIBLE CONNECTOR 1/0 AREA

ISA CONNECTOR (4 PLACES)

6. 00 8.950

PCI CONNECTOR (4 PLACES)

7.550 (MINI ATX)

9.600

M

M

M

5X Ø .156 MINI ATX MOUNTING HOLES MARKED (M)

10X Ø .156 MTG HOLES

M

MINI ATX BOARD 11.2" x 8.2"

3.100 4.900 10.300 (MINI ATX) .650

11.100 12.000

FIG. 4.5 ATX sp ecification version 2.01. NLX NLX is th e latest d evelop m en t in d esktop m oth erboard tech n ology, an d m ay p rove to be th e form factor of ch oice for low-cost, low-en d system s, or even Slim lin e corp orate d esktop system s in th e fu tu re. It is a low-p rofile form factor sim ilar in ap p earan ce to LPX, bu t with a n u m ber of im p rovem en ts d esign ed to allow fu ll in tegration of th e latest tech n ologies. NLX is basically an im p roved version of th e p rop rietary LPX d esign . Besid es d esign im p rovem en ts, it is fu lly stan d ard ized , wh ich m ean s you sh ou ld be able to rep lace on e NLX board with an oth er from a d ifferen t m an u factu rer, som eth in g th at was n ot p ossible with LPX. An oth er lim itation of LPX board s in clu d es d ifficu lties in h an d lin g th e p h ysical size of th e n ewer Pen tiu m II p rocessors an d th eir h igh er ou tp u t th erm al ch aracteristics. Th e NLX form factor h as been d esign ed sp ecifically to ad d ress th ese p roblem s.

M otherboard Form Factors

A

F

H

C

B

D

E

G

I

J

K

A

PS/2 keyboard or mouse

G

Serial Port B

B

PS/2 keyboard or mouse

H

MIDI/game Port (optional)

C

USB Port 1

I

Audio Line Out (optional)

D

USB Port 0

J

Audio Line In (optional)

E

Serial Port A

K

Audio Mic In (optional)

F

Parallel Port

FIG. 4.6 Typ ical ATX m oth erboard rear p an el con n ectors. Sp ecific ad van tages of th e NLX form factor in clu d e: ■ Support for current processor technologies. Th is is esp ecially im p ortan t in Pen tiu m II system s, becau se th e size of th e Sin gle Ed ge Con tact cartrid ge th is p rocessor u ses can lim it its u se on existin g Baby-AT an d LPX m oth erboard s. ■ Flexibility in the face of rapidly changing processor technologies. Backp lan e-like flexibility h as been bu ilt in to th e form by allowin g a n ew m oth erboard to be easily an d q u ickly in stalled with ou t tearin g you r en tire system to p ieces. Bu t u n like trad ition al backp lan e system s, m an y in d u stry lead ers are p u ttin g th eir su p p ort beh in d NLX, in clu d in g AST, Digital, Gateway, Hewlett-Packard , IBM, Micron , NEC, an d oth ers. ■ Support for other em erging technologies. Th is in clu d es Accelerated Grap h ics Port (AGP) h igh -p erform an ce grap h ic solu tion s, Un iversal Serial Bu s (USB), an d tall m em ory m od u les an d DIMM tech n ology. Fu rth erm ore, with th e em ergin g im p ortan ce of

177

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Chapter 4—M otherboards and Buses

m u ltim ed ia ap p lication s, con n ectivity su p p ort for su ch th in gs as vid eo p layback, en h an ced grap h ics, an d exten d ed au d io h ave been bu ilt in to th e m oth erboard . Th is sh ou ld rep resen t a good cost savin gs over exp en sive d au gh terboard arran gem en ts th at h ave been n ecessary for m an y ad van ced m u ltim ed ia u ses in th e p ast. Alth ou gh ATX also h as th is su p p ort, LPX an d Baby-AT d on ’t h ave th e room for th ese ad d ition al con n ectors. Figu re 4.7 sh ows th e basic NLX system layou t, wh ile th e NLX m oth erboard d im en sion s are sh own in Figu re 4.8. Notice th at, like ATX, th e system is clear of th e d rive bays an d oth er ch assis-m ou n ted com p on en ts. Also, th e m oth erboard an d I/ O card s (wh ich , like th e LPX form factor, are m ou n ted p arallel to th e m oth erboard ) can easily be slid in an d ou t of th e sid e of th e ch assis, leavin g th e riser card an d oth er card s in p lace. Th e p rocessor can be easily accessed an d en joys greater coolin g th an in a m ore closed -in layou t. Double height I/O connectors

Support for multiple board sizes provides product line differentiation

Single height I/O connectors

Power Supply Fan

Back Panel Connectors

Full length I/O slots.

Power connector R i s e ?r

PS/2 Form Factor Power Supply

C o n n Processor

Cables connect riser card to peripherals

Improved processor access, cooling, and clearance

Fan

5.25 drive bay

FIG. 4.7 NLX system ch assis layou t an d featu res.

3.5 drive bay

M otherboard Form Factors

10.000 9.800 .200

6.225

3.575

Mounting Holes

1.200

DIMM Slots 3.400 Slot 1 connector

9.000 MAXIMUM BOARD WIDTH 8.000 MINIMUM BOARD WIDTH

7.800

4.400 Mounting Holes

Edge connector connects to riser card with adapter slots

FIG. 4.8 NLX form factor. Th is sh ows a 10-in ch lon g NLX board . Th e NLX sp ecification also allows 11.2-in ch an d 13.6-in ch lon g version s. As you can see, th e NLX form factor h as been d esign ed for m axim u m flexibility an d sp ace efficien cy. Even extrem ely lon g I/ O card s will fit easily, with ou t gettin g in th e way of oth er system com p on en ts—a p roblem with Baby-AT form factor system s. ATX an d NLX form factors will p robably be u sed in m ost fu tu re system s. I u su ally d o n ot recom m en d LPX style system s if u p grad ability is a factor becau se it is n ot on ly d ifficu lt to locate a n ew m oth erboard th at will fit, bu t LPX system s are also lim ited in exp an sion slots an d d rive bays. ATX is still th e absolu te best ch oice for n ew system s wh ere exp an d ability, u p grad ability, low cost, an d ease of service are of p rim e im p ortan ce. Propriet ary Designs Moth erboard s th at are n ot on e of th e stan d ard form factors su ch as Fu ll-sized AT, BabyAT, ATX, or NLX are d eem ed p rop rietary. Most p eop le p u rch asin g PCs sh ou ld avoid p rop rietary d esign s becau se th ey d o n ot allow for a fu tu re m oth erboard , p ower su p p ly, or case u p grad e, wh ich greatly lim its fu tu re u se of th e system . To m e, p rop rietary system s are d isp osable PCs, becau se you can n eith er u p grad e th em , n or can you easily rep air th em . Th e p roblem is th at th e p rop rietary p arts can on ly com e from th e origin al system m an u factu rer, an d th ey u su ally cost m an y tim es m ore th an n on -p rop rietary p arts. Th is m ean s th at after you r p rop rietary system goes ou t of warran ty, it is essen tially n o lon ger worth rep airin g. If th e m oth erboard goes bad , you will be better off p u rch asin g a wh ole n ew stan d ard system th an p ayin g five tim es th e n orm al p rice for a n ew m oth erboard . In ad d ition , a n ew m oth erboard in a stan d ard form -factor system wou ld be a gen eration n ewer an d faster th an th e on e you are rep lacin g. In a p rop rietary system , th e rep lacem en t board wou ld be th e sam e as th e on e th at failed .

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Th e p op u lar LPX m oth erboard d esign is at th e h eart of m ost p rop rietary system s. Th ese system s are sold p rim arily in th e retail store ch an n el. Th is class of system is d om in ated by Com p aq an d Packard Bell, an d , as su ch , virtu ally all th eir system s h ave th e p roblem s in h eren t with th eir p rop rietary d esign s. Som e of th ese m an u factu rers seem to go ou t of th eir way to m ake th eir system s as p h ysically in com p atible as p ossible with an y oth er system . Th en , rep lacem en t p arts, rep airs, an d u p grad es are virtu ally im p ossible to fin d —excep t, of cou rse, from th e origin al system m an u factu rer an d at a sign ifican tly h igh er p rice th an th e eq u ivalen t p art wou ld cost to fit a stan d ard PC-com p atible system . For exam p le, if th e m oth erboard in m y cu rren t ATX form factor system (an d an y system u sin g a Baby-AT m oth erboard an d case) d ies, I can fin d an y n u m ber of rep lacem en t board s th at will bolt d irectly in —with m y ch oice of p rocessors an d clock sp eed s—at very good (n o, m ake th at great) p rices. If th e m oth erboard d ies in a n ewer Com p aq , Packard Bell, Hewlett-Packard , or oth er p rop rietary-sh ap ed system , you ’ll p ay for a rep lacem en t available on ly from th e origin al m an u factu rer, an d you h ave little or n o op p ortu n ity to select a board with a faster or better p rocessor th an th e on e th at failed . In oth er word s, u p grad in g or rep airin g on e of th ese system s via a m oth erboard rep lacem en t is d ifficu lt an d u su ally n ot cost effective. System s sold by th e lead in g m ail ord er su p p liers su ch as Dell, Gateway, Micron , an d oth ers are available in stan d ard ATX form factors, wh ich allow for easy u p grad in g an d system exp an sion in th e fu tu re. Th e ATX form factor also m ean s th at you can rep lace you r own m oth erboard s, p ower su p p lies, an d oth er com p on en ts easily an d select com p on en ts from an y n u m ber of su p p liers oth er th an wh ere you origin ally bou gh t th e system . Backplane Syst em s On e typ e of p rop rietary d esign is th e backp lan e system . Th ese system s d o n ot h ave a m oth erboard in th e tru e sen se of th e word . In a backp lan e system , th e com p on en ts n orm ally fou n d on a m oth erboard are located in stead on an exp an sion ad ap ter card p lu gged in to a slot. In th ese system s, th e board with th e slots is called a backplane, rath er th an a m oth erboard . System s u sin g th is typ e of con stru ction are called backplane system s. Backp lan e system s com e in two m ain typ es—passive an d active. A p assive backp lan e m ean s th e m ain backp lan e board d oes n ot con tain an y circu itry at all excep t for th e bu s con n ectors an d m aybe som e bu ffer an d d river circu its. All th e circu itry fou n d on a con ven tion al m oth erboard is con tain ed on on e or m ore exp an sion card s in stalled in slots on th e backp lan e. Som e backp lan e system s u se a p assive d esign th at in corp orates th e en tire system circu itry in to a sin gle m oth ercard . Th e m oth ercard is essen tially a com p lete m oth erboard th at is d esign ed to p lu g in to a slot in th e p assive backp lan e. Th e p assive backp lan e/ m oth ercard con cep t allows th e en tire system to be easily u p grad ed by ch an gin g on e or m ore card s. Becau se of th e exp en se of th e h igh -fu n ction m oth ercard , th is typ e of system d esign is rarely fou n d in PC system s. Th e p assive backp lan e d esign d oes en joy p op u larity in in d u strial system s, wh ich are often rack-m ou n ted . Som e h igh -en d file servers also featu re th is d esign .

M otherboard Form Factors

An active backp lan e m ean s th e m ain backp lan e board con tain s bu s con trol an d u su ally oth er circu itry as well. Most active backp lan e system s con tain all th e circu itry fou n d on a typ ical m oth erboard excep t for th e p rocessor com p lex. Th e processor com plex is th e n am e of th e circu it board th at con tain s th e m ain system p rocessor an d an y oth er circu itry d irectly related to it, su ch as clock con trol, cach e, an d so forth . Th e p rocessor com p lex d esign allows th e u ser to easily u p grad e th e system later to a n ew p rocessor typ e by ch an gin g on e card . In effect, it am ou n ts to a m od u lar m oth erboard with a rep laceable p rocessor section . Most m od ern PC system s th at u se a backp lan e d esign u se an active backp lan e/ p rocessor com p lex. Both IBM an d Com p aq , for exam p le, h ave u sed th is typ e of d esign in som e of th eir h igh -en d (server class) system s. Th is allows an easier an d gen erally m ore afford able u p grad e th an th e p assive backp lan e/ m oth ercard d esign becau se th e p rocessor com p lex board is u su ally m u ch ch eap er th an a m oth ercard . Un fortu n ately, becau se th ere are n o stan d ard s for th e p rocessor com p lex in terface to th e system , th ese board s are p rop rietary an d can on ly be p u rch ased from th e system m an u factu rer. Th is lim ited m arket an d availability cau ses th e p rices of th ese board s to be h igh er th an m ost com p lete m oth erboard s from oth er m an u factu rers. Th e m oth erboard system d esign an d th e backp lan e system d esign h ave both ad van tages an d d isad van tages. Most origin al p erson al com p u ters were d esign ed as backp lan es in th e late 1970s. Ap p le an d IBM sh ifted th e m arket to th e n ow trad ition al m oth erboard with a slot-typ e d esign becau se th is typ e of system gen erally is ch eap er to m ass-p rod u ce th an on e with th e backp lan e d esign . Th e th eoretical ad van tage of a backp lan e system , h owever, is th at you can u p grad e it easily to a n ew p rocessor an d n ew level of p erform an ce by ch an gin g a sin gle card . For exam p le, you can u p grad e a system ’s p rocessor ju st by ch an gin g th e card . In a m oth erboard -d esign system , you often m u st ch an ge th e m oth erboard , a seem in gly m ore form id able task. Un fortu n ately, th e reality of th e situ ation is th at a backp lan e d esign is often m u ch m ore exp en sive to u p grad e. For exam p le, becau se th e bu s rem ain s fixed on th e backp lan e, th e backp lan e d esign p reclu d es m ore com p reh en sive u p grad es th at in volve ad d in g local bu s slots. An oth er n ail in th e coffin of backp lan e d esign s is th e u p grad able p rocessor. In tel h as d esign ed all 486, Pen tiu m , Pen tiu m Pro, an d Pen tiu m II p rocessors to be u p grad able to faster (som etim es called OverDrive) p rocessors in th e fu tu re by sim p ly swap p in g (or ad d in g) th e n ew p rocessor ch ip . Ch an gin g on ly th e p rocessor ch ip for a faster on e is th e easiest an d gen erally m ost cost-effective way to u p grad e with ou t ch an gin g th e en tire m oth erboard . To allow p rocessor u p grad es, In tel h as stan d ard ized on a n u m ber of d ifferen t typ es of CPU sockets an d slots th at allow for u p grad in g to an y faster p rocessors d esign ed to fit th e sam e com m on socket or slot. Becau se of th e lim ited availability of th e p rocessor com p lex board s or m oth ercard s, th ey u su ally en d u p bein g m ore exp en sive th an a com p lete n ew m oth erboard th at u ses an in d u stry-stan d ard form factor.

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M ot herboard Com ponent s A m od ern m oth erboard h as several com p on en ts bu ilt in , in clu d in g variou s sockets, slots, con n ectors, ch ip s, an d oth er com p on en ts. Th is section exam in es th e com p on en ts fou n d on a typ ical m oth erboard . Most m od ern m oth erboard s h ave th e followin g com p on en ts on th em : ■ Processor Socket/ Slot ■ Ch ip set ■ Su p er I/ O ch ip ■ BIOS ■ SIMM/ DIMM sockets ■ Bu s Slots ■ CPU Voltage Regu lator ■ Battery Th ese com p on en ts are d iscu ssed in th e followin g section s. Processor Socket s/ Slot s Th e CPU is in stalled in a socket for all system s u p to an d in clu d in g th e Pen tiu m Pro p rocessor. Th e Pen tiu m II p rocessors an d beyon d u se a slot wh ere th e p rocessor card or cartrid ge p lu gs in . Startin g with th e 486 p rocessors, In tel d esign ed th e p rocessor to be a u ser in stallable an d rep laceable p art, an d d evelop ed stan d ard s for CPU sockets th at wou ld allow d ifferen t m od els of th e sam e basic p rocessor to p lu g in . Th ese socket sp ecification s were n u m bered an d based on th e socket or slot n u m ber you h ave on you r m oth erboard . Th is m ean s th at you will kn ow exactly wh at typ es of p rocessors can be in stalled . √√ See “ Processor Sockets,” p. 54

Sockets for p rocessors p rior to th e 486 were n ot n u m bered , an d in terch an geability was lim ited . Table 4.1 sh ows th e relation sh ip between th e variou s p rocessor sockets/ slots an d th e ch ip s d esign ed to go in to th em . Table 4.1

CPU Socket Specificat ions

Socket Num ber

Pins

Pin Layout

Volt age

Support ed Processors

Socket 1

169

17×17 PGA

5v

486 SX/ SX2, DX/ DX2*, DX4 OverDrive

Socket 2

238

19×19 PGA

5v

486 SX/ SX2, DX/ DX2*, DX4 OverDrive, 486 Pentium OverDrive

M otherboard Components

Socket Num ber

Pins

Pin Layout

Volt age

Support ed Processors

Socket 3

237

19×19 PGA

5v/ 3.3v

486 SX/ SX2, DX/ DX2, DX4, 486 Pentium OverDrive, 5x86

Socket 4

273

21×21 PGA

5v

Pentium 60/ 66, OverDrive

Socket 5

320

37×37 SPGA

3.3v/ 3.5v

Pentium 75-133, OverDrive

Socket 6**

235

19 ×19 PGA

3.3v

486 DX4, 486 Pentium OverDrive

Socket 7

321

37×37 SPGA

VRM

Pentium 75-266+, M M X, OverDrive, 6x86, K6

Socket 8

387

dual pattern SPGA

Auto VRM

Pentium Pro

Slot 1

242

SEC/ SEPP Slot

Auto VRM

Pentium II M M X, Pentium II Celeron

Slot 2

n/ a

SEC Slot

Auto VRM

Pentium II Xeon

*Non-OverDrive DX 4 also can be supported with the addition of an afterm arket 3.3v voltage-regulator adapter. **Socket 6 was a proposed standard only and was never actually im plem ented in any system s. PGA = Pin Grid Array SPGA = Staggered Pin Grid Array V RM = V oltage Regulator Module SEC = Single Edge Contact cartridge SEPP = Single Edge Processor Package (Pentium II without the plastic cartridge)

Chipset s W h en th e first PC m oth erboard s were created by IBM, th ey u sed m an y d iscrete ch ip s to com p lete th e d esign . Besid es th e p rocessor, th ere were m an y oth er com p on en ts req u ired to com p lete th e system . Th ese oth er com p on en ts in clu d ed th in gs su ch as th e clock gen erator, bu s con troller, system tim er, in terru p t an d DMA con trollers, CMOS RAM an d clock, an d th e keyboard con troller. Th ere were also a n u m ber of oth er sim p le logic ch ip s u sed to com p lete th e en tire m oth erboard circu it, p lu s, of cou rse, th in gs su ch as th e actu al p rocessor, m ath cop rocessor (floatin g-p oin t u n it), m em ory, an d oth er p arts. Table 4.2 lists all th e p rim ary ch ip com p on en ts u sed on th e origin al PC/ XT an d AT m oth erboard s. Table 4.2

Prim ary Chip Com ponent s on M ot herboards

Chip Funct ion

PC/ XT Version

AT Version

Processor

8088

80286

M ath Coprocessor (Floating-Point Unit

8087

80287

Clock Generator

8284

82284

Bus Controller

8288

82288

System Timer

8253

8254

Low-order Interrupt Controller

8259

8259

High-order Interrupt Controller

-

8259

Low-order DM A Controller

8237

8237 (continues)

183

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Chapter 4—M otherboards and Buses

Table 4.2

Prim ary Chip Com ponent s on M ot herboards Cont inued

Chip Funct ion

PC/ XT Version

AT Version

High-order DM A Controller

-

8237

CM OS RAM / Clock

-

M C146818

Keyboard Controller

8255

8042

All th ese com p on en ts cam e from In tel or an In tel-licen sed m an u factu rer excep t th e CMOS/ Clock ch ip , wh ich cam e from Motorola. To bu ild a clon e or cop y of on e of th ese IBM system s back th en wou ld req u ire all th ese ch ip s p lu s m an y sm aller d iscrete logic ch ip s, totalin g u p to 100 or m ore in d ivid u al ch ip s. Th is kep t th e p rice of a m oth erboard h igh , an d left little room on th e board to in tegrate oth er fu n ction s. In 1986, a com p an y called Ch ip s an d Tech n ologies in trod u ced a revolu tion ary com p on en t called th e 82C206, th e m ain p art of th e first PC m oth erboard ch ip set. Th is was a sin gle ch ip th at in tegrated in to it all th e fu n ction s of th e m ain m oth erboard ch ip s in an AT-com p atible system . Th is ch ip in clu d ed th e fu n ction s of th e 82284 Clock Gen erator, 82288 Bu s Con troller, 8254 System Tim er, d u al 8259 In terru p t Con trollers, d u al 8237 DMA Con trollers, an d even th e MC146818 CMOS/ Clock ch ip . Besid es th e p rocessor, virtu ally all th e m ajor ch ip com p on en ts on a PC m oth erboard cou ld n ow be rep laced by a sin gle ch ip . Fou r oth er ch ip s au gm en ted th e 82C206 actin g as bu ffers an d m em ory con trollers, th u s com p letin g virtu ally th e en tire m oth erboard circu it with five total ch ip s. Th is first ch ip set was called th e CS8220 ch ip set by Ch ip s an d Tech n ologies. Need less to say, th is was a revolu tion ary con cep t in PC m oth erboard m an u factu rin g. Not on ly d id it greatly red u ce th e cost to bu ild a PC m oth erboard , bu t it also m ad e it m u ch easier to d esign a m oth erboard an d th e red u ced com p on en t cou n t m ean t th e board s h ad m ore room for in tegratin g oth er item s form erly fou n d on exp an sion card s. Later th e fou r ch ip s au gm en tin g th e 82C206 were rep laced by a n ew set of on ly th ree ch ip s, an d th e en tire set was called th e New En h an ced AT (NEAT) CS8221 ch ip set. Th is was later followed by th e 82C836 Sin gle Ch ip AT (SCAT) ch ip set, wh ich fin ally con d en sed all th e ch ip s in th e set d own to a sin gle ch ip . Th e ch ip set id ea was rap id ly cop ied by oth er ch ip m an u factu rers. Com p an ies su ch as Acer, Erso, Op ti, Su n tac, Sym p h on y, UMC, an d VLSI each gain ed an im p ortan t sh are of th is m arket. Un fortu n ately for m an y of th em , th e ch ip set m arket h as been a volatile on e, an d m an y of th em h ave lon g sin ce gon e ou t of bu sin ess. In 1993 VLSI h ad becom e th e d om in an t force in th e ch ip set m arket an d h ad th e vast m ajority of th e m arket sh are; by th e n ext year, th ey, alon g with virtu ally everybod y else in th e ch ip set m arket, wou ld be figh tin g to stay alive. Th is is becau se a n ew ch ip set m an u factu rer h ad com e on th e scen e, an d with in a year or so of gettin g seriou s th ey were totally d om in atin g th e ch ip set m arket. Th at com p an y is In tel, an d sin ce 1994 th ey h ave h ad a virtu al lock on th e ch ip set m arket. If you h ave a m oth erboard bu ilt sin ce 1994, ch an ces are far better th an n ot th at it h as an In tel ch ip set on it alon g with an In tel p rocessor. Th ere are very few ch ip set com p etitors left, an d th e on es th at are left are scratch in g for th e lower en d of th e m arket. Tod ay, th at wou ld in clu d e p rim arily ALi (Acer Laboratories, In c.), VIA Tech n ologies, an d SiS (Silicon in tegrated System s). It is in terestin g to n ote th at Ch ip s an d Tech n ologies su rvived by ch an gin g cou rse to d esign an d m an u factu re vid eo ch ip s, an d fou n d a n ich e

M otherboard Components

in th at m arket sp ecifically for lap top an d n otebook vid eo ch ip sets. Th ey were bou gh t ou t by In tel in 1998 as a way for In tel to get in to th e vid eo ch ip set bu sin ess. Int el Chipset s You can n ot talk abou t ch ip sets tod ay with ou t p rim arily d iscu ssin g In tel. Th ey cu rren tly own well over 90% of th e ch ip set m arket, an d virtu ally 100% of th e h igh er-en d Pen tiu m II ch ip set m arket. It is in terestin g to n ote th at we p robably h ave Com p aq to th an k for forcin g In tel in to th e ch ip set bu sin ess in th e first p lace. Th e th in g th at really started it all was th e in trod u ction of th e EISA bu s d esign ed by Com p aq in 1989. At th at tim e, th ey h ad sh ared th e bu s with oth er m an u factu rers in an attem p t to m ake it a m arket stan d ard . However, th ey refu sed to sh are th eir EISA bu s ch ip set, a set of cu stom ch ip s n eed ed to im p lem en t th is bu s on a m oth erboard . En ter In tel, wh o d ecid ed to su p p ly th e ch ip set void for th e rest of th e PC m an u factu rers wan tin g to bu ild EISA bu s m oth erboard s. Th e EISA bu s failed to becom e a m arket su ccess excep t for th e n ich e server bu sin ess, bu t In tel n ow h ad a taste of th e ch ip set bu sin ess an d th is th ey ap p aren tly wou ld n ’t forget. W ith th e in trod u ction of th e 486 p rocessor, In tel becam e im p atien t with h ow lon g it was takin g th e oth er ch ip set com p an ies to create ch ip sets arou n d th eir n ew p rocessor d esign s, wh ich th en d elayed th e in trod u ction of m oth erboard s th at su p p orted th e n ew p rocessors. In tel cou ld n ’t sell th eir p rocessors in volu m e u n til th ere were read y-m ad e m oth erboard s th at wou ld su p p ort th em , so th ey th ou gh t th at by d evelop in g m oth erboard ch ip sets for a n ew p rocessor in p arallel with th e n ew p rocessor, th ey cou ld ju m p start th e m oth erboard bu sin ess by p rovid in g read y-m ad e ch ip sets. By th e tim e th e first Pen tiu m p rocessor d ebu ted in 1993, In tel h ad th eir first Pen tiu m m oth erboard ch ip set read y to go at th e sam e tim e. Now it took on ly scan t m on th s before th e first Pen tiu m m oth erboard s were available, rath er th an th e year or m ore it h ad h istorically taken . Sin ce th en , In tel h as th rived in th e ch ip set m arket, always in trod u cin g n ew ch ip sets to go with th eir n ew p rocessors. Th eir su ccess in ch ip sets p rom p ted th em to take th e fin al step —m akin g com p lete PC m oth erboard s u sin g th eir own p rocessors an d ch ip sets. Now as th ey d evelop n ew p rocessors, th ey d evelop ch ip sets an d even com p lete m oth erboard s sim u ltan eou sly, wh ich m ean s th ey can be an n ou n ced an d sh ip p ed in u n ison . Th is elim in ates th e d elay between in trod u cin g n ew p rocessors an d h avin g m oth erboard s an d system s be able to u se th em , wh ich was com m on in th e in d u stry’s early d ays. Th is d elay is virtu ally elim in ated tod ay. It was am azin g to m e th at on th e d ay th ey in trod u ced th e first Pen tiu m II p rocessor, n ot on ly was th ere a n ew ch ip set available to su p p ort it, bu t com p lete m oth erboard s, as well. Th at very d ay, you cou ld call Gateway or Dell an d ord er a com p lete In tel system u sin g th e n ew In tel PII p rocessor, ch ip set, an d m oth erboard . Th is h as n ot m ad e com p an ies su ch as Com p aq (wh o still like to m ake th eir own m oth erboard s rath er th an p u rch ase som ebod y else’s off-th e-sh elf p rod u ct) h ap p y, to say th e least. First with th e ad ven t of th e Pen tiu m , th en th e Pen tiu m Pro, an d n ow th e Pen tiu m II p rocessor, n ot on ly d o m ore th an 90% of th e system s sold u se In tel p rocessors, bu t th eir m oth erboard s also m ost likely h ave an In tel ch ip set on th em an d , in fact, th eir en tire m oth erboard was m ost likely m ad e by In tel. In m y sem in ars, I ask h ow m an y p eop le in th e class h ave In tel bran d PCs. Of cou rse, In tel d oes n ot sell or m arket a PC u n d er th eir

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own n am e, so n obod y th in ks th ey h ave an In tel bran d PC. Bu t I say if you r m oth erboard was m ad e by In tel, th en you h ave an In tel bran d PC, as far as I am con cern ed . Does it really m atter wh eth er Dell, Gateway, or Micron p u t th at sam e In tel m oth erboard in to a sligh tly d ifferen t lookin g case with th eir n am e on it? Int el Chipset M odel Num bers. In tel started a p attern of n u m berin g th eir ch ip sets as follows: Chipset Num ber

Processor Fam ily

420xx

P4 (486)

430xx

P5 (Pentium)

440xx

P6 (Pentium Pro/ Pentium II)

450xx

P6 Server (Pentium Pro/ Pentium II Xeon)

Th e ch ip set n u m bers listed h ere are an abbreviation of th e actu al ch ip set n u m bers stam p ed on th e in d ivid u al ch ip s. For exam p le, on e of th e cu rren t p op u lar Pen tiu m II ch ip sets is th e 440BX ch ip set, wh ich really con sists of two com p on en ts, th e 82443BX North Brid ge an d th e 82371EX Sou th Brid ge. By read in g th e n u m ber an d letter com bin ation s on th e larger ch ip s on you r m oth erboard , you can u su ally q u ickly id en tify th e ch ip set you r m oth erboard u ses. Most all of In tel’s ch ip sets (an d th ose of In tel’s com p etitors) are broken in to a two-tiered arch itectu re in corp oratin g a North Brid ge an d Sou th Brid ge section . Th e North Brid ge is th e m ain p ortion of th e ch ip set an d in corp orates th e in terface between th e p rocessor an d th e rest of th e m oth erboard . Th e North Brid ge com p on en ts are wh at th e ch ip set is n am ed after, m ean in g th at, for exam p le, wh at we call th e 440BX ch ip set is actu ally d erived from th e fact th at th e actu al North Brid ge ch ip p art n u m ber for th at set is 82443BX. Th e North Brid ge con tain s th e cach e an d m ain m em ory con trollers an d th e in terface between th e h igh -sp eed (33MHz, 50MHz, 66MHz or 100MHz) p rocessor bu s an d th e 33MHz PCI (Perip h eral Com p on en t In tercon n ect) an d or 66MHz AGP (Accelerated Grap h ics Port) bu ses. In tel often refers to th e North Brid ge of th eir m ore recen t ch ip sets as th e PAC (PCI/ AGP Con troller). Th e North Brid ge is essen tially th e m ain com p on en t of th e m oth erboard an d is th e on ly m oth erboard circu it besid es th e p rocessor th at n orm ally ru n s at fu ll m oth erboard (p rocessor bu s) sp eed . Most m od ern ch ip sets u se a sin gle-ch ip North Brid ge; h owever, som e of th e old er on es actu ally con sisted of u p to th ree in d ivid u al ch ip s to m ake u p th e com p lete North Brid ge circu it. Th e Sou th Brid ge is th e lower sp eed com p on en t in th e ch ip set an d h as always been a sin gle in d ivid u al ch ip . Th e Sou th Brid ge is a som ewh at in terch an geable com p on en t in th at d ifferen t North Brid ge ch ip sets often are d esign ed to u se th e sam e Sou th Brid ge com p on en t. Th is m od u lar d esign of th e ch ip set allows for lower cost an d greater flexibility for m oth erboard m an u factu rers. Th e Sou th Brid ge con n ects to th e 33MHz PCI bu s an d con tain s th e in terface to th e 8MHz ISA bu s. It also n orm ally con tain s th e d u al IDE h ard d isk con troller in terfaces, an d th e USB (Un iversal Serial Bu s) in terface—an d even th e CMOS RAM an d clock fu n ction s. Th e Sou th Brid ge con tain s all th e com p on en ts th at m ake u p th e ISA bu s, in clu d in g th e in terru p t an d DMA con trollers.

M otherboard Components

Let’s start by exam in in g th e In tel 486 m oth erboard ch ip sets an d th en work ou r way th rou gh th e latest Pen tiu m II sets. Int el’s Early 386/ 486 Chipset s In tel’s first real PC m oth erboard ch ip set was th e 82350 ch ip set for th e 386DX an d 486 p rocessors. Th is ch ip set was n ot very su ccessfu l, m ain ly becau se th e EISA bu s was n ot very p op u lar, an d becau se th ere were m an y oth er m an u factu rers m akin g stan d ard 386 an d 486 m oth erboard ch ip sets at th e tim e. Th e m arket ch an ged very q u ickly, an d In tel d rop p ed th e EISA bu s su p p ort an d in trod u ced follow-u p 486 ch ip sets th at were m u ch m ore su ccessfu l. Table 4.3 sh ows th e In tel 486 ch ip sets. Table 4.3

Int el 486 M ot herboard Chipset s

Chipset

420TX

420EX

420ZX

Codename

Saturn

Aries

Saturn II

Date Introduced

Nov. ’92

M arch ’94

M arch ’94

Processor

5v 486

5v/ 3.3v 486

5v/ 3.3v 486

Bus Speed

up to 33 M Hz

up to 50 M Hz

up to 333 M Hz

SM P (dual CPUs)

No

No

No

M emory Types

FPM

FPM

FPM

Parity/ ECC

Parity

Parity

Parity

M ax. M emory

128M M B

128M M B

160M M B

L2 Cache Type

Async

Async

Async

PCI Support

2.0

2.0

2.1

AGP Support

No

No

No

SMP = Sym m etric Multi-processing (Dual Processors) FPM = Fast Page Mode PCI = Peripheral Com ponent Interconnect AGP = Accelerated Graphics Port Note: PCI 2.1 supports concurrent PCI operations.

In tel h ad p retty good su ccess with th eir 486 ch ip sets. Th ey h ad d evelop ed th eir cu rren t two-tiered ap p roach to system d esign even back th en . Th is d esign is su ch th at all In tel 486, Pen tiu m , Pen tiu m Pro, an d Pen tiu m II h ave been d esign ed u sin g two m ain com p on en ts, wh ich are com m on ly called th e North Bridge an d th e South Bridge. Fift h-Generat ion ( P5 Pent ium Class) Chipset s W ith th e ad ven t of th e Pen tiu m p rocessor in March of ’93, In tel also in trod u ced th eir first Pen tiu m ch ip set, th e 430LX (cod e-n am ed Mercu ry) ch ip set. Th is was th e first Pen tiu m ch ip set on th e m arket an d set th e stage as In tel took th is lead an d ran with it. Oth er m an u factu rers took m on th s to a year or m ore to get th eir Pen tiu m ch ip sets ou t th e d oor. Sin ce th e d ebu t of th eir Pen tiu m ch ip sets, In tel h as d om in ated th e ch ip set m arket with n obod y even com in g close. Table 4.4 sh ows th e In tel Pen tiu m m oth erboard ch ip sets.

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Table 4.4

Int el Pent ium M ot herboard Chipset s

Chipset

430LX

430NX

430FX

Codename Date Introduced

M ercury

Neptune

Triton

M ar. ’93

M ar. ’94

Jan. ’95

Bus Speed

66 M Hz

66 M Hz

66 M Hz

CPUs Supported

P60/ 66

P75+

P75+

SM P (dual CPUs)

No

Yes

No

M emory Types

FPM

FPM

FPM / EDO

Parity/ ECC

Parity

Parity

Neither

M ax. M emory

192M

512M

128M

M ax. Cacheable

192M

512M

64M

L2 Cache Type

Async

Async

Async/ Pburst

PCI Support

2.0

2.0

2.0

AGP Support

No

No

No

South Bridge

SIO

SIO

PIIX

SMP = Sym m etric Multi-processing (Dual Processors) FPM = Fast Page Mode EDO = Extended Data Out BEDO = Burst EDO SDRAM = Synchronous Dynam ic RAM

Pburst = Pipeline Burst (Synchronous) PCI = Peripheral Com ponent Interconnect AGP = Accelerated Graphics Port SIO = System I/O PIIX = PCI ISA IDE X celerator

Not e PCI 2.1 supports concurrent PCI operations.

Table 4.5 sh ows all th e ap p licable In tel Sou th Brid ge ch ip s, wh ich are th e secon d p art of th e m od ern In tel m oth erboard ch ip sets. Table 4.5

Int el Sout h Bridge Chips

Chip Nam e

SIO

PIIX

PIIX3

PIIX4

PIIX4E

Part Number

82378IB/ ZB

82371FB

82371SB

82371AB

82371EB

IDE Support

None

BM IDE

BM IDE

UDM A

UDM A

USB Support

None

None

Yes

Yes

Yes

CM OS/ Clock

No

No

No

Yes

Yes

Power M anagement

SM M

SM M

SM M

SM M

ACPI 1.0

SIO = System I/O PIIX = PCI ISA IDE X celerator USB = Universal Serial Bus IDE = Integrated Drive Electronics (AT Attachm ent) BMIDE = Bus Master IDE UDMA = Ultra-DMA IDE SMM = System Managem ent Mode ACPI = Advanced Configuration and Power Interface specification

M otherboard Components

430M X

430HX

430VX

430TX

M obile Triton

Triton II

Triton III

n/ a

Oct. ’95

Feb. ’96

Feb. ’96

Feb. ’97

66 M Hz

66 M Hz

66 M Hz

66 M Hz

P75+

P75+

P75+

P75+

No

Yes

No

No

FPM / EDO

FPM / EDO

FPM / EDO/ SDRAM

FPM / EDO/ SDRAM

Neither

Both

Neither

Neither

128M

512M

128M

256M

64M

512M

64M

64M

Async/ Pburst

Async/ Pburst

Async/ Pburst

Async/ Pburst

2.0

2.1

2.1

2.1

No

No

No

No

M PIIX

PIIX3

PIIX3

PIIX4

Th e followin g section s d etail all th e Pen tiu m m oth erboard ch ip sets an d th eir sp ecification s. Int el 430LX ( M ercury) . Th e 430LX was in trod u ced in March of 1993 con cu rren t with th e in trod u ction of th e first Pen tiu m p rocessors. Th is ch ip set was on ly u sed with th e origin al Pen tiu m s, wh ich cam e in 60MHz an d 66MHz version s. Th ese were 5v ch ip s an d were u sed on m oth erboard s with Socket 4 p rocessor sockets. √√ See “ Processor Sockets,” p. 54 √√ See “ First-Generation Pentium Processor,” p. 109

Th e 430LX ch ip set con sisted of th ree total ch ip s for th e North Brid ge p ortion . Th e m ain ch ip was th e 82434LX system con troller. Th is m ain ch ip con tain ed th e p rocessor-tom em ory in terface, cach e con troller, an d PCI bu s con troller. Th ere was also a p air of PCI bu s in terface accelerator ch ip s, wh ich were id en tical 82433LX ch ip s. Th e 430LX ch ip set was n oted for th e followin g: ■ Sin gle p rocessor ■ Su p p ort for u p to 512K of L2 cach e ■ Su p p ort for u p to 192M of stan d ard DRAM Th is ch ip set d ied off alon g with th e 5v 60/ 66MHz Pen tiu m p rocessors.

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Int el 430NX ( Nept une) . In trod u ced in March of ’94, th e 430NX was th e first ch ip set d esign ed to ru n th e n ew 3.3v secon d gen eration Pen tiu m p rocessor. Th ese were n oted by h avin g Socket 5 p rocessor sockets, an d an on board 3.3v/ 3.5v voltage regu lator for both th e p rocessor an d ch ip set. Th is ch ip set was p rim arily d esign ed for Pen tiu m s with sp eed s from 75MHz to 133MHz, alth ou gh m ostly it was u sed with 75MHz to 100MHz system s. Alon g with th e lower-voltage p rocessor, th is ch ip set ran faster, cooler, an d m ore reliably th an th e first-gen eration Pen tiu m p rocessor an d th e corresp on d in g 5v ch ip sets. √√ See “ CPU Operating Voltages,” p. 72 √√ See “ Second-Generation Pentium Processor,“ p. 110

Th e 430NX ch ip set con sisted of th ree ch ip s for th e North Brid ge com p on en t. Th e p rim ary ch ip was th e 82434NX, wh ich in clu d ed th e cach e an d m ain m em ory (DRAM) con troller an d th e con trol in terface to th e PCI bu s. Th e actu al PCI d ata was m an aged by a p air of 82433NX ch ip s called local bus accelerators. Togeth er, th ese two ch ip s p lu s th e m ain 82434NX ch ip con stitu ted th e North Brid ge. Th e Sou th Brid ge u sed with th e 430NX ch ip set was th e 82378ZB System I/ O (SIO) ch ip . Th is com p on en t con n ected to th e PCI bu s an d gen erated th e lower-sp eed ISA bu s. Th e 430NX ch ip set in trod u ced th e followin g im p rovem en ts over th e Mercu ry (430LX) ch ip set: ■ Du al p rocessor su p p ort ■ Su p p ort for 512M of system m em ory (u p from 192M for th e LX Mercu ry ch ip set) Th is ch ip set rap id ly becam e th e m ost p op u lar ch ip set for th e early 75MHz to 100MHz system s, oversh ad owin g th e old er 60MHz an d 66MHz system s th at u sed th e 430LX ch ip set. Int el 430FX ( Trit on) . Th e 430FX (Triton ) ch ip set rap id ly becam e th e m ost p op u lar ch ip set ever after it was in trod u ced in Jan u ary of ’95. Th is ch ip set is n oted for bein g th e first to su p p ort EDO (Exten d ed Data Ou t) m em ory, wh ich also becam e p op u lar at th e tim e. EDO was sligh tly faster th an th e stan d ard FPM (Fast Page Mod e) m em ory th at h ad been u sed u p u n til th at tim e, bu t cost n o m ore th an th e slower FPM. Un fortu n ately, wh ile bein g kn own for faster m em ory su p p ort, th e Triton ch ip set was also kn own as th e first Pen tiu m ch ip set with ou t su p p ort for p arity ch eckin g for m em ory. Th is was a m ajor blow to PC reliability, alth ou gh m an y d id n ot kn ow it at th e tim e. ◊◊ See “ EDO RAM ,” p. 315 ◊◊ See “ Parity Checking,” p. 347

Th e Triton ch ip set lacked n ot on ly p arity su p p ort from th e p reviou s 430NX ch ip set, bu t it also wou ld on ly su p p ort a sin gle CPU. Th e 430FX was d esign ed as a low-en d ch ip set, for h om e or n on -m ission -critical system s. As su ch , it d id n ot rep lace th e 430NX, wh ich carried on in h igh er-en d n etwork file servers an d oth er m ore m ission -critical system s.

M otherboard Components

Th e 430FX con sisted of a th ree-ch ip North Brid ge. Th e m ain ch ip was th e 82437FX system con troller th at in clu d ed th e m em ory an d cach e con trollers, CPU in terface, an d PCI bu s con troller, alon g with d u al 82438FX d ata p ath ch ip s for th e PCI bu s. Th e Sou th Brid ge was th e first PIIX (PCI ISA IDE Xcelerator) ch ip th at was th e 82371FB. Th is ch ip acted n ot on ly as th e brid ge between th e 33MHz PCI bu s an d th e slower 8MHz ISA bu s, bu t it also in corp orated for th e first tim e a d u al-ch an n el IDE in terface. By m ovin g th e IDE in terface off of th e ISA bu s an d in to th e PIIX ch ip , it was n ow effectively con n ected to th e PCI bu s, allowin g for m u ch faster Bu s Master IDE tran sfers. Th is was key in su p p ortin g th e ATA-2 or En h an ced IDE in terface for better h ard d isk p erform an ce. Th e m ajor p oin ts on th e 430FX are ■ Su p p ort for EDO m em ory ■ Su p p ort for h igh er-sp eed —p ip elin ed bu rst cach e ■ PIIX Sou th Brid ge with h igh -sp eed Bu s Master IDE ■ Lack of su p p ort for p arity-ch ecked m em ory ■ On ly sin gle CPU su p p ort ■ Su p p orted on ly 128M of RAM, of wh ich on ly 64M cou ld be cach ed Th at last issu e is on e th at m an y p eop le are n ot aware of. Th e 430FX ch ip set can on ly cach e u p to 64M of m ain m em ory. Th is m ean s th at if you in stall m ore th an 64M of RAM in you r system , p erform an ce will su ffer greatly. Now, m an y th in k th is won ’t be th at m u ch of a p roblem —after all, th ey d on ’t n orm ally ru n en ou gh software to load p ast th e first 64M an yway. Th at is an oth er m isu n d erstan d in g, becau se W in d ows 95 an d NT load from th e top d own . Th is m ean s, for exam p le, th at if you in stall 96M of RAM (on e 64M an d on e 32M ban k), th en virtu ally all of you r software, in clu d in g th e m ain op eratin g system , will be load in g in to th e n on -cach ed region above 64M. On ly if you u se m ore th an 32M wou ld you begin to see an im p rovem en t in p erform an ce. Try d isablin g th e L2 cach e via you r CMOS setu p to see h ow slow you r system will ru n with ou t it. Th at is th e p erform an ce you can exp ect if you in stall m ore th an 64M of RAM in a 430FX-based system . Th is lack of cach eable m em ory p lu s th e lack of su p p ort for p arity or ECC (error correctin g cod e) m em ory m ake th is a n on -recom m en d ed ch ip set in m y book. Fortu n ately, th is ch ip set becam e obsolete wh en th e m ore p owerfu l 430HX was in trod u ced . Int el 430HX ( Trit on II) . Th e Triton II 430HX ch ip set was created by In tel as a tru e rep lacem en t for th e p owerfu l 430NX ch ip . It ad d ed som e of th e h igh -sp eed m em ory featu res from th e low-en d 430FX, su ch as su p p ort for EDO m em ory an d p ip elin e bu rst L2 cach e. It also retain ed d u al-p rocessor su p p ort an d in ad d ition to su p p ortin g p arity ch eckin g to d etect m em ory errors, it also ad d ed su p p ort for ECC (error-correctin g cod e) m em ory to n ot on ly d etect, bu t to correct, sin gle bit error on -th e-fly. An d th e great th in g was th at th is was im p lem en ted u sin g p lain p arity m em ory.

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Th is was a ch ip set su itable for h igh -en d or m ission -critical system u se su ch as file servers, wh ile also workin g well for lower-en d system s. Parity or ECC m em ory was n ot req u ired — th e ch ip set cou ld easily be con figu red to u se less exp en sive n on p arity, n on correctin g m em ory as well. Th e HX ch ip set’s p rim ary ad van tages over th e FX are ■ Sym m etric Mu ltip rocessor (d u al p rocessor) su p p ort ■ Su p p ort for ECC (Error Correctin g Cod e) an d p arity m em ory ■ 512M m axim u m RAM su p p ort (versu s 128M) ■ L2 cach e fu n ction s over 512M RAM versu s 64M (p rovid in g op tion al cach e Tag RAM is in stalled ) ■ Mem ory tran sfers in fewer cycles overall ■ PCI level 2.1 com p lian ce wh ich allows con cu rren t PCI op eration s ■ PIIX3 su p p orts d ifferen t IDE/ ATA tran sfer sp eed settin gs on a sin gle ch an n el. ■ PIIX3 Sou th Brid ge com p on en t su p p orts USB Th e m em ory p roblem s with cach in g in th e 430FX were corrected in th e 430HX. Th is ch ip set allowed for th e p ossibility of cach in g th e fu ll 512M of p ossible RAM as lon g as th e correct am ou n t of cach e tag was in stalled . Tag is a sm all cach e m em ory ch ip u sed to store th e in d ex to th e d ata in th e cach e. Most 430HX system s sh ip p ed with a tag ch ip th at cou ld on ly m an age 64M of cach ed m ain m em ory, wh ile you cou ld op tion ally u p grad e it to a larger-cap acity tag ch ip th at wou ld allow for cach in g th e fu ll 512M of RAM. Th e 430HX ch ip set was a tru e on e-ch ip North Brid ge. It was also on e of th e first ch ip s ou t in a ball-grid array p ackage, wh ere th e ch ip lead s were con figu red as balls on th e bottom of th e ch ip . Th is allowed for a sm aller ch ip p ackage th an th e p reviou s PQFP (Plastic Qu ad Flat Pack) p ackagin g u sed on th e old er ch ip s, an d , becau se th ere was on ly on e ch ip for th e North Brid ge, a very com p act m oth erboard was p ossible. Th e Sou th Brid ge was th e PIIX3 (82371SB) ch ip , wh ich allowed for in d ep en d en t tim in g of th e d u al IDE ch an n els. Th is m ean t th at you cou ld in stall two d ifferen t sp eed d evices on th e sam e ch an n el an d con figu re th eir tran sfer sp eed s in d ep en d en tly. Previou s PIIX ch ip s allowed both d evices to work at th e lowest com m on d en om in ator sp eed su p p orted by both . Th e PIIX3 also in corp orated th e USB (Un iversal Serial Bu s) for th e first tim e on a PC m oth erboard . Un fortu n ately at th e tim e, th ere were n o d evices available to attach to USB, n or was th ere an y op eratin g system s or d river su p p ort for th e bu s. USB p orts were a cu riosity at th e tim e, an d n obod y h ad a u se for th em . Th e 430HX su p p orts th e n ewer PCI 2.1 stan d ard , wh ich allowed for con cu rren t PCI op eration s an d greater p erform an ce. Com bin ed with th e su p p ort for EDO an d p ip elin ed bu rst cach e, th is was p erh ap s th e best Pen tiu m ch ip set for th e p ower u ser’s system . It offered n ot on ly excellen t p erform an ce, bu t with ECC m em ory it offered a tru ly reliable an d stable system d esign .

M otherboard Components

Th e 430HX was th e on ly m od ern In tel Pen tiu m -class ch ip set to offer p arity an d errorcorrected m em ory su p p ort. Th is m ad e it th e recom m en d ed In tel ch ip set for m ission critical ap p lication s su ch as file servers, d atabase servers, bu sin ess system s, an d so on . Of cou rse, tod ay few wou ld recom m en d u sin g an y typ e of Pen tiu m system as a file server in lieu of a m ore p owerfu l, an d yet n ot m u ch m ore exp en sive, Pen tiu m II system . As th is ch ip set an d m ost of th e Pen tiu m p rocessors are bein g p h ased ou t, you sh ou ld look toward Pen tiu m II system s for th is kin d of su p p ort. Int el 430VX ( Trit on III) . Th e 430VX ch ip set n ever h ad an official cod e-n am e, alth ou gh m an y in th e in d u stry began callin g it th e Triton III. Th e 430VX was d esign ed to be a rep lacem en t for th e low-en d 430FX ch ip set. It was n ot a rep lacem en t for th e h igh erp owered 430HX ch ip set. As su ch , th e VX h as on ly on e sign ifican t tech n ical ad van tage over th e HX, bu t in alm ost all oth er resp ects is m ore like th e 430FX th an th e HX. Th e VX h as th e followin g featu res: ■ Su p p ort for 66MHz SDRAM (syn ch ron ou s DRAM) ■ No p arity or ECC m em ory su p p ort ■ Sin gle p rocessor on ly ■ Su p p orts on ly 128M RAM ■ Su p p orts on ly 64M of cach ed RAM Alth ou gh th e su p p ort for SDRAM is a n ice bon u s, th e actu al sp eed d erived from su ch m em ory is lim ited . Th is is becau se with a good L2 cach e, th ere will on ly be a cach e m iss abou t 5% of th e tim e th e system is read in g or writin g m em ory, wh ich m ean s th at th e cach e p erform an ce is actu ally m ore im p ortan t th an m ain m em ory p erform an ce. Th is is wh y m ost 430HX system s are faster th an 430VX system s even th ou gh th e VX can u se faster SDRAM m em ory. Also, n ote th at becau se th e VX was d esign ed as a low-en d ch ip set for low-cost retail system s, m ost of th em wou ld n ever see an y SDRAM m em ory an yway. Like with th e 430FX, th e VX h as th e lim itation of bein g able to cach e on ly 64M of m ain m em ory. W ith th e m em ory p rice crash of 1996 brin gin g m em ory p rices d own to wh ere m ore th an 64M is actu ally afford able for m ost p eop le, an d with W in d ows software u sin g m ore an d m ore m em ory, th is is really becom in g a lim itation . Th e 430VX ch ip set was rap id ly m ad e obsolete in th e m arket by th e 430TX ch ip set th at followed . Int el 430TX. Th e 430TX ch ip set n ever h ad a cod e-n am e th at I am aware of; h owever, som e p ersisted in callin g it th e Triton IV. Th e 430TX was In tel’s last Pen tiu m ch ip set. It was d esign ed n ot on ly to be u sed in d esktop system s, bu t it was d esign ed to rep lace th e 430MX m obile Pen tiu m ch ip set for lap top an d n otebook system s.

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Th e 430TX h as som e refin em en ts over th e 430VX, bu t, u n fortu n ately, it still lacks su p p ort for p arity or ECC m em ory, an d retain s th e 64M cach eable RAM lim itation of th e old er FX an d VX ch ip sets. Th e 430TX was n ot d esign ed to rep lace th e h igh -en d 430HX ch ip set, wh ich still rem ain ed th e ch ip set of ch oice for m ission -critical system s. Th is is p robably d u e to In tel’s d e-em p h asizin g of th e Pen tiu m ; th ey are tryin g to wean u s from Pen tiu m p rocessors an d force th e m arket, esp ecially for h igh er-en d m ission -critical system s, to th e m ore p owerfu l Pen tiu m II. Th e TX ch ip set featu res in clu d e: ■ 66MHz SDRAM su p p ort ■ Cach eable m em ory still lim ited to 64M ■ Su p p ort for Ultra-ATA, or Ultra-DMA IDE tran sfers ■ Lower p ower con su m p tion for m obile u se ■ No p arity or ECC m em ory su p p ort ■ Sin gle p rocessor on ly Becau se th e Pen tiu m p rocessor h as been relegated to low-en d system u se on ly, th e fact th at it lacks p arity or ECC m em ory su p p ort, as well as th e lack of su p p ort for cach eable m em ory over 64M, h as n ot been th at m u ch of a p roblem for th e m arket for wh ich th is ch ip set is in ten d ed . You sh ou ld n ot u se it for bu sin ess-class system s, esp ecially th ose th at are m ission -critical. Th ose seekin g a tru e h igh -p erform an ce ch ip set an d a system th at is robu st—an d wh ich h as su p p ort for m ission -critical featu res su ch as ECC m em ory or for cach in g m ore th an 64M of m em ory—sh ou ld be lookin g at Pen tiu m II system s an d n ot th e lowly Pen tiu m . In tel h as recen tly stop p ed all fu rth er Pen tiu m p rocessor m an u factu rin g an d is on ly con tin u in g to sell wh at th ey h ave in in ven tory. Third-Part y ( Non-Int el) P5 Pent ium Class Chipset s VIA Te c h n o l o g i e s. VIA Tech n ologies, In c. was fou n d ed in 1987, an d h as becom e a m ajor d esign er of PC m oth erboard ch ip sets. VIA em p loys state-of-th e-art m an u factu rin g cap ability th rou gh fou n d ry relation sh ip s with lead in g silicon m an u factu rers, su ch as Tosh iba an d Taiwan Sem icon d u ctor Man u factu rin g Corp oration . A p o llo V P -1 . Th e VT82C580VP Ap ollo VP-1 is a 4-ch ip set released in October of 1995 an d u sed in old er Socket 5 an d Socket 7 system s. Th e Ap ollo VP-1 is an eq u ivalen t altern ative to th e In tel 430VX ch ip set, an d featu res su p p ort for SDRAM, EDO, or Fast Page Mod e m em ory as well as p ip elin e-bu rst SRAM cach e. Th e VP-1 con sists of th e VT82C585VP 208-p in PQFP (Plastic Qu ad Flat Pack) an d two VT82C587VP 100-p in PQFP ch ip s actin g as th e North Brid ge, an d th e VT82C586 208-p in PQFP Sou th Brid ge ch ip . A p o llo V P 2 . Th e two-ch ip Ap ollo VP2 ch ip set was released in May of 1996. Th e VP2 is a h igh -p erform an ce Socket-7 ch ip set in clu d in g several featu res over th e p reviou s VP-1 ch ip set. Th e VP2 ad d s su p p ort for ECC (Error Correctin g Cod e) m em ory over th e VPX.

M otherboard Components

Th e VP2 h as also been licen sed by AMD as th eir AMD 640 ch ip set. Moth erboard s u sin g th e Ap ollo VP2 can su p p ort P5 class p rocessors, in clu d in g th e In tel Pen tiu m an d Pen tiu m MMX, AMD K5 an d K6, an d Cyrix/ IBM 6x86 an d 6x86MX (MII) p rocessors. Th e VP2 ch ip set con sists of th e VT82C595 328 p in BGA (Ball Grid Array) p ackage North Brid ge ch ip , wh ich su p p orts u p to 2M of L2 cach e an d u p to 512M DRAM. Ad d ition al p erform an ce-related featu res in clu d e a fast DRAM con troller with su p p ort for SDRAM, EDO, BEDO, an d FPM DRAM typ es in m ixed com bin ation s with 32/ 64-bit d ata bu s wid th s an d row an d colu m n ad d ressin g, a d eep er bu ffer with en h an ced p erform an ce, an d an in telligen t PCI bu s con troller with Con cu rren t PCI m aster/ CPU/ IDE (PCI 2.1) op eration s. For d ata in tegrity an d server u se, th e VP2/ 97 in corp orates su p p ort for Error Ch eckin g an d Correctin g (ECC) or p arity m em ory. Th e Ap ollo VP2 featu res th e VIA VT82C586B PCI-IDE Sou th Brid ge con troller ch ip , wh ich com p lies with th e Microsoft PC97 in d u stry sp ecification by su p p ortin g ACPI/ On Now, Ultra DMA/ 33, an d USB tech n ologies. A p o llo V P X. Th e VT82C580VPX Ap ollo VPX is a 4-ch ip set for Socket-7 m oth erboard s released in Decem ber of 1996. Th e Ap ollo VPX is fu n ction ally eq u ivalen t to th e In tel 430TX ch ip set, bu t also h as sp ecific p erform an ce en h an cem en ts relative to th e 430TX. Th e VPX was d esign ed as a rep lacem en t for th e VP-1 ch ip set, an d is an u p grad e of th at set d esign ed to ad d su p p ort for th e n ewer AMD an d Cyrix P5 p rocessors. Th e Ap ollo VPX con sists of th e VT82C585VPX North Brid ge an d VT82C586B Sou th Brid ge ch ip s. Th ere are also two 208-p in PQFP fram e bu ffers th at go with th e North Brid ge m em ory in terface. Th e Ap ollo VPX/ 97 featu res th e VIA VT82C586B PCI-IDE Sou th Brid ge con troller ch ip th at com p lies with th e Microsoft PC97 in d u stry stan d ard by su p p ortin g ACPI/ On Now, Ultra-DMA/ 33, an d USB tech n ologies. VIA also offers a n on PC97 version of th e Ap ollo VPX th at in clu d es th e old er VT82C586A Sou th Brid ge an d wh ich was u sed in m ore en try-level PC d esign s. Moth erboard s u sin g th e Ap ollo VPX can su p p ort P5 class p rocessors, in clu d in g th e In tel Pen tiu m an d Pen tiu m MMX, AMD K5 an d K6, an d Cyrix/ IBM 6x86 an d 6x86MX (MII) p rocessors. To en able p rop er im p lem en tation of th e Cyrix/ IBM 6x86 200+ p rocessor, th e ch ip set featu res an asyn ch ron ou s CPU bu s th at op erates at eith er 66 or 75 MHz sp eed s. Th e Ap ollo VPX is an u p grad e over th e Ap ollo VP-1 with th e ad d ition al featu re of Con cu rren t PCI m aster/ CPU/ IDE op eration s (PCI 2.1). Th e VPX also su p p orts u p to 2M of L2 cach e an d u p to 512M DRAM. A p o llo V P 3 . Th e Ap ollo VP3 is on e of th e first P5 class ch ip sets to im p lem en t th e In tel AGP (Ad van ced Grap h ics Port) sp ecification . In tel offers th at in terface with th eir Pen tiu m II (P6) class ch ip sets. Th is allows a h igh er p erform an ce Socket 7 m oth erboard to be bu ilt th at can accep t th e faster AGP vid eo card s. Th e Socket 7 in terface allows P5 class p rocessors su ch as th e In tel Pen tiu m an d Pen tiu m MMX, AMD K5 an d K6, an d Cyrix/ IBM 6x86 an d 6x86MX (MII) to be u tilized .

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Th e Ap ollo VP3 ch ip set con sists of th e VT82C597 North Brid ge system con troller (472p in BGA) an d th e VT82C586B Sou th Brid ge (208-p in PQFP). Th e VT82C597 North Brid ge p rovid es su p erior p erform an ce between th e CPU, op tion al syn ch ron ou s cach e, DRAM, AGP bu s, an d th e PCI bu s with p ip elin ed , bu rst, an d con cu rren t op eration . Th e VT82C597 com p lies with th e Accelerated Grap h ics Port Sp ecification 1.0 an d featu res a 66 MHz m aster system bu s. A p o llo MV P 3 . Th e Ap ollo MVP3 ad d s to th e VP3 ch ip by su p p ortin g th e n ew Su p er-7 100MHz Socket 7 sp ecification . Th is allows th e n ewer h igh -sp eed P5 p rocessors su ch as th e AMD K6 an d Cyrix/ IBM MII p rocessors to be su p p orted . Th e Ap ollo MVP3 ch ip set is a 2-ch ip ch ip set th at con sists of th e VT82C598AT North Brid ge system con troller an d th e VT82C586B Sou th Brid ge. Th e VT82C598AT ch ip is a 476-p in BGA (Ball Grid Array) p ackage wh ile th e VT82C586B ch ip is a 208-p in PQFP (Plastic Qu ad Flat Pack) p ackage. Th e VT82C598AT North Brid ge ch ip in clu d es th e CPU-to-PCI brid ge, th e L2 cach e an d bu ffer con troller, th e DRAM con troller, th e AGP in terface, an d th e PCI IDE con troller. Th e VT82C598AT North Brid ge p rovid es su p erior p erform an ce between th e CPU, op tion al syn ch ron ou s cach e, DRAM, AGP bu s, an d th e PCI bu s with p ip elin ed , bu rst, an d con cu rren t op eration . Th e DRAM con troller su p p orts stan d ard Fast p age Mod e (FPM), EDO, SDRAM, an d DDR (Dou ble Data Rate) SDRAM. Th e VT82C598AT com p lies with th e Accelerated Grap h ics Port Sp ecification 1.0 an d featu res su p p ort for 66/ 75/ 83/ 100 MHz CPU bu s freq u en cies an d th e 66MHz AGP bu s freq u en cy. Th e VT82C586B Sou th Brid ge in clu d es th e PCI-to-ISA brid ge, ACPI su p p ort, SMBu s, th e USB h ost/ h u b in terface, th e Ultra-33 IDE Master con troller, PS/ 2 Keyboard / Mou se con troller, an d th e I/ O con troller. Th e ch ip also con tain s th e keyboard an d PS/ 2 m ou se con troller. Th is ch ip set is closest to th e In tel 430TX in th at it su p p orts Socket 7 ch ip s (Pen tiu m an d P5-com p atible p rocessors), SDRAM DIMM m em ory, an d is p h ysically a two-ch ip set. It d iffers m ain ly in th at it allows op eration at sp eed s u p to 100MHz an d su p p orts AGP, featu res on ly available with th e Pen tiu m II board s an d ch ip sets from In tel. Th is is an attem p t to m ake th e Socket 7 m oth erboard s an d p rocessors m ore com p etitive with th e lower-en d Pen tiu m II ch ip s su ch as th e Celeron . Th e Sou th Brid ge is com p atible with th e n ewer In tel PIIX4e in th at it in clu d es UDMA IDE, USB, CMOS RAM, p lu s ACPI 1.0 p ower m an agem en t. On e big ben efit over th e In tel 430TX is su p p ort for ECC (Error Correctin g Cod e) m em ory or p arity ch eckin g can be selected on a ban k-by-ban k basis, wh ich allows m ixin g of p arity an d ECC m od u les. Th e 430TX from In tel d oesn ’t su p p ort an y ECC or p arity fu n ction s at all. Mem ory tim in g for FPM is X-3-3-3, wh ile EDO is X-2-2-2, an d SDRAM is X-1-1-1, wh ich is sim ilar to th e In tel 430TX. An oth er ben efit over th e 430TX is in m em ory cach eability. Th e 430TX allows cach in g u p to on ly 64M of m ain m em ory, a sign ifican t lim itation in h igh er-en d system s. Th e m axim u m cach eable ran ge is d eterm in ed by a com bin ation of cach e m em ory size an d th e n u m ber of cach e tag bits u sed . Th e m ost com m on L2 cach e sizes will be 512K or 1M of

M otherboard Components

L2 cach e on th e m oth erboard , allowin g eith er 128M or 256M of m ain m em ory to be cach ed . Th e m axim u m con figu ration of 2M of L2 cach e will allow u p to 512M of m ain m em ory to be cach eable. In tel solves th is in th e Pen tiu m II by in clu d in g su fficien t cach e tag RAM in th e L2 cach e bu ilt in to th e Pen tiu m II p rocessors to allow eith er 512M of m ain m em ory or 4G of m ain m em ory to be cach ed . Th e MVP3 seem s to be th e ch ip set of ch oice in th e h igh er-en d Socket 7 m oth erboard s from DFI, FIC, Tyan , Acer, an d oth ers. Ac e r La b o ra t o ri e s, In c (ALi ). Acer Laboratories, In c. (ALi) was origin ally fou n d ed in 1987 as an in d ep en d en t research an d d evelop m en t cen ter for th e Acer Grou p . In 1993, ALi sep arated fin an cially an d legally from Acer In c. an d becam e a m em ber com p an y of th e Acer Grou p . ALi h as rap id ly claim ed a p rom in en t p osition am on g PC ch ip set m an u factu rers. A la d d i n IV . Th e Alad d in IV from Acer Labs is a two-ch ip set for P5 class p rocessors con sistin g of th e M1531 North Brid ge an d eith er an M1533 or M1543 Sou th Brid ge ch ip . Th e Alad d in IV su p p orts all In tel, AMD, Cyrix/ IBM an d oth er P5-class CPUs in clu d in g th e In tel Pen tiu m an d Pen tiu m MMX, AMD K5 an d K6, an d th e Cyrix/ IBM 6x86 an d 6x86MX (MII) p rocessors. Th e Alad d in IV is eq u ivalen t to th e In tel 430TX ch ip set, with th e ad d ition of error-correctin g m em ory su p p ort an d h igh er-sp eed 75MHz an d 83.3MHz op eration . Also, wh en u sin g th e M1543 Sou th Brid ge, an ad d ition al Su p er I/ O ch ip is n ot n ecessary as th ose fu n ction s are in clu d ed in th e M1543 Sou th Brid ge. Th e M1531 North Brid ge is a 328-p in BGA (Ball Grid Array) ch ip th at su p p orts CPU bu s sp eed s of 83.3 MHz, 75 MHz, 66 MHz, 60 MHz, an d 50MHz. Th e M1531 also su p p orts Pip elin ed -Bu rst SRAM cach e in sizes of u p to 1M, allowin g eith er 64M (with 8-bit Tag SRAM) or u p to 512M (with 11-bit Tag SRAM) of cach eable m ain m em ory. Eith er FPM, EDO, or SDRAM m ain m em ory m od u les are su p p orted for a total cap acity of 1GB in u p to 4 total ban ks. Mem ory tim in g is 6-3-3-3 for back-to-back FPM read s, 5-2-2-2 for backto-back EDO read s, an d 6-1-1-1 for back-to-back SDRAM read s. For reliability an d in tegrity in m ission -critical or server ap p lication s, ECC (Error Correctin g Cod e) or p arity is su p p orted . PCI sp ec. 2.1 is also su p p orted , allowin g con cu rren t PCI op eration s. Th e M1533 Sou th Brid ge in tegrates ACPI su p p ort, 2-ch an n el Ultra-DMA 33 IDE m aster con troller, 2-p ort USB con troller, an d a stan d ard Keyboard / Mou se con troller. A m ore fu ll-fu n ction M1543 Sou th Brid ge is also available th at h as everyth in g in th e M1533 Sou th Brid ge p lu s all th e fu n ction s of a n orm ally sep arate Su p er I/ O con troller. Th e M1543 in tegrates ACPI su p p ort, 2-ch an n el Ultra-DMA 33 IDE con troller, 2-p ort USB con troller, an d a stan d ard keyboard / m ou se con troller. Also in clu d ed is an in tegrated Su p er I/ O in clu d in g a 2.88M flop p y d isk con troller, two h igh -p erform an ce serial p orts, an d a m u lti-m od e p arallel p ort. Th e serial p orts in corp orate 16550-com p atible UARTs (Un iversal Asyn ch ron ou s Receiver Tran sm itters) with 16-byte FIFO (First In First Ou t) bu ffers an d Serial In fra Red (SIR) cap ability. Th e m u ltim od e Parallel Port in clu d es su p p ort for Stan d ard Parallel Port (SPP) m od e, PS/ 2 bid irection al m od e, En h an ced Parallel Port (EPP) m od e, an d th e Microsoft an d Hewlett Packard Exten d ed Cap abilities Port (ECP) m od e.

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A la d d i n V . Th e Acer Labs (ALi) Alad d in V Ch ip set is a two-ch ip set th at con sists of th e M1541 North Brid ge ch ip an d th e M1543 Sou th Brid ge/ Su p er I/ O con troller com bo ch ip . Th e M1541 North Brid ge is a 456-p in BGA p ackage ch ip wh ile th e M1543 Sou th Brid ge is a 328-p in BGA p ackage ch ip . Th e M1541 ch ip set is sim ilar to th e p reviou s M1532 ch ip set with th e ad d ition of h igh er sp eed (u p to 100MHz) op eration an d AGP (Accelerated Grap h ics Port) su p p ort. Th e M1541 North Brid ge in clu d es th e CPU-to-PCI brid ge, th e L2 cach e an d bu ffer con troller, th e DRAM con troller, th e AGP in terface, an d th e PCI con troller. Th e M1541 su p p orts th e Su p er-7 h igh -sp eed 100MHz Socket 7 p rocessor in terface u sed by som e of th e n ewer AMD an d Cyrix/ IBM P5 p rocessors. It will also ru n th e p rocessor bu s at 83.3MHz, 75MHz, 66 MHz, 60 MHz, an d 50MHz for backward com p atibility. W h en ru n n in g th e CPU bu s at 75MHz, th e PCI bu s on ly ru n s at 30MHz; h owever, wh en th e CPU bu s is ru n n in g at 83.3MHz or 100MHz, th e PCI bu s will ru n at fu ll 33MHz PCI stan d ard sp eed . Th e M1541 also in tegrates en ou gh cach e Tag RAM (16K×10) in tern ally to su p p ort 512KB of L2 cach e, sim p lifyin g th e L2 cach e d esign an d fu rth er red u cin g th e n u m ber of ch ip s on th e m oth erboard . Cach eable m em ory is u p to 512M of RAM wh en u sin g 512KB L2 cach e an d 1GB of RAM wh en u sin g 1M of L2 cach e. Eith er FPM, EDO, or SDRAM m em ory is su p p orted , in u p to fou r ban ks an d u p to 1GB total RAM. ECC/ Parity is also su p p orted for m ission -critical or fileserver ap p lication s to im p rove reliability. Mem ory tim in g is 6-3-3-3-3-3-3-3 for back-to-back FPM read s, 5-2-2-2-2-2-2-2 for back-to-back EDO read s, an d 6-1-1-1-2-1-1-1 for back-to-back SDRAM read s. Fin ally, Accelerated Grap h ics Port (AGP) In terface sp ecification V1.0 is su p p orted , alon g with 1x an d 2x m od es, allowin g th e latest grap h ics card s to be u tilized . Th e M1543 Sou th Brid ge an d Su p er I/ O com bo ch ip in clu d es ACPI su p p ort, th e USB h ost/ h u b in terface, d u al ch an n el Ultra-DMA/ 33 IDE h ost in terface, keyboard an d m ou se con troller, an d th e Su p er I/ O con troller. Th e bu ilt-in Su p er I/ O con sists of an in tegrated flop p y d isk con troller, two serial p orts with in frared su p p ort, an d a m u ltim od e p arallel p ort. Si l i c o n i n t e g ra t e d Sy st e m s (Si S). Silicon in tegrated System s (SiS) was form erly kn own as Sym p h on y Labs an d is on e of th e th ree largest n on -In tel PC m oth erboard ch ip set m an u factu rers. 5 5 8 1 a n d 5 5 8 2 . Th e SiS5581 an d 5582 ch ip s are both 553-p in BGA p ackage sin gle-ch ip sets in corp oratin g both North an d Sou th Brid ge fu n ction s. Th e SiS5582 is targeted for AT/ ATX form factor m oth erboard s wh ile th e SiS5581 is in ten d ed to be u sed on LPX/ NLX form factor board s. In all oth er ways, th e two North Brid ge ch ip s are id en tical. Th e SiS 5581/ 5582 is a sin gle-ch ip set d esign ed to be a h igh -p erform an ce, low-cost altern ative th at is fu n ction ally eq u ivalen t to In tel’s 430TX ch ip set. By h avin g everyth in g in a sin gle ch ip , a low-cost m oth erboard can be p rod u ced . Th e 5581/ 5582 con sists of both North an d Sou th Brid ge fu n ction s, in clu d in g PCI to ISA brid ge fu n ction , PCI IDE fu n ction , Un iversal Serial Bu s h ost/ h u b fu n ction , In tegrated RTC, an d In tegrated Keyboard Con troller. Th ese ch ip s su p p ort a CPU bu s sp eed of 50, 55, 60, 66, an d 75MHz.

M otherboard Components

A m axim u m of 512KB of L2 cach e is su p p orted , with a m axim u m cach eable ran ge of 128M of m ain m em ory. Th e m axim u m cach eable ran ge is d eterm in ed by a com bin ation of cach e m em ory size, an d th e n u m ber of Tag bits u sed . Th e m ost com m on cach e size th at will allow cach in g of u p to 128M of RAM will be 512k, alth ou gh u p to 384M of RAM can tech n ically be in stalled in u p to th ree total ban ks. Becau se th is is d esign ed for lowcost system s, ECC (Error Correctin g Cod e) or p arity fu n ction s are n ot su p p orted . Main m em ory tim in g is x-3-3-3 for FPM, wh ile EDO tim in g is x-2-2-2, an d SDRAM tim in g is x-1-1-1. Th e 5581/ 5582 ch ip set also in clu d es Ad van ced Con figu ration an d Power In terface (ACPI) p ower m an agem en t, a d u al ch an n el Ultra-DMA/ 33 IDE in terface, USB con troller, an d even th e CMOS RAM an d Real Tim e Clock (RTC). PCI v2.1 is su p p orted th at allows con cu rren t PCI op eration ; h owever, AGP is n ot su p p orted in th is ch ip set. 5 5 9 1 a n d 5 5 9 2 . Th e SiS 5591/ 5592 is a th ree-ch ip set con sistin g of eith er a 5591 or 5592 North Brid ge ch ip alon g with a SiS5595 Sou th Brid ge. Th e 5591/ 5592 North Brid ge ch ip s are both 3.3v 553-p in BGA p ackage ch ip s, wh ile th e 5595 Sou th Brid ge ch ip is a 5v 208-p in PQFP (Plastic Qu ad Flat Pack) p ackage ch ip . Th e SiS5591 North Brid ge is targeted for ATX form factor m oth erboard s wh ile th e SiS5592 version is in ten d ed to be u sed on th e NLX form factor. In all oth er ways, th e two North Brid ge ch ip s are id en tical. Th e 5591/ 5592 North Brid ge ch ip s in clu d e th e Host-to-PCI brid ge, th e L2 cach e con troller, th e DRAM con troller, th e Accelerated Grap h ics Port in terface, an d th e PCI IDE con troller. Th e SiS5595 Sou th Brid ge in clu d es th e PCI-to-ISA brid ge, th e ACPI/ APM p ower m an agem en t u n it, th e Un iversal Serial Bu s h ost/ h u b in terface, an d th e ISA bu s in terface th at con tain s th e ISA bu s con troller, th e DMA con trollers, th e in terru p t con trollers, an d th e Tim ers. It also in tegrates th e Keyboard con troller an d th e Real Tim e Clock (RTC). Th e 5591/ 5592 North Brid ge ch ip s su p p ort CPU bu s sp eed s of u p to 75MHz. Th ey also su p p ort u p to 1M of L2 cach e allowin g u p to 256M of m ain m em ory to be cach eable. Th e m axim u m cach eable m ain m em ory am ou n t is d eterm in ed by a com bin ation of cach e m em ory size an d th e n u m ber of Tag bits u sed . Most com m on cach e sizes will be 512K an d 1M. Th e 512K cach e with 7 Tag bits will allow on ly 64M of m em ory to be cach ed , wh ile 8 Tag bits will allow cach in g of u p to 128M. W ith 1M of cach e on board , th e cach eable ran ge is d ou bled to a m axim u m of 256M. A m axim u m of 256M of total RAM is allowed in u p to th ree ban ks. Both ECC an d p arity are su p p orted for m ission -critical or file server ap p lication s. Main m em ory tim in g for FPM m em ory is x-3-3-3, EDO tim in g is x-2-2-2, an d SDRAM is x-1-1-1. PCI sp ecification 2.1 is su p p orted at u p to 33MHz, an d AGP sp ecification 1.0 is su p p orted in both 1x an d 2x m od es. Th e sep arate 5595 Sou th Brid ge in clu d es a d u al-ch an n el UltraDMA/ 33 in terface an d su p p ort for USB. Sixt h-Generat ion ( P6 Pent ium Pro/ Pent ium II Class) Chipset s Alth ou gh In tel clearly d om in ated th e Pen tiu m ch ip set world , th ey are virtu ally th e on ly gam e in town for th e Pen tiu m Pro an d Pen tiu m II ch ip sets. Th e biggest reason for th is is th at sin ce th e Pen tiu m first cam e ou t in 1993, In tel h as been in trod u cin g n ew ch ip sets

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(an d even com p lete read y-to-go m oth erboard s) sim u ltan eou sly with th eir n ew p rocessors. Th is m akes it h ard for an ybod y else to catch u p . An oth er p roblem for oth er ch ip set m an u factu rers is th at In tel h as yet to licen se th e Slot 1 in terface u sed by th e Pen tiu m II p rocessor, wh ile th e Socket 7 in terface u sed by th e Pen tiu m h as been freely available for licen se. Clearly, In tel wan ts th e Pen tiu m II m arket to th em selves. Even th ou gh In tel h as refu sed to licen se th e Slot 1 in terface, several of th e th ird -p arty ch ip set m an u factu rers su ch as VIA Tech n ologies, Acer Laboratories, In c (ALi), an d Silicon in tegrated System s (SiS) h ave recen tly in trod u ced Pen tiu m II ch ip sets for Slot 1 m oth erboard s. W ith ou t d irect licen sin g, th ese com p an ies h ave h ad to reverse en gin eer th e Slot 1 d esign , wh ich is p erh ap s th e biggest reason wh y it h as taken so lon g for th ird p arty Pen tiu m Pro an d Pen tiu m II ch ip sets to com e ou t. Note th at becau se th e Pen tiu m Pro an d Pen tiu m II are essen tially th e sam e p rocessor with sligh tly d ifferen t cach e d esign s, th e sam e ch ip set can be u sed for both Socket 8 (Pen tiu m Pro) an d Slot 1 (Pen tiu m II) d esign s. At least th at was tru e for th e som e of th e old er P6 class ch ip sets su ch as th e In tel 440FX. Newer ch ip sets startin g with th e 440LX are op tim ized for th e Slot 1 arch itectu re an d p robably won ’t be u sed on Socket 8 d esign s. Th is is also tru e for th e Pen tiu m Pro, wh ich is essen tially obsolete com p ared to th e Pen tiu m II an d is cu rren tly bein g u sed on ly in lim ited file server ap p lication s. Alth ou gh th ere are a few n ewcom ers to th e P6 ch ip set m arket, virtu ally all Pen tiu m Pro an d Pen tiu m II m oth erboard s u se In tel ch ip sets; th eir m arket sh are h ere is for all p ractical p u rp oses n ear 100%. Th e sixth -gen eration P6 (Pen tiu m Pro/ II) ch ip sets con tin u e with th e North Brid ge/ Sou th Brid ge d esign first d ebu ted in th e Pen tiu m p rocessor ch ip sets. In fact, th e Sou th Brid ge p ortion of th e ch ip set is th e sam e as th at u sed in m an y of th e Pen tiu m ch ip sets. Table 4.6 sh ows th e p rocessors u sed on Pen tiu m Pro m oth erboard s. Table 4.6

Pent ium Pro Chipset s

Chipset

450KX

450GX

440FX

Codenam e

Orion Workstation

Orion Server

Natoma

Dat e Int roduced

Nov. ’95

Nov. ’95

M ay ’96

Bus Speed

66 M Hz

66 M Hz

66 M Hz

SM P ( dual CPUs)

Yes

Yes (4 CPUs)

Yes

M em ory Types

FPM

FPM

FPM / EDO/ BEDO

Parit y/ ECC

Both

Both

Both

M axim um M em ory

8GGB

1GB

1GB

L2 Cache Type

In CPU

In CPU

In CPU

M axim um Cacheable

1GB

1GB

1GB

PCI Support

2.0

2.0

2.1

AGP Support

No

No

No

M otherboard Components

Chipset

450KX

450GX

440FX

AGP Speed

n/ a

n/ a

n/ a

Sout h Bridge

various

various

PIIX3

SMP = Sym m etric Multi-processing (Dual Processors) FPM = Fast Page Mode EDO = Extended Data Out BEDO = Burst EDO SDRAM = Synchronous Dynam ic RAM Pburst = Pipeline Burst (Synchronous) PCI = Peripheral Com ponent Interconnect AGP = Accelerated Graphics Port SIO = System I/O PIIX = PCI ISA IDE X celerator

Not e PCI 2.1 supports concurrent PCI operations.

For Pen tiu m II ch ip sets, In tel offers th e ch ip sets in Table 4.7. Table 4.7

Pent ium II Chipset s

Chipset

440FX

440LX

440EX

440BX

Codenam e Dat e Int roduced

Natoma

none

none

none

M ay ’96

Aug. ’97

April ’98

April ’98

Bus Speed

66 M Hz

66 M Hz

66 M Hz

66/ 100 M Hz

SM P ( dual CPUs)

Yes

Yes

No

Yes

M em ory Types

FPM / EDO/ BEDO

FPM / EDO/ SDRAM

FPM / EDO/ SDRAM

FPM / EDO/ SDRAM

Parit y/ ECC

Both

Both

Neither

Both

M axim um M em ory

1G

1GB EDO/ 512M M SDRAM

256M M

1G

L2 Cache Type

In CPU

In CPU

In CPU

In CPU

M ax. Cacheable

1G

1G

1G

1G

PCI Support

2.1

2.1

2.1

2.1

AGP Support

No

AGP-1x

AGP-1x

AGP-2x

AGP Speed

n/ a

266M M / sec

266M M / sec

533M M / sec

Sout h Bridge

PIIX3

PIIX4

PIIX4E

PIIX4E

SMP = Sym m etric Multi-processing (Dual Processors) FPM = Fast Page Mode EDO = Extended Data Out BEDO = Burst EDO SDRAM = Synchronous Dynam ic RAM Pburst = Pipeline Burst (Synchronous) PCI = Peripheral Com ponent Interconnect AGP = Accelerated Graphics Port SIO = System I/O PIIX = PCI ISA IDE X celerator

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Not e Pentium Pro and Pentium II CPUs have their secondary cache integrated into the CPU package. Therefore, cache characteristics for these machines are not dependent on the chipset but are quite dependent on the Pentium Pro or Pentium II processor instead. Note also that the Pentium II Celeron has no L2 (secondary) cache.

Each In tel ch ip set is d esign ed as a two-p art system , u sin g a North Brid ge an d a Sou th Brid ge com p on en t. Often th e sam e Sou th Brid ge com p on en t can be u sed with several d ifferen t North Brid ge ch ip sets. Table 4.8 sh ows a list of all th e cu rren t In tel Sou th Brid ge com p on en ts an d th eir cap abilities. Table 4.8

Int el Sout h Bridge Chips

Chip Nam e

SIO

PIIX

PIIX3

PIIX4

PIIX4E 82371EB

Part Number

82378IB/ ZB

82371FB

82371SB

82371AB

IDE Support

None

BM IDE

BM IDE

UDM A

UDM A

USB Support

None

None

Yes

Yes

Yes

CM OS/ Clock

No

No

No

Yes

Yes

Power M anagement

SM M

SM M

SM M

SM M

ACPI 1.0

SIO = System I/O PIIX = PCI ISA IDE X celerator USB = Universal Serial Bus IDE = Integrated Drive Electronics (AT Attachm ent) BMIDE = Bus Master IDE UDMA = Ultra-DMA IDE SMM = System Managem ent Mode ACPI = Advanced Configuration and Power Interface specification

Th e followin g section s exam in e th e P6 ch ip sets for both th e Pen tiu m Pro an d Pen tiu m II p rocessors. Int el 450KX/ GX ( Orion W orkst at ion/ Server) . Th e first ch ip sets to su p p ort th e Pen tiu m Pro were th e 450KX an d GX, both cod e n am ed Orion . Th e 450KX was d esign ed for n etworked or stan d alon e workstation s wh ile th e m ore p owerfu l 450GX was d esign ed for file servers. Th e GX server ch ip set was p articu larly su ited to th e server role, as it su p p orted u p to fou r Pen tiu m Pro p rocessors for Sym m etric Mu ltip rocessin g (SMP) servers, u p to 8G of 4-way in terleaved m em ory with ECC or p arity, an d two brid ged PCI bu ses. Th e 450KX is th e workstation or stan d alon e u ser version of Orion an d as su ch it su p p orts fewer p rocessors (on e or two) an d less m em ory (1G) th an th e GX. Th e 450GX an d 450KX North Brid ge is com p rised of fou r in d ivid u al ch ip com p on en ts— an 82454KX/ GX PCI Brid ge, an 82452KX/ GX Data Path (DP), an 82453KX/ GX Data Con troller (DC), an d an 82451KX/ GX Mem ory In terface Con troller (MIC). Op tion s for

M otherboard Components

QFP (Qu ad Flat Pack) or BGA (Ball Grid Array) p ackagin g were available on th e PCI Brid ge an d th e DP. BGA u ses less sp ace on a board . Th e 450’s h igh reliability is obtain ed th rou gh ECC from th e Pen tiu m Pro p rocessor d ata bu s to m em ory. Reliability is also en h an ced by p arity p rotection on th e p rocessor bu s, con trol bu s, an d on all PCI sign als. In ad d ition , sin gle-bit error correction is p rovid ed , th ereby avoid in g server d own tim e d u e to sp u riou s m em ory errors cau sed by cosm ic rays. ◊◊ See “ M emory Reliability,” p. 344

Un til th e in trod u ction of th e followin g 440FX ch ip set, th ese were u sed alm ost exclu sively in file servers. After th e d ebu t of th e 440FX, th e exp en sive Orion ch ip s all bu t d isap p eared d u e to th eir com p lexity an d h igh cost. Int el 440FX ( Nat om a) . Th e first p op u lar m ain stream P6 (Pen tiu m Pro or Pen tiu m II) m oth erboard ch ip set was th e 440FX, wh ich was cod e n am ed Natom a. Th e 440FX was d esign ed by In tel to be a lower cost an d som ewh at h igh er p erform an ce rep lacem en t for th e 450KX workstation ch ip set. It offered better m em ory p erform an ce th rou gh su p p ort of EDO m em ory, wh ich th e p rior 450KX lacked . Th e 440FX u ses h alf th e n u m ber of com p on en ts th an th e p reviou s In tel ch ip set. It offers ad d ition al featu res su ch as su p p ort for th e PCI 2.1 (Con cu rren t PCI) stan d ard , Un iversal Serial Bu s (USB) su p p ort, an d reliability th rou gh Error Ch eckin g an d Correction (ECC). Th e Con cu rren t PCI p rocessin g arch itectu re m axim izes system p erform an ce with sim u ltan eou s activity on th e CPU, PCI, an d ISA bu ses. Con cu rren t PCI p rovid es in creased ban d wid th to better su p p ort 2D/ 3D grap h ics, vid eo an d au d io, an d p rocessin g for h ostbased ap p lication s. ECC m em ory su p p ort d elivers im p roved reliability to bu sin ess system u sers. Th e m ain featu res of th is ch ip set in clu d e: ■ Su p p ort for u p to 1G of EDO m em ory ■ Fu ll 1G cach eability (based on th e p rocessor becau se th e L2 cach e an d tag are in th e CPU) ■ Su p p ort for USB ■ Su p p ort for Bu sMaster IDE ■ Fu ll p arity/ ECC su p p ort Th e 440FX con sists of a two-ch ip North Brid ge. Th e m ain com p on en t is th e 82441FX PCI Brid ge an d Mem ory con troller, alon g with th e 82442FX Data Bu s accelerator for th e PCI bu s. Th is ch ip set u ses th e PIIX3 82371SB Sou th Brid ge ch ip th at su p p orts h igh -sp eed bu sm aster DMA IDE in terfaces an d USB, an d it acts as th e brid ge between th e PCI an d ISA bu ses.

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Note th at th is was th e first P6 ch ip set to su p p ort EDO m em ory, bu t it lacked su p p ort for th e faster SDRAM. Also, th e PIIX3 u sed with th is ch ip set d oes n ot su p p ort th e faster Ultra DMA IDE h ard d rives. Th e 440FX was th e ch ip set u sed on th e first Pen tiu m II m oth erboard s, wh ich h ave th e sam e basic arch itectu re as th e Pen tiu m Pro. Th e Pen tiu m II was released several m on th s before th e ch ip set th at was su p p osed ly d esign ed for it was read y, an d so early PII m oth erboard s u sed th e old er 440FX ch ip set. Th is ch ip set was n ever d esign ed with th e Pen tiu m II in m in d , wh ile th e n ewer 440LX was op tim ized sp ecifically to take ad van tage of th e Pen tiu m II arch itectu re. For th at reason , I n orm ally recom m en d ed th at p eop le stay away from th e origin al 440FX-based PII m oth erboard s an d wait for Pen tiu m II system s th at u sed th e forth com in g 440LX ch ip set. W h en th e n ew ch ip set was in trod u ced , th e 440FX was q u ickly su p ersed ed by th e im p roved 440LX d esign . Int el 440LX. Th e 440LX q u ickly took over in th e m arketp lace after it d ebu ted in Au gu st of ’97. Th is was th e first ch ip set to really take fu ll ad van tage of th e Pen tiu m II p rocessor. Com p ared to th e 440FX, th e 440LX ch ip set offers several im p rovem en ts: ■ Su p p ort for th e n ew Ad van ced Grap h ics Port (AGP) vid eo card bu s ■ Su p p ort for 66MHz SDRAM m em ory ■ Su p p ort for th e Ultra DMA IDE in terface ■ Su p p ort for Un iversal Serial Bu s (USB) Th e 440LX rap id ly becam e th e m ost p op u lar ch ip for all n ew Pen tiu m II system s from th e en d of ’97 th rou gh th e begin n in g of ’98. Int el 440EX. Th e 440EX is d esign ed to be a low-cost lower p erform an ce altern ative to th e 440LX ch ip set. It was in trod u ced in Ap ril ’98 alon g with th e In tel Celeron low-en d Pen tiu m II p rocessor. Th e 440EX lacks several featu res in th e m ore p owerfu l 440LX, in clu d in g d u al p rocessor an d ECC or p arity m em ory su p p ort. Th is ch ip set is basically d esign ed for low-en d 66MHz bu s-based system s th at u se th e n ew In tel Celeron low-en d Pen tiu m II p rocessor. Note th at board s with th e 440EX will fu lly su p p ort a fu ll blown Pen tiu m II bu t lack som e of th e featu res of th e m ore p owerfu l 440LX or 440BX ch ip sets. Th e m ain th in gs to n ote abou t th e 440EX are: ■ Design ed with a featu re set tu n ed for th e low-en d PC m arket ■ Prim arily for th e In tel Celeron p rocessor ■ Su p p orts AGP ■ Does n ot su p p ort ECC or p arity m em ory ■ Sin gle p rocessor su p p ort on ly Alth ou gh it is based on th e core tech n ology of th e In tel 440LX, th e 440EX is basically con sid ered a lower-featu re, lower-reliability version of th at ch ip set d esign ed for n on m ission -critical system s.

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Th e 440EX con sists of a 82443EX PCI AGP Con troller (PAC) North Brid ge com p on en t an d th e n ew 82371EB (PIIX4E) Sou th Brid ge ch ip . Alth ou gh th is ch ip set is fin e for m ost low-en d u se, I wou ld n orm ally recom m en d th e faster, m ore p owerfu l, an d m ore reliable (with ECC m em ory) 440BX in stead . Int el 440BX. Th e In tel 440BX ch ip set was in trod u ced in Ap ril of ’98 an d is th e first ch ip set to ru n th e p rocessor h ost bu s (an d basically th e m oth erboard ) at 100MHz. Th is is d esign ed sp ecifically to su p p ort th e n ewer Pen tiu m II p rocessors at 350MHz, 400MHz, or 450MHz. A m obile version of th is ch ip set also is th e first Pen tiu m II ch ip set for n otebook or lap top system s. Th e m ain ch an ge from th e 440LX to th e BX is th at th e 440BX ch ip set im p roves p erform an ce by in creasin g th e ban d wid th of th e system bu s from 66MHz to 100MHz. Th e ch ip set can ru n at eith er 66- or 100MHz, allowin g on e basic m oth erboard d esign to su p p ort all Pen tiu m II p rocessor sp eed s from 233MHz to 450MHz an d beyon d . In tel 440BX High ligh ts: ■ Su p p orts 100MHz SDRAM ■ Su p p orts both 100MHz or 66MHz system an d m em ory bu s d esign s ■ Su p p orts ACPI (Ad van ced Con figu ration an d Power In terface sp ecification ) ■ Th e first ch ip set to su p p ort th e Mobile In tel Pen tiu m II p rocessor. ◊◊ See “ M obile Pentium II,” p. 919

Th e In tel 440BX con sists of a sin gle North Brid ge ch ip called th e 82443BX Host Brid ge/ Con troller, wh ich is p aired with a n ew 82371EB PCI-ISA/ IDE Xcelerator (PIIX4E) Sou th Brid ge ch ip . Th e n ew Sou th Brid ge ad d s su p p ort for th e ACPI sp ecification version 1.0. Th e 440BX is cu rren tly th e h igh est-en d ch ip set in th e In tel arsen al for stan d ard d esktop u sers. It offers su p erior p erform an ce an d h igh reliability th rou gh th e u se of ECC (Error Correctin g Cod e), SDRAM (Syn ch ron ou s DRAM), an d DIMMs (Du al In lin e Mem ory Mod u les). If you are in th e m arket for a n ew Pen tiu m II-based system , I wou ld recom m en d a m oth erboard with th is ch ip set. Third-Part y ( Non-Int el) P6 Class Chipset s Ac e r La b o ra t o ri e s, In c . (ALi ) A la d d i n P r o II. Th e Acer Labs (ALi) Alad d in Pro II M1621 is a two-ch ip set for P6 (Pen tiu m Pro an d Pen tiu m II) p rocessors con sistin g of two BGA p ackage ch ip s, th e 456p in BGA p ackage M1621 North Brid ge, an d eith er th e M1533 or M1543 Sou th Brid ge. Th is is on e of th e first Slot 1 P6 p rocessor ch ip sets from a com p an y oth er th an In tel. Th e M1621 North Brid ge in clu d es an AGP, m em ory an d I/ O con troller, an d a d ata p ath with m u ltip ort bu ffers for d ata acceleration . It can su p p ort m u ltip le Pen tiu m II

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p rocessors with bu s sp eed s of 60, 66, an d 100MHz. Th is ch ip set is eq u ivalen t to th e 440BX ch ip set from In tel. Th e in tegrated m em ory con troller su p p orts FPM, EDO, an d SDRAM with a total cap acity of u p to 1G (SDRAM) or 2G (EDO). ECC (Error Correctin g Cod e) m em ory is su p p orted , allowin g u se in m ission -critical or fileserver ap p lication s. Mem ory tim in g is x-1-1-1-1-11-1 in back-to-back SDRAM read s, or x-2-2-2-2-2-2-2 in back-to-back EDO read s. Th e M1621 su p p orts AGP v1.0, in both 1x an d 2x m od es, an d is fu lly com p lian t with PCI Rev. 2.1, allowin g for con cu rren t PCI op eration s. Th e M1621 can be u sed with eith er th e M1533 Sou th Brid ge or M1543 Sou th Brid ge/ Su p er I/ O com bo ch ip s. Th e M1533 Sou th Brid ge in clu d es th e followin g featu res: ■ PCI-to-ISA Brid ge ■ Bu ilt-in keyboard / m ou se con troller ■ En h an ced Power Man agem en t featu rin g ACPI (Ad van ced Con figu ration an d Power In terface) ■ Two-p ort USB in terface ■ Du al ch an n el Ultra-DMA/ 33 IDE h ost ad ap ter ■ 328-p in BGA p ackage M1543 in clu d es all featu res in th e 1533 p lu s fu lly in tegrated Su p er I/ O, in clu d in g a Flop p y Disk Con troller, two h igh -sp eed serial p orts, an d on e m u ltim od e p arallel p ort. VIA Te c h n o l o g i e s A p o llo P 6 /9 7 . Th e VT82C680 Ap ollo P6 is a h igh -p erform an ce, cost-effective, an d en ergy-efficien t ch ip set for th e im p lem en tation of PCI/ ISA d esktop an d n otebook p erson al com p u ter system s based on 64-bit In tel P6 p rocessors. Th is was on e of th e first n on -In tel P6 ch ip sets of an y kin d available an d is fu n ction ally eq u ivalen t to th e In tel 440FX ch ip set. Th e Ap ollo P6 ch ip set su p p orts d u al p rocessor con figu ration s with u p to 66MHz extern al CPU bu s sp eed . Th e DRAM an d PCI bu s are also in d ep en d en tly p owered so th at each of th e bu ses can be ru n at 3.3v or 5v. Th e ISA bu s always ru n s at 5v. Th e Ap ollo P6 su p p orts u p to 1G of DRAM. Th is ch ip set n ever really ach ieved m u ch p op u larity in th e m arket. A p o llo P r o . Th e Ap ollo Pro is a h igh -p erform an ce ch ip set for Slot 1 m obile an d d esktop PC system s. Th e Ap ollo Pro in clu d es su p p ort for ad van ced system p ower m an agem en t cap ability for both d esktop an d m obile PC ap p lication s, PC100 SDRAM, AGP 2x m od e, an d m u ltip le CPU/ DRAM tim in g con figu ration s. Th e Ap ollo Pro ch ip set is com p arable in featu res to th e 440BX an d PIIX4e ch ip set from In tel, an d rep resen ts on e of th e first n on In tel ch ip sets to su p p ort th e Socket 1 arch itectu re. Th e VIA Ap ollo Pro con sists of two d evices—th e VT82C691 North Brid ge ch ip an d th e VT82C596, a BGA-p ackaged Sou th Brid ge with a fu ll set of m obile, p ower-m an agem en t

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featu res. For cost-effective d esktop d esign s, th e VT82C691 can also be con figu red with th e VT82C586B Sou th Brid ge. Th e VT82C691 Ap ollo Pro North Brid ge su p p orts all Slot-1 (In tel Pen tiu m II) an d Socket8 (In tel Pen tiu m Pro) p rocessors. Th e Ap ollo Pro also su p p orts th e 66MHz an d th e n ewer 100 MHz CPU extern al bu s sp eed req u ired by th e 350MHz an d faster Pen tiu m II p rocessors. AGP v1.0 an d PCI 2.1 are also su p p orted , as are FPM, EDO, an d SDRAM. Differen t DRAM typ es m ay be u sed in m ixed com bin ation s in u p to eigh t ban ks an d u p to 1G of DRAM. EDO m em ory tim in g is 5-2-2-2-2-2-2-2 for back-to-back accesses, an d SDRAM tim in g is 6-1-1-1-2-1-1-1 for back-to-back accesses. Th e VT82C596 Sou th Brid ge su p p orts both ACPI (Ad van ced Con figu ration an d Power In terface) an d APM (Ad van ced Power Man agem en t), an d in clu d es an in tegrated USB Con troller, an d d u al UltraDMA-66 EIDE p orts. Si l i c o n i n t e g ra t e d Sy st e m s (Si S) Si S5 6 0 0 /5 5 9 5 . Th e 5600/ 5595 ch ip set was in trod u ced in Ju n e of 1998 an d is d esign ed for low-cost Celeron CPUs with a 66MHz or 100MHz h ost bu s. SiS in ten d s to u se th is low-cost ch ip set to h elp p u sh th e Pen tiu m II PC tech n ology toward th e su b-$1,000 PC m arket. Super I/ O Chips Th e th ird m ajor ch ip seen on m ost PC m oth erboard s is called th e Su p er I/ O ch ip . Th is is a ch ip th at n orm ally in tegrates d evices form erly fou n d on sep arate exp an sion card s in old er system s. Most Su p er I/ O ch ip s con tain at a m in im u m th e followin g com p on en ts: ■ Flop p y con troller ■ Du al serial p ort con trollers ■ Parallel p ort con troller Th e flop p y con trollers on m ost Su p er I/ O ch ip s will h an d le two d rives, bu t som e of th em can on ly h an d le on e. Old er system s often req u ired a sep arate flop p y con troller card . Th e d u al serial p ort is an oth er item th at was form erly on on e or m ore card s. Most of th e better Su p er I/ O ch ip s im p lem en t a bu ffered serial p ort d esign kn own as a UART (Un iversal Asyn ch ron ou s Receiver Tran sm itter), on e for each p ort. Most m im ic th e stan d alon e NS16550A h igh -sp eed UART, wh ich was created by Nation al Sem icon d u ctor. By p u ttin g th e fu n ction of two of th ese ch ip s in to th e Su p er I/ O ch ip , we essen tially h ave th ese p orts bu ilt in to th e m oth erboard . Virtu ally all Su p er I/ O ch ip s also in clu d e a h igh -sp eed m u ltim od e p arallel p ort. Th e better on es allow th ree m od es, called stan d ard (bid irection al), En h an ced Parallel Port (EPP), an d th e En h an ced Cap abilities Port (ECP) m od es. Th e ECP m od e is th e fastest an d m ost p owerfu l, bu t selectin g it also m ean s you r p ort will u se an ISA bu s 8-bit DMA ch an n el, u su ally DMA ch an n el 3. As lon g as you accou n t for th is an d d on ’t set an yth in g else to

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th at ch an n el (su ch as a sou n d card , an d so on ), th en th e EPC m od e p arallel p ort sh ou ld work fin e. Som e of th e n ewer p rin ters an d scan n ers th at con n ect to th e system via th e p arallel p ort will u se ECP m od e, wh ich was in itially in ven ted by Hewlett Packard . Th e Su p er I/ O ch ip m ay con tain oth er com p on en ts, as well. For exam p le, cu rren tly th e m ost p op u lar Pen tiu m II m oth erboard on th e m arket—th e In tel SE440BX ATX m oth erboard —u ses an SMC (Stan d ard Microsystem s Corp .) FDC37C777 Su p er I/ O ch ip . Th is ch ip in corp orates th e followin g fu n ction s: ■ Sin gle flop p y d rive in terface ■ Two h igh -sp eed serial p orts ■ On e ECP/ EPP m u ltim od e p arallel p ort ■ 8042-style keyboard an d m ou se con troller On ly th e keyboard an d m ou se con troller are su rp risin g h ere; all th e oth er com p on en ts are in m ost Su p er I/ O ch ip s. Th e in tegrated keyboard an d m ou se con troller saves th e n eed to h ave th is ch ip as a sep arate p art on th e board . On e th in g I’ve n oticed over th e years is th at th e role of th e Su p er I/ O ch ip h as d ecreased m ore an d m ore in th e n ewer m oth erboard s. Th is is p rim arily d u e to In tel m ovin g Su p er I/ O fu n ction s su ch as IDE d irectly in to th e ch ip set Sou th Brid ge com p on en t, wh ere th ese d evices can attach to th e PCI bu s rath er th an th e ISA bu s. On e of th e sh ortcom in gs of th e Su p er I/ O ch ip is th at it is in terfaced to th e system via th e ISA bu s, an d sh ares all th e sp eed an d p erform an ce lim itation s of th at 8MHz bu s. Movin g th e IDE over to th e PCI bu s allowed h igh er-sp eed IDE d rives to be d evelop ed th at cou ld tran sfer at th e faster 33MHz PCI bu s sp eed . As In tel com bin es m ore an d m ore fu n ction s in to th eir m ain ch ip set, an d as USB-based p erip h erals rep lace stan d ard serial, p arallel, an d flop p y con troller-based d evices, we will p robably see th e Su p er I/ O ch ip fad e away on som e fu tu re m oth erboard d esign s. At least on e of th e th ird -p arty ch ip sets h as alread y com bin ed th e Sou th Brid ge an d Su p er I/ O ch ip in to a sin gle com p on en t, savin g sp ace an d red u cin g p arts cou n t on th e m oth erboard . BIOS All m oth erboard s m u st h ave a sp ecial ch ip con tain in g software we call th e BIOS or ROM BIOS. ROM stan d s for Read On ly Mem ory, an d BIOS stan d s for Basic In p u t/ Ou tp u t System . Th is ch ip con tain s th e startu p p rogram s an d d rivers th at are u sed to get th e system ru n n in g an d act as th e in terface to th e basic h ard ware in th e system . Th ere is also a POST (Power-On Self Test) in th e BIOS th at tests th e m ajor com p on en ts in th e system wh en you tu rn it on , an d n orm ally a SETUP p rogram u sed to store system con figu ration d ata in th e CMOS (Com p lem en tary Metal-Oxid e Sem icon d u ctor) m em ory p owered by a battery on th e m oth erboard . Th e BIOS is a collection of p rogram s em bed d ed in an EPROM (Erasable Program m able Read -On ly Mem ory) or EEPROM (Electrically Erasable PROM)—oth erwise called a Flash

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ROM ch ip or ch ip s, d ep en d in g on th e d esign of you r com p u ter. Th at collection of p rogram s is th e first th in g load ed wh en you start you r com p u ter, even before th e op eratin g system . Sim p ly p u t, th e BIOS in m ost PCs h as fou r m ain fu n ction s: ■ POST— Power-On Self Test. Th e POST tests you r com p u ter’s p rocessor, m em ory, ch ip set, vid eo ad ap ter, d isk con trollers, d isk d rives, keyboard , an d oth er cru cial com p on en ts. ■ Bootstrap loader. A rou tin e th at fin d s th e op eratin g system an d load s, or boots, it. If an op eratin g system is fou n d , it is load ed an d given con trol of you r com p u ter. ■ BIOS— Basic Input Output System . Th is refers to th e collection of actu al d rivers u sed to act as a basic in terface between th e op eratin g system an d you r h ard ware. W h en ru n n in g DOS or W in d ows in Safe Mod e, you are ru n n in g solely on BIOS d rivers. ■ CMOS setup. System con figu ration an d setu p p rogram . Th is is a n orm ally m en u d riven p rogram th at allows you to con figu re th e m oth erboard an d ch ip set settin gs, alon g with th e d ate an d tim e, p assword s, d isk d rives, an d oth er basic system settin gs. Som e old er system s d id n ot h ave th e Setu p p rogram in ROM an d req u ired th at you boot from a sp ecial Setu p d isk. Th e followin g section d iscu sses th e m oth erboard BIOS. ◊◊ See “ ROM ,” p. 304

ROM BIOS Com pat ibilit y. Th e issu e of ROM BIOS com p atibility is im p ortan t. If th e BIOS is n ot com p atible with th e PC stan d ard IBM origin ally created , an y n u m ber of p roblem s can resu lt. Th e BIOS is th e in terface between th e system h ard ware an d th e op eratin g system , so com p atibility with p op u lar op eratin g system s like W in d ows is im p ortan t. By in clu d in g d rivers in th e BIOS for an y u n iq u e or cu stom com p on en ts, a system m an u factu rer can en su re th at an y of th ese com p on en ts will work with th e p op u lar op eratin g system s an d software on th e m arket. OEM s. Man y OEMs (Origin al Eq u ip m en t Man u factu rers) h ave d evelop ed th eir own com p atible ROMs in d ep en d en tly. Com p an ies su ch as Com p aq an d AT&T h ave d evelop ed th eir own BIOS p rod u cts th at are com p arable to th ose offered by AMI, Ph oen ix, an d oth ers. Th ese com p an ies also offer u p grad es to n ewer version s th at often can offer m ore featu res an d im p rovem en ts or fix p roblem s with th e old er version s. If you u se a system with a p rop rietary ROM, m ake su re th at it is from a larger com p an y with a track record an d on e th at will p rovid e u p d ates an d fixes as n ecessary. Id eally, u p grad es sh ou ld be available for d own load from th e In tern et. Oth er OEMs h ave th eir BIOS written for th em by a th ird -p arty com p an y. For exam p le, Hewlett Packard system s h ave a cu stom p rop rietary d esign , an d , as su ch , n eed a u n iq u e BIOS. Rath er th an write th eir own , th ey con tract with Ph oen ix, a well-kn own BIOS su p p lier, to d evelop th e m oth erboard BIOSs u sed in all th e HP Vectra PCs. Note th at even th ou gh Ph oen ix m ay h ave d on e th e d evelop m en t, you still h ave to get an y u p grad es or fixes from Hewlett Packard .

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Several com p an ies h ave sp ecialized in th e d evelop m en t of a com p atible ROM BIOS p rod u ct. Th e th ree m ajor com p an ies th at com e to m in d in d iscu ssin g ROM BIOS software are Am erican Megatren d s, In c. (AMI), Award Software, an d Ph oen ix Software. Each com p an y licen ses its ROM BIOS to a m oth erboard m an u factu rer so th at th e m an u factu rer can worry abou t th e h ard ware rath er th an th e software. To obtain on e of th ese ROMs for a m oth erboard , th e OEM m u st an swer m an y q u estion s abou t th e d esign of th e system so th at th e p rop er BIOS can be eith er d evelop ed or selected from th ose alread y d esign ed . Com bin in g a ROM BIOS an d a m oth erboard is n ot a h ap h azard task. No sin gle, gen eric, com p atible ROM exists, eith er. AMI, Award , Microid Research , an d Ph oen ix sh ip m an y variation s of th eir BIOS cod e to d ifferen t board m an u factu rers, each on e cu stom tailored to th at sp ecific m oth erboard . Recen tly, th ere h ave been som e big ch an ges in th e BIOS in d u stry. Ph oen ix lan d ed a con tract with In tel, an d n ow p rovid es all of In tel’s m oth erboard BIOSes, rep lacin g AMI wh o p reviou sly h ad th e con tract. Th is is a big d eal becau se In tel sells abou t 80% or m ore of all PC m oth erboard s. W h at th at basically m ean s is th at if you p u rch ase a PC tod ay, you will p robably be gettin g an In tel-m ad e m oth erboard with th e n ew Ph oen ix BIOS. An oth er d evelop m en t is th at in m id -’98, Ph oen ix bou gh t Award , an d all of th eir n ew p rod u cts will be u n d er th e Ph oen ix n am e. Th u s th e big-3 BIOS d evelop ers are n ow red u ced to th e big-2—Ph oen ix an d AMI. Most of th e offsh ore m oth erboard m an u factu rers still con tin u e to u se th e AMI BIOS. However, Ph oen ix is cu rren tly th e lead in g BIOS com p an y. Th ey are n ot on ly d evelop in g th e BIOS for m ost n ewer system s on th e m arket, bu t th ey also are th e p rim ary BIOS d evelop er resp on sible for n ew BIOS d evelop m en t an d n ew BIOS stan d ard s. AMI. Alth ou gh AMI cu stom izes th e ROM cod e for a p articu lar system , it d oes n ot sell th e ROM sou rce cod e to th e OEM. An OEM m u st obtain each n ew release as it becom es available. Becau se m an y OEMs d on ’t n eed or wan t every n ew version d evelop ed , th ey m igh t skip several version ch an ges before licen sin g a n ew on e. Th e AMI BIOS is cu rren tly th e m ost p op u lar BIOS in PC system s. Newer version s of th e AMI BIOS are called Hi-Flex d u e to th e h igh flexibility fou n d in th e BIOS con figu ration p rogram . Th e AMI Hi-Flex BIOS is u sed in In tel, AMI, an d m an y oth er m an u factu rers’ m oth erboard s. On e sp ecial AMI featu re is th at it is th e on ly th ird -p arty BIOS m an u factu rer to m ake its own m oth erboard . Du rin g p oweru p , th e BIOS ID strin g is d isp layed on th e lower left of th e screen . Th is strin g tells you valu able in form ation abou t wh ich BIOS version you h ave, an d certain settin gs th at are d eterm in ed by th e bu ilt-in setu p p rogram .

Tip A good trick to help you view the BIOS ID string is to shut down and either unplug your keyboard, or hold down a key as you power back on. This will cause a keyboard error, and the string will remained displayed.

M otherboard Components

Th e p rim ary BIOS Id en tification strin g (ID Strin g 1) is d isp layed by an y AMI BIOS d u rin g th e POST (Power-On Self Test) at th e bottom -left corn er of th e screen , below th e cop yrigh t m essage. Two ad d ition al BIOS ID strin gs (ID Strin g 2 an d 3) can be d isp layed by th e AMI Hi-Flex BIOS by p ressin g th e In sert key d u rin g POST. Th ese ad d ition al ID strin gs d isp lay th e op tion s th at are in stalled in th e BIOS. Th e gen eral BIOS ID Strin g 1 form at for old er AMI BIOS version s is sh own in Table 4.9. Table 4.9

ABBB-NNNN-m m ddyy-KK

Posit ion

Descript ion

A

BIOS Options: D = Diagnostics built-in. S = Setup built-in. E = Extended Setup built-in.

BBB

Chipset or M otherboard Identifier: C& T = Chips & Technologies chipset. NET = C& T NEAT 286 chipset. 286 = Standard 286 motherboard. SUN = Suntac chipset. PAQ = Compaq motherboard. INT = Intel motherboard. AM I = AM I motherboard. G23 = G2 chipset 386 motherboard.

NNNN

The manufacturer license code reference number.

mmddyy

The BIOS release date, mm/ dd/ yy.

KK

The AM I keyboard BIOS version number.

Th e BIOS ID Strin g 1 form at for AMI Hi-Flex BIOS version s is sh own in Table 4.10. Table 4.10

AB-CCcc-DDDDDD-EFGHIJKL-m m ddyy-M M M M M M M M -N

Posit ion

Descript ion

A

Processor Type: 0 = 8086 or 8088. 2 = 286. 3 = 386. 4 = 486. 5 = Pentium. 6 = Pentium Pro/ II.

B

Size of BIOS: 0 = 64K BIOS. 1 = 128K BIOS. (continues)

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Table 4.10 Cont inued

AB-CCcc-DDDDDD-EFGHIJKL-m m ddyy-M M M M M M M M -N

Posit ion

Descript ion

CCcc

M ajor and M inor BIOS version number.

DDDDDD

M anufacturer license code reference number. 0036xx = AM I 386 motherboard, xx = Series #. 0046xx = AM I 486 motherboard, xx = Series #. 0056xx = AM I Pentium motherboard, xx = Series #. 0066xx = AM I Pentium Pro motherboard, xx = Series #.

E

1 = Halt on Post Error.

F

1 = Initialize CM OS every boot.

G

1 = Block pins 22 and 23 of the keyboard controller.

H

1 = M ouse support in BIOS/ keyboard controller.

I

1 = Wait for key on POST errors.

J

1 = Display floppy error during POST.

K

1 = Display video error during POST.

L

1 = Display keyboard error during POST.

mmddyy

BIOS Date, mm/ dd/ yy.

MMMMMMMM

Chipset identifier or BIOS name.

N

Keyboard controller version number.

AMI Hi-Flex BIOS ID Strin g 2 is sh own in Table 4.11. Table 4.11

AAB-C-DDDD-EE-FF-GGGG-HH-II-JJJ

Posit ion

Descript ion

AA

Keyboard controller pin number for clock switching.

B

Keyboard controller clock switching pin function: H = High signal switches clock to high speed. L = High signal switches clock to low speed.

C

Clock switching through chipset registers: 0 = Disable. 1 = Enable.

DDDD

Port address to switch clock high.

EE

Data value to switch clock high.

FF

M ask value to switch clock high.

GGGG

Port Address to switch clock low.

HH

Data value to switch clock low.

II

M ask value to switch clock low.

JJJ

Pin number for Turbo Switch Input.

AMI Hi-Flex BIOS ID Strin g 3 is sh own in Table 4.12.

M otherboard Components

Table 4.12

AAB-C-DDD-EE-FF-GGGG-HH-II-JJ-K-L

Posit ion

Descript ion

AA

Keyboard controller pin number for cache control.

B

Keyboard controller cache control pin function: H = High signal enables the cache. L = High signal disables the cache.

C

1 = High signal is used on the keyboard controller pin.

DDD

Cache control through chipset registers: 0 = Cache control off. 1 = Cache control on.

EE

Port address to enable cache.

FF

Data value to enable cache.

GGGG

M ask value to enable cache.

HH

Port address to disable cache.

II

Data value to disable cache.

JJ

M ask value to disable cache.

K

Pin number for resetting the 82335 memory controller.

L

BIOS M odification Flag: 0 = The BIOS has not been modified. 1–9, A–Z = Number of times the BIOS has been modified.

Th e AMI BIOS h as m an y featu res, in clu d in g a bu ilt-in setu p p rogram activated by p ressin g th e Delete or Esc key in th e first few secon d s of bootin g u p you r com p u ter. Th e BIOS will p rom p t you briefly as to wh ich key to p ress an d wh en to p ress it. Th e AMI BIOS offers u ser-d efin able h ard d isk typ es, essen tial for op tim al u se of m an y IDE or ESDI d rives. Th e 1995 an d n ewer BIOS version s also su p p ort En h an ced IDE d rives an d will au to-con figu re th e d rive p aram eters. A u n iq u e featu re of som e of th e AMI BIOS version s was, in ad d ition to th e setu p , th ey h ad a bu ilt-in , m en u -d riven d iagn ostics p ackage, essen tially a very lim ited version of th e stan d alon e AMIDIAG p rod u ct. Th e in tern al d iagn ostics are n ot a rep lacem en t for m ore com p reh en sive d isk-based p rogram s, bu t th ey can h elp in a p in ch . Th e m en u -d riven d iagn ostics d o n ot d o exten sive m em ory testin g, for exam p le, an d th e h ard d isk lowlevel form atter works on ly at th e BIOS level rath er th an at th e con troller register level. Th ese lim itation s often h ave p reven ted it from bein g cap able of form attin g severely d am aged d isks. Most n ewer AMI BIOS version s n o lon ger in clu d e th e fu ll d iagn ostics. AMI d oesn ’t p rod u ce BIOS d ocu m en tation ; th ey leave th at u p to th e m oth erboard m an u factu rers wh o in clu d e th eir BIOS on th e m oth erboard . However, AMI h as p u blish ed a d etailed version of th eir d ocu m en tation called th e Program m er’s Guide to the AMIBIOS, p u blish ed by W in d crest/ McGraw-Hill an d available u n d er th e ISBN 0-07-001561-9. Th is is a book written by AMI en gin eers th at d escribes all th e BIOS fu n ction s, featu res, error cod es, an d m ore. I wou ld recom m en d th is book to an ybod y with an AMI BIOS in th eir

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system , as th is p rovid es a com p lete version of th e d ocu m en tation for wh ich th ey m ay h ave been lookin g. Th e AMI BIOS is sold th rou gh d istribu tors, a list of wh ich is available at h t t p :/ / w w w .a m i .c o m / d i st ri b u t o r.h t m l. However, keep in m in d th at you can n ot bu y u p grad es an d rep lacem en ts d irectly from AMI. Aw a rd . Award is u n iq u e am on g BIOS m an u factu rers becau se it sells its BIOS cod e to th e OEM an d allows th e OEM to cu stom ize th e BIOS. Of cou rse, th en th e BIOS n o lon ger is Award BIOS, bu t rath er a h igh ly cu stom ized version . AST u ses th is ap p roach on its system s, as d o oth er m an u factu rers, for total con trol over th e BIOS cod e with ou t h avin g to write it from scratch . Alth ou gh AMI an d Ph oen ix cu stom ize th e ROM cod e for a p articu lar system , th ey d o n ot sell th e ROM’s sou rce cod e to th e OEM. Som e OEMs th at seem to h ave d evelop ed th eir own ROM cod e started with a base of sou rce cod e licen sed to th em by Award or som e oth er com p an y. Th e Award BIOS h as all th e n orm al featu res you exp ect, in clu d in g a bu ilt-in setu p p rogram activated by p ressin g Ctrl+Alt+Esc or a p articu lar key on startu p (n orm ally p rom p ted on th e screen ). Th is setu p offers u ser-d efin able d rive typ es, req u ired in ord er to fu lly u se IDE or ESDI h ard d isks. Th e POST is good , an d Award ru n s tech n ical su p p ort on its W eb site at h t t p :/ / w w w .a w a rd .c o m . Award was p u rch ased by Ph oen ix in m id -1998 an d n o lon ger p rod u ces a BIOS u n d er th e Award n am e. However, th ey will con tin u e to su p p ort th eir p ast BIOS version s an d d evelop u p d ates if n ecessary. P h o e n i x . Th e Ph oen ix BIOS for m an y years h as been a stan d ard of com p atibility by wh ich oth ers are ju d ged . It was on e of th e first th ird -p arty com p an ies to legally reverseen gin eer th e IBM BIOS u sin g a “clean room ” ap p roach . In th is ap p roach , a grou p of en gin eers stu d ied th e IBM BIOS an d wrote a sp ecification for h ow th at BIOS sh ou ld work an d wh at featu res sh ou ld be in corp orated . Th is in form ation th en was p assed to a secon d grou p of en gin eers wh o h ad n ever seen th e IBM BIOS. Th ey cou ld th en legally write a n ew BIOS to th e sp ecification s set forth by th e first grou p . Th is work wou ld th en be u n iq u e an d n ot a cop y of IBM’s BIOS; h owever, it wou ld fu n ction th e sam e way. Th e Ph oen ix BIOS excels in two areas th at p u t it h igh on m y list of recom m en d ation s. On e is th at th e POST is excellen t. Th e BIOS ou tp u ts an exten sive set of beep cod es th at can be u sed to d iagn ose severe m oth erboard p roblem s th at wou ld p reven t n orm al op eration of th e system . In fact, th is POST can isolate m em ory failu res in Ban k 0 righ t d own to th e in d ivid u al SIMM or DIMM m od u le with beep cod es alon e. Th e Ph oen ix BIOS also h as an excellen t setu p p rogram free from u n n ecessary frills, bu t th at offers all th e featu res on e wou ld exp ect, su ch as u ser-d efin able d rive typ es, an d so on . Th e bu ilt-in setu p is activated by p ressin g eith er Ctrl+Alt+S, Ctrl+Alt+Esc, or a p articu lar key on startu p su ch as F2, d ep en d in g on th e version of BIOS you h ave.

M otherboard Components

Th e secon d area in wh ich Ph oen ix excels is th e d ocu m en tation . Not on ly are th e m an u als th at you get with th e system d etailed , bu t also Ph oen ix h as written a set of BIOS tech n ical-referen ce m an u als th at are a stan d ard in th e in d u stry. Th e set con sists of th ree books, titled System BIOS for IBM PC/X T/AT Com puters and Com patibles, CBIOS for IBM PS/2 Com puters and Com patibles, an d ABIOS for IBM PS/2 Com puters and Com patibles. In ad d ition to bein g an excellen t referen ce for th e Ph oen ix BIOS, th ese books serve as an ou tstan d in g overall referen ce to th e BIOS in gen eral. Ph oen ix h as exten sive tech n ical su p p ort an d d ocu m en tation on th eir W eb site at h t t p :/ / w w w .p h o e n i x .c o m , as d oes th eir largest n ation wid e d istribu tor, Micro Firm ware, In c. at h t t p :/ / w w w .f i rm w a re .c o m , or ch eck th e p h on e n u m bers listed in th e ven d or list in Ap p en d ix A. Micro Firm ware offers u p grad es to m an y old er system s with a Ph oen ix BIOS, in clu d in g m an y Packard Bell, Gateway 2000 (with Micron ics m oth erboard s), Micron Tech n ologies, an d oth er system s. Th ese com p an ies’ p rod u cts are establish ed as ROM BIOS stan d ard s in th e in d u stry, an d freq u en t u p d ates an d im p rovem en ts en su re th at a system con tain in g th ese ROMs will h ave a lon g life of u p grad es an d service. Upgrading t he ROM BIOS In th is section , you learn th at ROM BIOS u p grad es can im p rove a system in m an y ways. You also learn th at th e u p grad es can be d ifficu lt an d m ay req u ire m u ch m ore th an p lu ggin g in a gen eric set of ROM ch ip s. Th e ROM BIOS, or read -on ly m em ory basic in p u t/ ou tp u t system , p rovid es th e cru d e brain s th at get you r com p u ter’s com p on en ts workin g togeth er. A sim p le BIOS u p grad e can often give you r com p u ter better p erform an ce an d m ore featu res. Th e BIOS is th e reason wh y d ifferen t op eratin g system s can op erate on virtu ally an y PCcom p atible system d esp ite h ard ware d ifferen ces. Becau se th e BIOS com m u n icates with th e h ard ware, th e BIOS m u st be sp ecific to th e h ard ware an d m atch it com p letely. In stead of creatin g th eir own BIOSs, m an y com p u ter m akers bu y a BIOS from sp ecialists su ch as Am erican Megatren d s, In c. (AMI), Award Software (n ow p art of Ph oen ix), Microid Research , or Ph oen ix Tech n ologies Ltd . A m oth erboard m an u factu rer th at wan ts to licen se a BIOS m u st u n d ergo a len gth y p rocess of workin g with th e BIOS com p an y to tailor th e BIOS cod e to th e h ard ware. Th is p rocess is wh at m akes u p grad in g a BIOS som ewh at p roblem atic; th e BIOS u su ally resid es on ROM ch ip s on th e m oth erboard an d is sp ecific to th at m oth erboard m od el or revision . In oth er word s, you m u st get you r BIOS u p grad es from you r m oth erboard m an u factu rer. ◊◊ See “ ROM ,” p. 304

In old er system s, you often m u st u p grad e th e BIOS to take ad van tage of som e oth er u p grad e. To in stall som e of th e larger an d faster IDE (In tegrated Drive Electron ics) h ard d rives an d LS-120 (120 m egabyte) flop p y d rives in old er m ach in es, for exam p le, you m ay

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n eed a BIOS u p grad e. Som e m ach in es are still bein g sold with old er BIOSs th at d o n ot su p p ort h ard d rives larger th an 8GB, for exam p le. Th e followin g list sh ows th e p rim ary fu n ction s of a ROM BIOS u p grad e: ■ Ad d in g LS-120 (120M) flop p y d rive su p p ort ■ Ad d in g su p p ort for h ard d rives greater th an 8G ■ Ad d in g su p p ort for Ultra-DMA/ 33 IDE h ard d rives ■ Ad d in g su p p ort for bootable ATAPI CD-ROM d rives ■ Ad d in g or im p rovin g Plu g-an d -Play su p p ort an d com p atibility ■ Correctin g year-2000 an d leap -year bu gs ■ Correctin g kn own bu gs or com p atibility p roblem s with certain h ard ware an d software ■ Up grad in g th e CPU For m ost BIOS u p grad es, you m u st con tact th e m oth erboard m an u factu rer by p h on e or d own load th e u p grad e from th eir W eb site. You will n eed to kn ow th e followin g in form ation : ■ Th e m ake an d m od el of th e m oth erboard or system u n it ■ Th e typ e of CPU (for exam p le, Pen tiu m MMX, AMD K6, Cyrix/ IBM 6x86MX, MII, Pen tiu m II, an d so on ) ■ Th e version of th e existin g BIOS You can n orm ally id en tify th e BIOS you h ave by watch in g th e screen wh en th e system is first p owered u p . It h elp s to tu rn th e m on itor on first as som e take a few secon d s to warm u p an d often th e BIOS in form ation is d isp layed for on ly a few secon d s. You can also often fin d th e BIOS ID in form ation in th e CMOS Setu p . After you h ave th is in form ation , you sh ou ld be able to con tact th e m oth erboard m an u factu rer to see if th ere is a n ew BIOS for you r system . If you go to th eir W eb site, ch eck to see wh eth er th ere is a version n ewer th an th e on e you h ave. If so, you can d own load it an d in stall it in you r system . Keyboard-Cont roller Chips. Besid es th e m ain system ROM, AT-class (286 an d h igh er) com p u ters also h ave a keyboard con troller or keyboard ROM, wh ich is a keyboard con troller m icrop rocessor with its own bu ilt-in ROM. Th is is often fou n d in th e Sou th Brid ge of th e ch ip set or even th e Su p er I/ O ch ip on som e board s. Th e keyboard con troller u su ally is an In tel 8042 m icrocon troller, wh ich in corp orates a m icrop rocessor, RAM, ROM, an d I/ O p orts. Th e keyboard con troller was origin ally a 40-p in ch ip th at often h ad a cop yrigh t n otice id en tifyin g th e BIOS cod e p rogram m ed in to th e ch ip . Mod ern board s h ave th is fu n ction in tegrated in to th e ch ip set.

M otherboard Components

Th e keyboard con troller con trols th e reset an d A20 lin es an d also d ecip h ers th e keyboard scan cod es. Th e A20 lin e is u sed in exten d ed m em ory an d oth er p rotected -m od e op eration s. In m an y system s, on e of th e u n u sed p orts is u sed to select th e CPU clock sp eed . Becau se of th e tie-in with th e keyboard con troller an d p rotected -m od e op eration , m an y p roblem s with keyboard con trollers becam e evid en t wh en u p grad in g from DOS to eith er W in d ows or OS/ 2 on th ese old er system s. If you exp erien ce locku p s or keyboard p roblem s with eith er W in d ows or OS/ 2 software—or with an y software th at ru n s in p rotected m od e, su ch as Lotu s 1-2-3 Release 3.x—get a rep lacem en t from you r BIOS ven d or or system -board ven d or. Problem s with th e keyboard con troller were solved in m ost system s in th e early 1990s, so you sh ou ld n ’t h ave to d eal with th is issu e in system s n ewer th an th at. W ith old er system s, wh en you u p grad ed th e BIOS in th e system , th e BIOS ven d or often in clu d ed a n ew keyboard con troller. Usi n g a Fl a sh BIOS. Virtu ally all PCs bu ilt sin ce 1996 in clu d e a Flash ROM to store th e BIOS. A Flash ROM is a typ e of EEPROM (Electrically Erasable Program m able Read -On ly Mem ory) ch ip th at you can erase an d rep rogram d irectly in th e system with ou t sp ecial eq u ip m en t. Old er EPROMs req u ired a sp ecial u ltraviolet ligh t sou rce an d an EPROM p rogram m er d evice to erase an d rep rogram th em , wh ile Flash ROMs can be erased an d rewritten with ou t even rem ovin g th em from th e system . Usin g Flash ROM en ables a u ser to d own load ROM u p grad es from a W eb site or receive th em on d isk; you th en can load th e u p grad e in to th e Flash ROM ch ip on th e m oth erboard with ou t rem ovin g an d rep lacin g th e ch ip . Norm ally, th ese u p grad es are d own load ed from th e m an u factu rer’s W eb site, an d th en an in clu d ed u tility is u sed to create a bootable flop p y with th e n ew BIOS im age an d th e u p d ate p rogram . It is im p ortan t to ru n th is p roced u re from a boot flop p y so th ere is n o oth er software or d rivers in th e way th at m igh t in terfere with th e u p d ate. Th is m eth od saves tim e an d m on ey for both th e system m an u factu rer an d th e en d u ser. Som etim es th e Flash ROM in a system is write-p rotected , an d you m u st d isable th e p rotection before p erform in g an u p d ate, u su ally by m ean s of a ju m p er or switch th at con trols th e lock on th e ROM u p d ate. W ith ou t th e lock, an y p rogram th at kn ows th e righ t in stru ction s can rewrite th e ROM in you r system —n ot a com fortin g th ou gh t. W ith ou t th e write p rotection , it is con ceivable th at viru s p rogram s cou ld be written th at cop y th em selves d irectly in to th e ROM BIOS cod e in you r system . Even with ou t a p h ysical write-p rotect lock, m od ern Flash ROM BIOSs h ave a secu rity algorith m th at h elp s to p reven t u n au th orized u p d ates. Th is is th e tech n iq u e th at In tel u ses on th eir m oth erboard s. Note th at m oth erboard m an u factu rers will n ot n otify you wh en th ey u p grad e th e BIOS for a p articu lar board . You m u st p eriod ically log in to th eir W eb site to ch eck for u p d ates. Norm ally, an y Flash u p d ates are free. Before p roceed in g with a BIOS u p grad e, you m u st first locate an d d own load th e u p d ated BIOS from you r m oth erboard m an u factu rer. Con su lt Ap p en d ix A, “Ven d or List,” to fin d

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th e W eb site ad d ress or oth er con tact in form ation for you r m oth erboard m an u factu rer. Log in to th eir W eb site an d follow th e m en u s to th e BIOS u p d ates p age, an d th en select an d d own load th e n ew BIOS for you r m oth erboard . Th e BIOS u p grad e u tility is con tain ed in a self-extractin g arch ive file th at can be in itially d own load ed to you r h ard d rive, bu t it m u st be extracted an d cop ied to a flop p y before th e u p grad e can p roceed . Differen t m oth erboard m an u factu rers h ave sligh tly d ifferen t p roced u res an d p rogram s to accom p lish a Flash ROM u p grad e, so it is best if you read th e d irection s n orm ally in clu d ed with th e u p d ate. I will in clu d e in stru ction s h ere for In tel m oth erboard s becau se th ey are by far th e m ost com m on . Th e In tel BIOS u p grad e u tility will fit on a flop p y d isk an d p rovid es th e cap ability to save, verify, an d u p d ate th e system BIOS. Th e u p grad e u tility also p rovid es th e cap ability to in stall altern ate lan gu ages for BIOS m essages an d th e SETUP u tility. Th e first step in th e u p grad e after d own load in g th e n ew BIOS file is to en ter CMOS setu p an d write d own you r existin g CMOS settin gs becau se th ey will be erased d u rin g th e u p grad e. Th en you will create a DOS boot flop p y, an d u n com p ress or extract th e BIOS u p grad e files to th e flop p y from th e file you d own load ed . Th en you reboot on th e n ewly created u p grad e d isk an d follow th e m en u s for th e actu al reflash p roced u re. Here is a step -by-step p roced u re for th e p rocess: 1. Save you r CMOS RAM setu p con figu ration . You can d o so by p ressin g th e ap p rop riate key d u rin g boot (F1 with an AMI BIOS, F2 with a Ph oen ix BIOS) an d write d own all you r cu rren t CMOS settin gs. You will n eed to reset th ese settin gs after you h ave u p grad ed to th e latest BIOS. W rite d own all settin gs th at are u n iq u e to th e system . Th ese settin gs will be n eed ed later to recon figu re th e system . Pay sp ecial atten tion to an y h ard d rive settin gs: Th ese are very im p ortan t. If you fail to restore th ese p rop erly, you m ay n ot be able to boot from th e d rive or access th e d ata on it. 2. Exit th e BIOS Setu p an d restart th e system . Allow th e system to fu lly start W in d ows an d brin g u p a DOS p rom p t win d ow or boot d irectly to a DOS p rom p t via th e W in d ows Start m en u (for exam p le, p ress F8 wh en you see “Startin g W in d ows,” an d select Com m an d Prom p t). 3. Place a flop p y d isk in th e A: flop p y d rive an d form at th e flop p y u sin g th e / S op tion on th e FORMAT com m an d as follows: C:\>FORMAT A: /S

4. Altern atively, if you h ave an oth erwise blan k p reform atted flop p y in th e flop p y d rive u se th e SYS com m an d to m ake it bootable as follows: C:\>SYS A:

5. Th e file you origin ally d own load ed from th e In tel W eb site will be a self-extractin g com p ressed arch ive th at in clu d es oth er files th at n eed to be extracted . Pu t th e file in a tem p orary d irectory, th en from with in th is d irectory, d ou ble-click th e BIOS file you d own load ed or typ e th e file n am e of th e file an d p ress En ter. Th is will cau se

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th e file to self-extract. For exam p le, if th e file you d own load ed was called SEBIOS04.EXE (for th e In tel SE440BX m oth erboard ), you wou ld en ter th e followin g com m an d : C:\TEMP>SEBIOS04

6. Th e extracted files resu ltin g from th is sh ou ld con tain a file n am ed BIOS.EXE an d a software licen se text file. You th en d o an oth er extract on th e BIOS.EXE file to th e bootable flop p y you created u sin g th e followin g com m an d : C:\TEMP>BIOS A:

7. Now you can restart th e system with th e bootable flop p y in d rive A: con tain in g th e n ew BIOS files you ju st extracted . Up on bootin g from th is d isk, th e IFLASH p rogram will au tom atically start; p ress En ter wh en p rom p ted . 8. High ligh t Save flash memory area to a file an d p ress En ter. Follow th e p rom p ts to en ter a filen am e. Th is will create a backu p of you r existin g BIOS. Th is will be valu able sh ou ld th e n ew BIOS cau se u n exp ected p roblem s. 9. High ligh t Update Flash Memory From a File an d p ress En ter. Follow th e p rom p ts to select th e n am e of th e BIOS im age file you will u se to u p d ate th e Flash ROM. Press th e Tab key to h igh ligh t th e filen am e an d p ress En ter. 10. Th e system will n ow give a warn in g statin g th at con tin u in g will d estroy th e cu rren t con ten ts of th e flash m em ory area. Press En ter to con tin u e—th e u p d ate sh ou ld take abou t th ree m in u tes. Do n ot in terru p t th is p roced u re or th e Flash BIOS will be corru p ted . 11. W h en you ’re told th at th e BIOS h as been su ccessfu lly load ed , rem ove th e bootable flop p y from th e d rive an d p ress En ter to reboot th e system . 12. Press F1 or F2 to en ter Setu p . On th e first screen with in SETUP, ch eck th e BIOS version to en su re th at it is th e n ew version . 13. In Setu p , load th e d efau lt valu es. If you h ave an AMI BIOS, p ress th e F5 key; with a Ph oen ix BIOS go to th e Exit su bm en u an d h igh ligh t Load Setup Defaults an d p ress En ter. If you d o n ot set th e valu es back to d efau lt, th e system m ay fu n ction erratically. 14. If th e system h ad u n iq u e settin gs, re-en ter th ose settin gs n ow. Press F10 to save th e valu es, exit Setu p , an d restart th e system . You r system sh ou ld n ow be fu lly fu n ction al with th e n ew BIOS.

Not e If you encounter a CM OS checksum error or other problems after rebooting, try rebooting the system again. CM OS checksum errors require that you enter Setup, check and save your settings, and exit Setup a second time.

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Fl a sh BIOS Re c o v e ry . W h en you p erform ed th e Flash rep rogram m in g, you sh ou ld h ave seen a warn in g m essage on th e screen sim ilar to th e followin g: “Th e BIOS is cu rren tly bein g u p d ated . DO NOT REBOOT OR POW ER DOW N u n til th e u p d ate is com p leted (typ ically with in th ree m in u tes)…” If you fail to h eed th is warn in g or som eth in g in terru p ts th e u p d ate p roced u re, you will be left with a system th at h as a corru p ted BIOS. Th is m ean s you will n ot be able to restart th e system an d red o th e p roced u re, at least n ot easily. Dep en d in g on th e m oth er-board , you m ay h ave to rep lace th e Flash ROM ch ip with on e th at was p rep rogram m ed by th e m oth erboard m an u factu rer becau se you r board will be n on fu n ction al u n til a n on corru p ted ROM is p resen t. Th is is wh y I still keep m y tru sty ROM bu rn er arou n d ; it is very u sefu l for th ose m oth erboard s with socketed Flash ROM ch ip s. In m in u tes, I can u se th e ROM bu rn er to rep rogram th e ch ip an d rein stall it in th e board . If you n eed a ROM p rogram m er, I recom m en d eith er An d rom ed a Research or Bytek (see Ap p en d ix A, “Ven d or List”). In m ost system s tod ay, th e Flash ROM is sold ered in to th e m oth erboard so it can n ot be rep laced , ren d erin g th e rep rogram m in g id ea m oot. However, th is d oesn ’t m ean th at th e on ly way ou t is a com p lete m oth erboard rep lacem en t: Most m oth erboard s with sold ered in Flash ROMs h ave a sp ecial BIOS Recovery p roced u re th at can be p erform ed . Th is h in ges on a sp ecial u n erasable p art of th e Flash ROM th at is reserved for th is p u rp ose. In th e u n likely even t th at a Flash u p grad e is in terru p ted catastrop h ically, th e BIOS m ay be left in an u n u sable state. Recoverin g from th is con d ition req u ires th e followin g step s. A m in im u m of a p ower su p p ly, sp eaker, an d a flop p y d rive con figu red as d rive A: sh ou ld be attach ed to th e m oth erboard for th is p roced u re to work. 1. Ch an ge th e Flash Recovery ju m p er to th e recovery m od e p osition . Virtu ally all In tel m oth erboard s an d m an y th ird -p arty m oth erboard s h ave a ju m p er or switch for BIOS recovery, wh ich is n orm ally labeled “Recover/ Norm al.” Figu re 4.9 sh ows th is ju m p er on th e In tel SE440BX, a typ ical m oth erboard .

1

3

J8A1

FIG. 4.9

Typ ical In tel m oth erboard BIOS recovery ju m p er.

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2. In stall th e bootable BIOS u p grad e d isk you p reviou sly created to d o th e Flash u p grad e in to d rive A: an d reboot th e system . Becau se of th e sm all am ou n t of cod e available in th e n on erasable Flash boot block area, n o vid eo p rom p ts are available to d irect th e p roced u re. In oth er word s, you will see n oth in g on th e screen . In fact, it is n ot even n ecessary for a vid eo card to be con n ected for th is p roced u re to work. Th e p roced u re can be m on itored by listen in g to th e sp eaker an d lookin g at th e flop p y d rive LED. W h en th e system beep s an d th e flop p y d rive LED is lit, th e system is cop yin g th e BIOS recovery cod e in to th e Flash d evice. 3. As soon as th e d rive LED goes off, th e recovery sh ou ld be com p lete. Power th e system off. 4. Ch an ge th e Flash recovery ju m p er back to th e d efau lt p osition for n orm al op eration . W h en you p ower th e system back on , th e n ew BIOS sh ou ld be in stalled an d fu n ction al. However, you m igh t wan t to leave th e BIOS u p grad e flop p y in d rive A: an d ch eck to see th at th e p rop er BIOS version was in stalled . Note th at th is BIOS recovery p roced u re is often th e fastest way to u p d ate a large n u m ber of m ach in es, esp ecially if you are p erform in g oth er u p grad es at th e sam e tim e. Th is is h ow it is n orm ally d on e in a system assem bly or p rod u ction en viron m en t. Usi n g IML Sy st e m P a rt i t i o n BIOS. IBM an d Com p aq u sed a sch em e sim ilar to a Flash ROM in som e of th eir old er Pen tiu m an d 486 system s called Initial Microcode Load (IML). IML is a tech n iq u e in wh ich th e BIOS cod e is in stalled on th e h ard d isk in a sp ecial h id d en system p artition an d is load ed every tim e th e system is p owered u p . Of cou rse, th e system still h as a core BIOS on th e m oth erboard , bu t all th at BIOS d oes is locate an d load u p d ated BIOS cod e from th e system p artition . Th is tech n iq u e en abled Com p aq an d IBM to d istribu te ROM u p d ates on d isk for in stallation in th e system p artition . Th e IML BIOS is load ed every tim e th e system is reset or p owered on . Alon g with th e system BIOS cod e, th e system p artition con tain s a com p lete cop y of th e Setu p an d Diagn ostics or Referen ce Disk, wh ich p rovid es th e op tion of ru n n in g th e setu p an d system -con figu ration software at an y tim e d u rin g a reboot op eration . Th is op tion elim in ates th e n eed to boot from th is d isk to recon figu re th e system , an d gives th e im p ression th at th e en tire Setu p an d Diagn ostics or Referen ce Disk is con tain ed in ROM. On e d rawback to th is tech n iq u e is th at th e BIOS cod e is in stalled on th e h ard d isk; th e system can n ot fu n ction p rop erly with ou t th e correctly set-u p h ard d isk con n ected . You always can boot from th e Referen ce Disk flop p y sh ou ld th e h ard d isk fail or becom e d iscon n ected , bu t you can n ot boot from a stan d ard flop p y d isk. Th is sch em e m akes h ard d rive u p d ates p roblem atic, an d cau ses all kin d s of su p p ort n igh tm ares. I recom m en d avoid in g an y system with an IML BIOS, esp ecially if you are bu yin g it u sed , as su p p ort for th ese typ es of con figu ration s is h ard to com e by an d n ot m an y p eop le kn ow h ow to d eal with th em .

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BIOS Error M essages Th e ROM m ap s of m ost PCs are sim ilar to th e origin al IBM system s with wh ich th ey are com p atible—with th e excep tion of th e Cassette BASIC p ortion (also called ROM BASIC). It m ay com e as a su rp rise to som e PC u sers, bu t th e origin al IBM PC actu ally h ad a jack on th e rear of th e system for con n ectin g a cassette tap e record er. Th is was to be u sed for load in g p rogram s an d d ata to or from a cassette tap e. Tap es were u sed at th e tim e becau se flop p y d rives were very costly, an d h ard d isks were n ot even an op tion yet. Flop p y d rives cam e d own in p rice q u ickly at th e tim e, an d th e cassette p ort n ever ap p eared on an y su bseq u en t IBM system s. Th e cassette p ort also n ever ap p eared on an y com p atible system . Th e origin al PC cam e stan d ard with on ly 16K of m em ory in th e base con figu ration . No flop p y d rives were in clu d ed , so you cou ld n ot load or save files from d isks. Most com p u ter u sers at th e tim e wou ld eith er write th eir own p rogram s in th e BASIC (Begin n er’s All-Pu rp ose Sym bolic In stru ction Cod e) lan gu age or ru n p rogram s written by oth ers. A BASIC lan gu age in terp reter was bu ilt in to th e ROM BIOS of th ese early IBMs, an d was d esign ed to access th e cassette p ort on th e back of th e system . W h at is really stran ge is th at IBM kep t th is ROM BASIC relation sh ip all th e way in to th e early ’90s! I liken th is to h u m an s h avin g an ap p en d ix. Th e ROM BASIC in th ose IBM system s is a sort of vestigial organ —a leftover th at h ad som e u se in p reh istoric an cestors, bu t th at h as n o fu n ction tod ay. You can catch a glim p se of th is ROM BASIC on old er IBM system s th at h ave it by d isablin g all th e d isk d rives in th e system . In th at case, with n oth in g to boot from , m ost IBM system s u n cerem on iou sly d u m p you in to th e stran ge (vin tage 1981) ROM BASIC screen . W h en th is occu rs, th e m essage looks like th is: The IBM Personal Computer Basic Version C1.10 Copyright IBM Corp 1981 62940 Bytes free Ok

Man y p eop le u sed to d read seein g th is becau se it u su ally m ean t th at you r h ard d isk h ad failed to be recogn ized ! Becau se n o com p atible system s ever h ad th e Cassette BASIC in terp reter in ROM, th ey h ad to com e u p with d ifferen t m essages to d isp lay for th e sam e situ ation s in wh ich an IBM system wou ld in voke th is BASIC. Com p atibles th at h ave an AMI BIOS in fact d isp lay a con fu sin g m essage as follows: NO ROM BASIC - SYSTEM HALTED

Th is m essage is a BIOS error m essage th at is d isp layed by th e AMI BIOS wh en th e sam e situ ation s occu r th at wou ld cau se an IBM system to d u m p in to Cassette BASIC, wh ich , of cou rse, is n ot p resen t in an AMI BIOS (or an y oth er com p atible BIOS, for th at m atter). Oth er BIOS version s d isp lay d ifferen t m essages. For exam p le, u n d er th e sam e circu m stan ces, a Com p aq BIOS d isp lays th e followin g: Non-System disk or disk error replace and strike any key when ready

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Th is is som ewh at con fu sin g on Com p aq ’s p art becau se th is very sam e (or sim ilar) error m essage is con tain ed in th e DOS Boot Sector, an d wou ld n orm ally be d isp layed if th e system files were m issin g or corru p ted . In th e sam e situ ation s th at you wou ld see Cassette BASIC on an IBM system , a system with an Award BIOS wou ld d isp lay th e followin g: DISK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS ENTER

Ph oen ix BIOS system s will d isp lay eith er: No boot device available strike F1 to retry boot, F2 for setup utility

or No boot sector on fixed disk strike F1 to retry boot, F2 for setup utility

Th e first or secon d Ph oen ix m essage d isp lays d ep en d in g on wh ich error actu ally occu rred . Alth ou gh th e m essage d isp layed varies from BIOS to BIOS, th e cau se is th e sam e for all of th em . Two th in gs can gen erally cau se an y of th ese m essages to be d isp layed , an d th ey both relate to sp ecific bytes in th e Master Boot Record , wh ich is th e first sector of a h ard d isk at th e p h ysical location Cylin d er 0, Head 0, Sector 1. Th e first p roblem relates to a d isk th at h as eith er n ever been p artition ed , or h as h ad th e Master Boot Sector corru p ted . Du rin g th e boot p rocess, th e BIOS ch ecks th e last two bytes in th e Master Boot Record (th e first sector of th e d rive) for a “sign atu re” valu e of 55AAh . If th e last two bytes are n ot 55AAh , an In terru p t 18h is in voked . Th is calls th e su brou tin e th at d isp lays th e m essage you received , an d th e oth ers in d icated , or on an IBM system in vokes Cassette (ROM) BASIC. Th e Master Boot Sector (in clu d in g th e sign atu re bytes) is written to th e h ard d isk by th e DOS FDISK p rogram . Im m ed iately after you low-level form at a h ard d isk, all th e sectors are in itialized with a p attern of bytes, an d th e first sector d oes not con tain th e 55AAh sign atu re. In oth er word s, th ese ROM error m essages are exactly wh at you see if you attem p t to boot from a h ard d isk th at h as been low-level form atted , bu t h as n ot yet been p artition ed . Now con sid er th e secon d situ ation th at can cau se th ese m essages. If th e sign atu re bytes are correct, th e BIOS execu tes th e Master Partition Boot Record cod e, wh ich p erform s a test of th e Boot In d icator Bytes in each of th e fou r p artition table en tries. Th ese bytes are at offset 446 (1BEh ), 462 (1CEh ), 478 (1DEh ), an d 494 (1EEh ), resp ectively. Th ey are u sed to in d icate wh ich of th e fou r p ossible p artition table en tries con tain an active (bootable) p artition . A valu e of 80h in an y of th ese byte offsets in d icates th at table con tain s th e active p artition , wh ereas all oth er valu es m u st be 00h . If m ore th an on e of th ese bytes is 80h (in d icatin g m u ltip le active p artition s), or an y of th e byte valu es is an yth in g oth er th an 80h or 00h , you see th e followin g error m essage: Invalid partition table

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If all th ese fou r Boot In d icator Bytes are 00h , in d icatin g n o active (bootable) p artition s, th en you also see Cassette BASIC on an IBM system or th e oth er m essages in d icated earlier d ep en d in g on wh ich BIOS you h ave. Th is is exactly wh at occu rs if you were to rem ove th e existin g p artition s from a d rive u sin g FDISK, bu t h ad n ot created n ew p artition s on th e d rive, or h ad failed to m ake on e of th e p artition s Active (bootable) with FDISK before rebootin g you r system . Un fortu n ately, th ere is n o easy way to clear ou t th e p artition table on a system wh ere it is d am aged . You can try to u se FDISK to rem ove d am aged p artition s, bu t FDISK will n ot always allow it. In th at case, you h ave to resort to som eth in g m ore p owerfu l su ch as th e DISKEDIT com m an d fou n d in th e Norton Utilities p ackage by Sym an tec. M ot herboard CM OS RAM Addresses In th e origin al AT system , a Motorola 146818 ch ip was u sed as th e RTC (Real Tim e Clock) an d CMOS (Com p lem en tary Metal-Oxid e Sem icon d u ctor) RAM ch ip . Th is is a sp ecial ch ip th at h ad a sim p le d igital clock th at u sed 10 bytes of RAM, an d an ad d ition al 54 m ore bytes of leftover RAM in wh ich you cou ld store an yth in g you wan ted . Th e d esign ers of th e IBM AT u sed th ese extra 54 bytes to store th e system con figu ration . Mod ern PC system s d on ’t u se th e Motorola ch ip ; in stead , th ey in corp orate th e fu n ction s of th is ch ip in to th e m oth erboard ch ip set (Sou th Brid ge), Su p er I/ O ch ip , or th ey u se a sp ecial battery an d NVRAM (Non -Volatile RAM) m od u le from com p an ies su ch as Dallas or Ben ch m arq . Table 4.13 sh ows th e stan d ard form at of th e in form ation stored in th e 64-byte stan d ard CMOS RAM m od u le. Th is in form ation con trols th e con figu ration of th e system an d is read an d written by th e system Setu p p rogram . Table 4.13

AT CM OS RAM Addresses

Offset Hex

Offset Dec

Field Size

Funct ion

00h

0

1 byte

Current second in binary coded decimal (BCD)

01h

1

1 byte

Alarm second in BCD

02h

2

1 byte

Current minute in BCD

03h

3

1 byte

Alarm minute in BCD

04h

4

1 byte

Current hour in BCD

05h

5

1 byte

Alarm hour in BCD

06h

6

1 byte

Current day of week in BCD

07h

7

1 byte

Current day in BCD

08h

8

1 byte

Current month in BCD

09h

9

1 byte

Current year in BCD

0Ah

10

1 byte

Status register A Bit 7 = Update in progress 0 = Date and time can be read 1 = Time update in progress

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Offset Hex

Offset Dec

Field Size

Funct ion Bits 6–4 = Time frequency divider 010 = 32.768KHz Bits 3–0 = Rate selection frequency 0110 = 1.024KHz square wave frequency

0Bh

11

1 byte

Status register B Bit 7 = Clock update cycle 0 = Update normally 1 = Abort update in progress Bit 6 = Periodic interrupt 0 = Disable interrupt (default) 1 = Enable interrupt Bit 5 = Alarm interrupt 0 = Disable interrupt (default) 0 = Disable interrupt (default) 1 = Enable interrupt Bit 4 = Update-ended interrupt 0 = Disable interrupt (default) 1 = Enable interrupt Bit 3 = Status register A square wave frequency 0 = Disable square wave (default) 1 = Enable square wave Bit 2 = Date format 0 = Calendar in BCD format (default) 1 = Calendar in binary format Bit 1 = 24-hour clock 0 = 24-hour mode (default) 1 = 12-hour mode Bit 0 = Daylight Savings Time 0 = Disable Daylight Savings (default) 1 = Enable Daylight Savings

0Ch

12

1 byte

Status register C Bit 7 = IRQF flag Bit 6 = PF flag Bit 5 = AF flag Bit 4 = UF flag Bits 3-0 = Reserved

0Dh

13

1 byte

Status register D Bit 7 = Valid CM OS RAM bit 0 = CM OS battery dead 1 = CM OS battery power good Bits 6–0 = Reserved

0Eh

14

1 byte

Diagnostic status Bit 7 = Real-time clock power status 0 = CM OS has not lost power 1 = CM OS has lost power Bit 6 = CM OS checksum status 0 = Checksum is good 1 = Checksum is bad Bit 5 = POST configuration information status 0 = Configuration information is valid 1 = Configuration information is invalid (continues)

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Table 4.13 Offset Hex

AT CM OS RAM Addresses Cont inued

Offset Dec

Field Size

Funct ion Bit 4 = M emory size compare during POST 0 = POST memory equals configuration 1 = POST memory not equal to configuration Bit 3 = Fixed disk/ adapter initialization 0 = Initialization good 1 = Initialization failed Bit 2 = CM OS time status indicator 0 = Time is valid 1 = Time is Invalid Bits 1-0 = Reserved

0Fh

15

1 byte

Shutdown code 00h = Power on or soft reset 01h = M emory size pass 02h = M emory test pass 03h = M emory test fail 04h = POST end; boot system 05h = JM P double word pointer with EOI 06h = Protected mode tests pass 07h = Protected mode tests fail 07h = Protected mode tests fail 08h = M emory size fail 09h = Int 15h block move 0Ah = JM P double word pointer without EOI 0Bh = used by 80386

10h

16

1 byte

Floppy disk drive types Bits 7-4 = Drive 0 type Bits 3-0 = Drive 1 type 0000 = None 0001 = 360K 0010 = 1.2M 0011 = 720K 0100 = 1.44M

11h

17

1 byte

Reserved

12h

18

1 byte

Hard disk types Bits 7–4 = Hard disk 0 type (0–15) Bits 3–0 = Hard disk 1 type (0–15)

13h

19

1 byte

Reserved

14h

20

1 byte

Installed equipment Bits 7–6 = Number of floppy disk drives 00 = 1 floppy disk drive 01 = 2 floppy disk drives Bits 5–4 = Primary display 00 = Use display adapter BIOS 01 = CGA 40-column 10 = CGA 80-column 11 = M onochrome Display Adapter Bits 3–2 = Reserved Bit 1 = M ath coprocessor present Bit 0 = Floppy disk drive present

15h

21

1 byte

Base memory low-order byte

16h

22

1 byte

Base memory high-order byte

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Offset Hex

Offset Dec

Field Size

Funct ion

17h

23

1 byte

Extended memory low-order byte

18h

24

1 byte

Extended memory high-order byte

19h

25

1 byte

Hard Disk 0 Extended Type (0–255)

1Ah

26

1 byte

Hard Disk 1 Extended Type (0–255)

1Bh

27

9 bytes

Reserved

2Eh

46

1 byte

CM OS checksum high-order byte

2Fh

47

1 byte

CM OS checksum low-order byte

30h

48

1 byte

Actual extended memory low-order byte

31h

49

1 byte

Actual extended memory high-order byte

32h

50

1 byte

Date century in BCD

33h

51

1 byte

POST information flag Bit 7 = Top 128K base memory status 0 = Top 128K base memory not installed 1 = Top 128K base memory installed Bit 6 = Setup program flag 0 = Normal (default) 1 = Put out first user message Bits 5–0 = Reserved

34h

52

2 bytes

Reserved

Note th at m an y n ewer system s h ave m ore th an 64 bytes of CMOS RAM; in fact, in som e system s th ey m ay h ave 2K or 4K. Th e extra room is u sed to store th e Plu g-an d -Play in form ation d etailin g th e con figu ration of ad ap ter card s an d oth er op tion s in th e system . As su ch , th ere is n o 100% stan d ard for h ow CMOS in form ation is stored in all system s. Table 4.13 on ly sh ows h ow th e origin al system s d id it; n ewer BIOS version s an d m oth erboard d esign s can d o th in gs d ifferen tly. You sh ou ld con su lt th e BIOS m an u factu rer for m ore in form ation if you wan t th e fu ll d etails of h ow CMOS is stored as th e CMOS con figu ration an d Setu p p rogram is n orm ally a p art of th e BIOS. Th is is an oth er exam p le of h ow close th e relation sh ip is between th e BIOS an d th e m oth erboard h ard ware. Th ere are backu p p rogram s an d u tilities in th e p u blic d om ain for CMOS RAM in form ation , wh ich can be u sefu l for savin g an d later restorin g a con figu ration . Un fortu n ately, th ese p rogram s wou ld be BIOS sp ecific an d wou ld on ly fu n ction on a BIOS th ey are d esign ed for. As su ch , I d on ’t n orm ally rely on th ese p rogram s as th ey are too m oth erboard an d BIOS sp ecific an d will n ot work on all m y system s seam lessly. Table 4.14 sh ows th e valu es th at m ay be stored by you r system BIOS in a sp ecial CMOS byte called th e diagnostics status byte. By exam in in g th is location with a d iagn ostics p rogram , you can d eterm in e wh eth er you r system h as set trouble codes, wh ich in d icate th at a p roblem p reviou sly h as occu rred .

227

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Chapter 4—M otherboards and Buses

Table 4.14

CM OS RAM Diagnost ic St at us Byt e Codes

Bit Num ber 76543210

Hex

Funct ion

1 • • • • • • •

80

Real-time clock (RTC) chip lost power

• 1 • • • • • •

40

CM OS RAM checksum is bad

• • 1 • • • • •

20

Invalid configuration information found at POST

• • • 1 • • • •

10

M emory size compare error at POST

• • • • 1 • • •

08

Fixed disk or adapter failed initialization

• • • • • 1 • •

04

Real-time clock (RTC) time found invalid

• • • • • • 1 •

02

Adapters do not match configuration

• • • • • • • 1

01

Time-out reading an adapter ID

• • • • • • • •

00

No errors found (Normal)

If th e Diagn ostic statu s byte is an y valu e oth er th an zero, you will n orm ally get a CMOS con figu ration error on bootu p . Th ese typ es of errors can be cleared by reru n n in g th e Setu p p rogram . M ot herboard Int erface Connect ors Th ere are a variety of d ifferen t con n ectors on a m od ern m oth erboard . Figu re 4.10 sh ows th e location of th ese con n ectors on a typ ical m oth erboard (u sin g th e In tel SE440BX m od el as th e exam p le). Several of th ese con n ectors su ch as p ower su p p ly con n ectors, serial an d p arallel p orts, an d keyboard / m ou se con n ectors are covered in oth er ch ap ters. Tables 4.15–4.19 con tain th e p in ou ts of m ost of th e oth er d ifferen t in terface an d I/ O con n ectors you will fin d . ◊◊ See “ Power Supply Connectors,” p. 403 ◊◊ See “ Serial Ports,” p. 583, and “ Parallel Ports,” p. 593 ◊◊ See “ Keyboard/ M ouse Interface Connectors,” p. 470 ◊◊ See “ USB (Universal Serial Bus),” p. 601 ◊◊ See “ ATA I/ O Connector,” p. 615

M otherboard Components

A

B

C

D

F

G

H

I

J

E 1

1 1

1

1 1

1

1

6 5 1 2

2

40

2

39

1 11

1

10 20 1

40 1 39

T

S

R

Q P

O

N

34

1 2 1

M

33

L

A

Wake on Ring (J1A1)

K

Fan 1 (J8M1)

B

PCI slots (J4D2, J4D1, J4C1, J4B1)

L

Diskette drive (J8K1)

C

Optional Wake on LAN technology (J1C1)

M

Power supply (J7L1)

D

Fan 3 (J3F2)

N

Optional SCSI LED (J8J1)

E

Optional Auxiliary Line In (J2F2)

O

Front panel (J8G2)

F

Optional telephony (J2F1)

P

Primary and secondary IDE (J7G1, J8G1)

G

Optional CD-ROM audio (J1F1)

Q

DIMMs (J6J1, J6J2, J7J1)

H

Optional chassis intrusion (J3F1)

R

A.G.P. (J4E1)

I

Slot 1 (J4J1)

S

PC/PCI (J6D1)

J

Fan 2 (J4M1)

T

ISA slots (J4B2, J4A1)

FIG. 4.10 Typ ical m oth erboard con n ectors (In tel SE440BX sh own ).

K

229

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Chapter 4—M otherboards and Buses

Table 4.15

Infrared Dat a ( IrDA) Pin-Header Connect or

Pin

Signal Nam e

Pin

Signal Nam e

1

+5 V

4

Ground

2

Key

5

IrTX

3

IrRX

6

CONIR (Consumer IR)

Table 4.16

Bat t ery Connect or

Pin

Signal

Pin

Signal

1

Gnd

3

KEY

2

Unused

4

+6v

Table 4.17 Pin

LED and Keylock Connect or

Signal

Pin

Signal

1

LED Power (+5v)

4

Keyboard Inhibit

2

KEY

5

Gnd

3

Gnd

Table 4.18

Speaker Connect or

Pin

Signal

Pin

Signal

1

Ground

3

Board-M ounted Speaker

2

KEY

4

Speaker Output

Table 4.19

M icroprocessor Fan Pow er Connect or

Pin

Signal Nam e

1

Ground

2

+12V

3

Sense tachometer

Caut ion Do not place a jumper on this connector; serious board damage will result if the 12v is shorted to ground.

Note th at som e board s h ave a board m ou n ted p iezo sp eaker. It is en abled by p lacin g a ju m p er over p in s 3 an d 4, wh ich rou tes th e sp eaker ou tp u t to th e board -m ou n ted sp eaker. Rem ovin g th e ju m p er allows a con ven tion al sp eaker to be p lu gged in . Som e oth er con n ectors th at you m ay fin d on som e n ewer m oth erboard s are listed in Tables 4.20–4.25.

M otherboard Components

Table 4.20

Chassis Int rusion ( Securit y) Pin-Header

Pin

Signal Nam e

1

Ground

2

CHS_SEC

Table 4.21

W ake on LAN Pin-Header

Pin

Signal Nam e

1

+5 VSB

2

Ground

3

WOL

Table 4.22

CD Audio Connect or

Pin

Signal Nam e

1

CD_IN-Left

3

Ground

2

Ground

4

CD_IN-Right

Pin

Signal Nam e

Table 4.23

Pin

Signal Nam e

Telephony Connect or

Pin

Signal Nam e

1

Audio Out (monaural)

3

Ground

2

Ground

4

Audio In (monaural)

Table 4.24

ATAPI-St yle Line In Connect or

Pin

Signal Nam e

1

Left Line In

3

Ground

2

Ground

4

Right Line In (monaural)

Table 4.25 Pin

Pin

Signal Nam e

W ake on Ring Pin-Header

Signal Nam e

1

Ground

2

RINGA

In tel an d several oth er m oth erboard m an u factu rers like to p lace all th e fron t-p an el m oth erboard con n ectors in a sin gle row as sh own in Figu re 4.11. 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 * * •

* * *

Sp eaker

Reset

•

* •

* •

Power LED

* * • HD LED

* •

* * * * • *• ** * *

In frared Data

Sleep Power

Figure 4.11 Typ ical ATX m oth erboard fron t p an el con n ectors (In tel m oth erboard sh own ).

231

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Chapter 4—M otherboards and Buses

Table 4.26 sh ows th e d esign ation s for th e fron t-p an el m oth erboard con n ectors com m on ly u sed on In tel ATX m oth erboard s. Table 4.26 Typical ATX M ot herboard Front Panel Connect ors ( Int el M ot herboard show n) Connect or

Pin

Signal Nam e

Speaker

27

SPKR_HDR

26

PIEZO_IN

25

Key

24

Ground

Reset

23

SW_RST

22

Ground

none

21

No connect/ Key

Sleep/ Power LED

20

PWR_LED

19

Key

18

Ground

none

17

No connect/ Key

Hard Drive LED

16

HD_PWR

15

HD Active#

14

Key

13

HD_PWR +5 V

none

12

No connect

IrDA

11

CONIR (Consumer IR)

10

IrTX

9

Ground

8

IrRX

7

Key

6

+5V

none

5

No connect

Sleep/ Resume

4

SLEEP_PU (pullup)

3

SLEEP

Power On

2

Ground

1

SW_ON#

Syst em Bus Funct ions and Feat ures At th e h eart of every m oth erboard are th e bu ses th at m ake it u p . A bus is n oth in g bu t a com m on p ath way across wh ich d ata can travel with in a com p u ter. Th is p ath way is u sed for com m u n ication an d can be establish ed between two or m ore com p u ter elem en ts.

System Bus Functions and Features

Th e PC h as a h ierarch y of d ifferen t bu ses. Most m od ern PCs h ave at least th ree d ifferen t bu ses; som e h ave fou r or m ore. Th ey are h ierarch ical becau se each slower bu s is con n ected to th e faster on e above it. Each d evice in th e system is con n ected to on e of th e bu ses, an d som e d evices (p rim arily th e ch ip set) act as brid ges between th e variou s bu ses. Th e m ain bu ses in a m od ern system are as follows: ■ The Processor Bus. Th is is th e h igh est-sp eed bu s in th e system an d is at th e core of th e ch ip set an d m oth erboard . Th is bu s is u sed p rim arily by th e p rocessor to p ass in form ation to an d from cach e or m ain m em ory, an d th e North Brid ge of th e ch ip set. Th e p rocessor bu s in Pen tiu m II system s ru n s at eith er 66 or 100MHz an d h as th e fu ll 64-bit d ata p ath wid th of th e p rocessor. ■ The AGP (Accelerated Graphics Port) Bus. Th is is a h igh -sp eed 66MHz, 32-bit bu s sp ecifically for a vid eo card . It is con n ected to th e North Brid ge of th e ch ip set an d is m an ifested as a sin gle AGP slot in system s th at su p p ort it. ■ The PCI (Peripheral Com ponent Interconnect) Bus. Th is is a 33Mh z, 32-bit bu s fou n d in virtu ally all n ewer 486 system s an d virtu ally all Pen tiu m an d h igh er p rocessor system s. Th is bu s is gen erated by th e ch ip set North Brid ge, wh ich acts as th e PCI con troller. Th is bu s is m an ifested in th e system as a collection of 32-bit slots, n orm ally abou t fou r on m ost m oth erboard s. High -sp eed p erip h erals su ch as SCSI ad ap ters, n etwork card s, vid eo card s, an d m ore can be p lu gged in to PCI bu s slots. Th e ch ip set Sou th Brid ge is p lu gged in to th e PCI bu s, an d from th ere gen erates th e IDE an d USB p orts. ■ The ISA (Industry Standard Architecture) Bus. Th is is an 8MHz, 16-bit bu s th at rem ain s in system s tod ay after first ap p earin g in th e origin al PC in 8-bit, 5MHz form , an d in th e 1984 IBM AT in fu ll 16-bit form . It is a very slow-sp eed bu s, bu t still id eal for certain slow-sp eed or old er p erip h erals. Th e PC in d u stry h as been loath to give u p th is bu s, d esp ite p ressu re from Microsoft an d In tel to d o away with it in fu tu re PC d esign s. Most p eop le h ave u sed it in recen t tim es for p lu g-in m od em s, sou n d card s, an d variou s oth er low-sp eed p erip h erals. Th e ISA bu s is gen erated by th e Sou th Brid ge p art of th e m oth erboard ch ip set, wh ich acts as th e ISA bu s con troller an d th e in terface between th e ISA bu s an d th e faster PCI bu s above it. Th e m oth erboard ’s Su p er I/ O ch ip is n orm ally con n ected to th is bu s. Th e system ch ip set is th e con d u ctor th at con trols th e orch estra of system com p on en ts, allowin g each to h ave th eir tu rn on th eir resp ective bu ses. Bus Type

W idt h ( bit s)

Speed ( M Hz)

Bandw idt h ( M M / sec)

8-bit ISA

8

4.77

2.39

16-bit ISA

16

8.33

8.33

EISA*

32

8.33

33.3

VLB*

32

33.33

133.33

PCI

32

33.33

133.33 (continues)

233

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Chapter 4—M otherboards and Buses

(continued)

Bus Type

W idt h ( bit s)

Speed ( M Hz)

Bandw idt h ( M M / sec)

PCI-2x**

32

66.66

266.66

PCI 64-bit**

64

33.33

266.66

PCI-2x 64-bit**

64

66.66

533.33

AGP

32

66.66

266.66

AGP-2x

32

66.66

533.33

AGP-4x*

32

66.66

1,066.66

* EISA and V LB are no longer used in current m otherboard designs. ** Note that these bus types are proposed and have not yet been im plem ented in PC system s.

Th e PCI bu s h as two p rop osed exten sion s. On e is to go from 32 bits to 64 bits. Th e oth er is to d ou ble th e clock sp eed of th e bu s to 66MHz. So far, n eith er of th ese h as been im p lem en ted in PC system s, an d it d oesn ’t seem likely th ey will in th e n ear fu tu re. More likely is th at we will see th e fu tu re im p lem en tation s of AGP soon er; th at is, a 2x m od e an d a 4x m od e. In terestin gly en ou gh , th ese faster m od es will be ach ieved at th e sam e clock rate; th e on ly d ifferen ce is th at 2 or 4 bits will be tran sferred for every h ertz (cycle) rath er th an th e 1 bit p er cycle stan d ard tod ay. Th is will allow th e AGP bu s to keep p ace with fu tu re vid eo n eed s, all th e way to over 1,066M/ sec! Th e followin g section s d iscu ss th e p rocessor an d oth er su bset bu ses in th e system , an d th e m ain I/ O bu ses m en tion ed in th e p reviou s ch art. The Processor Bus Th e processor bus is th e com m u n ication p ath way between th e CPU an d m oth erboard ch ip set, m ore sp ecifically th e North Brid ge. Th is bu s ru n s at th e fu ll m oth erboard sp eed , wh ich is n orm ally 66MHz, 75MHz, or 100MHz, an d is u sed to tran sfer d ata between th e CPU an d th e ch ip set North Brid ge, an d between th e CPU an d an extern al m em ory cach e on Pen tiu m (P5 class) system s. Figu re 4.12 sh ows h ow th is bu s fits in to a typ ical Pen tiu m (P5 class) PC system . In Figu re 4.12 you can see wh ere an d h ow th e oth er m ain bu ses, su ch as th e PCI an d IDE bu ses, fit in to th e system . As you can see th ere is clearly a th ree-tier arch itectu re with th e fastest CPU bu s on top , th e PCI bu s n ext, an d th e ISA bu s at th e bottom . Differen t com p on en ts in th e system are con n ected to on e of th ese th ree m ain bu ses. Pen tiu m (P5) class system s h ave an extern al cach e for th e CPU; th ese cach es are con n ected to th e p rocessor bu s th at ru n s at th e m oth erboard sp eed (n orm ally 66MHz). Th u s, as th e Pen tiu m p rocessors h ave been gettin g faster an d faster, th e L2 cach e h as u n fortu n ately rem ain ed at th e relatively slow m oth erboard sp eed . Th is was solved in th e Pen tiu m Pro an d Pen tiu m II system s. Th ey h ave m oved th e L2 cach e off of th e m oth erboard an d d irectly on to th e CPU. By in corp oratin g th e L2 cach e in th e CPU, th ey can ru n it at a sp eed closer to th e tru e CPU sp eed . In th e Pen tiu m Pro, th e L2 cach e actu ally d oes ru n at fu ll CPU sp eed , bu t in th e Pen tiu m II it ru n s at on e h alf of th e p rocessor sp eed . Th is is still m u ch faster th an th e m oth erboard -bou n d cach e on th e Socket 7 P5

System Bus Functions and Features

class system s. Th e bu ilt-in L2 CPU cach e is on e of th e m ain reason s th e Socket 8 an d Slot 1 arch itectu re is su p erior to th e Socket 7 d esign s. Pentium CPU

Up to 266MHz

L1 Cache Processor Bus 66MHz

L2 Cache (15ns)

66MHz

16/66MHz North Bridge (430TX)

PCI Bus 33MHz

USB1

EDO SIMM (16MHz) or SDRAM DIMM (66MHz)

PCI Slots

USB2 South Bridge (PIIX4)

CMOS & RTC

IDE 1

PCI Video

IDE 2

ISA Bus 8 MHz

ISA Slots

Floppy

Keyboard Mouse

Super I/O (87307)

COM 1

COM 2

LPT 1 ROM Flash BIOS

FIG. 4.12 Typ ical Pen tiu m (P5 Class) system arch itectu re sh owin g th e d ifferen t bu s levels in th e system .

Note th at recen tly th ere is a n ew version of th e Socket 7 arch itectu re called “Su p er-7” d esign ed p rim arily by AMD an d Cyrix for th eir n ew Socket 7 P5 class p rocessors th at ru n at m oth erboard sp eed s u p to 100MHz. Th is is d efin itely better th an 66MHz, bu t still n ot q u ite u p to th e Slot-1 arch itectu re wh ere th e L2 cach e au tom atically scales u p in sp eed alon g with th e p rocessor. By m ovin g th e L2 cach e off th e m oth erboard , th e Slot-1 d esign s offer greater p erform an ce. Figu re 4.13 sh ows th e typ ical Pen tiu m II system d esign . You can see th e two m ain ch an ges: On e is th e L2 cach e n ow ru n s at h alf p rocessor core sp eed rath er th an

235

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Chapter 4—M otherboards and Buses

m oth erboard sp eed . Also n ote th at th e m oth erboard sp eed h as been in creased to 100MHz, wh ich d ram atically im p roves m ain m em ory p erform an ce com bin ed with 100MHz SDRAM m em ory. Th e oth er m ain ch an ge is th e ad d ition of a n ew sin gle slot bu s called AGP (Accelerated Grap h ics Port). Th is allows th e vid eo card to be on its own d ed icated h igh -sp eed bu s, wh ich ru n s at twice th e sp eed of PCI. Actu ally, th e sp eed is m islead in g as AGP h as 2x an d 4x m od es th at allow a fu rth er d ou blin g or q u ad ru p lin g of th e sp eed over th e base of 66MHz. Th is resu lts in in cred ible vid eo ban d wid th , n ecessary for fu ll-m otion vid eo cap tu re an d d isp lay. Up to 450MHz Pentium II

L2 Cache

1/2

CPU = 225MHz

L1 Cache Processor Bus 100MHz

66MHz

100MHz

AGP North Bridge (440BX)

Video

PCI Bus 33 MHz

USB1

100MHz SDRAM DIMM

PCI Slots

USB2 South Bridge (PIIX4E)

CMOS & RTC

IDE 1

IDE 2

ISA Bus 8MHz

ISA Slots

Floppy

Keyboard Mouse

Super I/O (376777)

COM 1

COM 2

LPT 1 ROM Flash BIOS

FIG. 4.13 Typ ical Pen tiu m II (P6 Class) system arch itectu re sh owin g th e d ifferen t bu s levels in th e system .

Becau se th e p u rp ose of th e p rocessor bu s is to get in form ation to an d from th e CPU at th e fastest p ossible sp eed , th is bu s op erates at a m u ch faster rate th an an y oth er bu s in

System Bus Functions and Features

you r system ; n o bottlen eck exists h ere. Th e bu s con sists of electrical circu its for d ata, for ad d resses (th e ad d ress bu s, wh ich is d iscu ssed in th e followin g section ), an d for con trol p u rp oses. In a Pen tiu m -based system , th e p rocessor bu s h as 64 d ata lin es, 32 ad d ress lin es, an d associated con trol lin es. Th e Pen tiu m Pro an d Pen tiu m II h ave 36 ad d ress lin es, bu t oth erwise are th e sam e as th e Pen tiu m an d Pen tiu m MMX. Th e p rocessor bu s op erates at th e sam e base clock rate as th e CPU d oes extern ally. Th is can be m islead in g as m ost CPUs th ese d ays ru n in tern ally at a h igh er clock rate th an th ey d o extern ally. For exam p le, a Pen tiu m 266 system h as a Pen tiu m CPU ru n n in g at 266MHz in tern ally, bu t on ly 66.6MHz extern ally, wh ile a Pen tiu m II 450 ru n s at 450MHz in tern ally bu t on ly 100MHz extern ally. A Pen tiu m 133, 166, 200, an d even a Pen tiu m 233 also ru n th e p rocessor extern al bu s at 66.6MHz. In m ost n ewer system s, th e actu al p rocessor sp eed is som e m u ltip le (1.5x, 2x, 2.5x, 3x, an d so on ) of th e p rocessor bu s. √√ See “ Processor Speed Ratings,” p. 33

Th e p rocessor bu s is tied to th e extern al p rocessor p in con n ection s an d can tran sfer on e bit of d ata p er d ata lin e every on e or two clock cycles. Th u s, a Pen tiu m , Pen tiu m Pro, or Pen tiu m II can tran sfer 64 bits of d ata at a tim e. To d eterm in e th e tran sfer rate for th e p rocessor bu s, you m u ltip ly th e d ata wid th (64 bits for a Pen tiu m , Pen tiu m Pro, or Pen tiu m II) by th e clock sp eed of th e bu s (th e sam e as th e base or u n m u ltip lied clock sp eed of th e CPU). If you are u sin g a Pen tiu m , Pen tiu m MMX, Pen tiu m Pro, or Pen tiu m II ch ip th at ru n s at a 66MHz m oth erboard sp eed , an d it can tran sfer a bit of d ata each clock cycle on each d ata lin e, you h ave a m axim u m in stan tan eou s tran sfer rate of rou gh ly 528M/ sec. You get th is resu lt by u sin g th e followin g form u la: 66MHz×64 bits = 4,224Mbit/ sec 4,224Mbit/ sec÷8 = 528M/ sec Th is tran sfer rate, often called th e bandwidth of th e bu s, rep resen ts a m axim u m . Like all m axim u m s, th is rate d oes n ot rep resen t th e n orm al op eratin g ban d wid th ; you sh ou ld exp ect m u ch lower average th rou gh p u t. Oth er lim itin g factors su ch as ch ip set d esign , m em ory d esign an d sp eed , an d so on con sp ire to lower th e effective average th rou gh p u t. The M em ory Bus Th e m em ory bus is u sed to tran sfer in form ation between th e CPU an d m ain m em ory—th e RAM in you r system . Th is bu s is con n ected to th e m oth erboard ch ip set North Brid ge ch ip . Dep en d in g on th e typ e of m em ory you r ch ip set (an d th erefore m oth erboard ) is d esign ed to h an d le, th e North Brid ge will ru n th e m em ory bu s at d ifferen t sp eed s. System s th at u se FPM (Fast Page Mod e) or EDO (Exten d ed Data Ou t) m em ory with a 60n s access tim e ru n th e m em ory bu s at on ly 16MHz. Th at is becau se 16MHz resu lts in abou t 60n s cyclin g sp eed . Newer ch ip sets an d m oth erboard s th at su p p ort SDRAM can ru n th e m em ory bu s at 66MHz (15n s) or u p to 100MHz (10n s). Th is obviou sly resu lts in faster m em ory p erform an ce an d virtu ally n egates th e n eed for h avin g cach e m em ory on th e

237

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m oth erboard . Th at is wh y th e Pen tiu m II p rocessor was d esign ed to in clu d e a h igh er sp eed L2 cach e bu ilt in , as th e SDRAM m em ory on th e m oth erboard alread y ru n s at th e sam e sp eed as th e m oth erboard cach e fou n d in old er Pen tiu m system s. Figu re 4.12 an d Figu re 4.13 sh ow h ow th e m em ory bu s fits in to you r PC.

Not e Notice that the main memory bus is always the same width as the processor bus. This will define the size of what is called a “ bank” of memory. M emory banks and their width relative to processor buses are discussed in the “ M emory Banks” section in Chapter 5.

The Need for Expansion Slot s Th e I/ O bu s or exp an sion slots are wh at en ables you r CPU to com m u n icate with p erip h eral d evices. Th e bu s an d its associated exp an sion slots are n eed ed becau se basic system s can n ot p ossibly satisfy all th e n eed s of all th e p eop le wh o bu y th em . Th e I/ O bu s en ables you to ad d d evices to you r com p u ter to exp an d its cap abilities. Th e m ost basic com p u ter com p on en ts, su ch as sou n d card s an d vid eo card s, can be p lu gged in to exp an sion slots; you also can p lu g in m ore sp ecialized d evices, su ch as n etwork in terface card s, SCSI h ost ad ap ters, an d oth ers.

Not e In most modern PC systems, a variety of basic peripheral devices are built into the motherboard. M ost systems today have at least dual (primary and secondary) IDE interfaces, dual USB (Universal Serial Bus) ports, a floppy controller, two serial ports, a parallel port, keyboard, and mouse controller built directly into the motherboard. These devices are normally distributed between the motherboard chipset South Bridge and the Super I/ O chip. (Super I/ O chips are discussed earlier in this chapter.) M any will even add more items such as a built-in sound card, video adapter, SCSI host adapter, or network interface also built into the motherboard. Those items are not built into the motherboard chipset or Super I/ O chip, but would be configured as additional chips installed on the board. Nevertheless, these built-in controllers and ports still use the I/ O bus to communicate with the CPU. In essence, even though they are built in, they act as if there are cards plugged into the system’s bus slots, including using system resources in the same manner.

Types of I/ O Buses Sin ce th e in trod u ction of th e first PC, m an y I/ O bu ses h ave been in trod u ced . Th e reason is q u ite sim p le—faster I/ O sp eed s are n ecessary for better system p erform an ce. Th is n eed for h igh er p erform an ce in volves th ree m ain areas: ■ Faster CPUs ■ In creasin g software d em an d s ■ Greater m u ltim ed ia req u irem en ts

Types of I/ O Buses

Each of th ese areas req u ires th e I/ O bu s to be as fast as p ossible. Su rp risin gly, virtu ally all PC system s sh ip p ed tod ay still in corp orate th e sam e basic bu s arch itectu re as th e 1984 vin tage IBM PC/ AT. However, m ost of th ese system s n ow also in clu d e a secon d h igh sp eed local I/ O bu s su ch as VL-Bu s or PCI, wh ich offer m u ch greater p erform an ce for ad ap ters th at n eed it. Man y of th e n ewest system s also in clu d e a th ird h igh -sp eed bu s called AGP for im p roved vid eo p erform an ce beyon d wh at PCI offers. On e of th e p rim ary reason s wh y n ew I/ O-bu s stru ctu res h ave been slow in com in g is com p atibility—th at old Catch -22 th at an ch ors m u ch of th e PC in d u stry to th e p ast. On e of th e h allm arks of th e PC’s su ccess is its stan d ard ization . Th is stan d ard ization sp awn ed th ou san d s of th ird -p arty I/ O card s, each origin ally bu ilt for th e early bu s sp ecification s of th e PC. If a n ew h igh -p erform an ce bu s system is in trod u ced , it often h ad to be com p atible with th e old er bu s system s so th at th e old er I/ O card s wou ld n ot be obsolete. Th erefore, bu s tech n ologies seem to evolve rath er th an m ake q u an tu m leap s forward . You can id en tify d ifferen t typ es of I/ O bu ses by th eir arch itectu re. Th e m ain typ es of I/ O arch itectu re are: ■ ISA

■ AGP

■ Micro Ch an n el Arch itectu re (MCA)

■ PC-Card (form erly PCMCIA)

■ EISA

■ FireW ire (IEEE-1394)

■ VESA Local Bu s (VL-Bu s)

■ Un iversal Serial Bu s (USB)

■ PCI Local Bu s ◊◊ See “ PC Cards,” p. 932 ◊◊ See “ Firewire (IEEE 1394),” p. 604 ◊◊ See “ USB (Universal Serial Bus),” p. 601

Th e d ifferen ces am on g th ese bu ses con sist p rim arily of th e am ou n t of d ata th at th ey can tran sfer at on e tim e an d th e sp eed at wh ich th ey can d o it. Each bu s arch itectu re is im p lem en ted by a ch ip set th at is con n ected to th e p rocessor bu s. Typ ically, th is ch ip set also con trols th e m em ory bu s. Th e followin g section s d escribe th e d ifferen t typ es of PC bu ses. The ISA Bus ISA, wh ich is an acron ym for Industry Standard Architecture, is th e bu s arch itectu re th at was in trod u ced as an 8-bit bu s with th e origin al IBM PC in 1981 an d later exp an d ed to 16 bits with th e IBM PC/ AT in 1984. ISA is th e basis of th e m od ern p erson al com p u ter an d th e p rim ary arch itectu re u sed in th e vast m ajority of PC system s on th e m arket tod ay. It m ay seem am azin g th at su ch a seem in gly an tiq u ated arch itectu re is u sed in tod ay’s h igh -p erform an ce system s, bu t th is is tru e for reason s of reliability, afford ability, an d com p atibility, p lu s th is old bu s is still faster th an m an y of th e p erip h erals th at we con n ect to it!

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Two version s of th e ISA bu s exist, based on th e n u m ber of d ata bits th at can be tran sferred on th e bu s at a tim e. Th e old er version is an 8-bit bu s; th e n ewer version is a 16-bit bu s. Th e origin al 8-bit version ran at 4.77MHz in th e PC an d XT. Th e 16-bit version u sed in th e AT ran at 6MHz an d th en 8MHz. Later, th e in d u stry agreed on an 8.33MHz m axim u m stan d ard sp eed for 8/ 16-bit version s of th e ISA bu s for backward com p atibility. Som e system s h ave th e cap ability to ru n th e ISA bu s faster th an th is, bu t som e ad ap ter card s will n ot fu n ction p rop erly at h igh er sp eed s. ISA d ata tran sfers req u ire an ywh ere from two to eigh t cycles. Th erefore, th e th eoretical m axim u m d ata rate of th e ISA bu s is abou t 8M/ sec, as th e followin g form u la sh ows: 8MHz×16 bits = 128Mbit/ sec 128Mbit/ sec÷2 cycles = 64Mbit/ sec 64Mbit/ sec÷8 = 8M/ sec Th e ban d wid th of th e 8-bit bu s wou ld be h alf th is figu re (4M/ sec). Rem em ber, h owever, th at th ese figu res are th eoretical m axim u m s; becau se of I/ O bu s p rotocols, th e effective ban d wid th is m u ch lower—typ ically by alm ost h alf. Even so, at 8M/ sec, th e ISA bu s is still faster th an m an y of th e p erip h erals we con n ect to it. The 8-Bit ISA Bus. Th is bu s arch itectu re is u sed in th e origin al IBM PC com p u ters. Alth ou gh virtu ally n on existen t in n ew system s tod ay, th is arch itectu re still exists in h u n d red s of th ou san d s of PC system s in th e field . Ph ysically, th e 8-bit ISA exp an sion slot resem bles th e ton gu e-an d -groove system th at fu rn itu re m akers on ce u sed to h old two p ieces of wood togeth er. It is sp ecifically called a Card/Edge connector. An ad ap ter card with 62 con tacts on its bottom ed ge p lu gs in to a slot on th e m oth erboard th at h as 62 m atch in g con tacts. Electron ically, th is slot p rovid es eigh t d ata lin es an d 20 ad d ressin g lin es, en ablin g th e slot to h an d le 1M of m em ory. Figu re 4.14 d escribes th e p in ou ts for th e 8-bit ISA bu s. Figu re 4.15 sh ows h ow th ese p in s are orien ted in th e exp an sion slot. Alth ou gh th e d esign of th e bu s is sim p le, IBM waited u n til 1987 to p u blish fu ll sp ecification s for th e tim in gs of th e d ata an d ad d ress lin es. In th e early d ays of PC com p atibles, m an u factu rers h ad to d o th eir best to figu re ou t h ow to m ake ad ap ter board s. Th is p roblem was solved , h owever, as PC-com p atible p erson al com p u ters becam e m ore wid ely accep ted as th e in d u stry stan d ard an d m an u factu rers h ad m ore tim e an d in cen tive to bu ild ad ap ter board s th at worked correctly with th e bu s. Th e d im en sion s of 8-bit ISA ad ap ter card s are as follows: 4.2 in ch es (106.68m m ) h igh 13.13 in ch es (333.5m m ) lon g 0.5 in ch (12.7m m ) wid e

Types of I/ O Buses

Signal Ground RESET DRV +5 Vdc IRQ 2 -5 Vdc DRQ 2 -12 Vdc -CARD SLCTD +12 Vdc Ground -SMEMW -SMEMR -IOW -IOR -DACK 3 DRQ 3 -DACK 1 DRQ 1 -Refresh CLK(4.77MHz) IRQ 7 IRQ 6 IRQ 5 IRQ 4 IRQ 3 -DACK 2 T/C BALE +5 Vdc OSC(14.3MHz) Ground

Pin

Pin

Signal

B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B12 B13 B14 B15 B16 B17 B18 B19 B20 B21 B22 B23 B24 B25 B26 B27 B28 B29 B30 B31

A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 A21 A22 A23 A24 A25 A26 A27 A28 A29 A30 A31

-I/O CH CHK Data Bit 7 Data Bit 6 Data Bit 5 Data Bit 4 Data Bit 3 Data Bit 2 Data Bit 1 Data Bit 0 -I/O CH RDY AEN Address 19 Address 18 Address 17 Address 16 Address 15 Address 14 Address 13 Address 12 Address 11 Address 10 Address 9 Address 8 Address 7 Address 6 Address 5 Address 4 Address 3 Address 2 Address 1 Address 0

FIG. 4.14 Pin ou ts for th e 8-bit ISA bu s.

B1 A1

B31 A31

Rear of the Computer

FIG. 4.15 Th e 8-bit ISA bu s con n ector. The 16-Bit ISA Bus. IBM th rew a bom bsh ell on th e PC world wh en it in trod u ced th e AT with th e 286 p rocessor in 1984. Th is p rocessor h ad a 16-bit d ata bu s, wh ich m ean t th at com m u n ication s between th e p rocessor, th e m oth erboard , an d m em ory wou ld n ow be 16 bits wid e in stead of on ly 8 bits wid e. Alth ou gh th is p rocessor cou ld h ave been in stalled on a m oth erboard with on ly an 8-bit I/ O bu s, th at wou ld h ave m ean t a h u ge sacrifice in th e p erform an ce of an y ad ap ter card s or oth er d evices in stalled on th e bu s. Th e in trod u ction of th e 286 ch ip p osed a p roblem for IBM in relation to its n ext gen eration of PCs. Sh ou ld th e com p an y create a n ew I/ O bu s an d associated exp an sion slots, or sh ou ld it try to com e u p with a system th at cou ld su p p ort both 8- an d 16-bit card s? IBM op ted for th e latter solu tion , an d th e PC/ AT was in trod u ced with a set of exp an sion slots with 16-bit exten sion con n ectors. You can p lu g an 8-bit card in to th e forward p art of th e slot or a 16-bit card in to both p arts of th e slot.

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Not e The expansion slots for the 16-bit ISA bus also introduced access keys to the PC environment. An access key is a cutout or notch in an adapter card that fits over a corresponding tab in the connector into which the adapter card is inserted. Access keys typically are used to keep adapter cards from being inserted into a connector improperly.

Th e exten sion con n ector in each 16-bit exp an sion slot ad d s 36 con n ector p in s to carry th e extra sign als n ecessary to im p lem en t th e wid er d ata p ath . In ad d ition , two of th e p in s in th e 8-bit p ortion of th e con n ector were ch an ged . Th ese two m in or ch an ges d o n ot alter th e fu n ction of 8-bit card s. Figu re 4.16 d escribes th e p in ou ts for th e fu ll 16-bit ISA exp an sion slot. Figu re 4.17 sh ows th e orien tation an d relation of 8-bit an d 16-bit ISA bu s slots. Th e exten d ed 16-bit slots p h ysically in terfere with som e 8-bit ad ap ter card s th at h ave a skirt—an exten d ed area of th e card th at d rop s d own toward th e m oth erboard ju st after th e con n ector. To h an d le th ese card s, IBM left two exp an sion p orts in th e PC/ AT with ou t th e 16-bit exten sion s. Th ese slots, wh ich are id en tical to th e exp an sion slots in earlier system s, can h an d le an y skirted PC or XT exp an sion card . Th is is n ot a p roblem tod ay, as n o skirted 8-bit card s h ave been m an u factu red for years.

Not e 16-bit ISA expansion slots were introduced in 1984. Since then, virtually every manufacturer of 8-bit expansion cards have designed them without drop-down skirts so that they fit properly in 16-bit slots. M ost new systems do not have any 8-bit-only slots, because a properly designed 8-bit card will work in any 16-bit slot. Note that some poorly designed motherboards or adapter cards may have fitting problems. It is not uncommon to find that a full-length card will not work in a particular slot due to interference with the processor heat sink, SIM M or DIM M memory, voltage regulators, or other components on the board. Systems using the LPX motherboard and even the Baby-AT motherboard form factors are especially prone to these problems. This is another reason I recommend ATX form factor systems because things fit so much better.

Th e d im en sion s of a typ ical AT exp an sion board are as follows: 4.8 in ch es (121.92m m ) h igh 13.13 in ch es (333.5m m ) lon g 0.5 in ch (12.7m m ) wid e Two h eigh ts actu ally are available for card s th at are com m on ly u sed in AT system s—4.8 in ch es an d 4.2 in ch es (th e h eigh t of old er PC-XT card s). Th e sh orter card s becam e an issu e wh en IBM in trod u ced th e XT Mod el 286. Becau se th is m od el h as an AT

Types of I/ O Buses

m oth erboard in an XT case, it n eed s AT-typ e board s with th e 4.2-in ch m axim u m h eigh t. Most board m akers trim m ed th e h eigh t of th eir board s; m an y m an u factu rers n ow m ake on ly 4.2-in ch tall (or less) board s so th at th ey will work in system s with eith er p rofile. Signal

Pin

Ground RESET DRV +5 Vdc IRQ 9 -5 Vdc DRQ 2 -12 Vdc -0 WAIT +12 Vdc Ground -SMEMW -SMEMR -IOW -IOR -DACK 3 DRQ 3 -DACK 1 DRQ 1 -Refresh CLK(8.33MHz) IRQ 7 IRQ 6 IRQ 5 IRQ 4 IRQ 3 -DACK 2 T/C BALE +5 Vdc OSC(14.3MHz) Ground

B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B12 B13 B14 B15 B16 B17 B18 B19 B20 B21 B22 B23 B24 B25 B26 B27 B28 B29 B30 B31

-MEM CS16 -I/O CS16 IRQ 10 IRQ 11 IRQ 12 IRQ 15 IRQ 14 -DACK 0 DRQ 0 -DACK 5 DRQ5 -DACK 6 DRQ 6 -DACK 7 DRQ 7 +5 Vdc -Master Ground

D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15 D16 D17 D18

FIG. 4.16 Pin ou ts for th e 16-bit ISA bu s.

Pin A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 A21 A22 A23 A24 A25 A26 A27 A28 A29 A30 A31

C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18

Signal -I/O CH CHK Data Bit 7 Data Bit 6 Data Bit 5 Data Bit 4 Data Bit 3 Data Bit 2 Data Bit 1 Data Bit 0 -I/O CH RDY AEN Address 19 Address 18 Address 17 Address 16 Address 15 Address 14 Address 13 Address 12 Address 11 Address 10 Address 9 Address 8 Address 7 Address 6 Address 5 Address 4 Address 3 Address 2 Address 1 Address 0

-SBHE Latch Address 23 Latch Address 22 Latch Address 21 Latch Address 20 Latch Address 19 Latch Address 18 Latch Address 17 -MEMR -MEMW Data Bit 8 Data Bit 9 Data Bit 10 Data Bit 11 Data Bit 12 Data Bit 13 Data Bit 14 Data Bit 15

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8/16-bit ISA Bus Pinouts. 8-bit PC/XT Connector:

Signal GROUND RESET DRV +5 Vdc IRQ 2 -5 Vdc DRQ 2 -12 Vdc -CARD SLCT +12 Vdc GROUND -SMEMW -SMEMR -IOW -IOR -DACK 3 DRQ 3 -DACK 1 DRQ 1 -REFRESH CLK (4.77MHz) IRQ 7 IRQ 6 IRQ 5 IRQ 4 IRQ 3 -DACK 2 T/C BALE +5 Vdc OSC (14.3MHz) GROUND

16-bit AT Connector:

Pin Numbers B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B12 B13 B14 B15 B16 B17 B18 B19 B20 B21 B22 B23 B24 B25 B26 B27 B28 B29 B30 B31

A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 A21 A22 A23 A24 A25 A26 A27 A28 A29 A30 A31

Signal -I/O CHK DATA 7 DATA 6 DATA 5 DATA 4 DATA 3 DATA 2 DATA 1 DATA 0 -I/O RDY AEN ADDR 19 ADDR 18 ADDR 17 ADDR 16 ADDR 15 ADDR 14 ADDR 13 ADDR 12 ADDR 11 ADDR 10 ADDR 9 ADDR 8 ADDR 7 ADDR 6 ADDR 5 ADDR 4 ADDR 3 ADDR 2 ADDR 1 ADDR 0

Signal

Pin Numbers

Signal

GROUND RESET DRV +5 Vdc IRQ 9 -5 Vdc DRQ 2 -12 Vdc -OWS +12 Vdc GROUND -SMEMW -SMEMR -IOW -IOR -DACK 3 DRQ 3 -DACK 1 DRQ 1 -REFRESH CLK (8.33MHz) IRQ 7 IRQ 6 IRQ 5 IRQ 4 IRQ 3 -DACK 2 T/C BALE +5 Vdc OSC (14.3MHz) GROUND

B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B12 B13 B14 B15 B16 B17 B18 B19 B20 B21 B22 B23 B24 B25 B26 B27 B28 B29 B30 B31

A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 A21 A22 A23 A24 A25 A26 A27 A28 A29 A30 A31

-I/O CHK DATA 7 DATA 6 DATA 5 DATA 4 DATA 3 DATA 2 DATA 1 DATA 0 -I/O RDY AEN ADDR 19 ADDR 18 ADDR 17 ADDR 16 ADDR 15 ADDR 14 ADDR 13 ADDR 12 ADDR 11 ADDR 10 ADDR 9 ADDR 8 ADDR 7 ADDR 6 ADDR 5 ADDR 4 ADDR 3 ADDR 2 ADDR 1 ADDR 0

-MEM CS16 -I/O CS16 IRQ 10 IRQ 11 IRQ 12 IRQ 15 IRQ 14 -DACK 0 DRQ 0 -DACK 5 DRQ 5 -DACK 6 DRQ 6 -DACK 7 DRQ 7 +5 Vdc -MASTER GROUND

D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15 D16 D17 D18

C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18

-SBHE LADDR 23 LADDR 22 LADDR 21 LADDR 20 LADDR 19 LADDR 18 LADDR 17 -MEMR -MEMW DATA 8 DATA 9 DATA 10 DATA 11 DATA 12 DATA 13 DATA 14 DATA 15

FIG. 4.17 Th e 8-bit an d 16-bit ISA bu s con n ectors. 32-Bit Buses. After 32-bit CPUs becam e available, it was som e tim e before 32-bit bu s stan d ard s becam e available. Before MCA an d EISA sp ecs were released , som e ven d ors began creatin g th eir own p rop rietary 32-bit bu ses, wh ich were exten sion s of th e ISA bu s. Alth ou gh th e p rop rietary bu ses were few an d far between , th ey d o still exist. Th e exp an d ed p ortion s of th e bu s typ ically are u sed for p rop rietary m em ory exp an sion or vid eo card s. Becau se th e system s are p rop rietary (m ean in g th at th ey are n on stan d ard ), p in ou ts an d sp ecification s are n ot available.

Types of I/ O Buses

The M icro Channel Bus Th e in trod u ction of 32-bit ch ip s m ean t th at th e ISA bu s cou ld n ot h an d le th e p ower of an oth er n ew gen eration of CPUs. Th e 386DX ch ip s can tran sfer 32 bits of d ata at a tim e, bu t th e ISA bu s can h an d le a m axim u m of 16 bits. Rath er th an exten d th e ISA bu s again , IBM d ecid ed to bu ild a n ew bu s; th e resu lt was th e MCA bu s. MCA (Micro Channel Architecture) is com p letely d ifferen t from th e ISA bu s an d is tech n ically su p erior in every way. IBM n ot on ly wan ted to rep lace th e old ISA stan d ard , bu t also to receive royalties on it; th e com p an y req u ired ven d ors th at licen sed th e n ew MCA bu s to p ay IBM royalties for u sin g th e ISA bu s in all p reviou s system s. Th is req u irem en t led to th e d evelop m en t of th e com p etin g EISA bu s (see th e n ext section on th e EISA bu s) an d h in d ered accep tan ce of th e MCA bu s. An oth er reason wh y MCA h as n ot been ad op ted u n iversally for system s with 32-bit slots is ad ap ter card s d esign ed for ISA system s d o n ot work in MCA system s.

Not e The M CA bus is not compatible with the older ISA bus, so cards designed for the ISA bus do not work in an M CA system.

MCA ru n s asyn ch ron ou sly with th e m ain p rocessor, m ean in g th at fewer p ossibilities exist for tim in g p roblem s am on g ad ap ter card s p lu gged in to th e bu s. MCA system s p rod u ced a n ew level of ease of u se, as an yon e wh o h as set u p on e of th ese system s can tell you . An MCA system h as n o ju m p ers an d switch es—n eith er on th e m oth erboard n or on an y exp an sion ad ap ter. You d on ’t n eed an electrical en gin eerin g d egree to p lu g a card in to a PC. Th e MCA bu s also su p p orts bu s m asterin g. Th rou gh im p lem en tin g bu s m asterin g, th e MCA bu s p rovid es sign ifican t p erform an ce im p rovem en ts over th e old er ISA bu ses. (Bu s m asterin g is also im p lem en ted in th e EISA bu s.) In th e MCA bu s m asterin g im p lem en tation , an y bu s m asterin g d evices can req u est u n obstru cted u se of th e bu s in ord er to com m u n icate with an oth er d evice on th e bu s. Th e req u est is m ad e th rou gh a d evice kn own as th e Central Arbitration Control Point (CACP). Th is d evice arbitrates th e com p etition for th e bu s, m akin g su re all d evices h ave access an d th at n o sin gle d evice m on op olizes th e bu s. Each d evice is given a p riority cod e to en su re th at ord er is p reserved with in th e system . Th e m ain CPU is given th e lowest p riority cod e. Mem ory refresh h as th e h igh est p riority, followed by th e DMA ch an n els, an d th en th e bu s m asters in stalled in th e I/ O slots. On e excep tion to th is is wh en an NMI (n on m askable in terru p t) occu rs. In th is in stan ce, con trol retu rn s to th e CPU im m ed iately. Th e MCA sp ecification p rovid es for fou r ad ap ter sizes, wh ich are d escribed in Table 4.27. ◊◊ See “ DM A Transfer M odes,” p. 624

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Table 4.27

Physical Sizes of M CA Adapt er Cards

Adapt er Type

Height ( in Inches)

Lengt h ( in Inches)

Type 3

3.475

12.3

Type 3 half

3.475

6.35

Type 5

4.825

13.1

Type 9

9.0

13.1

Fou r typ es of slots are in volved in th e MCA d esign : ■ 16-bit ■ 16-bit with vid eo exten sion s ■ 16-bit with m em ory-m atch ed exten sion s ■ 32-bit Th e sixth ed ition of th is book, in clu d ed on th e CD-ROM, h as d etailed in form ation abou t each of th ese card s an d wh at system s th ey can be fou n d in . IBM still h as all of th e tech n ical referen ce m an u als for MCA available; h owever, d evelop m en t h as stop p ed for MCA d evices d u e to th e oth er faster an d m ore featu re-rich bu ses available tod ay. The EISA Bus EISA (Extended Industry Standard Architecture) is a stan d ard an n ou n ced in Sep tem ber 1988 as a resp on se to IBM’s in trod u ction of th e MCA bu s—m ore sp ecifically, to th e way th at IBM wan ted to h an d le licen sin g of th e MCA bu s. Ven d ors d id n ot feel obligated to p ay retroactive royalties on th e ISA bu s, so th ey tu rn ed th eir backs on IBM an d created th eir own bu ses. Th e EISA stan d ard was d evelop ed p rim arily by Com p aq , an d was in ten d ed as bein g th eir way of takin g over fu tu re d evelop m en t of th e PC bu s away from IBM. Com p aq kn ew th at n obod y wou ld clon e th eir bu s if th ey were th e on ly com p an y th at h ad it, so th ey essen tially gave th e d esign away to oth er lead in g m an u factu rers. Th ey form ed th e EISA com m ittee, a n on p rofit organ ization d esign ed sp ecifically to con trol d evelop m en t of th e EISA bu s. Very few EISA ad ap ters were ever d evelop ed . Th ose th at were d evelop ed cen tered m ain ly arou n d d isk array con trollers an d server-typ e n etwork card s. Th e EISA bu s p rovid es 32-bit slots for u se with 386DX or h igh er system s. Th e EISA slot en ables m an u factu rers to d esign ad ap ter card s th at h ave m an y of th e cap abilities of MCA ad ap ters, bu t th e bu s also su p p orts ad ap ter card s created for th e old er ISA stan d ard . EISA p rovid es m arked ly faster h ard d rive th rou gh p u t wh en u sed with d evices su ch as SCSI bu s-m asterin g h ard d rive con trollers. Com p ared with 16-bit ISA system arch itectu re, EISA p erm its greater system exp an sion with fewer ad ap ter con flicts. Th e EISA bu s ad d s 90 n ew con n ection s (55 n ew sign als) with ou t in creasin g th e p h ysical con n ector size of th e 16-bit ISA bu s. At first glan ce, th e 32-bit EISA slot looks m u ch like

Types of I/ O Buses

th e 16-bit ISA slot. Th e EISA ad ap ter, h owever, h as two rows of con n ectors. Th e first row is th e sam e kin d u sed in 16-bit ISA card s; th e oth er, th in n er row exten d s from th e 16-bit con n ectors. Th is m ean s th at ISA card s can still be u sed in EISA bu s slots. Alth ou gh th is com p atibility was n ot en ou gh to en su re th e p op u larity of EISA bu ses, it is a featu re th at was carried over in to th e n ewer VL-bu s stan d ard . Th e p h ysical sp ecification s of an EISA card are as follows: 5 in ch es (127m m ) h igh 13.13 in ch es (333.5m m ) lon g 0.5 in ch (12.7m m ) wid e Th e EISA bu s can h an d le u p to 32 bits of d ata at an 8.33MHz cycle rate. Most d ata tran sfers req u ire a m in im u m of two cycles, alth ou gh faster cycle rates are p ossible if an ad ap ter card p rovid es tigh t tim in g sp ecification s. Th e m axim u m ban d wid th on th e bu s is 33M/ sec, as th e followin g form u la sh ows: 8.33MHz×32 bits = 266.56Mbit/ sec 266.56Mbit/ sec÷8 = 33.32M/ sec Data tran sfers th rou gh an 8- or 16-bit exp an sion card across th e bu s wou ld be red u ced ap p rop riately. Rem em ber, h owever, th at th ese figu res rep resen t th eoretical m axim u m s. W ait states, in terru p ts, an d oth er p rotocol factors can red u ce th e effective ban d wid th — typ ically, by h alf. Figu re 4.18 d escribes th e p in ou ts for th e EISA bu s. Figu re 4.19 sh ows th e location s of th e p in s. Aut om at ed Set up. EISA system s also u se an au tom ated setu p to d eal with ad ap ter-board in terru p ts an d ad d ressin g issu es. Th ese issu es often cau se p roblem s wh en several d ifferen t ad ap ter board s are in stalled in an ISA system . EISA setu p software recogn izes p oten tial con flicts an d au tom atically con figu res th e system to avoid th em . EISA d oes, h owever, en able you to d o you r own trou blesh ootin g, an d to con figu re th e board s th rou gh ju m p ers an d switch es. Th is con cep t was n ot n ew to EISA; IBM’s MCA bu s also su p p orted con figu ration via software. An oth er n ew featu re of EISA system s is IRQ sh arin g, m ean in g th at m u ltip le bu s card s can sh are a sin gle in terru p t. Th is featu re h as also been im p lem en ted in PCI bu s card s.

Not e Although automated setup traditionally has not been available in ISA systems, it is now available with Plug-and-Play (PnP) systems and components. PnP systems are discussed toward the end of this chapter in the section titled “ Plug-and-Play Systems.”

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Chapter 4—M otherboards and Buses

Upper Signal

Lower Signal

Upper Signal

Pin

Pin

Ground +5 Vdc +5 Vdc Reserved Reserved KEY Reserved Reserved +12 Vdc M-IO -LOCK Reserved Ground Reserved -BE 3 KEY -BE 2 -BE 0 Ground +5 Vdc Latch Address 29 Ground Latch Address 26 Latch Address 24 KEY Latch Address 16 Latch Address 14 +5 Vdc +5 Vdc Ground Latch Address 10

Ground RESET DRV +5 Vdc IRQ 9 -5 Vdc DRQ 2 -12 Vdc -0 WAIT +12 Vdc Ground -SMEMW -SMEMR -IOW -IOR -DACK 3 DRQ 3 -DACK 1 DRQ 1 -Refresh CLK(8.33MHz) IRQ 7 IRQ 6 IRQ 5 IRQ 4 IRQ 3 -DACK 2 T/C BALE +5 Vdc OSC(14.3MHz) Ground

B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B12 B13 B14 B15 B16 B17 B18 B19 B20 B21 B22 B23 B24 B25 B26 B27 B28 B29 B30 B31

A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 A21 A22 A23 A24 A25 A26 A27 A28 A29 A30 A31

-I/O CH CHK Data Bit 7 Data Bit 6 Data Bit 5 Data Bit 4 Data Bit 3 Data Bit 2 Data Bit 1 Data Bit 0 -I/O CH RDY AEN Address 19 Address 18 Address 17 Address 16 Address 15 Address 14 Address 13 Address 12 Address 11 Address 10 Address 9 Address 8 Address 7 Address 6 Address 5 Address 4 Address 3 Address 2 Address 1 Address 0

Latch Address 8 Latch Address 6 Latch Address 5 +5 Vdc Latch Address 4 KEY Data Bit 16 Data Bit 18 Ground Data Bit 21 Data Bit 23 Data Bit 24 Ground Data Bit 27 KEY Data Bit 29 +5 Vdc +5 Vdc -MAKx

-MEM CS16 -I/O CS16 IRQ 10 IRQ 11 IRQ 12 IRQ 15 IRQ 14 -DACK 0 DRQ 0 -DACK 5 DRQ5 -DACK 6 DRQ 6 -DACK 7 DRQ 7 +5 Vdc -Master Ground

D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15 D16 D17 D18 D19

C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19

-SBHE Latch Address 23 Latch Address 22 Latch Address 21 Latch Address 20 Latch Address 19 Latch Address 18 Latch Address 17 -MEMR -MEMW Data Bit 8 Data Bit 9 Data Bit 10 Data Bit 11 Data Bit 12 Data Bit 13 Data Bit 14 Data Bit 15

FIG. 4.18 Pin ou ts for th e EISA bu s.

Lower Signal -CMD -START EXRDY -EX32 Ground KEY -EX16 -SLBURST -MSBURST W-R Ground Reserved Reserved Reserved Ground KEY -BE 1 Latch Address 31 Ground -Latch Address 30 -Latch Address 28 -Latch Address 27 -Latch Address 25 Ground KEY Latch Address 15 Latch Address 13 Latch Address 12 Latch Address 11 Ground Latch Address 9

Latch Address 7 Ground Latch Address 4 Latch Address 3 Ground KEY Data Bit 17 Data Bit 19 Data Bit 20 Data Bit 22 Ground Data Bit 25 Data Bit 26 Data Bit 28 KEY Ground Data Bit 30 Data Bit 31 -MREQx

Types of I/ O Buses

1 2 3 4 5

F

E

1

1

2

2

3

3

4

4

5

5

10 11 12 13 14 15

7

7

8

8

9

9

10

10

11

11

12

12

13

13

14

14

15

15

17

17

18 19 20 21 22 23 24

4 5

18

18

19

19

20

20

8 9 10 11 12 13 14 15 16

16 17

3

7

7

9

2

6

6

8

A 1

21

21

22

22

23

23

24

24

17 18 19 20 21 22 23 24

25

25

26

26

27 28 29 30 31

26

26

27

27

28

28

29

29

30

30

31

31

1 2 3 4 5

8 9 10 11 12 13 14

2 3 4

2 3 4 5

6

17 18 19

H

28 29 30 31

7 8 9 10 11 12 13

15 16 17 18

D

1 2 3 4 5

7 8 9 10 11 12 13 14

14 16

27

1 1

5 7

Rear of computer

B

6 7 8 9 10 11 12 13 14

16 17 18 19

G

15 16 17 18

C

FIG. 4.19 Th e card con n ector for th e EISA bu s.

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Local Buses Th e I/ O bu ses d iscu ssed so far (ISA, MCA, an d EISA) h ave on e th in g in com m on —relatively slow sp eed . Th e th ree n ewer bu s typ es th at we will look at in th e followin g few section s all u se th e local bus con cep t exp lain ed in th is section to ad d ress th e sp eed issu e. Th e th ree m ain local bu ses fou n d in PC system s are ■ VL-Bu s (VESA Local Bu s) ■ PCI (Perip h eral Com p on en t In tercon n ect) ■ AGP (Accelerated Grap h ics Port) Th e sp eed lim itation of ISA, MCA, an d EISA is a carryover from th e d ays of th e origin al PC, wh en th e I/ O bu s op erated at th e sam e sp eed as th e p rocessor bu s. As th e sp eed of th e p rocessor bu s in creased , th e I/ O bu s realized on ly n om in al sp eed im p rovem en ts, p rim arily from an in crease in th e ban d wid th of th e bu s. Th e I/ O bu s h ad to rem ain at a slower sp eed , becau se th e h u ge in stalled base of ad ap ter card s cou ld op erate on ly at slower sp eed s. Figu re 4.20 sh ows a con cep tu al block d iagram of th e bu ses in a com p u ter system .

CPU

External Cache

Processor Bus (High Speed)

Built-In I/O

I/O Bus (Slow Speed)

Bus Controller Chips

I/O Bus

Slotted I/O

(Slow Speed)

Memory Bus (High Speed)

RAM

FIG. 4.20 Bu s layou t in a trad ition al PC. Th e th ou gh t of a com p u ter system ru n n in g slower th an it cou ld both ers som e com p u ter u sers. Even so, th e slow sp eed of th e I/ O bu s is n oth in g m ore th an a n u isan ce in m ost cases. You d on ’t n eed blazin g sp eed to com m u n icate with a keyboard or a m ou se becau se you gain n oth in g in p erform an ce. Th e real p roblem occu rs in su bsystem s in wh ich you n eed th e sp eed , su ch as vid eo an d d isk con trollers.

Types of I/ O Buses

Th e sp eed p roblem becam e acu te wh en grap h ical u ser in terfaces (su ch as W in d ows) becam e p revalen t. Th ese system s req u ired th e p rocessin g of so m u ch vid eo d ata th at th e I/ O bu s becam e a bottlen eck for th e en tire com p u ter system . In oth er word s, it d id little good to h ave a p rocessor th at was cap able of 66MHz to 450MHz or faster if you cou ld p u t d ata th rou gh th e I/ O bu s at a rate of on ly 8MHz. An obviou s solu tion to th is p roblem is to m ove som e of th e slotted I/ O to an area wh ere it cou ld access th e faster sp eed s of th e p rocessor bu s—m u ch th e sam e way as th e extern al cach e. Figu re 4.21 sh ows th is arran gem en t.

CPU

External Cache

Processor Bus (High Speed)

Slotted I/O

Built-In I/O

I/O Bus (Slow Speed)

Bus Controller Chips

I/O Bus

Slotted I/O

(Slow Speed)

Memory Bus (High Speed)

RAM

FIG. 4.21 How a local bu s works. Th is arran gem en t becam e kn own as local bus, becau se extern al d evices (ad ap ter card s) n ow cou ld access th e p art of th e bu s th at was local to th e CPU—th e p rocessor bu s. Ph ysically, th e slots p rovid ed to tap th is n ew con figu ration wou ld n eed to be d ifferen t from existin g bu s slots, to p reven t ad ap ter card s d esign ed for slower bu ses from bein g p lu gged in to th e h igh er bu s sp eed s th at th is d esign m ad e accessible. It is in terestin g to n ote th at th e very first 8-bit an d 16-bit ISA bu ses were a form of Local Bu s arch itectu re. Th ese system s h ad th e p rocessor bu s as th e m ain bu s, an d everyth in g ran at fu ll p rocessor sp eed s. W h en ISA system s ran faster th an 8MHz, th e m ain ISA bu s h ad to be d ecou p led from th e p rocessor bu s becau se exp an sion card s, m em ory, an d so on cou ld n ot keep u p . In 1992, an exten sion to th e ISA bu s called th e V ESA Local Bus (VL-Bu s) started sh owin g u p on PC system s, in d icatin g a retu rn to Local Bu s arch itectu re. Sin ce th en , th e Peripheral Com ponent Interconnect (PCI) local bu s h as su p p lan ted VL-Bu s an d th e Accelerated Grap h ics Port (AGP) bu s h as been in trod u ced to com p lem en t PCI.

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Not e A system does not have to have a local-bus expansion slot to incorporate local-bus technology; instead, the local-bus device can be built directly into the motherboard. (In such a case, the localbus-slotted I/ O shown in Figure 4.21 would be built-in I/ O.) This built-in approach to local bus is the way the first local-bus systems were designed.

Local-bu s solu tion s d o n ot rep lace earlier stan d ard s, su ch as ISA; th ey are d esign ed in to th e system as a bu s th at is closer to th e p rocessor in th e system arch itectu re. Old er bu ses su ch as ISA h ave been kep t arou n d for backward com p atibility with slower typ es of ad ap ters th at d on ’t n eed an y faster con n ection to th e system (su ch as m od em s). Th erefore, a typ ical system will h ave AGP, PCI, an d ISA slots. Old er card s still are com p atible with th e system , bu t h igh -sp eed ad ap ter card s can take ad van tage of th e AGP an d PCI local-bu s slots, as well. Th e p erform an ce of grap h ical u ser in terfaces su ch as W in d ows an d OS/ 2 h ave been trem en d ou sly im p roved by m ovin g th e vid eo card s off of th e slow ISA bu s an d on to faster PCI an d n ow AGP local bu ses. VESA Local Bus Th e VESA Local Bu s was th e m ost p op u lar local bu s d esign from its d ebu t in Au gu st 1992 th rou gh 1994. It was created by th e VESA com m ittee, a n on p rofit organ ization fou n d ed by NEC to fu rth er d evelop vid eo d isp lay an d bu s stan d ard s. In a sim ilar fash ion to h ow EISA evolved , NEC h ad d on e m ost of th e work on th e VL-bu s (as it wou ld be called ), an d after fou n d in g th e n on p rofit VESA com m ittee, th ey tu rn ed over fu tu re d evelop m en t to VESA. At first, th e local-bu s slot seem ed p rim arily d esign ed to be u sed for vid eo card s. Im p rovin g vid eo p erform an ce was a top p riority at NEC to h elp sell th eir h igh -en d d isp lays an d th eir own PC system s. By 1991, vid eo p erform an ce h ad becom e a real bottlen eck in m ost PC system s. Th e V ideo Electronics Standards Association (V ESA) d evelop ed a stan d ard ized local-bu s sp ecification kn own as V ESA Local Bus or sim p ly V L-Bus. As in earlier local-bu s im p lem en tation s, th e VL-Bu s slot offers d irect access to system m em ory at th e sp eed of th e p rocessor. Th e VL-Bu s can m ove d ata 32 bits at a tim e, en ablin g d ata to flow between th e CPU an d a com p atible vid eo su bsystem or h ard d rive at th e fu ll 32-bit d ata wid th of th e 486 ch ip . Th e m axim u m rated th rou gh p u t of th e VL-Bu s is 128M to 132M/ sec. In oth er word s, local bu s wen t a lon g way toward rem ovin g th e m ajor bottlen ecks th at existed in earlier bu s con figu ration s. Ad d ition ally, VL-Bu s offers m an u factu rers of h ard -d rive in terface card s an op p ortu n ity to overcom e an oth er trad ition al bottlen eck—th e rate at wh ich d ata can flow between th e h ard d rive an d th e CPU. Th e average 16-bit IDE d rive an d in terface can ach ieve th rou gh p u t of u p to 5M/ sec, wh ereas VL-Bu s h ard d rive ad ap ters for IDE d rives are tou ted as p rovid in g th rou gh p u t of as m u ch as 8M/ sec. In real-world situ ation s, th e tru e th rou gh p u t of VL-Bu s h ard d rive ad ap ters is som ewh at less th an 8M/ sec, bu t VL-Bu s still p rovid es a su bstan tial boost in h ard -d rive p erform an ce.

Types of I/ O Buses

Desp ite all th e ben efits of th e VL-Bu s (an d , by exten sion , of all local bu ses), th is tech n ology h as are a few d rawbacks, wh ich are d escribed in th e followin g list: ■ Dependence on a 486 CPU. Th e VL-Bu s in h eren tly is tied to th e 486 p rocessor bu s. Th is bu s is q u ite d ifferen t from th at u sed by Pen tiu m an d later p rocessors. A VL-Bu s th at op erates at th e fu ll-rated sp eed of a Pen tiu m h as n ot been d evelop ed , alth ou gh stop gap m easu res (su ch as step p in g d own sp eed or d evelop in g bu s brid ges) are available. Un fortu n ately, th ese resu lt in p oor p erform an ce. Som e system s h ave been d evelop ed with both VL-Bu s an d PCI slots, bu t becau se of d esign com p rom ises, p erform an ce often su ffers. ■ Speed lim itations. Th e VL-Bu s sp ecification p rovid es for sp eed s of u p to 66MHz on th e bu s, bu t th e electrical ch aracteristics of th e VL-Bu s con n ector lim it an ad ap ter card to n o m ore th an 40 to 50MHz. In p ractice, ru n n in g th e VL-Bu s at sp eed s over 33MHz cau ses m an y p roblem s, so 33MHz h as becom e th e accep table sp eed lim it. System s th at u se faster p rocessor bu s sp eed s m u st bu ffer an d step d own th e clock on th e VL-Bu s or ad d wait states. Note th at if th e m ain CPU u ses a clock m od ifier (su ch as th e kin d th at d ou bles clock sp eed s), th e VL-Bu s u ses th e u n m od ified CPU clock sp eed as its bu s sp eed . ■ Electrical lim itations. Th e p rocessor bu s h as very tigh t tim in g ru les, wh ich m ay vary from CPU to CPU. Th ese tim in g ru les were d esign ed for lim ited load in g on th e bu s, m ean in g th at th e on ly elem en ts origin ally in ten d ed to be con n ected to th e local bu s are elem en ts su ch as th e extern al cach e an d th e bu s con troller ch ip s. As you ad d m ore circu itry, you in crease th e electrical load . If th e local bu s is n ot im p lem en ted correctly, th e ad d ition al load can lead to p roblem s su ch as loss of d ata in tegrity an d tim in g p roblem s between th e CPU an d th e VL-Bu s card s. ■ Card lim itations. Dep en d in g on th e electrical load in g of a system , th e n u m ber of VL-Bu s card s is lim ited . Alth ou gh th e VL-Bu s sp ecification p rovid es for as m an y as th ree card s, th is can be ach ieved on ly at clock rates of u p to 40MHz with an oth erwise low system -board load . As th e system -board load in creases an d th e clock rate in creases, th e n u m ber of card s su p p orted d ecreases. On ly on e VL-Bu s card can be su p p orted at 50MHz with a h igh system -board load . In p ractice, th ese lim its can n ot u su ally be reach ed with ou t p roblem s. Th e VL-Bu s d id n ot seem to be a well-en gin eered con cep t. Th e d esign was sim p le in d eed —ju st take th e p in s from th e 486 p rocessor an d ru n th em ou t to a card con n ector socket. In oth er word s, th e VL-Bu s is essen tially th e raw 486 p rocessor bu s. Th is allowed a very in exp en sive d esign , becau se n o ad d ition al ch ip sets or in terface ch ip s were req u ired . A m oth erboard d esign er cou ld ad d VL-Bu s slots to th eir 486 m oth erboard s very easily an d at a very low cost. Th is is wh y th ese slots ap p eared on virtu ally all 486 system d esign s overn igh t. Un fortu n ately, th e 486 p rocessor bu s was n ot d esign ed to h ave m u ltip le d evices (called loads) p lu gged in to it at on e tim e. Problem s arose with tim in g glitch es cau sed by th e cap acitan ce in trod u ced in to th e circu it by d ifferen t card s. Becau se th e VL-Bu s ran at th e sam e sp eed as th e p rocessor bu s, d ifferen t p rocessor sp eed s m ean t d ifferen t bu s sp eed s an d fu ll com p atibility was d ifficu lt to ach ieve. Alth ou gh th e VL-Bu s cou ld be ad ap ted to

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oth er p rocessors, in clu d in g th e 386 or even th e Pen tiu m , it was d esign ed for th e 486, an d worked best as a 486 solu tion on ly. Desp ite th e low cost, after a n ew bu s called PCI (Peripheral Com ponent Interconnect) ap p eared , VL-Bu s fell in to d isfavor very q u ickly. It n ever d id catch on with Pen tiu m system s, an d th ere is little or n o fu rth er d evelop m en t of th e VL-Bu s in th e PC in d u stry. I wou ld n ot recom m en d p u rch asin g VL-Bu s card s or system s tod ay. For a u sed system , or as an in exp en sive u p grad e for an old er system , VL-Bu s m igh t be ap p rop riate an d can p rovid e an accep table solu tion for h igh -sp eed com p u tin g. Ph ysically, th e VL-Bu s slot is an exten sion of th e slots u sed for wh atever typ e of base system you h ave. If you h ave an ISA system , th e VL-Bu s is p osition ed as an exten sion of you r existin g 16-bit ISA slots. Likewise, if you h ave an EISA system or MCA system , th e VL-Bu s slots are exten sion s of th ose existin g slots. Figu re 4.22 sh ows h ow th e VL-Bu s slots cou ld be situ ated in an ISA system . Th e VESA exten sion h as 112 con tacts an d u ses th e sam e p h ysical con n ector as th e MCA bu s.

Regular Slots

CPU VL-Bus Slots

FIG. 4.22 An exam p le of VL-Bu s slots in an ISA system .

Types of I/ O Buses

Th e VL-Bu s ad d s 116 p in location s to th e bu s con n ectors th at you r system alread y h as. Table 4.28 lists th e p in ou ts for on ly th e VL-Bu s con n ector p ortion of th e total con n ector. (For p in s for wh ich two p u rp oses are listed , th e secon d p u rp ose ap p lies wh en th e card is in 64-bit tran sfer m od e.) Table 4.28

Pinout s for t he VL-Bus

Pin

Signal Nam e

Pin

Signal Nam e

B1

Data 0

A1

Data 1

B2

Data 2

A2

Data 3

B3

Data 4

A3

Ground

B4

Data 6

A4

Data 5

B5

Data 8

A5

Data 7

B6

Ground

A6

Data 9

B7

Data 10

A7

Data 11

B8

Data 12

A8

Data 13

B9

VCC

A9

Data 15

B10

Data 14

A10

Ground

B11

Data 16

A11

Data 17

B12

Data 18

A12

VCC

B13

Data 20

A13

Data 19

B14

Ground

A14

Data 21

B15

Data 22

A15

Data 23

B16

Data 24

A16

Data 25

B17

Data 26

A17

Ground

B18

Data 28

A18

Data 27

B19

Data 30

A19

Data 29

B20

VCC

A20

Data 31

B21

Address 31 or Data 63

A21

Address 30 or Data 62

B22

Ground

A22

Address 28 or Data 60

B23

Address 29 or Data 61

A23

Address 26 or Data 58

B24

Address 27 or Data 59

A24

Ground

B25

Address 25 or Data 57

A25

Address 24 or Data 56

B26

Address 23 or Data 55

A26

Address 22 or Data 54

B27

Address 21 or Data 53

A27

VCC

B28

Address 19 or Data 51

A28

Address 20 or Data 52

B29

Ground

A29

Address 18 or Data 50

B30

Address 17 or Data 49

A30

Address 16 or Data 48

B31

Address 15 or Data 47

A31

Address 14 or Data 46

B32

VCC

A32

Address 12 or Data 44

B33

Address 13 or Data 45

A33

Address 10 or Data 42

B34

Address 11 or Data 43

A34

Address 8 or Data 40 (continues)

255

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Chapter 4—M otherboards and Buses

Table 4.28

Pinout s for t he VL-Bus Cont inued

Pin

Signal Nam e

Pin

Signal Nam e

B35

Address 9 or Data 41

A35

Ground

B36

Address 7 or Data 39

A36

Address 6 or Data 38

B37

Address 5 or Data 37

A37

Address 4 or Data 36

B38

Ground

A38

Write Back

B39

Address 3 or Data 35

A39

Byte Enable 0 or 4

B40

Address 2 or Data 34

A40

VCC

B41

Unused or LBS64#

A41

Byte Enable 1 or 5

B42

Reset

A42

Byte Enable 2 or 6

B43

Data/ Code Status

A43

Ground

B44

M emory-I/ O Status or Data 33

A44

Byte Enable 3 or 7

B45

Write/ Read Status or Data 32

A45

Address Data Strobe

B46

Access key

A46

Access key

B47

Access key

A47

Access key

B48

Ready Return

A48

Local Ready

B49

Ground

A49

Local Device

B50

IRQ 9

A50

Local Request

B51

Burst Ready

A51

Ground

B52

Burst Last

A52

Local Bus Grant

B53

ID0

A53

VCC

B54

ID1

A54

ID2

B55

Ground

A55

ID3

B56

Local Clock

A56

ID4 or ACK64#

B57

VCC

A57

Unused

B58

Local Bus Size 16

A58

Loc/ Ext Address Data Strobe

Figu re 4.23 sh ows th e location s of th e p in s.

B58

B48

B45

B1

A58

A48

A45

A1

Toward Main I/O Bus Connector

FIG. 4.23 Th e card con n ector for th e VL-Bu s. The PCI Bus In early 1992, In tel sp earh ead ed th e creation of an oth er in d u stry grou p . It was form ed with th e sam e goals as th e VESA grou p in relation to th e PC bu s. Recogn izin g th e n eed to overcom e weakn esses in th e ISA an d EISA bu ses, th e PCI Special Interest Group was form ed .

Types of I/ O Buses

Th e Peripheral Com ponent Interconnect (PCI) bu s sp ecification , released in Ju n e 1992 as version 1.0, was later u p d ated in Ap ril 1993 as version 2.0. Th e latest revision , version 2.1, ap p eared in early 1995. PCI red esign ed th e trad ition al PC bu s by in sertin g an oth er bu s between th e CPU an d th e n ative I/ O bu s by m ean s of brid ges. Rath er th an tap d irectly in to th e p rocessor bu s, with its d elicate electrical tim in g (as was d on e in th e VL-Bu s), a n ew set of con troller ch ip s was d evelop ed to exten d th e bu s, as sh own in Figu re 4.24.

Processor Cache Bridge/ Memory Controller

DRAM

Audio

Motion Video

PCI LOCAL BUS

LAN

SCSI

EXP Bus XFACE

Graphics

Base I/O Functions

ISA/EISA - Microchannel

FIG. 4.24 Con cep tu al d iagram of th e PCI bu s. Th e PCI bu s often is called a m ezzanine bus becau se it ad d s an oth er layer to th e trad ition al bu s con figu ration . PCI byp asses th e stan d ard I/ O bu s; it u ses th e system bu s to in crease th e bu s clock sp eed an d take fu ll ad van tage of th e CPU’s d ata p ath . System s th at in tegrate th e PCI bu s becam e available in m id -1993 an d h ave sin ce becom e th e m ain stay h igh -en d system s. In form ation is tran sferred across th e PCI bu s at 33MHz, at th e fu ll d ata wid th of th e CPU. W h en th e bu s is u sed in con ju n ction with a 32-bit CPU, th e ban d wid th is 132M p er secon d , as th e followin g form u la sh ows: 33MHz×32 bits = 1,056Mbit/ sec 1,056Mbit/ sec÷8 = 132M/ sec W h en th e bu s is u sed in fu tu re 64-bit im p lem en tation s, th e ban d wid th d ou bles, m ean in g th at you can tran sfer d ata at sp eed s u p to 264M/ sec. Real-life d ata tran sfer sp eed s n ecessarily will be lower, bu t still m u ch faster th an an yth in g else th at is cu rren tly available. Part of th e reason for th is faster real-life th rou gh p u t is th e fact th at th e PCI bu s can op erate con cu rren tly with th e p rocessor bu s; it d oes n ot su p p lan t it. Th e CPU can be p rocessin g d ata in an extern al cach e wh ile th e PCI bu s is bu sy tran sferrin g in form ation between oth er p arts of th e system —a m ajor d esign ben efit of th e PCI bu s.

257

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Chapter 4—M otherboards and Buses

A PCI ad ap ter card u ses its own u n iq u e con n ector. Th is con n ector can be id en tified with in a com p u ter system becau se it typ ically is offset from th e n orm al ISA, MCA, or EISA con n ectors (see Figu re 4.25). Th e size of a PCI card can be th e sam e as th at of th e card s u sed in th e system ’s n orm al I/ O bu s.

PCI Slots

ISA or EISA Slots

FIG. 4.25 Possible con figu ration of PCI slots in relation to ISA or EISA slots. Th e PCI sp ecification id en tifies th ree board con figu ration s, each d esign ed for a sp ecific typ e of system with sp ecific p ower req u irem en ts. Th e 5v sp ecification is for station ary com p u ter system s, th e 3.3v sp ecification is for p ortable m ach in es, an d th e u n iversal sp ecification is for m oth erboard s an d card s th at work in eith er typ e of system . Table 4.29 sh ows th e 5v PCI p in ou ts, an d Figu re 4.26 sh ows th e p in location s. Table 4.30 sh ows th e 3.3v PCI p in ou ts; th e p in location s are in d icated in Figu re 4.27. Fin ally, Table 4.31 sh ows th e p in ou ts, an d Figu re 4.28 sh ows th e p in location s for a u n iversal PCI slot an d card . Notice th at each figu re sh ows both th e 32-bit an d 64-bit variation s on th e resp ective sp ecification s.

Not e If the PCI card supports only 32 data bits, it needs only pins B1/ A1 through B62/ A62. Pins B63/ A63 through B94/ A94 are used only if the card supports 64 data bits.

Types of I/ O Buses

Table 4.29

Pinout s for a 5v PCI Bus

Pin

Signal Nam e

Pin

Signal Nam e

B1

–12v

A1

Test Reset

B2

Test Clock

A2

+12v

B3

Ground

A3

Test M ode Select

B4

Test Data Output

A4

Test Data Input

B5

+5v

A5

+5v

B6

+5v

A6

Interrupt A

B7

Interrupt B

A7

Interrupt C

B8

Interrupt D

A8

+5v

B9

PRSNT1#

A9

Reserved

B10

Reserved

A10

+5v I/ O

B11

PRSNT2#

A11

Reserved

B12

Ground

A12

Ground

B13

Ground

A13

Ground

B14

Reserved

A14

Reserved

B15

Ground

A15

Reset

B16

Clock

A16

+5v I/ O

B17

Ground

A17

Grant

B18

Request

A18

Ground

B19

+5v I/ O

A19

Reserved

B20

Address 31

A20

Address 30

B21

Address 29

A21

+3.3v

B22

Ground

A22

Address 28

B23

Address 27

A23

Address 26

B24

Address 25

A24

Ground

B25

+3.3v

A25

Address 24

B26

C/ BE 3

A26

Init Device Select

B27

Address 23

A27

+3.3v

B28

Ground

A28

Address 22

B29

Address 21

A29

Address 20

B30

Address 19

A30

Ground

B31

+3.3v

A31

Address 18

B32

Address 17

A32

Address 16

B33

C/ BE 2

A33

+3.3v

B34

Ground

A34

Cycle Frame

B35

Initiator Ready

A35

Ground

B36

+3.3v

A36

Target Ready

B37

Device Select

A37

Ground (continues)

259

260

Chapter 4—M otherboards and Buses

Table 4.29

Pinout s for a 5v PCI Bus Cont inued

Pin

Signal Nam e

Pin

Signal Nam e

B38

Ground

A38

Stop

B39

Lock

A39

+3.3v

B40

Parity Error

A40

Snoop Done

B41

+3.3v

A41

Snoop Backoff

B42

System Error

A42

Ground

B43

+3.3v

A43

PAR

B44

C/ BE 1

A44

Address 15

B45

Address 14

A45

+3.3v

B46

Ground

A46

Address 13

B47

Address 12

A47

Address 11

B48

Address 10

A48

Ground

B49

Ground

A49

Address 9

B50

Access key

A50

Access key

B51

Access key

A51

Access key

B52

Address 8

A52

C/ BE 0

B53

Address 7

A53

+3.3v

B54

+3.3v

A54

Address 6

B55

Address 5

A55

Address 4

B56

Address 3

A56

Ground

B57

Ground

A57

Address 2

B58

Address 1

A58

Address 0

B59

+5v I/ O

A59

+5v I/ O

B60

Acknowledge 64-bit

A60

Request 64-bit

B61

+5v

A61

+5v

B62

+5v Access key

A62

+5v Access key

B63

Reserved

A63

Ground

B64

Ground

A64

C/ BE 7

B65

C/ BE 6

A65

C/ BE 5

B66

C/ BE 4

A66

+5v I/ O

B67

Ground

A67

Parity 64-bit

B68

Address 63

A68

Address 62

B69

Address 61

A69

Ground

B70

+5v I/ O

A70

Address 60

B71

Address 59

A71

Address 58

B72

Address 57

A72

Ground

B73

Ground

A73

Address 56

Types of I/ O Buses

Pin

Signal Nam e

Pin

Signal Nam e

B74

Address 55

A74

Address 54

B75

Address 53

A75

+5v I/ O

B76

Ground

A76

Address 52

B77

Address 51

A77

Address 50

B78

Address 49

A78

Ground

B79

+5v I/ O

A79

Address 48

B80

Address 47

A80

Address 46

B81

Address 45

A81

Ground

B82

Ground

A82

Address 44

B83

Address 43

A83

Address 42

B84

Address 41

A84

+5v I/ O

B85

Ground

A85

Address 40

B86

Address 39

A86

Address 38

B87

Address 37

A87

Ground

B88

+5v I/ O

A88

Address 36

B89

Address 35

A89

Address 34

B90

Address 33

A90

Ground

B91

Ground

A91

Address 32

B92

Reserved

A92

Reserved

B93

Reserved

A93

Ground

B94

Ground

A94

Reserved

B1 A1

A52

A49

B52

A62

B49

B62

Rear of the Computer

32-bit Connector

A52

A1

B52

A62

B1

B62

A63

A49

B63

A94

B49

B94

64-bit Connector

FIG. 4.26 Th e 5v PCI slot an d card con figu ration .

Rear of the Computer

261

262

Chapter 4—M otherboards and Buses

Table 4.30

Pinout s for a 3.3v PCI Bus

Pin

Signal Nam e

Pin

Signal Nam e

B1

–12v

A1

Test Reset

B2

Test Clock

A2

+12v

B3

Ground

A3

Test M ode Select

B4

Test Data Output

A4

Test Data Input

B5

+5v

A5

+5v

B6

+5v

A6

Interrupt A

B7

Interrupt B

A7

Interrupt C

B8

Interrupt D

A8

+5v

B9

PRSNT1#

A9

Reserved

B10

Reserved

A10

+3.3v

B11

PRSNT2#

A11

Reserved

B12

Access key

A12

Access key

B13

Access key

A13

Access key

B14

Reserved

A14

Reserved

B15

Ground

A15

Reset

B16

Clock

A16

+3.3v

B17

Ground

A17

Grant

B18

Request

A18

Ground

B19

+3.3v

A19

Reserved

B20

Address 31

A20

Address 30

B21

Address 29

A21

+3.3v

B22

Ground

A22

Address 28

B23

Address 27

A23

Address 26

B24

Address 25

A24

Ground

B25

+3.3v

A25

Address 24

B26

C/ BE 3

A26

Init Device Select

B27

Address 23

A27

+3.3v

B28

Ground

A28

Address 22

B29

Address 21

A29

Address 20

B30

Address 19

A30

Ground

B31

+3.3v

A31

Address 18

B32

Address 17

A32

Address 16

B33

C/ BE 2

A33

+3.3v

B34

Ground

A34

Cycle Frame

B35

Initiator Ready

A35

Ground

B36

+3.3v

A36

Target Ready

B37

Device Select

A37

Ground

B38

Ground

A38

Stop

B39

Lock

A39

+3.3v

Types of I/ O Buses

Pin

Signal Nam e

Pin

Signal Nam e

B40

Parity Error

A40

Snoop Done

B41

+3.3v

A41

Snoop Backoff

B42

System Error

A42

Ground

B43

+3.3v

A43

PAR

B44

C/ BE 1

A44

Address 15

B45

Address 14

A45

+3.3v

B46

Ground

A46

Address 13

B47

Address 12

A47

Address 11

B48

Address 10

A48

Ground

B49

Ground

A49

Address 9

B50

Ground

A50

Ground

B51

Ground

A51

Ground

B52

Address 8

A52

C/ BE 0

B53

Address 7

A53

+3.3v

B54

+3.3v

A54

Address 6

B55

Address 5

A55

Address 4

B56

Address 3

A56

Ground

B57

Ground

A57

Address 2

B58

Address 1

A58

Address 0

B59

+3.3v

A59

+3.3v

B60

Acknowledge 64-bit

A60

Request 64-bit

B61

+5v

A61

+5v

B62

+5v Access key

A62

+5v Access key

B63

Reserved

A63

Ground

B64

Ground

A64

C/ BE 7

B65

C/ BE 6

A65

C/ BE 5

B66

C/ BE 4

A66

+3.3v

B67

Ground

A67

Parity 64-bit

B68

Address 63

A68

Address 62

B69

Address 61

A69

Ground

B70

+3.3v

A70

Address 60

B71

Address 59

A71

Address 58

B72

Address 57

A72

Ground

B73

Ground

A73

Address 56

B74

Address 55

A74

Address 54

B75

Address 53

A75

+3.3v

B76

Ground

A76

Address 52

B77

Address 51

A77

Address 50 (continues)

263

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Chapter 4—M otherboards and Buses

Table 4.30

Pinout s for a 3.3v PCI Bus Cont inued

Pin

Signal Nam e

Pin

Signal Nam e

B78

Address 49

A78

Ground

B79

+3.3v

A79

Address 48

B80

Address 47

A80

Address 46

B81

Address 45

A81

Ground

B82

Ground

A82

Address 44

B83

Address 43

A83

Address 42

B84

Address 41

A84

+3.3v

B85

Ground

A85

Address 40

B86

Address 39

A86

Address 38

B87

Address 37

A87

Ground

B88

+3.3v

A88

Address 36

B89

Address 35

A89

Address 34

B90

Address 33

A90

Ground

B91

Ground

A91

Address 32

B92

Reserved

A92

Reserved

B93

Reserved

A93

Ground

B94

Ground

A94

Reserved

A1

B11

B1

A11

A1

B1

A11

A14

B11

B14

A14

A62

B14

B62

Rear of the Computer

32-bit Connector

B94

B63

B62

A94

A63

A62

64-bit Connector

FIG. 4.27 Th e 3.3v PCI slot an d card con figu ration . Table 4.31

Pinout s for a Universal PCI Bus

Pin

Signal Nam e

Pin

Signal Nam e

B1

–12v

A1

Test Reset

B2

Test Clock

A2

+12v

B3

Ground

A3

Test M ode Select

B4

Test Data Output

A4

Test Data Input

B5

+5v

A5

+5v

Rear of the Computer

Types of I/ O Buses

Pin

Signal Nam e

Pin

Signal Nam e

B6

+5v

A6

Interrupt A

B7

Interrupt B

A7

Interrupt C

B8

Interrupt D

A8

+5v

B9

PRSNT1#

A9

Reserved

B10

Reserved

A10

+v I/ O

B11

PRSNT2#

A11

Reserved

B12

Access key

A12

Access key

B13

Access key

A13

Access key

B14

Reserved

A14

Reserved

B15

Ground

A15

Reset

B16

Clock

A16

+v I/ O

B17

Ground

A17

Grant

B18

Request

A18

Ground

B19

+v I/ O

A19

Reserved

B20

Address 31

A20

Address 30

B21

Address 29

A21

+3.3v

B22

Ground

A22

Address 28

B23

Address 27

A23

Address 26

B24

Address 25

A24

Ground

B25

+3.3v

A25

Address 24

B26

C/ BE 3

A26

Init Device Select

B27

Address 23

A27

+3.3v

B28

Ground

A28

Address 22

B29

Address 21

A29

Address 20

B30

Address 19

A30

Ground

B31

+3.3v

A31

Address 18

B32

Address 17

A32

Address 16

B33

C/ BE 2

A33

+3.3v

B34

Ground

A34

Cycle Frame

B35

Initiator Ready

A35

Ground

B36

+3.3v

A36

Target Ready

B37

Device Select

A37

Ground

B38

Ground

A38

Stop

B39

Lock

A39

+3.3v

B40

Parity Error

A40

Snoop Done

B41

+3.3v

A41

Snoop Backoff

B42

System Error

A42

Ground

B43

+3.3v

A43

PAR

B44

C/ BE 1

A44

Address 15 (continues)

265

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Chapter 4—M otherboards and Buses

Table 4.31

Pinout s for a Universal PCI Bus Cont inued

Pin

Signal Nam e

Pin

Signal Nam e

B45

Address 14

A45

+3.3v

B46

Ground

A46

Address 13

B47

Address 12

A47

Address 11

B48

Address 10

A48

Ground

B49

Ground

A49

Address 9

B50

Access key

A50

Access key

B51

Access key

A51

Access key

B52

Address 8

A52

C/ BE 0

B53

Address 7

A53

+3.3v

B54

+3.3v

A54

Address 6

B55

Address 5

A55

Address 4

B56

Address 3

A56

Ground

B57

Ground

A57

Address 2

B58

Address 1

A58

Address 0

B59

+5 I/ O

A59

+v I/ O

B60

Acknowledge 64-bit

A60

Request 64-bit

B61

+5v

A61

+5v

B62

+5v Access key

A62

+5v Access key

B63

Reserved

A63

Ground

B64

Ground

A64

C/ BE 7

B65

C/ BE 6

A65

C/ BE 5

B66

C/ BE 4

A66

+v I/ O

B67

Ground

A67

Parity 64-bit

B68

Address 63

A68

Address 62

B69

Address 61

A69

Ground

B70

+v I/ O

A70

Address 60

B71

Address 59

A71

Address 58

B72

Address 57

A72

Ground

B73

Ground

A73

Address 56

B74

Address 55

A74

Address 54

B75

Address 53

A75

+v I/ O

B76

Ground

A76

Address 52

B77

Address 51

A77

Address 50

B78

Address 49

A78

Ground

B79

+v I/ O

A79

Address 48

B80

Address 47

A80

Address 46

B81

Address 45

A81

Ground

B82

Ground

A82

Address 44

Types of I/ O Buses

Pin

Signal Nam e

Pin

Signal Nam e

B83

Address 43

A83

Address 42

B84

Address 41

A84

+v I/ O

B85

Ground

A85

Address 40

B86

Address 39

A86

Address 38

B87

Address 37

A87

Ground

B88

+v I/ O

A88

Address 36

B89

Address 35

A89

Address 34

B90

Address 33

A90

Ground

B91

Ground

A91

Address 32

B92

Reserved

A92

Reserved

B93

Reserved

A93

Ground

B94

Ground

A94

Reserved

A1

B11

B1

A11

A1

B1

A11

B11

A14

A49

B14

B49

A52

A14

B52

A62

B14

B62

Rear of the Computer

32-bit Connector

B94

B63

B62

B52

B49

A94

A63

A62

A52

A49

Rear of the Computer

64-bit Connector

FIG. 4.28 Th e u n iversal PCI slot an d card con figu ration . Notice th at th e u n iversal PCI board sp ecification s effectively com bin e th e 5v an d 3.3v sp ecification s. For p in s for wh ich th e voltage is d ifferen t, th e u n iversal sp ecification labels th e p in sim p ly V I/ O. Th is typ e of p in rep resen ts a sp ecial p ower p in for d efin in g an d d rivin g th e PCI sign alin g rail. An oth er im p ortan t featu re of PCI is th e fact th at it was th e m od el for th e In tel Pn P sp ecification . Th is m ean s th at PCI card s d o n ot h ave ju m p ers an d switch es, an d are in stead con figu red th rou gh software. Tru e Pn P system s are able to au tom atically con figu re th e ad ap ters, wh ile n on -Pn P system s with ISA slots h ave to con figu re th e ad ap ters th rou gh a p rogram th at is u su ally a p art of th e system CMOS con figu ration . Startin g in late 1995, m ost PC-com p atible system s h ave in clu d ed a Pn P BIOS th at allows th e au tom atic Pn P con figu ration . PCI Int errupt s. Th e PCM bu s su p p orts h ard ware in terru p ts, wh ich can be u sed by PCI d evices to sign al to th e bu s th at th ey n eed atten tion . Th ere are fou r PCI in terru p ts called INTA#, INTB#, INTC#, an d INTD#. Th ese INTx# in terru p ts are level-sen sitive, wh ich m ean s th at th e electrical sign alin g allows for th em to be sh ared am on g PCI card s. In fact,

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all sin gle d evice or sin gle fu n ction PCI ch ip s or card s th at u se on ly on e in terru p t m u st u se INTA#. Th is is on e of th e ru les in th e PCI sp ecification . If th ere are ad d ition al d evices with in a ch ip or on -board a card , th ese d evices m ay u se INTB# th rou gh INTD#. Becau se th ere are very few m u ltifu n ction PCI ch ip s or board s, th is m ean s th at p ractically all of th e d evices on a given PCI bu s will be sh arin g INTA#. For th e PCI bu s to fu n ction in a PC, th e PCI in terru p ts m u st be m ap p ed to ISA in terru p ts. Becau se ISA in terru p ts can n ot be sh ared , each PCI card th at is u sin g INTA# m u st be m ap p ed to a d ifferen t ISA in terru p t. For exam p le, you cou ld h ave a system with fou r PCI slots, an d fou r PCI card s in stalled each u sin g PCI in terru p t INTA#. Th ese card s wou ld each be m ap p ed to a d ifferen t ISA in terru p t req u est, su ch as IRQ9, IRQ10, IRQ11, an d IRQ5 in m ost cases. Th e m ap p in g of sp ecific PCI card s to ISA in terru p ts is som etim es referred to as PCI in terru p t “steerin g,” an d th is is con trolled by th e m oth erboard ch ip set. Som e system s en able you to m an u ally con trol th is m ap p in g via th e ad van ced ch ip set setu p rou tin es in th e BIOS Setu p . I h ave fou n d th is in terru p t m ap p in g to be th e sou rce of som e con fu sion am on g u sers. Even th ou gh PCI in terru p ts (INTx#) m ay in d eed be sh ared , becau se each card or d evice wh ich m igh t be sh arin g a PCI in terru p t m u st be m ap p ed to a u n iq u e ISA in terru p t wh ich in tu rn can n ot be sh ared . Th u s th e sh arin g cap abilities of th e PCI in terru p ts d o n oth in g for th e typ ical PC, wh ich is in d an ger of ru n n in g ou t of available ISA in terru p ts! An oth er sou rce of con fu sion is th e in terru p t listin g sh own in th e W in d ows d evice m an ager m ay sh ow th e PCI to ISA in terru p t m ap p in g as m u ltip le en tries for a given ISA in terru p t. On e en try wou ld be for th e d evice actu ally m ap p ed to th e in terru p t, for exam p le, a bu ilt-in USB con troller, wh ile th e oth er en try for th e sam e IRQ wou ld say “IRQ Hold er for PCI Steerin g.” Th is latter en try, even th ou gh claim in g to u se th e sam e IRQ, d oes n ot in d icate a resou rce con flict, in stead it rep resen ts th e ch ip set circu itry p u ttin g a reservation on th at in terru p t for m ap p in g p u rp oses. Th is is p art of th e p lu g-an d -p lay cap abilities of PCI an d th e m od ern m oth erboard ch ip sets. Note th at it is p ossible to h ave in tern al d evices on th e PCI bu s even th ou gh all of th e PCI slots are free. For exam p le m ost system s tod ay h ave two IDE con trollers an d a USB con troller as d evices on th e PCI bu s. Norm ally th e PCI IDE con trollers are m ap p ed to ISA in terru p ts 14 (p rim ary IDE) an d 15 (secon d ary IDE), wh ile th e USB con troller can be m ap p ed to th e n orm ally available ISA in terru p ts 9, 10, 11, or 5. ◊◊

See “ USB (Universal Serial Bus)” pg. 601

Th e PCI bu s allows two typ es of d evices to exist, called bu s m asters (in itiators) or slaves (targets). A bu s m aster is a d evice, wh ich can take con trol of th e bu s an d in itiate a tran sfer, wh ile th e target d evice is th e in ten d ed d estin ation of th e tran sfer. Most PCI d evices can act as both m asters an d targets, an d to be com p lian t with th e PC 97 an d n ewer system d esign gu id es, all PCI slots m u st su p p ort bu s m aster card s. Th e PCI bu s is an arbitrated bu s. Th is m ean s th at a cen tral arbiter (p art of th e PCI bu s con troller in th e m oth erboard ch ip set) govern s all bu s tran sfers, givin g fair an d con trolled access to all of th e d evices on th e bu s. Before a m aster can u se th e bu s, it m u st

System Resources

first req u est con trol from th e cen tral arbiter, an d th en it is on ly gran ted con trol for a sp ecified m axim u m n u m ber of cycles. Th is arbitration en ables eq u al an d fair access to all of th e bu s m aster d evices, as well as p reven ts a sin gle d evice from h oggin g th e bu s, an d also p reven ts d ead locks d u e to sim u ltan eou s m u ltip le d evice access. Accelerat ed Graphics Port ( AGP) In tel created Accelerated Graphics Port (AGP) as a n ew bu s sp ecifically d esign ed for h igh p erform an ce grap h ics an d vid eo su p p ort. AGP is based on PCI, bu t con tain s a n u m ber of ad d ition s an d en h an cem en ts, an d is p h ysically, electrically, an d logically in d ep en d en t of PCI. For exam p le, th e AGP con n ector is sim ilar to PCI alth ou gh it h as ad d ition al sign als an d is p osition ed d ifferen tly in th e system . Un like PCI, wh ich is a tru e bu s with m u ltip le con n ectors (slots), AGP is m ore of a p oin t to p oin t h igh -p erform an ce con n ection d esign ed sp ecifically for a vid eo card in a system , as on ly on e AGP slot is allowed for a sin gle vid eo card . Th e AGP sp ecification 1.0 was origin ally released by In tel in Ju ly 1996, an d d efin ed a 66MHz clock rate with 1X or 2X sign alin g u sin g 3.3 volts. AGP version 2.0 was released in May 1998, an d ad d ed 4X sign alin g as well as a lower 1.5v op eratin g cap ability. Th ere is also a n ew AGP Pro sp ecification th at d efin es a sligh tly lon ger slot with ad d ition al p ower p in s at each en d to d rive bigger an d faster AGP card s th at con su m e m ore th an 25 watts of p ower, u p to a m axim u m of 110 watts. AGP Pro card s wou ld likely be u sed for h igh -en d grap h ics workstation s. AGP Pro slots are backward com p atible, m ean in g stan d ard AGP card s will p lu g in . AGP is a h igh -sp eed con n ection , an d ru n s at a base freq u en cy of 66MHz (actu ally 66.66MHz), wh ich is d ou ble th at of stan d ard PCI. In th e basic AGP m od e called 1X, a sin gle tran sfer is d on e every cycle. Becau se th e AGP bu s is 32-bits (4-bytes) wid e, at 66 m illion tim es p er secon d it wou ld be cap able of tran sferrin g d ata at a rate of abou t 266 Million bytes p er secon d ! Th e origin al AGP sp ecification also d efin es a 2X m od e, wh ere two tran sfers are d on e every cycle, resu ltin g in 533 MB/ sec. Usin g an an alogy wh ere every cycle is eq u ivalen t to a d ru m beat, th e 1X m od e is th ou gh t of as tran sferrin g in form ation every tim e th e d ru m m er’s stick h its th e d ru m . In 2X m od e an ad d ition al tran sfer wou ld occu r every tim e th e stick was raised , th ereby d ou blin g p erform an ce wh ile tech n ically m ain tain in g th e sam e clock rate or in th is case th e sam e n u m ber of beats p er secon d . Th e n ewer AGP 2.0 sp ecification ad d s th e cap ability for 4X tran sfers, wh ich tran sfers d ata fou r tim es p er cycle an d eq u als a d ata tran sfer rate of 1,066 MB/ sec. Becau se AGP is in d ep en d en t of PCI, u sin g an AGP vid eo card will free u p th e PCI bu s for m ore trad ition al in p u t an d ou tp u t, su ch as for IDE/ ATA or SCSI con trollers, USB con trollers, sou n d card s, an d so on . Besid es faster vid eo p erform an ce, on e of th e m ain reason s In tel d esign ed AGP was to allow th e vid eo card to h ave a h igh -sp eed con n ection d irectly to th e system RAM. Th is allows an AGP vid eo card to h ave d irect access to th e system RAM, red u cin g th e n eed for m ore an d m ore vid eo m em ory. Th is is esp ecially im p ortan t as m em ory h u n gry 3D vid eo becom es m ore an d m ore p revalen t on PCs. AGP allows th e sp eed of th e vid eo card to p ace th e req u irem en ts for h igh -sp eed 3D grap h ics ren d erin g as well as fu ll m otion vid eo on th e PC in th e fu tu re.

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Syst em Resources System resou rces are th e com m u n ication s ch an n els, ad d resses, an d oth er sign als u sed by h ard ware d evices to com m u n icate on th e bu s. At th eir lowest level, th ese resou rces typ ically in clu d e th e followin g: ■ Mem ory ad d resses ■ IRQ (In terru p t Req u est) ch an n els ■ DMA (Direct Mem ory Access) ch an n els ■ I/ O Port ad d resses I h ave listed th ese rou gh ly in th e ord er you wou ld exp erien ce p roblem s with th em . Mem ory con flicts are p erh ap s th e m ost trou blesom e of th ese, certain ly th e m ost d ifficu lt to fu lly exp lain an d overcom e. Th ese are d iscu ssed in Ch ap ter 5, “Mem ory,” wh ich focu ses on th e oth ers listed h ere in th e ord er you will likely h ave p roblem s with th em . IRQs cau se m ore p roblem s th an DMA becau se th ey are in m u ch h igh er d em an d ; th erefore, virtu ally all card s will u se IRQ ch an n els. Th ere are fewer p roblem s with DMA ch an n els becau se few card s u se th em , an d th ere are u su ally m ore th an en ou gh ch an n els to go arou n d . I/ O p orts are u sed by all h ard ware d evices on th e bu s, bu t th ere are tech n ically 64K of th em , wh ich m ean s p len ty to go arou n d . W ith all of th ese resou rces, you h ave to m ake su re th at a u n iq u e card or h ard ware fu n ction u ses each resou rce; th ey can n ot or sh ou ld n ot be sh ared . Th ese resou rces are req u ired an d u sed by m an y d ifferen t com p on en ts of you r system . Ad ap ter card s n eed th ese resou rces to com m u n icate with you r system an d to p erform th eir fu n ction s. Not all ad ap ter card s h ave th e sam e resou rce req u irem en ts. A serial com m u n ication s p ort, for exam p le, n eed s an IRQ ch an n el an d I/ O p ort ad d ress; wh ereas a sou n d board n eed s th ese resou rces an d at least on e DMA ch an n el as well. Most n etwork card s u se a 16K block of m em ory ad d resses, an IRQ ch an n el, an d an I/ O p ort ad d ress. As you r system in creases in com p lexity, th e ch an ce for resou rce con flicts in creases d ram atically. Mod ern system s with sou n d card s an d n etwork card s can really p u sh th e en velop e an d can becom e a con figu ration n igh tm are for th e u n in itiated . So th at you can resolve con flicts, m ost ad ap ter card s allow you to m od ify resou rce assign m en ts by u sin g th e Plu g-an d -Play software th at com es with th e card or th e Device Man ager in W in d ows 95 an d later. Even if th e au tom atic con figu ration gets con fu sed (wh ich h ap p en s m ore often th an it sh ou ld ), fortu n ately in alm ost all cases th ere is a logical way to con figu re th e system —on ce you kn ow th e ru les. Int errupt s ( IRQs) Interrupt request channels (IRQs), or h ard ware in terru p ts, are u sed by variou s h ard ware d evices to sign al th e m oth erboard th at a req u est m u st be fu lfilled . Th is p roced u re is th e sam e as a stu d en t raisin g h is h an d to in d icate th at h e n eed s atten tion . Th ese in terru p t ch an n els are rep resen ted by wires on th e m oth erboard an d in th e slot con n ectors. W h en a p articu lar in terru p t is in voked , a sp ecial rou tin e takes over th e system , wh ich first saves all th e CPU register con ten ts in a stack an d th en d irects th e system

System Resources

to th e in terru p t vector table. Th is vector table con tain s a list of m em ory ad d resses th at corresp on d to th e in terru p t ch an n els. Dep en d in g on wh ich in terru p t was in voked , th e p rogram corresp on d in g to th at ch an n el is ru n . Th e p oin ters in th e vector table p oin t to th e ad d ress of wh atever software d river is u sed to service th e card th at gen erated th e in terru p t. For a n etwork card , for exam p le, th e vector m ay p oin t to th e ad d ress of th e n etwork d rivers th at h ave been load ed to op erate th e card ; for a h ard d isk con troller, th e vector m ay p oin t to th e BIOS cod e th at op erates th e con troller. After th e p articu lar software rou tin e fin ish es p erform in g wh atever fu n ction th e card n eed ed , th e in terru p t-con trol software retu rn s th e stack con ten ts to th e CPU registers, an d th e system th en resu m es wh atever it was d oin g before th e in terru p t occu rred . Th rou gh th e u se of in terru p ts, you r system can resp on d to extern al even ts in a tim ely fash ion . Each tim e th at a serial p ort p resen ts a byte to you r system , an in terru p t is gen erated to en su re th at th e system read s th at byte before an oth er com es in . Keep in m in d th at in som e cases a p ort d evice—in p articu lar, a m od em with a 16550 or h igh er UART ch ip —m ay in corp orate a byte bu ffer th at allows m u ltip le ch aracters to be stored before an in terru p t is gen erated . Hard ware in terru p ts are gen erally p rioritized by th eir n u m bers; with som e excep tion s, th e h igh est-p riority in terru p ts h ave th e lowest n u m bers. High er-p riority in terru p ts take p reced en ce over lower-p riority in terru p ts. As a resu lt, several in terru p ts can occu r in you r system con cu rren tly, each in terru p t n estin g with in an oth er. If you overload th e system —in th is case, by ru n n in g ou t of stack resou rces (too m an y in terru p ts were gen erated too q u ickly)—an in tern al stack overflow error occu rs an d you r system h alts. Th e m essage u su ally ap p ears as Internal stack overflow—system halted at a DOS p rom p t. If you exp erien ce th is typ e of system error an d ru n DOS, you can com p en sate for it by u sin g th e STACKS p aram eter in you r CONFIG.SYS file to in crease th e available stack resou rces. Most p eop le will n ot see th is error in W in d ows 95 or W in d ows NT. Th e ISA bu s u ses ed ge-triggered interrupt sensing, in wh ich an in terru p t is sen sed by a sign al sen t on a p articu lar wire located in th e slot con n ector. A d ifferen t wire corresp on d s to each p ossible h ard ware in terru p t. Becau se th e m oth erboard can n ot recogn ize wh ich slot con tain s th e card th at u sed an in terru p t lin e an d th erefore gen erated th e in terru p t, con fu sion wou ld resu lt if m ore th an on e card were set to u se a p articu lar in terru p t. Each in terru p t, th erefore, u su ally is d esign ated for a sin gle h ard ware d evice, an d m ost of th e tim e, in terru p ts can n ot be sh ared . A d evice can be d esign ed to sh are in terru p ts, an d a few d evices allow th is; m ost can n ot, h owever, becau se of th e way in terru p ts are sign aled in th e ISA bu s. Th e PCI bu s allows in terru p t sh arin g; in fact, virtu ally all PCI card s are set to PCI in terru p t A. Th e real p roblem is th at for th ese card s to work in you r system , th ey m u st be m ap p ed to ISA in terru p ts, wh ich are n on sh arable. Th at is wh y you r PCI card s still work th e sam e way as before as far as in terru p ts are con cern ed . Th at is, you will h ave to assign a n on con flictin g in terru p t for each card .

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Extern al h ard ware in terru p ts often are referred to as m askable interrupts, wh ich sim p ly m ean s th at th e in terru p ts can be m asked or tu rn ed off for a sh ort tim e wh ile th e CPU is u sed for oth er critical op eration s. It is u p to th e p rogram m er to m an age in terru p ts p rop erly an d efficien tly for th e best system p erform an ce. Becau se in terru p ts u su ally can n ot be sh ared in an ISA bu s system , you often ru n in to con flicts an d can even ru n ou t of in terru p ts wh en you are ad d in g board s to a system . If two board s u se th e sam e IRQ to sign al th e system , th e resu ltin g con flict p reven ts eith er board from op eratin g p rop erly. Th e followin g section s d iscu ss th e IRQs th at an y stan d ard d evices u se, an d wh at m ay be free in you r system . 8-Bit ISA Bus Int errupt s. Th e PC an d XT (th e system s based on th e 8-bit 8086 CPU) p rovid e for eigh t d ifferen t extern al h ard ware in terru p ts. Table 4.32 sh ows th e typ ical u ses for th ese in terru p ts, wh ich are n u m bered 0 th rou gh 7. Table 4.32

8-Bit ISA Bus Default Int errupt Assignm ent s

IRQ

Funct ion

Bus Slot

0

System Timer

No

1

Keyboard Controller

No

2

Available

Yes (8-bit)

3

Serial Port 2 (COM 2:)

Yes (8-bit)

4

Serial Port 1 (COM 1:)

Yes (8-bit)

5

Hard Disk Controller

Yes (8-bit)

6

Floppy Disk Controller

Yes (8-bit)

7

Parallel Port 1 (LPT1:)

Yes (8-bit)

If you r system h as on e of th e origin al 8-bit ISA bu ses, you will fin d th at th e IRQ resou rces p rovid ed by th e system p resen t a severe lim itation . In stallin g several d evices th at n eed th e services of system IRQs in a PC/ XT-typ e system can be a stu d y in fru stration , becau se th e on ly way to resolve th e in terru p t-sh ortage p roblem is to rem ove th e ad ap ter board th at you n eed th e least. 16-Bit ISA, EISA, and M CA Bus Int errupt s. Th e in trod u ction of th e AT, based on th e 286 p rocessor, was accom p an ied by an in crease in th e n u m ber of extern al h ard ware in terru p ts th at th e bu s wou ld su p p ort. Th e n u m ber of in terru p ts was d ou bled to 16 by u sin g two In tel 8259 in terru p t con trollers an d p ip in g th e in terru p ts gen erated by th e secon d on e th rou gh th e u n u sed IRQ 2 in th e first con troller. Th is arran gem en t effectively m ean s th at 15 IRQ assign m en ts are available, an d IRQ 2 is effectively in accessible. By rou tin g all of th e in terru p ts from th e secon d IRQ con troller th rou gh IRQ 2 on th e first, all of th ese n ew in terru p ts are assign ed a n ested p riority level between IRQ 1 an d IRQ 3. Th u s, IRQ 15 en d s u p h avin g a h igh er p riority th an IRQ 3. Figu re 4.29 sh ows h ow th e two 8259 ch ip s were wired to create th e cascad e th rou gh IRQ 2 on th e first ch ip . To p reven t p roblem s with board s set to u se IRQ 2, th e AT system d esign ers rou ted on e of th e n ew in terru p ts (IRQ 9) to fill th e slot p osition left op en after rem ovin g IRQ 2. Th is m ean s th at an y card you in stall in a m od ern system th at claim s to u se IRQ 2 is really

System Resources

u sin g IRQ 9 in stead . Som e card s n ow label th is selection as IRQ 2/ 9, wh ile oth ers m ay call it IRQ 2 or IRQ 9. No m atter wh at th e labelin g says, you m u st n ever assign two card s to u se th at in terru p t! From Timer Circuits From Keyboard Controller From FPU From RTC/CMOS

8259 PIC (#1)

To CPU

INT

0 1 2 3 4 5 6 7

IRQ 0 IRQ 1 8259 PIC (#2) IRQ IRQ IRQ IRQ IRQ

3 4 5 6 7

INT

From 8-bit slots

0 1 2 3 4 5 6 7

IRQ IRQ IRQ IRQ IRQ IRQ IRQ IRQ

8 9 10 11 12 13 14 15

From 16-bit slots From 8-bit slots (former IRQ 2 pin position)

FIG. 4.29 In terru p t con troller cascad e wirin g. Table 4.33 sh ows th e typ ical u ses for in terru p ts in th e 16-bit ISA, EISA, an d MCA bu ses an d lists th em in p riority ord er from h igh est to lowest. Table 4.33

16/ 32-Bit ISA/ PCI Default Int errupt Assignm ent s

IRQ

St andard Funct ion

Bus Slot

Card Type

Recom m ended Use

0

System Timer

No

-

-

1

Keyboard Controller

No

-

-

2

2nd IRQ Controller Cascade

No

-

-

8

Real-Time Clock

No

-

-

9

Available (Appears as IRQ 2)

Yes

8/ 16-bit

Network Interface Card

10

Available

Yes

16-bit

USB

11

Available

Yes

16-bit

SCSI Host Adapter

12

M otherboard M ouse Port/ Available

Yes

16-bit

M otherboard M ouse Port

13

M ath Coprocessor

No

-

-

14

Primary IDE

Yes

16-bit

Primary IDE (Hard disks)

Secondary IDE/ Available

Yes

16-bit

Secondary IDE (CDROM / Tape)

3

15

Serial Port 2 (COM 2:)

Yes

8/ 16-bit

COM 2:/ Internal M odem

4

Serial Port 1 (COM 1:)

Yes

8/ 16-bit

COM 1:

5

Sound/ Parallel Port 2 (LPT2:)

Yes

8/ 16-bit

Sound Card

6

Floppy Disk Controller

Yes

8/ 16-bit

Floppy Controller

7

Parallel Port 1 (LPT1:)

Yes

8/ 16-bit

LPT1:

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Notice th at in terru p ts 0, 1, 2, 8, an d 13 are n ot on th e bu s con n ectors an d are n ot accessible to ad ap ter card s. In terru p ts 8, 10, 11, 12, 13, 14, an d 15 are from th e secon d in terru p t con troller an d are accessible on ly by board s th at u se th e 16-bit exten sion con n ector, becau se th is is wh ere th ese wires are located . IRQ 9 is rewired to th e 8-bit slot con n ector in p lace of IRQ 2, wh ich m ean s th at IRQ 9 rep laces IRQ 2 an d th erefore is available to 8-bit card s, wh ich treat it as th ou gh it were IRQ 2.

Not e Although the 16-bit ISA bus has twice as many interrupts as systems that have the 8-bit ISA bus, you still may run out of available interrupts because only 16-bit adapters can use most of the newly available interrupts.

Th e extra IRQ lin es in a 16-bit ISA system are of little h elp u n less th e ad ap ter board s th at you p lan to u se en able you to con figu re th em for on e of th e u n u sed IRQs. Som e d evices are h ard -wired so th at th ey can u se on ly a p articu lar IRQ. If you h ave a d evice th at alread y u ses th at IRQ, you m u st resolve th e con flict before in stallin g th e secon d ad ap ter. If n eith er ad ap ter en ables you to recon figu re its IRQ u se, you p robably can n ot u se th e two d evices in th e sam e system . IRQ Conflict s. On e of th e m ost com m on areas of IRQ con flict in volves serial (COM) p orts. You m ay h ave n oticed in th e p reced in g two section s th at two IRQs are set asid e for two COM p orts. IRQ 3 is u sed for COM2:, an d IRQ 4 is u sed for COM1:. Th e p roblem occu rs wh en you h ave m ore th an two serial p orts in a system . Th e p roblem is th at wh en p eop le ad d COM3: an d COM4: p orts, th ey often d on ’t set th em to n on con flictin g in terru p ts, resu ltin g in a con flict an d n on fu n ction in g p orts. Con tribu tin g to th e p roblem are p oorly d esign ed COM p ort board s th at d o n ot allow IRQ settin gs oth er th an 3 or 4. W h at h ap p en s is th at th ey en d u p settin g COM3: to IRQ 4 (sh arin g it with COM1:), an d COM4: to IRQ 3 (sh arin g it with COM2:). Th is is n ot accep table, as it will p reven t you from u sin g th e two COM p orts on an y on e of th e in terru p t ch an n els sim u ltan eou sly. Th is was som ewh at accep table u n d er p lain DOS, becau se sin gle-taskin g (ru n n in g on ly on e p rogram at a tim e) was th e ord er of th e d ay, bu t is totally u n accep table with W in d ows an d OS/ 2. If you m u st sh are IRQs, you can u su ally get away with sh arin g d evices on th e sam e IRQ as lon g as th ey u se d ifferen t COM p orts. For in stan ce, a scan n er an d an in tern al m od em cou ld sh are an IRQ, alth ou gh if th e two d evices are u sed sim u ltan eou sly, a con flict will resu lt. Th e best solu tion is to p u rch ase a m u ltip ort serial I/ O card th at will allow n on con flictin g in terru p t settin gs, or an in telligen t card with its own p rocessor th at can h an d le th e m u ltip le p orts on board an d on ly u se on e in terru p t in th e system . ◊◊ See “ Serial Ports,” p. 583

If a d evice listed in th e table is n ot p resen t, su ch as th e m oth erboard m ou se p ort (IRQ 12) or p arallel p ort 2 (IRQ 5), th en you can con sid er th ose in terru p ts as available.

System Resources

For exam p le, a secon d p arallel p ort is a rarity, an d m ost system s will h ave a sou n d card in stalled an d set for IRQ 5. Also, on m ost system s IRQ 15 is assign ed to a secon d ary IDE con troller. If you d o n ot h ave a secon d IDE h ard d rive, you cou ld d isable th e secon d ary IDE con troller to free u p th at IRQ for an oth er d evice. Note th at an easy way to ch eck you r in terru p t settin gs is to u se th e Device Man ager in W in d ows 95/ 98 or NT 5.0 or later. By d ou ble-clickin g th e com p u ter p rop erties icon in th e Device Man ager, you can get con cise lists of all u sed system resou rces. Microsoft h as also in clu d ed a p rogram called HW DIAG on W in d ows 95B an d n ewer version s th at d oes an excellen t job of rep ortin g system resou rce u sage. DM A Channels DMA (Direct Mem ory Access) ch an n els are u sed by h igh -sp eed com m u n ication s d evices th at m u st sen d an d receive in form ation at h igh sp eed . A serial or p arallel p ort d oes n ot u se a DMA ch an n el, bu t a sou n d card or SCSI ad ap ter often d oes. DMA ch an n els som etim es can be sh ared if th e d evices are n ot of th e typ e th at wou ld n eed th em sim u ltan eou sly. For exam p le, you can h ave a n etwork ad ap ter an d a tap e backu p ad ap ter sh arin g DMA ch an n el 1, bu t you can n ot back u p wh ile th e n etwork is ru n n in g. To back u p d u rin g n etwork op eration , you m u st en su re th at each ad ap ter u ses a u n iq u e DMA ch an n el. 8-Bit ISA Bus DM A Channels. In th e 8-bit ISA bu s, fou r DMA ch an n els su p p ort h igh sp eed d ata tran sfers between I/ O d evices an d m em ory. Th ree of th e ch an n els are available to th e exp an sion slots. Table 4.34 sh ows th e typ ical u ses of th ese DMA ch an n els. Table 4.34

8-Bit ISA Default DM A-Channel Assignm ent s

DM A

St andard Funct ion

Bus Slot

0

Dynamic RAM Refresh

No

1

Available

Yes (8-bit)

2

Floppy disk controller

Yes (8-bit)

3

Hard disk controller

Yes (8-bit)

Becau se m ost system s typ ically h ave both a flop p y an d h ard d isk d rive, on ly on e DMA ch an n el is available in 8-bit ISA system s. 16-Bit ISA DM A Channels. Sin ce th e in trod u ction of th e 286 CPU, th e ISA bu s h as su p p orted eigh t DMA ch an n els, with seven ch an n els available to th e exp an sion slots. Like th e exp an d ed IRQ lin es d escribed earlier in th is ch ap ter, th e ad d ed DMA ch an n els were created by cascad in g a secon d DMA con troller to th e first on e. DMA ch an n el 4 is u sed to cascad e ch an n els 0 th rou gh 3 to th e m icrop rocessor. Ch an n els 0 th rou gh 3 are available for 8-bit tran sfers, an d ch an n els 5 th rou gh 7 are for 16-bit tran sfers on ly. Table 4.35 sh ows th e typ ical u ses for th e DMA ch an n els.

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Table 4.35

16/ 32-Bit ISA/ PCI Default DM A-Channel Assignm ent s

DM A

St andard Funct ion

Bus Slot

Card Type

Transfer

Recom m ended Use

0

Available

Yes

16-bit

8-bit

None

1

Available

Yes

8/ 16-bit

8-bit

8-bit Sound

2

Floppy Disk Controller

Yes

8/ 16-bit

8-bit

Floppy Controller

3

Available

Yes

8/ 16-bit

8-bit

LPT1: in ECP M ode

4

1st DM A Controller Cascade

No

-

16-bit

-

5

Available

Yes

16-bit

16-bit

16-bit Sound

6

Available

Yes

16-bit

16-bit

ISA SCSI Adapter

7

Available

Yes

16-bit

16-bit

Available

Th e on ly stan d ard DMA ch an n el u sed in all system s is DMA 2, wh ich is u n iversally u sed by th e flop p y con troller. DMA 4 is n ot u sable, an d d oes n ot ap p ear in th e bu s slots. DMA ch an n els 1 an d 5 are m ost com m on ly u sed by sou n d card s su ch as th e Sou n d Blaster 16. Th ese card s u se both an 8- an d a 16-bit DMA ch an n el for h igh -sp eed tran sfers.

Not e Although DM A channel 0 appears in a 16-bit slot connector extension and therefore can only be used by a 16-bit card, it only does 8-bit transfers! Because of this, you will generally not see DM A 0 as a choice on 16-bit cards. M ost 16-bit cards (such as SCSI host adapters) that use DM A channels have their choices limited to DM A 5 through 7.

EISA. Realizin g th e sh ortcom in gs in h eren t in th e way DMA ch an n els are im p lem en ted in th e ISA bu s, th e creators of th e EISA sp ecification created a sp ecific DMA con troller for th eir n ew bu s. Th ey in creased th e n u m ber of ad d ress lin es to in clu d e th e en tire ad d ress bu s, th u s allowin g tran sfers an ywh ere with in th e ad d ress sp ace of th e system . Each DMA ch an n el can be set to ru n eith er 8-, 16-, or 32-bit tran sfers. In ad d ition , each DMA ch an n el can be sep arately p rogram m ed to ru n an y of fou r typ es of bu s cycles wh en tran sferrin g d ata: ■ Com patible. Th is tran sfer m eth od is in clu d ed to m atch th e sam e DMA tim in g as u sed in th e ISA bu s. Th is is d on e for com p atibility reason s; all ISA card s can op erate in an EISA system in th is tran sfer m od e. ■ Type A. Th is tran sfer typ e com p resses th e DMA tim in g by 25 p ercen t over th e com p atible m eth od . It was d esign ed to ru n with m ost (bu t n ot all) ISA card s an d still yield a sp eed in crease. ■ Type B. Th is tran sfer typ e com p resses tim in g by 50 p ercen t over th e com p atible m eth od . Usin g th is m eth od , m ost EISA card s fu n ction p rop erly, bu t on ly a few ISA card s will be p roblem -free.

System Resources

■ Type C. Th is tran sfer m eth od com p resses tim in g by 87.5 p ercen t over th e com p atible m eth od ; it is th e fastest DMA tran sfer m eth od available u n d er th e EISA sp ecification . No ISA card s will work u sin g th is tran sfer m eth od . EISA DMA also allows for sp ecial read in g an d writin g op eration s referred to as scatter write an d gather read. Scattered writes are d on e by read in g a con tigu ou s block of d ata an d writin g it to m ore th an on e area of m em ory at th e sam e tim e. Gath ered read s in volve read in g from m ore th an on e p lace in m em ory an d writin g to a d evice. Th ese fu n ction s are often referred to as Buffered Chaining, an d th ey in crease th e th rou gh p u t of DMA op eration s. M CA. It m igh t be assu m ed th at becau se MCA is a com p lete rebu ild in g of th e PC bu s stru ctu re th at DMA in an MCA en viron m en t wou ld be better con stru cted . Th is is n ot so. Qu ite th e op p osite is tru e; DMA in MCA system s were for th e m ost p art all d esign ed arou n d on e DMA con troller with th e followin g issu es: ■ It can on ly con n ect to two 8-bit d ata p ath s. Th is can on ly tran sfer on e or two bytes p er bu s cycle. ■ It is on ly con n ected to AO:A23 on th e ad d ress bu s. Th is m ean s it can on ly m ake u se of th e lower 16M of m em ory. ■ Ru n s at 10MHz. Th e in ability of th e DMA con troller to ad d ress m ore th an two bytes p er tran sfer severely crip p les th is oth erwise p owerfu l bu s. I/ O Port Addresses You r com p u ter’s I/ O p orts en able com m u n ication s between d evices an d software in you r system . Th ey are eq u ivalen t to two-way rad io ch an n els. If you wan t to talk to you r serial p ort, th en you n eed to kn ow wh at I/ O p ort (rad io ch an n el) it is listen in g on . Sim ilarly, if you wan t to receive d ata from th e serial p ort, you n eed to listen on th e sam e ch an n el on wh ich it is tran sm ittin g. Un like IRQs an d DMA ch an n els, we h ave an abu n d an ce of I/ O p orts in ou r system s. Th ere are 65,535 p orts, to be exact (n u m bered from 0000h to FFFFh ), an d th is is an artifact of th e In tel p rocessor d esign m ore th an an yth in g else. Even th ou gh m ost d evices u se u p to eigh t p orts for th em selves, with th at m an y to sp are, we aren ’t goin g to ru n ou t an ytim e soon . Th e biggest p roblem you h ave to worry abou t is settin g two d evices to u se th e sam e p ort. Most m od ern Plu g-an d -Play system s will resolve an y p ort con flicts an d select altern ate p orts for on e of th e con flictin g d evices. On e con fu sin g issu e is th at I/ O p orts are d esign ated by h exad ecim al ad d resses sim ilar to m em ory ad d resses. Th ey are n ot m em ory; th ey are p orts. Th e d ifferen ce is th at wh en you sen d d ata to m em ory ad d ress 1000h , it gets stored in you r SIMM or DIMM m em ory. If you sen d d ata to I/ O p ort ad d ress 1000h , it gets sen t ou t on th e bu s on th at “ch an n el”

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an d an ybod y listen in g in wou ld th en “h ear” it. If n obod y was listen in g to th at p ort ad d ress, th en th e d ata wou ld reach th e en d of th e bu s an d be absorbed by th e bu s term in atin g resistors. Driver p rogram s are p rim arily wh at in teract with d evices at th e d ifferen t p ort ad d resses. Th e d river m u st kn ow wh ich p orts th e d evice is u sin g to work with it, an d vice versa. Th at is n ot u su ally a p roblem becau se th e d river an d d evice both com e from th e sam e com p an y. Moth erboard an d ch ip set d evices are n orm ally set to u se I/ O p ort ad d resses from 0h to FFh , an d all oth er d evices u se from 100h to FFFFh . Table 4.36 sh ows th e com m on ly u sed m oth erboard an d ch ip set based I/ O p ort u sage: Table 4.36

M ot herboard and Chipset -based Device Port Addresses

Address ( hex)

Size

Descript ion

000–000F

16 bytes

Chipset—8237 DM A 1

0020–0021

2 bytes

Chipset—8259 Interrupt Controller 1

002E–002F

2 bytes

Super I/ O Controller Configuration Registers

0040–0043

4 bytes

Chipset—Counter/ Timer 1

0048–004B

4 bytes

Chipset—Counter/ Timer 2

0060

1 byte

Keyboard/ M ouse Controller Byte—Reset IRQ

0061

1 byte

Chipset—NM I, Speaker Control

0064

1 byte

Keyboard/ M ouse Controller, CM D/ STAT Byte

0070, bit 7

1 bit

Chipset— Enable NM I

0070, bits 6:0

7 bits

M C146818— Real Time Clock, Address

0071

1 byte

M C146818— Real Time Clock, Data

0078

1 byte

Reserved— Board Configuration

0079

1 byte

Reserved— Board Configuration

0080–008F

16 bytes

Chipset— DM A Page Registers

00A0–00A1

2 bytes

Chipset—8259 Interrupt Controller 2

00B2

1 byte

APM control port

00B3

1 byte

APM status port

00C0–00DE

31 bytes

Chipset—8237 DM A 2

00F0

1 byte

M ath Coprocessor Reset Numeric Error

To fin d ou t exactly wh at p ort ad d resses are bein g u sed on you r m oth erboard , con su lt th e m oth erboard d ocu m en tation or look th ese settin gs u p in th e W in d ows Device Man ager. Bu s-based d evices n orm ally u se th e ad d resses from 100h on u p . Table 4.37 lists th e com m on ly u sed bu s-based d evice ad d resses an d also lists som e com m on ad ap ter card s an d th eir settin gs.

System Resources

Table 4.37

Bus-Based Device Port Addresses

Address ( hex)

Size

Descript ion

0130–0133

4 bytes

Adaptec SCSI Adapter (alternate)

0134–0137

4 bytes

Adaptec SCSI Adapter (alternate)

0168–016F

8 bytes

Fourth IDE Interface

0170–0177

8 bytes

Secondary IDE Interface

01E8–01EF

8 bytes

Third IDE Interface

01F0–01F7

8 bytes

Primary IDE / AT (16-bit) Hard Disk Controller

0200–0207

8 bytes

Gameport or Joystick Adapter

0210–0217

8 bytes

IBM XT Expansion Chassis

0220–0233

20 bytes

Creative Labs Sound Blaster 16 Audio (default)

0230–0233

4 bytes

Adaptec SCSI Adapter (alternate)

0234–0237

4 bytes

Adaptec SCSI Adapter (alternate)

0238–023B

4 bytes

M S Bus M ouse (alternate)

023C–023F

4 bytes

M S Bus M ouse (default)

0240–024F

16 bytes

SM C Ethernet Adapter (default)

0240–0253

20 bytes

Creative Labs Sound Blaster 16 Audio (alternate)

0258–025F

8 bytes

Intel Above Board

0260–026F

16 bytes

SM C Ethernet Adapter (alternate)

0260–0273

20 bytes

Creative Labs Sound Blaster 16 Audio (alternate)

0270–0273

4 bytes

Plug and Play I/ O read ports

0278–027F

8 bytes

Parallel Port 2 (LPT2)

0280–028F

16 bytes

SM C Ethernet Adapter (alternate)

0280–0293

19 bytes

Creative Labs Sound Blaster 16 Audio (alternate)

02A0–02AF

16 bytes

SM C Ethernet Adapter (alternate)

02C0–02CF

16 bytes

SM C Ethernet Adapter (alternate)

02E0–02EF

16 bytes

SM C Ethernet Adapter (alternate)

02E8–02EF

8 bytes

Serial Port 4 (COM 4)

02EC–02EF

4 bytes

Video, 8514 or ATI standard ports

02F8–02FF

8 bytes

Serial Port 2 (COM 2)

0300–0301

2 bytes

M PU-401 M IDI Port (secondary)

0300–030F

16 bytes

SM C Ethernet Adapter (alternate)

0320–0323

4 bytes

XT (8-bit) Hard Disk Controller

0320–032F

16 bytes

SM C Ethernet Adapter (alternate)

0330–0331

2 bytes

M PU-401 M IDI Port (default)

0330–0333

4 bytes

Adaptec SCSI Adapter (default)

0334–0337

4 bytes

Adaptec SCSI Adapter (alternate)

0340–034F

16 bytes

SM C Ethernet Adapter (alternate)

0360–036F

16 bytes

SM C Ethernet Adapter (alternate) (continues)

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Table 4.37

Bus-Based Device Port Addresses Cont inued

Address ( hex)

Size

Descript ion

0366

1 byte

Fourth IDE Command Port

0367, bits 6:0

7 bits

Fourth IDE Status Port

0370–0375

6 bytes

Secondary Floppy Controller

0376

1 byte

Secondary IDE Command Port

0377, bit 7

1 bit

Secondary Floppy Controller Disk Change

0377, bits 6:0

7 bits

Secondary IDE Status Port

0378–037F

8 bytes

Parallel Port 1 (LPT1)

0380–038F

16 bytes

SM C Ethernet Adapter (alternate)

0388–038B

4 bytes

Audio—FM Synthesizer

03B0–03BB

12 bytes

Video, M ono/ EGA/ VGA standard ports

03BC–03BF

4 bytes

Parallel Port 1 (LPT1) in some systems

03BC–03BF

4 bytes

Parallel Port 3 (LPT3)

03C0–03CF

16 bytes

Video, EGA/ VGA standard ports

03D0–03DF

16 bytes

Video, CGA/ EGA/ VGA standard ports

03E6

1 byte

Third IDE Command Port

03E7, bits 6:0

7 bits

Third IDE Status Port

03E8–03EF

8 bytes

Serial Port 3 (COM 3)

03F0–03F5

6 bytes

Primary Floppy Controller

03F6

1 byte

Primary IDE Command Port

03F7, bit 7

1 bit

Primary Floppy Controller Disk Change

03F7, bits 6:0

7 bits

Primary IDE Status Port

03F8–03FF

8 bytes

Serial Port 1 (COM 1)

04D0–04D1

2 bytes

Edge/ level triggered PCI Interrupt Controller

0530–0537

8 bytes

Windows Sound System (default)

0604–060B

8 bytes

Windows Sound System (alternate)

0678–067F

8 bytes

LPT2 in ECP mode

0778–077F

8 bytes

LPT1 in ECP mode

0A20–0A23

4 bytes

IBM Token Ring Adapter (default)

0A24–0A27

4 bytes

IBM Token Ring Adapter (alternate)

0CF8–0CFB

4 bytes

PCI Configuration Address Registers

0CF9

1 byte

Turbo and Reset Control Register

0CFC–0CFF

4 bytes

PCI Configuration Data Registers

FF00–FF07

8 bytes

IDE Bus M aster Registers

FF80–FF9F

32 bytes

Universal Serial Bus (USB)

FFA0–FFA7

8 bytes

Primary Bus M aster IDE Registers

FFA8–FFAF

8 bytes

Secondary Bus M aster IDE Registers

To fin d ou t exactly wh at you r d evices are u sin g, again I recom m en d con su ltin g th e d ocu m en tation for th e d evice or lookin g th e d evice u p in th e W in d ows Device Man ager.

Resolving Resource Conflicts

Virtu ally all d evices on you r system bu ses u se I/ O p ort ad d resses. Most of th ese are fairly stan d ard ized , m ean in g you won ’t often h ave con flicts or p roblem s with th ese settin gs. In th e n ext section , you learn som e of th e tech n iq u es th at you can u se to solve th is p roblem .

Resolving Resource Conflict s Th e resou rces in a system are lim ited , wh ile th e d em an d s on th ose resou rces seem to be u n lim ited . As you ad d m ore an d m ore ad ap ter card s to you r system , you will fin d th at th e p oten tial for resou rce con flicts in creases. If you r system is fu lly Pn Pcom p atible, th en p oten tial con flicts sh ou ld be resolved au tom atically. How d o you kn ow wh eth er you h ave a resou rce con flict? Typ ically, on e of th e d evices in you r system stop s workin g. Resou rce con flicts can exh ibit th em selves in oth er ways, th ou gh . An y of th e followin g even ts cou ld be d iagn osed as a resou rce con flict: ■ A d evice tran sfers d ata in accu rately. ■ You r system freq u en tly locks u p . ■ You r sou n d card d oesn ’t sou n d q u ite righ t. ■ You r m ou se d oesn ’t work. ■ Garbage ap p ears on you r vid eo screen for n o ap p aren t reason . ■ You r p rin ter p rin ts gibberish . ■ You can n ot form at a flop p y d isk. ■ Th e PC starts in Safe Mod e (W in d ows 95). W in d ows 95 an d n ewer version s will also sh ow con flicts by h igh ligh tin g a d evice in yellow or red in th e Device Man ager rep resen tation . By u sin g th e W in d ows Device Man ager, you can u su ally sp ot th e con flicts q u ickly. In th e followin g section s, you learn som e of th e step s th at you can take to h ead off resou rce con flicts or to track th em d own wh en th ey occu r.

Caut ion Be careful in diagnosing resource conflicts; a problem may not be a resource conflict at all, but a computer virus. M any computer viruses are designed to exhibit themselves as glitches or as periodic problems. If you suspect a resource conflict, it may be worthwhile to run a virus check first to ensure that the system is clean. This procedure could save you hours of work and frustration.

Resolving Conflict s M anually Un fortu n ately, th e on ly way to resolve con flicts m an u ally is to take th e cover off you r system an d start ch an gin g switch es or ju m p er settin gs on you r ad ap ter card s. Each of th ese ch an ges th en m u st be accom p an ied by a system reboot, wh ich im p lies th at th ey

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take a great d eal of tim e. Th is situ ation brin gs u s to th e first ru le of resolvin g con flicts: W h en you set abou t rid d in g you r system of resou rce con flicts, m ake su re th at you allow a good d eal of u n in terru p ted tim e. Also m ake su re th at you write d own you r cu rren t system settin gs before you start m akin g ch an ges. Th at way, you will kn ow wh ere you began an d can go back to th e origin al con figu ration (if n ecessary). Fin ally, d ig ou t th e m an u als for all you r ad ap ter board s; you will n eed th em . If you can n ot fin d th e m an u als, con tact th e m an u factu rers to d eterm in e wh at th e variou s ju m p er p osition s an d switch settin gs m ean . Ad d ition ally, you cou ld look for m ore cu rren t in form ation on lin e at th e m an u factu rers’ W eb sites. On e of th e greatest resou rces for p rod u ct d ocu m en tation is Micro Hou se In tern ation al. Th ey p rod u ce several d ocu m en tation su p p ort p rod u cts in clu d in g Support Source for Hardware. In it you will fin d in form ation in clu d in g resou rce settin gs for virtu ally every typ e of ad ap ter card . Qu e also p u blish es a set of books, The Micro House PC Hardware Library (ISBN 0-7897-1662-3), based on th is m aterial. Th ere is a selection of it in clu d ed in th e Su p p ort Sou rce p rogram on th e CD with th is book. I h igh ly recom m en d you ch eck th is ou t. On ce you see h ow m u ch in form ation is th ere, you will u se it all th e tim e. It’s esp ecially u sefu l for old er h ard ware wh ere th e origin al d ocu m en tation h as been lost or th e com p an y h as gon e ou t of bu sin ess. Now you are read y to begin you r d etective work. As you try variou s switch settin gs an d ju m p er p osition s, keep th e followin g q u estion s in m in d ; th e an swers will h elp you n arrow d own th e con flict areas: ■ W hen did the conflict first becom e apparent? If th e con flict occu rred after you in stalled a n ew ad ap ter card , th at n ew card p robably is cau sin g th e con flict. If th e con flict occu rred after you started u sin g n ew software, ch an ces are good th at th e software u ses a d evice th at is taxin g you r system ’s resou rces in a n ew way. ■ Are there two sim ilar devices in your system that do not work? For exam p le, if you r m od em an d m ou se—d evices th at u se a COM p ort—d o n ot work, ch an ces are good th at th ese d evices are con flictin g with each oth er. ■ Have other people had the sam e problem , and if so, how did they resolve it? Pu blic foru m s—su ch as th ose on Com p u Serve, In tern et n ewsgrou p s, an d Am erica On lin e—are great p laces to fin d oth er u sers wh o m ay be able to h elp you solve th e con flict. W h en ever you m ake ch an ges in you r system , reboot an d see wh eth er th e p roblem p ersists. W h en you believe th at you h ave solved th e p roblem , m ake su re th at you test all you r software. Fixin g on e p roblem often seem s to cau ses an oth er to crop u p . Th e on ly way to m ake su re th at all p roblem s are resolved is to test everyth in g in you r system . On e of th e best p ieces of ad vice I can give you h ere is to try ch an gin g on e th in g at a tim e an d th en retest. Th at is th e m ost m eth od ical an d sim p lest way to isolate a p roblem q u ickly an d efficien tly.

Resolving Resource Conflicts

As you attem p t to resolve you r resou rce con flicts, you sh ou ld work with an d u p d ate a system -con figu ration tem p late, as d iscu ssed in th e followin g section . Using a Syst em -Configurat ion Tem plat e A system -configuration tem plate is h elp fu l, sim p ly becau se it is easier to rem em ber som eth in g th at is written d own th an it is to keep it in you r h ead . To create a con figu ration tem p late, all you n eed to d o is start writin g d own wh at resou rces are u sed by wh ich p arts of you r system . Th en , wh en you n eed to m ake a ch an ge or ad d an ad ap ter, you can q u ickly d eterm in e wh ere con flicts m ay arise. You can also u se th e W in d ows 95, 98, or NT 5.0+ d evice m an ager to list an d p rin t th is in form ation . I like to u se a worksh eet sp lit in to th ree m ain areas—on e for in terru p ts, an oth er for DMA ch an n els, an d a m id d le area for d evices th at d o n ot u se in terru p ts. Each section lists th e IRQ or DMA ch an n el on th e left an d th e I/ O p ort d evice ran ge on th e righ t. Th is way, you get th e clearest p ictu re of wh at resou rces are u sed an d wh ich on es are available in a given system . See th e System Resou rce Map on p age 284—it’s th e system -con figu ration tem p late I h ave d evelop ed over th e years an d still u se alm ost d aily. Th is typ e of con figu ration sh eet is resou rce-based in stead of com p on en t-based . Each row in th e tem p late rep resen ts a d ifferen t resou rce, an d lists th e com p on en t u sin g th e resou rce an d th e resou rces u sed . Th e ch art h as p re-en tered all of th e fixed item s in a m od ern PC, wh ose con figu ration can n ot be ch an ged . To fill ou t th is typ e of ch art, you wou ld p erform th e followin g step s: 1. En ter th e d efau lt resou rces u sed by stan d ard com p on en ts, su ch as serial an d p arallel p orts, d isk con trollers, an d vid eo. You can u se th e filled -ou t exam p le I h ave p rovid ed to see h ow m ost stan d ard d evices are con figu red . 2. En ter th e d efau lt resou rces u sed by ad d ition al ad d -on com p on en ts su ch as sou n d card s, SCSI card s, n etwork card s, p rop rietary card s, an d so on . 3. Ch an ge an y con figu ration item s th at are in con flict. Try to leave bu ilt-in d evices at th eir d efau lt settin gs, an d sou n d card s. Oth er in stalled ad ap ters m ay h ave th eir settin gs ch an ged , bu t be su re to d ocu m en t th e ch an ges. Of cou rse, a tem p late su ch as th is is best u sed wh en first in stallin g com p on en ts, n ot after. On ce you h ave it com p letely filled ou t to m atch you r system , you can label it an d keep it with th e system . W h en you ad d an y m ore d evices, th e tem p late will be you r gu id e as to h ow an y n ew d evices sh ou ld be con figu red . Th e exam p le on p age 285 is th e sam e tem p late filled ou t for a typ ical m od ern PC system .

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Syst em Resource M ap PC Make an d Mod el: Serial Nu m ber: Date:

_________________________ _________________________ _________________________

In terru p ts (IRQs):

I/ O Port Ad d resses:

0

-

Tim er Circu its.......................

040-04B............

1

-

Keyboard / Mou se Con troller..........

060 & 064..........

2

-

2n d 8259 IRQ Con troller..............

0A0-0A1............

8 -

Real Tim e Clock / CMOS RAM..........

070-071............

9 -

____________________________________

___________________

10 -

____________________________________

___________________

11 -

____________________________________

___________________

12 -

____________________________________

___________________

13 -

Math Cop rocessor....................

0F0................

14 -

____________________________________

___________________

15 -

____________________________________

___________________

3

-

____________________________________

___________________

4

-

____________________________________

___________________

5

-

____________________________________

___________________

6

-

____________________________________

___________________

7

-

____________________________________

___________________

Devices n ot u sin g In terru p ts:

I/ O Port Ad d resses:

Mon o/ EGA/ VGA Stan d ard Ports...............

3B0-3BB............

EGA/ VGA Stan d ard Ports....................

3C0-3CF............

CGA/ EGA/ VGA Stan d ard Ports................

3D0-3DF............

___________________________________________

___________________

___________________________________________

___________________

___________________________________________

___________________

___________________________________________

___________________

___________________________________________

___________________

DMA Ch an n els: 0 -

____________________________________

1 -

____________________________________

2 -

____________________________________

3 -

____________________________________

4-

DMA Ch an n el 0-3 Cascad e..............

5-

____________________________________

6-

____________________________________

7-

____________________________________

Resolving Resource Conflicts

Syst em Resource M ap PC Make an d Mod el: Serial Nu m ber: Date:

In tel AL440LX____________ 100000 __________________ 06/ 09/ 98_________________

In terru p ts (IRQs):

I/ O Port Ad d resses:

0

-

Tim er Circu its.......................

040-04B............

1

-

Keyboard / Mou se Con troller..........

060 & 064..........

2

-

2n d 8259 IRQ Con troller..............

0A0-0A1............

8 -

Real Tim e Clock / CMOS RAM..........

070-071............

9 -

SMC Eth erEZ Eth ern et card ___________

340-35F____________

10 -

____________________________________

___________________

11 -

Ad ap tec 1542CF SCSI Ad ap ter (scan n er)

334-337*___________

12 -

Moth erboard Mou se Port______________

060 & 064__________

13 -

Math Cop rocessor....................

0F0................

14 -

Prim ary IDE (h ard d isk 1 an d 2)_____

1F0-1F7, 3F6_______

15 -

Secon d ary IDE (CDROM/ tap e)__________

170-177, 376_______

3

-

Serial Port 2 (Mod em )________________

3F8-3FF____________

4

-

Serial Port 1 (COM1)_________________

2F8-2FF____________

5

-

Sou n d Blaster 16 Au d io_______________

220-233____________

6

-

Flop p y Con troller____________________

3F0-3F5____________

7

-

Parallel Port 1 (Prin ter)____________

378-37F____________

Devices n ot u sin g In terru p ts:

I/ O Port Ad d resses:

Mon o/ EGA/ VGA Stan d ard Ports...............

3B0-3BB............

EGA/ VGA Stan d ard Ports....................

3C0-3CF............

CGA/ EGA/ VGA Stan d ard Ports................

3D0-3DF............

ATI Mach 64 Vid eo card ad d ition al p orts___

102,1CE-1CF,2EC-2EF

Sou n d Blaster 16 MIDI p ort________________

330-331____________

Sou n d Blaster 16 Gam e p ort (joystick)_____

200-207____________

Sou n d Blaster 16 FM syn th esizer (m u sic)___

388-38B____________

__________________________________________

___________________

DMA Ch an n els: 0 -

_____________________________________

1 -

Sou n d Blaster 16 (8-bit DMA)_________

2 -

Flop p y Con troller____________________

3 -

Parallel Port 1 (in ECP m od e)________

4-

DMA Ch an n el 0-3 Cascad e..............

5-

Sou n d Blaster 16 (16-bit DMA)________

6-

Ad ap tec 1542CF SCSI ad ap ter*_________

7-

_____________________________________

*Rep resen ts a resou rce settin g th at h ad to be ch an ged to resolve a con flict.

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As you can see from th is tem p late, on ly on e IRQ an d two DMA ch an n els rem ain available, an d th ere wou ld be n o IRQs if I en abled th e USB on th e m oth erboard ! Th is exam p le also sh ows th at in terru p t sh ortages are a big p roblem in m od ern system s. In th at case, I wou ld p robably fin d a way to recover on e of th e oth er in terru p ts. For exam p le, I am n ot really u sin g COM1: so I cou ld d isable th at p ort an d gain back IRQ 4. In th is exam p le con figu ration , th e p rim ary an d secon d ary IDE con n ectors were bu ilt in to th e m oth erboard : ■ Flop p y con troller ■ Two serial p orts ■ On e p arallel p ort W h eth er th ese d evices are bu ilt in to th e m oth erboard or on a sep arate card m akes n o d ifferen ce becau se th e resou rce allocation s are th e sam e in eith er case. All d efau lt settin gs are n orm ally u sed for th ese d evices, an d are in d icated in th e com p leted con figu ration . Next, th e accessory card s were con figu red . In th is exam p le, th e followin g card s were in stalled : ■ SVGA vid eo card (ATI Mach 64) ■ Sou n d card (Creative Labs Sou n d Blaster 16) ■ SCSI h ost ad ap ter (Ad ap tec AHA-1542CF) ■ Network in terface card (SMC Eth erEZ) It h elp s to in stall th e card s in th is ord er. Start with th e vid eo card ; n ext, ad d th e sou n d card . Du e to p roblem s with software th at m u st be con figu red to th e sou n d card , it is best to in stall it early an d m ake su re on ly d efau lt settin gs are u sed . It is better to ch an ge settin gs on oth er card s th an th e sou n d card . After th e sou n d card , th e SCSI ad ap ter was in stalled ; h owever, th e d efau lt I/ O Port ad d resses (330-331) an d DMA ch an n el (DMA 5) u sed were in con flict with oth er card s (m ain ly th e sou n d card ). Th ese settin gs were ch an ged to th eir n ext logical settin gs wh ich d id n ot cau se a con flict. Fin ally, th e n etwork card was in stalled , wh ich also h ad d efau lt settin gs th at con flicted with oth er card s. In th is case, th e Eth ern et card cam e p recon figu red to IRQ 3, wh ich was alread y in u se by COM2:. Th e solu tion was to ch an ge th e settin g, an d IRQ 9 was th e n ext logical ch oice in th e card ’s con figu ration settin gs. Even th ou gh th is is a fu lly load ed con figu ration , on ly th ree in d ivid u al item s am on g all of th e card s h ad to be ch an ged to ach ieve an op tim u m system con figu ration . Usin g a con figu ration tem p late su ch as th e on e sh own can m ake wh at wou ld oth erwise be a ju m ble of settin gs com e togeth er in an easy-to-follow m an n er. Th e on ly real p roblem s you will ru n in to on ce you work with th ese tem p lates are card s th at d o n ot allow for en ou gh ad ju stm en t in th eir settin gs, or card s th at are lackin g in d ocu m en tation . As you can im agin e, you will n eed th e d ocu m en tation for each ad ap ter card , an d th e

Resolving Resource Conflicts

m oth erboard , in ord er to accu rately com p lete a con figu ration table su ch as th e on e sh own .

Tip Do not rely too much on third-party software diagnostics such as M SD.EXE that claim to be able to show hardware settings such as IRQ and I/ O port settings. While they can be helpful in certain situations, they are often wrong with respect to at least some of the information they are displaying about your system. One or two items shown incorrectly can be very troublesome if you believe the incorrect information and configure your system based on it! A much better utility to view these settings is the Device M anager built in to Windows 95/ 98 and NT 5.0+. On a Plug-and-Play system, it will not only report settings, but also will allow you to change them. On older legacy hardware, you will be able to view the settings but not change them.

Heading Off Problem s: Special Boards A n u m ber of d evices th at you m ay wan t to in stall in a com p u ter system req u ire IRQ lin es or DMA ch an n els, wh ich m ean s th at a world of con flict cou ld be waitin g in th e box th at th e d evice com es in . As m en tion ed in th e p reced in g section , you can save you rself p roblem s if you u se a system -con figu ration tem p late to keep track of th e way th at you r system is con figu red . You also can save you rself trou ble by carefu lly read in g th e d ocu m en tation for a n ew ad ap ter board before you attem p t to in stall it. Th e d ocu m en tation d etails th e IRQ lin es th at th e board can u se, an d its DMA-ch an n el req u irem en ts. In ad d ition , th e d ocu m en tation will d etail th e ad ap ter’s u p p er-m em ory n eed s for ROM an d ad ap ter. Th e followin g section s d escribe som e of th e con flicts th at you m ay en cou n ter wh en you in stall tod ay’s m ost p op u lar ad ap ter board s. Alth ou gh th e list of ad ap ter board s covered in th ese section s is far from com p reh en sive, th e section s serve as a gu id e to in stallin g com p lex h ard ware with m in im u m h assle. In clu d ed are tip s on sou n d board s, SCSI h ost ad ap ters, an d n etwork ad ap ters. Sound Boards. Sou n d card s are p robably th e biggest sin gle resou rce h og in you r system . Th ey u su ally u se at least on e IRQ, two DMA ch an n els, an d m u ltip le I/ O p ort ad d ress ran ges. Th is is becau se a sou n d card is actu ally several d ifferen t p ieces of h ard ware all on on e board . Most sou n d card s are sim ilar to th e Sou n d Blaster 16 from Creative Labs. Figu re 4.30 sh ows th e d efau lt resou rces u sed by th e com p on en ts on a typ ical Sou n d Blaster 16 card . As you can see, th ese card s u se q u ite a few resou rces. If you take th e tim e to read you r sou n d board ’s d ocu m en tation an d d eterm in e its com m u n ication s-ch an n el n eed s, com p are th ose n eed s to th e IRQ lin es an d DMA ch an n els th at alread y are in u se in you r system , an d th en ch an ge th e settin gs of th e oth er ad ap ters to avoid con flicts with th e sou n d card , you r in stallation will go q u ickly an d sm ooth ly.

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Device

Interrupt

I/O Ports

16-bit DMA

8-bit DMA

Audio

IRQ5

220h-233h

DMA 5

DMA 1

Device

Interrupt

MIDI Port FM Synthesizer Game Port

330h-331h 388h-38Bh 200h-207h

FIG. 4.30 Defau lt resou rces for Sou n d Blaster 16 card .

Tip The greatest single piece of advice I have for installing a sound card is to put the sound card in before all other cards except the video card. In other words, let the sound card retain all of its default settings; never change a resource setting to prevent a conflict. Instead, always change the settings of other adapters when a conflict with the sound card arises. The problem here is that many educational and game programs that use sound are very poorly written with respect to supporting alternate resource settings on sound cards. Save yourself some grief and let the sound card have its way!

On e exam p le of a p oten tial sou n d -board con flict is th e com bin ation of a Sou n d Blaster 16 an d an Ad ap tec SCSI ad ap ter. Th e Sou n d an d SCSI ad ap ters will con flict on DMA 5 an d on I/ O p orts 330-331. Rath er th an ch an gin g th e settin gs of th e sou n d card , it is best to alter th e SCSI ad ap ter to th e n ext available settin gs th at will n ot con flict with th e sou n d card or an yth in g else. Th e fin al settin gs were sh own in th e p reviou s con figu ration tem p late. Th e card s in q u estion (Sou n d Blaster 16 an d AHA-1542CF) are n ot sin gled ou t h ere becau se th ere is som eth in g wron g with th em , bu t in stead becau se th ey h ap p en to be th e m ost p op u lar card s of th eir resp ective typ es, an d as su ch will often be p aired togeth er. Most p eop le wou ld be u sin g PCI version s of th ese card s tod ay, bu t th ey will still req u ire th e sam e typ es of resou rce settin gs with th e on ly excep tion bein g DMA ch an n els. Un fortu n ately, it wasn ’t DMA ch an n els th at we were really ru n n in g ou t of. Th e in terru p t sh ortage con tin u es even with PCI card s becau se th ey m u st be m ap p ed to ISA IRQs. Th e real solu tion will be in a year or so wh en we start to see a n ew breed of PC th at lacks an y ISA slots an d th at breaks ties with th at bu s forever. W h en th at h ap p en s, we will be free of th e in terru p t restriction s we h ave been on for so m an y years. On e tip worth m en tion in g is th at th e n ewer PCI sou n d card s are largely in com p atible with old er DOS-based software becau se th ey d on ’t u se DMA ch an n els like th eir ISA cou n terp arts. Eith er u p d ate you r software to 32-bit W in d ows version s or you will n ot be able to u se th ese n ewer PCI bu s sou n d card s. Most of th e n ewer PCI card s d o in clu d e an em u lation p rogram th at allows th e card to work with old er DMA-d ep en d en t software, bu t th e resu lts are often p roblem atic.

Resolving Resource Conflicts

SCSI Adapt er Boards. SCSI ad ap ter board s u se m ore resou rces th an ju st abou t an y oth er typ e of ad d -in d evice excep t p erh ap s a sou n d card . Th ey will often u se resou rces th at are in con flict with sou n d card s or n etwork card s. A typ ical SCSI h ost ad ap ter req u ires an IRQ lin e, a DMA ch an n el, a ran ge of I/ O p ort ad d resses, p lu s a 16K ran ge of u n u sed u p p er m em ory for its ROM an d p ossible scratch -p ad RAM u se. Fortu n ately, th e typ ical SCSI ad ap ter is also easy to recon figu re, an d ch an gin g an y of th ese settin gs sh ou ld n ot affect p erform an ce or software op eration . Before in stallin g a SCSI ad ap ter, be su re to read th e d ocu m en tation for th e card , an d m ake su re th at an y IRQ lin es, DMA ch an n els, I/ O p orts, an d u p p er m em ory th at th e card n eed s are available. If th e system resou rces th at th e card n eed s are alread y in u se, u se you r system -con figu ration tem p late to d eterm in e h ow you can alter th e settin gs on th e SCSI card or oth er card s to p reven t an y resou rce con flicts before you attem p t to p lu g in th e ad ap ter card . Net w ork Int erface Cards ( NICs) . Networks are becom in g m ore an d m ore p op u lar all th e tim e. A typ ical n etwork ad ap ter d oes n ot req u ire as m an y resou rces as som e of th e oth er card s d iscu ssed h ere, bu t will req u ire at least a ran ge of I/ O p ort ad d resses an d an in terru p t. Most NICs will also req u ire a 16K ran ge of free u p p er m em ory to be u sed for th e RAM tran sfer bu ffer on th e n etwork card . As with an y oth er card s, m ake su re th at all of th ese resou rces are u n iq u e to th e card , an d are n ot sh ared with an y oth er d evices. M ult iple-COM -Port Adapt ers. A serial p ort ad ap ter u su ally h as two or m ore p orts on board . Th ese COM p orts req u ire an in terru p t an d a ran ge of I/ O p orts each . Th ere aren ’t too m an y p roblem s with th e I/ O p ort ad d resses, becau se th e ran ges u sed by u p to fou r COM p orts in a system are fairly well-d efin ed . Th e real p roblem is with th e in terru p ts. Most old er in stallation s of m ore th an two serial p orts h ave an y ad d ition al on es sh arin g th e sam e in terru p ts as th e first two. Th is is in correct, an d will cau se n oth in g bu t p roblem s with software th at ru n s u n d er W in d ows or OS/ 2. W ith th ese old er board s, m ake su re th at each serial p ort in you r system h as a u n iq u e I/ O p ort ad d ress ran ge, an d m ore im p ortan tly, a u n iq u e in terru p t settin g. Becau se COM p orts are req u ired for so m an y p erip h erals th at con n ect to th e m od ern PC, an d becau se th e n u m ber of COM p orts th at can be u sed is strictly lim ited by th e IRQ setu p in th e basic IBM system d esign , sp ecial COM-p ort card s are available th at en able you to assign a u n iq u e IRQ to each of th e COM p orts on th e card . For exam p le, you can u se su ch a card to leave COM1: an d COM2: con figu red for IRQ 4 an d IRQ 3, resp ectively, bu t to con figu re COM3: for IRQ 10 an d COM4: for IRQ 12 (p rovid ed you d o n ot h ave a m oth erboard -based m ou se p ort in you r system ). Man y n ewer m u ltip ort ad ap ter card s—su ch as th ose offered by Byte Ru n n er Tech n ologies—allow “in telligen t” in terru p t sh arin g am on g p orts. In som e cases, you can h ave u p to 12 COM p ort settin gs with ou t con flict p roblem s. Ch eck with you r ad ap ter card ’s m an u factu rer to d eterm in e wh eth er it allows for au tom atic or “in telligen t” in terru p t sh arin g.

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Alth ou gh m ost p eop le h ave p roblem s in correctly tryin g to sh are in terru p ts wh en in stallin g m ore th an two serial p orts in a system , th ere is a fairly com m on p roblem with th e I/ O p ort ad d ressin g th at sh ou ld be m en tion ed . Man y of th e h igh -p erform an ce vid eo ch ip sets, su ch as th ose from S3 In c. an d ATI, u se som e ad d ition al I/ O p ort ad d resses th at will con flict with th e stan d ard I/ O p ort ad d resses u sed by COM4:. In th e exam p le system -con figu ration ju st covered , you can see th at th e ATI vid eo card u ses som e ad d ition al I/ O p ort ad d resses, sp ecifically 2EC-2EF. Th is is a p roblem becau se COM4: is n orm ally con figu red as 2E8-2EF, wh ich overlap s with th e vid eo card . Th e vid eo card s th at u se th ese ad d resses are n ot n orm ally ad ju stable for th is settin g, so you will eith er h ave to ch an ge th e ad d ress of COM4: to a n on stan d ard settin g, or sim p ly d isable COM4:. Th is restricts you rself to u sin g on ly th ree serial p orts in th e system . If you d o h ave a serial ad ap ter th at su p p orts n on stan d ard I/ O ad d ress settin gs for th e serial p orts, you m u st en su re th at th ose settin gs are n ot u sed by oth er card s, an d you m u st in form an y software or d rivers, su ch as th ose in W in d ows, of you r n on stan d ard settin gs. W ith a m u ltip le-COM-p ort ad ap ter card in stalled an d p rop erly con figu red for you r system , you can h ave d evices h ooked to n u m erou s COM p orts, an d u p to fou r d evices can be fu n ction in g at th e sam e tim e. For exam p le, you can u se a m ou se, m od em , p lotter, an d serial p rin ter at th e sam e tim e. USB ( Universal Serial Bus) . USB p orts are n ow fou n d on m ost m oth erboard s an d with W in d ows 98 we fin ally h ave an op eratin g system th at will p rop erly su p p ort it. Th e big p roblem is th at USB will take an oth er in terru p t from you r system an d m an y eith er d on ’t h ave an y free or were d own to th eir last on e. In th at case, you sh ou ld look at wh at oth er d evices you can d isable (su ch as COM or LPT p orts) to gain back a n ecessary in terru p t for oth er d evices. If you aren ’t u sin g an y USB d evices, you sh ou ld tu rn off th e p ort u sin g you r m oth erboard CMOS setu p so th at th e IRQ it was u sin g will be freed . In th e fu tu re, as we m ove to USB-based keyboard s, m ice, m od em s, p rin ters, an d so on , th e IRQ sh ortage will be less of a p roblem . Also, th e elim in ation of th e ISA bu s in ou r system s will go a lon g way to solve th is p roblem . M iscellaneous Boards. Som e vid eo card s sh ip with ad van ced software th at allows sp ecial vid eo featu res su ch as oversized d esktop s, cu stom m on itors, switch m od es on -th e-fly, an d so on . Un fortu n ately, th is software req u ires th at th e card be con figu red to u se an in terru p t. I su ggest th at you d isp en se with th is u n n ecessary software an d con figu re th e card to free u p th e in terru p t for oth er d evices. Also related to vid eo is th e u se of an MPEG d ecod er ad d -on card th at works in ad d ition to you r n orm al grap h ics ad ap ter. Th ese are u sed m ore in sp ecialized vid eo p rod u ction , ed itin g, an d in p layin g DVD m ovies. However, th ey d o u se ad d ition al system resou rces th at m u st be available. Plug-and-Play Syst em s Plu g an d Play (Pn P) rep resen ts a m ajor revolu tion in recen t in terface tech n ology. Pn P first cam e on th e m arket in 1995, an d m ost n ew system s com e read y to take ad van tage

Resolving Resource Conflicts

of it. In th e p ast, PC u sers were forced to m u d d le th rou gh a n igh tm are of d ip switch es an d ju m p ers every tim e th ey wan ted to ad d n ew d evices to th eir system s. Th e resu lts, all too often , were system resou rce con flicts an d n on fu n ction in g card s. Pn P is n ot an en tirely n ew con cep t. It was a key d esign featu re of MCA an d EISA in terfaces, bu t th e lim ited ap p eal of MCA an d EISA m ean t th at th ey n ever becam e in d u stry stan d ard s. Th erefore, m ain stream PC u sers still worry abou t I/ O ad d resses, DMA ch an n els, an d IRQ settin gs. Bu t n ow th at Pn P sp ecification s are available for ISA-, PCI-, SCSI-, IDE-, an d PCMCIA-based system s, worry-free h ard ware setu p is with in th e grasp of all n ew com p u ter bu yers. Of cou rse, Pn P m ay well be with in you r grasp , bu t th at d oes n ot n ecessarily m ean you are read y to take ad van tage of it. For Pn P to work, th e followin g com p on en ts are req u ired : ■ Pn P h ard ware ■ Pn P BIOS ■ Pn P op eratin g system (op tion al) Each of th ese com p on en ts n eed s to be Pn P-com p atible, m ean in g th at it com p lies with th e Pn P sp ecification s. The Hardw are Com ponent . Th e hardware com ponent refers to both com p u ter system s an d ad ap ter card s. Th e term d oes n ot m ean , h owever, th at you can n ot u se you r old er ISA ad ap ter card s (referred to as legacy cards) in a Pn P system . You can u se th ese card s; in fact, you r Pn P BIOS au tom atically reassign s Pn P-com p atible card s arou n d existin g legacy com p on en ts. Pn P ad ap ter card s com m u n icate with th e system BIOS an d th e op eratin g system to con vey in form ation abou t wh at system resou rces are n eed ed . Th e BIOS an d op eratin g system , in tu rn , resolve con flicts (wh erever p ossible) an d in form th e ad ap ter card s wh ich sp ecific resou rces it sh ou ld u se. Th e ad ap ter card th en can m od ify its con figu ration to u se th e sp ecified resou rces. The BIOS Com ponent . Th e BIOS com p on en t m ean s th at m ost u sers of old er PCs n eed to u p d ate th eir BIOSs or p u rch ase n ew m ach in es th at h ave Pn P BIOSs. For a BIOS to be com p atible, it m u st su p p ort 13 ad d ition al system fu n ction calls, wh ich can be u sed by th e OS com p on en t of a Pn P system . Th e Pn P BIOS sp ecification was d evelop ed join tly by Com p aq , In tel, an d Ph oen ix Tech n ologies. Th e Pn P featu res of th e BIOS are im p lem en ted th rou gh an exp an d ed POST. Th e BIOS is resp on sible for id en tification , isolation , an d p ossible con figu ration of Pn P ad ap ter card s. Th e BIOS accom p lish es th ese tasks by p erform in g th e followin g step s: 1. Disable an y con figu rable d evices on th e m oth erboard or on ad ap ter card s. 2. Id en tify an y Pn P PCI or ISA d evices. 3. Com p ile an in itial resou rce-allocation m ap for p orts, IRQs, DMAs, an d m em ory.

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4. En able I/ O d evices. 5. Scan th e ROMs of ISA d evices. 6. Con figu re in itial-p rogram -load (IPL) d evices, wh ich are u sed later to boot th e system . 7. En able con figu rable d evices by in form in g th em wh ich resou rces h ave been assign ed to th em . 8. Start th e bootstrap load er. 9. Tran sfer con trol to th e op eratin g system . The Operat ing-Syst em Com ponent . Th e op eratin g-system com p on en t can be im p lem en ted by m ost n ewer system s, su ch as OS/ 2, W in d ows 95, W in d ows 98, or DOS exten sion s. Exten sion s of th is typ e sh ou ld be fam iliar to m ost DOS u sers; exten sion s h ave been u sed for years to p rovid e su p p ort for CD-ROM d rives. Exten sion software is available n ow for existin g op eratin g system s, an d you can exp ect all n ew PC op eratin g system s to h ave Pn P su p p ort bu ilt in . If you are u sin g W in d ows NT 4.0, Pn P d rivers m ay or m ay n ot h ave been load ed au tom atically. If n ot, th e d river can be fou n d on th e W in d ows NT 4.0 CD in th e DRVLIB\ PNPISA\ d irectory. Op en th e correct su bd irectory for you r ch ip set an d in stall th e file PNPISA.INF. W in d ows NT 5.0 h as fu ll su p p ort for Plu g an d Play bu ilt in . It is th e resp on sibility of th e op eratin g system to in form u sers of con flicts th at can n ot be resolved by th e BIOS. Dep en d in g on th e sop h istication of th e op eratin g system , th e u ser th en cou ld con figu re th e offen d in g card s m an u ally (on screen ) or tu rn th e system off an d set switch es on th e p h ysical card s. W h en th e system is restarted , th e system is ch ecked for rem ain in g (or n ew) con flicts, an y of wh ich are brou gh t to th e u ser’s atten tion . Th rou gh th is rep etitive p rocess, all system con flicts are resolved .

Not e Plug and Play is still going through some revisions. Windows 95 requires at least version 1.0a of the ISA PnP BIOS. If your system does not have the most current BIOS, I suggest that you install a BIOS upgrade. With the Flash ROM used in most PnP systems, you can just download the new BIOS image from the system vendor or manufacturer and run the supplied BIOS update program.

Know ing W hat t o Look For ( Select ion Crit eria) As a con su ltan t, I am often asked to m ake a recom m en d ation for p u rch ases. Makin g th ese typ es of recom m en d ation s is on e of th e m ost freq u en t tasks a con su ltan t p erform s. Man y con su ltan ts ch arge a large fee for th is ad vice. W ith ou t gu id an ce, m an y in d ivid u als d on ’t h ave an y rh ym e or reason to th eir selection s an d in stead base th eir ch oices solely on m agazin e reviews or, even worse, on som e p erson al bias. To h elp elim in ate th is h ap h azard selection p rocess, I h ave d evelop ed a sim p le ch ecklist th at will h elp you select a

Knowing What to Look For (Selection Criteria)

system . Th is list takes in to con sid eration several im p ortan t system asp ects overlooked by m ost ch ecklists. Th e goal is to en su re th at th e selected system tru ly is com p atible an d h as a lon g life of service an d u p grad es ah ead . It h elp s to th in k like an en gin eer wh en you m ake you r selection . Con sid er every asp ect an d d etail of th e m oth erboard s in q u estion . For in stan ce, you sh ou ld con sid er an y fu tu re u ses an d u p grad es. Tech n ical su p p ort at a p rofession al (as op p osed to a u ser) level is extrem ely im p ortan t. W h at su p p ort will be p rovid ed ? Is th ere d ocu m en tation , an d wh at d oes it cover? In sh ort, a ch ecklist is a good id ea. Here is on e for you to u se in evalu atin g an y PCcom p atible system . You m igh t n ot h ave to m eet every on e of th ese criteria to con sid er a p articu lar system , bu t if you m iss m ore th an a few of th ese ch ecks, con sid er stayin g away from th at system . Th e item s at th e top of th e list are th e m ost im p ortan t, an d th e item s at th e bottom are p erh ap s of lesser im p ortan ce (alth ou gh I th in k each item is im p ortan t). Th e rest of th is ch ap ter d iscu sses in d etail th e criteria in th is ch ecklist: ■ Processor. A Pen tiu m m oth erboard sh ou ld u se as a m in im u m th e Pen tiu m MMX p rocessor, wh ich req u ires a Socket 7-typ e socket for th e p rocessor to p lu g in to. A bon u s wou ld be on e of th e n ewer board s su p p ortin g th e 100MHz “Su p er-7” stan d ard d evelop ed by AMD an d Cyrix for th eir n ewest Socket 7 p rocessors. Th ere sh ou ld also be a bu ilt-in ad ju stable voltage regu lator allowin g for d ifferen t voltage CPUs to be accom m od ated with ou t p u rch asin g an ad d ition al regu lator m od u le. I can barely recom m en d a Pen tiu m system an ym ore; th ese d ays on e sh ou ld really con sid er a Pen tiu m II m ach in e as th e m in im u m . Th e lowest cost PII p rocessor is th e Celeron in trod u ced by In tel in m id -1998. Th is is a PII p rocessor with ou t th e Level 2 cach e, wh ich m akes it slower th an a regu lar Pen tiu m II bu t still faster th an th e Pen tiu m . All Celeron system s can be u p grad ed to fu ll PII statu s by m erely p lu ggin g in a PII p rocessor, becau se th e m oth erboard s are th e sam e. All Pen tiu m Pro m oth erboard s u se Socket 8, an d all n on server Pen tiu m II system s u se Slot 1 in wh ich to in stall th e p rocessor. ■ Processor sockets. A Pen tiu m m oth erboard sh ou ld h ave at least on e ZIF socket th at follows th e In tel Socket 7 (321-p in ) sp ecification . Th e Socket 7 with a bu ilt-in VRM (Voltage Regu lator Mod u le) rath er th an a socket for on e th at p lu gs in is best. Th is is becau se if you ch an ge th e p rocessor later; th e bu ilt-in VRM can be recon figu red with ju m p ers, wh ile if you h ave on ly a VRM socket, you will h ave to p u rch ase a n ew VRM to go with each n ew voltage p rocessor you try. Pen tiu m Pro (P6) m oth erboard s u se Socket 8, an d m an y are set u p for m u ltip le p rocessors. Pen tiu m II board s u se eith er Slot 1 or Slot 2. Th e Slot 1 system s are for n orm al u se, wh ile Slot 2 system s are on ly for th e h igh er-en d Pen tiu m II Xen on server p rocessors. Th ere are Slot 1 an d Slot 2 board s available with m u ltip le p rocessor sockets. Before goin g to th e exp en se of bu yin g a m u ltip rocessor board , en su re th at you r op eratin g system is able to h an d le it. For in stan ce, wh ile W in d ows 95 or 98 can n ot really ben efit from m ore th an on e CPU, W in d ows NT, OS/ 2, an d som e oth ers m ay ru n con sid erably faster.

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■ Motherboard speed. A Pen tiu m or Pen tiu m Pro m oth erboard sh ou ld ru n at 66MHz m in im u m ; som e can be set to an u n au th orized (bu t often fu lly fu n ction al) sp eed of 75MHz. Pen tiu m II m oth erboard s are available to ru n at eith er 66MHz or 100MHz for th e n ewer board s. Notice th at all th e Pen tiu m p rocessors sold tod ay ru n at a m u ltip le of th e m oth erboard sp eed . For exam p le, th e Pen tiu m II 350, 400 an d h igh er m egah ertz p rocessors ru n at a m oth erboard sp eed of 100MHz, an d wou ld th erefore req u ire a m oth erboard cap able of 100MHz op eration . Pen tiu m 333MHz an d lower-sp eed p rocessors ru n at 66MHz m axim u m . All com p on en ts on th e m oth erboard (esp ecially cach e m em ory on Pen tiu m board s) sh ou ld be rated to ru n at th e m axim u m allowable m oth erboard sp eed . ■ Cache m em ory. All classic Pen tiu m m oth erboard s sh ou ld h ave 256–512K of Level 2 cach e on board , som e will h ave 1M. Pen tiu m Pro an d Pen tiu m II p rocessors u se a bu ilt-in L1/ L2 cach e, wh ich m ean s th at th ere will be n o cach e on a Pen tiu m Pro or Pen tiu m II m oth erboard . Th e Pen tiu m Pro can h ave eith er 256K, 512K, or 1M of Level 2 cach e bu ilt-in wh ile th e Pen tiu m II can h ave eith er 0K (Celeron ) or 512K, an d 1M or m ore in th e Xen on p rocessors. Th e Level 2 cach e on a classic Pen tiu m board sh ou ld be p op u lated with ch ip s th at are fast en ou gh to su p p ort th e m axim u m m oth erboard sp eed , wh ich sh ou ld be 15n s or faster for 66MHz m axim u m m oth erboard sp eed s, an d 13n s or better for 75MHz op eration . For Pen tiu m board s, th e cach e sh ou ld be a Syn ch ron ou s SRAM (Static RAM) typ e, wh ich is also called Pipelined Burst SRAM. ■ SIMM/DIMM m em ory. If th e board is bein g u sed to u p grad e an old er system th at u sed 72-p in SIMMs, th en it m ay be d esirable to get th e typ e th at h as both SIMM an d DIMM sockets. If you are gettin g all n ew m em ory for th e board (recom m en d ed ), th en I h igh ly recom m en d on ly u sin g board s th at take SDRAM (Syn ch ron ou s DRAM) 168-p in DIMMs (Du al In lin e Mem ory Mod u les). Du e to th e 64-bit d esign of th ese board s, th e 72-p in SIMMs m u st be in stalled in m atch ed p airs, wh ile DIMMs are in stalled on e at a tim e (on e p er 64-bit ban k). Be su re th at th e m em ory is com p atible with th e ch ip set you are u sin g, an d m ore sp ecifically is rated for th e 66MHz or 100MHz sp eed it will be ru n n in g. Carefu lly con sid er th e total am ou n t of m em ory you will n eed , an d h ow m u ch th e board su p p orts. Classic Pen tiu m system s with th e 430FX, VX, or TX ch ip set on ly su p p ort a m axim u m of 64M of cach eable m em ory, wh ich effectively lim its you to th at am ou n t. Pen tiu m II system s will allow cach in g for all th e m em ory you can fit in to th e board , an d m ost will h an d le 384M or m ore of SDRAM DIMM m em ory. Th e 333MHz an d lower Pen tiu m II p rocessors can cach e u p to 512M of RAM (n ote m ost m oth erboard s won ’t h an d le th at m u ch ) wh ile th e n ewer 350MHz an d faster Pen tiu m IIs will cach e u p to 4G of system RAM. Alth ou gh 32M is regard ed as a m in im u m for tod ay’s m em ory-h u n gry ap p lication s, you m ay actu ally req u ire m u ch m ore. I recom m en d in stallin g 64M in m ost n ew system s. For m axim u m p erform an ce, look for system s th at su p p ort 3.3v SDRAM (Syn ch ron ou s DRAM) as a m in im u m . Fu tu re system s will u se even faster RDRAM (Ram bu s DRAM) RIMMs (Ram bu s In lin e Mem ory Mod u les) with sp eed s of 800MHz or m ore.

Knowing What to Look For (Selection Criteria)

■ Mission -critical system s sh ou ld u se p arity or ECC (Error Correctin g Cod e) DIMMs an d en su re th at th e m oth erboard fu lly su p p orts ECC (Error Correctin g Cod e) op eration . Most Pen tiu m (430 series) ch ip sets do not su p p ort ECC, wh ile m ost Pen tiu m II ch ip sets d o. Note th at th e low-en d 440EX board s n orm ally u sed in Celeron p rocessor-based system s d o n ot su p p ort ECC an d sh ou ld n ot be u sed for m ission -critical ap p lication s. ■ Fin ally, n ote th at m ost Pen tiu m an d Pen tiu m II m oth erboard s su p p ort eith er 3 or 4 DIMM sockets. Be su re th at you p op u late th em wisely so you d on ’t h ave to resort to rem ovin g m em ory later to ad d m ore, wh ich is n ot very cost-effective. ■ Bus type. Pen tiu m , Pen tiu m Pro, an d Pen tiu m II m oth erboard s sh ou ld h ave on e or m ore ISA bu s slots an d at least th ree or fou r PCI local bu s slots. Make su re th e PCI slots con form to th e PCI 2.1 revision (p rim arily based on th e ch ip set). Take a look at th e layou t of th e slots to en su re th at card s in serted in th em will n ot block access to m em ory sockets, or be blocked by oth er com p on en ts in th e case. Newer system s sh ou ld also featu re on e AGP (Accelerated Grap h ics Port) slot for a h igh p erform an ce AGP vid eo card . ■ BIOS. Th e m oth erboard sh ou ld u se an in d u stry-stan d ard BIOS su ch as th ose from AMI, Ph oen ix, or Award . Th e BIOS sh ou ld be of a Flash ROM or EEPROM (Electrically Erasable Program m able Read On ly Mem ory) d esign for easy u p d atin g. Look for a BIOS Recover ju m p er or m od e settin g, an d p ossibly a Flash ROM write-p rotect ju m p er on som e system s. Th e BIOS sh ou ld su p p ort th e Plu g-an d -Play (Pn P) sp ecification , an d En h an ced IDE or Fast ATA h ard d rives. Th ere sh ou ld also be su p p ort for th e n ewer LS-120 (120M) flop p y d rives an d IDE CD-ROM d rives as boot d evices. APM (Ad van ced Power Man agem en t) su p p ort sh ou ld be bu ilt in to th e BIOS, as well. ■ Form factor. For m axim u m flexibility, p erform an ce, reliability, an d ease-of-u se, th e ATX form factor can n ot be beat. ATX h as several d istin ct p erform an ce an d fu n ction al ad van tages over Baby-AT, an d is vastly su p erior to an y p rop rietary d esign s su ch as LPX. Ad d ition ally, th e n ew NLX form factor m ay be a con sid eration for low-p rofile or low-cost d esktop system s. ■ Built-in interfaces. Id eally, a m oth erboard sh ou ld con tain as m an y bu ilt-in stan d ard con trollers an d in terfaces as p ossible (excep t p erh ap s vid eo). A m oth erboard sh ou ld h ave a bu ilt-in flop p y con troller, bu ilt-in p rim ary an d secon d ary local bu s (PCI or VL-Bu s) En h an ced IDE (also called Fast ATA) con n ectors, two bu ilt-in h igh -sp eed serial p orts (m u st u se 16550A typ e bu ffered UARTs), two bu ilt-in USB (Un iversal Serial Bu s) p orts, an d a bu ilt-in h igh -sp eed p arallel p ort (m u st be EPP/ ECPcom p lian t). A bu ilt-in PS/ 2 typ e (6-p in m in i-DIN) m ou se p ort sh ou ld be in clu d ed , as well. Th e USB p orts h ave taken a wh ile to catch on , bu t th ey will becom e a “m u st-h ave” in th e n ear fu tu re as m ore an d m ore USB p erip h erals becom e available. A bu ilt-in SCSI p ort is a bon u s as lon g as it con form s to ASPI (Ad van ced SCSI Program m in g In terface) stan d ard s. Bu ilt-in n etwork ad ap ters are also n ice as lon g as th ey are th e typ e th at m atch es you r n etwork n eed s. A bu ilt-in sou n d card is a great featu re; th ey

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u su ally offer fu ll Sou n d Blaster com p atibility an d fu n ction s, an d m ay offer ad d ition al featu res. If you r sou n d n eed s are m ore d em an d in g, th en you m ay fin d th e bu ilt-in solu tion s less d esirable, an d will wan t to h ave a sep arate sou n d card in you r system . Bu ilt-in vid eo ad ap ters are also a bon u s in som e situ ation s, bu t becau se th ere are m an y d ifferen t vid eo ch ip set an d ad ap ter d esign s to ch oose from , gen erally, th ere are better ch oices in extern al local bu s vid eo ad ap ters. Th is is esp ecially tru e if you n eed th e h igh est p erform an ce vid eo available. Norm ally bu ilt-in d evices can be d isabled to allow fu tu re ad d -on s, bu t th ere can be p roblem s. ■ Plug and Play (PnP). Th e m oth erboard an d BIOS sh ou ld fu lly su p p ort th e In tel Pn P sp ecification . Th is will allow au tom atic con figu ration of PCI ad ap ters an d Pn P ISA ad ap ters.

Tip Even if a motherboard doesn’t list that it’s PnP-compatible, it may be. PCI motherboards are required to be PnP-compatible, as it is a part of the PCI standard.

■ Power Managem ent. Th e m oth erboard sh ou ld fu lly su p p ort SL En h an ced p rocessors with APM (Ad van ced Power Man agem en t) an d SMM (System Man agem en t Mod e) p rotocols th at allow for p owerin g d own variou s system com p on en ts to d ifferen t levels of read in ess an d p ower con su m p tion . Th e latest stan d ard for p ower m an agem en t is called ACPI (Ad van ced Con figu ration & Power In terface) version 1.0; m ake su re an y n ew board you p u rch ase su p p orts th at as a m in im u m . An En ergy-Starcom p lian t system is also a bon u s as th at m ean s it will u se less th an 30 watts of electrical en ergy wh en in sleep m od e, savin g en ergy an d you r electric bill. ■ Motherboard chipset. Pen tiu m II m oth erboard s sh ou ld u se a h igh -p erform an ce ch ip set th at su p p orts SDRAM DIMMs—p referably on e th at allows ECC m em ory, su ch as th e In tel 440LX or 440BX. Th e 440EX th at is d esign ed for low-cost an d low-en d system s on ly, d oes n ot su p p ort ECC m em ory an d sh ou ld n ot be u sed in m ission -critical system s. Note th at for Classic Pen tiu m system s, m ost of th e available In tel ch ip sets d o n ot su p p ort p arity or ECC m em ory. In th at case, board s with ch ip sets from ALi (Acer Laboratories, In c.), VIA tech n ologies, or SiS (Silicon In tegrated System s) sh ou ld be con sid ered . Th ese com p an ies h ave con tin u ed m akin g h igh -p erform an ce classic Pen tiu m ch ip sets, an d m an y of th eir offerin gs d o su p p ort SDRAM DIMMs with ECC. ■ Docum entation. Good tech n ical d ocu m en tation is a req u irem en t. Docu m en ts sh ou ld in clu d e in form ation on an y an d all ju m p ers an d switch es fou n d on th e board , con n ector p in ou ts for all con n ectors, sp ecification s for cach e RAM ch ip s, SIMMs, an d oth er p lu g-in com p on en ts, an d an y oth er ap p licable tech n ical in form ation . I wou ld also acq u ire sep arate d ocu m en tation from th e BIOS m an u factu rer coverin g th e sp ecific BIOS u sed in th e system , an d th e d ata books coverin g th e

Knowing What to Look For (Selection Criteria)

sp ecific ch ip set u sed in th e m oth erboard . Ad d ition al d ata books for an y oth er con troller or I/ O ch ip s on board are a bon u s, an d m ay be acq u ired from th e resp ective ch ip m an u factu rers. An oth er n ice th in g to h ave is available on lin e su p p ort an d d ocu m en tation u p d ates, alth ou gh th is sh ou ld n ot be accep ted in p lace of good h ard cop y m an u als. You m ay n otice th at th ese selection criteria seem fairly strict, an d m ay d isq u alify m an y m oth erboard s on th e m arket, in clu d in g wh at you alread y h ave in you r system ! Th ese criteria will, h owever, gu aran tee you th e h igh est q u ality m oth erboard offerin g th e latest in PC tech n ology th at will be u p grad able, exp an d able, an d p rovid e good service for m an y years. Most of th e tim e, I recom m en d p u rch asin g board s from better-kn own m oth erboard m an u factu rers su ch as In tel, Acer, ABIT, Asu sTek, Elitegrou p , FIC (First In tern ation al Com p u ter), an d oth ers. Th ese board s m igh t cost a little m ore th an oth ers th at you h ave n ever h eard of, bu t th ere is som e safety in th e m ore well-kn own bran d s. Th at is, th e m ore board s th at th ey sell, th e m ore likely th at an y p roblem s will h ave been d iscovered by oth ers an d solved lon g before you get you rs. Also, if service or su p p ort are n eed ed , th e larger ven d ors are m ore likely to be arou n d in th e lon g ru n . Docum ent at ion As m en tion ed , exten sive d ocu m en tation is an im p ortan t factor to con sid er wh en you ’re p lan n in g to p u rch ase a m oth erboard . Most m oth erboard m an u factu rers d esign th eir board s arou n d a p articu lar ch ip set, wh ich actu ally cou n ts as th e bu lk of th e m oth erboard circu itry. Th ere are a n u m ber of m an u factu rers offerin g ch ip sets, su ch as In tel, VIA, ALi, SiS, an d oth ers. I recom m en d obtain in g th e d ata book or oth er tech n ical d ocu m en tation on th e ch ip set d irectly from th e ch ip set m an u factu rer. On e of th e m ore com m on q u estion s I h ear abou t a system relates to th e BIOS Setu p p rogram . Peop le wan t to kn ow wh at th e “Ad van ced Ch ip set Setu p ” featu res m ean an d wh at will th e effects of ch an gin g th em be. Often th ey go to th e BIOS m an u factu rer th in kin g th at th e BIOS d ocu m en tation will offer h elp . Usu ally, h owever, p eop le fin d th at th ere is n o real coverage of wh at th e ch ip set setu p featu res are in th e BIOS d ocu m en tation . You will fin d th is in form ation in th e d ata book p rovid ed by th e ch ip set m an u factu rer. Alth ou gh th ese books are m ean t to be read by th e en gin eers wh o d esign th e board s, th ey con tain all th e d etailed in form ation abou t th e ch ip set’s featu res, esp ecially th ose th at m igh t be ad ju stable. W ith th e ch ip set d ata book, you will h ave an exp lan ation of all th e con trols in th e Ad van ced Ch ip set Setu p section of th e BIOS Setu p p rogram . Besid es th e m ain ch ip set d ata books, I also recom m en d collectin g an y d ata books on th e oth er m ajor ch ip s in th e system . Th is wou ld in clu d e an y flop p y or IDE con troller ch ip s, Su p er I/ O ch ip s, an d , of cou rse, th e m ain p rocessor. You will fin d an in cred ible am ou n t of in form ation on th ese com p on en ts in th e d ata books.

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Caut ion M ost chipset manufacturers only make a particular chip for a short time, rapidly superseding it with an improved or changed version. The data books are only available during the time the chip is being manufactured, so if you wait too long, you will find that such documents may no longer be available. The time to collect documentation on your motherboard is now !

Using Correct Speed-Rat ed Part s Som e com p atible ven d ors u se su bstan d ard p arts in th eir system s to save m on ey. Becau se th e CPU is on e of th e m ost exp en sive com p on en ts on th e m oth erboard , an d m oth erboard s are sold to system assem blers with ou t th e CPU in stalled , it is tem p tin g for th e assem bler to in stall a CPU rated for less th an th e actu al op eratin g sp eed . A system cou ld be sold as a 266MHz system , for exam p le, bu t wh en you look “u n d er th e h ood ,” you m ay fin d a CPU rated for on ly 233MHz. Th is is called overclocking, an d m an y ven d ors h ave p racticed th is over th e last few years. Som e even go so far as to rem ark th e CPUs, so th at even if you look, th e p art ap p ears to h ave th e correct ratin g. Th e on ly way to stop th at is to p u rch ase system s from kn own reliable ven d ors, an d p rocessors from d istribu tors th at are closely con n ected with th e m an u factu rer. Overclockin g is fin e if you wan t to d o it you rself an d u n d erstan d th e risks, bu t wh en I p u rch ase a system n ew, I exp ect th at all th e p arts in clu d ed be rated to ru n at th e sp eed to wh ich th ey are set. √√ See “ Processor Speed Ratings,” p. 33

W h en a ch ip is ru n at a sp eed h igh er th an it is rated for, it will ru n h otter th an it wou ld n orm ally. Th is m ay cau se th e ch ip to overh eat occasion ally, wh ich wou ld ap p ear as ran d om locku p s, glitch es, an d fru stration . I h igh ly recom m en d th at you ch eck to be su re you are gettin g th e correct sp eed -rated p arts for wh ich you are p ayin g. Also m ake su re th at you u se th e recom m en d ed h eat sin k com p ou n d (th erm al grease). Th is can im p rove th e efficien cy of you r h eat sin k by u p to 30%. Th is p ractice is easy to fall in to becau se th e faster-rated ch ip s cost m ore m on ey, an d In tel an d oth er ch ip m an u factu rers u su ally rate th eir ch ip s very con servatively. Over th e years, I h ave taken several 25MHz 486 p rocessors an d ru n th em at 33MHz, an d th ey seem ed to work fin e. Th e Pen tiu m 166 an d even som e 133 ch ip s I h ave seem to ru n fin e at 200MHz. Alth ou gh I m igh t p u rch ase a Pen tiu m 166 system an d m ake a d ecision to ru n it at 200MHz, if I were to exp erien ce locku p s or glitch es in op eration , I wou ld im m ed iately retu rn it to 166MHz an d retest. If I p u rch ase a 200MHz system from a ven d or, I fu lly exp ect it to h ave 200MHz p arts, n ot 166m Hz p arts ru n n in g p ast th eir rated sp eed ! Th ese d ays, m an y ch ip s will h ave som e form of h eat sin k on th em , wh ich h elp s to p reven t overh eatin g, bu t wh ich can also som etim es cover u p for a “p u sh ed ” ch ip . Fortu n ately, sin ce th e Pen tiu m p rocessor, In tel h as been m arkin g all th eir ch ip s on th e bottom an d th e top .

Knowing What to Look For (Selection Criteria)

Th e p ractice of overclockin g m ay be all bu t over for In tel p rocessor system s. In tel h as recen tly begu n bu ild in g overclock p rotection in to th eir CPUs, wh ich p reven ts th em from ru n n in g at an y sp eed h igh er th an th ey are rated at. Th ey will ru n at lower sp eed s, bu t n ot h igh er on es. Th is was d on e m ain ly to com bat th ose re-m arkin g CPUs an d d eceivin g cu stom ers, alth ou gh , u n fortu n ately, it also p reven ts th ose wh o wan t to from h ot-rod d in g th eir ch ip s. Th e AMD an d Cyrix ch ip s m ay n ot be m arked on th e bottom su ch as In tel’s ch ip s—an d of sp ecial n ote is th at th e in k u sed on th e AMD ch ip s is very easy to wip e off. Becau se m ost AMD ch ip s seem to be cap able of ru n n in g well over th eir rated sp eed , th is h as con tribu ted to a great d eal of rem arkin g of th ose ch ip s. If you p u rch ase an AMD K6 p rocessor or a system with th at p rocessor, verify th at th e m arkin gs are th e origin al AMD m arkin gs an d th at th e sp eed ratin g on th e ch ip is wh at you really p aid for. Th e bottom lin e is if th e p rice is too good to be tru e, ask before you bu y: “Are th e p arts really m an u factu rer-rated for th e system sp eed ?” To d eterm in e th e rated sp eed of a CPU ch ip , look at th e writin g on th e ch ip . Most of th e tim e, th e p art n u m ber will en d in a su ffix of –xxx wh ere th e xxx is a n u m ber in d icatin g th e m axim u m sp eed . For exam p le, –333 in d icates th at th e ch ip is rated for 333MHz op eration .

Caut ion Be careful when running software to detect processor speed. Such programs can only tell you what speed the chip is currently running at, not what the true rating is. Also ignore the speed indicator lights on the front of some cases. These digital displays can literally be set via jumpers to read any speed you desire! They have no true relation to actual system speed. M ost of the better diagnostics on the market such as the Norton Utilities from Symantec will read the processor ID and stepping information. You can consult the processor manufacturer or Chapter 3 for tables listing the various processor steppings to see exactly how yours stacks up.

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Chapter 5

M emory

5

Th is ch ap ter looks at m em ory from both a p h ysical an d logical p oin t of view. W e will first look at wh at m em ory is, wh ere it fits in to th e PC arch itectu re, an d h ow it works. W e will d iscu ss th e d ifferen t typ es of m em ory, sp eed s, an d p ackagin g of th e ch ip s an d m em ory m od u les th at you can p u rch ase an d in stall.

Th e ch ap ter also looks at th e logical layou t of m em ory, d efin in g th e d ifferen t areas an d u ses of th ese areas from th e system ’s p oin t of view. Becau se th e logical layou t an d u ses are with in th e “m in d ” of th e p rocessor, m em ory m ap p in g an d logical layou t rem ain as p erh ap s th e m ost d ifficu lt su bjects to grasp in th e PC u n iverse. Th is ch ap ter con tain s u sefu l in form ation th at rem oves th e m ysteries associated with m em ory an d en ables you to get th e m ost ou t of you r system .

M em ory Basics Mem ory is th e worksp ace for th e com p u ter’s p rocessor. It is a tem p orary storage area wh ere th e p rogram s an d d ata bein g op erated on by th e p rocessor m u st resid e. Mem ory storage is con sid ered tem p orary becau se th e d ata an d p rogram s will rem ain th ere on ly as lon g as th e com p u ter h as electrical p ower or is n ot reset. Before bein g sh u t d own or reset, an y d ata th at h as been ch an ged sh ou ld be saved to a m ore p erm an en t storage d evice of som e typ e (u su ally a h ard d isk) so it can be reload ed in to m em ory again in th e fu tu re. W e often call m em ory RAM, for Ran d om Access Mem ory. Main m em ory is called RAM becau se you can ran d om ly (an d q u ickly) access an y location in m em ory. W h en we talk abou t a com p u ter’s m em ory, we u su ally m ean th e RAM in th e system , m ean in g p rim arily th e m em ory ch ip s or m od u les th at m ake u p th e p rim ary active p rogram an d d ata storage u sed by th e p rocessor. Th is is often con fu sed with th e term “storage,” wh ich sh ou ld be u sed wh en referrin g to th in gs su ch as d isk an d tap e d rives (alth ou gh som e p eop le d o con sid er th em a form of m em ory).

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RAM can refer to both th e p h ysical ch ip s th at m ake u p th e m em ory in th e system , an d th e logical m ap p in g an d layou t of th at m em ory. Logical m ap p in g an d layou t refer to h ow th e m em ory ad d resses are m ap p ed to actu al ch ip s, an d wh at ad d ress location s con tain wh at typ es of system in form ation . Peop le n ew to com p u ters often con fu se m ain m em ory with d isk storage, as both h ave cap acities th at are exp ressed in sim ilar m egabyte or gigabyte term s. Th e best an alogy to exp lain th e relation sh ip between m em ory an d d isk storage I’ve fou n d is to th in k of a sm all office with a d esk an d a file cabin et. In th is p op u lar an alogy, th e file cabin et rep resen ts th e system ’s h ard d isk, wh ere both p rogram s an d d ata are stored for lon g-term safekeep in g. Th e d esktop rep resen ts th e system ’s m ain m em ory, wh ich allows th e p erson workin g at th e d esk (actin g as th e p rocessor) d irect access to an y files p laced on it. To work on a p articu lar file, it first m u st be retrieved from th e cabin et an d p laced on th e d esktop . If th e d esktop is large en ou gh , you m ay be able to h ave several files op en on it at on e tim e; likewise, if you r system h as m ore m em ory, you can ru n m ore or larger p rogram s. Ad d in g h ard d isk sp ace to a system is like p u ttin g a bigger file cabin et in th e office; m ore files can be p erm an en tly stored . Ad d in g m ore m em ory to a system is like gettin g a bigger d esk; you can work on m ore p rogram s an d d ata at th e sam e tim e. On e d ifferen ce between th is an alogy an d th e way th in gs really work in a com p u ter is th at wh en a file is load ed in to m em ory, it is a cop y of th e file th at is actu ally load ed ; th e origin al still resid es on th e h ard d isk. Note th at becau se of th e tem p orary n atu re of m em ory, an y files th at h ave been ch an ged after bein g load ed in to m em ory m u st th en be saved back to th e h ard d isk before th e system is p owered off an d th e m em ory su bseq u en tly cleared . If th e ch an ged file is n ot saved , th en th e origin al cop y of th e file on th e h ard d isk will rem ain u n altered . Th is is like sayin g th at an y ch an ges m ad e to an y files left on th e d esktop will be d iscard ed wh en th e office is closed , alth ou gh th e origin al files th em selves will still be p resen t in th e cabin et. Mem ory tem p orarily stores p rogram s wh en th ey are ru n n in g, alon g with th e d ata bein g u sed by th ose p rogram s. RAM ch ip s are som etim es term ed volatile storage becau se wh en you tu rn off you r com p u ter or an electrical ou tage occu rs, wh atever is stored in RAM is lost u n less you saved it to you r h ard d rive. Becau se of th e volatile n atu re of RAM, m an y com p u ter u sers m ake it a h abit to save th eir work freq u en tly. (Som e software ap p lication s can d o tim ed backu p s au tom atically.) Lau n ch in g a com p u ter p rogram brin gs files in to RAM, an d as lon g as th ey are ru n n in g, com p u ter p rogram s resid e in RAM. Th e CPU execu tes p rogram m ed in stru ction s in RAM, an d also stores resu lts in RAM. RAM stores you r keystrokes wh en you u se a word p rocessor, an d also stores n u m bers u sed in calcu lation s. Tellin g a p rogram to save you r d ata in stru cts th e p rogram to store RAM con ten ts on you r h ard d rive as a file. Ph ysically, th e m ain m em ory in a system is a collection of ch ip s or m od u les con tain in g ch ip s th at are n orm ally p lu gged in to th e m oth erboard . Th ese ch ip s or m od u les vary in

Types of M emory

both th eir electrical an d p h ysical d esign an d m u st be com p atible with th e system in to wh ich th ey are bein g in stalled in ord er to fu n ction p rop erly. In th is ch ap ter, we will d iscu ss th e d ifferen t typ es of ch ip s an d m od u les th at m ay be in stalled in d ifferen t system s. Next to th e p rocessor, m em ory can be on e of th e m ore exp en sive com p on en ts in a m od ern PC, alth ou gh th e total am ou n t sp en t on m em ory for a typ ical system h as d eclin ed over th e last few years. Even after th e p rice d rop s, you sh ou ld still be sp en d in g m ore on th e m em ory for you r system th an th e cost of you r m oth erboard ; in fact, u p to twice as m u ch . Prior to th e m em ory p rice crash in m id -’96, m em ory h ad m ain tain ed a fairly con sisten t p rice for m an y years of abou t $40 p er m egabyte. 16M (a typ ical con figu ration back th en ) cost m ore th an $600. In fact, m em ory was so exp en sive at th at tim e, it was worth m ore th an its weigh t in gold . Th ese h igh p rices cau gh t th e atten tion of crim in als as m em ory m od u le m an u factu rers were robbed at gu n p oin t in several large h eists. Th ese robberies were p artially in d u ced by th e fact th at m em ory was so valu able, th e d em an d was h igh , an d stolen ch ip s or m od u les were virtu ally im p ossible to trace. After th e rash of arm ed robberies an d oth er th efts, m em ory m od u le m an u factu rers began p ostin g arm ed gu ard s an d im p lem en tin g beefed -u p secu rity p roced u res. By th e en d of ’96, m em ory p rices h ad cooled con sid erably to abou t $4 a m eg, a ten fold p rice d rop in less th an a year. Prices con tin u ed to fall after th e m ajor crash an d recen tly h ave reach ed abou t a d ollar an d a h alf p er m eg, or abou t $100 for 64M, a typ ical con figu ration tod ay. Th is m ean s th at ou t of all th e m on ey sp en t on a PC system tod ay, we are n ow in stallin g abou t fou r tim es m ore m em ory in a system com p ared to a few years ago an d , at th e sam e tim e, are sp en d in g abou t 1/ 6 of th e total am ou n t for it. Mem ory m ay cost u s less n ow th an a few years ago, bu t its u sefu l life h as also becom e m u ch sh orter. New typ es of m em ory are bein g ad op ted m ore q u ickly th an before, an d it is n ow m ore likely th at an y n ew system s you p u rch ase will n ot accep t th e sam e m em ory as you r existin g on es. Th is m ean s th at in an u p grad e or rep air situ ation , you will often h ave to ch an ge th e m em ory if you ch an ge th e m oth erboard . Th e ch an ce th at you can reu se th e m em ory in an existin g m oth erboard wh en u p grad in g to a n ew on e is slim . Th is is likely to con tin u e in th e fu tu re, m ean in g th at th e system or u p grad e m oth erboard you p u rch ase n ext year will m ost likely n ot be able to u se th e m em ory in you r cu rren t system s. Becau se of th is, it is im p ortan t to u n d erstan d all th e d ifferen t typ es of m em ory on th e m arket tod ay, so you can best d eterm in e wh ich typ es are req u ired by wh ich system s, an d th u s m ore easily p lan for fu tu re u p grad es an d rep airs.

Types of M em ory To better u n d erstan d p h ysical m em ory in a system , it is n ecessary to see wh ere an d h ow it fits in to th e system . Th ree m ain typ es of p h ysical m em ory u sed in m od ern PCs are ■ ROM. Read On ly Mem ory ■ DRAM. Dyn am ic Ran d om Access Mem ory ■ SRAM. Static RAM

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ROM Read On ly Mem ory, or ROM, is a typ e of m em ory th at can p erm an en tly or sem ip erm an en tly h old d ata. It is called read -on ly becau se it is eith er im p ossible or d ifficu lt to write to. ROM is also often referred to as n on -volatile m em ory becau se an y d ata stored in ROM will rem ain , even if th e p ower is tu rn ed off. As su ch , ROM is an id eal p lace to p u t th e PC’s startu p in stru ction s—th at is, th e software th at boots th e system . Note th at ROM an d RAM are n ot op p osites, as som e p eop le seem to believe. In fact, ROM is tech n ically a su bset of th e system ’s RAM. In oth er word s, a p ortion of th e system ’s Ran d om Access Mem ory ad d ress sp ace is m ap p ed in to on e or m ore ROM ch ip s. Th is is n ecessary to con tain th e software th at en ables th e PC to boot u p ; oth erwise, th e p rocessor wou ld h ave n o p rogram in m em ory to execu te wh en it was p owered on . ◊◊ See “ The Boot Process,” p. 1042

For exam p le, wh en a PC is tu rn ed on , th e p rocessor au tom atically ju m p s to ad d ress FFFF0h , exp ectin g to fin d in stru ction s to tell th e p rocessor wh at to d o. Th is location is exactly 16 bytes from th e en d of th e first m egabyte of RAM sp ace, an d th e en d of th e ROM. If th is location was m ap p ed in to regu lar m em ory ch ip s, an y d ata stored th ere wou ld h ave d isap p eared wh en th e p ower was tu rn ed off p reviou sly, an d th e p rocessor wou ld su bseq u en tly fin d n o in stru ction s to ru n th e n ext tim e p ower was tu rn ed on . By p lacin g a ROM ch ip at th is ad d ress, a system startu p p rogram can be p erm an en tly load ed in to th e ROM an d will be available every tim e th e system is tu rn ed on . ◊◊ For more information about Dynamic RAM , see “ DRAM ,” p. 311

Norm ally, th e system ROM will start at ad d ress F0000h , wh ich is 64K p rior to th e en d of th e first m egabyte. Becau se th e ROM ch ip is n orm ally 64K in size, th e ROM p rogram s occu p y th e en tire last 64K of th e first m egabyte, in clu d in g th e critical FFFF0h startu p in stru ction ad d ress. Som e th in k it stran ge th at th e PC wou ld start execu tin g in stru ction s 16 bytes from th e en d of th e ROM, bu t th is d esign was in ten tion al. All th e ROM p rogram m er h as to d o is p lace a JMP (ju m p ) in stru ction at th at ad d ress, wh ich in stru cts th e p rocessor to ju m p to th e actu al begin n in g of th e ROM—in m ost cases close to F0000h , wh ich is abou t 64K earlier in th e m em ory m ap . It’s kin d of like d ecid in g to read every book startin g 16 p ages from th e en d , an d th en h avin g all book p u blish ers agree to p lace an in stru ction th ere to ju m p back th e n ecessary n u m ber of p ages to get to p age 1. By settin g th e startu p location in th is way, In tel allowed th e ROM to grow to be an y size, all th e wh ile keep in g it at th e u p p er en d of ad d resses in th e first m egabyte of th e m em ory ad d ress sp ace. Th e m ain ROM BIOS is con tain ed in a ROM ch ip on th e m oth erboard , bu t th ere are also ad ap ter card s with ROMs on th em as well. ROMs on ad ap ter card s con tain au xiliary BIOS rou tin es an d d rivers n eed ed by th e p articu lar card , esp ecially for th ose card s th at m u st be active early in th e boot p rocess, su ch as vid eo card s. Card s th at d on ’t n eed d rivers active

Types of M emory

at boot tim e will n orm ally n ot h ave a ROM becau se th ose d rivers can be load ed from th e h ard d isk later in th e boot p rocess. Th e m oth erboard ROM n orm ally con tain s fou r m ain p rogram s, in clu d in g th e followin g in m ost system s: ■ POST. Power-On Self Test. A series of test rou tin es th at en su re th e system com p on en ts are op eratin g p rop erly. ■ CMOS Setup. A m en u -d riven ap p lication th at allows th e u ser to set system con figu ration p aram eters, op tion s, secu rity settin gs, an d p referen ces. ■ Bootstrap Loader. Th e rou tin e th at first scan s th e flop p y d rive an d th en th e h ard d isk, lookin g for an op eratin g system to load . ■ BIOS. Basic In p u t/ Ou tp u t System . A series of d evice d river p rogram s d esign ed to p resen t a stan d ard in terface to th e basic system h ard ware, esp ecially h ard ware th at m u st be active d u rin g th e boot p rocess. Becau se th e BIOS is th e m ain p ortion of th e cod e stored in ROM, we often call th e ROM th e ROM BIOS. In old er PCs, th e m oth erboard ROM BIOS cou ld con sist of u p to five or six total ch ip s, bu t m ost PCs h ave req u ired on ly a sin gle ch ip for m an y years n ow. For m ore in form ation on th e m oth erboard ROM, see Ch ap ter 4, “Moth erboard s an d Bu ses.” Ad ap ter card s th at req u ire startu p d rivers also h ave ROMs on th em . Th is in clu d es card s su ch as vid eo card s, m ost SCSI (Sm all Com p u ter System s In terface) card s, En h an ced IDE con troller card s, an d som e Network card s. Th e ROM ch ip on th ese card s con tain s d rivers an d startu p p rogram s th at will be execu ted by th e m oth erboard ROM at boot tim e. Th is, for exam p le, is h ow a vid eo card can be recogn ized an d in itialized , even th ou gh you r m oth erboard ROM d oes n ot con tain sp ecific d rivers for it. You wou ld n ’t wan t to load th e in itial VGA m od e d rivers from d isk becau se th e screen wou ld rem ain d ark u n til th ose d rivers were load ed . W h at h ap p en s is th e m oth erboard ROM scan s a sp ecial ad ap ter ROM area of RAM (ad d resses C0000-DFFFFh ), lookin g for a 55AAh sign atu re byte p air th at in d icates th e start of a ROM. Th e m oth erboard BIOS au tom atically ru n s th e p rogram s in an y ad ap ter ROMs it fin d s d u rin g th e scan . You see th is in m ost system s wh en you tu rn you r system on , an d d u rin g th e POST you see th e vid eo card BIOS in itialize an d an n ou n ce its p resen ce. ROM ch ip s are very slow by n atu re, with n orm al access tim es of 150n s (n an osecon d s, or billion th s of a secon d ; for m ore in form ation , see th e Mem ory Sp eed section later in th is ch ap ter), com p ared to DRAM access tim es of 60n s or less. Du e to th is fact, in m an y system s th e ROMs are shadowed, wh ich m ean s th ey are cop ied in to DRAM ch ip s at startu p to allow faster access d u rin g n orm al op eration . Th e sh ad owin g p roced u re cop ies th e ROM in to RAM, an d th en assign s th at RAM th e sam e ad d ress as th e ROM origin ally u sed , d isablin g th e actu al ROM in th e p rocess. Th is m akes th e system seem like it h as 60n s (or wh atever th e RAM sp eed is) ROM. Th e p erform an ce gain from sh ad owin g is often very sligh t, an d it can cau se p roblem s if n ot set u p p rop erly, so in m ost cases it is wise to sh ad ow on ly th e m oth erboard an d m aybe vid eo card BIOS, an d leave th e oth ers alon e.

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Sh ad owin g is m ostly u sefu l on ly if you are ru n n in g 16-bit op eratin g system s su ch as DOS or W in d ows 3.x. If you are ru n n in g a 32-bit op eratin g system su ch as W in d ows 95, W in d ows 98, or W in d ows NT, th en sh ad owin g is virtu ally u seless becau se th ose op eratin g system s d o n ot u se th e 16-bit ROM cod e wh ile ru n n in g. In stead , th ose op eratin g system s load 32-bit d rivers in to RAM, wh ich rep lace th e 16-bit BIOS cod e u sed on ly d u rin g system startu p . Sh ad owin g con trols are fou n d in th e CMOS Setu p p rogram in th e m oth erboard ROM, wh ich is covered in m ore d etail in Ch ap ter 4. Fou r d ifferen t typ es of ROM ch ip s are ■ ROM. Read On ly Mem ory ■ PROM. Program m able ROM ■ EPROM. Erasable PROM ■ EEPROM. Electrically Erasable PROM, also called a flash ROM No m atter wh ich typ e of ROM you u se, th e d ata stored in a ROM ch ip is n on -volatile an d will rem ain in d efin itely u n less in ten tion ally erased or overwritten . Table 5.1 lists th e id en tifyin g p art n u m bers typ ically u sed for each typ e of ROM ch ip alon g with an y oth er id en tifyin g in form ation . Table 5.1

ROM Chip Part Num bers

ROM Type

Part Num ber

ROM

No longer in use

PROM

27nnnn

EPROM

27nnnn

EEPROM

28xxxx or 29xxxx

Ot her

Quartz window

M ask ROM Origin ally, m ost ROMs were m an u factu red with th e 0s an d 1s alread y “cast in ” or in tegrated in to th e d ie. Th e d ie rep resen ts th e actu al silicon ch ip . Th ese are called m ask ROMs, becau se th e d ata is form ed in to th e m ask from wh ich th e ROM d ie is p h otolith ograp h ically p rod u ced . Th is typ e of m an u factu rin g m eth od is econ om ical if you are m akin g h u n d red s of th ou san d s of ROMs with th e exact sam e in form ation . If you h ave to ch an ge a sin gle bit, h owever, you m u st rem ake th e m ask, wh ich is an exp en sive p rop osition . Du e to costs an d in flexibility, n obod y u ses m ask ROMs an ym ore. PROM PROMs are a typ e of ROM th at is blan k wh en n ew an d m u st be p rogram m ed with wh atever d ata you wan t. Th e PROM was in ven ted in th e late ’70s by Texas In stru m en ts, an d h as been available in sizes from 1K (8K bits) to 2M (16M bits) or m ore. Th ey can be id en tified by th eir p art n u m bers, wh ich are u su ally 27n n n n , wh ere th e 27 in d icates th e TI typ e PROM an d th e n n n n in d icates th e size of th e ch ip in Kbits. For exam p le, m ost PCs

Types of M emory

th at u sed PROMs cam e with 27512 or 271000 ch ip s, wh ich in d icate 512K bits (64K bytes) or 1M bits (128K bytes).

Not e M y ’89 Pontiac Turbo Trans Am came with an onboard computer containing a 2732 PROM , which was a 32Kbit (4K byte) chip in the ECM (Electronic Control M odule or vehicle computer) under the dash. This chip contained a portion of the vehicle operating software and all the data tables describing spark advance, fuel delivery, and other engine and vehicle operating parameters. M any devices with integrated computers use PROM s to store their operating programs.

Alth ou gh we say th ese ch ip s are blan k wh en n ew, th ey are tech n ically p reload ed with bin ary 1s. In oth er word s, a 1Mbit ROM ch ip u sed in a m od ern PC wou ld com e with 1 m illion (actu ally 1,048,576) bit location s, each con tain in g a bin ary 1. A blan k PROM can th en be p rogram m ed , wh ich is th e act of writin g to it. Th is n orm ally req u ires a sp ecial m ach in e called a Device Program m er, ROM Program m er, or ROM bu rn er (see Figu re 5.1). W e som etim es refer to p rogram m in g th e ROM as “bu rn in g” it becau se th at is tech n ically an ap t d escrip tion of th e p rocess. Each bin ary 1 bit can be th ou gh t of as a fu se th at is in tact. Most ch ip s ru n on 5 volts, bu t wh en we p rogram a PROM, we p lace a h igh er voltage (n orm ally 12 volts) at th e variou s ad d resses with in th e ch ip . Th is h igh er voltage actu ally blows or bu rn s th e fu ses at th e location s we d esire, th u s tu rn in g an y given 1 in to a 0. Alth ou gh we can tu rn a 1 in to a 0, you sh ou ld n ote th at th e p rocess is irreversible; th at is, we can n ot tu rn a 0 back in to a 1. Th e p rogram m er d evice exam in es th e p rogram you wan t to write in to th e ch ip , an d th en selectively ch an ges on ly th e 1s to 0s wh ere n ecessary in th e ch ip . PROM ch ip s are often referred to as OTP (On e Tim e Program m able) ch ip s for th is reason . Th ey can be p rogram m ed on ce, an d n ever erased . Most PROMs are very in exp en sive, on th e ord er of $3 for a typ ical PC m oth erboard PROM, so if you wan ted to ch an ge th e p rogram in a PROM, you d iscard it an d p rogram a fresh on e with th e n ew d ata.

KE/EPROM/P AL/GANG/SE T PROGRAMM ER

SKT 1

SKT 2

SKT 3

SKT 4

FIG. 5.1 Typ ical Gan g (m u lti-socket) Device Program m er (PROM Bu rn er).

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Th e act of p rogram m in g a PROM takes an ywh ere from a few secon d s to a few m in u tes, d ep en d in g on th e size of th e ch ip an d th e algorith m u sed by th e p rogram m in g d evice. Figu re 5.1 sh ows a typ ical PROM p rogram m er th at h as m u ltip le sockets. Th is is called a gan g-p rogram m er an d can p rogram several ch ip s at on ce, savin g tim e if you h ave several ch ip s to write with th e sam e d ata. Less exp en sive p rogram m ers are available with on ly on e socket, wh ich is fin e for m ost in d ivid u al u se. I u se an d recom m en d a very in exp en sive p rogram m er from a com p an y called An d rom ed a Research (see Ap p en d ix A, “Ven d or List”). Besid es bein g econ om ical, th eir u n it h as th e ad van tage of con n ectin g to a PC via th e p arallel p ort for fast an d easy d ata tran sfer of files between th e PC an d th e p rogram m in g u n it. Th eir u n it is also p ortable an d com es bu ilt in to a con ven ien t carryin g case. It is op erated by an in clu d ed m en u -d riven p rogram th at you in stall on th e con n ected PC. Th e p rogram con tain s several featu res, in clu d in g a fu n ction th at allows you to read th e d ata from a ch ip an d save it in a file on you r system ; you can also write a ch ip from a d ata file, verify a ch ip m atch es a file, an d verify a ch ip is blan k before p rogram m in g begin s. Ch ap ter 4 sh ows h ow I u sed m y PROM p rogram m er to m od ify th e BIOS in som e of m y old er PCs. W ith tod ay’s system s p rim arily u sin g flash ROMs, th is cap ability is som ewh at lim ited , bu t I in clu d e th e in form ation becau se I th in k it is very in terestin g.

Not e I even used my PROM programmer to reprogram the PROM in my ’89 Turbo Trans Am, changing the factory preset speed and rpm limiters, turbocharger boost, torque converter lockup points, spark advance, fuel delivery, idle speed, and much more! I also incorporated a switch box under the dash that allows me to switch among four different chips even while the vehicle is running. One chip I created I call the “ valet chip,” which when engaged will cut off the fuel injectors at a preset speed of 36 miles per hour, and restart them when the vehicle coasts down to 35 mph. I imagine this type of modification would be useful for those with teenagers driving, as you could set the mph or engine rpm limit to whatever you want! Another chip I created cuts off all fuel to the engine altogether, which I engage when the vehicle is parked, for security purposes. No matter how clever, a thief will not be able to steal this car unless they tow it away. If you are interested in such a chip-switching device or custom chips for your Turbo Trans Am or Buick Grand National, contact Casper’s Electronics (see the vendor list in Appendix A). For other vehicles with replaceable PROM s, companies such as Superchips, Hypertech, and Evergreen offer custom PROM s for improved performance (see Appendix A). I installed a Superchips chip in a Ford Explorer I had and it made a dramatic improvement in engine operation and vehicle performance.

EPROM On e variation of th e PROM th at h as been very p op u lar is th e EPROM. An EPROM is a PROM th at is erasable. An EPROM ch ip can be easily recogn ized by th e clear q u artz crystal win d ow set in th e ch ip p ackage d irectly over th e d ie. You can actu ally see th e d ie th rou gh th e win d ow! EPROMs h ave th e sam e 27xxxx p art n u m berin g sch em e as th e stan d ard PROM, an d are fu n ction ally an d p h ysically id en tical excep t for th e clear q u artz win d ow above th e d ie.

Types of M emory

Th e p u rp ose of th e win d ow is to allow u ltraviolet ligh t to reach th e ch ip d ie, becau se th e EPROM is erased by exp osu re to in ten se UV ligh t. Th e win d ow is q u artz crystal becau se regu lar glass will block UV ligh t. You can ’t get a su n tan th rou gh a win d ow! Th e q u artz win d ow m akes th e EPROMS m ore exp en sive th an th e OTP PROMs. Th is extra exp en se is n eed less if erasability is n ot im p ortan t. Th e UV ligh t erases th e ch ip by cau sin g a ch em ical reaction th at essen tially m elts th e fu ses back togeth er! Th u s, an y bin ary 0s in th e ch ip becom e 1s, an d th e ch ip is restored to n ew con d ition with bin ary 1s in all location s. To work, th e UV exp osu re m u st be at a sp ecific wavelen gth (2,537 an gstrom s), at a fairly h igh in ten sity (12,000 u w/ cm 2), in close p roxim ity (2–3cm or abou t 1 in ch ), an d last for between 5 an d 15 m in u tes d u ration . An EPROM eraser (see Figu re 5.2) is a d evice th at con tain s a UV ligh t sou rce (u su ally a su n lam p -typ e bu lb) above a sealed com p artm en t d rawer wh ere you p lace th e ch ip or ch ip s.

FIG. 5.2 A p rofession al EPROM eraser. Figu re 5.2 sh ows a p rofession al-typ e EPROM eraser th at can h an d le u p to 50 ch ip s at a tim e. I u se a m u ch sm aller an d less exp en sive on e called th e DataRase by W allin g Co. (see th e ven d or list). Th is d evice erases u p to fou r ch ip s at a tim e an d is both econ om ical an d p ortable. Th e q u artz crystal win d ow on an EPROM is n orm ally covered by tap e, wh ich p reven ts accid en tal exp osu re to UV ligh t. Th ere is UV ligh t in su n ligh t, of cou rse, an d even in stan d ard room ligh tin g, su ch th at over tim e a ch ip exp osed to th e ligh t m ay begin to d egrad e. For th is reason , after a ch ip is p rogram m ed , it is a good id ea to p u t a sticker over th e win d ow to p rotect it. EEPROM / Flash ROM A n ewer typ e of ROM is th e EEPROM, wh ich stan d s for Electrically Erasable PROM. Th ese ch ip s are also called flash ROMs, an d are ch aracterized by th eir cap ability to be erased an d rep rogram m ed d irectly in th e circu it board in wh ich th ey are in stalled , with n o

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sp ecial eq u ip m en t req u ired . By u sin g an EEPROM or flash ROM, it is p ossible to erase an d rep rogram th e m oth erboard ROM in a PC with ou t rem ovin g th e ch ip from th e system , or even op en in g u p th e system ch assis! W ith a flash ROM or EEPROM, you d on ’t n eed a UV eraser or d evice p rogram m er to p rogram or erase ch ip s. Not on ly d o virtu ally all PC m oth erboard s bu ilt sin ce 1994 u se flash ROMs or EEPROMs, m ost au tom obiles bu ilt sin ce th en also u se th em as well. For exam p le, m y ’94 Ch evy Im p ala SS h as a PCM (Powertrain Con trol Mod u le) with an in tegral flash ROM. Th e EEPROM or flash ROM can be id en tified by a 28xxxx or 29xxxx p art n u m ber, an d th e lack of a win d ow on th e ch ip . Havin g an EEPROM or flash ROM in you r PC m oth erboard m ean s you can n ow easily u p grad e th e m oth erboard ROM with ou t h avin g to swap ch ip s. In m ost cases, you will d own load th e u p d ated ROM from th e m oth erboard m an u factu rer’s W eb site, an d th en ru n a sp ecial p rogram th ey p rovid e to u p d ate th e ROM. Th is p roced u re is d escribed in m ore d etail in Ch ap ter 4. √√ See “ Upgrading the ROM BIOS,” p. 215

It is recom m en d ed th at you p eriod ically ch eck with you r m oth erboard m an u factu rer to see wh eth er an u p d ated BIOS is available for you r system . An u p d ated BIOS m ay con tain bu g fixes or en able n ew featu res n ot origin ally fou n d in you r system . For exam p le, you m igh t fin d fixes for a p oten tial Year 2000 d ate p roblem or n ew d rivers to su p p ort bootin g from LS-120 (120M flop p y) d rives. ◊◊ See “ LS-120 (120M ) Floptical Drives,“ p. 798

Not e For the auto enthusiasts out there, you might want to do the same for your car; that is, check to see if ROM upgrades are available for your vehicle’s computer. Now that updates are so easy and inexpensive, vehicle manufacturers are releasing bug-fix ROM upgrades for cars that correct operational problems or improve vehicle performance. In most cases, you will have to check with your dealer to see whether any new vehicle ROM s are available. If you have a GM car, GM has a site on the Web where you can get information about the BIOS revisions available for your car, which they call Vehicle Calibrations. The GM Vehicle Calibration Information site address is as follows:

ht t p:/ / 207.74.147.14/ vci/ When you enter your VIN (Vehicle Identification Number), this page displays the calibration history for the vehicle, which is a list of all the different flash ROM upgrades (calibrations) developed since the vehicle was new. For example, when I entered the VIN on my ’94 Impala, I found that there have been five different flash ROM calibrations over the years, and my car had only the second revision installed originally, meaning there had been three newer ROM s than the one I had! The fixes in the various calibration updates are listed also. A trip to the dealer with this information allowed them to use their diagnostic computer to connect to my car and reflash the PCM with the latest software, which, in my case, fixed several problems including engine surging under specific

Types of M emory

conditions, shift clunks, erroneous “ check engine” light warnings, and several other minor problems. With the flash ROM capability, I began experimenting with running calibrations originally intended for other vehicles and now, in fact, run a modified Camaro calibration loaded into the flash ROM in my Impala. The spark advance curve and fuel delivery parameters are much more aggressive in the Camaro calibration, as are the transmission shift points and other features. If you are interested in having a custom program installed in your flash ROM -equipped vehicle, I recommend you contact Wright Automotive or Evergreen Performance (see the vendor list).

Th ese d ays, m an y objects with em bed d ed com p u ters con trollin g th em are u sin g flash ROMs. Pretty soon you ’ll be takin g you r toaster in for flash ROM u p grad es! Th e m eth od for locatin g an d u p d atin g you r PC m oth erboard flash ROMs is sh own in Ch ap ter 4. Oth er d evices m ay h ave flash ROMs, as well—for exam p le, I h ave u p d ated th e flash ROMs in m y Motorola ISDN m od em an d in m y Kod ak d igital cam era. Both of th ese item s h ad m in or q u irks th at were fixed by u p d atin g th eir in tern al ROM cod e, wh ich was as easy as d own load in g a file from th eir resp ective W eb sites an d ru n n in g th e u p d ate p rogram in clu d ed in th e file. Flash ROMs are also freq u en tly u sed to ad d n ew cap abilities to p erip h erals or u p d ate p erip h erals su ch as m od em s to th e latest stan d ard s, su ch as u p d atin g a m od em from X2 or Kflex to v.90. DRAM Dyn am ic RAM is th e typ e of m em ory ch ip u sed for m ost of th e m ain m em ory in a m od ern PC. Th e m ain ad van tages of DRAM is th at it is very d en se, m ean in g you can p ack a lot of bits in to a very sm all ch ip , an d it is very in exp en sive, wh ich m akes it afford able for large am ou n ts of m em ory. Th e m em ory cells in a DRAM ch ip are tin y cap acitors th at retain a ch arge to in d icate a bit. Th e p roblem with DRAM is th at it is d yn am ic, an d becau se of th e d esign m u st be con stan tly refreshed or th e electrical ch arges in th e in d ivid u al m em ory cap acitors will d rain an d th e d ata will be lost. Refresh occu rs wh en th e system m em ory con troller takes a tin y break an d accesses all th e rows of d ata in th e m em ory ch ip s. Most system s h ave a m em ory con troller (n orm ally bu ilt in to th e m oth erboard ch ip set), wh ich is set for an in d u stry-stan d ard refresh rate of 15µs (m icrosecon d s). Th e m em ory is accessed in su ch a way th at all rows of d ata will be accessed after exactly 128 of th ese sp ecial refresh cycles. Th is m ean s th at every 1.92m s (m illisecon d s or 128×15µsec), all th e rows in th e m em ory are read to refresh th e d ata. √√ See “ Chipsets,” p. 183

Refresh in g th e m em ory u n fortu n ately takes p rocessor tim e away from oth er tasks becau se each refresh cycle takes several CPU cycles to com p lete. In old er system s, th e refresh cyclin g cou ld take u p to 10% or m ore of th e total CPU tim e, bu t with m od ern system s ru n n in g in th e h u n d red s of m egah ertz, refresh overh ead is n ow on th e ord er of

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1% or less of th e total CPU tim e. Som e system s allow you to alter th e refresh tim in g p aram eters via th e CMOS Setu p , bu t be aware th at in creasin g th e tim e between refresh cycles to sp eed u p you r system can allow som e of th e m em ory cells to begin d rain in g, wh ich can cau se ran d om soft m em ory errors to ap p ear. A soft error is a d ata error th at is n ot cau sed by a d efective ch ip . It is safer to stick with th e recom m en d ed or d efau lt refresh tim in g in m ost cases. Becau se refresh con su m es less th an 1% of m od ern system overall ban d wid th , alterin g th e refresh rate h as little effect on p erform an ce. DRAMs u se on ly on e tran sistor an d cap acitor p air p er bit, wh ich m akes th em very d en se, offerin g a lot of m em ory cap acity p er ch ip th an oth er typ es of m em ory. Th ere are cu rren tly DRAM ch ip s available with d en sities of u p to 256Mbits or m ore. Th is m ean s th at th ere are DRAM ch ip s with 256 m illion or m ore tran sistors! Com p are th is to a Pen tiu m II, wh ich h as 7.5 m illion tran sistors, an d it m akes th e p rocessor look wim p y by com p arison . Th e d ifferen ce is th at in a m em ory ch ip , th e tran sistors an d cap acitors are all con sisten tly arran ged in a (n orm ally sq u are) grid of very sim p le rep etitive stru ctu res, u n like th e p rocessor, wh ich is a m u ch m ore com p lex circu it of d ifferen t stru ctu res an d elem en ts in tercon n ected in a h igh ly irregu lar fash ion . At least on e m an u factu rer is workin g on ch ip s, in ten d ed for th e 2001-2002 tim efram e, with 256-gigabit d en sities u sin g circu it lin e wid th s of 0.05 m icron , in d icatin g th at m em ory d en sities will con tin u e to rise as th ey h ave been for years. Th e tran sistor for each DRAM bit cell is u sed to read th e ch arge state of th e ad jacen t cap acitor. If th e cap acitor is ch arged , th e cell is read to con tain a 1; n o ch arge in d icates a 0. Th e ch arge in th e tin y cap acitors is con stan tly d rain in g, wh ich is wh y th e m em ory m u st be refresh ed con stan tly. Even a m om en tary p ower in terru p tion , or an yth in g th at in terferes with th e refresh cycles, will cau se a DRAM m em ory cell to lose th e ch arge an d th erefore th e d ata. DRAM is u sed in PC system s becau se it is in exp en sive an d th e ch ip s can be d en sely p acked , m ean in g th at a lot of m em ory cap acity can fit in a sm all sp ace. Un fortu n ately, DRAM is also slow, n orm ally m u ch slower th an th e p rocessor. For th is reason , th ere h ave been m an y d ifferen t typ es of DRAM arch itectu res d evelop ed to im p rove p erform an ce.

M em ory Speeds Th e sp eed an d p erform an ce issu e with m em ory is con fu sin g to som e becau se m em ory sp eed is u su ally exp ressed in n s (n an osecon d s), wh ile p rocessor sp eed is exp ressed in MHz (m egah ertz). A n an osecon d is d efin ed as on e billion th of a secon d —a very sh ort tim e in d eed . To p u t som e p ersp ective on th at, n ote th at th e sp eed of ligh t is 186,282 m iles (299,792 kilom eters) p er secon d in a vacu u m . In on e billion th of a secon d , a beam of ligh t wou ld travel a m ere 11.80 in ch es or 29.98 cen tim eters, less th an th e len gth of a typ ical ru ler! Ch ip an d system sp eed h as been exp ressed in m egah ertz (MHz), wh ich is m illion s of cycles p er secon d . Th ere are system s tod ay with p rocessors ru n n in g 500MHz or faster,

M emory Speeds

an d we sh ou ld see gigah ertz (GHz or billion s of cycles p er secon d ) sp eed s with in a few years. Becau se it is con fu sin g to sp eak in th ese d ifferen t term s for sp eed s, I th ou gh t it wou ld be in terestin g to see h ow th ey com p are. Table 5.2 sh ows th e relation sh ip between n an osecon d s (n s) an d m egah ertz (MHz) for th e sp eed s associated with PCs tod ay. Table 5.2

The Relat ionship Bet w een Clock Speeds in M egahert z ( M Hz) t o

Cycle Tim es in Nanoseconds ( ns) Clock Speed

Cycle Tim e

Clock Speed

Cycle Tim e

6M Hz

166ns

120M Hz

8.3ns

8M Hz

125ns

133M Hz

7.5ns

10M Hz

100ns

150M Hz

6.6ns

12M Hz

83ns

166M Hz

6.0ns

16M Hz

62ns

180M Hz

5.5ns

20M Hz

50ns

200M Hz

5.0ns

25M Hz

40ns

233M Hz

4.2ns

33M Hz

30ns

250M Hz

4.0ns

40M Hz

25ns

300M Hz

3.3ns

50M Hz

20ns

333M Hz

3.0ns

60M Hz

16ns

350M Hz

2.8ns

66M Hz

15ns

400M Hz

2.5ns

75M Hz

13ns

450M Hz

2.2ns

80M Hz

12ns

500M Hz

2.0ns

100M Hz

10ns

550M Hz

1.8ns

As you can see from th is table, as clock sp eed s in crease, cycle tim e d ecreases. If you exam in e th is table, you can clearly see th at th e DRAM m em ory u sed in th e typ ical PC for m an y years is totally in ad eq u ate wh en com p ared to p rocessor sp eed s of 400MHz an d h igh er. Note th at u n til recen tly, m ost DRAM m em ory u sed in PCs h as been rated at an access tim e of 60n s, wh ich works ou t to be on ly abou t 16.7MHz! Con sid er th at th is su p er slow m em ory h as been in stalled in system s ru n n in g u p to 300MHz or faster; you can see wh at a m ism atch th ere is between p rocessor an d m ain m em ory p erform an ce. System m em ory tim in g is a little m ore in volved th an con vertin g n an osecon d s to m egah ertz. Becau se th e tran sistors for each bit in a m em ory ch ip are m ost efficien tly arran ged in a grid , each tran sistor is accessed by u sin g a row an d colu m n sch em e. All m em ory accesses in volve first selectin g a row ad d ress, th en a colu m n ad d ress, an d th en tran sferrin g th e d ata. Th e in itial setu p for a m em ory tran sfer wh ere th e row an d colu m n ad d resses are selected is a n ecessary overh ead n orm ally referred to as latency. Th e access tim e for m em ory is th e cycle tim e p lu s laten cy for selectin g th e row an d colu m n ad d resses. For exam p le, m em ory rated at 60n s n orm ally h as a laten cy of abou t 25n s (to select th e row an d colu m n ad d ress) an d a cycle tim e of abou t 35n s to actu ally tran sfer

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th e d ata. Th u s, th e tru e m em ory clock rate in a system with 60n s m em ory wou ld be on th e ord er of 28.5MHz (35n s = 28.5MHz). Even so, a sin gle m em ory tran sfer will still req u ire a fu ll 60n s, so con secu tive tran sfers will h ap p en at a rate of on ly 16.7MHz (60n s) becau se of th e ad d ed laten cy. W h at h ap p en s wh en a 300MHz p rocessor is tryin g to read m u ltip le bytes of d ata from 16MHz m em ory? Th e an swer is a lot of wait states! A wait state is an ad d ition al “d on oth in g” cycle th at th e p rocessor m u st execu te wh ile waitin g for th e d ata to becom e read y. In th e case with m em ory cyclin g every 60n s (16MHz) an d a p rocessor cyclin g every 3n s (300MHz), th e p rocessor wou ld h ave to execu te ap p roxim ately 19 wait states before th e d ata wou ld be read y on th e 20 th cycle. Ad d in g wait states in th is fash ion effectively slows th e p rocessin g sp eed to th at of th e m em ory, or 16MHz in th is exam p le. To red u ce th e n u m ber of wait states req u ired , th ere are several typ es of faster m em ory an d cach e available, all of wh ich are d iscu ssed in th is ch ap ter. Fast Page M ode ( FPM ) DRAM Stan d ard DRAM is accessed via a tech n iq u e called paging. Norm al m em ory access req u ires th at a row an d colu m n ad d ress be selected , wh ich takes tim e. Pagin g allows for faster access to all th e d ata with in a given row of m em ory by keep in g th e row ad d ress th e sam e an d ch an gin g on ly th e colu m n . Mem ory th at u ses th is tech n iq u e is called Page Mode or Fast Page Mode m em ory. Oth er variation s on Page Mod e were called Static Colu m n or Nibble Mod e m em ory. Paged m em ory is a sim p le sch em e for im p rovin g m em ory p erform an ce th at d ivid es m em ory in to p ages ran gin g from 512 bytes to a few kilobytes lon g. Th e p agin g circu itry th en en ables m em ory location s with in a p age to be accessed with fewer wait states. If th e d esired m em ory location is ou tsid e th e cu rren t p age, on e or m ore wait states are ad d ed wh ile th e system selects th e n ew p age. To im p rove fu rth er on m em ory access sp eed s, system s h ave evolved to allow for faster access to DRAM. On e of th e m ore sign ifican t ch an ges was th e im p lem en tation of bu rst m od e access in th e 486 an d later p rocessors. Bu rst m od e cyclin g takes ad van tage of th e fact th at m ost m em ory accesses are con secu tive in n atu re. After settin g u p th e row an d colu m n ad d resses for a given access, u sin g bu rst m od e, on e can th en access th e n ext th ree ad jacen t ad d resses with n o ad d ition al laten cy or wait states. A bu rst access is n orm ally lim ited to fou r total accesses. To d escribe th is, we often refer to th e tim in g in th e n u m ber of cycles for each access. A typ ical bu rst m od e access of stan d ard DRAM wou ld be exp ressed as x-y-y-y, wh ere x is th e tim e for th e first access (laten cy p lu s cycle tim e) an d y rep resen ts th e n u m ber of cycles req u ired for each con secu tive access. Stan d ard 60n s DRAM n orm ally ru n s 5-3-3-3 bu rst m od e tim in g. Th is m ean s th e first access takes a total of five cycles (on a 66MHz system bu s, th is wou ld be abou t 75n s total or 5×15n s cycles), wh ile th e con secu tive cycles take th ree cycles each (3×15n s = 45n s). As you can see, th e actu al system tim in g is som ewh at less th an th e m em ory is tech n ically rated for. Note th at with ou t th e bu rstin g tech n iq u e, m em ory access wou ld be 5-5-5-5 becau se th e fu ll laten cy wou ld be n eed ed for each m em ory tran sfer.

M emory Speeds

DRAM m em ory th at su p p orts p agin g an d th is bu rstin g tech n iq u e is called Fast Page Mode (FPM) m em ory. Th e term com es from th e fact th at m em ory accesses to d ata on th e sam e p age can be d on e with less laten cy. Most 486 an d n ewer system s u se FPM m em ory, wh ile old er system s u sed con ven tion al DRAM. An oth er tech n iq u e for sp eed in g u p FPM m em ory was a tech n iq u e called interleaving. Th is is a d esign wh ere two sep arate ban ks of m em ory are u sed togeth er, altern atin g access from on e to th e oth er as even an d od d bytes. W h ile on e is bein g accessed , th e oth er is bein g p rech arged , wh ere th e row an d colu m n ad d resses are bein g selected . Th en , by th e tim e th e first ban k in th e p air is fin ish ed retu rn in g d ata, th e secon d ban k in th e p air is fin ish ed with th e laten cy p art of th e cycle an d is n ow read y to retu rn d ata. W h ile th e secon d ban k is retu rn in g d ata, th e first ban k is bein g p rech arged , selectin g th e row an d colu m n ad d ress of th e n ext access. Th is overlap p in g of accesses in two ban ks red u ces th e effect of th e laten cy or p rech arge cycles an d allows for faster overall d ata retrieval. Th e on ly p roblem is th at to u tilize in terleavin g, you m u st in stall id en tical p airs of ban ks togeth er, d ou blin g th e am ou n t of SIMMs or DIMMs req u ired . Th is was p op u lar on 32-bit wid e m em ory system s on 486 p rocessors, bu t fell ou t of favor on Pen tiu m s d u e to th e 64bit wid e m em ory wid th on th ose system s. To d o in terleavin g on a Pen tiu m m ach in e, you wou ld n eed to in stall m em ory 128 bits at a tim e, m ean in g fou r 72-p in SIMMs or two DIMMs at a tim e. EDO RAM Startin g in 1995, a n ew typ e of m em ory becam e available for Pen tiu m system s called EDO (Extended Data Out) RAM. EDO is a m od ified form of FPM m em ory an d is also referred to as Hyper Page Mode. EDO was in ven ted an d p aten ted by Micron Tech n ology, alth ou gh th ey h ave licen sed p rod u ction to n u m erou s oth er m em ory m an u factu rers. EDO m em ory con sists of sp ecially m an u factu red ch ip s th at allow for a tim in g overlap between su ccessive accesses. Th e n am e Exten d ed Data Ou t refers sp ecifically to th e fact th at u n like FPM, th e d ata ou tp u t d rivers on th e ch ip are n ot tu rn ed off wh en th e m em ory con troller rem oves th e colu m n ad d ress to begin th e n ext cycle. Th is allows th e n ext cycle to overlap th e p reviou s on e, savin g ap p roxim ately 10n s p er cycle. Th e effect of EDO is th at cycle tim es are im p roved by allowin g th e m em ory con troller to begin a n ew colu m n ad d ress in stru ction wh ile it is read in g d ata at th e cu rren t ad d ress. Th is is alm ost id en tical to wh at was ach ieved in old er system s by in terleavin g ban ks of m em ory, bu t u n like in terleavin g, you d on ’t n eed to in stall two id en tical ban ks of m em ory in th e system at a tim e. EDO RAM allows for bu rst m od e cyclin g of 5-2-2-2, as com p ared to th e 5-3-3-3 of stan d ard Fast Page Mod e m em ory. Th is m ean s th at to d o fou r m em ory tran sfers, EDO wou ld req u ire 11 total system cycles as com p ared to 14 total cycles for FPM. Th is is a 22% im p rovem en t in overall cyclin g tim e, bu t in actu al testin g EDO n orm ally in creases overall

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system ben ch m ark sp eed by abou t 5%. Even th ou gh th e overall system im p rovem en t m ay seem sm all, th e im p ortan t th in g abou t EDO is th at it u ses th e sam e basic DRAM ch ip d esign as FPM, m ean in g th at th ere is virtu ally n o ad d ition al cost over FPM. As su ch , EDO costs abou t th e sam e as FPM an d offers h igh er p erform an ce. To actu ally u se EDO m em ory, you r m oth erboard ch ip set m u st su p p ort it. Most m oth erboard ch ip sets sin ce th e In tel 430FX (Triton ), wh ich d ebu ted in 1995, h ave offered su p p ort for EDO. Becau se EDO m em ory ch ip s cost th e sam e to m an u factu re as stan d ard ch ip s, com bin ed with th e fact th at In tel began to su p p ort EDO in all th eir ch ip sets, th e PC m arket ju m p ed on th e EDO ban d wagon fu ll force. √√ See “ Fifth-Generation (P5 Pentium Class) Chipsets,” p. 187, and “ Sixth-Generation (P6 Pentium Pro / Pentium II Class) Chipsets,” p. 199

EDO RAM is id eal for system s with bu s sp eed s of u p to 66MHz, wh ich fit p erfectly with th e PC m arket u p th rou gh 1997; h owever, for 1998 an d beyon d , th e m arket for EDO will rap id ly d eclin e as th e n ewer an d faster SDRAM (Syn ch ron ou s DRAM) arch itectu re becom es th e stan d ard for n ew PC system m em ory. Burst EDO A variation of EDO is Burst Extended-Data-Out Dynam ic Random Access Mem ory (BEDO DRAM). BEDO is basically EDO m em ory with sp ecial bu rst featu res for even sp eed ier d ata tran sfers th an stan d ard EDO. Un fortu n ately, on ly on e ch ip set (In tel 440FX Natom a) su p p orted it, an d it was q u ickly oversh ad owed by SDRAM, wh ich seem ed to be favored am on g PC system ch ip set an d system d esign ers. As su ch , you won ’t see BEDO bein g u sed in system s tod ay, an d it is n o lon ger in p rod u ction . SDRAM SDRAM stan d s for Syn ch ron ou s DRAM, a typ e of DRAM th at ru n s in syn ch ron ization with th e m em ory bu s. SDRAM d elivers in form ation in very h igh -sp eed bu rsts u sin g a h igh -sp eed , clocked in terface. SDRAM rem oves m ost of th e laten cy in volved in asyn ch ron ou s DRAM becau se th e sign als are alread y in syn ch ron ization with th e m oth erboard clock. Like EDO RAM, you r ch ip set m u st su p p ort th is typ e of m em ory for it to be u sable in you r system . Startin g in 1997 with th e 430VX an d 430TX, all of In tel’s su bseq u en t ch ip sets fu lly su p p ort SDRAM, m akin g it th e m ost p op u lar typ e of m em ory for n ew system s. SDRAM is esp ecially su ited to th e Pen tiu m II arch itectu re, an d th e n ew h igh -p erform an ce m oth erboard s th at ru n it. Perform an ce of SDRAM is d ram atically im p roved over FPM or EDO RAM. Becau se SDRAM is still a typ e of DRAM, th e in itial laten cy is th e sam e, bu t overall cycle tim es are m u ch faster th an with FPM or EDO. SDRAM tim in g for a bu rst access wou ld be 5-1-1-1, m ean in g th at fou r m em ory read s wou ld com p lete in on ly eigh t system bu s cycles, as com p ared to 11 cycles for EDO an d 14 cycles for FPM.

Future DRAM M emory Technologies

Besid es th e fact th at SDRAM can work in fewer cycles, it is also cap able of su p p ortin g 100MHz (10n s) or faster system bu s cyclin g, wh ich h as becom e th e n ew stan d ard for system sp eed startin g in 1998. As su ch , virtu ally all n ew PC system s sold in 1998 an d for p robably two years th ereafter will in clu d e SDRAM m em ory. It is an ticip ated th at in th e n ear fu tu re, th is figu re will be p u sh ed to 200MHz in ord er to keep u p with faster system s of th e fu tu re. SDRAM is sold in DIMM form , an d is often rated by m egah ertz sp eed rath er th an n an osecon d cyclin g tim e. As su ch , you will see SDRAM sold as 66MHz or 15n s, 83MHz or 12n s, or 100MHz or 10n s. Du e to th e extrem e tim in g at th e 100MHz level, In tel h as created a PC/ 100 stan d ard th at d efin es th e p erform an ce criteria a 100MHz m em ory m od u le m u st m eet to be reliable in a 100MHz system . To m eet th e criteria with en ou gh overh ead to sp are, m ost PC/ 100-certified m em ory will be 8n s, or 125MHz. Even th ou gh th ey are tech n ically cap able of 125MHz, th ey will be PC/ 100 or 100MHz “certified .” Alth ou gh 10n s m em ory m igh t work, In tel feels th at it will n ot be reliable en ou gh becau se th e m argin s are too close. Alth ou gh SDRAM is sign ifican tly faster th an p reviou s typ es of m em ory, p rices are n ot ap p reciably h igh er, wh ich h as m ad e th e accep tan ce of SDRAM even m ore rap id . ◊◊ See “ SIM M s and DIM M s,” p. 324

Fut ure DRAM M em ory Technologies RDRAM Th e RDRAM, or Ram bu s DRAM, is a rad ical n ew m em ory d esign th at will be u sed in h igh -en d PC system s startin g in th e 1999-2000 tim efram e. It is en d orsed by In tel an d will be d irectly su p p orted in th e fu tu re ch ip sets released d u rin g th at tim efram e. RDRAMs boost raw m em ory ban d wid th by d ou blin g th e on -ch ip d ata bu s to 16 bits an d in creasin g th e clock to 800MHz, for a p eak ban d wid th of 1.6 Gbytes/ secon d . Ram bu s m ad e im p rovem en ts to th e bu s p rotocol so th at it n o lon ger m u ltip lexes or sh ares con trol in form ation on th e d ata bu s. In stead , it creates an in d ep en d en t con trol an d ad d ress bu s sp lit in to two grou p s of p in s for row an d colu m n com m an d s, wh ile d ata is tran sferred across th e 2-byte-wid e d ata bu s. Syn ch ron ization is ach ieved by sen d in g p ackets on th e fallin g ed ge of th e clock. Th e arch itectu re su p p orts m u ltip le, sim u ltan eou s in terleaved tran saction s. In tern ally, th e 64-Mbit d evice u ses a total 128-bit-wid e d ata p ath op eratin g at 100MHz, allowin g 16byte tran sfers to or from th e core every 10n s. Becau se RDRAMs h ave fou r p ower-d own m od es an d au tom atically tran sition in to stan d by at th e en d of a tran saction , total m od u le p ower is sligh tly lower th an an SDRAM’s at th e d esktop an d sim ilar to EDO for m obile system s. RDRAM ch ip s will be in stalled in m od u les called RIMMs (Ram bu s In lin e Mem ory Mod u les). A RIMM (sh own in Figu re 5.3) is sim ilar in size an d form to cu rren t DIMMs, bu t th ey are n ot in terch an geable.

317

Chapter 5—M emory

Front Side

3±0.05

TBD 43 ±0.05

TBD

3±0.05

1.5±0.05 0.5±0.05

43 ±0.05

20.675±0.05

63.675±0.05

pin1

17.78±0.05

318

pin84

63.675±0.05 66.675±0.05

20.675±0.05

TBD

66.675±0.05 Back side

Component area (TBD)

pin85

pin168

FIG. 5.3 168-p in RIMM m od u le. An RDRAM m em ory con troller with a sin gle Ram bu s ch an n el su p p orts u p to th ree RIMM m od u les, wh ich at th e 64Mbit ch ip d en sity level su p p orts 256M p er RIMM. Fu tu re RIMM version s will be available in h igh er cap acities, u p to 1G or m ore, an d it will be p ossible to d evelop ch ip sets (with in tegral Ram bu s m em ory con trollers), wh ich can su p p ort m ore Ram bu s ch an n els, allowin g for m ore RIMM sockets p er board . In terestin gly Ram bu s d oes n ot m an u factu re eith er th e RDRAM ch ip s or th e RIMMs; th at is left to oth er com p an ies. Ram bu s is m erely a d esign com p an y, an d th ey h ave n o ch ip fabs or m an u factu rin g facilities of th eir own . Th ey licen se th eir tech n ology to oth er com p an ies wh o th en m an u factu re th e d evices an d m od u les. Th ere are at least 13 RDRAM licen sees, su ch as Fu jitsu Ltd ., Hitach i Ltd ., Hyu n d ai Electron ics In d u stry Co. Ltd ., IBM Microelectron ics, LG Sem icon d u ctor Co. Ltd ., Micron Tech n ology In c., Mitsu bish i Electric Corp ., NEC Corp ., Oki Electric In d u stry Co. Ltd ., Sam su n g Electron ics Corp ., Siem en s AG, an d Tosh iba Corp . All th ese com p an ies will be m an u factu rin g both th e RDRAM d evices an d th e RIMMs th at con tain th em . DDR SDRAM Dou ble Data Rate (DDR) SDRAM m em ory is an evolu tion ary d esign of stan d ard SDRAM wh ere d ata is tran sferred twice as fast. In stead of d ou blin g th e actu al clock rate, DDR m em ory ach ieves th e d ou blin g in p erform an ce by tran sferrin g two tim es p er tran sfer cycle, on ce at th e lead in g an d on ce at th e trailin g ed ge of th e cycle. Th is effectively d ou bles th e tran sfer rate, even th ou gh th e sam e overall clock an d tim in g sign als are u sed . DDR is bein g p rop osed by p rocessor com p an ies su ch as AMD an d Cyrix, an d ch ip set m an u factu rers su ch as VIA Tech n ologies, ALi (Acer Labs, In c.), an d SiS (Silicon in tegrated System s) as a low-cost licen se-free altern ative to RDRAMs. In tel is officially su p p ortin g on ly RDRAMs for n ew h igh -en d system s in 1999 an d beyon d , wh ile DDR seem s d estin ed for th e lower-en d com m od ity PCs as an altern ative. Official stan d ard ization of DDR was u n d ertaken by th e DDR Con sortiu m , an in d u stry p an el con sistin g of Fu jitsu , Ltd ., Hitach i, Ltd ., Hyu n d ai Electron ics In d u stries Co., Mitsu bish i Electric Corp ., NEC Corp ., Sam su n g Electron ics Co., Texas In stru m en ts, In c., an d Tosh iba Corp .

Cache M emory—SRAM

Exp ect DDR SDRAM to m ake an ap p earan ce d u rin g 1999, p rim arily in n on -In tel p rocessor-based system s.

Cache M em ory—SRAM Th ere is an oth er d istin ctly d ifferen t typ e of m em ory th at is sign ifican tly faster th an m ost typ es of DRAM. SRAM stan d s for Static RAM, wh ich is so n am ed becau se it d oes n ot n eed th e p eriod ic refresh rates like DRAM (Dyn am ic RAM). Du e to th e d esign of SRAM, n ot on ly are refresh rates u n n ecessary, bu t SRAM is m u ch faster th an DRAM an d is fu lly able to keep p ace with m od ern p rocessors. SRAM m em ory is available in access tim es of 2n s or less, wh ich m ean s it can keep p ace with p rocessors ru n n in g 500MHz or faster! Th is is d u e to th e SRAM d esign , wh ich calls for a clu ster of six tran sistors for each bit of storage. Th e u se of tran sistors bu t n o cap acitors m ean s th at refresh rates are n ot n ecessary becau se th ere are n o cap acitors to lose th eir ch arges over tim e. As lon g as th ere is p ower, SRAM will rem em ber wh at is stored . W ith th ese attribu tes, th en wh y d on ’t we u se SRAM for all system m em ory? Th e an swers are sim p le: Type

Speed

Densit y

Cost

DRAM

Slow

High

Low

SRAM

Fast

Low

High

Com p ared to DRAM, SRAM is m u ch faster, bu t also m u ch lower in d en sity an d m u ch m ore exp en sive. Th e lower d en sity m ean s th at SRAM ch ip s are p h ysically larger an d store m an y less bits overall. Th e h igh n u m ber of tran sistors an d th e clu stered d esign m ean s th at SRAM ch ip s are both p h ysically larger an d m u ch m ore exp en sive to p rod u ce th an DRAM ch ip s. For exam p le, a DRAM m od u le m igh t con tain 64M of RAM or m ore, wh ile SRAM m od u les of th e sam e ap p roxim ate p h ysical size wou ld h ave room for on ly 2M or so of d ata an d wou ld cost th e sam e as th e 64M DRAM m od u le. Basically, SRAM is u p to 30 tim es larger p h ysically an d u p to 30 tim es m ore exp en sive th an DRAM. Th e h igh cost an d p h ysical con strain ts h ave p reven ted SRAM from bein g u sed as th e m ain m em ory for PC system s. Even th ou gh SRAM is too exp en sive for PC u se as m ain m em ory, PC d esign ers h ave fou n d a way to u se SRAM to d ram atically im p rove PC p erform an ce. Rath er th an sp en d th e m on ey for all RAM to be SRAM m em ory, wh ich can ru n fast en ou gh to m atch th e CPU, it is m u ch m ore cost-effective to d esign in a sm all am ou n t of h igh -sp eed SRAM m em ory, called cache m em ory. Th e cach e ru n s at sp eed s close to or even eq u al to th e p rocessor, an d is th e m em ory from wh ich th e p rocessor n orm ally d irectly read s from an d writes to. Du rin g read op eration s, th e d ata in th e h igh -sp eed cach e m em ory is resu p p lied from th e lower-sp eed m ain m em ory or DRAM in ad van ce. Up u n til recen tly, DRAM was lim ited to abou t 60n s (16MHz) in sp eed . W h en PC system s were ru n n in g 16MHz an d less, it was p ossible for th e DRAM to fu lly keep p ace with th e m oth erboard an d system p rocessor, an d th ere was n o n eed for cach e. However, as soon as p rocessors crossed th e 16MHz barrier, it was n o lon ger p ossible for DRAM to keep

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p ace, an d th at is exactly wh en SRAM began to en ter PC system d esign s. Th is occu rred back in 1986–1987 with th e d ebu t of system s with th e 386 p rocessor ru n n in g at 16- an d 20MHz. Th ese were am on g th e first PC system s to em p loy wh at we call cache m em ory, a h igh -sp eed bu ffer m ad e u p of SRAM th at d irectly feed s th e p rocessor. Becau se th e cach e can ru n at th e sp eed of th e p rocessor, th e system is d esign ed so th e cach e con troller will an ticip ate th e p rocessor’s m em ory n eed s, an d p reload th e h igh -sp eed cach e m em ory with th at d ata. Th en , as th e p rocessor calls for a m em ory ad d ress, th e d ata can be retrieved from th e h igh -sp eed cach e rath er th an th e m u ch lower sp eed m ain m em ory. Cach e effectiven ess is exp ressed as a hit ratio. Th is is th e ratio of cach e h its to total m em ory accesses. A hit is wh en th e d ata th e p rocessor n eed s h as been p reload ed in to th e cach e from th e m ain m em ory, m ean in g th at th e p rocessor can read it from th e cach e. A cache m iss is wh en th e cach e con troller d id n ot an ticip ate th e n eed for a sp ecific ad d ress; th e d esired d ata was n ot p reload ed in to th e cach e; th erefore, th e p rocessor m u st retrieve th e d ata from th e slower m ain m em ory, in stead of th e faster cach e. An ytim e th e p rocessor read s d ata from m ain m em ory, th e p rocessor will h ave to wait becau se th e m ain m em ory cycles at a m u ch slower rate th an th e p rocessor. If th e p rocessor is ru n n in g at 233MHz, th en it is cyclin g at n early 4n s, wh ile th e m ain m em ory m igh t be 60n s, wh ich m ean s it is ru n n in g at on ly 16MHz. Th u s, every tim e th e p rocessor read s from m ain m em ory, it wou ld effectively slow d own to 16MHz! Th e slowd own is accom p lish ed by h avin g th e p rocessor execu te wh at are called wait states, wh ich are cycles wh ere n oth in g is d on e; th e p rocessor essen tially cools its h eels wh ile waitin g for th e slower m ain m em ory to retu rn th e d esired d ata. Obviou sly, we d on ’t wan t ou r p rocessors slowin g d own , so cach e fu n ction an d d esign becom e very im p ortan t as system sp eed s in crease. To m in im ize th e situ ation wh ere th e p rocessor is forced to read d ata from th e slow m ain m em ory, th ere are n orm ally two stages of cach e in a m od ern system , called Level 1 (L1) an d Level 2 (L2). Th e Level 1 cach e is also called in tegral or in tern al cach e becau se it is d irectly bu ilt in to th e p rocessor, an d is actu ally a p art of th e p rocessor d ie (raw ch ip ). Becau se of th is, L1 cach e always ru n s at th e fu ll sp eed of th e p rocessor core, an d is th e fastest cach e in an y system . All 486 an d h igh er p rocessors in corp orate in tegral L1 cach e, m akin g th em sign ifican tly faster th an th eir p red ecessors. Level 2 cach e is also called extern al cach e becau se it is extern al to th e p rocessor ch ip . Origin ally, th is m ean t th at it was in stalled on th e m oth erboard , as was th e case with all 386, 486, an d Pen tiu m system s. In th ose system s, th e L2 cach e ru n s at m oth erboard sp eed becau se it is in stalled on th e m oth erboard . You can n orm ally fin d th e L2 cach e d irectly ad jacen t to th e p rocessor socket in Pen tiu m an d earlier system s. In th e in terest of im p roved p erform an ce, later p rocessor d esign s from In tel, in clu d in g th e Pen tiu m Pro an d Pen tiu m II, h ave in clu d ed th e L2 cach e as a p art of th e p rocessor. It is still extern al to th e actu al CPU d ie, an d is in stead a sep arate d ie or ch ip m ou n ted in sid e th e p rocessor p ackage or m od u le. As su ch , Pen tiu m Pro or Pen tiu m II system s will n ot h ave an y cach e on th e m oth erboard ; it is all con tain ed with in th e p rocessor m od u le, in stead .

Cache M emory—SRAM

Th e key to u n d erstan d in g both cach e an d m ain m em ory is to see wh ere th ey fit in th e overall system arch itectu re. Figu re 5.4 sh ows a typ ical Pen tiu m MMX system with th e In tel 430TX ch ip set.

Pentium CPU

Up to 266MHz

L1 Cache Processor Bus 66MHz

L2 Cache (15ns)

66MHz

16/66MHz North Bridge (430TX)

PCI Bus 33MHz

USB1

EDO SIMM (16MHz) or SDRAM DIMM (66MHz)

PCI Slots

USB2 South Bridge (PIIX4)

CMOS & RTC

IDE 1

PCI Video

IDE 2

ISA Bus 8 MHz

ISA Slots

Floppy

Keyboard Mouse

Super I/O (87307)

COM 1

COM 2

LPT 1 ROM Flash BIOS

FIG. 5.4 System Arch itectu re, Pen tiu m MMX system with an In tel 430TX ch ip set. Table 5.3 illu strates th e n eed for an d fu n ction of Level 1 (in tern al) an d Level 2 (extern al) cach e in m od ern system s.

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Table 5.3

The Relat ionship Bet w een Level 1 ( Int ernal) and Level 2

( Ext ernal) Cache in M odern Syst em s 486 DX4

Pent ium

Pent ium Pro

Pent ium II ( 1997)

Pent ium II ( 1998)

Typical CPU Speed:

100M Hz

233M Hz

200M Hz

300M Hz

400M Hz

L1 Cache Speed:

10ns (100M Hz)

4ns (233M Hz)

5ns (200M Hz)

3ns (300M Hz)

2ns (400M Hz)

L2 Cache Speed:

30ns (33M Hz)

15ns (66M Hz)

5ns (200M Hz)

6ns (150M Hz)

5ns (200M Hz)

CPU Type

M otherboard Speed:

33M Hz

66M Hz

66M Hz

66M Hz

100M Hz

SIM M / DIM M Speed:

60ns (16M Hz)

60ns (16M Hz)

60ns (16M Hz)

15ns (66M Hz)

10ns (100M Hz)

Cach e d esign s were origin ally asyn ch ron ou s, m ean in g th ey ran at a clock sp eed th at was n ot id en tical or in syn c with th e p rocessor bu s. Startin g with th e 430FX ch ip set released in early ’95, a n ew typ e of syn ch ron ou s cach e d esign was su p p orted . Th is req u ired th at th e ch ip s n ow ru n in syn c or at th e sam e id en tical clock tim in g as th e p rocessor bu s, fu rth er im p rovin g sp eed an d p erform an ce. Also ad d ed at th at tim e was a featu re called Pip elin e Bu rst m od e, wh ich red u ced overall cach e laten cy (wait states) by allowin g for sin gle-cycle accesses for m u ltip le tran sfers after th e first on e. Becau se both syn ch ron ou s an d p ip elin e bu rst cap ability cam e at th e sam e tim e in n ew m od u les, u su ally sp ecifyin g on e im p lies th e oth er. Overall syn ch ron ou s p ip elin e bu rst cach e allowed for abou t a 20% im p rovem en t in overall system p erform an ce, wh ich was a very sign ifican t ju m p . Th e cach e con troller for a m od ern system is con tain ed with in eith er th e North Brid ge of th e ch ip set as with Pen tiu m an d lesser system s, or with in th e p rocessor as with th e Pen tiu m Pro/ II an d n ewer system s. Th e cap abilities of th e cach e con troller d ictate th e p erform an ce an d cap abilities of th e cach e. On e im p ortan t th in g to n ote is th at m ost cach e con trollers h ave a lim itation of th e am ou n t of m em ory th at m ay be cach ed . Often , th is lim it can be q u ite low, as with th e 430TX ch ip set-based Pen tiu m system s. Th e 430TX ch ip set can cach e d ata on ly with in th e first 64M of system RAM. If you h ave m ore m em ory th an th at, you will exp erien ce a n oticeable slowd own in system p erform an ce becau se all d ata ou tsid e th e first 64M will n ever be cach ed , an d wou ld always be accessed with all th e wait states req u ired by th e slower DRAM. Dep en d in g on wh at software you u se an d wh ere d ata is stored in m em ory, th is can be very sign ifican t. For exam p le, 32-bit op eratin g system s su ch as W in 95/ 98 an d NT load from th e top d own , so if you h ad 96M of RAM, th e op eratin g system an d ap p lication s wou ld be load in g d irectly in to th e u p p er 32M (p ast 64M), wh ich is n ot cach ed . Th is wou ld resu lt in a d ram atic slowd own in overall system u se. Rem ovin g th e ad d ition al m em ory to brin g th e system total d own to th e cach eable lim it of 64M wou ld be th e solu tion . In sh ort, it is u n wise to in stall m ore m ain RAM m em ory th an you r system (ch ip set) can cach e. Con su lt you r system d ocu m en tation or th e ch ip set section in Ch ap ter 4, “Moth erboard s an d Bu ses,” for m ore in form ation .

Physical M emory

Physical M em ory Th e CPU an d m oth erboard arch itectu re (ch ip set) d ictates a p articu lar com p u ter’s p h ysical m em ory cap acity, an d th e typ es an d form s of m em ory th at can be in stalled . Over th e years, th ere h ave been two m ain ch an ges occu rrin g with com p u ter m em ory—it h as grad u ally becom e faster an d wid er! Th e sp eed an d wid th req u irem en ts are in d icated by th e CPU an d th e m em ory con troller circu itry. Th e m em ory con troller in a m od ern PC resid es in th e m oth erboard ch ip set. Even th ou gh a system m ay p h ysically su p p ort a given am ou n t of m em ory, th e typ e of software you ru n m ay d ictate wh eth er or n ot all th e m em ory can be u sed . Th e 8088 an d 8086, with 20 ad d ress lin es, can u se as m u ch as 1M (1024K) of RAM. Th e 286 an d 386SX CPUs h ave 24 ad d ress lin es; th ey can keep track of as m u ch as 16M of m em ory. Th e 386DX, 486, Pen tiu m , Pen tiu m -MMX, an d Pen tiu m Pro CPUs h ave a fu ll set of 32 ad d ress lin es; th ey can keep track of 4G of m em ory, wh ile th e Pen tiu m II with 36 ad d ress lin es can m an age an im p ressive 64G! √√ See “ Processor Specifications,” p. 31

W h en th e 286 an d h igh er ch ip s em u late th e 8088 ch ip (as th ey d o wh en ru n n in g 16-bit software su ch as DOS or W in d ows 3.x), th ey im p lem en t a h ard ware op eratin g m od e called real m ode. Real m od e is th e on ly m od e available on th e 8086 an d 8088 ch ip s u sed in PC an d XT system s. In real m od e, all In tel p rocessors—even th e m igh ty Pen tiu m —are restricted to u sin g on ly 1M of m em ory, ju st as th eir 8086 an d 8088 an cestors were, an d th e system d esign reserves 384K of th at am ou n t. On ly in p rotected m od e can th e 286 or better ch ip s u se th eir m axim u m p oten tial for m em ory ad d ressin g. √√ See “ Processor M odes,” p. 43

Pen tiu m -based system s can ad d ress as m u ch as 4G of m em ory, an d Pen tiu m Pro/ II system s can ad d ress 64G. To p u t th ese m em ory-ad d ressin g cap abilities in to p ersp ective, 64G (65,536M) of m em ory wou ld cost abou t $100,000! Even if you cou ld afford all th is m em ory, som e of th e largest m em ory m od u les available tod ay are 168-p in DIMMs with 256M cap acity. To in stall 64G of RAM wou ld req u ire 256 of th e largest 256M DIMMs available, an d m ost system s tod ay can su p p ort u p to on ly fou r or m aybe eigh t DIMM sockets. Most Pen tiu m II m oth erboard s h ave a m axim u m of on ly th ree to six DIMM sockets, wh ich allows a m axim u m of .75–1.5G if all th e sockets are filled . Th ese lim itation s are from th e ch ip set, n ot th e p rocessor. Tech n ically, a Pen tiu m can ad d ress 4G of m em ory an d a Pen tiu m II can ad d ress 64G, bu t th ere isn ’t a ch ip set on th e m arket th at will allow th at! Most of th e PII ch ip sets tod ay are lim ited to 1G of m em ory. Pen tiu m system s h ave even fu rth er lim itation s. Pen tiu m system s h ave been available sin ce ’93, bu t on ly th ose bu ilt in ’97 or later u se a m oth erboard ch ip set th at will su p p ort SDRAM DIMMs. Even th ose u sin g th e n ewest 430TX ch ip set from In tel will n ot su p p ort

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m ore th an 256M of total m em ory, an d sh ou ld n ot h ave m ore th an 64M actu ally in stalled d u e to m em ory-cach in g lim itation s. Don ’t in stall m ore th an 64M of RAM in you r Pen tiu m system u n less you are su re th e m oth erboard an d ch ip set will allow th e L2 cach e to fu n ction with th e ad d ition al m em ory. See th e ch ip set section in Ch ap ter 4 for th e m axim u m cach eable lim its on all th e In tel an d oth er m oth erboard ch ip sets. Old er 386 an d 486 m oth erboard s m ay h ave p roblem s ad d ressin g m em ory p ast 16M d u e to DMA (Direct Mem ory Access) con troller p roblem s. If you in stall an ISA ad ap ter th at u ses a DMA ch an n el (su ch as a bu sm aster SCSI ad ap ter) an d you h ave m ore th an 16M of m em ory, you h ave th e p oten tial for p roblem s becau se th e ISA bu s allows on ly DMA access to 16M. Attem p ted tran sfers beyon d 16M cau se th e system to crash . Th is sh ou ld n ot be an issu e with n ewer 32-bit op eratin g system s, an d 32-bit slots su ch as PCI. Th e 32bit op eratin g system s will au tom atically rem ap ISA bu s DMA tran sfers beyon d 16M p rop erly, an d PCI sim p ly d oesn ’t h ave an y su ch lim itation s. SIM M s and DIM M s Origin ally, system s h ad m em ory in stalled via in d ivid u al ch ip s. Th ese are often referred to as DIP (Du al In lin e Package) ch ip s becau se of th eir d esign . Th e origin al IBM XT an d AT h ad 36 sockets on th e m oth erboard for th ese in d ivid u al ch ip s, an d th en m ore of th em wou ld be in stalled on variou s m em ory card s p lu gged in to th e bu s slots. I rem em ber sp en d in g h ou rs p op u latin g board s with th ese ch ip s, wh ich was a ted iou s job. Besid es bein g a tim e-con su m in g an d labor-in ten sive way to d eal with m em ory, DIP ch ip s h ad on e n otoriou s p roblem —th ey wou ld creep ou t of th eir sockets over tim e as th e system wou ld go th rou gh th erm al cycles. Every d ay wh en you p owered th e system on an d off, it wou ld h eat an d cool, an d th e ch ip s wou ld grad u ally walk th eir way ou t of th e sockets. Even tu ally, good con tact wou ld be lost an d m em ory errors wou ld resu lt. Fortu n ately, reseatin g all th e ch ip s back in th eir sockets wou ld u su ally rectify th e p roblem , bu t th at was labor-in ten sive if you h ad a lot of system s to su p p ort. Th e altern ative to th is at th e tim e was to h ave th e m em ory sold ered in to eith er th e m oth erboard or an exp an sion card . Th is p reven ted th e ch ip s from creep in g an d m ad e th e con n ection s m ore p erm an en t, bu t th at cau sed an oth er p roblem . If a ch ip d id go bad , you wou ld eith er h ave to attem p t d esold erin g an d resold erin g a n ew on e, or resort to scrap p in g th e m oth erboard or m em ory card in wh ich th e ch ip was in stalled . Th is was exp en sive, an d it m ad e m em ory trou blesh ootin g very d ifficu lt. W h at was n eed ed was a ch ip th at was both sold ered yet rem ovable, an d th at is exactly wh at was fou n d in th e ch ip th at we call a SIMM. For m em ory storage, m ost m od ern system s h ave ad op ted th e sin gle in lin e m em ory m od u le (SIMM) or d u al in lin e m em ory m od u le (DIMM) as an altern ative to in d ivid u al m em ory ch ip s. Th ese sm all board s p lu g in to sp ecial con n ectors on a m oth erboard or m em ory card . Th e in d ivid u al m em ory ch ip s are sold ered to th e SIMM/ DIMM, so rem ovin g an d rep lacin g in d ivid u al m em ory ch ip s is im p ossible. In stead , you m u st rep lace th e en tire m od u le if an y p art of it fails. Th e SIMM/ DIMM is treated as th ou gh it were on e large m em ory ch ip .

Physical M emory

PC system s u se two m ain p h ysical typ es of SIMMs—30-p in (8 bits p lu s on e op tion al p arity bit) an d 72-p in (32 bits p lu s fou r op tion al p arity bits)—with variou s cap acities an d oth er sp ecification s. Th e 30-p in SIMMs are sm aller th an th e 72-p in version s, an d m ay h ave ch ip s on eith er on e or both sid es. 30-p in SIMMs are basically obsolete, an d th ey are bein g followed rap id ly by th e 72-p in version s. Th is is tru e p rim arily becau se th e 64-bit system s, wh ich are n ow th e in d u stry stan d ard , wou ld req u ire eigh t 30-p in SIMMs or two 72-p in SIMMs p er ban k. DIMMs, wh ich h ave becom e p op u lar on Pen tiu m -MMX an d Pen tiu m Pro-based system s, are 168-p in u n its with 64-bit (n on -p arity) or 72-bit (p arity or ECC) d ata p ath s. Figu res 5.5, 5.6, an d 5.7 sh ow typ ical 30-p in (8-bit) an d 72-p in (32-bit) SIMMs, an d a 168-p in (64-bit) DIMM, resp ectively. Th e p in s are n u m bered from left to righ t an d are con n ected th rou gh to both sid es of th e m od u le on th e SIMMs. Th e p in s on th e DIMM are d ifferen t on each sid e. Note th at all d im en sion s are in both in ch es an d m illim eters (in p aren th eses). .653 (16.59) .647 (16.43)

3.505 (89.03) 3.495 (88.77)

.200 (5.08) MAX.

.133 (3.38) TYP.

.250 (6.35) TYP.

.400 (10.16) TYP.

PIN 1 .080 (2.03) TYP.

.100 (2.54) TYP.

.070 (1.78) TYP.

.055 (1.40) .047 (1.19)

FIG. 5.5 A typ ical 30-p in SIMM. Th e on e sh own h ere is 9-bit, alth ou gh th e d im en sion s wou ld be th e sam e for 8-bit as well. 4.260 (108.20) 4.240 (107.70)

.133 (3.38) TYP

.125 (3.18) TYP

.350 (8.98) MAX

1.010 (25.65) .990 (25.15)

+ .400 (10.16) TYP

.250 (6.35)

.080 (2.03)

.235 (5.97) MIN

1.75 (44.45) TYP PIN 1

.250 (6.35)

.050 (1.27) TYP

.054 (1.37) .047 (1.19)

.040 (1.02) TYP

3.75 (95.25)

FIG. 5.6 A typ ical 72-p in SIMM. Th e on e sh own h ere is 36-bit, alth ou gh th e d im en sion s wou ld be th e sam e for 32-bit as well.

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FRONT VIEW 5.260 (133.80) 5.240 (133.00)

.350 (8.89) MAX

.079 (2.00) R (2X) – 1.260 (32.00) 1240 (31.50) .118 (3.00) R (2X)

.700 (17.7B) TYP

.118 (3.00) TYP .250 (6.35) TYP .118 (3.00) TYP

1.661 (42.18) 2.625 (66.68)

.039 (1.00)R (2X) .39 (1.27) TYP

.050 (1.27) TYP

PIN 1 (PIN 85 ON BACKSIDE)

.128 (3.25) (2x) .118 (3.00)

.054 (1.37) .046 (1.17)

PIN 84 (PIN 168 ON BACKSIDE)

4.550 (115.57)

FIG. 5.7 A typ ical 168-p in DIMM. Th e on e sh own h ere is 72-bit, alth ou gh th e d im en sion s wou ld be th e sam e for 64-bit as well.

Sin gle in lin e p in n ed p ackages, som etim es called SIPPs, really are SIMMs with p in s, n ot con tacts. Th e p in s are d esign ed to be in stalled in a lon g con n ector socket th at is m u ch ch eap er th an th e stan d ard SIMM socket. SIPPs are in ferior to SIMMs becau se th ey lack th e p ositive latch in g m ech an ism th at retain s th e m od u le, an d th e con n ector lacks th e h igh -force wip in g con tacts th at resist corrosion . SIPPs are rarely u sed tod ay.

Not e It would be possible to convert a SIPP to a SIM M by cutting off the pins, or to convert a SIM M to a SIPP by soldering pins on. Also, some companies have made SIPP-to-SIM M converters that allow the SIPPs to be plugged into 30-pin SIM M sockets.

Th ese m em ory m od u les are extrem ely com p act con sid erin g th e am ou n t of m em ory th ey h old . SIMMs an d DIMMs are available in several cap acities an d sp eed s. Table 5.4 lists th e d ifferen t cap acities available for both th e 30-p in an d 72-p in SIMMs, an d 168-p in DIMMs. Table 5.4

SIM M and DIM M Capacit ies

30-Pin SIM M Capacit ies Capacit y

Parit y SIM M

Non-Parit y SIM M

256K

256K×9

256K×8

1M

1M ×9

1M ×8

4M

4M ×9

4M ×8

16M

16M ×9

16M ×8

72-Pin SIM M Capacit ies Capacit y

Parit y SIM M

Non-Parit y SIM M

1M

256K×36

256K×32

2M

512K×36

512K×32

4M

1M ×36

1M ×32

8M

2M ×36

2M ×32

Physical M emory

Capacit y

Parit y SIM M

Non-Parit y SIM M

16M

4M ×36

4M ×32

32M

8M ×36

8M ×32

64M

16M ×36

16M ×32

128M

32M ×36

32M ×32

168-Pin DIM M Capacit ies Capacit y

Parit y DIM M

Non-Parit y DIM M

8M

1M ×72

1M ×64

16M

2M ×72

2M ×64

32M

4M ×72

4M ×64

64M

8M ×72

8M ×64

128M

16M ×72

16M ×64

256M

32M ×72

32M ×64

Dyn am ic RAM (DRAM) SIMMs an d DIMMs of each typ e an d cap acity are available in d ifferen t sp eed ratin gs. SIMMs h ave been available in m an y d ifferen t sp eed ratin gs, ran gin g from 120n s for som e of th e slowest, to 50n s for som e of th e fastest available. DIMMs are available in sp eed s from 60n s to 10n s or faster. Man y of th e first system s to u se SIMMs u sed version s rated at 120n s. Th ese were q u ickly rep laced in th e m arket by 100n s an d even faster version s. Tod ay, you gen erally p u rch ase EDO SIMMs rated at 60n s, an d SDRAM DIMMs rated at 10n s. Both faster an d slower on es are available, bu t th ey are n ot freq u en tly req u ired an d are d ifficu lt to obtain . If a system req u ires a sp ecific sp eed , you can alm ost always su bstitu te faster sp eed s if th e on e sp ecified is n ot available. Th ere are n o p roblem s in m ixin g SIMM sp eed s, as lon g as you u se SIMMs eq u al to or faster th an wh at th e system req u ires. Becau se very little p rice d ifferen ce exists between th e d ifferen t sp eed version s, I u su ally bu y faster SIMMs th an are n eed ed for a p articu lar ap p lication . Th is m ay m ake th em m ore u sable in a fu tu re system th at m ay req u ire th e faster sp eed .

Not e M ost DIM M s are Synchronous DRAM (SDRAM ) memory, which means they deliver data in very high-speed bursts using a clocked interface. SDRAM supports bus speeds of up to 100M Hz, with data transfer rates of up to 200M Hz possible in the future.

Several variation s on th e 30-p in SIMMs can affect h ow th ey work (if at all) in a p articu lar system . First, th ere are actu ally two variation s on th e p in ou t con figu ration s. Most system s u se a generic typ e of SIMM, wh ich h as an in d u stry-stan d ard p in con figu ration . Man y old er IBM system s u sed a sligh tly m od ified 30-p in SIMM, startin g with th e XT-286 in trod u ced in 1986 th rou gh th e PS/ 2 Mod el 25, 30, 50, an d 60. Th ese system s req u ire a SIMM with d ifferen t sign als on five of th e p in s. Th ese are kn own as IBM-style 30-p in SIMMs. You can m od ify a gen eric 30-p in SIMM to work in th e IBM system s an d vice

327

328

Chapter 5—M emory

versa, bu t p u rch asin g a SIMM with th e correct p in ou ts is m u ch easier. Be su re you tell th e SIMM ven d or if you n eed th e sp ecific IBM-style version s. An oth er issu e with resp ect to th e 30-p in SIMMs relates to th e ch ip cou n t. Th e SIMM acts as if it were a sin gle ch ip of 8 bits wid e (with op tion al p arity), an d it really d oes n ot m atter h ow th is total is d erived . Old er SIMMs were con stru cted with eigh t or n in e in d ivid u al 1-bit-wid e ch ip s to m ake u p th e m od u le, wh ereas m an y n ewer SIMMs u se two 4-bit-wid e ch ip s an d op tion ally on e 1-bit-wid e ch ip for p arity, m akin g a total of two or th ree ch ip s on th e SIMM. Accessin g th e two- or th ree-ch ip SIMMs can req u ire ad ju stm en ts to th e refresh tim in g circu its on th e m oth erboard , an d m an y old er 386 an d 486 m oth erboard s cou ld n ot cop e. Most n ewer m oth erboard s au tom atically h an d le th e sligh tly d ifferen t refresh tim in g of both th e 2/ 3-ch ip or 8/ 9-ch ip SIMMs, an d in th is case th e 2/ 3-ch ip version s are m ore reliable, u se less p ower, an d gen erally cost less as well. If you h ave an old er system , m ost likely it will also work with th e 2/ 3-ch ip SIMMs, bu t som e d o n ot. Un fortu n ately, th e on ly way to kn ow is to try th em . To p reven t th e ad d ition al tim e req u ired to ch an ge th em for 8/ 9-ch ip version s sh ou ld th e 2/ 3-ch ip version s n ot work in an old er system , it seem s wise to stick with th e 8/ 9-ch ip variety in an y old er system . Th e 72-p in SIMMs d o n ot h ave d ifferen t p in ou ts an d are d ifferen tiated on ly by cap acity an d sp eed . Th ese SIMMs are n ot affected by th e n u m ber of ch ip s on th em . Th e 72-p in SIMMs are id eal for 32-bit system s su ch as 486 m ach in es becau se th ey com p rise an en tire ban k of m em ory (32 d ata bits p lu s 4 p arity bits). W h en you con figu re a 32-bit (486) system th at u ses 72-p in SIMMs, you can u su ally ad d or rem ove m em ory as sin gle SIMM m od u les (excep t on system s th at u se in terleaved m em ory sch em es to red u ce wait states). Th is is becau se a 32-bit ch ip su ch as a 486 read s an d writes ban ks of m em ory 32 bits wid e, an d a 72-p in SIMM is exactly 32 bits wid e (36 bits with op tion al p arity). In 64-bit system s—wh ich in clu d es an y Pen tiu m or n ewer p rocessor—72-p in SIMMs m u st be u sed in p airs to fill a sin gle ban k. A few m oth erboard m an u factu rers offer so-called “SIMM-saver” m oth erboard s th at are d esign ed for n ewer Pen tiu m p rocessors, bu t h ave both 72- an d 30-p in SIMM sockets. Alth ou gh th is is n ot th e m ost d esirable arran gem en t, it allowed u sers on a bu d get to reu se th eir old 30-p in SIMMs. In th is situ ation , eigh t 30p in SIMMs can be u sed at a tim e to fill on e ban k. Altern atively, you cou ld p air fou r 30p in SIMMs with on e 72-p in SIMM to create on e ban k. Th is really is n ot a very efficien t setu p becau se it con su m es large am ou n ts of sp ace on th e m oth erboard . Oth er op tion s available are SIMM stackers an d con verters. Th ese item s allow you to u se 30-p in SIMMs in 72-p in sockets, th ereby savin g you th e exp en se of h avin g to scrap all th ose old 30-p in SIMMs you h ave lyin g arou n d . Again , su ch ad ap ters can cau se p roblem s—esp ecially if overh ead clearan ce is tigh t—so in vestigate carefu lly before you bu y. W ith th e fallin g p rices of SIMMs tod ay, you are p robably better off stayin g with 72p in SIMMs an d 168-p in DIMMs. Rem em ber th at som e old er h igh -p erform an ce 486 system s u se in terleaved m em ory to red u ce wait states. Th is req u ires a m u ltip le of two 72-p in 36-bit (32-bit) SIMMs becau se in terleaved m em ory access is altern ated between th e SIMMs to im p rove p erform an ce. Th u s, a 32-bit p rocessor en d s u p u sin g two 32-bit ban ks togeth er in an altern atin g fash ion .

Physical M emory

Not e A bank is the smallest amount of memory that can be addressed by the processor at one time and usually corresponds to the data bus width of the processor. If the memory is interleaved, a virtual bank may be twice the absolute data bus width of the processor.

You can n ot always rep lace a SIMM with a greater-cap acity u n it an d exp ect it to work. System s m ay h ave sp ecific d esign lim itation s as to th e m axim u m cap acity of SIMM th ey will take. A larger-cap acity SIMM works on ly if th e m oth erboard is d esign ed to accep t it in th e first p lace. Con su lt you r system d ocu m en tation to d eterm in e th e correct cap acity an d sp eed to u se. All system s on th e m arket tod ay u se SIMMs, an d m an y u se DIMMs. Th e SIMM/ DIMM is n ot a p rop rietary m em ory system , bu t an in d u stry-stan d ard d evice. As m en tion ed , som e SIMMs h ave sligh tly d ifferen t p in ou ts an d sp ecification s oth er th an sp eed an d cap acity, so be su re th at you obtain th e correct SIMMs for you r system . SIM M Pinout s Tables 5.5 an d 5.6 sh ow th e in terface con n ector p in ou ts for both 30-p in SIMM varieties an d th e stan d ard 72-p in version . Also in clu d ed is a sp ecial p resen ce d etect table th at sh ows th e con figu ration of th e p resen ce d etect p in s on variou s 72-p in SIMMs. Th e p resen ce d etect p in s are u sed by th e m oth erboard to d etect exactly wh at size an d sp eed SIMM is in stalled . In d u stry-stan d ard 30-p in SIMMs d o n ot h ave a p resen ce d etect featu re, bu t IBM d id ad d th is cap ability to th eir m od ified 30-p in con figu ration . Table 5.5

Indust ry-St andard and IBM 30-Pin SIM M Pinout s

Pin

St andard SIM M Signal Nam es

IBM SIM M Signal Nam es

1

+5 Vdc

+5 Vdc

2

Column Address Strobe

Column Address Strobe

3

Data Bit 0

Data Bit 0

4

Address Bit 0

Address Bit 0

5

Address Bit 1

Address Bit 1

6

Data Bit 1

Data Bit 1

7

Address Bit 2

Address Bit 2

8

Address Bit 3

Address Bit 3

9

Ground

Ground

10

Data Bit 2

Data Bit 2

11

Address Bit 4

Address Bit 4

12

Address Bit 5

Address Bit 5

13

Data Bit 3

Data Bit 3

14

Address Bit 6

Address Bit 6

15

Address Bit 7

Address Bit 7

16

Data Bit 4

Data Bit 4 (continues)

329

330

Chapter 5—M emory

Table 5.5

Indust ry-St andard and IBM 30-Pin SIM M Pinout s Cont inued

Pin

St andard SIM M Signal Nam es

IBM SIM M Signal Nam es

17

Address Bit 8

Address Bit 8

18

Address Bit 9

Address Bit 9

19

Address Bit 10

Row Address Strobe 1

20

Data Bit 5

Data Bit 5

21

Write Enable

Write Enable

22

Ground

Ground

23

Data Bit 6

Data Bit 6

24

No Connection

Presence Detect (Ground)

25

Data Bit 7

Data Bit 7

26

Data Bit 8 (Parity) Out

Presence Detect (1M = Ground)

27

Row Address Strobe

Row Address Strobe

28

Column Address Strobe Parity

No Connection

29

Data Bit 8 (Parity) In

Data Bit 8 (Parity) I/ O

30

+5 Vdc

+5 Vdc

Table 5.6

St andard 72-Pin SIM M Pinout

Pin

SIM M Signal Nam e

Pin

SIM M Signal Nam e

1

Ground

22

Data Bit 5

2

Data Bit 0

23

Data Bit 21

3

Data Bit 16

24

Data Bit 6

4

Data Bit 1

25

Data Bit 22

5

Data Bit 17

26

Data Bit 7

6

Data Bit 2

27

Data Bit 23

7

Data Bit 18

28

Address Bit 7

8

Data Bit 3

29

Address Bit 11

9

Data Bit 18

30

+5 Vdc

10

+5 Vdc

31

Address Bit 8

11

Presence Detect 5

32

Address Bit 9

12

Address Bit 0

33

Row Address Strobe 3

13

Address Bit 1

34

Row Address Strobe 2

14

Address Bit 2

35

Parity Data Bit 2

15

Address Bit 3

36

Parity Data Bit 0

16

Address Bit 4

37

Parity Data Bit 1

17

Address Bit 5

38

Parity Data Bit 3

18

Address Bit 6

39

Ground

19

Address Bit 10

40

Column Address Strobe 0

20

Data Bit 4

41

Column Address Strobe 2

21

Data Bit 20

42

Column Address Strobe 3

Physical M emory

Pin

SIM M Signal Nam e

Pin

SIM M Signal Nam e

43

Column Address Strobe 1

58

Data Bit 28

44

Row Address Strobe 0

59

+5 Vdc

45

Row Address Strobe 1

60

Data Bit 29

46

Reserved

61

Data Bit 13

47

Write Enable

62

Data Bit 30

48

ECC Optimized

63

Data Bit 14

49

Data Bit 8

64

Data Bit 31

50

Data Bit 24

65

Data Bit 15

51

Data Bit 9

66

Reserved

52

Data Bit 25

67

Presence Detect 1

53

Data Bit 10

68

Presence Detect 2

54

Data Bit 26

69

Presence Detect 3

55

Data Bit 11

70

Presence Detect 4

56

Data Bit 27

71

Reserved

57

Data Bit 12

72

Ground

Notice th at th e 72-p in SIMMs em p loy a set of fou r or five p in s to in d icate th e typ e of SIMM to th e m oth erboard . Th ese p resen ce d etect p in s are eith er grou n d ed or n ot con n ected to in d icate th e typ e of SIMM to th e m oth erboard . Presen ce d etect ou tp u ts m u st be tied to th e grou n d th rou gh a zero-oh m resistor on th e SIMM—to gen erate a h igh logic level wh en th e p in is op en or low logic level wh en th e p in is grou n d ed by th e m oth erboard . Th is p rod u ces sign als th at are d ecod able by th e m em ory in terface logic. If p resen ce d etect sign als are em p loyed by th e m oth erboard , th en a Power-On Self Test p roced u re can d eterm in e th e size an d sp eed of th e in stalled SIMMs an d ad ju st con trol an d ad d ressin g sign als au tom atically. Th is allows th e m em ory size an d sp eed to be au tod etected .

Not e In many ways, this is similar to the industry-standard DX code used on modern 35mm film rolls to indicate the ASA (speed) rating of the film to the camera. When you drop the film into the camera, electrical contacts can read the film’s speed rating via an industry standard configuration.

Table 5.7 sh ows th e JEDEC in d u stry stan d ard p resen ce d etect con figu ration listin g for th e 72-p in SIMM fam ily. JEDEC is th e Join t Electron ic Devices En gin eerin g Cou n cil, an organ ization of th e U.S. sem icon d u ctor m an u factu rers an d u sers th at sets p ackage ou tlin e d im en sion an d oth er stan d ard s for ch ip an d m od u le p ackages. Table 5.7

Presence Det ect Pin Configurat ions for 72-Pin SIM M s

Size

Speed

Pin 67

Pin 68

Pin 69

Pin 70

Pin 11

1M

100ns

Gnd

-

Gnd

Gnd

-

1M

80ns

Gnd

-

-

Gnd

(continues)

331

332

Chapter 5—M emory

Table 5.7

Presence Det ect Pin Configurat ions for 72-Pin SIM M s Cont inued

Size

Speed

Pin 67

Pin 68

Pin 69

Pin 70

Pin 11

1M

70ns

Gnd

-

Gnd

-

-

1M

60ns

Gnd

-

-

-

-

2M

100ns

-

Gnd

Gnd

Gnd

-

2M

80ns

-

Gnd

-

Gnd

-

2M

70ns

-

Gnd

Gnd

-

-

2M

60ns

-

Gnd

-

-

-

4M

100ns

Gnd

Gnd

Gnd

Gnd

-

4M

80ns

Gnd

Gnd

-

Gnd

-

4M

70ns

Gnd

Gnd

Gnd

-

-

4M

60ns

Gnd

Gnd

-

-

-

8M

100ns

-

-

Gnd

Gnd

-

8M

80ns

-

-

-

Gnd

-

8M

70ns

-

-

Gnd

-

-

8M

60ns

-

-

-

-

-

16M

80ns

Gnd

-

-

Gnd

Gnd

16M

70ns

Gnd

-

Gnd

-

Gnd

16M

60ns

Gnd

-

-

-

Gnd

16M

50ns

Gnd

-

Gnd

Gnd

Gnd

32M

80ns

-

Gnd

-

Gnd

Gnd

32M

70ns

-

Gnd

Gnd

-

Gnd

32M

60ns

-

Gnd

-

-

Gnd

32M

50ns

-

Gnd

Gnd

Gnd

Gnd

- = No Connection (open) Gnd = Ground Pin 67 = Presence detect 1 Pin 68 = Presence detect 2 Pin 69 = Presence detect 3 Pin 70 = Presence detect 4 Pin 11 = Presence detect 5

Un fortu n ately, u n like th e film in d u stry, n ot everybod y in th e com p u ter in d u stry follows establish ed stan d ard s. As su ch , p resen ce d etect sign alin g is n ot a stan d ard th rou gh ou t th e PC in d u stry. Differen t system m an u factu rers som etim es u se d ifferen t con figu ration s for wh at is exp ected on th ese fou r p in s. Com p aq , IBM (m ain ly PS/ 2 system s), an d Hewlett-Packard are n otoriou s for th is typ e of beh avior; m an y of th eir system s req u ire sp ecial SIMMs th at are basically th e sam e as stan d ard 72-p in SIMMs, excep t for sp ecial p resen ce d etect req u irem en ts. Table 5.8 sh ows h ow IBM d efin es th ese p in s.

Physical M emory

Table 5.8

72-Pin SIM M Presence Det ect Pins

67

68

69

70

SIM M Type

IBM Part Num ber

-

-

-

-

Not a valid SIM M

N/ A

Gnd

-

-

-

1M 120ns

N/ A

-

Gnd

-

-

2M 120ns

N/ A

Gnd

Gnd

-

-

2M 70ns

92F0102

-

-

Gnd

-

8M 70ns

64F3606

Gnd

-

Gnd

-

Reserved

N/ A

-

Gnd

Gnd

-

2M 80ns

92F0103

Gnd

Gnd

Gnd

-

8M 80ns

64F3607

-

-

-

Gnd

Reserved

N/ A

Gnd

-

-

Gnd

1M 85ns

90X8624

-

Gnd

-

Gnd

2M 85ns

92F0104

Gnd

Gnd

-

Gnd

4M 70ns

92F0105

-

-

Gnd

Gnd

4M 85ns

79F1003 (square notch) L40-SX

Gnd

-

Gnd

Gnd

1M 100ns

N/ A

Gnd

-

Gnd

Gnd

8M 80ns

79F1004 (square notch) L40-SX

-

Gnd

Gnd

Gnd

2M 100ns

N/ A

Gnd

Gnd

Gnd

Gnd

4M 80ns

87F9980

Gnd

Gnd

Gnd

Gnd

2M 85ns

79F1003 (square notch) L40SX

- = No Connection (open) Gnd = Ground Pin 67 = Presence detect 1 Pin 68 = Presence detect 2 Pin 69 = Presence detect 3 Pin 70 = Presence detect 4

Cu stom variation s on th ese p in s are wh y you m u st often sp ecify IBM, Com p aq , HP, or gen eric SIMMs wh en you ord er m em ory. Table 5.9 sh ows th e p in ou t con figu ration of a 168-p in stan d ard u n bu ffered SDRAM DIMM. Table 5.9

168-Pin SDRAM DIM M Pinout s

Pin

x64 Non-Parit y

x72 Parit y/ ECC

Pin

x64 Non-Parit y

x72 Parit y/ ECC

1

Gnd

Gnd

85

Gnd

Gnd

2

Data Bit 0

Data Bit 0

86

Data Bit 32

Data Bit 32

3

Data Bit 1

Data Bit 1

87

Data Bit 33

Data Bit 33

4

Data Bit 2

Data Bit 2

88

Data Bit 34

Data Bit 34

5

Data Bit 3

Data Bit 3

89

Data Bit 35

Data Bit 35

6

+5V

+5V

90

+5V

+5V (continues)

333

334

Chapter 5—M emory

Table 5.9

168-Pin SDRAM DIM M Pinout s Cont inued

Pin

x64 Non-Parit y

x72 Parit y/ ECC

Pin

x64 Non-Parit y

x72 Parit y/ ECC

7

Data Bit 4

Data Bit 4

91

Data Bit 36

Data Bit 36

8

Data Bit 5

Data Bit 5

92

Data Bit 37

Data Bit 37

9

Data Bit 6

Data Bit 6

93

Data Bit 38

Data Bit 38

10

Data Bit 7

Data Bit 7

94

Data Bit 39

Data Bit 39

11

Data Bit 8

Data Bit 8

95

Data Bit 40

Data Bit 40

12

Gnd

Gnd

96

Gnd

Gnd

13

Data Bit 9

Data Bit 9

97

Data Bit 41

Data Bit 41

14

Data Bit 10

Data Bit 10

98

Data Bit 42

Data Bit 42

15

Data Bit 11

Data Bit 11

99

Data Bit 43

Data Bit 43

16

Data Bit 12

Data Bit 12

100

Data Bit 44

Data Bit 44

17

Data Bit 13

Data Bit 13

101

Data Bit 45

Data Bit 45

18

+5V

+5V

102

+5V

+5V

19

Data Bit 14

Data Bit 14

103

Data Bit 46

Data Bit 46

20

Data Bit 15

Data Bit 15

104

Data Bit 47

Data Bit 47

21

-

Check Bit 0

105

-

Check Bit 4

22

-

Check Bit 1

106

-

Check Bit 5

23

Gnd

Gnd

107

Gnd

Gnd

24

-

-

108

-

-

25

-

-

109

-

-

26

+5V

+5V

110

+5V

+5V

27

Write Enable

Write Enable

111

Column Address Strobe

Column Address Strobe

28

Byte M ask 0

Byte M ask 0

112

Byte M ask 4

Byte M ask 4

29

Byte M ask 1

Byte M ask 1

113

Byte M ask 5

Byte M ask 5

30

S0

S0

114

S1

S1

31

Reserved

Reserved

115

Row Address Strobe

Row Address Strobe

32

Gnd

Gnd

116

Gnd

Gnd

33

Address Bit 0

Address Bit 0

117

Address Bit 1

Address Bit 1

34

Address Bit 2

Address Bit 2

118

Address Bit 3

Address Bit 3

35

Address Bit 4

Address Bit 4

119

Address Bit 5

Address Bit 5

36

Address Bit 6

Address Bit 6

120

Address Bit 7

Address Bit 7

37

Address Bit 8

Address Bit 8

121

Address Bit 9

Address Bit 9

38

Address Bit 10

Address Bit 10

122

Bank Address 0

Bank Address 0

39

Bank Address 1

Bank Address 1

123

Address Bit 11

Address Bit 11

40

+5V

+5V

124

+5V

+5V

41

+5V

+5V

125

Clock 1

Clock 1

42

Clock 0

Clock 0

126

Address Bit 12

Address Bit 12

Physical M emory

Pin

x64 Non-Parit y

x72 Parit y/ ECC

Pin

x64 Non-Parit y

x72 Parit y/ ECC

43 44

Gnd

Gnd

127

Gnd

Gnd

Reserved

Reserved

128

Clock Enable 0

Clock Enable 0

45

S2

S2

129

S3

S3

46

Byte M ask 2

Byte M ask 2

130

Byte M ask 6

Byte M ask 6

47

Byte M ask 3

Byte M ask 3

131

Byte M ask 7

Byte M ask 7

48

Reserved

Reserved

132

Address Bit 13

Address Bit 13

49

+5V

+5V

133

+5V

+5V

50

-

-

134

-

-

51

-

-

135

-

-

52

-

Check Bit 2

136

-

Check Bit 6

53

-

Check Bit 3

137

-

Check Bit 7

54

Gnd

Gnd

138

Gnd

Gnd

55

Data Bit 16

Data Bit 16

139

Data Bit 48

Data Bit 48

56

Data Bit 17

Data Bit 17

140

Data Bit 49

Data Bit 49

57

Data Bit 18

Data Bit 18

141

Data Bit 50

Data Bit 50

58

Data Bit 19

Data Bit 19

142

Data Bit 51

Data Bit 51

59

+5V

+5V

143

+5V

+5V

60

Data Bit 20

Data Bit 20

144

Data Bit 52

Data Bit 52

61

-

-

145

-

-

62

Voltage Reference

Voltage Reference

146

Voltage Reference

Voltage Reference

63

Clock Enable 1

Clock Enable 1

147

-

-

64

Gnd

Gnd

148

Gnd

Gnd

65

Data Bit 21

Data Bit 21

149

Data Bit 53

Data Bit 53

66

Data Bit 22

Data Bit 22

150

Data Bit 54

Data Bit 54

67

Data Bit 23

Data Bit 23

151

Data Bit 55

Data Bit 55

68

Gnd

Gnd

152

Gnd

Gnd

69

Data Bit 24

Data Bit 24

153

Data Bit 56

Data Bit 56

70

Data Bit 25

Data Bit 25

154

Data Bit 57

Data Bit 57

71

Data Bit 26

Data Bit 26

155

Data Bit 58

Data Bit 58

72

Data Bit 27

Data Bit 27

156

Data Bit 59

Data Bit 59

73

+5V

+5V

157

+5V

+5V

74

Data Bit 28

Data Bit 28

158

Data Bit 60

Data Bit 60

75

Data Bit 29

Data Bit 29

159

Data Bit 61

Data Bit 61

76

Data Bit 30

Data Bit 30

160

Data Bit 62

Data Bit 62

77

Data Bit 31

Data Bit 31

161

Data Bit 63

Data Bit 63

78

Gnd

Gnd

162

Gnd

Gnd

79

Clock 2

Clock 2

163

Clock 3

Clock 3

80

-

-

164

-

(continues)

335

336

Chapter 5—M emory

Table 5.9

168-Pin SDRAM DIM M Pinout s Cont inued

Pin

x64 Non-Parit y

x72 Parit y/ ECC

Pin

x64 Non-Parit y

x72 Parit y/ ECC

81

-

-

165

Serial PD Address 0

Serial PD Address 0

82

Serial Data I/ O

Serial Data I/ O

166

Serial PD Address 1

Serial PD Address 1

83

Serial Clock Input

Serial Clock Input

167

Serial PD Address 2

Serial PD Address 2

84

+5V

+5V

168

+5V

+5V

- = No Connection (open) Gnd = Ground

Th e DIMM u ses a com p letely d ifferen t typ e of Presen ce Detect called Serial Presen ce Detect. Th is con sists of a sm all EEPROM (Electrically Erasable Program m able Read On ly Mem ory) or even a flash m em ory ch ip on th e DIMM th at con tain s sp ecially form atted d ata in d icatin g th e featu res of th e DIMM. Th is serial d ata can be read via th e serial d ata p in s on th e DIMM, an d allows th e m oth erboard to au tocon figu re to th e exact typ e of DIMM in stalled . Physical RAM Capacit y and Organizat ion Several typ es of m em ory ch ip s h ave been u sed in PC system m oth erboard s. Most of th ese ch ip s are sin gle-bit-wid e ch ip s, available in several cap acities. Th e followin g table lists available RAM ch ip s an d th eir cap acities: RAM Chip

Capacit y

16K by 1 bit

These devices were used in the original IBM PC with a Type 1 motherboard.

64K by 1 bit

These chips were used in the standard IBM PC Type 2 motherboard and in the XT Type 1 and 2 motherboards. M any memory adapters of the era, such as the popular vintage AST six-pack boards, also used these chips.

128K by 1 bit

These chips, used in the IBM AT Type 1 motherboard, often were a strange physical combination of two 64K chips stacked one on top of the other and soldered together. Single-chip versions were used also for storing the parity bits in the IBM XT 286.

256K by 1 bit (or 64K by 4 bits)

These chips once were very popular in motherboards and memory cards. The IBM XT Type 2 and IBM AT Type 2 motherboards, and most compatible systems of that era used these chips.

1M by 1 bit (or 256K by 4 bits)

1M chips were very popular for a number of years and were most often used in 256K to 8M SIM M s.

4M by 1 bit (or 1M by 4 bits)

4M chips are used primarily in SIM M s from 1M to 16M in capacity. They are used primarily in 4M and 8M SIM M s and generally are not sold as individual chips.

16M by 1 bit (or 4M by 4 bits)

16M chips are often used in 72-pin SIM M s of 16M to 32M capacity.

Physical M emory

RAM Chip

Capacit y

64M by 1 bit (or 16M by 4 bits)

64M chips are popular in high-capacity 16M or larger memory modules, especially for notebook systems.

256M by 1 bit (or 64M by 4 bits)

256M chips are the most recent on the market. These chips allow enormous SIM M capacities of 128M or larger! Because of the high expense and limited availability of these chips, you see them only in the most expensive and highest capacity modules on the market.

Note th at ch ip cap acity n orm ally goes u p by factors of 4 becau se th e d ie th at m ake u p th e ch ip s are sq u are. W h en th ey in crease cap acity, th is n orm ally resu lts in 4 tim es m ore tran sistors an d 4 tim es m ore cap acity. Most m od ern SIMMs an d DIMMs u se 16M-bit to 256M-bit ch ip s on board . Figu re 5.8 sh ows th e m arkin gs on a typ ical old er m em ory ch ip . Man y m em ory m an u factu rers u se sim ilar sch em es for n u m berin g th eir ch ip s; h owever, if you are really tryin g to id en tify a p articu lar ch ip , it is best to con su lt th e m an u factu rer catalog for m ore in form ation .

F

MB81256-10 8609 B04 BC

USA

FIG. 5.8 Th e m arkin gs on a typ ical old er m em ory ch ip . Th e -10 on th e ch ip corresp on d s to its sp eed in n an osecon d s (a 100-n an osecon d ratin g). MB81256 is th e ch ip ’s p art n u m ber, wh ich u su ally con tain s a clu e abou t th e ch ip ’s cap acity. Th e key d igits are 1256, wh ich in d icate th at th is ch ip is 1 bit wid e an d h as a d ep th of 256K. Th e 1 m ean s th at to m ake a fu ll byte with p arity, you n eed n in e of th ese sin gle-bit-wid e ch ip s. A ch ip with a p art n u m ber KM4164B-10 in d icates a 64K-by-1-bit ch ip at a sp eed of 100 n an osecon d s. Th e followin g list m atch es com m on ch ip s with th eir in d u stry-stan d ard p art n u m bers: Part Num ber

Chip

4164

64K by 1 bit

4464

64K by 4 bits

41128

128K by 1 bit

44128

128K by 4 bits

41256

256K by 1 bit

44256

256K by 4 bits

41000

1M by 1 bit

44000

1M by 4 bits

337

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Chapter 5—M emory

Ch ip s wid er th an 1 bit are u sed to con stru ct ban ks of less th an 9, 18, or 36 ch ip s (d ep en d in g on th e system arch itectu re). For exam p le, a 32-bit SIMM can be con stru cted of on ly eigh t 4-bit wid e ch ip s. In Figu re 5.8, th e “F” sym bol cen tered between two lin es is th e m an u factu rer’s logo for Fu jitsu Microelectron ics. Th e 8609 in d icates th e d ate of m an u factu re (n in th week of 1986). Som e m an u factu rers, h owever, u se a Ju lian d ate cod e. To d ecod e th e ch ip fu rth er, con tact th e m an u factu rer or ch ip ven d or. SIMMs an d DIMMs also h ave p art n u m bers th at can be d ifficu lt to d ecod e. Un fortu n ately, th ere is n o in d u stry stan d ard for n u m berin g th ese m od u les, so you will h ave to con tact th e m an u factu rer if you wan t to d ecod e th e n u m bers. Figu re 5.9 sh ows h ow Micron Tech n ology (also Cru cial Tech n ology) SIMMs are en cod ed .

MT4LC1M16E5TG-6 S ES Micron Technology Product Family 4 = DRAM 41 = SGRAM 48 = Synchronous DRAM Process Technology C = 5V Vcc CMOS LC = 3.3V Vcc CMOS Device Number Depth, Width No Letter = Bits K = Kilobits M = Megabits G = Gigabits Device Versions (The first character is an alphabetic character only; the second character is a numeric character only.) Specified by individual data sheet only.

Special Processing ES = Engineering Sample MS = Mechanical Sample Refresh Options (Multiple processing codes are separated by a space and are listed in hierarchical order.) L = Low Power (Extended Refresh) S = Self Refresh Access/Cycle Time DRAM SGRAM and SDRAM (Access Time) (Cycle Time) –4 = 40ns –15 = 66MHz –5 = 50ns –12 = 83MHz –6 = 60ns –10 = 100MHz –7 = 70ns –8 = 125MHz –7 = 143MHz Package Codes LG = TQFP TG = TSOP (Type II) DJ = SOJ DW = SOJ (Wide)

FIG. 5.9 Typ ical SIMM p art n u m bers for Micron (Cru cial Tech n ology) SIMMs. M em ory Banks Mem ory ch ip s (DIPs, SIMMs, SIPPs, an d DIMMs) are organ ized in banks on m oth erboard s an d m em ory card s. You sh ou ld kn ow th e m em ory ban k layou t an d p osition on th e m oth erboard an d m em ory card s. You n eed to kn ow th e ban k layou t wh en ad d in g m em ory to th e system . In ad d ition , m em ory d iagn ostics rep ort error location s by byte an d bit ad d resses, an d you m u st u se th ese n u m bers to locate wh ich ban k in you r system con tain s th e p roblem . Th e ban ks u su ally corresp on d to th e d ata bu s cap acity of th e system ’s m icrop rocessor. Table 5.10 sh ows th e wid th s of in d ivid u al ban ks based on th e typ e of PC.

Physical M emory

Table 5.10

M em ory Bank W idt hs on Different Syst em s

Processor

M em ory M em ory Bank Size Bank Size Dat a Bus ( No Parit y) ( Parit y)

8088

8-bit

8-bits

9-bits

30-Pin SIM M s per Bank 1

72-Pin SIM M s per Bank N/ A

168-Pin SIM M s per Bank N/ A

8086

16-bit

16-bits

18-bits

2

N/ A

N/ A

286

16-bit

16-bits

18-bits

2

N/ A

N/ A

386SX, SL, SLC

16-bit

16-bits

18-bits

2

N/ A

N/ A

386DX

32-bit

32-bits

36-bits

4

1

N/ A

486SLC, SLC2

16-bit

16-bits

18-bits

2

N/ A

N/ A

486SX, DX, DX2,DX4

32-bit

32-bits

36-bits

4

1

N/ A

Pentium

64-bit

64-bits

72-bits

8

2

1

Pentium Pro, PII

64-bit

64-bits

72-bits

8

2

1

Th e n u m ber of bits for each ban k can be m ad e u p of sin gle ch ip s, SIMMs, or DIMMs. Mod ern system s d on ’t u se in d ivid u al ch ip s, bu t on ly SIMMs or DIMMs, in stead . If th e system h as a 16-bit p rocessor su ch as a 386SX, it wou ld p robably u se 30-p in SIMMs an d h ave two SIMMs p er ban k. All th e SIMMs in a sin gle ban k m u st be th e sam e size an d typ e. A 486 system wou ld req u ire fou r 30-p in SIMMs or on e 72-p in SIMM to m ake u p a ban k. A sin gle 72-p in SIMM is 32 bits wid e or 36 bits wid e if it su p p orts p arity. You can often tell wh eth er or n ot a SIMM su p p orts p arity by cou n tin g its ch ip s. To m ake a 32-bit SIMM, you cou ld u se 32 in d ivid u al 1-bit-wid e ch ip s, or you cou ld u se eigh t in d ivid u al 4-bit-wid e ch ip s to m ake u p th e d ata bits. If th e system u sed p arity, th en fou r extra bits wou ld be req u ired (36 bits total), so you wou ld see on e m ore 4-bit-wid e or fou r in d ivid u al 1-bit-wid e ch ip s ad d ed to th e ban k for th e p arity bits. As you m igh t im agin e, 30-p in SIMMs are less th an id eal for 32-bit or 64-bit system s (i.e., 486 or Pen tiu m ) becau se you m u st u se th em in in crem en ts of fou r or eigh t p er ban k! Becau se th ese SIMMs are available in 1M, 4M, an d 16M cap acities tod ay, th is m ean s th at a sin gle ban k of 30-p in SIMMs in a 486 system wou ld be 4M, 16M, or 64M; for a Pen tiu m system , th is wou ld be 8M, 32M, or 128M of m em ory, with n o in -between am ou n ts. Usin g 30-p in SIMMs in 32- an d 64-bit system s artificially con strain s m em ory con figu ration s an d su ch system s are n ot recom m en d ed . If a 32-bit system (su ch as an y PC with a 486 p rocessor) u ses 72-p in SIMMs, each SIMM rep resen ts a sep arate ban k, an d th e SIMMs can be ad d ed or rem oved on an in d ivid u al basis rath er th an in grou p s of fou r, as wou ld be req u ired with 30-p in SIMMs. Th is m akes m em ory con figu ration m u ch easier an d m ore flexible. In m od ern 64-bit system s th at u se SIMMs, two 72-p in SIMMs are req u ired p er ban k. DIMMs are id eal for Pen tiu m an d h igh er system s, as th e 64-bit wid th of th e DIMM exactly m atch es th e 64-bit wid th of th e Pen tiu m p rocessor d ata bu s. Th is m ean s th at each DIMM rep resen ts an in d ivid u al ban k, an d th ey can be ad d ed or rem oved on e at a tim e.

339

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Th e p h ysical orien tation an d n u m berin g of th e SIMMs or DIMMs u sed on a m oth erboard is arbitrary an d d eterm in ed by th e board ’s d esign ers. Docu m en tation coverin g you r system or card com es in very h an d y. You can d eterm in e th e layou t of a m oth erboard or ad ap ter card th rou gh testin g, bu t th is takes tim e an d m ay be d ifficu lt, p articu larly after you h ave a p roblem with a system . RAM Chip Speed PC m em ory sp eed s vary from abou t 10n s to 200n s. W h en you rep lace a failed m em ory m od u le, you m u st in stall a m od u le of th e sam e typ e an d sp eed as th e failed m od u le. You can su bstitu te a ch ip with a d ifferen t sp eed on ly if th e sp eed of th e rep lacem en t ch ip is eq u al to or faster th an th at of th e failed ch ip . Som e p eop le h ave h ad p roblem s wh en “m ixin g” ch ip s becau se th ey u sed a ch ip th at d id n ot m eet th e m in im u m req u ired sp ecification s (for exam p le, refresh tim in g sp ecification s) or was in com p atible in p in ou t, d ep th , wid th , or d esign . Ch ip access tim e always can be less (th at is, faster) as lon g as you r ch ip is th e correct typ e an d m eets all oth er sp ecification s. Su bstitu tin g faster m em ory u su ally d oesn ’t p rovid e im p roved p erform an ce becau se th e system still op erates th e m em ory at th e sam e sp eed . In system s n ot en gin eered with a great d eal of “forgiven ess” in th e tim in g between m em ory an d system , h owever, su bstitu tin g faster m em ory ch ip s m igh t im p rove reliability. To p lace m ore em p h asis on tim in g an d reliability, In tel h as created stan d ard s for th e n ew h igh -sp eed 100MHz m em ory su p p orted by th eir n ewer ch ip sets. Th is is called th e PC/ 100 stan d ard , an d it is a stan d ard by wh ich m em ory m od u les can be certified to p erform with in In tel’s tim in g an d p erform an ce gu id elin es. At 100MHz, th ere is n ot very m u ch “forgiven ess” or slop allowable in m em ory tim in g. Th e sam e com m on sym p tom s resu lt wh en th e system m em ory h as failed or is sim p ly n ot fast en ou gh for th e system ’s tim in g. Th e u su al sym p tom s are freq u en t p arity ch eck errors or a system th at d oes n ot op erate at all. Th e POST also m igh t rep ort errors. If you ’re u n su re of wh at ch ip s to bu y for you r system , con tact th e system m an u factu rer or a rep u table ch ip su p p lier. ◊◊ See “ Parity Checking,” p. 347

Gold Versus Tin Man y p eop le d on ’t u n d erstan d th e im p ortan ce of th e SIMM an d DIMM electrical con tacts in a com p u ter system . Both SIMMs an d DIMMs are available in gold or tin -p lated con tact form . I in itially th ou gh t th at gold con tact SIMMs or DIMMs were th e best way to go for reliability in all situ ation s, bu t th at is n ot tru e. To h ave th e m ost reliable system , you m u st in stall SIMMs or DIMMs with gold -p lated con tacts in to gold -p lated sockets an d SIMMs or DIMMs with tin -p lated con tacts in to on ly tin -p lated sockets.

Physical M emory

If you d on ’t h eed th is warn in g an d in stall m em ory with gold -p lated con tacts in to tin sockets or vice versa, you will exp erien ce m em ory errors at a fu tu re d ate. In m y exp erien ces, th is will occu r between six m on th s to on e year after in stallation . I h ave en cou n tered th is several tim es in m y own system s an d in several system s I h ave serviced . I h ave even been asked to assist on e cu stom er in a lawsu it, wh ere th e cu stom er p u rch ased several h u n d red m ach in es from a ven d or, an d severe m em ory failu res began ap p earin g in m ost of th e m ach in es ap p roxim ately a year after d elivery. Th e cau se was traced to d issim ilar m etals between th e m em ory m od u les an d sockets (gold SIMMs in tin sockets, in th is case). Th e ven d or refu sed to rep lace th e SIMMs with tin -p lated version s, h en ce th e lawsu it. Most In tel Pen tiu m an d 486 m oth erboard s th at were d esign ed to accep t 72-p in SIMMs h ave tin -p lated sockets, so th ey m u st h ave tin -p lated m em ory. In tel n ow sp ecifically recom m en d s not m ixin g d issim ilar m etals in a system ’s m em ory. Stu d ies d on e by th e con n ector m an u factu rers sh ow th at a typ e of corrosion called fretting occu rs wh en tin com es in p ressu re con tact with gold or an y oth er m etal. Frettin g corrosion is wh ere tin oxid e tran sfers to th e gold su rface an d h ard en s, even tu ally cau sin g a h igh resistan ce con n ection . Th is occu rs wh ere gold com es in to con tact with tin , n o m atter h ow th ick or th in th e gold coatin g. Over tim e, d ep en d in g on th e en viron m en t frettin g, corrosion can an d will cau se h igh resistan ce at th e con tact p oin t an d th u s cau se m em ory errors. On e wou ld th in k th at tin wou ld m ake a p oor con n ector m aterial becau se it d oes read ily oxid ize. Even so, electrical con tact is easily m ad e between two tin su rfaces u n d er p ressu re becau se th e oxid es on both soft su rfaces will ben d an d break, en su rin g con tact. Th is is esp ecially tru e in SIMMs or DIMMs wh ere a lot of p ressu re is p laced on th e con tacts. W h en tin an d gold com e in to con tact, becau se on e su rface is h ard , th e oxid ation bu ild s u p an d will n ot break easily u n d er p ressu re. In creased con tact resistan ce u ltim ately resu lts in m em ory failu res. Th e bottom lin e is th at you sh ou ld p lace on ly gold SIMMs in to gold sockets, an d on ly tin SIMMs in to tin sockets. Th e con n ector m an u factu rer AMP h as p u blish ed several d ocu m en ts from th e AMP Con tact Ph ysics Research Dep artm en t th at d iscu ss th is issu e, bu t th ere are two th at are m ost ap p licable. On e is titled Golden Rules: Guidelines for the Use of Gold on Connector Contacts, an d th e oth er is called The Tin Com m andm ents: Guidelines for the Use of Tin on Connector Contacts. Both can be d own load ed in .PDF form from th e AMP W eb site at h t t p / / w w w .a m p i n c o rp o ra t e d .c o m / . Here is an excerp t from th e Tin Com m andm ents, sp ecifically com m an d m en t Nu m ber Seven , wh ich states “7. Matin g of tin -coated con tacts to gold -coated con tacts is n ot recom m en d ed .” For fu rth er tech n ical d etails, you can con tact In tel or AMP at th e sites I h ave recom m en d ed . Certain ly, th e best typ e of setu p wou ld be gold to gold , as in h avin g gold -p lated SIMMs or DIMMs an d gold -p lated sockets on th e m oth erboard . Most h igh -en d file servers or oth er h igh -reliability system s are d esign ed th is way. In fact, m ost system s th at req u ire SDRAM DIMMs u se gold -p lated sockets an d th erefore req u ire SDRAM DIMMs with gold p lated con tacts.

341

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Chapter 5—M emory

If you h ave m ixed m etals in you r m em ory n ow, th e correct resp on se wou ld be to rep lace th e m em ory m od u les with th e ap p rop riate con tact typ e to m atch th e socket. An oth er m u ch less d esirable solu tion wou ld be to wait u n til p roblem s ap p ear (abou t six m on th s to a year in m y exp erien ce), th en rem ove th e m od u les, clean th e con tacts, rein stall, an d rep eat th e cycle. Th is is p robably fin e if you are an in d ivid u al with on e or two system s, bu t it is not fin e if you are m ain tain in g h u n d red s of system s. Note th at if you r system d oes n ot featu re p arity or ECC m em ory (m ost system s sold tod ay d o n ot), wh en th e p roblem s d o occu r, you m ay n ot be able to im m ed iately id en tify th em as m em ory related (Global Protection Fau lts, crash es, file an d d ata corru p tion , an d so on ). On e p roblem with clean in g is th at th e h ard tin oxid e d ep osits th at form on th e gold su rface are d ifficu lt to rem ove, an d often req u ire abrasive clean in g (su ch as by u sin g an eraser or crocu s cloth ). Th is sh ou ld n ever be d on e d ry becau se th is will gen erate static d isch arges th at can d am age th e ch ip s. In stead , u se a con tact clean er to lu bricate th e con tacts, wh ich wh en wet will m in im ize th e p oten tial for static d isch arge d am age wh en ru bbin g th e eraser or oth er abrasive on th e su rface. To fu rth er forestall th is p roblem from occu rrin g, I h igh ly recom m en d u sin g a liq u id con tact en h an cer an d lu brican t called Stabilan t 22 from DW Electroch em icals wh en in stallin g SIMMs or DIMMs. Th ey h ave a d etailed ap p lication n ote on th eir W eb site on th is su bject if you are in terested in m ore tech n ical d etails. Som e p eop le h ave accu sed m e of bein g too p icky by in sistin g th at th e m em ory m atch th e socket. On several occasion s, I h ave eith er retu rn ed m em ory or m oth erboard s becau se th e ven d or p u ttin g th em togeth er d id n ot h ave a clu e th is was a p roblem . W h en I tell som e p eop le abou t th is, th ey tell m e th ey h ave a lot of PCs ou t th ere with m ixed m etal con tacts th at ru n fin e an d , in m an y cases, h ave been d oin g so for m an y years. Of cou rse, th at is certain ly a p oor argu m en t again st d oin g th e righ t th in g. Th ere are a lot of p eop le ru n n in g SCSI bu ses th at are way too lon g, with im p rop er term in ation , an d th ey say it ru n s “fin e.” Parallel p ort cables are by th e sp ec lim ited to 10 feet in len gth , yet I see m an y h ave lon ger cables, wh ich th ey claim work “fin e.” Th e IDE cable lim it is 18 in ch es; th at sp ec is violated an d p eop le get away with it, sayin g th eir d rive ru n s ju st “fin e.” I see ch eap , cru m m y p ower su p p lies th at p u t ou t n oise, h ash , an d loosely regu lated voltages, an d I h ave even m easu red u p to 69 volts AC of grou n d leakage, an d yet th e system s were ru n n in g “fin e.” I h ave en cou n tered num erous system s with ou t p rop er CPU h eat sin ks, or wh ere th e active h eat sin k (fan ) was stalled , an d th e system ran “fin e.” Th is rem in d s m e of wh en Joh n n y Carson wou ld in terview 100-year-old p eop le an d wou ld often get th em to ad m it th at th ey d ran k h eavily an d sm oked cigarettes every d ay, as if th ose are good p ractices th at will en su re lon gevity! Th e tru th is I am often am azed at h ow p oorly d esign ed or im p lem en ted som e system s are, an d yet th ey d o seem to work… for th e m ost p art. Th e occasion al locku p or crash is ju st written off by th e u ser as “th at’s th ey way th ey all are.” All excep t m y system s, of cou rse. In m y system s, I ad h ere to p rop er d esign an d en gin eerin g p ractices; in fact, I am often gu ilty of en gin eerin g or sp ecifyin g overkill in to th in gs. Alth ou gh it ad d s to th e cost, th ey d o seem to ru n better becau se of it.

Physical M emory

In oth er word s, wh at on e in d ivid u al can “get away” with d oes n ot ch an ge th e laws of p h ysics—th is d oes n ot ch an ge th e fact th at for th ose su p p ortin g m an y system s or sellin g system s wh ere th e m axim u m in reliability an d service life is d esired , th e gold / tin issu e does m atter. An oth er issu e th at was brou gh t to m y atten tion was th e th ickn ess of th e gold on th e con tacts; p eop le are afraid th at it is so th in , it will wear off after on e or two in sertion s. Certain ly, th e ch oice of gold coatin g th ickn ess d ep en d s on th e d u rability req u ired by th e ap p lication ; d u e to th e h igh cost of gold , it is p ru d en t to keep th e gold coatin g th ickn ess as low as is ap p rop riate for th e d u rability req u irem en ts. An aid to d u rability is th at th e gold coatin gs are u su ally h ard en ed by ad d in g sm all am ou n ts of cobalt or n ickel to th e gold . Su ch coatin gs are d efin ed as “h ard gold ” an d p rod u ce coatin gs with a low coefficien t of friction an d excellen t d u rability ch aracteristics. Hard gold -coated con tacts can gen erally with stan d h u n d red s to th ou san d s of d u rability cycles with ou t failin g. Th e d u rability of h ard gold coatin gs can be en h an ced by u sin g an u n d erlayer h avin g a h ard n ess valu e th at is greater th an th at of gold an d wh ich will p rovid e m ech an ical su p p ort. Nickel is gen erally recom m en d ed as an u n d erlayer for th is p u rp ose. Lu brican ts are also effective at in creasin g th e d u rability of gold coatin gs. Gen erally, lu brication can in crease th e d u rability of a gold con tact by an ord er of m agn itu d e. In creasin g th e th ickn ess of a h ard gold coatin g in creases d u rability. Th e followin g laboratory resu lts were obtain ed by AMP for th e wear-th rou gh of a h ard gold coatin g to th e 1.3 m icron (50 m icroin ch ) th ick n ickel u n d erp late. Th e followin g d ata is for a 0.635 cm . (0.250 in .) d iam eter ball wip ed a d istan ce of 1.27 cm . (0.500 in .) u n d er a n orm al force of 100 gram s for each cycle. Thickness M icrons

Thickness M icro-in

Cycles t o Failure

0.4

15

200

0.8

30

1000

1.3

50

2000

As you can see from th is table, an 0.8 m icron (30 m icroin ch ) coatin g of h ard gold resu lts in d u rability th at is m ore th an ad eq u ate for m ost con n ector ap p lication s, as it wou ld allow 1,000 in sertion an d rem oval cycles before wearin g th rou gh . I stu d ied th e sp ecification sh eets for DIMM an d SIMM sockets p rod u ced by AMP an d fou n d th at th eir gold p lated sockets com e m ostly as .000030 (30 m icroin ch es)-th ick gold over .000050 (50 m icroin ch es)-th ick n ickel in th e con tact area. As far as I can d eterm in e, th e coatin g on virtu ally all SIMM an d DIMM con tacts wou ld be sim ilar in th ickn ess, allowin g for th e sam e d u rability. AMP also h as a few gold -p lated sockets with sp ecification s of .001020 (1,020 m icroin ch es)-th ick gold over .001270 (1,270 m icroin ch es)-th ick n ickel. I’d gu ess th at th e latter sockets were for d evices su ch as SIMM testers, wh ere m an y in sertion s were exp ected over th e life of th e eq u ip m en t. Th ey cou ld also be u sed in h igh vibration or very h igh h u m id ity en viron m en ts, as well.

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For referen ce, all th eir tin -con tact SIMM an d DIMM sockets h ave th e followin g con n ector p latin g sp ecification s: .000030 (30 m icroin ch es) m in im u m th ick tin on m atin g ed ge over .000050 (50 m icroin ch es) m in im u m th ick n ickel on en tire con tact. Th e bottom lin e is th at th e th ickn ess of th e coatin g in cu rren t SIMM an d DIMM sockets an d m od u les is n ot an issu e for th e exp ected u se of th ese d evices. Th e th ickn ess of th e p latin g u sed in cu rren t SIMM an d DIMM system s is also n ot relevan t with regard to th e tin versu s gold m atability issu e. Th e on ly d rawback to a th in n er gold p latin g is th at it will wear after fewer in sertion / rem oval cycles, exp osin g th e n ickel u n d ern eath an d allowin g th e on set of frettin g corrosion to occu r. In m y op in ion , th is tin / gold issu e will be even m ore im portant for th ose u sin g DIMMs. Th is will be for two reason s. W ith SIMMs, you really h ave two con n ection s for each p in (on e on each sid e of th e m od u le), so if on e of th em goes h igh resistan ce, it will n ot m atter; th ere is a bu ilt-in red u n d an cy. W ith DIMMs, you h ave m an y, m an y m ore con n ection s (168 versu s 72), an d n o red u n d an t con n ection s. Th e ch an ce for failu re will be m u ch greater. Also, m ost DIMM ap p lication s will be SDRAM, wh ere th e tim in g is d own in th e 15–10n s ran ge for 66MHz an d 100MHz board s, resp ectively. At th ese sp eed s, th e sligh test ad d ition al resistan ce in th e con n ection will cau se p roblem s. Becau se of th ese issu es, for th e fu tu re I wou ld sp ecify on ly m oth erboard s th at h ave gold p lated SDRAM DIMM con n ectors, an d th en , of cou rse, u se on ly SDRAMs with gold p lated con tacts. I n oted th at, for exam p le, Micron p rod u ces on ly SDRAM DIMMs with gold -p lated con tacts, an d all th e DIMM sockets I’ve seen so far are gold p lated , as well. I wou ld n ot cu rren tly recom m en d an y m oth erboard s u sin g tin -lead SDRAM DIMM con n ectors, n or wou ld I recom m en d p u rch asin g tin -lead SDRAM DIMMs. M em ory Reliabilit y A p art of th e n atu re of m em ory is th at it will in evitably fail. Th ese failu res are u su ally classified as two basic typ es: h ard fails an d soft errors. Th e m ost well u n d erstood are h ard fails, in wh ich th e ch ip is workin g an d th en , d u e to som e flaw, p h ysical d am age, or oth er even t, becom es d am aged an d exp erien ces a p erm an en t failu re. Fixin g th is typ e of failu re n orm ally req u ires rep lacem en t of som e p art of th e m em ory h ard ware, su ch as th e ch ip , SIMM, or DIMM. Hard error rates are kn own as HERs. Th e oth er m ore in sid iou s typ e of failu re is th e soft error. A soft error is a n on p erm an en t failu re th at m ay n ever reoccu r, or occu r at in freq u en t in tervals. (Soft fails are effectively “fixed ” by p owerin g th e system off an d back on .) Soft error rates are kn own as SERs. Abou t 20 years ago, In tel m ad e a d iscovery th at sh ook th e m em ory in d u stry with resp ect to soft errors. Th ey fou n d th at alp h a-p articles were cau sin g an u n accep tably h igh rate of soft errors or Sin gle Even t Up sets (SEUs, as th ey are som etim es called ) in th e 16K DRAMs th at were available at th e tim e. Becau se alp h a-p articles are low-en ergy p articles th at can be stop p ed by som eth in g as th in an d ligh t as a sh eet of p ap er, it becam e clear th at for alp h a-p articles to cau se a DRAM soft error, th ey wou ld h ave to be com in g from with in

Physical M emory

th e sem icon d u ctor m aterial. Testin g sh owed th at th ere were trace elem en ts of th oriu m an d u ran iu m fou n d in th e p lastic an d ceram ic ch ip p ackagin g m aterials u sed at th e tim e. Th is forced all th e m em ory m an u factu rers to evalu ate th eir m an u factu rin g p rocess to p rod u ce m aterials free from con tam in ation . Tod ay, th e m em ory m an u factu rers h ave all bu t totally elim in ated th e alp h a-p article sou rce of soft errors; d u e to th is, m an y were believin g th at th is was ju stification for th e in d u stry tren d to d rop p arity ch eckin g. Th e argu m en t is th at, for exam p le, a 16M m em ory su bsystem bu ilt with 4M tech n ology wou ld exp erien ce a soft error d u e to alp h ap articles on ly abou t on ce every 16 years! Th e real p roblem with th is th in kin g is th at it is seriou sly flawed , an d m an y system m an u factu rers an d ven d ors were cod d led in to rem ovin g p arity an d oth er m em ory fau lt-toleran t tech n iq u es from th eir system s even th ou gh soft errors con tin u e to be an on goin g p roblem . Th ere are m ore recen t d iscoveries th at p rove th at alp h a-p articles are n ow on ly a sm all fraction of th e cau se of DRAM soft errors! As it tu rn s ou t, th e biggest cau se of soft errors tod ay are cosm ic rays. IBM research ers began in vestigatin g th e p oten tial of terrestrial cosm ic rays in cau sin g soft errors sim ilar to alp h a-p articles. Th e d ifferen ce is th at cosm ic rays are very h igh -en ergy p articles an d can n ot be stop p ed by sh eets of p ap er or oth er m ore p owerfu l typ es of sh ield in g. Th e lead er in th is lin e of in vestigation was Dr. J. F. Ziegler of th e IBM W atson Research Cen ter in Yorktown Heigh ts, New York. He h as p rod u ced lan d m ark research in to th e u n d erstan d in g of cosm ic rays an d th eir in flu en ce on soft errors in m em ory. On e exam p le of th e m agn itu d e of th e cosm ic ray soft-error p h en om en on d em on strated th at with a certain sam p le of n on -IBM DRAMs, th e Soft Error Rate (SER)—as m easu red u n d er real-life con d ition s, an d with th e ben efit of m illion s of d evice h ou rs of testin g— at sea level was m easu red at 5950 FIT (Failu res in Tim e, wh ich is m easu red at 1 billion h ou rs) p er ch ip . In an average system with 36 m em ory ch ip s am on g th e SIMMs, th is wou ld resu lt in a soft error occu rrin g every six m on th s! In p ower u ser or server system s with a larger am ou n t of m em ory, th is cou ld m ean an error p er m on th or m ore. W h en th e exact sam e test setu p an d DRAMs were m oved to an u n d ergrou n d vau lt sh ield ed by over 50 feet of rock, th u s elim in atin g all cosm ic rays, th ere were absolu tely n o soft errors record ed ! Th is n ot on ly d em on strates h ow p roblem atic cosm ic rays can be, bu t it also p roves th at th e p ackagin g con tam in ation an d alp h a-p article p roblem h as in d eed been solved . Cosm ic ray-in d u ced errors are even m ore of a p roblem in SRAMs th an DRAMS. Th is is becau se th e am ou n t of ch arge req u ired to flip a bit in an SRAM cell is less th an is req u ired to flip a DRAM cell cap acitor. Cosm ic rays are also m ore of a p roblem for h igh erd en sity m em ory. As ch ip d en sity in creases, it becom es easier for a stray p article to flip a bit. It h as been p red icted by som e th at th e Soft Error Rate of a 64M DRAM will be d ou ble th at of a 16M ch ip , an d a 256M DRAM will h ave a rate fou r tim es h igh er. Un fortu n ately, th e PC in d u stry h as largely failed to recogn ize th is n ew cau se of m em ory errors. Th e ran d om an d in term itten t n atu re of a soft error can be m u ch m ore easily exp lain ed away by electrostatic d isch arge, p ower su rges, or u n stable software, esp ecially righ t after a n ew release of an op eratin g system or m ajor ap p lication .

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Stu d ies h ave sh own th at th e soft-error rate for ECC system s is on th e ord er of 30 tim es greater th an th e h ard -error rate. Th is is n ot su rp risin g to th ose fam iliar with th e fu ll effects of cosm ic ray-gen erated soft errors. Data n ow exists th at su ggests som e 16M DRAM ch ip d esign s will actu ally exp erien ce soft errors n u m berin g in th e 24,000 FIT (Failu res In Tim e - p er 1 billion h ou rs) ran ge. Th is wou ld resu lt in a soft error abou t on ce a m on th for m ost system s tod ay! How can we d eal with th ese errors? Ju st ign orin g th em is certain ly n ot th e best way to d eal with th em , bu t u n fortu n ately th at is wh at m an y system m an u factu rers an d ven d ors are d oin g tod ay. Th e best way to d eal with th is p roblem is to in crease th e system ’s fau lt toleran ce. Th is m ean s im p lem en tin g ways of d etectin g an d p ossibly correctin g errors in PC system s. Th ere are basically th ree levels an d tech n iq u es for fau lt toleran ce u sed in m od ern PCs: ■ Non -p arity ■ Parity ■ ECC (Error Correctin g Cod e) Non -p arity system s h ave n o fau lt toleran ce at all. Th e reason th ey are even u sed is becau se th ey h ave th e lowest in h eren t cost. No ad d ition al m em ory is n ecessary as is th e case with p arity or ECC tech n iq u es. Becau se a p arity-typ e d ata byte h as n in e bits versu s eigh t for n on -p arity, m em ory cost is 12.5 p ercen t h igh er. Also th e n on -p arity m em ory con troller is sim p lified becau se it d oes n ot n eed th e logic gates to calcu late p arity or ECC ch eck bits. Portable system s th at p lace a p rem iu m on m in im izin g p ower m igh t ben efit from th e red u ction in m em ory p ower d u e to fewer DRAM ch ip s. Fin ally, th e m em ory system d ata bu s is n arrower, wh ich red u ces th e am ou n t of d ata bu ffers. Th e statistical p robability of m em ory failu res in a m od ern office d esktop com p u ter is n ow estim ated at abou t on e error every few m on th s, m ore or less d ep en d in g on h ow m u ch m em ory you h ave. Th is error rate m ay be tolerable for low-en d system s th at are n ot u sed for m ission critical ap p lication s. In th is case, th eir extrem e m arket cost sen sitivity p robably can ’t ju stify th e extra cost of p arity or ECC m em ory, an d su ch errors will th en h ave to be tolerated . At an y rate, em p loyin g n o fau lt toleran ce in a system is sim p ly gam blin g th at m em ory errors are u n likely, an d if th ey d o occu r, resu lt in an in h eren t cost less th an th e ad d ition al h ard ware n ecessary for error d etection . However, th e d isad van tage is th at th e errors can lead to a seriou s p roblem su ch as calcu latin g th e wron g valu e to go in to a ban k ch eck, or in th e case of a system bein g u sed as a server, a m em ory error forcin g a system h an g an d brin gin g d own all LAN-resid en t clien t system s with su bseq u en t loss of p rod u ctivity. Fin ally, with a n on -p arity or n on -ECC m em ory system , p roblem traceability is d ifficu lt, wh ich is n ot th e case with p arity or ECC. Th ese tech n iq u es at least isolate to a m em ory sou rce as th e cu lp rit, th u s red u cin g both th e tim e an d cost of p roblem resolu tion s.

Physical M emory

Parit y Checking. On e stan d ard IBM set for th e in d u stry is th at th e m em ory ch ip s in a ban k of n in e each h an d le on e bit of d ata: eigh t bits p er ch aracter p lu s on e extra bit called th e parity bit. Th e p arity bit en ables m em ory-con trol circu itry to keep tabs on th e oth er eigh t bits—a bu ilt-in cross-ch eck for th e in tegrity of each byte in th e system . If th e circu itry d etects an error, th e com p u ter stop s an d d isp lays a m essage in form in g you of th e m alfu n ction . If you are ru n n in g a n ewer op eratin g system su ch as W in d ows or OS/ 2, a p arity error will gen erally m an ifest itself as a locked system . W h en you reboot, th e BIOS sh ou ld d etect th e error an d d isp lay th e ap p rop riate error m essage. SIMMs an d DIMMs are available both with an d with ou t p arity bits. Origin ally, all PC system s u sed p arity-ch ecked m em ory to en su re accu racy. Startin g in 1994, a d istu rbin g tren d d evelop ed in th e PC-com p atible m arketp lace. Most ven d ors began sh ip p in g system s with ou t p arity ch eckin g or an y oth er m ean s of d etectin g or correctin g errors! Th ese system s can u se ch eap er n on -p arity SIMMs, wh ich saves abou t 10–15 p ercen t on m em ory costs for a system . Parity m em ory resu lts in in creased in itial system cost d u e p rim arily to th e ad d ition al m em ory bits in volved . Parity can n ot correct system errors, bu t, becau se p arity can d etect errors, it can m ake th e u ser aware of m em ory errors wh en th ey occu r. Th is h as two basic ben efits: ■ Parity gu ard s again st th e con seq u en ces of fau lty calcu lation s based on in correct d ata. ■ Parity p in p oin ts th e sou rce of errors, wh ich assists in p roblem resolu tion , th u s im p rovin g system serviceability. PC system s can easily be d esign ed to fu n ction u sin g eith er p arity or n on -p arity m em ory. Th e cost of im p lem en tin g p arity as an op tion on a m oth erboard is virtu ally n oth in g; th e on ly cost in volved is in actu ally p u rch asin g th e p arity SIMMs or DIMMs, wh ich are abou t 10–15 p ercen t m ore exp en sive th an n on -p arity version s. Th is wou ld en able a system m an u factu rer to offer th eir system p u rch asers th e ch oice of p arity if th ey feel th e ad d ition al cost is ju stified for th eir p articu lar ap p lication . Un fortu n ately, several of th e big n am es began sellin g system s with ou t p arity to red u ce th e p rice of th eir system s, an d th ey d id n ot m ake it well-kn own th at th e lower cost was d u e to p arity m em ory n o lon ger bein g in clu d ed as stan d ard . Th is began h ap p en in g m ostly in 1994-1995, an d h as con tin u ed u n til very recen tly with few p eop le u n d erstan d in g th e fu ll im p lication s. After on e or two m ajor ven d ors d id th is, m ost of th e oth ers were forced to follow to rem ain p rice-com p etitive. Becau se n obod y wan ted to an n ou n ce th is in form ation , it rem ain ed as a sort of d irty little secret with in th e in d u stry. Origin ally, wh en th is h ap p en ed , you cou ld still sp ecify p arity m em ory wh en you ord ered a system , even th ou gh th e d efau lt con figu ration s n o lon ger in clu d ed it. Th ere wou ld be a 10–15 p ercen t su rch arge on th e m em ory, bu t th ose wh o wan ted reliable, tru stworth y system s cou ld at least get th em , p rovid ed th ey kn ew to ask, of cou rse. Th en a m ajor bom b h it th e in d u stry, in th e form of th e In tel Triton 430FX Pen tiu m ch ip set, wh ich was th e first m ajor ch ip set on th e m arket th at d id n ot su p p ort

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p arity ch eckin g at all! Th is also becam e th e m ost p op u lar ch ip set of its tim e, an d was fou n d in virtu ally all Pen tiu m m oth erboard s sold in th e 1995 tim efram e. Th is set a d istu rbin g tren d for th e n ext few years. All bu t on e of In tel’s Pen tiu m p rocessor ch ip sets after th e 430FX also d id n ot su p p ort p arity-ch ecked m em ory; th e on ly on e th at d id was th e 430HX Triton II. Th e good n ews is th at th is tren d n ow seem s to be over, an d th e system m an u factu rers an d u sers are fin ally com in g arou n d to th e im p ortan ce of fau lttoleran t m em ory. As su ch , all th e Pen tiu m Pro an d Pen tiu m II ch ip sets cu rren tly available d o su p p ort p arity an d ECC, an d m ore an d m ore p eop le are realizin g th at th is typ e of m em ory is worth wh ile. I d o exp ect n ew low-en d ch ip sets even for th e Pen tiu m II to em erge th at will n ot su p p ort p arity, bu t th ese are d esign ed for th e su b-$1,000 m arket, wh ere p rice an d n ot system in tegrity is th e m ost im p ortan t con cern . Let’s look at h ow p arity ch eckin g works, an d th en exam in e in m ore d etail th e su ccessor to p arity ch eckin g, called ECC (Error Correctin g Cod e), wh ich can n ot on ly d etect bu t correct m em ory errors on -th e-fly. IBM origin ally establish ed th e odd parity stan d ard for error ch eckin g. Th e followin g exp lan ation m ay h elp you u n d erstan d wh at is m ean t by od d p arity. As th e eigh t in d ivid u al bits in a byte are stored in m em ory, a p arity gen erator/ ch ecker, wh ich is eith er p art of th e CPU or located in a sp ecial ch ip on th e m oth erboard , evalu ates th e d ata bits by cou n tin g th e n u m ber of 1s in th e byte. If an even n u m ber of 1s is in th e byte, th e p arity gen erator/ ch ecker creates a 1 an d stores it as th e n in th bit (p arity bit) in th e p arity m em ory ch ip . Th at m akes th e total su m for all n in e bits an od d n u m ber. If th e origin al su m of th e eigh t d ata bits is an od d n u m ber, th e p arity bit created is 0, keep in g th e 9-bit su m an od d n u m ber. Th e valu e of th e p arity bit is always ch osen so th at th e su m of all n in e bits (eigh t d ata bits p lu s on e p arity bit) is an od d n u m ber. Rem em ber th at th e eigh t d ata bits in a byte are n u m bered 0 1 2 3 4 5 6 7. Th e followin g exam p les m ay m ake it easier to u n d erstan d : Data bit number: Data bit value:

0 1 2 3 4 5 6 7 1 0 1 1 0 0 1 1

Parity bit 0

In th is exam p le, becau se th e total n u m ber of d ata bits with a valu e of 1 is an od d n u m ber (5), th e p arity bit m u st h ave a valu e of 0 to en su re an od d su m for all n in e bits. Th e followin g is an oth er exam p le: Data bit number: Data bit value:

0 1 2 3 4 5 6 7 0 0 1 1 0 0 1 1

Parity bit 1

In th is exam p le, becau se th e total n u m ber of d ata bits with a valu e of 1 is an even n u m ber (4), th e p arity bit m u st h ave a valu e of 1 to create an od d su m for all n in e bits. W h en th e system read s m em ory back from storage, it ch ecks th e p arity in form ation . If a (9-bit) byte h as an even n u m ber of bits with a p arity bit valu e of 1, th at byte m u st h ave an error. Th e system can n ot tell wh ich bit h as ch an ged , or if on ly a sin gle bit h as ch an ged . If th ree bits ch an ged , for exam p le, th e byte still flags a p arity-ch eck error; if two bits ch an ged , h owever, th e bad byte m ay p ass u n n oticed . Th e followin g exam p les sh ow p arity-ch eck m essages for th ree typ es of system s:

Physical M emory

For the IBM PC: For the IBM XT: For the IBM AT and late model XT:

PARITY CHECK x PARITY CHECK x PARITY CHECK x

yyyyy (z) yyyyy

W h ere x is 1 or 2: 1 = Error occu rred on th e m oth erboard 2 = Error occu rred in an exp an sion slot yyyyy rep resen ts a n u m ber from 00000 th rou gh FFFFF th at in d icates, in h exad ecim al n otation , th e byte in wh ich th e error h as occu rred .

W h ere (z) is (S) or (E): (S) = Parity error occu rred in th e system u n it (E) = Parity error occu rred in th e exp an sion ch assis

Not e An expansion chassis was an option IBM sold for the original PC and XT systems to add more expansion slots. This unit consisted of a backplane motherboard with eight slots, one of which contained a special extender/ receiver card cabled to a similar extender/ receiver card placed in the main system. Due to the extender/ receiver cards in the main system and the expansion chassis, the net gain was six slots.

W h en a p arity-ch eck error is d etected , th e m oth erboard p arity-ch eckin g circu its gen erate a non-m askable interrupt (NMI), wh ich h alts p rocessin g an d d iverts th e system ’s atten tion to th e error. Th e NMI cau ses a rou tin e in th e ROM to be execu ted . Th e rou tin e clears th e screen an d th en d isp lays a m essage in th e u p p er-left corn er of th e screen . Th e m essage d iffers d ep en d in g on th e typ e of com p u ter system . On som e old er IBM system s, th e ROM p arity-ch eck rou tin e h alts th e CPU. In su ch a case, th e system locks u p , an d you m u st p erform a h ard ware reset or a p ower-off/ p ower-on cycle to restart th e system . Un fortu n ately, all u n saved work is lost in th e p rocess. Most system s d o n ot h alt th e CPU wh en a p arity error is d etected ; in stead , th ey offer you a ch oice of eith er rebootin g th e system or con tin u in g as th ou gh n oth in g h ap p en ed . Ad d ition ally, th ese system s m ay d isp lay th e p arity error m essage in a d ifferen t form at from IBM, alth ou gh th e in form ation p resen ted is basically th e sam e. For exam p le, m an y system s with a Ph oen ix BIOS d isp lay th ese m essages: Memory parity interrupt at xxxx:xxxx Type (S)hut off NMI, Type (R)eboot, other keys to continue

or I/O card parity interrupt at xxxx:xxxx Type (S)hut off NMI, Type (R)eboot, other keys to continue

Th e first of th ese two m essages in d icates a m oth erboard p arity error (Parity Ch eck 1), an d th e secon d in d icates an exp an sion -slot p arity error (Parity Ch eck 2). Notice th at th e ad d ress given in th e form xxxx:xxxx for th e m em ory error is in a segm en t:offset form rath er

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th an a straigh t lin ear ad d ress su ch as with IBM’s error m essages. Th e segm en t:offset ad d ress form still gives you th e location of th e error to a resolu tion of a sin gle byte. You h ave th ree ways to p roceed after viewin g th is error m essage. ■ You can p ress S, wh ich sh u ts off p arity ch eckin g an d resu m es system op eration at th e p oin t wh ere th e p arity ch eck first occu rred . ■ Pressin g R forces th e system to reboot, losin g an y u n saved work. ■ Pressin g an y oth er key cau ses th e system to resu m e op eration with p arity ch eckin g still en abled . If th e p roblem occu rs, it is likely to cau se an oth er p arity-ch eck in terru p tion . In m ost cases, it is m ost p ru d en t to p ress S, wh ich d isables th e p arity ch eckin g so th at you can th en save you r work. It wou ld be best in th is case to save you r work to a flop p y d isk to p reven t th e p ossible corru p tion of a h ard d isk. You sh ou ld also avoid overwritin g an y p reviou s (still good ) version s of wh atever file you are savin g, becau se in fact you m ay be savin g a bad file d u e to th e m em ory corru p tion . Becau se p arity ch eckin g is n ow d isabled , you r save op eration s will n ot be in terru p ted . Th en you sh ou ld p ower th e system off, restart it, an d ru n wh atever m em ory d iagn ostics software you h ave to try an d track d own th e error. In som e cases, th e POST fin d s th e error on th e n ext restart, bu t, in m ost cases, you n eed to ru n a m ore sop h isticated d iagn ostics p rogram , p erh ap s in a con tin u ou s m od e, to locate th e error. Th e AMI BIOS d isp lays th e p arity error m essages in th e followin g form s: ON BOARD PARITY ERROR ADDR (HEX) = (xxxxx)

or OFF BOARD PARITY ERROR ADDR (HEX) = (xxxxx)

Th ese m essages in d icate th at an error in m em ory h as occu rred d u rin g th e POST, an d th e failu re is located at th e ad d ress in d icated . Th e first on e in d icates th e error occu rred on th e m oth erboard , wh ereas th e secon d m essage in d icates an error in an exp an sion slot ad ap ter card . Th e AMI BIOS also can d isp lay m em ory errors in th e followin g m an n er: Memory Parity Error at xxxxx

or I/O Card Parity Error at xxxxx

Th ese m essages in d icate th at an error in m em ory h as occu rred at th e in d icated ad d ress d u rin g n orm al op eration . Th e first on e in d icates a m oth erboard m em ory error, an d th e secon d in d icates an exp an sion slot ad ap ter m em ory error. Alth ou gh m an y system s en able you to con tin u e p rocessin g after a p arity error, an d even allow for th e d isablin g of fu rth er p arity ch eckin g, con tin u in g to u se you r system after a p arity error is d etected can be d an gerou s. Th e id ea beh in d lettin g you con tin u e u sin g eith er m eth od is to give you tim e to save an y u n saved work before you d iagn ose an d service th e com p u ter, bu t be carefu l h ow you d o th is.

Physical M emory

Caut ion When you are notified of a memory parity error, remember the parity check is telling you that memory has been corrupted. Do you want to save potentially corrupted data over the good file from the last time you saved? Definitely not! M ake sure that you save your work to a different file name. In addition, after a parity error, save only to a floppy disk if possible and avoid writing to the hard disk; there is a slight chance that the hard drive could become corrupted if you save the contents of corrupted memory.

After savin g you r work, d eterm in e th e cau se of th e p arity error an d rep air th e system . You m ay be tem p ted to u se an op tion to sh u t off fu rth er p arity ch eckin g an d sim p ly con tin u e u sin g th e system as if n oth in g were wron g. Doin g so resem bles u n screwin g th e oil p ressu re warn in g in d icator bu lb on a car with an oil leak so th at th e oil p ressu re ligh t won ’t both er you an ym ore! ECC ( Error Correct ing Code) . ECC goes a big step beyon d sim p le p arity error d etection . Rath er th an ju st d etectin g an error, ECC allows a sin gle bit error to be corrected , wh ich m ean s th e system can con tin u e on with ou t in terru p tion an d with ou t corru p tin g d ata. ECC as im p lem en ted in m ost PCs can on ly d etect an d n ot correct d ou ble-bit errors. Becau se stu d ies h ave in d icated th at ap p roxim ately 98 p ercen t of m em ory errors are sin glebit variety, th e m ost com m on ly u sed typ e of ECC is on e in wh ich th e atten d an t m em ory con troller d etects an d corrects sin gle-bit errors in an accessed d ata word (d ou ble-bit errors can be d etected , bu t n ot corrected ). Th is typ e of ECC is kn own as SEC-DED an d req u ires an ad d ition al seven ch eck bits over 32 bits in a 4-byte system an d eigh t ch eck bits in an 8-byte system . ECC in a 4-byte system obviou sly costs m ore th an n on -p arity or p arity, bu t in an 8-byte system , ECC an d p arity costs are eq u al. ECC en tails th e m em ory con troller calcu latin g th e ch eck bits on a m em ory-write op eration , p erform in g a com p are between th e read an d calcu lated ch eck-bits on a read op eration an d , if n ecessary, correctin g bad bit(s). Th e ad d ition al ECC logic in th e m em ory con troller is n ot very sign ifican t in th is age of in exp en sive, h igh -p erform an ce VLSI logic, bu t ECC actu ally affects m em ory p erform an ce on writes. Th is is becau se th e op eration m u st be tim ed to wait for th e calcu lation of ch eck bits an d , wh en th e system waits for corrected d ata, read s. On a p artial-word write, th e en tire word m u st first be read , th e affected byte(s) rewritten , an d th en n ew ch eck bits calcu lated . Th is tu rn s p artial-word write op eration s in to slower read -m od ify writes. Most m em ory errors are of a sin gle-bit n atu re, wh ich are correctable by ECC. In corp oratin g th is fau lt-toleran t tech n iq u e p rovid es h igh system reliability an d atten d an t availability. An ECC-based system is a good ch oice for servers, workstation s, or m ission -critical ap p lication s in wh ich th e cost of a p oten tial m em ory error ou tweigh s th e ad d ition al m em ory an d system cost to correct it, alon g with en su rin g th at it d oes n ot d etract from system reliability. W h at I’m sayin g is th at if you valu e you r d ata an d u se you r system for im p ortan t (to you ) tasks, th en you ’ll wan t ECC m em ory.

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By d esign in g a system th at allows th e u ser to m ake th e ch oice of ECC, p arity, or n on p arity, th e u ser can ch oose th e level of fau lt toleran ce d esired , as well as h ow m u ch th ey wan t to gam ble with th eir d ata.

Inst alling M em ory Upgrades Ad d in g m em ory to a system is on e of th e m ost u sefu l u p grad es th at you can p erform , an d also on e of th e least exp en sive, esp ecially wh en you con sid er th e in creased cap abilities of W in d ows 95/ 98, W in d ows NT, an d OS/ 2 wh en you give th em access to m ore m em ory. In som e cases, d ou blin g th e m em ory can virtu ally d ou ble th e sp eed of a com p u ter. Th is section d iscu sses ad d in g m em ory, in clu d in g selectin g m em ory ch ip s, in stallin g m em ory ch ip s, an d testin g th e in stallation . Upgrade Opt ions and St rat egies Ad d in g m em ory can be an in exp en sive solu tion ; at th is writin g, th e cost of m em ory h as fallen to abou t $1.50 p er m egabyte. A sm all d ose can give you r com p u ter’s p erform an ce a big boost. How d o you ad d m em ory to you r PC? You h ave th ree op tion s, listed in ord er of con ven ien ce an d cost: ■ Ad d in g m em ory in vacan t slots on you r m oth erboard . ■ Rep lacin g you r cu rren t m oth erboard ’s m em ory with h igh er-cap acity m em ory. ■ Pu rch asin g a m em ory exp an sion card (n ot a cost-effective or p erform an ce-effective solu tion for an y system cu rren tly on th e m arket). Ad d in g exp an d ed m em ory to PC- or XT-typ e system s is n ot a good id ea, m ain ly becau se an exp an d ed m em ory board with a cou p le of m egabytes of exp an d ed m em ory in stalled can cost m ore th an th e en tire system is worth . Also, th is m em ory d oes n ot fu n ction for W in d ows, an d a PC- or XT-class system can n ot ru n OS/ 2. In stead , p u rch ase a m ore p owerfu l system —for exam p le, an in exp en sive Pen tiu m II 266—with greater exp an sion cap abilities. If you d ecid e to u p grad e to a m ore p owerfu l com p u ter system , you n orm ally can n ot salvage th e m em ory from a PC or XT system . Th e 8-bit m em ory board s are u seless in 16bit system s, an d th e sp eed of th e m em ory ch ip s u su ally is in ad eq u ate for n ewer system s. All n ew system s u se h igh -sp eed SIMM or DIMM m od u les rath er th an ch ip s. A p ile of 150n s (n an osecon d s), 64K, or 256K ch ip s is u seless if you r n ext system is a h igh -sp eed system th at u ses SIMMs or m em ory d evices faster th an 70n s. Be su re to weigh carefu lly you r fu tu re n eed s for com p u tin g sp eed an d for a m u ltitaskin g op eratin g system (OS/ 2, W in d ows 95/ 98, W in d ows NT, or Lin u x, for exam p le) with th e am ou n t of m on ey th at you sp en d to u p grad e cu rren t eq u ip m en t. Before you ad d RAM to a system (or rep lace d efective RAM ch ip s), you m u st d eterm in e th e m em ory ch ip s req u ired for you r system . You r system d ocu m en tation con tain s th is in form ation .

Installing M emory Upgrades

If you n eed to rep lace a d efective SIMM or DIMM an d d o n ot h ave th e system d ocu m en tation , you can d eterm in e th e correct m od u le for you r system by in sp ectin g th e on es th at are alread y in stalled . Each m od u le h as m arkin gs th at in d icate th e m od u le’s cap acity an d sp eed . RAM cap acity an d sp eed are both d iscu ssed in d etail earlier in th is ch ap ter. If you d o n ot h ave th e d ocu m en tation for you r system an d th e m an u factu rer d oes n ot offer tech n ical su p p ort, op en you r system case an d carefu lly write d own th e m arkin gs th at ap p ear on you r m em ory ch ip s. Th en , con tact a local com p u ter store or m od u le ven d or su ch as Kin gston , Micron (Cru cial), PNY, or oth ers for h elp in d eterm in in g th e p rop er RAM ch ip s for you r system . Ad d in g th e wron g m od u les to a system can m ake it as u n reliable as leavin g a d efective m od u le in stalled an d tryin g to u se th e system in th at con d ition .

Not e Before upgrading a system beyond 64M of RAM , be sure that your chipset supports caching of more than 64M . Adding RAM beyond the amount that your system can cache will slow performance rather than increase it. See the section “ Cache M emory—SRAM ” earlier in this chapter and the discussion of chipsets in Chapter 4 for a more complete explanation of this common system limitation.

Select ing and Inst alling M ot herboard M em ory w it h Chips, SIM M s, or DIM M s If you are u p grad in g a m oth erboard by ad d in g m em ory, follow th e m an u factu rer’s gu id elin es on wh ich m em ory ch ip s or m od u les to p u rch ase. As you learn ed earlier, m em ory com es in variou s form factors, in clu d in g in d ivid u al ch ip s kn own as DIP m em ory ch ip s, SIMMs (sin gle in lin e m em ory m od u les), an d DIMMs. You r com p u ter m ay u se on e or p ossibly a m ixtu re of th ese form factors. No m atter wh at typ e of m em ory ch ip s you h ave, th e ch ip s are in stalled in m em ory ban ks. A m em ory bank is a collection of m em ory ch ip s th at m ake u p a block of m em ory. Each ban k of m em ory is read by you r p rocessor in on e p ass. A m em ory ban k d oes n ot work u n less it is filled with m em ory ch ip s. (Ban ks are d iscu ssed in m ore d etail earlier in th is ch ap ter in th e section “Mem ory Ban ks.”) Pen tiu m , Pen tiu m Pro, an d Pen tiu m II com p u ters also n orm ally h ave between two an d fou r ban ks of m em ory, bu t each ban k u su ally req u ires two 72-p in (32- or 36-bit) SIMMs or on e 168-p in DIMM. In stallin g extra m em ory on you r m oth erboard is an easy way to ad d m em ory to you r com p u ter. Most system s h ave at least on e vacan t m em ory ban k in wh ich you can in stall extra m em ory at a later tim e an d sp eed you r com p u ter. Replacing SIM M S and DIM M s w it h Higher Capacit y If all th e SIMM or DIMM slots on you r m oth erboard are occu p ied , you r best op tion is to rem ove an existin g ban k of m em ory an d rep lace it with h igh er m em ory. For exam p le, if you h ave a 16M of RAM in a Pen tiu m system with fou r SIMM slots filled with 4M 72-p in SIMMs, you m ay be able to rep lace all fou r SIMMs with 8M SIMMs an d in crease th e system m em ory to 32M. Altern ately, you cou ld keep two of th e existin g 4M SIMMs an d

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rep lace two with 8M SIMMs, in creasin g th e total RAM to 24M. Rem em ber th at ju st as wh en you in stall SIMMs, th ey n eed to be rep laced in a fu ll ban k an d all th e SIMMs in th e ban k n eed to be th e sam e cap acity. Th e m u ltip le m od u le req u irem en t is n ot an issu e with DIMMs as in all cu rren t system s; a DIMM con stitu tes at least on e fu ll ban k of m em ory. However, ju st becau se th ere are h igh er-cap acity SIMMs or DIMMs available th at are th e correct p in cou n t to p lu g in to you r m oth erboard , d on ’t au tom atically assu m e th e h igh ercap acity m em ory will work. Th e ch ip set an d BIOS of you r system will set lim its on th e cap acity of th e m em ory you can u se. Ch eck you r system or m oth erboard d ocu m en tation to see wh at size SIMMs or DIMMs will work with it before p u rch asin g th e n ew RAM. Adding Adapt er Boards Mem ory exp an sion board s typ ically are a last-resort way to ad d m em ory. For m an y system s (su ch as old er m od els from Com p aq ) with p rop rietary local bu s m em ory-exp an sion con n ectors, you m u st p u rch ase all m em ory-exp an sion board s from th at com p an y. Sim ilarly, IBM u sed p rop rietary m em ory con n ectors in m an y of th e PS/ 2 system s. For oth er in d u stry-stan d ard system s th at u se n on p rop rietary m em ory exp an sion , you can p u rch ase from h u n d red s of ven d ors m em ory-exp an sion board s th at p lu g in to th e stan d ard bu s slots. Un fortu n ately, an y m em ory exp an sion th at p lu gs in to a stan d ard bu s slot ru n s at bu s sp eed rath er th an at fu ll-system sp eed . For th is reason , m ost system s tod ay p rovid e stan d ard SIMM or DIMM con n ector sockets d irectly on th e m oth erboard so th at th e m em ory can be p lu gged d irectly in to th e system ’s local bu s. Usin g m em ory ad ap ter card s in th ese system s on ly slows th em d own . Oth er system s u se p rop rietary local bu s con n ectors for m em ory-exp an sion ad ap ters, wh ich can cau se ad d ition al p roblem s an d exp en se wh en you h ave to ad d or service m em ory. Up grad in g a system by u sin g a m em ory ad ap ter card is n o lon ger cost-effective, eith er. Becau se m ost system s an d m oth erboard s bu ilt on 486 or later p rocessors can be u p grad ed with SIMMs or DIMMs, th e on ly system s th at wou ld be u p grad ed with an ad ap ter card are so old , it wou ld be less exp en sive to rep lace th e en tire m oth erboard th an to u p grad e th ese old system s. Inst alling M em ory Th is section d iscu sses in stallin g m em ory —sp ecifically, n ew SIMM or DIMM m od u les. Th e section also covers th e p roblem s th at you are m ost likely to en cou n ter an d h ow to avoid th em . You will also get in form ation on con figu rin g you r system to u se n ew m em ory. W h en you in stall or rem ove m em ory, you are m ost likely to en cou n ter th e followin g p roblem s: ■ Electrostatic d isch arge ■ Broken or ben t p in s ■ In correctly seated SIMMs an d DIMMs ■ In correct switch an d ju m p er settin gs

Installing M emory Upgrades

To p reven t electrostatic d isch arge (ESD) wh en you in stall sen sitive m em ory ch ip s or board s, d o n ot wear syn th etic-fiber cloth in g or leath er-soled sh oes. Rem ove an y static ch arge th at you are carryin g by tou ch in g th e system ch assis before you begin , or better yet, wear a good com m ercial grou n d in g strap on you r wrist. You can ord er on e from an electron ics p arts store or m ail-ord er h ou se. A grou n d in g strap con sists of a con d u ctive wristban d grou n d ed at th e oth er en d by a wire clip p ed to th e system ch assis. Leave th e system u n it p lu gged in —bu t tu rn ed off—to keep it grou n d ed .

Caut ion Be sure to use a properly designed commercial grounding strap; do not make one yourself . Commercial units have a one-megohm resistor that serves as protection if you accidentally touch live power. The resistor ensures that you do not become the path of least resistance to the ground and therefore become electrocuted. An improperly designed strap can cause the power to conduct through you to the ground, possibly killing you.

Broken or ben t lead s are an oth er p oten tial p roblem associated with in stallin g in d ivid u al m em ory ch ip s (DIPs) or SIPP m od u les. Fortu n ately, th is is n ot a p roblem you will en cou n ter in stallin g a SIMM or DIMM. Som etim es, th e p in s on n ew ch ip s are ben t in to a V, m akin g th em d ifficu lt to align with th e socket h oles. If you n otice th is p roblem on a DIP ch ip , p lace th e ch ip on its sid e on a table, an d p ress gen tly to ben d th e p in s so th at th ey are at a 90-d egree an gle to th e ch ip . For a SIPP m od u le, you m ay wan t to u se n eed le-n ose p liers to carefu lly straigh ten th e p in s so th at th ey p rotru d e d irectly d own from th e ed ge of th e m od u le, with eq u al am ou n ts of sp ace between p in s. Th en , you sh ou ld in stall th e ch ip s in th e sockets on e at a tim e.

Caut ion Straightening the pins on a DIP chip or SIPP module is not difficult work, but if you are not careful, you could easily break off one of the pins, rendering the chip or memory module useless. Use great care when you straighten the bent pins on any memory chip or module. You can use chipinsertion and pin-straightening devices to ensure that the pins are straight and aligned with the socket holes; these inexpensive tools can save you a great deal of time.

Each m em ory ch ip or m od u le m u st be in stalled to p oin t in a certain d irection . Each d evice h as a p olarity m arkin g on on e en d . Th is is n orm ally a n otch on SIMMs or DIMMs, an d m ay be a n otch , circu lar in d en tation , or m ark on an y in d ivid u al ch ip . Th e ch ip socket m ay h ave a corresp on d in g n otch . Oth erwise, th e m oth erboard m ay h ave a p rin ted legen d th at in d icates th e orien tation of th e ch ip . If th e socket is n ot m arked , you sh ou ld u se oth er ch ip s as a gu id e. Th e orien tation of th e n otch in d icates th e location of Pin 1 on th e d evice. Align in g th is n otch correctly with th e oth ers on th e board en su res th at you d o n ot in stall th e ch ip backward . Gen tly set each ch ip in to a socket, en su rin g th at every p in is p rop erly align ed with th e con n ector in to wh ich it fits. Th en p u sh th e ch ip in firm ly with both th u m bs u n til th e ch ip is fu lly seated .

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SIMM m em ory is orien ted by a n otch on on e sid e of th e m od u le th at is n ot p resen t on th e oth er sid e, as sh own in Figu re 5.9. Th e socket h as a p rotru sion th at m u st fit in to th is n otch ed area on on e sid e of th e m od u le. Th is p rotru sion m akes it im p ossible to in stall a SIMM backward u n less you break th e con n ector. Figu re 5.10 sh ows a d etailed blowu p of th e backsid e of th e SIMM, sh owin g th e n otch an d th e lockin g clip . Figu re 5.11 sh ows a closeu p of a DIMM (n ote th at it, too, is keyed to en su re p rop er exp an sion socket in stallation ). Insert down first...

...then tilt forward

FIG. 5.10 Th e n otch on th is SIMM is sh own on th e left en d . In sert th e SIMM at an an gle an d th en tilt it forward u n til th e lockin g clip s sn ap in to p lace.

Sim ilarly, DIMMs are keyed by n otch es alon g th e bottom con n ector ed ge th at are offset from cen ter so th at th ey can be in serted in on ly on e d irection , as sh own in Figu re 5.12. SIPP m od u les, h owever, d o n ot p lu g in to a keyed socket; you h ave to orien t th em p rop erly. Th e system d ocu m en tation can be h elp fu l if th e m oth erboard h as n o m arks to gu id e you . You also can u se existin g SIPP m od u les as a gu id e. Th e DIMM ejector tab locks in to p lace in th e n otch on th e sid e of th e DIMM wh en it is fu lly in serted . Som e DIMM sockets h ave ejector tabs on both en d s. W h en in stallin g SIMMs an d DIMMs, take care n ot to force th e m od u le in to th e socket. If th e m od u le d oes n ot slip easily in to th e slot an d th en sn ap in to p lace, th ere is a good ch an ce th e m od u le is n ot orien ted or align ed correctly. Forcin g th e m od u le cou ld break th e m od u le or th e socket. If th e retain in g clip s on th e socket break, th e m em ory will n ot be h eld firm ly in p lace an d th ere is a good ch an ce you will exp erien ce ran d om m em ory errors becau se th e m od u le will n ot m ake con sisten t electrical con tact if it is loose.

Installing M emory Upgrades

Hole in SIMM Locking Clip

Tab in socket fits hole in SIMM

Notch in SIMM SIMM Socket is molded to fit notch

FIG. 5.11 Th is closeu p sh ows th e backsid e of a SIMM in serted in th e SIMM socket with th e n otch align ed , th e lockin g clip locked , an d th e h ole in th e SIMM align ed with th e tab th at sticks ou t from th e socket.

M DIM c Eje

tor

Mo

dul

e

Tab

Ke

yed

FIG. 5.12 DIMMs keys m atch th e p rotru sion s in th e DIMM sockets.

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As exp lain ed earlier in th is ch ap ter, DIMMs can com e in several d ifferen t varieties, in clu d in g u n bu ffered or bu ffered an d 3.3v or 5v. Bu ffered DIMMs h ave ad d ition al bu ffer ch ip s on th em to in terface to th e m oth erboard . Un fortu n ately, th ese bu ffer ch ip s slow th e DIMM d own an d are n ot effective at h igh er sp eed s. For th is reason , all PC system s u se u n bu ffered DIMMs. Th e voltage is sim p le—DIMM d esign s for PCs are alm ost u n iversally 3.3v. If you in stall a 5v DIMM in a 3.3v socket, it wou ld be d am aged , bu t fortu n ately keyin g in th e socket an d on th e DIMM will p reven t th at. Mod ern PC system s on ly u se u n bu ffered 3.3v DIMMs. Ap p le an d oth er n on -PC system s m ay u se th e bu ffered 5v version s. Fortu n ately, th e key n otch es alon g th e con n ector ed ge of a DIMM are sp aced d ifferen tly for RFU an d bu ffered DIMMs an d 5.0v DIMMs, as sh own in Figu re 5.13. Th is p reven ts in sertin g a DIMM of th e wron g typ e in to a socket.

DRAM Key Position Reserved Unbuffered Buffered

Voltage Key Position 5.0V

Reserved 3.3V

FIG. 5.13 168-p in DRAM DIMM n otch key d efin ition s. Before in stallin g m em ory, m ake su re th at th e system p ower is off. Th en rem ove th e PC cover an d an y in stalled card s. SIMMs an d DIMMs sn ap easily in to p lace, bu t ch ip s can be m ore d ifficu lt to in stall. A ch ip -in stallation tool is n ot req u ired , bu t it can m ake in sertin g th e ch ip s in to sockets m u ch easier. To rem ove ch ip s, u se a ch ip extractor or sm all screwd river. Never try rem ovin g a RAM ch ip with you r fin gers, becau se you can ben d th e ch ip ’s p in s or p oke a h ole in you r fin ger with on e of th e p in s. You rem ove SIMMs an d DIMMs by releasin g th e lockin g tabs an d eith er p u llin g or rollin g th em ou t of th eir sockets. After ad d in g th e m em ory an d p u ttin g th e system back togeth er, you m ay h ave to ru n th e CMOS setu p an d resave with th e n ew am ou n t of m em ory. Most n ewer system s au tom atically d etect th e n ew am ou n t of m em ory an d recon figu re th is for you . Most n ewer system s also d on ’t req u ire settin g an y ju m p ers or switch es on th e m oth erboard to con figu re th em for you r n ew m em ory. Old er m oth erboard s th at u sed in d ivid u al RAM ch ip s rath er th an SIMMs or DIMMs for m em ory are m ore likely to n eed ch an ges to ju m p er an d switch settin gs. If you in stall in d ivid u al RAM ch ip s on a m oth erboard an d th e CMOS d oes n ot recogn ize th e n ew RAM, ch eck th e system d ocu m en tation to see if ch an ges to m oth erboard ju m p ers or switch es are req u ired .

Not e Information on installing memory on older memory-expansion cards can be found in Chapter 7 of the sixth Edition of Upgrading and Repairing PCs on the CD-ROM accompanying this book.

The System Logical M emory Layout

After con figu rin g you r system to work p rop erly with th e ad d ition al m em ory, you sh ou ld ru n a m em ory-d iagn ostics p rogram to en su re th e p rop er op eration of th e n ew m em ory. At least two an d som etim es th ree m em ory-d iagn ostic p rogram s are available for all system s. In ord er of accu racy, th ese p rogram s are: ■ POST (Power-On Self Test) ■ Disk-based ad van ced d iagn ostics software Th e POST is u sed every tim e you p ower u p th e system . Man y ad d ition al d iagn ostics p rogram s are available from afterm arket u tility software com p an ies. More in form ation on afterm arket testin g facilities can be fou n d in Ch ap ter 17, “Diagn ostics, Testin g, an d Main ten an ce.”

The Syst em Logical M em ory Layout Th e origin al PC h ad a total of 1M of ad d ressable m em ory, an d th e top 384K of th at was reserved for u se by th e system . Placin g th is reserved sp ace at th e top (between 640K an d 1024K in stead of at th e bottom , between 0K an d 640K) led to wh at tod ay is often called th e conventional m em ory barrier. Th e con stan t p ressu res on system an d p erip h eral m an u factu rers to m ain tain com p atibility by n ever breakin g from th e origin al m em ory sch em e of th e first PC h as resu lted in a system m em ory stru ctu re th at is (to p u t it kin d ly) a m ess. Alm ost two d ecad es after th e first PC was in trod u ced , even th e n ewest Pen tiu m II-based system s are lim ited in m an y im p ortan t ways by th e m em ory m ap of th e first PCs. Som eon e wh o wan ts to becom e kn owled geable abou t p erson al com p u ters m u st at on e tim e or an oth er com e to term s with th e typ es of m em ory in stalled on h is system —th e sm all an d large p ieces of d ifferen t kin d s of m em ory, som e accessible by software ap p lication p rogram s, an d som e n ot. Th e followin g section s d etail th e d ifferen t kin d s of m em ory in stalled on a m od ern PC. Th e kin d s of m em ory covered in th e followin g section s in clu d e th e followin g: ■ Con ven tion al (Base) m em ory ■ Up p er Mem ory Area (UMA) ■ High Mem ory Area (HMA) ■ Exten d ed m em ory (XMS) ■ Exp an d ed m em ory (obsolete) ■ Vid eo RAM m em ory (p art of UMA) ■ Ad ap ter ROM an d Sp ecial Pu rp ose RAM (p art of UMA) ■ Moth erboard ROM BIOS (p art of UMA) Su bseq u en t section s also cover p reven tin g m em ory con flicts an d overlap , u sin g m em ory m an agers to op tim ize you r system ’s m em ory, an d m akin g better u se of m em ory. In a 16-bit or h igh er system , th e m em ory m ap exten d s beyon d th e 1M bou n d ary an d can

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con tin u e to 16M on a system based on th e 286 or h igh er p rocessor, 4G (4,096M) on a 386DX or h igh er, or as m u ch as 64G (65,536M) on a Pen tiu m II. An y m em ory p ast 1M is called extended m em ory. Figu re 5.14 sh ows th e logical ad d ress location s for a 16-bit or h igh er system . If th e p rocessor is ru n n in g in real m od e, on ly th e first m egabyte is accessible. If th e p rocessor is in p rotected m od e, th e fu ll 16M, 4,096M, or 65,536M are accessible. Each sym bol is eq u al to 1K of m em ory, an d each lin e or segm en t is 64K. Th is m ap sh ows th e first two m egabytes of system m em ory. √√ See “ Processor M odes,” p. 43

Not e To save space, this map is ended after the end of the second megabyte. In reality, this map continues to the maximum of addressable memory.

Convent ional ( Base) M em ory Th e origin al PC/ XT-typ e system was d esign ed to u se 1M of m em ory worksp ace, som etim es called RAM (random access m em ory). Th is 1M of RAM is d ivid ed in to several section s, som e of wh ich h ave sp ecial u ses. DOS can read an d write to th e en tire m egabyte, bu t can m an age th e load in g of p rogram s on ly in th e p ortion of RAM sp ace called conventional m em ory, wh ich was 512K at th e tim e th e first PC was in trod u ced . Th e oth er 512K was reserved for u se by th e system , in clu d in g th e m oth erboard an d ad ap ter board s p lu gged in to th e system slots. After in trod u cin g th e system , IBM d ecid ed th at on ly 384K was n eed ed for th ese reserved u ses, an d th e com p an y began m arketin g PCs with 640K of u ser m em ory. Th u s, 640K becam e th e stan d ard for m em ory th at can be u sed by DOS for ru n n in g p rogram s, an d is often term ed th e 640K m em ory barrier. Th e rem ain in g m em ory after 640K was reserved for u se by th e grap h ics board s, oth er ad ap ters, an d th e m oth erboard ROM BIOS. Th is barrier largely affects 16-bit software su ch as DOS an d W in d ows 3.1, an d is m u ch less of a factor with 32-bit software an d op eratin g system s su ch as W in d ows 95/ 98, NT, an d so on . Upper M em ory Area ( UM A) Th e term Upper Mem ory Area (UMA) d escribes th e reserved 384K at th e top of th e first m egabyte of system m em ory on a PC/ XT an d th e first m egabyte on an AT-typ e system . Th is m em ory h as th e ad d resses from A0000 th rou gh FFFFF. Th e way th e 384K of u p p er m em ory is u sed breaks d own as follows: ■ Th e first 128K after con ven tion al m em ory is called video RAM. It is reserved for u se by vid eo ad ap ters. W h en text an d grap h ics are d isp layed on screen , th e electron ic im p u lses th at con tain th eir im ages resid e in th is sp ace. Vid eo RAM is allotted th e ad d ress ran ge from A0000-BFFFF.

The System Logical M emory Layout

. G M C V a r R b h

= = = = = = = = = =

Program-accessible memory (standard RAM) Graphics Mode Video RAM Monochrome Text Mode Video RAM Color Text Mode Video RAM Video ROM BIOS (would be “a” in PS/2) Adapter board ROM and special-purpose RAM (free UMA space) Additional PS/2 Motherboard ROM BIOS (free UMA in non-PS/2 systems) Motherboard ROM BIOS IBM Cassette BASIC ROM (would be “R” in IBM compatibles) High Memory Area (HMA), if HIMEM.SYS is loaded.

Conventional (Base) Memory: : 000000: 010000: 020000: 030000: 040000: 050000: 060000: 070000: 080000: 090000:

0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................

Upper Memory Area (UMA): : 0A0000: 0B0000: : 0C0000: 0D0000: : 0E0000: 0F0000:

0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr RRRRRRRRRRRRRRRRRRRRRRRRbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbRRRRRRRR

Extended Memory: : 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--100000: hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh Extended Memory Specification (XMS) Memory: 110000: 120000: 130000: 140000: 150000: 160000: 170000: 180000: 190000: 1A0000: 1B0000: 1C0000: 1D0000: 1E0000: 1F0000:

................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................ ................................................................

FIG. 5.14 Th e logical m em ory m ap of th e first 2M.

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■ Th e n ext 128K is reserved for th e ad ap ter BIOS th at resid es in read -on ly m em ory ch ip s on som e ad ap ter board s p lu gged in to th e bu s slots. Most VGA-com p atible vid eo ad ap ters u se th e first 32K of th is area for th eir on board BIOS. Th e rest can be u sed by an y oth er ad ap ters in stalled . Man y n etwork ad ap ters also u se th is area for sp ecial-p u rp ose RAM called Sh ared Mem ory. Ad ap ter ROM an d sp ecial-p u rp ose RAM is allotted th e ad d ress ran ge from C0000-DFFFF. ■ Th e last 128K of m em ory is reserved for m oth erboard BIOS (th e basic in p u t/ ou tp u t system , wh ich is stored in read -on ly RAM ch ip s or ROM). Th e POST (Power-On Self Test) an d bootstrap load er, wh ich h an d les you r system at bootu p u n til th e op eratin g system takes over, also resid e in th is sp ace. Most system s on ly u se th e last 64K (or less) of th is sp ace, leavin g th e first 64K or m ore free for rem ap p in g with m em ory m an agers. Som e system s also in clu d e th e CMOS Setu p p rogram in th is area. Th e m oth erboard BIOS is allotted th e ad d ress ran ge from E0000-FFFFF. Not all th e 384K of reserved m em ory is fu lly u sed on m ost 16-bit an d h igh er system s. For exam p le, accord in g to th e PC stan d ard , reserved vid eo RAM begin s at ad d ress A0000, wh ich is righ t at th e 640K bou n d ary. Norm ally, th is is u sed for VGA grap h ics m od es, wh ile th e m on och rom e an d color text m od es u se B0000-B7FFF an d B8000-BFFFF, resp ectively. Old er n on -VGA ad ap ters on ly u sed m em ory in th e B0000 segm en t. Differen t vid eo ad ap ters u se varyin g am ou n ts of RAM for th eir op eration s, d ep en d in g m ain ly on th e m od e th ey are in . To th e p rocessor, h owever, it always ap p ears as th e sam e 128K area n o m atter h ow m u ch RAM is really on th e vid eo card . Th is is m an aged by ban k switch in g areas of m em ory on th e card in an d ou t of th e A0000-BFFFF segm en ts. Alth ou gh th e top 384K of th e first m egabyte was origin ally term ed reserved m em ory, it is p ossible to u se p reviou sly u n u sed region s of th is m em ory to load 16-bit d evice d rivers (su ch as ANSI.SYS) an d m em ory-resid en t p rogram s (su ch as MOUSE.COM), wh ich frees u p th e con ven tion al m em ory th ey wou ld oth erwise req u ire. Note th at 32-bit d evice d rivers su ch as th ose u sed with W in d ows 95/ 98, NT, an d so forth are n ot affected by th is as th ey load in to exten d ed m em ory. Th e am ou n t of free UMA sp ace varies from system to system , d ep en d in g on th e ad ap ter card s in stalled on th e system . For exam p le, m ost SCSI ad ap ters an d n etwork ad ap ters req u ire som e of th is area for bu ilt-in ROMs or sp ecialp u rp ose RAM u se. Segm ent Addresses and Linear Addresses. On e th in g th at can be con fu sin g is th e d ifferen ce between a segm en t ad d ress an d a fu ll lin ear ad d ress. Th e u se of segm en ted ad d ress n u m bers com es from th e in tern al stru ctu re of th e In tel p rocessors, an d is u sed p rim arily by old er, 16-bit op eratin g system s. Th ey u se a sep arate register for th e segm en t in form ation an d an oth er for th e offset. Th e con cep t is very sim p le. For exam p le, assu m e th at I am stayin g in a h otel room , an d som ebod y asks for m y room n u m ber. Th e h otel h as 10 floors, n u m bered from zero th rou gh n in e; each floor h as 100 room s, n u m bered from 00 to 99. A segm en t is d efin ed as an y grou p of 100 room s startin g at a m u ltip le of 10, an d in d icated by a two-d igit n u m ber. So, a segm en t ad d ress of 54 wou ld in d icate th e actu al room 540, an d you cou ld h ave an offset of 00 to 99 room s from th ere.

The System Logical M emory Layout

Th u s in th is h otel exam p le, each segm en t is sp ecified as a two-d igit n u m ber from 00 to 99, an d an offset can be sp ecified from an y segm en t startin g with a n u m ber from 00 to 99 as well. As an exam p le, let’s say I am stayin g in room 541. If th e p erson n eed s th is in form ation in segm en t:offset form , an d each n u m ber is two d igits, I cou ld say th at I am stayin g at a room segm en t startin g ad d ress of 54 (room 540), an d an offset of 01 from th e start of th at segm en t. I cou ld also say th at I am in room segm en t 50 (room 500), an d an offset of 41. You cou ld even com e u p with oth er an swers, su ch as I am at segm en t 45 (room 450) offset 91 (450+91=541). Here is an exam p le of h ow th is ad d s u p : Segm ent

Offset

Tot al

54

01

541

50

41

541

45

91

541

As you can see, alth ou gh th e p articu lar segm en t an d offset are d ifferen t, th ey all ad d u p to th e sam e room ad d ress. In th e In tel x86 p rocessors, a sim ilar sch em e is u sed wh ere a segm en t an d offset are ad d ed in tern ally to p rod u ce th e actu al ad d ress. It can be som ewh at con fu sin g, esp ecially if you are writin g assem bly lan gu age or m ach in e lan gu age software! Th is is exactly h ow segm en ted m em ory in an In tel p rocessor works. Notice th at th e segm en t an d offset n u m bers essen tially overlap on all d igits excep t th e first an d last. By ad d in g th em togeth er with th e p rop er align m en t, you can see th e lin ear ad d ress total. W ith 32-bit op eratin g system s, segm en t ad d resses are n ot an issu e. A lin ear ad d ress is on e with ou t segm en t:offset bou n d aries, su ch as sayin g room 541. It is a sin gle n u m ber an d n ot com p rised of two n u m bers ad d ed togeth er. For exam p le, a SCSI h ost ad ap ter m igh t h ave 16K ROM on th e card ad d ressed from D4000 to D7FFF. Th ese n u m bers exp ressed in segm en t:offset form are D400:0000 to D700:0FFF. Th e segm en t p ortion is com p osed of th e m ost sign ifican t fou r d igits, an d th e offset p ortion is com p osed of th e least sign ifican t fou r d igits. Becau se each p ortion overlap s by on e d igit, th e en d in g ad d ress of its ROM can be exp ressed in fou r d ifferen t ways, as follows: D000:7FFF =

D000 7FFF ----= D7FFF

segment offset

D700 + 0FFF ----= D7FFF

segment offset

+

D700:0FFF =

D7F0:00FF =

total

total

D7F0 00FF ----= D7FFF

segment offset

D7FF + 000F ----= D7FFF

segment offset

+

D7FF:000F =

total

total

As you can see in each case, alth ou gh th e segm en t an d offset d iffer sligh tly, th e total en d s u p bein g th e sam e. Ad d in g togeth er th e segm en t an d offset n u m bers m akes p ossible even m ore com bin ation s, as in th e followin g exam p les:

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D500:2FFF =

D500 2FFF ----= D7FFF

segment offset

D6EE 111F ----= D7FFF

segment offset

+

D6EE:111F =

+

total

total

As you can see, several com bin ation s are p ossible. Th e correct an d gen erally accep ted way to write th is ad d ress as a lin ear ad d ress is D7FFF, wh ereas m ost wou ld write th e segm en t:offset ad d ress as D000:7FFF. Keep in g th e segm en t m ostly zeros m akes th e segm en t:offset relation sh ip easier to u n d erstan d an d th e n u m ber easier to com p reh en d . If you u n d erstan d th e segm en t:offset relation sh ip to th e lin ear ad d ress, you n ow kn ow wh y wh en a lin ear ad d ress n u m ber is d iscu ssed it is five d igits, wh ereas a segm en t n u m ber is on ly fou r. Video RAM M em ory. A vid eo ad ap ter in stalled in you r system u ses a p ortion of you r system ’s low m em ory to h old grap h ics or ch aracter in form ation for d isp lay, bu t n orm ally on ly wh en in basic VGA m od e. A vid eo card m ay h ave 4M or 8M on board , bu t m ost of th at is u sed by th e vid eo ch ip set on th e card an d n ot d irectly accessed by you r p rocessor. W h en in basic VGA m od e, su ch as wh en at a DOS p rom p t or wh en ru n n in g in W in d ows safe m od e, you r p rocessor can d irectly access u p to 128K of th e vid eo RAM from ad d ress A0000-BFFFFh . All m od ern vid eo card s also h ave on board BIOS n orm ally ad d ressed at C0000-C7FFFh , wh ich is p art of th e m em ory sp ace reserved for ad ap ter card BIOS. Gen erally, th e h igh er th e resolu tion an d color cap abilities of th e vid eo ad ap ter, th e m ore system m em ory th e vid eo ad ap ter u ses, bu t again th at ad d ition al m em ory (p ast 128K) is n ot n orm ally accessible by th e p rocessor. In stead , th e system tells th e vid eo ch ip wh at sh ou ld be d isp layed , an d th e vid eo ch ip gen erates th e p ictu re by p u ttin g d ata d irectly in to th e vid eo RAM on th e card . In th e stan d ard system -m em ory m ap , a total of 128K is reserved for u se by th e vid eo card to store cu rren tly d isp layed in form ation wh en in basic VGA m od e. Th e reserved vid eo m em ory is located in segm en ts A000 an d B000. Th e vid eo ad ap ter ROM u ses ad d ition al u p p er m em ory sp ace in segm en t C000. Even with th e n ew m u ltip le m on itor featu re in W in d ows 98, on ly on e vid eo card (th e p rim ary vid eo card ) is in th e m em ory m ap ; all oth ers u se n o low system m em ory. Th e location of vid eo ad ap ter RAM is resp on sible for th e 640K DOS conventional m em ory barrier. DOS can u se all available con tigu ou s m em ory in th e first m egabyte of m em ory u n til th e vid eo ad ap ter RAM is en cou n tered . Th e u se of an cien t vid eo ad ap ters su ch as th e MDA an d CGA allows DOS access to m ore th an 640K of system m em ory. Th e vid eo m em ory wall begin s at A0000 for th e EGA, MCGA, an d VGA system s, bu t th e MDA an d CGA d o n ot u se as m u ch vid eo RAM, wh ich leaves som e sp ace th at can be u sed by DOS an d p rogram s. Th e p reviou s segm en t an d offset exam p les sh ow th at th e MDA ad ap ter

The System Logical M emory Layout

en ables DOS to u se an ad d ition al 64K of m em ory (all of segm en t A000), brin gin g th e total for DOS p rogram sp ace to 704K. Sim ilarly, th e CGA en ables a total of 736K of p ossible con tigu ou s m em ory. Th e EGA, VGA, or MCGA is lim ited to th e n orm al m axim u m of 640K of con tigu ou s m em ory becau se of th e larger am ou n t u sed by vid eo RAM. Th e m axim u m DOS-p rogram m em ory worksp ace, th erefore, d ep en d s on wh ich vid eo ad ap ter is in stalled . Table 5.11 sh ows th e m axim u m am ou n t of m em ory available to DOS u sin g th e referen ced vid eo card . Table 5.11

DOS M em ory Lim it at ions Based on Video Adapt er Type

Video Adapt er Type

M axim um DOS M em ory

M onochrome Display Adapter (M DA)

704K

Color Graphics Adapter (CGA)

736K

Enhanced Graphics Adapter (EGA)

640K

Video Graphics Array (VGA)

640K

Super VGA (SVGA)

640K

eXtended Graphics Array (XGA)

640K

Usin g th is m em ory to 736K m igh t be p ossible d ep en d in g on th e vid eo ad ap ter, th e typ es of m em ory board s in stalled , ROM p rogram s on th e m oth erboard , an d th e typ e of system . You can u se som e of th is m em ory if you r system h as a 386 or h igh er p rocessor. W ith m em ory m an ager software (su ch as EMM386 th at com es with DOS an d W in d ows), wh ich can op erate th e Mem ory Man agem en t Un it (MMU) fou n d in th ose p rocessors, you can rem ap exten d ed m em ory in to th is sp ace. Rem em ber th at W in d ows 9x will au tom atically u se th is m em ory if available. Th e followin g section s exam in e h ow stan d ard vid eo ad ap ters u se th e system ’s m em ory. Th is m ap is im p ortan t becau se it m ay be p ossible to recogn ize som e of th is as u n u sed in som e system s, wh ich m ay free u p m ore sp ace for software d rivers to be load ed . Ob so l e t e Vi d e o Ad a p t e r Ty p e s. Th e MDA, CGA, an d EGA vid eo ad ap ter typ es are n ot u sed in an y cu rren t system s. Th e followin g section s give a brief d escrip tion of th e m em ory u sage of th ese ad ap ters so th at you can see th e p rogression of m em ory u sage as ad ap ters h ave evolved . If you still service or u se system s with th ese vid eo ad ap ters, p lease see th e Sixth ed ition of th e book on th e CD-ROM for th e com p lete m em ory m ap s for th is obsolete h ard ware. Mo n o ch r o m e D i s p la y A d a p t er Mem o r y ( MD A ) . Th e origin al Mon och rom e Disp lay Ad ap ter (MDA) u ses on ly a 4K p ortion of th e reserved vid eo RAM from B0000-B0FFF. Becau se th e ROM cod e u sed to op erate th is ad ap ter is actu ally a p ortion of th e m oth erboard ROM, n o ad d ition al ROM sp ace is u sed in segm en t C000. Note th at alth ou gh th e origin al Mon och rom e Disp lay Ad ap ter on ly u sed 4K of m em ory startin g at B0000, a VGA ad ap ter ru n n in g in Mon och rom e em u lation m od e (Mon o Text Mod e) activates 32K of RAM at th is ad d ress. A tru e Mon och rom e Disp lay Ad ap ter h as n o on board BIOS, an d in stead is op erated by d river p rogram s fou n d in th e p rim ary m oth erboard BIOS.

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Co lo r Gr a p h i cs A d a p t er ( CGA ) Mem o r y. Th e Color Grap h ics Ad ap ter (CGA) u ses a 16K p ortion of th e reserved vid eo RAM from B8000-BBFFF. Becau se th e ROM cod e u sed to op erate th is ad ap ter is a p ortion of th e m oth erboard ROM, n o ad d ition al ROM sp ace is u sed in segm en t C000. Th e CGA card leaves m em ory from A0000-B7FFF free, wh ich can be u sed by m em ory m an agers for ad d ition al DOS m em ory sp ace. However, th is p reclu d es u sin g an y grap h ics m od e software su ch as W in d ows. Th e origin al CGA card on ly u sed 16K of sp ace startin g at B8000, wh ereas a VGA ad ap ter ru n n in g in CGA em u lation (Color Text) m od e can activate 32K of RAM at th is ad d ress. Th e origin al CGA card h as n o on board BIOS an d is in stead op erated by d river p rogram s fou n d in th e p rim ary m oth erboard BIOS. En h a n ced Gr a p h i cs A d a p t er ( EGA ) Mem o r y. Th e En h an ced Grap h ics Ad ap ter (EGA) u ses all 128K of th e vid eo RAM from A0000-BFFFF. Th e ROM cod e u sed to op erate th is ad ap ter is on th e ad ap ter an d con su m es 16K of m em ory from C0000-C3FFF. Th e origin al IBM EGA card on ly u sed 16K of ROM sp ace at C0000. Afterm arket com p atible EGA ad ap ters can u se ad d ition al ROM sp ace u p to 32K total. Th e m ost in terestin g th in g to n ote abou t EGA (an d th is ap p lies to VGA ad ap ters, as well) is th at segm en ts A000 an d B000 are n ot all u sed at all tim es. For exam p le, if th e card is in a grap h ics m od e, on ly segm en t A000 wou ld ap p ear to h ave RAM in stalled , wh ereas segm en t B000 wou ld ap p ear com p letely em p ty. If you switch ed th e m od e of th e ad ap ter (th rou gh software) in to Color Text m od e, segm en t A000 wou ld in stan tly ap p ear em p ty, an d th e last h alf of segm en t B000 wou ld su d d en ly “blin k on .” Th e m on och rom e text m od e RAM area wou ld p ractically n ever be u sed on a m od ern system , becau se little or n o software wou ld ever n eed to switch th e ad ap ter in to th at m od e. Th e EGA card becam e som ewh at p op u lar after it ap p eared , bu t th is was q u ickly oversh ad owed by th e VGA card th at followed . Most of th e VGA ch aracteristics with regard to m em ory are th e sam e as th e EGA becau se th e VGA is backward com p atible with EGA. Vi d e o Gra p h i c s Arra y (VGA) Me m o ry . All VGA-com p atible card s, in clu d in g Su p er VGA card s, are alm ost id en tical to th e EGA in term s of m em ory u se. Ju st as with th e EGA, th ey u se all 128K of th e vid eo RAM from A0000-BFFFF, bu t n ot all at on ce. Again , th e vid eo RAM area is sp lit in to th ree d istin ct region s, an d each of th ese region s is u sed on ly wh en th e ad ap ter is in th e corresp on d in g m od e. On e m in or d ifferen ce with th e EGA card s is th at virtu ally all VGA card s u se th e fu ll 32K allotted to th em for on board ROM (C0000 to C7FFF). Figu re 5.15 sh ows th e VGA ad ap ter m em ory m ap . You can see th at th e typ ical VGA card u ses a fu ll 32K of sp ace for th e on board ROM con tain in g d river cod e. Som e VGA card s m ay u se sligh tly less, bu t th is is rare. Ju st as with th e EGA card , th e vid eo RAM areas are on ly active wh en th e ad ap ter is in th e p articu lar m od e d esign ated . In oth er word s, wh en a VGA ad ap ter is in grap h ics m od e, on ly segm en t A000 is u sed ; wh en it is in color text m od e, on ly th e last h alf of segm en t B000 is u sed . Becau se th e VGA ad ap ter is alm ost n ever ru n in m on och rom e text m od e, th e first h alf of segm en t B000 rem ain s u n u sed (B0000-B7FFF). Figu re 5.15 also sh ows th e stan d ard m oth erboard ROM BIOS so th at you can get a p ictu re of h ow th e en tire UMA is laid ou t with th is ad ap ter.

The System Logical M emory Layout

. G M C V R

= = = = = =

Empty Addresses Video Graphics Array (VGA) Adapter Graphics Mode Video RAM VGA Monochrome Text Mode Video RAM VGA Color Text Mode Video RAM Standard VGA Video ROM BIOS Standard Motherboard ROM BIOS

: 0A0000: 0B0000: : 0C0000: 0D0000: : 0E0000: 0F0000:

0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV................................ ................................................................ 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--................................................................ RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR

FIG. 5.15 Th e VGA (an d Su p er VGA) ad ap ter m em ory m ap . System s th at u se th e LPX (Low Profile) m oth erboard d esign in an LPX- or Slim lin e-typ e case in corp orate th e vid eo ad ap ter in to th e m oth erboard . In th ese system s, even th ou gh th e vid eo BIOS an d m oth erboard BIOS m ay be from th e sam e m an u factu rer, th ey are always set u p to em u late a stan d ard VGA-typ e ad ap ter card . In oth er word s, th e vid eo BIOS ap p ears in th e first 32K of segm en t C000 ju st as if a stan d alon e VGA-typ e card were p lu gged in to a slot. Th e bu ilt-in vid eo circu it in th ese system s can be easily d isabled via a switch or ju m p er, wh ich th en allows a con ven tion al VGA-typ e card to be p lu gged in . By h avin g th e bu ilt-in VGA act exactly as if it were a sep arate card , d isablin g it allows a n ew ad ap ter to be in stalled with n o com p atibility p roblem s th at m igh t arise if th e vid eo d rivers h ad been in corp orated in to th e m oth erboard BIOS. If you were in volved with th e PC in d u stry in 1987, you m igh t rem em ber h ow lon g it took for clon e vid eo card m an u factu rers to accu rately cop y th e IBM VGA circu its. It took n early two years (alm ost to 1989) before you cou ld bu y an afterm arket VGA card an d exp ect it to ru n everyth in g an IBM VGA system wou ld with n o p roblem s. Som e of m y associates wh o bou gh t som e of th e early card s in ad verten tly becam e m em bers of th e vid eo card m an u factu rer’s “ROM of th e week” clu b! Th ey were con stan tly fin d in g p roblem s with th e op eration of th ese card s, an d m an y u p d ated an d p atch ed ROMs were sen t to try an d fix th e p roblem s. Not wan tin g to p ay for th e p rivilege of beta testin g th e latest attem p ts at VGA com p atibility, I bit th e bu llet an d took th e easy way ou t. I bou gh t th e IBM VGA card (PS/ 2 Disp lay Ad ap ter) for $595. Note th at a top lin e AGP vid eo card tod ay n orm ally ru n s for less th an th is! Alth ou gh th e card worked very well in m ost situ ation s, I d id fin d com p atibility p roblem s with th e m em ory u se of th is card an d a few oth er card s, m ain ly SCSI ad ap ters. Th is was m y first in trod u ction to wh at I call scratch pad m em ory u se by an ad ap ter. I fou n d th at m an y d ifferen t typ es of ad ap ters m ay u se som e areas in th e UMA for m ap p in g scratch p ad m em ory. Th is refers to m em ory on th e card th at stores statu s in form ation , con figu ration d ata, or an y oth er tem p orary typ e in form ation of a variable n atu re. Most card s keep th is scratch p ad m em ory to th em selves an d d o n ot attem p t to m ap it in to th e

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p rocessor’s ad d ress sp ace. Bu t som e card s d o p lace th is typ e of m em ory in th e ad d ress sp ace so th at th e d river p rogram s for th e card can u se it. Figu re 5.16 sh ows th e m em ory m ap of th e IBM PS/ 2 Disp lay Ad ap ter (IBM’s origin al VGA card ).

. G M C V v R

= = = = = = =

Empty Addresses Video Graphics Array (VGA) Adapter Graphics Mode Video RAM VGA Monochrome Text Mode Video RAM VGA Color Text Mode Video RAM IBM VGA Video ROM BIOS IBM VGA Scratch Pad memory (used by the card) Standard Motherboard ROM BIOS

: 0A0000: 0B0000: : 0C0000: 0D0000: : 0E0000: 0F0000:

0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--VVVVVVVVVVVVVVVVVVVVVVVV..vvvvvv........vv...................... ................................................................ 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--................................................................ RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR

FIG. 5.16 IBM’s ISA-bu s VGA card (PS/ 2 Disp lay Ad ap ter) m em ory m ap . Th ere is n oth in g d ifferen t abou t th is VGA card an d an y oth er with resp ect to th e vid eo RAM area. W h at is d ifferen t is th at th e ROM cod e th at op erates th is ad ap ter on ly con su m es 24K of m em ory from C0000-C5FFF. Also stran ge is th e 2K “h ole” at C6000, an d th e 6K of scratch p ad m em ory startin g at C6800, an d th e ad d ition al 2K of scratch p ad m em ory at CA000. In p articu lar, th e 2K “straggler” area really cau gh t m e off gu ard wh en I in stalled a SCSI h ost ad ap ter in th is system th at h ad a 16K on board BIOS with a d efau lt startin g ad d ress of C8000. I im m ed iately ran in to a con flict th at com p letely d isabled th e system . In fact, it wou ld n ot boot, h ad n o d isp lay at all, an d cou ld on ly beep ou t error cod es th at in d icated th at th e vid eo card h ad failed . I first th ou gh t th at I h ad som eh ow “fried ” th e card , bu t rem ovin g th e n ew SCSI ad ap ter h ad everyth in g fu n ction in g n orm ally. I also cou ld get th e system to work with th e SCSI ad ap ter an d an old CGA card su bstitu tin g for th e VGA, so I im m ed iately kn ew a con flict was afoot. Th is scratch p ad m em ory u se was n ot d ocu m en ted clearly in th e tech n ical-referen ce in form ation for th e ad ap ter, so it was som eth in g th at I h ad to fin d ou t by trial an d error. If you h ave ever h ad two card s th at d on ’t work togeth er in th e sam e system , th is is on e exam p le of a p oten tial con flict th at can d isable th e system com p letely! ◊◊ See “ Adapter M emory Configuration and Optimization,” p. 385

Need less to say, n oth in g cou ld be d on e abou t th is 2K of scratch p ad m em ory h an gin g ou t th ere, an d I h ad to work arou n d it as lon g as I h ad th is card in th e system . I solved m y SCSI ad ap ter p roblem by m erely m ovin g th e SCSI ad ap ter BIOS to a d ifferen t ad d ress.

The System Logical M emory Layout

Not e I have seen other VGA-type video adapters use scratch pad memory, but they have all kept it within the C0000-C7FFF 32K region allotted normally for the video ROM BIOS. By using a 24K BIOS, I have seen other cards with up to 8K of scratch pad area, but none—except for IBM ’s—in which the scratch pad memory goes beyond C8000.

Adapt er ROM and Special Purpose RAM M em ory. Th e secon d 128K of u p p er m em ory begin n in g at segm en t C000 is reserved for th e software p rogram s, or BIOS (basic in p u t/ ou tp u t system ), on th e ad ap ter board s p lu gged in to th e system slots. Th ese BIOS p rogram s are stored on sp ecial ch ip s kn own as read -on ly m em ory (ROM). Most ad ap ters tod ay u se EEPROM (Electrically Erasable Program m able ROM) or flash ROM, wh ich can both be erased an d rep rogram m ed righ t in th e system with ou t rem ovin g th e ch ip or card . Up d atin g th e flash ROM is as sim p le as ru n n in g th e u p d ate p rogram you get from th e m an u factu rer an d followin g th e d irection s on screen . It p ays to ch eck p eriod ically with you r card m an u factu rers to see if th ey h ave flash ROM u p d ates for th eir card s. ROM is u sefu l for sem i-p erm an en t p rogram s th at always m u st be p resen t wh ile th e system is ru n n in g, an d esp ecially for bootin g. Grap h ics board s, h ard d isk con trollers, com m u n ication s board s, an d exp an d ed m em ory board s, for exam p le, are ad ap ter board s th at m igh t h ave ad ap ter ROM. Th ese ad ap ter ROMs are in a sep arate area of m em ory from th e VGA vid eo RAM area an d th e m oth erboard ROM as well. On system s based on th e 386 CPU ch ip or h igh er, m em ory m an agers th at are in clu d ed with DOS 6 or th ird -p arty p rogram s can load d evice d rivers an d m em ory-resid en t p rogram s in to u n u sed region s in th e UMA. To actu ally m ove th e RAM u sage on an y given ad ap ter req u ires th at you con su lt th e d ocu m en tation for th e card . Most old er card s req u ire th at sp ecific switch es or ju m p ers be ch an ged , an d th e settin gs will p robably n ot be obviou s with ou t th e m an u al. Most n ewer card s, esp ecially th ose th at are Plu g an d Play, allow th ese settin gs to be ch an ged by software th at eith er com es with th e card , or th e Device Man ager p rogram th at goes with som e of th e n ewer op eratin g system s su ch as W in d ows 95/ 98 or NT 5.0 an d n ewer. Vi d e o Ad a p t e r BIOS. Th e vid eo ad ap ter BIOS h an d les th e tran slation between th e vid eo card an d basic VGA m od e grap h ics in stru ction s. Rem em ber th at you r system is in a basic VGA m od e d u rin g boot, an d wh en ever you are ru n n in g W in d ows in safe m od e. Alth ou gh 128K of u p p er m em ory begin n in g at segm en t C000 is reserved for u se by ad ap ter BIOSs, n ot all th is sp ace is u sed by variou s vid eo ad ap ters com m on ly fou n d on PCs. Table 5.12 d etails th e am ou n t of sp ace u sed by th e BIOS on each typ e of com m on vid eo ad ap ter card .

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Table 5.12

M em ory Used by Different Video Cards

Type of Adapt er

Adapt er BIOS M em ory Used

M onochrome Display Adapter (M DA)

None - Drivers in M otherboard BIOS

Color Graphics Adapter (CGA)

None - Drivers in M otherboard BIOS

Enhanced Graphics Adapter (EGA)

16K onboard (C0000-C3FFF)

Video Graphics Array (VGA)

32K onboard (C0000-C7FFF)

Super VGA (SVGA)

32K onboard (C0000-C7FFF)

Dep en d in g on th e basic VGA m od e selected (Color Text, Mon och rom e Text, or VGA Grap h ics), th e vid eo card will u se all th e 128K of u p p er m em ory begin n in g at segm en t C000. In ad d ition , th ese grap h ics card s m ay con tain u p to 8M or m ore of on board m em ory for u se in th eir n ative h igh -resolu tion m od es in wh ich to store cu rren tly d isp layed d ata an d m ore q u ickly fetch n ew screen d ata for d isp lay. H a rd D i sk Co n t ro l l e r a n d SCSI H o st Ad a p t e r BIOS. Th e u p p er m em ory ad d resses C0000 to DFFFF also are u sed for th e bu ilt-in BIOS con tain ed on m an y h ard d rive an d SCSI con trollers. Table 5.13 d etails th e am ou n t of m em ory an d th e ad d resses com m on ly u sed by th e BIOS con tain ed on h ard d rive ad ap ter card s. Table 5.13

M em ory Addresses Used by Different Hard Drive Adapt er Cards

Disk Adapt er Type

Onboard BIOS Size

BIOS Address Range

M ost XT Compatible Controllers

8K

C8000-C9FFF

M ost AT Controllers

None

Drivers in M otherboard BIOS

M ost Standard IDE Adapters

None

Drivers in M otherboard BIOS

M ost Enhanced IDE Adapters

16K

C8000-CBFFF

Some SCSI Host Adapters

16K

C8000-CBFFF

Some SCSI Host Adapters

16K

DC000-DFFFF

Th e h ard d rive or SCSI ad ap ter card u sed on a p articu lar system m ay u se a d ifferen t am ou n t of m em ory, bu t it is m ost likely to u se th e m em ory segm en t begin n in g at C800 becau se th is ad d ress is con sid ered p art of th e IBM stan d ard for p erson al com p u ters. Virtu ally all th e d isk con troller or SCSI ad ap ters tod ay th at h ave an on board BIOS allow th e BIOS startin g ad d ress to be easily m oved in th e C000 an d D000 segm en ts. Th e location s listed in Table 5.13 are on ly th e d efau lt ad d resses th at m ost of th ese card s u se. If th e d efau lt ad d ress is alread y in u se by an oth er card , you h ave to con su lt th e d ocu m en tation for th e n ew card to see h ow to ch an ge th e BIOS startin g ad d ress to avoid an y con flicts. Figu re 5.17 sh ows an exam p le m em ory m ap for an Ad ap tec AHA-2940 SCSI ad ap ter.

The System Logical M emory Layout

. G M C V S R

= = = = = = =

Empty Addresses Video Graphics Array (VGA) Adapter Graphics Mode Video RAM VGA Monochrome Text Mode Video RAM VGA Color Text Mode Video RAM Standard VGA Video ROM BIOS SCSI Host Adapter ROM BIOS Standard Motherboard ROM BIOS

: 0A0000: 0B0000: : 0C0000: 0D0000: : 0E0000: 0F0000:

0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV................................ ................................................SSSSSSSSSSSSSSSS 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--................................................................ RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR

FIG. 5.17 Ad ap tec AHA-2940U SCSI ad ap ter d efau lt m em ory u se. Note h ow th is SCSI ad ap ter fits in h ere. Alth ou gh n o con flicts are in th e UMA m em ory, th e free region s h ave been fragm en ted by th e p lacem en t of th e SCSI BIOS. Becau se m ost system s d o n ot h ave an y BIOS in segm en t E000, th at rem ain s as a free 64K region . W ith n o oth er ad ap ters u sin g m em ory, th is exam p le sh ows an oth er free UMB (Up p er Mem ory Block) startin g at C8000 an d con tin u in g th rou gh DBFFF, wh ich rep resen ts an 80K free region . Usin g th e EMM386 d river th at com es with DOS or W in d ows, m em ory can be m ap p ed in to th ese two region s for load in g 16-bit m em ory-resid en t d rivers an d p rogram s. Note th at th is will h ave n o effect on 32-bit W in d ows 95/ 98 or NT d rivers, as th ose are load ed in to exten d ed m em ory au tom atically. Un fortu n ately, becau se p rogram s can n ot be sp lit across region s, th e largest 16-bit d river p rogram you cou ld load is 80K, wh ich is th e size of th e largest free region . It wou ld be m u ch better if you cou ld m ove th e SCSI ad ap ter BIOS so th at it was n ext to th e VGA BIOS, as th is wou ld brin g th e free UMB sp ace to a sin gle region of 144K. It is m u ch easier an d m ore efficien t to u se a sin gle 144K region th an two region s of 80K an d 64K, resp ectively. Note again th at m an ip u latin g m em ory in th is m an n er is n ot n ecessary with 32-bit d rivers, becau se th ey are au tom atically load ed in to exten d ed m em ory an yway. Fortu n ately, it is p ossible to m ove th is p articu lar SCSI ad ap ter becau se it is a Plu g-an d Play card . Th is m ean s you can con trol th e resou rce settin gs via th e W in 95/ 98 Device Man ager. If you h ave an old er n on –Plu g-an d -Play card , th en you will likely n eed th e d ocu m en tation to d iscover th e switch an d ju m p er settin gs for th e card , as m ost m an u factu rers d on ’t clearly label th em . If you can ’t fin d you r origin al d ocu m en tation , you can con su lt th e Micro Hou se PC Hard ware Library on th e CD with th is book, wh ich con tain s an exten sive d atabase of ad ap ter card s, m oth erboard s, an d h ard d rives sh owin g ju m p er settin gs, con figu ration in form ation , m an u factu rer in form ation , an d so on .

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Most card s sold sin ce ’96 h ave been Plu g an d Play, m ean in g th at th ey are fu lly software con figu rable. After ch an gin g th e ap p rop riate switch es to m ove th e SCSI ad ap ter BIOS to start at C8000, th e op tim ized m ap wou ld look like Figu re 5.18.

. G M C V S R

= = = = = = =

Empty Addresses Video Graphics Array (VGA) Adapter Graphics Mode Video RAM VGA Monochrome Text Mode Video RAM VGA Color Text Mode Video RAM Standard VGA Video ROM BIOS SCSI Host Adapter ROM BIOS Standard Motherboard ROM BIOS

: 0A0000: 0B0000: : 0C0000: 0D0000: : 0E0000: 0F0000:

0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVSSSSSSSSSSSSSSSS................ ................................................................ 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--................................................................ RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR

FIG. 5.18 Ad ap tec AHA-2940U SCSI ad ap ter with op tim ized m em ory u se. Notice h ow th e free sp ace is n ow a sin gle con tigu ou s block of 144K. Th is rep resen ts a far m ore op tim u m setu p th an th e d efau lt settin gs. Ne t w o rk Ad a p t e rs. Network ad ap ter card s also can u se u p p er m em ory in segm en ts C000 an d D000. Th e exact am ou n t of m em ory u sed an d th e startin g ad d ress for each n etwork card vary with th e typ e an d m an u factu rer of th e card . Som e n etwork card s d o n ot u se an y m em ory at all. A n etwork card m igh t h ave two p rim ary u ses for m em ory. Th ey are as follows: ■ IPL (In itial Program Load or Boot) ROM ■ Sh ared Mem ory (RAM) An IPL ROM is u su ally an 8K ROM th at con tain s a bootstrap load er p rogram th at allows th e system to boot d irectly from a file server on th e n etwork. Th is allows th e rem oval of all d isk d rives from th e PC, creatin g a d iskless workstation . Becau se n o flop p y or h ard d isk wou ld be in th e system to boot from , th e IPL ROM gives th e system th e in stru ction s n ecessary to locate an im age of th e op eratin g system on th e file server an d load it as if it were on an in tern al d rive. If you are n ot u sin g you r system as a d iskless workstation , it wou ld be ben eficial to d isable an y IPL ROM or IPL ROM socket on th e ad ap ter card . Note th at m an y n etwork ad ap ters d o n ot allow th is socket to be d isabled , wh ich m ean s th at you lose th e 8K of ad d ress sp ace for oth er h ard ware, even if th e ROM ch ip is rem oved from th e socket!

The System Logical M emory Layout

Shared m em ory refers to a sm all p ortion of RAM con tain ed on th e n etwork card th at is m ap p ed in to th e PC’s u p p er m em ory area. Th is region is u sed as a m em ory win d ow on to th e n etwork an d offers very fast d ata tran sfer from th e n etwork card to th e system . IBM p ion eered th e u se of sh ared m em ory for its first Token Rin g n etwork ad ap ters, an d n ow sh ared m em ory is in com m on u se am on g oth er com p an ies’ n etwork ad ap ters. Sh ared m em ory was first d evised by IBM becau se it fou n d th at tran sfers u sin g th e DMA ch an n els were n ot fast en ou gh in m ost system s. Th is h ad m ain ly to d o with som e q u irks in th e DMA con troller an d bu s d esign , wh ich esp ecially affected 16-bit ISA bu s system s. Network ad ap ters th at d o n ot u se sh ared m em ory will eith er u se DMA or Program m ed I/ O (PIO) tran sfers to m ove d ata to an d from th e n etwork ad ap ter. Alth ou gh sh ared m em ory is faster th an eith er DMA or PIO for ISA system s, it d oes req u ire 16K of UMA sp ace to work. Most stan d ard p erform an ce n etwork ad ap ters u se PIO becau se th is m akes th em easier to con figu re, an d th ey req u ire n o free UMA sp ace, wh ereas m ost h igh p erform an ce ad ap ters will u se sh ared m em ory. Th e sh ared m em ory region on m ost n etwork ad ap ters th at u se on e is u su ally 16K in size an d m ay be located at an y u ser-selected 4K in crem en t of m em ory in segm en ts C000 or D000. Figu re 5.19 sh ows th e d efau lt m em ory ad d resses for th e IPL ROM an d sh ared m em ory of an IBM Token Rin g n etwork ad ap ter, alth ou gh m an y oth er n etwork ad ap ters su ch as Eth ern et ad ap ters wou ld be sim ilar. On e th in g to n ote is th at m ost Eth ern et ad ap ters u se eith er a DMA ch an n el or stan d ard PIO (Program m ed I/ O) com m an d s to sen d d ata to an d from th e n etwork, an d d on ’t u se sh ared m em ory like m an y Token Rin g card s.

. G M C V I N R

= = = = = = = =

Empty Addresses Video Graphics Array (VGA) Adapter Graphics Mode Video RAM VGA Monochrome Text Mode Video RAM VGA Color Text Mode Video RAM Standard VGA Video ROM BIOS Token Ring Network Adapter IPL ROM Token Ring Network Adapter Shared RAM Standard Motherboard ROM BIOS

: 0A0000: 0B0000: : 0C0000: 0D0000: : 0E0000: 0F0000:

0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV................IIIIIIII........ ................................NNNNNNNNNNNNNNNN................ 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--................................................................ RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR

FIG. 5.19 Network ad ap ter d efau lt m em ory m ap . I h ave also in clu d ed th e stan d ard VGA vid eo BIOS in Figu re 5.19 becau se n early every system wou ld h ave a VGA-typ e vid eo ad ap ter as well. Note th at th ese d efau lt ad d resses for th e IPL ROM an d th e sh ared m em ory can easily be ch an ged by recon figu rin g th e

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ad ap ter. Most oth er n etwork ad ap ters are sim ilar in th at th ey also wou ld h ave an IPL ROM an d a sh ared m em ory ad d ress, alth ou gh th e sizes of th ese areas an d th e d efau lt ad d resses m ay be d ifferen t. Most n etwork ad ap ters th at in corp orate an IPL ROM op tion can d isable th e ROM an d socket su ch th at th ose ad d resses are n ot n eed ed at all. Th is h elp s to con serve UMA sp ace an d p reven t p ossible fu tu re con flicts if you are n ever goin g to u se th e fu n ction . Notice in th is case th at th e SCSI ad ap ter u sed in Figu re 5.20 wou ld fit both at its d efau lt BIOS ad d ress of DC000, an d th e op tim u m ad d ress of C8000. Th e Token -Rin g sh ared m em ory location is n ot op tim u m an d cau ses th e UMB sp ace to be fragm en ted . By ad ju stin g th e location of th e sh ared m em ory, th is setu p can be greatly im p roved . Figu re 5.20 sh ows an op tim u m setu p with both th e Token -Rin g ad ap ter an d th e SCSI ad ap ter in th e sam e m ach in e.

. G M C V S I N R

= = = = = = = = =

Empty Addresses Video Graphics Array (VGA) Adapter Graphics Mode Video RAM VGA Monochrome Text Mode Video RAM VGA Color Text Mode Video RAM Standard VGA Video ROM BIOS SCSI Host Adapter ROM BIOS Token Ring Network Adapter IPL ROM Token Ring Network Adapter Shared RAM Standard Motherboard ROM BIOS

: 0A0000: 0B0000: : 0C0000: 0D0000: : 0E0000: 0F0000:

0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVSSSSSSSSSSSSSSSSNNNNNNNNNNNNNNNN IIIIIIII........................................................ 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--................................................................ RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR

FIG. 5.20 Ad ap tec AHA-2940U SCSI ad ap ter an d n etwork ad ap ter with op tim ized m em ory u se. Th is con figu ration allows a sin gle 120K UMB th at can very efficien tly be u sed to load software d rivers. Notice th at th e IPL ROM was m oved to D0000, wh ich p laces it as th e last item in stalled before th e free m em ory sp ace. Th is is becau se if th e IPL fu n ction is n ot n eed ed , it can be d isabled an d th e UMB sp ace wou ld in crease to 128K an d still be con tigu ou s. If th e d efau lt settin gs are u sed for both th e SCSI an d n etwork ad ap ters, th e UMB m em ory wou ld be fragm en ted in to th ree region s of 16K, 40K, an d 64K. Th e m em ory wou ld still fu n ction , bu t it is h ard ly an op tim u m situ ation . Note th at th e Plu g-an d -Play featu re in W in 95/ 98 an d NT 5.0 d oes n ot attem p t to op tim ize m em ory u se, on ly to resolve con flicts. Of cou rse, with 32-bit d rivers, th e location an d size of free Up p er Mem ory Blocks d on ’t really m atter, as 32-bit d rivers will be load ed in to exten d ed m em ory. If you are still occasion ally ru n n in g DOS-based p rogram s su ch as gam es, you will wan t to m an u ally op tim ize th e u p p er m em ory area con figu ration for m axim u m m em ory an d p erform an ce.

The System Logical M emory Layout

Ot h e r ROMs i n t h e Up p e r Me m o ry Are a . In ad d ition to th e BIOS for h ard d rive con trollers, SCSI ad ap ters, an d n etwork card s, u p p er m em ory segm en ts C000 an d D000 are u sed by som e term in al em u lators, secu rity ad ap ters, m em ory board s, an d variou s oth er d evices an d ad ap ter board s. Som e ad ap ters m ay req u ire m em ory on ly for BIOS in form ation , an d oth ers m ay req u ire RAM in th ese u p p er m em ory segm en ts. For in form ation on a sp ecific ad ap ter, con su lt th e m an u factu rer’s d ocu m en tation . M ot herboard BIOS M em ory. Th e last 128K of reserved m em ory is u sed by th e m oth erboard BIOS. Th e BIOS p rogram s in ROM con trol th e system d u rin g th e boot-u p p roced u re an d rem ain as d rivers for variou s h ard ware in th e system d u rin g n orm al op eration . Becau se th ese p rogram s m u st be available im m ed iately, th ey can n ot be load ed from a d evice su ch as a d isk d rive. Fou r m ain p rogram s stored in m ost m oth erboard ROMs are as follows: ■ Power-On Self Test, th e POST, is a set of rou tin es th at tests th e m oth erboard , m em ory, d isk con trollers, vid eo ad ap ters, keyboard , an d oth er p rim ary system com p on en ts. Th is rou tin e is u sefu l wh en you trou blesh oot system failu res or p roblem s. ◊◊ See “ The Power-On Self Test (POST),” p. 984

■ Th e bootstrap loader rou tin e in itiates a search for an op eratin g system on a flop p y d isk or h ard d isk. If an op eratin g system is fou n d , it is load ed in to m em ory an d given con trol of th e system . ◊◊ See “ The Boot Process,” p. 1042

■ Th e BIOS is th e software in terface to all th e h ard ware in th e system . Th e BIOS is a collection of in d ivid u al d rivers for th e h ard ware in th e system . W ith th e BIOS, a p rogram easily can access featu res in th e system by callin g on a stan d ard BIOS d river fu n ction in stead of talkin g d irectly to th e d evice. √√ See “ BIOS,” p. 208

■ Th e CMOS Setup p rogram is a m en u -d riven ap p lication th at is u sed for system con figu ration an d setu p . It is n orm ally activated at boot tim e by p ressin g th e p rop er key. Th is p rogram is u sed to set basic system con figu ration p aram eters an d BIOS featu res, m oth erboard an d ch ip set featu res, u ser p referen ces an d secu rity featu res (p assword s), an d in som e cases to ru n lim ited d iagn ostics. Not all system s h ave th e CMOS Setu p p rogram in ROM; som e m u st load it from a flop p y d isk or h ard d isk in stead . Both segm en ts E000 an d F000 in th e m em ory m ap are con sid ered reserved for th e m oth erboard BIOS, bu t on ly som e system s actu ally u se th is en tire area. Old er 8-bit system s req u ire on ly segm en t F000 an d en able ad ap ter card ROM or RAM to u se segm en t

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E000. Most 16-bit or greater system s u se all of F000 for th e BIOS, an d m ay d ecod e bu t n ot u se an y of segm en t E000. By d ecod in g an area, th e m oth erboard essen tially grabs con trol of th e ad d resses, wh ich p reclu d es in stallin g an y oth er h ard ware in th is region . In oth er word s, it is n ot p ossible to con figu re ad ap ter card s to u se th is area. Th at is wh y you will fin d th at m ost ad ap ters th at u se m em ory sim p ly d o n ot allow an y ch oices for m em ory u se in segm en t E000. Alth ou gh th is m ay seem like a waste of 64K of m em ory sp ace, an y 386 or h igh er system can u se th e p owerfu l MMU in th e p rocessor to m ap RAM from exten d ed m em ory in to segm en t E000 as an Up p er Mem ory Block, an d su bseq u en tly u se it for load in g 16-bit d river software if n ecessary. Th is is a n ice solu tion to wh at oth erwise wou ld be wasted m em ory, alth ou gh it is n ot im p ortan t if you u se 32-bit d rivers. Man y d ifferen t ROM-in terface p rogram s are in th e IBM m oth erboard s, bu t th e location of th ese p rogram s is m ostly con sisten t. Figu re 5.21 sh ows th e m oth erboard ROM BIOS m em ory u se of m ost 16-bit or greater system s.

. = Empty Addresses R = Standard Motherboard ROM BIOS : 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F--0E0000: ................................................................ 0F0000: RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR

FIG. 5.21 Moth erboard ROM BIOS m em ory u se of m ost system s. Note th at th e stan d ard system BIOS u ses on ly segm en t F000 (64K). In alm ost every case, th e rem ain d er of th e BIOS area (segm en t E000) is com p letely free an d can be u sed as UMA block sp ace. Ext ended M em ory As m en tion ed p reviou sly in th is ch ap ter, th e m em ory m ap on a system based on th e 286 or h igh er p rocessor can exten d beyon d th e 1M bou n d ary th at exists wh en th e p rocessor is in real m od e. On a 286 or 386SX system , th e exten d ed m em ory lim it is 16M; on a 386DX, 486, Pen tiu m , Pen tiu m MMX, or Pen tiu m Pro system , th e exten d ed m em ory lim it is 4G (4,096M). System s based on th e Pen tiu m II p rocessor h ave a lim it of 64G (65,536M). For a system to ad d ress m em ory beyon d th e first m egabyte, th e p rocessor m u st be in protected m ode—th e n ative m od e of 286 an d h igh er p rocessors. On a 286, on ly p rogram s d esign ed to ru n in p rotected m od e can take ad van tage of exten d ed m em ory. 386 an d h igh er p rocessors offer an oth er m od e, called virtual real m ode, wh ich en ables exten d ed m em ory to be, in effect, ch op p ed in to 1M p ieces (each its own real-m od e session ). Virtu al real m od e also allows for several of th ese session s to be ru n n in g sim u ltan eou sly in p rotected areas of m em ory. Th ese can be seen as DOS p rom p t session s or win d ows with in W in d ows 95/ 98, NT, or OS/ 2. Alth ou gh several DOS p rogram s can be ru n n in g at

The System Logical M emory Layout

on ce, each still is lim ited to a m axim u m of 640K of m em ory becau se each session sim u lates a real-m od e en viron m en t, righ t d own to th e BIOS an d Up p er Mem ory Area. Ru n n in g several p rogram s at on ce in virtu al real m od e, called m ultitasking, req u ires software th at can m an age each p rogram an d keep th em from crash in g in to on e an oth er. OS/ 2, W in d ows 95/ 98, an d W in d ows NT all d o th is. Th e 286 an d h igh er CPU ch ip s also ru n in wh at is term ed real m ode, wh ich en ables fu ll com p atibility with th e 8088 CPU ch ip in stalled on th e PC/ XT-typ e com p u ter. Real m od e en ables you to ru n DOS p rogram s on e at a tim e on an AT-typ e system ju st like you wou ld on a PC/ XT. However, an AT-typ e system ru n n in g in real m od e, p articu larly a 386-, 486-, Pen tiu m -, Pen tiu m Pro-, or Pen tiu m II-based system , is really fu n ction in g as little m ore th an a tu rbo PC. In real m od e, th ese p rocessors can em u late th e 8086 or 8088, bu t th ey can n ot op erate in p rotected m od e at th e sam e tim e. For th at reason , th e 386 an d above also p rovid e a virtu al real m od e th at op erates u n d er p rotected m od e. Th is allows for th e execu tion of real-m od e p rogram s u n d er th e con trol of a p rotected -m od e op eratin g system , su ch as W in 95/ 98, NT, or OS/ 2.

Not e Extended memory is basically all memory past the first megabyte, which can only be accessed while the processor is in protected mode.

XM S M em ory. Th e exten d ed m em ory sp ecification (XMS) was d evelop ed in 1987 by Microsoft, In tel, AST Corp ., an d Lotu s Develop m en t to sp ecify h ow p rogram s wou ld u se exten d ed m em ory. Th e XMS sp ecification fu n ction s on system s based on th e 286 or h igh er an d allows real-m od e p rogram s (th ose d esign ed to ru n in DOS) to u se exten d ed m em ory an d an oth er block of m em ory u su ally ou t of th e reach of DOS. Before XMS, th ere was n o way to en su re coop eration between p rogram s th at switch ed th e p rocessor in to p rotected m od e an d u sed exten d ed m em ory. Th ere was also n o way for on e p rogram to kn ow wh at an oth er h ad been d oin g with th e exten d ed m em ory becau se n on e of th em cou ld see th at m em ory wh ile in real m od e. HIMEM.SYS becom es an arbitrator of sorts th at first grabs all th e exten d ed m em ory for itself an d th en d oles it ou t to p rogram s th at kn ow th e XMS p rotocols. In th is m an n er, several p rogram s th at u se XMS m em ory can op erate togeth er u n d er DOS on th e sam e system , switch in g th e p rocessor in to an d ou t of p rotected m od e to access th e m em ory. XMS ru les p reven t on e p rogram from accessin g m em ory th at an oth er h as in u se. Becau se W in d ows 3.x is a p rogram m an ager th at switch es th e system to an d from p rotected m od e in ru n n in g several p rogram s at on ce, it h as been set u p to req u ire XMS m em ory to fu n ction . W in d ows 95 op erates m ostly in p rotected m od e, bu t still calls on real m od e for access to m an y system com p on en ts. W in d ows NT is a tru e p rotected -m od e op eratin g system , as is OS/ 2. Exten d ed m em ory can be m ad e to con form to th e XMS sp ecification by in stallin g a d evice d river in th e CONFIG.SYS file. Th e m ost com m on XMS d river is HIMEM.SYS, wh ich is in clu d ed with W in d ows 3.x an d later version s of DOS, startin g with 4.0 an d u p . W in d ows 95/ 98 an d NT au tom atically allow XMS fu n ction s in DOS p rom p t session s, an d you can con figu re fu ll-blown DOS-m od e session s to allow XMS fu n ction s as well.

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High M em ory Area ( HM A) and t he A20 line. Th e High Mem ory Area (HMA) is an area of m em ory 16 bytes sh ort of 64K in size, startin g at th e begin n in g of th e first m egabyte of exten d ed m em ory. It can be u sed to load d evice d rivers an d m em ory-resid en t p rogram s to free u p con ven tion al m em ory for u se by real-m od e p rogram s. On ly on e d evice d river or m em ory-resid en t p rogram can be load ed in to HMA at on e tim e, n o m atter wh at its size. Origin ally, th is cou ld be an y p rogram , bu t Microsoft d ecid ed th at DOS cou ld get th ere first, an d bu ilt cap ability in to DOS 5 an d n ewer version s. Th e HMA area is extrem ely im p ortan t to th ose wh o u se DOS 5 or h igh er becau se th ese DOS version s can m ove th eir own kern el (abou t 45K of p rogram in stru ction s) in to th is area. Th is is accom p lish ed sim p ly by first load in g an XMS d river (su ch as HIMEM.SYS) an d ad d in g th e lin e D OS=H IGH to you r CONFIG.SYS file. Takin g ad van tage of th is DOS cap ability frees an oth er 45K or so of con ven tion al m em ory for u se by real-m od e p rogram s by essen tially m ovin g 45K of p rogram cod e in to th e first segm en t of exten d ed m em ory. Alth ou gh th is m em ory was su p p osed to be accessible in p rotected m od e on ly, it tu rn s ou t th at a d efect in th e d esign of th e origin al 286 (wh ich , fortu n ately, h as been p rop agated forward to th e m ore recen t p rocessors as a “featu re”) accid en tally allows access to m ost of th e first segm en t of exten d ed m em ory wh ile still in real m od e. Th e u se of th e HMA is con trolled by th e HIMEM.SYS or eq u ivalen t d river. Th e origin s of th is m em ory u sage are in terestin g becau se th ey are based on a bu g in th e origin al 286 p rocessor carried forward th rou gh even th e Pen tiu m II. Th e p roblem started from th e fact th at m em ory ad d resses in In tel p rocessors are d ictated by an overlap p in g segm en t an d offset ad d ress. By settin g th e segm en t ad d ress to FFFF— wh ich itself sp ecifies an actu al ad d ress of FFFF0, wh ich is 16 bytes from th e en d of th e first m egabyte—an d th en sp ecifyin g an offset of FFFF, wh ich is eq u al to 64K, you can create a m em ory ad d ress as follows: FFFF FFFF -----= 10FFEF +

segment offset total

Th is typ e of ad d ress is im p ossible on an 8088 or 8086 system th at h as on ly 20 ad d ress lin es an d th erefore can n ot calcu late an ad d ress th at large. By leavin g off th e lead in g d igit, th ese p rocessors in terp ret th e ad d ress as 0FFEF, in essen ce cau sin g th e ad d ress to “wrap arou n d ” an d en d u p 16 bytes from th e en d of th e first 64K segm en t of th e first m egabyte. Th e p roblem with th e 286 an d h igh er was th at wh en th ey were in real m od e, th ey were su p p osed to op erate th e sam e way, an d th e ad d ress sh ou ld wrap arou n d to th e begin n in g of th e first m egabyte also. Un fortu n ately, a “bu g” in th e ch ip left th e 21st ad d ress lin e active (called th e A20 lin e), wh ich allowed th e ad d ress to en d u p 16 bytes from th e en d of th e first 64K segm en t in th e secon d m egabyte. Th is m em ory was su p p osed to be ad d ressable on ly in p rotected m od e, bu t th is bu g allowed all bu t 16 bytes of th e first 64K of exten d ed m em ory to be ad d ressable in real m od e. Becau se th is bu g cau sed p roblem s with m an y real-m od e p rogram s th at relied on th e wrap to take p lace, wh en IBM en gin eers d esign ed th e AT, th ey h ad to fin d a way to

The System Logical M emory Layout

d isable th e A20 lin e wh ile in real m od e, bu t th en re-en able it wh en in p rotected m od e. Th ey d id th is by u sin g som e u n u sed p in s on th e 8042 keyboard con troller ch ip on th e m oth erboard . Th e 8042 keyboard con troller was d esign ed to accep t scan cod es from th e keyboard an d tran sm it th em to th e p rocessor, bu t th ere were u n u sed p in s n ot n eed ed strictly for th is fu n ction . So IBM cam e u p with a way to com m an d th e keyboard con troller to tu rn on an d off th e A20 lin e, th u s en ablin g th e “d efective” 286 to tru ly em u late an 8088 an d 8086 wh ile in real m od e. Microsoft realized th at you cou ld com m an d th e 8042 keyboard con troller to tu rn back on th e A20 lin e strictly for th e p u rp ose of u sin g th is “bu g” as a featu re, wh ich en abled you to access th e first 64K of exten d ed m em ory (less 16 bytes) with ou t h avin g to go th rou gh th e len gth y an d com p licated p rocess of switch in g in to p rotected m od e. Th u s, HIMEM.SYS an d th e High Mem ory Area was born ! HIMEM.SYS h as to watch th e system to see if th e A20 lin e sh ou ld be off for com p atibility, or on to en able access to th e HMA or wh ile in p rotected m od e. In essen ce, HIMEM becom es a con trol p rogram th at m an ip u lates th e A20 lin e th rou gh th e 8042 keyboard con troller ch ip . Expanded M em ory Som e old er p rogram s can u se a typ e of m em ory called Expanded Mem ory Specification or EMS m em ory. Un like con ven tion al (th e first m egabyte) or exten d ed (th e secon d th rou gh 16th or 4,096th m egabytes) m em ory, exp an d ed m em ory is not d irectly ad d ressable by th e p rocessor. In stead , it can on ly be accessed th rou gh a 64K win d ow an d sm all 16K p ages establish ed in th e UMA. Exp an d ed m em ory is a segm en t or ban k-switch in g sch em e in wh ich a cu stom m em ory ad ap ter h as a large n u m ber of 64K segm en ts on board , com bin ed with sp ecial switch in g an d m ap p in g h ard ware. Th e system u ses a free segm en t in th e UMA as th e h om e ad d ress for th e EMS board . After th is 64K is filled with d ata, th e board rotates th e filled segm en t ou t an d a n ew, em p ty segm en t ap p ears to take its p lace. In th is fash ion , you h ave a board th at can keep on rotatin g in n ew segm en ts to be filled with d ata. Becau se on ly on e segm en t can be seen or op erated on at on e tim e, EMS is very in efficien t for p rogram cod e an d is n orm ally on ly u sed for d ata. Figu re 5.22 sh ows h ow exp an d ed m em ory fits with con ven tion al an d exten d ed m em ory. In tel origin ally created a cu stom -p u rp ose m em ory board th at h ad th e n ecessary EMS ban k-switch in g h ard ware. Th ey called th ese board s Above Boards, an d th ey were wid ely sold m an y years ago. EMS was d esign ed with 8-bit system s in m in d an d was ap p rop riate for th em becau se th ey h ad n o cap ability to access exten d ed m em ory. 286 an d n ewer system s, h owever, p ossess th e cap ability to h ave 15 or m ore m egabytes of exten d ed m em ory, wh ich is m u ch m ore efficien t th an th e goofy (an d slow) ban k-switch in g EMS sch em e. Th e Above Board s are n o lon ger bein g m an u factu red , an d EMS m em ory—as a con cep t an d fu n ction ally—is extrem ely obsolete. If you h ave an y an tiq u e software th at still req u ires EMS m em ory, you are ad vised to u p grad e to n ewer version s th at can u se exten d ed m em ory d irectly. It is also p ossible to u se th e p owerfu l MMU of th e 386 an d h igh er p rocessors to con vert exten d ed m em ory to fu n ction like LIM EMS, bu t th is sh ou ld on ly be d on e if th ere is n o way to u se th e exten d ed m em ory d irectly. EMM386 can con vert exten d ed to exp an d ed , an d in fact was

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origin ally d esign ed for th is p u rp ose, alth ou gh tod ay it is m ore likely to be u sed to m ap exten d ed m em ory in to th e UMA for th e p u rp oses of load in g d rivers an d n ot for EMS. Th e EMM386 d river is in clu d ed with DOS version s 5 an d n ewer as well as with W in d ows. If you h ave several version s on h an d , as a ru le, always u se th e n ewest on e. Conventional and EXTENDED Memory

EXPANDED Memory 32M

16M/4G

EXTENDED Memory

EXPANDED Memory

Motherboard ROM BIOS

Divided into logical pages and Mapped into the EMS Window

1M

896K

EMS Window 832K Adapter ROM 768K

Video RAM

4 16K Pages (64K) of "bank switched" memory appear in the EMS Window usually at segment D000

640K Conventional (Base) Memory 512K

256K

0K

0K

FIG. 5.22 Con ven tion al, exten d ed , an d exp an d ed m em ory. Prevent ing ROM BIOS M em ory Conflict s and Overlap As d etailed in p reviou s section s, C000 an d D000 are reserved for u se by ad ap ter-board ROM an d RAM. If two ad ap ters h ave overlap p in g ROM or RAM ad d resses, u su ally n eith er board op erates p rop erly. Each board fu n ction s if you rem ove or d isable th e oth er on e, bu t th ey d o n ot work togeth er. W ith m an y ad ap ter board s, you can ch an ge th e actu al m em ory location s to be u sed with ju m p ers, switch es, or d river software, wh ich m igh t be n ecessary to allow two board s to coexist in on e system . Th is typ e of con flict can cau se p roblem s for trou blesh ooters. You m u st read th e d ocu m en tation for each ad ap ter to fin d ou t wh at m em ory ad d resses th e ad ap ter u ses an d h ow to ch an ge th e ad d resses to allow coexisten ce with an oth er ad ap ter.

The System Logical M emory Layout

Most of th e tim e, you can work arou n d th ese p roblem s by recon figu rin g th e board or ch an gin g ju m p ers, switch settin gs, or software-d river p aram eters. Th is ch an ge en ables th e two board s to coexist an d stay ou t of each oth er’s way. Ad d ition ally, you m u st en su re th at ad ap ter board s d o n ot u se th e sam e IRQ (In terru p t Req u est Lin e), DMA (d irect m em ory access) ch an n el, or I/ O Port ad d ress. You can easily avoid ad ap ter board m em ory, IRQ , DMA ch an n el, an d I/ O Port con flicts by creatin g a ch art or tem p late to m ock u p th e system con figu ration by p en cilin g on th e tem p late th e resou rces alread y u sed by each in stalled ad ap ter. You en d u p with a p ictu re of th e system resou rces an d th e relation sh ip of each ad ap ter to th e oth ers. Th is p roced u re h elp s you an ticip ate con flicts an d en su res th at you con figu re each ad ap ter board correctly th e first tim e. Th e tem p late also becom es im p ortan t d ocu m en tation wh en you con sid er n ew ad ap ter p u rch ases. New ad ap ters m u st be con figu rable to u se th e available resou rces in you r system . √√ See “ System Resources,” p. 270

If you r system h as Plu g-an d -Play cap abilities, an d you u se Pn P ad ap ters, it will be able to resolve con flicts between th e ad ap ters by m ovin g th e m em ory u sage on an y con flict. Un fortu n ately, th is rou tin e is n ot in telligen t an d still req u ires h u m an in terven tion —th at is, m an u al sp ecification of ad d resses in ord er to ach ieve th e m ost op tim u m location for th e ad ap ter m em ory. ROM Shadow ing Com p u ters based on th e 386 or h igh er CPU ch ip , wh ich p rovid es m em ory access on a 32- or 64-bit p ath , often u se a 16-bit d ata p ath for system ROM BIOS in form ation . In ad d ition , ad ap ter card s with on board BIOS m ay u se an 8-bit p ath to system m em ory. On th ese h igh -en d com p u ters, u sin g a 16- or 8-bit p ath to m em ory is a sign ifican t bottlen eck to system p erform an ce. In ad d ition to th ese p roblem s of wid th , m ost actu al ROM ch ip s are available in m axim u m sp eed s far less th an wh at is available for th e system ’s d yn am ic RAM. For exam p le, th e fastest ROMs available are gen erally 150n s to 200n s, wh ereas th e RAM in a m od ern system is rated at 60n s or faster in m ost cases. Becau se of th e fact th at ROM is so slow, an y system accesses to p rogram s or d ata in ROM cau se m an y ad d ition al wait states to be in serted . Th ese wait states can slow th e en tire system d own trem en d ou sly, esp ecially con sid erin g th at m an y of th e 16-bit d river p rogram s u sed con stan tly by DOS resid e in th e BIOS ch ip s fou n d on th e m oth erboard an d m an y of th e in stalled ad ap ters. Fortu n ately, a way was fou n d to tran sfer th e con ten ts of th e slow 8- or 16-bit ROM ch ip s in to m u ch faster 32-bit m ain m em ory. Th is is called shadowing the ROMs. Virtu ally all 386 an d h igh er system s en able you to u se wh at is term ed shadow m em ory for th e m oth erboard an d p ossibly som e ad ap ter ROMs as well. Sh ad owin g essen tially m oves th e p rogram m in g cod e from slow ROM ch ip s in to fast 32-bit system m em ory. Sh ad owin g slower ROMs by cop yin g th eir con ten ts in to RAM can greatly sp eed u p th ese BIOS rou tin es—som etim es m akin g th em fou r to five tim es faster.

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Sh ad owin g is accom p lish ed by u sin g th e p owerfu l MMU in th e 386 an d h igh er p rocessors. W ith th e ap p rop riate in stru ction s, th e MMU can take a cop y of th e ROM cod e, p lace it in RAM, an d en able th e RAM su ch th at it ap p ears to th e system in exactly th e sam e ad d resses at wh ich it was origin ally located . Th is actu ally d isables th e ROM ch ip s th em selves, wh ich are essen tially sh u t d own . Th e system RAM th at is n ow m asq u erad in g as ROM is fu lly write-p rotected so th at it acts in every way ju st like th e real ROM, with th e excep tion of bein g m u ch faster, of cou rse! Most system s h ave an op tion in th e system setu p to en able sh ad owin g for th e m oth erboard BIOS (u su ally segm en t F000) an d th e vid eo BIOS (u su ally th e first 32K of segm en t C000). Som e system s will go fu rth er an d offer you th e cap ability to en able or d isable sh ad owin g in in crem en ts (u su ally 16K) th rou gh ou t th e rem ain d er of th e C000 an d D000 segm en ts.

Not e The important thing to note about shadowing is that if you enable shadowing for a given set of addresses, anything found there when the system is booting will be copied to RAM and locked in place. If you were to do this to a memory range that had a network adapter’s shared memory mapped into it, the network card would cease to function. You must only shadow ranges that contain true ROM and no RAM .

Som e system s d o n ot offer sh ad owin g for areas oth er th an th e m oth erboard an d vid eo BIOS. In th ese system s, you can u se a m em ory m an ager su ch as EMM386 (wh ich com es with DOS an d W in d ows) to en able sh ad owin g for an y ran ge you sp ecify. It is p referable to u se th e system ’s own in tern al sh ad owin g cap abilities first becau se th e system sh ad owin g u ses m em ory th at wou ld oth erwise be d iscard ed . Usin g an extern al m em ory m an ager su ch as EMM386 for sh ad owin g costs you a sm all am ou n t of exten d ed m em ory, eq u al to th e am ou n t of sp ace you are sh ad owin g. If you en able sh ad owin g for a ran ge of ad d resses, an d on e or m ore ad ap ters or th e system in gen eral n o lon ger works p rop erly, you m ay h ave scratch p ad m em ory or oth er RAM with in th e sh ad owed area, wh ich is n ot accessible as lon g as th e sh ad owin g rem ain s active. In th is case, you sh ou ld d isable th e sh ad owin g for th e system to op erate p rop erly. If you can figu re ou t p recisely wh ich ad d resses are ROM an d wh ich are RAM with in th e Up p er Mem ory Area, you can selectively sh ad ow on ly th e ROM for m axim u m system p erform an ce. Note th at sh ad owin g ROMs is n ot very im p ortan t wh en ru n n in g a 32-bit op eratin g system su ch as W in 95/ 98 or NT. Th is is becau se th ose op eratin g system s on ly u se th e 16-bit BIOS d river cod e d u rin g bootin g; th en th ey load 32-bit rep lacem en t d rivers in to faster exten d ed m em ory an d u se th em . Th u s, sh ad owin g n orm ally on ly affects DOS or oth er 16-bit software an d op eratin g system s. Tot al Inst alled M em ory Versus Tot al Usable M em ory On e th in g th at m ost p eop le d on ’t realize is th at n ot all th e SIMM or oth er RAM m em ory you p u rch ase an d in stall in a system will be available. Becau se of som e q u irks in system d esign , th e system u su ally h as to “th row away” u p to 384K of RAM to m ake way for th e Up p er Mem ory Area.

The System Logical M emory Layout

For exam p le, m ost system s with 16M of RAM (wh ich is 16,384K) in stalled sh ow a total of on ly 16,000K in stalled d u rin g th e POST or wh en ru n n in g Setu p . Th is in d icates th at 16,384K–16,000K = 384K of m issin g m em ory! Som e system s m ay sh ow 16,256K with th e sam e 16M in stalled , wh ich works ou t to 16,384K–16,256K = 128K m issin g. If you ru n you r Setu p p rogram an d ch eck ou t you r base an d exten d ed m em ory valu es, you will fin d m ore in form ation th an ju st th e sin gle figu re for th e total sh own d u rin g th e POST. In m ost system s with 4,096K (4M), you h ave 640K base an d 3,072K exten d ed . In som e system s, Setu p rep orts 640K base an d 3,328K exten d ed m em ory, wh ich is a bon u s. In oth er word s, m ost system s com e u p 384K sh ort, bu t som e com e u p on ly 128K sh ort. Th is sh ortfall is n ot easy to exp lain , bu t it is con sisten t from system to system . Say th at you h ave a 486 system with two in stalled 72-p in (32-bit) 16M SIMMs. Th is resu lts in a total in stalled m em ory of 32M in two sep arate ban ks becau se th e p rocessor h as a 32-bit d ata bu s. Each SIMM is a sin gle ban k in th is system . Note th at m ost ch eap er 486 system s u se th e 30-p in (8-bit) SIMMs, of wh ich fou r are req u ired to m ake a sin gle ban k. Th e first ban k (or SIMM, in th is case) starts at ad d ress 0000000h (th e start of th e first m egabyte), an d th e secon d starts at 1000000 (th e start of th e 17 th m egabyte). On e of th e card in al ru les of m em ory is th at you absolu tely can n ot h ave two h ard ware d evices wired to th e sam e ad d ress. Th is m ean s th at 384K of th e first m em ory ban k in th is system wou ld be in d irect con flict with th e vid eo RAM (segm en ts A000 an d B000), an y ad ap ter card ROMs (segm en ts C000 an d D000), an d of cou rse th e m oth erboard ROM (segm en ts E000 an d F000). Th is m ean s th at all SIMM RAM th at occu p ies th ese ad d resses m u st be sh u t off or th e system will n ot fu n ction ! Actu ally, a m oth erboard d esign er can d o th ree th in gs with th e SIMM m em ory th at wou ld overlap from A0000-FFFFF: ■ Use th e faster RAM to h old a cop y of an y slow ROMs (sh ad owin g), d isablin g th e ROM in th e p rocess. ■ Tu rn off an y RAM n ot u sed for sh ad owin g, elim in atin g an y UMA con flicts. ■ Rem ap an y RAM n ot u sed for sh ad owin g, ad d in g to th e stack of cu rren tly in stalled exten d ed m em ory. Most system s sh ad ow th e m oth erboard ROM (u su ally 64K), th e vid eo ROM (32K), an d sim p ly tu rn off th e rest. Som e m oth erboard ROMs allow ad d ition al sh ad owin g to be selected between C8000-DFFFF, u su ally in 16K in crem en ts.

Not e You can only shadow ROM , never RAM , so if any card (such as a network card) has a RAM buffer in the C8000-DFFFF area, you must not shadow the RAM buffer addresses or the card will not function. For the same reason, you cannot shadow the A0000-BFFFF area because this is the video adapter RAM buffer.

Most m oth erboard s d o n ot d o an y rem ap p in g, wh ich m ean s th at an y of th e 384K n ot sh ad owed is sim p ly tu rn ed off. Th at is wh y en ablin g sh ad owin g d oes n ot seem to u se

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an y m em ory. Th e m em ory u sed for sh ad owin g wou ld oth erwise be d iscard ed in m ost system s. Th ese system s wou ld ap p ear to be sh ort by 384K com p ared to wh at is p h ysically in stalled in th e system . For exam p le, in a system with 32M, n o rem ap p in g wou ld resu lt in 640K of base m em ory an d 31,744K of exten d ed m em ory, for a total of 32,384K of u sable RAM—384K sh ort of th e total (32,768K–384K). Som e system s sh ad ow wh at th ey can an d th en rem ap an y segm en ts th at d o n ot h ave sh ad owin g in to exten d ed m em ory so as n ot to waste th e n on -sh ad owed RAM. PS/ 2 system s, for exam p le, sh ad ow th e m oth erboard BIOS area (E0000-FFFFF or 128K in th ese system s) an d rem ap th e rest of th e first ban k of SIMM m em ory (256K from A0000-DFFFF) to wh atever ad d ress follows th e last in stalled ban k.

Not e Note that most new systems don’t allow selecting ROM shadowing functions, nor do they do any remapping. These days, the small amount of memory gain just isn’t worth the trouble in system engineering and design to accomplish it.

In m y exam p le system with two 16M 32-bit SIMMs, th e 256K n ot u sed for sh ad owin g wou ld be rem ap p ed to 2000000-203FFFF, wh ich is th e start of th e 33rd m egabyte. Th is affects d iagn ostics becau se if you h ad an y m em ory error rep orted in th ose ad d resses (2000000-203FFFF), it wou ld in d icate a failu re in th e first SIMM, even th ou gh th e ad d resses p oin t to th e en d of in stalled exten d ed m em ory. Th e ad d resses from 10000001FFFFFF wou ld be in th e secon d SIMM, an d th e 640K base m em ory 0000000-009FFFF wou ld be back in th e first SIMM. As you can see, figu rin g ou t h ow th e SIMMs are m ap p ed in to th e system is n ot easy! Most system s th at d o rem ap p in g can on ly rem ap an en tire segm en t if n o sh ad owin g is goin g on with in it. Th e vid eo RAM area in segm en ts A000 an d B000 can n ever con tain sh ad owin g, so at least 128K can be rem ap p ed to th e top of in stalled exten d ed m em ory in an y system th at su p p orts rem ap p in g. Becau se m ost system s sh ad ow in segm en ts F000 (m oth erboard ROM) an d C000 (vid eo ROM), th ese two segm en ts can n ot be rem ap p ed . Th is leaves 256K m axim u m for rem ap p in g. An y system rem ap p in g th e fu ll 384K m u st n ot be sh ad owin g at all, wh ich wou ld slow d own th e system an d is n ot recom m en d ed . Sh ad owin g is always p referred over rem ap p in g, an d rem ap p in g wh at is n ot sh ad owed is d efin itely p referred over sim p ly tu rn in g off th e RAM. System s th at h ave 384K of “m issin g” m em ory d o n ot d o rem ap p in g. If you wan t to d eterm in e if you r system h as an y m issin g m em ory, all you n eed to kn ow are th ree th in gs. On e is th e total p h ysical m em ory actu ally in stalled . Th e oth er two item s can be d iscovered by ru n n in g you r Setu p p rogram . You wan t to kn ow th e total base an d exten d ed m em ory n u m bers recogn ized by th e system . Th en sim p ly su btract th e base an d exten d ed m em ory from th e total in stalled to d eterm in e th e m issin g m em ory. You will u su ally fin d th at you r system is “m issin g” 384K, bu t you m ay be lu cky an d h ave a system th at rem ap s 256K of wh at is m issin g an d th u s sh ows on ly 128K of m em ory m issin g.

The System Logical M emory Layout

Virtu ally all system s u se som e of th e m issin g m em ory for sh ad owin g ROMs, esp ecially th e m oth erboard an d vid eo BIOS, so wh at is m issin g is n ot com p letely wasted . System s “m issin g” 128K will fin d th at it is bein g u sed to sh ad ow you r m oth erboard BIOS (64K from F0000-FFFFF) an d vid eo BIOS (32K from C0000-C8000). Th e rem ain d er of segm en t C0000 (32K from C8000-CFFFF) is sim p ly bein g tu rn ed off. All oth er segm en ts (128K from A0000-BFFFF an d 128K from D0000-EFFFF) are bein g rem ap p ed to th e start of th e fifth m egabyte (400000-43FFFF). Most system s sim p ly d isable th ese rem ain in g segm en ts rath er th en take th e trou ble to rem ap th em . Rem ap p in g req u ires ad d ition al logic an d BIOS rou tin es to accom p lish , an d m an y m oth erboard d esign ers d o n ot feel th at it is worth th e effort to reclaim 256K.

Not e If your system is doing remapping, any errors reported near the end of installed extended memory are likely in the first bank of memory because that is where they are remapped from. The first bank in a 32-bit system would be constructed of either four 30-pin (8-bit) SIM M s or one 72-pin (32-bit) SIM M . The first bank in a 64-bit system would be constructed of either two 72-pin (32-bit) SIM M s or one 168-pin (64-bit) DIM M .

Adapt er M em ory Configurat ion and Opt im izat ion Id eally, all ad ap ter board s wou ld be Plu g-an d -Play d evices th at req u ire you to m erely p lu g th e ad ap ter in to a m oth erboard slot an d th en u se it. W ith th e n ew Plu g-an d -Play sp ecification , we are m ovin g toward th at goal. However, som etim es it alm ost seem s th at ad ap ter board s are d esign ed as if th ey were th e on ly ad ap ter likely to be p resen t on a system . Th ey u su ally req u ire you to kn ow th e u p p er m em ory ad d resses an d IRQ an d DMA ch an n els alread y on you r system , an d h ow to con figu re th e n ew ad ap ter so th at it d oes n ot con flict with you r alread y-in stalled ad ap ters. Ad ap ter board s u se u p p er m em ory for th eir BIOS an d as workin g RAM. If two board s attem p t to u se th e sam e BIOS area or RAM area of u p p er m em ory, a con flict occu rs th at can keep you r system from bootin g. Th e followin g section s cover ways to avoid th ese p oten tial con flicts an d h ow to trou blesh oot if th ey d o occu r. In ad d ition , th ese section s d iscu ss m ovin g ad ap ter m em ory to resolve con flicts an d p rovid e som e id eas on op tim izin g ad ap ter m em ory u se. How t o Det erm ine W hat Adapt ers Occupy t he UM A. You can d eterm in e wh at ad ap ters are u sin g sp ace in u p p er m em ory in th e followin g two ways: ■ Stu d y th e d ocu m en tation for each ad ap ter on you r system to d eterm in e th e m em ory ad d resses th ey u se. ■ Use a software u tility th at can q u ickly d eterm in e for you wh at u p p er m em ory areas you r ad ap ters are u sin g. Th e sim p lest way (alth ou gh by n o m ean s always th e m ost foolp roof) is to u se a software u tility to d eterm in e th e u p p er m em ory areas u sed by th e ad ap ters in stalled on you r system . On e su ch u tility, Microsoft Diagn ostics (MSD), com es with W in d ows 3.x an d DOS 6

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or h igh er version s. Th e Device Man ager u n d er System in th e W in d ows 95 Con trol Pan el also p rovid es th is in form ation , as d oes th e n ew System In form ation u tility th at com es with W in d ows 98. Th ese u tilities exam in e you r system con figu ration an d d eterm in e n ot on ly th e u p p er m em ory u sed by you r ad ap ters, bu t also th e IRQs u sed by each of th ese ad ap ters. Tru e Plu g-an d -Play system s will also sh u t d own on e of th e card s in volved in a con flict to p reven t a total system locku p . Th is m ay cau se W in d ows to boot in safe m od e. After you ru n MSD, Device Man ager, or an oth er u tility to d eterm in e you r system ’s u p p er m em ory con figu ration , m ake a p rin tou t of th e m em ory ad d resses u sed . Th ereafter, you can q u ickly refer to th e p rin tou t wh en you are ad d in g a n ew ad ap ter to en su re th at th e n ew board d oes n ot con flict with an y d evices alread y in stalled on you r system . M oving Adapt er M em ory t o Resolve Conflict s. After you id en tify a con flict or p oten tial con flict by stu d yin g th e d ocu m en tation for th e ad ap ter board s in stalled on you r system or u sin g a software d iagn ostic u tility to d eterm in e th e u p p er m em ory ad d resses u sed by you r ad ap ter board s, you m ay h ave to recon figu re on e or m ore of you r ad ap ters to m ove th e u p p er m em ory sp ace u sed by a p roblem ad ap ter. Most ad ap ter board s m ake m ovin g ad ap ter m em ory a som ewh at sim p le p rocess, en ablin g you to ch an ge a few ju m p ers or switch es to recon figu re th e board ; in Plu g-an d -Play card s, you can u se th e con figu ration p rogram th at com es with th e board or th e W in d ows Device Man ager to m ake th e ch an ges. Th e followin g step s h elp you resolve m ost con flicts th at arise becau se ad ap ter board s con flict with on e an oth er: 1. Determ in e th e u p p er m em ory ad d resses cu rren tly u sed by you r ad ap ter board s an d write th em d own . 2. Determ in e if an y of th ese ad d resses are overlap p in g, wh ich resu lts in a con flict. 3. Con su lt th e d ocu m en tation for you r ad ap ter board s to d eterm in e wh ich board s can be recon figu red so th at all ad ap ters h ave access to u n iq u e m em ory ad d resses. 4. Con figu re th e affected ad ap ter board s so th at n o con flict in m em ory ad d resses occu rs. For exam p le, if on e ad ap ter u ses th e u p p er m em ory ran ge C8000-CBFFF an d an oth er ad ap ter u ses th e ran ge CA000-CCFFF, you h ave a p oten tial ad d ress con flict. On e of th ese m u st be ch an ged . Note th at Plu g-an d -Play card s allow th ese ch an ges to be m ad e d irectly from th e W in d ows Device Man ager. Opt im izing Adapt er M em ory Use. On an id eal PC, ad ap ter board s wou ld always com e con figu red so th at th e u p p er m em ory ad d resses th ey u se im m ed iately follow th e u p p er m em ory ad d resses u sed by th e p reviou s ad ap ter, with n o overlap th at wou ld cau se con flicts. Su ch an u p p er m em ory arran gem en t wou ld n ot on ly be “clean ,” bu t wou ld m ake it m u ch m ore sim p le to u se available u p p er m em ory for load in g d evice d rivers an d m em ory-resid en t p rogram s. However, th is is n ot th e case. Ad ap ter board s often leave gap s of u n u sed m em ory between on e an oth er—th is is, of cou rse, p referable to an overlap , bu t still is n ot th e best u se of u p p er m em ory.

The System Logical M emory Layout

Som eon e wh o wan ted to m ake th e m ost of th eir u p p er m em ory m igh t con sid er stu d yin g th e d ocu m en tation for each ad ap ter board in stalled on h is or h er system to d eterm in e a way to com p act th e u p p er m em ory u sed by each of th ese d evices. For exam p le, if it were p ossible on a p articu lar system u sin g th e ad ap ters in stalled on it, th e u se of u p p er m em ory cou ld be m ore sim p le if you con figu red you r ad ap ter board s so th at th e blocks of m em ory th ey u se fit togeth er like bricks in a wall, rath er th an like a slice of Swiss ch eese, as is th e case on m ost system s. Th e m ore you can red u ce you r free u p p er m em ory to as few con tigu ou s ch u n ks as p ossible, th e m ore com p letely an d efficien tly you can take ad van tage of th e UMA. Mem ory op tim ization in th is m an n er is n ot really n ecessary if you are ru n n in g 32-bit d rivers as you wou ld in a n orm al W in 95/ 98 or NT system . Th is is m ostly u sefu l for ru n n in g old er DOS ap p lication s, gam es, an d so on . Taking Advant age of Unused Upper M em ory On system s u sin g an old er 16-bit op eratin g system su ch as W in d ows 3.1 or DOS, m em ory-resid en t p rogram s an d d evice d rivers can be m oved in to th e UMA by u sin g a m em ory m an ager su ch as th e MEMMAKER u tility or som e oth er afterm arket u tility. Th ese m em ory m an agem en t u tilities exam in e th e m em ory-resid en t p rogram s an d d evice d rivers in stalled on you r system , d eterm in e th eir m em ory n eed s, an d th en calcu late th e best way to m ove th ese d rivers an d p rogram s in to u p p er m em ory, th u s freein g th e con ven tion al m em ory th ey u sed . Usin g MEMMAKER is q u ite sim p le. Make a backu p of you r CONFIG.SYS an d AUTOEXEC.BAT files so th at you h ave u sable cop ies if you n eed th em to restore you r system con figu ration ; th en ru n MEMMAKER from th e DOS p rom p t. MEMMAKER will in stall req u ired d evice d rivers in you r CONFIG.SYS file, an d th en begin op tim izin g you r m em ory con figu ration . It d oes a d ecen t job of freein g u p con ven tion al m em ory; h owever, with carefu l fin e-tu n in g, an in d ivid u al can p erform feats of m em ory m an agem en t u sin g on ly th e raw DOS HIMEM.SYS an d EMM386.EXE d rivers th at n o au tom atic p rogram can d o. On ly d river p rogram s th at ru n in th e p rocessor’s real m od e m u st be load ed with in th e first m egabyte of m em ory. Becau se real-m od e d rivers are m ad e u p of 16-bit real m od e p rogram cod e, th ey can n ot resid e in exten d ed m em ory, becau se on ly th e first m egabyte (base m em ory) is accessible wh en in real m od e. DOS an d W in d ows 3.x are 16-bit p rogram s an d u tilize d rivers th at ru n in real m od e, h en ce th e n eed for th e base m em ory op tim ization . W ith th e n u m ber of d rivers th at p eop le are u sin g tod ay, it can be d ifficu lt to fit th em all in th e available UMA sp ace wh ile leavin g en ou gh base m em ory free to ru n ap p lication s. Th in gs are d ifferen t with th e n ewer op eratin g system s. W in d ows 95/ 98, for exam p le, u ses p rim arily 32-bit p rotected m od e d rivers an d p rogram cod e, alth ou gh th ere is still som e 16-bit real-m od e p rogram cod e left. W in d ows NT an d OS/ 2 are fu ll 32-bit op eratin g system s, an d all th eir d rivers an d ap p lication s are m ad e u p of 32-bit p rotected m od e in stru ction cod e. If you are u sin g all 32-bit p rogram s, th en virtu ally n o m em ory op tim ization is n ecessary in th e first m egabyte, as 32-bit p rogram s are free to ru n in exten d ed m em ory.

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Th e followin g section s cover u sin g m em ory-m an agem en t software to op tim ize con ven tion al m em ory, an d ad d ition al ways to con figu re you r system m em ory to m ake you r system ru n as efficien tly as p ossible. It is im p ortan t to n ote th at th e DOS HIMEM.SYS an d EMM386.EXE p lay an in tegral role in MEMMAKER’s cap ability to m ove d evice d rivers an d m em ory-resid en t p rogram s in to u p p er m em ory. Th e n ext two section s d escribe u sin g HIMEM.SYS an d EMM386.EXE to con figu re exten d ed an d exp an d ed m em ory.

Not e If you are running older 16-bit DOS applications under Windows 95, Windows NT, or OS/ 2, then you still need to know about base memory optimization. In these cases, you will be running the application in a DOS window, which, using the virtual real mode of the processor, can emulate the first megabyte of real-mode workspace. Using these 32-bit operating systems, you can customize how the application running in the DOS window sees the system, and how the system memory appears to be organized.

Using HIM EM .SYS ( DOS) . Th e DOS d evice d river HIMEM.SYS, wh ich h as been in clu d ed with W in d ows an d DOS 4.0 an d h igh er, is u sed to con figu re exten d ed m em ory to th e XMS sp ecification , as well as to en able th e u se of th e first 64K of exten d ed m em ory as th e h igh m em ory area (HMA). HIMEM.SYS is in stalled by ad d in g a lin e in vokin g th e d evice d river to you r CONFIG.SYS file. Using EM M 386.EXE ( DOS) . Th e p rogram EMM386.EXE, wh ich is in clu d ed with DOS 5.0 an d h igh er, is u sed p rim arily to m ap XMS m em ory (exten d ed m em ory m an aged by HIMEM.SYS) in to u n u sed region s of th e UMA. Th is allows p rogram s to be load ed in to th ese region s for u se u n d er DOS. EMM386 also h as a secon d ary fu n ction of u sin g XMS m em ory to em u late EMS version 4 m em ory, wh ich can th en be u sed by p rogram s th at n eed exp an d ed m em ory. For m ore in form ation on u sin g EMM386.EXE, refer to Qu e’s Special Edition Using MS-DOS 6.2 or you r DOS m an u al. M S-DOS 6.x M EM M AKER. If you still ru n DOS ap p lication s an d gam es th at ru n in DOS, you can in crease th e am ou n t of con ven tion al m em ory available to software ru n n in g in DOS on system s based on th e 386 ch ip an d above by ru n n in g th e MS DOS 6.x u tility MEMMAKER. DOS 5 h ad th e cap ability, u sin g EMM386, to m ap exten d ed m em ory in to th e UMA so th at DOS cou ld load m em ory-resid en t p rogram s an d d rivers in to th e UMA. Un fortu n ately, th is req u ired an exten sive kn owled ge of th e u p p er m em ory con figu ration of a p articu lar system , an d trial an d error to see wh at p rogram s cou ld fit in to th e available free region s. Th is p rocess was d ifficu lt en ou gh th at m an y p eop le were n ot effectively u sin g th eir m em ory u n d er DOS (an d W in d ows). To m ake th in gs easier, wh en DOS 6 was released , Microsoft in clu d ed a m en u -d riven p rogram called MEMMAKER th at d eterm in es th e system con figu ration , au tom atically creates th e p rop er EMM386 statem en ts, an d in serts th em in to th e CONFIG.SYS file. By m an ip u latin g th e UMA m an u ally or th rou gh MEMMAKER an d load in g d evice d rivers an d m em ory-resid en t p rogram s in to u p p er m em ory, you can h ave m ore th an 600K of free con ven tion al m em ory.

The System Logical M emory Layout

Over th e cou rse of m on th s or years of u se, th e in stallation p rogram s for variou s software u tilities often in stall so m an y m em ory-resid en t p rogram s an d d evice d rivers in you r AUTOEXEC.BAT an d CONFIG.SYS files th at you h ave too little con ven tion al m em ory left to start all th e p rogram s you wan t to ru n . You m ay wan t to u se MEMMAKER to free u p m ore con ven tion al m em ory for you r p rogram s. You can get h elp on MEMMAKER by typ in g H ELP MEMMAKER at th e DOS p rom p t. W h en you ru n th e MEMMAKER u tility, it au tom atically p erform s th e followin g fu n ction s to free u p m ore m em ory: ■ Moves a p ortion of th e DOS kern el in to th e HMA. ■ Map s free XMS m em ory in to u n u sed region s in th e UMA as UMBs, in to wh ich DOS can th en load d evice d rivers an d m em ory-resid en t p rogram s to free u p th e con ven tion al m em ory th ese d rivers an d p rogram s oth erwise u se. ■ Mod ifies CONFIG.SYS an d AUTOEXEC.BAT to cau se DOS to load m em ory-resid en t p rogram s an d d evice d rivers in to UMBs. Before ru n n in g MEMMAKER, carefu lly exam in e you r CONFIG.SYS an d AUTOEXEC.BAT files to id en tify u n n ecessary d evice d rivers an d m em ory-resid en t p rogram s. For exam p le, th e DOS d evice d river ANSI.SYS is often load ed in CONFIG.SYS to en able you to u se color an d oth er attribu tes at th e DOS p rom p t an d to rem ap th e keys on you r keyboard . If you are p rim arily a W in d ows u ser an d d o n ot sp en d m u ch tim e at th e DOS p rom p t, you can elim in ate ANSI.SYS from you r CONFIG.SYS file to free u p th e m em ory th e d river is u sin g.

Tip SETVER is another often-loaded driver that most people don’t need. If you don’t run utilities or programs that require a specific version of DOS, you can remove SETVER from your CONFIG.SYS file.

After you strip d own CONFIG.SYS an d AUTOEXEC.BAT to th eir bare essen tials (it is ad visable to m ake backu p cop ies first), you are read y to ru n MEMMAKER to op tim ize you r system m em ory. To ru n MEMMAKER, follow th ese step s: 1. Exit from an y oth er p rogram s you are ru n n in g. 2. Start you r n etwork or an y m em ory-resid en t p rogram s an d d evice d rivers you absolu tely n eed . 3. At th e DOS p rom p t, typ e MEMMAKER. Th e MEMMAKER setu p ru n s in two m od es—Exp ress an d Cu stom . Exp ress setu p is p referable for u sers wh o wan t to en able MEMMAKER to load d evice d rivers an d m em oryresid en t p rogram s in to h igh m em ory with th e m in im u m am ou n t of u ser in p u t, u n less th ey h ave an EGA or VGA (bu t n ot a Su p er VGA) m on itor. If you h ave an EGA or VGA m on itor, ch oose Cu stom Setu p an d an swer Yes in th e ad van ced op tion s screen wh ere it asks wh eth er MEMMAKER sh ou ld u se m on och rom e region (B0000-B7FFF) for ru n n in g p rogram s. Use th e d efau lts for th e rest of th e op tion s in Cu stom setu p u n less you are su re

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th at on e of th e d efau lts is n ot correct for you r system . Cu stom setu p is p robably n ot a good id ea u n less you are kn owled geable abou t op tim izin g system m em ory, p articu lar d evice d rivers, an d m em ory-resid en t p rogram s on th e system . W h en MEMMAKER fin ish es op tim izin g th e system m em ory, th e followin g th ree lin es are ad d ed to CONFIG.SYS: DEVICE=C:\DOS\HIMEM.SYS DEVICE=C:\DOS\EMM386.E XE NOEMS DOS=HIGH,UMB

In ad d ition , MEMMAKER m od ifies each lin e in CONFIG.SYS an d AUTOEXEC.BAT th at load s a d evice d river or m em ory-resid en t p rogram n ow bein g load ed in to UMBs. Variou s DEVICE= lin es in you r CONFIG.SYS are ch an ged to DEVICEHIGH=, an d variou s lin es in you r AUTOEXEC.BAT h ave th e LH (Load High ) com m an d in serted in fron t of th em . For exam p le, th e lin e DEVICE=ANSI.SYS is ch an ged to DEVICEHIGH=ANSI.SYS. In you r AUTOEXEC.BAT, lin es su ch as C:\DOS\DOSKEY are ch an ged to LH C:\DOS\DOSKEY. Th e DEVICEHIGH an d LH com m an d s load th e d evice d rivers an d m em ory-resid en t p rogram s in to UMBs. MEMMAKER also ad d s cod es to sp ecify wh ere in u p p er m em ory each p rogram will be load ed . For exam p le, after you ru n MEMMAKER, a statem en t like th is m igh t be ad d ed to you r AUTOEXEC.BAT: LH /L:1 C:\DOS\DOSKEY

Th e /L:1 cau ses th e resid en t p rogram DOSKEY to load in to th e first UMB region . On m an y system s, MEMMAKER con figu res th e system to free u p 620K of con ven tion al m em ory.

Chapter 6

6

Power Supply and Case

Th e p ower su p p ly is a critical com p on en t in a PC becau se it su p p lies electrical p ower to every system com p on en t th at n eed s it. In m y exp erien ce, it is also on e of th e m ost failu re-p ron e com p on en ts in an y com p u ter system . A m alfu n ction in g p ower su p p ly can d am age th e oth er com p on en ts in you r com p u ter by d eliverin g an im p rop er or erratic voltage. Becau se of its im p ortan ce to p rop er an d reliable system op eration , you sh ou ld u n d erstan d both th e fu n ction an d lim itation s of a p ower su p p ly, as well as its p oten tial p roblem s an d th eir solu tion s.

Pow er Supply Funct ion and Operat ion Th e basic fu n ction of th e p ower su p p ly is to con vert th e typ e of electrical p ower available at th e wall socket to th e typ e th e com p u ter circu itry can u se. Th e p ower su p p ly in a con ven tion al d esktop system is d esign ed to con vert th e Am erican 120-volt, 60Hz, AC cu rren t in to +3.3v, +5v, an d +12v DC cu rren t. Usu ally, th e d igital electron ic com p on en ts an d circu its in th e system (m oth erboard , ad ap ter card s, an d d isk d rive logic board s) u se th e +3.3v or +5v p ower, an d th e m otors (d isk d rive m otors an d an y fan s) u se th e +12v p ower. Th e p ower su p p ly m u st d eliver a good , stead y su p p ly of DC cu rren t so th at th e system can op erate p rop erly. If you look at a sp ecification sh eet for a typ ical PC p ower su p p ly, you can see th at th e su p p ly gen erates n ot on ly +3.3v, +5v, an d +12v, bu t also –5v an d –12v. Th e p ositive voltages seem in gly p ower everyth in g in th e system (logic an d m otors), so wh at are th e n egative voltages u sed for? Th e an swer is, n ot m u ch ! Th ese ad d ition al n egative voltages are n ot u sed at all in m an y m od ern system s, alth ou gh th ey are still req u ired for backward com p atibility. Becau se th e +3.3v sign al is a relatively recen t ad d ition , p ower su p p lies d o n ot gen erate a –3.3v sign al DC cu rren t.

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Not e When Intel began releasing processors that required a +3.3v power source, power supplies that supplied the additional output voltage were not yet available. As a result, motherboard manufacturers began adding voltage regulators to their products, which convert +5v current to +3.3v. Voltage regulators, however, also generate a lot of heat, which should always be avoided in a PC. Now that you can obtain power supplies and motherboards designed to supply and use +3.3v, you should not have to purchase a system that converts voltages on the motherboard.

√√ See “ CPU Operating Voltages,” p. 72

Alth ou gh –5v an d –12v are su p p lied to th e m oth erboard via th e p ower su p p ly con n ectors, th e m oth erboard u ses on ly th e +5v. Th e –5v sign al is sim p ly rou ted to th e ISA bu s on p in B5. Th e m oth erboard d oes n ot u se it. Origin ally, th e an alog d ata sep arator circu its fou n d in old er flop p y con trollers u sed –5v, so it was su p p lied to th e bu s. Becau se m od ern con trollers d o n ot n eed th e –5v, system s n o lon ger u se it. It is still req u ired , h owever, becau se it is p art of th e ISA bu s stan d ard .

Not e Power supplies in systems with a M icro Channel Architecture (M CA bus) do not have –5v. This power signal was never needed in these systems because they always used a more modern floppy controller design. IBM no longer uses the M CA bus in its PCs, but you may encounter it on legacy systems. Also, certain PCI-only systems are now being produced that do not need –5v current.

Th e m oth erboard logic d oesn ’t u se th e +12v an d –12v sign als eith er. Th ey are rou ted to p in s B9 an d B7 of th e ISA bu s (resp ectively). An y ad ap ter card on th e bu s can m ake u se of th ese voltages if n eed ed , bu t typ ically th ey are u sed by serial p ort d river/ receiver circu its. If th e m oth erboard h as in tegrated serial p orts, th en it m ay u se th e +12v an d –12v sign als for th ose p orts.

Not e The load placed on the +12v and –12v signals by a serial port is very small. For example, the PS/ 2 Dual Async adapter uses only 35mA of +12v and 35mA of –12v (0.035 amps each) to operate two ports.

Most n ewer serial p ort circu its n o lon ger u se 12v d river/ receiver circu its. In stead , th ey n ow u se circu its th at ru n on on ly +3.3 or +5v. If you h ave serial p orts su ch as th ese in you r system , th e –12v sign al from you r p ower su p p ly will p robably n ot be u sed . Th e m ain fu n ction of th e +12v p ower is to ru n d isk d rive m otors. Usu ally, a large am ou n t of cu rren t is available, esp ecially in system s with a large n u m ber of d rive bays (su ch as in a tower con figu ration ). Besid es d isk d rive m otors, th e +12v su p p ly is u sed by an y coolin g fan s in th e system —wh ich , of cou rse, sh ou ld always be ru n n in g. A sin gle

Power Supply Function and Operation

coolin g fan can d raw between 100m A an d 250m A (0.1 to 0.25 am p s); h owever, m ost n ewer fan s u se th e lower 100m A figu re. Note th at alth ou gh m ost fan s in d esktop system s ru n on +12v, p ort-able system s m ay u se fan s th at ru n on +5v, or even +3.3v. In ad d ition to su p p lyin g p ower to ru n th e system , th e p ower su p p ly also en su res th at th e system d oes n ot ru n u n less th e p ower su p p lied is su fficien t to op erate th e system p rop erly. In oth er word s, th e p ower su p p ly actu ally p reven ts th e com p u ter from startin g u p or op eratin g u n til all th e correct p ower levels are p resen t. Each p ower su p p ly com p letes in tern al ch ecks an d tests before allowin g th e system to start. If th e tests are su ccessfu l, th e p ower su p p ly sen d s a sp ecial sign al to th e m oth erboard called Power_Good. If th is sign al is n ot p resen t con tin u ou sly, th e com p u ter d oes n ot ru n . Th erefore, wh en th e AC voltage d ip s an d th e p ower su p p ly becom es overstressed or overh eated , th e Power_Good sign al goes d own an d forces a system reset or com p lete sh u td own . If you h ave ever worked on a system th at seem s d ead wh en th e p ower switch is on an d th e fan an d h ard d isks are ru n n in g, you kn ow th e effects of losin g th e Power_Good sign al. IBM origin ally im p lem en ted th is con servative d esign so th at th e com p u ter wou ld n ot op erate if th e p ower becam e low or th e su p p ly, overh eated or overstressed , cau sed ou tp u t p ower to falter.

Not e You even can use the Power_Good feature as a method of designing and implementing a reset switch for the PC. The Power_Good line is wired to the clock generator circuit, which controls the clock and reset lines to the microprocessor. When you ground the Power_Good line with a switch, the chip and related circuitry stop the processor. They do so by killing the clock signal and then resetting the processor when the Power_Good signal appears after you release the switch. The result is a full hardware reset of the system. Later in this chapter, you can find instructions for installing such a reset switch in a system not already equipped with one.

System s with n ewer m oth erboard form factors, su ch as th e ATX an d th e LPX, in clu d e an oth er sp ecial sign al. Th is featu re, called PS_ON, can be u sed to tu rn th e p ower su p p ly (an d th u s th e system ) off via software. It is som etim es kn own as th e soft-off feature. PS_ON is m ost evid en t wh en you u se it with an op eratin g system th at su p p orts th e Ad van ced Power Man agem en t (APM) stan d ard su ch as W in d ows 9x. W h en you select th e Sh u t Down th e Com p u ter op tion from th e Start m en u , th e p ower su p p ly soft-offs—th at is, W in d ows au tom atically tu rn s th e com p u ter com p letely off after it com p letes th e OS sh u td own seq u en ce. A system with ou t th is featu re on ly d isp lays a m essage th at it’s safe to sh u t d own th e com p u ter. Pow er Supply Form Fact ors Th e sh ap e an d gen eral p h ysical layou t of a com p on en t is called th e form factor. Item s th at sh are a form factor are gen erally in terch an geable, at least as far as th eir size is con cern ed . W h en d esign in g a PC, th e en gin eers can ch oose to u se on e of th e p op u lar stan d ard PSU (p ower su p p ly u n it) form factors, or th ey can elect to bu ild th eir own .

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Ch oosin g th e form er m ean s th at a virtu ally in exh au stible su p p ly of in exp en sive rep lacem en t p arts will be available in a variety of q u ality an d p ower ou tp u t levels. Goin g th e cu stom rou te m ean s ad d ition al tim e an d exp en se for d evelop m en t. In ad d ition , th e PSU will be u n iq u e to th e system an d available on ly from th e origin al m an u factu rer. If you can ’t tell alread y, I am a fan of th e in d u stry-stan d ard form factors! In th e early d ays of PCs, th e com p u ter in d u stry was d om in ated by com p an ies—su ch as IBM—th at m an u factu red m ost of th eir own p rop rietary com p on en ts. W h en oth er m an u factu rers began to “clon e” PCs on a large scale, th is p h ilosop h y becam e in creasin gly im p ractical. Th e d rive toward th e stan d ard ization of PC com p on en ts, wh ich began at th at tim e, con tin u es tod ay. Un til th e in trod u ction of In tel’s ATX arch itectu re in 1995, th e form factors of th e p ower su p p lies u sed in PC system s d iffered p rim arily in th eir size an d th eir orien tation in th e com p u ter case. ATX an d related stan d ard s in trod u ced som e n ew featu res (su ch as th e PS_ON sign al), bu t virtu ally all th e p ower su p p lies u sed in PCs n ow con form to th e sam e basic electron ic d esign . Tech n ically, th e PSU in you r PC is d escribed as a constant voltage half-bridge forward converting switching power supply. Constant voltage m ean s th at th e PSU p u ts ou t th e sam e voltage to th e com p u ter’s in tern al com p on en ts, n o m atter wh at th e voltage of AC cu rren t ru n n in g it or th e cap acity (wattage) of th e p ower su p p ly. Half-bridge forward converting refers to th e PSU’s switch in g d esign an d its p ower regu lation tech n iq u e. Th is typ e of p ower su p p ly is som etim es kn own as a switching supply. Com p ared to oth er typ es of p ower su p p lies, th is d esign p rovid es an efficien t p ower sou rce an d gen erates a m in im u m am ou n t of h eat. It also m ain tain s a sm all size an d a low p rice.

Not e Although two power supplies may share the same basic design and form factor, they can differ greatly in quality and efficiency. Later in this chapter, you’ll learn about some of the features and specifications to look for when evaluating PC power supplies.

Cu rren tly, eigh t p ower su p p ly form factors can be called industry standard. Th ese d ifferen t form factors are as follows: PC/ XT style

LPX style

AT/ Desk style

ATX style

AT/ Tower style

NLX style

Baby AT style

SFX style

Each of th ese p ower su p p ly typ es is available in n u m erou s d ifferen t con figu ration s an d p ower ou tp u t levels. Th e n ew PCs on th e m arket tod ay gen erally u se th e ATX or Min istyle p ower su p p ly. Th e earlier form factors are largely obsolete, an d th e NLX an d SFX styles are on ly ju st begin n in g to gain p op u larity in n ew system s.

Power Supply Function and Operation

√√ See “ M otherboard Form Factors,” p. 167

PC/ XT St yle. IBM’s XT u sed th e sam e basic p ower su p p ly sh ap e as th e origin al PC, excep t th at th e n ew XT su p p ly h ad m ore th an d ou ble th e p ower ou tp u t cap ability. Becau se th ey were id en tical in both extern al ap p earan ce an d in th e typ e of con n ectors th ey u sed , you cou ld easily in stall th e better XT su p p ly as an u p grad e for a PC system . Th e trem en d ou s p op u larity of th e origin al PC an d XT d esign led a n u m ber of m an u factu rers to begin bu ild in g system s th at m im icked th eir sh ap e an d layou t. Th ese clones, as th ey h ave been called , cou ld in terch an ge virtu ally all com p on en ts with th e IBM system s, in clu d in g th e p ower su p p ly. Nu m erou s m an u factu rers th en began p rod u cin g th ese com p on en ts. Most of th ese com p on en ts follow th e form factor of on e or m ore IBM system s. Th e PC/ XT p ower su p p ly an d con n ectors are sh own in Figu re 6.1. +5V G

48 mm

G +12V

ON

+5V G G +12V

120 mm OFF

+5V G G +12V

142 mm 10

190 mm

10

+5V G G +12V

12 mm

+5V +5V +5V -5V G G

120 mm 100 mm

8 mm 20 mm 12

210 mm 222 mm

G G -12V +12V N.C. P.G.

FIG. 6.1 PC/ XT form factor p ower su p p ly. AT/ Desk St yle. Th e AT d esktop system , in trod u ced by IBM after th e XT, h ad a larger p ower su p p ly an d a d ifferen t form factor th an th e origin al PC/ XT. Th is system , wh ich was rap id ly clon ed , rep resen ted th e basis for m an y IBM-com p atible d esign s. Th e p ower

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su p p ly u sed in th ese system s was called th e AT/Desktop-style power supply (see Figu re 6.2). Hu n d red s of m an u factu rers began m akin g m oth erboard s, p ower su p p lies, cases, an d oth er com p on en ts th at were p h ysically in terch an geable with th e origin al IBM AT.

+5V G G +12V

+5V ON

G G +12V

150mm OFF

+5V G G +12V

150mm

189mm

8

13mm

16

+

+5V G G +12V

+ +5V G G +12V

150mm 131mm

P.G. +5V +12V -12V G G

28mm 35mm

+

6mm 6

+ 16mm

144mm 213mm

7mm 47mm

G G -5V +5V +5V +5V

8.35"x5.9"x5.9"

FIG. 6.2 AT/ Desktop form factor p ower su p p ly. AT/ Tow er St yle. Th e early PC-com p atible m arket cam e u p with som e oth er variation s on th e AT th em e th at becam e q u ite p op u lar. Th e AT/Tower configuration was basically a fu ll-sized AT-style d esktop system ru n n in g on its sid e. Th e p ower su p p ly an d m oth erboard form factors were largely th e sam e in th e tower system as th ey were in th e d esktop . Th e tower con figu ration is n ot n ew; in fact, even IBM’s origin al AT h ad a sp ecially m ou n ted logo th at cou ld be rotated wh en you ran th e system on its sid e in th e tower con figu ration . Th e typ e of p ower su p p ly u sed in a tower system is id en tical to th at u sed in a d esktop system , excep t for th e location of th e p ower switch . On m ost AT/ Desktop system s, th e p ower switch is located on th e p ower su p p ly (u su ally in th e form of a large toggle switch ). Most AT/ Tower system s u se an extern al switch attach ed to th e p ower su p p ly th rou gh a sh ort fou r-wire cable. A fu ll-sized AT p ower su p p ly with a rem ote switch is called an AT/Tower form factor power supply (see Figu re 6.3).

Power Supply Function and Operation

+5V G G +12V

+5V G G +12V

150mm

+5V G G +12V

150mm

189mm

8

16

+5V G G +12V

13mm

+

+ +5V G G +12V

P.G. +5V +12V -12V G G

150mm 131mm

28mm 35mm

+

6mm 6

+ 16mm

144mm 213mm

7mm 47mm

G G -5V +5V +5V +5V

8.35"x5.9"x5.9"

FIG. 6.3 AT/ Tower form factor p ower su p p ly. Baby AT St yle. An oth er typ e of AT-based form factor is th e so-called Baby AT, wh ich is a sh orten ed version of th e fu ll-sized AT system . Th e p ower su p p ly in th ese system s is sh orten ed in on e d im en sion bu t m atch es th e AT d esign in all oth er resp ects. Baby AT– style p ower su p p lies can fit in to both a Baby AT ch assis an d th e larger AT-style ch assis; h owever, th e fu ll-sized AT/ Tower p ower su p p ly d oes n ot fit in th e Baby AT ch assis (see Figu re 6.4). Becau se th e Baby AT PSU p erform ed all th e sam e fu n ction s as th e AT-style p ower su p p ly, bu t was in a sm aller p ackage, it becam e th e p referred form factor u n til overtaken by later d esign s. LPX St yle. Th e n ext PSU form factor to gain p op u larity was th e LPX style, also called th e m ini an d th e slim line (see Figu re 6.5). LPX system s are d esign ed to h ave a sm aller footp rin t an d a lower h eigh t th an AT-sized system s. Th ese com p u ters u se a d ifferen t m oth erboard con figu ration th at m ou n ts th e exp an sion bu s slots on a “riser” card th at p lu gs in to th e m oth erboard . Th e exp an sion card s p lu g in to th is riser an d are m ou n ted sid eways in th e system , p arallel to th e m oth erboard . Becau se of its sm aller case, an LPX system n eed s a sm aller p ower su p p ly. Th e PSU d esign ed for LPX system s is sm aller th an th e Baby AT style in every d im en sion an d takes u p less th an h alf th e sp ace of its p red ecessor.

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+5V G G +12V

+5V ON

G G +12V

150mm OFF

+5V G G +12V +5V G

150mm

G 10 13mm

150mm

+

5

+12V

+ +5V G G +12V

150mm

131mm P.G. +5V +12V -12V

+

6mm 8

+ 144mm 165mm

G G

15 G G -5V +5V +5V +5V

6.5"x5.9"x5.9"

FIG. 6.4 Baby AT form factor p ower su p p ly. As with th e Baby AT d esign in its tim e, th e LPX p ower su p p ly d oes th e sam e job as its p red ecessor, bu t com es in a sm aller p ackage. Th e LPX p ower su p p ly q u ickly fou n d its way in to m an y m an u factu rers’ system s, soon becom in g a de facto stan d ard . It is still u sed in m an y of th e PCs p rod u ced tod ay, even in fu ll-sized d esktop an d tower cases th at can accep t a larger form factor. On ly in th e last two years h as th e p op u larity of LPX been seriou sly ch allen ged by th e in creasin g accep tan ce of th e ATX d esign . ATX St yle. On e of th e n ewer stan d ard s in th e in d u stry tod ay is th e ATX form factor (see Figu re 6.6). Th e ATX sp ecification , n ow in version 2.01, d efin es a n ew m oth erboard sh ap e, as well as a n ew case an d p ower su p p ly form factor. Th e ATX p ower su p p ly is based on th e LPX d esign , bu t its d ifferen ces are worth n otin g. On e d ifferen ce is th at th e ATX sp ecification origin ally called for th e fan to be m ou n ted alon g th e in n er sid e of th e su p p ly, wh ere it cou ld blow air across th e m oth erboard an d d raw it in from ou tsid e th e case at th e rear. Th is kin d of airflow ru n s in th e op p osite d irection as m ost stan d ard su p p lies, wh ich blow air ou t th e back of th e su p p ly th rou gh a h ole in th e case wh ere th e fan p rotru d es. Th e reverse-flow coolin g p rovid ed by th e ATX d esign forces air over th e h ottest com p on en ts of th e board , su ch as th e p rocessor, m em ory m od u les, an d exp an sion slots, wh ich are located in su ch a way as to take

Power Supply Function and Operation

m axim u m ad van tage of th e airflow. Th is elim in ates th e n eed for m u ltip le fan s in th e system —in clu d in g th e CPU fan s com m on in m an y system s tod ay—th e am ou n t of n oise p rod u ced by th e system , an d th e am ou n t of p ower n eed ed to ru n th e system . +5V G G +12V

+5V G G +12V 86mm +5V G G +12V +5V G

140mm

G 138mm

5

+

6mm

+12V

7

+

P.G. +5V +12V -12V

86mm

64mm

G G

+

G

+

16mm

6

G -5V +5V

5

115mm 150mm

30mm

+5V +5V

5.9"x5.5"x3.4"

FIG. 6.5 LPX form factor p ower su p p ly. An oth er ben efit of th e reverse-flow coolin g is th at th e system rem ain s clean er, free from d u st an d d irt. Th e case is essen tially p ressu rized , so air is con tin u ally forced ou t of th e cracks in th e case—th e op p osite of wh at h ap p en s with earlier d esign s. For th is reason , th e reverse-flow coolin g d esign is often referred to as a positive-pressure-ventilation d esign . For exam p le, if you h eld a lit cigarette in fron t of you r flop p y d rive on a n orm al system , th e sm oke wou ld be su cked in th rou gh th e fron t of th e d rive an d cou ld con tam in ate th e h ead s. On an ATX system with reverse-flow coolin g, th e sm oke wou ld be blown ou t away from th e d rive becau se th e on ly air in take wou ld be th e sin gle fan ven t on th e p ower su p p ly at th e rear. For system s th at op erate in extrem ely h arsh en viron m en ts, you can ad d a filter to th e fan in take ven t to fu rth er en su re th at all th e air en terin g th e system is clean an d free of d u st. Alth ou gh th is is th eoretically th e best way to ven tilate a system , a p rop erly d esign ed p ositive-p ressu re system n eed s to u se a m ore p owerfu l fan to p u ll th e req u ired am ou n t of air th rou gh a filter. Also, th e filter h as to be serviced on a p eriod ic basis—d ep en d in g u p on op eratin g con d ition s, it m ay n eed ch an gin g or clean in g as often as every week.

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In ad d ition , th e h eat load from th e p ower su p p ly on a fu lly load ed system exh au sts h eated air over th e CPU, red u cin g its coolin g cap ability. As n ewer CPUs create m ore an d m ore h eat, th e coolin g cap ability of th e airflow becom es absolu tely critical. In com m on p ractice, u sin g a stan d ard n egative-p ressu re system with an exh au st fan on th e p ower su p p ly an d a h igh -q u ality CPU coolin g fan is th e best solu tion . For th is reason , th e ATX p ower su p p ly sp ecification h as been am en d ed to allow for th e old er m eth od of n egativep ressu re ven tilation . +5V G G +12V

+5V G G +12V 86mm +5V G G +12V +5V G G +12V

140mm

138mm

5

7

3.3V* -12V COM

+

6mm

+

PS-ON COM

86mm

64mm

COM COM

+ -5V

+

16mm

115mm

1

12

2

13

3

14

4

15

5

16

6

17

7

18

8

19

9

20

10

3.3V* 3.3V* COM 5V COM 5V COM PW-OK

6 5V

5

11

30mm

5V

5VSB 12V

150mm *optional ATX Power connector pin out

5.9"x5.5"x3.4"

FIG. 6.6 ATX form factor p ower su p p ly. Th e ATX sp ecification was first released by In tel in 1995. In 1996 it becam e in creasin gly p op u lar in Pen tiu m an d Pen tiu m Pro-based PCs, cap tu rin g 18% of th e m oth erboard m arket. By th e year 2000, th is figu re is exp ected to in crease to 80%, with m ost Pen tiu m an d Pen tiu m II system s u sin g ATX m oth erboard s, case d esign s, an d p ower su p p lies. Th e ATX form factor ad d resses several p roblem s with th e Baby AT an d m in i form factors. Two m ain p roblem s with th e p ower su p p ly p ersist. On e is th at th e trad ition al PC p ower su p p ly h as two con n ectors th at p lu g in to th e m oth erboard . If you in sert th ese con n ectors backward or ou t of th eir n orm al seq u en ce, you will fry th e m oth erboard . Most resp on sible system m an u factu rers “key” th e m oth erboard an d p ower su p p ly con n ectors so th at you can n ot in stall th em backward or ou t of seq u en ce. However, som e ven d ors of ch eap er system s d o n ot featu re th is keyin g on th e board s or su p p lies th ey u se.

Power Supply Function and Operation

Th e ATX form factor in clu d es a n ew p ower p lu g for th e m oth erboard to p reven t u sers from p lu ggin g in th eir p ower su p p lies in correctly. Th is n ew con n ector h as 20 p in s an d is sin gle-keyed . Th is m akes it virtu ally im p ossible to p lu g it in backward . Becau se th ere is on e con n ector in stead of two alm ost id en tical on es, it is im p ossible to p lu g th em in ou t of seq u en ce. Th e n ew con n ector also su p p lies +3.3v, elim in atin g th e n eed for voltage regu lators on th e m oth erboard to p ower th e CPU an d oth er +3.3v circu its. Besid es th e n ew +3.3v sign als, an oth er set of sign als is fu rn ish ed by th e ATX PSU th at is n ot n orm ally seen on stan d ard p ower su p p lies. Th e set con sists of th e Power_On (PS_On ) an d 5v_Standby (5VSB) sign als, kn own collectively as Soft Power. Power_On is a m oth erboard sign al th at op eratin g system s su ch as W in d ows 9x u se to p ower th e system d own via software. Th ese sign als can also allow for th e op tion al u se of th e keyboard to p ower th e system back on —exactly like Ap p le Macin tosh system s. Th e 5v_Stan d by sign al is always active, givin g th e m oth erboard a lim ited sou rce of p ower even wh en off. Th e oth er p roblem solved by an ATX form factor p ower su p p ly with reverse-coolin g airflow is th at of keep in g tod ay’s system p rocessors cool. Bu t it on ly works in in d u strial ap p lication s, in wh ich an in d u strial-d u ty p ower su p p ly h as been d esign ed p rop erly for th e h eat-load of th e in ten d ed system an d in wh ich con stan t m ain ten an ce is p rovid ed . Most of th e h igh -en d Pen tiu m an d Pen tiu m Pro system s on th e m arket u se active h eat sin ks on th e p rocessor, wh ich m ean s th ere is a sm all fan on th e CPU d esign ed to cool it. In tel an d oth er m an u factu rers n ow p ackage coolin g fan s with th e CPU—som e are actu ally p erm an en tly m ou n ted on th e CPU. For best resu lts, u se CPU fan s on ly from rep u table m an u factu rers becau se a CPU fan can be on e of th e m ost critical com p on en ts for reliable op eration .

Not e The cooling method described here is recommended by the ATX specification, but it is not required. M anufacturers can use alternative methodologies, such as the traditional outblowing fan arrangement, as well as active and/ or passive heat sinks, on a system with an ATX motherboard. In fact, this may be a better solution for nonindustrial applications for which periodic maintenance of the power-supply filter is not assured. It is possible to modify a standard Baby AT or LPX power supply for use in an ATX system by adding the PS_ON and 5VSB signals and a +3.3v supply rail. If you plan to purchase a system with an ATX motherboard, don’t automatically assume that you are getting an ATX power supply. If a vendor is unable to supply you with answers to technical questions such as this, it may be a good idea to try another vendor.

NLX St yle. Th e NLX sp ecification , also d evelop ed by In tel, d efin es a low-p rofile case an d m oth erboard with m an y of th e sam e attribu tes as th e ATX. It u ses a sm aller form factor, h owever. As in p reviou s slim lin e system s, th e NLX m oth erboard u ses a riser board for th e exp an sion bu s slots. Th e NLX m oth erboard is also d esign ed for easy m ain ten an ce access; releasin g a sim p le catch en ables you to slid e th e en tire m oth erboard ou t of th e ch assis. Ju st as th e ATX arch itectu re fu n ction ally rep laced th e Baby AT form factor in fu ll-sized d esktop an d tower system s, NLX is in ten d ed to rep lace th e LPX form factor.

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Th e NLX sp ecification d oes n ot d efin e a n ew p ower su p p ly form factor, bu t a sep arate NLX p ower su p p ly recom m en d ation s d ocu m en t d escribes th e featu res n eed ed . To fit in to an NLX case, a com p u ter n eed s a p ower su p p ly th at is com p arable to th e LPX form factor in size, bu t wh ich u ses th e sam e 20-p in con n ector, voltage sign als, an d fan arran gem en t as an ATX-style PSU. Alth ou gh it’s p ossible to m od ify an LPX p ower su p p ly to su p p ort th e n ew m oth erboard featu res, som e m an u factu rers h ave begu n p rod u cin g p ower su p p lies sp ecifically d esign ed for u se in NLX system s. NLX is targeted m ore at th e corp orate com p u ter m arket, wh ich h as featu re an d m ain ten an ce req u irem en ts q u ite d ifferen t from th ose of h om e u sers. Ad op tion of th e NLX stan d ard is d raggin g sligh tly beh in d th at of ATX, bu t q u ite a few com p u ter m an u factu rers h ave an n ou n ced system s th at take ad van tage of th e lower p rices, sm aller footp rin ts, an d easier m ain ten an ce th at th e n ew form factor can p rovid e. SFX St yle ( m icroATX M ot herboards) . In tel h as released a th ird n ew m oth erboard sp ecification , called m icroATX, th at is in ten d ed for low-en d system s th at are d esign ed with an even sm aller footp rin t th an NLX an d with sm aller p ower su p p ly req u irem en ts. Becau se th e m icroATX d ocu m en t d efin es on ly th e m oth erboard form factor, In tel h as also released th e sp ecification for a n ew p ower su p p ly called SFX (see Figu re 6.7). Th e SFX p ower su p p ly is sp ecifically d esign ed for u se in sm all system s con tain in g a lim ited am ou n t of h ard ware. Th e PSU can p rovid e 90 watts of con tin u ou s p ower (135 watts at its p eak) in fou r voltages (+5, +12, –12, an d +3.3v). Th is am ou n t of p ower h as p roved to be su fficien t for a sm all system with a Pen tiu m II p rocessor, an AGP in terface, th ree exp an sion slots, an d th ree p erip h eral d evices—su ch as h ard d rives an d CD-ROMs.

Not e The SFX power supply does not provide the –5v current required for full compliance with the ISA bus standard. M icroATX systems are supposed to use the PCI bus or the AGP interface for all the expansion cards installed in the computer, omitting the ISA bus entirely.

Alth ou gh In tel d esign ed th e SFX p ower su p p ly sp ecification with th e m icroATX m oth erboard form factor in m in d , SFX is a wh olly sep arate stan d ard th at is com p lian t with oth er m oth erboard s as well. SFX p ower su p p lies u se th e sam e 20-p in con n ector d efin ed in th e ATX stan d ard an d in clu d e both th e Power_On an d 5v_Stan d by sign als. Th e fan arran gem en t is d ifferen t, h owever. Som e m od ification to th e p ower su p p ly’s m etal h ou sin g is req u ired in ord er to accom m od ate th e ATX arch itectu re. On an SFX p ower su p p ly, th e fan is located on th e su rface of th e h ou sin g, facin g th e in sid e of th e com p u ter’s case. Th e fan d raws th e air in to th e p ower su p p ly h ou sin g from th e system cavity an d exp els it th rou gh a p ort at th e rear of th e system . In tern alizin g th e fan in th is way red u ces system n oise, bu t it also sign ifies a retu rn to th e p re-ATX airflow d esign m od el, in wh ich th e fan d raws air in to th e case th rou gh th e d rive slots an d oth er op en in gs.

Power Supply Function and Operation

85.0 72.00

9.0 X 3.2 Cutout Clearance under cutout minimum 4.5 from inside cover

5.0 33.5

5.0

27.3

11.0 X 5.0 Cutout (2x) Clearance under cutout minimum 6.0 from inside cover

3.5 OP Wire Harness

15.0 100.0 4.0 X 5

5.0

Venting holes optional - to outside of chassis

120.0

Notes 1. Unless otherwise specified, all dimensions are in mm. Tolerance: Whole No.: XX→/x1 Decimal No.: XX↑/–0.5 2. Do not scale drawing. 3. A stamped SM fan guard may be used subject to approval.

115220

6.0

No. 8-32 UNC-28 Threaded Hole (3X)

63.5 31.5 5.0 6.02x 9.0 30.0

FIG. 6.7 SFX form factor p ower su p p ly. Pow er Supply Connect ors Table 6.1 sh ows th e p in ou ts for m ost LPX, Baby AT, stan d ard AT, an d PC/ XT-com p atible system s. Th e two six-p in con n ectors (P8 an d P9) attach th e p ower su p p ly to th e m oth erboard , wh ile P10 th rou gh P13 are id en tical fou r-p in con n ectors th at you u se to su p p ly p ower to in tern al p erip h erals, su ch as flop p y an d h ard d isk d rives. All stan d ard PC p ower su p p lies th at u se th e P8 an d P9 con n ectors h ave th em in stalled en d -to-en d so th at th e two black-colored wires (grou n d con n ection s) on both p ower cables are n ext to each oth er. Becau se th e con n ectors u su ally h ave a clasp th at p reven ts th em from bein g in serted backward on th e p in s on th e m oth erboard s, th e m ajor con cern is gettin g th em in th e correct ord er. Followin g th e “black on black” ru le keep s you safe. You m u st take care, h owever, to m ake su re n o u n con n ected m oth erboard p in s are between th e two con n ectors wh en you in stall th em . A p rop erly in stalled con n ector con n ects to an d covers every m oth erboard p ower p in —if an y p ower p in s are sh owin g on

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Chapter 6—Power Supply and Case

eith er sid e of th e con n ectors, th e en tire con n ector assem bly is in stalled in correctly, wh ich can resu lt in catastrop h ic failu re for th e m oth erboard an d everyth in g p lu gged in to it at th e tim e of p ower-u p . Som e system s m ay h ave m ore or fewer d rive con n ectors. For exam p le, IBM’s AT system p ower su p p lies h ave on ly th ree d isk d rive p ower con n ectors, alth ou gh m ost AT/ Tower-typ e p ower su p p lies h ave fou r d rive con n ectors. Dep en d in g on th eir p ower ratin gs, som e ATX su p p lies h ave as m an y as eigh t d rive con n ectors. If you are ad d in g d rives an d n eed ad d ition al d isk d rive p ower con n ectors, “Y” sp litter cables are available from m an y electron ics su p p ly h ou ses (in clu d in g Rad io Sh ack). Th ese cables can ad ap t a sin gle p ower con n ector to service two d rives. As a p recau tion , m ake su re th at you r total p ower su p p ly ou tp u t is cap able of su p p lyin g th e ad d ition al p ower. Table 6.1

Typical PC/ XT and AT Pow er Supply Connect ions

Connect or

AT Type

PC/ XT Type

P8-1

Power_Good (+5v)

Power_Good (+5v)

P8-2

+5v

Key (No connect)

P8-3

+12v

+12v

P8-4

–12v

–12v

P8-5

Ground (0)

Ground (0)

P8-6

Ground (0)

Ground (0)

P9-1

Ground (0)

Ground (0)

P9-2

Ground (0)

Ground (0)

P9-3

–5v

–5v

P9-4

+5v

+5v

P9-5

+5v

+5v

P9-6

+5v

+5v

P10-1

+12v

+12v

P10-2

Ground (0)

Ground (0)

P10-3

Ground (0)

Ground (0)

P10-4

+5v

+5v

P11-1

+12v

+12v

P11-2

Ground (0)

Ground (0)

P11-3

Ground (0)

Ground (0)

P11-4

+5v

+5v

P12-1

+12v

—

P12-2

Ground (0)

—

P12-3

Ground (0)

—

P12-4

+5v

—

P13-1

+12v

—

P13-2

Ground (0)

—

P13-3

Ground (0)

—

P13-4

+5v

—

Power Supply Function and Operation

Notice th at th e Baby AT an d LPX p ower su p p lies also u se th e AT/ Desktop or Tower p in con figu ration . Th e on ly oth er in d u stry stan d ard PSU-to-m oth erboard con n ector is th e Molex 39-29-9202 (or eq u ivalen t). First u sed in th e ATX form factor p ower su p p ly, it is n ow u sed by th e NLX an d SFX form factors. Th is is a 20-p in keyed con n ector with p in s con figu red , as sh own in Table 6.2. Th e colors for th e wires are th ose recom m en d ed by th e ATX stan d ard ; h owever, th ey are n ot req u ired for com p lian ce to th e sp ecification (in oth er word s, th e colors cou ld vary from m an u factu rer to m an u factu rer).

Tip Although the PC/ XT power supplies do not have any signal on pin P8-2, you can still use them on AT-type motherboards, or vice versa. The presence or absence of the +5v signal on that pin has little or no effect on system operation.

Table 6.2

ATX Pow er Supply Connect ions

Color

Signal

Pin

Pin

Signal

Color

Orange

+3.3v*

11

1

+3.3v*

Orange

Blue

–12v

12

2

+3.3v*

Orange

Black

GND

13

3

GND

Black

Green

PS_On

14

4

+5v

Red

Black

GND

15

5

GND

Black

Black

GND

16

6

+5v

Red

Black

GND

17

7

GND

Black

White

–5v

18

8

Power_Good

Gray

Red

+5v

19

9

+5VSB (Standby)

Purple

Red

+5v

20

10

+12v

Yellow

* = Optional signal

Not e The ATX supply features several signals not seen before, such as the +3.3v, Power_On, and +5v_Standby signals. Therefore, it is difficult to adapt a standard LPX form factor supply to make it work properly in an ATX system, even though the shapes of the power supplies themselves are virtually identical.

ATX Opt ional Pow er Connect or. In ad d ition to th e m ain 20-p in p ower con n ector, th e ATX sp ecification d efin es an op tion al six-p in con n ector (two rows of th ree p in s each ) as u sin g 22 AW G wire to p rovid e th e sign als sh own in Table 6.3. Th e com p u ter can u se th ese sign als to m on itor an d con trol th e coolin g fan , m on itor th e voltage of th e +3.3v sign al to th e m oth erboard , an d p rovid e p ower an d grou n d in g to d evices com p lian t with th e IEEE 1394 (FireW ire) stan d ard .

405

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Chapter 6—Power Supply and Case

Table 6.3

ATX Opt ional Pow er Supply Connect ions

Pin

Signal

Color

1

FanM

White

2

FanC

White w/ blue stripe

3

+3.3v sense

White w/ brown stripe

4

1394R

White w/ black stripe

5

1394V

White w/ red stripe

6

Reserved

Th e Fan M sign al en ables th e op eratin g system to m on itor th e statu s of th e p ower su p p ly’s coolin g fan so th at it can take ap p rop riate action s, su ch as sh u ttin g d own th e system if th e fan fails. An op eratin g system can u se th e Fan C sign al with variable voltages to con trol th e op eration of th e p ower su p p ly’s fan , sh iftin g it in to a low p ower state or sh u ttin g it off com p letely wh en th e system is in sleep or stan d by m od e. Th e ATX stan d ard sp ecifies th at a voltage of +1v or less in d icates th at th e fan is to sh u t d own , wh ile +10.5v or m ore in stru ct th e fan to op erate at fu ll sp eed . Th e system d esign er can d efin e in term ed iate voltages to op erate variable-sp eed fan s at variou s levels. If th e p ower su p p ly d oes n ot in clu d e a variable-sp eed fan circu it, an y voltage level h igh er th an +1v on th e Fan C sign al is in terp reted as a com m an d to ru n th e fan at its fu ll (an d on ly) sp eed .

Not e The SFX specification also defines the use of a six-pin control connector, but uses it only to provide a fan control signal on one pin. The other five pins are all reserved for future use.

Pow er Sw it ch Connect ors. Most of th e p ower su p p lies u sed tod ay em p loy a rem ote p ower switch th at is accessible from th e fron t of th e com p u ter case. In con trast, earlier form factors, su ch as th e AT d esktop an d Baby AT, u sed a switch th at was in tegrated in to th e p ower su p p ly h ou sin g. Becau se th e p ower su p p ly was m ou n ted in a rear corn er of th e case, th e switch was in con ven ien tly located on th e back of th e com p u ter case. Pre-ATX p ower su p p lies u se a rem ote switch th at is con n ected to th e p ower su p p ly th rou gh a stan d ard fou r-wire cable. Th e en d s of th e cable are fitted with sp ad e con n ector lu gs, wh ich p lu g on to th e sp ad e con n ectors on th e p ower switch . Th e switch is u su ally a p art of th e case, so th e p ower su p p ly com es with th e cable an d n o switch . Th e cable from th e p ower su p p ly to th e switch in th e case con tain s fou r color-cod ed wires. Th ere m ay also be a fifth wire su p p lyin g a grou n d con n ection to th e case.

Caut ion The remote power switch leads carry 110v AC current at all times. You could be electrocuted if you touch the ends of these wires with the power supply plugged in! Always make sure the power supply is unplugged before connecting or disconnecting the remote power switch.

Power Supply Function and Operation

Th e fou r or five wires are color cod ed as follows: ■ Th e brown an d blu e wires are th e live an d n eu tral feed wires from th e 110v p ower cord to th e p ower su p p ly. Th ese wires are always h ot wh en th e p ower su p p ly is p lu gged in . ■ Th e black an d wh ite wires carry th e AC feed from th e switch back to th e p ower su p p ly. Th ese lead s sh ou ld be h ot on ly wh en th e p ower su p p ly is p lu gged in an d th e switch is tu rn ed on . ■ A green wire or a green wire with a yellow strip e is th e grou n d lead . It sh ou ld be con n ected to th e PC case, an d sh ou ld h elp grou n d th e p ower su p p ly to th e case. On th e switch , th e tabs for th e lead s are u su ally color cod ed ; if n ot, you can still con n ect th em easily. If n o color cod in g is on th e switch , th en p lu g th e blu e an d brown wires on to th e tabs th at are p arallel to each oth er an d th e black an d wh ite wires to th e tabs th at are an gled away from each oth er. See Figu re 6.8 as a gu id e.

Caut ion Although these wire color codings are used on most power supplies, they are not universal. I have encountered power supplies that did not use the same coloring scheme described here. Unless you can verify the color codes with the power supply manufacturer, always disconnect the power supply from the wall socket before handling any of these wires.

White

Black

Blue

Brown

FIG. 6.8 Power su p p ly rem ote switch con n ection s. As lon g as th e blu e an d brown wires are on th e on e set of tabs an d th e black an d wh ite lead s are on th e oth er, th e switch an d su p p ly will work p rop erly. If you in correctly m ix th e lead s, you will likely blow th e circu it breaker for th e wall socket, becau se m ixin g th em can create a d irect sh ort circu it. All ATX an d su bseq u en t p ower su p p lies th at em p loy th e 20-p in m oth erboard con n ector u se th e PS_ON sign al to p ower u p th e system . As a resu lt, th e rem ote switch d oes n ot p h ysically con trol th e p ower su p p ly’s access to th e 110v AC p ower, as in th e old er style PSUs. In stead , th e p ower su p p ly’s on or off statu s is toggled by a PS_ON sign al received on p in 14 of th e ATX con n ector.

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Chapter 6—Power Supply and Case

Th e PS_ON sign al can be gen erated p h ysically by th e com p u ter’s p ower switch or electron ically by th e op eratin g system . PS_ON is an active low sign al, m ean in g th at all th e DC p ower sign als gen erated by th e PSU are d eactivated wh en PS_ON is h eld h igh , with th e excep tion of th e +5VSB (stan d by) sign al on p in 9, wh ich is active wh en ever th e p ower su p p ly is con n ected to an AC p ower sou rce. Th e +5VSB sign al p rovid es th e p ower for th e rem ote switch on th e case to op erate wh ile th e com p u ter is off. Th u s, th e rem ote switch in an ATX-style system (wh ich sh ou ld in clu d e m ost NLX an d SFX system s) carries on ly +5v of DC p ower, rath er th an th e fu ll 110v AC cu rren t th at is in th e old er form factors.

Caut ion The continuous presence of the +5VSB signal on pin 9 of the ATX connector means that the motherboard is always receiving power from the PSU when connected to an AC source, even when the computer is turned off. As a result, it is even more crucial to unplug an ATX system from the power source before working inside the case than it is on an earlier model system.

Disk Drive Pow er Connect ors. Th e d isk d rive con n ectors on p ower su p p lies are fairly u n iversal with regard to p in con figu ration , an d even wire color. Table 6.4 sh ows th e stan d ard d isk d rive p ower con n ector p in ou t an d wire colors. Table 6.4

Disk Drive Pow er Connect or Pinout

Pin

W ire Color

Signal

1

Yellow

+12v

2

Black

Gnd

3

Black

Gnd

4

Red

+5v

Th is in form ation ap p lies wh eth er th e d rive con n ector is th e larger Molex version or th e sm aller m in i-version u sed on m ost 3 1/ 2-in ch flop p y d rives. In each case, th e p in ou ts an d wire colors are th e sam e. To d eterm in e th e location of p in 1, look at th e con n ector carefu lly. It is u su ally em bossed in th e p lastic con n ector bod y; h owever, it is often tin y an d d ifficu lt to read . Fortu n ately, th ese con n ectors are keyed an d th erefore d ifficu lt to in sert in correctly. Figu re 6.9 sh ows th e keyin g with resp ect to p in n u m bers on th e larger d rive p ower con n ector.

Black

Black

Red

+12 Gnd Gnd +5 Yellow

408

1

2

3

4

FIG. 6.9 A d isk d rive fem ale p ower su p p ly cable con n ector.

Power Supply Function and Operation

Not e Some drive connectors may supply only two wires—usually the +5v and a single ground (pins 3 and 4)—because the floppy drives in most newer systems run on only +5v and do not use the +12v at all.

Physical Connect or Part Num bers. Th e p h ysical con n ectors u sed in in d u stry-stan d ard PC p ower su p p lies were origin ally sp ecified by IBM for th e su p p lies u sed in th e origin al PC/ XT/ AT system s. Th ey u sed a sp ecific typ e of con n ector between th e p ower su p p ly an d th e m oth erboard (th e P8 an d P9 con n ectors) an d sp ecific con n ectors for th e d isk d rives. Th e m oth erboard con n ectors u sed in all th e in d u stry-stan d ard p ower su p p lies were u n ch an ged from 1981 (wh en th e IBM PC ap p eared ) u n til 1995 (wh en In tel released th e ATX stan d ard ). Th e origin al PC’s fou r-p in d isk d rive con n ector was au gm en ted by a sm aller (also fou r-p in ) p ower con n ector wh en 3 1/ 2-in ch flop p y d rives ap p eared in 1986. Table 6.5 lists th e stan d ard con n ectors u sed for m oth erboard an d d isk d rive p ower. Table 6.5

Physical Pow er Connect ors

Connect or Descript ion

Fem ale ( on Pow er Cable)

M ale ( on Com ponent )

ATX/ NLX/ SFX (20-pin)

M olex 39-29-9202

M olex 39-01-2200

ATX Optional (6-pin)

M olex 39-01-2960

M olex 39-30-1060

PC/ AT/ LPX M otherboard P8/ P9

Burndy GTC6P-1

Burndy GTC 6RI

Disk Drive (large style)

AM P 1-480424-0

AM P 1-480426-0

Disk Drive (small style)

AM P 171822-4

AM P 171826-4

You can get th ese raw con n ectors th rou gh th e electron ics su p p ly h ou ses (Allied , Newark, an d Digi-Key, for exam p le) fou n d in Ap p en d ix A, “Ven d or List.” You also can get com p lete cable assem blies, in clu d in g d rive ad ap ters th at con vert th e large con n ectors in to sm all con n ectors; d isk d rive “Y” sp litter cables; an d m oth erboard p ower exten sion cables from a n u m ber of th e cable an d m iscellan eou s su p p ly h ou ses, su ch as Ci Design an d Key Power.

Caut ion Before you install additional connectors to your power supply using “ Y” splitters or any other type of connector, be sure your power supply is capable of delivering sufficient power for all your internal peripherals. Overloading the power supply can cause damage to electrical components and stored data.

The Pow er_Good Signal Th e Power_Good sign al (som etim es called Power_OK or POK) is a +5v sign al (with variation from +3.0 th rou gh +6.0v gen erally bein g con sid ered accep table) gen erated in th e p ower su p p ly wh en it h as p assed its in tern al self tests an d th e ou tp u ts h ave stabilized . Th is n orm ally takes p lace an ywh ere from 0.1 to 0.5 secon d s after you tu rn on th e p ower su p p ly switch . Th is p ower su p p ly sen d s th e sign al to th e m oth erboard , wh ere it is received by th e p rocessor tim er ch ip , wh ich con trols th e reset lin e to th e p rocessor.

409

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Chapter 6—Power Supply and Case

In th e absen ce of Power_Good , th e tim er ch ip con tin u ou sly resets th e p rocessor, wh ich p reven ts th e system from ru n n in g u n d er bad or u n stable p ower con d ition s. W h en th e tim er ch ip receives th e Power_Good sign al, it stop s resettin g th e p rocessor, an d th e p rocessor begin s execu tin g wh atever cod e is at ad d ress FFFF:0000 (u su ally th e ROM BIOS). If th e p ower su p p ly can n ot m ain tain p rop er ou tp u ts (su ch as wh en a brown ou t occu rs), th e Power_Good sign al is with d rawn , an d th e p rocessor is au tom atically reset. W h en th e p ower ou tp u t retu rn s to its p rop er levels, th e PSU regen erates th e Power_Good sign al an d th e system again begin s op eration (as if you h ad ju st p owered on ). By with d rawin g Power_Good , th e system n ever “sees” th e bad p ower becau se it is “stop p ed ” q u ickly (reset) rath er th an bein g allowed to op erate u sin g u n stable or im p rop er p ower levels, wh ich can cau se p arity errors an d oth er p roblem s. On p re-ATX system s, th e Power_Good con n ection is m ad e via con n ector P8-1 (P8 Pin 1) from th e p ower su p p ly to th e m oth erboard . ATX an d later system s u se p in 8 of th e 20p in con n ector. A well-d esign ed p ower su p p ly d elays th e arrival of th e Power_Good sign al u n til all th e PSU’s voltages stabilize after you tu rn th e system on . Bad ly d esign ed p ower su p p lies, wh ich are fou n d in m any low-cost system s, often d o n ot d elay th e Power_Good sign al p rop erly an d en able th e p rocessor to start too soon . (Th e n orm al Power_Good d elay is from 0.1 to 0.5 secon d s.) Im p rop er Power_Good tim in g also cau ses CMOS m em ory corru p tion in som e system s. If you fin d th at a system con sisten tly fails to boot u p p rop erly th e first tim e you tu rn on th e switch bu t th at it su bseq u en tly boots u p if you p ress th e reset or Ctrl+Alt+Delete warm boot com m an d , you likely h ave a p roblem with th e Power_Good tim in g. You m u st in stall a n ew, h igh -q u ality p ower su p p ly an d see wh eth er it solves th e p roblem . Som e ch eap er p ower su p p lies d o n ot h ave p rop er Power_Good circu itry an d m ay ju st tie an y +5v lin e to th at sign al. Som e m oth erboard s are m ore sen sitive to an im p rop erly d esign ed or im p rop erly fu n ction in g Power_Good sign al th an oth ers. In term itten t startu p p roblem s are often th e resu lt of im p rop er Power_Good sign al tim in g. A com m on exam p le is wh en you rep lace a m oth erboard in a system an d th en fin d th at th e system in term itten tly fails to start p rop erly wh en you tu rn th e p ower on . Th is can be very d ifficu lt to d iagn ose, esp ecially for th e in exp erien ced tech n ician , becau se th e p roblem ap p ears to be cau sed by th e n ew m oth erboard . Alth ou gh it seem s as if th e n ew m oth erboard is d efective, it u su ally tu rn s ou t th at th e p ower su p p ly is p oorly d esign ed . It eith er can n ot p rod u ce stable en ou gh p ower to p rop erly op erate th e n ew board , or it h as an im p rop erly wired or tim ed Power_Good sign al (wh ich is m ore likely). In th ese situ ation s, rep lacin g th e su p p ly with a h igh -q u ality u n it, in ad d ition to th e n ew m oth erboard , is th e p rop er solu tion . Pow er Supply Loading PC p ower su p p lies are of a switch in g rath er th an a lin ear d esign . Th e switch in g typ e of d esign u ses a h igh -sp eed oscillator circu it to gen erate d ifferen t ou tp u t voltages. It is very efficien t in size, weigh t, an d en ergy in com p arison to th e stan d ard lin ear d esign , wh ich u ses a large in tern al tran sform er to gen erate d ifferen t ou tp u ts. Th is typ e of tran sform er

Power Supply Function and Operation

d esign is in efficien t in at least th ree ways. First, th e ou tp u t voltage of th e tran sform er lin early follows th e in p u t voltage (h en ce th e n am e, lin ear), so an y flu ctu ation s in th e AC p ower goin g in to th e system can cau se p roblem s with th e ou tp u t. Secon d , th e h igh cu rren t req u irem en ts of a PC system req u ire th e u se of h eavy wirin g in th e tran sform er. Th ird , th e 60Hz (h ertz) freq u en cy of th e AC p ower su p p lied from you r bu ild in g is d ifficu lt to filter ou t in sid e th e p ower su p p ly, req u irin g large an d exp en sive filter cap acitors. Th e switch in g su p p ly, on th e oth er h an d , u ses a switch in g circu it th at “ch op s u p ” th e in com in g p ower at a relatively h igh freq u en cy. Th is allows for th e u se of h igh -freq u en cy tran sform ers th at are m u ch ligh ter. Also, th e h igh er freq u en cy is m u ch easier an d ch eap er to filter ou t at th e ou tp u t, an d th e in p u t voltage can vary wid ely. In p u t ran gin g from 90 to 135 volts still p rod u ces th e p rop er ou tp u t levels, an d m an y switch in g su p p lies can au tom atically ad ju st to 220-volt in p u t. On e ch aracteristic of all switch in g-typ e p ower su p p lies is th at th ey d o n ot ru n with ou t a load . Th is m ean s th at you m u st h ave th e su p p ly p lu gged in to som eth in g d rawin g p ower for th e su p p ly to work. If you sim p ly h ave th e p ower su p p ly on a ben ch with n oth in g p lu gged in to it, th e su p p ly eith er bu rn s u p or its p rotection circu itry sh u ts it d own . Most p ower su p p lies are p rotected from n o-load op eration an d sh u t d own au tom atically. Som e of th e ch eap clon e su p p lies, h owever, lack th e p rotection circu it an d relay. Th ey are d estroyed after a few secon d s of n o-load op eration . A few p ower su p p lies h ave th eir own bu ilt-in load resistors, so th ey can ru n even th ou gh n o n orm al load is p lu gged in . Accord in g to IBM sp ecification s for th e stan d ard 192-watt p ower su p p ly u sed in th e origin al AT, a m in im u m load of 7.0 am p s was req u ired at +5v an d a m in im u m of 2.5 am p s was req u ired at +12v for th e su p p ly to work p rop erly. Becau se flop p y d rives p resen t n o +12v load u n less th ey are sp in n in g, system s with ou t a h ard d isk d rive often d o n ot op erate p rop erly. Som e p ower su p p lies h ave a m in im u m load req u irem en t for both th e +5v an d +12v sid es. If you fail to m eet th is m in im u m load , th e su p p ly sh u ts d own . Becau se of th is ch aracteristic, wh en IBM u sed to sh ip AT system s with ou t a h ard d isk, th ey p lu gged th e h ard d isk d rive p ower cable in to a large 5-oh m 50-watt san d bar resistor, wh ich was m ou n ted in a little m etal cage assem bly wh ere th e d rive wou ld h ave been . Th e AT case h ad screw h oles on top of wh ere th e h ard d isk wou ld go, sp ecifically d esign ed to m ou n t th is resistor cage. Several com p u ter stores I kn ew of in th e m id -80s wou ld ord er th e d iskless AT an d in stall th eir own 20M or 30M d rives, wh ich th ey cou ld get m ore ch eap ly from oth er sou rces th an from IBM. Th ey were th rowin g away th e load resistors by th e h u n d red s! I m an aged to grab a cou p le at th e tim e, wh ich is h ow I kn ow th e typ e of resistor th ey u sed . Th is resistor wou ld be con n ected between p in 1 (+12v) an d p in 2 (Grou n d ) on th e h ard d isk p ower con n ector. Th is wou ld p lace a 2.4-am p load on th e su p p ly’s +12v ou tp u t, d rawin g 28.8 watts of p ower—it wou ld get h ot!—an d th u s en ablin g th e su p p ly to op erate n orm ally. Note th at th e coolin g fan in m ost p ower su p p lies d raws ap p roxim ately 0.1 to

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0.25 am p s, brin gin g th e total load to 2.5 am p s or m ore. If th e load resistor were m issin g, th e system wou ld in term itten tly fail to start u p or op erate p rop erly. Th e m oth erboard wou ld d raw +5v at all tim es, bu t +12v wou ld n orm ally be u sed on ly by m otors, an d th e flop p y d rive m otors wou ld be off m ost of th e tim e. Most of th e p ower su p p lies in u se tod ay d o n ot req u ire as m u ch of a load as th e origin al IBM AT p ower su p p ly. In m ost cases, a m in im u m load of 0 to 0.3 am p at +3.3v, 2.0 to 4.0 am p s at +5v, an d 0.5 to 1.0 am p s at +12v is con sid ered accep table. Most m oth erboard s easily d raw th e m in im u m +5v cu rren t by th em selves. Th e stan d ard p ower su p p ly coolin g fan d raws on ly 0.1 to 0.25 am p s, so th e +12v m in im u m load m ay still be a p roblem for a d iskless workstation . Gen erally, th e h igh er th e ratin g on th e su p p ly, th e m ore m in im u m load req u ired ; h owever, th ere are excep tion s, so th is is a sp ecification you wan t to ch eck wh en evalu atin g p ower su p p lies. Som e h igh -q u ality switch in g p ower su p p lies h ave bu ilt-in load resistors an d can ru n u n d er a n o-load situ ation becau se th e su p p ly load s. Oth er h igh -q u ality p ower su p p lies, su ch as th ose from PC Power an d Coolin g, h ave n o in tern al load resistors. Th ey on ly req u ire a sm all load on th e +5 su p p ly to op erate p rop erly. Man y of th e ch eap er clon e su p p lies, wh ich often d o n ot h ave bu ilt-in load resistors, m ay req u ire +3.3v, +5v, an d +12v load s to work. If you wan t to ben ch test a p ower su p p ly, m ake su re you p lace load s on all th e PSU’s p ositive voltage ou tp u ts. Th is is on e reason wh y it is best to test th e su p p ly wh ile it is in stalled in th e system in stead of testin g it sep arately on th e ben ch . For im p rom p tu ben ch testin g, you can u se a sp are m oth erboard an d h ard d isk d rive to load th e ou tp u ts. Pow er-Supply Rat ings A system m an u factu rer sh ou ld be able to p rovid e you with th e tech n ical sp ecification s of th e p ower su p p lies th ey u se in th eir system s. Th is typ e of in form ation m ay be fou n d in th e system ’s tech n ical-referen ce m an u al, as well as on stickers attach ed d irectly to th e p ower su p p ly. Power-su p p ly m an u factu rers can also su p p ly th is d ata, wh ich is p referable if you can id en tify th e m an u factu rer an d con tact th em d irectly. Tables 6.6 an d 6.7 list p ower-su p p ly sp ecification s for several of IBM’s u n its, from wh ich th e p ower su p p lies of m an y oth er system s are d erived . Th e in p u t sp ecification s are listed as voltages, an d th e ou tp u t sp ecification s are listed as am p s at several voltage levels. IBM rep orts ou tp u t wattage level as “sp ecified ou tp u t wattage.” If you r m an u factu rer d oes n ot list th e total wattage, you can con vert am p erage to wattage by u sin g th e followin g sim p le form u la: W atts = Volts × Am p s By m u ltip lyin g th e voltage by th e am p erage available at each ou tp u t an d th en ad d in g th e resu lts u p , you can calcu late th e total cap able ou tp u t wattage of th e su p p ly.

Power Supply Function and Operation

Table 6.6

Pow er-Supply Out put Rat ings for IBM “Classic” Syst em s PC

Port -PC

XT

XT-286

AT

M inim um Input Voltage

104

90

90

90

90

M axim um Input Voltage

127

137

137

137

137

No

Yes

No

Auto

Yes

110/ 220v Switching Output Current (amps): +5v

7.0

11.2

15.0

20.0

–5v

0.3

0.3

0.3

0.3

0.3

+12v

2.0

4.4

4.2

4.2

7.3

–12v

0.25

0.25

0.25

19.8

0.25

0.3

Calculated output wattage

63.5

113.3

129.9

154.9

191.7

Specified output wattage

63.5

114.0

130.0

157.0

192.0

Table 6.6 sh ows th e stan d ard p ower su p p ly ou tp u t levels available in in d u stry-stan d ard form factors. Most m an u factu rers offer su p p lies with ratin gs from 100 watts to 450 watts or m ore. Table 6.7 sh ows th e rated ou tp u ts at each of th e voltage levels for su p p lies with d ifferen t m an u factu rer-sp ecified ou tp u t ratin gs. To com p ile th e table, I referred to th e sp ecification sh eets for su p p lies from Astec Stan d ard Power an d PC Power an d Coolin g. Alth ou gh m ost of th e ratin gs are accu rate, th ey are som ewh at m islead in g for th e h igh er wattage u n its. Table 6.7

Typical Com pat ible Pow er-Supply Out put Rat ings

Specified Out put W at t age

100W

150W

200W

250W

300W

375W

450W

+5v

10.0

15.0

20.0

25.0

32.0

35.0

45.0

–5v

0.3

0.3

0.3

0.5

1.0

0.5

0.5

+12v

3.5

5.5

8.0

10.0

10.0

13.0

15.0

Output Current (amps):

–12v Calculated output wattage

0.3

0.3

0.3

0.5

1.0

0.5

1.0

97.1

146.1

201.1

253.5

297.0

339.5

419.5

Ad d in g a +3.3v sign al to th e p ower su p p ly m od ifies th e eq u ation sign ifican tly. Table 6.8 con tain s d ata for variou s ATX p ower su p p lies th at in clu d e a +3.3v sign al. Table 6.8

ATX Pow er-Supply Out put Rat ings

Specified Out put W at t age

235W

275W

300W

400W

+3.3v

14.0

14.0

14.0

28.0

+5v

22.0

30.0

30.0

30.0

Output Current (amps):

(continues)

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Chapter 6—Power Supply and Case

Table 6.8

ATX Pow er-Supply Out put Rat ings Cont inued

Specified Out put W at t age M ax +3.3/ +5v

235W 125

275W 150

300W 150

400W 215

–5v

0.5

0.5

0.5

1.0

+12v

8.0

10.0

12.0

14.0

–12v

1.0

1.0

1.0

1.0

If you com p u te th e total ou tp u t in th e u su al way, th ese PSUs seem to p rod u ce an ou tp u t th at is m u ch h igh er th an th eir ratin gs. Th e 300W m od el, for exam p le, com es ou t at 354.7 watts. However, n otice th at th e su p p ly also h as a m axim u m com bin ed ou tp u t for th e +3.3v an d +5v sign als of 150 watts. Th is brin gs th e total ou tp u t to a m ore logical 308.5 watts. Most PC p ower su p p lies h ave ratin gs between 150 an d 300 watts. Alth ou gh lesser ratin gs are n ot u su ally d esirable, it is p ossible to p u rch ase h eavy-d u ty p ower su p p lies for m ost system s th at h ave ou tp u ts as h igh as 500 watts. Th e 300-watt an d larger u n its are excellen t for en th u siasts wh o are bu ild in g fu lly op tion ed d esktop s or tower system s. Th ese su p p lies ru n an y com bin ation of m oth erboard an d exp an sion card , as well as a large n u m ber of d isk d rives an d oth er p erip h erals. In m ost cases, you can n ot exceed th e ratin gs on th ese p ower su p p lies—th e system will be ou t of room for ad d ition al item s first! Most p ower su p p lies are con sid ered to be universal, or worldwide. Th at is, th ey can also ru n on th e 220v, 50-cycle cu rren t u sed in Eu rop e an d m an y oth er p arts of th e world . Man y p ower su p p lies th at can switch from 110v to 220v in p u t d o so au tom atically, bu t a few req u ire you to set a switch on th e back of th e p ower su p p ly to in d icate wh ich typ e of p ower you will access. If you r su p p ly d oes n ot switch au tom atically, m ake su re th e voltage settin g is correct. If you p lu g th e p ower su p p ly in to a 110v ou tlet wh ile set in th e 220v settin g, n o d am age will resu lt, bu t th e su p p ly will certain ly n ot op erate p rop erly u n til you correct th e settin g. On th e oth er h an d , if you are in a foreign cou n try with a 220v ou tlet an d h ave th e switch set for 110v, you m ay cau se som e d am age. Pow er-Supply Specificat ions In ad d ition to p ower ou tp u t, m an y oth er sp ecification s an d featu res go in to m akin g a h igh -q u ality p ower su p p ly. I h ave h ad m an y system s over th e years. My exp erien ce h as been th at if a brown ou t occu rs in a room with several system s ru n n in g, th e system s with h igh er-q u ality p ower su p p lies an d h igh er ou tp u t ratin gs are far m ore likely to m ake it th rou gh th e p ower d istu rban ces u n scath ed , wh ereas oth ers ch oke. High -q u ality p ower su p p lies also h elp p rotect you r system s. A p ower su p p ly from a ven d or su ch as Astec or PC Power an d Coolin g will n ot be d am aged if an y of th e followin g con d ition s occu r:

Power Supply Function and Operation

■ A 100 p ercen t p ower ou tage of an y d u ration ■ A brown ou t of an y kin d ■ A sp ike of u p to 2,500v ap p lied d irectly to th e AC in p u t (for exam p le, a ligh tn in g strike or a ligh tn in g sim u lation test) Decen t p ower su p p lies h ave an extrem ely low cu rren t leakage to grou n d of less th an 500 m icroam p s. Th is safety featu re is im p ortan t if you r ou tlet h as a m issin g or im p rop erly wired grou n d lin e. As you can see, th ese sp ecification s are fairly tou gh an d are certain ly rep resen tative of a h igh -q u ality p ower su p p ly. Make su re th at you r su p p ly can m eet th ese sp ecification s. You can also u se m an y oth er criteria to evalu ate a PSU. Th e p ower su p p ly is a com p on en t m an y u sers ign ore wh en sh op p in g for a PC, an d it is th erefore on e th at som e system ven d ors m ay ch oose to skim p on . After all, a d ealer is far m ore likely to be able to in crease th e p rice of a com p u ter by sp en d in g m on ey on ad d ition al m em ory or a larger h ard d rive th an by in stallin g a better p ower su p p ly. W h en bu yin g a com p u ter (or a rep lacem en t PSU), it is always a good id ea to learn as m u ch as p ossible abou t th e p ower su p p ly. However, m an y con su m ers are in tim id ated by th e vocabu lary an d th e statistics fou n d in a typ ical PSU sp ecification . Here are som e of th e m ost com m on p aram eters fou n d on p ower su p p ly sp ecification sh eets, alon g with th eir m ean in gs: ■ Mean Tim e Between Failures (MTBF) or Mean Tim e To Failure (MTTF). Th e (calcu lated ) average in terval, in h ou rs, th at th e p ower su p p ly is exp ected to op erate before failin g. Power su p p lies typ ically h ave MTBF ratin gs (su ch as 100,000 h ou rs or m ore) th at are clearly n ot th e resu lt of real-tim e em p irical testin g. In fact, m an u factu rers u se p u blish ed stan d ard s to calcu late th e resu lts, based on th e failu re rates of th e p ower su p p ly’s in d ivid u al com p on en ts. MTBF figu res for p ower su p p lies often in clu d e th e load to wh ich th e PSU was su bjected (in th e form of a p ercen tage) an d th e tem p eratu re of th e en viron m en t in wh ich th e tests were p erform ed . ■ Input Range (or Operating Range). Th e ran ge of voltages th at th e p ower su p p ly is p rep ared to accep t from th e AC p ower sou rce. For 110v AC cu rren t, an in p u t ran ge of 90 to 135v is com m on ; for 220v cu rren t, a 180 to 270v ran ge is typ ical. ■ Peak Inrush Current. Th e greatest am ou n t of cu rren t d rawn by th e p ower su p p ly at a given m om en t im m ed iately after it is tu rn ed on , exp ressed in term s of am p s at a p articu lar voltage. Th e lower th e cu rren t, th e less th erm al sh ock th e system exp erien ces. ■ Holdup Tim e. Th e am ou n t of tim e (in m illisecon d s) th at a p ower su p p ly’s ou tp u t rem ain s with in th e sp ecified voltage ran ges after its in p u t ceases. Valu es of 15–25 m illisecon d s are com m on for tod ay’s PSUs.

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■ Transient Response. Th e am ou n t of tim e (in m icrosecon d s) a p ower su p p ly takes to brin g its ou tp u t back th e sp ecified voltage ran ges after a steep ch an ge of th e ou tp u t cu rren t. In oth er word s, th e am ou n t of tim e it takes for th e ou tp u t p ower levels to stabilize after a d evice in th e system starts or stop s d rawin g p ower. Power su p p lies sam p le th e cu rren t bein g u sed by th e com p u ter at regu lar in tervals. W h en a d evice stop s d rawin g p ower d u rin g on e of th ese in tervals (su ch as wh en a flop p y d rive stop s sp in n in g), th e PSU m ay su p p ly too h igh a voltage to th e ou tp u t for a brief tim e. Th is excess voltage is called overshoot, an d th e tran sien t resp on se is th e tim e th at it takes for th e voltage to retu rn to th e sp ecified level. On ce a m ajor p roblem th at cam e with switch in g p ower su p p lies, oversh oot h as been greatly red u ced in recen t years. Tran sien t resp on se valu es are som etim es exp ressed in tim e in tervals, an d at oth er tim es are exp ressed in term s of a p articu lar ou tp u t ch an ge, su ch as “p ower ou tp u t levels stay with in regu lation d u rin g ou tp u t ch an ges of u p to 20%.” ■ Overvoltage Protection. Th e trip p oin ts for each ou tp u t at wh ich th e p ower su p p ly sh u ts d own or sq u elch es th e sign al for th at ou tp u t. Valu es can be exp ressed as a p ercen tage (for exam p le, 120% for +3.3 an d +5v) or as raw voltages (for exam p le, +4.6v for th e +3.3v ou tp u t an d 7.0v for th e +5v ou tp u t). ■ Maxim um Load Current. Th e largest am ou n t of cu rren t (in am p s) th at can be safely d elivered th rou gh a p articu lar ou tp u t. Valu es are exp ressed as in d ivid u al am p erages for each ou tp u t voltage. W ith th ese figu res, you can calcu late n ot on ly th e total am ou n t of p ower th e PSU can su p p ly, bu t also h ow m an y d evices u sin g th ose variou s voltages it can su p p ort. ■ Minim um Load Current. Th e sm allest am ou n t of cu rren t (in am p s) th at m u st be d rawn from a p articu lar ou tp u t for th at ou tp u t to fu n ction . If th e cu rren t d rawn from an ou tp u t falls below th e m in im u m , th e p ower su p p ly cou ld be d am aged or cou ld au tom atically sh u t d own . ■ Load Regulation (or V oltage Load Regulation). W h en th e cu rren t d rawn from a p articu lar ou tp u t in creases or d ecreases, th e voltage ch an ges sligh tly as well, u su ally in creasin g as th e cu rren t rises. Load regu lation is th e ch an ge in th e voltage for a p articu lar ou tp u t as it tran sition s from its m in im u m load to its m axim u m load (or vice versa). Valu es, exp ressed in term s of a +/ – p ercen tage, typ ically ran ge from +/ –1% to +/ –5% for th e +3.3, +5, an d +12v ou tp u ts. ■ Line Regulation. Th e ch an ge in ou tp u t voltage as th e AC in p u t voltage tran sition s from th e lowest to th e h igh est valu e of th e in p u t ran ge. A p ower su p p ly sh ou ld be cap able of h an d lin g an y AC voltage in its in p u t ran ge with a ch an ge in its ou tp u t of 1 p ercen t or less. ■ Efficiency. Th e rat io o f a PSU’s p o wer in p u t t o it s p o wer o u t p u t , exp ressed in t erm s o f a p ercen t age. Valu es o f 65–85% are co m m o n fo r p o wer su p p lies t o d ay. Th e rem ain in g 15–35% o f t h e p o wer in p u t is co n vert ed t o h eat d u rin g t h e AC/ DC co n versio n p ro cess. Alt h o u gh great er efficien cy m ean s less h eat in sid e t h e co m p u t er (always a go o d t h in g) an d lo wer elect ric b ills, it sh o u ld n o t b e

Power Supply Function and Operation

em p h asized at t h e exp en se o f p recisio n , as evid en ced in t h e PSU’s lo ad regu lat io n an d o t h er p aram et ers. ■ Ripple (or Ripple and Noise, or AC Ripple, or PARD [Periodic and Random Deviation]). Th e average voltage of all AC com p on en ts’ effects on th e p ower su p p ly’s ou tp u ts, m easu red in m illivolts p eak-to-p eak (RMS) for each ou tp u t voltage. Th e effects can be cau sed by in tern al switch in g tran sien ts, feed th rou gh of th e rectified lin e freq u en cy, an d oth er ran d om n oise. Pow er-Supply Cert ificat ions Man y agen cies arou n d th e world certify electric an d electron ic com p on en ts for safety an d q u ality. Th e m ost com m on ly kn own agen cy in th e Un ited States is Un d erwriters Laboratories, In c. (UL). UL stan d ard #1950; th e Standard for Safety of Inform ation Technology Equipm ent, Including Electrical Business Equipm ent, Third Edition; covers p ower su p p lies an d oth er PC com p on en ts. It is always a good id ea to p u rch ase p ower su p p lies an d oth er d evices th at are UL-certified . It h as often been said th at alth ou gh n ot every good p rod u ct is UL-certified , n o bad p rod u cts are. In Can ad a, electric an d electron ic p rod u cts are certified by th e Can ad ian Stan d ard s Agen cy (CSA). Th e Germ an eq u ivalen ts are TÜV Rh ein lan d an d VDE. NEMKO op erates in Norway. Th ese th ree agen cies are resp on sible for certification of p rod u cts th rou gh ou t Eu rop e. Power su p p ly m an u factu rers th at sell to an in tern ation al m arket sh ou ld h ave p rod u cts th at are certified at least by UL, th e CSA, an d TÜV—if n ot by all of th e agen cies listed , an d m ore. Ap art from UL-typ e certification s, m an y p ower-su p p ly m an u factu rers, even th e m ost rep u table on es, claim th at th eir p rod u cts h ave a Class B certification from th e Fed eral Com m u n ication s Com m ission , m ean in g th at th ey m eet FCC stan d ard s for electrom agn etic an d rad io freq u en cy in terferen ce (EMI/ RFI). Th is is a con ten tiou s p oin t, h owever, becau se th e FCC d oes n ot certify p ower su p p lies as in d ivid u al com p on en ts. Title 47 of th e Cod e of Fed eral Regu lation s, Part 15, Section 15.101(c) states as follows: “Th e FCC d oes NOT cu rren tly au th orize m oth erboard s, cases, an d in tern al p ower su p p lies. Ven d or claim s th at th ey are sellin g ‘FCC-certified cases’, ‘FCC-certified m oth erboard s’ or ‘FCC-certified in tern al p ower su p p lies’ are false.” In fact, an FCC certification can be issu ed collectively on ly to a base u n it con sistin g of a com p u ter case, m oth erboard , an d a p ower su p p ly. Th u s, a p ower su p p ly p u rp orted to be FCC-certified was actu ally certified alon g with a p articu lar case an d m oth erboard —n ot n ecessarily th e sam e case an d m oth erboard you are u sin g in you r system . Th is d oes n ot m ean , h owever, th at th e m an u factu rer is bein g d eceitfu l, or th at th e p ower su p p ly is in ferior. If an yth in g, th is m ean s th at wh en evalu atin g p ower su p p lies, you sh ou ld p lace less weigh t on th e FCC certification th an on oth er factors, su ch as UL certification . Pow er-Use Calculat ions W h en exp an d in g or u p grad in g you r PC, it is im p ortan t to be su re you r p ower su p p ly is cap able of p rovid in g su fficien t cu rren t to p ower all th e system ’s in tern al d evices. On e

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way to see wh eth er you r system is cap able of exp an sion is to calcu late th e levels of p ower d rain in th e d ifferen t system com p on en ts an d d ed u ct th e total from th e m axim u m p ower su p p lied by th e PSU. Th is calcu lation can h elp you d ecid e wh eth er you m u st u p grad e th e p ower su p p ly to a m ore cap able u n it. Un fortu n ately, th ese calcu lation s can be d ifficu lt to m ake becau se m an y m an u factu rers d o n ot p u blish p ower con su m p tion d ata for th eir p rod u cts. It can be d ifficu lt to get p ower-con su m p tion d ata for m an y +5v d evices, in clu d in g m oth erboard s an d ad ap ter card s. Moth erboard s can con su m e d ifferen t p ower levels, d ep en d in g on n u m erou s factors. Most m oth erboard s con su m e abou t 5 am p s or so, bu t try to get in form ation on th e on e you are u sin g. For ad ap ter card s, if you can fin d th e actu al sp ecification s for th e card , u se th ose figu res. To be on th e con servative sid e, h owever, I u su ally go by th e m axim u m available p ower levels set forth in th e resp ective bu s stan d ard s. For exam p le, con sid er th e p ower-con su m p tion figu res for com p on en ts in a m od ern PC, su ch as a d esktop or slim lin e system with a 200-watt p ower su p p ly rated for 20 am p s at +5v an d 8 am p s at +12v. Th e ISA sp ecification calls for a m axim u m of 2.0 am p s of +5v an d 0.175 am p s of +12v p ower for each slot in th e system . Most system s h ave eigh t slots, an d you can assu m e th at fou r are filled for th e p u rp oses of calcu latin g p ower d raw. Th e followin g calcu lation sh ows wh at h ap p en s wh en you su btract th e am ou n t of p ower n ecessary to ru n th e d ifferen t system com p on en ts: 5v Pow er: Less:

20.0 Am ps M otherboard –5.0 4 slots filled at 2.0 each –8.0 3 1/ 2- and 5 1/ 4-inch floppy drives –1.5 3 1/ 2-inch hard disk drive –0.5 CD-ROM drive –1.0

=Remaining power:

4.0 amps

12v Pow er:

8.0 Am ps

Less:

4 slots filled at 0.175 each –0.7 3 1/ 2-inch hard disk drive –1.0 3 1/ 2- and 5 1/ 4-inch floppy drives –1.0 Cooling fan –0.1 CD-ROM drive –1.0

=Remaining power:

4.2 amps

In th e p reced in g exam p le, everyth in g seem s all righ t for th e p resen t. W ith h alf th e slots filled , two flop p y d rives, an d on e h ard d isk, th e system still h as room for m ore. Problem s with th e p ower su p p ly cou ld com e u p , h owever, if th is system were exp an d ed to th e extrem e. W ith every slot filled an d two or m ore h ard d isks, th ere d efin itely wou ld be p roblem s with th e +5v cu rren t. However, th e +12v d oes seem to h ave room to sp are. You cou ld ad d a CD-ROM d rive or a secon d h ard d isk with ou t worryin g too m u ch abou t th e +12v p ower, bu t th e +5v p ower wou ld be strain ed .

Power Supply Function and Operation

If you an ticip ate load in g u p a system to th e extrem e—as in a h igh -en d m u ltim ed ia system , for exam p le—you m ay wan t to in vest in th e in su ran ce of a h igh er ou tp u t p ower su p p ly. For exam p le, a 250-watt su p p ly u su ally h as 25 am p s of +5v an d 10 am p s of +12v cu rren t, wh ereas a 300-watt u n it h as 32 am p s of +5v p ower. Th ese su p p lies en able you to fu lly load th e system an d are likely to be fou n d in fu ll-sized d esktop or tower case con figu ration s in wh ich th is typ e of exp an sion is exp ected . Moth erboard s can d raw an ywh ere from fou r to fifteen am p s or m ore of +5v p ower to ru n . In fact, a sin gle Pen tiu m 66MHz CPU d raws u p to 3.2 am p s of +5v p ower all by itself. A 200MHz Pen tiu m Pro CPU or 400MHz Pen tiu m II con su m es u p to 15 am p s. Con sid erin g th at system s with two or m ore p rocessors are n ow becom in g com m on , you cou ld h ave 30 am p s or m ore d rawn by th e p rocessors alon e. A m oth erboard su ch as th is—with two CPUs an d 128M or m ore of RAM for each CPU—m igh t d raw m ore th an 40 am p s all by itself. Very few “n o-n am e” p ower su p p lies can su p p ly th is kin d of cu rren t. For th ese ap p lication s, you sh ou ld con sid er on ly h igh -q u ality, h igh -cap acity p ower su p p lies from a rep u table m an u factu rer, su ch as PC Power an d Coolin g. In th ese calcu lation s, bu s slots are allotted m axim u m p ower in am p s, as sh own in Table 6.9. Table 6.9

M axim um Pow er Consum pt ion in Am ps per Bus Slot

Bus Type

+5v Pow er

+12v Pow er

+3.3v Pow er

ISA

2.0

0.175

N/ A

EISA

4.5

1.5

N/ A

VL-Bus

2.0

N/ A

N/ A

16-Bit M CA

1.6

0.175

N/ A

32-Bit M CA

2.0

0.175

N/ A

PCI

5

0.5

7.6

As you can see from th e table, ISA slots are allotted 2.0 am p s of +5v an d 0.175 am p of +12v p ower. Note th at th ese are m axim u m figu res. All card s d o n ot d raw th is m u ch p ower. If th e slot h as a VL-Bu s exten sion con n ector, an ad d ition al 2.0 am p s of +5v p ower are allowed for th e VL-Bu s. Flop p y d rives can vary in p ower con su m p tion , bu t m ost of th e n ewer 3 1/ 2-in ch d rives h ave m otors th at ru n on +5v cu rren t in ad d ition to th e logic circu its. Th ese d rives u su ally d raw 1.0 am p s of +5v p ower an d u se n o +12v at all. 5 1/ 4-in ch d rives u se stan d ard +12v m otors th at d raw abou t 1.0 am p s. Th ese d rives also req u ire abou t 0.5 am p s of +5v for th e logic circu its. Most coolin g fan s d raw abou t 0.1 am p s of +12v p ower, wh ich is n egligible. Typ ical 3 1/ 2-in ch h ard d isks tod ay d raw abou t 1 am p of +12v p ower to ru n th e m otors—an d on ly abou t 0.5 am p of +5v p ower for th e logic. 5 1/ 4-in ch h ard d isks, esp ecially th ose th at are fu ll-h eigh t, d raw m u ch m ore p ower. A typ ical fu ll-h eigh t h ard d rive d raws 2.0 am p s of +12v p ower an d 1.0 am p s of +5v p ower.

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An oth er p roblem with h ard d isks is th at th ey req u ire m u ch m ore p ower d u rin g th e sp in u p p h ase of op eration th an d u rin g n orm al op eration . In m ost cases, th e d rive d raws d ou ble th e +12v p ower d u rin g sp in u p , wh ich can be 4.0 am p s or m ore for th e fu ll-h eigh t d rives. Th is tap ers off to n orm al after th e d rive is sp in n in g. Th e figu res th at m ost m an u factu rers rep ort for m axim u m p ower su p p ly ou tp u t are fu ll d u ty-cycle figu res. Th e PSU can su p p ly th ese levels of p ower con tin u ou sly. You u su ally can exp ect a u n it th at con tin u ou sly su p p lies a given level of p ower to be cap able of exceed in g th is level for som e n on con tin u ou s am ou n t of tim e. A su p p ly u su ally can offer 50% greater ou tp u t th an th e con tin u ou s figu re in d icates for as lon g as on e m in u te. System s often u se th is cu sh ion to su p p ly th e n ecessary p ower to sp in u p a h ard d isk d rive. After th e d rive h as sp u n to fu ll sp eed , th e p ower d raw d rop s to a valu e with in th e system ’s con tin u ou s su p p ly cap abilities. Drawin g an yth in g over th e rated con tin u ou s figu re for an y exten d ed len gth of tim e cau ses th e p ower su p p ly to ru n h ot an d fail early, an d can also create n asty sym p tom s in th e system .

Tip If you are using internal SCSI hard drives, you can ease the startup load on your power supply. The key is to enable the SCSI drives Remote Start option, which causes the drive to start spinning only when it receives a startup command over the SCSI bus. The effect is that the drive remains stationary (drawing very little power) until the very end of the POST and spins up right when the SCSI portion of the POST is begun. If you have multiple SCSI drives, they all spin up sequentially based on their SCSI ID setting. This is designed so that only one drive is spinning up at any one time and so that no drives start spinning until the rest of the system has had time to start. This greatly eases the load on the power supply when you first power the system on. In most cases, you enable Remote Start through your SCSI host adapter’s setup program. This program may be supplied with the adapter on separate media, or it may be integrated into the adapter’s BIOS and activated with a specific key combination at boot time.

Th e biggest cau se of p ower-su p p ly overload p roblem s h as h istorically been fillin g u p th e exp an sion slots an d ad d in g m ore d rives. Mu ltip le h ard d rives, CD-ROM d rives, an d flop p y d rives can create q u ite a d rain on th e system p ower su p p ly. Make su re th at you h ave en ou gh +12v p ower to ru n all th e d rives you p lan to in stall. Tower system s can be esp ecially p roblem atic becau se th ey h ave so m an y d rive bays. Ju st becau se th e case h as room for th e d evices d oesn ’t m ean th e p ower su p p ly can su p p ort th em . Make su re you h ave en ou gh +5v p ower to ru n all you r exp an sion card s, esp ecially PCI card s. It p ays to be con servative, bu t rem em ber th at m ost card s d raw less th an th e m axim u m allowed . Tod ay’s n ewest p rocessors can h ave very h igh cu rren t req u irem en ts for th e +5 or +3.3volt su p p lies. W h en selectin g a p ower su p p ly for you r system , be su re to take in to accou n t an y fu tu re p rocessor u p grad es. Man y p eop le wait u n til an existin g com p on en t fails before th ey rep lace it with an u p grad ed version . If you are on a tigh t bu d get, th is “if it ain ’t broke, d on ’t fix it” attitu d e m ay be n ecessary. Power su p p lies, h owever, often d o n ot fail com p letely all at on ce; th ey

Leave It On or Turn It Off?

can fail in an in term itten t fash ion or allow flu ctu atin g p ower levels to reach th e system , wh ich resu lts in u n stable op eration . You m igh t be blam in g system locku p s on software bu gs wh en th e cu lp rit is an overload ed p ower su p p ly. If you h ave been ru n n in g you r origin al p ower su p p ly for a lon g tim e an d h ave u p grad ed you r system in oth er ways, you sh ou ld exp ect som e p roblem s. Alth ou gh th ere is certain ly an ap p rop riate p lace for th e exactin g p ower-con su m p tion calcu lation s you ’ve read abou t in th is section , a great m an y exp erien ced PC u sers p refer th e “d on ’t worry abou t it” p ower calcu lation m eth od . Th is tech n iq u e con sists of bu yin g a system with a good q u ality 300- or 350-watt p ower su p p ly (or in stallin g su ch a su p p ly you rself) an d th en u p grad in g th e system freely, with ou t con cern for p ower con su m p tion . Un less you p lan to bu ild a system with six SCSI d rives an d a d ozen oth er p erip h erals, you will p robably n ot exceed th e cap abilities of th e PSU, an d th is m eth od certain ly req u ires far less effort.

Leave It On or Turn It Off? Sh ou ld you tu rn off a system wh en it is n ot in u se? To an swer th is freq u en t q u estion , you sh ou ld u n d erstan d som e facts abou t electrical com p on en ts an d wh at m akes th em fail. Com bin e th is kn owled ge with in form ation on p ower con su m p tion , cost, an d safety, in ord er to com e to you r own con clu sion . Becau se circu m stan ces can vary, th e best an swer for you r own situ ation m igh t be d ifferen t th an for oth ers, d ep en d in g on you r p articu lar n eed s an d ap p lication s. Freq u en tly, p owerin g a system on an d off d oes cau se d eterioration an d d am age to th e com p on en ts. Th is seem s logical, bu t th e sim p le reason is n ot obviou s to m ost p eop le. Man y believe th at flip p in g system p ower on an d off freq u en tly is h arm fu l becau se it electrically “sh ocks” th e system . Th e real p roblem , h owever, is tem p eratu re or th erm al sh ock. As th e system warm s u p , th e com p on en ts exp an d ; an d as it cools off, th e com p on en ts con tract. In ad d ition , variou s m aterials in th e system h ave d ifferen t th erm al exp an sion coefficien ts, wh ich m ean s th at th ey exp an d an d con tract at d ifferen t rates. Over tim e, th erm al sh ock cau ses d eterioration in m an y areas of a system . From a p u re system -reliability viewp oin t, it is d esirable to in su late th e system from th erm al sh ock as m u ch as p ossible. W h en a system is tu rn ed on , th e com p on en ts go from am bien t (room ) tem p eratu re to as h igh as 185 d egrees F (85 d egrees C) with in 30 m in u tes or less. W h en you tu rn th e system off, th e sam e th in g h ap p en s in reverse, an d th e com p on en ts cool back to am bien t tem p eratu re in a sh ort p eriod of tim e. Th erm al exp an sion an d con traction rem ain th e sin gle largest cau se of com p on en t failu re. Ch ip cases can sp lit, allowin g m oistu re to en ter an d con tam in ate th em . Delicate in tern al wires an d con tacts can break, an d circu it board s can d evelop stress cracks. Su rface-m ou n ted com p on en ts exp an d an d con tract at d ifferen t rates th an th e circu it board th ey are m ou n ted on , wh ich cau ses en orm ou s stress at th e sold er join ts. Sold er

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join ts can fail d u e to th e m etal h ard en in g from th e rep eated stress, resu ltin g in cracks in th e join t. Com p on en ts th at u se h eat sin ks, su ch as p rocessors, tran sistors, or voltage regu lators, can overh eat an d fail becau se th e th erm al cyclin g cau ses h eat sin k ad h esives to d eteriorate, breakin g th e th erm ally con d u ctive bon d between th e d evice an d th e h eat sin k. Th erm al cyclin g also cau ses socketed d evices an d con n ection s to loosen or “creep ,” wh ich can cau se a variety of in term itten t con tact failu res. Th erm al exp an sion an d con traction affect n ot on ly ch ip s an d circu it board s, bu t also th in gs su ch as h ard d isk d rives. Most h ard d rives tod ay h ave sop h isticated th erm al com p en sation rou tin es th at m ake ad ju stm en ts in h ead p osition relative to th e exp an d in g an d con tractin g p latters. Most d rives p erform th is th erm al com p en sation rou tin e on ce every five m in u tes for th e first 30 m in u tes th e d rive is ru n n in g, an d th en every 30 m in u tes th ereafter. In m an y d rives, th is p roced u re can be h eard as a rap id “tick-tick-tick-tick” sou n d . In essen ce, an yth in g you can d o to keep th e system at a con stan t tem p eratu re p rolon gs th e life of th e system , an d th e best way to accom p lish th is is to leave th e system eith er p erm an en tly on or off. Of cou rse, if th e system is n ever tu rn ed on in th e first p lace, it sh ou ld last a lon g tim e in d eed ! Now, I am n ot sayin g th at you sh ou ld leave all system s on 24 h ou rs a d ay. A system p owered on an d left u n atten d ed can be a fire h azard (I h ave h ad m on itors sp on tan eou sly catch fire—lu ckily, I was th ere at th e tim e), is a d ata secu rity risk (from clean in g crews an d oth er n octu rn al visitors), can be easily d am aged if m oved wh ile ru n n in g, an d wastes electrical en ergy. I cu rren tly p ay $0.11 for a kilowatt-h ou r of electricity. A typ ical d esktop -style PC with d isp lay con su m es at least 300 watts (0.3 kilowatt) of electricity (an d th at is a con servative estim ate). Th is m ean s th at it wou ld cost 3.3 cen ts to ru n m y typ ical PC for an h ou r. Mu ltip lyin g by 168 h ou rs in a week m ean s th at it wou ld cost $5.54 p er week to ru n th is PC con tin u ou sly. If th e PC were tu rn ed on at 9 a.m . an d off at 5 p .m ., it wou ld be on on ly 40 h ou rs p er week an d wou ld cost on ly $1.32—a savin gs of $4.22 p er week! Mu ltip ly th is savin gs by 100 system s, an d you are savin g $422 p er week. Mu ltip ly th is by 1,000 system s, an d you are savin g $4,220 p er week! Usin g system s certified u n d er th e n ew EPA En ergy Star p rogram (th at is, “Green ” PCs) wou ld accou n t for an ad d ition al savin gs of arou n d $1 p er system p er week—or $1,000 p er week for 1,000 system s. Th e great th in g abou t En ergy Star system s is th at th e savin gs are even greater if th e system s are left on for lon g p eriod s of tim e becau se th e p ower m an agem en t rou tin es are au tom atic. Based on th ese facts, m y recom m en d ation s are th at you p ower th e system s on at th e begin n in g of th e workd ay an d off at th e en d of th e workd ay. Do n ot p ower th e system s off for lu n ch , breaks, or an y oth er sh ort d u ration s of tim e. Servers, of cou rse, sh ou ld be

Power M anagement

left on con tin u ou sly. Th is seem s to be th e best com p rom ise of system lon gevity with p u re econ om ics.

Pow er M anagem ent As th e stan d ard PC con figu ration h as grown to in clu d e cap abilities form erly con sid ered op tion s, th e p ower req u irem en ts of th e system h ave in creased stead ily. Larger d isp lays, CD-ROM d rives, an d au d io ad ap ters all n eed m ore p ower to ru n , an d th e cost of op eratin g a PC rises stead ily. To ad d ress th ese con cern s, several p rogram s an d stan d ard s are n ow bein g d evelop ed th at are in ten d ed to red u ce th e p ower n eed ed to ru n a PC as m u ch as p ossible. For stan d ard d esktop system s, p ower m an agem en t is a m atter of econ om y an d con ven ien ce. By tu rn in g off sp ecific com p on en ts of th e PC wh en th ey are n ot in u se, you can red u ce th e electric bill an d avoid h avin g to p ower th e com p u ter u p an d d own m an u ally. For p ortable system s, p ower m an agem en t is far m ore im p ortan t. Ad d in g CD-ROMs, sp eakers, an d oth er com p on en ts to a lap top or n otebook com p u ter red u ces wh at is in m an y cases a sh ort battery life even fu rth er. By ad d in g n ew p ower m an agem en t tech n ology, a p ortable system can su p p ly p ower on ly to th e com p on en ts it actu ally n eed s to ru n , th u s exten d in g th e life of th e battery ch arge. Energy St ar Syst em s Th e EPA h as started a certification p rogram for en ergy-efficien t PCs an d p erip h erals. To be a m em ber of th is p rogram , th e PC or d isp lay m u st d rop to a p ower d raw at th e ou tlet of 30 watts or less d u rin g p eriod s of in activity. System s th at con form to th is sp ecification get to wear th e En ergy Star logo. Th is is a volu n tary p rogram ; h owever, m an y PC m an u factu rers are fin d in g th at it h elp s th em sell th eir system s if th ey can ad vertise th ese system s as en ergy-efficien t. On e p roblem with th is typ e of system is th at th e m oth erboard an d d isk d rives literally can go to sleep, wh ich m ean s th ey can en ter a stan d by or sleep m od e, in wh ich th ey d raw very little p ower. Th is cau ses h avoc with som e of th e old er p ower su p p lies becau se th e low p ower d raw d oes n ot p rovid e en ou gh of a load for th em to fu n ction p rop erly. Most of th e n ewer su p p lies on th e m arket, wh ich are d esign ed to work with th ese system s, h ave a very low m in im u m load sp ecification . I su ggest th at you en su re th at th e m in im u m load will be p rovid ed by th e eq u ip m en t in you r system if you bu y a p ower su p p ly u p grad e. Oth erwise, wh en th e PC goes to sleep , it m ay take a p ower switch cycle to wake it u p again . Th is p roblem wou ld be m ost n oticeable if you in vested in a very h igh ou tp u t su p p ly an d u sed it in a system th at d raws very little p ower to begin with . Advanced Pow er M anagem ent Ad van ced Power Man agem en t (APM) is a sp ecification join tly d evelop ed by In tel an d Microsoft th at d efin es a series of in terfaces between p ower m an agem en t-cap able h ard ware an d a com p u ter’s op eratin g system . W h en it is fu lly im p lem en ted , APM can

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au tom atically switch a com p u ter between five states, d ep en d in g on th e system ’s cu rren t activity. Each state rep resen ts a fu rth er red u ction in p ower u se, accom p lish ed by p lacin g u n u sed com p on en ts in to a low-p ower m od e. Th e five system states are as follows: ■ Full On. Th e system is com p letely op eration al, with n o p ower m an agem en t occu rrin g. ■ APM Enabled. Th e system is op eration al, with som e d evices bein g p ower m an aged . Un u sed d evices m ay be p owered d own an d th e CPU clock slowed or stop p ed . ■ APM Standby. Th e system is n ot op eration al, with m ost d evices in a low p ower state. Th e CPU clock m ay be slowed or stop p ed , bu t op eration al p aram eters are retain ed in m em ory. W h en triggered by a sp ecific u ser or system activities, th e system can retu rn to th e APM En abled state alm ost in stan tan eou sly. ■ APM Suspend. Th e system is n ot op eration al, with m ost d evices u n p owered . Th e CPU clock is stop p ed an d op eration al p aram eters are saved to d isk for later restoration . W h en triggered by a wakeu p even t, th e system retu rn s to th e APM En abled state relatively slowly. ■ Off. Th e system is n ot op eration al. Th e p ower su p p ly is off. APM req u ires su p p ort from both h ard ware an d software to fu n ction . In th is ch ap ter, you ’ve alread y seen h ow ATX-style p ower su p p lies can be con trolled by software com m an d s u sin g th e Power_On sign al an d th e six-p in op tion al p ower con n ector. Man u factu rers are also in tegratin g th e sam e sort of con trol featu res in to oth er system com p on en ts, su ch as m oth erboard s, m on itors, an d d isk d rives. Op eratin g system s th at su p p ort APM, su ch as W in d ows 9x, trigger p ower m an agem en t even ts by m on itorin g th e activities p erform ed by th e com p u ter u ser an d th e ap p lication s ru n n in g on th e system . However, th e OS d oes n ot ad d ress th e p ower m an agem en t cap abilities of th e h ard ware d irectly. A system can h ave m an y d ifferen t h ard ware d evices an d m an y d ifferen t software fu n ction s p articip atin g in APM fu n ction s, wh ich m akes com m u n ication d ifficu lt. To ad d ress th is p roblem , both th e op eratin g system an d th e h ard ware h ave an abstraction layer th at facilitates com m u n ication between th e variou s elem en ts of th e APM arch itectu re. Th e op eratin g system ru n s an APM d river th at com m u n icates with th e variou s ap p lication s an d software fu n ction s th at trigger p ower m an agem en t activities, wh ile th e system ’s APM-cap able h ard ware d evices all com m u n icate with th e system BIOS. Th e APM d river an d th e BIOS com m u n icate d irectly, com p letin g th e lin k between th e OS an d th e h ard ware. Th u s, for APM to fu n ction , th ere m u st be su p p ort for th e stan d ard bu ilt in to th e system ’s in d ivid u al h ard ware d evices, th e system BIOS, an d th e op eratin g system (wh ich in clu d es th e APM d river). W ith ou t all of th ese com p on en ts, APM activities can n ot occu r.

Power Supply Problems

Tip If, for any reason, you find that power management activities cause problems on your system, such as operating system freeze-ups or hardware malfunctions, the easiest way to disable APM is through the system BIOS. M ost BIOSs that support APM include an option to disable it. This breaks the chain of communication between the operating system and the hardware, causing all power management activities to cease. Although it is also possible to achieve the same end by removing the APM driver from the operating system, Windows 9x’s Plug-and-Play (PnP) feature detects the system’s APM capabilities whenever you restart the computer and attempts to reinstall the APM driver.

Pow er Supply Problem s A weak or in ad eq u ate p ower su p p ly can p u t a d am p er on you r id eas for system exp an sion . Som e system s are d esign ed with beefy p ower su p p lies, as if to an ticip ate a great d eal of system ad d -on s an d exp an sion com p on en ts. Most d esktop or tower system s are bu ilt in th is m an n er. Som e system s h ave in ad eq u ate p ower su p p lies from th e start, h owever, an d can n ot ad eq u ately service th e p ower-h u n gry op tion s you m igh t wan t to ad d . Th e wattage ratin g can som etim es be very m islead in g. Not all 300-watt su p p lies are created th e sam e. Peop le fam iliar with h igh -en d au d io system s kn ow th at som e watts are better th an oth ers. Ch eap p ower su p p lies m ay in fact p u t ou t th e rated p ower, bu t wh at abou t n oise an d d istortion ? Som e of th e su p p lies are u n d er-en gin eered to ju st barely m eet th eir sp ecification s, wh ereas oth ers m ay greatly exceed th eir sp ecification s. Man y of th e ch eap er su p p lies su p p ly n oisy or u n stable p ower, wh ich can cau se n u m erou s p roblem s with th e system . An oth er p roblem with u n d er-en gin eered p ower su p p lies is th at th ey can ru n h ot an d force th e system to d o so as well. Th e rep eated h eatin g an d coolin g of solid -state com p on en ts even tu ally cau ses a com p u ter system to fail, an d en gin eerin g p rin cip les d ictate th at th e h otter a PC’s tem p eratu re, th e sh orter its life. Man y p eop le recom m en d rep lacin g th e origin al su p p ly in a system with a h eavier d u ty m od el, wh ich solves th e p roblem . Becau se p ower su p p lies com e in com m on form factors, fin d in g a h eavy-d u ty rep lacem en t for m ost system s is easy, as is th e in stallation p rocess. Som e of th e available rep lacem en t p ower su p p lies h ave h igh er-cap acity coolin g fan s th an th e origin als, wh ich can greatly p rolon g system life an d m in im ize overh eatin g p roblem s, esp ecially for th e n ewer, h otter-ru n n in g p rocessors. If system n oise is a p roblem , m od els with sp ecial fan s can ru n m ore q u ietly th an th e stan d ard m od els. Th ese PSUs often u se larger-d iam eter fan s th at sp in m ore slowly, so th ey ru n m ore q u ietly an d m ove th e sam e am ou n t of air as th e sm aller fan s. PC Power an d Coolin g sp ecializes in h eavy-d u ty an d q u iet su p p lies; Astec h as several h eavy-d u ty m od els as well. Ven tilation in a system is also im p ortan t. You m u st en su re ad eq u ate airflow to cool th e h otter item s in th e system . Man y p rocessors tod ay u se p assive h eat sin ks th at req u ire a stead y stream of air to cool th e ch ip . If th e p rocessor h eat sin k h as its own fan , th is is n ot m u ch of a con cern . If you h ave free exp an sion slots, it’s a good id ea to sp ace ou t th e

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board s in you r system to p erm it airflow between th em . Place th e h ottest ru n n in g board s n earest th e fan or th e ven tilation h oles in th e system . Make su re th at th ere is ad eq u ate airflow arou n d th e h ard d isk d rive, esp ecially for th ose th at sp in at h igh rates of sp eed . Som e h ard d isks can gen erate q u ite a bit of h eat d u rin g op eration . If th e h ard d isks overh eat, d ata can be lost. Always m ake su re you ru n you r com p u ter with th e case cover on , esp ecially if you h ave a load ed system . Rem ovin g th e cover can actu ally cau se a system to overh eat. W ith th e cover off, th e p ower su p p ly fan n o lon ger d raws air th rou gh th e system . In stead , th e fan en d s u p coolin g th e su p p ly on ly, an d th e rest of th e system m u st be cooled by sim p le con vection . Alth ou gh m ost system s d o n ot im m ed iately overh eat for th is reason , several of m y own system s, esp ecially th ose th at are fu lly exp an d ed , h ave overh eated with in 15 to 30 m in u tes wh en ru n with th e case cover off. In ad d ition , be su re th at an y em p ty slot p osition s h ave th e filler brackets in stalled . If you leave th ese brackets off after rem ovin g a card , th e resu ltan t h ole in th e case d isru p ts th e in tern al airflow an d m ay cau se h igh er in tern al tem p eratu res. If you exp erien ce in term itten t p roblem s th at you su sp ect are related to overh eatin g, a h igh er-cap acity rep lacem en t p ower su p p ly is u su ally th e best cu re. Sp ecially d esign ed su p p lies with ad d ition al coolin g fan cap acity also can h elp . At least on e com p an y sells a d evice called a fan card, bu t I am n ot con vin ced th ese are a good id ea. Un less th e fan is p osition ed to d raw air to or from ou tsid e th e case, all it d oes is blow h ot air arou n d in sid e th e system an d p rovid e a sp ot coolin g effect for an yth in g it is blowin g on . In fact, ad d in g fan s in th is m an n er con tribu tes to th e overall h eat in sid e th e system becau se th e fan con su m es p ower an d gen erates h eat. CPU-m ou n ted fan s are an excep tion becau se th ey are d esign ed on ly for sp ot coolin g of th e CPU. Man y of th e n ewer p rocessors ru n so m u ch h otter th an th e oth er com p on en ts in th e system th at a con ven tion al fin n ed alu m in u m h eat sin k can n ot d o th e job. In th is case, a sm all fan p laced d irectly over th e p rocessor p rovid es a sp ot coolin g effect th at keep s th e p rocessor tem p eratu res d own . On e d rawback to th ese active p rocessor coolin g fan s is th at th e p rocessor overh eats in stan tly an d can even be d am aged if th ey fail. W h en ever p ossible, try to u se th e biggest p assive (fin n ed alu m in u m ) h eat sin k you can fin d an d p u rch ase a CPU fan from a rep u table ven d or.

Pow er Supply Troubleshoot ing Trou blesh ootin g th e p ower su p p ly basically m ean s isolatin g th e su p p ly as th e cau se of p roblem s with in a system an d , if n ecessary, rep lacin g it.

Caut ion It is rarely recommended that an inexperienced user open a power supply to make repairs because of the dangerous high voltages present. Even when unplugged, power supplies can retain dangerous voltage and must be discharged (like a monitor) before service. Such internal repairs are beyond the scope of this book and are specifically not recommended unless the technician knows what he or she is doing.

Power Supply Troubleshooting

Man y sym p tom s lead m e to su sp ect th at th e p ower su p p ly in a system is failin g. Th is can som etim es be d ifficu lt for an in exp erien ced tech n ician to see becau se at tim es th ere ap p ears to be little con n ection between th e sym p tom an d th e cau se—th e p ower su p p ly. For exam p le, in m an y cases a “p arity ch eck” error m essage can in d icate a p roblem with th e p ower su p p ly. Th is m ay seem stran ge becau se th e p arity ch eck m essage sp ecifically refers to m em ory th at h as failed . Th e con n ection is th at th e p ower su p p ly p owers th e m em ory, an d m em ory with in ad eq u ate p ower fails. It takes som e exp erien ce to kn ow wh en th is typ e of failu re is p ower related , n ot cau sed by th e m em ory. On e clu e is th e rep eatability of th e p roblem . If th e p arity ch eck m essage (or oth er p roblem ) ap p ears freq u en tly an d id en tifies th e sam e m em ory location each tim e, I wou ld su sp ect d efective m em ory is th e p roblem . However, if th e p roblem seem s ran d om , or if th e m em ory location th e error m essage cites as h avin g failed seem s ran d om , I wou ld su sp ect im p rop er p ower as th e cu lp rit. Th e followin g is a list of PC p roblem s th at often are p ower su p p ly–related : ■ An y p ower-on or system startu p failu res or locku p s. ■ Sp on tan eou s rebootin g or in term itten t locku p s d u rin g n orm al op eration . ■ In term itten t p arity ch eck or oth er m em ory-typ e errors. ■ Hard d isk an d fan sim u ltan eou sly failin g to sp in (n o +12v). ■ Overh eatin g d u e to fan failu re. ■ Sm all brown ou ts cau se th e system to reset. ■ Electric sh ocks felt on th e system case or con n ectors. ■ Sligh t static d isch arges d isru p t system op eration . In fact, ju st abou t an y in term itten t system p roblem can be cau sed by th e p ower su p p ly. I always su sp ect th e su p p ly wh en flaky system op eration is a sym p tom . Of cou rse, th e followin g fairly obviou s sym p tom s p oin t righ t to th e p ower su p p ly as a p ossible cau se: ■ System is com p letely d ead (n o fan , n o cu rsor) ■ Sm oke ■ Blown circu it breakers If you su sp ect a p ower su p p ly p roblem , som e of th e sim p le m easu rem en ts an d th e m ore sop h isticated tests ou tlin ed in th is section can h elp you d eterm in e wh eth er th e p ower su p p ly is at fau lt. Becau se th ese m easu rem en ts m ay n ot d etect som e in term itten t failu res, you m igh t h ave to u se a sp are p ower su p p ly for a lon g-term evalu ation . If th e sym p tom s an d p roblem s d isap p ear wh en a “kn own good ” sp are u n it is in stalled , you h ave fou n d th e sou rce of you r p roblem .

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Digit al M ult i-M et ers On e sim p le test you can p erform on a p ower su p p ly is to ch eck th e ou tp u t voltages. Th is sh ows wh eth er a p ower su p p ly is op eratin g correctly an d wh eth er th e ou tp u t voltages are with in th e correct toleran ce ran ge. Note th at you m u st m easu re all voltages with th e p ower su p p ly con n ected to a p rop er load , wh ich u su ally m ean s testin g wh ile th e p ower su p p ly is still in stalled in th e system . Select ing a M et er. You n eed a sim p le Digital Multi-Meter (DMM) or Digital V olt-Ohm Meter (DV OM) to p erform voltage an d resistan ce ch ecks on electron ic circu its (see Figu re 6.10). You sh ou ld u se on ly a DMM in stead of th e old er n eed le-typ e m u lti-m eters becau se th e old er m eters work by in jectin g a 9v sign al in to th e circu it wh en m easu rin g resistan ce, wh ich d am ages m ost com p u ter circu its. A DMM u ses a m u ch sm aller voltage (u su ally 1.5v) wh en m akin g resistan ce m easu rem en ts, wh ich is safe for electron ic eq u ip m en t. You can get a good DMM with m an y d ifferen t featu res from several sou rces. I p refer th e sm all p ocket-sized m eters for com p u ter work becau se th ey are easy to carry arou n d . Som e featu res to look for in a good DMM are as follows: ■ Pocket size. Th is is self-exp lan atory, bu t sm all m eters are available th at h ave m an y, if n ot all, th e featu res of larger on es. Th e elaborate featu res fou n d on som e of th e larger m eters are n ot really n eed ed for com p u ter work. ■ Overload protection. Th is m ean s th at if you p lu g th e m eter in to a voltage or cu rren t beyon d th e m eter’s cap ability to m easu re, th e m eter p rotects itself from d am age. Ch eap er m eters lack th is p rotection an d can be easily d am aged by read in g cu rren t or voltage valu es th at are too h igh . ■ Autoranging. Th is m ean s th at th e m eter au tom atically selects th e p rop er voltage or resistan ce ran ge wh en m akin g m easu rem en ts. Th is is p referable to th e m an u al ran ge selection ; h owever, really good m eters offer both au toran gin g cap ability an d a m an u al ran ge overrid e. ■ Detachable probe leads. Th e lead s can be easily d am aged , an d som etim es a variety of d ifferen tly sh ap ed p robes are req u ired for d ifferen t tests. Ch eap er m eters h ave th e lead s p erm an en tly attach ed , wh ich m ean s th at you can n ot easily rep lace th em . Look for a m eter with d etach able lead s th at p lu g in to th e m eter. ■ Audible continuity test. Alth ou gh you can u se th e oh m scale for testin g con tin u ity (0 oh m s in d icates con tin u ity), a con tin u ity test fu n ction cau ses th e m eter to p rod u ce a beep n oise wh en con tin u ity exists between th e m eter test lead s. By u sin g th e sou n d , you can q u ickly test cable assem blies an d oth er item s for con tin u ity. After you u se th is featu re, you will n ever wan t to u se th e oh m s d isp lay for th is p u rp ose again . ■ Autom atic power off. Th ese m eters ru n on batteries, an d th e batteries can easily be worn d own if th e m eter is accid en tally left on . Good m eters h ave an au tom atic sh u toff th at tu rn s off th e u n it wh en it sen ses n o read in gs for a p red eterm in ed p eriod of tim e.

Power Supply Troubleshooting

■ Autom atic display hold. Th is featu re en ables you to h old th e last stable read in g on th e d isp lay even after th e read in g is taken . Th is is esp ecially u sefu l if you are tryin g to work in a d ifficu lt-to-reach area sin gle-h an d ed ly. ■ Minim um and m axim um trap. Th is featu re en ables th e m eter to trap th e lowest an d h igh est read in gs in m em ory an d h old th em for later d isp lay, wh ich is esp ecially u sefu l if you h ave read in gs th at are flu ctu atin g too q u ickly to see on th e d isp lay.

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COV

V0A

FIG. 6.10 A typ ical Digital Mu lti-Meter. Alth ou gh you can get a basic p ocket DMM for as little as $20, on e with all of th ese featu res is p riced in th e $100–$200 ran ge. Rad io Sh ack carries som e n ice in exp en sive u n its, an d you can p u rch ase th e h igh -en d m od els from electron ics su p p ly h ou ses, su ch as Newark or Digi-Key. M easuring Volt age. To m easu re voltages on a system th at is op eratin g, you m u st u se a tech n iq u e called back probing on th e con n ectors. You can n ot d iscon n ect an y of th e con n ectors wh ile th e system is ru n n in g, so you m u st m easu re with everyth in g con n ected . Nearly all th e con n ectors you n eed to p robe h ave op en in gs in th e back wh ere th e wires en ter th e con n ector. Th e m eter p robes are n arrow en ou gh to fit in to th e con n ector alon gsid e th e wire an d m ake con tact with th e m etal term in al in sid e. Th e tech n iq u e is called back probing becau se you are p robin g th e con n ector from th e back. You m u st u se th is back p robin g tech n iq u e to p erform virtu ally all of th e followin g m easu rem en ts. To test a p ower su p p ly for p rop er ou tp u t, ch eck th e voltage at th e Power_Good p in (P8-1 on AT, Baby AT, an d LPX su p p lies; p in 8 on th e ATX-typ e con n ector) for +3v to +6v of p ower. If th e m easu rem en t is n ot with in th is ran ge, th e system n ever sees th e Power_Good sign al an d th erefore d oes n ot start or ru n p rop erly. In m ost cases, th e p ower su p p ly is bad an d m u st be rep laced . Con tin u e by m easu rin g th e voltage ran ges of th e p in s on th e m oth erboard an d d rive p ower con n ectors. If you are m easu rin g voltages for testin g p u rp oses, an y read in g with in 10% of th e sp ecified voltage is con sid ered accep table, alth ou gh m ost

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m an u factu rers of h igh -q u ality p ower su p p lies sp ecify a tigh ter 5% toleran ce. For ATX p ower su p p lies, th e sp ecification req u ires th at voltages m u st be with in 5% of th e ratin g, excep t for th e 3.3v cu rren t, wh ich m u st be with in 4%.

Desired Volt age

Loose Tolerance M in. ( –10% ) M ax. ( +8% )

Tight Tolerance M in. ( –5% ) M ax. ( +5% )

+3.3v

2.97v

3.63v

3.135

+/ –5.0v

4.5v

5.4v

4.75

5.25

+/ –12.0v

10.8v

12.9v

11.4

12.6

3.465

Th e Power_Good sign al h as toleran ces th at are d ifferen t from th e oth er sign als, alth ou gh it is n om in ally a +5v sign al in m ost system s. Th e trigger p oin t for Power_Good is abou t +2.5v, bu t m ost system s req u ire th e sign al voltage to be with in th e toleran ces listed : Signal

M inim um

M axim um

Power_Good (+5v)

3.0v

6.0v

Rep lace th e p ower su p p ly if th e voltages you m easu re are ou t of th ese ran ges. Again , it is worth n otin g th at an y an d all p ower-su p p ly tests an d m easu rem en ts m u st be m ad e with th e p ower su p p ly p rop erly load ed , wh ich u su ally m ean s th at it m u st be in stalled in a system an d th e system m u st be ru n n in g. Specialized Test Equipm ent You can u se several typ es of sp ecialized test gear to test p ower su p p lies m ore effectively. Becau se th e p ower su p p ly is on e of th e m ost failu re-p ron e item s in PCs tod ay, it is wise to h ave th ese sp ecialized item s if you service m an y PC system s. Load Resist ors for Bench Test ing a Pow er Supply. Ben ch testin g a p ower su p p ly req u ires som e sp ecial setu p becau se all PC p ower su p p lies req u ire a load to op erate. Variable Volt age Transform er. W h en testin g p ower su p p lies, it is som etim es d esirable to sim u late d ifferen t AC voltage con d ition s at th e wall socket to observe h ow th e su p p ly reacts. A variable voltage transform er is a u sefu l test d evice for ch eckin g p ower su p p lies becau se it en ables you to exercise con trol over th e AC lin e voltage u sed as in p u t for th e p ower su p p ly (see Figu re 6.11). Th is d evice con sists of a large tran sform er m ou n ted in a h ou sin g with a d ial in d icator th at con trols th e ou tp u t voltage. You p lu g th e lin e cord from th e tran sform er in to th e wall socket an d p lu g th e PC p ower cord in to th e socket p rovid ed on th e tran sform er. Th e kn ob on th e tran sform er can be u sed to ad ju st th e AC lin e voltage received by th e PC. Most variable tran sform ers can ad ju st th eir AC ou tp u t from 0v to 140v, n o m atter wh at th e AC in p u t (wall socket) voltage is. Som e can cover a ran ge from 0v to 280v as well. You can u se th e tran sform er to sim u late brown ou t con d ition s, en ablin g you to observe th e PC’s resp on se. Th u s, you can ch eck a p ower su p p ly for p rop er Power_Good sign al op eration , am on g oth er th in gs.

Repairing the Power Supply

OHMITE 60

70

80 90

50

100

40

110 30 120 20 130

10 0

ON

140

OFF

FIG. 6.11 A variable voltage tran sform er. By ru n n in g th e PC an d d rop p in g th e voltage u n til th e PC sh u ts d own , you can see h ow m u ch “reserve” is in th e p ower su p p ly for h an d lin g a brown ou t or oth er voltage flu ctu ation s. If you r tran sform er can ou tp u t voltages in th e 200v ran ge, you can test th e cap ability of th e p ower su p p ly to ru n on foreign voltage levels. A p rop erly fu n ction in g su p p ly sh ou ld op erate between 90v to 135v bu t sh ou ld sh u t d own clean ly if th e voltage is ou tsid e th at ran ge. On e in d ication of a p roblem is seein g “p arity ch eck” typ e error m essages wh en you d rop th e voltage to 80v. Th is in d icates th at th e Power_Good sign al is n ot bein g with d rawn before th e p ower su p p ly ou tp u t to th e PC fails. Th e PC sh ou ld sim p ly stop op eratin g as th e Power_Good sign al is with d rawn , cau sin g th e system to en ter a con tin u ou s reset loop . Variable voltage tran sform ers are sold by a n u m ber of electron ic p arts su p p ly h ou ses, su ch as Newark an d Digi-Key. You sh ou ld exp ect to p ay an ywh ere from $100 to $300 for th is d evice.

Repairing t he Pow er Supply Hard ly an yon e actu ally rep airs p ower su p p lies an ym ore, p rim arily becau se it is u su ally ch eap er sim p ly to rep lace th e su p p ly with a n ew on e. Even h igh -q u ality p ower su p p lies are n ot th at exp en sive wh en com p ared to th e labor req u ired to rep air th em . A d efective p ower su p p ly is u su ally d iscard ed u n less it h ap p en s to be on e of th e h igh erq u ality or m ore exp en sive u n its. In th at case, it is u su ally wise to sen d th e su p p ly ou t to a com p an y th at sp ecializes in rep airin g p ower su p p lies an d oth er com p on en ts. Th ese com p an ies u su ally p rovid e wh at is called depot repair, wh ich m ean s you sen d th e su p p ly to th em ; th ey rep air it an d retu rn it to you . If tim e is of th e essen ce, m ost of th e d ep ot

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rep air com p an ies im m ed iately sen d you a fu n ction al eq u ivalen t to you r d efective su p p ly an d take you rs in as a core ch arge. Dep ot rep air is th e recom m en d ed way to service m an y PC com p on en ts, su ch as p ower su p p lies, m on itors, an d p rin ters. If you take you r PC in to a con ven tion al service ou tlet, th ey often d eterm in e wh ich com p on en t h as th e p roblem an d sen d it ou t to be d ep ot rep aired . You can d o th at you rself an d save th e m arku p th at th e rep air sh op n orm ally ch arges in su ch cases. For th ose with exp erien ce arou n d h igh voltages, it m igh t be p ossible to rep air a failin g su p p ly with two relatively sim p le op eration s; h owever, th ese req u ire op en in g th e su p p ly. I d o n ot recom m en d d oin g so bu t I m en tion it on ly as an altern ative to rep lacem en t in som e cases. Most m an u factu rers try to p reven t you from en terin g th e su p p ly by sealin g it with sp ecial tam p er-p roof Torx screws. Th ese screws u se th e fam iliar Torx star d river, bu t also h ave a tam p er-p reven tion p in in th e cen ter th at p reven ts a stan d ard d river from workin g. Most tool com p an ies su ch as Jen sen or Sp ecialized sell sets of TT (tam perproof Torx) bits, wh ich rem ove th e tam p er-resistan t screws. Oth er m an u factu rers rivet th e p ower su p p ly case sh u t, wh ich m ean s you m u st d rill ou t th e rivets to gain access.

Caut ion The manufacturers place these obstacles there for a reason—to prevent entry by those who are inexperienced with high voltage. Consider yourself warned!

Most p ower su p p lies h ave an in tern al fu se th at is p art of th e overload p rotection . If th is fu se is blown , th e su p p ly d oes n ot op erate. It is p ossible to rep lace th is fu se if you op en th e su p p ly. Be aware, h owever, th at in m ost cases an u n d erlyin g p ower su p p ly p roblem cau sed th e fu se to blow, an d rep lacin g it on ly cau ses it to blow again u n til you ad d ress th e root cau se of th e p roblem . In th is case, you are better off sen d in g th e u n it to a p rofession al d ep ot rep air com p an y. Th e ven d or list in Ap p en d ix A lists several com p an ies th at d o d ep ot rep air on p ower su p p lies an d oth er com p on en ts. PC p ower su p p lies h ave an in tern al voltage ad ju stm en t con trol th at th e m an u factu rer calibrates an d sets at th e factory. Over tim e, th e con d ition of som e of th e com p on en ts in th e su p p ly can ch an ge, th u s alterin g th e ou tp u t voltages. If th is is th e case, you m ay be able to access th e ad ju stm en t con trol an d tweak it to brin g th e voltages back to wh ere th ey sh ou ld be. Several ad ju stable con trols are in th e su p p ly—u su ally sm all variable resistors th at you can tu rn with a screwd river.

Caut ion You should use a nonconductive tool, such as a fiberglass or plastic screwdriver designed for this purpose. If you dropped a metal tool into an operating supply, dangerous sparks and possibly fire could result—not to mention the danger of electrocution and damage to the supply.

Obtaining Replacement Units

You also h ave to figu re ou t wh ich of th e ad ju stm en ts are for voltage an d wh ich are for each voltage sign al. Th is req u ires som e trial-an d -error testin g. You can m ark th e cu rren t p osition s of all th e resistors, begin m easu rin g a sin gle voltage sign al, an d try m ovin g each ad ju ster sligh tly u n til you see th e voltage ch an ge. If you m ove an ad ju ster an d n oth in g ch an ges, p u t it back to th e origin al p osition you m arked . Th rou gh th is p rocess, you can locate an d ad ju st each of th e voltages to th e stan d ard 3.3v, 5v, an d 12v levels.

Obt aining Replacem ent Unit s Most of th e tim e, it is sim p ly easier, safer, or less exp en sive (con sid erin g th e tim e an d m aterials in volved ) to rep lace th e p ower su p p ly rath er th an to rep air it. As m en tion ed earlier, rep lacem en t p ower su p p lies are available from m an y m an u factu rers. Before you can sh op for a su p p lier, h owever, you sh ou ld con sid er oth er p u rch asin g factors. Deciding on a Pow er Supply W h en you are sh op p in g for a n ew p ower su p p ly, you sh ou ld take several factors in to accou n t. First, con sid er th e p ower su p p ly’s sh ap e, or form factor. For exam p le, th e p ower su p p ly u sed in an AT-style system d iffers in size from th e on e u sed in a slim lin e com p u ter. Th e larger AT form factor p ower su p p lies sim p ly will n ot fit in to a slim lin e case. Ap art from electrical con sid eration s, p ower su p p ly form factors can d iffer p h ysically in th eir size, sh ap e, screw-h ole p osition s, con n ector typ e, n u m ber of con n ectors, fan location , an d switch p osition . However, system s th at u se th e sam e form factor can easily in terch an ge p ower su p p lies. W h en ord erin g a rep lacem en t su p p ly, you n eed to kn ow wh ich form factor you r system req u ires. Som e system s u se p rop rietary p ower su p p ly d esign s, wh ich m akes rep lacem en t m ore d ifficu lt. If a system u ses on e of th e com m on form factor p ower su p p lies, rep lacem en t u n its are available from h u n d red s of ven d ors. An u n fortu n ate u ser of a system with a n on stan d ard form factor su p p ly d oes n ot h ave th is kin d of ch oice an d m u st get a rep lacem en t from th e origin al m an u factu rer of th e system —an d u su ally p ay th rou gh th e n ose for th e u n it. Alth ou gh you can fin d stan d ard form factor su p p lies for u n d er $100, th e p rop rietary u n its from som e m an u factu rers ru n as h igh as $400 or m ore. PC bu yers often overlook th is an d d iscover too late th e con seq u en ces of h avin g n on stan d ard com p on en ts in a system . √√ See “ Power Supply Form Factors,” p. 393

IBM, for exam p le, u sed a n u m ber of PSU d esign s for th e PS/ 2 system s, with little in terch an geability p ossible between th em . Som e of th e su p p lies d o in terch an ge, esp ecially between an y th at h ave th e sam e or sim ilar cases, su ch as th e Mod el 60, 65, an d 80. An oth er exam p le of a PC m an u factu rer th at h as som etim es u sed p rop rietary p ower su p p ly d esign s is Com p aq . Som e of th eir system s d o n ot u se stan d ard form factor PSUs, wh ich m ean s th at Com p aq u su ally is th e on ly p lace from wh ich you can get a rep lacem en t. If th e p ower su p p ly in som e Com p aq Deskp ro system s “goes sou th ,” you can exp ect to p ay

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over $400 for a rep lacem en t, an d th e rep lacem en t u n it will be n o better or q u ieter th an th e on e you are rep lacin g. You h ave little ch oice in th e m atter becau se alm ost n o on e offers Com p aq form factor p ower su p p lies excep t for Com p aq . On e excep tion is th at PC Power an d Coolin g offers excellen t rep lacem en t p ower su p p lies for th e earlier Com p aq Portable system s an d for th e Deskp ro series. Th ese rep lacem en t p ower su p p lies h ave h igh er-ou tp u t p ower levels th an th e origin al su p p lies from Com p aq an d cost m u ch less. Sources for Replacem ent Pow er Supplies Becau se on e of th e m ost failu re-p ron e item s in PC system s is th e p ower su p p ly, I am often asked to recom m en d a rep lacem en t. Literally h u n d red s of com p an ies m an u factu re PC p ower su p p lies, an d I certain ly h ave n ot tested th em all. I can , h owever, recom m en d som e com p an ies wh ose p rod u cts I h ave com e to kn ow an d tru st. Alth ou gh oth er h igh -q u ality m an u factu rers are ou t th ere, at th is tim e I recom m en d p ower su p p lies from eith er Astec Stan d ard Power or PC Power an d Coolin g. Astec m akes th e p ower su p p lies u sed in m ost of th e h igh -en d system s by IBM, HewlettPackard , Ap p le, an d m an y oth er n am e-bran d system s. Th ey h ave p ower su p p lies available in a n u m ber of stan d ard form factors (AT/ Tower, Baby AT, LPX, an d ATX) an d a variety of ou tp u t levels. Th ey h ave p ower su p p lies with ratin gs of u p to 450 watts an d p ower su p p lies esp ecially d esign ed for “green ” PCs, wh ich m eet th e EPA En ergy Star req u irem en ts for low-p ower con su m p tion . Th eir “green ” p ower su p p lies are sp ecifically d esign ed to ach ieve h igh efficien cy at low-load con d ition s. Be aware th at h igh -ou tp u t su p p lies from oth er m an u factu rers m ay h ave p roblem s with very low load s. Astec also m akes a n u m ber of p ower su p p lies for lap top an d n otebook PC system s an d h as n u m erou s n on -PC typ e su p p lies. PC Power an d Coolin g h as a com p lete lin e of p ower su p p lies for PC system s. Th ey m ake su p p lies in all th e stan d ard PC form factors u sed tod ay. Version s are available in a variety of d ifferen t q u ality an d ou tp u t levels, from in exp en sive rep lacem en ts to very h igh q u ality h igh -ou tp u t m od els with ratin gs of u p to 450 watts. Th ey even h ave version s with bu ilt-in battery backu p , red u n d an t p ower system s, an d a series of sp ecial m od els with h igh -volu m e, low-sp eed (q u iet) fan assem blies. Th eir q u iet m od els are esp ecially welcom e to p eop le wh o work in q u iet h om es or offices an d are an n oyed by th e fan n oise th at som e p ower su p p lies em an ate. PC Power an d Coolin g also h as u n its available th at fit som e of Com p aq ’s p rop rietary d esign s. Th is can be a real boon if you h ave to service or rep air Com p aq system s becau se th e PC Power an d Coolin g u n its are available in h igh er ou tp u t ratin gs th an Com p aq ’s. Th ese u n its cost m u ch less th an Com p aq an d bolt in as d irect rep lacem en ts. Th e su p p ort offered by PC Power an d Coolin g is excellen t also, an d th ey h ave been in bu sin ess a lon g tim e, wh ich is rare in th is in d u stry. Besid es p ower su p p lies, th ey also h ave an excellen t lin e of cases. A h igh -q u ality p ower su p p ly from eith er of th ese ven d ors can be on e of th e best cu res for in term itten t system p roblem s an d can go a lon g way toward en su rin g trou ble-free op eration in th e fu tu re.

Using Power-Protection Systems

Using Pow er-Prot ect ion Syst em s Power-p rotection system s d o ju st wh at th e n am e im p lies: Th ey p rotect you r eq u ip m en t from th e effects of p ower su rges an d p ower failu res. In p articu lar, p ower su rges an d sp ikes can d am age com p u ter eq u ip m en t, an d a loss of p ower can resu lt in lost d ata. In th is section , you learn abou t th e fou r p rim ary typ es of p ower-p rotection d evices available an d wh en you sh ou ld u se th em . Before con sid erin g an y fu rth er levels of p ower p rotection , you sh ou ld kn ow th at a good q u ality p ower su p p ly alread y afford s you a su bstan tial am ou n t of p rotection . High -en d p ower su p p lies from th e ven d ors I recom m en d are d esign ed to p rovid e p rotection from h igh er-th an -n orm al voltages an d cu rren ts, an d th ey p rovid e a lim ited am ou n t of p owerlin e n oise filterin g. Som e of th e in exp en sive afterm arket p ower su p p lies p robably d o n ot h ave th is sort of p rotection . If you h ave an in exp en sive com p u ter, fu rth er p rotectin g you r system m igh t be wise.

Caut ion All the power protection features in this chapter and the protection features in the power supply inside your computer require that the computer’s AC power cable be connected to a ground. M any older homes do not have three-prong (grounded) outlets to accommodate grounded devices. Do not use a three-pronged adapter (that bypasses the three-prong requirement and enables you to connect to a two-prong socket) to plug in a surge suppressor, computer, or UPS into a twopronged outlet. They often don’t provide a good ground and can inhibit the capabilities of your power-protection devices. It is also a good idea to test your power sockets to make sure they are grounded. Sometimes outlets, despite having three-prong sockets, are not connected to a ground wire; an inexpensive socket tester (available at most hardware stores) can detect this condition.

Of cou rse, th e easiest form of p rotection is to tu rn off an d u n p lu g you r com p u ter eq u ip m en t (in clu d in g you r m od em ) wh en a th u n d erstorm is im m in en t. W h en th is is n ot p ossible, h owever, th ere are oth er altern atives. Power su p p lies sh ou ld stay with in op eratin g sp ecification s an d con tin u e to ru n a system if an y of th ese p ower lin e d istu rban ces occu r: ■ Voltage d rop to 80v for u p to 2 secon d s ■ Voltage d rop to 70v for u p to .5 secon d s ■ Voltage su rge of u p to 143v for u p to 1 secon d IBM also states th at n eith er th eir p ower su p p lies, n or system s will be d am aged by th e followin g occu rren ces:

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■ Fu ll p ower ou tage ■ An y voltage d rop (brown ou t) ■ A sp ike of u p to 2,500v Becau se of th eir in tern al p rotection , m an y com p u ter m an u factu rers th at u se h igh -q u ality PSUs state in th eir d ocu m en tation th at extern al su rge su p p ressors are n ot n eed ed with th eir system s. To verify th e levels of p rotection bu ilt in to th e existin g p ower su p p ly in a com p u ter system , an in d ep en d en t laboratory su bjected several u n p rotected PC system s to variou s sp ikes an d su rges of u p to 6,000v—con sid ered th e m axim u m level of su rge th at can be tran sm itted to a system th rou gh an electrical ou tlet. An y h igh er voltage wou ld cau se th e p ower to arc to th e grou n d with in th e ou tlet. Non e of th e system s su stain ed p erm an en t d am age in th ese tests. Th e worst th in g th at h ap p en ed was th at som e of th e system s rebooted or sh u t d own if th e su rge was m ore th an 2,000v. Each system restarted wh en th e p ower switch was toggled after a sh u td own . I d o n ot u se an y real form of p ower p rotection on m y system s, an d th ey h ave su rvived n ear-d irect ligh tn in g strikes an d p owerfu l su rges. Th e m ost recen t in cid en t, on ly 50 feet from m y office, was a d irect ligh tn in g strike to a brick ch im n ey th at blew th e top of th e ch im n ey ap art. Non e of m y system s (wh ich were ru n n in g at th e tim e) were d am aged in an y way from th is in cid en t; th ey ju st sh u t th em selves d own . I was able to restart each system by togglin g th e p ower switch es. An alarm system located in th e sam e office, h owever, was d estroyed by th is strike. I am n ot sayin g th at ligh tn in g strikes or even m u ch m ild er sp ikes an d su rges can n ot d am age com p u ter system s—an oth er n earby ligh tn in g strike d id d estroy a m od em an d serial ad ap ter in stalled in on e of m y system s. I was ju st lu cky th at th e d estru ction d id n ot in clu d e th e m oth erboard . Th is d iscu ssion p oin ts ou t an im p ortan t oversigh t in som e p ower-p rotection strategies: Do n ot forget to p rovid e p rotection from sp ikes an d su rges on th e p h on e lin e. Th e au tom atic sh u td own of a com p u ter d u rin g p ower d istu rban ces is a bu ilt-in fu n ction of m ost h igh -q u ality p ower su p p lies. You can reset th e p ower su p p ly by flip p in g th e p ower switch from on to off an d back on again . Som e p ower su p p lies even h ave an au torestart fu n ction . Th is typ e of p ower su p p ly acts th e sam e as oth ers in a m assive su rge or sp ike situ ation : It sh u ts d own th e system . Th e d ifferen ce is th at after n orm al p ower resu m es, th e p ower su p p ly waits for a sp ecified d elay of th ree to six secon d s an d th en resets itself an d p owers th e system back u p . Becau se n o m an u al switch resettin g is req u ired , th is featu re m ay be d esirable in system s fu n ction in g as n etwork servers or in th ose fou n d in oth er u n atten d ed location s. Th e first tim e I witn essed a large su rge cau se an im m ed iate sh u td own of all m y system s, I was extrem ely su rp rised . All th e system s were silen t, bu t th e m on itor an d m od em ligh ts were still on . My first th ou gh t was th at everyth in g was blown , bu t a sim p le toggle of each system -u n it p ower switch cau sed th e p ower su p p lies to reset, an d th e u n its p owered u p with n o p roblem . Sin ce th at first tim e, th is typ e of sh u td own h as h ap p en ed to m e several tim es, always with ou t fu rth er p roblem s.

Using Power-Protection Systems

Th e followin g typ es of p ower-p rotection d evices are exp lain ed in th e section s th at follow: ■ Su rge su p p ressors ■ Lin e con d ition ers ■ Stan d by p ower su p p lies (SPS) ■ Un in terru p tible p ower su p p lies (UPS) Surge Suppressors ( Prot ect ors) Th e sim p lest form of p ower p rotection is an y on e of th e com m ercially available su rge p rotectors—th at is, d evices in serted between th e system an d th e p ower lin e. Th ese d evices, wh ich cost between $20 an d $200, can absorb th e h igh -voltage tran sien ts p rod u ced by n earby ligh tn in g strikes an d p ower eq u ip m en t. Som e su rge p rotectors can be effective for certain typ es of p ower p roblem s, bu t th ey offer on ly very lim ited p rotection . Su rge p rotectors u se several d evices, u su ally m etal-oxide varistors (MOV s), th at can clam p an d sh u n t away all voltages above a certain level. MOVs are d esign ed to accep t voltages as h igh as 6,000v an d d ivert an y p ower above 200v to grou n d . MOVs can h an d le n orm al su rges, bu t p owerfu l su rges su ch as a d irect ligh tn in g strike can blow righ t th rou gh th em . MOVs are n ot d esign ed to h an d le a very h igh level of p ower an d self-d estru ct wh ile sh u n tin g a large su rge. Th ese d evices th erefore cease to fu n ction after eith er a sin gle large su rge or a series of sm aller on es. Th e real p roblem is th at you can n ot easily tell wh en th ey n o lon ger are fu n ction al. Th e on ly way to test th em is to su bject th e MOVs to a su rge, wh ich d estroys th em . Th erefore, you n ever really kn ow if you r so-called su rge p rotector is p rotectin g you r system . Som e su rge p rotectors h ave statu s ligh ts th at let you kn ow wh en a su rge large en ou gh to blow th e MOVs h as occu rred . A su rge su p p ressor with ou t th is statu s in d icator ligh t is u seless becau se you n ever kn ow wh en it h as stop p ed p rotectin g. Un d erwriters Laboratories h as p rod u ced an excellen t stan d ard th at govern s su rge su p p ressors, called UL 1449. An y su rge su p p ressor th at m eets th is stan d ard is a very good on e, an d d efin itely offers a lin e of p rotection beyon d wh at th e p ower su p p ly in you r PC alread y offers. Th e on ly typ es of su rge su p p ressors worth bu yin g, th erefore, sh ou ld h ave two featu res: ■ Con form an ce to th e UL 1449 stan d ard ■ A statu s ligh t in d icatin g wh en th e MOVs are blown Un its th at m eet th e UL 1449 sp ecification say so on th e p ackagin g or d irectly on th e u n it. If th is stan d ard is n ot m en tion ed , it d oes n ot con form . Th erefore, you sh ou ld avoid it. An oth er good featu re to h ave in a su rge su p p ressor is a bu ilt-in circu it breaker th at can be m an u ally reset rath er th an a fu se. Th e breaker p rotects you r system if it or a p erip h eral d evelop s a sh ort. Th ese better su rge su p p ressors u su ally cost abou t $40.

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Phone Line Surge Prot ect ors In ad d ition to p rotectin g th e p ower lin es, it is critical to p rovid e p rotection to you r system s from an y con n ected p h on e lin es. If you are u sin g a m od em or fax board th at is p lu gged in to th e p h on e system , an y su rges or sp ikes th at travel th rou gh th e p h on e lin e can d am age you r system . In m an y areas, th e p h on e lin es are esp ecially su scep tible to ligh tn in g strikes, wh ich are th e largest cau se of fried m od em s an d d am age to th e com p u ter eq u ip m en t attach ed to th em . Several com p an ies m an u factu re or sell sim p le su rge p rotectors th at p lu g in between you r m od em an d th e p h on e lin e. Th ese in exp en sive d evices can be p u rch ased from m ost electron ics su p p ly h ou ses. Most of th e cable an d com m u n ication p rod u cts ven d ors listed in Ap p en d ix A sell th ese p h on e lin e su rge p rotectors. Som e of th e stan d ard p ower lin e su rge p rotectors in clu d e con n ectors for p h on e lin e p rotection as well. Line Condit ioners In ad d ition to h igh -voltage an d cu rren t con d ition s, oth er p roblem s can occu r with in com in g p ower. Th e voltage m igh t d ip below th e level n eed ed to ru n th e system , resu ltin g in a brown ou t. Form s of electrical n oise oth er th an sim p le voltage su rges or sp ikes m igh t travel th rou gh th e p ower lin e, su ch as rad io-freq u en cy in terferen ce or electrical n oise cau sed by m otors or oth er in d u ctive load s. Rem em ber two th in gs wh en you wire togeth er d igital d evices (su ch as com p u ters an d th eir p erip h erals): ■ An y wire can act as an an ten n a an d h ave voltage in d u ced in it by n earby electrom agn etic field s, wh ich can com e from oth er wires, telep h on es, CRTs, m otors, flu orescen t fixtu res, static d isch arge, an d , of cou rse, rad io tran sm itters. ■ Digital circu itry resp on d s with su rp risin g efficien cy to n oise of even a volt or two, m akin g th ose in d u ced voltages p articu larly trou blesom e. Th e electrical wirin g in you r bu ild in g can act as an an ten n a, p ickin g u p all kin d s of n oise an d d istu rban ces. A lin e con d ition er can h an d le m an y of th ese typ es of p roblem s. A line conditioner is d esign ed to rem ed y a variety of p roblem s. It filters th e p ower, brid ges brown ou ts, su p p resses h igh -voltage an d cu rren t con d ition s, an d gen erally acts as a bu ffer between th e p ower lin e an d th e system . A lin e con d ition er d oes th e job of a su rge su p p ressor, an d m u ch m ore. It is m ore of an active d evice, fu n ction in g con tin u ou sly, rath er th an a p assive d evice th at activates on ly wh en a su rge is p resen t. A lin e con d ition er p rovid es tru e p ower con d ition in g an d can h an d le m yriad p roblem s. It con tain s tran sform ers, cap acitors, an d oth er circu itry th at can tem p orarily brid ge a brown ou t or low-voltage situ ation . Th ese u n its u su ally cost from $100 to $300, d ep en d in g on th e p ower-h an d lin g cap acity of th e u n it. Backup Pow er Th e n ext level of p ower p rotection in clu d es backup power-protection devices. Th ese u n its can p rovid e p ower in case of a com p lete blackou t, wh ich p rovid es th e tim e n eed ed for an ord erly system sh u td own . Two typ es are available: th e standby power supply (SPS) an d th e

Using Power-Protection Systems

uninterruptible power supply (UPS). Th e UPS is a sp ecial d evice becau se it d oes m u ch m ore th an ju st p rovid e backu p p ower: It is also th e best kin d of lin e con d ition er you can bu y. St andby Pow er Supplies ( SPS) . A stan d by p ower su p p ly is kn own as an offline device: It fu n ction s on ly wh en n orm al p ower is d isru p ted . An SPS system u ses a sp ecial circu it th at can sen se th e AC lin e cu rren t. If th e sen sor d etects a loss of p ower on th e lin e, th e system q u ickly switch es over to a stan d by battery an d p ower in verter. Th e p ower in verter con verts th e battery p ower to 110v AC p ower, wh ich is th en su p p lied to th e system . SPS system s d o work, bu t som etim es a p roblem occu rs d u rin g th e switch to battery p ower. If th e switch is n ot fast en ou gh , th e com p u ter system sh u ts d own or reboots an yway, wh ich d efeats th e p u rp ose of h avin g th e backu p p ower su p p ly. A tru ly ou tstan d in g SPS ad d s to th e circu it a ferroresonant transform er, a large tran sform er with th e cap ability to store a sm all am ou n t of p ower an d d eliver it d u rin g th e switch tim e. Th is d evice fu n ction s as a bu ffer on th e p ower lin e, givin g th e SPS alm ost u n in terru p tible cap ability. SPS u n its also m ay or m ay n ot h ave in tern al lin e con d ition in g of th eir own . Un d er n orm al circu m stan ces, m ost ch eap er u n its p lace you r system d irectly on th e regu lar p ower lin e an d offer n o con d ition in g. Th e ad d ition of a ferroreson an t tran sform er to an SPS gives it ad d ition al regu lation an d p rotection cap abilities becau se of th e bu ffer effect of th e tran sform er. SPS d evices with ou t th e ferroreson an t tran sform er still req u ire th e u se of a lin e con d ition er for fu ll p rotection . SPS system s u su ally cost from a cou p le h u n d red to several th ou san d s of d ollars, d ep en d in g on th e q u ality an d p ower-ou tp u t cap acity. Unint errupt ible Pow er Supplies ( UPS) . Perh ap s th e best overall solu tion to an y p ower p roblem is to p rovid e a p ower sou rce th at is con d ition ed an d th at can n ot be in terru p ted —wh ich is th e d efin ition of an u n in terru p tible p ower su p p ly. UPSs are kn own as online system s becau se th ey con tin u ou sly fu n ction an d su p p ly p ower to you r com p u ter system s. Becau se som e com p an ies ad vertise ferroreson an t SPS d evices as th ou gh th ey were UPS d evices, m an y n ow u se th e term true UPS to d escribe a tru ly on lin e system . A tru e UPS system is con stru cted in m u ch th e sam e way as an SPS system ; h owever, becau se th e com p u ter is always op eratin g from th e battery, th ere is n o switch in g circu it. In a tru e UPS, you r system always op erates from th e battery. A voltage in verter con verts from 12v DC to 110v AC. You essen tially h ave you r own p rivate p ower system th at gen erates p ower in d ep en d en tly of th e AC lin e. A battery ch arger con n ected to th e lin e or wall cu rren t keep s th e battery ch arged at a rate eq u al to or greater th an th e rate at wh ich p ower is con su m ed . W h en th e AC cu rren t su p p lyin g th e battery ch arger fails, a tru e UPS con tin u es fu n ction in g u n d istu rbed becau se th e battery-ch argin g fu n ction is all th at is lost. Becau se th e com p u ter was alread y ru n n in g off th e battery, n o switch takes p lace, an d n o p ower d isru p tion is p ossible. Th e battery begin s d isch argin g at a rate d ictated by th e am ou n t of load you r system p laces on th e u n it, wh ich (based on th e size of th e battery) gives you p len ty of tim e to execu te an ord erly system sh u td own . Based on an ap p rop riately scaled storage battery, th e UPS fu n ction s con tin u ou sly, gen eratin g p ower an d p reven tin g u n p leasan t su rp rises. W h en th e lin e p ower retu rn s, th e battery ch arger begin s rech argin g th e battery, again with n o in terru p tion .

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Not e Occasionally, a UPS can accumulate too much storage and not enough discharge. When this occurs, the UPS emits a loud alarm, alerting you that it’s full. Simply unplugging the unit from the AC power source for a while can discharge the excess storage (as it powers your computer) and drain the UPS of the excess.

Man y SPS system s are ad vertised as th ou gh th ey were tru e UPS system s. Th e giveaway is th e u n it’s switch tim e. If a sp ecification for switch tim e exists, th e u n it can n ot be a tru e UPS becau se UPS u n its n ever switch . However, a good SPS with a ferroreson an t tran sform er can virtu ally eq u al th e p erform an ce of a tru e UPS at a lower cost.

Not e M any UPSs today come equipped with a cable and software that enables the protected computer to shut down in an orderly manner on receipt of a signal from the UPS. This way, the system can shut down properly even if the computer is unattended. Some operating systems, such as Windows NT, contain their own UPS software components.

UPS cost is a d irect fu n ction of both th e len gth of tim e it can con tin u e to p rovid e p ower after a lin e cu rren t failu re an d h ow m u ch p ower it can p rovid e. You sh ou ld th erefore p u rch ase a UPS th at p rovid es you with en ou gh p ower to ru n you r system an d p erip h erals an d en ou gh tim e to close files an d p rovid e an ord erly sh u td own . Rem em ber, h owever, to m an u ally p erform a system sh u td own p roced u re d u rin g a p ower ou tage. You will p robably n eed you r m on itor p lu gged in to th e UPS an d th e com p u ter. Be su re th e UPS you p u rch ase can p rovid e su fficien t p ower for all th e d evices you m u st con n ect to it. Becau se of a tru e UPS’s alm ost total isolation from th e lin e cu rren t, it is u n m atch ed as a lin e con d ition er an d su rge su p p ressor. Th e best UPS system s ad d a ferroreson an t tran sform er for even greater p ower con d ition in g an d p rotection cap ability. Th is typ e of UPS is th e best form of p ower p rotection available. Th e p rice, h owever, can be h igh . To fin d ou t ju st h ow m u ch p ower you r com p u ter system req u ires, look at th e UL sticker on th e back of th e u n it. Th is sticker lists th e m axim u m p ower d raw in watts, or som etim es in ju st volts an d am p eres. If on ly voltage an d am p erage are listed , m u ltip ly th e two figu res to calcu late th e wattage. As an exam p le, if th e d ocu m en tation for a system in d icates th at th e com p u ter can req u ire as m u ch as 110v at a m axim u m cu rren t d raw of 5 am p s, th e m axim u m p ower th e system can d raw is abou t 550 watts. Th is wattage is for a system with every slot fu ll, two h ard d isks, an d on e flop p y—in oth er word s, a system at th e m axim u m p ossible level of exp an sion . Th e system sh ou ld n ever d raw an y m ore p ower th an th at; if it d oes, a 5-am p ere fu se in th e p ower su p p ly will blow. Th is typ e of system n orm ally d raws an average of 300 watts; to be safe wh en you m ake calcu lation s for UPS cap acity, h owever, be con servative. Use th e 550-watt figu re. Ad d in g a m on itor th at d raws 100 watts brin gs th e total to 650 watts or m ore. Th erefore, to ru n two fu lly load ed system s, you ’ll n eed an

Using Power-Protection Systems

1100-watt UPS. Don ’t forget two m on itors, each d rawin g 100 watts. Th erefore, th e total is 1,300 watts. A UPS of th at cap acity or greater will cost ap p roxim ately $500–$700. Un fortu n ately, th at is wh at th e best level of p rotection costs. Most com p an ies can ju stify th is typ e of exp en se on ly for critical-u se PCs, su ch as n etwork servers.

Not e The highest-capacity UPS sold for use with a conventional 15-amp outlet is about 1,400 watts. If it’s any higher, you risk tripping a 15-amp circuit when the battery is charging heavily and the inverter is drawing maximum current.

In ad d ition to th e total available ou tp u t p ower (wattage), several oth er factors can d ifferen tiate on e UPS from an oth er. Th e ad d ition of a ferroreson an t tran sform er im p roves a u n it’s p ower con d ition in g an d bu fferin g cap abilities. Good u n its also h ave an in verter th at p rod u ces a tru e sin e wave ou tp u t; th e ch eap er on es m ay gen erate a sq u are wave. A square wave is an ap p roxim ation of a sin e wave with abru p t u p -an d -d own voltage tran sition s. Th e abru p t tran sition s of a sq u are wave sign al are n ot com p atible with som e com p u ter eq u ip m en t p ower su p p lies. Be su re th at th e UPS you p u rch ase p rod u ces a sign al com p atible with you r com p u ter eq u ip m en t. Every u n it h as a sp ecification for h ow lon g it can su stain ou tp u t at th e rated level. If you r system s d raw less th an th e rated level, you h ave som e ad d ition al tim e.

Caut ion Be careful. M ost UPS systems are not designed for you to sit and compute for hours through an electrical blackout. They are designed to provide power only to essential components and to remain operating long enough to allow for an orderly shutdown. You pay a large amount for units that provide power for more than 15 minutes or so. At some point, it becomes more cost effective to buy a generator than to keep investing in extended life for a UPS.

Som e of th e m an y sou rces of p ower p rotection eq u ip m en t in clu d e Am erican Power Con version (APC), Trip p Lite, an d Best Power. Th ese com p an ies sell a variety of UPS, SPS, lin e, an d su rge p rotector p rod u cts.

Caut ion Don’t connect a laser printer to a backed-up socket in any SPS or UPS unit. They are both “ electrically noisy” and have widely varying current draws. This can be hard on the inverter in an SPS or UPS, frequently causing the inverter to fail or detect an overload and shut down. Either case means that your system will lose power, too. Printers are normally noncritical because whatever is being printed can be reprinted. Don’t connect them to a UPS unless there’s a good business need to do so. Some UPSs and SPSs have sockets that are conditioned, but not backed up—that is, they do not draw power from the battery. In cases such as this, you can safely plug printers and other peripherals into these sockets.

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RTC/ NVRAM Bat t eries All 16-bit an d h igh er system s h ave a sp ecial typ e of ch ip in th em th at com bin es a Real Tim e Clock (RTC) with at least 64 bytes (in clu d in g th e clock d ata) of Non -Volatile RAM (NVRAM) m em ory. Th is ch ip is officially called th e RTC/NV RAM chip, bu t is often referred to as th e CMOS chip or CMOS RAM becau se th e typ e of ch ip u sed is p rod u ced u sin g a CMOS (Com p lem en tary Metal Oxid e Sem icon d u ctor) p rocess. CMOS d esign ch ip s are kn own for very low p ower con su m p tion . Th is sp ecial RTC/ NVRAM ch ip is d esign ed to ru n off of a battery for several years. Th e origin al ch ip of th is typ e u sed in th e IBM AT was th e Motorola 146818 ch ip . Alth ou gh th e ch ip s u sed tod ay h ave d ifferen t m an u factu rers an d p art n u m bers, th ey are all d esign ed to be com p atible with th is origin al Motorola p art. Th ese ch ip s in clu d e a real-tim e clock. Its fu n ction sh ou ld be obviou s. Th e clock en ables software to read th e d ate an d tim e an d p reserves th e d ate an d tim e d ata even wh en th e system is p owered off or u n p lu gged . Th e NVRAM p ortion of th e ch ip h as an oth er fu n ction . It is d esign ed to store basic system con figu ration , in clu d in g th e am ou n t of m em ory in stalled , typ es of flop p y an d h ard d isk d rives, an d oth er in form ation . Som e of th e m ore m od ern m oth erboard s u se exten d ed NVRAM ch ip s with as m u ch as 2K or m ore of sp ace to h old th is con figu ration in form ation . Th is is esp ecially tru e for Plu g-an d -Play system s, wh ich store n ot on ly th e m oth erboard con figu ration , bu t also th e con figu ration of ad ap ter card s. Th is system can th en read th is in form ation every tim e you p ower on th e system . Th ese ch ip s are n orm ally p owered by som e typ e of battery wh ile th e system is off. Th is battery p reserves th e in form ation in th e NVRAM an d p owers th e clock. Most system s u se a lith iu m -typ e battery becau se th ey h ave a very lon g life, esp ecially at th e low p ower d raw from th e typ ical RTC/ NVRAM ch ip . Most of th e h igh er-q u ality m od ern system s sold tod ay h ave a n ew typ e of ch ip th at h as th e battery em bed d ed with in it. Th ese are m ad e by several com p an ies—in clu d in g Dallas Sem icon d u ctor an d Ben ch m arq . Th ese ch ip s are n otable for th eir lon g life. Un d er n orm al con d ition s, th e battery will last for 10 years—wh ich is, of cou rse, lon ger th an th e u sefu l life of th e system . If you r system u ses on e of th e Dallas or Ben ch m arq m od u les, th e battery an d ch ip m u st be rep laced as a u n it becau se th ey are in tegrated . Most of th e tim e, th ese ch ip / battery com bin ation s are in stalled in a socket on th e m oth erboard ju st in case a p roblem req u ires an early rep lacem en t. You can get n ew m od u les d irect from th e m an u factu rers for $18 or less, wh ich is often less th an th e cost of th e old er sep arate battery alon e. Som e system s d o n ot u se a battery at all. Hewlett-Packard , for exam p le, in clu d es a sp ecial cap acitor in m an y of th eir system s th at is au tom atically rech arged an ytim e th e system is p lu gged in . Note th at th e system d oes n ot h ave to be ru n n in g for th e cap acitor to ch arge; it on ly h as to be p lu gged in . If th e system is u n p lu gged , th e cap acitor will p ower th e RTC/ NVRAM ch ip for u p to a week or m ore. If th e system rem ain s u n p lu gged for a d u ration lon ger th an th at, th e NVRAM in form ation is lost. In th at case, th ese system s can

RTC/ NVRAM Batteries

reload th e NVRAM from a backu p kep t in a sp ecial flash ROM ch ip con tain ed on th e m oth erboard . Th e on ly p ieces of in form ation th at will actu ally be m issin g wh en you rep ower th e system will be th e d ate an d tim e, wh ich will h ave to be re-en tered . By u sin g th e cap acitor com bin ed with a NVRAM backu p in flash ROM, th ese system s h ave a very reliable solu tion th at will last in d efin itely. Man y system s u se on ly a con ven tion al battery, wh ich m ay be eith er d irectly sold ered in to th e m oth erboard or p lu gged in via a battery con n ector. For th ose system s with th e battery sold ered in , th ere is n orm ally a sp are battery con n ector on th e m oth erboard wh ere you can in sert a con ven tion al p lu g-in battery, sh ou ld th e origin al ever fail. In m ost cases, you wou ld n ever h ave to rep lace th e m oth erboard battery, even if it were com p letely d ead . Con ven tion al batteries com e in m an y form s. Th e best are of a lith iu m d esign becau se th ey will last from two to five years or m ore. I h ave seen system s with con ven tion al alkalin e batteries m ou n ted in a h old er; th ese are m u ch less d esirable becau se th ey fail m ore freq u en tly an d d o n ot last as lon g. Also, th ey can be p ron e to leak, an d if a battery leaks on th e m oth erboard , th e m oth erboard m ay be severely d am aged . Besid es th e d ifferen t battery typ es, th e ch ip can req u ire an y on e of several d ifferen t voltages. Th e batteries in PCs are n orm ally 3.6v, 4.5v, or 6v. If you are rep lacin g th e battery, m ake su re th at you r rep lacem en t is th e sam e voltage as th e on e you rem oved from th e system . Som e m oth erboard s can u se batteries of several d ifferen t voltages. Use a ju m p er or switch to select th e d ifferen t settin gs. If you su sp ect you r m oth erboard h as th is cap ability, con su lt th e d ocu m en tation for in stru ction s on ch an gin g th e settin gs. Of cou rse, th e easiest th in g to d o is to rep lace th e existin g battery with an oth er of th e sam e typ e. Sym p tom s th at in d icate th at th e battery is abou t to fail in clu d e h avin g to reset th e clock on you r PC every tim e you sh u t d own th e system (esp ecially after m ovin g it) an d p roblem s d u rin g th e system ’s POST, su ch as d rive-d etection d ifficu lties. If you exp erien ce p roblem s su ch as th ese, it is a good id ea to m ake n ote of you r system ’s CMOS settin gs an d rep lace th e battery as soon as p ossible.

Caut ion When you replace a PC battery, be sure that you get the polarity correct, or you will damage the RTC/ NVRAM (CM OS) chip. Because the chip is soldered onto most motherboards, this can be an expensive mistake! The battery connector on the motherboard and the battery are normally keyed to prevent a backward connection. The pinout of this connector is in Appendix A, but should also be listed in your system documentation.

W h en you rep lace a battery, in m ost cases th e existin g d ata stored in th e NVRAM is lost. Som etim es, h owever, th e d ata will rem ain in tact for several m in u tes (I h ave observed NVRAM retain in form ation with n o p ower for an h ou r or m ore), so if you m ake th e battery swap q u ickly, th e in form ation in th e NVRAM m igh t be retain ed . Ju st to be su re, it is recom m en d ed th at you record all th e system con figu ration settin gs stored in th e NVRAM

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by you r system Setu p p rogram . In m ost cases, you wou ld wan t to ru n th e BIOS Setu p p rogram an d cop y or p rin t ou t all th e screen s sh owin g th e d ifferen t settin gs. Som e Setu p p rogram s offer th e cap ability to save th e NVRAM d ata to a file for later restoration if n ecessary.

Tip If your system BIOS is password protected and you forget the password, one possible way to bypass the block is to remove the battery for a few minutes and then replace it. This will reset the BIOS to its default settings, removing the password protection.

After rep lacin g a battery, p ower u p th e system an d u se th e Setu p p rogram to ch eck th e d ate an d tim e settin g an d an y oth er d ata th at was stored in th e NVRAM.

Chapter 7

Input Devices

7

Th is ch ap ter d iscu sses in p u t d evices—th e d evices u sed to com m u n icate with th e com p u ter. Th e m ost com m on in p u t d evice is th e keyboard , wh ich th is ch ap ter d iscu sses in d ep th . It also d iscu sses th e m ice an d altern ative p oin tin g d evices req u ired to op erate a PC with a GUI (grap h ical u ser in terface), su ch as W in d ows or OS/ 2. Fin ally, th is ch ap ter d iscu sses th e gam e or joystick in terface, wh ich is u sed to in p u t sign als from joysticks, p ad d les, or oth er gam e d evices.

Keyboards On e of th e m ost basic system com p on en ts is th e keyboard, wh ich is th e p rim ary in p u t d evice. It is u sed for en terin g com m an d s an d d ata in to th e system . Th is section looks at th e keyboard s available for PC-com p atible system s, exam in in g th e d ifferen t typ es of keyboard s, h ow th e keyboard fu n ction s, th e keyboard -to-system in terface, an d keyboard trou blesh ootin g an d rep air. Types of Keyboards In th e years sin ce th e in trod u ction of th e origin al IBM PC, IBM h as created th ree d ifferen t keyboard d esign s for PC system s, an d Microsoft h as au gm en ted on e of th em . Th ese d esign s h ave becom e de facto stan d ard s in th e in d u stry an d are sh ared by virtu ally all PC m an u factu rers. More recen tly, with th e in trod u ction of W in d ows 95, a m od ified version of th e stan d ard 101-key d esign (created by Microsoft) h as ap p eared , called th e 104-key W in d ows keyboard . Th e p rim ary keyboard typ es are as follows: ■ 83-key PC an d XT keyboard ■ 84-key AT keyboard ■ 101-key En h an ced keyboard ■ 104-key En h an ced W in d ows keyboard

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Th is section d iscu sses each keyboard typ e an d sh ows its layou t an d p h ysical ap p earan ce. Of th e fou r d esign s listed , on ly th e last two are still in gen eral u se, alth ou gh you can still fin d old system s th at u tilize th e 83-key an d 84-key d esign s. Becau se all n ew system s tod ay u se th e 101- an d 104-key En h an ced keyboard d esign s, th ese version s are em p h asized . 83-Key PC and XT Keyboard. W h en th e origin al PC was in trod u ced , it h ad som eth in g th at few oth er p erson al com p u ters h ad at th e tim e: an extern al d etach able keyboard . Most oth er sm all p erson al com p u ters of th e tim e, su ch as th e Ap p le II, h ad bu ilt-in keyboard s. Alth ou gh th e extern al d esign was a good m ove on IBM’s p art, th e keyboard d esign was n ot with ou t its d rawbacks. On e of th e m ost criticized com p on en ts of th e origin al 83-key keyboard was th e awkward layou t (see Figu re 7.1). Th e Sh ift keys in th is m od el were sm all an d were in th e wron g p lace on th e left sid e. Th e En ter key was also too sm all. Th ese oversigh ts were esp ecially irritatin g at th e tim e becau se IBM h ad recen tly p rod u ced th e Selectric typ ewriter, p erceived as a stan d ard for good keyboard layou t.

F1

F2

F3

F4

F5

F6

F7

F8

F9

F10

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FIG. 7.1 PC an d XT 83-key keyboard layou t. Th e PC keyboard h as a bu ilt-in p rocessor th at com m u n icates with th e m oth erboard via a sp ecial serial d ata lin k. Th e com m u n ication is on e-way, wh ich m ean s th at th e m oth erboard can n ot sen d com m an d s or d ata back to th e keyboard . For th is reason , IBM 83-key keyboard s h ave n o Ligh t Em ittin g Diod e (LED) in d icator ligh ts. Becau se th e statu s of th e Cap s Lock, Nu m Lock, an d Scroll Lock fu n ction s are m ain tain ed by th e m oth erboard , th ere is n o way to m ake su re th at an y LED in d icator ligh ts rem ain in syn c with th e actu al statu s of th e fu n ction . Man y afterm arket (n on -IBM) PC keyboard s ad d ed th e ligh ts, an d th e keyboard attem p ted to keep track of th e th ree fu n ction s in d ep en d en tly of th e m oth erboard . Th is worked in m ost situ ation s, bu t som etim es th e LEDs wou ld get ou t of syn c with th e actu al fu n ction statu s. Rebootin g corrected th is tem p orary p roblem , bu t it was an n oyin g p rocess n on eth eless. Th e origin al 83-key PC/ XT keyboard is n o lon ger u sed an d is n ot electrically com p atible with AT-com p atible m oth erboard s, alth ou gh som e afterm arket u n its m ay be com p atible if an XT/ AT switch u su ally fou n d on th e bottom of th e keyboard is m oved .

Keyboards

√√ See “ System Types,” p. 21

84-Key AT Keyboard. W h en th e AT was in trod u ced in 1984, it in clu d ed a n ew keyboard —th e 84-key u n it (see Figu re 7.2). Th is keyboard corrected m an y p roblem s of th e origin al PC an d XT keyboard s. Th e p osition an d arran gem en t of th e n u m eric keyp ad were m od ified . Th e En ter key was m ad e m u ch larger, like th at of a Selectric typ ewriter. Th e Sh ift key p osition s an d sizes were corrected . IBM also fin ally ad d ed LED in d icators for th e statu s of th e Cap s Lock, Scroll Lock, an d Nu m Lock toggles.

Num Lock

F1 F3

F2

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FIG. 7.2 AT 84-key keyboard layou t. Th ese keyboard s u se a sligh tly m od ified , bid irection al in terface p rotocol. Th is m ean s th at th e p rocessor bu ilt in to th e keyboard can talk to an oth er p rocessor (called th e 8042 keyboard controller chip) th at is bu ilt in to th e m oth erboard . Th e keyboard con troller on th e m oth erboard can sen d com m an d s an d d ata to th e keyboard , wh ich allows for fu n ction s su ch as ch an gin g th e keyboard typ em atic (or rep eat) rate an d th e d elay before rep eatin g begin s. Th e keyboard con troller on th e m oth erboard also p erform s scan code translations, wh ich allows for a m u ch easier in tegration of foreign lan gu age keyboard s in to th e system . Scan codes are th e h exad ecim al cod es actu ally sen t by th e keyboard to th e m oth erboard . Th e bid irection al in terface can be u sed to con trol th e LED in d icators on th e keyboard , th u s en su rin g th at th e statu s of a p articu lar fu n ction an d th e corresp on d in g in d icator are always in syn c. Th e 84-key u n it th at cam e with th e origin al AT system is n o lon ger u sed , alth ou gh its electrical d esign is com p atible with n ewer system s. It lacks som e of th e keys fou n d in th e n ewer keyboard s an d d oes n ot h ave as n ice a n u m eric keyp ad section , bu t m an y u sers p refer th e m ore Selectric-style layou t of th e alp h an u m eric keys. Likewise, som e u sers p refer to h ave th e 10 fu n ction keys arran ged on th e left sid e in stead of th e en h an ced arran gem en t, in wh ich 12 fu n ction keys are lin ed u p alon g th e top . For u sers accu stom ed to th e n ewer keyboard layou ts, th e m ost obviou s p roblem with th e AT keyboard is th e lack of d ed icated cu rsor keys. Becau se th e cu rsor keys are in tegrated in to th e n u m eric keyp ad , th e statu s of th e Nu m Lock fu n ction is cru cial to th e op eration

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Chapter 7—Input Devices

of th e system an d con tin u es to be a sou rce of con stan t exasp eration to u sers. W h en you con sid er th e im p ortan ce of sp read sh eet ap p lication s su ch as Lotu s 1-2-3 in th e early h istory of p erson al com p u tin g, it is easy to see wh y u sers wh o rely h eavily on both th e n u m eric keyp ad an d th e cu rsor keys welcom ed th e 101-key keyboard as a boon . Enhanced 101-Key ( or 102-Key) . In 1986, IBM in trod u ced th e “corp orate” en h an ced 101-key keyboard for th e n ewer XT an d AT m od els (see Figu re 7.3). I u se th e word “corp orate” becau se th is u n it first ap p eared in IBM’s RT PC, wh ich is a RISC (Reduced Instruction Set Com puter) system d esign ed for scien tific an d en gin eerin g ap p lication s. Keyboard s with th is d esign were soon su p p lied with virtu ally every typ e of system an d term in al th at IBM sold . Oth er com p an ies q u ickly cop ied th is d esign , wh ich h as been th e stan d ard on In tel-based PC system s ever sin ce. Th e layou t of th is u n iversal keyboard h as im p roved over th at of th e 84-key u n it—with p erh ap s th e excep tion of th e En ter key, wh ich reverted to a sm aller size. Th e 101-key En h an ced keyboard was d esign ed to con form to in tern ation al regu lation s an d sp ecification s for keyboard s. In fact, oth er com p an ies, su ch as Digital Eq u ip m en t Corp oration (DEC) an d Texas In stru m en ts (TI), h ad alread y been u sin g d esign s sim ilar to th e IBM 101-key u n it. Th e IBM 101-key u n its origin ally cam e in version s with an d with ou t th e statu s in d icator LEDs, d ep en d in g on wh eth er th e u n it was sold with an XT or AT system . Now th ere are m an y oth er variation s to ch oose from , in clu d in g som e with in tegrated p oin tin g d evices.

F1

Esc

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F2

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Ctrl

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8

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5

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2

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FIG. 7.3 101-key En h an ced keyboard layou t. Th e En h an ced keyboard is available in several d ifferen t variation s, bu t all are basically th e sam e electrically an d all can be in terch an ged . IBM an d its Lexm ark keyboard an d p rin ter su bsid iary h ave p rod u ced a n u m ber of version s, in clu d in g keyboard s with bu ilt-in p oin tin g d evices an d n ew ergon om ic layou ts. Som e of th e En h an ced keyboard s still attach to th e system via th e five-p in DIN (an acron ym from th e Germ an Deu tsch e In d u strie Norm ) con n ector, bu t m ost tod ay com e with cables for th e six-p in m in i-DIN con n ector in trod u ced on th e IBM PS/ 2s. Alth ou gh th e con n ectors m ay be p h ysically d ifferen t, th e keyboard s are n ot, an d you can eith er in terch an ge th e cables or u se a cable ad ap ter to p lu g on e typ e in to th e oth er.

Keyboards

Th e 101-key keyboard layou t can be d ivid ed in to th e followin g fou r section s: ■ Typ in g area ■ Nu m eric keyp ad ■ Cu rsor an d screen con trols ■ Fu n ction keys Th e 101-key arran gem en t is sim ilar to th e Selectric keyboard layou t, with th e excep tion of th e En ter key. Th e Tab, Cap s Lock, Sh ift, an d Backsp ace keys h ave a larger strikin g area an d are located in th e fam iliar Selectric location s. Ctrl an d Alt keys are on each sid e of th e Sp acebar. Th e typ in g area an d n u m eric keyp ad h ave h om e-row id en tifiers for tou ch typ in g. Th e cu rsor an d screen -con trol keys h ave been sep arated from th e n u m eric keyp ad , wh ich is reserved for n u m eric in p u t. (As with oth er PC keyboard s, you can u se th e n u m eric keyp ad for cu rsor an d screen con trol wh en th e keyboard is n ot in Nu m Lock m od e.) A d ivision -sign key an d an ad d ition al En ter key h ave been ad d ed to th e n u m eric keyp ad . Th e cu rsor-con trol keys are arran ged in th e in verted T form at th at is n ow exp ected on all com p u ter keyboard s. Th e In sert, Delete, Hom e, En d , Page Up , an d Page Down keys, located above th e d ed icated cu rsor-con trol keys, are sep arate from th e n u m eric keyp ad . Th e fu n ction keys, sp aced in grou p s of fou r, are located across th e top of th e keyboard . Th e keyboard also h as two ad d ition al fu n ction keys: F11 an d F12. Th e Esc key is isolated in th e u p p er-left corn er of th e keyboard . Ded icated Prin t Screen / Sys Req , Scroll Lock, an d Pau se/ Break keys are p rovid ed for com m on ly u sed fu n ction s. Foreign lan gu age version s of th e En h an ced keyboard in clu d e 102 keys an d a sligh tly d ifferen t layou t from th e 101-key U.S. version s. On e of th e m an y u sefu l featu res of th e en h an ced keyboard is rem ovable keycap s. Th is p erm its th e rep lacem en t of broken keys an d p rovid es access for easier clean in g. Also, with clear keycap s an d p ap er in serts, you can cu stom ize th e keyboard . Keyboard tem p lates are also available to p rovid e sp ecific op erator in stru ction s. Th e 101-key En h an ced keyboard or on e of its variation s will p robably con tin u e to be fu rn ish ed with all d esktop PC system s for som e tim e to com e. It is by far th e m ost p op u lar d esign an d d oes n ot sh ow an y sign s of bein g rep laced in th e fu tu re. Becau se m ost PCs u se th is sam e typ e of keyboard , it is easy to m ove from on e system to an oth er with ou t relearn in g th e layou t. Also, as a relatively in exp en sive com p on en t, you can easily rep lace a broken or u n com fortable keyboard . 104-Key ( W indow s Keyboard) . If you are a tou ch typ ist like I am , th en you really h ate to take you r h an d s off of th e keyboard to u se a m ou se. W in d ows 95 m akes th is even m ore of a p roblem becau se it exp loits both m ou se bu tton s. Man y n ew keyboard s, esp ecially th ose in p ortable com p u ters, in clu d e a variation of th e IBM TrackPoin t or th e Alp s

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Glid ep oin t p oin tin g d evices (d iscu ssed later in th is ch ap ter), wh ich allow tou ch typ ists to keep th eir h an d s on th e keyboard even wh ile m ovin g th e p oin ter. However, th ere is still an oth er altern ative th at can h elp . Microsoft h as com e u p with a sp ecification th at calls for th ree n ew W in d ows-sp ecific keys to be ad d ed to th e keyboard . Th ese n ew keys h elp with fu n ction s th at wou ld oth erwise req u ire m u ltip le keystrokes or m ou se clicks. Th e Microsoft W in d ows keyboard sp ecification ou tlin es a set of n ew keys an d key com bin ation s. Th e fam iliar 101-key layou t h as n ow grown to 104 keys, with th e ad d ition of left an d righ t W in d ows keys an d an Ap p lication key. Th ese keys are u sed for op eratin gsystem an d ap p lication -level keyboard com bin ation s, sim ilar to tod ay’s Ctrl an d Alt com bin ation s. You d on ’t n eed th e n ew keys to u se W in d ows 95 or NT, bu t software ven d ors are startin g to ad d sp ecific fu n ction s to th eir W in d ows p rod u cts th at m ake u se of th e n ew Ap p lication key (wh ich p rovid es th e sam e fu n ction ality as clickin g th e righ t m ou se bu tton ). Figu re 7.4 sh ows th e stan d ard W in d ows keyboard layou t, in clu d in g th e th ree n ew keys.

Esc

~ ` Tab → →

Caps Lock

↑Shift

F1

! 1

F2

@ 2 Q

F3

# 3 W

A

$ 4 E

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F4

% 5 R

D

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F5

^ 6 T

F

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Left Windows key Right Windows key

FIG. 7.4 104-key W in d ows keyboard layou t. Th e recom m en d ed W in d ows keyboard layou t calls for th e Left an d Righ t W in d ows keys (called W IN keys) to flan k th e Alt keys on each sid e of th e Sp acebar, as well as an Ap p lication key on th e righ t of th e Righ t W in d ows key. Note th at th e exact p lacem en t of th ese keys is u p to th e keyboard d esign er, so you will see variation s from keyboard to keyboard . Th e W IN keys op en th e W in d ows 95 Start m en u , wh ich you can th en n avigate with th e cu rsor keys. Th e Ap p lication key sim u lates th e righ t m ou se bu tton ; in m ost ap p lication s, it brin gs u p a con text-sen sitive p op -u p m en u . Several W IN key com bin ation s offer p reset m acro com m an d s as well. For exam p le, you p ress W IN+E to lau n ch th e W in d ows Exp lorer ap p lication . Th e followin g table sh ows a list of all th e n ew W in d ows 95 key com bin ation s:

Keyboards

Key Com binat ion

Act ion

WIN+R

Displays the Run dialog box

WIN+M

M inimizes All

Shift+WIN+M

Undoes M inimize All

WIN+F1

Starts Help

WIN+E

Starts Windows Explorer

WIN+F

Finds files or folders

Ctrl+WIN+F

Finds the computer

WIN+Tab

Cycles through Taskbar buttons

WIN+Break

Displays the System Properties dialog box

Th e W in d ows keyboard sp ecification req u ires th at keyboard m akers in crease th e n u m ber of trilogram s in th eir keyboard d esign s. A trilogram is a com bin ation of th ree rap id ly p ressed keys th at p erform a sp ecial fu n ction , su ch as Ctrl+Alt+Delete. Design in g a keyboard so th at th e switch m atrix will correctly registers trilogram s is exp en sive, an d th is featu re, p lu s th e ad d ition al W in d ows keys, will cau se th e p rice of th ese keyboard s to rise. Volu m e sales, h owever, as well as th e n atu ral m arket com p etition , sh ou ld keep th e p rice reason able. Virtu ally every keyboard m an u factu rer is n ow p rod u cin g keyboard s with th ese W in d owssp ecific keys. Som e are also com bin in g th ese n ew keys with oth er featu res. For exam p le, besid es th e n ew W in d ows keys, th e Microsoft Natural Keyboard in clu d es ergon om ic featu res, su ch as sp lit keyp ad s th at are rotated ou t from th e m id d le to en cou rage a straigh t wrist p osition . For u sers accu stom ed to th e stan d ard key arran gem en t, th ese d esign s can take som e gettin g u sed to. Un fortu n ately, th is keyboard (m ad e by Keytron ics for Microsoft) d oes n ot h ave n early as com fortable a feel as th e m ech an ical switch d esign s su ch as Alp s, Lite-On , or NMB. Nor d oes it h ave th e extrem ely h igh -q u ality feel of th e Lexm ark an d Un icom p keyboard s. In ad d ition to th e W in d ows keys, oth er com p an ies, su ch as Lexm ark, NMB, an d Alp s, h ave licen sed a n ew Sp acebar d esign from Keyboard En h an cem en ts, In c. called Erase-Ease. Th is n ew d esign sp lits th e Sp acebar in to two p arts, u sin g th e sh orter left (or op tion ally th e righ t) h alf as an ad d ition al Backsp ace key. If you see a keyboard ad vertisin g 105 keys, th en it p robably h as both th e th ree ad d ition al W in d ows keys an d th e extra Backsp ace key n ext to th e Sp acebar. Alth ou gh th e n ew W in d ows keys are n ot m an d atory wh en ru n n in g W in d ows, an d are n ot yet u n iversally accep ted by PC m an u factu rers, m ore an d m ore n ew PC system s in clu d e keyboard s with th ese extra keys. Th ey can m ake it easier for both exp erien ced tou ch typ ists an d n ovice u sers to access som e of th e fu n ction s of W in d ows an d th eir ap p lication s. Port able Keyboards. On e of th e biggest in flu en ces on keyboard d esign in recen t years h as been th e p roliferation of lap top an d n otebook system s. Becau se of size lim itation s, it is obviou sly n ot p ossible to u tilize th e stan d ard keyboard layou t for a p ortable com p u ter. Man u factu rers h ave com e u p with m an y d ifferen t solu tion s. Un fortu n ately, n on e

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of th ese solu tion s h as becom e an in d u stry stan d ard , as is th e 101-key layou t. Becau se of th e variation s in d esign , an d becau se a p ortable system keyboard is n ot as easily rep laceable as th at of a d esktop system , th e keyboard arran gem en t sh ou ld be an im p ortan t p art of you r p u rch asin g d ecision . Early lap top system s often u sed sm aller th an n orm al keys to m in im ize th e size of th e keyboard , wh ich resu lted in m an y com p lain ts from u sers. Tod ay, th e keytop s on p ortable system s are u su ally com p arable in size to th at of a d esktop keyboard , alth ou gh som e system s in clu d e h alf-sized keytop s for th e fu n ction keys an d oth er lesser-u sed keyboard elem en ts. In ad d ition , con su m er d em an d h as cau sed m ost m an u factu rers to retain th e in verted T d esign for th e cu rsor keys after a few abortive attem p ts at ch an gin g th eir arran gem en t. Of cou rse, th e m ost obviou s d ifferen ce in a p ortable system keyboard is th e sacrifice of th e n u m eric keyp ad . Most system s n ow em bed th e keyp ad in to th e stan d ard alp h abetical p art of th e keyboard , as sh own in Figu re 7.5. To switch th e keys from th eir stan d ard valu es to th eir keyp ad valu es, you typ ically m u st p ress a key com bin ation in volvin g a p rop rietary fu n ction key, often labeled Fn .

7

8

9

4

5 1 0

* 6

2

– +

3 .

/

FIG. 7.5 Most p ortable system s tod ay em bed th e n u m eric keyp ad in to an od d ly sh ap ed block of keys on th e alp h abetical p art of th e keyboard .

Th is is an extrem ely in con ven ien t solu tion , an d m an y u sers aban d on th eir u se of th e keyp ad en tirely on p ortable system s. Un fortu n ately, som e activities, su ch as th e en try of ASCII cod es u sin g th e Alt key, req u ire th e u se of th e keyp ad n u m bers, wh ich can be q u ite fru stratin g on system s u sin g th is arran gem en t. In ad d ition to keyp ad con trol, th e Fn key is often u sed to trigger oth er p rop rietary featu res in p ortable system s, su ch as togglin g between an in tern al an d extern al d isp lay an d con trollin g screen brigh tn ess an d sou n d volu m e. Som e p ortable system m an u factu rers h ave gon e to great len gth s to p rovid e u sers with ad eq u ate keyboard s. For a sh ort tim e, IBM m arketed system s with a keyboard th at u sed a “bu tterfly” d esign . Th e keyboard was sp lit in to two h alves th at rested on top of on e an oth er wh en th e system was closed . W h en you op en ed th e lid , th e two h alves sep arated to rest sid e-by-sid e, form in g a keyboard th at was actu ally larger th an th e com p u ter case. Iron ically, th e tren d toward larger-sized d isp lays in p ortable system s h as m ad e th is sort of arran gem en t u n n ecessary. Man y m an u factu rers h ave in creased th e footp rin t of th eir

Keyboards

com p u ters to accom m od ate 12- an d even 14-in ch d isp lay p an els, leavin g m ore room for th e exp an sion of th e keyboard . ◊◊ See “ Keyboards,” p. 937

Com pat ibilit y Th e 83-key PC/ XT typ e is d ifferen t from all th e oth ers. It n orm ally p lu gs in to on ly 8-bit PC/ XT system s th at d o n ot u se th e m oth erboard -based 8042-typ e keyboard con troller ch ip . Th is is d efin itely tru e for IBM’s keyboard s, as well as for m an y com p atible u n its. Som e com p atibles m ay be switch able to work with an AT-typ e m oth erboard via an XT/ AT switch . Th e 84-key u n it from IBM works on on ly AT-typ e 16-bit (or greater) m oth erboard s. It d oes n ot work at all with PC/ XT system s. Again , som e afterm arket d esign s m ay h ave an XT/ AT switch to allow for com p atibility with PC/ XT-typ e system s. If you h ave th e keyboard set in th e wron g m od e, it will n ot work, bu t n o d am age will occu r. Th e En h an ced keyboard s from IBM are u n iversal. Th ey are also auto-switching, wh ich m ean s th at th ey work in virtu ally an y system —from th e XT to th e PS/ 2 or an y PCcom p atible—after you p lu g th em in . Som e m ay also req u ire th at a switch be m oved on th e keyboard to m ake it com p atible with PC/ XT system s th at d o n ot h ave th e 8042-typ e keyboard con troller on th e m oth erboard . In som e cases, you m ay also n eed to switch to a d ifferen t cable with th e p rop er system en d con n ector or u se an ad ap ter. Alth ou gh th e En h an ced keyboard is electrically com p atible with an y AT-typ e m oth erboard an d even m ost PC/ XT-typ e m oth erboard s, m an y old er system s will h ave software p roblem s u sin g th ese keyboard s. IBM ch an ged th e ROM on th e system s to su p p ort th e n ew keyboard p rop erly, an d th e com p atible ven d ors followed su it. Very old (1986 or earlier) m ach in es m ay req u ire a ROM u p grad e to p rop erly u se som e of th e featu res on th e 101-key En h an ced keyboard s, su ch as th e F11 an d F12 keys. If th e in d ivid u al system ROM BIOS is n ot cap able of op eratin g th e 101-key keyboard correctly, th e 101-key keyboard m ay n ot work at all (as with all th ree ROM version s of th e IBM PC). Th e ad d ition al keys (F11 an d F12 fu n ction keys) m ay n ot work, or you m ay h ave p roblem s with keyboard op eration in gen eral. In som e cases, th ese com p atibility p roblem s cau se im p rop er ch aracters to ap p ear wh en keys are typ ed (cau sin g th e system to beep ), an d gen eral keyboard op eration is a p roblem . Th ese p roblem s can often be solved by a ROM u p grad e to a n ewer version th at h as p rop er su p p ort for th e En h an ced keyboard . In an in form al test, I p lu gged th e n ew keyboard in to an earlier XT. Th e keyboard seem ed to work well. Non e of th e keys th at d id n ot exist p reviou sly, su ch as F11 an d F12, were op erable, bu t th e n ew arrow keys an d n u m eric keyp ad worked . Th e En h an ced keyboard seem s to work on XT or AT system s, bu t it d oes n ot fu n ction on th e origin al PC system s becau se of BIOS an d electrical in terface p roblem s. Man y com p atible version s of th e 101key En h an ced keyboard s h ave a m an u al XT/ AT switch on th e bottom th at m ay en able th e keyboard to work in an origin al PC system .

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Tip If you have an older IBM system, you can tell whether your system has complete ROM BIOS support for the 101-key unit: When you plug in the keyboard and turn on the system unit, the Num Lock light automatically comes on and the numeric keypad portion of the keyboard is enabled. This method of detection is not 100% accurate, but if the light goes on, your BIOS generally supports the keyboard. A notable exception is the IBM AT BIOS, dated 06/ 10/ 85. It turns on the Num Lock light, but still does not properly support the Enhanced keyboard. All IBM BIOS versions dated since 11/ 15/ 85 have proper support for the Enhanced keyboards.

Num Lock On IBM system s th at su p p ort th e En h an ced keyboard , wh en th e system d etects th e keyboard on p ower-u p , it en ables th e Nu m Lock featu re an d th e ligh t goes on . If th e system d etects an old er 84-key AT-typ e keyboard , it d oes n ot en able th e Nu m Lock fu n ction becau se th ese keyboard s d o n ot h ave cu rsor keys sep arate from th e n u m eric keyp ad . W h en th e En h an ced keyboard s first ap p eared in 1986, m an y u sers (in clu d in g m e) were irritated to fin d th at th e n u m eric keyp ad was au tom atically en abled every tim e th e system booted . Most system m an u factu rers su bseq u en tly began in tegratin g a fu n ction in to th e BIOS setu p th at en abled you to sp ecify th e Nu m Lock statu s im p osed d u rin g th e boot p rocess. Som e u sers th ou gh t th at th e au tom atic en ablin g of Nu m Lock was a fu n ction of th e En h an ced keyboard becau se n on e of th e earlier keyboard s seem ed to op erate in th is way. Rem em ber th at th is fu n ction is n ot really a keyboard fu n ction bu t in stead a fu n ction of th e m oth erboard ROM BIOS, wh ich id en tifies an En h an ced 101-key u n it an d tu rn s on th e Nu m Lock as a “favor.” In system s with a BIOS th at can n ot con trol th e statu s of th e n u m eric keyp ad , you can u se th e DOS 6.0 or h igh er version NUMLOCK= p aram eter in CONFIG.SYS to tu rn Nu m Lock on or off, as d esired . If you are ru n n in g a version of DOS earlier th an 6.0, you can u se on e of th e m an y p u blic d om ain p rogram s available for con trollin g th e Nu m Lock fu n ction . Ru n n in g th e p rogram from th e AUTOEXEC.BAT file can set th e n u m eric keyp ad statu s wh en ever th e system reboots. Keyboard Technology Th e tech n ology th at m akes u p a typ ical PC keyboard is very in terestin g. Th is section focu ses on all of th e asp ects of keyboard tech n ology an d d esign , in clu d in g th e keyswitch es, th e in terface between th e keyboard an d th e system , scan cod es, an d th e keyboard con n ectors. Keysw it ch Design. Tod ay’s keyboard s u se an y on e of several switch typ es to create th e action for each key. Most keyboard s u se a variation of th e m ech an ical keyswitch . A m echanical keyswitch relies on a m ech an ical m om en tary con tact typ e switch to m ake th e electrical con tact th at form s a circu it. Som e h igh -en d keyboard s u se a totally d ifferen t n on m ech an ical d esign th at relies on cap acitive switch es. Th is section d iscu sses th ese switch es an d th e h igh ligh ts of each d esign .

Keyboards

Th e m ost com m on typ e of keyswitch is th e m ech an ical typ e, available in th e followin g variation s: ■ Pu re m ech an ical ■ Foam elem en t ■ Ru bber d om e ■ Mem bran e Th e pure m echanical typ e is ju st th at—a sim p le m ech an ical switch th at featu res m etal con tacts in a m om en tary con tact arran gem en t. Th e switch often in clu d es a tactile feedback m echanism , con sistin g of a clip an d sp rin g arran gem en t d esign ed to give a “clicky” feel to th e keyboard an d offer som e resistan ce to th e keyp ress. Several com p an ies, in clu d in g Alp s Electric, Lite-On , an d NMB Tech n ologies, m an u factu re th is typ e of keyboard u sin g switch es obtain ed p rim arily from Alp s Electric. Mech an ical switch es are very d u rable, u su ally h ave self-clean in g con tacts, an d are n orm ally rated for 20 m illion keystrokes, wh ich is secon d on ly to th e cap acitive switch in lon gevity. Th ey also offer excellen t tactile feed back. Foam elem ent m ech an ical switch es were a very p op u lar d esign in som e old er keyboard s. Most of th e old er PC keyboard s, in clu d in g th ose m ad e by Keytron ics an d m an y oth ers, u se th is tech n ology. Th ese switch es are ch aracterized by a foam elem en t with an electrical con tact on th e bottom . Th is foam elem en t is m ou n ted on th e bottom of a p lu n ger th at is attach ed to th e key (see Figu re 7.6). Press down on key top Key top Return spring Flexible foam Foil layer on bottom of foam

Contacts on circuit board

Foil layer makes connection between contacts

FIG. 7.6 Typ ical foam elem en t m ech an ical keyswitch . W h en th e switch is p ressed , a foil con d u ctor on th e bottom of th e foam elem en t closes a circu it on th e p rin ted circu it board below. A retu rn sp rin g p u sh es th e key back u p wh en th e p ressu re is released . Th e foam d am p en s th e con tact, h elp in g to p reven t bou n ce, bu t u n fortu n ately gives th ese keyboard s a “m u sh y” feel. Th e big p roblem with th is typ e of keyswitch d esign is th at th ere is often little tactile feed back. System s with th ese keyboard s som etim es resort to tricks, su ch as clickin g th e PC’s sp eaker to sign ify th at con tact h as been m ad e. Com p aq h as u sed keyboard s of th is typ e (m ad e by Keytron ics) in m an y

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of th eir system s. Preferen ces in keyboard feel are som ewh at su bjective; I p erson ally d o n ot favor th e foam elem en t switch d esign . An oth er p roblem with th is typ e of d esign is th at it is m ore su bject to corrosion on th e foil con d u ctor an d th e circu it board traces below. W h en th is h ap p en s, th e key strikes m ay becom e in term itten t, wh ich can be fru stratin g. Fortu n ately, th ese keyboard s are am on g th e easiest to clean . By d isassem blin g th e keyboard com p letely, you can u su ally rem ove th e circu it board p ortion —with ou t rem ovin g each foam p ad sep arately—an d exp ose th e bottom s of all th e p ad s. Th en you can easily wip e th e corrosion an d d irt off th e bottom of th e foam p ad s an d th e circu it board , th u s restorin g th e keyboard to a “like-n ew” con d ition . Un fortu n ately, over tim e, th e corrosion p roblem will occu r again . I recom m en d u sin g som e Stabilan t 22a from D.W . Electroch em icals to im p rove th e switch con tact action an d to p reven t fu tu re corrosion . Becau se of su ch p roblem s, th e foam elem en t d esign is n ot u sed m u ch an ym ore an d h as been su p ersed ed in p op u larity by th e ru bber d om e d esign . Rubber dom e switch es are m ech an ical switch es th at are sim ilar to th e foam elem en t typ e bu t are im p roved in m an y ways. In stead of a sp rin g, th ese switch es u se a ru bber d om e th at h as a carbon bu tton con tact on th e u n d ersid e. As you p ress a key, th e key p lu n ger p resses on th e ru bber d om e, cau sin g it to resist an d th en collap se all at on ce, m u ch like th e top of an oil can . As th e ru bber d om e collap ses, th e u ser feels th e tactile feed back, an d th e carbon bu tton m akes con tact between th e circu it board traces below. W h en th e key is released , th e ru bber d om e re-form s an d p u sh es th e key back u p . Th e ru bber elim in ates th e n eed for a sp rin g an d p rovid es a reason able am ou n t of tactile feed back with ou t an y sp ecial clip s or oth er p arts. Ru bber d om e switch es u se a carbon bu tton becau se it is resistan t to corrosion an d becau se it h as a self-clean in g action on th e m etal con tacts below. Th e ru bber d om es th em selves are form ed in to a sh eet th at com p letely p rotects th e con tacts below from d irt, d u st, an d even m in or sp ills. Th is typ e of switch d esign is th e sim p lest, an d it u ses th e fewest p arts. Th is m akes th e ru bber d om e keyswitch very reliable an d h elp s m ake th e keyboard s th at u se it th e m ost p op u lar in service tod ay. If th e ru bber d om e keyboard h as an y d rawback, it is th at th e tactile feed back is n ot as good as m an y u sers wou ld like. Alth ou gh m an y p eop le fin d its tou ch accep table, som e u sers p refer m ore tactile feed back th an ru bber d om e keyboard s n orm ally p rovid e. Th e m em brane keyboard is a variation on th e ru bber d om e typ e. Th e keys th em selves are n o lon ger sep arate, bu t in stead are form ed togeth er in a sh eet th at sits on th e ru bber d om e sh eet. Th is arran gem en t severely lim its key travel. For th is reason , m em bran e keyboard s are n ot con sid ered u sable for n orm al tou ch typ in g. However, th ey are id eal for u se in extrem ely h arsh en viron m en ts. Becau se th e sh eets can be bon d ed togeth er an d sealed from th e elem en ts, m em bran e keyboard s can be u sed in situ ation s in wh ich n o oth er typ e cou ld su rvive. Man y in d u strial ap p lication s u se m em bran e keyboard s for term in als th at d o n ot req u ire exten sive d ata en try bu t are u sed in stead to op erate eq u ip m en t, su ch as cash registers.

Keyboards

Capacitive switch es are th e on ly n on m ech an ical typ es of keyswitch in u se tod ay (see Figu re 7.7). Th e cap acitive switch is th e Cad illac of keyswitch es. It is m u ch m ore exp en sive th an th e m ore com m on m ech an ical ru bber d om e, bu t is m ore resistan t to d irt an d corrosion an d offers th e h igh est-q u ality tactile feed back of an y typ e of switch . Key Return spring

Upper plate is movable Lower plate is fixed

Oscillator

Reference

Phase lock loop

Comparator

Output

FIG. 7.7 A cap acitive keyswitch . A cap acitive switch d oes n ot work by m akin g con tact between con d u ctors. In stead , two p lates u su ally m ad e of p lastic are con n ected in a switch m atrix th at is d esign ed to d etect ch an ges in th e cap acitan ce of th e circu it. W h en th e key is p ressed , th e p lu n ger m oves th e top p late relative to th e fixed bottom p late. Usu ally a m ech an ism p rovid es for a d istin ct over-cen ter tactile feed back with a resou n d in g “click.” As th e top p late m oves, th e cap acitan ce between th e two p lates ch an ges. Th e com p arator circu itry in th e keyboard d etects th is ch an ge. Becau se th is typ e of switch d oes n ot rely on m etal con tacts, it is n early im m u n e to corrosion an d d irt. Th ese switch es are very resistan t to th e key bou n ce p roblem s th at resu lt in m u ltip le ch aracters ap p earin g from a sin gle strike. Th ey are also th e m ost d u rable in th e in d u stry—rated for 25 m illion or m ore keystrokes, as op p osed to 10 to 20 m illion for oth er d esign s. Th e tactile feed back is u n su rp assed becau se th e switch p rovid es a relatively lou d click an d a stron g over-cen ter feel. Th e on ly d rawback to th e d esign is th e cost. Cap acitive switch keyboard s are am on g th e m ost exp en sive d esign s. Th e q u ality of th e feel an d th eir d u rability m ake th em worth th e p rice, h owever. Trad ition ally, th e on ly ven d ors of cap acitive keyswitch keyboard s h ave been IBM an d th e in h eritors of its keyboard tech n ology, Lexm ark an d Un icom p . The Keyboard Int erface. A keyboard con sists of a set of switch es m ou n ted in a grid or array called th e key m atrix. W h en a switch is p ressed , a p rocessor in th e keyboard id en tifies wh ich key is p ressed by d eterm in in g wh ich grid location in th e m atrix sh ows con tin u ity. Th e keyboard p rocessor, wh ich also in terp rets h ow lon g th e key is p ressed , can even h an d le m u ltip le keyp resses at th e sam e tim e. A 16-byte h ard ware bu ffer in th e keyboard can h an d le rap id or m u ltip le keyp resses, p assin g each on e to th e system in su ccession .

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W h en you p ress a key, th e con tact bou n ces sligh tly in m ost cases, m ean in g th at th ere are several rap id on -off cycles ju st as th e switch m akes con tact. Th is is called bounce. Th e p rocessor in th e keyboard is d esign ed to filter th is, or debounce th e keystroke. Th e keyboard p rocessor m u st d istin gu ish bou n ce from a d ou ble keystrike th at th e keyboard op erator in ten d s to m ake. Th is is fairly easy becau se th e bou n cin g is m u ch m ore rap id th an a p erson cou ld sim u late by strikin g a key q u ickly several tim es. Th e keyboard in a PC is actu ally a com p u ter itself. It com m u n icates with th e m ain system th rou gh a sp ecial serial d ata lin k. Th is lin k tran sm its an d receives d ata in 11-bit p ackets of in form ation , con sistin g of eigh t d ata bits, p lu s fram in g an d con trol bits. Alth ou gh it is in d eed a serial lin k (in th at th e d ata flows on on e wire), th e keyboard in terface is n ot com p atible with th e stan d ard RS-232 serial p ort com m on ly u sed to con n ect m od em s. Th e p rocessor in th e origin al PC keyboard was an In tel 8048 m icrocon troller ch ip . Newer keyboard s often u se an 8049 version th at h as bu ilt-in ROM or oth er m icrocon troller ch ip s com p atible with th e 8048 or 8049. For exam p le, in its En h an ced keyboard s, IBM h as always u sed a cu stom version of th e Motorola 6805 p rocessor, wh ich is com p atible with th e In tel ch ip s. Th e keyboard ’s bu ilt-in p rocessor read s th e key m atrix, d ebou n ces th e keyp ress sign als, con verts th e keyp ress to th e ap p rop riate scan cod e, an d tran sm its th e cod e to th e m oth erboard . Th e p rocessors bu ilt in to th e keyboard con tain th eir own RAM, p ossibly som e ROM, an d a bu ilt-in serial in terface. In th e origin al PC/ XT d esign , th e keyboard serial in terface is con n ected to an 8255 Program m able Perip h eral In terface (PPI) ch ip on th e m oth erboard of th e PC/ XT. Th is ch ip is con n ected to th e in terru p t con troller IRQ1 lin e, wh ich is u sed to sign al to th e system th at keyboard d ata is available. Th e d ata is sen t from th e 8255 to th e p rocessor via I/ O p ort ad d ress 60h . Th e IRQ1 sign al cau ses th e m ain system p rocessor to ru n a su brou tin e (INT 9h) th at in terp rets th e keyboard scan cod e d ata an d d ecid es wh at to d o. In an AT-typ e keyboard d esign , th e keyboard serial in terface is con n ected to a sp ecial keyboard con troller on th e m oth erboard . Th is con troller is an In tel 8042 Un iversal Perip h eral In terface (UPI) slave m icrocon troller ch ip in th e origin al AT d esign . Th is m icrocon troller is essen tially an oth er p rocessor th at h as its own 2K of ROM an d 128 bytes of RAM. An 8742 version th at u ses EPROM (Erasable Program m able Read Only Mem ory) can be erased an d rep rogram m ed . In th e p ast, wh en you p u rch ased a m oth erboard ROM u p grad e from a m oth erboard m an u factu rer for an old er system , th e u p grad e in clu d ed a n ew keyboard con troller ch ip as well becau se it h ad som ewh at d ep en d en t an d u p d ated ROM cod e in it. Som e system s m ay u se th e 8041 or 8741 ch ip s, wh ich d iffer on ly in th e am ou n t of bu ilt-in ROM or RAM, wh ereas oth er system s n ow h ave th e keyboard con troller bu ilt in to th e m ain system ch ip set. In an AT system , th e (8048-typ e) m icrocon troller in th e keyboard sen d s d ata to th e (8042-typ e) keyboard con troller on th e m oth erboard . Th e m oth erboard -based con troller can also sen d d ata back to th e keyboard . W h en th e keyboard con troller on th e m oth erboard receives d ata from th e keyboard , it sign als th e m oth erboard with an IRQ1 an d sen d s th e d ata to th e m ain m oth erboard p rocessor via I/ O p ort ad d ress 60h , ju st as in th e PC/ XT. Actin g as an agen t between th e keyboard an d th e m ain system p rocessor, th e 8042-typ e keyboard con troller can tran slate scan cod es an d p erform several oth er

Keyboards

fu n ction s as well. Th e system can also sen d d ata to th e 8042 keyboard con troller via p ort 60h , wh ich th en p asses it on to th e keyboard . Ad d ition ally, wh en th e system n eed s to sen d com m an d s to or read th e statu s of th e keyboard con troller on th e m oth erboard , it read s or writes th rou gh I/ O p ort 64h . Th ese com m an d s are u su ally followed by d ata sen t back an d forth via p ort 60h . In old er system s, th e 8042 keyboard con troller is also u sed by th e system to con trol th e A20 m em ory ad d ress lin e, wh ich p rovid es access to system m em ory greater th an 1M. More m od ern m oth erboard s u su ally in corp orate th is fu n ction ality d irectly in to th e m oth erboard ch ip set. √√ See “ High M emory Area (HM A) and the A20 Line,” p. 378

Typem at ic Funct ions. If a key on th e keyboard is h eld d own , it becom es typem atic, wh ich m ean s th at th e keyboard rep eated ly sen d s th e keyp ress cod e to th e m oth erboard . In th e AT-style keyboard s, th e typ em atic rate is ad ju sted by sen d in g th e ap p rop riate com m an d s to th e keyboard p rocessor. Th is is n ot p ossible for th e earlier PC/ XT keyboard typ es becau se th e keyboard in terface for th ese typ es is n ot bid irection al. AT-style keyboard s h ave p rogram m able typ em atic rep eat rate an d d elay p aram eters. Most op eratin g system s in clu d e fu n ction s th at en able you to ad ju st th ese p aram eters to you r own sp ecification s. In W in d ows 9x an d W in d ows NT, you u se th e Keyboard Con trol Pan el. In DOS, you u se th e MODE com m an d . Ad ju st i n g Ke y b o a rd P a ra m e t e rs i n W i n d o w s 9 x / NT/ 3 .x . To m od ify th e d efau lt valu es for th e typ em atic rep eat rate an d d elay p aram eters in an y version of W in d ows, you op en th e Keyboard Con trol Pan el. In W in d ows 95, 98, an d NT, th e con trols are located on th e Sp eed p age, as sh own in Figu re 7.8. Th e Rep eat Delay slid er con trols th e am ou n t of tim e a key m u st be p ressed before th e ch aracter begin s to rep eat, an d th e Rep eat Rate slid er con trols h ow fast th e ch aracter rep eats after th e d elay h as elap sed .

FIG. 7.8 W in d ows 9x an d NT p rovid e grap h ical con trols for th e keyboard typ em atic p aram eters.

459

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Chapter 7—Input Devices

Not e The increments on the Repeat Delay and Repeat Rate sliders in the Keyboard Control Panel correspond to the timings given for the MODE command’s RATE and DELAY values, as listed in Tables 7.1 and 7.2 later in this chapter.

Th e d ialog box also con tain s a text box you can u se to test th e settin gs you h ave ch osen before com m ittin g th em to you r system . W h en you click in th e box an d p ress a key, th e keyboard reacts u sin g th e settin gs cu rren tly sp ecified by th e slid ers, even if you h ave n ot yet ap p lied th e ch an ges to th e W in d ows en viron m en t.

Not e In Windows 3.1, the settings in the Keyboard Control Panel override any typematic settings that you may have applied in DOS using the MODE command.

Ad ju st i n g Ke y b o a rd P a ra m e t e rs i n D OS. In DOS version s 4.0 an d later, th e MODE com m an d en ables you to set th e keyboard typ em atic (rep eat) rate, as well as th e d elay, before typ em atic action begin s. Th e d efau lt valu e for th e RATE p aram eter (r) is 20 for m ost PC system s an d 21 for IBM PS/ 2 system s. Th e d efau lt valu e for th e DELAY p aram eter (d) is 2. Th u s, for m ost system s, th e stan d ard keyboard typ em atic sp eed is 10cp s (ch aracters p er secon d ), an d th e d elay before typ em atic action occu rs is 0.5 secon d s. To u se th e DOS MODE com m an d to reset th e keyboard typ em atic rate an d d elay, u se th e followin g com m an d : MODE CON[:] [RATE=r DELAY=d]

Th e accep table valu es for th e rate r an d th e resu ltan t typ em atic rate in cp s are sh own in Table 7.1. Table 7.1

DOS 4.0+ M ODE Com m and Keyboard Typem at ic Rat e Param et ers

Rat e No.

Rat e ± 20%

Rat e No.

Rat e ± 20%

32

30.0cps

16

7.5cps

31

26.7cps

15

6.7cps

30

24.0cps

14

6.0cps

29

21.8cps

13

5.5cps

28

20.0cps

12

5.0cps

27

18.5cps

11

4.6cps

26

17.1cps

10

4.3cps

25

16.0cps

9

4.0cps

24

15.0cps

8

3.7cps

23

13.3cps

7

3.3cps

Keyboards

Rat e No.

Rat e ± 20%

Rat e No.

Rat e ± 20%

22

12.0cps

6

3.0cps

21

10.9cps

5

2.7cps

20

10.0cps

4

2.5cps

19

9.2cps

3

2.3cps

18

8.6cps

2

2.1cps

17

8.0cps

1

2.0cps

Table 7.2 sh ows th e valu es for DELAY an d th e resu ltan t d elay tim e in secon d s. Table 7.2

DOS M ODE Com m and Keyboard Typem at ic Delay Param et ers

DELAY No.

Delay Tim e

1

0.25sec

2

0.50sec

3

0.75sec

4

1.00sec

For exam p le, wh en ru n n in g DOS, I always p lace th e followin g com m an d in m y AUTOEXEC.BAT file: MODE CON: RATE=32 DELAY=1

Th is com m an d sets th e typ em atic rate to th e m axim u m sp eed p ossible, or 30cp s. It also trim s th e d elay to th e m in im u m of 0.25 secon d s before rep eatin g begin s. Th is com m an d “tu rboch arges” th e keyboard an d m akes op eration s req u irin g rep eated keystrokes work m u ch faster, su ch as m ovin g with in a file by u sin g arrow keys. Th e q u ick typ em atic action an d sh ort d elay can be d iscon certin g to som e keyboard op erators. Slower typ ists m igh t wan t to leave th eir keyboard sp eed at th e d efau lt u n til th ey becom e m ore p roficien t.

Not e Note that if you are working on a very old system or keyboard, you may receive the following message: Function not supported on this computer

This indicates that your system, keyboard, or both do not support the bidirectional interface or the commands required to change the typematic rate and delay. Upgrading the BIOS or the keyboard may enable this function, but it is probably not cost effective to do this on an older system.

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Not e Some BIOS versions feature keyboard speed selection capability; however, not all of them allow for full control over the speed and delay.

Keyboard Key Num bers and Scan Codes. W h en you p ress a key on th e keyboard , th e p rocessor bu ilt in to th e keyboard (8048- or 6805-typ e) read s th e keyswitch location in th e keyboard m atrix. Th e p rocessor th en sen d s to th e m oth erboard a serial p acket of d ata th at con tain s th e scan cod e for th e key th at was p ressed . In AT-typ e m oth erboard s th at u se an 8042-typ e keyboard con troller, th e 8042 ch ip tran slates th e actu al keyboard scan cod e in to on e of u p to th ree d ifferen t sets of system scan cod es, wh ich are sen t to th e m ain p rocessor. It can be u sefu l in som e cases to kn ow wh at th ese scan cod es are, esp ecially wh en trou blesh ootin g keyboard p roblem s or wh en read in g th e keyboard or system scan cod es d irectly in software. W h en a keyswitch on th e keyboard sticks or oth erwise fails, th e scan cod e of th e failed keyswitch is u su ally rep orted by d iagn ostics software, in clu d in g th e POST (Power-On Self Test), as well as con ven tion al d isk-based d iagn ostics. Th is m ean s th at you h ave to id en tify th e m alfu n ction in g key by its scan cod e. Tables 7.3 th rou gh 7.7 list all th e scan cod es for every key on th e 83-, 84-, an d 101-key keyboard s. By lookin g u p th e rep orted scan cod e on th ese ch arts, you can d eterm in e wh ich keyswitch is d efective or n eed s to be clean ed .

Not e 101-key Enhanced keyboards are capable of three different scan code sets. Set 1 is the default. Some systems, including some of the IBM PS/ 2 machines, use one of the other scan code sets during the POST. For example, my IBM P75 uses Scan Code Set 2 during the POST but switches to Set 1 during normal operation. This is rare, and it really threw me off in diagnosing a stuck key problem at one time. It is useful to know if you are having difficulty interpreting the Scan Code number, however.

IBM also assign s each key a u n iq u e key n u m ber to d istin gu ish it from th e oth ers. Th is is im p ortan t wh en you are tryin g to id en tify keys on foreign keyboard s, wh ich m ay u se d ifferen t sym bols or ch aracters from th e U.S. m od els. In th e case of th e En h an ced keyboard , m ost foreign m od els are m issin g on e of th e keys (key 29) fou n d on th e U.S. version an d h ave two oth er ad d ition al keys (keys 42 an d 45). Th is accou n ts for th e 102-key total rath er th an th e 101 keys fou n d on th e U.S. version . Figu re 7.9 sh ows th e keyboard n u m berin g an d ch aracter location s for th e origin al 83-key PC keyboard . Table 7.3 sh ows th e scan cod es for each key relative to th e key n u m ber an d ch aracter.

Keyboards

59

1

60 F1

61

F2

15

62 F3

63

Q

Ctrl

43

F8

--

F7

30

42

66

4

@ 2 17

31

A 44

W

Z

5

# 3 18

S 45

E 32

X

6

$ 4 19

D 46

R 33

C

7

% 5 20

21

T 34

F 47

V

8

^ 6

G 48

Y 35

9

& 7 22

F10

U 36

H 49

B

10 * 8

N

\

23

J 50

24

I 37

M

11

( 9

K 51 < ,

O 38

12 — –

) 0 25

L

13

40

53 ? / 58

Alt

69

70

Scroll Lock

Num Lock

27

} ]

[

39 : ;

52 > .

14

+ =

26 {

P

57

58

68 F9

16

29 F6

F5

67

3

! 1

F4 64

65

2 Esc

" '

28

71

75

55

Caps Lock

72

Break

73

8

Home

41 ~ `

54

7

82

4

79 1

PrtSc *

74 –

PgUp

76

77

5

80 2

6

PgDn

83

Ins

78

81 3

End

0

9

+

. Del

FIG. 7.9 83-key PC keyboard key n u m ber an d ch aracter location s. Table 7.3 Key Num ber

83-Key ( PC/ XT) Keyboard Key Num bers and Scan Codes Scan Code

Key

Key Num ber

Scan Code

Key

1

01

Esc

29

1D

Ctrl

2

02

1

30

1E

a

3

03

2

31

1F

s

4

04

3

32

20

d

5

05

4

33

21

f

22

g

6

06

5

34

7

07

6

35

23

h

8

08

7

36

24

j

9

09

8

37

25

k

10

0A

9

38

26

l

11

0B

0

39

27

;

12

0C

-

40

28

‘

13

0D

=

41

29

‘

14

0E

Backspace

42

2A

Left Shift

15

0F

Tab

43

2B

\

16

10

q

44

2C

z

17

11

w

45

2D

x

18

12

e

46

2E

c

19

13

r

47

2F

v

20

14

t

48

30

b

21

15

y

49

31

n

22

16

u

50

32

m

23

17

i

51

33

,

24

18

o

52

34

.

25

19

p

53

35

/

26

1A

[

54

36

Right Shift

27

1B

]

55

37

*

28

1C

Enter

56

38

Alt (continues)

463

464

Chapter 7—Input Devices

Table 7.3 83-Key ( PC/ XT) Keyboard Key Num bers and Scan Codes Cont inued Key Num ber

Scan Code

Key

Key Num ber

Scan Code

Key

57

39

Spacebar

71

47

Keypad 7 (Home)

58

3A

Caps Lock

72

48

Keypad 8 (Up arrow)

59

3B

F1

73

49

Keypad 9 (PgUp)

60

3C

F2

74

4A

Keypad -

61

3D

F3

75

4B

Keypad 4 (Left arrow)

62

3E

F4

76

4C

Keypad 5

63

3F

F5

77

4D

Keypad 6 (Right arrow)

64

40

F6

78

4E

Keypad +

65

41

F7

79

4F

Keypad 1 (End)

66

42

F8

80

50

Keypad 2 (Down arrow)

67

43

F9

81

51

Keypad 3 (PgDn)

68

44

F10

82

52

Keypad 0 (Ins)

69

45

Num Lock

83

53

Keypad . (Del)

70

46

Scroll Lock

Figu re 7.10 sh ows th e keyboard n u m berin g an d ch aracter location s for th e origin al 84key AT keyboard . Table 7.4 sh ows th e scan cod es for each key relative to th e key n u m ber an d ch aracter. 70

65 F1

71

F2

72

F6

Q

F8

F7

31 Ctrl

44

68

Shift

F10

Alt

4

@ 2

A

19

32

Z

5

# 3

18 W

46

58

69 F9

17

30

67

74

3

! 1

F4

F5 73

2

16

66 F3

1 ~ `

S 47

20

E 33

X

6

$ 4

D 48

R 34

C

7

% 5 21

F 49

T 35

V

8

^ 6 22

G 50

Y 36

B

9

& 7

10 * 8

23

H 51

U 37

N

24

J 52

I 38

M

11

( 9 25

K

O 39

53 < ,

12 — –

) 0 26

L 54 > .

P

13

14

+ =

27 {

28 }

[

]

40 : ; 55 ? /

41

15

90

95

" '

91

7

96

8

92

43

4

Enter

93

57

64

1

61

End

99 Caps Lock

97

5

98

Shift

0 Ins

84-Key AT Keyboard Key Num bers and Scan Codes

Key Num ber

Scan Code

Key

Key Num ber

Scan Code

Key

1

29

`

8

08

7

2

02

1

9

09

8

3

03

2

10

0A

9

4

04

3

11

0B

0

5

05

4

12

0C

-

6

06

5

13

0D

=

7

07

6

14

2B

\

100 105 Scroll Sys Lock 101

9

106 PrtSc

Pg Up

Home

FIG. 7.10 84-key AT keyboard key n u m ber an d ch aracter location s. Table 7.4

Num Lock

Esc

\

*

102

107

103

108

6

2

-

3 Pg Dn

104

. Del

+

Keyboards

Key Num ber

Scan Code

Key

Key Num ber

Scan Code

Key

15 16

0E

Backspace

53

33

,

0F

Tab

54

34

.

17

10

q

55

35

/

18

11

w

57

36

Right Shift

19

12

e

58

38

Alt

20

13

r

61

39

Spacebar

21

14

t

64

3A

Caps Lock

22

15

y

65

3C

F2

23

16

u

66

3E

F4

24

17

i

67

40

F6

25

18

o

68

42

F8

26

19

p

69

44

F10

27

1A

[

70

3B

F1

28

1B

]

71

3D

F3

30

1D

Ctrl

72

3F

F5

31

1E

a

73

41

F7

32

1F

s

74

43

F9

33

20

d

90

01

Escape

34

21

f

91

47

Keypad 7 (Home)

35

22

g

92

4B

Keypad 4 (Left arrow)

36

23

h

93

4F

Keypad 1 (End)

37

24

j

95

45

Num Lock

38

25

k

96

48

Keypad 8 (Up arrow)

39

26

l

97

4C

Keypad 5

40

27

;

98

50

Keypad 2 (Down arrow)

41

28

‘

99

52

Keypad 0 (Ins)

43

1C

Enter

100

46

Scroll Lock

44

2A

Left Shift

101

49

Keypad 9 (PgUp)

46

2C

z

102

4D

Keypad 6 (Right arrow)

47

2D

x

103

51

Keypad 3 (PgDn)

48

2E

c

104

53

Keypad . (Del)

49

2F

v

105

54

SysRq

50

30

b

106

37

Keypad *

51

31

n

107

4A

Keypad -

52

32

m

108

4E

Keypad +

Figu re 7.11 sh ows th e keyboard n u m berin g an d ch aracter location s for th e 101-key En h an ced keyboard . Table 7.5 sh ows each of th e th ree scan cod e sets for each key relative to th e key n u m ber an d ch aracter. Scan Cod e Set 1 is th e d efau lt; th e oth er two are rarely u sed . Figu re 7.12 sh ows th e layou t of a typ ical foreign lan gu age 102-key version of th e En h an ced keyboard —in th is case, a U.K. version .

465

466

Chapter 7—Input Devices

110

112

Esc

113

F1

1

~ `

2

! 1

16

30

17

44

46

58

5

$ 4

E

R

47

X

7

^ 6

T 34

48

C

60

Ctrl

6

20

F

117

F5

% 5

33

D

116

F4

19

32

S

Z

Shift

4

# 3

W

115

F3

18

31

A

Caps Lock

3

@ 2

Q

Tab

114

F2

21

G 49

V

Y

U

H 50

B

I

J 51

N

M

O

K

11

) 0 25

38

121

F9

10

( 9 24

37

120

F8

9

* 8 23

36

119

F7

8

& 7 22

35

118

F6

P 39

L

52 < 53 ,

12

— – 26

+ =

{ [

" '

F12

28

} ]

126 Pause

Num Lock

Caps Lock

Scroll Lock

Break

Insert

80 Home

76 Delete

\

41

125 Scroll Lock

75

| 29

Page Up

85

81 Page 86

End

Down

43

Num Lock

90

7

95

/ 91

92

100

105

-

*

8 96 9 101

106

Pg Up

Home

4

Enter

97

5

102

6

+

— 83

57

93

1

Shift

98

2

62

64

79

84

89

Ctrl

103

3

108

Pg Dn

End

Alt

Alt

124

Print Screen Sys Aq

15 Backspace

> 54 ? 55 . /

61

123

F11

13

27

40

: ;

122

F10

99

0

104

.

Ins

Enter

Del

FIG. 7.11 101-key En h an ced keyboard key n u m ber an d ch aracter location s (U.S. version ).

110

112

Esc

113

F1

1 `

2

! 1

16

Q

Tab

30

A

Caps Lock

44

| \

3

" 2 17

45

18

S

Z

E 32

46

X

115

F3

4

£ 3

W 31

58 Ctrl

114

F2

$ 4 19

D 47

60

116

F4

5

R 33

C

6

% 5 20

F 48

T 34

V

117

F5

^ 6

7

21

G 49

Y 35

B

118

F6

8

& 7 22

H 50

U 36

N

119

F7

* 8 23

J 51

9

I 37

120

F8

10

( 9 24

K

O 38

) 0 25

L

52 < 53 M ,

61

11

P 39

— – 26

: ;

122

F10

12

{ [

+ = 27

'

> 54 ? 55 . / 62

123

F11

13

F12

124

Print Screen Sys Aq

15

} ]

28

75

43

126 Pause

Num Lock

Caps Lock

Scroll Lock

Break

80 Home

76 Delete

~

125 Scroll Lock

Insert

40 @ 41

Alt Gr

Alt

121

F9

81 End

Page Up Page Down

85

86

42

Num Lock

7

90

95

/ 91

4

#

105

-

8 96 9 101

106

Pg Up

Home

92

100

*

5

97

6

102

+

— 83

57

1

93

2

98

64

79

84

Ctrl

89

0

3

103

108

Pg Dn

End

99

.

104

Enter

Del

Ins

FIG. 7.12 102-key En h an ced keyboard key n u m ber an d ch aracter location s (U.K. En glish version ). Table 7.5 Key Num ber

101/ 102-Key ( Enhanced) Keyboard Key Num bers and Scan Codes Key/ Charact er

Scan Code Set 1

Scan Code Set 2

Scan Code Set 3

1

‘

29

0E

0E

2

1

2

16

16

3

2

3

1E

1E

4

3

4

26

26

5

4

5

25

25

6

5

6

2E

2E

7

6

7

36

36

8

7

8

3D

3D

9

8

9

3E

3E

10

9

0A

46

46

11

0

0B

45

45

12

-

0C

4E

4E

13

=

0D

55

55

15

Backspace

0E

66

66

16

Tab

0F

0D

0D

Keyboards

Key Num ber

Key/ Charact er

Scan Code Set 1

Scan Code Set 2

Scan Code Set 3

17

q

10

15

15

18

w

11

1D

1D

19

e

12

24

24

20

r

13

2D

2D

21

t

14

2C

2C

22

y

15

35

35

23

u

16

3C

3C

24

i

17

43

43

25

o

18

44

44

26

p

19

4D

4D

27

[

1A

54

54

28

]

1B

5B

5B

29

\ (101-key only)

2B

5D

5C

30

Caps Lock

3A

58

14

31

a

1E

1C

1C

32

s

1F

1B

1B

33

d

20

23

23

34

f

21

2B

2B

35

g

22

34

34

36

h

23

33

33

37

j

24

3B

3B

38

k

25

42

42

39

l

26

4B

4B

40

;

27

4C

4C

41

‘

28

52

52

42

# (102-key only)

2B

5D

53

43

Enter

1C

5A

5A

44

Left Shift

2A

12

12

45

\ (102-key only)

56

61

13

46

z

2C

1A

1A

47

x

2D

22

22

48

c

2E

21

21

49

v

2F

2A

2A

50

b

30

32

32

51

n

31

31

31

52

m

32

3A

3A

53

,

33

41

41

54

.

34

49

49

55

/

35

4A

4A (continues)

467

468

Chapter 7—Input Devices

Table 7.5 101/ 102-Key ( Enhanced) Keyboard Key Num bers and Scan Codes Cont inued Key Num ber

Key/ Charact er

Scan Code Set 1

Scan Code Set 2

Scan Code Set 3

57

Right Shift

36

59

59

58

Left Ctrl

1D

14

11

60

Left Alt

38

11

19

61

Spacebar

39

29

29

62

Right Alt

E0,38

E0,11

39

64

Right Ctrl

E0,1D

E0,14

58

75

Insert

E0,52

E0,70

67

76

Delete

E0,53

E0,71

64

79

Left arrow

E0,4B

E0,6B

61

80

Home

E0,47

E0,6C

6E

81

End

E0,4F

E0,69

65

83

Up arrow

E0,48

E0,75

63

84

Down arrow

E0,50

E0,72

60

85

Page Up

E0,49

E0,7D

6F

86

Page Down

E0,51

E0,7A

6D

89

Right arrow

E0,4D

E0,74

6A

90

Num Lock

45

77

76

91

Keypad 7 (Home)

47

6C

6C

92

Keypad 4 (Left arrow) 4B

6B

6B

93

Keypad 1 (End)

4F

69

69

95

Keypad /

E0,35

E0,4A

77

96

Keypad 8 (Up arrow)

48

75

75

97

Keypad 5

4C

73

73

98

Keypad 2 (Down arrow) 50

72

72

99

Keypad 0 (Ins)

52

70

70

100

Keypad *

37

7C

7E

101

Keypad 9 (PgUp)

49

7D

7D

102

Keypad 6 (Left arrow) 4D

74

74

103

Keypad 3 (PgDn)

51

7A

7A

104

Keypad . (Del)

53

71

71

105

Keypad -

4A

7B

84

106

Keypad +

4E

E0,5A

7C

108

Keypad Enter

E0,1C

E0,5A

79

110

Escape

1

76

8

112

F1

3B

5

7

113

F2

3C

6

0F

114

F3

3D

4

17

115

F4

3E

0C

1F

Keyboards

Key Num ber

Key/ Charact er

Scan Code Set 1

Scan Code Set 2

Scan Code Set 3

116

F5

3F

3

27

117

F6

40

0B

2F

118

F7

41

83

37

119

F8

42

0A

3F

120

F9

43

1

47

121

F10

44

9

4F

122

F11

57

78

56

123

F12

58

7

5E

124

Print Screen

E0,2A,E0,37

E0,12,E0,7C

57

125

Scroll Lock

46

7E

5F

126

Pause

E1,1D,45,E1,9D,C5

E1,14,77,E1,F0,14,F0,77

62

Th e n ew keys fou n d on a 104-key W in d ows keyboard h ave th eir own u n iq u e scan cod es. Table 7.6 sh ows th e scan cod es for th e n ew keys. Table 7.6

104-Key W indow s Keyboard New Key Scan Codes Scan Code Set 1

Scan Code Set 2

Scan Code Set 3

Left Windows

E0,5B

E0,1F

8B

Right Windows

E0,5C

E0,27

8C

Application

E0,5D

E0,2F

8D

New Key

Kn owin g th ese key n u m ber figu res an d scan cod es are u sefu l wh en you are trou blesh ootin g stu ck or failed keys on a keyboard . Diagn ostics can rep ort th e d efective keyswitch by th e scan cod e, wh ich varies from keyboard to keyboard on th e ch aracter it rep resen ts an d its location . Int ernat ional Keyboard Layout s. After th e keyboard con troller in th e system receives th e scan cod es gen erated by th e keyboard an d p asses th em to th e m ain p rocessor, th e op eratin g system con verts th e cod es in to th e ap p rop riate alp h an u m erical ch aracters. In th e Un ited States, th ese ch aracters are th e letters, n u m bers, an d sym bols fou n d on th e stan d ard Am erican keyboard . However, n o m atter wh at ch aracters you see on th e keytop s, it is a relatively sim p le m atter to ad ju st th e scan cod e con version p rocess to m ap d ifferen t ch aracters to th e keys. W in d ows 9x an d W in d ows NT take ad van tage of th is cap ability by en ablin g you to in stall m u ltip le keyboard layou ts to su p p ort d ifferen t lan gu ages. W h en you op en th e Keyboard Con trol Pan el an d select th e Lan gu age p age, you see a screen like Figu re 7.13. Th e Lan gu age box sh ou ld d isp lay th e keyboard layou t you selected wh en you in stalled th e op eratin g system . By clickin g th e Ad d bu tton , you can select an y on e of several ad d ition al keyboard layou ts su p p ortin g oth er lan gu ages.

469

470

Chapter 7—Input Devices

FIG. 7.13 Th e Lan gu age p age of th e Keyboard Con trol Pan el p rovid es su p p ort for m u ltip le ch aracter sets.

Th ese keyboard layou ts m ap d ifferen t ch aracters to certain keys on th e stan d ard keyboard . Th e stan d ard Fren ch layou t p rovid es easy access to th e accen ted ch aracters com m on ly u sed in th at lan gu age. For exam p le, p ressin g th e 2 key p rod u ces th e é ch aracter. To typ e th e n u m eral 2, you p ress th e Sh ift+2 key com bin ation . Oth er Fren ch -sp eakin g cou n tries h ave d ifferen t keyboard con ven tion s for th e sam e ch aracters, so W in d ows in clu d es su p p ort for several keyboard layou t variation s for som e lan gu ages, based on n ation ality.

Not e It is important to understand that this feature is not the same as installing the operating system in a different language. These keyboard layouts do not modify the text already displayed on the screen; they only alter the characters generated when you press certain keys.

Th e altern ative keyboard layou ts also d o n ot p rovid e su p p ort for n on -Rom an alp h abets, su ch as Ru ssian an d Ch in ese. Th e accen ted ch aracters an d oth er sym bols u sed in lan gu ages su ch as Fren ch an d Germ an are p art of th e stan d ard ASCII ch aracter set. Th ey are always accessible to En glish -lan gu age u sers th rou gh th e W in d ows Ch aracter Map u tility or th rou gh th e u se of Alt+keyp ad com bin ation s. An altern ative keyboard layou t sim p ly p rovid es an easier way to access th e ch aracters u sed in certain lan gu ages. If you work on d ocu m en ts u sin g m ore th an on e lan gu age, you can in stall as m an y keyboard layou ts as n ecessary an d switch between th em at will. W h en you click th e En able In d icator on Taskbar ch eckbox on th e Lan gu age p age of th e Keyboard Con trol Pan el, a selector ap p ears in th e Taskbar’s tray area th at en ables you to switch lan gu ages easily. On th e sam e p age, you can en able a key com bin ation th at switch es between th e in stalled keyboard layou ts. Keyboard/ M ouse Int erface Connect ors. Keyboard s h ave a cable with on e of two p rim ary typ es of con n ectors at th e system en d . On m ost afterm arket keyboard s, th e cable is con n ected in sid e th e keyboard case on th e keyboard en d , req u irin g you to op en u p th e

Keyboards

keyboard case to d iscon n ect or test it. En h an ced keyboard s m an u factu red by IBM u se a u n iq u e cable assem bly th at p lu gs in to both th e keyboard an d th e system u n it. Th is m akes cable in terch an ge or rep lacem en t an easy p lu g-in affair. A sp ecial con n ector called an SDL (Shielded Data Link) is u sed at th e keyboard en d , an d th e ap p rop riate DIN con n ector is u sed at th e PC en d . An y IBM keyboard or cable can be ord ered sep arately as a sp are p art. Th e n ewer En h an ced keyboard s com e with an extern ally d etach able keyboard cable th at p lu gs in to th e keyboard p ort with a sp ecial con n ector, m u ch like a telep h on e con n ector. Th e oth er en d of th e cable is of on e of th e followin g two typ es: ■ 5-pin DIN connector. Used on m ost PC system s with Baby-AT form factor m oth erboard s. ■ 6-pin m ini-DIN connector. Used on PS/ 2 system s an d m ost PCs with LPX, ATX, an d NLX m oth erboard s. Figu re 7.14 an d Table 7.7 sh ow th e p h ysical layou t an d p in ou ts of all th e resp ective keyboard con n ector p lu gs an d sockets. Plug

Socket

1

3

3

4

5

1

5

4

5-pin DIN 2

2

Plug

Socket 6

5 3

6-pin mini-DIN

1

4

2

A

B

C

3 2

1

Socket

Plug 6-pin SDL

5

6 4

D

E

F

F

E

D

C

B

A

FIG. 7.14 Keyboard an d m ou se con n ectors. Table 7.7

Keyboard Connect or Signals

Signal Nam e

5-Pin DIN

6-Pin M ini-DIN

6-Pin SDL

Keyboard Data

2

1

B

Ground

4

3

C

+5v

5

4

E (continues)

471

472

Chapter 7—Input Devices

Table 7.7

Keyboard Connect or Signals Cont inued

Signal Nam e

5-Pin DIN

6-Pin M ini-DIN

6-Pin SDL

Keyboard Clock

1

5

D

Not Connected

—

2

A

Not Connected

—

6

F

Not Connected

3

—

—

DIN = Germ an Industrial Norm (Deutsche Industrie Norm ), a com m ittee that sets Germ an dim ensional standards SDL = Shielded Data Link, a type of shielded connector created by AMP and used by IBM and others for keyboard cables

Moth erboard m ou se con n ectors also u se th e 6-p in m in i-DIN con n ector an d h ave th e sam e p in ou t an d sign al d escrip tion s as th e keyboard con n ector; h owever, th e d ata p ackets are in com p atible. Th is m ean s th at you can easily p lu g a m oth erboard m ou se (PS/ 2 style) in to a m in i-DIN keyboard con n ector or p lu g th e m in i-DIN typ e keyboard con n ector in to a m oth erboard m ou se p ort; h owever, n eith er on e will work p rop erly in th is situ ation .

Caut ion I have also seen PCs with external power supplies that used the same standard DIN connectors to attach the keyboard and the power supply. Although cross-connecting the mini-DIN connectors of a mouse and a keyboard is a harmless annoyance, connecting a power supply to a keyboard socket can be disastrous.

Keyboards w it h Special Feat ures. A n u m ber of keyboard s on th e m arket h ave sp ecial featu res n ot fou n d in th e stan d ard d esign s. Th ese ad d ition al featu res ran ge from sim p le th in gs, su ch as bu ilt-in calcu lators an d clocks, to m ore com p licated featu res, su ch as in tegrated p oin tin g d evices, sp ecial ch aracter layou ts, sh ap es, an d even p rogram m able keys. Th e D v o ra k Ke y b o a rd . Over th e years, m an y p eop le h ave attem p ted to ch an ge th e d esign of th e stan d ard keyboard in ord er to im p rove typ in g sp eed an d ergon om ics. Th e stan d ard QW ERTY layou t (so n am ed for th e first six letters below th e n u m ber keys) th at we are all fam iliar with tod ay was d esign ed p rim arily to facilitate th e m ech an ical n eed s of early m an u al typ ewriters. Th e arran gem en t of th e letters h elp ed p reven t th e keys from jam m in g togeth er as th ey flew u p to strike th e p ap er. Arou n d 1936, Au gu st Dvorak an d W illiam L. Dealy d evelop ed a m od ified ch aracter layou t for th e keyboard th at was in ten d ed to rep lace th e QW ERTY layou t. It was d esign ed with th e typ ist’s n eed s in m in d . Th e Dvorak-Dealy keyboard d esign is n orm ally called th e Dvorak d esign . It featu red d ifferen t ch aracter p osition s on th e keys th at were d esign ed to p rom ote th e altern ation of h an d s d u rin g typ in g. Th e ch aracters are arran ged so th at th e vowels are in th e h om e row u n d er th e left h an d , wh ile th e con son an ts u sed m ost freq u en tly are p laced in th e h om e row u n d er th e righ t h an d . Th e th eory was th at th is form at wou ld d ram atically im p rove typ in g sp eed ; h owever, m ost tests sh ow on ly m od est im p rovem en ts. Th e Dvorak keyboard d esign still h as its d evotees, bu t it h as n ot ach ieved wid esp read

Keyboards

p op u larity, largely d u e to th e d ifficu lty of switch in g from th e fam iliar QW ERTY layou t, wh ich is still by far th e m ost com m on ly u sed d esign . Erg o n o m i c Ke y b o a rd s. A m ore recen t tren d is to ch an ge th e sh ap e of th e keyboard in stead of alterin g th e ch aracter layou t. Th is h as resu lted in a n u m ber of d ifferen t socalled ergon om ic d esign s. Th e goal is to sh ap e th e keyboard to better fit th e h u m an h an d . Th e m ost com m on of th ese d esign s sp lits th e keyboard in th e cen ter, ben d in g th e sid es ou tward . Som e of th ese d esign s allow th e an gle between th e sid es to be ad ju sted , su ch as th e Lexm ark Select-Ease d esign . Oth ers, su ch as th e Microsoft Natu ral Keyboard , are fixed . Th ese sp lit or ben t d esign s m ore easily con form to th e n atu ral an gle of th e h an d s wh ile typ in g th an th e stan d ard keyboard . Th ey can im p rove p rod u ctivity an d typ in g sp eed an d h elp p reven t rep etitive strain in ju ries, su ch as carp al tu n n el syn d rom e (ten d on in flam m ation ). Virtu ally every keyboard com p an y n ow h as som e form of sim ilar ergon om ic keyboard , an d th e sam e criteria ap p ly with resp ect to q u ality an d feel as with th e stan d ard keyboard d esign s. On e of th e m ost p op u lar ergon om ic keyboard s, th e Microsoft Natu ral Keyboard , is m an u factu red for Microsoft by Keytron ics. It u ses th e in exp en sive keyswitch es th ey are kn own for. For th ose wh o p refer a m ore ru gged keyboard with h igh er-q u ality switch es, I recom m en d th e Lexm ark Select-Ease, Alp s, NMB Tech n ologies, or Lite-On keyboard s. Th ese keyboard s are available with very h igh -q u ality m ech an ical switch es th at h ave a p ositive tactile feel to th em . Th e Lexm ark d esign , in p articu lar, allows you to ad ju st th e an gle between th e two sid es of th e keyboard from fu lly closed like a stan d ard keyboard , to sp lit at virtu ally an y an gle. You can even sep arate th e two h alves com p letely. It also featu res bu ilt-in p alm rests, an oversized Sp acebar, an d cu rsor keys on both sid es of th e keyboard . Becau se of th eir n ovelty an d th eir tren d y ap p eal, som e ergon om ic keyboard s can be con sid erably m ore exp en sive th an trad ition al d esign s, bu t for u sers with m ed ical p roblem s cau sed or exacerbated by im p rop er p osition in g of th e wrists at th e keyboard , th ey can be an im p ortan t rem ed y to a seriou s p roblem . Gen eral u sers, h owever, are h igh ly resistan t to ch an ge, an d th ese d esign s h ave yet to sign ifican tly d isp lace th e stan d ard keyboard layou t. P ro g ra m m a b l e Ke y b o a rd s. Several com p an ies, in clu d in g Maxi-Switch , h ave in trod u ced keyboard s th at featu re p rogram m able keys. You can assign d ifferen t keystrokes or m acros to keys, or even rep rogram th e en tire keyboard layou t. Th is typ e of keyboard h as been su p p lied in th e p ast by som e of th e m ajor PC ven d ors, su ch as Gateway 2000. At on e tim e I u sed a n u m ber of th ese keyboard s in th e sem in ars I teach . Un fortu n ately, I fou n d th e p rogram m in g fu n ction s d ifficu lt to rem em ber. Accid en tally p ressin g th e p rogram m in g con trol keys wou ld often p u t th e keyboard in to an altered state, req u irin g it to be reset. In a bu sin ess en viron m en t, th is p h en om en on resu lted in an an n oyin g n u m ber of tech n ical su p p ort calls from m ystified u sers wh o were won d erin g wh y th eir keyboard s were locked u p . On e oth er p roblem was th at th e extra keys ad d ed wid th to th e keyboard , m akin g it wid er th an m ost oth er stan d ard d esign s. I q u ickly d ecid ed th at th e p rogram m in g fu n ction s were so rarely u sed th at th ey were sim p ly n ot worth th e h assle an d sp ecified stan d ard keyboard s for fu tu re p u rch ases.

473

474

Chapter 7—Input Devices

Keyboard Troubleshoot ing and Repair Keyboard errors are u su ally cau sed by two sim p le p roblem s. Oth er m ore d ifficu lt, in term itten t p roblem s can arise, bu t th ey are m u ch less com m on . Th e m ost freq u en t p roblem s are as follows: ■ Defective cables ■ Stu ck keys Defective cables are easy to sp ot if th e failu re is n ot in term itten t. If th e keyboard stop s workin g altogeth er or every keystroke resu lts in an error or in correct ch aracter, th e cable is likely th e cu lp rit. Trou blesh ootin g is sim p le, esp ecially if you h ave a sp are cable on h an d . Sim p ly rep lace th e su sp ected cable with on e from a kn own , workin g keyboard to verify wh eth er th e p roblem still exists. If it d oes, th e p roblem m u st be elsewh ere. You also can test th e cable for con tin u ity wh en it is rem oved from th e keyboard by u sin g a Digital Multi-Meter (DMM). DMMs th at h ave an au d ible con tin u ity tester bu ilt in m ake th is p roced u re m u ch easier to p erform . W iggle th e en d s of th e cable as you ch eck each wire to m ake su re th ere are n o in term itten t con n ection s. If you d iscover a p roblem with th e con tin u ity in on e of th e wires, rep lace th e cable or th e en tire keyboard , wh ich ever is ch eap er. Becau se rep lacem en t keyboard s are so in exp en sive, som etim es it can be ch eap er to rep lace th e en tire u n it th an to get a n ew cable. Man y tim es you first d iscover a p roblem with a keyboard becau se th e system h as an error d u rin g th e POST. Most system s u se error cod es in a 3xx n u m eric form at to d istin gu ish th e keyboard . If you h ave an y su ch errors d u rin g th e POST, write th em d own . Som e BIOS version s d o n ot u se cryp tic n u m eric error cod es; th ey sim p ly state som eth in g like th e followin g: Keyboard stuck key failure

Th is m essage n orm ally wou ld be d isp layed by a system with a Ph oen ix BIOS if a key were stu ck. Un fortu n ately, th e m essage d oes n ot id en tify wh ich key it is! If you r system d isp lays a 3xx (keyboard ) error th at is p reced ed by a two-d igit h exad ecim al n u m ber, th e n u m ber is th e scan cod e of a failin g or stu ck keyswitch . Look u p th e scan cod e in th e tables p rovid ed in th is section to d eterm in e wh ich keyswitch is th e cu lp rit. By rem ovin g th e keycap of th e offen d in g key an d clean in g th e switch , you can often solve th e p roblem . For a sim p le test of th e m oth erboard keyboard con n ector, you can ch eck voltages on som e of th e p in s. Usin g Figu re 7.14 as a gu id e, m easu re th e voltages on variou s p in s of th e keyboard con n ector. To p reven t p ossible d am age to th e system or keyboard , tu rn off th e p ower before d iscon n ectin g th e keyboard . Th en u n p lu g th e keyboard an d tu rn th e p ower back on . Make m easu rem en ts between th e grou n d p in an d th e oth er p in s accord in g to Table 7.8. If th e voltages are with in th ese sp ecification s, th e m oth erboard keyboard circu itry is p robably okay. Table 7.8

Keyboard Connect or Specificat ions

DIN Connect or Pin M ini-DIN Connect or Pin

Signal

Volt age

1

5

Keyboard Clock

+2.0v to +5.5v

2

1

Keyboard Data

+4.8v to +5.5v

Keyboards

DIN Connect or Pin M ini-DIN Connect or Pin

Signal

Volt age

3

-

Reserved

—

4

3

Ground

—

5

4

+5v Power

+2.0v to +5.5v

If you r m easu rem en ts d o n ot m atch th ese voltages, th e m oth erboard m igh t be d efective. Oth erwise, th e keyboard cable or keyboard m igh t be d efective. If you su sp ect th at th e cable is th e p roblem , th e easiest th in g to d o is to rep lace th e keyboard cable with a kn own good on e. If th e system still d oes n ot work n orm ally, you m ay h ave to rep lace eith er th e en tire keyboard or th e m oth erboard . In m an y n ewer system s, th e m oth erboard ’s keyboard an d m ou se con n ectors are p rotected by a fu se th at can be rep laced . Look for an y typ e of fu se on th e m oth erboard in th e vicin ity of th e keyboard or m ou se con n ectors. Oth er system s m ay h ave a socketed keyboard con troller ch ip (8042-typ e). In th at case, it m ay be p ossible to rep air th e m oth erboard keyboard circu it by rep lacin g th is ch ip . Becau se th ese ch ip s h ave ROM cod e in th em , it is best to get th e rep lacem en t from th e m oth erboard or BIOS m an u factu rer. Followin g is a list of stan d ard POST an d d iagn ostics keyboard error cod es: Error Code

Descript ion

3xx

Keyboard errors

301

Keyboard reset or stuck-key failure (XX 301, XX = scan code in hex)

302

System unit keylock switch is locked

302

User-indicated keyboard test error

303

Keyboard or system-board error; keyboard controller failure

304

Keyboard or system-board error; keyboard clock high

305

Keyboard +5v error; PS/ 2 keyboard fuse (on motherboard) blown

341

Keyboard error

342

Keyboard cable error

343

Keyboard LED card or cable failure

365

Keyboard LED card or cable failure

366

Keyboard interface cable failure

367

Keyboard LED card or cable failure

Disassem bly Procedures and Caut ions. Rep airin g an d clean in g a keyboard often req u ires you to take it ap art. W h en p erform in g th is task, you m u st kn ow wh en to stop ! Som e keyboard s com e ap art in to literally h u n d red s of little p ieces th at are alm ost im p ossible to reassem ble. An IBM keyboard gen erally h as th ese fou r m ajor p arts: ■ Cable ■ Case ■ Keyp ad assem bly ■ Keycap s

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You easily can break d own a keyboard in to th ese m ajor com p on en ts an d rep lace an y of th em , bu t d on ’t d isassem ble th e keyp ad assem bly, or you will be sh owered with h u n d red s of tin y sp rin gs, clip s, an d keycap s. Fin d in g all th ese p arts—several h u n d red of th em —an d p iecin g th e u n it back togeth er is n ot a fu n way to sp en d you r tim e. You also m ay n ot be able to reassem ble th e keyboard p rop erly. Figu re 7.15 sh ows a typ ical keyboard with th e case op en ed . External cable

Base

LED card Internal cable

Keyboard assembly

Top cover Foot

FIG. 7.15 Typ ical keyboard com p on en ts. An oth er p roblem is th at you can n ot p u rch ase th e sm aller p arts sep arately, su ch as con tact clip s an d sp rin gs. Th e on ly way to obtain th ese p arts is from an oth er keyboard . If you ever h ave a keyboard th at is beyon d rep air, keep it arou n d for th ese p arts. Th ey m igh t com e in h an d y som ed ay. Most rep air op eration s are lim ited to ch an gin g th e cable or clean in g som e com p on en t of th e keyboard , from th e cable con tact en d s to th e key con tact p oin ts. Th e keyboard cable takes q u ite a lot of abu se an d , th erefore, can fail easily. Th e en d s are stretch ed , tu gged , p u lled , an d gen erally h an d led rou gh ly. Th e cable u ses strain reliefs, bu t you still m igh t h ave p roblem s with th e con n ectors m akin g p rop er con tact at each en d or even with wires th at h ave broken in sid e th e cable. You m igh t wan t to carry a sp are cable for every typ e of keyboard you h ave. All keyboard cables p lu g in to th e keyboard an d PC with con n ectors, an d you can ch an ge th e cables easily with ou t h avin g to sp lice wires or sold er con n ection s. W ith th e earlier 83-key PC an d 84-key AT keyboard s, you m u st op en th e case to access th e con n ector to wh ich th e cable attach es. On th e n ewer 101-key En h an ced keyboard s from IBM, Lexm ark, an d Un icom p , th e cable p lu gs in to th e keyboard from th e ou tsid e of th e case,

Keyboards

u sin g a m od u lar jack an d p lu g sim ilar to a telep h on e jack. Th is d esign also m akes th e IBM/ Lexm ark/ Un icom p keyboard s u n iversally u sable on n early an y system (excep t th e origin al PC) by sim p ly switch in g th e cable. Th e on ly d ifferen ce, for exam p le, between th e En h an ced keyboard s for an IBM AT an d an IBM PS/ 2 system is th e attach ed cable. PS/ 2 system s u se a tan cable with a sm aller p lu g on th e com p u ter sid e. Th e AT cable is black an d h as th e larger DIN-typ e p lu g on th e com p u ter sid e. You can in terch an ge th e En h an ced keyboard s as lon g as you u se th e correct cable for th e system . Th e on ly feasible way to rep air a keyboard is to rep lace th e cable an d to clean th e in d ivid u al keyswitch assem blies, th e en tire keyp ad , or th e cable con tact en d s. Oth er th an clean in g a keyboard , th e on ly th in g th at you can d o is rep lace th e en tire keyp ad assem bly (virtu ally th e en tire keyboard ) or th e cable. Cleaning a Keyboard. On e of th e best ways to keep a keyboard in top con d ition is p eriod ic clean in g. As p reven tive m ain ten an ce, you sh ou ld vacu u m th e keyboard weekly, or at least m on th ly. You can also u se can n ed com p ressed air to blow th e d u st an d d irt ou t in stead of u sin g a vacu u m . Before you d u st a keyboard with th e com p ressed air, tu rn th e keyboard u p sid e d own so th at th e p articles of d irt an d d u st collected in sid e can fall ou t. On all keyboard s, each keycap is rem ovable, wh ich can be h an d y if a key sticks or acts erratically. For exam p le, a com m on p roblem is a key th at d oes n ot work every tim e you p ress it. Th is p roblem u su ally resu lts from d irt collectin g u n d er th e key. An excellen t tool for rem ovin g keycap s on alm ost an y keyboard is th e U-sh ap ed ch ip -p u ller in clu d ed in m an y com p u ter tool kits. Sim p ly slip th e h ooked en d s of th e tool u n d er th e keycap , sq u eeze th e en d s togeth er to grip th e u n d ersid e of th e keycap , an d lift u p . IBM sells a tool d esign ed sp ecifically for rem ovin g keycap s from its keyboard s, bu t th e ch ip p u ller works even better. After rem ovin g th e cap , sp ray som e com p ressed air in to th e sp ace u n d er th e cap to d islod ge th e d irt. Th en rep lace th e cap an d ch eck th e action of th e key.

Caut ion When you remove the keycaps, be careful not to remove the Spacebar on the original 83-key PC and the 84-key AT-type keyboards. This bar is very difficult to reinstall. The newer 101-key units use a different wire support that can be removed and replaced much more easily.

Sp ills also can be a p roblem . If you tip a soft d rin k or cu p of coffee in to a keyboard , you d o n ot n ecessarily h ave a d isaster. You sh ou ld im m ed iately (or as soon as p ossible) flu sh ou t th e keyboard with d istilled water. Partially d isassem ble th e keyboard an d u se th e water to wash th e com p on en ts. (See th e followin g section for d isassem bly in stru ction s.) If th e sp illed liq u id h as d ried , soak th e keyboard in som e of th e water for a wh ile. W h en you are su re th at th e keyboard is clean , p ou r an oth er gallon or so of d istilled water over it an d th rou gh th e keyswitch es to wash away an y resid u al d irt. After th e u n it d ries com p letely, it sh ou ld be p erfectly fu n ction al. You m ay be su rp rised to kn ow th at d ren ch in g you r keyboard with water will n ot h arm th e com p on en ts. Ju st m ake su re th at you u se d istilled water, wh ich is free from resid u e or m in eral con ten t. Also m ake su re th at th e

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keyboard is fu lly d ry before you attem p t to u se it, or som e of th e com p on en ts m igh t sh ort ou t. Replacem ent Keyboards. In m ost cases, it is ch eap er or m ore cost effective to rep lace a keyboard rath er th an rep air it. Th is is esp ecially tru e if th e keyboard h as an in tern al m alfu n ction or if on e of th e keyswitch es is d efective. Rep lacem en t p arts for keyboard s are alm ost im p ossible to p rocu re, an d in m ost cases th e in stallation of an y rep air p art is d ifficu lt. In ad d ition , m an y of th e keyboard s su p p lied with lower-cost PCs leave m u ch to be d esired . Th ey often h ave a m u sh y feel, with little or n o tactile feed back. A p oor keyboard can m ake u sin g a system a fru stratin g exp erien ce, esp ecially if you are a tou ch typ ist. For all th ese reason s, it is often a good id ea to rep lace an existin g keyboard with som eth in g better. Perh ap s th e h igh est-q u ality keyboard s in th e en tire com p u ter in d u stry are th ose m ad e by IBM, or, m ore accu rately, Un icom p . Several years ago, IBM sp u n off its keyboard an d p rin ter d ivision s as a sep arate com p an y called Lexm ark. Lexm ark u sed to m an u factu rer m ost IBM-bran d keyboard s an d p rin ters an d sold th em n ot on ly to IBM, bu t also to oth er PC ven d ors an d en d u sers. In 1996, Lexm ark sold its keyboard tech n ology to a com p an y called Un icom p , wh ich n ow m ain tain s an exten sive selection of over 1,400 keyboard s. Table 7.9 sh ows th e p art n u m bers of all IBM-labeled keyboard s an d cables. Th ese n u m bers can serve as a referen ce wh en you are seekin g a rep lacem en t IBM keyboard from IBM d irectly or from th ird -p arty com p an ies. Man y th ird -p arty com p an ies sell IBM label keyboard s for m u ch less th an IBM, in both n ew an d refu rbish ed form . Rem em ber th at you can also p u rch ase th ese sam e keyboard s th rou gh Un icom p , alth ou gh th ey d o n ot com e with an IBM label. Table 7.9

IBM Keyboard and Cable Part Num bers

Descript ion

Part Num ber

83-key U.S. PC keyboard assembly with cable

8529297

Cable assembly for 83-key PC keyboard

8529168

84-key U.S. AT keyboard assembly with cable

8286165

Cable assembly for 84-key keyboard

8286146

101-key U.S. keyboard without LED panel

1390290

101-key U.S. keyboard with LED panel

6447033

101-key U.S. keyboard with LED panel (PS/ 2 logo)

1392090

6-foot cable for Enhanced keyboard (DIN plug)

6447051

6-foot cable for Enhanced keyboard (mini-DIN plug)

61X8898

6-foot cable for Enhanced keyboard (shielded mini-DIN plug)

27F4984

10-foot cable for Enhanced keyboard (mini-DIN plug)

72X8537

Notice th at th e origin al 83/ 84-key IBM keyboard s are sold with a cable th at h as th e larger, five-p in DIN con n ector alread y attach ed . IBM En h an ced keyboard s are always sold (at least by IBM) with ou t a cable. You m u st ord er th e p rop er cable as a sep arate item . Cables are available to con n ect th e keyboard s to eith er th e old er system u n its th at u se th e larger DIN con n ector or to PS/ 2 system s (an d m an y com p atibles) th at u se th e sm aller m in i-DIN con n ector.

Keyboards

Recen tly, IBM h as started sellin g com p lete keyboard assem blies u n d er a p rogram called IBM Options. Th is p rogram is d esign ed to sell th ese com p on en ts in th e retail ch an n el to en d u sers of both IBM an d com p atible system s from oth er ven d ors. Item s u n d er th e IBM Op tion s p rogram are sold th rou gh n orm al retail ch an n els, su ch as Com p USA an d Com p u ter Discou n t W areh ou se (CDW ). Th ese item s are also p riced m u ch ch eap er th an item s p u rch ased as sp are p arts. Th ey in clu d e a fu ll warran ty an d are sold as com p lete p ackages, in clu d in g cables. Table 7.10 lists som e of th e IBM Op tion s keyboard s an d p art n u m bers. Table 7.10

IBM Opt ions Keyboards ( Sold Ret ail)

Descript ion

Part Num ber

IBM Enhanced keyboard (cable w/ DIN plug)

92G7454

IBM Enhanced keyboard (cable w/ mini-DIN plug)

92G7453

IBM Enhanced keyboard, built-in Trackball (cable w/ DIN plug)

92G7456

IBM Enhanced keyboard, built-in Trackball (cable w/ mini-DIN plug)

92G7455

IBM Enhanced keyboard, integrated TrackPoint II (cables w/ mini-DIN plugs)

92G7461

Th e extrem ely p ositive tactile feed back of th e IBM/ Lexm ark/ Un icom p d esign is also a ben ch m ark of com p arison for th e rest of th e in d u stry. Alth ou gh keyboard feel is an issu e of p erson al p referen ce, I h ave n ever u sed a keyboard th at feels better th an th e IBM/ Lexm ark/ Un icom p d esign s. I n ow eq u ip every system I u se with a Un icom p keyboard , in clu d in g th e m an y n on -IBM system s I u se. You can p u rch ase th ese keyboard s d irectly from Un icom p at very reason able p rices. Also, you can som etim es fin d IBM-labeled m od els sellin g for u n d er $100 available from ad vertisers in com p u ter m agazin es. ◊◊ An online catalog of Unicomp keyboard products is available on the World Wide Web at ht t p:/ / w w w .pckeyboard.com .

Un icom p sells oth er keyboard s for very reason able p rices as well. Man y d ifferen t m od els are available, in clu d in g som e with a bu ilt-in trackball or even th e revolu tion ary TrackPoin t p oin tin g d evice. (TrackPoin t refers to a sm all stick m ou n ted between th e G, H, an d B keys.) Th is d evice was first featu red on th e IBM Th in kPad lap top system s, alth ou gh th e keyboard s are n ow sold for u se on oth er m an u factu rers’ PCs. Th e tech n ology is bein g licen sed to m an y oth er m an u factu rers, in clu d in g Tosh iba. Oth er m an u factu rers of h igh -q u ality keyboard s th at are sim ilar in feel to th e IBM/ Lexm ark/ Un icom p u n its are Alp s, Lite-On , an d NMB Tech n ologies. Th ese keyboard s h ave excellen t tactile feed back, with a p ositive click sou n d . Th ey are m y secon d ch oice, after a Un icom p u n it. MaxiSwitch also m akes a h igh -q u ality afterm arket keyboard , wh ich is u sed by a n u m ber of PC m an u factu rers, in clu d in g Gateway 2000. Th ese also h ave a good feel an d are recom m en d ed . Man y of th ese com p an ies can m ake th eir keyboard s with you r own com p an y logo on th em (su ch as th e Maxi-Switch m od els u sed by Gateway 2000), wh ich is id eal for clon e m an u factu rers lookin g for n am e-bran d recogn ition . Reference M at erial If you are in terested in m ore d etails abou t keyboard d esign or in terfacin g, a com p an y called An n asoft System s p u blish es a book/ d isk p ackage called PC Keyboard Design. Th is d ocu m en t d efin es th e p rotocol between th e keyboard an d com p u ter for both XT an d AT

479

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typ es an d in clu d es sch em atics an d keyboard con troller sou rce cod e. Th e kit, wh ich in clu d es a licen se to u se th e sou rce cod e, costs $249. Oth er excellen t sou rces of in form ation are th e variou s tech n ical referen ce m an u als p u t ou t by IBM. Ap p en d ix A, “Ven d or List,” con tain s a list of im p ortan t IBM referen ce m an u als, in wh ich you can fin d m u ch valu able in form ation . Th is in form ation can be esp ecially valu able to own ers of n on -IBM system s becau se oth er m an u factu rers often d o n ot p u t ou t th e sam e level of tech n ical in form ation as IBM, an d m an y PC d esign s are sim ilar or even id en tical to on e or m ore IBM system s. After all, th at is wh y th ese d esign s were referred to as IBM-com p atibles for so lon g. Mu ch of m y p erson al kn owled ge an d exp ertise com es from p orin g over th e variou s IBM tech n ical referen ce m an u als.

M ice Th e m ou se was in ven ted in 1964 by Dou glas En glebart, wh o at th e tim e was workin g at th e Stanford Research Institute (SRI), a th in k tan k sp on sored by Stan ford Un iversity. Th e m ou se was officially called an X -Y Position Indicator for a Display System . Xerox later ap p lied th e m ou se to its revolu tion ary Alto com p u ter system in 1973. At th e tim e, u n fortu n ately, th ese system s were exp erim en tal an d u sed p u rely for research . In 1979, several p eop le from Ap p le, in clu d in g Steve Jobs, were in vited to see th e Alto an d th e software th at ran th e system . Steve Jobs was blown away by wh at h e saw as th e fu tu re of com p u tin g, wh ich in clu d ed th e u se of th e m ou se as a p oin tin g d evice an d th e GUI it op erated . Ap p le p rom p tly in corp orated th ese featu res in to wh at was to becom e th e Lisa com p u ter an d lu red away 15 to 20 Xerox scien tists to work on th e Ap p le system . Alth ou gh Xerox released th e Star 8010 com p u ter th at u sed th is tech n ology in 1981, it was exp en sive, p oorly m arketed , an d p erh ap s way ah ead of its tim e. Ap p le released th e Lisa com p u ter, its first system th at u sed th e m ou se, in 1983. It also was n ot a ru n away su ccess, largely becau se of its $10,000 list p rice, bu t by th en Jobs alread y h ad Ap p le workin g on th e low-cost su ccessor to th e Lisa, th e Macin tosh . Th e Ap p le Macin tosh was in trod u ced in 1984. Alth ou gh it was n ot an im m ed iate h it, th e Macin tosh h as grown in p op u larity sin ce th at tim e. Man y cred it th e Macin tosh with in ven tin g th e m ou se an d GUI, bu t as you can see, th is tech n ology was actu ally borrowed from oth ers, in clu d in g SRI an d Xerox. Certain ly th e Macin tosh , an d n ow Microsoft W in d ows an d OS/ 2, h ave gon e on to p op u larize th is in terface an d brin g it to th e legion of In tel-based PC system s. Alth ou gh th e m ou se d id n ot catch on q u ickly in th e PC m arketp lace, tod ay th e GUIs for PC system s su ch as W in d ows an d OS/ 2 virtu ally d em an d th e u se of a m ou se. Th erefore, it is com m on for a m ou se to be sold with n early every n ew system on th e m arket. Mice com e in m an y sh ap es an d sizes from m an y d ifferen t m an u factu rers. Som e h ave taken th e stan d ard m ou se d esign an d tu rn ed it u p sid e d own , creatin g th e trackball. In th e trackball d evices, you m ove th e ball with you r h an d d irectly rath er th an th e u n it itself. IBM even p rod u ced a very cool m ou se/ trackball con vertible d evice called th e TrackPoin t (p / n 1397040). Th e TrackPoin t cou ld be u sed as eith er a m ou se (ball sid e d own ), or as a trackball (ball sid e u p ). In m ost cases, th e d ed icated trackballs h ave a m u ch larger ball

M ice

th an wou ld be fou n d on a stan d ard m ou se. Oth er th an th e orien tation an d p erh ap s th e size of th e ball, a trackball is id en tical to a m ou se in d esign , basic fu n ction , an d electrical in terface. Th e largest m an u factu rers of m ice are Microsoft an d Logitech . Even th ou gh m ice m ay com e in d ifferen t varieties, th eir actu al u se an d care d iffer very little. Th e stan d ard m ou se con sists of several com p on en ts: ■ A h ou sin g th at you h old in you r h an d an d m ove arou n d on you r d esktop ■ A roller ball th at sign als m ovem en t to th e system ■ Bu tton s (u su ally two) for m akin g selection s ■ A cable for con n ectin g th e m ou se to th e system ■ An in terface con n ector to attach th e m ou se to th e system Th e h ou sin g, wh ich is m ad e of p lastic, con sists of very few m ovin g p arts. On top of th e h ou sin g, wh ere you r fin gers n orm ally resid e, are bu tton s. Th ere m ay be an y n u m ber of bu tton s, bu t in th e PC world , th ere are typ ically on ly two. If ad d ition al bu tton s are on you r m ou se, sp ecialized software is req u ired for th em to op erate. On th e bottom of th e h ou sin g is a sm all ru bber ball th at rolls as you m ove th e m ou se across th e tabletop . Th e m ovem en ts of th is ru bber ball are tran slated in to electrical sign als tran sm itted to th e com p u ter across th e cable. Som e m ice u se a sp ecial op tical sen sor th at d etects m ovem en t over a grid . Th ese op tical m ice h ave fallen in to d isfavor becau se th ey work on ly if you u se a sp ecial grid p ad u n d ern eath th em . Th e cable can be an y len gth , bu t it is typ ically between fou r an d six feet lon g.

Tip If you have a choice on the length of cable to purchase, go for a longer one. This allows easier placement of the mouse in relation to your computer.

After th e m ou se is con n ected to you r com p u ter, it com m u n icates with you r system th rou gh th e u se of a device driver, wh ich can be eith er load ed exp licitly or bu ilt in to th e op eratin g system software. For exam p le, n o sep arate d rivers are n eed ed to u se a m ou se with W in d ows or OS/ 2, bu t u sin g th e m ou se with m ost DOS-based p rogram s req u ires a sep arate d river to be load ed from th e CONFIG.SYS or AUTOEXEC.BAT file. Regard less of wh eth er it is bu ilt in or n ot, th e d river tran slates th e electrical sign als sen t from th e m ou se in to p osition al in form ation an d in d icates th e statu s of th e bu tton s. In tern ally, a m ou se is very sim p le as well. Th e ball u su ally rests again st two rollers, on e for tran slatin g th e X-axis m ovem en t an d th e oth er for tran slatin g th e Y-axis m ovem en t. Th ese rollers are u su ally con n ected to sm all d isks with sh u tters th at altern ately block an d allow th e p assage of ligh t. Sm all op tical sen sors d etect m ovem en t of th e wh eels by watch in g an in tern al in frared ligh t blin k on an d off as th e sh u tter wh eel rotates an d “ch op s” th e ligh t. Th ese blin ks are tran slated in to m ovem en t alon g th e axes. Th is typ e of setu p , called an opto-m echanical m echanism , is by far th e m ost p op u lar in u se tod ay (see Figu re 7.16).

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Rubber ball

"Chopper" wheel for X-axis

"Chopper" wheel for Y-axis

X output

Light detector

Y output

Light source

Roller for X-axis

Roller for Y-axis

Light source

Light detector

FIG. 7.16 Typ ical op to-m ech an ical m ou se m ech an ism . M ouse Int erface Types Th e con n ector u sed to attach you r m ou se to th e system d ep en d s on th e typ e of in terface you are u sin g. Th ree basic in terfaces are u sed for m ou se con n ection s, with a fou rth com bin ation d evice p ossible as well. Mice are m ost com m on ly con n ected to you r com p u ter th rou gh th e followin g th ree in terfaces: ■ Serial in terface ■ Ded icated m oth erboard m ou se p ort ■ Bu s-card in terface Serial. A p op u lar m eth od of con n ectin g a m ou se to old er PCs is th rou gh th e stan d ard serial in terface. As with oth er serial d evices, th e con n ector on th e en d of th e m ou se cable is eith er a 9-p in or 25-p in m ale con n ector. On ly a cou p le of p in s in th e DB-9 or DB-25 con n ectors are u sed for com m u n ication s between th e m ou se an d th e d evice d river, bu t th e m ou se con n ector typ ically h as all n in e or 25 p in s p resen t. Becau se m ost PCs com e with two serial p orts, a serial m ou se can be p lu gged in to eith er COM1: or COM2:. Th e d evice d river, wh en in itializin g, search es th e p orts to d eterm in e wh ich on e th e m ou se is con n ected to. Becau se a serial m ou se d oes n ot con n ect to th e system d irectly, it d oes n ot u se system resou rces by itself. In stead , th e resou rces u sed are th ose u sed by th e serial p ort to wh ich it is con n ected . For exam p le, if you h ave a m ou se con n ected to COM2, it m ost likely u ses IRQ3 an d I/ O p ort ad d resses 2F8h -2FFh . ◊◊ See “ Serial Ports,” p. 583

M ice

M ot herboard M ouse Port ( PS/ 2) . Most n ewer com p u ters n ow com e with a d ed icated m ou se p ort bu ilt in to th e m oth erboard . Th is p ractice was in trod u ced by IBM with th e PS/ 2 system s in 1987, so th is in terface is often referred to as a PS/2 m ouse interface. Th is term d oes n ot im p ly th at su ch a m ou se can work on ly with a PS/ 2; in stead , it m ean s th at th e m ou se can con n ect to an y system th at h as a d ed icated m ou se p ort on th e m oth erboard . From a h ard ware p ersp ective, a m oth erboard m ou se con n ector u su ally is exactly th e sam e as th e m in i-DIN con n ector u sed for n ewer keyboard s. In fact, th e m oth erboard m ou se p ort is con n ected to th e 8042-typ e keyboard con troller fou n d on th e m oth erboard . All th e PS/ 2 com p u ters in clu d e m in i-DIN keyboard an d m ou se p ort con n ectors on th e back. Most com p atible slim lin e com p u ters also h ave th ese sam e con n ectors for sp ace reason s. Oth er m oth erboard s h ave a p in -h ead er typ e con n ector for th e m ou se p ort becau se m ost stan d ard cases d o n ot h ave a p rovision for th e m in i-DIN m ou se con n ector. If th at is th e case, an ad ap ter cable is u su ally su p p lied with th e system . Th is cable ad ap ts th e p in -h ead er con n ector on th e m oth erboard to th e stan d ard m in i-DIN typ e con n ector u sed for th e m oth erboard m ou se.

Caut ion As mentioned in the “ Keyboard/ M ouse Interface Connectors” section earlier in this chapter, the mini-DIN sockets used for both keyboard and mouse connections on many systems are physically and electrically interchangeable, but the data packets they carry are not. Be sure to plug each device into the correct socket or neither will function correctly.

Con n ectin g a m ou se to th e bu ilt-in m ou se p ort is th e best m eth od of con n ection becau se you d o n ot sacrifice an y of th e system ’s in terface slots or an y serial p orts, an d th e p erform an ce is n ot lim ited by th e serial p ort circu itry. Th e stan d ard resou rce u sage for a m oth erboard (or PS/ 2) m ou se p ort is IRQ 12, as well as I/ O p ort ad d resses 60h an d 64h . Becau se th e m oth erboard m ou se p ort u ses th e 8042-typ e keyboard con troller ch ip , th e p ort ad d resses are th ose of th is ch ip . IRQ 12 is an in terru p t th at is u su ally free on m ost system s an d it, of cou rse, m u st rem ain free on an y ISA bu s system s th at h ave a m oth erboard m ou se p ort becau se in terru p t sh arin g is n ot allowed with th e ISA bu s. Serial and M ot herboard M ouse Port ( PS/ 2) . A h ybrid typ e of m ou se can p lu g in to a serial p ort or a m oth erboard m ou se p ort con n ection . Th is com bin ation serial-PS/ 2 m ou se is m ore flexible th an th e sin gle d esign typ es. Circu itry in th is m ou se au tom atically d etects th e typ e of p ort to wh ich it is con n ected an d con figu res th e m ou se au tom atically. Th ese m ice u su ally com e with a m in i-DIN con n ector on th e en d of th eir cable an d an ad ap ter th at con verts th e m in i-DIN to a 9- or 25-p in serial p ort con n ector. Som etim es p eop le u se ad ap ters to try to con n ect a serial m ou se to a m oth erboard m ou se p ort or a m oth erboard m ou se to a serial p ort. Th at th is d oes n ot work is n ot th e fau lt of th e ad ap ter. If th e m ou se d oes n ot exp licitly state th at it is both a serial an d a PS/ 2-typ e m ou se, it d oes n ot work on eith er in terface, bu t in stead works on ly on th e sin gle in terface for wh ich it was d esign ed . Most of th e tim e, you fin d th e d esign ation for wh at typ e of m ou se you h ave p rin ted on its u n d ersid e.

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Bus. A bus m ou se is typ ically u sed in system s th at d o n ot h ave a m oth erboard m ou se p ort or an y available serial p orts. Th e n am e bus m ouse is d erived from th e fact th at th e m ou se req u ires a sp ecial bu s in terface board , wh ich occu p ies a slot in you r com p u ter an d com m u n icates with th e d evice d river across th e m ain m oth erboard bu s. Alth ou gh th e u se of a bu s m ou se is tran sp aren t to th e u ser (th ere is n o op eration al d ifferen ce between a bu s m ou se an d oth er typ es of m ice), m an y p eop le view a bu s m ou se as less d esirable th an oth er typ es becau se it occu p ies a slot th at cou ld be u sed for oth er p erip h erals. An oth er d rawback to th e bu s m ou se is th at it is electrically in com p atible with th e oth er typ es of m ice. Becau se th ey are n ot very p op u lar, bu s m ice can be h ard to fin d in a p in ch . Likewise, th e bu s ad ap ters are typ ically available on ly for ISA slots; becau se th ey are always 8-bit card s, you are lim ited in th e ch oice of n on con flictin g h ard ware in terru p ts. A bu s m ou se can also be d an gerou s becau se it u ses a m in i-DIN con n ector—ju st like th e m oth erboard (PS/ 2)-typ e m ou se—alth ou gh th ey are totally in com p atible. I h ave even h eard of p eop le d am agin g m oth erboard s by p lu ggin g a bu s m ou se in to a m oth erboard m ou se con n ector. Bu s m ou se ad ap ter card s u su ally h ave a selectable in terru p t an d I/ O p ort ad d ress settin g, bu t th e IRQ selection is lim ited to 8-bit in terru p ts. Th is u su ally m ean s th at you m u st ch oose IRQ 5 in m ost system s th at alread y h ave two serial p orts becau se all th e oth er 8-bit in terru p ts are in u se. If you are alread y u sin g an oth er 8-bit-on ly card th at n eed s an in terru p t, like som e sou n d card s, you will n ot be able to ru n both d evices in th e sam e system with ou t con flicts. All in all, I th in k bu s m ice sh ou ld be avoid ed .

Not e M icrosoft sometimes calls a bus mouse an inport mouse, which is its proprietary name for a bus mouse connection.

USB. Th e n ewest in terface for PC keyboard s, an d virtu ally every oth er typ e of p erip h eral you can n am e, is th e Un iversal Serial Bu s (USB). USB keyboard s con n ect to a PC th rou gh th e u n iversal fou r-wire con n ector u sed by all USB d evices. Becau se you can p lu g u p to 127 d evices in to a sin gle USB p ort on you r PC, th ese keyboard s freq u en tly in clu d e ad d ition al USB sockets bu ilt in to th e h ou sin g, en ablin g th em to fu n ction as h u bs for oth er USB d evices. Altern atively, th e USB p lu g th at con n ects to you r PC m ay h ave a “p ass-th rou gh ” con n ector. Th is is a stan d ard USB p lu g with an in tegrated USB socket, so you can con n ect an oth er d evice u sin g th e sam e p ort on th e com p u ter. Som e USB keyboard s also in clu d e a stan d ard PS/ 2 m ou se p ort, so you can con n ect you r existin g m ou se d irectly to th e keyboard in stead of to th e com p u ter. M ouse Calibrat ion Most m ou se d rivers in clu d e p aram eters th at you can ad ju st to m od ify th e p erform an ce of th e d evice to you r sp ecification s. Th ese ad ju stm en ts d o n ot alter th e p h ysical p erform an ce of th e m ou se; in stead , th ey con trol th e way th at th e op eratin g system in terp rets th e sign als th at it receives from th e h ard ware. Th e W in d ows op eratin g system s in clu d e a Mou se Con trol Pan el th at p rovid es th e in terface for th ese con trol p aram eters.

M ice

On a PC ru n n in g W in d ows 9x with th e op eratin g system ’s stan d ard PS/ 2 p ort m ou se d river in stalled , th e Mou se Con trol Pan el ap p ears as sh own in Figu re 7.17. The But t ons Page. On th e Mou se Con trol Pan el’s Bu tton s p age, you can select wh eth er you r m ou se sh ou ld op erate in Righ t-h an d ed or Left-h an d ed m od e. On th e stan d ard , twobu tton m ou se u sed with W in d ows, th e left m ou se bu tton is trad ition ally th e p rim ary bu tton . It is u sed for selectin g an d d raggin g, wh ile th e righ t bu tton is th e secon d ary bu tton , wh ich p rovid es access to con text m en u s an d oth er sp ecial featu res. In m an y con texts, th e term s p rim ary an d secon d ary are p referable to left an d righ t becau se th e d river can switch th e fu n ction s of th e two bu tton s to accom m od ate left-h an d ed u sers.

FIG. 7.17 Th e W in d ows 9x Mou se Con trol Pan el en ables you to ad ju st m ou se p erform an ce attribu tes to you r sp ecification s.

Mou se d esign is a sore p oin t am on g m an y left-h an d ed u sers becau se a great d eal of d ocu m en tation an d even som e m ou se h ard ware favor th e righ t-h an d ed . Man u als often refer to th e left or righ t m ou se bu tton in stead of th e p rim ary or secon d ary, wh ich can be con fu sin g to th e u n in form ed . W orse, th e so-called Microsoft Ergon om ic Mou se in clu d ed with a great m an y of th e n ew system s sold tod ay h as a cu rved d esign th at favors righ th an d ed u sers. I h ave seen m an y u sers becom e accu stom ed to u sin g th is m ou se with th e left h an d , bu t in m y exp erien ce, an eq u al n u m ber of left-h an d ed p eop le get in to th e h abit of op eratin g th e m ou se righ t-h an d ed . Also on th e Bu tton s p age is a slid er th at en ables you to ad ju st th e m ou se’s d ou ble-click sp eed . Th is ad ju stm en t con trols th e tim e in terval between two clicks of th e p rim ary m ou se bu tton en ablin g you to d istin gu ish two sin gle clicks from on e d ou ble click. W h en u sin g ap p lication s su ch as W in d ows Exp lorer, th is d istin ction can be im p ortan t, for it sign als th e d ifferen ce between lau n ch in g a file an d ren am in g it. Man y u sers are fru strated by th e m in u scu le click tim in g d ifferen ces th at d istin gu ish on e m ou se fu n ction from an oth er an d are u n aware th at th ey can easily m od ify th e beh avior of th e m ou se to p rovid e th em with a greater m argin of error. Th e test area of th e d ialog

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box con tain s an an im ation of a jack-in -th e-box th at lets you test you r ad ju stm en ts before com m ittin g th em to th e system con figu ration . The Point ers Page. On th e Poin ters p age, you can select th e cu rsors th at W in d ows 9x d isp lays d u rin g sp ecific system even ts. Th e op eratin g system in clu d es a large selection of am u sin g cu rsors, som e of wh ich are an im ated . However, th is cap ability to select cu rsors also h as a fu n ction al u se. W in d ows 9x also in clu d es cu rsors th at are d esign ed u sin g sizes an d colors in ten d ed to accom m od ate certain screen typ es (su ch as old er, less visible p ortable system d isp lays), lon g-d istan ce viewin g (su ch as at p resen tation s), an d u sers with visu al d isabilities. The M ot ion Page. On th e Motion p age (see Figu re 7.18), you can con trol h ow th e d istan ce th at you m ove th e m ou se relates to th e d istan ce th e p oin ter m oves on th e com p u ter screen . If, for exam p le, you r work su rface p rovid es on ly a sm all area in wh ich to m ove th e m ou se, you can m ove th e Poin ter Sp eed slid er to th e righ t to in crease th e sp eed . Th is can p reven t you from h avin g to lift th e m ou se off of th e work su rface to m ove th e p oin ter across th e wh ole screen . Som e m ou se typ es, su ch as th e TrackPoin t in clu d ed on m an y p ortable system s, are d esign ed to react to very su btle tou ch es, an d you can easily fin e-tu n e th eir m ovem en ts by u sin g th is con trol.

FIG. 7.18 On th e Motion p age, you can con trol th e relation sh ip between th e m ovem en t of th e m ou se an d th at of th e p oin ter.

Th e Poin ter Trail con trol en ables you to con figu re you r m ou se to leave a series of p oin ter im ages beh in d it as it m oves across th e screen , form in g a trail of ad ju stable len gth . Again , th is featu re h as a p ractical u se in situ ation s in wh ich p oin ter visibility is a p roblem . However, som e u sers sim p ly en joy th e effect, wh ile oth ers are p rofou n d ly irritated by it. The General Page. On th e Gen eral p age, you select th e m ou se d river u sed by you r system . In m ost cases, W in d ows 9x au tom atically d etects an d id en tifies th e m ou se d u rin g th e op eratin g system in stallation an d su p p lies th e correct d river. However, in cases in wh ich you are in stallin g a n ew or u n u su al p oin tin g d evice, you can u se th is p age to in stall a n ew or u p d ated m ou se d river.

M ice

M ouse Troubleshoot ing If you are exp erien cin g p roblem s with you r m ou se, you n eed to look in on ly two gen eral p laces—h ard ware or software. Becau se m ice are basically sim p le d evices, lookin g at th e h ard ware takes very little tim e. Detectin g an d correctin g software p roblem s can take a bit lon ger, h owever. Hardw are Problem s. Two typ es of h ard ware p roblem s can crop u p wh en you are u sin g a m ou se. Th e m ost com m on is a d irty m ou se, wh ich is fixed by d oin g som e “m ou se clean in g.” Th e oth er p roblem , wh ich relates to in terru p t con flicts, is m ore d ifficu lt to solve. Cl e a n i n g Yo u r Mo u se . If you n otice th at th e m ou se p oin ter m oves across th e screen in a jerky fash ion , it m ay be tim e to clean you r m ou se. Th is jerkin ess is cau sed wh en d irt an d d u st get trap p ed arou n d th e m ou se’s ball-an d -roller assem bly, th ereby restrictin g its free m ovem en t. From a h ard ware p ersp ective, th e m ou se is a sim p le d evice, an d clean in g it is also very sim p le. Th e first step is to tu rn th e m ou se h ou sin g over so th at you can see th e ball on th e bottom . Notice th at su rrou n d in g th e ball is an access p an el th at you can op en . Som e in stru ction s m ay even in d icate h ow th e p an el is to be op en ed . (Som e off-bran d m ice m ay req u ire you to rem ove som e screws to get at th e roller ball.) Rem ove th e p an el to see m ore of th e roller ball an d th e socket in wh ich it rests. If you tu rn th e m ou se back over, th e ru bber roller ball sh ou ld fall in to you r h an d . Take a look at th e ball. It m ay be gray or black, bu t it sh ou ld h ave n o visible d irt or oth er con tam in ation . If it d oes, wash it in soap y water or a m ild solven t, su ch as con tact len s clean er solu tion or alcoh ol, an d d ry it off. Now take a look at th e socket in wh ich th e roller ball n orm ally rests. You will see two or th ree sm all wh eels or bars again st wh ich th e ball n orm ally rolls. If you see d u st or d irt on or arou n d th ese wh eels or bars, you n eed to clean th em . Th e best way is to u se a com p ressed air d u ster, wh ich can blow ou t an y d u st or d irt. You also can u se som e electrical con tact clean er to clean th e rollers. Rem em ber, an y rem ain in g d irt or d u st im p ed es th e m ovem en t of th e roller ball an d resu lts in th e m ou se n ot workin g as it sh ou ld . Pu t th e m ou se back togeth er by in sertin g th e roller ball in to th e socket an d th en secu rely attach in g th e cover p an el. Th e m ou se sh ou ld look ju st like it d id before you rem oved th e p an el, excep t th at it will be n oticeably clean er. In t e rru p t Co n f l i c t s. Interrupts are in tern al sign als u sed by you r com p u ter to in d icate wh en som eth in g n eed s to h ap p en . W ith a m ou se, an in terru p t is u sed wh en ever th e m ou se h as in form ation to sen d to th e m ou se d river. If a con flict occu rs an d th e sam e in terru p t u sed by th e m ou se is u sed by a d ifferen t d evice, th e m ou se will n ot work p rop erly—if at all. In terru p t con flicts d o n ot n orm ally occu r if you r system u ses a m ou se p ort, bu t th ey can occu r with th e oth er typ es of m ou se in terfaces. Mou se p orts bu ilt in to m od ern m oth erboard s are alm ost always set to IRQ 12. Be su re if you r system h as a m oth erboard m ou se p ort th at you d on ’t set an y oth er ad ap ter card s to IRQ 12, or a con flict will resu lt.

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W h en you are u sin g a serial m ou se, in terru p t con flicts typ ically occu r if you ad d a th ird an d fou rth serial p ort, u sin g eith er an exp an sion card or an in tern al serial d evice, su ch as a m od em . Th is is becau se in ISA bu s system s, th e od d -n u m bered serial p orts (1 an d 3) are u su ally con figu red to u se th e sam e in terru p ts, as are th e even -n u m bered p orts (2 an d 4). Th u s, if you r m ou se is con n ected to COM2: an d an in tern al m od em u ses COM4:, th ey both m ay u se th e sam e in terru p t, an d you can n ot u se th em at th e sam e tim e. Becau se th e m ou se gen erates in terru p ts on ly wh en it is m oved , you m ay fin d th at th e m od em fu n ction s p rop erly u n til you tou ch th e m ou se, at wh ich p oin t th e m od em is d iscon n ected . You m ay be able to u se th e m ou se an d m od em at th e sam e tim e by m ovin g on e of th em to a d ifferen t serial p ort. For in stan ce, if you r m ou se u ses COM1: an d th e m od em still u ses COM4:, you can u se th em both at on ce becau se od d an d even p orts u se d ifferen t in terru p ts. Th e best way arou n d th ese in terru p t con flicts is to m ake su re n o two d evices u se th e sam e in terru p t. Serial p ort ad ap ters are available for ad d in g COM3: an d COM4: serial p orts th at d o n ot sh are th e in terru p ts u sed by COM1: an d COM2:. Th ese board s en able th e n ew COM p orts to u se oth er n orm ally available in terru p ts, su ch as IRQs 10, 11, 12, 15, or 5. I n ever recom m en d con figu rin g a system with sh ared in terru p ts; it is a su re way to ru n in to p roblem s later. If you su sp ect an in terru p t p roblem with a bu s-typ e m ou se, you can u se th e Device Man ager bu ilt in to W in d ows 9x (wh ich is accessible from th e System Con trol Pan el) or even a p rogram su ch as MicroSoft Diagn ostics (MSD) to h elp you id en tify wh at in terru p t is bein g u sed by th e m ou se. You get MSD free with W in d ows 3.0 or later, as well as with MS-DOS 6.0 or later. ◊◊ See “ Operating System Diagnostics,” p. 995

Be aware th at p rogram s th at attem p t to id en tify IRQ u sage su ch as MSD are n ot always 100 p ercen t accu rate—in fact, th ey are in accu rate in m an y cases—an d th ey u su ally req u ire th at th e d evice d river for th e p articu lar d evice be load ed to work. Th e Device Man ager in W in d ows 9x is p art of th e Plu g-an d -Play (Pn P) software for th e system , an d it is u su ally 100 p ercen t accu rate on Pn P h ard ware. Alth ou gh som e of th ese in terru p t-rep ortin g p rogram s can h ave p roblem s, m ost will easily id en tify th e m ou se IRQ if th e m ou se d river h as been load ed . After th e IRQ is id en tified , you m ay n eed to ch an ge th e IRQ settin g of th e bu s m ou se ad ap ter or on e or m ore oth er d evices in you r system so th at everyth in g works togeth er p rop erly. If you r d river refu ses to recogn ize th e m ou se at all, regard less of its typ e, try u sin g a d ifferen t m ou se th at you kn ow works. Rep lacin g a d efective m ou se with a kn own good on e m ay be th e on ly way to kn ow wh eth er th e p roblem is in d eed cau sed by a bad m ou se. I h ave h ad p roblem s in wh ich a bad m ou se cau sed th e system to lock righ t as th e d river load ed or even wh en d iagn ostics su ch as MSD attem p ted to access th e m ou se. You can easily ferret ou t th is typ e of p roblem by load in g MSD with th e /I op tion , wh ich cau ses

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MSD to byp ass its in itial h ard ware d etection . Th en ru n each of th e tests sep arately, in clu d in g th e m ou se test, to see wh eth er th e system locks. If th e system locks d u rin g th e m ou se test, you h ave fou n d a p roblem with eith er th e m ou se or th e m ou se p ort. Try rep lacin g th e m ou se to see wh eth er th at h elp s. If it d oes n ot, you m ay n eed to rep lace th e serial p ort or bu s m ou se ad ap ter. If a m oth erboard -based m ou se p ort goes bad , you can rep lace th e en tire m oth erboard —wh ich is u su ally exp en sive—or you can ju st d isable th e m oth erboard m ou se p ort via ju m p ers or th e system BIOS setu p p rogram an d in stall a serial or bu s m ou se in stead . Th is en ables you to con tin u e u sin g th e system with ou t h avin g to rep lace th e m oth erboard . Soft w are Problem s. Software p roblem s can be a little trickier th an h ard ware p roblem s. Software p roblem s gen erally m an ifest th em selves as th e m ou se “ju st n ot workin g.” In su ch in stan ces, you n eed to ch eck th e d river an d you r software ap p lication s before assu m in g th at th e m ou se h as gon e bad . D ri v e r So f t w a re . To fu n ction p rop erly, th e m ou se req u ires th e in stallation of a d evice d river. In DOS, you h ave to load th e d river m an u ally th rou gh you r CONFIG.SYS or AUTOEXEC.BAT file, bu t th e d river is au tom atically load ed in all version s of W in d ows. I n orm ally recom m en d u sin g th e d efau lt d rivers bu ilt in to th e W in d ows or OS/ 2 op eratin g system s. In th ose en viron m en ts, n o ad d ition al extern al d river is n ecessary. Th e on ly reason for load in g an extern al d river (via CONFIG.SYS) is if you wan t th e m ou se to work with DOS ap p lication s in W in d ows 3.1. W in d ows 9x d rivers su p p ort th e u se of th e m ou se in DOS ap p lication s by d efau lt. If you n eed th e m ou se to work in stan d ard DOS—in oth er word s, ou tsid e W in d ows or OS/ 2—you m u st load a d evice d river th rou gh eith er you r CONFIG.SYS file or you r AUTOEXEC.BAT file. Th is d river, if load ed in th e CONFIG.SYS file, is typ ically called MOUSE.SYS. Th e version th at load s in th e AUTOEXEC.BAT file is called MOUSE.COM. (It is p ossible th at you r m ou se d rivers h ave d ifferen t n am es, d ep en d in g on wh o m an u factu red you r m ou se.) Again , rem em ber th at if you u se a m ou se on ly in W in d ows or OS/ 2, n o extern al d rivers are req u ired becau se th e m ou se d river is bu ilt in . Th e first step to in stallin g a DOS m ou se d river is to m ake su re th e p rop er com m an d to load th e d river is in you r CONFIG.SYS or AUTOEXEC.BAT file. If it isn ’t, ad d th e p rop er lin e, accord in g to th e in form ation su p p lied with you r m ou se. For in stan ce, th e p rop er com m an d to load th e m ou se d river th rou gh th e CONFIG.SYS file for a Microsoft m ou se is as follows: DEVICEHIGH=\DOS\MOUSE.SYS

Th e actu al syn tax of th e com m an d m ay vary, d ep en d in g on wh eth er you are load in g th e d evice in to u p p er m em ory an d wh ere th e d evice d river is located on you r d isk. On e of th e biggest p roblem s with th e sep arate m ou se d river is gettin g it load ed in to an Up p er Mem ory Block (UMB). Th e old er Microsoft m ou se d rivers—version s 9.0 an d earlier—req u ire a very large block of 40–56K UMB to load , an d u p on load in g th ey sh rin k d own to less th an 20K. Even th ou gh th ey take on ly 20K or less after load in g, you still n eed a very large area to get th em “in th e d oor.”

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Th e best tip I can give you with resp ect to th ese sep arate d rivers is to u se th e n ewest d rivers available from Microsoft. Th ese d rivers are in clu d ed with th e n ewer Microsoft m ice an d are sold sep arately as an u p grad e. Th e Microsoft d river works with an y typ e of Microsoft-com p atible m ou se, wh ich basically m ean s ju st abou t an y m ou se at all. Microsoft req u ires th at you p ay abou t $50 for an u p grad e to th e n ewer version s of th e m ou se d river. You can also get th e n ew d river with a n ew m ou se for $35 or less, wh ich m akes th e d river-on ly p u rch ase n ot very cost effective. Microsoft still in clu d es on ly th e old er d river with MS-DOS 6.22 or earlier. IBM in clu d ed th e n ew d river with PC DOS 6.3 bu t switch ed back to th e 8.2 d river in PC DOS 7.0. If you u se version 9.01 or later, th e d river req u ires less m em ory th an p reviou s version s an d au tom atically load s in to h igh m em ory. On e of th e best featu res is th at th e d river first load s in to low m em ory, sh rin ks d own to abou t 24K, an d th en m oves in to u p p er m em ory au tom atically. In ad d ition , th e d river seeks ou t th e sm allest UMB th at can h old it in stead of tryin g on ly th e largest, as wou ld h ap p en if you u sed th e DEVICEHIGH, LOADHIGH, or LH com m an d s to load th e d river. Previou s version s of th e d river cou ld n ot fit in to an u p p er m em ory block u n less th at block was at least 40–56K or larger in size, an d th ey wou ld certain ly n ot m ove in to u p p er m em ory au tom atically. Th e en h an ced selfload in g cap ability of th e Microsoft DOS m ou se d river 9.01 an d h igh er can save m u ch m em ory sp ace. It is well worth h avin g. √√ See “ Taking Advantage of Unused Upper M emory,” p. 387

After p lacin g th e p rop er d river load com m an d in you r CONFIG.SYS or AUTOEXEC.BAT file, reboot th e system with th e m ou se con n ected an d m ake su re th e d river load s p rop erly. If th e p rop er com m an d is in p lace an d th e d river is n ot load in g, watch you r vid eo screen as you r system boots. At som e p oin t, you sh ou ld see a m essage from th e m ou se d river in d icatin g th at it is load ed . If you see a m essage in d icatin g th at th e d river failed to load in stead , you m u st d eterm in e wh y. For exam p le, th e d river m ay n ot be able to load becau se n ot en ou gh m em ory is available. After you d eterm in e wh y th e d river is n ot load in g, you n eed to rectify th e situ ation an d m ake su re th e d river load s. D OS Ap p l i c a t i o n So f t w a re . If you r m ou se d oes n ot work with a sp ecific p iece of DOS ap p lication software, ch eck th e setu p in form ation or con figu ration section of th e p rogram . Make su re you in d icated to th e p rogram (if n ecessary) th at you are u sin g a m ou se. If it still d oes n ot work an d th e m ou se works with oth er software you are u sin g, con tact th e tech n ical su p p ort d ep artm en t of th e ap p lication software com p an y. M icrosoft Int elliM ouse Late in 1996, Microsoft in trod u ced a n ew variation of its p op u lar m ou se, called th e IntelliMouse. Th is d evice looks exactly like th e stan d ard Microsoft m ou se excep t for a m in iatu re gray wh eel risin g u p between th e two bu tton s. Th is wh eel rep resen ts th e on ly m ajor ch an ge in extern al m ou se d esign in m an y years. Th e wh eel h as two m ain fu n ction s. Th e p rim ary fu n ction is to act as a scrollin g d evice, en ablin g you to scroll th rou gh d ocu m en ts or W eb p ages by m an ip u latin g th e wh eel with you r in d ex fin ger. Th e wh eel also fu n ction s as a th ird m ou se bu tton wh en you p ress it.

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Alth ou gh th ree-bu tton m ice h ave been available for years, th e scrollin g fu n ction is a real breakth rou gh . No lon ger d o you h ave to m ove th e m ou se p oin ter to click th e scrollbar on th e righ t sid e of you r screen or take you r h an d off of th e m ou se to u se th e arrow keys on th e keyboard . You ju st p u sh or p u ll on th e wh eel. Th is is a m ajor con ven ien ce, esp ecially wh en browsin g W eb p ages or workin g with word p rocessin g d ocu m en ts or sp read sh eets. Also, u n like th ree-bu tton m ice from oth er ven d ors, th e In telliMou se’s wh eelbu tton d oesn ’t seem to get in th e way an d you are less likely to click it by m istake. Th e m ajor d rawback to th e In telliMou se is th at th e wh eel fu n ction s on ly in software th at is written to su p p ort it. At th e tim e th e In telliMou se d ebu ted , Microsoft In tern et Exp lorer h ad alread y been m od ified to u se th e n ew wh eel, an d all th e ap p lication s in Office 97 su p p ort it as well. For exam p le, m ost Office 97 ap p lication s allow you to h old d own th e Ctrl key wh ile tu rn in g th e wh eel to zoom in an d ou t. Man ip u latin g th e wh eel wh ile h old in g d own th e Sh ift key exp an d s an d collap ses ou tlin es. As n ew an d u p d ated version s of oth er software com e ou t, you can exp ect th at th ey will also su p p ort th e n ew wh eel fu n ction s. Th e In telliMou se 2.0 d river com bin es featu res from earlier version s of Microsoft’s m ou se d river with som e in terestin g n ew fu n ction s. A featu re called ClickLock allows you to d rag item s with ou t h old in g d own th e p rim ary m ou se bu tton . You can cu stom ize th is featu re by sp ecifyin g h ow lon g you h ave to h old th e bu tton d own to activate ClickLock. You can also con figu re th e wh eel to scroll a sp ecified n u m ber of lin es or scroll a screen with each click of th e wh eel. You can also set th e d river software so th at th e wh eel-bu tton ign ores all ap p lication sp ecific fu n ction s an d in stead p erform s on e of fou r p reset fu n ction s in all W in d ows ap p lication s. Th e fou r ch oices are as follows: ■ Dou ble-left-click ■ Op en an ap p lication ’s Help file ■ Switch to W in d ows Exp lorer ■ Brin g u p th e W in d ows Start m en u Oth er d river featu res retain ed from earlier version s in clu d e a Sn ap To featu re, wh ich m oves th e p oin ter to th e d efau lt bu tton of a d ialog box, an d fu n ction s th at ad d trails wh en th e p oin ter m oves an d m ake th e p oin ter d isap p ear wh en you start typ in g. TrackPoint II/ III On October 20, 1992, IBM in trod u ced a revolu tion ary n ew p oin tin g d evice called TrackPoint II as an in tegrated featu re of its n ew Th in kPad 700 an d 700C com p u ters. Often referred to as a pointing stick d evice, it con sists p rim arily of a sm all ru bber cap th at ap p ears on th e keyboard righ t above th e B key, between th e G an d H keys. Th is was th e first sign ifican t n ew p oin tin g d evice sin ce th e m ou se h ad been in ven ted n early 30 years earlier!

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Th is d evice occu p ies n o sp ace on a d esk, d oes n ot h ave to be ad ju sted for left-h an d ed or righ t-h an d ed u se, h as n o m ovin g p arts to fail or becom e d irty, an d —m ost im p ortan tly— d oes n ot req u ire you to m ove you r h an d s from th e h om e row to u se. Th is is an absolu te boon for tou ch typ ists. I was fortu n ate en ou gh to m eet th e actu al creator an d d esign er of th is d evice in early 1992 at th e sp rin g Com d ex/ W in d ows W orld in Ch icago. He was in a sm all corn er of th e IBM booth sh owin g off h is cu stom -m ad e keyboard s with a sm all silicon e ru bber n u b in th e m id d le. In fact, th e d evices h e h ad were h an d -bu ilt p rototyp es in stalled in stan d ard d esktop keyboard s, an d h e was th ere tryin g to get p u blic reaction an d feed back on h is in ven tion . I was in vited to p lay with on e of th e keyboard s, wh ich was con n ected to a d em on stration system . By p ressin g on th e stick with m y in d ex fin ger, I cou ld m ove th e m ou se p oin ter on th e screen . Th e stick itself d id n ot m ove, so it was n ot a joystick. In stead , it h ad a silicon e ru bber cap th at was con n ected to p ressu re tran sd u cers th at m easu red th e am ou n t of force m y fin ger was ap p lyin g an d th e d irection of th e force an d m oved th e m ou se p oin ter accord in gly. Th e h ard er I p ressed , th e faster th e p oin ter m oved . I cou ld m ove th e p oin ter in an y d irection sm ooth ly by sligh tly ch an gin g th e d irection of p u sh or p u ll. Th e silicon e ru bber grip p ed m y fin ger even th ou gh I h ad been sweatin g from d ash in g abou t th e sh ow. After p layin g arou n d with it for ju st a few m in u tes, th e m ovem en ts becam e au tom atic—alm ost as if I cou ld ju st “th in k” abou t wh ere I wan ted th e p oin ter to go. After reflectin g on th is for a m in u te, it really h it m e: Th is h ad to be th e m ost revolu tion ary p oin tin g d evice sin ce th e m ou se itself! Not on ly wou ld th is be a n atu ral rep lacem en t for a m ou se, bu t it wou ld also be a boon for tou ch typ ists like m e wh o d on ’t like to take th eir h an d s off of th e keyboard . Th e gen tlem an at th e booth tu rn ed ou t to be Ted Selker, th e p rim ary in ven tor of th e d evice. He an d Josep h Ru tled ge created th is in tegrated p oin tin g d evice at th e IBM T.J. W atson Research Cen ter. W h en I asked h im wh en su ch keyboard s wou ld becom e available, h e cou ld n ot an swer. At th e tim e, th ere were ap p aren tly n o p lan s for p rod u ction , an d h e was on ly tryin g to test u ser reaction to th e d evice. Ju st over six m on th s later, IBM an n ou n ced th e ThinkPad 700, wh ich in clu d ed th is revolu tion ary d evice, th en called th e TrackPoin t II In tegrated Poin tin g Device. Sin ce th e origin al version cam e ou t, an en h an ced version with greater con trol an d sen sitivity called th e TrackPoin t III h as been available.

Not e The reason the device was called TrackPoint II is that IBM had previously been selling a convertible mouse/ trackball device called the TrackPoint. No relationship exists between the original TrackPoint mouse/ trackball, which has since been discontinued, and the TrackPoint II integrated device. Since the original TrackPoint II came out, an improved version called TrackPoint III is now available. It is basically an improved version of the same design. In the interest of simplicity, I will refer to all of the TrackPoint II, III, and successive devices as just TrackPoint.

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In its fin al p rod u ction form , th e TrackPoin t con sists of a sm all red silicon e ru bber kn ob n estled between th e G, H, an d B keys on th e keyboard . Th e p rim ary an d secon d ary m ou se bu tton s are p laced below th e Sp acebar wh ere you can easily reach th em with you r th u m bs with ou t takin g you r h an d s off th e keyboard . IBM stu d ies con d u cted by Selker fou n d th at th e act of rem ovin g you r h an d from th e keyboard to reach for a m ou se an d rep lacin g th e h an d on th e keyboard takes ap p roxim ately 1.75 secon d s. If you typ e 60wp m , th at can eq u al n early two lost word s p er m in u te, n ot in clu d in g th e tim e lost wh ile you regain you r train of th ou gh t. Alm ost all th is tim e can be saved each tim e you u se th e track p oin t to eith er m ove th e p oin ter or m ake a selection (click or d ou ble-click). Th e com bin ation of th e bu tton s an d th e p osition in g kn ob also en able you to p erform d rag-an d -d rop fu n ction s easily. IBM’s research also fou n d th at p eop le can get u p to 20 p ercen t m ore work accom p lish ed u sin g th e TrackPoin t in stead of a m ou se, esp ecially wh en th e ap p lication in volves a m ix of typ in g an d p oin tin g activities, su ch as with word p rocessin g, sp read sh eets, an d oth er typ ical office ap p lication s. In u sability tests with th e TrackPoin t III, IBM p rovid ed a grou p of d esktop com p u ter u sers with both a TrackPoin t an d a trad ition al m ou se. After two weeks, 80 p ercen t of th e u sers h ad u n p lu gged th eir m ice an d switch ed solely to th e TrackPoin t d evice. Selker is con vin ced (as am I) th at th e TrackPoin t is th e best p oin tin g solu tion for both lap top an d d esktop system s. An oth er featu re of th e TrackPoin t is th at a stan d ard m ou se can be con n ected to th e system at th e sam e tim e to allow for d u al-p oin ter u se. In th is case, a sin gle m ou se p oin ter wou ld still be on th e screen bu t both th e TrackPoin t an d th e sim u ltan eou sly con n ected m ou se cou ld m ove th e p oin ter. Th is n ot on ly en ables a sin gle p erson to u se both d evices, bu t also en ables two p eop le to u se th e TrackPoin t an d th e m ou se sim u ltan eou sly to m ove th e p oin ter on th e screen . Th e first p oin tin g d evice th at m oves (th u s issu in g a system in terru p t) takes p reced en ce an d retain s con trol over th e m ou se p oin ter on th e screen u n til it com p letes its m ovem en t action . Th e secon d p oin tin g d evice is au tom atically locked ou t u n til th e p rim ary d evice is station ary. Th is en ables th e u se of both d evices, wh ile p reven tin g each on e from in terferin g with th e oth er. Recogn izin g th e sign ifican ce of th e TrackPoin t, esp ecially for p ortable system s, several oth er m an u factu rers of lap top an d n otebook p ortable com p u ters, su ch as Tosh iba an d Texas In stru m en ts, h ave licen sed th e TrackPoin t p oin tin g d evice from IBM. Th ey often give th e d evice a d ifferen t n am e, bu t th e tech n ology an d op eration are th e sam e. For exam p le, Tosh iba calls its p oin tin g stick th e Accu p oin t. I h ave com p ared th e TrackPoin t d evice to oth er p oin tin g d evices for n otebooks, su ch as th e trackballs an d even th e cap acitive tou ch p ad s. Bu t n oth in g com p ares in term s of accu racy an d con trol, an d , of cou rse, you d on ’t h ave to take you r h an d s off of th e keyboard ! Un fortu n ately, m an y of th e lower-en d p ortable system m an u factu rers h ave ch osen n ot to licen se th e IBM TrackPoin t tech n ology, bu t in stead h ave attem p ted to cop y it u sin g in ferior tran sd u cers an d con trol software. Th e m ajor d rawback to th ese n on licen sed TrackPoin t typ e d evices is th at th ey sim p ly d o n ot p erform as well as th e official version s

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licen sed from IBM. Th ey are u su ally slow to resp on d , slu ggish in op eration , an d lack th e sen sitivity an d accu racy fou n d in th e IBM-d esign ed version s. On e way of tellin g th at th e TrackPoin t d evice is licen sed from IBM an d u ses th e IBM tech n ology is th at it will accep t IBM TrackPoin t II or III ru bber cap s. Th ese h ave a sq u are h ole in th em an d will p rop erly lock on to an y of th e licen sed version s, su ch as th ose fou n d in Tosh iba system s. IBM recen tly u p grad ed its p oin tin g stick an d n ow calls it TrackPoin t III. Th ere are two m ain d ifferen ces in th e III system , bu t th e on e th at is m ost obviou s is in th e ru bber cap . IBM always u ses red cap s in th eir TrackPoin t d evice, wh ile oth er com p an ies u se d ifferen t colors (Tosh iba u ses green or gray, for exam p le). However, th e m ain d ifferen ce in th e n ew TrackPoin t III cap s is in th e ru bber com p osition , n ot th e color. Th e IBM TrackPoin t II an d Tosh iba Accu p oin t cap s are m ad e ou t of silicon e ru bber, wh ich is grip p y an d works well in m ost situ ation s. However, if th e u ser h as greasy fin gers, th e textu red su rface of th e ru bber can absorb som e of th e grease an d becom e slip p ery. Clean in g th e cap (an d th e u ser’s h an d s) solves th e p roblem , bu t it can be an n oyin g at tim es. Th e n ew TrackPoin t III cap s are m ad e ou t of a d ifferen t typ e of ru bber, wh ich Selker calls “p lastic san d p ap er.” Th is typ e of cap is m u ch m ore grip p y, an d d oes n ot req u ire clean in g excep t for cosm etic p u rp oses. I h ave u sed both typ es of cap s an d can say for certain th at th e TrackPoin t III cap is su p erior!

Not e Because the Accupoint device used in the Toshiba notebooks is licensed from IBM , it uses the same hardware (a pressure transducer called a strain gauge) and takes the same physical caps. I ordered a set of the new TrackPoint III caps and installed them on my Toshiba portable systems, which dramatically improved the grip. You can get these caps by ordering them from IBM Parts directly or from others who sell IBM parts, such as DakTech, under IBM part number 84G6536. The cost is approximately $9 for a set of two “ plastic sandpaper” red caps.

Rep lacin g th e cap is easy—sim p ly grab th e existin g cap with you r fin gers an d p u ll straigh t u p ; it will p op righ t off. Th en p u sh on th e n ew red IBM TrackPoin t III cap in its p lace. You will th an k m e wh en you feel h ow you can grip th e n ew IBM cap m u ch m ore easily th an you can grip th e d esign s u sed by oth ers. Th e oth er d ifferen ce between th e TrackPoin t II an d III from IBM is in th e con trol software. IBM ad d ed rou tin es th at im p lem en t a su btle tech n iq u e Selker calls “n egative in ertia,” bu t wh ich is m arketed u n d er th e term QuickStop response. Th is software n ot on ly takes in to accou n t h ow far you p u sh th e p oin ter in an y d irection , bu t also h ow q u ickly you p u sh or release it. Selker fou n d th at th is im p roved software (an d th e san d p ap er cap ) allows p eop le to m ake selection s u p to 8% faster. Th e TrackPoin t is obviou sly an id eal p oin tin g d evice for a p ortable system in wh ich lu ggin g arou n d an extern al m ou se or trackball can be in con ven ien t. Th e trackballs an d m in i-trackballs bu ilt in to som e lap top keyboard s are very d ifficu lt to u se an d u su ally req u ire rem ovin g you r h an d s from th e h om e row. Mou se an d trackball d evices are

M ice

n otoriou s for becom in g “sticky” as th e ball p icks u p d irt th at affects th e in tern al roller m otion . Th is is esp ecially n oticeable with th e sm aller m in i-trackball d evices. Man y n ewer n otebook system s in clu d e a tou ch p ad , an d alth ou gh th is seem ed like a good id ea at first, it p ales in com p arison with th e TrackPoin t. Th e tou ch p ad s are based on a cap acitive effect, an d p oin ter op eration can becom e erratic if you r skin is eith er too d ry or too m oist. Th eir biggest d rawback is th at th ey are p osition ed on th e keyboard below th e Sp acebar, wh ich m ean s you eith er h ave to rem ove you r h an d from th e h om e row to p lace you r in d ex fin ger on th e p ad , or try to u se th e p ad with you r th u m b, wh ich h as too wid e a con tact area for p recise m ovem en t an d con trol. Th e bottom lin e is th at an yon e wh o tou ch typ es sh ou ld stron gly con sid er on ly p ortable system s th at in clu d e an IBM-licen sed TrackPoin t d evice (su ch as Tosh iba). TrackPoin ts are far su p erior to oth er p oin tin g d evices, su ch as th e tou ch p ad s, becau se th e TrackPoin t is faster to u se (you d on ’t h ave to take you r h an d s off of th e h om e row on th e keyboard ), easier to ad ap t to (esp ecially for sp eed y tou ch typ ists), an d far m ore p recise. Bu t th e ben efits of th e TrackPoin t are n ot lim ited to p ortable system s. Becau se I u se a n otebook so often an d h ave fou n d th e TrackPoin t so fast an d easy to u se, I wan ted to u se it on m y d esktop system s as well. For d esktop system s, I u se a Lexm ark keyboard with th e IBM-licen sed TrackPoin t d evice bu ilt in . Th is m akes for a m ore con sisten t in terface between d esktop an d n otebook u se becau se I can u se th e sam e p oin tin g d evice in both en viron m en ts. On e d rawback for som e old er system s is th at th e TrackPoin t d evice in th ese keyboard s works on ly with system s th at u sed a PS/ 2- or m oth erboard -typ e m ou se con n ector—n o serial version is available. I list th e p art n u m ber for th e IBM En h an ced keyboard with th e TrackPoin t in th e section “Rep lacem en t Keyboard s” earlier in th is ch ap ter. You can also p u rch ase th ese keyboard s d irectly from Un icom p , wh ich h as p u rch ased Lexm ark’s keyboard tech n ology. Glidepoint In resp on se to th e TrackPoin t, oth er com p an ies h ave ad op ted n ew p oin tin g d evice tech n ologies as well. For exam p le, Alp s Electric h as in trod u ced a tou ch p ad p oin tin g d evice called th e Glidepoint. Th e Glid ep oin t u ses a flat, sq u are p ad th at sen ses fin ger p osition th rou gh bod y cap acitan ce. Th is is sim ilar to th e cap acitan ce-sen sitive elevator bu tton con trols you som etim es en cou n ter in office bu ild in gs or h otels. In stead of sittin g in between th e keys, th e Glid ep oin t is m ou n ted below th e Sp acebar, an d it d etects p ressu re ap p lied by you r th u m bs or fin gers. Tran sd u cers u n d er th e p ad con vert fin ger m ovem en t in to p oin ter m ovem en t. Several lap top an d n otebook m an u factu rers h ave licen sed th is tech n ology from Alp s an d are in corp oratin g it in to th eir p ortable system s. Ap p le was on e of th e first to ad op t it in its p ortable system s. Alth ou gh it seem s to h ave gain ed wid e accep tan ce, th is tech n ology h as a n u m ber of d rawbacks. Op eration of th e d evice can be erratic, d ep en d in g on skin resistan ce an d m oistu re con ten t. Th e biggest d rawback is th at to op erate th e tou ch p ad , u sers h ave to rem ove th eir h an d s from th e h om e row on th e keyboard , wh ich d ram atically slows th eir p rogress. In ad d ition , th e op eration of th e tou ch p ad can be im p recise, d ep en d in g on h ow p oin ty you r fin ger or th u m b is!

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On th e oth er h an d , if you ’re n ot a tou ch typ ist, th en rem ovin g you r h an d s from th e keyboard to op erate th e tou ch p ad m ay be easier th an u sin g a TrackPoin t. Even with th eir d rawbacks, tou ch p ad typ e p oin tin g d evices are still vastly p referable for p ortable system s to u sin g a trackball or a cu m bersom e extern al m ou se. The Fut ure. Poin ter tech n ology is p rogressin g in ways th at were u n d ream ed of wh en th e first m ice were d evelop ed . Hard ware d evelop ers are begin n in g to take ad van tage of th e bid irection al in terfaces on PCs to d evelop in p u t d evices th at react to a u ser’s action s. A com p an y called Im m ersion Corp . is p lan n in g to release a m ou se called FEELit in late 1998. FEELit is p erm an en tly m ou n ted to a sp ecially d esign ed p ad th at h ou ses a p rocessor for gen eratin g real-tim e sim u lation s. An electrom agn etic d rive in sid e th e p ad gen erates sen sation s, en ablin g you to feel th reed im en sion al icon s, win d ow ed ges, scroll bu tton s, an d oth er W in d ows artifacts. You can click an d d rag objects with variable p ressu re an d feel th e elasticity of sh ap es as you stretch th em . Develop ers can write ap p lication s u sin g sp ecial fu n ction calls th at allow th em to in corp orate th e feelin gs gen erated by textu res, su rfaces, liq u id s, an d vibration s in to th eir p rogram s. Th is typ e of tech n ology h as great p rom ise for m akin g com p u ters tru ly in teractive an d for en h an cin g th e reality of gam es an d oth er sim u lated en viron m en ts.

Gam e Adapt er ( Joyst ick) Int erface Th e gam e control or joystick ad ap ter is a sp ecial in p u t d evice th at en ables you to attach u p to fou r p ad d les or two joysticks to a PC system . Th e term paddle is u sed to refer to a kn ob th at can be rotated to m ove an object on th e screen . It was n am ed after th e first p op u lar vid eo gam e, called Pon g, in wh ich th e kn ob m oved th e gam e p ad d les. You can fin d th e gam e ad ap ter fu n ction on a d ed icated ISA bu s ad ap ter card , or it can be com bin ed with oth er fu n ction s on a m u ltifu n ction card . Th e gam e con n ector on th e card is a fem ale 15-p in D-Sh ell typ e socket (see Figu re 7.19). Th e gam e ad ap ter can recogn ize u p to fou r sim p le con tact switch es (called buttons) an d fou r resistive in p u ts. Each p ad d le n orm ally h as on e bu tton an d on e kn ob th at con trols a variable resistor, wh ereas a joystick n orm ally h as two bu tton s an d a cen tral stick th at con trols two variable resistors. In a joystick, th e variable resistors are tied to th e cen tral stick. On e in d icates th e relative h orizon tal p osition (or x-coord in ate) of th e stick, an d th e oth er in d icates its relative vertical p osition (or y-coord in ate). More ad van ced con trollers track th e rotation al m ovem en t (R-axis) of th e joystick, an d som e also track th e p osition of th e “top h at,” an ad d ition al con trol th at sits atop th e stick an d is m an eu vered with th e th u m b. Also, som e d igital joysticks sen se p osition u sin g crystals in th e top h at to gen erate an electrical cu rren t wh en it is p ressed or d istorted . Digital joysticks also allow for th e u se of m ore th an two p airs of X-Y axes; in fact, joysticks are n ow bein g d esign ed th at in clu d e a Z-axis, to track m ovem en t in th e th ird d im en sion .

Game Adapter (Joystick) Interface

15-Pin D-Shell Connector

1

9

15 8

FIG. 7.19 Typ ical gam e ad ap ter an d 15-p in con n ector. Th e Un iversal Serial Bu s also p rom ises to im p rove th e gam in g exp erien ce by p rovid in g a bid irection al in terface th rou gh wh ich you will be able to feel a resp on se in a joystick to an artificial stim u lu s. By in tegratin g servo m ech an ism s in to th e joystick, you can be m ad e to feel bu m p s in th e road wh ile p layin g a d rivin g gam e an d win d resistan ce in a fligh t sim u lator. Th is tech n iq u e is called force feedback; it is alread y bein g assim ilated in to p rod u cts su ch as th e Microsoft Sid ewin d er Force Feed back Pro gam e con troller. Resistor in p u ts are variable, from 0 to 100K oh m s. Th e ad ap ter con verts th e resistive valu e to a d igital p u lse with a d u ration p rop ortion al to th e resistive load . Software can tim e th ese p u lses to d eterm in e th e relative resistan ce valu e. Th e gam e ad ap ter d oes n ot u se m u ch in th e way of system resou rces. Th e card d oes n ot u se an IRQ , DMA ch an n el, or m em ory, an d it req u ires on ly a sin gle I/ O ad d ress (p ort) 201h . Th e ad ap ter is con trolled by read in g an d writin g d ata to an d from p ort 201h . Note th at joystick resistan ce is read by p ollin g th e ad ap ter; th e gam e p ort in terface is n ot in terru p t d riven . Th is m ean s th at a p rogram h as to scan th e d evice by sen d in g an I/ O com m an d for in p u t rath er th an by receivin g an in terru p t, as with oth er (su ch as serial) d evices. Table 7.11 sh ows th e in terface con n ector p in ou t sp ecification for a PC-com p atible gam e ad ap ter.

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Table 7.11

PC-Com pat ible Gam e Adapt er Connect or

Pin

Signal

Funct ion

I/ O

1

+5v

Paddle 1, Joystick A

Out

2

Button 4

Paddle 1 button, Joystick A button #1

In

3

Position 0

Paddle 1 position, Joystick A x-coordinate

In

4

Ground

—

—

5

Ground

—

—

6

Position 1

Paddle 2 position, Joystick A y-coordinate

In

7

Button 5

Paddle 2 button, Joystick A button #2

In

8

+5v

Paddle 2

Out

9

+5v

Paddle 3 and Joystick B

Out

10

Button 6

Paddle 3 button, Joystick B button #1

In

11

Position 2

Paddle 3 position, Joystick B x-coordinate

In

12

Ground

—

—

13

Position 3

Paddle 4 position, Joystick B y-coordinate

In

14

Button 7

Paddle 4 button, Joystick B button #2

In

15

+5v

Paddle 4

Out

Becau se th is ad ap ter actu ally read s resistan ce an d can be easily m an ip u lated with stan d ard p rogram m in g lan gu ages, th e gam e ad ap ter serves as a p oor m an ’s d ata acq u isition board or real-tim e in terface card . W ith it, you can h ook u p to fou r sen sors an d fou r switch es an d easily read th e d ata on th e PC. Gam e ad ap ters are available for ISA bu s system s from a n u m ber of ven d ors, an d joysticks u sin g th e Un iversal Serial Bu s sh ou ld be available by th e tim e you read th is. Con su lt Ap p en d ix A for som e com p an ies th at m ay offer th ese typ es of ad ap ters. Gen erally, th e best p lace to look is on e of th e larger m ail ord er system an d p erip h eral ven d ors. Som e m an u factu rers h ave p rod u ced sp ecialized joysticks th at really d on ’t look like joysticks at all. Perh ap s th e best kn own of th ese is th e steerin g wh eel an d p ed al con trol set sold for u se with d rivin g an d fligh t sim u lator gam es. However, th ese d evices are exactly th e sam e as th e stan d ard joystick an d p ad d les as far as you r system is con cern ed . In stead of p ad d le kn obs, th ey h ave steerin g wh eels an d p ed als con trollin g th e variable resistors in th e circu it. A n u m ber of th ese d evices are on th e m arket for th e p op u lar d rivin g an d fligh t sim u lator gam es, an d th ey can m ake th ese gam es m u ch m ore realistic. Becau se th e d ifferen t con trols can be con n ected to d ifferen t p ad d le in p u ts on th e gam e ad ap ters, m ake su re th at you r software will su p p ort th e p articu lar con trol d evice you select.

Chapter 8

Video Hardware

8

As th e visu al lin k between you an d you r com p u ter, th e vid eo d isp lay is on e of th e m ost im p ortan t com p on en ts of you r PC. Before CRT m on itors cam e in to gen eral u se, th e teletyp ewriter was th e stan d ard com p u ter in terface—a large, lou d d evice th at p rin ted th e in p u t an d ou tp u t ch aracters on a roll of p ap er. Th e first CRT d isp lays were p rim itive by tod ay’s stan d ard s; th ey d isp layed on ly text in a sin gle color, bu t to u sers at th e tim e th ey were a great im p rovem en t. Tod ay, PC vid eo d isp lays are m u ch m ore sop h isticated , bu t you m u st be carefu l wh en selectin g vid eo h ard ware for you r com p u ter. W orkin g with even th e fastest an d m ost p owerfu l PC can be a ch ore wh en th e d isp lay slows th e system d own , cau ses eyestrain , or is n ot su itable for th e tasks you wan t to accom p lish . Th e vid eo su bsystem of a PC con sists of two m ain com p on en ts: ■ Mon itor (or vid eo d isp lay) ■ Vid eo ad ap ter (also called th e vid eo card or grap h ics ad ap ter) Th is ch ap ter exp lores th e ran ge of PC vid eo ad ap ters on th e m arket tod ay, an d th e d isp lays th at work with th em .

Not e The term video, as it is used in this context, does not necessarily imply the existence of a moving image, such as on a television screen. All adapters that feed signals to a monitor or other display are video adapters, whether or not they are used with applications that display moving images, such as multimedia or videoconferencing software.

M onit ors A m on itor req u ires a sou rce of in p u t. Th e sign als th at ru n to you r m on itor com e from a vid eo ad ap ter in sid e or p lu gged in to you r com p u ter. Som e

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com p u ters—su ch as th ose th at u se th e low p rofile (LPX) or n ew low p rofile (NLX) m oth erboard form factor—con tain th is ad ap ter circu itry on th e m oth erboard . Most system s, h owever, u se Baby-AT or ATX-style m oth erboard s an d n orm ally in corp orate th e vid eo ad ap ter on a sep arate circu it board th at is p lu gged in to an exp an sion or bu s slot. Th e exp an sion card s th at p rod u ce vid eo sign als are called video cards, or graphics cards. Th e term vid eo ad ap ter is ap p licable to eith er in tegrated or sep arate vid eo circu itry. W h eth er th e vid eo ad ap ter is bu ilt in to th e m oth erboard or fou n d on a sep arate card , th e circu itry op erates th e sam e way an d gen erally u ses th e sam e com p on en ts.

Not e One product, the Cyrix M ediaGX, actually incorporates video adapter (and audio adapter and RAM controller) functionality into the system processor. The processor’s XpressGRAPHICS feature eliminates the delays incurred by the constant transfer of data to and from the video adapter. Also, because it does not use dedicated memory, the video adapter functions can self-adjust to use as much main system memory as needed for the selected video resolution. Obviously, this is a radical approach to video display technology that requires a motherboard that is built around this special processor.

Display Technologies A m on itor m ay u se on e of several d isp lay tech n ologies. By far th e m ost p op u lar is cath od e ray tu be (CRT) tech n ology, th e sam e tech n ology u sed in television sets. CRTs con sist of a vacu u m tu be en closed in glass. On e en d of th e tu be con tain s an electron gu n ; th e oth er en d con tain s a screen with a p h osp h orou s coatin g. W h en h eated , th e electron gu n em its a stream of h igh -sp eed electron s th at are attracted to th e oth er en d of th e tu be. Alon g th e way, a focu s con trol an d d eflection coil steer th e beam to a sp ecific p oin t on th e p h osp h orou s screen . W h en stru ck by th e beam , th e p h osp h or glows. Th is ligh t is wh at you see wh en you watch TV or you r com p u ter screen . Th e p h osp h or ch em ical h as a q u ality called persistence, wh ich in d icates h ow lon g th is glow will rem ain on screen . Persisten ce is wh at cau ses a fain t im age to rem ain on you r TV screen for a few secon d s after you tu rn th e set off. Th e scanning frequency of th e d isp lay sp ecifies h ow often th e im age is refresh ed . You sh ou ld h ave a good m atch between p ersisten ce an d scan n in g freq u en cy so th e im age h as less flicker (wh ich occu rs wh en th e p ersisten ce is too low) an d n o gh ost im ages (as wh en th e p ersisten ce is too h igh ). Th e electron beam m oves very q u ickly, sweep in g th e screen from left to righ t in lin es from top to bottom , in a p attern called a raster. Th e horizontal scan rate refers to th e sp eed at wh ich th e electron beam m oves laterally across th e screen . Du rin g its sweep , th e beam strikes th e p h osp h or wh erever an im age sh ou ld ap p ear on screen . Th e beam also varies in in ten sity to p rod u ce d ifferen t levels of brigh tn ess. Becau se th e glow begin s to fad e alm ost im m ed iately, th e electron beam m u st con tin u e to sweep th e screen to m ain tain an im age—a p ractice called redrawing or refreshing th e screen .

M onitors

Most d isp lays h ave an id eal refresh rate (also called th e vertical scan frequency) of abou t 70 h ertz (Hz), m ean in g th at th e screen is refresh ed 70 tim es p er secon d . Refresh rates th at are too low cau se th e screen to flicker, con tribu tin g to eyestrain . Th e h igh er th e refresh rate, th e better for you r eyes. It is im p ortan t th at th e refresh rates exp ected by you r m on itor m atch th ose p rod u ced by you r vid eo card . If you h ave m ism atch ed rates, you will n ot see an im age an d m ay actu ally d am age you r m on itor. Som e m on itors h ave a fixed refresh rate. Oth er m on itors m ay su p p ort a ran ge of freq u en cies; th is su p p ort p rovid es bu ilt-in com p atibility with fu tu re vid eo stan d ard s (d escribed in th e “Vid eo Disp lay Ad ap ters” section later in th is ch ap ter). A m on itor th at su p p orts m an y vid eo stan d ard s is called a m ultiple-frequency m onitor. Most m on itors tod ay are m u ltip le-freq u en cy m on itors, wh ich m ean s th ey su p p ort op eration with a variety of p op u lar vid eo sign al stan d ard s. Differen t ven d ors call th eir m u ltip le-freq u en cy m on itors by d ifferen t trad e n am es, in clu d in g m u ltisyn c, m u ltifreq u en cy, m u ltiscan , au tosyn ch ron ou s, an d au totrackin g. Ph osp h or-based screen s com e in two styles—curved an d flat. Th e typ ical d isp lay screen is cu rved , m ean in g th at it bu lges ou tward from th e m id d le of th e screen . Th is d esign is con sisten t with th e vast m ajority of CRT d esign s (th e sam e as th e tu be in m ost television sets). Th e trad ition al screen is cu rved both vertically an d h orizon tally. Som e m od els u se th e Trinitron design, wh ich is cu rved on ly h orizon tally an d is flat vertically. Man y p eop le p refer th is flatter screen becau se it sh ows less glare an d a h igh er-q u ality, m ore accu rate im age. Th e d isad van tage is th at th e tech n ology req u ired to p rod u ce flat-screen d isp lays is m ore exp en sive, resu ltin g in h igh er p rices for th e m on itors. LCD Displays. Altern ative d isp lay d esign s are available, as well. Borrowin g tech n ology from lap top m an u factu rers, som e com p an ies m arket m on itors with LCD (liq u id -crystal d isp lay) d isp lays. LCDs h ave low-glare screen s th at are com p letely flat, an d low p ower req u irem en ts (five watts versu s n early 100 watts for an ord in ary m on itor). Th e color q u ality of an active-m atrix LCD p an el actu ally exceed s th at of m ost CRT d isp lays. At th is p oin t, h owever, LCD screen s u su ally are m ore lim ited in resolu tion th an typ ical CRTs an d are m ore exp en sive; for exam p le, a 14-in ch LCD screen can cost m ore th an $1,000, m ore th an th e cost of a h igh -q u ality 17-in ch CRT m on itor. However, it is im p ortan t to con sid er th at an LCD screen p rovid es a larger viewable im age th an a CRT m on itor of th e sam e size. Th ere are th ree basic LCD ch oices: p assive-m atrix m on och rom e, p assive-m atrix color, an d active-m atrix color. Th e p assive-m atrix d esign s are also available in sin gle- an d d u al-scan version s. In an LCD, a p olarizin g filter creates two sep arate ligh t waves. Th e p olarizin g filter allows ligh t waves th at are align ed on ly with th e filter to p ass th rou gh . After p assin g th rou gh th e p olarizin g filter, th e rem ain in g ligh t waves are all align ed in th e sam e d irection . By align in g a secon d p olarizin g filter at a righ t an gle to th e first, all th ose waves are blocked . By ch an gin g th e an gle of th e secon d p olarizin g filter, th e am ou n t of ligh t allowed to p ass

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can be ch an ged . It is th e role of th e liq u id crystal cell to ch an ge th e an gle of p olarization an d con trol th e am ou n t of ligh t th at p asses. In a color LCD, th ere is an ad d ition al filter th at h as th ree cells for each p ixel—on e each for d isp layin g red , green , an d blu e. Th e ligh t wave p asses th rou gh a liq u id -crystal cell, with each color segm en t h avin g its own cell. Th e liq u id crystals are rod -sh ap ed m olecu les th at flow like a liq u id . Th ey en able ligh t to p ass straigh t th rou gh , bu t an electrical ch arge alters th eir orien tation an d th e orien tation of ligh t p assin g th rou gh th em . Alth ou gh m on och rom e LCDs d o n ot h ave color filters, th ey can h ave m u ltip le cells p er p ixel for con trollin g sh ad es of gray. In a p assive-m atrix LCD, each cell is con trolled by th e electrical ch arges of two tran sistors, d eterm in ed by th e cell’s row an d colu m n p osition s on th e d isp lay. Th e n u m ber of tran sistors alon g th e screen ’s h orizon tal an d vertical ed ges d eterm in es th e resolu tion of th e screen . For exam p le, a screen with an 800×600 resolu tion h as 800 tran sistors on its h orizon tal ed ge an d 600 on th e vertical, for a total of 1,400. As th e cell reacts to th e p u lsin g ch arge from its two tran sistors, it twists th e ligh t wave, with stron ger ch arges twistin g th e ligh t wave m ore. Supertwist refers to th e orien tation of th e liq u id crystals, com p arin g on m od e to off m od e—th e greater th e twist, th e h igh er th e con trast. Ch arges in p assive-m atrix LCDs are p u lsed , so th e d isp lays lack th e brillian ce of activem atrix, wh ich p rovid es a con stan t ch arge to each cell. To in crease th e brillian ce, som e ven d ors h ave tu rn ed to a n ew tech n iq u e called double-scan LCD, wh ich sp lits p assivem atrix screen s in to a top h alf an d bottom h alf, red u cin g th e tim e between each p u lse. Besid es in creasin g th e brigh tn ess, d u al-scan d esign s also in crease th e resp on se tim e an d th erefore th e p ercep tible sp eed of th e d isp lay, m akin g th is typ e m ore u sable for fu llm otion vid eo or oth er ap p lication s wh ere th e d isp layed in form ation ch an ges rap id ly. In an active-m atrix LCD, each cell h as its own d ed icated tran sistor beh in d th e p an el to ch arge it an d twist th e ligh t wave. Th u s, an 800×600 active-m atrix d isp lay h as 480,000 tran sistors. Th is p rovid es a brigh ter im age th an p assive-m atrix d isp lays becau se th e cell can m ain tain a con stan t, rath er th an a m om en tary, ch arge. However, active-m atrix tech n ology u ses m ore en ergy th an p assive-m atrix. W ith a d ed icated tran sistor for every cell, active-m atrix d isp lays are m ore d ifficu lt an d exp en sive to p rod u ce.

Not e Because an LCD display requires a specified number of transistors to support each cell, there are no multiple frequency displays of this type. All the pixels on an LCD screen are of a fixed size, although CRT pixels are variable. Thus, LCD displays are designed to be operated at a specific resolution. Before purchasing this type of display, be sure your video adapter supports the same resolution as the screen, and that the resolution will be sufficient for your needs throughout the life of the monitor.

In both active- an d p assive-m atrix LCDs, th e secon d p olarizin g filter con trols h ow m u ch ligh t p asses th rou gh each cell. Cells twist th e wavelen gth of ligh t to closely m atch th e filter’s allowable wavelen gth . Th e m ore ligh t th at p asses th rou gh th e filter at each cell, th e brigh ter th e p ixel.

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Mon och rom e LCDs ach ieve grayscales (u p to 64) by varyin g th e brigh tn ess of a cell or d ith erin g cells in an on -an d -off p attern . Color LCDs, on th e oth er h an d , d ith er th e th reecolor cells an d con trol th eir brillian ce to ach ieve d ifferen t colors on th e screen . Dou blescan p assive-m atrix LCDs h ave recen tly gain ed in p op u larity becau se th ey ap p roach th e q u ality of active-m atrix d isp lays, bu t d o n ot cost m u ch m ore to p rod u ce th an oth er p assive-m atrix d isp lays. Th e big p roblem with active-m atrix LCDs is th at th e m an u factu rin g yield s are low, forcin g h igh er p rices. Th is m ean s m an y of th e p an els p rod u ced h ave m ore th an a certain m axim u m n u m ber of failed tran sistors. Th e resu ltin g low yield s lim it th e p rod u ction cap acity an d in cu rs h igh er p rices. In th e p ast, several h ot CRTs were n eed ed to ligh t an LCD screen , bu t p ortable com p u ter m an u factu rers n ow u se a sin gle tu be th e size of a cigarette. Fiber-op tic tech n ology even ly sp read s ligh t em itted from th e tu be across an en tire d isp lay. Th an ks to su p ertwist an d trip le-su p ertwist LCDs, tod ay’s screen s en able you to see th e screen clearly from m ore an gles with better con trast an d ligh tin g. To im p rove read ability, esp ecially in d im ligh t, som e lap top s in clu d e backlighting or edgelighting (also called sidelighting). Backlit screen s p rovid e ligh t from a p an el beh in d th e LCD. Ed gelit screen s get th eir ligh t from th e sm all flu orescen t tu bes m ou n ted alon g th e sid es of th e screen . Som e old er lap top s exclu d ed su ch ligh tin g system s to len gth en battery life. Most m od ern lap top s en able you to ru n th e backligh t at a red u ced p ower settin g th at d im s th e d isp lay, bu t allows for lon ger battery life. Th e best color d isp lays are active-m atrix or thin-film transistor (TFT) p an els, in wh ich each p ixel is con trolled by th ree tran sistors (for red , green , an d blu e). Active-m atrix-screen refresh es an d red raws are im m ed iate an d accu rate, with m u ch less gh ostin g an d blu rrin g th an in p assive-m atrix LCDs (wh ich con trol p ixels via rows an d colu m n s of tran sistors alon g th e ed ges of th e screen ). Active-m atrix d isp lays are also m u ch brigh ter an d can easily be read at an an gle. Gas Plasm a Displays. An altern ative to LCD screen s is gas-p lasm a tech n ology, typ ically kn own for its black an d oran ge screen s in som e of th e old er Tosh iba n otebook com p u ters. Som e com p an ies are in corp oratin g gas-p lasm a tech n ology for d esktop screen s an d p ossibly color h igh -d efin ition television (HDTV) flat-p an el screen s. M onochrom e Versus Color Du rin g th e early years of th e IBM PC an d th e com p atibles th at followed , own ers h ad on ly two vid eo ch oices—color u sin g a CGA d isp lay ad ap ter an d m on och rom e u sin g an MDA d isp lay ad ap ter. Sin ce th en , m an y ad ap ter an d d isp lay op tion s h ave h it th e m arket. Mon och rom e m on itors p rod u ce im ages of on e color. Th e m ost p op u lar is am ber, followed by wh ite an d green . Th e color of th e m on itor is d eterm in ed by th e color of th e p h osp h ors on th e CRT screen . Som e m on och rom e m on itors with wh ite p h osp h ors can su p p ort m an y sh ad es of gray.

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Color m on itors u se m ore sop h isticated tech n ology th an m on och rom e m on itors, wh ich accou n ts for th eir h igh er p rices. W h ereas a m on och rom e p ictu re tu be con tain s on e electron gu n , a color tu be con tain s th ree gu n s arran ged in a trian gu lar sh ap e referred to as a delta configuration. In stead of am ber, wh ite, or green p h osp h ors, th e m on itor screen con tain s p h osp h or triad s, wh ich con sist of on e red p h osp h or, on e green p h osp h or, an d on e blu e p h osp h or arran ged in th e sam e p attern as th e electron gu n s. Th ese th ree p rim ary colors can be m ixed to p rod u ce all oth er colors. Mon och rom e m on itors are d ifficu lt to fin d th ese d ays, wh ich is a sh am e becau se th ey d o still h ave ap p lication s. It h as always seem ed wastefu l to m e to d evote a color m on itor to a system ru n n in g an OS with a m on o-color d isp lay, su ch as on a NetW are server. The Right Size Mon itors com e in d ifferen t sizes, ran gin g from 9-in ch to 42-in ch d iagon al m easu re. Th e larger th e m on itor, th e h igh er th e p rice tag—on ce you get beyon d 17 in ch d isp lays, th e p rices skyrocket. Th e m ost com m on m on itor sizes are 14, 15, 17, an d 21 in ch es. Th ese d iagon al m easu rem en ts, u n fortu n ately, often rep resen t n ot th e size of th e actu al im age th at th e screen d isp lays, bu t th e size of th e tu be. As a resu lt, com p arin g on e com p an y’s 15-in ch m on itor to th at of an oth er m ay be u n fair u n less you actu ally m easu re th e active screen area. Th e active screen area refers to th e d iagon al m easu re of th e ligh ted area on th e screen . In oth er word s, if you are ru n n in g W in d ows, th e viewin g area is th e actu al d iagon al m easu re of th e d esktop . Th is area can vary wid ely from m on itor to m on itor, so on e com p an y’s 17-in ch m on itor m ay d isp lay a 15.0-in ch im age, an d an oth er com p an y’s 17-in ch m on itor m ay p resen t a 15.5-in ch im age. Th e followin g table sh ows th e m on itor’s ad vertised d iagon al screen size, alon g with th e ap p roxim ate d iagon al m easu re of th e actu al active viewin g area for th e m ost com m on d isp lay sizes. M onit or Size ( in Inches)

View ing Area ( in Inches)

12

10.5

14

12.5

15

13.5

16

14.5

17

15.5

18

16.5

19

17.5

20

18.5

21

19.5

Th e size of th e actu al viewable area varies from m an u factu rer to m an u factu rer, bu t ten d s to be ap p roxim ately 1.5 in ch es less th an th e actu al screen size. However, you can ad ju st som e m on itors—su ch as som e m od els m ad e by NEC, for exam p le—to d isp lay a

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h igh -q u ality im age th at com p letely fills th e tu be from ed ge to ed ge. Oth er m akes can fill th e screen also, bu t som e of th em d o so on ly by p u sh in g th e m on itor beyon d its com fortable lim its. Th e resu lt is a d istorted im age th at is worse th an th e m on itor’s sm aller, p rop erly ad ju sted p ictu re. Th is p h en om en on is a well-kn own m on itor p u rch asin g caveat an d , as a resu lt, som e m an u factu rers an d ven d ors h ave begu n ad vertisin g th e size of th e active viewin g area of th eir m on itors alon g with th e screen size. Th is m akes it easier for con su m ers to get wh at th ey are p ayin g for. In m ost cases, th e 17-in ch m on itor is cu rren tly th e best bargain in th e in d u stry. A 17-in ch m on itor is recom m en d ed for n ew system s, esp ecially wh en ru n n in g W in d ows, an d is n ot m u ch m ore exp en sive th an a 15-in ch d isp lay. I recom m en d a 17-in ch m on itor as th e m in im u m you sh ou ld con sid er for m ost n orm al ap p lication s. Low-en d ap p lication s can still get away with a 15-in ch d isp lay, bu t you will be lim ited in th e screen resolu tion s th at you can view com fortably. Eigh teen –21-in ch or larger d isp lays are recom m en d ed for h igh -en d system s, esp ecially wh ere grap h ics ap p lication s are th e m ajor focu s. Larger m on itors are p articu larly h an d y for ap p lication s su ch as CAD an d d esktop p u blish in g, in wh ich th e sm allest d etails m u st be clearly visible. W ith a 17-in ch or larger d isp lay, you can see n early an en tire 8 1/ 2×11-in ch p rin t p age in 100% view—in oth er word s, wh at you see on screen virtu ally m atch es th e p age th at will be p rin ted . Th is featu re is called W YSIW YG—sh ort for “wh at you see is wh at you get.” If you can see th e en tire p age at its actu al size, you can save you rself th e trou ble of p rin tin g several d rafts before you get it righ t. W ith th e p op u larity of th e In tern et, m on itor size an d resolu tion becom e even m ore of an issu e. Man y W eb p ages are bein g d esign ed for 1,024×768 resolu tion , wh ich req u ires a 17-in ch CRT d isp lay as a m in im u m to h an d le with ou t eyestrain an d in ad eq u ate focu s. Becau se of th eir m u ch tigh ter d ot p itch , LCD d isp lays in lap top com p u ters can h an d le th at resolu tion easily on 13.3– or even som e 12.1-in ch d isp lays. Usin g 1,024×768 resolu tion m ean s you will be able to view m ost W eb p ages with ou t scrollin g sid eways, wh ich is a m ajor con ven ien ce.

Not e Although many monitors smaller than 17 inches are physically capable of running at 1,024×768 and even higher resolutions, most people have trouble reading print at that size.

M onit or Resolut ion Resolution is th e am ou n t of d etail a m on itor can ren d er. Th is q u an tity is exp ressed in th e n u m ber of h orizon tal an d vertical p ictu re elem en ts, or pixels, con tain ed in th e screen . Th e greater th e n u m ber of p ixels, th e m ore d etailed th e im ages. Th e resolu tion req u ired d ep en d s on th e ap p lication . Ch aracter-based ap p lication s (su ch as DOS com m an d -lin e p rogram s) req u ire little resolu tion , wh ereas grap h ics-in ten sive ap p lication s (su ch as d esktop p u blish in g an d W in d ows software) req u ire a great d eal.

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As PC vid eo tech n ology d evelop ed , th e screen resolu tion s su p p orted by vid eo ad ap ters grew at a stead y p ace. Th e followin g table lists som e stan d ard resolu tion s u sed in PC vid eo ad ap ters an d th e term s th at were u sed to com m on ly d escribe th em : Resolut ion

Acronym

St andard Designat ion

640×480

VGA

Video Graphics Array

800×600

SVGA

Super VGA

1,024 ×768

XGA

eXtended Graphics Array

1,280 ×1,024

UVGA

Ultra VGA

Tod ay, th e term VGA is still in com m on u sage as a referen ce to th e stan d ard 640×480 16-color d isp lay th at th e W in d ows op eratin g system s u se as th eir d efau lt. Th e 15-p in con n ector to wh ich you con n ect th e m on itor on m ost vid eo ad ap ters is also often called a VGA p lu g. However, th e term s SVGA, XGA, an d UVGA h ave fallen in to d isu se. Th e in d u stry n ow d escribes screen resolu tion s sim p ly by citin g th e n u m ber of p ixels. Nearly all th e vid eo ad ap ters sold tod ay su p p ort th e 640×480, 800×600, an d 1,024×768 p ixel resolu tion s at several color d ep th s, an d m an y su p p ort 1,280×1,024 an d h igh er as well. Dot Pit ch An oth er im p ortan t sp ecification th at d en otes th e q u ality of a given m on itor is its d ot p itch . In a m on och rom e m on itor, th e p ictu re elem en t is a screen p h osp h or, bu t in a color m on itor, th e p ictu re elem en t is a p h osp h or triad . Dot p itch , wh ich ap p lies on ly to color m on itors, is th e d istan ce (in m illim eters) between p h osp h or triad s. Screen s with a sm all d ot p itch h ave a sm aller sp ace between th e p h osp h or triad s. As a resu lt, th e p ictu re elem en ts are closer togeth er, p rod u cin g a sh arp er p ictu re on th e screen . Con versely, screen s with a large d ot p itch ten d to p rod u ce im ages th at are less clear. Th e origin al IBM PC color m on itor h ad a d ot p itch of 0.43m m , wh ich is con sid ered to be p oor by alm ost an y stan d ard . Th e state-of-th e-art m on itors m arketed tod ay h ave a d ot p itch of 0.25m m or less; I wou ld n ot recom m en d bu yin g a m on itor with a d ot p itch of m ore th an 0.28m m in m ost cases. Alth ou gh you can save m on ey by p ickin g a sm aller m on itor or on e with a h igh er d ot p itch , th e trad e off is n ot u su ally worth it. Int erlaced Versus Nonint erlaced Mon itors an d vid eo ad ap ters m ay su p p ort in terlaced or n on in terlaced resolu tion . In noninterlaced (con ven tion al) m od e, th e electron beam sweep s th e screen in lin es from top to bottom , on e lin e after th e oth er, com p letin g th e screen in on e p ass. In interlaced m od e, th e electron beam also sweep s th e screen from top to bottom , bu t it d oes so in two p asses—sweep in g th e od d lin es first an d th e even lin es secon d . Each p ass takes h alf th e tim e of a fu ll p ass in n on in terlaced m od e. Th erefore, both m od es refresh th e en tire screen in th e sam e am ou n t of tim e. Th is tech n iq u e red raws th e screen faster an d p rovid es m ore stable im ages, bu t also p rod u ces wh at is often a very n oticeable flicker. If you switch you r vid eo ad ap ter to a h igh er screen resolu tion , an d you fin d th at you r solid , satisfactory p ictu re su d d en ly seem s

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flickery, you h ave p robably switch ed to a resolu tion th at you r h ard ware on ly su p p orts in in terlaced m od e. Differen t u sers react to in terlaced d isp lays d ifferen tly. To som e p eop le, it is h ard ly n oticeable, wh ile to oth ers, lookin g at th e screen is u n bearable.

Caut ion It’s not unheard of for people with neurological disorders such as epilepsy to be profoundly affected by the flicker produced by monitors running in interlaced mode or at low refresh rates. These people should take adequate precautions before adjusting their video display setting and, if possible, be aware of their physical limitations.

Mon itors th at u se in terlacin g can u se lower refresh rates, th u s lessen in g th eir cost. Th e d rawback is th at in terlacin g d ep en d s on th e ability of th e eye to com bin e two n early id en tical lin es, sep arated by a gap , in to on e solid lin e. If you are lookin g for h igh -q u ality vid eo, h owever, you sh ou ld avoid in terlacin g at all costs an d get a vid eo ad ap ter an d m on itor th at su p p ort h igh -resolu tion , n on in terlaced d isp lays. Energy and Safet y A p rop erly selected m on itor can save en ergy. Man y PC m an u factu rers are tryin g to m eet th e En viron m en tal Protection Agen cy’s En ergy Star req u irem en ts. An y PC-an d -m on itor com bin ation th at con su m es less th an 60 watts (30 watts ap iece) d u rin g id le p eriod s can u se th e En ergy Star logo. Som e research sh ows th at su ch “green ” PCs can save each u ser abou t $70 p er year in electricity costs. Pow er M anagem ent . Mon itors, bein g on e of th e m ost p ower-h u n gry com p u ter com p on en ts, can con tribu te to th ose savin gs. On e of th e first en ergy-savin g stan d ard s for m on itors was VESA’s Disp lay Power-Man agem en t Sign alin g (DPMS) sp ec, wh ich d efin es th e sign als th at a com p u ter sen d s to a m on itor to in d icate id le tim es. Th e com p u ter or vid eo card d ecid es wh en to sen d th ese sign als. Sin ce th en , In tel an d Microsoft h ave join tly d evelop ed th e Ad van ced Power Man agem en t (APM) sp ecification , wh ich d efin es a BIOS-based in terface between h ard ware th at is cap able of p ower m an agem en t fu n ction s an d an op eratin g system th at im p lem en ts p ower m an agem en t p olicies. In sh ort, th is m ean s th at you can con figu re an OS su ch as W in d ows 9x to switch you r m on itor in to a low-p ower m od e after an in terval of n on u se, an d even to sh u t it off en tirely. For th ese action s to occu r, h owever, th e m on itor, th e system BIOS, an d th e op eratin g system m u st all su p p ort th e APM stan d ard . For d isp lays, p ower m an agem en t is im p lem en ted wh en DPMS sign als th e m on itor to en ter in to th e variou s APM m od es. Th e basis of th e DPMS stan d ard is th e con d ition of th e syn ch ron ization sign als bein g sen t to th e d isp lay. By alterin g th ese sign als, a DPMScom p atible m on itor can be forced in to th e variou s APM m od es by an op eratin g system th at su p p orts th e p ower m an agem en t stan d ard . You can con figu re th e m on itor to en ter th e stan d -by an d su sp en d m od es at p red efin ed in tervals wh en th e com p u ter is n ot in u se, an d even sh ift back to th e on m od e wh en certain even ts occu r, su ch as wh en a m od em p h on e lin e rin gs.

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Th e d efin ed m on itor states in DPMS are as follows: ■ On. Refers to th e state of th e d isp lay wh en it is in fu ll op eration . ■ Stand-By. Defin es an op tion al op eratin g state of m in im al p ower red u ction with th e sh ortest recovery tim e. ■ Suspend. Refers to a level of p ower m an agem en t in wh ich su bstan tial p ower red u ction is ach ieved by th e d isp lay. Th e d isp lay can h ave a lon ger recovery tim e from th is state th an from th e Stan d -By state. ■ Off. In d icates th at th e d isp lay is con su m in g th e lowest level of p ower an d is n on op eration al. Recovery from th is state m ay op tion ally req u ire th e u ser to m an u ally p ower on th e m on itor. Table 8.1 su m m arizes th e DPMS m od es. Table 8.1

Display Pow er M anagem ent Signaling

St at e

Horizont al

Vert ical

Video

Pow er Savings Recovery Tim e

On

Pulses

Pulses

Active

None

Not Applicable

Stand-By

No Pulses

Pulses

Blanked

M inimal

Short

Suspend

Pulses

No Pulses

Blanked

Substantial

Longer

Off

No Pulses

No Pulses

Blanked

M aximum

System Dependent

Em issions. An oth er tren d in green m on itor d esign is to m in im ize th e u ser’s exp osu re to p oten tially h arm fu l electrom agn etic field s. Several m ed ical stu d ies in d icate th at th ese electrom agn etic em ission s m ay cau se h ealth p roblem s, su ch as m iscarriages, birth d efects, an d can cer. Th e risk m ay be low, bu t if you sp en d a th ird of you r d ay (or m ore) in fron t of a com p u ter m on itor, th at risk is in creased . Th e con cern is th at VLF (very low freq u en cy) an d ELF (extrem ely low freq u en cy) em ission s m igh t affect th e bod y. Th ese two em ission s com e in two form s—electric an d m agnetic. Som e research in d icates th at ELF m agn etic em ission s are m ore th reaten in g th an VLF em ission s, becau se th ey in teract with th e n atu ral electric activity of bod y cells. Mon itors are n ot th e on ly cu lp rits; sign ifican t ELF em ission s also com e from electric blan kets an d p ower lin es.

Not e ELF and VLF are a form of electromagnetic radiation; they consist of radio frequencies below those used for normal radio broadcasting.

Th ese two freq u en cies are covered by th e n ew Swed ish m on itor-em ission stan d ard called SW EDAC, n am ed after th e Swed ish regu latory agen cy. In m an y Eu rop ean cou n tries, govern m en t agen cies an d bu sin esses bu y on ly low-em ission m on itors. Th e d egree to wh ich em ission s are red u ced varies from m on itor to m on itor. Th e Swed ish govern m en t’s MPR I stan d ard , wh ich d ates back to 1987, is th e least restrictive. MPR II, establish ed in

M onitors

1990, is sign ifican tly stron ger (ad d in g m axim u m s for ELF an d VLF em ission s) an d is th e level th at you will m ost likely fin d in low-em ission m on itors tod ay. A m ore strin gen t 1992 stan d ard called TCO fu rth er tigh ten s th e MPR II req u irem en ts. In ad d ition , it is a m ore broad -based en viron m en tal stan d ard th at in clu d es p ower-savin g req u irem en ts an d em ission lim its. Most of th e m ajor m an u factu rers cu rren tly offer m on itors th at m eet th e TCO stan d ard . A low-em ission m on itor costs abou t $20 to $100 m ore th an sim ilar regu lar-em ission m on itors. W h en you sh op for a low-em ission m on itor, d on ’t ju st ask for a low-em ission m on itor; also fin d ou t wh eth er th e m on itor lim its sp ecific typ es of em ission s. Use as you r gu id elin e th e th ree electrom agn etic-em ission stan d ard s d escribed in th is section . If you d ecid e n ot to bu y a low-em ission m on itor, you can take oth er step s to p rotect you rself. Th e m ost im p ortan t is to stay at arm ’s len gth (abou t 28 in ch es) from th e fron t of you r m on itor. W h en you m ove a cou p le of feet away, ELF m agn etic em ission levels u su ally d rop to th ose of a typ ical office with flu orescen t ligh ts. Likewise, m on itor em ission s are weakest at th e fron t of a m on itor, so stay at least th ree feet from th e sid es an d backs of n earby m on itors an d five feet from an y p h otocop iers, wh ich are also stron g sou rces of ELF. Electrom agn etic em ission s sh ou ld n ot be you r on ly con cern ; you also sh ou ld be con cern ed abou t screen glare. In fact, som e of th e an tiglare p an els th at fit in fron t of a m on itor screen n ot on ly red u ce eyestrain , bu t also cu t ELF an d VLF em ission s. M onit or Buying Crit eria A m on itor m ay accou n t for a large p art of th e p rice of you r com p u ter system . W h at sh ou ld you look for wh en you sh op for a m on itor? Frequencies. On e essen tial trick is to ch oose a m on itor th at works with you r selected vid eo ad ap ter. You can save m on ey by p u rch asin g a sin gle-stan d ard (fixed -freq u en cy) m on itor an d a m atch in g vid eo card ; for exam p le, you can ord er a VGA m on itor an d a VGA vid eo card . For greatest flexibility, h owever, you sh ou ld bu y a m u ltip le-freq u en cy (also called m u ltiscan n in g an d m u ltifreq u en cy) m on itor th at accom m od ates a ran ge of stan d ard s, in clu d in g th ose th at are n ot yet stan d ard ized .

Tip High-quality monitors retain their value longer than most other computer components. Although it’s common for a newer, faster processor to come out right after you have purchased your computer, or to find the same model with a bigger hard disk for the same money, a good quality monitor should outlast your computer. If you purchase a unit with the expectation that your own personal requirements will grow over the years, you may be able to save money on your next system by reusing your old monitor.

W ith m u ltip le-freq u en cy m on itors, you m u st m atch th e ran ge of h orizon tal an d vertical freq u en cies th e m on itor accep ts with th ose gen erated by you r vid eo ad ap ter. Th e wid er th e ran ge of sign als, th e m ore exp en sive—an d m ore versatile—th e m on itor. You r vid eo

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ad ap ter’s vertical an d h orizon tal freq u en cies m u st fall with in th e ran ges su p p orted by you r m on itor. Th e vertical frequency (or refresh / fram e rate) d eterm in es h ow stable you r im age will be. Th e h igh er th e vertical freq u en cy, th e better. Typ ical vertical freq u en cies ran ge from 50Hz to 160Hz, bu t m u ltip le-freq u en cy m on itors su p p ort d ifferen t vertical freq u en cies at d ifferen t resolu tion s. You m ay fin d th at a bargain m on itor h as a resp ectable 100Hz vertical freq u en cy at 640×480, bu t d rop s to a less d esirable 50Hz at 1,024×768. Th e horizontal frequency (or lin e rate) typ ically ran ges from 31.5KHz to 90KHz or m ore. To keep th e freq u en cy low, som e vid eo ad ap ters u se in terlaced sign als, altern ately d isp layin g h alf th e lin es of th e total im age. As d iscu ssed earlier in th is ch ap ter, in terlacin g p rod u ces a p ron ou n ced flicker in th e d isp lay on m ost m on itors, u n less th e p h osp h or is d esign ed with a very lon g p ersisten ce. For th is reason , you sh ou ld avoid u sin g in terlaced vid eo m od es if p ossible. Som e old er ad ap ters an d d isp lays u sed in terlacin g as an in exp en sive way to attain a h igh er resolu tion th an oth erwise wou ld be p ossible. For exam p le, th e origin al IBM XGA ad ap ters an d m on itors u sed an in terlaced vertical fram e rate of 43.5Hz in 1,024×768 m od e, in stead of th e h igh er fram e rate th at m ost oth er ad ap ters an d d isp lays u se at th at resolu tion . In m y exp erien ce, a 60Hz vertical scan freq u en cy (fram e rate) is th e m in im u m an ybod y sh ou ld u se, an d even at th is freq u en cy a flicker will be n oticed by m ost p eop le. Esp ecially on a larger d isp lay, th is can cau se eyestrain an d fatigu e. If you can select a fram e rate (vertical scan freq u en cy) of 72Hz or h igh er, m ost p eop le will n ot be able to d iscern an y flicker. Most m od ern d isp lays easily h an d le vertical freq u en cies of u p to 85Hz or m ore, wh ich greatly red u ces th e flicker seen by th e u ser. However, n ote th at in creasin g th e fram e rate, wh ile im p rovin g th e q u ality of th e im age, can also slow d own th e vid eo h ard ware, becau se it n ow n eed s to d isp lay each im age m ore tim es p er secon d . In gen eral, I recom m en d you set th e lowest fram e rate th at you fin d com fortable. W h en you sh op for a VGA m on itor, m ake su re th e m on itor su p p orts a h orizon tal freq u en cy of at least 31.5KHz—th e m in im u m th at a VGA card n eed s to p ain t a 640×480 screen . Th e 800×600 resolu tion req u ires at least a 72Hz vertical freq u en cy an d a h orizon tal freq u en cy of at least 48KHz. Th e sh arp er 1,024×768 im age req u ires a vertical freq u en cy of 60Hz an d a h orizon tal freq u en cy of 58KHz. If th e vertical freq u en cy in creases to 72Hz, th e h orizon tal freq u en cy m u st be 58KHz. For a su p er-crisp d isp lay, look for available vertical freq u en cies of 75Hz or h igh er an d h orizon tal freq u en cies of u p to 90KHz or m ore. My favorite 17-in ch NEC m on itor su p p orts vertical resolu tion s of u p to 75Hz at 1,600×1,200 p ixels, 117Hz at 1,024×768, an d 160Hz at 640×480! Most of th e an alog m on itors on th e m arket tod ay are, to on e exten t or an oth er, m u ltip le-freq u en cy. Becau se literally h u n d red s of m an u factu rers p rod u ce th ou san d s of m on itor m od els, it is im p ractical to d iscu ss th e tech n ical asp ects of each m on itor m od el in d etail. Su ffice it to say th at before in vestin g in a m on itor, you sh ou ld ch eck th e tech n ical sp ecification s to m ake su re th at th e m on itor m eets you r n eed s. If you are lookin g for a p lace to start, ch eck ou t som e of th e d ifferen t m agazin es, wh ich p eriod ically featu res reviews of m on itors. If you can ’t wait for a m agazin e review, in vestigate m on itors at th e W eb sites ru n by an y of th e followin g ven d ors:

M onitors

IBM

Son y

Mitsu bish i

Viewson ic

NEC Each of th ese m an u factu rers creates m on itors th at set th e stan d ard s by wh ich oth er m on itors can be ju d ged . Alth ou gh you typ ically p ay a bit m ore for th ese m an u factu rers’ m on itors, th ey offer a kn own h igh level of q u ality an d com p atibility, as well as service an d su p p ort. Dot Pit ch. You also sh ou ld ch eck th e d ot p itch of th e m on itor. Th e dot pitch (also called p h osp h or p itch ) is th e d iagon al d istan ce between p h osp h or d ots of th e sam e color, m easu red in m illim eters. Sm aller p itch valu es in d icate sh arp er im ages. Most m on itors h ave a d ot p itch between 0.25 an d 0.30m m . To avoid grain y im ages, look for a d ot p itch of 0.26m m or sm aller. Be wary of m on itors with an yth in g larger th an a 0.28m m d ot p itch ; th ey lack clarity for fin e text an d grap h ics. Th e d ot p itch is on e of th e m ost im p ortan t sp ecification s of an y m on itor, bu t it is n ot th e on ly sp ecification . It is en tirely p ossible th at you m ay fin d th e im age on a m on itor with a sligh tly h igh er d ot p itch su p erior to th at of a m on itor with a lower p itch . Screen Size. W h at resolu tion d o you wan t for you r d isp lay? Gen erally, th e h igh er th e resolu tion , th e larger th e d isp lay you will wan t. If you are op eratin g at 640×480 resolu tion , for exam p le, you sh ou ld fin d a 14- or 15-in ch m on itor to be com fortable. At 1,024×768, you p robably will fin d th at th e d isp lay of a 15-in ch m on itor is too sm all an d will th erefore p refer to u se a larger on e, su ch as a 17-in ch m on itor. Here are th e m in im u m sized m on itors I recom m en d to p rop erly d isp lay th e resolu tion s th at u sers typ ically select: Resolut ion

M inim um Recom m ended M onit or

640×480

13-inch

800×600

15-inch

1,024 ×768

17-inch

1,280 ×1,024

21-inch

Th ese m in im u m recom m en d ed d isp lay sizes are th e ad vertised d iagon al d isp lay d im en sion of th e m on itor. Note th at th ese are n ot n ecessarily th e lim its of th e given m on itors’ cap abilities, bu t are wh at I recom m en d . In oth er word s, m ost 15-in ch m on itors are able to d isp lay resolu tion s at least u p to 1,024×768, bu t th e ch aracters, icon s, an d oth er in form ation are too sm all for m ost u sers an d can cau se eyestrain if you try to ru n beyon d th e recom m en d ed 800×600 resolu tion . On e excep tion to th is ru le is with th e LCD d isp lays u sed in p ortable system s an d a few d esktop m on itors. LCD-typ e d isp lays are always crisp an d p erfectly focu sed by n atu re. Also, th e d im en sion s ad vertised for th e LCD screen s rep resen t th e exact size of th e viewable im age, u n like m ost con ven tion al CRT-based m on itors. So, th e 12.1-in ch LCD p an els fou n d on m an y n otebook system s tod ay actu ally h ave a viewable area with a 12.1-in ch d iagon al m easu rem en t. Th is m easu rem en t is

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com p arable to a 14-in ch or even 15-in ch CRT d isp lay in m ost cases. Not on ly th at, bu t th e LCD is so crisp th at screen s of a given size can easily h an d le resolu tion s th at are h igh er th an oth erwise wou ld be accep table on a CRT. For exam p le, m an y of th e h igh en d n otebook system s n ow u se 13.3-in ch LCD p an els th at featu re 1,024×768 resolu tion . Alth ou gh th is resolu tion wou ld be u n accep table on a 14-in ch or 15-in ch CRT d isp lay, it works well on th e 13.3-in ch LCD p an el d u e to th e crystal clear im age. Cont rols. Most of th e n ewer m on itors n ow u se d igital con trols in stead of an alog con trols. Th is h as n oth in g to d o with th e sign als th at th e m on itor receives from th e com p u ter, bu t on ly th e con trols (or lack of th em ) on th e fron t p an el th at en able you to ad ju st th e d isp lay. Mon itors with d igital con trols h ave a bu ilt-in m en u system th at allows you to set p aram eters su ch as brigh tn ess, con trast, screen size, vertical an d h orizon tal sh ifts, an d even focu s. Th e m en u is brou gh t u p on th e screen by a bu tton , an d you u se con trols to m ake m en u selection s an d vary th e settin gs. W h en you com p lete you r ad ju stm en ts, th e m on itor saves th e settin gs in NVRAM (Non volatile RAM) located in sid e th e m on itor. Th is typ e of m em ory p rovid es p erm an en t storage for th e settin gs with n o battery or oth er p ower sou rce. You can u n p lu g th e m on itor with ou t losin g you r settin gs, an d alter th em at an y tim e in th e fu tu re. Digital con trols p rovid e a m u ch h igh er level of con trol over th e m on itor, an d are h igh ly recom m en d ed .

Tip Get a monitor with positioning and image controls that are easy to reach, preferably on the front of the case. Look for more than just basic contrast and brightness controls; a good monitor should enable you to adjust the width and height of your screen images, and the placement of the image on the screen. The monitor should also be equipped with a tilt-swivel stand, so you can adjust the monitor to the best angle for your use.

Environm ent . On e factor th at you m ay n ot con sid er wh en sh op p in g for a m on itor is th e size of th e d esk th at you in ten d to p u t it on . Before you th in k abou t p u rch asin g a m on itor larger th an 15 in ch es, be aware th at a 17-in ch m on itor can be 18 in ch es to two feet d eep an d weigh u p ward s of 40 p ou n d s; 21-in ch an d larger m on itors can be tru ly h u ge! Som e of th e rickety com p u ter stan d s an d m ech an ical arm s u sed to keep m on itors off th e d esktop m ay n ot be able to safely h old or su p p ort a large u n it. An oth er im p ortan t con sid eration is th e ligh tin g in th e room wh ere you will u se th e m on itor. Th e ap p earan ce of a CRT d isp lay in th e flu orescen t ligh tin g of an office will be m arked ly d ifferen t from th at in you r h om e. Th e p resen ce or absen ce of su n ligh t in th e room also m akes a big d ifferen ce. Office ligh tin g an d su n ligh t can p rod u ce glare th at becom es in cred ibly an n oyin g wh en you are forced to stare at it for h ou rs on en d . Som e m on itors are eq u ip p ed with an an ti-glare coatin g th at can h elp in th ese in stan ces. Man y m an u factu rers an d th ird -p arty ven d ors also p rod u ce afterm arket filters d esign ed to red u ce glare. Man y in exp en sive m on itors are cu rved becau se it is easier to sen d an electron beam across th em . Flat-screen m on itors, wh ich are a bit m ore exp en sive, look better to m ost p eop le. As a gen eral ru le, th e less cu rvatu re a m on itor h as, th e less glare it will reflect.

Video Display Adapters

Test ing. Un like m ost of th e oth er com p on en ts of you r com p u ter, you can ’t really tell wh eth er a m on itor will su it you by exam in in g its tech n ical sp ecification s. Price m ay n ot be a reliable in d icator eith er. Testin g m on itors is a h igh ly su bjective p rocess, an d it is best to “kick th e tires” of a few at a d ealer sh owroom or (with a liberal retu rn p olicy) in th e p rivacy of you r h om e or office. Testin g sh ou ld also n ot be sim p ly a m atter of lookin g at wh atever h ap p en s to be d isp layed on th e m on itor at th e tim e. Man y com p u ter stores d isp lay m ovies, scen ic p h otos, or oth er flash y grap h ics th at are all bu t u seless for a seriou s evalu ation an d com p arison . If p ossible, you sh ou ld look at th e sam e im ages on each m on itor you try, an d com p are th e m an n er in wh ich th ey p erform a sp ecific series of tasks. On e good series of tasks is as follows: ■ Draw a p erfect circle with a grap h ics p rogram . If th e d isp layed resu lt is an oval, n ot a circle, th is m on itor will n ot serve you well with grap h ics or d esign software. ■ Usin g a word p rocessor, typ e som e word s in 8- or 10-p oin t typ e (1 p oin t eq u als 1/ 72 in ch ). If th e word s are fu zzy, or if th e black ch aracters are frin ged with color, select an oth er m on itor. ■ Tu rn th e brigh tn ess u p an d d own wh ile exam in in g th e corn er of th e screen ’s im age. If th e im age bloom s or swells, it is likely to lose focu s at h igh brigh tn ess levels. ■ Disp lay a screen with as m u ch wh ite sp ace as p ossible an d look for areas of color varian ce. Th is m ay in d icate a p roblem on ly with th at in d ivid u al u n it or its location , bu t if you see it on m ore th an on e m on itor of th e sam e m ake, it m ay be in d icative of a m an u factu rin g p roblem . ■ Load Microsoft W in d ows to ch eck for u n iform focu s. Are th e corn er icon s as sh arp as th e rest of th e screen ? Are th e lin es in th e title bar cu rved or wavy? Mon itors u su ally are sh arp ly focu sed at th e cen ter, bu t seriou sly blu rred corn ers in d icate a p oor d esign . Bowed lin es m ay be th e resu lt of a p oor vid eo ad ap ter, so d on ’t d ism iss a m on itor th at sh ows th ose lin es with ou t u sin g an oth er ad ap ter to d ou blech eck th e effect. ■ A good m on itor will be calibrated so th at rays of red , green , an d blu e ligh t h it th eir targets (in d ivid u al p h osp h or d ots) p recisely. If th ey d on ’t, you h ave bad con vergen ce. Th is is ap p aren t wh en ed ges of lin es ap p ear to illu m in ate with a sp ecific color. If you h ave good con vergen ce, th e colors will be crisp , clear, an d tru e, p rovid ed th ere isn ’t a p red om in an t tin t in th e p h osp h or.

Video Display Adapt ers A video adapter p rovid es th e in terface between you r com p u ter an d you r m on itor an d tran sm its th e sign als th at ap p ear as im ages on th e d isp lay. Th rou gh ou t th e h istory of th e PC, th ere h ave been a su ccession of stan d ard s for vid eo d isp lay ch aracteristics th at rep resen t a stead y in crease in screen resolu tion an d color d ep th . Th e followin g list of stan d ard s can serve as an abbreviated h istory of PC vid eo d isp lay tech n ology:

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MDA (Mon och rom e Disp lay Ad ap ter) CGA (Color Grap h ics Ad ap ter) EGA (En h an ced Grap h ics Ad ap ter) VGA (Vid eo Grap h ics Array) SVGA (Su p er VGA) XGA (eXten d ed Grap h ics Array) Most of th ese stan d ard s were p ion eered by IBM, bu t were also ad op ted by th e m an u factu rers of com p atible PCs as well. Tod ay, IBM is n o lon ger th e in d u stry lead er th at it on ce was, an d m an y of th ese stan d ard s are obsolete. Th ose th at aren ’t obsolete are seld om referred to by th ese n am es an ym ore. Th e sole excep tion to th is is VGA, wh ich is a term th at is still u sed to refer to a baselin e grap h ic d isp lay cap ability su p p orted by virtu ally every vid eo ad ap ter on th e m arket tod ay. W h en you sh op for a vid eo ad ap ter tod ay, you are m ore likely to see sp ecific referen ces to th e screen resolu tion s an d color d ep th s th at th e d evice su p p orts th an a list of stan d ard s su ch as VGA, SVGA, an d XGA. However, read in g abou t th ese stan d ard s gives you a good id ea of h ow vid eo d isp lay tech n ology d evelop ed over th e years, an d p rep ares you for an y close en cou n ters you m ay h ave with legacy eq u ip m en t from th e d ark ages. Obsolet e Display Adapt ers Alth ou gh m an y typ es of d isp lay system s were at on e tim e con sid ered to be in d u stry stan d ard s, few of th ese are viable stan d ard s for tod ay’s h ard ware an d software. For exam p le, th e CGA stan d ard works, bu t it is u n accep table for ru n n in g th e grap h ics-in ten sive p rogram s on wh ich m an y u sers n ow rely. In fact, Microsoft W in d ows 3.1 d oes n ot work with an y PC th at h as less-th an -EGA resolu tion , an d W in d ows 9x an d W in d ows NT req u ire VGA as an absolu te m in im u m . Th e n ext several section s d iscu ss th e d isp lay ad ap ters th at are viewed as bein g obsolete in tod ay’s m arket, alth ou gh you m ay still fin d th em in u se in som e p laces. M onochrom e Display Adapt er ( M DA) and Display. Th e sim p lest (an d first available) d isp lay typ e was th e IBM Monochrom e Display Adapter (MDA). It was in trod u ced alon g with th e IBM PC in 1981. Th e MDA vid eo card d isp layed text on ly at a 720×350 resolu tion . On e in terestin g p oin t is th at th e MDA card also in corp orated a p rin ter p ort an d was th e first m u lti-fu n ction ad ap ter card available. As a ch aracter-on ly system , th e MDA d isp lay h ad n o in h eren t grap h ics cap abilities. Th e d isp lay origin ally was a top -sellin g op tion becau se it was fairly cost-effective. As a bon u s, th e MDA p rovid ed a p rin ter in terface, th u s con servin g an exp an sion slot. For its tim e, th e MDA d isp lay was kn own for clarity an d h igh resolu tion , m akin g it id eal for bu sin ess u se—esp ecially for bu sin esses u sin g DOS-based word p rocessin g or sp read sh eet p rogram s. Becau se th e m on och rom e d isp lay is a ch aracter-on ly d isp lay, you can n ot u se it with software th at req u ires grap h ics. Origin ally, th at d rawback kep t u sers on ly from p layin g

Video Display Adapters

gam es on a m on och rom e d isp lay, bu t tod ay even th e m ost seriou s bu sin ess software u ses grap h ics an d color to great ad van tage. W ith th e 9×14 d ot ch aracter box (m atrix), th e IBM m on och rom e m on itor d isp lays attractive ch aracters. Later, a com p an y n am ed Hercu les released a vid eo card called th e Hercules Graphics Card (HGC). Th is card cou ld d isp lay sh arp er text an d h an d le grap h ics, su ch as th e ch arts p rod u ced by sp read sh eet ap p lication s. Color Graphics Adapt er ( CGA) and Display. Th e Color Graphics Adapter (CGA) was in trod u ced alon g with th e IBM PC in 1981 an d for m an y years was th e m ost com m on ly u sed vid eo ad ap ter. Of cou rse, by tod ay’s stan d ard s, its cap abilities leave m u ch to be d esired . Th e CGA ad ap ter h as two basic m od es of op eration : alp h an u m eric (A/ N) or all p oin ts ad d ressable (APA). In A/N m ode, th e card op erates in 40-colu m n by 25-lin e m od e or 80-colu m n by 25-lin e m od e with 16 colors. In APA an d A/ N m od es, th e ch aracter set is form ed with a resolu tion of 8×8 p ixels. In APA m od e, two resolu tion s are available: m ed iu m -resolu tion color m od e (320×200), with fou r colors available from a p alette of 16; an d two-color h igh -resolu tion m od e (640×200). Most of th e m on itors sold for u se with th e CGA ad ap ter were RGBs, n ot com p osite m on itors. Th e color sign al of a com p osite m on itor con tain s a m ixtu re of colors th at m u st be d ecod ed or sep arated . RGB m on itors receive red , green , an d blu e sep arately, an d com bin e th e colors in d ifferen t p rop ortion s to gen erate oth er colors. RGB m on itors offer better resolu tion th an com p osite m on itors, an d th ey d o a m u ch better job of d isp layin g 80colu m n text. On e severe d rawback of th e CGA vid eo ad ap ter was th e fact th at it was p ron e to p rod u cin g flicker an d sn ow. Flicker is th e an n oyin g ten d en cy of th e text to flash as you m ove th e im age u p or d own . Snow is th e flu rry of brigh t d ots th at can ap p ear an ywh ere on th e screen . Most com p an ies th at sold CGA-typ e ad ap ters h ave lon g sin ce d iscon tin u ed th ose p rod u cts. W ith VGA ad ap ters available for less th an $100, recom m en d in g a CGA m akes little sen se, even if you cou ld fin d on e. Enhanced Graphics Adapt er ( EGA) and Display. Th e IBM En h an ced Grap h ics Ad ap ter was in trod u ced in 1984, ju st after th e IBM AT system . It was d iscon tin u ed wh en th e PS/ 2 system s were in trod u ced in Ap ril 1987. Th e EGA p ackage con sisted of a grap h ics board , a grap h ics m em ory-exp an sion board , a grap h ics m em ory-m od u le kit, an d a h igh resolu tion color m on itor. Th e wh ole p ackage origin ally cost abou t $1,800! Th e afterm arket gave IBM a great d eal of com p etition in th is area; it was p ossible to p u t togeth er a sim ilar system from n on -IBM ven d ors for m u ch less m on ey. On e ad van tage of EGA, h owever, was th at you cou ld bu ild you r system in m od u lar step s. Becau se th e card worked with an y of th e m on itors IBM p rod u ced at th e tim e, you cou ld u se it with th e IBM Mon och rom e Disp lay, th e earlier IBM Color Disp lay, or th e IBM En h an ced Color Disp lay. W ith th e EGA ad ap ter, th e IBM color m on itor d isp lays 16 colors in 320×200 or 640×200 m od e, an d th e IBM m on och rom e m on itor sh ows a resolu tion of 640×350 with a 9×14 ch aracter box (text m od e).

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W ith th e EGA ad ap ter, th e IBM En h an ced Color Disp lay is cap able of d isp layin g 640×350 p ixels in 16 colors from a p alette of 64. Th e ch aracter box for text is 8×14, com p ared with 8×8 for th e earlier CGA board an d m on itor. Th e 8×8 ch aracter box can be u sed , h owever, to d isp lay 43 lin es of text. Th rou gh software, th e ch aracter box can be m an ip u lated u p to th e size of 8×32. You can en large th e RAM-resid en t, 256-m em ber ch aracter set to 512 ch aracters by u sin g th e IBM m em ory exp an sion card , an d ad d a 1,024-ch aracter set by in stallin g th e IBM grap h ics m em ory-m od u le kit. Th ese ch aracter sets are load ed from p rogram s. All of th is m em ory fits in th e u n u sed sp ace between th e en d of th e RAM u ser m em ory an d th e cu rren t d isp lay-ad ap ter m em ory. Th e EGA h as a m axim u m 128K of m em ory th at m ap s in to th e RAM sp ace ju st above th e 640K bou n d ary. If you in stall m ore th an 640K, you will p robably lose th e extra m em ory after in stallin g th e EGA. Th e grap h ics m em oryexp an sion card ad d s 64K to th e stan d ard 64K, for a total of 128K. Th e IBM grap h ics m em ory-m od u le kit ad d s an oth er 128K, for a total of 256K. Th is secon d 128K of m em ory is on ly on th e card an d d oes n ot con su m e an y of th e PC’s m em ory sp ace. (Becau se alm ost every afterm arket EGA card com es con figu red with th e fu ll 256K of m em ory, exp an sion op tion s are n ot n ecessary.) Th e VGA system su p ersed es th e EGA in m an y resp ects. Th e EGA h as p roblem s em u latin g th e earlier CGA or MDA ad ap ters, an d som e software th at works with th e earlier card s will n ot ru n on th e EGA u n til th e p rogram s are m od ified . Professional Color Display and Adapt er. Th e Profession al Grap h ics Disp lay System is a vid eo d isp lay p rod u ct th at IBM in trod u ced in 1984. At $4,290, th e system was too exp en sive to becom e a m ain stream p rod u ct an d n ever ach ieved an y sign ifican t p op u larity. It was th e first p rocessor-based vid eo ad ap ter for PCs; it actu ally in corp orated an In tel 8088 p rocessor on th e card . Th e system con sisted of a Profession al Grap h ics Mon itor an d a Profession al Grap h ics Card Set. W h en fu lly exp an d ed , th e card set u sed th ree slots in an XT or AT system —a h igh p rice to p ay, bu t th e featu res were im p ressive. Th e Profession al Grap h ics Ad ap ter (PGA) offered th ree-d im en sion al rotation an d clip p in g as a bu ilt-in h ard ware fu n ction . Th e ad ap ter cou ld ru n 60 fram es of an im ation p er secon d becau se th e PGA u sed a bu iltin d ed icated m icrocom p u ter. Th e Profession al Grap h ics card an d m on itor was in ten d ed for en gin eerin g an d scien tific u se rath er th an for fin an cial or bu sin ess ap p lication s. Th e VGA an d oth er h igh erresolu tion grap h ics stan d ard s d esign ed for th ese n ewer system s rep laced th is system , wh ich was d iscon tin u ed wh en th e PS/ 2 was in trod u ced . 8514 Display Adapt er. Th e PS/ 2 Disp lay Ad ap ter 8514/ A, in trod u ced in 1987 alon g with th e PS/ 2 system s, offered h igh er resolu tion an d m ore colors th an th e stan d ard VGA. Th is ad ap ter, d esign ed for u se with th e PS/ 2 Color Disp lay 8514, p lu gs in to a Micro Ch an n el slot in an y PS/ 2 m od el so eq u ip p ed .

Video Display Adapters

W ith th e 8514/ A in stalled , all op eration al m od es of th e PS/ 2’s bu ilt-in VGA con tin u e to be available. An IBM 8514 m em ory-exp an sion kit was also available for th e 8514/ A, p rovid in g in creased color an d grayscale su p p ort. To take fu ll ad van tage of th e 8514/ A ad ap ter, you h ad to u se th e 8514 d isp lay becau se it was m atch ed to th e cap abilities of th e ad ap ter. Note th at IBM h as lon g sin ce d iscon tin u ed th e 8514/ A ad ap ter, an d sp ecified th e XGA in its p lace. M ult iColor Graphics Array ( M CGA) . Th e MultiColor Graphics Array (MCGA) grap h ics ad ap ter was in tegrated in to th e m oth erboard of th e PS/ 2 Mod els 25 an d 30. Th e MCGA su p p orted all CGA m od es wh en an IBM an alog d isp lay was attach ed , bu t an y p reviou s IBM d isp lay was n ot com p atible. In ad d ition to p rovid in g existin g CGA m od e su p p ort, th e MCGA in clu d ed fou r ad d ition al m od es. Th e MCGA u sed as m an y as 64 sh ad es of gray in con vertin g color m od es for d isp lay on m on och rom e m on itors, so u sers wh o p referred a m on och rom e d isp lay cou ld execu te color-based ap p lication s. VGA Adapt ers and Displays W h en IBM in trod u ced th e PS/ 2 system s on Ap ril 2, 1987, it also in trod u ced th e Vid eo Grap h ics Array (VGA) d isp lay. On th at d ay, in fact, IBM also in trod u ced th e lowerresolu tion Mu ltiColor Grap h ics Array (MCGA) an d h igh er-resolu tion 8514 ad ap ters. Th e MCGA an d 8514 ad ap ters d id n ot becom e p op u lar stan d ard s like th e VGA, an d both were d iscon tin u ed . Digit al Versus Analog Signals. Un like earlier vid eo stan d ard s, wh ich are d igital, th e VGA is an an alog system . W h y are d isp lays goin g from d igital to an alog wh en m ost oth er electron ic system s are goin g d igital? Com p act-d isc p layers (d igital) h ave rep laced m ost tu rn tables (an alog), an d n ewer VCRs an d cam cord ers h ave d igital p ictu re storage for sm ooth slow-m otion an d freeze-fram e cap ability. W ith a d igital television set, you can watch several ch an n els on a sin gle screen by sp littin g th e screen or p lacin g a p ictu re with in an oth er p ictu re. Most p erson al com p u ter d isp lays in trod u ced before th e PS/ 2 are d igital. Th is typ e of d isp lay gen erates d ifferen t colors by firin g th e RGB electron beam s in on -or-off m od e, wh ich allows for th e d isp lay of u p to eigh t colors (2 to th e th ird p ower). In th e IBM d isp lays an d ad ap ters, an oth er sign al d ou bles th e n u m ber of color com bin ation s from 8 to 16 by d isp layin g each color at on e of two in ten sity levels. Th is d igital d isp lay is easy to m an u factu re an d offers sim p licity with con sisten t color com bin ation s from system to system . Th e real d rawback of th e d igital d isp lay system is th e lim ited n u m ber of p ossible colors. In th e PS/ 2 system s, IBM wen t to an an alog d isp lay circu it. An alog d isp lays work like th e d igital d isp lays th at u se RGB electron beam s to con stru ct variou s colors, bu t each color in th e an alog d isp lay system can be d isp layed at varyin g levels of in ten sity—64 levels, in th e case of th e VGA. Th is versatility p rovid es 262,144 p ossible colors (64 3 ). For realistic com p u ter grap h ics, color d ep th is often m ore im p ortan t th an h igh resolu tion , becau se th e h u m an eye p erceives a p ictu re th at h as m ore colors as bein g m ore realistic. IBM m oved to an alog grap h ics to en h an ce th e color cap abilities of th eir system s.

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Video Graphics Array ( VGA) . PS/ 2 system s in corp orate th e p rim ary d isp lay ad ap ter circu itry on to th e m oth erboard . A sin gle cu stom VLSI ch ip d esign ed an d m an u factu red by IBM im p lem en ts th e circu its, or VGA. To ad ap t th is n ew grap h ics stan d ard to th e earlier system s, IBM in trod u ced th e PS/ 2 Disp lay Ad ap ter. Also called a VGA card , th is ad ap ter con tain s th e com p lete VGA circu it on a fu ll-len gth ad ap ter board with an 8-bit in terface. IBM h as sin ce d iscon tin u ed its VGA card , bu t m an y th ird -p arty u n its are available. Th e VGA BIOS (Basic Input/Output System ) is th e con trol software resid in g in th e system ROM for con trollin g VGA circu its. W ith th e BIOS, software can in itiate com m an d s an d fu n ction s with ou t h avin g to m an ip u late th e VGA d irectly. Program s becom e som ewh at h ard ware-in d ep en d en t an d can call a con sisten t set of com m an d s an d fu n ction s bu ilt in to th e system ’s ROM-con trol software. √√ See “ Video Adapter BIOS,” p. 369

Oth er im p lem en tation s of th e VGA d iffer in th eir h ard ware bu t resp on d to th e sam e BIOS calls an d fu n ction s. New featu res are ad d ed as a su p erset of th e existin g fu n ction s, an d VGA rem ain s com p atible with th e grap h ics an d text BIOS fu n ction s bu ilt in to th e PC system s from th e begin n in g. Th e VGA can ru n alm ost an y software th at origin ally was written for th e MDA, CGA, or EGA. In a p erfect world , software p rogram m ers wou ld write to th e BIOS in terface rath er th an d irectly to th e h ard ware an d wou ld p rom ote software in terch an ges between d ifferen t typ es of h ard ware. More freq u en tly, h owever, p rogram m ers wan t th e software to p erform better, so th ey write th e p rogram s to con trol th e h ard ware d irectly. As a resu lt, th ese p rogram m ers ach ieve h igh er-p erform an ce ap p lication s th at are d ep en d en t on th e h ard ware for wh ich th ey were first written . W h en byp assin g th e BIOS, a p rogram m er m u st en su re th at th e h ard ware is 100% com p atible with th e stan d ard so th at software written to a stan d ard p iece of h ard ware ru n s on th e system . Ju st becau se a m an u factu rer claim s th is register level of com p atibility d oes n ot m ean th at th e p rod u ct is 100% com p atible or th at all software ru n s as it wou ld on a tru e IBM VGA. Most m an u factu rers h ave “clon ed ” th e VGA system at th e register level, wh ich m ean s th at even ap p lication s th at write d irectly to th e vid eo registers will fu n ction correctly. Also, th e VGA circu its th em selves em u late th e old er ad ap ters even to th e register level an d h ave an am azin g level of com p atibility with th ese earlier stan d ard s. Th is com p atibility m akes th e VGA a tru ly u n iversal stan d ard . Th e VGA d isp lays u p to 256 colors on screen , from a p alette of 262,144 (256K) colors. Becau se th e VGA ou tp u ts an an alog sign al, you m u st h ave a m on itor th at accep ts an an alog in p u t. VGA d isp lays com e n ot on ly in color bu t also in m on och rom e VGA m od els, u sin g color su m m in g. W ith color sum m ing, 64 gray sh ad es are d isp layed in stead of colors; th e tran slation is p erform ed in th e ROM BIOS. Th e su m m in g rou tin e is in itiated if th e BIOS d etects

Video Display Adapters

a m on och rom e d isp lay wh en th e system boots. Th is rou tin e u ses an algorith m th at takes th e d esired color an d rewrites th e form u la to in volve all th ree color gu n s, p rod u cin g varyin g in ten sities of gray. Users wh o p refer a m on och rom e d isp lay, th erefore, can execu te color-based ap p lication s. Table 8.2 lists th e VGA d isp lay m od es. Table 8.2 Resolut ion

VGA Display M odes M ode BIOS Charact er Charact er Vert ical Colors Type M ode Form at Box ( Hz)

Horizont al ( KHz)

360×400

16

Text

00/ 01h 40 ×25

9 ×16

70

31.5

720×400

16

Text

02/ 03h 80 ×25

9 ×16

70

31.5

320×200

4

APA

04/ 05h 40×25

8 ×8

70

31.5

640×200

2

APA

06h

80×25

8 ×8

70

31.5

720×400

16

Text

07h

80 ×25

9 ×16

70

31.5

320×200

16

APA

0Dh

40 ×25

8 ×8

70

31.5

640×200

16

APA

0Eh

80 ×25

8 ×8

70

31.5

640×350

4

APA

0Fh

80×25

8 ×14

70

31.5

640×350

16

APA

10h

80 ×25

8 ×14

70

31.5

640×480

2

APA

11h

80×30

8 ×16

60

31.5

640×480

16

APA

12h

80 ×30

8 ×16

60

31.5

320×200

256

APA

13h

40 ×25

8 ×8

70

31.5

APA = All points addressable (graphics) — = Not supported

Few vid eo ad ap ters on th e m arket tod ay are lim ited on ly to su p p ort for th e VGA stan d ard . In stead , VGA, at its 16-color 640×480 resolu tion , h as com e to be th e baselin e for PC grap h ical d isp lay con figu ration s. VGA is accep ted as th e least com m on d en om in ator for all W in d ows system s, an d is exp ected to be su p p orted by th e vid eo ad ap ters in all system s ru n n in g W in d ows. Th e in stallation p rogram s of all W in d ows version s u se th ese VGA settin gs as th eir d efau lt vid eo con figu ration . In ad d ition to VGA, m ost ad ap ters su p p ort a ran ge of h igh er screen resolu tion s an d color d ep th s, d ep en d in g on th e cap abilities of th e h ard ware. XGA and XGA-2 IBM an n ou n ced th e PS/ 2 XGA Disp lay Ad ap ter/ A on October 30, 1990, an d th e XGA-2 in Sep tem ber 1992. Both ad ap ters are h igh -p erform an ce, 32-bit bu s-m asterin g ad ap ters for Micro Ch an n el-based system s. Th ese vid eo su bsystem s, evolved from th e VGA, p rovid e greater resolu tion , m ore colors, an d m u ch better p erform an ce. Com bin e fast VGA, m ore colors, h igh er resolu tion , a grap h ics cop rocessor, an d bu sm asterin g, an d you h ave XGA. Bein g a bu s-m asterin g ad ap ter m ean s th at th e XGA can take con trol of th e system as th ou gh it were th e m oth erboard . In essen ce, a bu s m aster is an ad ap ter with its own p rocessor th at can execu te op eration s in d ep en d en t of th e m oth erboard .

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Chapter 8—Video Hardware

Th e XGA was in trod u ced as th e d efau lt grap h ics-d isp lay p latform with th e Mod el 90 XP 486 an d th e Mod el 95 XP 486. In th e d esktop Mod el 90, th e XGA is on th e m oth erboard ; in th e Mod el 95 (a tower u n it), it is located on a sep arate ad d -in board . Th is board —th e XGA Disp lay Ad ap ter/ A—also is available for oth er 386- an d 486-based Micro Ch an n el system s. Th e XGA ad ap ter can be in stalled in an y MCA system s th at h ave 80386, 80386SX, 80386SLC, 486SLC2, 486SLC3, or 80486 p rocessors, in clu d in g PS/ 2 Mod els 53, 55, 57, 65, 70, an d 80. Th e XGA com es stan d ard with 512K of grap h ics m em ory, wh ich can be u p grad ed to 1M with an op tion al vid eo-m em ory exp an sion . In ad d ition to all VGA m od es, th e XGA ad ap ter offers several n ew m od es of op eration , wh ich are listed in Table 8.3. Table 8.3

XGA Unique M odes of Operat ion

M axim um Resolut ion

M axim um Colors

Required VRAM

1,024 ×768

256 colors

1M

1,024 ×768

64 gray shades

1M

1,024 ×768

16 colors

512K

1,024 ×768

16 gray shades

512K

640×480

65,536 colors

1M

640×480

64 gray shades

512K

Th e reason for th e d ifferen t m em ory req u irem en ts is exp lain ed in th e “Th e Vid eo RAM” section , later in th is ch ap ter. Th e 65,536-color m od e p rovid es n ear p h otograp h ic q u ality ou tp u t. Th e 16-bit p ixel is laid ou t as 5 bits of red , 6 bits of green , an d 5 bits of blu e (5-65)—in oth er word s, 32 (2 5 ) sh ad es of red , 64 (2 6 ) sh ad es of green , an d 32 sh ad es of blu e. (Th e eye n otices m ore variation s in green th an in red or blu e.) Th e XGA-2 im p roves on th e p erform an ce of th e origin al XGA in several ways. To begin with , th e XGA-2 in creases th e n u m ber of colors su p p orted at 1,024×768 resolu tion to 65,536 (64K). In ad d ition , becau se of th e circu itry of th e XGA-2, it can p rocess d ata at twice th e sp eed of th e XGA. Th e XGA-2 also works in n on in terlaced m od e, so it p rod u ces less flicker th an th e XGA d oes. Both th e XGA an d XGA-2 su p p ort all existin g VGA an d 8514/ A vid eo m od es. Qu ite a few p op u lar ap p lication s were d evelop ed to su p p ort th e 8514/ A h igh -resolu tion 1,024×768 m od e. Th ese ap p lication s were written to th e 8514/A Adapter interface, wh ich is a software in terface between th e ap p lication an d th e 8514/ A h ard ware. Th e XGA’s exten d ed grap h ics fu n ction m ain tain s com p atibility at th e sam e level. Becau se of th e p ower of th e XGA an d XGA-2, VGA an d 8514/ A ap p lication s ru n m u ch faster. Mu ch of th e sp eed of th e XGA an d XGA-2 also can be attribu ted to its video RAM (V RAM), a typ e of d u al-p orted RAM d esign ed for grap h ics-d isp lay system s. Th is m em ory can be accessed both by th e p rocessor on th e grap h ics ad ap ter an d th e system CPU sim u ltan eou sly, p rovid in g n early in stan tan eou s d ata tran sfers. Th e XGA VRAM is m ap p ed

Video Display Adapters

in to th e system ’s ad d ress sp ace. Th e VRAM n orm ally is located in th e top ad d resses of th e 386’s 4G ad d ress sp ace. Becau se n o oth er ad ap ters n orm ally u se th is area, con flicts are rare. Th e ad ap ters also h ave an 8K ROM BIOS exten sion th at m u st be m ap p ed som ewh ere in segm en t C000 or D000. (Th e in tegrated m oth erboard im p lem en tation of th e XGA d oes n ot req u ire its own ROM, becau se th e m oth erboard BIOS con tain s all th e n ecessary cod e.) √√ See “ Video RAM M emory,” p. 364

Table 8.4 su m m arizes th e XGA m od es. Table 8.4

IBM eXt ended Graphics Array ( XGA) Specificat ions

M ode BIOS Charact er Charact er Vert ical Horizont al Resolut ion Colors Type M ode Form at Box ( Hz) ( KHz) 360×400

16

Text

00/ 01h 40 ×25

9 ×16

70

31.5

720×400

16

Text

02/ 03h 80 ×25

9 ×16

70

31.5

320×200

4

APA

04/ 05h 40×25

8 ×8

70

31.5

640×200

2

APA

06h

80 ×25

8 ×8

70

31.5 31.5

720×400

16

Text

07h

80 ×25

9 ×16

70

320×200

16

APA

0Dh

40 ×25

8 ×8

70

31.5

640×200

16

APA

0Eh

80 ×25

8 ×8

70

31.5

640×350

4

APA

0Fh

80 ×25

8 ×14

70

31.5

640×350

16

APA

10h

80 ×25

8 ×14

70

31.5

640×480

2

APA

11h

80 ×30

8 ×16

60

31.5 31.5

640×480

16

APA

12h

80 ×30

8 ×16

60

320×200

256

APA

13h

40 ×25

8 ×8

70

31.5

1,056 ×400

16

Text

14h

132×25

8 ×16

70

31.5

1,056 ×400

16

Text

14h

132×43

8 ×9

70

31.5

1,056 ×400

16

Text

14h

132×56

8 ×8

70

31.5

1,056 ×400

16

Text

14h

132×60

8 ×6

70

31.5

1,024 ×768

256

APA*

14h

85 ×38

12 ×20

43.48

35.52

640×480

65,536

APA

14h

80 ×34

8 ×14

60

31.5

1,024 ×768

256

APA*

14h

128 ×54

8 ×14

43.48

35.52

1,024 ×768

256

APA*

14h

146 ×51

7 ×15

43.48

35.52

APA = All points addressable (graphics) * = Interlaced

Super VGA ( SVGA) W h en IBM’s XGA an d 8514/ A vid eo card s were in trod u ced , com p etin g m an u factu rers ch ose n ot to attem p t to clon e th ese in crem en tal im p rovem en ts on th eir VGA p rod u cts. In stead , th ey began p rod u cin g lower-cost ad ap ters th at offered even h igh er resolu tion s. Th ese vid eo card s fall in to a category loosely kn own as Super V GA (SV GA).

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SVGA p rovid es cap abilities th at su rp ass th ose offered by th e VGA ad ap ter. Un like th e d isp lay ad ap ters d iscu ssed so far, SVGA refers n ot to an ad ap ter th at m eets a p articu lar sp ecification bu t to a grou p of ad ap ters th at h ave d ifferen t cap abilities. For exam p le, on e card m ay offer several resolu tion s (su ch as 800×600 an d 1,024×768) th at are greater th an th ose ach ieved with a regu lar VGA, wh ereas an oth er card m ay offer th e sam e or even greater resolu tion s bu t also p rovid e m ore color ch oices at each resolu tion . Th ese card s h ave d ifferen t cap abilities; n on eth eless, both are classified as SVGA. Th e SVGA card s look m u ch like th eir VGA cou n terp arts. Th ey h ave th e sam e con n ectors, in clu d in g th e featu re ad ap ter sh own . Becau se th e tech n ical sp ecification s from d ifferen t SVGA ven d ors vary trem en d ou sly, it is im p ossible to p rovid e a d efin itive tech n ical overview in th is book. Th e p in ou ts for th e stan d ard VGA an d SVGA vid eo con n ector (see Figu re 8.1) are sh own in th e followin g table.

1 6

2 7

11

3 8

12

4 9

13

5 10

14

15

FIG. 8.1 Th e stan d ard 15-p in VGA con n ector. Pin

Funct ion

Direct ion

1

Red Video

Out

2

Green Video

Out

3

Blue Video

Out

4

M onitor ID 2

In

5

TTL Ground (monitor self-test)

-_

6

Red Analog Ground

-_

7

Green Analog Ground

-_

8

Blue Analog Ground

-_

9

Key (Plugged Hole)

-_

10

Sync Ground

-_

11

M onitor ID 0

In

12

M onitor ID 1

In

13

Horizontal Sync

Out

14

Vertical Sync

Out

15

M onitor ID 3

In

On th e VGA cable con n ector th at p lu gs in to you r vid eo ad ap ter, p in 9 is always p in less. Pin 5 is u sed on ly for testin g p u rp oses an d p in 15 is rarely u sed ; th ese are often p in less as well. To id en tify th e typ e of m on itor con n ected to th e system , som e m an u factu rers u se th e p resen ce or absen ce of th e m on itor ID p in s in variou s com bin ation s.

Video Display Adapters

VESA SVGA St andards Th e Vid eo Electron ics Stan d ard s Association (VESA) in clu d es m em bers from variou s com p an ies associated with PC an d com p u ter vid eo p rod u cts. In October 1989, VESA, recogn izin g th at p rogram m in g ap p lication s to su p p ort th e m an y SVGA card s on th e m arket was virtu ally im p ossible, p rop osed a stan d ard for a u n iform p rogram m er’s in terface for SVGA card s. Th e SVGA stan d ard is called th e V ESA BIOS Extension. If a vid eo card in corp orates th is stan d ard , a p rogram easily can d eterm in e th e cap abilities of th e card an d access th em . Th e ben efit of th e VESA BIOS Exten sion is th at a p rogram m er n eed s to worry abou t on ly on e rou tin e or d river to su p p ort SVGA. Differen t card s from d ifferen t m an u factu rers are accessible th rou gh th e com m on VESA in terface. W h en first p rop osed , th is con cep t m et with lim ited accep tan ce. Several m ajor SVGA m an u factu rers started su p p lyin g th e VESA BIOS Exten sion as a sep arate m em ory-resid en t p rogram th at you cou ld load wh en you booted you r com p u ter. Over th e years, h owever, oth er ven d ors started su p p lyin g th e VESA BIOS Exten sion as an in tegral p art of th eir SVGA BIOS. Obviou sly, from a u ser’s p ersp ective, su p p ort for VESA in BIOS is a better solu tion . You d o n ot h ave to worry abou t load in g a d river or oth er m em ory-resid en t p rogram wh en ever you wan t to u se a p rogram th at exp ects th e VESA exten sion s to be p resen t. Th e cu rren t VESA SVGA stan d ard covers ju st abou t every vid eo resolu tion an d colord ep th com bin ation cu rren tly available, u p to 1,280×1,024 with 16,777,216 (24-bit) colors. Even if an SVGA vid eo ad ap ter claim s to be VESA-com p atible, h owever, it still m ay n ot work with a p articu lar d river, su ch as th e 800×600, 256-color, SVGA d river th at com es with Microsoft W in d ows. In p ractice, h owever, m an u factu rers con tin u e to p rovid e th eir own d river software. Table 8.5 lists th e vid eo m od es of th e Ch ip s an d Tech n ologies 65554 SVGA grap h ics accelerator, a typ ical ch ip set u sed tod ay. Table 8.5 Chips and Technologies 65554 Graphics Accelerat or Chipset Video M odes BIOS M ode M ode Type

Resolut ion

Charact er

Colors

Scan Freq ( hor/ vert )

0, 1

VGA Text

40 ×25 char

9 ×16

16/ 256K

31.5KHz/ 70Hz

2, 3

VGA Text

80 ×25 char

9 ×16

16/ 256K

31.5KHz/ 70Hz

4, 5

VGA Graph

320 ×200 pels

8 ×8

4/ 256K

31.5KHz/ 70Hz

6

VGA Graph

640 ×200 pels

8 ×8

2/ 256K

31.5KHz/ 70Hz

7

VGA Text

80 ×25 char

9 ×16

M ono

31.5KHz/ 70Hz

D

VGA Graph

320 ×200 pels

8 ×8

16/ 256K

31.5KHz/ 70Hz

E

VGA Graph

640 ×200 pels

8 ×8

16/ 256K

31.5KHz/ 70Hz

F

VGA Graph

640 ×350 pels

8 ×14

M ono

31.5KHz/ 70Hz (continues)

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Chapter 8—Video Hardware

Table 8.5 Chips and Technologies 65554 Graphics Accelerat or Chipset Video M odes Cont inued BIOS M ode M ode Type

Resolut ion

Charact er

Colors

Scan Freq ( hor/ vert )

10

VGA Graph

640 ×350 pels

8 ×14

16/ 256K

31.5KHz/ 70Hz

11

VGA Graph

640 ×480 pels

8 ×16

2/ 256K

31.5KHz/ 60Hz

12

VGA Graph

640 ×480 pels

8 ×16

16/ 256K

31.5KHz/ 60Hz

13

VGA Graph

320 ×200 pels

8 ×8

256/ 256K

31.5KHz/ 70Hz

20

SVGA Graph

640 ×480 pels

8 ×16

16/ 256K

31.5KHz/ 60Hz 37.6KHz/ 75Hz 43.2KHz/ 85Hz

22

SVGA Graph

800 ×600 pels

8 ×8

16/ 256K

37.9KHz/ 60Hz 46.9KHz/ 75Hz 53.7KHz/ 85Hz

24

SVGA Graph

1024×768 pels

8 ×16

16/ 256K

35.5KHz/ 87Hz* 48.5KHz/ 60Hz 60.0KHz/ 75Hz 68.8KHz/ 85Hz

28

SVGA Graph

1280×1024 pels

8 ×16

16/ 256K

35.5KHz/ 87Hz* 35.5KHz/ 60Hz

30

SVGA Graph

640 ×480 pels

8 ×16

256/ 256K

31.5KHz/ 60Hz 37.6KHz/ 75Hz 43.2KHz/ 85Hz

32

SVGA Graph

800 ×600 pels

8 ×16

256/ 256K

37.9KHz/ 60Hz 46.9KHz/ 75Hz 53.7KHz/ 85Hz

34

SVGA Graph

1024×768 pels

8 ×16

256/ 256K

35.5KHz/ 87Hz* 48.5KHz/ 60Hz 60.0KHz/ 75Hz 68.8KHz/ 85Hz

38

SVGA Graph

1280×1024 pels

8 ×16

256/ 256K

35.5KHz/ 87Hz* 35.5KHz/ 60Hz

40

SVGA Graph

640 ×480 pels

8 ×16

32K/ 32K

31.5KHz/ 60Hz 37.6KHz/ 75Hz 43.2KHz/ 85Hz

41

SVGA Graph

640 ×480 pels

8 ×16

64K/ 64K

31.5KHz/ 60Hz 37.6KHz/ 75Hz 43.2KHz/ 85Hz

42

SVGA Graph

800 ×600 pels

8 ×16

32K/ 32K

37.9KHz/ 60Hz 46.9KHz/ 75Hz 53.7KHz/ 85Hz

Video Display Adapters

BIOS M ode M ode Type

Resolut ion

Charact er

Colors

43

800 ×600 pels

8 ×16

64K/ 64K

SVGA Graph

Scan Freq ( hor/ vert ) 37.9KHz/ 60Hz 46.9KHz/ 75Hz 53.7KHz/ 85Hz

44

SVGA Graph

1024×768 pels

8 ×16

32K/ 32K

45

SVGA Graph

1024×768 pels

8 ×16

64K/ 64K

48.5KHz/ 60Hz

50

SVGA Graph

640 ×480 pels

8 ×16

16M / 16M

31.5KHz/ 60Hz

52

SVGA Graph

800 ×600 pels

8 ×16

16M / 16M

37.9KHz/ 60Hz

48.5KHz/ 60Hz

* = interlaced

Video Adapt er Com ponent s All vid eo d isp lay ad ap ters con tain certain basic com p on en ts, su ch as th e followin g: ■ Th e vid eo BIOS ■ Th e vid eo p rocessor ■ Th e vid eo m em ory ■ Th e d igital-to-an alog con verter (DAC) ■ Th e bu s con n ector ■ Th e vid eo d river Man y of th e p op u lar ad ap ters on th e m arket tod ay in clu d e ad d ition al m od u les in ten d ed for sp ecial p u rp oses, su ch as 3D acceleration . Th e followin g section s exam in e th ese com p on en ts in greater d etail. The Video BIOS. Vid eo ad ap ters in clu d e a BIOS (basic in p u t/ ou tp u t system ) th at is sim ilar in con stru ction , bu t com p letely sep arate from th e m ain system BIOS. (Oth er d evices in you r system , su ch as SCSI ad ap ters, m ay also in clu d e th eir own BIOS.) If you tu rn you r m on itor on first an d look q u ickly, you m ay see an id en tification ban n er for you r ad ap ter’s vid eo BIOS at th e very begin n in g of th e system startu p p rocess. Like th e system BIOS, th e vid eo ad ap ter’s BIOS takes th e form of a ROM (read -on ly m em ory) ch ip con tain in g basic in stru ction s th at p rovid e an in terface between th e vid eo ad ap ter h ard ware an d th e software ru n n in g on you r system . Th e software th at m akes calls to th e vid eo BIOS can be a stan d alon e ap p lication , an op eratin g system , or th e m ain system BIOS. It is th e p rogram m in g in th e BIOS ch ip th at en ables you r system to d isp lay in form ation on th e m on itor d u rin g th e system POST an d boot seq u en ces, before an y oth er software d rivers h ave been load ed from d isk. Th e vid eo BIOS is also u p grad able, ju st like a system BIOS, in on e of two ways. Eith er th e BIOS u ses a rewritable ch ip called an EEPROM (electrically erasable program m able read-only m em ory), th at you can u p grad e with a u tility th at th e ad ap ter m an u factu rer p rovid es, or you can com p letely rep lace th e ch ip with a n ew on e, again su p p lied by th e m an u factu rer. A BIOS th at you can u p grad e u sin g software is referred to as a flash BIOS.

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Vid eo BIOS u p grad es are som etim es n ecessary to u se an existin g ad ap ter with a n ew op eratin g system , or wh en th e m an u factu rer en cou n ters a sign ifican t bu g in th e origin al p rogram m in g. As a gen eral ru le, th e vid eo BIOS is a com p on en t th at falls in to th e “if it ain ’t broke, d on ’t fix it” category. Try n ot to let you rself be tem p ted to u p grad e ju st becau se you ’ve d iscovered th at a n ew BIOS revision is available. Ch eck th e d ocu m en tation for th e u p grad e, an d u n less you are exp erien cin g a p roblem th at th e u p grad e ad d resses, leave it alon e. √√ See “ Video Adapter BIOS,” p. 369

The Video Processor. Th e vid eo p rocessor, or chipset, is th e h eart of an y vid eo ad ap ter an d essen tially d efin es th e card ’s fu n ction s an d p erform an ce levels. Two vid eo ad ap ters bu ilt u sin g th e sam e ch ip set often h ave m an y of th e sam e cap abilities an d d eliver com p arable p erform an ce. Also, th e software d rivers th at op eratin g system s an d ap p lication s u se to ad d ress th e vid eo ad ap ter h ard ware are written p rim arily with th e ch ip set in m in d . You can often u se a d river in ten d ed for an ad ap ter with a p articu lar ch ip set on an y oth er ad ap ter u sin g th e sam e ch ip set. Of cou rse, card s bu ilt u sin g th e sam e ch ip set can d iffer in th e am ou n t an d typ e of m em ory in stalled , so p erform an ce m ay vary. Th ere are th ree m ain typ es of p rocessors u sed in vid eo ad ap ters: ■ Fram e bu ffers ■ Cop rocessors ■ Accelerators Th e old est tech n ology u sed in creatin g a vid eo ad ap ter is kn own as fram e-buffer technology. In th is sch em e, th e vid eo ad ap ter is resp on sible for d isp layin g th e in d ivid u al fram es of an im age. Th e vid eo ad ap ter m ain tain s each fram e, bu t it is th e m ain system CPU th at p erform s th e calcu lation s n ecessary to create th e fram e. Th is arran gem en t p laces a h eavy bu rd en on th e CPU, wh ich cou ld be bu sy d oin g oth er p rogram -related com p u tin g. At th e oth er en d of th e sp ectru m is a ch ip set tech n ology kn own as coprocessing. In th is sch em e, th e vid eo ad ap ter in clu d es its own p rocessor, wh ich p erform s all vid eo-related com p u tation s. Th is arran gem en t red u ces th e bu rd en on th e system ’s m ain CPU, en ablin g it to p erform oth er tasks. Th eoretically, th is typ e of ch ip set p rovid es th e fastest overall system th rou gh p u t, bu t p erform an ce is, of cou rse, d ep en d en t on th e h ard ware bein g u sed . Between th ese two arran gem en ts is a m id d le grou n d —a fixed -fu n ction accelerator chip. In th is sch em e, wh ich is u sed in m an y of th e grap h ics accelerator board s on th e m arket tod ay, th e circu itry on th e vid eo ad ap ter d oes m an y of th e m ore tim e-con su m in g vid eo tasks (su ch as d rawin g lin es, circles, an d oth er objects); h owever, th e m ain CPU still d irects th e ad ap ter by p assin g grap h ics-p rim itive com m an d s from ap p lication s, su ch as an in stru ction to d raw a rectan gle of a given size an d color. W h en you evalu ate vid eo ad ap ters for p u rch ase, you sh ou ld always kn ow wh ich ch ip set th e d evices u se. Th is in form ation gives you a m u ch better basis for com p arin g th at card

Video Display Adapters

again st oth ers. Prod u ct literatu re an d W eb sites th at p rovid e tech n ical sp ecification s for vid eo ad ap ters sh ou ld always sp ecify th e ch ip sets u sed on th e d evices. Also, you can often fin d reviews or op in ion s con cern in g sp ecific ch ip sets th at can in flu en ce you r p u rch asin g d ecision . You m ay, for exam p le, read abou t a great n ew ch ip set th at h as recen tly been released by a p articu lar m an u factu rer an d , as a resu lt, seek ou t vid eo ad ap ters u sin g th at ch ip set. Id en tifyin g th e ch ip set on you r vid eo ad ap ter also p rovid es you with an ad d ition al aven u e for d rivers an d tech n ical su p p ort. Most ch ip set m an u factu rers m ain tain W eb sites an d tech su p p ort d ep artm en ts, ju st as ad ap ter m an u factu rers d o. If you d o n ot receive ad eq u ate service from on e of th e com p an ies, you can always try th e oth er. Th e ven d or list in Ap p en d ix A h as in form ation on m ost of th e p op u lar vid eo ch ip set m an u factu rers, in clu d in g h ow to con tact th em . The Video RAM . Vid eo ad ap ters rely on th eir own on -board m em ory th at th ey u se to store vid eo im ages wh ile p rocessin g th em . Th e am ou n t of m em ory on th e ad ap ter d eterm in es th e m axim u m screen resolu tion an d color d ep th th at th e d evice can su p p ort. You can often select h ow m u ch m em ory you wan t on a p articu lar vid eo ad ap ter—for exam p le, 256K, 512K, 1M, 2M, 4M, or 8M are com m on ch oices tod ay. Most card s tod ay com e with at least 2M, an d m an y h ave 4M. Ad d in g m ore m em ory d oes n ot sp eed u p you r vid eo ad ap ter; in stead , it en ables th e card to gen erate m ore colors an d / or h igh er resolu tion s. Man y d ifferen t typ es of m em ory are u sed on vid eo ad ap ters tod ay. Th ese m em ory typ es are su m m arized in Table 8.6 an d exam in ed m ore fu lly in u p com in g section s. Table 8.6

M em ory Types Used in Video Display Adapt ers

I/ O Bus

Tot al Frequency ( M Hz)

Net Lat ency ( ns)

Bandw idt h ( M / sec)

FPM DRAM

Fast Page-M ode RAM

25-33

80

80

VRAM

Video RAM

25-33

*

100

WRAM

Window RAM

>50

*

120

EDO DRAM

Extended Data Out DRAM

40-50

100

105

SDRAM

Synchronous DRAM

66-100

102-75

166-253

M DRAM

M ultibank DRAM

125-166

22-19

405-490

SGRAM

Synchronous Graphics DRAM

>125

100-75

200-300

M em ory Type

*V RAM and W RAM are dual-ported m em ory types that can read and write data sim ultaneously.

RAM Ca l c u l a t i o n s. Th e am ou n t of m em ory th at a vid eo ad ap ter n eed s to d isp lay a p articu lar resolu tion an d color d ep th is based on a m ath em atical eq u ation . Th ere h as to be a location in th e ad ap ter’s m em ory array to d isp lay every p ixel on th e screen , an d th e n u m ber of total p ixels is d eterm in ed by th e resolu tion . For exam p le, a screen resolu tion of 1,024×768 req u ires a total of 786,432 p ixels. If you were to d isp lay th at resolu tion with on ly two colors, you wou ld n eed on ly on e bit of m em ory sp ace to rep resen t each p ixel. If th e bit h as a valu e of 0, th e d ot is black, an d

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if its valu e is 1, th e d ot is wh ite. If you u se fou r bits of m em ory sp ace to con trol each p ixel, you can d isp lay 16 colors, becau se th ere are 16 p ossible com bin ation s with a 4d igit bin ary n u m ber (2 to th e 4th p ower eq u als 16). If you m u ltip ly th e n u m ber of p ixels n eed ed for th e screen resolu tion by th e n u m ber of bits req u ired to rep resen t each p ixel, you h ave th e am ou n t of m em ory th at th e ad ap ter n eed s to d isp lay th at resolu tion . Here is h ow th e calcu lation works: 1,024×768 = 786,432 p ixels × 4-bits p er p ixel = 3,145,728 bits = 393,216 bytes = 384K As you can see, d isp layin g 16 colors at 1,024×768 resolu tion req u ires exactly 384K of RAM on th e vid eo ad ap ter. Becau se m ost ad ap ters su p p ort m em ory am ou n ts of on ly 256K, 512K, 1M, 2M, or 4M, you wou ld h ave to in stall 512K to ru n you r system u sin g th at resolu tion an d color d ep th . In creasin g th e color d ep th to 8 bits p er p ixel resu lts in 256 p ossible colors, an d a m em ory req u irem en t of 786,432 bytes or 768K. Again , becau se n o vid eo ad ap ters are eq u ip p ed with th at exact am ou n t, you wou ld h ave to p u rch ase an ad ap ter with 1M of m em ory. To u se th e h igh er resolu tion m od es an d greater n u m bers of colors th at are com m on tod ay, you will n eed m u ch m ore m em ory on you r vid eo ad ap ter th an th e 256K fou n d on th e origin al IBM VGA. Table 8.7 sh ows th e m em ory req u irem en ts for som e of th e m ost com m on ly u sed screen resolu tion s an d color d ep th s. Table 8.7

Video Display Adapt er M inim um M em ory Requirem ent s

Resolut ion

Color Dept h

No. Colors

Video

M em ory Required

640×480

4-bit

16

256K

153,600 bytes

640×480

8-bit

256

512K

307,200 bytes 614,400 bytes

640×480

16-bit

65,536

1M

640×480

24-bit

16,777,216

1M

921,600 bytes

800×600

4-bit

16

256K

240,000 bytes

800×600

8-bit

256

512K

480,000 bytes 960,000 bytes

800×600

16-bit

65,536

1M

800×600

24-bit

16,777,216

2M

1,440,000 bytes

1,024 ×768

4-bit

16

512K

393,216 bytes

1,024 ×768

8-bit

256

1M

786,432 bytes

1,024 ×768

16-bit

65,536

2M

1,572,864 bytes

1,024 ×768

24-bit

16,777,216

4M

2,359,296 bytes

1,280 ×1,024

4-bit

16

1M

655,360 bytes

1,280 ×1,024

8-bit

256

2M

1,310,720 bytes

1,280 ×1,024

16-bit

65,536

4M

2,621,440 bytes

1,280 ×1,024

24-bit

16,777,216

4M

3,932,160 bytes

Video Display Adapters

From th is table, you can see th at a vid eo ad ap ter with 2M can d isp lay 65,536 colors in 1,024×768 resolu tion m od e, bu t for a tru e color (16.8M colors) d isp lay, you wou ld n eed to u p grad e to 4M.

Not e Although some adapters can operate in a 32-bit mode, this does not necessarily mean that they can produce more than the 16,277,216 colors of a 24-bit true color display. M any video processors and video memory buses are optimized to move data in 32-bit words, and actually display 24bit color while operating in a 32-bit mode, instead of the 4,294,967,296 colors that you would expect from a true 32-bit color depth.

If you sp en d a lot of tim e workin g with grap h ics, you m ay wan t to in vest in a 24-bit vid eo card with 4M of RAM. Man y of th e card s tod ay can easily h an d le 24-bit color, bu t you will n eed 4M of RAM to get th at cap ability in th e h igh er resolu tion m od es.

Not e You can upgrade the RAM on some video adapters by installing a separate module containing the additional memory chips. The module usually takes the form of a daughter card; that is, a small circuit board that plugs into a socket on the video adapter. The design of the daughter board is proprietary, even if the type of memory chips on the board are not. You will have to purchase the module from the manufacturer of the video adapter.

Vi d e o Bu s W i d t h . An oth er issu e with resp ect to th e m em ory on th e vid eo ad ap ter is th e wid th of th e bu s con n ectin g th e grap h ics ch ip set an d th e m em ory on th e ad ap ter. Th e ch ip set is u su ally a sin gle large ch ip on th e card th at con tain s virtu ally all of th e ad ap ter’s fu n ction s. It is wired d irectly to th e m em ory on th e ad ap ter th rou gh a local bu s on th e card . Most of th e h igh -en d ad ap ters u se an in tern al m em ory bu s th at is 64 bits or even 128 bits wid e. Th is jargon can be con fu sin g, becau se vid eo ad ap ters th at take th e form of sep arate exp an sion card s also p lu g in to th e m ain system bu s, wh ich h as its own sp eed ratin g. W h en you read abou t a 64-bit or 128-bit vid eo ad ap ter, you m u st u n d erstan d th at th is refers to th e local vid eo bu s, an d th at th e bu s con n ectin g th e ad ap ter to th e system is actu ally th e 32- or 64-bit PCI or AGP bu s on th e system ’s m oth erboard . √√ See “ System Bus Functions and Features,” p. 233

D RAM. Historically, m ost vid eo ad ap ters h ave u sed regu lar dynam ic RAM (DRAM) for th is p u rp ose. Th is typ e of RAM, alth ou gh in exp en sive, is rath er slow. Th e slown ess can be attribu ted to th e n eed to con stan tly refresh th e in form ation con tain ed with in th e RAM, an d to th e fact th at DRAM can n ot be read at th e sam e tim e it is bein g written . Mod ern PC grap h ics ad ap ters n eed extrem ely h igh d ata tran sfer rates to an d from th e vid eo m em ory. At a resolu tion of 1,024×768 an d a stan d ard refresh rate of 72Hz, th e d igital-to-an alog con verter (DAC) on th e card n eed s to read th e con ten ts of th e vid eo m em ory fram e bu ffer 72 tim es p er secon d . In tru e color (24-bits p er p ixel) m od e, th is

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m ean s th at th e DAC m u st be able to read from th e vid eo m em ory at a rate of abou t 170M/ sec, wh ich is ju st abou t th e m axim u m available from a con ven tion al DRAM d esign . Becau se of th e h igh ban d wid th req u ired , a n u m ber of com p etin g m em ory tech n ologies h ave em erged over th e p ast several years to m eet th e p erform an ce n eed s of h igh -en d vid eo m em ory. √√ See “ DRAM ,” p. 311

ED O D RAM. On e of th e m ore recen t m em ory d esign s to be in corp orated in to vid eo ad ap ters is EDO (Extended Data Out) DRAM. EDO p rovid es a wid er effective ban d wid th by offload in g m em ory p rech argin g to sep arate circu its, m ean in g th at th e n ext access can begin before th e last access h as fin ish ed . As a resu lt, EDO offers a 10% sp eed boost over DRAM, at a sim ilar cost. EDO DRAM was in trod u ced by Micron Tech n ologies, an d was origin ally d esign ed for u se in a PC’s m ain RAM array, bu t it is n ow also bein g u sed for vid eo ad ap ter m em ory. EDO ch ip s are con stru cted u sin g th e sam e d ies as con ven tion al DRAM ch ip s, an d th ey d iffer from DRAMs on ly in h ow th ey are wired in fin al p rod u ction . Th is m eth od en ables m an u factu rers to m ake EDO ch ip s on th e sam e p rod u ction lin es an d at th e sam e relative costs as DRAM. √√ See “ EDO RAM ,” p. 315

VRAM. V RAM (V ideo RAM) is an oth er p op u lar typ e of m em ory th at m an u factu rers h ave been u sin g in vid eo ad ap ters for som e tim e n ow. VRAM is d esign ed to be dual-ported, wh ich en ables th e p rocessor or accelerator ch ip on th e ad ap ter an d th e DAC or even th e PC’s own p rocessor to access th e RAM sim u ltan eou sly. Th is p rovid es m u ch greater p erform an ce th an stan d ard DRAM or even EDO, bu t it com es at a h igh er p rice. W RAM. W RAM, or W indows RAM, is a m od ified VRAM-typ e d u al-p orted m em ory tech n ology d evelop ed by Sam su n g th at is aim ed sp ecifically at grap h ics ad ap ters. W RAM offers m argin ally better p erform an ce th an stan d ard VRAM at a lower cost. Man y m akers of h igh -en d vid eo ad ap ters are n ow u sin g W RAM as a rep lacem en t for VRAM. MD RAM. MDRAM (Multibank DRAM) is a n ew typ e of m em ory th at is also exp licitly aim ed at grap h ics an d vid eo ap p lication s. Develop ed by MoSys In c., MDRAMs con sist of a large n u m ber of sm all (32K) ban ks. Trad ition ally, DRAM or VRAM is logically organ ized as a sin gle, m on olith ic ban k. Organ izin g th e m em ory in to sm all ban ks m akes it p ossible for m an u factu rers to easily su p p ly ad ap ters with an y am ou n t of MDRAM th at is an in tegral m u ltip le of 32K, in stead of bein g restricted to th e trad ition al bin ary m u ltip le sizes fou n d in m an y vid eo card s. Th is is a sign ifican t ad van tage for th e cost-sen sitive PC m arketp lace. For exam p le, a 1,024×768 tru e color (24-bit) grap h ics system req u ires 2.3M for th e fram e bu ffer p lu s som e extra m em ory for off-screen storage. For an ad ap ter u sin g 256K×16 DRAMs an d a 64-bit bu s, th e on ly workable m em ory size th at accom m od ates th is fram e bu ffer is 4M, con stru cted of two ban ks of fou r ch ip s each . However, with MDRAM, it is

Video Display Adapters

n o p roblem to con stru ct an ad ap ter with a m em ory system of 2.5M, th at is com p osed of on ly two or th ree in d ivid u al ch ip s. Th is elim in ates th e wasted extra 1.5M, an d th e total m em ory cost can be sign ifican tly red u ced . In ad d ition to th e better m em ory sizin g, MDRAM organ izes its in tern al ban ks off of a n arrow cen tral bu s, wh ich p erm its access to each ban k in d ivid u ally. As a resu lt, th is d esign can com p lete a bu rst to or from on e ban k an d th en begin a bu rst to or from an oth er, all in a sin gle clock cycle, offerin g m u ch h igh er p erform an ce th an VRAM or W RAM. SGRAM. SGRAM, or Synchronous Graphics RAM, is a h igh -en d solu tion for very fast vid eo ad ap ter d esign s. Like th e SDRAM u sed in m oth erboard m em ory arrays, SGRAM can syn ch ron ize itself with th e sp eed of th e bu s, u p to 100MHz. Th is typ e of m em ory can be u p to fou r tim es as fast as con ven tion al DRAM an d op erate at sp eed s u p to 125MHz or faster an d is n ow bein g u sed in m an y of th e h igh est q u ality PCI an d AGP ad ap ters. SGRAM is on e of th e m ost exp en sive m em ory tech n ologies n ow u sed in vid eo ad ap ters, bu t it offers su p erior p erform an ce for grap h ics-in ten sive ap p lication s. √√ See “ SDRAM ,” p. 316

The Digit al-t o-Analog Convert er. Th e d igital-to-an alog con verter on a vid eo ad ap ter (com m on ly called a RAMDAC) d oes exactly as its n am e d escribes. Th e RAMDAC is resp on sible for con vertin g th e d igital im ages th at you r com p u ter gen erates in to an alog sign als th at th e m on itor can d isp lay. Th e sp eed of th e RAMDAC is m easu red in MHz; th e faster th e con version p rocess, th e h igh er th e ad ap ter’s vertical refresh rate. Th e sp eed s of th e RAMDAC’s u sed in tod ay’s h igh p erform an ce vid eo ad ap ters can exceed 200MHz. The Bus. You ’ve learn ed in th is ch ap ter th at certain vid eo ad ap ters were d esign ed for u se with certain system bu ses. For exam p le, th e VGA an d XGA were both origin ally d esign ed for u se with IBM’s MCA bu s. Th e bu s th at you u se in you r com p u ter affects th e sp eed at wh ich you r system p rocesses vid eo in form ation . For exam p le, th e ISA bu s offers a 16-bit d ata p ath at sp eed s of 8.33MHz. Th e EISA or MCA bu ses can p rocess 32 bits of d ata at a tim e, bu t th ey also ru n at sp eed s u p to 10MHz. Th ese th ree bu ses are n o lon ger u sed for vid eo ad ap ters, becau se IBM h as d iscon tin u ed th e MCA bu s an d th e oth ers are too slow.

Not e Don’t confuse the system bus speed with the system processor speed, even though they are both measured in megahertz (M Hz). System processors run at speeds upward of 300M Hz, but the system bus is much slower.

Th e n ext m ajor im p rovem en t in bu s sp eed cam e with th e V ESA local bus (VL-Bu s) stan d ard . Th e VL-Bu s stan d ard typ ically is an ad d ition to an existin g bu s tech n ology. For exam p le, you m igh t h ave an ISA system th at also con tain s a VL-Bu s slot. Even if it is u sed in an ISA system , th e VL-Bu s p rocesses 32 bits of d ata at a tim e an d at th e fu ll-rated extern al sp eed of th e CPU—u p to 40MHz. Th u s, you can ach ieve m u ch greater sp eed s by u sin g a well im p lem en ted VL-Bu s in you r system .

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In Ju ly 1992, In tel Corp oration in trod u ced Perip h eral Com p on en t In tercon n ect (PCI) as a blu ep rin t for d irectly con n ectin g m icrop rocessors an d su p p ort circu itry; it th en exten d ed th e d esign to a fu ll exp an sion bu s with Release 2 in 1993. Pop u larly term ed a m ezzanine bus, PCI com bin es th e sp eed of a local bu s with m icrop rocessor in d ep en d en ce. PCI vid eo ad ap ters, like VL-Bu s ad ap ters, can in crease vid eo p erform an ce d ram atically. PCI vid eo ad ap ters, by th eir d esign , are m ean t to be Plug and Play (PnP), m ean in g th at th ey req u ire little con figu ration . Th e PCI stan d ard virtu ally rep laced th e old er VL-Bu s stan d ard overn igh t an d is n ow fou n d in n early all n ew PCs. Th e vast m ajority of th e vid eo ad ap ters on th e m arket tod ay u se th e PCI bu s. √√ See “ Accelerated Graphics Port (AGP),” p. 268 √√ See “ The PCI Bus,” p. 256

Th e m ost recen t system bu s in n ovation is th e Accelerated Grap h ics Port (AGP), a d ed icated vid eo bu s d esign ed by In tel th at d elivers a m axim u m ban d wid th fou r tim es larger th an th at of a com p arable PCI bu s. AGP is essen tially an en h an cem en t to th e existin g PCI bu s, in ten d ed for u se on ly with vid eo ad ap ters, an d p rovid in g th em with h igh -sp eed access to th e m ain system m em ory array. Th is en ables th e ad ap ter to p rocess certain 3D vid eo elem en ts, su ch as textu re m ap s, d irectly from system m em ory, rath er th an h avin g to cop y th e d ata to th e ad ap ter m em ory before th e p rocessin g can begin . Th is saves tim e an d elim in ates th e n eed to u p grad e th e vid eo ad ap ter m em ory to better su p p ort 3D fu n ction s. Alth ou gh it was d esign ed with th e Pen tiu m II in m in d , AGP is n ot p rocessor-d ep en d en t. However, it d oes req u ire su p p ort from th e m oth erboard ch ip set, wh ich m ean s th at you can n ot u p grad e an existin g system to u se AGP with ou t rep lacin g th e m oth erboard . Cu rren tly, Pen tiu m II m oth erboard s with th e In tel 440LX, 440EX, an d 440BX ch ip sets su p p ort AGP. In tel is also cu rren tly d evelop in g an AGP ch ip set for u se on socket 7 m oth erboard s, so system s with p rocessors oth er th an th e Pen tiu m II can u se AGP. Acer Laboratories In c. (ALi) also h as th e Alad d in Pro II ch ip set th at su p p orts AGP X2 for Pen tiu m II Slot 1 m oth erboard s an d th e Alad d in V Pen tiu m ch ip set th at su p p orts AGP X2 for Pen tiu m Socket 7 m oth erboard s. VIA Tech n ologies’ Ap ollo VP3 an d Ap ollo MVP3 both su p p ort AGP for Socket 7 m oth erboard s. An d , SiS h as th eir SiS 5591 wh ich also su p p orts AGP on a socket 7 m oth erboard . Even with th e p rop er ch ip set, h owever, you can n ot take fu ll ad van tage of AGP’s cap abilities with ou t th e p rop er op eratin g system su p p ort. AGP’s DIrect Mem ory Execu te (DIME) featu re u ses m ain m em ory in stead of th e vid eo ad ap ter’s m em ory for certain tasks, to lessen th e traffic to an d from th e ad ap ter. W in d ows 98 su p p orts th is featu re, as will W in d ows NT 5, bu t W in d ows 95 d oes n ot. √√ See “ Chipsets,” p. 183

It is always wise to be cau tiou s before ad op tin g an y n ew tech n ology, an d AGP is n o excep tion . Th ere h ave been p roblem s rep orted with som e of th e early AGP

Video Display Adapters

im p lem en tation s to reach th e m arket. Also, version 2.0 of th e AGP sp ecification is cu rren tly in th e p relim in ary d raft stage. Th e n ew sp ec in clu d es su p p ort for 2x an d 4x d ata tran sfer m od es th at p rom ise to im p rove th e p erform an ce of th e bu s still fu rth er. After AGP tech n ology h as m atu red a bit, h owever, it is very likely to becom e th e in d u stry stan d ard bu s for vid eo ad ap ters. Man y of th e h igh -en d vid eo ad ap ters on th e m arket tod ay are alread y available in both PCI an d AGP version s. If you r com p u ter h as a ch ip set th at su p p orts AGP, you are likely to be well served by takin g ad van tage of its cap abilities. VL-Bu s, PCI, an d AGP h ave som e im p ortan t d ifferen ces, as Table 8.8 sh ows. Table 8.8

Local Bus Specificat ions

Feat ure

VL-Bus

PCI

AGP

Theoretical maximum throughput

132M / sec

132M / sec*

533M / sec

Slots**

3 (typical)

4/ 5 (typical)

1

Plug and Play support

No

Yes

Yes

Cost

Inexpensive

Slightly higher

Slightly higher than PCI

Ideal use

Low cost 486

High-end 486, Pentium, P6 Pentium II

*At the 66MHz bus speed and 32 bits. Throughput will be higher on the 100MHz system bus. **More slots are possible through the use of PCI bridge chips.

The Video Driver. Th e software d river is an essen tial, an d often a p roblem atic, elem en t of a vid eo d isp lay su bsystem . Th e d river en ables you r software to com m u n icate with th e vid eo ad ap ter. You can h ave a vid eo ad ap ter with th e fastest p rocessor an d th e m ost efficien t m em ory on th e m arket, bu t still h ave p oor vid eo p erform an ce becau se of a bad ly written d river. DOS ap p lication s ad d ress th e vid eo d isp lay h ard ware d irectly, an d typ ically in clu d e th eir own d rivers for variou s typ es of vid eo ad ap ters. All version s of W in d ows, h owever, u se a d river th at is in stalled in th e op eratin g system . Ap p lication s th en can u se op eratin g system fu n ction calls to access th e vid eo h ard ware. Vid eo d rivers are gen erally d esign ed to su p p ort th e p rocessor on th e vid eo ad ap ter. All vid eo ad ap ters com e eq u ip p ed with d rivers su p p lied by th e m an u factu rer, bu t you often can u se a d river created by th e ch ip set m an u factu rer as well. Som etim es you m ay fin d th at on e of th e two p rovid es better p erform an ce th an th e oth er, or resolves a p articu lar p roblem you are exp erien cin g. Most m an u factu rers of vid eo ad ap ters an d ch ip sets m ain tain W eb sites from wh ich you can obtain th e latest d rivers. A d river from th e ch ip set m an u factu rer can be a u sefu l altern ative, bu t you sh ou ld always try th e ad ap ter m an u factu rer’s d river first. Before p u rch asin g a vid eo ad ap ter, it is a good id ea to ch eck ou t th e m an u factu rer’s site an d see wh eth er you can d eterm in e h ow m an y d river releases th ere h ave been for th e ad ap ter you ’re con sid erin g. Freq u en t d river revision s can be a sign th at m an y u sers are exp erien cin g p roblem s. Alth ou gh it m ay be a good th in g to see th at th e com p an y is resp on d in g to com p lain ts, it m ay also in d icate th at th e h ard ware is n ot d ep en d able.

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Th e vid eo d river also p rovid es th e in terface th at you can u se to con figu re th e d isp lay p rod u ced by you r ad ap ter. On a W in d ows 98 system , th e Settin gs p age of th e Disp lay Con trol Pan el (sh own in Figu re 8.2) id en tifies th e m on itor an d vid eo ad ap ter in stalled on you r system , an d en ables you to select th e color d ep th an d screen resolu tion th at you p refer. Th e d river con trols th e op tion s th at are available for th ese settin gs, so you can ’t ch oose p aram eters th at aren ’t su p p orted by th e h ard ware. For exam p le, th e con trols wou ld n ot allow you to select a 1024×768 resolu tion with 24-bit color if th e ad ap ter h ad on ly 1M of m em ory.

FIG. 8.2 From th e W in d ows 98 Con trol Pan el, you can set th e screen resolu tion an d color d ep th for you r d isp lay.

W h en you click th e Ad van ced bu tton on th e Settin gs p age, you see th e Prop erties d ialog box for you r p articu lar vid eo d isp lay ad ap ter. Th e con ten ts of th is d ialog box can vary, d ep en d in g on th e d river an d th e cap abilities of th e h ard ware. Typ ically, on th e Gen eral p age of th is d ialog box, you can select th e size of th e fon ts (large or sm all) to u se with th e resolu tion you ’ve ch osen . W in d ows 98 also ad d s a con trol to activate a very con ven ien t featu re. Th e Sh ow Settin gs Icon on Task Bar ch eckbox activates a tray icon th at en ables you to q u ickly an d easily ch an ge resolu tion s an d color d ep th s with ou t h avin g to op en th e Con trol Pan el. Th e Ad ap ter p age d isp lays d etailed in form ation abou t you r ad ap ter an d th e d rivers in stalled on th e system , an d en ables you to set th e Refresh Rate for you r d isp lay. If you r ad ap ter in clu d es a grap h ics accelerator, th e Perform an ce p age (see Figu re 8.3) con tain s a Hard ware Acceleration slid er th at you can u se to con trol th e d egree of grap h ic d isp lay assistan ce p rovid ed by you r ad ap ter h ard ware. Settin g th e Hard ware Acceleration slid er to th e Fu ll p osition activates all th e ad ap ter’s h ard ware acceleration featu res. Movin g th e slid er on e n otch to th e left ad d resses m ou se d isp lay p roblem s by d isablin g th e h ard ware’s cu rsor su p p ort in th e d isp lay d river. Th is is th e eq u ivalen t of ad d in g th e SWCursor=1 d irective to th e [Display] section of th e System .in i file.

Video Display Adapters

FIG. 8.3 W in d ows 98 d isp lays d etailed in form ation abou t you r vid eo d isp lay ad ap ter an d its d river su p p ort. Movin g th e slid er an oth er n otch (to th e secon d n otch from th e righ t) p reven ts th e ad ap ter from p erform in g certain bit block tran sfers. W ith som e d rivers, th is settin g also d isables m em ory-m ap p ed I/ O. Th is is th e eq u ivalen t of ad d in g th e Mmio=0 d irective to th e [Display] section of System .in i an d th e SafeMode=1 d irective to th e [Windows] section of W in .in i (an d th e SWCursor d irective m en tion ed p reviou sly). Movin g th e slid er to th e Non e settin g (th e far left) ad d s th e SafeMode=2 d irective to th e [Windows] section of th e W in .in i file. Th is d isables all h ard ware acceleration su p p ort an d forces th e op eratin g system to u se on ly th e d evice-in d ep en d en t bitm ap (DIB) en gin e to d isp lay im ages, rath er th an bit-block tran sfers. Use th is settin g wh en you exp erien ce freq u en t screen locku p s or wh en you receive invalid page fault error m essages. Video Cards for M ult im edia Mu ltim ed ia h as becom e an im p ortan t elem en t of th e p erson al com p u tin g in d u stry. Tech n ology th at was at first relegated to en tertain m en t u ses, an d th erefore d ism issed by m an y com p u tin g p rofession als, h as n ow been assim ilated in to th e corp orate world . Live d ata feed s, vid eocon feren cin g, an d an im ated p resen tation s are ju st a few of th e tech n ologies th at are n ow com m on p lace elem en ts of bu sin ess com p u tin g. As th e d em an d for m u ltim ed ia con ten t in creases, so d o th e cap abilities of th e h ard ware an d software u sed to p rod u ce th e con ten t. Vid eo is ju st on e, albeit im p ortan t, elem en t of th e m u ltim ed ia exp erien ce, an d th e grap h ics ad ap ters on th e m arket tod ay reflect th e d em an d for th ese in creased cap abilities. Prod u cin g state-of-th e-art m u ltim ed ia con ten t tod ay often req u ires th at th e PC be cap able of in terfacin g with oth er d evices, su ch as cam eras, VCRs, an d television sets, an d m an y vid eo ad ap ters are n ow eq u ip p ed with th is cap ability. Oth er m u ltim ed ia tech n ologies, su ch as 3D an im ation , p lace an en orm ou s bu rd en on a system ’s p rocessin g an d d ata-h an d lin g cap abilities, an d m an y m an u factu rers of vid eo ad ap ters are red esign in g th eir p rod u cts to sh ou ld er th is bu rd en m ore efficien tly. Th e followin g section s exam in e som e of th e vid eo ad ap ter com p on en ts th at m ake th ese tech n ologies p ossible an d p ractical.

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Video Feat ure Connect ors. On e often overlooked p art of th e VGA stan d ard th at IBM released in 1987 was th e V ideo Feature Connector, or V FC. Th is was a 26-p in con n ector th at en abled oth er vid eo card s to con n ect to a VGA ad ap ter d irectly. Un fortu n ately, th is stan d ard was p oorly d ocu m en ted by IBM an d p oorly im p lem en ted by m ost VGA ad ap ter m an u factu rers. In fact, m an y VGA card s d id n ot im p lem en t th e VFC at all, basically ign orin g th e n eed . Th at m ay h ave been fin e in th e early d ays of VGA, becau se th ere were few m u ltim ed ia p rod u cts th at n eed ed to tap in to th e VGA sign al. Tod ay, h owever, th ere are m an y typ es of m u ltim ed ia ad d -on board s th at h ave featu res su ch as fu ll-m otion vid eo, vid eo cap tu re, vid eo com p ression , an d television tu n ers th at n eed th e services of th is con n ector to d o th eir job. Un fortu n ately, th ere was an oth er p roblem with th e VFC besid es it n ot bein g th ere or bein g im p lem en ted in correctly. Th e p roblem was on e of p erform an ce. Th e origin al VGA ad ap ter was d esign ed as an 8-bit bu s ad ap ter, an d fu n ction ed at a m axim u m resolu tion of on ly 640×480 p ixels. Th u s, th e VFC h ad th ese sam e lim itation s, wh ich p u t a d am p er on th e typ e of vid eo sign al th at cou ld be tran sferred d irectly from on e card to an oth er. Becau se m ost of th e tech n ologies tod ay th at req u ire com m u n ication between ad ap ters in volve fu ll-m otion vid eo an d oth er ban d wid th -in ten sive ap p lication s, th is was a m ajor p roblem . In Novem ber 1983, th e p roblem s with th e VFC were ad d ressed by th e Vid eo Electron ics Stan d ard s Association ’s (VESA) an n ou n cem en t of th e VESA Ad van ced Featu re Con n ector (VAFC) an d th e VESA Med ia Ch an n el (VMC) vid eo bu s stan d ard s. Th ese n ew stan d ard s were d esign ed to p rovid e com p atibility an d p erform an ce for in tercon n ected m u ltim ed ia ad ap ters an d vid eo ad ap ters. Th e resu lt is th e rap id growth in th e ad op tion of n ew ap p lication s su ch as in teractive vid eo, vid eo p resen tation , vid eo con feren cin g, an d d esktop vid eo ed itin g. Th e V ESA Advanced Feature Connector (V AFC) p rovid es an exten sion of th e in d u stry stan d ard VFC fou n d on m an y grap h ics board s. Th e VAFC solves h igh ban d wid th req u irem en ts by wid en in g th e cu rren t featu re con n ector’s d ata p ath from 16/ 32 to 8 bits an d ad d in g ad d ition al sign als, wh ich p rovid e m ore reliable op eration . Th e VAFC d elivers 75M/ sec th rou gh p u t in its 16-bit baselin e con figu ration , an d u p to 150M/ sec in th e 32bit con figu ration . Oth er featu res in clu d e m u ltip le p ixels p er clock, color sp ace d ata, gen lockin g, an d asyn ch ron ou s vid eo in p u t. Th e VAFC also overcom es th e cu rren t 640×480 p ixel 256-color resolu tion lim itation s of m ost vid eo overlay p rod u cts. Un fortu n ately, wh ile th e VAFC su ccessfu lly ad d resses th e p erform an ce an d com p atibility issu es of th e VFC, it h as n ot tu rn ed ou t to be a cost-effective solu tion , an d h as n ot been ad op ted by m an y vid eo ad ap ter m an u factu rers. Th e V ESA Media Channel (V MC) is a d ed icated m u ltim ed ia bu s th at p rovid es an in d ep en d en t p ath for th e sim u ltan eou s p rocessin g of several h igh ban d wid th vid eo stream s. Th e VMC d irectly ad d resses th e cu rren t lim itation s of ru n n in g vid eo across a com p u ter’s

Video Display Adapters

system bu s. Th is d esign solves th e u n iversal ban d wid th bottlen eck an d laten cy issu es th at exist in all system or p rocessor bu s arch itectu res in clu d in g ISA, EISA, MicroCh an n el, VL-Bu s, an d PCI. To correct th ese p roblem s, th e V ESA Media Channel is d esign ed to en able th e tran sp aren t in tegration of vid eo an d grap h ics with ou t th e in terferen ce of p rocessor in terru p ts or bu s con ten tion . VESA Med ia Ch an n el p rovid es th e op tion for a 68-p in m u lti-d rop cable, en ablin g th e com bin ation of u p to 15 d evices in a m od u lar fash ion with d ata tran sfer rates of u p to 132M/ sec. For exam p le, a grap h ics system su p p ortin g th e VESA Med ia Ch an n el can easily an d cost-effectively be con figu red as a cap tu re, d ecod e on ly, en cod e on ly, or a fu ll en cod e/ d ecod e vid eo system . Th is is im p ortan t in ap p lication s su ch as vid eo telecon feren cin g, an d p rovid es flexible, cost-effective en gin eerin g of a p articu lar system .

Tip If you intend to use your PC for video applications that require the use of additional adapters for services like video capture or M PEG compression, it is a good idea to select a video adapter that supports the 68-pin VM C connector. If you see only a 26-pin connector on the adapter, then the card supports only the standard VFC. M ost of the higher-quality multimedia adapters will require a VM C connection for high performance video signal transfer.

Becau se n on e of th ese sp ecification s for in tern al vid eo featu re con n ectors h ave becom e in d u stry stan d ard s, som e m an u factu rers of au xiliary vid eo p rod u cts su ch as d ed icated 3D accelerator board s an d MPEG d ecod ers h ave taken an altern ate rou te th rou gh th e stan d ard VGA con n ector. Th e Diam on d Mon ster 3D (an d 3D II), for exam p le, works in ad d ition to a system ’s stan d ard 2D vid eo ad ap ter, n ot in p lace of it. However, in stead of req u irin g th at th e 2D ad ap ter h ave a p articu lar in tern al con n ector, th e Mon ster 3D in clu d es an extern al p assth rou gh cable. Th is cable con n ects th e Mon ster 3D card to you r 2D ad ap ter, after wh ich you p lu g you r m on itor in to th e VGA p ort on th e Mon ster 3D card . Gam es an d an y oth er ap p lication s th at su p p ort th e Mon ster 3D can ad d ress th at d evice d irectly th rou gh th e PCI bu s, an d all of th e sign als gen erated by th e 2D ad ap ter p ass th rou gh th e Mon ster 3D card an d are relayed to th e m on itor. Video Out put Devices. W h en vid eo tech n ology was first in trod u ced , it was based on television . Th ere is a d ifferen ce between th e sign als u sed by a television an d th e sign als u sed by a com p u ter. In th e Un ited States, th e Nation al Television System Com m ittee (NTSC) establish ed color TV stan d ard s in 1953. Som e oth er cou n tries, su ch as Jap an , followed th is stan d ard . Man y cou n tries in Eu rop e d evelop ed m ore sop h isticated stan d ard s, in clu d in g Ph ase Altern ate Lin e (PAL) an d SEq u en tial Cou leu r Avec Mém oire (SECAM). Table 8.9 sh ows th e d ifferen ces am on g th ese stan d ard s.

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Table 8.9 St andard

Television Versus Com put er M onit ors Yr. Est .

Count ry

Lines

Rat e

1953 (color)

U.S., Japan

525

60Hz

Television NTSC

1941 (b& w) PAL

1941

Europe*

625

50Hz

SECAM

1962

France

625

25Hz

1987

U.S.

640 ×480**

72Hz

Com put er VGA

*England, Holland, W est Germ any. **V GA is based upon m ore lines and uses pixels (480) versus lines; genlocking is used to lock pixels into lines and synchronize com puters with TV standards.

A vid eo-ou tp u t (or VGA-to-NTSC) ad ap ter en ables you to d isp lay com p u ter screen s on a TV set or record th em on to vid eotap e for easy d istribu tion . Th ese p rod u cts fall in to two categories: th ose with genlocking (wh ich en ables th e board to syn ch ron ize sign als from m u ltip le vid eo sou rces or vid eo with PC grap h ics) an d th ose with ou t. Gen lockin g p rovid es th e sign al stability you n eed to obtain ad eq u ate resu lts wh en record in g to tap e, bu t is n ot n ecessary for u sin g a television as a vid eo d isp lay. VGA-to-NTSC con verters are available both as in tern al exp an sion board s or extern al boxes th at are p ortable en ou gh to u se with a lap top for p resen tation s on th e road . In d eed , m an y lap top an d n otebook system s th ese d ays com e eq u ip p ed with a bu ilt in VGAto-NTSC con verter. Th e con verter d oes n ot rep lace you r existin g vid eo ad ap ter bu t in stead con n ects to th e ad ap ter u sin g an extern al cable. In ad d ition to VGA in p u t an d ou tp u t p orts, a vid eo ou tp u t board h as a vid eo ou tp u t in terface for S-Vid eo an d com p osite vid eo. Most VGA-to-TV con verters su p p ort th e stan d ard NTSC television form at an d m ay also su p p ort th e Eu rop ean PAL form at. Th e resolu tion th at th ese d evices d isp lay on a TV set or record on vid eotap e is often lim ited to straigh t VGA at 640×480 p ixels. Th e con verter m ay also con tain an an ti-flicker circu it to h elp stabilize th e p ictu re, becau se VGA-to-TV p rod u cts often su ffer from a case of th e jitters. St ill-Im age Video Capt ure Cards. You can in stall a board in to you r PC th at en ables you to cap tu re in d ivid u al screen im ages for later ed itin g an d p layback. Th ere are also extern al d evices th at p lu g in to a PC’s p arallel p ort. Th ese u n its cap tu re still im ages from NTSC vid eo sou rces su ch as cam cord ers or VCRs. Alth ou gh im age q u ality is lim ited by th e in p u t sign al, th e resu lts are still good en ou gh for p resen tation s an d d esktop p u blish in g ap p lication s. Th ese d evices work with 8-, 16-, an d 24-bit VGA card s an d u su ally accep t vid eo in p u t from VHS, Su p er VHS, an d Hi-8 d evices. As you m igh t exp ect, h owever, Su p er VHS an d Hi-8 vid eo sou rces give better resu lts, as d o con figu ration s u sin g m ore th an 256 colors.

Video Display Adapters

M ult iple M onit ors. W in d ows 98 in clu d es a vid eo d isp lay featu re th at Macin tosh system s h ave h ad for years: th e cap ability to u se m u ltip le m on itors on on e system . W in d ows 98 su p p orts u p to n in e m on itors (an d vid eo ad ap ters), each of wh ich can p rovid e a d ifferen t view of th e d esktop . W h en you con figu re a W in d ows 98 system to d o th is, th e op eratin g system creates a virtual desktop; th at is, a d isp lay th at exists in vid eo m em ory th at can be larger th an th e im age actu ally d isp layed on a sin gle m on itor. You u se th e m u ltip le m on itors to d isp lay variou s p ortion s of th e virtu al d esktop , en ablin g you to p lace th e win d ows for d ifferen t ap p lication s on sep arate m on itors, an d m ove th em arou n d at will. Of cou rse, each m on itor th at you con n ect to th e system req u ires its own vid eo ad ap ter, so u n less you h ave n in e bu s slots free, th e p rosp ects of seein g a n in e-screen win d ows d isp lay are slim , for n ow. However, even two m on itors can be a boon to com p u tin g p rod u ctivity. On a m u lti-m on itor W in d ows 98 system , th ere is always on e d isp lay th at is con sid ered to be th e p rim ary d isp lay. Th e p rim ary d isp lay can u se an y PCI VGA vid eo ad ap ter th at u ses a W in d ows 98 m in id river with a lin ear fram e bu ffer an d a p acked (n on -p lan ar) form at, m ean in g th at m ost of th e bran d n am e ad ap ters sold tod ay are eligible. Ad d ition al m on itors are called secon d aries, an d are m u ch m ore lim ited in th eir h ard ware su p p ort. A secon d ary m u st u se on e of th e followin g vid eo ad ap ters: ■ Th e S3-ViRGE series ■ S3Trio-64V+ ■ S3 Au rora ■ Cirru s 5436, 5446, 7548 ■ ET6000 ■ ATI Mach 64, Rage I, II ■ Im agin e i128(2) It’s im p ortan t th at th e com p u ter correctly id en tify wh ich on e of th e vid eo ad ap ters is th e p rim ary. Th is is a fu n ction of th e system BIOS an d , if th e BIOS on you r com p u ter d oes n ot let you select wh ich d evice sh ou ld be th e p rim ary VGA d isp lay, th en it d ecid es based on th e ord er of th e PCI slots in th e m ach in e. You sh ou ld th erefore in stall th e p rim ary ad ap ter in th e h igh est p riority PCI slot. √√ See “ The PCI Bus,” p. 256

After th e h ard ware is in p lace, you can con figu re th e d isp lay for each m on itor from th e Disp lay Con trol Pan el’s Settin gs p age. Th e p rim ary d isp lay is always fixed in th e u p p erleft corn er of th e virtu al d esktop , bu t you can m ove th e secon d ary d isp lays to view an y area of th e d esktop you like. You can also set th e screen resolu tion an d color d ep th for each d isp lay in d ivid u ally.

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Deskt op Video ( DTV) Boards. You can also cap tu re NTSC (television ) sign als to you r com p u ter system for d isp lay or ed itin g. In oth er word s, you can literally watch TV in a win d ow on you r com p u ter. W h en cap tu rin g vid eo, you sh ou ld th in k in term s of d igital versu s an alog. Th e biggest con ven ien ce of an an alog TV sign al is efficien cy; it is a com p act way to tran sm it vid eo in form ation th rou gh a low-ban d wid th p ip elin e. Th e d isad van tage is th at wh ile you can con trol h ow th e vid eo is d isp layed , you can ’t ed it it. Actu ally cap tu rin g an d record in g vid eo from extern al sou rces an d savin g th e files on to you r PC req u ires sp ecial tech n ology. To d o th is, you n eed a d evice called a video capture board, also called a TV tuner, video digitizer, or video grabber.

Not e In this context, the technical nomenclature again becomes confusing, because the term video here has its usual connotation; that is, it refers to the display of full-motion photography on the PC monitor. When evaluating video hardware, be sure to distinguish between devices that capture still images from a video source, and those that capture full-motion video streams.

On e of th e u ses for an alog vid eo is with in teractive Com p u ter-Based Train in g (CBT) p rogram s in wh ich you r ap p lication sen d s start, stop , an d search com m an d s to a laserd isc p layer th at p lays d iscs you h ave m astered . Th e software con trols th e p layer via an in terface th at also con verts th e laserd isc’s NTSC sign al in to a VGA-com p atible sign al for d isp lay on you r com p u ter’s m on itor. Th ese typ es of ap p lication s req u ire NTSC-to-VGA con version h ard ware. W h ereas a com p u ter can d isp lay u p to 16 m illion colors, th e NTSC stan d ard allows for ap p roxim ately on ly 32,000 colors. Afford able, h igh -q u ality vid eo is th e Ach illes’ h eel of m u ltim ed ia. Th e im ages are often jerky or less th an fu ll-screen . Th e reason is becau se fu ll-m otion vid eo, su ch as th at wh ich you see on TV, req u ires 30 im ages or fram es p er secon d (fp s), wh ich can be an en orm ou s am ou n t of d ata. Th e typ ical com p u ter screen was d esign ed to d isp lay m ain ly static im ages. Th e storin g an d retrievin g of th ese im ages req u ires m an agin g h u ge files. Con sid er th is: A sin gle, fu llscreen color im age in an u n com p ressed form at can req u ire as m u ch as 2M of d isk sp ace; a on e-secon d vid eo wou ld th erefore req u ire 45M. Likewise, an y vid eo tran sm ission th at you wan t to cap tu re for u se on you r PC m u st be con verted from an an alog NTSC sign al to a d igital sign al th at you r com p u ter can u se. On top of th at, th e vid eo sign al m u st be m oved in sid e you r com p u ter at 10 tim es th e sp eed of th e con ven tion al ISA bu s stru ctu re. You n eed n ot on ly a su p erior vid eo card an d m on itor bu t also an excellen t exp an sion bu s, su ch as PCI or AGP. Con sid erin g th e fact th at fu ll-m otion vid eo can con su m e m assive q u an tities of d isk sp ace, it becom es ap p aren t th at d ata com p ression is all bu t essen tial. Com p ression an d d ecom p ression (or codec) ap p lies to both vid eo an d au d io. Not on ly d oes a com p ressed file take u p less sp ace, it also p erform s better; th ere is sim p ly less d ata to p rocess. W h en you are read y to rep lay th e vid eo/ au d io, th e ap p lication d ecom p resses th e file d u rin g

Video Display Adapters

p layback. In an y case, if you are goin g to work with vid eo, be su re th at you r h ard d rive is large en ou gh an d fast en ou gh to h an d le th e h u ge files th at can resu lt. Th ere are two typ es of cod ecs: hardware-dependent codecs an d software (or hardware-independent) codecs. Hard ware cod ecs typ ically p erform better; h owever, th ey req u ire ad d ition al h ard ware. Software cod es d o n ot req u ire h ard ware for com p ression or p layback, bu t th ey typ ically d o n ot d eliver th e sam e q u ality or com p ression ratio. Two of th e m ajor cod ec algorith m s are: ■ JPEG (Joint Photographic Experts Group). Origin ally d evelop ed for still im ages, JPEG can com p ress an d d ecom p ress at rates accep table for n early fu ll-m otion vid eo (30fp s). JPEG still u ses a series of still im ages, wh ich m akes ed itin g easier. JPEG is typ ically lossy (m ean in g th at a sm all am ou n t of th e d ata is lost d u rin g th e com p ression p rocess, sligh tly d im in ish in g th e q u ality of th e im age), bu t it can also be lossless. JPEG com p ression fu n ction s by elim in atin g red u n d an t d ata for each in d ivid u al im age (in trafram e). Com p ression efficien cy is ap p roxim ately 30:1 (20:1– 40:1). ■ MPEG (Motion Pictures Experts Group). MPEG by itself com p resses vid eo at ap p roxim ately a 30:1 ratio, bu t with p re-com p ression th rou gh oversam p lin g, th e ratio can clim b to 100:1 an d h igh er, wh ile retain in g h igh q u ality. Th u s, MPEG com p ression resu lts in better, faster vid eos th at req u ire less storage sp ace. MPEG is an in terfram e com p ressor. Becau se MPEG stores on ly in crem en tal ch an ges, it is n ot u sed d u rin g ed itin g p h ases. MPEG d ecod in g can be p erform ed in software on h igh -p erform an ce Pen tiu m system s. If you will be cap tu rin g, com p ressin g, an d p layin g vid eo, you will n eed Microsoft Vid eo for W in d ows (VFW ), wh ich is in clu d ed with th e W in d ows 9x an d NT op eratin g system s, or Qu ickTim e, wh ich is available as a free d own load from Ap p le’s W eb site. Th e followin g cod ecs are p rovid ed alon g with VFW : ■ Cinepak. Alth ou gh Cin ep ak can take lon ger to com p ress, it can p rod u ce better q u ality an d h igh er com p ression th an In d eo. It is also referred to as Com pact V ideo Coded (CV C). ■ Indeo. In d eo can ou tp erform Cin ep ak an d is cap able of real-tim e com p ression . An In tel Sm art Vid eo board is req u ired for real-tim e com p ression . ■ Microsoft V ideo 1. Develop ed by Med iaVision (MotiVE) an d ren am ed MS Vid eo 1, th is cod ec is a DCT-based p ost-p rocessor. A file is com p ressed after cap tu re. Man y oth er cod ecs are freely available from variou s ven d ors, p rovid in g su p p ort for oth er vid eo form ats. Man y of th e vid eo p lu g-in s th at work with W eb browsers su p p ly th eir cod ecs an d au tom atically in stall th em on you r system . If you look on th e Devices p age of th e W in d ows 98 Mu ltim ed ia Con trol Pan el (or th e Ad van ced p age in W in d ows 95) u n d er Vid eo Com p ression Cod ecs (see Figu re 8.4), you can view an d m an age th e cod ecs in stalled on you r com p u ter.

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FIG. 8.4 In th e W in d ows 9x Mu ltim ed ia Con trol Pan el, you can see th e vid eo com p ression cod ecs in stalled on you r system . To p lay or record vid eo on you r m u ltim ed ia PC (MPC), you will n eed som e extra h ard ware an d software: ■ Vid eo system software, su ch as Ap p le’s Qu ickTim e for W in d ows or Microsoft’s Vid eo for W in d ows. ■ A com p ression / d igitization vid eo ad ap ter th at en ables you to d igitize an d p lay large vid eo files. ■ An NTSC-to-VGA ad ap ter th at com bin es TV sign als with com p u ter vid eo sign als for ou tp u t to a VCR. Vid eo can com e from a variety of sou rces: TV, VCR, vid eo cam era, or laserd isc p layer. W h en you record an an im ation file, you can save it in a variety of d ifferen t file form ats: AVI (Au d io Vid eo In terleave), MOV (Ap p le Qu ickTim e form at), or MPG (MPEG form at). W h en you con n ect vid eo d evices, u se th e S-Vid eo (S-VHS) con n ector wh en ever available. Th is cable p rovid es th e best sign al becau se sep arate sign als are u sed for color (chrom a) an d brigh tn ess (lum a). Oth erwise, you will h ave to u se com posite video, wh ich m ixes lu m a an d ch rom a. Th is resu lts in a lower-q u ality sign al. Th e better you r sign al, th e better you r vid eo q u ality will be. You can also p u rch ase d evices th at d isp lay ju st NTSC sign als on you r com p u ter. Th e way th at m u ltim ed ia tech n ology is ad van cin g, you will soon n ot be able to tell wh eth er you are u sin g a com p u ter screen or a television . Digital vid eo, in -screen fillin g, an d fu llm otion color h as arrived on d esktop p latform s with titles, p layback board s, an d en cod in g eq u ip m en t. Soon , MPEG m ovie clip libraries will be th e n ext form of clip art on CD-ROM. Hard ware ad van ces su ch as th e MMX in stru ction s in corp orated in to th e Pen tiu m arch itectu re are h elp in g to m ake m otion vid eo m ore of a u sefu l reality rath er th an ju st a n ovelty.

Video Display Adapters

3D Graphics Accelerat ors Th e latest tren d in PC grap h ic d isp lay tech n ology is th e exp an d ed u se of th ree d im en sion al im ages. Th ree-d im en sion al—or 3D—im agery h as been u sed for years in th e com p u ter gam in g world , an d h as even m ad e its way in to bu sin ess com p u tin g. Sp read sh eet p rogram s su ch as Microsoft Excel h ave for years u sed 3D ch arts to d isp lay sp read sh eet d ata. Of cou rse, th e im ages are n ot tru ly th ree-d im en sion al, becau se th e m on itor screen is a 2-D m ed iu m , bu t software can p rod u ce 3D effects u sin g p ersp ective, textu res, an d sh ad in g. Abstract sh ap es su ch as Excel’s 3D bar grap h s are n ot d ifficu lt to p rod u ce, becau se th ey con sist solely of p olygon s an d oth er sh ap es with solid color fills of variou s sh ad es. You fin d th e tru ly in n ovative sid e of 3D grap h ics in th e so-called virtu al reality en viron m en ts created in gam es an d oth er ap p lication s. As with oth er typ es of m u ltim ed ia, h owever, th e tech n iq u es th at origin ate in gam es an d oth er en tertain m en t software will even tu ally be assim ilated in to m ain stream u se. A 3D im age can con tain an im m en se am ou n t of d etail, an d an an im ated 3D seq u en ce like th ose of m an y gam es req u ires a great m an y im ages. Obviou sly, th e m ore im ages th at are n eed ed , th e m ore d isk sp ace is req u ired to store th em , an d th e m ore p rocessin g an d im age-h an d lin g sp eed is n eed ed to d isp lay th em . To m an age all th at d etail, 3D ap p lication s u su ally store an d work with abstraction s of th e im ages, rath er th an th e actu al im ages th em selves. In essen ce, th e 3D im ages are actu ally gen erated —or rendered—as n eed ed , rath er th an sim p ly read from a storage m ed iu m . To con stru ct an an im ated 3D seq u en ce, a com p u ter can m ath em atically an im ate th e seq u en ces between keyfram es. A keyfram e id en tifies sp ecific p oin ts. A bou n cin g ball, for exam p le, can h ave th ree keyfram es: u p , d own , an d u p . Usin g th ese fram es as a referen ce p oin t, th e com p u ter can create all th e in terim im ages between th e top an d th e bottom . Th is creates th e effect of a sm ooth bou n cin g ball. After it h as created th e basic seq u en ce, th e system can th en refin e th e ap p earan ce of th e im ages by fillin g th em in with color. Th e m ost p rim itive an d least effective fill m eth od is called flat shading, in wh ich a sh ap e is sim p ly filled with a solid color. Gouraud shading, a sligh tly m ore effective tech n iq u e, in volves th e assign m en t of colors to sp ecific p oin ts on a sh ap e. Th e p oin ts are th en join ed u sin g a sm ooth grad ien t between th e colors. Th e m ost p rocessor in ten sive, an d by far th e m ost effective typ e of fill, is called texture m apping. Th e 3D ap p lication in clu d es p attern s—or textu res—in th e form of sm all bitm ap s th at it tiles on to th e sh ap es in th e im age, ju st as you can tile a sm all bitm ap to form th e wallp ap er for you r W in d ows d esktop . Th e p rim ary d ifferen ce is th at th e 3D ap p lication can m od ify th e ap p earan ce of each tile by ap p lyin g p ersp ective an d sh ad in g to ach ieve 3D effects. Un til recen tly, 3D ap p lication s h ad to rely on su p p ort from software rou tin es to con vert th ese abstraction s in to live im ages. Th is p laces a h eavy bu rd en on th e system p rocessor in th e PC, wh ich h as a sign ifican t im p act on th e p erform an ce n ot on ly of th e visu al d isp lay, bu t also of an y oth er ap p lication s th at th e com p u ter m ay be ru n n in g. Now, th ere is a n ew breed of vid eo accelerator ch ip sets fou n d on m an y vid eo ad ap ters th at can

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take on a lot of th e tasks in volved in ren d erin g 3D im ages, greatly lessen in g th e load on th e system p rocessor an d overall system p erform an ce. Prices are d rop p in g rap id ly on th ese 3D accelerators an d m ore an d m ore software titles are m akin g u se of th em . Tech n ology th at was on ce available on ly on h igh -en d grap h ics workstation s is n ow available on PCs. By ren d erin g im ages righ t on th e ad ap ter, 3D grap h ics accelerator ad ap ters can create sm ooth , p h oto-realistic 3D im ages on a PC at sp eed s th at rival th ose of low-en d grap h ics workstation s. 3D tech n ology h as ad d ed an en tirely n ew vocabu lary to th e world of vid eo d isp lay ad ap ters. Before p u rch asin g a 3D accelerator ad ap ter, it is a good id ea to fam iliarize you rself with th e som e of th e term s an d con cep ts in volved in th e 3D im age gen eration p rocess. Th e basic fu n ction of 3D software is to con vert im age abstraction s in to th e fu lly realized im ages th at are th en d isp layed on th e m on itor. Th e im age abstraction s typ ically con sist of th e followin g elem en ts: ■ V ertices. Location s of objects in th ree d im en sion al sp ace, d escribed in term s of th eir X, Y, an d Z coord in ates on th ree axes rep resen tin g h eigh t, wid th , an d d ep th . ■ Prim itives. Th e sim p le geom etric objects th at th e ap p lication u ses to create m ore com p lex con stru ction s, d escribed in term s of th e relative location s of th eir vertices. Th is serves n ot on ly to sp ecify th e location of th e object in th e 2D im age, bu t also p rovid es p ersp ective, as th e th ree axes can d efin e an y location in th reed im en sion al sp ace. ■ Textures. Two-dim en sion al bitm ap im ages or su rfaces th at are design ed to be m apped on to prim itives. Th e software en h an ces th e 3D effect by m odifyin g th e appearan ce of th e textu res depen din g on th e location an d attitu de of th e prim itive; th is process is called perspective correction. Som e application s u se an oth er process called MIP m apping, wh ich u tilizes differen t version s of th e sam e textu re th at con tain varyin g am ou n ts of detail, depen din g on h ow close th e object is to th e viewer in th e th reedim en sion al space. An oth er tech n iqu e, called depth cueing, redu ces th e color an d in ten sity of an object’s fill as th e object m oves farth er away from th e viewer. Usin g th ese elem en ts, th e abstract im age d escrip tion s m u st th en be rendered, m ean in g th at th ey are con verted to visible form . Ren d erin g d ep en d s on two stan d ard ized fu n ction s th at con vert th e abstraction s in to th e com p leted im age th at is d isp layed on screen . Th e stan d ard fu n ction s p erform ed in ren d erin g are: ■ Geom etry. Th e sizin g, orien tin g, an d m ovin g of p rim itives in sp ace an d th e calcu lation of th e effects p rod u ced by th e virtu al ligh t sou rces th at illu m in ate th e im age. ■ Rasterization. Th e con vertin g of prim itives in to pixels on th e video display by fillin g th e sh apes with properly illu m in ated sh adin g, textu res, or a com bin ation of th e two. A m od ern vid eo ad ap ter th at in clu d es a ch ip set cap able of 3D vid eo acceleration will h ave sp ecial bu ilt-in h ard ware th at can p erform th e rasterization p rocess m u ch faster th an if it is d on e by software (u sin g th e system p rocessor) alon e. Most ch ip sets with 3D acceleration p erform th e followin g rasterization fu n ction s righ t on th e ad ap ter:

Video Display Adapters

■ Scan conversion. Th e d eterm in ation of wh ich on screen p ixels fall in to th e sp ace d elin eated by each p rim itive. ■ Shading. Th e p rocess of fillin g p ixels with sm ooth ly flowin g color u sin g th e flat or Gou rau d sh ad in g tech n iq u e. ■ Texturing. Th e p rocess of fillin g p ixels with im ages d erived from a 2D sam p le p ictu re or su rface im age. ■ V isible surface determ ination. Th e id en tification of wh ich p ixels in a scen e are obscu red by oth er objects closer to th e viewer in th ree-d im en sion al sp ace. ■ Anim ation. Th e p rocess of switch in g rap id ly an d clean ly to su ccessive fram es of m otion seq u en ces. Com p ared to software-on ly ren d erin g, h ard ware-accelerated ren d erin g p rovid es better im age q u ality an d faster an im ation th an with software alon e. Usin g sp ecial d rivers, th ese 3D ad ap ters can take over th e in ten sive calcu lation s n eed ed to ren d er a 3D im age th at were form erly p erform ed by software ru n n in g on th e system p rocessor. Th is is p articu larly u sefu l if you are creatin g you r own 3D im ages an d an im ation s, bu t it is also a great en h an cem en t to th e m an y m od ern gam es th at rely exten sively on 3D effects. 3D Chipset s. As with stan d ard 2D vid eo ad ap ters, th ere are several m an u factu rers of p op u lar 3D vid eo ch ip sets, an d m an y m ore m an u factu rers of vid eo ad ap ters th at u se th em . Table 8.10 lists th e m ajor 3D ch ip set m an u factu rers, th e variou s ch ip sets th ey m ake, an d th e vid eo ad ap ters th at u se th em . Table 8.10

3D Video Chipset M anufact urers

M anufact urer

Chipset

Available Boards

3Dfx Interactive

Voodoo Graphics(3D only)

A-Trend Helios 3D Canopus Pure 3D Deltron Flash 3D Diamond M onster 3D Guillemot M AXI Gamer 3Dfx Orchid Righteous 3D Quantum 3D Obsidian series Skywell M agic 3D

3Dfx Interactive

Voodoo Rush (2D/ 3D)

California Graphics Emotion 3D Deltron Flash AT3D Rush Hercules Stingray 128/ 3D Intergraph Intense 3D Jazz Adrenaline Rush Viewtop Rush 3D

3D labs

Permedia 2 (2D/ 3D)

Creative G.B. Extreme Diamond FireGL 1000Pro (continues)

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Table 8.10

Cont inued

M anufact urer

Chipset

Available Boards

ATi

RAGE PRO TURBO (2D/ 3D)

ALL-IN-WONDER PRO

ATi

RAGE II+ (2D/ 3D)

3D XPRESSION+

ATi

3D RAGE II+DVD (2D/ 3D)

3D PRO TURBO PC2TV

nVidia

RIVA 128(2D/ 3D)

ASUS 3D Explorer

XPERT@PLAY 98

Canopus Total 3D 128V Diamond Viper330 Elsa Erazor Victory STB Velocity 128 Rendition

Vérité 2100(2D/ 3D)

Diamond Stealth S220

Rendition

Vérité 2200(2D/ 3D)

DSystems Gladiator Hercules Thriller 3D Jazz Outlaw 3D

S3

ViRGE (2D/ 3D)

Cardex Genesis SV

Dataexpert Expertcolor DSV3325P Diamond Stealth 3D 2000 Pro Elsa Victory 3D Expert EVP ViRGE Genoa Phantom 3D Hercules Terminator 64/ 3D Number Nine 9FX Reality 332 Orchid Fahrenheit Video3D STB Powergraph 64 3D VideoLogic/ NEC

PowerVR PCX2(3D only)

M atrox m3D VideoLogic 3Dx VideoLogic 5D VideoLogic 5D Sonic

Adapt er and Display Troubleshoot ing Solvin g m ost grap h ics ad ap ter an d m on itor p roblem s is fairly sim p le, alth ou gh costly, becau se rep lacin g th e ad ap ter or d isp lay is th e u su al p roced u re. However, before you take th is step , m ake su re th at you h ave exh au sted all of you r oth er op tion s. On e em barrassin gly obviou s fix to m on itor d isp lay p roblem s th at is often overlooked by m an y u sers is to ad ju st th e con trols on th e m on itor, su ch as th e con trast an d th e brigh tn ess. W h ile m ost m on itors tod ay h ave a con trol p an el on th e fron t of th e u n it, oth er ad ju stm en ts m ay be p ossible as well. Som e NEC m on itors, for exam p le, h ave a focu s ad ju stm en t screw on th e left sid e of th e u n it. Becau se th e screw is d eep in sid e th e case, th e on ly evid en ce of its existen ce is a h ole in th e p lastic grillwork on top of it. To ad ju st th e m on itor’s focu s, you h ave to stick a lon g-sh an ked screwd river abou t two in ch es in to th e h ole an d feel arou n d for th e screw

Adapter and Display Troubleshooting

h ead . Th is typ e of ad ju stm en t can save you both an exp en sive rep air bill an d th e h u m iliation of bein g rid icu led by th e rep air tech n ician . Always exam in e th e m on itor case, th e d ocu m en tation , an d th e m an u factu rer’s W eb site or oth er on lin e services for th e location s of ad ju stm en t con trols. A d efective or d ysfu n ction al ad ap ter or d isp lay u su ally is rep laced as a sin gle u n it, rath er th an rep aired . Most of tod ay’s ad ap ters cost m ore to service th an to rep lace, an d th e d ocu m en tation req u ired to service th e h ard ware p rop erly is n ot always available. You u su ally can n ot get sch em atic d iagram s, p arts lists, wirin g d iagram s, an d oth er d ocu m en ts for m ost ad ap ters or m on itors. Also, m an y ad ap ters n ow are con stru cted with su rfacem ou n t tech n ology th at req u ires a su bstan tial in vestm en t in a rework station before you can rem ove an d rep lace th ese com p on en ts by h an d . You can n ot u se a $25 p en cil-typ e sold erin g iron on th ese board s! Servicin g m on itors is a sligh tly d ifferen t p rop osition . Alth ou gh a d isp lay often is rep laced as a wh ole u n it, m an y d isp lays are too exp en sive to rep lace. You r best bet is to eith er con tact th e com p an y from wh ich you p u rch ased th e d isp lay, or to con tact on e of th e com p an ies th at sp ecializes in m on itor d ep ot rep air. Depot repair m ean s th at you sen d in you r d isp lay to rep air sp ecialists wh o eith er fix you r p articu lar u n it or retu rn an id en tical u n it th ey h ave alread y rep aired . Th is is n orm ally accom p lish ed for a flat-rate fee; in oth er word s, th e p rice is th e sam e n o m atter wh at th ey h ave d on e to rep air you r actu al u n it. Becau se you will u su ally get a d ifferen t (bu t id en tical) u n it in retu rn , th ey can sh ip ou t you r rep aired d isp lay im m ed iately on receivin g th e on e you sen t in , or even in ad van ce in som e cases. Th is way, you h ave th e least am ou n t of d own tim e, an d can receive th e rep aired d isp lay as q u ickly as p ossible. In som e cases, if you r p articu lar m on itor is u n iq u e or on e th ey d on ’t h ave in stock, th en you will h ave to wait wh ile th ey rep air you r sp ecific u n it. Trou blesh ootin g a failed m on itor is relatively sim p le. If you r d isp lay goes ou t, for exam p le, a swap with an oth er m on itor can con firm th at th e d isp lay is th e p roblem . If th e p roblem d isap p ears wh en you ch an ge th e d isp lay, th e p roblem is alm ost certain ly in th e origin al d isp lay or th e cable; if th e p roblem rem ain s, it is likely in th e vid eo ad ap ter or PC itself. Th e m on itor cable can som etim es be th e sou rce of d isp lay p roblem s. A ben t p in in th e DB-15 con n ector th at p lu gs in to th e vid eo ad ap ter can p reven t th e m on itor from d isp layin g im ages. Most of th e tim e, you can rep air th e con n ector by carefu lly straigh ten in g th e ben t p in with sh arp -n osed p liers. If th e p in breaks off, or th e con n ector is oth erwise d am aged , you can som etim es rep lace th e m on itor cable. Som e m on itor m an u factu rers u se cables th at d iscon n ect from th e m on itor an d th e vid eo ad ap ter, wh ereas oth ers are p erm an en tly con n ected . Dep en d in g on th e typ e of con n ector th e d evice u ses at th e m on itor en d , you m ay h ave to con tact th e m an u factu rer for a rep lacem en t. If you n arrow d own th e p roblem to th e d isp lay, con su lt th e d ocu m en tation th at cam e with th e m on itor or call th e m an u factu rer for th e location of th e n earest factory rep air

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d ep ot. Th ere are also altern ative th ird -p arty d ep ot rep air service com p an ies th at can rep air m ost d isp lays (if th ey are n o lon ger covered by a warran ty); th eir p rices often are m u ch lower th an factory service. Ch eck th e ven d or list in Ap p en d ix A for several com p an ies wh o d o d ep ot rep air of com p u ter m on itors an d d isp lays.

Caut ion You should never attempt to repair a CRT monitor yourself. Touching the wrong component can be fatal. The display circuits can hold extremely high voltages for hours, days, or even weeks after the power is shut off. A qualified service person should discharge the cathode ray tube and power capacitors before proceeding.

For m ost d isp lays, you are lim ited to m akin g sim p le ad ju stm en ts. For color d isp lays, th e ad ju stm en ts can be q u ite form id able if you lack exp erien ce. Even factory service tech n ician s often lack p rop er d ocu m en tation an d service in form ation for n ewer m od els; th ey u su ally exch an ge you r u n it for an oth er an d rep air th e d efective on e later. Never bu y a d isp lay for wh ich n o local factory rep air d ep ot is available. If you h ave a problem with a display or adapter, it pays to call th e m an ufacturer wh o m igh t kn ow about th e problem an d m ake repairs available. Som etim es, wh en m an ufacturers en coun ter n um erous problem s with a product, th ey m ay offer free repair, replacem en ts, or an oth er gen erous offer th at you would n ever kn ow about if you did n ot call. Rem em ber also th at m an y of th e p roblem s you m ay en cou n ter with m od ern vid eo ad ap ters an d d isp lays are related to th e d rivers th at con trol th ese d evices, rath er th an to th e h ard ware. Be su re you h ave th e latest an d p rop er d rivers before you attem p t to h ave th e h ard ware rep aired ; th ere m ay alread y be a solu tion available.

DisplayM at e DisplayM ate is a unique diagnostic and testing program designed to thoroughly test your video

adapter and display. It is somewhat unique in that most conventional PC hardware diagnostics programs do not emphasize video testing as this program does. I find it useful not only in testing if a video adapter is functioning properly, but also in examining video displays. You can easily test the image quality of a display, which allows you to make focus, centering, brightness and contrast, color level, and other adjustments much more accurately than before. If you are purchasing a new monitor, you can use the program to evaluate the sharpness and linearity of the display, and to provide a consistent way of checking each monitor that you are considering. If you use projection systems for presentations as I do in my PC hardware seminars, you will find it invaluable for setting up and adjusting the projector. DisplayM ate can also test a video adapter thoroughly. It will set the video circuits into each possible video mode, so you can test all of its capabilities. It will also help you to determine the performance level of your card, both with respect to resolution and colors as well as to speed. You can then use the program to benchmark the performance of the display, which enables you to compare one type of video adapter system to another. See the vendor list in Appendix A for more information on Sonera Technologies, the manufacturer and distributor of DisplayM ate.

Chapter 9

Audio Hardware

9

W h en th e PC was first created , it d id n ot in clu d e au d io cap abilities oth er th an ru d im en tary beep in g or ton e gen eration . Part of th e reason for th is was th at th e PC stan d ard origin ated in ’81, an d m ost of th e oth er com p u ters of th at tim e h ad sim ilar ru d im en tary cap abilities. An oth er reason was th at th ere really were n o im p ortan t ap p lication s for an yth in g oth er th an th e m ost basic sou n d s. Com p u ters u sed beep s to sign al p roblem s su ch as a fu ll keyboard bu ffer or errors d u rin g th e POST (p ower on self test) seq u en ce an d little else. System s th at were d esign ed later, su ch as th e Macin tosh th at d ebu ted in ’84, d id in clu d e h igh -q u ality au d io cap abilities as an in tegral p art of th e system h ard ware an d software. Alth ou gh th ere still is n o u n iversal au d io h ard ware an d software stan d ard for PC-com p atible system s, th e in h eren t exp an d ability of th e PC p latform en ables u sers to easily ad d au d io cap ability to existin g system s, an d at least on e d e facto au d io stan d ard h as em erged . Tod ay’s PC au d io h ard ware u su ally takes th e form of an au d io ad ap ter on an exp an sion card th at you in stall in to a bu s slot in th e com p u ter. As with vid eo ad ap ters, som e system s tod ay in clu d e th e au d io h ard ware d irectly on th e m oth erboard . Th e ad ap ter p rovid es jacks for sp eakers, a m icrop h on e, an d som etim es oth er d evices su ch as joysticks an d MIDI h ard ware. On th e software sid e, th e au d io ad ap ter req u ires th e su p p ort of a d river th at you in stall eith er d irectly from an ap p lication or in you r com p u ter’s op eratin g system . Th is ch ap ter focu ses on th e au d io p rod u cts fou n d in tod ay’s PCs, th eir u ses, an d h ow you in stall an d op erate th em .

Audio Adapt er Applicat ions At first, con su m er au d io ad ap ters were u sed on ly for gam es. Several com p an ies, in clu d in g Ad LiB, Rolan d , an d Creative Labs, released p rod u cts by th e late ’80s. In ’89, Creative Labs in trod u ced th e Gam e Blaster, wh ich p rovid ed stereo sou n d to a h an d fu l of com p u ter gam es. Th e q u estion for m an y bu yers was: “W h y sp en d $100 for a card th at ad d s sou n d to a $50 gam e?” More

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im p ortan tly, becau se n o sou n d stan d ard s existed at th e tim e, th e sou n d card you selected m igh t tu rn ou t to be u seless with oth er gam es.

Not e About the same time as the release of the Game Blaster, hardware supporting the M usical Instrument Digital Interface (M IDI) became available for the PC. At this time, however, such hardware was used only in very specialized recording applications. As M IDI support became a more common feature in musical instruments, it also became a more affordable PC add-on.

A few m on th s after releasin g th e Gam e Blaster, Creative Labs an n ou n ced th e Sou n d Blaster au d io ad ap ter. Th e Sou n d Blaster was com p atible with th e Ad LiB sou n d card an d Creative Labs’ own Gam e Blaster card . It in clu d ed a bu ilt-in m icrop h on e jack an d a MIDI p ort for con n ectin g th e PC to a syn th esizer or oth er electron ic m u sical in stru m en t. Fin ally, th e au d io ad ap ter h ad th e p oten tial for u ses oth er th an gam es. Un fortu n ately, as in ’89, th ere is still n o official stan d ard for PC au d io ad ap ters. In m an y areas of th e com p u ter in d u stry, stan d ard s often evolve in form ally d u e to th e wid esp read accep tan ce of th e m arket lead er’s p rod u cts in a p articu lar segm en t of th e m arketp lace. Th ese are called de facto standards, as con trasted with de jure standards, wh ich are officially ratified by th e m an u factu rers in volved in th e d evelop m en t p rocess. For exam p le, Hewlett-Packard p rin ters u se a p age d escrip tion lan gu age called PCL th at h as becom e a d e facto stan d ard becau se a great m an y of th eir p rin ters h ave been sold an d m ost software su p p orts th em . Oth er p rin ter m an u factu rers th en strive to create p rod u cts th at em u late th e Hewlett-Packard p rin ters so th at th ey d on ’t req u ire u n iq u e com m an d s an d can u se th e sam e d rivers as a Hewlett-Packard p rin ter. Th is is h ow a d e facto stan d ard is born . Th e p rocess is essen tially based on p op u larity an d econ om ic factors. Alth ou gh oth er stan d ard s for p age d escrip tion lan gu ages exist, Hewlett-Packard ’s stan d ard is su p p orted by m ost PC-com p atible p rin ters becau se failu re to su p p ort it wou ld all bu t gu aran tee a m arketin g d isaster. Over th e p ast few years, som e m an u factu rers of au d io ad ap ters h ave fou gh t for d om in an ce over th e m arket, an d th ere are several p op u lar bran d s. However, th ere is n o q u estion th at th e lead er in th e field is Creative Labs, wh ose Sou n d Blaster au d io ad ap ters d om in ate th e m arketp lace an d h ave becom e th e d e facto stan d ard for th e in d u stry. As a resu lt, virtu ally all th e au d io ad ap ters on th e m arket tod ay em u late th e Creative Labs Sou n d Blaster. As with th e Hewlett-Packard p rin ter stan d ard , th e Creative Labs Sou n d Blaster in terface is th e on e th at m ost h ard ware p rod u cts em u late, an d th e on e for wh ich m ost d rivers are written . Failu re to su p p ort th is d e facto stan d ard wou ld be all bu t su icid al for a com m ercial au d io ad ap ter p rod u ct. Tod ay, au d io ad ap ters h ave m an y u ses, in clu d in g th e followin g: ■ Ad d in g stereo sou n d to m u ltim ed ia en tertain m en t (gam e) software ■ In creasin g th e effectiven ess of ed u cation al software, p articu larly for you n g ch ild ren

Audio Adapter Applications

■ Ad d in g sou n d effects to bu sin ess p resen tation s an d train in g software ■ Creatin g m u sic by u sin g MIDI h ard ware an d software ■ Ad d in g voice n otes to files ■ Au d iocon feren cin g an d n etwork telep h on y ■ Ad d in g sou n d effects to op eratin g system even ts ■ En ablin g a PC to read ■ En ablin g PC u se by h an d icap p ed in d ivid u als ■ Playin g au d io CDs Gam es As with oth er m u ltim ed ia tech n ologies, au d io ad ap ters were origin ally d esign ed to p lay gam es. In fact, m an y ad ap ters in clu d e a gam e adapter interface, wh ich is a con n ector for ad d in g a gam e con trol d evice (u su ally a joystick or con trol p ad d les). Som e ad ap ters also u se th is in terface to con n ect a p lu g p rovid in g a MIDI con n ector. Th e gam e p ort is a p oten tial area of con flict becau se oth er card s, su ch as th e m u lti-I/ O typ e card s th at m an y PCs u se to p rovid e serial an d p arallel p orts, also h ave a gam e in terface. Th is can resu lt in an I/ O p ort ad d ress con flict becau se m ost gam e in terfaces u se th e sam e I/ O p ort ad d resses. In th ese cases, it is u su ally best to u se th e gam e ad ap ter in terface on th e au d io ad ap ter an d d isable an y oth er in you r system , esp ecially if you p lan to u se MIDI d evices. By ad d in g an au d io ad ap ter, gam e p layin g takes on a n ew d im en sion . Sou n d ad d s a level of realism th at wou ld oth erwise be im p ossible, even with th e best grap h ics. For exam p le, som e gam es u se d igitized h u m an voices or real record ed d ialog. In ad d ition to realistic sou n d s an d effects, gam es can also h ave m u sical scores, wh ich ad d to th e excitem en t an d en tertain m en t. M ult im edia A sou n d card is a p rereq u isite if you wan t to tu rn you r PC in to a Multim edia PC (MPC). W h at is m u ltim ed ia? Th e term em braces a n u m ber of PC tech n ologies, bu t p rim arily d eals with vid eo, sou n d , an d storage. Basically, PC m u ltim ed ia m ean s th e cap ability to m erge im ages, d ata, an d sou n d on a com p u ter in to a u n ified p ercep tu al exp erien ce. In a p ractical sen se, m u ltim ed ia u su ally m ean s ad d in g an au d io ad ap ter an d a CD-ROM d rive to you r system . An organ ization called th e Mu ltim ed ia PC (MPC) Marketin g Cou n cil was origin ally form ed by Microsoft to gen erate stan d ard s for MPCs. Th ey h ave created several MPC stan d ard s an d licen se th eir logo an d trad em ark to m an u factu rers wh ose h ard ware an d software con form to th ese stan d ard s. More recen tly, th e MPC Marketin g Cou n cil form ally tran sferred resp on sibility for th eir stan d ard s to th e Software Pu blish ers Association ’s Mu ltim ed ia PC W orkin g Grou p . Th is grou p in clu d es m an y of th e sam e m em bers as th e origin al MPC, an d is n ow th e bod y govern in g th e MPC sp ecification s. Th e first th in g th is grou p d id was create a n ew MPC stan d ard .

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Th e MPC Marketin g Cou n cil origin ally d evelop ed two p rim ary stan d ard s for m u ltim ed ia. Th ey are called th e MPC Level 1 an d MPC Level 2 stan d ard s. Now u n d er th e d irection of th e Software Pu blish ers Association (SPA), th ese first two stan d ard s h ave been au gm en ted by a th ird stan d ard called MPC Level 3, wh ich was in trod u ced in Ju n e 1995. Th ese stan d ard s d efin e th e m in im u m cap abilities for an MPC. Table 9.1 sh ows th ese stan d ard s. Table 9.1

M ult im edia St andards M PC Level 1

M PC Level 2

M PC Level 3

Processor

16M Hz 386SX

25M Hz 486SX

75M Hz Pentium

RAM

2M

4M

8M

Hard disk

30M

160M

540M

Floppy disk

1.44M 3 1/ 2-inch

1.44M 3 1/ 2-inch

1.44M 3 1/ 2-inch

CD-ROM drive

Single-speed

Double-speed

Quad-speed

Audio

8-bit

16-bit

16-bit

VGA video

640 ×480

640×480

640×480

Resolution

16K colors

64K colors

64K colors

Other I/ O

Serial, Parallel, M IDI, Game

Serial, Parallel, M IDI, Game

Serial, Parallel, M IDI, Game

Software

M icrosoft Windows 3.1

M icrosoft Windows 3.1

M icrosoft Windows 3.1

Date introduced

1990

M ay 1993

June 1995

Th e MPC-3 sp ecification s sh ou ld be con sid ered th e absolu te bare m in im u m s for an y m u ltim ed ia system . In fact, m ost of th e n ew com p u ters sold tod ay exceed th e Level 3 sp ecification by a su bstan tial m argin in alm ost every area. W ith W in d ows 95 or 98 as th e stan d ard op eratin g system , I wou ld n orm ally recom m en d a system th at in clu d es at least 32M of RAM, a 200MHz Pen tiu m p rocessor, an d 2G of h ard d rive sp ace. A faster CDROM d rive an d a h igh er vid eo resolu tion also en h an ce th e m u ltim ed ia exp erien ce. Note th at alth ou gh sp eakers or h ead p h on es are tech n ically n ot a p art of th e MPC sp ecification , th ey are certain ly req u ired for sou n d rep rod u ction . In ad d ition to h ard ware sp ecification s, th e MPC sp ecification s also d efin e th e au d io cap abilities of a m u ltim ed ia system . Th ese cap abilities m u st in clu d e d igital au d io record in g an d p layback (lin ear PCM sam p lin g), m u sic syn th esis, an d au d io m ixin g. Sound Files You can u se two basic typ es of files to store au d io on you r PC. On e typ e is gen erically called a sound file an d u ses form ats like W AV, VOC, AU, an d AIFF. Sou n d files con tain waveform data, wh ich m ean s th ey are an alog au d io record in gs th at h ave been d igitized for storage on a com p u ter. Ju st as you can store grap h ic im ages at d ifferen t resolu tion s, you can h ave sou n d files th at u se variou s resolu tion s, trad in g off sou n d q u ality for file size. Th e th ree d efau lt sou n d resolu tion levels u sed in W in d ows 9x are sh own in Table 9.2.

Audio Adapter Applications

Table 9.2

W indow s 9x Sound File Resolut ions

Resolut ion

Frequency

Bandw idt h

File Size

Telephone quality

11,025Hz

8-bit mono

11K/ sec

Radio quality

22,050Hz

8-bit mono

22K/ sec

CD quality

44,100Hz

16-bit stereo

172K/ sec

As you can see, th e d ifferen ce in file sizes between th e h igh est an d lowest au d io resolu tion levels is su bstan tial. CD q u ality sou n d files can occu p y en orm ou s am ou n ts of d isk sp ace. At th is rate, ju st 60 secon d s of au d io wou ld req u ire over 10M of storage. For ap p lication s th at d on ’t req u ire or ben efit from su ch h igh resolu tion , su ch as voice an n otation , telep h on e q u ality au d io is su fficien t, an d gen erates m u ch sm aller files. M IDI Files Th e secon d typ e of au d io file is a MIDI file, wh ich is as d ifferen t from a W AV as a vector grap h ic is from a bitm ap . MIDI files, wh ich u se MID or RMI exten sion s, are wh olly d igital files th at d o n ot con tain record in gs of sou n d ; in stead , th ey con tain th e in stru ction s th at th e au d io h ard ware u ses to create th e sou n d . Ju st as 3D vid eo ad ap ters u se in stru ction s an d textu res to create im ages for th e com p u ter to d isp lay, MIDI-cap able au d io ad ap ters u se MIDI files to syn th esize m u sic. MIDI is a p owerfu l p rogram m in g lan gu age d evelop ed in th e ’80s to p erm it electron ic m u sical in stru m en ts to com m u n icate. MIDI was th e breakth rou gh stan d ard in th e electron ic m u sic in d u stry, an in d u stry th at to th is d ay sh u n s n early all attem p ts at h ard ware stan d ard ization in favor of p rop rietary system s. W ith MIDI you can create, store, ed it, an d p lay back m u sic files on you r com p u ter eith er in tan d em with a MIDI-com p atible electron ic m u sical in stru m en t, typ ically a keyboard syn th esizer, or with ju st th e com p u ter. Un like th e oth er typ es of sou n d files, MIDI m essages req u ire relatively little storage sp ace. An h ou r of stereo m u sic stored in MIDI form at req u ires less th an 500K. Man y gam es u se MIDI sou n d s in stead of record ed on es to su p p ly large am ou n ts of m u sic wh ile con servin g d isk sp ace. Becau se th ey are n ot record in gs, th e u se of variou s resolu tion s d oes n ot ap p ly to MIDI files. A MIDI file is actu ally a d igital rep resen tation of a m u sical score. It is com p osed of a collection of sep arate channels, each of wh ich rep resen ts a d ifferen t m u sical in stru m en t or typ e of sou n d . Each ch an n el sp ecifies th e freq u en cies an d d u ration of th e n otes to be “p layed ” by th at in stru m en t, ju st like a p iece of sh eet m u sic d oes. Th u s, a MIDI file of a strin g q u artet con tain s fou r ch an n els, rep resen tin g two violin s, a viola, an d a cello.

Not e M IDI files are not intended to be a replacement for sound files such as WAVs; they should be considered a complementary technology. The biggest drawback of M IDI is that the playback technology is limited to sounds that are readily synthesizable. The most obvious shortcoming is (continues)

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(continued) that M IDI files are incapable of producing voices (except for synthesized choir effects). Therefore, when you download a M IDI file of your favorite song from the Internet, you’ll have to do the singing.

All th ree of th e MPC sp ecification s call for all au d io ad ap ters to su p p ort MIDI. Th e gen eral MIDI stan d ard u sed by m ost of th e au d io ad ap ters on th e m arket allows for u p to 16 ch an n els in a sin gle MIDI file, bu t th is d oes n ot n ecessarily lim it you to 16 in stru m en ts. A sin gle ch an n el can rep resen t th e sou n d of a grou p of in stru m en ts, su ch as a violin section , en ablin g you to syn th esize an en tire orch estra. Becau se MIDI files con sist of d igital in stru ction s, you can ed it th em m u ch m ore easily th an you can a sou n d file su ch as a W AV file. W ith th e ap p rop riate software, you can select an y ch an n el of a MIDI file an d ch an ge th e n otes, th e in stru m en t u sed to p lay th em , an d m an y oth er attribu tes th at affect th e sou n d th e PC p rod u ces. Som e software p ackages can even p rod u ce a m an u scrip t of th e m u sic in a MIDI file by u sin g stan d ard m u sical n otation . A com p oser can write a p iece of m u sic d irectly on th e com p u ter, ed it it as n eed ed , an d th en p rin t ou t sh eet m u sic for live m u sician s to read . Th is is an en orm ou s ben efit for p rofession al m u sician s wh o, th rou gh ou t h istory, h ave h ad to eith er em p loy m u sic cop yists or p u blish ers or sp en d lon g h ou rs cop yin g m u sic by h an d . Playing M IDI Files. W h en you p lay a MIDI file on you r PC, you are n ot p layin g back a record in g. You r system is actu ally creatin g m u sic from scratch . To d o th is, th e com p u ter req u ires a syn th esizer, an d every MIDI-cap able au d io ad ap ter h as on e. As th e system read s th e MIDI file, th e syn th esizer gen erates th e ap p rop riate sou n d for each ch an n el, u sin g th e in stru ction s in th e file to create th e p rop er p itch es an d n ote len gth s, an d u sin g a p red efin ed p atch to sim u late th e sou n d of a sp ecific m u sical in stru m en t. A patch is a set of in stru ction s th at th e syn th esizer u ses to create sou n d sim ilar to a p articu lar in stru m en t. You can con trol th e sp eed at wh ich th e m u sic p lays an d its volu m e in real tim e with th e MIDI p layer software. Th e syn th esizer on an au d io ad ap ter is sim ilar electron ically to th ose fou n d in actu al electron ic keyboard in stru m en ts, bu t it is u su ally n ot as cap able. Th e MPC sp ecification s call for au d io ad ap ters to con tain FM syn th esizer ch ip s th at are cap able of p layin g at least six m elod ic n otes an d two p ercu ssive n otes sim u ltan eou sly. FM Sy n t h e si s. Most sou n d board s gen erate sou n d s by u sin g FM synthesis, a tech n ology first p ion eered in 1976. By u sin g on e sin e wave op erator to m od ify an oth er, FM syn th esis creates an artificial sou n d th at m im ics an in stru m en t. Th e MIDI stan d ard su p p orted by th e ad ap ter sp ecifies an array of p rep rogram m ed sou n d s con tain in g m ost of th e in stru m en ts u sed by p op ban d s an d orch estras. Over th e years, th e tech n ology h as p rogressed (som e FM syn th esizers n ow u se fou r op erators) to a p oin t wh ere FM syn th esis can sou n d m od erately good , bu t is still n oticeably

Audio Adapter Applications

artificial. Th e tru m p et sou n d , for exam p le, is vagu ely sim ilar to th at of a tru m p et, bu t wou ld n ever be con fu sed with th e real th in g. W a v e t a b l e Sy n t h e si s. As you m ove u p to th e h igh er en d of th e au d io ad ap ter m arket, fewer d evices u se FM syn th esis becau se, even at its best, th e sou n d it p rod u ces is n ot a realistic sim u lation of a m u sical in stru m en t. More realistic, in exp en sive sou n d was p ion eered by En son iq Corp ., th e m akers of p rofession al keyboard s, in 1984. Usin g a tech n ology th at was th eorized at abou t th e sam e tim e as FM syn th esis, En son iq d evelop ed a m eth od of sam p lin g an y in stru m en t—in clu d in g p ian os, violin s, gu itars, flu tes, tru m p ets, an d d ru m s—an d storin g th e d igitized sou n d in a wavetable. Stored eith er in ROM ch ip s or on d isk, th e wavetable su p p lies an actu al d igitized sou n d of an in stru m en t th at th e au d io ad ap ter can m an ip u late as n eed ed . Soon after En son iq ’s d iscovery, oth er keyboard m akers rep laced th eir FM syn th esizers with wavetable syn th esis. A wavetable syn th esizer can take a sam p le of an in stru m en t p layin g a sin gle n ote an d m od ify its freq u en cy to p lay an y n ote on th e scale. Som e ad ap ters p rod u ce better sou n d by u sin g several sam p les of th e sam e in stru m en t. Th e h igh est n ote on a p ian o d iffers from th e lowest n ote in m ore th an ju st p itch , an d th e closer th e p itch of th e sam p le is to th e n ote bein g syn th esized , th e m ore realistic th e sou n d is. Th u s, th e size of th e wavetable h as a p owerfu l effect on th e q u ality an d variety of sou n d s th at th e syn th esizer can p rod u ce. Th e best q u ality wavetable ad ap ters on th e m arket u su ally h ave several m egabytes of m em ory on th e card for storin g sam p les. Som e su p p ort op tion al d au gh tercard s for th e in stallation of ad d ition al m em ory an d en able you to cu stom ize th e sam p les in th e wavetable to you r own sp ecification s. M IDI Connect ivit y. Th e ad van tages of MIDI go beyon d th e in tern al fu n ction s of you r com p u ter. You can also u se you r au d io ad ap ter’s MIDI in terface to con n ect an electron ic keyboard , sou n d gen erator, d ru m m ach in e, or oth er MIDI d evice to you r com p u ter. You can th en p lay MIDI files by u sin g th e syn th esizer in th e keyboard in stead of th e on e on you r ad ap ter—or create you r own MIDI files by p layin g n otes on th e keyboard . W ith th e righ t software, you can com p ose an en tire sym p h on y by p layin g th e n otes of each in stru m en t sep arately in to its own ch an n el, an d th en p layin g back all th e ch an n els togeth er. Man y p rofession al m u sician s an d com p osers u se MIDI to create m u sic d irectly on com p u ters, byp assin g trad ition al in stru m en ts altogeth er. Som e m an u factu rers even offer h igh -en d MIDI card s th at can op erate in fu ll-d u p lex m od e, m ean in g th at you can p lay back p rerecord ed au d io tracks as you record a n ew track in to th e sam e MIDI file. Th is is tech n ology th at on ly a few years ago req u ired th e services of a p rofession al record in g stu d io with eq u ip m en t costin g h u n d red s of th ou san d s of d ollars. To con n ect a MIDI d evice to you r PC, you n eed an au d io ad ap ter th at h as th e MIDI p orts d efin ed by th e MIDI sp ecification . MIDI u ses two rou n d 5-p in DIN p orts (see Figu re 9.1) for sep arate in p u t (MIDI-IN) an d ou tp u t (MIDI-OUT). Man y d evices also h ave a MIDITHRU p ort th at p asses th e in p u t from a d evice d irectly to ou tp u t, bu t au d io ad ap ters gen erally d o n ot h ave th is. In terestin gly, MIDI sen d s d ata th rou gh on ly p in s 1 an d 3 of th e con n ector. Pin 2 is sh ield ed an d p in s 4 an d 5 are u n u sed .

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2 5 3

4 1

FIG. 9.1 Th e MIDI sp ecification calls for th e u se of two or th ree 5-p in DIN con n ectors. Th e p rim ary fu n ction of th e au d io ad ap ter’s MIDI in terface is to con vert th e p arallel d ata bytes u sed on a com p u ter’s system bu s in to th e serial MIDI d ata form at. MIDI u ses asyn ch ron ou s serial p orts th at ru n at 31.25kbau d . MIDI com m u n ication s u se 8 d ata bits, with on e start an d on e stop bit, for a sp eed of 320 m icrosecon d s p er serial byte.

Not e You can obtain the most recent specifications for the M IDI standard, for a modest fee, from the International M IDI Association, 23634 Emelita Street, Woodland Hills, California 91367 USA.

MIDI ru n s over sp ecial u n sh ield ed twisted -p air cables th at can h ave a m axim u m len gth of u p to 50 feet (alth ou gh m ost of th e cables sold are 10 or 20 feet lon g). You can also d aisy ch ain m u ltip le MIDI d evices togeth er to com bin e th eir cap abilities. Th e total len gth of th e MIDI ch ain is n ot lim ited , as lon g as each in d ivid u al cable is less th an 50 feet. Man y au d io ad ap ters d o n ot h ave MIDI p orts d irectly on th e ad ap ter card . In stead , th ey u se a sep arate con n ector th at p lu gs in to th e ad ap ter’s gam e p ort an d p rovid es th e MIDI p orts. Un fortu n ately, th is con n ector is rarely in clu d ed in th e box with th e ad ap ter. You h ave to p u rch ase it sep arately from th e m an u factu rer. M IDI Soft w are. W in d ows 9x in clu d es basic software th at en ables you to p lay MIDI files, in th e form of its Med ia Player ap p lication , an d also in clu d es a selection of MIDI m u sic files. For fu ll MIDI cap abilities, h owever, you ’ll n eed seq u en cin g software to m an ip u late th e tem p o of MIDI files an d th e sou n d s u sed to p lay th em , or to cu t an d p aste togeth er variou s p rerecord ed m u sic seq u en ces. Man y au d io ad ap ters com e with a selection of software p rod u cts th at p rovid e som e MIDI cap abilities, an d th ere are sh areware an d freeware tools available on th e In tern et, bu t th e tru ly p owerfu l software th at en ables you to create, ed it, an d m an ip u late MIDI files m u st be p u rch ased sep arately. Present at ions Bu sin esses are rap id ly d iscoverin g th at in tegratin g grap h ics, an im ation , an d sou n d in to th eir p resen tation s is m ore im p ressive th an a sim p le slid e sh ow, an d m ore likely to keep th eir au d ien ces awake. An au d io ad ap ter ad d s im p act to an y p resen tation or classroom . A variety of bu sin ess-p resen tation software an d h igh -en d train in g an d au th orin g p ackages th at can take ad van tage of a PC’s au d io cap abilities alread y exist, an d you d on ’t h ave to be a p rogram m er to get you r own sh ow on th e road . Pop u lar software p ackages

Audio Adapter Applications

su ch as Microsoft PowerPoin t n ow in clu d e sou n d an d an im ation featu res for th eir p resen tation files. Presen tation software p ackages su p p ort W AV, AVI, an d MIDI files. W ith th ese p rod u cts, you can syn ch ron ize sou n d s with objects. W h en a p resen tation d isp lays a p ictu re of you r n ew p rod u ct, for exam p le, you can ad d a roarin g rou n d of ap p lau se. You can even p u ll in sou n d from an au d io CD in you r CD-ROM d rive. Man y p resen tation software p ackages also in clu d e clip -m ed ia libraries with au d io files th at you can u se licen se-free. You can even take you r sh ow on th e road . Man y lap top an d n otebook com p u ters in clu d e sou n d cap ability an d even h ave bu ilt-in CD-ROM d rives an d sp eakers. Th ere are also extern al au d io ad ap ters an d even CD-ROM d rives available to p rovid e m u ltim ed ia on th e go. An au d io ad ap ter can m ake m an y com p u tin g tasks (su ch as learn in g h ow to u se software) easier. PC software m an u factu rers h ave taken an early lead in th is area. Man y p u blish ers are takin g ad van tage of th e sp ace on th e CD-ROMs th ey n ow u se to d istribu te th eir p rod u cts by in clu d in g an im ated tu torials an d on lin e h elp , rep lete with m u sic. Sou n d h as also fou n d its p lace on th e W orld W id e W eb. Becau se of th eir relatively sm all size, MIDI files are an excellen t ch oice for p rovid in g backgrou n d m u sic wh en u sers arrive at you r W eb site. A catch y tu n e can h elp p eop le rem em ber you r site ou t of th e m an y oth ers th ey see each d ay. Recording Virtu ally all au d io ad ap ters h ave an au d io in p u t jack. W ith a m icrop h on e, you can record you r voice. Usin g th e Sou n d Record er ap p lication in clu d ed with all version s of Microsoft W in d ows, you can p lay, ed it, or record a sou n d file in th e W AV form at. From th e W in d ows Sou n d s Con trol Pan el, you can assign sp ecific W AV files to certain W in d ows even ts (see Figu re 9.2). I always get a lau gh wh en I exit W in d ows an d h ear th e sou n d of a flu sh in g toilet!

FIG. 9.2 Th e W in d ows 9x Sou n d s Con trol Pan el ad d s sou n d to d ifferen t W in d ows even ts.

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Th is cap ability is n ot ju st an en tertain in g n ovelty, h owever. You can also u se sp ecific sou n d s to n otify you of im p ortan t even ts, su ch as wh en you r system exp erien ces an error or wh en you receive n ew e-m ail. Th e W in d ows op eratin g system sh ip s with a collection of basic W AV files th at you can assign as n eed ed . W in d ows 9x also in clu d es collection s of W AV files called sou n d sch em es th at p rovid e a u n ified en viron m en t for you r system , based on a given su bject. Th e Mu sica sou n d sch em e, for exam p le, au tom atically assign s sou n d files of variou s m u sical in stru m en ts to m an y of th e stan d ard system even ts. Man y ap p lication s ad d th eir own even ts to th e op eratin g system , en ablin g you to con figu re sou n d s for activities sp ecific to th at p rod u ct. By record in g th e sou n d of you r own voice, or an yth in g else, you can create you r own W AV files an d assign th em to certain even ts, in stead of u sin g th e d efau lt W in d ows W AVs. On m ost m u ltim ed ia system s, you can record d irectly from an au d io CD in you r CD-ROM d rive to th e W AV form at. You can also attach you r stereo system or VCR to th e au d io in p u t jack an d record an y sou n d to a W AV file. W ith th is sim p le con n ection , u sers h ave am assed libraries con sistin g of th ou san d s of W AV files celebratin g p op u lar son gs, m ovies, an d TV sh ows. Voice Annot at ion By u sin g W AV files, you can record voice m essages an d em bed th em in to you r W in d ows d ocu m en ts. For exam p le, a bu sin ess execu tive cou ld p ick u p a m icrop h on e an d , by em bed d in g a m essage in a con tract or sp read sh eet, give h is or h er secretary exp licit in stru ction s. Th is m essage is called a voice annotation. I like to th in k of it as a verbal Post-It Note. W ith voice an n otation , you can em bed voice m essages, su ggestion s, or q u estion s in a d ocu m en t an d sen d it to a colleagu e. To leave su ch m essages, you r W in d ows ap p lication m u st su p p ort W in d ows’ Object Lin kin g an d Em bed d in g (OLE). OLE is a tech n ology th at en ables you to take objects created by on e ap p lication an d em bed th em in to a d ocu m en t created in an oth er ap p lication . Activatin g th e em bed d ed object in th e target ap p lication by d ou ble-clickin g it au tom atically lau n ch es th e object’s sou rce ap p lication . For exam p le, if you em bed a p ortion of a Microsoft Excel sp read sh eet in to a W ord d ocu m en t, you will see th e grid of th e sp read sh eet on th e p age in W ord . However, wh en you d ou ble-click th e sp read sh eet, Excel lau n ch es an d tem p orarily rep laces th e W ord m en u an d bu tton bars with th ose of Excel. Clickin g an oth er p art of th e W ord d ocu m en t retu rn s you to th e n orm al W ord en viron m en t. Em bed d in g a sou n d in a d ocu m en t works th e sam e way. Im agin e th at you ’re ed itin g an Excel sp read sh eet an d you wan t to in sert a voice n ote n ext to a total th at looks q u estion able. Place th e cu rsor in th e cell n ext to th e total, th en select Ed it, In sert, Object, Sou n d to call u p W in d ows’ Sou n d Record er. Click th e Record bu tton an d begin sp eakin g. After you ’ve fin ish ed record in g, th e sou n d ap p ears as an icon in th e selected cell. Becau se th e sou n d file is actu ally an em bed d ed p art of th e sp read sh eet file, you can cop y it to a d isk or e-m ail it to an oth er u ser. Th at u ser can th en d ou ble-click th e icon an d h ear you r voice.

Audio Adapter Applications

Tip Voice annotation is typically an area where sound quality is not a major issue. Be sure to configure your system to use telephone-quality (that is, the lowest quality) audio for this purpose, or you could end up with files that are enormously inflated in size by the addition of embedded audio.

Voice Recognit ion Som e au d io ad ap ters are eq u ip p ed with software th at is cap able of voice recogn ition . You can also get voice recogn ition for you r cu rren t ad ap ter in th e form of ad d -on software. Voice-recogn ition , as th e n am e im p lies, is wh en you r com p u ter is “tau gh t” to recogn ize sp oken word form s an d react to th em . Voice recogn ition p rod u cts gen erally take two form s: th ose th at are d esign ed to p rovid e a sim p le voice in terface to basic com p u ter fu n ction s, an d th ose th at can accep t vocal d ictation an d in sert th e sp oken text in to an ap p lication su ch as a word p rocessor. Voice Com m and Soft w are. Th e voice in terface ap p lication is clearly th e sim p ler of th e two, as th e software on ly h as to recogn ize a lim ited vocabu lary of word s. W ith th is typ e of software, you can sit in fron t of you r com p u ter an d say th e word s “file op en ” to access th e m en u in you r active W in d ows ap p lication . For th e average u ser, th is typ e of ap p lication is of d u biou s valu e. For a tim e, Com p aq was sh ip p in g com p u ters to corp orate clien ts with a m icrop h on e an d an ap p lication of th is typ e, at little or n o ad d ition al cost. Th e p h en om en on of d ozen s of u sers in an office, talkin g to th eir com p u ters, was in terestin g, to say th e least. Th e exp erim en t resu lted in virtu ally n o in creased p rod u ctivity, a lot of wasted tim e as u sers exp erim en ted with th e software, an d a n oisier office. However, for u sers with p h ysical h an d icap s th at lim it th eir ability to u se a keyboard , th is typ e of software can rep resen t a wh ole n ew aven u e of com m u n ication . For th is reason alon e, con tin u ed d evelop m en t of voice recogn ition tech n ology is essen tial.

Not e Voice recognition applications, by necessity, have to be somewhat limited in their scope. For example, it quickly becomes a standard office joke for someone to stick their head into another person’s cubicle and call out “ Format C!,” as though this command would erase the user’s hard drive. Obviously, the software must not be able to damage a user’s system because of a misinterpreted voice command.

Voice Dict at ion Soft w are. Th e oth er typ e of voice recogn ition software is far m ore com p lex. Con vertin g stan d ard sp eech in to text is an extraord in arily d ifficu lt task, given th e wid e variation in h u m an sp eech p attern s. For th is reason , n early all software of th is typ e (an d som e of th e basic voice com m an d ap p lication s, as well) m u st be “train ed ” to u n d erstan d a p articu lar u ser’s voice. You d o th is train in g by read in g p rep ared text

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sam p les su p p lied with th e software to th e com p u ter. Becau se th e software kn ows wh at you ’re su p p osed to be sayin g beforeh an d , it can associate certain word s with th e m an n er in wh ich you sp eak th em . Users’ resu lts with th is sort of ap p lication vary wid ely, p robably d u e in n o sm all p art to th eir in d ivid u al sp eech p attern s. I’ve h eard p eop le rave abou t bein g able to d ictate p ages of text with ou t tou ch in g th e keyboard , wh ile oth ers claim th at correctin g th e m an y typ ograp h ical errors is m ore trou ble th an typ in g th e text m an u ally. Voice recogn ition tech n ology is still in its in fan cy, an d is sen sitive to ch an ges in a p erson ’s voice. Illn ess an d stress can often ch an ge a p erson ’s voice en ou gh to th row off m ost of th e “con su m er” voice recogn ition p rod u cts. You will also n eed a fast com p u ter, at least a Pen tiu m , to ach ieve resp on se tim es th at are q u ick en ou gh to keep u p with you r sp eech . However, ad van ces in th is tech n ology m ay d evelop to a p oin t th at we’ll be able to u se con tin u ou s sp eech to con trol com p u ters, rath er th an typ in g. Conferencing On e of th e n ewest ap p lication s in th e world of m u ltim ed ia is vid eo an d au d io con feren cin g over th e In tern et. Th ese ap p lication s ran ge from p oin t-to-p oin t p rod u cts, su ch as VocalTec’s In tern et Ph on e, to m u ltiu ser-con feren cin g p ackages, su ch as Microsoft’s NetMeetin g. Oth er ap p lication s, su ch as RealNetworks’ Real Player, can p lay back au d io (with or with ou t vid eo) as it is received over th e In tern et, a p rocess called stream ing. For all th ese ap p lication s, th e au d io ad ap ter is an in tegral p art of th e tech n ology. Dep en d in g on th e sp eed of you r In tern et con n ection , th e d ata com p ression tech n ology th at th e software u ses, an d wh eth er or n ot you elect to stream vid eo alon g with au d io, th e q u ality of th e sou n d d elivered by con feren cin g software can ran ge from p oor to rath er good . As with voice recogn ition , th is is a tech n ology th at is still very you n g. Over a 33.6Kbp s m od em con n ection (wh ich freq u en tly d oes n ot reach a fu ll 33.6), on e-way au d io an d vid eo stream in g gen erally works tolerably well, bu t fu ll-d u p lex com m u n ication s, even wh en au d io-on ly, ten d to d rop word s. However, as faster In tern et con n ection s an d better d ata com p ression tech n iq u es becom e available, au d iocon feren cin g an d vid eocon feren cin g are likely to becom e as reliable as th e telep h on e n etwork. Proofreading You can also u se an au d io ad ap ter as an in exp en sive p roofread in g tool. Man y ad ap ters in clu d e a text-to-sp eech u tility th at you can u se to read a list of n u m bers or text back to you . Th is typ e of software can read back h igh ligh ted word s or even an en tire file. Havin g text read back to you en ables you to m ore easily sp ot forgotten word s or awkward p h rases. Accou n tan ts can d ou ble-ch eck n u m bers, an d bu sy execu tives can listen to th eir e-m ail wh ile th ey are d oin g p ap erwork. Audio CDs On e con ven ien t an d en tertain in g u se of a CD-ROM d rive is to p lay au d io CDs wh ile you are workin g on som eth in g else. Virtu ally all CD-ROM d rives su p p ort au d io CDs, an d th e

Audio Adapter Applications

m u sic can be p ip ed n ot on ly th rou gh a p air of sp eakers (an d even a su bwoofer) con n ected to th e au d io ad ap ter, bu t also th rou gh h ead p h on es p lu gged in to th e jack p rovid ed on m ost CD-ROM d rives. Most sou n d card s in clu d e a CD-p layer u tility, as d oes W in d ows 9x, an d free version s are available for d own load on th e In tern et. Th ese p rogram s u su ally p resen t a visu al d isp lay sim ilar to th e Con trol Pan el of an au d io CD p layer. You op erate th e con trols with a m ou se or th e keyboard , an d can listen to au d io CDs as you work on oth er th in gs. Sound M ixer On a m u ltim ed ia PC, it is often p ossible for two or m ore sou n d sou rces to req u ire th e services of th e au d io ad ap ter at th e sam e tim e. An y tim e you h ave m u ltip le sou n d sou rces th at you wan t to p lay th rou gh a sin gle set of sp eakers, a m ixer is n ecessary. Most au d io ad ap ters in clu d e a m ixer th at en ables all th e d ifferen t au d io sou rces, MIDI, W AV, lin e in , an d th e CD to u se th e sin gle lin e ou t jack. Norm ally, th e ad ap ter sh ip s with software th at d isp lays visu al slid ers like you wou ld see on an actu al au d io m ixer in a record in g stu d io. W ith th ese con trols, you can set th e relative volu m e of each of th e sou n d sou rces. Is an Audio Adapt er Necessary? In th e p reced in g section s, you read abou t th e variou s ways th at h igh -q u ality au d io can im p rove th e com p u tin g exp erien ce. Certain ly, for recreation al com p u ter u sers, au d io greatly en h an ces th e en tertain m en t valu e of gam es an d oth er m u ltim ed ia software. Th e q u estion still rem ain s, h owever, of wh eth er au d io is su ited to th e bu sin ess world . Th ere are d efin itely ap p lication s, su ch as voice an n otation an d au d iocon feren cin g, th at can be u sefu l to bu sin ess com p u ter u sers. In train in g an d oth er ed u cation al en viron m en ts, au d io can be a n ecessity in som e cases. However, th ree oth er factors th at can m ake th e assim ilation of PC au d io in to th e bu sin ess office p roblem atic are th e followin g: ■ Exp en se ■ Prod u ctivity ■ Noise Th e p rice of ad d in g basic au d io cap abilities to a PC, like th at of virtu ally all com p u ter h ard ware, h as p lu m m eted d u rin g th e p ast few years. Bu sin ess ap p lication s d o n ot req u ire h igh -en d au d io featu res su ch as wavetable syn th esis, so a sim p le ad ap ter th at con form s to th e MPC sp ecification is su fficien t. You can u su ally bu y a serviceable au d io ad ap ter an d sp eakers for abou t $100, or less wh en you are bu yin g in volu m e. However, th is is n ot an in sign ifican t exp en d itu re wh en you are talkin g abou t h u n d red s or th ou san d s of PCs. Ad d ed to th at is th e cost of th e m an p ower n eed ed to in stall an d con figu re all th is n ew h ard ware. Th e easiest solu tion to th is p roblem is to p u rch ase PCs with in tegrated au d io ad ap ters on th e m oth erboard . Becau se th ese system s u su ally arrive p recon figu red , or are

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au tom atically con figu red by th e op eratin g system , in tegrated au d io elim in ates th e tim e an d exp en se of in stallation , an d p rovid es basic au d io cap abilities at th e lowest p ossible cost. Em p loyee p rod u ctivity is an oth er im p ortan t con cern . Man y n etwork ad m in istrators an d com p an y execu tives are on ly n ow com in g to grip s with th e effect th at In tern et access h as h ad on th e workforce. Au d io d efin itely h as its u ses in th e bu sin ess world , as d oes th e W orld W id e W eb, bu t th e q u estion rem ain s as to wh eth er it will be seen by m an y su p ervisors as ju st an oth er tim e-wastin g toy. Th e an swer to th is p roblem is n ot so sim p le. Ad m in istrators can take step s to lim it u sers’ access to th e op eratin g system ’s sou n d con figu ration con trols, u sin g W in d ows 9x system p olicies, bu t th ey can n ot easily p reven t u sers from d own load in g or record in g sou n d files an d p layin g th em back, with ou t lim itin g th e au d io h ard ware’s u sefu ln ess. As with th e W eb, h owever, it is likely th at on ce th e n ovelty of th e n ew cap abilities wears off, u sers will waste less tim e p layin g with au d io an d m ore tim e u sin g it p rod u ctively. Th e fin al p roblem is th e obviou s on e of th e n oise p rod u ced by th e in d ivid u al sp eakers attach ed to a large fleet of PCs. Th e d egree of d ifficu lty is, of cou rse, d ep en d en t on th e arch itectu ral layou t of th e workp lace. For u sers workin g in sm all or p rivate offices, th e n oise level sh ou ld be m in im al. For workers in cu bicles, th e situ ation sh ou ld be tolerable, as lon g as th e u sers exercise som e restrain t in th e volu m e. In an op en office with m an y com p u ters, h owever, th e n oise cou ld be a severe p roblem . Network ad m in istrators sh ou ld con sid er th ese factors wh en d ecid in g wh ich u sers sh ou ld be fu rn ish ed with au d io h ard ware.

Audio Adapt er Concept s and Term s To fu lly u n d erstan d au d io ad ap ters an d th eir fu n ction s, you n eed to u n d erstan d variou s con cep ts an d term s. Term s like 16-bit, CD quality, an d MIDI port are ju st a few. Con cep ts su ch as sam pling an d digital-to-audio conversion (DAC) are often sp rin kled th rou gh ou t stories abou t n ew sou n d p rod u cts. You ’ve alread y learn ed abou t som e of th ese term s an d con cep ts; th e followin g section s d escribe m an y oth ers. The Nat ure of Sound To u n d erstan d an au d io ad ap ter, you h ave to u n d erstan d th e n atu re of sou n d . Every sou n d is p rod u ced by vibration s th at com p ress air or oth er su bstan ces. Th ese sou n d waves travel in all d irection s, exp an d in g in balloon -like fash ion from th e sou rce of th e sou n d . W h en th ese waves reach you r ear, th ey cau se vibration s th at you p erceive as sou n d . Two of th e basic p rop erties of an y sou n d are its p itch an d its in ten sity. Pitch is th e rate at wh ich vibration s are p rod u ced . It is m easu red in th e n u m ber of hertz (Hz), or cycles p er secon d . On e cycle is a com p lete vibration back an d forth . Th e n u m ber of Hz is th e freq u en cy of th e ton e; th e h igh er th e freq u en cy, th e h igh er th e p itch .

Audio Adapter Concepts and Terms

Hu m an s can n ot h ear all p ossible freq u en cies. Very few p eop le can h ear sou n d s with freq u en cies less th an 16Hz or m ore th an abou t 20KHz (kiloh ertz; 1KHz eq u als 1,000Hz). In fact, th e lowest n ote on a p ian o h as a freq u en cy of 27Hz, an d th e h igh est n ote a little m ore th an 4KHz. Freq u en cy-m od u lation (FM) rad io station s can broad cast n otes with freq u en cies as h igh as 15KHz. Th e in ten sity of a sou n d is called its am plitude. Th is in ten sity d eterm in es th e sou n d ’s volu m e, an d d ep en d s u p on th e stren gth of th e vibration s p rod u cin g th e sou n d . A p ian o strin g, for exam p le, vibrates gen tly wh en th e key is stru ck softly. Th e strin g swin gs back an d forth in a n arrow arc, an d th e ton e it sen d s ou t is soft. If th e key is stru ck m ore forcefu lly, h owever, th e strin g swin gs back an d forth in a wid er arc, p rod u cin g a greater am p litu d e an d a greater volu m e. Th e lou d n ess of sou n d s is m easu red in decibels (db). Th e ru stle of leaves is rated at 20d b, average street n oise at 70d b, an d n earby th u n d er at 120d b. Gam e St andards Most au d io ad ap ters su p p ort th e Sou n d Blaster, by Creative Labs, wh ich is th e cu rren t en tertain m en t au d io stan d ard . AdLiB was a com p an y wh ose au d io ad ap ters at on e tim e rivaled th ose of Creative Labs in th e PC gam e in d u stry. Th ey were in volved in th e d evelop m en t of th e MSC Level 1 an d 2 stan d ard s an d , for som e tim e, Ad LiB an d Creative Labs were ru n n in g n eck an d n eck as th e de facto stan d ard , u n til Ad LiB d eclin ed an d wen t ou t of bu sin ess for a tim e. Now, th e com p an y is back in bu sin ess as Ad LiB Mu ltim ed ia, bu t th ey n o lon ger h old a p osition com p arable to th at of Creative Labs. To h ear sou n d s in m ost DOS gam es, you m u st con figu re th e gam e by selectin g on e of th e au d io ad ap ter d rivers in clu d ed with th e p rogram . Stickin g with a p op u lar sou n d card p rod u ct like on e of th e Sou n d Blaster m od els will en su re th at you always h ave software su p p ort, becau se m ost software su p p orts th em . Even if you d on ’t h ave an actu al Sou n d Blaster, h owever, n early all oth er au d io ad ap ters on th e m arket tod ay em u late th em . If you h ave som e old or off-bran d ad ap ter th at d oes n ot em u late th e Sou n d Blaster, th en you m ay fin d m an y software p rod u cts th at d o n ot sp ecifically su p p ort you r card . Man y gam es are n ow bein g written for th e W in d ows 9x op eratin g system , wh ich elim in ates th e p roblem of au d io ad ap ter com p atibility. In W in d ows 9x, you in stall th e d river in th e op eratin g system , an d an y ap p lication can take ad van tage of it. As lon g as you h ave a W in d ows 9x d river for you r ad ap ter, you can ru n an y gam e d esign ed for th e OS. Frequency Response Th e q u ality of an au d io ad ap ter is often m easu red by two criteria: freq u en cy resp on se (or ran ge) an d total h arm on ic d istortion . Th e frequency response of an au d io ad ap ter is th e ran ge in wh ich an au d io system can record an d / or p lay at a con stan t an d au d ible am p litu d e level. Man y card s su p p ort 30Hz to 20KHz. Th e wid er th e sp read , th e better th e ad ap ter. Th e total harm onic distortion m easu res an au d io ad ap ter’s linearity, th e straigh tn ess of a freq u en cy resp on se cu rve. In laym an ’s term s, th e h arm on ic d istortion is a m easu re of

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accu rate sou n d rep rod u ction . An y n on lin ear elem en ts cau se d istortion in th e form of h arm on ics. Th e sm aller th e p ercen tage of d istortion , th e better. Sam pling W ith an au d io ad ap ter, a PC can record waveform au d io. W aveform audio (also kn own as sam pled or digitized sound) u ses th e PC as a record in g d evice (su ch as a tap e record er). Sm all com p u ter ch ip s bu ilt in to th e ad ap ter, called analog-to-digital converters (ADCs), con vert an alog sou n d waves in to d igital bits th at th e com p u ter can u n d erstan d . Likewise, digital-to-analog converters (DACs) con vert th e record ed sou n d s to an au d ible an alog form at. Sam pling is th e p rocess of tu rn in g th e origin al an alog sou n d waves (see Figu re 9.3) in to d igital (bin ary) sign als th at th e com p u ter can save an d later rep lay. Th e system sam p les th e sou n d by takin g sn ap sh ots of its freq u en cy an d am p litu d e at regu lar in tervals. For exam p le, at tim e X th e sou n d m ay be m easu red with an am p litu d e of Y. Th e h igh er (or m ore freq u en t) th e sam p le rate, th e m ore accu rate th e d igital sou n d is to its real-life sou rce, an d th e larger th e am ou n t of d isk sp ace n eed ed to store it.

+ Intensity

Time

Time

- Intensity Analog Sound Wave Sampling

+ 128

+ Intensity

0

- 127

- Intensity Measurable Digital Value

FIG. 9.3 Sam p lin g tu rn s a ch an gin g sou n d wave in to m easu rable d igital valu es. 8-Bit Versus 16-Bit Th e origin al MPC sp ecification s req u ired au d io ad ap ters to p rovid e 8-bit sou n d . Th is d oesn ’t m ean th e au d io ad ap ter m u st fit in to an 8-bit in stead of a 16-bit exp an sion slot. Rath er, 8-bit audio m ean s th at th e ad ap ter u ses eigh t bits to d igitize each sou n d sam p le.

Audio Adapter Features

Th is tran slates in to 256 (2 8 ) p ossible d igital valu es to wh ich th e sam p le can be p egged (less q u ality th an th e 65,536 valu es p ossible with a 16-bit sou n d card ). Gen erally, 8-bit au d io is ad eq u ate for record ed sp eech , wh ile 16-bit sou n d is best for th e d em an d s of m u sic. Figu re 9.4 sh ows th e d ifferen ce between 8- an d 16-bit sou n d .

+ 128

+ Intensity

+ Intensity

0

0

Time

Time

- 127

- Intensity 8-Bit

- Intensity 16-Bit

FIG. 9.4 16-bit resolu tion allows m ore accu rate sou n d rep rod u ction th an 8-bit resolu tion . Man y of th e old er au d io ad ap ters d id on ly 8-bit sou n d rep rod u ction . Tod ay, I wou ld n ot recom m en d an yth in g less th an a 16-bit card , wh ich offers very h igh resolu tion . Besid es resolu tion , th e sam p lin g rate or freq u en cy d eterm in es h ow often th e au d io ad ap ter m easu res th e level of th e sou n d bein g record ed or p layed back. Basically, you h ave to sam p le at abou t two tim es th e h igh est freq u en cy you wan t to p rod u ce, p lu s an extra 10 p ercen t to keep ou t u n wan ted sign als. Hu m an s can h ear u p to 20,000 cycles p er secon d , or 20KHz. If you d ou ble th is n u m ber an d ad d 10%, you get a 44.1KHz sam p lin g rate, th e sam e sam p lin g rate u sed by h igh -fid elity au d io CDs. Sou n d record ed at th e telep h on e q u ality rate of 11KHz (cap tu rin g 11,000 sam p les p er secon d ) is fu zzier th an sou n d sam p led at th e rad io q u ality rate of 22KHz. A sou n d sam p led in 16-bit stereo (two ch an n el) at 44KHz (CD-au d io q u ality) req u ires as m u ch as 10.5M p er m in u te of d isk sp ace. Th e sam e sou n d sam p le in 8-bit m on o (sin gle ch an n el) at 11KHz takes 1/ 16th th e sp ace.

Audio Adapt er Feat ures To m ake an in telligen t p u rch asin g d ecision , you sh ou ld be aware of som e au d io ad ap ter basic com p on en ts an d th e featu res th ey p rovid e. Th e followin g section s d iscu ss th e featu res you sh ou ld con sid er wh ile evalu atin g au d io ad ap ters for you r PC. Connect ors Most au d io ad ap ters h ave th e sam e con n ectors. Th ese 1/ 8-in ch m in ijack con n ectors p rovid e th e m ean s of p assin g sou n d sign als from th e ad ap ter to sp eakers, h ead p h on es, an d stereo system s, an d of receivin g sou n d from a m icrop h on e, CD p layer, tap e p layer, or stereo. Th e fou r typ es of con n ectors you r au d io ad ap ter sh ou ld h ave are sh own in Figu re 9.5.

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Cassette, tape, CD players, synthesizers, Line Out etc.

Microphone

Line In Microphone In To CD-ROM Drive

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Speakers Out Joystick/MIDI Adapter Plug Speakers

Joystick

FIG. 9.5 Th e basic in p u t an d ou tp u t con n ectors th at m ost au d io ad ap ters h ave in com m on . ■ Stereo line, or audio, out connector. Th e lin e ou t con n ector is u sed to sen d sou n d sign als from th e au d io ad ap ter to a d evice ou tsid e th e com p u ter. You can h ook u p th e cables from th e lin e ou t con n ector to stereo sp eakers, a h ead p h on e set, or you r stereo system . If you h ook u p th e PC to you r stereo system , you can h ave am p lified sou n d . Som e ad ap ters , su ch as th e Microsoft W in d ows Sou n d System , p rovid e two jacks for lin e ou t. On e is for th e left ch an n el of th e stereo sign al; th e oth er is for th e righ t ch an n el. ■ Stereo line, or audio, in connector. W ith th e lin e in con n ector, you can record or m ix sou n d sign als from an extern al sou rce, su ch as a stereo system or VCR, to th e com p u ter’s h ard d isk. ■ Speaker/headphone connector. Th e sp eaker/ h ead p h on e con n ector is p rovid ed on m ost au d io ad ap ters, bu t n ot n ecessarily all of th em . In stead , th e lin e ou t (d escribed earlier) d ou bles as a way to sen d stereo sign als from th e ad ap ter to you r stereo system or sp eakers. W h en th e ad ap ter p rovid es both a sp eaker/ h ead p h on e an d a lin e ou t con n ector, th e sp eaker/ h ead p h on e con n ector p rovid es an am p lified sign al th at can p ower you r h ead p h on es or sm all booksh elf sp eakers. Most ad ap ters can p rovid e u p to fou r watts of p ower to d rive you r sp eakers. Th e sign als th at th e ad ap ter sen d s th rou gh th e lin e ou t con n ector are n ot am p lified . Th e lin e ou t con n ector gen erally p rovid es better sou n d rep rod u ction becau se it relies on th e extern al am p lifier bu ilt-in to you r stereo system or sp eakers, wh ich is typ ically m ore p owerfu l th an th e sm all am p lifier on th e au d io ad ap ter. ■ Microphone, or m ono, in connector. Th e m on o in con n ector is u sed to con n ect a m icrop h on e for record in g you r voice or oth er sou n d s to d isk. Th is m icrop h on e jack record s in m on o, n ot in stereo, an d is th erefore n ot su itable for h igh -q u ality m u sic record in gs. Man y au d io ad ap ters card s u se Autom atic Gain Control (AGC) to im p rove record in gs. Th is featu re ad ju sts th e record in g levels on -th e-fly. A 600oh m to 10K

Audio Adapter Features

oh m d yn am ic or con d en ser m icrop h on e works best with th is jack. Som e in exp en sive au d io ad ap ters u se th e lin e in con n ector in stead of a sep arate m icrop h on e jack. ■ Joystick connector. Th e joystick con n ector is a 15-p in , D-sh ap ed con n ector th at can con n ect to an y stan d ard joystick or gam e con troller. Som etim es th e joystick p ort can accom m od ate two joysticks if you p u rch ase an op tion al Y-ad ap ter. Man y com p u ters alread y con tain a joystick p ort as p art of a m u lti-fu n ction I/ O circu it on th e m oth erboard or an exp an sion card . If th is is th e case, you m u st take n ote of wh ich p ort you r op eratin g system or ap p lication is con figu red to u se wh en con n ectin g th e gam e con troller. ■ MIDI connector. Au d io ad ap ters typ ically u se th e sam e joystick p ort as th eir MIDI con n ector. Two of th e p in s in th e con n ector are d esign ed to carry sign als to an d from a MIDI d evice, su ch as an electron ic keyboard . In m ost cases, you m u st p u rch ase a sep arate MIDI con n ector from th e au d io ad ap ter m an u factu rer th at p lu gs in to th e joystick p ort an d con tain s th e two rou n d , 5-p in DIN con n ectors u sed by MIDI d evices, p lu s a con n ector for a joystick. Becau se th eir sign als u se sep arate p in s, you can con n ect th e joystick an d a MIDI d evice at th e sam e tim e. You n eed on ly th is con n ector if you p lan to con n ect you r PC to extern al MIDI d evices. You can still p lay th e MIDI files fou n d on m an y W eb sites by u sin g th e au d io ad ap ter’s in tern al syn th esizer. ■ Internal pin-type connector. Most au d io ad ap ters h ave an in tern al p in -typ e con n ector th at you can u se to p lu g an in tern al CD-ROM d rive d irectly in to th e ad ap ter, u sin g a ribbon cable. Th is con n ection en ables you to ch an n el au d io sign als from th e CD-ROM d irectly to th e au d io ad ap ter, so you can p lay th e sou n d th rou gh th e com p u ter’s sp eakers. Note th at th is con n ector is d ifferen t from th e CD-ROM con troller con n ector fou n d on som e au d io ad ap ters. Th is con n ector d oes n ot carry d ata from th e CD-ROM to th e system bu s; it on ly p rovid es th e CD-ROM d rive with d irect au d io access to th e sp eakers. If you r ad ap ter lacks th is con n ector, you can still p lay CD au d io th rou gh th e com p u ter sp eakers by con n ectin g th e CD-ROM d rive’s h ead p h on e jack to th e au d io ad ap ter’s lin e in jack with an extern al cable.

Tip The line in, line out, and speaker connectors on an audio adapter all use the same 1/ 8-inch minijack socket. The three jacks are usually labeled, but when setting up a computer on or under a desk, these labels on the back of the PC can be difficult to read. One of the most common reasons why a PC fails to produce any sound is that the speakers are plugged into the wrong socket.

Volum e Cont rol Som e au d io ad ap ters in clu d e a th u m bwh eel volu m e con trol n ext to th e in p u t/ ou tp u t jacks, alth ou gh sop h isticated sou n d card s h ave n o room for it. Th is con trol is u su ally red u n d an t, as th e op eratin g system or th e software in clu d ed with th e ad ap ter typ ically p rovid es a com bin ation of keys or a visu al slid er con trol th at you can u se to ad ju st th e volu m e. In fact, th e volu m e wh eel can be trou blesom e; if you aren ’t aware of its

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existen ce an d it is tu rn ed all th e way d own , you m ay be p u zzled by th e ad ap ter’s failu re to p rod u ce su fficien t sou n d . Synt hesis At on e tim e, wh en evalu atin g au d io ad ap ters, you h ad to d ecid e wh eth er to bu y a m on op h on ic or stereop h on ic card . Tod ay, virtu ally all au d io ad ap ters are stereop h on ic. Stereophonic card s p rod u ce m an y voices con cu rren tly an d from two d ifferen t sou rces. A voice is a sin gle sou n d p rod u ced by th e ad ap ter. A strin g q u artet u ses fou r voices, on e for each in stru m en t, wh ile a p olyp h on ic in stru m en t su ch as a p ian o req u ires on e voice for each n ote of a ch ord . Th u s, to fu lly rep rod u ce th e cap abilities of a p ian ist req u ires ten voices, on e for each fin ger. Th e m ore voices an au d io ad ap ter is cap able of p rod u cin g, th e better th e sou n d fid elity. Th e best au d io ad ap ters on th e m arket tod ay can p rod u ce u p to 128 sim u ltan eou s voices. Most of th e au d io ad ap ters th at u se FM syn th esis to im itate m u sical in stru m en ts u se syn th esizer ch ip s d evelop ed by Yam ah a. Old er an d less-exp en sive ad ap ters u se th e m on op h on ic 11-voice YM3812 or OPL2 ch ip . Better m od els u se th e stereop h on ic 20-voice YMF262 or OPL3 ch ip . Im itated m u sical in stru m en ts are n ot as im p ressive as th e real th in g. W avetable au d io ad ap ters u se d igital record in gs of real in stru m en ts an d sou n d effects. Often , several m egabytes of th ese sou n d clip s are em bed d ed in ROM ch ip s on th e card . For exam p le, som e sou n d card s u se th e En son iq ch ip set (a typ e of circu it d esign ) th at d oes wavetable syn th esis of m u sical in stru m en ts. In stead of syn th esizin g th e sou n d of a trom bon e p layin g a D flat, th e En son iq ch ip set accesses a d igitized sam p le of an actu al trom bon e p layin g th at n ote. If you r p rim ary in terest in an au d io ad ap ter is for en tertain m en t or for u se in ed u cation al or bu sin ess settin gs, FM syn th esis q u ality m ay be good en ou gh . If you are a m u sic en th u siast or p lan to work exten sively with MIDI, th en a wavetable ad ap ter is p referable.

Not e To enhance the M IDI capabilities of Sound Blaster adapters that use FM synthesis, Creative Labs offers the Wave Blaster . The Wave Blaster is a daughtercard that plugs into the Sound Blaster card. When the system plays M IDI music, the adapter looks to the Wave Blaster for any of 213 CDquality digitally recorded musical instrument sounds. Without the Wave Blaster, the Sound Blaster would imitate these sounds through FM synthesis. With the Wave Blaster, the music sounds as though it’s being played by real instruments—because it is.

Dat a Com pression Most sou n d card s tod ay can easily p rod u ce CD-q u ality au d io, wh ich is sam p led at 44.1KHz. At th is rate, record ed files (even of you r own voice) can con su m e over 10M for every m in u te of record in g. To cou n ter th is d em an d for d isk sp ace, m an y au d io ad ap ters in clu d e th eir own d ata-com p ression cap ability. For exam p le, th e Sou n d Blaster ASP 16 in clu d es on -th e-fly com p ression of sou n d files in ratios of 2:1, 3:1, or 4:1.

Audio Adapter Features

Som e m an u factu rers of au d io ad ap ters u se an algorith m called Adaptive Differential Pulse Code Modulation (ADPCM) com pression to red u ce file size by m ore th an 50%. However, a sim p le fact of au d io tech n ology is th at wh en you u se su ch com p ression , you lose sou n d q u ality. Becau se it d egrad es sou n d q u ality, th ere is n o stan d ard for th e u se of ADPCM. Creative Labs u ses a p rop rietary h ard ware ap p roach , wh ile Microsoft is p rom otin g th e Bu sin ess Au d io ADPCM d esign , d evelop ed with Com p aq . Th e m ost p op u lar com p ression stan d ard is th e Motion Pictures Experts Group (MPEG) standard, wh ich works with both au d io an d vid eo com p ression an d is gain in g su p p ort in th e n on -PC world from p rod u cts su ch as th e n ew crop of DVD p layers n ow h ittin g th e m arket. MPEG by itself p rovid es a p oten tial com p ression ratio of 30:1, an d largely becau se of th is, fu ll-m otion -vid eo MPEG DVD an d CD-ROM titles are n ow available. M ult i-Purpose Digit al Signal Processors Man y au d io ad ap ters u se digital signal processors (DSPs) to ad d in telligen ce to th e ad ap ter, freein g th e system p rocessor from work-in ten sive tasks, su ch as filterin g n oise from record in gs or com p ressin g au d io on -th e-fly. Th e Sou n d Blaster AW E32’s p rogram m able DSP, for exam p le, featu res com p ression algorith m s for p rocessin g text-to-sp eech d ata an d en ables th e card ’s QSou n d su rrou n d -sou n d 3D au d io, alon g with reverb an d ch oru s effects. DSPs en able an au d io ad ap ter to be a m u lti-p u rp ose d evice. IBM u ses its DSP to ad d a fax m od em an d d igital an swerin g m ach in e to its W in d Su rfer Com m u n ication s Ad ap ter. CD-ROM Connect ors Som e au d io ad ap ters d ou ble as a CD-ROM con troller, or in terface, card s. Before th e EIDE in terface m ad e th e CD-ROM a u biq u itou s PC com p on en t, con n ectin g th e d rive to th e au d io ad ap ter was an in exp en sive m ean s of ad d in g m u ltim ed ia cap abilities to a system . Alth ou gh som e ad ap ters p rovid e a SCSI p ort th at you can th eoretically u se to con n ect an y SCSI d evice, oth ers u se a p rop rietary con n ection th at accom m od ates on ly a select few CD-ROM d rives th at su p p ort th e sam e in terface. If you ’re seekin g to ad d both an au d io ad ap ter an d a CD-ROM d rive to an existin g system , th en you m igh t wan t to con sid er u sin g an ad ap ter with a CD-ROM con n ector. Som e m an u factu rers m arket m u ltim ed ia u p grad e kits th at bu n d le an au d io ad ap ter, CD-ROM d rive, CD-ROM titles, software, an d cables in an attractively p riced p ackage. By p u rch asin g a m u ltim ed ia u p grad e kit rath er th an sep arate com p on en ts, you m ay save som e m on ey, an d you can be certain th at all th e com p on en ts will work togeth er. If you alread y own a CD-ROM d rive, m ake su re it’s com p atible with th e au d io ad ap ter you p lan to bu y. If you p lan to ad d a CD-ROM d rive or exp ect to u p grad e you r d rive, keep in m in d th at a p rop rietary in terface will lim it you r ch oices, p erh ap s to a sin gle CD-ROM bran d . Alth ou gh an in tegrated au d io/ CD-ROM con troller can be a q u ick an d easy m u ltim ed ia solu tion for old er system s, I gen erally recom m en d th at u sers con n ect th e CD-ROM

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th rou gh a stan d ard EIDE or SCSI in terface, an d avoid th e CD-ROM con n ector on th e au d io ad ap ter. Virtu ally all n ew system s sold tod ay in clu d e an EIDE in terface, an d a SCSI ad ap ter en ables you to attach oth er d evices to th e sam e in terface, su ch as h ard d isks, tap e d rives, an d scan n ers. Th e software d river su p p ort an d p erform an ce of a d ed icated d river in terface will be m u ch better th an th ose p rovid ed by au d io/ CD-ROM com bin ation card s. ◊◊ For more information on adding a CD-ROM drive to your system, see Chapter 13, “ Optical Storage.”

Sound Drivers As with m an y PC com p on en ts, a software d river p rovid es a vital lin k between an au d io ad ap ter an d th e ap p lication or op eratin g system th at u ses it. Op eratin g system s su ch as W in d ows 9x an d W in d ows NT in clu d e a large library of d rivers for m ost of th e au d io ad ap ters on th e m arket. In m ost cases, th ese d rivers are written by th e m an u factu rer of th e au d io ad ap ter an d on ly d istribu ted by Microsoft. You m ay fin d th at th e d rivers th at sh ip with th e ad ap ter are m ore recen t th an th ose in clu d ed with th e op eratin g system . As always, th e best p lace to fin d th e m ost recen t d rivers for a p iece of h ard ware is th e m an u factu rers own W eb site or oth er on lin e service. DOS ap p lication s d o n ot u su ally in clu d e as wid e a ran ge of d river su p p ort as an op eratin g system , bu t you sh ou ld fin d th at m ost gam es an d oth er p rogram s su p p ort th e Sou n d Blaster ad ap ters. If you are carefu l to bu y an ad ap ter th at is Sou n d Blaster-com p atible, you sh ou ld h ave n o trou ble fin d in g d river su p p ort for all you r ap p lication s.

Choosing an Audio Adapt er W h at are som e key featu res to con sid er in a sou n d card ? Alth ou gh som e asp ects are su bjective, th e followin g section s d escribe som e key bu yin g p oin ts. Consum er or Producer? Differen t u sers req u ire varyin g d egrees of p erform an ce an d d ifferen t featu res from an au d io ad ap ter. On e sim p le way of classifyin g au d io u sers is to d ivid e th em in to con su m ers an d p rod u cers of sou n d . Man y u sers n eed on ly basic au d io cap abilities. Th ey wan t to h ear sou n d effects an d m u sic wh en th ey p lay gam es or view W eb sites, an d m aybe listen to au d io CDs as th ey work. Th ese are con su m ers of sou n d . Th ey obtain au d io from ou tsid e sou rces su ch as CD-ROMs an d th e In tern et an d p lay th em over th eir sp eakers. For th is typ e of u ser, a m od est au d io ad ap ter is all th at is n eed ed . Th e ad ap ter sh ou ld p rovid e 16-bit au d io, bu t an FM syn th esizer sh ou ld be su fficien t for sou n d p rod u ction . Users of th is typ e th at are h ard -core gam ers m ay wan t to m ove u p to an ad ap ter with a wavetable syn th esizer, bu t th ey d o n ot req u ire a top -of-th e-lin e m od el. Prod u cers are p eop le wh o in ten d to create th eir own sou n d files. Th ese can ran ge from casu al bu sin ess u sers record in g low-fid elity voice an n otation s to p rofession al m u sician s

Audio Adapter Installation

an d MIDI-m an iacs. Th ese u sers n eed an ad ap ter th at can p erform as m u ch of th e au d io p rocessin g as p ossible itself, so as n ot to p lace an ad d ition al bu rd en on th e system p rocessor. Ad ap ters th at u se DSPs to p erform com p ression an d oth er tasks are h igh ly recom m en d ed in th is case. Mu sician s will certain ly wan t an ad ap ter with as m an y voices as p ossible an d a wavetable syn th esizer. Ad ap ters with exp an d able m em ory arrays an d th e cap ability to create an d m od ify cu stom wavetables are also p referable. Com pat ibilit y Alth ou gh th ere are n o official au d io ad ap ter stan d ard s, Creative Labs’ p op u lar Sou n d Blaster lin e h as becom e a de facto stan d ard . Th e Sou n d Blaster—th e first wid ely d istribu ted au d io ad ap ter—is su p p orted by th e greatest n u m ber of software p rogram s. An au d io ad ap ter ad vertised as Sou n d Blaster-com p atible sh ou ld be able to ru n with virtu ally an y ap p lication th at su p p orts sou n d . Most ad ap ters also su p p ort th e MPC Level 2 or Level 3 sp ecification s, en ablin g you to p lay sou n d files in W in d ows an d m ore.

Caut ion Beware of audio adapters that require special drivers to be Sound Blaster-compatible. These drivers can cause problems and will take up additional memory that otherwise would be available to your applications.

Bundled Soft w are A software bu n d le can som etim es m ake th e d ifferen ce between a good bu y on an au d io ad ap ter an d a great on e. Au d io ad ap ters u su ally in clu d e several sou n d u tilities so you can begin u sin g you r ad ap ter righ t away. Som e of th e typ es of software you m ay receive are as follows: ■ Text-to-sp eech con version p rogram s ■ Ap p lication s for p layin g, ed itin g, an d record in g au d io files ■ Au d io CD-p layer p rogram s ■ Stereo sou n d -m ixer p rogram s ■ Seq u en cer software, wh ich h elp s you create, ed it, an d p lay back MIDI m u sic files ■ Variou s sou n d clip s

Audio Adapt er Inst allat ion In stallin g an au d io ad ap ter is n o m ore in tim id atin g th an in stallin g an in tern al m od em or a vid eo ad ap ter, esp ecially if you are u sin g W in d ows 9x an d th e ad ap ter con form s to th e Plu g-an d -Play sp ecification , as m ost d o. Typ ically, you follow th ese step s: 1. Op en you r com p u ter. 2. Con figu re you r sou n d card (if it isn ’t Plu g an d Play). 3. In sert th e au d io ad ap ter in to a bu s slot an d attach th e CD-ROM d rive to th e CD Au d io In con n ector, if p resen t.

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4. Close you r com p u ter. 5. Boot th e system , cau sin g W in d ows 9x to locate an d in stall th e d river for th e ad ap ter (or in stall th e sou n d card software for n on –Plu g-an d -Play d evices). 6. Attach you r sp eakers an d oth er sou n d accessories. Inst alling t he Sound Card After you r com p u ter is op en , you can in stall th e au d io ad ap ter. Most ad ap ters tod ay u se a 16-bit ISA slot, alth ou gh som e h igh -en d ad ap ters u se th e PCI bu s. Th e m igration from ISA to PCI in th e au d io-ad ap ter in d u stry h as been slower th an th at for oth er com p on en ts, su ch as vid eo-d isp lay ad ap ters. Th e first PCI au d io card s were m u ch m ore exp en sive th an stan d ard com m ercial m od els an d in ten d ed for p rofession al ap p lication s, bu t several m an u factu rers, in clu d in g Cirru s Logic an d Vid eoLogic, are n ow m arketin g PCI ad ap ters for th e h om e PC m arket. If you h ave several em p ty bu s slots from wh ich to ch oose, in stall th e au d io ad ap ter in th e slot th at is as far away as p ossible from th e oth er card s in th e com p u ter. Th is red u ces an y p ossible electrom agn etic in terferen ce; th at is, it red u ces stray rad io sign als from on e card th at m igh t affect th e sou n d card . Th e an alog com p on en ts on au d io ad ap ters are h igh ly su scep tible to in terferen ce an d , even th ou gh th ey are sh ield ed , th ey sh ou ld be p rotected as well as p ossible. Next, you m u st rem ove th e screw th at h old s th e m etal cover over th e em p ty exp an sion slot you ’ve ch osen . Rem ove you r au d io ad ap ter from its p rotective p ackagin g. W h en you op en th e bag, carefu lly grab th e card by its m etal bracket an d ed ges. Do n ot tou ch an y of th e com p on en ts on th e card . An y static electricity you m ay tran sm it can d am age th e card . Also, d o n ot tou ch th e gold -ed ge con n ectors. You m ay wan t to in vest in a grou n d in g wrist strap , wh ich con tin u ally d rain s you of static bu ild -u p as you work on you r com p u ter. If you r ad ap ter is n ot Plu g an d Play, you m ay h ave to set ju m p ers or DIP switch es to con figu re th e ad ap ter to u se th e ap p rop riate h ard ware resou rces in you r com p u ter. For exam p le, you m ay h ave to ad ju st an IRQ or DMA settin g, or tu rn off th e ad ap ter’s joystick p ort becau se you r joystick is alread y con n ected to you r PC elsewh ere. See th e in stru ction s th at cam e with you r au d io ad ap ter. If you r system h as an in tern al CD-ROM d rive with an au d io cable, con n ect it to th e ad ap ter’s CD Au d io In con n ector. Th is con n ector is keyed so th at you can ’t in sert it im p rop erly. Note th at th ere is n o tru e stan d ard for th is au d io cable, so be su re th at you get th e righ t on e th at m atch es you r d rive an d ad ap ter. Next, in sert th e ad ap ter’s ed ge con n ector in to th e bu s slot, bu t first tou ch a m etal object, su ch as th e in sid e of th e com p u ter’s cover, to d rain you rself of static electricity. W h en th e card is firm ly in p lace, attach th e screw to h old th e exp an sion card an d th en reassem ble you r com p u ter. After th e ad ap ter card is in stalled , you can con n ect sm all sp eakers to th e sp eaker jack. Typ ically, sou n d card s p rovid e fou r watts of p ower p er ch an n el to d rive booksh elf

Audio Adapter Installation

sp eakers. If you are u sin g sp eakers rated for less th an fou r watts, d o n ot tu rn u p th e volu m e on you r sou n d card to th e m axim u m ; you r sp eakers m ay bu rn ou t from th e overload . You ’ll get better resu lts if you p lu g you r sou n d card in to p owered sp eakers— th at is, sp eakers with bu ilt-in am p lifiers. Using Your St ereo Inst ead of Speakers An oth er altern ative is to p atch you r sou n d card in to you r stereo system for greatly am p lified sou n d . Ch eck th e p lu gs an d jacks at both en d s of th e con n ection . Most stereos u se pin plugs—also called RCA or phono plugs—for in p u t. Alth ou gh p in p lu gs are stan d ard on som e sou n d card s, m ost u se m in iatu re 1/ 8-in ch p h on o p lu gs, wh ich req u ire an ad ap ter wh en con n ectin g to you r stereo system . From Rad io Sh ack, for exam p le, you can p u rch ase an au d io cable th at p rovid es a stereo 1/ 8-in ch m in ip lu g on on e en d an d p h on o p lu gs on th e oth er (Cat. No. 42-2481A). Make su re th at you get stereo, n ot m on o, p lu gs, u n less you r sou n d card su p p orts on ly m on o. To en su re th at you h ave en ou gh cable to reach from th e back of you r PC to you r stereo system , get a six-foot lon g cable. Hookin g u p you r stereo to an au d io ad ap ter is a m atter of slid in g th e p lu gs in to p rop er jacks. If you r au d io ad ap ter gives you a ch oice of ou tp u ts—sp eaker/ h ead p h on e an d stereo lin e ou t—ch oose th e stereo lin e ou t jack for th e con n ection . Th is will give you th e best sou n d q u ality becau se th e sign als from th e stereo lin e ou t jack are n ot am p lified . Th e am p lification is best left to you r stereo system . Con n ect th is cable ou tp u t from you r au d io ad ap ter to th e au xiliary in p u t of you r stereo receiver, p ream p , or in tegrated am p lifier. If you r stereo d oesn ’t h ave an au xiliary in p u t, oth er in p u t op tion s in clu d e—in ord er of p referen ce—tu n er, CD, or Tap e 2. (Do n ot u se p h on o in p u ts, h owever, becau se th e level of th e sign als will be u n even .) You can con n ect th e cable’s sin gle stereo m in ip lu g to th e sou n d card ’s Stereo Lin e Ou t jack, for exam p le, an d th en con n ect th e two RCA p h on o p lu gs to th e stereo’s Tap e/ VCR 2 Playback jacks. Th e first tim e you u se you r au d io ad ap ter with a stereo system , tu rn d own th e volu m e on you r receiver to p reven t blown sp eakers. Barely tu rn u p th e volu m e con trol an d th en select th e p rop er in p u t (su ch as Tap e/ VCR 2) on you r stereo receiver. Fin ally, start you r PC. Never in crease th e volu m e to m ore th an th ree-fou rth s of th e way u p . An y h igh er an d th e sou n d m ay becom e d istorted .

Tricks for Using t he Tape M onit or Circuit of Your St ereo Your receiver might be equipped with something called a tape monitor . This outputs the sound coming from the tuner, tape, or CD to the tape out port on the back, and then expects the sound to come back in on the tape in port. These ports, in conjunction with the line in and line out ports on your audio adapter, enable you to play computer sound and the radio through the same set of speakers. (continues)

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(continued) Here’s how you do it:

1. Turn off the tape monitor circuit on your receiver. 2. Turn down all the controls on the sound card’s mixer application. 3. Connect the receiver’s tape out ports to the audio adapter’s line in port. 4. Connect the audio adapter’s line out port to the receiver’s tape in ports. 5. Turn on the receiver, select some music, and set the volume to a medium level. 6. Turn on the tape monitor circuit. 7. Slowly adjust the line in and main out sliders in the audio adapter’s mixer application until the sound level is about the same as before. 8. Disengage and re-engage the tape monitor circuit while adjusting the output of the audio adapter so that the sound level is the same, whether the tape monitor circuit is engaged or not. 9. Start playing a WAV file. 10. Slowly adjust up the volume slider for the WAV file in the audio adapter’s mixer application until it plays at a level (slightly above, or below the receiver) that is comfortable. Now you can get sounds from your computer, and the radio through the receiver’s speakers.

Troubleshoot ing Sound Card Problem s To op erate, an au d io ad ap ter n eed s h ard ware resou rces, su ch as IRQ n u m bers, a base I/ O ad d ress, an d DMA ch an n els th at d on ’t con flict with oth er d evices. Most ad ap ters com e p recon figu red to u se th e stan d ard Sou n d Blaster resou rces th at h ave com e to be associated with au d io ad ap ters. However, p roblem s occasion ally arise, even with Plu g-an d -Play ad ap ters. Trou blesh ootin g m ay m ean th at you h ave to ch an ge board ju m p ers or switch es, or even recon figu re th e oth er d evices in you r com p u ter. No on e said life was fair. Hardw are ( Resource) Conflict s Th e m ost com m on p roblem for au d io ad ap ters is th at th ey con flict with oth er d evices in stalled in you r PC. You m ay n otice th at you r au d io ad ap ter sim p ly d oesn ’t work (n o sou n d effects or m u sic), rep eats th e sam e sou n d s over an d over, or cau ses you r PC to freeze. Th is situ ation is called a device, or hardware conflict. W h at are th ey figh tin g over? Main ly th e sam e bu s sign al lin es or ch an n els (called resources) u sed for talkin g to you r PC. Th e sou rces of con flict in au d io ad ap ter in stallation s are gen erally th reefold : ■ Interrupt ReQuests (IRQs). Hard ware d evices u se IRQs to “in terru p t” you r PC an d get its atten tion . ■ Direct Mem ory Access (DMA) channels. DMA ch an n els m ove in form ation d irectly to you r PC’s m em ory, byp assin g th e system p rocessor. DMA ch an n els en able sou n d to p lay wh ile you r PC is d oin g oth er work.

Troubleshooting Sound Card Problems

■ Input/Output (I/O) port addresses. You r PC u ses I/ O p ort ad d resses to ch an n el in form ation between th e h ard ware d evices on you r au d io ad ap ter an d you r PC. Th e ad d resses u su ally m en tion ed in a sou n d card m an u al are th e startin g or base ad d resses. An au d io ad ap ter h as several d evices on it, an d each on e u ses a ran ge of ad d resses startin g with a p articu lar base ad d ress. Most au d io ad ap ters in clu d e in stallation software th at an alyzes you r PC an d attem p ts to n otify you sh ou ld an y of th e stan d ard settin gs be in u se by oth er d evices. Th e W in d ows 9x Device Man ager (accessed from th e System Con trol Pan el) can also h elp you to resolve con flicts. Alth ou gh th ese d etection rou tin es can be fairly reliable, u n less a d evice is op eratin g d u rin g th e an alysis, it m ay n ot always be d etectable. Table 9.3 sh ows th e d efau lt resou rces u sed by th e com p on en ts on a typ ical Sou n d Blaster 16 card . Table 9.3

Default Sound Blast er Resource Assignm ent s

Device

Int errupt

I/ O Port s

16-Bit DM A

8-Bit DM A

Audio

IRQ 5

220h-233h

DM A 5

DM A 1

M IDI Port

—

330h-331h

—

—

FM Synthesizer

—

388h-38Bh

—

—

Game Port

—

200h-207h

—

—

All th ese resou rces are u sed by a single sou n d card in you r system . No won d er m an y p eop le h ave con flicts an d p roblem s with au d io ad ap ter in stallation s! In reality, workin g ou t th ese con flicts is n ot all th at h ard , as we sh all see. You can ch an ge m ost of th e resou rces th at au d io ad ap ters u se to altern ate settin gs, sh ou ld th ere be con flicts with oth er d evices; even better, you can ch an ge th e settin gs of th e oth er d evice to elim in ate th e con flict. Note th at som e d evices on th e au d io ad ap ter su ch as th e MIDI Port, FM Syn th esizer, an d Gam e Port d o n ot u se resou rces like IRQs or DMA ch an n els. It is always best to in stall an au d io ad ap ter by u sin g th e d efau lt settin gs wh en ever p ossible. Th is is m ain ly becau se of p oorly written software th at can n ot work p rop erly with altern ate settin gs, even if th ey d o n ot cau se con flicts. In oth er word s, if you are h avin g a con flict with an oth er typ e of ad ap ter, m od ify th e settin gs of th e oth er d evice rath er th an th ose of th e au d io ad ap ter. Take th is from exp erien ce; oth erwise, you will h ave to exp lain to you r five-year old wh y th e n ew Din osau r p rogram you ju st in stalled d oes n ot m ake an y sou n d s! Resolving Resource Conflict s. Th e au d io p ortion of a sou n d card h as a d efau lt IRQ settin g, bu t also su p p orts an y of several altern ate in terru p ts. As stated earlier, you sh ou ld en d eavor to leave th e au d io IRQ at th e d efau lt settin g (u su ally IRQ 5) an d ch an ge th ose of oth er ad ap ters wh ere p ossible. If you r au d io ad ap ter is set to th e sam e IRQ as an oth er d evice in you r system , you m ay see sym p tom s su ch as skip p in g, jerky sou n d , or system locku p s. A typ ical au d io ad ap ter req u ires th e u se of two sim u ltan eou s DMA ch an n els. Th ese are u su ally sp lit in to a req u irem en t for an 8-bit DMA an d a 16-bit DMA ch an n el. Most

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ad ap ters u se DMA 1 for 8-bit sou n d (Creative Labs calls th is Low DMA), an d DMA 5 for 16-bit sou n d (High DMA). Th e p rim ary sym p tom of a DMA con flict in you r system is th at you h ear n o sou n d at all. Solving Hardw are Conflict s. If you u se W in d ows 9x, th e Device Man ager ap p lication can tell you wh ich d evices are u sin g a p articu lar resou rce. If n ot, you m ay h ave to m an u ally resolve an y resou rce con flicts you fin d . Th e best way to m an u ally locate a h ard ware con flict is to gath er all th e d ocu m en tation for you r PC an d its variou s d evices, su ch as th e SCSI in terface ad ap ters, CD-ROM d rives, an d so on . Th is top ic is d iscu ssed m ore com p letely in Ch ap ter 10, “I/ O In terfaces.” Th e m ost com m on cau ses of system resou rce con flicts are th e followin g: ■ SCSI h ost ad ap ters ■ Network in terface card s ■ Bu s m ou se ad ap ter card s ■ Serial p ort ad ap ter card s for COM3: or COM4: ■ Parallel p ort ad ap ter card s for LPT2: ■ In tern al m od em s ■ Scan n er in terface card s On e way to fin d wh ich d evice is con flictin g with you r au d io ad ap ter is to tem p orarily rem ove all th e exp an sion card s from you r system excep t for th e au d io ad ap ter an d essen tial d evices (su ch as th e vid eo ad ap ter). Th en , rep lace each of th e card s you rem oved , on e at a tim e, u n til you r au d io ad ap ter n o lon ger works. Th e last card you ad d ed is th e trou blem aker. Havin g fou n d th e card th at’s cau sin g th e con flict, you can eith er switch th e settin gs for th e d evice th at is con flictin g with you r au d io ad ap ter or ch an ge th e settin gs of th e au d io ad ap ter. In eith er case, you will h ave to ch an ge th e IRQ , DMA, or I/ O ad d ress. To d o th is, you m ay h ave to set ju m p ers or DIP switch es on th e ad ap ter, or u se a con figu ration p rogram su p p lied with th e ad ap ter to ch an ge its settin gs. Ot her Sound Card Problem s Like th e com m on cold , au d io ad ap ter p roblem s h ave com m on sym p tom s. Use th e followin g section s to d iagn ose you r p roblem . No Sound. If you d on ’t h ear an yth in g from you r au d io ad ap ter, con sid er th ese solu tion s: ■ Make su re th at th e au d io ad ap ter is set to u se all d efau lt resou rces, an d th at all oth er d evices u sin g th ese resou rces h ave been eith er recon figu red or rem oved . ■ Are th e sp eakers con n ected ? Ch eck th at th e sp eakers are p lu gged in to th e sou n d card ’s Stereo Lin e Ou t or sp eaker jack (n ot th e Lin e In or m icrop h on e jack).

Troubleshooting Sound Card Problems

■ If you ’re u sin g am p lified sp eakers, are th ey p owered on ? Ch eck th e stren gth of th e batteries or th e AC ad ap ter’s con n ection to th e electrical ou tlet. ■ Are th e sp eakers stereo? Ch eck th at th e p lu g in serted in to th e jack is a stereo p lu g, n ot m on o. ■ Are th e m ixer settin gs h igh en ou gh ? Man y au d io ad ap ters in clu d e a sou n d m ixer ap p lication . Th e m ixer con trols th e volu m e settin gs for variou s sou n d d evices, su ch as th e m icrop h on e or CD p layer. Th ere m ay be sep arate con trols for both record in g an d p layback. In crease th e m aster volu m e or sp eaker volu m e wh en you are in th e p lay m od e. ■ Use you r au d io ad ap ter’s setu p or d iagn ostic software to test an d ad ju st th e volu m e of th e ad ap ter. Su ch software u su ally in clu d es sam p le sou n d s u sed to test th e ad ap ter. ■ Tu rn off you r com p u ter for on e m in u te an d th en tu rn it back on . A h ard reset (as op p osed to p ressin g th e Reset bu tton or p ressin g Ctrl+Alt+Delete) m ay clear th e p roblem . ■ If you r com p u ter gam e lacks sou n d , ch eck th at it is d esign ed to work with you r au d io ad ap ter. For exam p le, som e gam es m ay req u ire th e exact settin gs of IRQ 7, DMA 1, an d ad d ress 220 to be Sou n d Blaster-com p atible. One-Sided Sound. If you h ear sou n d com in g from on ly on e sp eaker, ch eck ou t th ese p ossible cau ses: ■ Are you u sin g a m on o p lu g in th e stereo jack? A com m on m istake is to u se a m on o p lu g in to th e sou n d card ’s sp eaker or stereo ou t jacks. Seen from th e sid e, a stereo con n ector h as two d arker strip es. A m on o con n ector h as on ly on e strip e. ■ Is th e au d io ad ap ter d river load ed ? Som e sou n d card s p rovid e on ly left-ch an n el sou n d if th e d river is n ot load ed correctly. Re-ru n you r ad ap ter’s setu p software or re-in stall it in th e op eratin g system . Volum e Is Low . If you can barely h ear you r sou n d card , try th ese solu tion s: ■ Are th e sp eakers p lu gged in to th e p rop er jack? Sp eakers req u ire a h igh er level of d rive sign al th an h ead p h on es. Again , ad ju st th e volu m e level in you r m ixer ap p lication . ■ Are th e m ixer settin gs too low? Again , ad ju st th e volu m e level in you r m ixer ap p lication . ■ Is th e in itial volu m e too low? If you r au d io ad ap ter h as a th u m bwh eel volu m e con trol, ch eck to m ake su re th at it is n ot tu rn ed d own too low. ■ Are th e sp eakers too weak? Som e sp eakers m ay n eed m ore p ower th an you r au d io ad ap ter can p rod u ce. Try oth er sp eakers or p u t a stereo am p lifier between you r sou n d card an d sp eakers.

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Scrat chy Sound. Scratch y or staticy sou n d can be cau sed by several d ifferen t p roblem s. Im p rovin g th e sou n d m ay be as sim p le as rearran gin g you r h ard ware com p on en ts. Th e followin g list su ggests p ossible solu tion s to th e p roblem of scratch y sou n d : ■ Is you r au d io ad ap ter n ear oth er exp an sion card s? Th e ad ap ter m ay be p ickin g u p electrical in terferen ce from oth er exp an sion card s in sid e th e PC. Move th e au d io card to an exp an sion slot as far away as p ossible from oth er card s. ■ Are you r sp eakers too close to you r m on itor? Th e sp eakers m ay p ick u p electrical n oise from you r m on itor. Move th em farth er away. ■ Are you u sin g a ch eap er au d io ad ap ter with an FM syn th esizer? Som e of th e ad ap ters th at u se FM syn th esis in stead of wavetable sou n d gen eration h ave very p oor q u ality ou tp u t. Man y p eop le h ave been fooled in to th in kin g th ey h ad a d efective sou n d card , wh en in reality it was ju st a p oor-q u ality FM syn th esis card th at sim p ly d oes n ot sou n d good . You can test th is by com p arin g th e sou n d of a MIDI file (wh ich u ses th e FM syn th esizer) with th at of a sou n d file like a W AV (wh ich d oesn ’t). If th e p roblem is th e syn th esizer, th en I recom m en d u p grad in g to an ad ap ter th at d oes wavetable syn th esis so you can get th e fu ll ben efit of h igh q u ality sou n d . Your Com put er W on’t St art . If you r com p u ter won ’t start at all, you m ay n ot h ave in serted th e au d io ad ap ter com p letely in to its slot. Tu rn off th e PC an d th en p ress firm ly on th e card u n til it is seated correctly. Parit y Errors or Ot her Lockups. You r com p u ter m ay d isp lay a m em ory p arity error m essage or sim p ly “crash .” Th is is n orm ally cau sed by resou rce con flicts in on e of th e followin g areas: ■ IRQ (In terru p t ReQu est) ■ DMA (Direct Mem ory Access) ■ I/ O (In p u t/ Ou tp u t) p orts If oth er d evices in you r system are u sin g th e sam e resou rces as you r au d io ad ap ter, crash es, locku p s, or p arity errors can resu lt. You m u st en su re th at m u ltip le d evices in you r system d o n ot sh are th ese resou rces. Follow th e p roced u res ou tlin ed earlier in th is ch ap ter to resolve th e resou rce con flicts. Joyst ick Troubleshoot ing. If you r joystick won ’t work, con sid er th e followin g list of cu res: ■ Are you u sin g two gam e p orts? If you alread y h ave a gam e p ort in stalled in you r PC, th e gam e or joystick p ort p rovid ed on you r au d io ad ap ter m ay con flict with it. Usu ally it is best to d isable an y oth er gam e p orts an d u se th e on e on th e au d io ad ap ter. Man y of th e Mu lti-I/ O or Su p er-I/ O ad ap ters th at com e in PC-com p atible system s featu re gam e p orts th at you sh ou ld d isable wh en you in stall an au d io ad ap ter.

Speakers

■ Is you r com p u ter too fast? Som e fast com p u ters get con fu sed by th e in exp en sive gam e p orts. Du rin g th e h eat of virtu al com bat, for exam p le, you m ay fin d you rself flyin g u p sid e d own or sp iralin g ou t of con trol. Th is is on e sign th at you r gam e p ort is in ad eq u ate. Most of th e gam e ad ap ters bu ilt in to au d io ad ap ters work better th an th e on es on th e Mu lti-I/ O ad ap ters. Th ere are also d ed icated gam e card s available, wh ich can work with faster com p u ters. Th ese gam e card s in clu d e software to calibrate you r joystick an d d u al p orts so th at you can en joy a gam e with a frien d . An oth er solu tion is to ru n you r com p u ter at a slower sp eed , wh ich on som e system s is as easy as p ressin g som e typ e of “d e-tu rbo” bu tton on th e case. Ot her Problem s. Som etim es sou n d p roblem s can be d ifficu lt to solve. Du e to q u irks an d p roblem s with th e way DMA is im p lem en ted in som e m oth erboard ch ip sets, th ere can be p roblem s in teractin g with certain card s or d rivers. Som etim es alterin g th e Ch ip set Setu p op tion s in you r CMOS settin gs can resolve p roblem s. Th ese kin d s of p roblem s can take a lot of trial an d error to solve. Th e PC “stan d ard ” is based loosely on th e coop eration am on g a h an d fu l of com p an ies. Som eth in g as sim p le as on e ven d or’s BIOS or m oth erboard d esign can m ake th e stan d ard n on stan d ard .

Speakers Su ccessfu l bu sin ess p resen tation s, m u ltim ed ia ap p lication s, an d MIDI work d em an d extern al h igh -fid elity stereo sp eakers. Alth ou gh you can u se stan d ard stereo sp eakers, th ey are often too big to fit on or n ear you r d esk. Sm aller booksh elf sp eakers are better. Sou n d card s offer little or n on e of th e am p lification n eed ed to d rive extern al sp eakers. Alth ou gh som e sou n d card s h ave sm all 4-watt am p lifiers, th ey are n ot p owerfu l en ou gh to d rive q u ality sp eakers. Also, con ven tion al sp eakers sittin g n ear you r d isp lay m ay create m agn etic in terferen ce, wh ich can d istort colors an d objects on -screen or ju m ble th e d ata record ed on n earby flop p y d isks or oth er m agn etic m ed ia. To solve th ese p roblem s, com p u ter sp eakers n eed to be sm all, efficien t, an d self-p owered . Also, th ey sh ou ld be p rovid ed with m agn etic sh ield in g, eith er in th e form of ad d ed layers of in su lation in th e sp eaker cabin et or electron ic can cellation of th e m agn etic d istortion .

Caut ion Although most computer speakers are magnetically shielded, do not leave recorded tapes, watches, credit cards, or floppy disks in front of the speakers for long periods of time.

Qu ality sou n d d ep en d s on q u ality sp eakers. A 16-bit au d io ad ap ter m ay p rovid e better sou n d to com p u ter sp eakers, bu t even an 8-bit ad ap ter sou n d s good from a good sp eaker. Con versely, an in exp en sive sp eaker m akes both 8-bit an d 16-bit ad ap ters card s sou n d tin n y.

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Th ere are n ow d ozen s of m od els of PC sp eakers on th e m arket ran gin g from in exp en sive m in isp eakers from Son y, Koss, an d LabTech to larger self-p owered m od els from p restigiou s au d io com p an ies su ch as Bose an d Altec Lan sin g. Man y of th e h igh er-en d sp eaker system s even in clu d e su bwoofers to p rovid e ad d ition al bass resp on se. To evalu ate sp eakers, it h elp s to kn ow th e jargon . Sp eakers are m easu red by th ree criteria: ■ Frequency response. A m easu rem en t of th e ran ge of h igh an d low sou n d s a sp eaker can rep rod u ce. Th e id eal ran ge is from 20Hz to 20KHz, th e ran ge of h u m an h earin g. No sp eaker system rep rod u ces th is ran ge p erfectly. In fact, few p eop le h ear sou n d s above 18KHz. An excep tion al sp eaker m ay cover a ran ge of 30Hz to 23,000KHz. Lesser m od els m ay cover on ly 100Hz to 20,000Hz. Freq u en cy resp on se is th e m ost d ecep tive sp ecification , becau se id en tically rated sp eakers can sou n d com p letely d ifferen t. ■ Total Harm onic Distortion (THD). An exp ression of th e am ou n t of d istortion or n oise created by am p lifyin g th e sign al. Sim p ly p u t, d istortion is th e d ifferen ce between th e sou n d sen t to th e sp eaker an d th e sou n d you h ear. Th e am ou n t of d istortion is m easu red in p ercen tages. An accep table level of d istortion is below .1 p ercen t (on eten th of 1 p ercen t). For som e CD-q u ality record in g eq u ip m en t, a com m on stan d ard is .05 p ercen t. Som e sp eakers h ave a d istortion of 10 p ercen t or m ore. Head p h on es often h ave a d istortion of abou t 2 p ercen t or less. ■ W atts. Usu ally stated as watts per channel, th e am ou n t of am p lification available to d rive th e sp eakers. Ch eck th at th e com p an y m ean s “p er ch an n el” (or RMS) an d n ot total p ower. Man y au d io ad ap ters h ave bu ilt-in am p lifiers, p rovid in g u p to eigh t watts p er ch an n el (m ost p rovid e fou r watts). Th is wattage is n ot en ou gh to p rovid e rich sou n d , h owever, wh ich is wh y m an y sp eakers h ave bu ilt-in am p lifiers. W ith th e flick of a switch or th e p ress of a bu tton , th ese sp eakers am p lify th e sign als th ey receive from th e au d io ad ap ter. If you d o n ot wan t to am p lify th e sou n d , you typ ically leave th e sp eaker switch set to “d irect.” In m ost cases, you ’ll wan t to am p lify th e sign al. PC sp eakers often u se batteries to p ower th e am p lifiers. Becau se th ese sp eakers req u ire so m u ch p ower, you m ay wan t to in vest in an AC ad ap ter, or p u rch ase sp eakers th at u se AC p ower. W ith an AC ad ap ter, you won ’t h ave to bu y n ew batteries every few weeks. If you r sp eakers d id n ’t com e with an AC ad ap ter, you can p ick on e u p from you r local Rad io Sh ack or h ard ware store. Be su re th at th e ad ap ter you p u rch ase m atch es you r sp eakers in voltage an d p olarity. You can con trol th e volu m e an d oth er sou n d attribu tes of you r sp eakers in variou s ways, d ep en d in g on th eir com p lexity an d cost. Typ ically, each sp eaker h as a volu m e kn ob, alth ou gh som e sh are a sin gle volu m e con trol. If on e sp eaker is farth er away th an th e oth er, you m ay wan t to ad ju st th e volu m e accord in gly. Man y com p u ter sp eakers in clu d e a dynam ic bass boost (DBB) switch. Th is bu tton p rovid es a m ore p owerfu l bass an d clearer treble, regard less of th e volu m e settin g. Oth er sp eakers h ave sep arate bass an d treble boost switch es or a th ree-ban d eq u alizer to con trol low, m id d le, an d h igh freq u en cies.

M icrophones

W h en you rely on you r au d io ad ap ter’s p ower rath er th an you r sp eakers’ bu ilt-in am p lifier, th e volu m e an d d yn am ic bass boost con trols h ave n o effect. You r sp eakers are at th e m ercy of th e ad ap ter’s p ower. An 1/ 8-in ch stereo m in ijack con n ects from th e au d io ad ap ter’s ou tp u t jack to on e of th e sp eakers. Th e sp eaker th en sp lits th e sign al an d feed s th rou gh a sep arate cable from th e first sp eaker to th e secon d on e (often referred to as th e “satellite sp eaker”). Before p u rch asin g a set of sp eakers, ch eck th at th e cables between th e sp eakers are lon g en ou gh for you r com p u ter setu p . For exam p le, a tower case sittin g alon gsid e on e’s d esk m ay req u ire lon ger sp eaker wires th an a d esktop com p u ter. Beware of sp eakers th at h ave a tard y bu ilt-in “sleep ” featu re. Su ch sp eakers, wh ich save electricity by tu rn in g th em selves off wh en th ey are n ot in u se, m ay h ave th e an n oyin g h abit of clip p in g th e first p art of a sou n d after a p eriod of in activity. Head p h on es are an op tion wh en you can ’t afford a p rem iu m set of sp eakers. Head p h on es also p rovid e p rivacy an d allow you to p lay you r PC au d io as lou d as you like.

M icrophones Som e au d io ad ap ters com e com p lete with a m icrop h on e, bu t m ost d o n ot. You ’ll n eed on e to record you r voice to a W AV file. Selectin g a m icrop h on e is q u ite sim p le. You n eed on e th at h as an 1/ 8-in ch m in ijack to p lu g in to you r au d io ad ap ter’s m icrop h on e, or au d io in , jack. Most m icrop h on es h ave an on / off switch . Like sp eakers, m icrop h on es are m easu red by th eir freq u en cy ran ge. Th is is n ot an im p ortan t bu yin g factor, h owever, becau se th e h u m an voice h as a lim ited ran ge. If you are record in g on ly voices, con sid er an in exp en sive m icrop h on e th at covers a lim ited ran ge of freq u en cies. An exp en sive m icrop h on e’s record in g cap abilities exten d to freq u en cies ou tsid e th e voice’s ran ge. W h y p ay for som eth in g you won ’t be n eed in g? If you are record in g m u sic, in vest in an exp en sive m icrop h on e, bu t m ake su re th at you r au d io ad ap ter can d o ju stice to th e sign al p rod u ced by th e m icrop h on e. A h igh -q u ality m icrop h on e can p rod u ce m ed iocre resu lts wh en p aired with a ch eap 8-bit au d io ad ap ter. You r biggest d ecision is to select a m icrop h on e th at su its you r record in g style. If you work in a n oisy office, you m ay wan t an u n id irection al m icrop h on e th at will p reven t extran eou s n oises from bein g record ed . An om n id irection al m icrop h on e is best for record in g a grou p con versation . Most h igh er-p riced au d io ad ap ters in clu d e a m icrop h on e of som e typ e. Th is can be a sm all lap el m icrop h on e, a h an d -h eld m icrop h on e, or on e with a d esktop stan d . If you wan t to leave you r h an d s free, you m ay wan t to sh u n th e trad ition al h an d -h eld m icrop h on e for a lap el or d esktop m od el. If you r au d io ad ap ter d oes n ot com e with a m icrop h on e, see you r local stereo or electron ics p arts store. Be su re th at an y m icrop h on e you p u rch ase h as th e correct im p ed an ce to m atch th e au d io ad ap ter’s in p u t.

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10

I/ O Interfaces

W h en th in kin g abou t In p u t/ Ou tp u t d evices, it’s easy to categorize on ly serial p orts, p arallel p orts, Un iversal Serial Bu s, an d FireW ire (IEEE-1394) as bein g I/ O in terfaces. I cover th ese top ics in -d ep th in th is ch ap ter. It’s im p ortan t to rem em ber th at SCSI an d IDE are I/ O in terfaces too.

Th is ch ap ter covers th e m ajor I/ O in terfaces u sed in PCs tod ay. W h en d iscu ssin g I/ O in terfaces for d rives, I talk m ostly abou t SCSI an d IDE becau se th ese are th e m ost p op u lar h igh -sp eed storage in terfaces u sed tod ay.

Serial and Parallel Port s Th e m ost basic com m u n ication s p orts in an y PC system are th e serial an d p arallel p orts. Th e serial p orts were origin ally u sed for d evices th at m u st com m u n icate bid irection ally with th e system . Su ch d evices in clu d e m od em s, m ice, scan n ers, d igitizers, an d an y oth er d evices th at “talk to” an d receive in form ation from th e PC. Newer p arallel p ort stan d ard s n ow allow th e p arallel p ort to p erform h igh -sp eed bid irection al com m u n ication s. Several com p an ies m an u factu re com m u n ication s p rogram s th at p erform h igh -sp eed tran sfers between PC system s u sin g serial or p arallel p orts. Version s of th ese file tran sfer p rogram s h ave been in clu d ed with DOS 6.0 an d h igh er (In terlin k), an d W in d ows 95 an d n ewer version s (DCC—Direct Cable Con n ection ). Several p rod u cts are cu rren tly on th e m arket th at m ake n on trad ition al u se of th e p arallel p ort. You can p u rch ase n etwork ad ap ters, h igh cap acity flop p y d isk d rives, CD-ROM d rives, or tap e backu p u n its th at attach to th e p arallel p ort, for exam p le. Serial Port s Th e asynchronous serial interface was d esign ed as a system -to-system com m u n ication s p ort. Asynchronous m ean s th at n o syn ch ron ization or clockin g sign al is p resen t, so ch aracters m ay be sen t with an y arbitrary tim e sp acin g. Each ch aracter sen t over a serial con n ection is fram ed by a stan d ard start-an d stop sign al. A sin gle 0 bit, called th e start bit, p reced es each ch aracter to tell

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th e receivin g system th at th e n ext 8 bits con stitu te a byte of d ata. On e or two stop bits follow th e ch aracter to sign al th at th e ch aracter h as been sen t. At th e receivin g en d of th e com m u n ication , ch aracters are recogn ized by th e start-an d -stop sign als in stead of by th e tim in g of th eir arrival. Th e asyn ch ron ou s in terface is ch aracter-orien ted an d h as abou t a 20% overh ead for th e extra in form ation n eed ed to id en tify each ch aracter. Serial refers to d ata sen t over a sin gle wire, with each bit lin in g u p in a series as th e bits are sen t. Th is typ e of com m u n ication is u sed over th e p h on e system , becau se th is system p rovid es on e wire for d ata in each d irection . Ad d -on serial p orts for th e PC are available from m an y m an u factu rers. You u su ally can fin d th ese p orts on on e of th e m u ltifu n ction board s available or on a board with at least a p arallel p ort. Virtu ally all m od ern m oth erboard s in clu d e a bu ilt-in Su p er I/ O ch ip th at ad d s on e or two serial p orts to th e m oth erboard , m ean in g n o ad d ition al in terface card is req u ired . Old er system s n orm ally h ave th e serial p orts on a card . Note th at card -based m od em s also in corp orate a bu ilt-in serial p ort on th e card as p art of th e m od em circu itry. Figu re 10.1 sh ows th e stan d ard 9-p in con n ector u sed with m ost m od ern extern al serial p orts. Figu re 10.2 sh ows th e origin al stan d ard 25-p in version .

5

1

External Device

Carrier Detect

1

Receive Data

2

Transmit Data

3

Data Terminal Ready

4

Signal Ground

5

Data Set Ready Request To Send

6 7

Clear To Send

8

Ring Indicator

9

FIG. 10.1 AT-style 9-p in serial-p ort con n ector sp ecification s.

9 6

Serial Parallel Adapter

Serial and Parallel Ports

25-Pin D-Shell connector

Description

External Device

13

25

1

14

Pin

NC

1

Transmitted Data

2

Received Data

3

Request to Send

4

Clear to Send

5

Data Set Ready Signal Ground

6 7

Received Line Signal Detector

8

+ Transmit Current Loop Data

9

NC

10

- Transmit Current Loop Data

11

NC

12

NC

13

NC

14

NC

15

NC

16

NC

17

+ Receive Current Loop Data

18

NC

19

Data Terminal Ready

20

NC

21

Ring Indicator

22

NC

23

NC

24 25

- Receive Current Loop Return

Asynchronous Communications Adapter (RS-232C)

FIG. 10.2 Stan d ard 25-p in serial-p ort con n ector sp ecification s. Serial p orts m ay con n ect to a variety of d evices su ch as m od em s, p lotters, p rin ters, oth er com p u ters, bar cod e read ers, scales, an d d evice con trol circu its. Basically, an yth in g th at n eed s a two-way con n ection to th e PC u ses th e in d u stry-stan d ard Referen ce Stan d ard n u m ber 232 revision C (RS-232C) serial p ort. Th is d evice en ables d ata tran sfer between oth erwise in com p atible d evices.

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Th e official sp ecification recom m en d s a m axim u m cable len gth of 50 feet. Th e lim itin g factor is th e total load cap acitan ce of cable an d in p u t circu its of th e in terface. Th e m axim u m cap acitan ce is sp ecified as 2500 p F. Sp ecial low-cap acitan ce cables are available th at can effectively in crease th e m axim u m cable len gth greatly, to as m u ch as 500 feet or m ore. Also lin e d rivers (am p lifier/ rep eaters) are available th at can exten d cable len gth even fu rth er. Tables 10.1, 10.2, an d 10.3 sh ow th e p in ou ts of th e 9-p in (AT-style), 25-p in , an d 9-p in to-25-p in serial con n ectors. Table 10.1

9-Pin ( AT) Serial Port Connect or

Pin

Signal

Descript ion

I/ O

1

CD

Carrier detect

In

2

RD

Receive data

In

3

TD

Transmit data

Out

4

DTR

Data terminal ready

Out

5

SG

Signal ground

—

6

DSR

Data set ready

In

7

RTS

Request to send

Out

8

CTS

Clear to send

In

9

RI

Ring indicator

In

Table 10.2

25-Pin ( PC, XT, and PS/ 2) Serial Port Connect or

Pin

Signal

Descript ion

I/ O

1

—

Chassis ground

—

2

TD

Transmit data

Out

3

RD

Receive data

In

4

RTS

Request to send

Out

5

CTS

Clear to send

In

6

DSR

Data set ready

In

7

SG

Signal ground

—

8

CD

Carrier detect

In

9

—

+Transmit current loop return

Out

11

—

–Transmit current loop data

Out

18

—

+Receive current loop data

In

20

DTR

Data terminal ready

Out

22

RI

Ring indicator

In

25

—

-Receive current loop return

In

Serial and Parallel Ports

Table 10.3

9-Pin t o 25-Pin Serial Cable Adapt er Connect ions

9-Pin

25-Pin

Signal

1

8

CD

Carrier detect

2

3

RD

Receive data

3

2

TD

Transmit data

4

20

DTR

Data terminal ready

5

7

SG

Signal ground

6

6

DSR

Data set ready

7

4

RTS

Request to send

8

5

CTS

Clear to send

9

22

RI

Ring indicator

Descript ion

Not e M acintosh systems use a similar serial interface defined as RS-422. M ost external modems in use today can interface with either RS-232 or RS-422, but it is safest to make sure that the external modem you get for your PC is designed for a PC, not a M acintosh.

UARTs. Th e h eart of an y serial p ort is th e Universal Asynchronous Receiver/Transm itter (UART) chip. Th is ch ip com p letely con trols th e p rocess of breakin g th e n ative p arallel d ata with in th e PC in to serial form at, an d later con vertin g serial d ata back in to th e p arallel form at. Th ere are several typ es of UART ch ip s on th e m arket. Th e origin al PC an d XT u sed th e 8250 UART, wh ich was u sed for m an y years in low-p riced serial card s. Startin g with th e first 16-bit system s, th e 16450 UART was n orm ally u sed . Th e on ly d ifferen ce between th ese ch ip s is th eir su itability for h igh -sp eed com m u n ication s. Th e 16450 is better su ited for h igh -sp eed com m u n ication s th an th e 8250; oth erwise, both ch ip s ap p ear id en tical to m ost software. Th e 16550 UART was th e first serial ch ip u sed in th e IBM PS/ 2 lin e, an d oth er 386 an d h igh er system s rap id ly ad op ted it. Th is ch ip cou ld fu n ction as th e earlier 16450 an d 8250 ch ip s, bu t it also in clu d ed a 16-byte bu ffer th at aid ed in faster com m u n ication s. Th is is som etim es referred to as a FIFO (first in/first out) buffer. Un fortu n ately, th e early 16550 ch ip s h ad a few bu gs, p articu larly in th e bu ffer area. Th ese bu gs were corrected with th e release of th e 16550A. Th e m ost cu rren t version of th e ch ip is th e 16550D, wh ich is p rod u ced by Nation al Sem icon d u ctor.

Tip The high-speed buffered 16550A (or newer) UART chip is pin-for-pin compatible with the 16450 UART. If your 16450 UART is socketed, it is a cheap and easy way to improve serial performance to install a 16550 UART chip in the socket.

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Becau se th e 16550 is a faster, m ore reliable ch ip th an its p red ecessors, it is best to en su re you r serial p orts eith er h ave th at ch ip or an eq u ivalen t. Most m oth erboard s tod ay th at h ave bu ilt-in serial p orts u se a Su p er I/ O ch ip th at con tain s th e serial p ort UARTs with in it. If you are in d ou bt abou t wh ich typ e of UART you h ave in you r system , you can u se th e Microsoft MSD p rogram (p rovid ed with W in d ows, MS DOS 6.x, an d W in d ows 95) to d eterm in e th e typ e of UART you h ave.

Not e Another way to tell if you have a 16650 UART in Windows 95 or 98 is to click the Start menu, choose Settings, Control Panel, double-click M odems, then click the Diagnostics tab. The Diagnostics tab shows a list of all COM ports in the system, even if they don’t have a modem attached to them. Select the port you want to check in the list and click M ore Info. Windows 95 or 98 will communicate with the port to determine the UART type and that information will be listed in the Port Information portion of the M ore Info box. If a modem was attached, then you will see additional information about the modem displayed.

Th e origin al d esign er of th ese UARTs is Nation al Sem icon d u ctor (NS). Man y oth er m an u factu rers are p rod u cin g clon es of th ese UARTs, su ch th at you p robably d on ’t h ave an actu al NS bran d p art in you r system . Even so, th e p art you h ave will be com p atible with on e of th e NS p arts, h op efu lly th e 16550. In oth er word s, you sh ou ld ch eck to see th at wh atever UART ch ip you d o h ave d oes in d eed featu re th e 16-byte FIFO bu ffer as fou n d in th e NS 16550 p art. Most m oth erboard s n ow in clu d e Su p er I/ O in tegrated ch ip s th at take on th e fu n ction s of m u ltip le sep arate ch ip s. Most of th ese in tegrated ch ip s fu n ction as a 16550 wou ld ; h owever, som e u sed on old er m oth erboard s m ay n ot. √√ See “ Super I/ O Chips” p. 207

Table 10.4 lists th e stan d ard UART ch ip typ es u sed in PC system s. Table 10.4

UART Chips in PC Syst em s

Chip

Descript ion

8250

IBM used this original chip in the PC serial port card. This chip has no transmit/ receive buffer, which means it is very slow. The chip has several bugs, none of which is serious. The PC and XT ROM BIOS are written to anticipate at least one of the bugs. This chip was replaced by the 8250B.

8250A

Do not use the second version of the 8250 in any system. This upgraded chip fixes several bugs in the 8250, including one in the interrupt enable register, but because the PC and XT ROM BIOS expect the bug, this chip does not work properly with those systems. The 8250A should work in an AT system that does not expect the bug, but does not work adequately at 9600bps.

8250B

The last version of the 8250 fixes bugs from the previous two versions. The interrupt enable bug in the original 8250, expected by the PC and XT ROM BIOS software, has been put back into this chip, making the 8250B the most desirable chip for any non-AT serial port application. The 8250B chip may work in an AT under DOS, but does not run properly at 9600bps because like all 8250s it has no transmit/ receive buffer.

Serial and Parallel Ports

Chip

Descript ion

16450

IBM selected the higher-speed version of the 8250 for the AT. The higher performance mainly comes from a 1-byte transmit/ receive buffer contained within the chip. Because this chip has fixed the interrupt enable bug mentioned earlier, the 16450 does not operate properly in many PC or XT systems, because they expect this bug to be present. OS/ 2 requires this chip as a minimum, or the serial ports do not function properly. It also adds a scratch-pad register as the highest register. The 16450 is used primarily in AT systems because of its increase in throughput over the 8250B.

16550A

This chip is pin-compatible with the 16450, but is much faster due to a built-in 16character Transmit and Receive FIFO (First In First Out) buffer. It also allows multiple DM A channel access. The original version of this chip would not allow the buffer to work but all 16550A or later revisions had the bug fixed. The last version produced by National Semiconductor was called the 16550D. You should use a version of this UART in your serial port if you do any communications at 9600bps or higher. If your communications program makes use of the FIFO, which all do today, it can greatly increase communications speed and eliminate lost characters and data at the higher speeds. Virtually all Super I/ O chips contain the equivalent of dual 16550A or later chips. M ost 16550 UARTs have a maximum communications speed of 115Kbps (bits per second).

16650

Several companies have produced versions with larger buffers that they have called 16650 and 16750. These chips are not from National Semiconductor and the designations are only to imply that they are compatible with the 16550 but have a larger buffer. The 16650 chips normally have a 32-byte buffer while the 16750 chips have a 64-byte buffer. These larger buffered versions allow speeds of 230K or 460Kbps and are recommended when running a high-speed external communications link such as an ISDN terminal adapter. These are discussed more in the following section.

High-Speed Serial Port s. Som e m od em m an u factu rers h ave gon e a step fu rth er on im p rovin g serial d ata tran sfer by in trod u cin g Enhanced Serial Ports (ESP) or Super High Speed Serial Ports. Th ese p orts en able a 28.8Kbp s or faster m od em to com m u n icate with th e com p u ter at d ata rates u p to 921.6Kbp s. Th e extra sp eed on th ese p orts is gen erated by in creasin g th e bu ffer size. Th ese p orts are u su ally based on a 16550, 16650, or 16750 UART an d som e even in clu d e m ore bu ffer m em ory on th e card . Most will allow raw p ort sp eed settin gs of 230Kbp s or 460Kbp s, wh ich is very valu able wh en con n ectin g a PC to a h igh -sp eed extern al com p on en t con n ected to a serial p ort, su ch as an ISDN term in al ad ap ter. You can ’t really get th e fu ll-sp eed ben efit of an extern al ISDN m od em (term in al ad ap ter) u n less you r serial p ort can go at least 230Kbp s. Lava Com p u ter Mfg. is on e com p an y th at offers a com p lete lin e of h igh -sp eed serial an d p arallel p ort card s (see Ap p en d ix A, “Ven d or List”). As th e n eed for ad d ition al serial d evices con tin u es to in crease, u sers are begin n in g to n eed m ore th an th e stan d ard two COM p orts th at are bu ilt in to m ost m od ern m oth erboard s. As a resu lt, m ulti-port serial cards were created . Th ese card s gen erally h ave 2–32 p orts on th em . Often , th ey also p rovid e h igh er bau d rates th an can be ach ieved on a stan d ard serial p ort. Most of th e m u lti-p ort serial card s on th e m arket u se stan d ard 16550 UARTs with a p rocessor (typ ically an 80×86 based p rocessor) an d som e m em ory. Th ese card s can im p rove p erform an ce sligh tly becau se th e p rocessor is d ed icated to h an d lin g serial in form ation . However, it’s n ot always th e best m eth od for h igh -p erform an ce ap p lication s.

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Som e of th e better m u lti-p ort serial card s h ave broken th e m od el of th e 16550 UART in favor of a sin gle in tegrated circu it. Th ese card s h ave th e ad van tage of h igh er su stain able th rou gh p u t with ou t loss. Variou s m an u factu rers m ake version s of th e 16550; Nation al Sem icon d u ctor was th e first. Th e cu rren t version is a 40-p in DIP (Du al In -lin e Pin p ackage) ch ip called th e NS16550D. You can con tact Fry’s Electron ics or Jam eco Electron ics to obtain th e NS16550D, for exam p le. Serial-Port Configurat ion. Each tim e a ch aracter is received by a serial p ort, it h as to get th e atten tion of th e com p u ter by raisin g an Interrupt Request Line (IRQ). Eigh t-bit ISA bu s system s h ave eigh t of th ese lin es, an d system s with a 16-bit ISA bu s h ave 16 lin es. Th e 8259 in terru p t con troller ch ip u su ally h an d les th ese req u ests for atten tion . In a stan d ard con figu ration , COM1 u ses IRQ4, an d COM2 u ses IRQ3. W h en a serial p ort is in stalled in a system , it m u st be con figu red to u se sp ecific I/ O ad d resses (called ports), an d in terru p ts (called IRQs for In terru p t Req u est). Th e best p lan is to follow th e existin g stan d ard s for h ow th ese d evices sh ou ld be set u p . For con figu rin g serial p orts, you sh ou ld u se th e ad d resses an d in terru p ts in d icated in Table 10.5. Table 10.5

St andard Serial I/ O Port Addresses and Int errupt s

Syst em

COM x

Port

IRQ

All

COM 1

3F8-3FFh

IRQ4

All

COM 2

2F8-2FFh

IRQ3

ISA bus

COM 3

3E8-3EFh

IRQ4*

ISA bus

COM 4

2E8-2EFh

IRQ3*

*Note that although m any serial ports can be set up to share IRQ 3 and 4 with COM1 and COM2, it is not recom m ended. The best recom m endation is setting COM3 to IRQ 10 and COM4 to IRQ 11 (if available). If ports above COM3 are required, it is recom m ended that you purchase a special m ulti-port serial board.

You sh ou ld en su re th at if you are ad d in g m ore th an th e stan d ard COM1 an d COM2 serial p orts, th ey u se u n iq u e an d n on -con flictin g in terru p ts. If you p u rch ase a serial p ort ad ap ter card an d in ten d to u se it to su p p ly p orts beyon d th e stan d ard COM1 an d COM2, be su re th at it can u se in terru p ts oth er th an IRQ3 an d IRQ4. An oth er p roblem if you are still u sin g DOS or DOS-based 16-bit p rogram s is th at th e BIOS m an u factu rers n ever bu ilt su p p ort for COM3 an d COM4 in to th e BIOS. Th erefore, th e DOS MODE com m an d can n ot work with serial p orts above COM2 becau se DOS gets its I/ O in form ation from th e BIOS. Th e BIOS fin d s ou t wh at is in stalled in you r system an d wh ere it is in stalled d u rin g th e POST (Power On Self Test). Th e POST ch ecks on ly for th e first two in stalled p orts. Th is is n ot a p roblem at all u n d er W in d ows becau se both W in d ows 95 an d 98 h ave bu ilt-in su p p ort for u p to 128 p orts. To get arou n d th is p roblem in a DOS en viron m en t, m ost com m u n ication s software an d som e serial p erip h erals (su ch as m ice) su p p ort h igh er COM p orts by ad d ressin g th em d irectly, rath er th an m akin g DOS fu n ction calls. Th e p op u lar DOS com m u n ication s p rogram Procom m , for exam p le, su p p orts th e ad d ition al p orts even if you r BIOS or DOS

Serial and Parallel Ports

d oes n ot. Of cou rse, if you r system or software d oes n ot su p p ort th ese extra p orts or you n eed to red irect d ata u sin g th e MODE com m an d , trou ble arises. Becau se W in d ows 95/ 98 su p p ort 128 p orts, sp ecial d rivers or com m u n ication s software is n ot n orm ally n ecessary. W ith su p p ort for u p to 128 serial p orts in W in d ows 95 an d W in d ows 98, it is m u ch easier to u se m u lti-p ort board s in th e system . Multi-port boards give you r system th e cap ability to collect or sh are d ata with m u ltip le d evices, wh ile u sin g on ly on e slot an d on e in terru p t.

Caut ion Sharing interrupts between COM ports or any devices can function properly sometimes and not others. It is recommended that you never share interrupts between multiple serial ports. It will cause you hours of frustration trying to track down drivers, patches, and updates to allow this to work successfully—if it’s even possible at all in your system.

√√ See “ Resolving Resource Conflicts,” p. 281

Test ing Serial Port s You can p erform several tests on serial an d p arallel p orts. Th e two m ost com m on typ es of tests in volve software on ly, or both h ard ware an d software. Th e software-on ly tests are d on e with d iagn ostic p rogram s su ch as Microsoft’s MSD, wh ile th e h ard ware an d software tests in volve u sin g a wrap p lu g to p erform loop back testin g. M icrosoft Diagnost ics ( M SD) . MSD is a d iagn ostic p rogram su p p lied with MS-DOS 6.x, Microsoft W in d ows, an d W in d ows 95. Early version s of th e p rogram also were sh ip p ed with som e Microsoft ap p lication s su ch as Microsoft W ord for DOS. Note th at with W in d ows 95, th is p rogram can be fou n d on th e CD in th e \ oth er\ m sd d irectory. In W in d ows 98, you can fin d it on th e CD in th e \ tools\ old m sd os d irectory. MSD is n ot au tom atically in stalled wh en you in stall th e op eratin g system . To u se it, you m u st ru n it from th e CD d irectly or cop y th e p rogram from th e CD to you r h ard d isk. Man y d iagn ostics p rogram s su ch as MSD are best ru n in a DOS-on ly en viron m en t for th e m ost accu rate resu lts. Becau se of th is, you sh ou ld restart th e m ach in e in DOS m od e before u sin g th em . Th en to u se MSD, switch to th e d irectory in wh ich it is located . Th is is n ot n ecessary, of cou rse, if th e d irectory con tain in g th e p rogram is in you r search p ath — wh ich is often th e case with th e DOS 6.x or W in d ows-p rovid ed version s of MSD. Th en sim p ly typ e MSD at th e DOS p rom p t an d p ress En ter. Soon you see th e MSD screen . Ch oose th e Serial Ports op tion . Notice th at you are p rovid ed in form ation abou t wh ich typ e of serial ch ip you h ave in you r system , an d in form ation abou t wh ich p orts are available. If an y of th e p orts are in u se (with a m ou se, for exam p le), th at in form ation is p rovid ed as well.

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MSD is h elp fu l in at least d eterm in in g wh eth er you r serial p orts are resp on d in g. If MSD can n ot d eterm in e th e existen ce of a p ort, it d oes n ot p rovid e th e rep ort in d icatin g th at th e p ort exists. Th is sort of “look-an d -see” test is th e first action I u su ally take to d eterm in e wh y a p ort is n ot resp on d in g. W indow s 95/ 98 Diagnost ics. W in d ows 95/ 98 also sh ow wh eth er or n ot you r p orts are fu n ction in g. To ch eck you r p orts, righ t-click My Com p u ter an d ch oose Prop erties. Ch oose th e Device Man ager tab. On th e Device Man ager screen , if a d evice is n ot workin g p rop erly th ere will be an exclam ation p oin t in a yellow circle n ext to th e d evice on th e list. You can also d ou ble-click Ports (COM & LPT), an d th en d ou ble-click th e d esired p ort to see wh eth er W in d ows 95/ 98 says th at th e p ort is fu n ction in g or n ot. In m an y cases, it tells you wh at is con flictin g with th at sp ecific p ort. Advanced Diagnost ics Using Loopback Test ing. On e of th e m ost u sefu l tests is th e loopback test, wh ich can be u sed to en su re th e correct fu n ction of th e serial p ort, an d an y attach ed cables. Loop back tests basically are in tern al (d igital), or extern al (an alog). In tern al tests can be ru n sim p ly by u n p lu ggin g an y cables from th e p ort an d execu tin g th e test via a d iagn ostics p rogram . Th e extern al loop back test is m ore effective. Th is test req u ires th at a sp ecial loop back con n ector or wrap p lu g be attach ed to th e p ort in q u estion . W h en th e test is ru n , th e p ort is u sed to sen d d ata ou t to th e loop back p lu g, wh ich sim p ly rou tes th e d ata back in to th e p ort’s receive p in s so th at th e p ort is tran sm ittin g an d receivin g at th e sam e tim e. A loop back or wrap p lu g is n oth in g m ore th an a cable d ou bled back on itself. Most d iagn ostics p rogram s th at ru n th is typ e of test in clu d e th e loop back p lu g, an d if n ot, th ese typ es of p lu gs can be p u rch ased easily or even bu ilt. Th e wirin g n eed ed to con stru ct you r own loop back or wrap p lu gs is as follows: ■ Stan d ard IBM typ e 25-Pin Serial (Fem ale DB25S) Loop back Con n ector (W rap Plu g). Con n ect th ese p in s: 1 to 7 2 to 3 4 to 5 to 8 6 to 11 to 20 to 22 15 to 17 to 23 18 to 25 ■ Norton Utilities (Sym an tec) 25-Pin Serial (Fem ale DB25S) Loop back Con n ector (W rap Plu g). Con n ect th ese p in s: 2 to 3 4 to 5 6 to 8 to 20 to 22

Serial and Parallel Ports

■ Stan d ard IBM typ e 9-Pin Serial (Fem ale DB9S) Loop back Con n ector (W rap Plu g). Con n ect th ese p in s: 1 to 7 to 8 2 to 3 4 to 6 to 9 ■ Norton Utilities (Sym an tec) 9-Pin Serial (Fem ale DB9S) Loop back Con n ector (W rap Plu g). Con n ect th ese p in s: 2 to 3 7 to 8 1 to 4 to 6 to 9 On e ad van tage of u sin g loop back con n ectors is th at you can p lu g th em in to th e en d s of a cable th at in clu d es th e cable in th e test. Th is can verify th at both th e cable an d th e p ort are workin g p rop erly. If you n eed to test serial p orts fu rth er, refer to Ch ap ter 17 “Diagn ostics, Testin g, an d Main ten an ce,” wh ich d escribes th ird -p arty testin g software. Parallel Port s A parallel port h as eigh t lin es for sen d in g all th e bits th at com p rise 1 byte of d ata sim u ltan eou sly across eigh t wires. Th is in terface is fast an d h as trad ition ally been u sed for p rin ters. However, p rogram s th at tran sfer d ata between system s h ave always u sed th e p arallel p ort as an op tion for tran sm ittin g d ata becau se it can d o so 4 bits at a tim e rath er th an 1 bit at a tim e with a serial in terface. In th e followin g section , we’ll look at h ow th ese p rogram s tran sfer d ata between p arallel p orts. Th e on ly p roblem with p arallel p orts is th at th eir cables can n ot be exten d ed for an y great len gth with ou t am p lifyin g th e sign al or errors occu r in th e d ata. Table 10.6 sh ows th e p in ou t for a stan d ard PC p arallel p ort. Table 10.6 Pin

25-Pin PC-Com pat ible Parallel Port Connect or Descript ion

I/ O

1

–Strobe

Out

2

+Data Bit 0

Out

3

+Data Bit 1

Out

4

+Data Bit 2

Out

5

+Data Bit 3

Out

6

+Data Bit 4

Out

7

+Data Bit 5

Out

8

+Data Bit 6

Out

9

+Data Bit 7

Out (continues)

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Table 10.6

25-Pin PC-Com pat ible Parallel Port Connect or Cont inued

Pin

Descript ion

I/ O

10

–Acknowledge

In

11

+Busy

In

12

+Paper End

In

13

+Select

In

14

–Auto Feed

Out

15

–Error

In

16

–Initialize Printer

Out

17

–Select Input

Out

18

–Data Bit 0 Return (GND)

In

19

–Data Bit 1 Return (GND)

In

20

–Data Bit 2 Return (GND)

In

21

–Data Bit 3 Return (GND)

In

22

–Data Bit 4 Return (GND)

In

23

–Data Bit 5 Return (GND)

In

24

–Data Bit 6 Return (GND)

In

25

–Data Bit 7 Return (GND)

In

Over th e years, several typ es of p arallel p orts h ave evolved . Here are th e p rim ary typ es of p arallel p orts fou n d in system s tod ay: ■ Un id irection al (4-bit) ■ Bid irection al (8-bit) ■ En h an ced Parallel Port (EPP) ■ En h an ced Cap abilities Port (ECP) Th e followin g section s d iscu ss each of th ese typ es of p arallel p orts. Unidirect ional ( 4-bit ) . Old er PCs d id n ot h ave d ifferen t typ es of p arallel p orts available. Th e on ly p ort available was th e p arallel p ort u sed to sen d in form ation from th e com p u ter to a d evice, su ch as a p rin ter. Th is is n ot to say th at bid irection al p arallel p orts were n ot available; in d eed , th ey were com m on in oth er com p u ters on th e m arket an d in h obbyist com p u ters at th e tim e. Th e u n id irection al n atu re of th e origin al PC p arallel p ort is con sisten t with its p rim ary u se—th at is, of sen d in g d ata to a p rin ter. Th ere were tim es, h owever, wh en it was d esirable to h ave a bid irection al p ort—for exam p le, wh en you n eed feed back from a p rin ter, wh ich is com m on with PostScrip t p rin ters. Th is cou ld n ot be d on e easily with th e origin al u n id irection al p orts. Alth ou gh it was n ever in ten d ed to be u sed for in p u t, a clever sch em e was d evised wh ere fou r of th e sign al lin es cou ld be u sed as a 4-bit in p u t con n ection . Th u s, th ese p orts can d o 8-bit byte ou tp u t an d 4-bit (n ibble) in p u t. Th is is still very com m on on low-en d

Serial and Parallel Ports

d esktop system s. System s bu ilt after 1993 are likely to h ave m ore cap able p arallel p orts, su ch as 8-bit, EPP, or ECP. 4-bit p orts are cap able of effective tran sfer rates of abou t 40–60K/ sec with typ ical d evices an d can be p u sh ed to u p ward s of 140K/ sec with certain d esign tricks. Bidirect ional ( 8-bit ) . W ith th e in trod u ction of th e PS/ 2 in 1987, IBM in trod u ced th e bid irection al p arallel p ort. Th ese are com m on ly fou n d in PC-com p atible system s tod ay, an d m ay be d esign ated “PS/ 2 typ e,” “bid irection al,” or “exten d ed ” p arallel p ort. On n ewer system s with m u lti-m od e p orts, th is m od e is often called “stan d ard ” or “Cen tron ics” m od e, an d rep resen ts th e lowest p erform an ce settin g. Th is p ort d esign op en ed th e way for tru e com m u n ication s between th e com p u ter an d th e p erip h eral across th e p arallel p ort. Th is was d on e by d efin in g a few of th e p reviou sly u n u sed p in s in th e p arallel con n ector, an d d efin in g a statu s bit to in d icate in wh ich d irection in form ation was travelin g across th e ch an n el. Th ese p orts can d o both 8-bit in p u t an d ou tp u t u sin g th e stan d ard eigh t d ata lin es, an d are con sid erably faster th an th e 4-bit p orts wh en u sed with extern al d evices. 8-bit p orts are cap able of sp eed s ran gin g from 80–300K/ sec, d ep en d in g on th e sp eed of th e attach ed d evice, th e q u ality of th e d river software, an d th e p ort’s electrical ch aracteristics. Enhanced Parallel Port ( EPP) . EPP is a n ewer sp ecification som etim es referred to as th e Fast Mode parallel port. Th e EPP was d evelop ed by In tel, Xircom , an d Zen ith Data System s an d an n ou n ced in October 1991. Th e first p rod u cts to offer EPP were ZDS lap top s, Xircom Pocket LAN Ad ap ters, an d th e In tel 82360 SL I/ O ch ip . EPP op erates alm ost at ISA bu s sp eed , an d offers a 10-fold in crease in th e raw th rou gh p u t cap ability over a con ven tion al p arallel p ort. EPP is esp ecially d esign ed for p arallel p ort p erip h erals su ch as LAN ad ap ters, d isk d rives, an d tap e backu p s. EPP h as been in clu d ed in th e n ew IEEE 1284 Parallel Port stan d ard . Tran sfer rates of 1 to 2M/ sec are p ossible with EPP. Sin ce th e origin al In tel 82360 SL I/ O ch ip in 1992, oth er m ajor ch ip ven d ors (su ch as Nation al Sem icon d u ctor, SMC, W estern Digital, an d VLSI) h ave also p rod u ced I/ O ch ip sets offerin g som e form of EPP cap ability. On e p roblem is th at th e p roced u re for en ablin g EPP across th e variou s ch ip s d iffers wid ely from ven d or to ven d or, an d m an y ven d ors offer m ore th an on e I/ O ch ip . EPP version 1.7 (March 1992) id en tifies th e first p op u lar version of th e h ard ware sp ecification . W ith m in or ch an ges, th is h as sin ce been aban d on ed an d fold ed in to th e IEEE 1284 stan d ard . Som e tech n ical referen ce m aterials h ave erron eou sly m ad e referen ce to “EPP sp ecification version 1.9” cau sin g con fu sion abou t th e EPP stan d ard . Note th at “EPP version 1.9” d oes n ot exist, an d an y EPP sp ecification after th e origin al version 1.7 is tech n ically a p art of th e IEEE 1284 sp ecification . Un fortu n ately, th is h as resu lted in two som ewh at in com p atible stan d ard s for EPP p arallel p orts: th e origin al EPP Stan d ard s Com m ittee version 1.7 stan d ard , an d th e IEEE 1284 Com m ittee stan d ard . Th e two stan d ard s are su fficien tly sim ilar th at n ew p erip h erals m ay

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be d esign ed in su ch a way as to su p p ort both stan d ard s, bu t existin g EPP 1.7 p erip h erals m ay n ot op erate with EPP 1284 p orts. EPP p orts were m ore com m on with IBM m ach in es th an oth er h ard ware m an u factu rers wh o seem ed to stay away from th e p rin ter p ort issu e u n til th e En h an ced Cap abilities Port (ECP) was in trod u ced by Microsoft an d Hewlett-Packard (HP). However, becau se th e EPP p ort is d efin ed in th e IEEE 1284 stan d ard , it h as gain ed software an d d river su p p ort, in clu d in g su p p ort in W in d ows NT. Enhanced Capabilit ies Port ( ECP) . An oth er typ e of h igh -sp eed p arallel p ort called th e ECP (Enhanced Capabilities Port) was join tly d evelop ed by Microsoft an d Hewlett-Packard , an d form ally an n ou n ced in 1992. Like EPP, ECP offers im p roved p erform an ce for th e p arallel p ort an d req u ires sp ecial h ard ware logic. Sin ce th e origin al an n ou n cem en t, ECP is in clu d ed in IEEE 1284 ju st like EPP. Un like EPP, ECP is n ot tailored to su p p ort p ortable PCs’ p arallel p ort p erip h erals; its p u rp ose is to su p p ort an in exp en sive attach m en t to a very h igh -p erform an ce p rin ter. Fu rth er, ECP m od e req u ires th e u se of a DMA ch an n el, wh ich EPP d id n ot d efin e, an d wh ich can cau se trou blesom e con flicts with oth er d evices th at u se DMA. Most PCs with n ewer “su p er I/ O” ch ip s will be able to su p p ort eith er EPP or ECP m od e. Most n ew system s are bein g d elivered with ECP p orts th at su p p ort h igh th rou gh p u t com m u n ication s. In m ost cases, th e ECP p orts can be tu rn ed in to EPP, or stan d ard u n id irection al p arallel p orts via BIOS. However, it’s recom m en d ed th at th e p ort be p laced in ECP m od e for th e best th rou gh p u t. IEEE 1284. Th e IEEE 1284 stan d ard called “Stan d ard Sign alin g Meth od for a Bid irection al Parallel Perip h eral In terface for Person al Com p u ters” was ap p roved for fin al release in March 1994. Th is stan d ard d efin es th e p h ysical ch aracteristics of th e p arallel p ort, in clu d in g d ata tran sfer m od es an d p h ysical an d electrical sp ecification s. IEEE 1284 d efin es th e electrical sign alin g beh avior extern al to th e PC for a m u ltim od al p arallel p ort th at m ay su p p ort 4-bit an d m od es of op eration . Not all m od es are req u ired by th e 1284 sp ecification , an d th e stan d ard m akes som e p rovision for ad d ition al m od es. Th e IEEE 1284 sp ecification is targeted at stan d ard izin g th e beh avior between a PC an d an attach ed d evice, m ost sp ecifically attach ed p rin ters. Alth ou gh , th e sp ecification is of in terest to ven d ors of p arallel p ort p erip h erals (d isks, LAN ad ap ters, an d so on ). IEEE 1284 is a h ard ware an d lin e con trol-on ly stan d ard an d d oes n ot d efin e h ow software sh ou ld talk to th e p ort. An offsh oot of th e origin al 1284 stan d ard h as been created to d efin e th e software in terface. Th e IEEE 1284.3 com m ittee was form ed to d evelop a stan d ard for software u sed with IEEE 1284-com p lian t h ard ware. Th is stan d ard , d esign ed to ad d ress th e d isp arity am on g p rovid ers of p arallel p ort ch ip s, con tain s a sp ecification for su p p ortin g EPP m od e via th e PC’s system BIOS. IEEE 1284 allows for m u ch h igh er th rou gh p u t in a con n ection between a com p u ter an d a p rin ter, or two com p u ters. Th e resu lt is th at th e p rin ter cable is n o lon ger th e stan d ard p rin ter cable. Th e IEEE 1284 p rin ter cable u ses twisted -p air tech n ology, th e sam e tech n ology th at allows Category 5 cablin g to carry sp eed s u p to 100Mbp s.

Serial and Parallel Ports

IEEE 1284 also d efin ed a n ew p ort—a fact th at m ost p eop le aren ’t fam iliar with . A typ e A con n ector in th e IEEE 1284 stan d ard is d efin ed as a DB25 p in con n ector. A typ e B con n ector is d efin ed as a Cen tron ics 36 con n ector. Th e n ew con n ector, referred to as typ e C is a h igh -d en sity con n ector th at is alread y begin n in g to be in stalled in HP’s p rin ter lin e. Th e th ree con n ectors are sh own in Figu re 10.3. 0.840

370

2.716

2.089

Type A

1.713

1284 Type B

1284 Type C

FIG. 10.3 Th e th ree d ifferen t IEEE 1284 con n ectors. Upgrading t o EPP/ ECP Port s. If you are p u rch asin g a system tod ay, I wou ld recom m en d on e th at h as a so-called “Su p er I/ O” ch ip th at su p p orts both EPP an d ECP op eration . If you wan t to test th e p arallel p orts in a system , esp ecially to d eterm in e wh at typ e th ey are, I h igh ly recom m en d a u tility called Parallel. Th is is a h an d y p arallel p ort in form ation u tility th at exam in es you r system ’s p arallel p orts an d rep orts th e Port Typ e, IO ad d ress, IRQ level, BIOS n am e, an d an assortm en t of in form ative n otes an d warn in gs in a com p act an d easy-to-read d isp lay. Th e ou tp u t m ay be red irected to a file for tech su p p ort p u rp oses. Parallel u ses very sop h isticated tech n iq u es for p ort an d IRQ d etection , an d is aware of a broad ran ge of q u irky p ort featu res. You can get it from Parallel Tech n ologies (see Ap p en d ix A). If you h ave an old er system th at d oes n ot in clu d e an EPP/ ECP p ort an d you wou ld like to u p grad e, th ere are several com p an ies n ow offerin g board s with th e correct Su p er I/ O ch ip s th at im p lem en t th ese featu res. I recom m en d you ch eck with Farp oin t Com m u n ication s, Byteru n n er Tech n ologies, or Lava Com p u ter Mfg.; th ey are listed in th e ven d or list in Ap p en d ix A.

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Parallel-Port Configurat ion Parallel-p ort con figu ration is n ot as com p licated as it is for serial p orts. Even th e origin al IBM PC h as BIOS su p p ort for th ree LPT p orts, an d DOS h as always h ad th is su p p ort as well. Table 10.7 sh ows th e stan d ard I/ O ad d ress an d in terru p t settin gs for p arallel p ort u se. Table 10.7 Syst em

Parallel Int erface I/ O Port Addresses and Int errupt s LPTx St d.

Alt

I/ O Port

IRQ

8/ 16-bit ISA

LPT1

—

3BCh

IRQ7

8/ 16-bit ISA

LPT1

LPT2

378h

IRQ5

8/ 16-bit ISA

LPT2

LPT3

278h

None

Becau se th e BIOS an d DOS always h ave p rovid ed th ree d efin ition s for p arallel p orts, p roblem s with old er system s are in freq u en t. Problem s can arise, h owever, from th e lack of available in terru p t-d riven p orts for ISA bu s system s. Norm ally, an in terru p t-d riven p ort is n ot absolu tely req u ired for p rin tin g op eration s; in fact, m an y p rogram s d o n ot u se th e in terru p t-d riven cap ability. Man y p rogram s d o u se th e in terru p t, h owever, su ch as n etwork p rin t p rogram s an d oth er typ es of backgrou n d or sp ooler-typ e p rin ter p rogram s. Also, h igh -sp eed , laser-p rin ter u tility p rogram s often u se th e in terru p t cap abilities to allow for p rin tin g. If you u se th ese typ es of ap p lication s on a p ort th at is n ot in terru p t d riven , you see th e p rin tin g slow to a crawl, if it works at all. Th e on ly solu tion is to u se an in terru p t-d riven p ort. MS-DOS an d W in d ows 95/ 98 n ow su p p ort u p to 128 p arallel p orts. To con figu re p arallel p orts in ISA bu s system s, you p robably will h ave to set ju m p ers an d switch es. Becau se each board on th e m arket is d ifferen t, you always sh ou ld con su lt th e OEM m an u al for th at p articu lar card if you n eed to kn ow h ow th e card sh ou ld be con figu red . Linking Syst em s w it h Parallel Port s. Th e origin al IBM PC d esign ers en vision ed th at th e p arallel p ort wou ld be u sed on ly for com m u n icatin g with a p rin ter. Over th e years, th e n u m ber of d evices th at can be u sed with a p arallel p ort h as in creased trem en d ou sly. You n ow can fin d everyth in g from tap e backu p u n its to LAN ad ap ters to CD-ROMs th at con n ect th rou gh you r p arallel p ort. Som e m od em m an u factu rers n ow h ave m od em s th at con n ect to th e p arallel p ort in stead of th e serial p ort for faster d ata tran sfer. Perh ap s on e of th e m ost com m on u ses for bid irection al p arallel p orts is to tran sfer d ata between you r system an d an oth er, su ch as a lap top com p u ter. If both system s u se an EPP/ ECP p ort, you can actu ally com m u n icate at rates of u p to 2M/ sec, wh ich rivals th e sp eed of som e h ard d isk d rives. Th is cap ability h as led to an in crease in software to serve th is n ich e of th e m arket. If you are in terested in su ch software (an d th e p arallel p orts n ecessary to facilitate th e software), you sh ou ld refer to th e reviews th at p eriod ically ap p ear in sou rces su ch as PC Magazine.

Serial and Parallel Ports

Con n ectin g two com p u ters with stan d ard u n id irection al p arallel p orts req u ires a sp ecial cable, kn own as a n u ll m od em cable. Most p rogram s sell or p rovid e th ese cables with th eir software. However, if you n eed to m ake on e for you rself, Table 10.8 p rovid es th e wirin g d iagram you n eed . Table 10.8

Null M odem / Lap Link Cable W iring

25-pin

Signal Descript ions

pin 2

Data Bit 0

pin 3

Data Bit 1

pin 4

Data Bit 2

pin 5

Data Bit 3

pin 6

Data Bit 4

pin 15

–Error

pin 13

Select

pin 12

Paper End

pin 10

–Acknowledge

pin 11

Busy

pin 25

Ground

↔ ↔ ↔ ↔ ↔ ↔ ↔ ↔ ↔ ↔ ↔

Signal Descript ions

25-pin

–Error

pin 15

Select

pin 13

Paper End

pin 12

–Acknowledge

pin 10

Busy

pin 11

Data Bit 0

pin 2

Data Bit 1

pin 3

Data Bit 2

pin 4

Data Bit 3

pin 5

Data Bit 4

pin 6

Ground

pin 25

Tip Even though cables are most often provided for data transfer programs, notebook users may want to look for an adapter that makes the appropriate changes to a standard parallel cable. This can make traveling lighter by preventing the need for additional cables. M ost of the time, these adapters attach to the Centronics end of the cable, and provide a standard DB25 connection on the other end. They’re sold under a variety of names; however, null modem cable, Laplink adapter, or Laplink converter are the most common.

Alth ou gh th e wirin g con figu ration an d p rem ad e in terlin k cables given in Table 10.8 will work for con n ectin g two m ach in es with ECP/ EPP p orts, th ey won ’t be able to take ad van tage of th e ad van ced tran sfer rates of th ese p orts. Sp ecial cables are n eed ed to com m u n icate between ECP/ EPP p orts. Parallel Tech n ologies is a com p an y th at sells ECP/ EPP cables for con n ectin g to oth er ECP/ EPP com p u ters, an d also sells a u n iversal cable for con n ectin g an y two p arallel p orts togeth er to u se th e h igh est sp eed . Con n ect Air is listed in Ap p en d ix A. W in d ows 95 an d n ewer version s in clu d e a sp ecial p rogram called DCC (Direct Cable Con n ection ), wh ich allows two system s to be n etworked togeth er via a n u ll m od em / Lap Lin k cable. Con su lt th e W in d ows d ocu m en tation for in form ation on h ow to establish a DCC con n ection . A com p an y called Parallel Tech n ologies (see Ap p en d ix A) h as been con tracted by Microsoft to su p p ly th e sp ecial DCC cables u sed to con n ect th e system s. Th ey h ave on e sp ecial typ e of cable th at u ses active electron ics to en su re a reliable h igh -sp eed in tercon n ection .

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Test ing Parallel Port s Testin g p arallel p orts is, in m ost cases, sim p ler th an testin g serial p orts. Th e p roced u res you u se are effectively th e sam e as th ose u sed for serial p orts, excep t th at wh en you u se th e d iagn ostics software, you ch oose th e obviou s ch oices for p arallel p orts rath er th an serial p orts. Not on ly are th e software tests sim ilar, bu t th e h ard ware tests req u ire th e p rop er p lu gs for th e loop back tests on th e p arallel p ort. Several d ifferen t loop back p lu gs are req u ired d ep en d in g on wh at software you are u sin g to test. Most u se th e IBM style loop back, bu t som e u se th e style origin ated in th e Norton Utilities d iagn ostics. Th e wirin g n eed ed to con stru ct you r own loop back or wrap p lu gs is as follows: ■ IBM 25-Pin Parallel (Male DB25P) Loop back Con n ector (W rap Plu g). Con n ect th ese p in s: 1 to 13 2 to 15 10 to 16 11 to 17 ■ Norton Utilities 25-Pin Parallel (Male DB25P) Loop back Con n ector (W rap Plu g). Con n ect th ese p in s: 2 3 4 5 6

to to to to to

15 13 12 10 11

Serial and Parallel Port Replacem ent s Two n ew h igh -sp eed serial-bu s arch itectu res for d esktop an d p ortable are becom in g available, called th e Universal Serial Bus (USB) an d FireW ire or IEEE 1394. Th ese are h igh -sp eed com m u n ication s p orts th at far ou tstrip th e cap abilities of th e stan d ard serial an d p arallel p orts m ost system s con tain tod ay, an d m ay be u sed as an altern ative to SCSI for h igh sp eed p erip h eral con n ection s. In ad d ition to p erform an ce, th ese n ew p orts will offer I/ O d evice con solid ation , m ean in g all typ es of extern al p erip h erals will con n ect to th ese p orts. Th e recen t tren d in h igh -p erform an ce p erip h eral bu s d esign is to u se a serial arch itectu re, wh ere on e bit is sen t at a tim e d own a wire. Parallel arch itectu re u ses 8, 16, or m ore wires to sen d bits sim u ltan eou sly. At th e sam e clock sp eed , th e p arallel bu s is faster; h owever, it is m u ch easier to in crease th e clock sp eed of a serial con n ection th an a p arallel on e. Parallel con n ection s su ffer from several p roblem s, th e biggest bein g sign al skew an d jitter. Skew an d jitter are th e reason s th at h igh -sp eed p arallel bu ses like SCSI are lim ited

Serial and Parallel Port Replacements

to sh ort d istan ces of 3 m eters or less. Th e p roblem is th at alth ou gh th e 8 or 16 bits of d ata are fired from th e tran sm itter at th e sam e tim e, by th e tim e th ey reach th e receiver, p rop agation d elays h ave con sp ired to allow som e bits to arrive before th e oth ers. Th e lon ger th e cable, th e lon ger th e tim e between th e arrival of th e first an d last bits at th e oth er en d ! Th is signal skew, as it is called , eith er p reven ts you from ru n n in g a h igh -sp eed tran sfer rate, a lon ger cable, or both . Jitter is th e ten d en cy for th e sign al to reach its target voltage an d float above an d below for a sh ort p eriod of tim e. W ith a serial bu s, th e d ata is sen t on e bit at a tim e. Becau se th ere is n o worry abou t wh en each bit will arrive, th e clockin g rate can be in creased d ram atically. W ith a h igh clock rate, p arallel sign als ten d to in terfere with each oth er. Serial again h as an ad van tage in th at with on ly on e or two sign al wires, crosstalk an d in terferen ce between th e wires in th e cable are n egligible. Parallel cables are very exp en sive. In ad d ition to th e m an y ad d ition al wires n eed ed to carry th e m u ltip le bits in p arallel, th e cable also n eed s to be sp ecially con stru cted to p reven t crosstalk an d in terferen ce between ad jacen t d ata lin es. Th is is on e reason extern al SCSI cables are so exp en sive. Serial cables, on th e oth er h an d , are very in exp en sive. For on e th in g, th ey h ave very few wires, p lu s th e sh ield in g req u irem en ts are far sim p ler, even at very h igh sp eed s. Becau se of th is, it is also easier to tran sm it serial d ata reliably over lon ger d istan ces, wh ich is wh y p arallel in terfaces h ave sh orter recom m en d ed cable len gth s th an serial in terfaces. If you go by sp ecification s, serial cables sh ou ld be n o lon ger th an 50 feet wh ile p arallel cables sh ou ld be n o lon ger th an 10 feet. It is for th ese reason s, p lu s th e n eed for n ew Plu g-an d -Play extern al p erip h eral in terfaces, an d th e elim in ation of th e p h ysical p ort crowd in g on p ortable com p u ters, th at th ese n ew h igh -p erform an ce serial bu ses h ave been d evelop ed . Both USB an d 1394 are available on d esktop an d p ortable PCs tod ay. USB ( Universal Serial Bus) USB is p erip h eral bu s stan d ard d evelop ed by PC an d telecom in d u stry lead ers in clu d in g Com p aq , DEC, IBM, In tel, Microsoft, NEC, an d North ern Telecom , th at will brin g Plu g an d Play of com p u ter p erip h erals ou tsid e of th e PC. USB will elim in ate th e n eed to in stall card s in to d ed icated com p u ter slots an d recon figu re th e system , savin g on im p ortan t system resou rces su ch as In terru p ts (IRQs). Person al com p u ters eq u ip p ed with USB will allow com p u ter p erip h erals to be au tom atically con figu red as soon as th ey are p h ysically attach ed , with ou t th e n eed to reboot or ru n setu p . USB will also allow u p to 127 d evices to ru n sim u ltan eou sly on a com p u ter, with p erip h erals su ch as m on itors an d keyboard s actin g as ad d ition al p lu g-in sites, or h u bs. In tel h as been th e p rim ary p rop on en t of USB, an d all th eir n ew PC ch ip sets, startin g with th e PIIX3 Sou th Brid ge com p on en t u sed with th e 430HX Triton II, will in clu d e USB su p p ort as stan d ard . Six oth er com p an ies h ave worked with In tel in co-d evelop in g th e USB, in clu d in g Com p aq , Digital, IBM, Microsoft, NEC, an d North ern Telecom . Togeth er, th ese com p an ies h ave establish ed th e USB Im p lem en ters Foru m to d evelop , su p p ort, an d p rom ote th e USB arch itectu re.

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√√ See “ Chipsets,” p. 183

Th e USB is a 12Mbit/ sec (1.5M/ sec) in terface over a sim p le 4-wire con n ection . Th e bu s su p p orts u p to 127 d evices an d u ses a tiered star top ology bu ilt on exp an sion h u bs th at can resid e in th e PC, an y USB p erip h eral, or even stan d alon e h u b boxes. A sam p le USB con figu ration is sh own in Figu re 10.4. For low-p erform an ce p erip h erals su ch as p oin tin g d evices an d keyboard s, th e USB also h as a slower 1.5Mbit/ sec su bch an n el. Th e su bch an n el con n ection is u sed for slower in terface d evices su ch as keyboard s an d m ice. Maxim u m cable len gth between two fu ll-sp eed (12Mbit/ sec) d evices or a d evice an d a h u b is five m eters u sin g twisted p air sh ield ed cable with 20 gau ge wire. Maxim u m cable len gth for low sp eed (1.5Mbit/ sec) d evices u sin g n on twisted p air wire is th ree m eters. Th ese d istan ce lim its are sh orter if sm aller-gau ge wire is u sed , accord in g to Table 10.9: Table 10.9

M axim um Cable Lengt hs Versus W ire Gauge

Gauge

Resist ance ( in Ohm s/ m et er Ω/ m )

Lengt h ( M ax.)

28

0.232 Ω/ m

0.81m

26

0.145 Ω/ m

1.31m

24

0.091 Ω/ m

2.08m

22

0.057 Ω/ m

3.33m

20

0.036 Ω/ m

5.00m

Alth ou gh USB is n ot as fast at d ata tran sfer as FireW ire or SCSI, it is still m ore th an ad eq u ate for th e typ es of p erip h erals for wh ich it is d esign ed . Spkr

Spkr

Printer/Hub

Mic

Tablet Keyboard/Hub Telcom

FIG. 10.4 A PC can u se m u ltip le USB h u bs to su p p ort a variety of d ifferen t p erip h erals con n ected to wh ich ever h u b is m ost con ven ien t.

Th e p h ysical USB p lu g is sm all an d , u n like a typ ical serial or p arallel cable, th e p lu g is n ot attach ed by screws or th u m bscrews. Th e USB p lu g (sh own in Figu re 10.5) sn ap s in to

Serial and Parallel Port Replacements

p lace on th e USB con n ector on th e PC. Table 10.10 sh ows th e p in ou t for th e USB 4-wire con n ector an d cable.

FIG. 10.5 Th e slots on th e USB p lu g sn ap it in to p lace on th e sp rin g-load ed tabs in a USB con n ector.

Table 10.10

USB Connect or Pinout

Pin

Signal Nam e

Com m ent

1

VCC

Cable power

2

– Data

3

+ Data

4

Ground

Cable ground

USB con form s to In tel’s Plu g an d Play (Pn P) sp ecification , in clu d in g hot plugging, wh ich m ean s th at d evices can be p lu gged in d yn am ically with ou t p owerin g d own or rebootin g th e system . Sim p ly p lu g in th e d evice, an d th e USB con troller in th e PC will d etect th e d evice an d au tom atically d eterm in e an d allocate th e resou rces an d d rivers req u ired . Microsoft h as USB d rivers d evelop ed an d h as in clu d ed th em in existin g version s of W in d ows 95 an d NT. Note th at th e W in d ows 95b release or later is req u ired for USB su p p ort; th e n ecessary d rivers are n ot p resen t in th e origin al W in d ows 95 or 95a. USB su p p ort will also be req u ired in th e BIOS, wh ich will be in clu d ed in n ewer system s with USB p orts bu ilt in . Afterm arket board s are also available for ad d in g USB to system s th at d on ’t in clu d e it as stan d ard on th e m oth erboard . USB p erip h erals will in clu d e m od em s, telep h on es, joysticks, keyboard s, an d p oin tin g d evices su ch as m ice an d trackballs. On e in terestin g featu re of USB is th at all attach ed d evices will be p owered by th e USB bu s. Th e Pn P asp ects of USB allow th e system to q u ery th e attach ed p erip h erals as to th eir p ower req u irem en ts an d issu e a warn in g if available p ower levels are bein g exceed ed . Th is will be im p ortan t for USB wh en u sed in p ortable system s, becau se battery p ower to ru n th e extern al p erip h erals m ay be lim ited . An oth er ben efit of th e USB sp ecification is self-id en tifyin g p erip h erals, a featu re th at sh ou ld greatly ease in stallation s. Th is m ean s th at you d on ’t h ave to set u n iq u e IDs or id en tifiers for each p erip h eral, th e USB h an d les th at au tom atically. Also, USB d evices can be “h ot” p lu gged or u n p lu gged , m ean in g th at you will n ot h ave to tu rn off you r com p u ter or reboot every tim e you wan t to con n ect or d iscon n ect a p erip h eral. As of th is writin g, USB-com p atible d evices are still h ard to fin d , alth ou gh m ost n ewer m oth erboard s are bein g m ad e to su p p ort th em . On e th in g to keep in m in d before

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p u rch asin g USB p erip h erals is th at you r op eratin g system m u st offer USB su p p ort. W h ereas th e origin al W in d ows 95 u p grad e an d W in d ows NT 4.0 d o n ot su p p ort USB, th e later OSR-2 (OEM Service Release 2) release of W in d ows 95 (also called 95B) d oes. W in d ows 98 an d W in d ows NT 5.0 h ave fu ll su p p ort for USB. Becau se th e USB stan d ard sh ows p rom ise, it sh ou ld becom e an im p ortan t bu s tech n ology in th e years to com e. On e of th e biggest ad van tages to an in terface su ch as USB is th at USB on ly req u ires a sin gle in terru p t from th e PC. Th is m ean s th at you can con n ect u p to 127 d evices an d th ey will n ot u se sep arate in terru p ts as th ey m igh t if each were con n ected over a sep arate in terface. W ith m od ern PCs su fferin g from an in terru p t sh ortage, th is is a m ajor ben efit, an d sh ou ld sp u r th e ad op tion of th is in terface for lower-sp eed p erip h erals. FireW ire ( IEEE 1394) FireW ire is a relatively n ew bu s tech n ology; it is th e resu lt of th e large d ata-m ovin g d em an d s of tod ay’s au d io an d vid eo m u ltim ed ia d evices. It is extrem ely fast, with d ata tran sfer rates u p to an in cred ible 400M/ sec, an d even faster sp eed s are bein g d evelop ed . Th e IEEE-1394 (as it is officially kn own ) sp ecification was p u blish ed by th e IEEE Stan d ard s Board in late 1995. Th e IEEE-1394 stan d ard cu rren tly exists with th ree d ifferen t sign alin g rates: 100-, 200-, an d 400Mbits/ sec (12.5-, 25-, 50MBytes/ sec), with gigabit-p er-secon d version s in th e works! Most PC ad ap ter card s su p p ort th e 200M/ sec rate, even th ou gh cu rren t d evices gen erally on ly op erate at 100M/ sec. A m axim u m of 63 d evices can be con n ected to a sin gle IEEE-1394 ad ap ter card by d aisy ch ain in g. Cables for IEEE-1394 d evices u se Nin ten d o Gam eBoy-d erived con n ectors an d con sist of six con d u ctors; fou r wires are u sed for d ata tran sm ission , an d two con d u ct p ower. Con n ection with th e m oth erboard is m ad e eith er by a d ed icated IEEE-1394 in terface or by a PCI ad ap ter card . Th is bu s was d erived from th e FireW ire bu s origin ally d evelop ed by Ap p le an d Texas In stru m en ts, an d is also a p art of th e n ew Serial SCSI stan d ard th at is d iscu ssed later in th is ch ap ter in th e section titled “SCSI-3.” 1394 u ses a sim p le six-wire cable with two d ifferen tial p airs of clock an d d ata lin es p lu s two p ower lin es. Ju st as with USB, 1394 is fu lly Pn P, in clu d in g th e cap ability for h ot p lu ggin g (in sertion an d rem oval of com p on en ts with ou t p owerin g d own ). Un like th e m u ch m ore com p licated p arallel SCSI bu s, 1394 d oes n ot req u ire com p licated term in ation , an d d evices con n ected to th e bu s can d raw u p to 1.5 am p s of electrical p ower. 1394 offers eq u al or greater p erform an ce com p ared to Ultra-W id e SCSI, with a m u ch less exp en sive an d less com p licated con n ection . 1394 is bu ilt on a d aisy-ch ain ed an d bran ch ed top ology an d allows u p to 63 n od es with a ch ain of u p to 16 d evices on each n od e. If th is is n ot en ou gh , th e stan d ard also calls for u p to 1,023 brid ged bu ses, wh ich can in tercon n ect m ore th an 64,000 n od es! Ad d ition ally, 1394 can su p p ort d evices with d ifferen t d ata rates on th e sam e bu s, ju st as with SCSI. Th e typ es of d evices th at will be con n ected to th e PC via 1394 in clu d e p ractically an yth in g th at m igh t u se SCSI tod ay. Th is in clu d es all form s of d isk d rives, in clu d in g h ard

Storage Device Interfaces

d isk, op tical, flop p y, CD-ROM, an d th e n ew DVD (Digital Vid eo Disc) d rives. Also, d igital cam eras, tap e d rives, an d m an y oth er h igh -sp eed p erip h erals featu rin g 1394 h ave in terfaces bu ilt in . Exp ect th e 1394 bu s to be im p lem en ted in both d esktop an d p ortable com p u ters as a rep lacem en t for oth er extern al h igh -sp eed bu ses like SCSI. Ch ip sets an d PCI ad ap ters for th e 1394 bu s are alread y available. Microsoft h as d evelop ed d rivers to su p p ort 1394 in W in d ows 95/ 98 an d W in d ows NT. As of th is writin g, d evices th at con form to th e IEEE-1394 stan d ard are lim ited p rim arily to cam cord ers an d VCRs with d igital vid eo (DV) cap ability. Son y was am on g th e first to release su ch d evices, alth ou gh its p rod u cts h ave a u n iq u e fou r-wire con n ector th at req u ires an ad ap ter cord to be u sed with IEEE-1394 PC card s. DV p rod u cts are also available from Pan ason ic an d Matsu sh ita, an d fu tu re IEEE-1394 ap p lication s sh ou ld in clu d e DV con feren cin g d evices, satellite au d io an d vid eo d ata stream s, au d io syn th esizers, DVD, an d oth er h igh -sp eed d isc d rives. Becau se of th e cu rren t DV em p h asis for IEEE-1394 p erip h erals, m ost PC card s cu rren tly offered by Ad ap tec, FAST Mu ltim ed ia, Matrox, an d oth ers in volve DV cap tu rin g an d ed itin g. If you ’re willin g to sp en d $1,000 or m ore on DV eq u ip m en t, th ese item s sh ou ld p rovid e su bstan tial vid eo ed itin g an d d u bbin g cap abilities on you r PC. Of cou rse, you will n eed IEEE-1394 I/ O con n ectivity, wh ich is still a rarity on cu rren t m oth erboard s. Fortu n ately, Ad ap tec an d Texas In stru m en ts both offer PCI ad ap ter card s th at su p p ort IEEE-1394. IEEE-1394 stan d s to offer u n p reced en ted m u ltim ed ia cap abilities to cu rren t an d fu tu re PC u sers. Cu rren t p erip h erals—p articu larly DV d evices—are exp en sive, bu t as with an y em ergin g tech n ology, p rices sh ou ld com e d own in th e fu tu re, op en in g th e d oor wid e for n ew PC u ses both in th e h om e an d office. A great n u m ber of p eop le wou ld gain th e ability to d o ad van ced au d io an d vid eo ed itin g. If you an ticip ate h avin g m u ltim ed ia n eed s on you r PC in th e fu tu re, IEEE-1394 con n ectivity is a m u st.

St orage Device Int erfaces Th e rem ain d er of th is ch ap ter d escribes in terfaces u sed com m on ly by storage d evices— m ain ly d isk d rives. It covers th e d isk in terface from th e d rives to th e cables an d con trollers th at ru n th em . You learn abou t th e variou s d isk in terfaces you can select, an d th e sh ortcom in gs an d stren gth s of each typ e. As th ese in terfaces h ave evolved , th ey are n ow m u ch m ore versatile. Th e IDE in terface, wh ich is th e m ost wid ely u sed storage d evice in terface in m od ern system s, h as evolved from a h ard d isk on ly in terface to on e th at su p p orts h ard d isks an d m an y d ifferen t typ es of rem ovable m ed ia su ch as tap e, CD-ROM, CD-RW , Zip , an d oth ers. Th e SCSI in terface h as always been m u ch m ore th an a d rive in terface an d is even m ore versatile th an IDE, allowin g n on storage d evices su ch as scan n ers to be attach ed . A variety of h ard d isk in terfaces are available tod ay. As tim e h as p assed , th e n u m ber of ch oices h as in creased , an d m an y of th e old er d esign s are n o lon ger viable in n ewer system s. You n eed to kn ow abou t all th ese in terfaces, from th e old est to th e n ewest d esign s, becau se you will en cou n ter all of th em wh en ever u p grad in g or rep airin g system s is n ecessary.

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Th e in terfaces h ave d ifferen t cablin g an d con figu ration op tion s, an d th e setu p an d form at of d rives will vary as well. Sp ecial p roblem s m ay arise wh en you are tryin g to in stall m ore th an on e d rive of a p articu lar in terface typ e or (esp ecially) wh en you are m ixin g d rives of d ifferen t in terface typ es in on e system . Th is section covers th e d ifferen t h ard d isk d rive in terfaces, givin g you all th e tech n ical in form ation you n eed to d eal with th em in an y way—trou blesh ootin g, servicin g, u p grad in g, an d even m ixin g th e d ifferen t typ es. Th is section also exam in es th e stan d ard con trollers an d d escribes h ow you can work with th ese con trollers, an d rep lace th em with m u ch faster u n its. Also d iscu ssed are th e d ifferen t typ es of d rive in terfaces: ST-506/ 412, ESDI, IDE, an d SCSI. Ch oosin g th e p rop er in terface is im p ortan t, becau se you r ch oice also affects you r d isk d rive p u rch ase an d th e u ltim ate sp eed of th e d isk su bsystem . Th e p rim ary job of th e h ard d isk con troller or in terface is to tran sm it an d receive d ata to an d from th e d rive. Th e d ifferen t in terface typ es lim it h ow fast d ata can be m oved from th e d rive to th e system an d offer d ifferen t levels of p erform an ce. If you are p u ttin g togeth er a system in wh ich p erform an ce is a p rim ary con cern , you n eed to kn ow h ow th ese d ifferen t in terfaces affect p erform an ce an d wh at you can exp ect from th em . Man y of th e statistics th at ap p ear in tech n ical literatu re are n ot in d icative of th e real p erform an ce figu res you will see in p ractice. I will sep arate th e m yth s p resen ted by som e of th ese overly op tim istic figu res from th e reality of wh at you will actu ally see. W ith regard to d isk d rives, an d esp ecially h ard d isk d rives, th e sp ecification on wh ich p eop le seem to focu s th e m ost is th e d rive’s rep orted average seek tim e, th e (average) tim e it takes for th e h ead s to be p osition ed from on e track to an oth er. Un fortu n ately, th e im p ortan ce of th is sp ecification often is overstated , esp ecially in relation to oth er sp ecification s, su ch as th e d ata tran sfer rate. Th e tran sfer rate of d ata between th e d rive an d th e system is m ore im p ortan t th an access tim e, becau se m ost d rives sp en d m ore tim e read in g an d writin g in form ation th an th ey d o sim p ly m ovin g th e h ead s arou n d . Th e sp eed at wh ich a p rogram or d ata file is load ed or read is affected m ost by th e d ata tran sfer rate. Sp ecialized op eration s su ch as sortin g large files, wh ich in volves a lot of ran d om access to in d ivid u al record s of th e file (an d , th erefore, m an y seek op eration s), are h elp ed greatly by a faster-seekin g d isk d rive. Seekin g p erform an ce is im p ortan t in th ese cases. Most n orm al file load an d save op eration s, h owever, are affected m ost by th e rate at wh ich d ata can be read an d written to an d from th e d rive. Th e d ata tran sfer rate d ep en d s on both th e d rive an d th e in terface. Several typ es of h ard d isk in terfaces h ave been u sed in PC system s over th e years, as sh own in th e followin g table. Int erface

W hen Used:

ST-506/ 412

1978–1985

ESDI

1986–1989

SCSI

1986–Present

IDE

1988–Present

Storage Device Interfaces

As you can see, on ly IDE an d SCSI rem ain p op u lar tod ay. Of th ese in terfaces, on ly ST-506/ 412 an d ESDI are wh at you cou ld call tru e d isk-con troller-to-d rive in terfaces. SCSI an d IDE are system -level in terfaces th at u su ally in corp orate a ch ip set-based variation of on e of th e oth er two typ es of d isk con troller in terfaces in tern ally. For exam p le, m ost SCSI an d IDE d rives in corp orate th e sam e basic con troller circu itry u sed in sep arate ESDI con trollers. Th e SCSI in terface ad d s an oth er layer of in terface th at attach es th e con troller to th e system bu s, wh ereas IDE is a d irect bu s-attach m en t in terface. Even so, virtu ally all m od ern d isk d rives u se eith er IDE or SCSI in terfaces to con n ect to a system . In d ata recovery, it h elp s to kn ow th e d isk in terface you are workin g with , becau se m an y d ata-recovery p roblem s in volve d rive setu p an d in stallation p roblem s. Each in terface req u ires a sligh tly d ifferen t m eth od of in stallation an d d rive con figu ration . If th e in stallation or con figu ration is in correct or accid en tally altered by th e system u ser, it m ay p reven t access to d ata on a d rive. Accord in gly, an yon e wh o wan ts to becom e p roficien t in d ata recovery m u st be an exp ert on in stallin g an d con figu rin g variou s typ es of h ard d isks an d con trollers. IBM’s relian ce on in d u stry-stan d ard in terfaces su ch as th ose listed h ere was a boon for everybod y in th e IBM-com p atible in d u stry. Th ese stan d ard s allow a great d eal of crosssystem an d cross-m an u factu rer com p atibility. Th e u se of th ese in d u stry-stan d ard in terfaces allows you to p ick u p a m ail-ord er catalog, p u rch ase a h ard d isk for th e lowest p ossible p rice, an d be assu red th at it will work with you r system . Th is Plu g-an d -Play cap ability resu lts in afford able h ard d isk storage an d a variety of op tion s in cap acities an d sp eed . The ST-506/ 412 Int erface Th e ST-506/ 412 in terface was d evelop ed by Seagate Tech n ologies arou n d 1980. Th e in terface origin ally ap p eared in th e Seagate ST-506 d rive, wh ich was a 5M form atted (or 6M u n form atted ) d rive in a fu ll-h eigh t, 5 1/ 4-in ch form factor. By tod ay’s stan d ard s, th is d rive is a tan k! In 1981, Seagate in trod u ced th e ST-412 d rive, wh ich ad d ed a featu re called buffered seek to th e in terface. Th is d rive was a 10M form atted (12M u n form atted ) d rive th at also q u alifies as a tan k by tod ay’s stan d ard s. Besid es th e Seagate ST-412, IBM also u sed th e Min iscribe 1012 as well as th e In tern ation al Mem ories, In c. (IMI) m od el 5012 d rive in th e XT. IMI an d Min iscribe are lon g gon e, bu t Seagate rem ain s as on e of th e largest d rive m an u factu rers. Sin ce th e origin al XT, Seagate h as su p p lied d rives for n u m erou s system s m ad e by m an y d ifferen t m an u factu rers. Most d rive m an u factu rers th at m ad e h ard d isks for PC system s ad op ted th e Seagate ST-506/ 412 stan d ard , a situ ation th at h elp ed m ake th is in terface p op u lar. On e im p ortan t featu re is th e in terface’s Plu g-an d -Play d esign . No cu stom cables or sp ecial m od ification s are n eed ed for th e d rives, wh ich m ean s th at virtu ally an y ST-506/ 412 d rive will work with an y ST-506/ 412 con troller. Th e on ly real com p atibility issu e with th is in terface is th e level of BIOS su p p ort p rovid ed by th e system . W h en in trod u ced to th e PC in d u stry by IBM in 1983, ROM BIOS su p p ort for th is h ard d isk in terface was p rovid ed by a BIOS ch ip on th e con troller. Con trary to wh at m ost believed , th e PC an d XT m oth erboard BIOS h ad n o in h eren t h ard d isk su p p ort. W h en

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th e AT system was in trod u ced , IBM p laced th e ST-506/ 412 in terface su p p ort in th e m oth erboard BIOS an d elim in ated it from th e con troller. All 16-bit an d h igh er system s sin ce th en h ave an en h an ced version of th e sam e su p p ort in th e m oth erboard BIOS as well. Becau se th is su p p ort was som ewh at lim ited , esp ecially in th e old er BIOS version s, m an y d isk con troller m an u factu rers also p laced ad d ition al BIOS su p p ort for th eir con trollers d irectly on th e con trollers th em selves. In som e cases, you wou ld u se th e con troller BIOS an d m oth erboard BIOS togeth er; in oth er cases, you wou ld d isable th e con troller or m oth erboard BIOS an d th en u se on e or th e oth er. Th ese issu es will be d iscu ssed m ore com p letely later in th is ch ap ter in th e section “System Con figu ration .” Th e ST-506/ 412 in terface d oes n ot q u ite m ake th e grad e in tod ay’s h igh -p erform an ce PC system s. Th is in terface was d esign ed for a 5M d rive, an d I h ave n ot seen an y d rives larger th an 152M (Mod ified Freq u en cy Mod u lation en cod in g) or 233M (Ru n -Len gth Lim ited en cod in g) available for th is typ e of in terface. Becau se th e cap acity, p erform an ce, an d exp an d ability of ST-506/ 412s are so lim ited , th is in terface is obsolete an d gen erally u n available in n ew system s. However, m an y old er system s still u se d rives th at h ave th is in terface. Disk Drive Encoding Schem es and Problem s. As in d icated in Ch ap ter 12, “Magn etic Storage” in th e section “Data En cod in g Sch em es,” encoding schem es are u sed in com m u n ication s for con vertin g d igital d ata bits to variou s ton es for tran sm ission over a telep h on e lin e. For d isk d rives, th e d igital bits are con verted , or encoded, in a p attern of m agn etic im p u lses, or flux transitions (also called flux reversals), wh ich are written on th e disk. Th ese flux tran sition s are decoded later, wh en th e data is read from th e disk. A device called an endec (encoder/decoder) accom p lish es th e con version to flu x tran sition s for writin g on th e m ed ia an d th e su bseq u en t recon version back to d igital d ata d u rin g read op eration s. Th e fu n ction of th e en d ec is very sim ilar to th at of a m od em (m od u lator/ d em od u lator) in th at d igital d ata is con verted to an an alog waveform , wh ich th en is con verted back to d igital d ata. Som etim es, th e en d ec is called a data separator, becau se it is d esign ed to sep arate d ata an d clockin g in form ation from th e flu x-tran sition p u lse stream read from th e d isk. On e of th e biggest p roblem s with th e origin al ST-506/ 412 in terface u sed in th e first PC h ard d isks was th e fact th at th is en d ec resid ed on th e d isk con troller (rath er th an th e d rive), wh ich resu lted in th e p ossibility of corru p tion of th e an alog d ata sign al before it reach ed th e m ed ia. Th is p roblem becam e esp ecially p ron ou n ced wh en th e ST-506/ 412 con trollers later switch ed to u sin g RLL en d ecs to store 50 p ercen t m ore d ata on th e d rive. W ith th e RLL en cod in g sch em e, th e actu al d en sity of m agn etic flu x tran sition s on th e d isk m ed ia rem ain s th e sam e as with MFM en cod in g, bu t th e tim in g between th e tran sition s m u st be m easu red m u ch m ore p recisely. In RLL encoding, th e in tervals between flu x ch an ges are ap p roxim ately th e sam e as with MFM, bu t th e actu al tim in g between th em is m u ch m ore critical. As a resu lt, th e tran sition cells in wh ich sign als m u st be recogn ized are m u ch sm aller an d m ore p recisely p laced th an with MFM. RLL en cod in g p laces m ore strin gen t d em an d s on th e tim in g of th e con troller an d d rive electron ics. W ith RLL en cod in g, accu rately read in g th e tim in g of

Storage Device Interfaces

th e flu x ch an ges is p aram ou n t. Ad d ition ally, becau se RLL en cod es variable-len gth grou p s of bits rath er th an sin gle bits, a sin gle error in on e flu x tran sition can corru p t 2 to 4 bits of d ata. For th ese reason s, an RLL con troller u su ally h as a m ore sop h isticated errord etection an d error-correction rou tin e th an an MFM con troller. Th e bottom lin e is th at oth er th an im p roved p recision , th ere is n o real d ifferen ce between an ST-506/ 412 d rive th at is sold as an MFM m od el an d on e th at is sold as an RLL m od el. On e m eth od for avoid in g reliability p roblem s in th e con version p rocess is to p lace an en d ec d irectly on th e d rive rath er th an on th e con troller. Th is m eth od red u ces th e su scep tibility to n oise an d in terferen ce th at can p lagu e som e d rive system s ru n n in g RLL en cod in g. IDE an d SCSI d rives both h ave th e en d ec (an d , often , th e en tire con troller) bu ilt in to th e d rive by d efau lt. Becau se th e en d ec is attach ed to th e d rive with ou t cables an d with an extrem ely sh ort electrical d istan ce, th e p rop en sity for tim in g- an d n oisein d u ced errors is greatly red u ced or elim in ated . Th is situ ation is an alogou s to a local telep h on e call between th e en d ec an d th e d isk p latters. Th is local com m u n ication m akes th e ESDI, IDE, an d SCSI in terfaces m u ch m ore reliable th an th e old er ST-506/ 412 in terface; th ey sh are n on e of th e reliability p roblem s th at were on ce associated with RLL en cod in g over th e ST-506/ 412 in terface. Virtu ally all ESDI, IDE, an d SCSI d rives u se RLL en cod in g tod ay with trem en d ou sly in creased reliability over even MFM ST-506/ 412 d rives. For a complete historical reference covering the original ST-506/ 412 controllers used in the PC environment, see Upgrading and Repairing PCs Sixth Edition , found in its entirety on the CDs included with this book.

The ESDI Int erface ESDI, or Enhanced Sm all Device Interface, is a sp ecialized h ard d isk in terface establish ed as a stan d ard in 1983, p rim arily by Maxtor Corp oration . Maxtor led a con sortiu m of d rive m an u factu rers to ad op t its p rop osed in terface as a h igh -p erform an ce stan d ard to su cceed ST-506/ 412. ESDI later was ad op ted by th e ANSI (Am erican Nation al Stan d ard s In stitu te) organ ization an d p u blish ed u n d er th e ANSI X3T9.2 Com m ittee. Th e latest version of th e ANSI ESDI d ocu m en t is kn own as X3.170a-1991. You can obtain th is d ocu m en t, an d oth er ANSI-stan d ard d ocu m en ts, from ANSI or from Global En gin eerin g Docu m en ts. Th ese com p an ies are listed in Ap p en d ix A. Com p ared with ST-506/ 412, ESDI h as p rovision s for in creased reliability, su ch as bu ild in g th e en d ec in to th e d rive. ESDI was m u ch faster th an th e old er ST-506/ 412 th at p reced ed it, an d was cap able of a m axim u m 24Mbit/ sec tran sfer rate. Most d rives ru n n in g ESDI, h owever, are lim ited to a m axim u m 10- or 15Mbit/ sec. Un fortu n ately, com p atibility p roblem s between d ifferen t ESDI im p lem en tation s com bin ed with p ressu re from lowcost, h igh -p erform an ce IDE in terface d rives served to m ake th e ESDI in terface obsolete by th e early ’90s. ESDI becam e som ewh at p op u lar in h igh -en d (esp ecially file server) system s d u rin g th e late ’80s.

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En h an ced com m an d s en abled som e ESDI con trollers to read a d rive’s cap acity p aram eters d irectly from th e d rive, an d to con trol d efect m ap p in g, bu t several m an u factu rers h ad d ifferen t m eth od s for writin g th is in form ation on th e d rive. W h en you in stall an ESDI d rive, in som e cases th e con troller au tom atically read s th e p aram eter an d d efect in form ation d irectly from th e d rive. In oth er cases, h owever, you still h ave to en ter th is in form ation m an u ally, as with ST-506/ 412. Th e ESDI’s en h an ced d efect-m ap p in g com m an d s p rovid e a stan d ard way for th e PC system to read a d efect m ap from a d rive, wh ich m ean s th at th e m an u factu rer’s d efect list can be written to th e d rive as a file. Th e d efect-list file th en can be read by th e con troller an d low-level form at software, elim in atin g th e n eed for th e in staller to typ e th ese en tries from th e keyboard an d en ablin g th e form at p rogram to u p d ate th e d efect list with n ew en tries if it fin d s n ew d efects d u rin g th e low-level form at or th e su rface an alysis. Most ESDI im p lem en tation s h ave d rives form atted to 32 sectors p er track or m ore (80 or m ore sectors p er track are p ossible)—m an y m ore sectors p er track th an th e stan d ard ST-506/ 412 im p lem en tation of 17 to 26. Th e greater d en sity resu lts in two or m ore tim es th e d ata-tran sfer rate, with a 1:1 in terleave. Alm ost with ou t excep tion , ESDI con trollers su p p ort a 1:1 in terleave, wh ich allows for a tran sfer rate of 1M/ sec or greater. Becau se ESDI is m u ch like th e ST-506/ 412 in terface, it can rep lace th at in terface with ou t affectin g software in th e system . Most ESDI con trollers are register-com p atible with th e old er ST-506/ 412 con trollers, wh ich en ables OS/ 2 an d oth er n on -DOS op eratin g system s to ru n with few or n o p roblem s. Th e ROM BIOS in terface to ESDI is sim ilar to th e ST-506/ 412 stan d ard , an d m an y low-level d isk u tilities th at ru n on on e in terface will ru n on th e oth er. To take ad van tage of ESDI d efect m ap p in g an d oth er sp ecial featu res, h owever, u se a low-level-form at an d su rface-an alysis u tility d esign ed for ESDI (su ch as th e on es u su ally bu ilt in to th e con troller ROM BIOS an d called by DEBUG). Du rin g th e late 1980s, m ost h igh -en d system s from m ajor m an u factu rers were eq u ip p ed with ESDI con trollers an d d rives. Startin g with th e early 1990s, m an u factu rers began eq u ip p in g h igh -en d system s su ch as n etwork file servers an d workstation s with SCSI. Th e SCSI in terface allows for m u ch greater exp an d ability, su p p orts m ore typ es of d evices th an ESDI d oes, an d offers eq u al or greater p erform an ce.

The IDE Int erface Integrated Drive Electronics (IDE) is a gen eric term ap p lied to an y d rive with an in tegrated (bu ilt-in ) d isk con troller. Th e IDE in terface as we kn ow it is officially called ATA (AT Attachm ent), an d is an ANSI stan d ard ; h owever, IDE can rou gh ly ap p ly to an y d isk d rive with a bu ilt-in con troller. Th e first d rives with in tegrated con trollers were hardcards; tod ay, a variety of d rives with in tegrated con trollers is available. In a d rive with IDE, th e d isk con troller is in tegrated in to th e d rive, an d th is com bin ation d rive/ con troller assem bly u su ally p lu gs in to a bu s con n ector on th e m oth erboard or bu s ad ap ter card . Com bin in g th e d rive an d con troller greatly sim p lifies in stallation , becau se th ere are n o sep arate p ower or sign al cables from th e con troller to th e d rive. Also, wh en th e con troller an d th e d rive are assem bled as a

The IDE Interface

u n it, th e n u m ber of total com p on en ts is red u ced , sign al p ath s are sh orter, an d th e electrical con n ection s are m ore n oise-resistan t, resu ltin g in a m ore reliable d esign th an is p ossible wh en a sep arate con troller, con n ected to th e d rive by cables, is u sed . Placin g th e con troller (in clu d in g en d ec) on th e d rive gives IDE d rives an in h eren t reliability ad van tage over in terfaces with sep arate con trollers. Reliability is in creased becau se th e d ata en cod in g, from d igital to an alog, is p erform ed d irectly on th e d rive in a tigh t n oise-free en viron m en t; th e tim in g-sen sitive an alog in form ation d oes n ot h ave to travel alon g cru d e ribbon cables th at are likely to p ick u p n oise an d in sert p rop agation d elays in to th e sign als. Th e in tegrated con figu ration allows for in creases in th e clock rate of th e en cod er an d th e storage d en sity of th e d rive. In tegratin g th e con troller an d d rive also frees th e con troller an d d rive en gin eers from h avin g to ad h ere to th e strict stan d ard s im p osed by th e earlier in terface stan d ard s. En gin eers can d esign wh at essen tially are cu stom d rive an d con troller im p lem en tation s becau se n o oth er con troller wou ld ever h ave to be con n ected to th e d rive. Th e resu ltin g d rive an d con troller com bin ation s can offer h igh er p erform an ce th an earlier stan d alon e con troller an d d rive setu p s. IDE d rives som etim es are called d rives with em bed d ed con trollers. Th e IDE con n ector on m oth erboard s in m an y system s is n oth in g m ore th an a strip p ed d own bu s slot. In ATA IDE in stallation s, th ese con n ectors n orm ally con tain a 40-p in su bset of th e 98 p in s th at wou ld be available in a stan d ard 16-bit ISA bu s slot. Th e p in s u sed are on ly th e sign al p in s req u ired by a stan d ard -typ e XT or AT h ard d isk con troller. For exam p le, becau se an AT-style d isk con troller u ses on ly in terru p t lin e 14, th e m oth erboard ATA IDE con n ector su p p lies on ly th at in terru p t lin e; n o oth er in terru p t lin es are n eed ed . Th e XT IDE m oth erboard con n ector su p p lies in terru p t lin e 5 becau se th at is wh at an XT con troller wou ld u se. Note th at even if you r ATA in terface is con n ected to th e Sou th Brid ge ch ip an d ru n s at PCI bu s sp eed s, th e p in ou t an d fu n ction s of th e p in s are still th e sam e. √√ See “ M otherboard Interface Connectors,” p. 228 √√ See “ The ISA Bus,” p. 239

Not e M any people who use systems with IDE connectors on the motherboard believe that a hard disk controller is built into their motherboard, but the controller really is in the drive. I do not know of any PC systems that have hard disk controllers built into the motherboard.

W h en IDE d rives are d iscu ssed , th e ATA IDE variety u su ally is th e on ly kin d m en tion ed becau se it is so p op u lar. Bu t oth er form s of IDE d rives exist, based on oth er bu ses. For exam p le, several PS/ 2 system s cam e with Micro-Ch an n el (MCA) IDE d rives th at p lu g d irectly in to a Micro-Ch an n el Bu s slot (th rou gh an an gle ad ap ter or in terp oser card ). An 8-bit ISA form of IDE also existed bu t was n ever very p op u lar. Most IBM-com p atible

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system s with th e ISA or EISA bu s u se AT-Bu s (16-bit) IDE d rives. Th e ATA IDE in terface is by far th e m ost p op u lar typ e of d rive in terface available.

Not e ATA is a specific interface, which is commonly called IDE. As such, they are often (technically incorrectly, I might add) used interchangeably. IDE is a generic name that could be given to any interface where the controller portion of the circuit is on the drive.

Th e p rim ary ad van tage of IDE d rives is cost. Becau se th e sep arate con troller or h ost ad ap ter is elim in ated an d th e cable con n ection s are sim p lified , IDE d rives cost m u ch less th an a stan d ard con troller-an d -d rive com bin ation . Th ese d rives also are m ore reliable, becau se th e con troller is bu ilt in to th e d rive. Th erefore, th e en d ec or d ata sep arator (th e con verter between th e d igital an d an alog sign als on th e d rive) stays close to th e m ed ia. Becau se th e d rive h as a sh ort an alog-sign al p ath , it is less su scep tible to extern al n oise an d in terferen ce. An oth er ad van tage is p erform an ce. IDE d rives are som e of th e h igh est-p erform an ce d rives available—bu t th ey also are am on g th e lowest-p erform an ce d rives. Th is ap p aren t con trad iction is a resu lt of th e fact th at all IDE d rives are d ifferen t. You can n ot m ake a blan ket statem en t abou t th e p erform an ce of IDE d rives becau se each d rive is u n iq u e. Th e h igh -en d m od els, h owever, offer p erform an ce th at is eq u al or su p erior to th at of an y oth er typ e of d rive on th e m arket for a sin gle-u ser, sin gle-taskin g op eratin g system . IDE Origins Tech n ically, th e first IDE d rives were h ard card s. Com p an ies su ch as th e Plu s Develop m en t d ivision of Qu an tu m took sm all 3 1/ 2-in ch d rives (eith er ST-506/ 412 or ESDI) an d attach ed th em d irectly to a stan d ard con troller. Th e assem bly th en was p lu gged in to a bu s slot as th ou gh it were a n orm al d isk con troller. Un fortu n ately, th e m ou n tin g of a h eavy, vibratin g h ard d isk in an exp an sion slot with n oth in g bu t a sin gle screw to h old it in p lace left a lot to be d esired —n ot to m en tion th e p ossible in terferen ce with ad jacen t card s d u e to th e fact th at m an y of th ese u n its were m u ch th icker th an a con troller card alon e. Several com p an ies got th e id ea th at you cou ld red esign th e con troller to rep lace th e logic-board assem bly on a stan d ard h ard d isk an d th en m ou n t it in a stan d ard d rive bay ju st like an y oth er d rive. Becau se th e bu ilt-in con troller in th ese d rives still n eed ed to p lu g d irectly in to th e exp an sion bu s ju st like an y oth er con troller, a cable was ru n between th e d rive an d on e of th e slots. Th ese con n ection p roblem s were solved in d ifferen t ways. Com p aq was th e first to in corp orate a sp ecial bu s ad ap ter in its system to ad ap t th e 98-p in AT bu s ed ge con n ector on th e m oth erboard to a sm aller 40-p in h ead er style con n ector th at th e d rive wou ld p lu g in to. Th e 40-p in con n ectors were all th at was n eed ed , becau se it was kn own th at a d isk con troller n ever wou ld n eed m ore th an 40 of th e bu s lin es.

The IDE Interface

In 1987, IBM d evelop ed its own MCA IDE d rives an d con n ected th em to th e bu s th rou gh a bu s ad ap ter d evice called an interposer card. Th ese bu s ad ap ters (som etim es called paddle boards or angle boards) n eed ed on ly a few bu ffer ch ip s an d d id n ot req u ire an y real circu itry becau se th e d rive-based con troller was d esign ed to p lu g d irectly in to th e bu s. Th e p ad d le board n ickn am e cam e from th e fact th at th ey resem bled gam e p ad d le or joystick ad ap ters, wh ich d o n ot h ave m u ch circu itry on th em . An oth er 8-bit variation of IDE ap p eared in 8-bit ISA system s su ch as th e PS/ 2 Mod el 30. Th e XT IDE in terface u ses a 40-p in con n ector an d cable th at is sim ilar to, bu t n ot com p atible with , th e 16-bit version . IDE Bus Versions Th ree m ain typ es of IDE in terfaces are available, with th e d ifferen ces based on th ree d ifferen t bu s stan d ard s: ■ AT Attach m en t (ATA) IDE (16-bit ISA) ■ XT IDE (8-bit ISA) ■ MCA IDE (16-bit Micro Ch an n el)

Not e M any people are confused about 16- versus 32-bit bus connections and 16- versus 32-bit hard drive connections. A PCI connection allows for a 32-bit (and possibly 64-bit in the future) bandwidth from the bus to the IDE host interface, which is normally in the motherboard chipset South Bridge. However, the actual ATA-IDE interface between the host connector on the motherboard and the drive (or drives) themselves is only a 16-bit interface. Thus, in an IDE (or EIDE) drive configuration, you are still getting only 16-bit bandwidth between the drive and the motherboardbased host interface. This usually does not create a bottleneck, because one or two hard drives cannot supply the controller enough data to saturate even a 16-bit channel.

Th e XT an d ATA version s h ave stan d ard ized on 40-p in con n ectors an d cables, bu t th e con n ectors h ave sligh tly d ifferen t p in ou ts, ren d erin g th em in com p atible with on e an oth er. MCA IDE u ses a com p letely d ifferen t 72-p in con n ector an d is d esign ed for MCA bu s system s on ly. In m ost cases, you m u st u se th e typ e of IDE d rive th at m atch es you r system bu s. Th is situ ation m ean s th at XT IDE d rives work on ly in XT-class 8-bit ISA slot system s, AT IDE (ATA) d rives work on ly in AT-class 16-bit or greater ISA/ PCI or EISA slot system s, an d MCA IDE d rives work on ly in Micro-Ch an n el system s (su ch as th e IBM PS/ 2 Mod el 50 or h igh er). A com p an y called Silicon Valley offers ad ap ter card s for XT system s th at will ru n ATA IDE d rives. Oth er com p an ies, su ch as Arco Electron ics an d Sigm a Data, h ave IDE ad ap ters for Micro-Ch an n el system s th at allow ATA IDE d rives to be u sed on th ese system s. (You can fin d th ese ven d ors in Ap p en d ix A.) Th ese ad ap ters are very u sefu l for XT or PS/ 2 system s, becau se th ere is a very lim ited selection of XT or MCA IDE d rives, wh ereas th e selection of ATA IDE d rives is virtu ally u n lim ited .

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In m ost m od ern ISA/ PCI system s, you will fin d an ATA con n ector on th e m oth erboard . If you r m oth erboard d oes n ot h ave on e of th ese con n ectors an d you wan t to attach an AT IDE d rive to you r system , you can p u rch ase an ad ap ter card th at ad d s an ATA in terface (or two) to a system via th e ISA or PCI bu s slots. Som e of th e card s offer ad d ition al featu res, su ch as an on -board ROM BIOS or cach e m em ory. ATA IDE CDC, W estern Digital, an d Com p aq actu ally created wh at cou ld be called th e first ATAtyp e IDE in terface d rive an d were th e first to establish th e 40-p in IDE con n ector p in ou t. Th e first ATA IDE d rives were 5 1/ 4-in ch h alf-h eigh t CDC 40M u n its with in tegrated W D con trollers sold in th e first Com p aq 386 system s in 1986. Even tu ally, th e 40-p in IDE con n ector an d d rive in terface m eth od was p laced before on e of th e ANSI stan d ard s com m ittees wh ich , in con ju n ction with d rive m an u factu rers, iron ed ou t som e d eficien cies, tied u p som e loose en d s, an d p u blish ed wh at is kn own as th e CAM ATA (Com m on Access Method AT Attachm ent) interface. Th e CAM Com m ittee was form ed in October 1988, an d th e first workin g d ocu m en t of th e AT Attach m en t in terface was in trod u ced in March 1989. Before th e CAM ATA stan d ard , m an y com p an ies th at followed CDC, su ch as Con n er Perip h erals, m ad e p rop rietary ch an ges to wh at h ad been d on e by CDC. As a resu lt, m an y old er ATA d rives from th e late ’80s are very d ifficu lt to in tegrate in to a d u al-d rive setu p th at h as n ewer d rives. By th e early ’90s, m ost d rive m an u factu rers brou gh t th eir d rives in to fu ll com p lian ce with th e official stan d ard , wh ich elim in ated m an y of th ese com p atibility p roblem s. Som e areas of th e ATA stan d ard h ave been left op en for ven d or-sp ecific com m an d s an d fu n ction s. Th ese ven d or-sp ecific com m an d s an d fu n ction s are th e m ain reason wh y it is so d ifficu lt to low-level form at IDE d rives. To work p rop erly, th e form atter th at you are u sin g u su ally m u st kn ow th e sp ecific ven d or-u n iq u e com m an d s for rewritin g sector h ead ers an d rem ap p in g d efects. Un fortu n ately, th ese an d oth er sp ecific d rive com m an d s d iffer from OEM to OEM, clou d in g th e “stan d ard ” som ewh at.

Not e It is important to note that only the ATA IDE interface has been standardized by the industry. The XT IDE and M CA IDE never were adopted as industry-wide standards and never became very popular. These interfaces no longer are in production, and no new systems of which I am aware come with these nonstandard IDE interfaces.

The ATA Specificat ion Th e ATA sp ecification was in trod u ced in March 1989 as an ANSI stan d ard . ATA-1 was fin ally ap p roved in 1994, an d ATA-2 (also called Enhanced IDE) was ap p roved in 1995. ATA-3 was ap p roved in 1997, an d ATA-4 is in d evelop m en t. You can obtain th e cu rren t version of th ese stan d ard s from Global En gin eerin g Docu m en ts, wh ich is listed in Ap p en d ix A. Th e ATA stan d ard s h ave gon e a lon g way toward elim in atin g in com p atibilities an d p roblem s with in terfacin g IDE d rives to ISA/ PCI bu s system s. Th e ATA sp ecification s d efin e th e sign als on th e 40-p in con n ector, th e fu n ction s an d tim in gs of th ese sign als,

The IDE Interface

cable sp ecification s, an d so on . Th e followin g section lists som e of th e elem en ts an d fu n ction s d efin ed by th e ATA sp ecification . Dual-Drive Configurat ions. Du al-d rive ATA in stallation s can be p roblem atic becau se each d rive h as its own con troller, an d both con trollers m u st fu n ction wh ile bein g con n ected to th e sam e bu s. Th ere h as to be a way to en su re th at on ly on e of th e two con trollers will resp on d to a com m an d at a tim e. Th e ATA stan d ard p rovid es th e op tion of op eratin g on th e AT Bu s with two d rives in a d aisy-ch ain ed con figu ration . Th e p rim ary d rive (d rive 0) is called th e m aster, an d th e secon d ary d rive (d rive 1) is th e slave. You d esign ate a d rive as bein g m aster or slave by settin g a ju m p er or switch on th e d rive or by u sin g a sp ecial lin e in th e in terface called th e Cable Select (CSEL) pin, an d by settin g th e CS ju m p er on th e d rive. W h en on ly on e d rive is in stalled , th e con troller resp on d s to all com m an d s from th e system . W h en two d rives (an d , th erefore, two con trollers) are in stalled , all com m an d s from th e system are received by both con trollers. Each con troller th en m u st be set u p to resp on d on ly to com m an d s for itself. In th is situ ation , on e con troller th en m u st be d esign ated as th e m aster an d th e oth er as th e slave. W h en th e system sen d s a com m an d for a sp ecific d rive, th e con troller on th e oth er d rive m u st rem ain silen t wh ile th e selected con troller an d d rive are fu n ction in g. Settin g th e ju m p er to m aster or slave allows d iscrim in ation between th e two con trollers by settin g a sp ecial bit (th e DRV bit) in th e Drive/ Head Register of a com m an d block. ATA I/ O Connect or. Th e ATA in terface con n ector is a 40-p in h ead er-typ e con n ector th at sh ou ld be keyed to p reven t th e p ossibility of in stallin g it u p sid e d own . A key is p rovid ed by th e rem oval of p in 20, an d th e corresp on d in g p in on th e cable con n ector sh ou ld be p lu gged in to p reven t a backward in stallation . Th e u se of keyed con n ectors an d cables is h igh ly recom m en d ed , becau se p lu ggin g an IDE cable in backward can d am age both th e d rive an d th e bu s ad ap ter circu its (alth ou gh I h ave d on e it m yself m an y tim es with n o sm oked p arts yet!). Table 10.11 sh ows th e ATA-IDE in terface con n ector p in ou t. Table 10.11

ATA Connect or

Signal Nam e

Pin

Pin

Signal Nam e

–RESET

1

2

GROUND

Data Bit 7

3

4

Data Bit 8

Data Bit 6

5

6

Data Bit 9

Data Bit 5

7

8

Data Bit 10

Data Bit 4

9

10

Data Bit 11

Data Bit 3

11

12

Data Bit 12

Data Bit 2

13

14

Data Bit 13

Data Bit 1

15

16

Data Bit 14

Data Bit 0

17

18

Data Bit 15 (continues)

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Table 10.11

ATA Connect or Cont inued

Signal Nam e

Pin

Pin

Signal Nam e

GROUND

19

20

KEY (pin m issing)

DRQ 3

21

22

GROUND

–IOW

23

24

GROUND

–IOR

25

26

GROUND

I/ O CH RDY

27

28

SPSYNC:CSEL

–DACK 3

29

30

GROUND

IRQ 14

31

32

–IOCS16

Address Bit 1

33

34

–PDIAG

Address Bit 0

35

36

Address Bit 2

–CS1FX

37

38

–CS3FX

–DA/ SP

39

40

GROUND

+5 Vdc (Logic)

41

42

+5 Vdc (M otor)

GROUND

43

44

–TYPE (0=ATA)

Note th at th e con n ector p in ou t sh ows 44 total p in s, alth ou gh on ly th e first 40 are u sed on m ost 3 1/ 2 in ch or larger ATA d rives. Th e ad d ition al 4 p in s sh own (p in s 41-44) are fou n d p rim arily on th e sm aller 2 1/ 2 in ch d rives u sed in n otebook an d lap top system s. Th ose d rives d on ’t h ave room for a sep arate p ower con n ector, so th e ad d ition al p in s are p rim arily d esign ed to su p p ly p ower to th e d rive. ATA I/ O Cable. A 40-con d u ctor ribbon cable is sp ecified to carry sign als between th e bu s ad ap ter circu its an d th e d rive (con troller). To m axim ize sign al in tegrity an d to elim in ate p oten tial tim in g an d n oise p roblem s, th e cable sh ou ld n ot be lon ger th an 0.46 m eters (18 in ch es). Note th at th e n ewer h igh -sp eed IDE in terfaces are esp ecially su scep tible to cable p roblem s, an d cables th at are too lon g. If th e cable is too lon g, you will exp erien ce d ata corru p tion an d oth er errors th at can be m ad d en in g. I always keep a sp ecial h igh -q u ality sh ort IDE cable in m y toolbox for testin g d rives wh ere I su sp ect th is p roblem . ATA Signals. Th is section d escribes som e of th e m ost im p ortan t sign als in m ore d etail. Pin 20 is u sed as a key p in for cable orien tation an d is n ot con n ected th rou gh in th e in terface. Th is p in sh ou ld be m issin g from an y ATA con n ectors, an d th e cable sh ou ld h ave th e p in -20 h ole in th e con n ector p lu gged off to p reven t th e cable from bein g p lu gged in backward . Pin 39 carries th e Drive Active/Slave Present (DASP) signal, wh ich is a d u al-p u rp ose, tim em u ltip lexed sign al. Du rin g p ower-on in itialization , th is sign al in d icates wh eth er a slave d rive is p resen t on th e in terface. After th at, each d rive asserts th e sign al to in d icate th at it is active. Early d rives cou ld n ot m u ltip lex th ese fu n ction s an d req u ired sp ecial ju m p er settin gs to work with oth er d rives. Stan d ard izin g th is fu n ction to allow for com p atible d u al-d rive in stallation s is on e of th e featu res of th e ATA stan d ard .

The IDE Interface

Pin 28 carries th e Cable Select or Spindle Synchronization signal (CSEL or SPSYNC), wh ich is a d u al-p u rp ose con d u ctor; a given in stallation , h owever, m ay u se on ly on e of th e two fu n ction s. Th e CSEL fu n ction is th e m ost wid ely u sed an d is d esign ed to con trol th e d esign ation of a d rive as m aster (d rive 0) or slave (d rive 1) with ou t req u irin g ju m p er settin gs on th e d rives. If a d rive sees th e CSEL as bein g grou n d ed , th e d rive is a m aster; if CSEL is op en , th e d rive is a slave. You can in stall sp ecial cablin g to grou n d CSEL selectively. Th is in stallation n orm ally is accom p lish ed th rou gh a Y-cable arran gem en t, with th e IDE bu s con n ector in th e m id d le an d each d rive at op p osite en d s of th e cable. On e leg of th e Y h as th e CSEL lin e con n ected th rou gh , in d icatin g a m aster d rive; th e oth er leg h as th e CSEL lin e op en (con d u ctor in terru p ted or rem oved ), m akin g th e d rive at th at en d th e slave. ATA Com m ands. On e of th e best featu res of th e ATA IDE in terface is th e en h an ced com m an d set. Th e ATA IDE in terface was m od eled after th e W D1003 con troller th at IBM u sed in th e origin al AT system . All ATA IDE d rives m u st su p p ort th e origin al W D com m an d set (eigh t com m an d s), with n o excep tion s, wh ich is wh y IDE d rives are so easy to in stall in system s tod ay. All IBM-com p atible system s h ave bu ilt-in ROM BIOS su p p ort for th e W D1003, wh ich m ean s th at, essen tially, th ey su p p ort ATA IDE as well. In ad d ition to su p p ortin g all th e W D1003 com m an d s, th e ATA sp ecification ad d ed n u m erou s oth er com m an d s to en h an ce p erform an ce an d cap abilities. Th ese com m an d s are an op tion al p art of th e ATA in terface, bu t several of th em are u sed in m ost d rives available tod ay an d are very im p ortan t to th e p erform an ce an d u se of ATA d rives in gen eral. Perh ap s th e m ost im p ortan t is th e Identify Drive com m an d . Th is com m an d cau ses th e d rive to tran sm it a 512-byte block of d ata th at p rovid es all d etails abou t th e d rive. Th rou gh th is com m an d , an y p rogram (in clu d in g th e system BIOS) can fin d ou t exactly wh at typ e of d rive is con n ected , in clu d in g th e d rive m an u factu rer, m od el n u m ber, op eratin g p aram eters, an d even th e serial n u m ber of th e d rive. Man y m od ern BIOSs u se th is in form ation to au tom atically receive an d en ter th e d rive’s p aram eters in to CMOS m em ory, elim in atin g th e n eed for th e u ser to en ter th ese p aram eters m an u ally d u rin g system con figu ration . Th is arran gem en t h elp s p reven t m istakes th at can later lead to d ata loss wh en th e u ser n o lon ger rem em bers wh at p aram eters h e or sh e u sed d u rin g setu p . Th e Id en tify Drive d ata can tell you m an y th in gs abou t you r d rive, in clu d in g th e followin g: ■ Nu m ber of cylin d ers in th e recom m en d ed (d efau lt) tran slation m od e ■ Nu m ber of h ead s in th e recom m en d ed (d efau lt) tran slation m od e ■ Nu m ber of sectors p er track in th e recom m en d ed (d efau lt) tran slation m od e ■ Nu m ber of cylin d ers in th e cu rren t tran slation m od e ■ Nu m ber of h ead s in th e cu rren t tran slation m od e ■ Nu m ber of sectors p er track in th e cu rren t tran slation m od e

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■ Man u factu rer an d m od el n u m ber ■ Firm ware revision ■ Serial n u m ber ■ Bu ffer typ e, in d icatin g sector bu fferin g or cach in g cap abilities Several p u blic-d om ain p rogram s can execu te th is com m an d to th e d rive an d rep ort th e in form ation on screen . I u se th e IDEINFO (available at h t t p :/ / w w w .d c .e e / Fi l e s/ Ut i l s/ ID EINFO.ARJ) or IDEDIAG (available from m an y of th e p op u lar sh areware sites) p rogram . I fin d th ese p rogram s esp ecially u sefu l wh en I am tryin g to in stall IDE d rives an d n eed to kn ow th e correct p aram eters for a u ser-d efin able BIOS typ e. Th ese p rogram s get th e in form ation d irectly from th e d rive. Two oth er very im p ortan t com m an d s are th e Read Multiple an d Write Multiple com m an d s. Th ese com m an d s p erm it m u ltip le-sector d ata tran sfers an d , wh en com bin ed with block-m od e Program m ed I/ O (PIO) cap abilities in th e system , can resu lt in in cred ible d ata-tran sfer rates m an y tim es faster th an sin gle-sector PIO tran sfers.

Tip If you want the ultimate in IDE performance and installation ease, make sure that your motherboard BIOS and IDE adapter support ATA-2 or EIDE. This support allows your BIOS to execute data transfers to and from the IDE drive several times faster than normal, and also makes installation and configuration easier because the BIOS will be able to detect the drive-parameter information automatically. The most recent South Bridge chipsets found on motherboards today implement the Ultra-DM A (UDM A or Ultra-33) 33M / sec interface, which is part of the most recent ATA-3 standard.

Th ere are m an y oth er en h an ced com m an d s, in clu d in g room for a given d rive m an u factu rer to im p lem en t wh at are called vendor-unique com m ands. Th ese com m an d s often are u sed by a p articu lar ven d or for featu res u n iq u e to th at ven d or. Often , featu res su ch as low-level form attin g an d d efect m an agem en t are con trolled by ven d or-u n iq u e com m an d s. Th is is wh y low-level form at p rogram s can be so sp ecific to a p articu lar m an u factu rer’s IDE d rives an d wh y m an y m an u factu rers m ake th eir own LLF p rogram s available. ATA IDE Drive Cat egories ATA-IDE d rives can be d ivid ed in to th ree m ain categories. Th ese categories sep arate th e d rives by fu n ction (su ch as tran slation cap abilities) an d d esign (wh ich can affect featu res su ch as low-level form attin g): ■ Non -In telligen t ATA-IDE d rives ■ In telligen t ATA-IDE d rives ■ In telligen t Zon ed Record in g ATA-IDE d rives

The IDE Interface

Non-Int elligent IDE. As I stated earlier, th e ATA stan d ard req u ires th at th e bu ilt-in con troller resp on d exactly as th ou gh it were a W estern Digital W D1003 con troller. Th is con troller resp on d s to a com m an d set of eigh t com m an d s. Early IDE d rives su p p orted th ese com m an d s an d h ad few, if an y, oth er op tion s. Th ese early d rives actu ally were m ore like regu lar ST-506/ 412 or ESDI con trollers bolted d irectly in to th e d rive th an th e m ore in telligen t d rives th at we con sid er tod ay to be IDE. Th ese d rives were n ot con sid ered to be in telligen t IDE d rives; an in telligen t d rive is su p p osed to h ave several cap abilities th at th ese early IDE d rives lacked . Th e d rives cou ld n ot resp on d to an y of th e en h an ced com m an d s th at were sp ecified as (an op tion al) p art of th e ATA IDE sp ecification , in clu d in g th e Identify Drive com m an d . Th ese d rives also d id n ot su p p ort sector translation, in wh ich th e p h ysical p aram eters cou ld be altered to ap p ear as an y set of logical cylin d ers, h ead s, an d sectors. En h an ced com m an d s an d sector-tran slation su p p ort are wh at m ake an IDE d rive an in telligen t IDE d rive, an d th ese featu res were n ot available in th e early IDE d rives. Th ese d rives cou ld be low-level form atted in th e sam e m an n er as an y n orm al ST-506/ 412 or ESDI d rive. Th ey were u n iversally low-level form atted at th e factory, with factorycalcu lated op tim u m in terleave (u su ally 1:1) an d h ead - an d cylin d er-skew factors. Also, factory d efects were record ed in a sp ecial area on th e d rive; th ey n o lon ger were written on a sticker p asted to th e exterior. Un fortu n ately, th is arran gem en t m ean s th at if you low-level form at th ese d rives in th e field , you m ost likely will alter th ese settin gs (esp ecially th e skew factors) from wh at th e factory set as op tim u m , an d wip e ou t th e factorywritten d efect table. Som e m an u factu rers released sp ecial low-level form at rou tin es th at wou ld reform at th e d rives wh ile p reservin g th ese settin gs, bu t oth ers d id n ot m ake su ch p rogram s available. Becau se th ey d id n ot wan t you to overwrite th e d efect list or p oten tially slow th e d rive, m ost m an u factu rers stated th at you sh ou ld n ever low-level form at th eir IDE d rives. Th is statem en t started a m yth th at th e d rives cou ld som eh ow be d am aged or ren d ered in op erable by su ch a form at, wh ich tru ly is n ot th e case. On e ru m or was th at th e servo in form ation cou ld be overwritten , wh ich wou ld m ean th at you wou ld h ave to sen d th e d rive back to th e m an u factu rer for re-servoin g. Th is also is n ot tru e; th e servo in form ation is p rotected an d can n ot be overwritten . Th e on ly con seq u en ce of an im p rop er lowlevel form at of th ese d rives is th e p ossible alteration of th e skew factors an d th e p oten tial loss of th e factory d efect m ap s. Th e Disk Man ager p rogram by On track is th e best sp ecial-p u rp ose form at u tility to u se on th ese d rives for form attin g becau se it is aware of th ese typ es of d rives an d often can restore th e skew factors an d p reserve th e d efect in form ation . If you are workin g with a d rive th at alread y h as h ad th e d efect m ap overwritten , Disk Man ager can p erform a very good su rface an alysis th at will m ark off an y of th ese areas th at it fin d s. Disk Man ager allows you to sp ecify th e skew factors an d to m ark d efects at th e sector level so th at th ey will n ot cau se p roblem s later. Oth er gen eral-p u rp ose d iagn ostics th at work esp ecially well with IDE d rives su ch as th is in clu d e th e PC-Tech n ician p rogram by W in d sor Tech n ologies an d Microscop e by Micro 2000. An oth er altern ative is th e Drive Pro software from MicroHou se.

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Int elligent IDE. Later IDE d rives becam e kn own as intelligent IDE drives. Th ese d rives su p p ort en h an ced ATA com m an d s, su ch as th e Identify Drive com m an d , an d sectortran slation cap abilities. Th ese d rives can be con figu red in two ways: in raw p h ysical m od e or in tran slation m od e. To con figu re th e d rive in raw p h ysical m od e, you sim p ly en ter th e CMOS d rive p aram eters d u rin g setu p so th at th ey m atch th e tru e p h ysical p aram eters of th e d rive. For exam p le, if th e d rive p h ysically h as 800 cylin d ers, 6 h ead s, an d 50 sectors p er track, you en ter th ese figu res d u rin g setu p . To con figu re th e d rive in tran slation m od e, you sim p ly en ter an y com bin ation of cylin d ers, h ead s, an d sectors th at ad d s u p to eq u al or less th an th e tru e n u m ber of sectors on th e d rive. In th e exam p le I ju st u sed , th e d rive h as a total of 240,000 sectors (800×6×50). All I h ave to d o is figu re ou t an oth er set of p aram eters th at ad d s u p to eq u al or less th an 240,000 sectors. Th e sim p lest way to d o th is is to cu t th e n u m ber of cylin d ers in h alf an d d ou ble th e n u m ber of h ead s. Th u s, th e n ew d rive p aram eters becom e 400 cylin d ers, 12 h ead s, an d 50 sectors p er track. Th is m eth od ad d s u p to 240,000 sectors an d en ables th e d rive to work in tran slation m od e. W h en th ese d rives are in tran slation m od e, a low-level form at can n ot alter th e in terleave an d skew factors, n or can it overwrite th e factory d efect-m ap p in g in form ation . A lowlevel form at p rogram can , h owever, p erform ad d ition al d efect m ap p in g or sector sp arin g wh ile in th is m od e. If th e d rive is in tru e p h ysical m od e, a low-level form at rewrites th e sector h ead ers an d m od ifies th e h ead an d cylin d er skewin g. If p erform ed in correctly, th e form at can be rep aired by a p rop er low-level form at p rogram th at allows you to set th e correct h ead an d cylin d er skew. Th is task can be accom p lish ed au tom atically by th e d rive m an u factu rer’s recom m en d ed low-level form at p rogram (if available) or by oth er p rogram s, su ch as Disk Man ager by On track. W h en you u se Disk Man ager, you h ave to en ter th e skew valu es m an u ally; oth erwise, th e p rogram u ses p red eterm in ed d efau lts. To obtain th e correct skew valu es, it is best to con tact th e d rive m an u factu rer’s tech n ical su p p ort d ep artm en t. You can calcu late th e skew valu es if th e m an u factu rer can n ot p rovid e th em . Skew valu es n orm ally on ly ap p ly to n on -IDE or n on -SCSI d rives, as IDE an d SCSI d rives n orm ally d on ’t allow a tru e p h ysical form at; th at can on ly be d on e at th e factory. ◊◊ See “ Hard Drive Parameters,” p. 1353

To p rotect th e skew factors an d d efect in form ation on in telligen t IDE d rives, all you h ave to d o is ru n th em in tran slation m od e. In tran slation m od e, th is in form ation can n ot be overwritten . Int elligent Zoned Recording IDE. Most m od ern IDE d rives com bin e in telligen ce with Zon ed Record in g. W ith Zoned Recording, th e d rive h as a variable n u m ber of sectors p er track in several zon es across th e su rface of th e d rive. Becau se th e PC BIOS can h an d le on ly a fixed n u m ber of sectors on all tracks, th ese d rives always m u st ru n in tran slation

The IDE Interface

m od e. Becau se th ese d rives are always in tran slation m od e, you can n ot alter th e factoryset in terleave an d skew factors or wip e ou t th e factory d efect in form ation . You still can low-level form at th ese d rives, h owever, an d u se su ch a form at to m ap or sp are ad d ition al d efective sectors th at crop u p d u rin g th e life of th e d rive. To low-level form at in telligen t Zon ed Record in g d rives, you n eed eith er a sp ecific u tility from th e d rive m an u factu rer or an IDE-aware p rogram , su ch as Disk Man ager by On track, PCTech n ician by W in d sor Tech n ologies, Microscop e by Micro 2000, or Drive Pro by MicroHou se. ATA-2 and ATA-3 ( Enhanced IDE) ATA-2 an d ATA-3 are exten sion s of th e origin al ATA (IDE) sp ecification . Th e m ost im p ortan t ad d ition s are p erform an ce-en h an cin g featu res su ch as fast PIO an d DMA m od es. ATA-2 also featu res im p rovem en ts in th e Id en tify Drive com m an d allowin g a d rive to tell th e software exactly wh at its ch aracteristics are; th is is essen tial for both Plu g an d Play (Pn P) an d com p atibility with fu tu re revision s of th e stan d ard . ATA-3 ad d s im p roved reliability, esp ecially of th e faster m od e 4 tran sfers; n ote th at ATA-3 d oes n ot d efin e an y faster m od es. ATA-3 also ad d s a sim p le p assword -based secu rity sch em e, m ore sop h isticated p ower m an agem en t, an d Self Mon itorin g An alysis an d Rep ort Tech n ology (SMART). Th is allows a d rive to keep track of p roblem s th at m igh t resu lt in a failu re. ATA-2 an d 3 are often called En h an ced IDE (or EIDE). EIDE is tech n ically a m arketin g p rogram from W estern Digital. Fast-ATA an d Fast-ATA-2 are sim ilar Seagate-in sp ired m arketin g p rogram s, wh ich are also en d orsed by Qu an tu m . As far as th e h ard d isk an d BIOS are con cern ed , th ese are all d ifferen t term s for basically th e sam e th in g. Th ere are fou r m ain areas wh ere ATA-2 (EIDE), ATA-3, an d ATA-4 h ave im p roved th e origin al ATA/ IDE in terface in several ways: ■ In creased m axim u m d rive cap acity ■ Faster d ata tran sfer ■ Secon d ary two-d evice ch an n el ■ ATAPI (ATA Program In terface) Th e followin g section s d escribe th ese im p rovem en ts. Increased Drive Capacit y. ATA-2/ EIDE allows for in creased d rive cap acity over th e origin al ATA/ IDE sp ecification . Th is is d on e th rou gh an En h an ced BIOS, wh ich m akes it p ossible to u se h ard d isks exceed in g th e 504M barrier. Th e origin of th is lim it is th e d isk geom etry (cylin d ers, h ead s, sectors) su p p orted by th e com bin ation of an IDE d rive an d th e BIOS’ software in terface. Both IDE an d th e BIOS are cap able of su p p ortin g h u ge d isks, bu t th eir com bin ed lim itation s con sp ire to restrict th e u sefu l cap acity to 504M. An En h an ced BIOS circu m ven ts th is by u sin g a d ifferen t geom etry wh en talkin g to th e d rive th an wh en talkin g to th e software. W h at h ap p en s in between is called translation. For exam p le, if you r d rive h as 2,000 cylin d ers an d 16 h ead s, a tran slatin g BIOS will m ake p rogram s th in k th at th e d rive h as 1,000 cylin d ers an d 32 h ead s.

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◊◊ See “ Hard Drive Parameters,” p. 1353

You can u su ally tell if you r BIOS is en h an ced by th e cap ability to sp ecify m ore th an 1,024 cylin d ers in th e BIOS setu p , alth ou gh th is is in con clu sive. If you see d rive-related settin gs like LBA, ECHS, or even Large, th ese are telltale sign s of a BIOS with tran slation su p p ort. Most BIOSs with a d ate of 1994 or later are en h an ced . If you r system cu rren tly d oes n ot h ave an En h an ced BIOS, you m ay be able to get an u p grad e. Th ere are th ree ways tod ay’s BIOSs can h an d le tran slation : Stan d ard CHS ad d ressin g, Exten d ed CHS ad d ressin g, an d LBA ad d ressin g. Th ey are su m m arized in th e followin g table. BIOS M ode

Operat ing Syst em t o BIOS

BIOS t o Drive Port s

Standard CHS

Logical CHS Parameters

Logical CHS Parameters

Extended CHS

Translated CHS Parameters

Logical CHS Parameters

LBA

Translated CHS Parameters

LBA Parameters

In Stan d ard CHS, th ere is on ly on e p ossible tran slation step in tern al to th e d rive. Th e d rive’s actu al, p h ysical geom etry is com p letely in visible from th e ou tsid e with all zon ed record ed ATA d rives tod ay. Th e Cylin d ers, Head s, an d Sectors p rin ted on th e label for u se in th e BIOS setu p are p u rely logical geom etry, an d d o n ot rep resen t th e actu al p h ysical p aram eters. Stan d ard CHS ad d ressin g is lim ited to 16 h ead s an d 1,024 cylin d ers, wh ich gives u s a lim it of 504M. Th is is often called “Norm al” in th e BIOS setu p , an d cau ses th e BIOS to beh ave like an old -fash ion ed on e with ou t tran slation . Use th is settin g if you r d rive h as fewer th an 1,024 cylin d ers or if you wan t to u se th e d rive with a n on -DOS op eratin g system th at d oesn ’t u n d erstan d tran slation . In Exten d ed CHS, a tran slated logical geom etry is u sed to com m u n icate between th e d rive an d th e BIOS, wh ile a d ifferen t tran slated geom etry is u sed to com m u n icate between th e BIOS an d everyth in g else. In oth er word s, th ere are n orm ally two tran slation step s. Th e d rive still tran slates in tern ally, bu t h as logical p aram eters th at exceed th e 1,024 cylin d er lim itation of th e stan d ard BIOS. In th is case, th e d rive’s cylin d er cou n t is u su ally d ivid ed by 2, an d th e h ead cou n t is m u ltip lied by 2 to get th e tran slated valu es from th ose actu ally stored in th e CMOS Setu p . Th is typ e of settin g breaks th e 504/ 528M barrier. Th is is often called “Large” or “ECHS” in th e BIOS setu p , an d tells th e BIOS to u se Exten d ed CHS tran slation . It u ses a d ifferen t geom etry (cylin d ers/ h ead s/ sectors) wh en talkin g to th e d rive th an wh en talkin g to th e BIOS. Th is typ e of tran slation sh ou ld be u sed with d rives th at h ave m ore th an 1,024 cylin d ers bu t th at d o n ot su p p ort LBA (Logical Block Ad d ressin g). Note th at th e geom etry en tered in you r BIOS setu p is th e logical geom etry, n ot th e tran slated on e.

The IDE Interface

LBA is a m ean s of lin early ad d ressin g sector ad d resses, begin n in g at Cylin d er 0, Head 0, Sector 1 as LBA 0, an d p roceed in g on to th e last p h ysical sector on th e d rive. Th is is n ew in ATA-2, bu t h as always been th e on e an d on ly ad d ressin g m od e in SCSI. W ith LBA, each sector on th e d rive is n u m bered startin g from 0. Th e n u m ber is a 28-bit bin ary n u m ber in tern ally, wh ich tran slates to a sector n u m ber from 0 to 268,435,456. Becau se each sector rep resen ts 512 bytes, th is resu lts in a m axim u m d rive cap acity of exactly 128G, or 137 billion bytes. Un fortu n ately, th e op eratin g system still n eed s to see a tran slated CHS, so th e BIOS d eterm in es h ow m an y sectors th ere are, an d com es u p with Tran slated CHS to m atch . Th e BIOS CHS lim its are 1,024 cylin d ers, 256 h ead s, an d 63 sectors p er track, wh ich lim its total d rive cap acity to ju st u n d er 8G. In oth er word s, th is breaks th e 528M barrier in essen tially th e sam e way as Exten d ed CHS d oes. Becau se it is som ewh at sim p ler to u se a sin gle lin ear n u m ber to ad d ress a sector on th e h ard d isk com p ared to a CHS typ e ad d ress, th is is th e p referred m eth od if th e d rive su p p orts LBA.

Caut ion A word of warning with these BIOS translation settings: If you switch between Standard CHS, Extended CHS, or LBA, the BIOS may change the (translated) geometry. The same thing may happen if you transfer a disk that has been formatted on an old, non-LBA computer to a new one that uses LBA. This will cause the logical CHS geometry seen by the operating system to change, and will cause the data to appear in the wrong locations from where it actually is! This can cause you to lose access to your data if you are not careful. I always recommend recording the CM OS Setup screens associated with the hard disk configuration so that you can properly match the setup of a drive to the settings it was originally at.

Fast er Dat a Transfer. ATA-2/ EIDE an d ATA-3 d efin e several h igh -p erform an ce m od es for tran sferrin g d ata to an d from th e d rive. Th ese faster m od es are th e m ain p art of th e n ew sp ecification s an d were th e m ain reason th ey were in itially d evelop ed . Most of th e faster d rives on th e m arket tod ay will su p p ort eith er PI/ O tran sfer Mod e 3 or Mod e 4, wh ich resu lts in a very fast tran sfer. Th e followin g section d iscu sses th ese m od es. Th e PIO m od e d eterm in es h ow fast d ata is tran sferred to an d from th e d rive. In th e slowest p ossible m od e, PIO m od e 0, th e d ata cycle tim e can n ot exceed 600 n an osecon d s (n s). In a sin gle cycle, 16 bits are tran sferred in to or ou t of th e d rive m akin g th e th eoretical tran sfer rate of PIO Mod e 0 (600n s cycle tim e) 3.3M/ sec. Most of th e h igh -p erform an ce ATA-2 (EIDE) d rives tod ay su p p ort PIO Mod e 4, wh ich offers a 16.6M/ sec tran sfer rate. Th e followin g table sh ows th e PIO m od es, with th eir resp ective tran sfer rates. PIO M ode

Cycle Tim e ( ns)

Transfer Rat e ( M / sec)

Specificat ion

0

600

3.33

ATA

1

383

5.22

ATA

2

240

8.33

ATA

3

180

11.11

ATA-2

4

120

16.67

ATA-2

623

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To ru n in Mod e 3 or 4 req u ires th at th e IDE p ort on th e system be a local bu s p ort. Th is m ean s th at it m u st op erate th rou gh eith er a VL-Bu s or PCI bu s con n ection . Most m oth erboard s with ATA-2/ EIDE su p p ort h ave d u al IDE con n ectors on th e m oth erboard , an d m ost of th em n ow allow fu ll th rou gh p u t. Old er 486 an d som e early Pen tiu m board s h ave on ly th e p rim ary con n ector ru n n in g th rou gh th e system ’s PCI local bu s. Th e secon d ary con n ector on th ose board s u su ally ru n s th rou gh th e ISA bu s, an d th erefore su p p orts u p to Mod e 2 op eration on ly. W h en in terrogated with an Identify Drive com m an d , a h ard d isk retu rn s, am on g oth er th in gs, in form ation abou t th e PIO an d DMA m od es it is cap able of u sin g. Most en h an ced BIOSs will au tom atically set th e correct m od e to m atch th e cap abilities of th e d rive. If you set a m od e faster th an th e d rive can h an d le, d ata corru p tion will resu lt. ATA-2 an d n ewer d rives also p erform Block Mode PIO, wh ich m ean s th at th ey u se th e Read/Write Multiple com m an d s th at greatly red u ce th e n u m ber of in terru p ts sen t to th e h ost p rocessor. Th is lowers th e overh ead , an d th e resu ltin g tran sfers are even faster. DM A Transfer M odes. Alth ou gh it is n ot u sed by m ost op eratin g system s or BIOSs, ATA-2 d rives also su p p ort Direct Mem ory Access tran sfers. DMA m ean s th at th e d ata is tran sferred d irectly between d rive an d m em ory with ou t u sin g th e CPU as an in term ed iary, as op p osed to PIO. Th ere are two d istin ct typ es of d irect m em ory access: DMA an d busm astering DMA. Ord in ary DMA relies on th e DMA con troller on th e system ’s m ain board to p erform th e com p lex task of arbitration , grabbin g th e system bu s an d tran sferrin g th e d ata. In th e case of bu sm asterin g DMA, all th is is d on e by logic on th e in terface card . Of cou rse, th is ad d s con sid erably to th e com p lexity an d th e p rice of a bu sm asterin g in terface. System s u sin g th e In tel PIIX (PCI IDE ISA eXcelerator) an d later Sou th Brid ge ch ip s h ave th e cap ability of su p p ortin g Bu s Master IDE. Th is u ses th e bu sm aster m od e on th e PCI bu s to execu te d ata tran sfers. Th e bu sm aster IDE m od es an d tran sfer rates are sh own in th e followin g table. BM IDE M ode

Cycle Tim e ( ns)

Transfer Rat e ( M / sec)

Specificat ions

0

480

4.16

ATA-2

1

150

3.33

ATA-2

2

120

16.67

ATA-2

Un fortu n ately, even th e fastest bu sm aster IDE m od e 2 resu lts in th e sam e 16.67M/ sec tran sfer sp eed as PIO Mod e 4, so bu sm aster IDE n ever really cau gh t on as bein g d esirable, an d m ost of th e tim e it is recom m en d ed to stick with th e stan d ard PIO Mod e 4 on d rives th at su p p ort it. Bu sm aster IDE m od es were n ever very effective an d h ave n ow been su p ersed ed by th e n ewer Ultra-DMA m od es su p p orted in ATA-4 com p atible d evices. ATAPI ( ATA Packet Int erface) . ATAPI is a stan d ard d esign ed for d evices su ch as CD-ROMs an d tap e d rives th at p lu g in to an ord in ary ATA (IDE) con n ector. Th e p rin cip al ad van tage of ATAPI h ard ware is th at it’s ch eap an d works on you r cu rren t ad ap ter. For CD-ROMs, it h as a som ewh at lower CPU u sage com p ared to p rop rietary ad ap ters, bu t

The IDE Interface

th ere’s n o p erform an ce gain oth erwise. For tap e d rives, ATAPI h as p oten tial for su p erior p erform an ce an d reliability com p ared to th e p op u lar flop p y con troller attach ed tap e d evices. ATAPI is also u sed to ru n oth er rem ovable storage d evices su ch as th e LS-120 su p erd isk d rives an d in tern al Iom ega Zip an d Jaz d rives. Alth ou gh ATAPI CD-ROMs u se th e h ard d isk in terface, th is d oes n ot m ean th ey look like ord in ary h ard d isks; to th e con trary, from a software p oin t of view, th ey are a com p letely d ifferen t kin d of an im al. Th ey actu ally m ost closely resem ble a SCSI d evice.

Caut ion ATAPI support is not found directly in the BIOS of many systems. Systems without ATAPI support in the BIOS cannot boot from an ATAPI CD-ROM and you still must load a driver to use it under DOS or Windows. Windows 95 and Windows NT have native ATAPI support, and newer systems with ATAPI-aware BIOS which will even allow booting from an ATAPI CD-ROM are now available. The Windows 98 and NT 5.0 CD-ROM s will be directly bootable on those systems, greatly easing installation.

An oth er n ote is th at I n orm ally recom m en d keep in g d ifferen t typ es of IDE d evices on sep arate ch an n els. Som e old er ch ip sets can n ot su p p ort settin g d ifferen t tran sfer rates for d ifferen t d evices, wh ich m ean s th e ch an n el m u st be set to th e sp eed of th e slowest d evice. Becau se m ost CD-ROM an d tap e d rives ru n at lower IDE m od e sp eed s, th is wou ld force you r h ard d isk to ru n slower if th ey sh ared a sin gle cable. Even if th e ch ip set you h ave su p p orts sep arate sp eed settin gs for d evices on th e sam e ch an n el (cable), I still recom m en d keep in g th em sep arate as IDE d oes n ot n orm ally su p p ort overlap p in g access su ch as SCSI. In oth er word s, wh en on e d rive is ru n n in g, th e oth er can n ot be accessed . By keep in g th e CD-ROM an d h ard d isk on sep arate ch an n els, you can m ore effectively overlap accessin g between th em . ATA-4 ATA-4 is th e latest revision of ATA an d sh ou ld receive fin al ap p roval in 1998. Even so, n u m erou s d rives an d in terfaces alread y fu lly su p p ort th e latest version . Th e n ewer PIIX4 an d later Sou th Brid ge ch ip s from th e In tel m oth erboard ch ip sets su p p ort ATA-4, an d m an y of th e n ew d rives su p p ort th e h igh -sp eed UDMA (Ultra-DMA) tran sfer m od e. √√ See “ Chipsets,” p. 183

ATA-4 m akes ATAPI (ATA Packet In terface) su p p ort a fu ll p art of th e ATA stan d ard , an d th u s ATAPI is n o lon ger an au xiliary in terface to ATA bu t is m erged com p letely with in . Th is sh ou ld p rom ote ATA for u se as an in terface for m an y oth er typ es of d evices. ATA-4 also ad d s su p p ort for n ew Ultra-DMA m od es (also called Ultra-ATA) for even faster d ata tran sfer. Th e h igh est-p erform an ce m od e, called DMA/ 33, h as 33M/ secon d ban d wid th , twice th at of th e fastest p rogram m ed I/ O m od e or DMA m od e p reviou sly su p p orted . Also in clu d ed is su p p ort for q u eu in g com m an d s, wh ich is sim ilar to th at p rovid ed in SCSI-2. Th is allows for better m u ltitaskin g as m u ltip le p rogram s m ake req u ests for IDE tran sfers.

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◊◊ See “ IDE Versus SCSI,” p. 646

Obsolet e IDE Versions As m en tion ed earlier, oth er version s of th e IDE in terface were u sed in som e early system s. W h ile you m ay fin d som e system s based on th ese in terfaces if you are su p p ortin g legacy h ard ware, n on e of th ese h as been u sed in an y n ew system sin ce th e ap p roval of th e ATA-1 stan d ard in 1994. XT-Bus ( 8-Bit ) IDE. Man y system s with XT ISA bu s arch itectu re u sed XT IDE h ard d rives. Th e IDE in terface in th ese system s u su ally is bu ilt in to th e m oth erboard . Th e IBM PS/ 2 Mod els 25, 25-286, 30, an d 30-286 system s u sed an 8-bit XT IDE in terface. Th ese 8-bit XT IDE d rives are d ifficu lt to fin d ; few m an u factu rers oth er th an IBM, W estern Digital, an d Seagate m ad e th em ; n on e of th ese d rives were available in cap acities beyon d 40M. Becau se th e ATA IDE in terface is a 16-bit d esign , it cou ld n ot be u sed in 8-bit (XT typ e) system s, so som e of th e d rive m an u factu rers stan d ard ized an XT-Bu s (8-bit) IDE in terface for XT class system s. Th ese d rives were n ever very p op u lar, an d were u su ally on ly available in cap acities from 20M to 40M. M CA IDE. Th e IBM PS/ 2 Mod els 50 an d h igh er com e with Micro-Ch an n el Arch itectu re (MCA) bu s slots. IBM u sed a typ e of MCA IDE d rive in m an y of th ese system s. MCA IDE is a form of IDE in terface, bu t it is d esign ed for th e MCA bu s an d is n ot com p atible with th e m ore in d u stry-stan d ard ATA IDE in terface. Few com p an ies oth er th an IBM an d W estern Digital m ake rep lacem en t MCA IDE d rives for th ese system s. I recom m en d rep lacin g th ese d rives with ATA IDE d rives, u sin g ad ap ters from Arco Electron ics or Sigm a Data, or switch in g to SCSI d rives in stead . Th e IBM MCA IDE d rives are exp en sive for th e lim ited cap acity th at th ey offer.

Sm all Com put er Syst em Int erface ( SCSI) SCSI (p ron ou n ced “scu zzy”) stan d s for Sm all Com puter System Interface. Th is in terface h as its roots in SASI, th e Shugart Associates System Interface. SCSI is n ot a d isk in terface, bu t a system s-level in terface. SCSI is n ot a typ e of con troller, bu t a bu s th at su p p orts as m an y as 8 or 16 total d evices. On e of th ese d evices, th e h ost ad ap ter, fu n ction s as th e gateway between th e SCSI bu s an d th e PC system bu s. Th e SCSI bu s d oes n ot talk d irectly with d evices su ch as h ard d isks; in stead , it talks to th e con troller th at is bu ilt in to th e d rive. A sin gle SCSI bu s can su p p ort as m an y as 8 or 16 p h ysical u n its, u su ally called SCSI IDs. On e of th ese u n its is th e ad ap ter card in you r PC; th e oth er seven can be oth er p erip h erals. You cou ld h ave h ard d isks, tap e d rives, CD-ROM d rives, a grap h ics scan n er, or oth er d evices (u p to seven or fifteen total) attach ed to a sin gle SCSI h ost ad ap ter. Most system s su p p ort u p to fou r h ost ad ap ters, each with u p to 15 d evices, for a total of 60 d evices! W h en you p u rch ase a SCSI d evice, you u su ally are p u rch asin g th e d evice, con troller, an d SCSI ad ap ter in on e circu it. Th is typ e of d rive u su ally is called an em bedded SCSI device; th e SCSI in terface is bu ilt in . For exam p le, m ost SCSI h ard d rives are tech n ically th e sam e

Small Computer System Interface (SCSI)

as th eir IDE cou n terp arts excep t for th e ad d ition of th e SCSI bu s ad ap ter circu its ad d ed . You d o n ot n eed to kn ow wh at typ e of con troller is in sid e th e SCSI d rive, becau se you r system can n ot talk d irectly to th e con troller as th ou gh it were p lu gged in to th e system bu s, like on a stan d ard IDE d rive. In stead , com m u n ication s go th rou gh th e SCSI h ost ad ap ter in stalled in th e system bu s. You can access th e d rive on ly with th e SCSI p rotocols. Ap p le origin ally rallied arou n d SCSI as bein g an in exp en sive way ou t of th e bin d in wh ich it p u t itself with th e Macin tosh . W h en th e en gin eers at Ap p le realized th e p roblem in m akin g th e Macin tosh a closed system (with n o slots), th ey d ecid ed th at th e easiest way to gain exp an d ability was to bu ild a SCSI p ort in to th e system , wh ich is h ow extern al p erip h erals can be ad d ed to th e slotless Macs. Becau se PC system s always h ave been exp an d able, th e p u sh toward SCSI h as n ot been as u rgen t. W ith u p to eigh t bu s slots su p p ortin g d ifferen t d evices an d con trollers in PC com p atible system s, it seem ed as th ou gh SCSI was n ot n eed ed as m u ch . SCSI h as sin ce becom e p op u lar in th e PC-based com p u ter world becau se of th e great exp an d ability th at it offers an d th e n u m ber of d evices th at are available with bu ilt-in SCSI. On e block th at stalled accep tan ce of SCSI in th e PC m arketp lace was th e lack of a real stan d ard ; th e SCSI stan d ard was d esign ed p rim arily by a com m ittee. No sin gle m an u factu rer h as led th e way, at least in th e PC aren a; each com p an y h as its own in terp retation of h ow SCSI sh ou ld be im p lem en ted , p articu larly at th e h ost-ad ap ter level. SCSI is a stan d ard , in m u ch th e sam e way th at RS-232 is a stan d ard . Th e SCSI stan d ard (like th e RS-232 stan d ard ), h owever, d efin es on ly th e h ard ware con n ection s, n ot th e d river sp ecification s req u ired to com m u n icate with th e d evices. Software ties th e SCSI su bsystem in to you r PC, bu t u n fortu n ately, m ost of th e d river p rogram s work on ly for a sp ecific d evice an d a sp ecific h ost ad ap ter. W ith a SCSI d river for m ost com m on ad ap ters an d d evices bu ilt in to W in d ows 95 an d 98, it is n ow m u ch easier to get m u ltip le SCSI d evices to work u sin g a sin gle ad ap ter.

Not e Some SCSI host adapters bundled with hardware such as graphics scanners or a “ bargain” SCSI CD-ROM drive, will not include all the features needed to support multiple SCSI devices or bootable SCSI hard drives. This has nothing to do with any limitations in the SCSI specification. The situation is simply that the manufacturer has included the most stripped-down version of a SCSI adapter available to save money. It has all the functionality needed to support the device it came with, but nothing else. Fortunately, with the right adapter and drivers, one card could do it all, most likely the one used for the hard disk as it would be the most full-featured of the bunch.

SCSI can be trou blesom e at tim es becau se of th e lack of a sin gle h ost-ad ap ter stan d ard , a software in terface stan d ard , an d stan d ard ROM BIOS su p p ort for h ard d isk d rives attach ed to th e SCSI bu s. Fortu n ately, som e sim p le recom m en d ation s can keep you from livin g th is com p atibility n igh tm are!

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In th e begin n in g, SCSI lacked th e cap ability to ru n h ard d isks off th e SCSI bu s. To boot from th ese d rives an d u se a variety of op eratin g system s was a p roblem th at resu lted from th e lack of an in terface stan d ard . Th e stan d ard IBM XT an d AT ROM BIOS software was d esign ed to talk to ST-506/ 412 h ard d isk con trollers. Th e software easily was m od ified to work with ESDI becau se ESDI con trollers are sim ilar to ST-506/ 412 con trollers at th e register level. (Th is sim ilarity at th e register level en abled m an u factu rers to easily d esign self-bootin g, ROM-BIOS-su p p orted ESDI d rives.) Th e sam e can be said of IDE, wh ich com p letely em u lates th e W D1003 ST-506/ 412 con troller in terface an d works p erfectly with th e existin g BIOS as well. SCSI is so d ifferen t from th ese oth er stan d ard d isk in terfaces th at a n ew set of ROM BIOS rou tin es are n ecessary to su p p ort th e system so it can self-boot. SCSI h ost ad ap ters are available with BIOS su p p ort on th e SCSI h ost ad ap ter. Becau se of th e lead taken by Ap p le in d evelop in g system s software (op eratin g system s an d ROM) su p p ort for SCSI, p erip h erals con n ect to Ap p le system s in fairly stan d ard ways. Un til recen tly, th is kin d of stan d ard -settin g lead ersh ip was lackin g for SCSI in th e PC world . Th is situ ation ch an ged d ram atically with W in d ows 95, wh ich in clu d ed d rivers for m ost stan d ard SCSI ad ap ters an d p erip h erals on th e m arket. Man y PC m an u factu rers h ave stan d ard ized SCSI for h igh -en d system s. In th ese system s, a SCSI h ost ad ap ter card is in on e of th e slots, or th e system h as a SCSI h ost ad ap ter bu ilt in to th e m oth erboard . Th is arran gem en t is sim ilar in ap p earan ce to th e IDE in terface, becau se a sin gle cable ru n s from th e m oth erboard to th e SCSI d rive. Alth ou gh , SCSI su p p orts as m an y as seven or fifteen ad d ition al d evices (som e of wh ich m ay n ot be h ard d isks), wh ereas IDE su p p orts on ly fou r d evices (two p er con troller). Ad d ition ally, SCSI su p p orts m ore typ es of d evices oth er th an h ard d isks th an IDE su p p orts wh ich IDE d evices m u st be eith er a h ard d isk, IDE-typ e CD-ROM d rive, or a tap e d rive, LS-120 su p erd isk d rive, Zip d rive, an d so on . System s with SCSI d rives are easy to u p grad e, becau se virtu ally an y th ird -p arty SCSI d rive will p lu g in an d fu n ction . ANSI SCSI St andards Th e SCSI stan d ard d efin es th e p h ysical an d electrical p aram eters of a p arallel I/ O bu s u sed to con n ect com p u ters an d p erip h eral d evices in d aisy-ch ain fash ion . Th e stan d ard su p p orts d evices su ch as d isk d rives, tap e d rives, an d CD-ROM d rives. Th e origin al SCSI stan d ard (ANSI X3.131-1986) was ap p roved in 1986, SCSI-2 was ap p roved in Jan u ary 1994, an d a n ew revision called SCSI-3 is still u n d er d evelop m en t. Th e SCSI in terface is d efin ed as a stan d ard by ANSI. Th e X3 Task Grou p op erates as an ASC (Accred ited Stan d ard s Com m ittee) u n d er ANSI to d evelop In form ation Processin g System stan d ard s. X3T9 is th e I/ O In terfaces grou p , an d X3T9.2 sp ecifically is in ch arge of low-level in terfaces su ch as SCSI an d ATA-IDE (am on g oth ers). Th e origin al SCSI-1 stan d ard was p u blish ed by th e X3T9 ANSI grou p in 1986, an d is officially p u blish ed by ANSI as X3.131-1986. On e p roblem with th e origin al SCSI-1 d ocu m en t was th at m an y of th e com m an d s an d featu res were op tion al, an d th ere was little or n o gu aran tee th at a p articu lar p erip h eral wou ld su p p ort th e exp ected com m an d s. Th is p roblem cau sed th e in d u stry as a wh ole to

Small Computer System Interface (SCSI)

d efin e a set of 18 basic SCSI com m an d s called th e Com m on Com m and Set (CCS), wh ich wou ld becom e th e m in im u m set of com m an d s su p p orted by all p erip h erals. CCS becam e th e basis for wh at is n ow th e SCSI-2 sp ecification . In ad d ition to form al su p p ort for CCS, SCSI-2 p rovid ed ad d ition al d efin ition s for com m an d s to access CD-ROM d rives (an d th eir sou n d cap abilities), tap e d rives, rem ovable d rives, op tical d rives, an d several oth er p erip h erals. In ad d ition , an op tion al h igh er sp eed called Fast SCSI-2 an d a 16-bit version called W id e SCSI-2 were d efin ed . An oth er featu re of SCSI-2 is com m and queuing, wh ich en ables a d evice to accep t m u ltip le com m an d s an d execu te th em in th e ord er th at th e d evice d eem s to be m ost efficien t. Th is featu re is m ost ben eficial wh en you are u sin g a m u ltitaskin g op eratin g system th at cou ld be sen d in g several req u ests on th e SCSI bu s at th e sam e tim e. Th e X3T9 grou p ap p roved th e SCSI-2 stan d ard as X3.131-1990 in Au gu st 1990, bu t th e d ocu m en t was recalled in Decem ber 1990 for ch an ges before fin al ANSI p u blication . Fin al ap p roval for th e SCSI-2 d ocu m en t was fin ally m ad e in Jan u ary 1994, alth ou gh it h as ch an ged little from th e origin al 1990 release. Th e SCSI-2 d ocu m en t is n ow called ANSI X3.131-1994. Th e official d ocu m en t is available from Global En gin eerin g Docu m en ts or th e ANSI com m ittee, wh ich are listed in Ap p en d ix A. You can also d own load workin g d rafts of th ese d ocu m en ts from th e NCR SCSI BBS, listed in Ap p en d ix A u n d er “NCR Microelectron ics.” Most com p an ies in d icate th at th eir h ost ad ap ters follow both th e ANSI X3.131-1986 (SCSI-1) as well as th e x3.131-1994 (SCSI-2) stan d ard s. Note th at becau se virtu ally all p arts of SCSI-1 are su p p orted in SCSI-2, virtu ally an y SCSI-1 d evice is also con sid ered SCSI-2 by d efau lt. Man y m an u factu rers ad vertise th at th eir d evices are SCSI-2, bu t th is d oes n ot m ean th at th ey su p p ort an y of th e ad d ition al op tion al featu res th at were in corp orated in th e SCSI-2 revision . For exam p le, an op tion al p art of th e SCSI-2 sp ecification in clu d es a fast syn ch ron ou s m od e th at d ou bles th e stan d ard syn ch ron ou s tran sfer rate from 5M/ sec to 10M/ sec. Th is Fast SCSI tran sfer m od e can be com bin ed with 16-bit W id e SCSI for tran sfer rates of u p to 20M/ sec. Th ere was an op tion al 32-bit version d efin ed in SCSI-2, bu t com p on en t m an u factu rers h ave sh u n n ed th is as too exp en sive. In essen ce, 32-bit SCSI was a stillborn sp ecification . Most SCSI im p lem en tation s are 8-bit stan d ard SCSI or Fast/ W id e SCSI. Even d evices wh ich su p p ort n on e of th e Fast or W id e m od es can still be con sid ered SCSI-2. Th e SCSI-3 stan d ard sh ou ld be ap p roved in ’98. Even before it was fu lly com p leted , p ortion s of th is sp ecification , alth ou gh n ot fin al, h ave been sold in p rod u cts. On e of th ese d evelop m en ts is th e Fast-20 m od e, wh ich is also called Ultra-SCSI. Th is essen tially is q u ad -sp eed SCSI, an d will ru n 20M/ sec on an 8-bit stan d ard SCSI bu s, an d 40M/ sec on W id e (16-bit) SCSI. Table 10.12 sh ows th e m axim u m tran sfer rates for th e SCSI bu s at variou s sp eed s an d wid th s, an d th e cable typ e req u ired for th e sp ecific tran sfer wid th s.

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Table 10.12

SCSI Dat a-Transfer Rat es

Bus W idt h

St andard SCSI

Fast SCSI

Fast -20 ( Ult ra)

Fast -40 ( Ult ra 2)

Cable Type

8-bit

5M / sec

10M / sec

20M / sec

40M / sec

A (50-pin)

16-bit (Wide)

10M / sec

20M / sec

40M / sec

80M / sec

P (68-pin)

Not e The A cable is the standard 50-pin SCSI cable, whereas the P cable is a 68-pin cable designed for 16-bit. M aximum cable length is 6m (about 20 feet) for standard speed SCSI, and only 3m (about 10 feet) for Fast/ Fast-20/ Fast-40 (Ultra) SCSI. Pinouts for these cable connections are listed in this chapter in Tables 10.13 through 10.17.

So-called SCSI-1 ad ap ters h ave n o p roblem s with SCSI-2 p erip h erals. In fact, as was stated earlier, virtu ally an y SCSI-1 d evice can also legitim ately be called SCSI-2 (or even SCSI-3). You can ’t take ad van tage of Fast, Fast-20, or W id e tran sfer cap abilities, bu t th e extra com m an d s d efin ed in SCSI-2 can be sen t by m ean s of a SCSI-1 con troller. In oth er word s, n oth in g is d ifferen t between SCSI-1- an d SCSI-2-com p lian t h ard ware. For exam p le, I am ru n n in g a Seagate Barracu d a 4G Fast SCSI-2 d rive with m y stan d ard IBM SCSI-1 h ost ad ap ter, an d it ru n s fin e. Most ad ap ters are sim ilar, in th at th ey actu ally are SCSI-2 com p atible, even if th ey ad vertise on ly SCSI-1 su p p ort. Becau se th e SCSI-2 stan d ard was n ot actu ally ap p roved before Jan u ary 1994, an y d evices th at claim ed to be SCSI-2 before th at tim e were n ot officially in com p lian ce with th e stan d ard . Th is is really n ot a p roblem , h owever, becau se th e SCSI-2 d ocu m en t h ad n ot ch an ged ap p reciably sin ce it was n early ap p roved in 1990. Th e sam e th in g is cu rren tly h ap p en in g with ad vertisers listin g d evices as “SCSI-3.” Th e SCSI-3 sp ecification is n ot yet ap p roved , alth ou gh certain areas are bein g worked ou t. Single-ended or Different ial SCSI “Norm al” SCSI also is called single-ended SCSI. For each sign al th at n eed s to be sen t across th e bu s, a wire exists to carry it. W ith d ifferen tial SCSI, for each sign al th at n eed s to be sen t across th e bu s, a p air of wires exists to carry it. Th e first in th is p air carries th e sam e typ e of sign al th at th e sin gle-en d ed SCSI carries. Th e secon d in th is p air, h owever, carries th e logical in version of th e sign al. Th e receivin g d evice takes th e d ifferen ce of th e p air (h en ce th e n am e differential), wh ich m akes it less su scep tible to n oise an d allows for greater cable len gth . Becau se of th is, d ifferen tial SCSI can be u sed with cable len gth s of u p to 25m , wh ereas sin gle-en d ed SCSI is good on ly for 6m with stan d ard asyn ch ron ou s or syn ch ron ou s tran sfers or for on ly 3m for Fast SCSI. You can n ot m ix sin gle-en d ed an d d ifferen tial d evices on a sin gle SCSI bu s; th e resu lt wou ld be catastrop h ic. (Th at is to say, you p robably will see sm oke!) Notice th at th e cables an d con n ectors are th e sam e, so it’s en tirely p ossible to m ake th is m istake. Th is u su ally is n ot a p roblem , h owever, becau se very few d ifferen tial SCSI im p lem en tation s exist. Esp ecially with SCSI in th e PC en viron m en t, sin gle-en d ed is abou t all you will ever

Small Computer System Interface (SCSI)

see. If, h owever, you com e u p on a p erip h eral th at you believe m igh t be d ifferen tial, th ere are a few ways to tell. On e way is to look for a sp ecial sym bol on th e u n it; th e in d u stry h as ad op ted d ifferen t u n iversal sym bols for sin gle-en d ed an d d ifferen tial SCSI. Figu re 10.6 sh ows th ese sym bols.

SCSI

SE

Single-ended SCSI

SCSI

DIFF

Differential SCSI

FIG. 10.6 Sin gle-en d ed an d d ifferen tial SCSI u n iversal sym bols. If you d o n ot see su ch sym bols, you can tell wh eth er you h ave a d ifferen tial d evice by u sin g an oh m m eter to ch eck th e resistan ce between p in s 21 an d 22 on th e d evice con n ector. On a sin gle-en d ed system , th e p in s sh ou ld be tied togeth er an d also tied to th e grou n d . On a d ifferen tial d evice, th e p in s sh ou ld be op en or h ave sign ifican t resistan ce between th em . Again , th is gen erally sh ou ld n ot be a p roblem , becau se virtu ally all d evices u sed in th e PC en viron m en t are sin gle-en d ed . SCSI-1 and SCSI-2 Th e SCSI-2 sp ecification essen tially is an im p roved version of SCSI-1 with som e p arts of th e sp ecification tigh ten ed an d with several n ew featu res an d op tion s ad d ed . Norm ally, SCSI-1 an d SCSI-2 d evices are com p atible, bu t SCSI-1 d evices ign ore th e ad d ition al featu res in SCSI-2. Som e of th e ch an ges in SCSI-2 are very m in or. For exam p le, SCSI-1 allowed SCSI Bu s p arity to be op tion al, wh ereas p arity m u st be im p lem en ted in SCSI-2. An oth er req u irem en t is th at in itiator d evices, su ch as h ost ad ap ters, p rovid e term in ator p ower to th e in terface; m ost d evices alread y d id so. SCSI-2 also h as several op tion al featu res: ■ Fast SCSI ■ W id e SCSI ■ Com m an d q u eu in g

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■ High -d en sity cable con n ectors ■ Im p roved Active (Altern ative 2) term in ation Th ese featu res are n ot req u ired ; th ey are op tion al u n d er th e SCSI-2 sp ecification . If you con n ect a stan d ard SCSI h ost ad ap ter to a Fast SCSI d rive, for exam p le, th e in terface will work, bu t on ly at stan d ard SCSI sp eed s. SCSI-3. SCSI-3 is a term u sed to d escribe a set of stan d ard s cu rren tly bein g d evelop ed . Sim p ly p u t, it is th e n ext gen eration of d ocu m en ts a p rod u ct con form s to. See th e section “New Com m an d s” later in th is ch ap ter. Fast and Fast -W ide SCSI. Fast SCSI refers to h igh -sp eed syn ch ron ou s tran sfer cap ability. Fast SCSI ach ieves a 10M/ sec tran sfer rate on th e stan d ard 8-bit SCSI cablin g. W h en com bin ed with a 16-bit W id e SCSI in terface, th is con figu ration resu lts in d ata-tran sfer rates of 20M/ sec (called Fast/W ide). Fast -20 ( Ult ra) SCSI. Fast-20 or Ultra SCSI refers to h igh -sp eed syn ch ron ou s tran sfer cap ability th at is twice as fast as Fast-SCSI. Th is h as been in trod u ced in th e Draft (u n fin ish ed ) SCSI-3 sp ecification an d h as alread y been ad op ted by th e m arketp lace, esp ecially for h igh -sp eed h ard d isks. Ultra SCSI ach ieves a 20M/ sec tran sfer rate on th e stan d ard 8-bit SCSI cablin g. W h en com bin ed with a 16-bit W id e SCSI in terface, th is con figu ration resu lts in d ata-tran sfer rates of 40M/ sec (called Ultra/W ide). Fast -40 SCSI. Fast-40 SCSI is a fu tu re revision of SCSI-3 (m en tion ed earlier in th e ch ap ter) cap able of ach ievin g a 40M/ sec tran sfer rate. W ide SCSI. W ide SCSI allows for p arallel d ata tran sfer at a bu s wid th of 16 bits. Th e wid er con n ection req u ires a n ew cable d esign . Th e stan d ard 50-con d u ctor 8-bit cable is called th e A cable. SCSI-2 origin ally d efin ed a sp ecial 68-con d u ctor B cable th at was su p p osed to be u sed in con ju n ction with th e A cable for wid e tran sfers, bu t th e in d u stry ign ored th is sp ecification in favor of a n ewer 68-con d u ctor P cable th at was in trod u ced as p art of th e SCSI-3 sp ecification . Th e P cable su p ersed ed th e A an d B cable com bin ation becau se th e P cable can be u sed alon e (with ou t th e A cable) for 16-bit W id e SCSI. A 32-bit W id e SCSI version was origin ally d efin ed on p ap er as a p art of th e SCSI-2 sp ecification , bu t h as n ot fou n d p op u larity an d p robably n ever will in th e PC en viron m en t. Th eoretically, 32-bit SCSI im p lem en tation s wou ld req u ire two cables: a 68-con d u ctor P cable an d a 68-con d u ctor Q cable. Fiber Channel SCSI. Fiber Ch an n el SCSI is a sp ecification for a serial in terface u sin g a fiber ch an n el p h ysical an d p rotocol ch aracteristic, with SCSI com m an d set. It can ach ieve 100M/ sec over eith er fiber or coaxial cable. Term inat ion. Th e sin gle-en d ed SCSI bu s d ep en d s on very tigh t term in ation toleran ces to fu n ction reliably. Un fortu n ately, th e origin al 132-oh m p assive term in ation d efin ed in th e SCSI-1 d ocu m en t was n ot d esign ed for u se at th e h igh er syn ch ron ou s sp eed s n ow p ossible. Th ese p assive term in ators can cau se sign al reflection s to gen erate errors wh en tran sfer rates in crease or wh en m ore d evices are ad d ed to th e bu s. SCSI-2 d efin es an

Small Computer System Interface (SCSI)

active (voltage-regu lated ) term in ator th at lowers term in ation im p ed an ce to 110 oh m s an d im p roves system in tegrity. Com m and Queuing. In SCSI-1, an in itiator d evice, su ch as a h ost ad ap ter, was lim ited to sen d in g on e com m an d p er d evice. In SCSI-2, th e h ost ad ap ter can sen d as m an y as 256 com m an d s to a sin gle d evice, wh ich will store an d p rocess th ose com m an d s in tern ally before resp on d in g on th e SCSI bu s. Th e target d evice even can reseq u en ce th e com m an d s to allow for th e m ost efficien t execu tion or p erform an ce p ossible. Th is featu re is esp ecially u sefu l in m u ltitaskin g en viron m en ts, su ch as OS/ 2 an d W in d ows NT, wh ich can take ad van tage of th is featu re. New Com m ands. SCSI-2 took th e Com m on Com m an d Set th at was bein g u sed th rou gh ou t th e in d u stry an d m ad e it an official p art of th e stan d ard . Th e CCS was d esign ed m ain ly for d isk d rives an d d id n ot in clu d e sp ecific com m an d s d esign ed for oth er typ es of d evices. In SCSI-2, m an y of th e old com m an d s are reworked , an d several n ew com m an d s h ave been ad d ed . New com m an d sets h ave been ad d ed for CD-ROMs, op tical d rives, scan n ers, com m u n ication s d evices, an d m ed ia ch an gers (ju keboxes). SCSI-3 Even th ou gh th e SCSI-2 sp ecification h as on ly recen tly been ap p roved (alth ou gh it h as rem ain ed stable for som e tim e), th e SCSI-3 sp ecification is alread y bein g d evelop ed . SCSI-3 will h ave everyth in g th at SCSI-2 h as an d d efin itely will ad d n ew com m an d s, featu res, an d im p lem en tation s. For exam p le, SCSI-3 will p rovid e su p p ort for u p to 32 d evices on th e bu s in stead of on ly eigh t. On e of th e m ost excitin g th in gs abou t SCSI-3 is th e p rop osed Serial SCSI, a sch em e th at m ay u se on ly a six-con d u ctor cable an d th at will be able to tran sfer d ata at u p to 100M/ sec! Th e switch to serial in stead of p arallel is d esign ed to con trol th e d elay, n oise, an d term in ation p roblem s th at h ave p lagu ed SCSI-2, as well as to sim p lify th e cable con n ection . Serial SCSI will be cap able of tran sferrin g m ore d ata over six wires th an 32-bit Fast W id e SCSI-2 can over 128 wires! Th e in ten tion is th at Serial SCSI be im p lem en ted on th e m oth erboard of fu tu re system s, givin g th em in cred ible exp an sion an d p erform an ce cap abilities. Alth ou gh Serial SCSI m ay n ot m ake th e old er h ost ad ap ters an d cables obsolete overn igh t, it d oes m ake fu tu re cablin g p ossibilities even m ore of a p u zzle. Serial SCSI offers th e p ossibility of lon ger cable len gth s, less electrom agn etic in terferen ce, an d easier con n ection s on lap top s, n otebooks, an d d ockin g station s. Exp ect SCSI-3 to offer alm ost p ain -free in stallation s with au tom atic Pn P SCSI ID setu p an d term in ation sch em es. In an y p ractical sen se, SCSI-3 is still a bit away from bein g ap p roved . Becau se th e stan d ard exists in d raft d ocu m en ts before bein g officially ap p roved , if th e p ortion s of th e stan d ard becom e stable, we m ay very well see p rod u cts claim in g SCSI-3 com p atibility well before th e stan d ard tru ly exists. Becau se SCSI-3 actu ally in corp orates all of wh at is in SCSI-2, tech n ically an ybod y can call an y SCSI-1 or SCSI-2 d evice a SCSI-3 d evice as well. Beware of p rod u ct h yp e alon g th ese lin es. Som e of th e n ew SCSI-3 featu res will likely be in com p atible with p reviou s SCSI im p lem en tation s, an d m ay take a wh ile to ap p ear on th e m arket.

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SCSI Cables and Connect ors Th e SCSI stan d ard s are very sp ecific wh en it com es to cables an d con n ectors. Th e m ost com m on con n ectors sp ecified in th is stan d ard are th e 50-p osition u n sh ield ed p in h ead er con n ector for in tern al SCSI con n ection s an d th e 50-p osition sh ield ed Cen tron ics latch style con n ectors for extern al con n ection s. Th e sh ield ed Cen tron ics style con n ector also is called Alternative 2 in th e official sp ecification . Passive or Active term in ation (Active is p referred ) is sp ecified for both sin gle-en d ed an d d ifferen tial bu ses. Th e 50-con d u ctor bu s con figu ration is d efin ed in th e SCSI-2 stan d ard as th e A-cabled . Th e SCSI-2 revision ad d ed a h igh -d en sity, 50-p osition , D-sh ell con n ector op tion for th e A-cable con n ectors. Th is con n ector n ow is called Alternative 1. Th e Altern ative 2 Cen tron ics latch -style con n ector rem ain s u n ch an ged from SCSI-1. A 68-con d u ctor B-cable sp ecification was ad d ed to th e SCSI-2 stan d ard to p rovid e for 16- an d 32-bit d ata tran sfers; th e con n ector, h owever, h ad to be u sed in p arallel with an A cable. Th e in d u stry d id n ot wid ely accep t th e B-cable op tion , wh ich h as been d rop p ed from th e SCSI-3 stan d ard . To rep lace th e ill-fated B cable, a n ew 68-con d u ctor P cable was d evelop ed as p art of th e SCSI-3 sp ecification . Sh ield ed an d u n sh ield ed h igh -d en sity D-sh ell con n ectors are sp ecified for both th e A cable an d P cable. Th e sh ield ed h igh -d en sity con n ectors u se a sq u eeze-to-release latch rath er th an th e wire latch u sed on th e Cen tron ics-style con n ectors. Active term in ation for sin gle-en d ed bu ses is sp ecified , p rovid in g a h igh level of sign al in tegrity. SCSI Cable and Connect or Pinout s Th e followin g section d etails th e p in ou ts of th e variou s SCSI cables an d con n ectors. Th ere are two electrically d ifferen t version s of SCSI, Single-ended an d Differential. Th ese two version s are electrically in com p atible, an d m u st n ot be in tercon n ected or d am age will resu lt. Fortu n ately, th ere are very few Differen tial SCSI ap p lication s available in th e PC in d u stry, so you will rarely (if ever) en cou n ter it. W ith in each electrical typ e (Sin gleen d ed or Differen tial), th ere are basically th ree SCSI cable typ es: ■ A Cable (Stan d ard SCSI) ■ P Cable (16- an d 32-bit W id e SCSI) ■ Q Cable (32-bit W id e SCSI) Th e A cable is u sed in m ost SCSI-1 an d SCSI-2 in stallation s, an d is th e m ost com m on cable you will en cou n ter. SCSI-2 W id e (16-bit) ap p lication s u se a P cable in stead , wh ich com p letely rep laces th e A cable. You can in term ix stan d ard an d W id e SCSI d evices on a sin gle SCSI bu s by in tercon n ectin g A an d P cables with sp ecial ad ap ters. 32-bit wid e SCSI-3 ap p lication s u se both th e P an d Q cables in p arallel to each 32-bit d evice. Tod ay th ere are virtu ally n o PC ap p lication s for 32-bit W id e SCSI-3, an d becau se of th e twocable req u irem en t, it is n ot likely to catch on .

Small Computer System Interface (SCSI)

Th e A cables can h ave Pin Head er (In tern al) typ e con n ectors or Extern al Sh ield ed con n ectors, each with a d ifferen t p in ou t. Th e P an d Q cables featu re th e sam e con n ector p in ou t on eith er In tern al or Extern al cable con n ection s. Single-Ended SCSI Cables and Connect ors. Th e sin gle-en d ed electrical in terface is th e m ost p op u lar typ e for PC system s. Tables 10.13 an d 10.14 sh ow all th e p ossible sin gleen d ed cable an d con n ector p in ou ts. Th e A cable is available in both in tern al u n sh ield ed an d extern al sh ield ed con figu ration s. A h yp h en p reced in g a sign al n am e in d icates th e sign al is Active Low. Th e RESERVED lin es h ave con tin u ity from on e en d of th e SCSI bu s to th e oth er. In an A cable bu s, th e RESERVED lin es sh ou ld be left op en in SCSI d evices (bu t m ay be con n ected to grou n d ), an d are con n ected to grou n d in th e bu s term in ator assem blies. In th e P an d Q cables, th e RESERVED lin es are left op en in SCSI d evices an d in th e bu s term in ator assem blies. Table 10.13

A-Cable ( Single-Ended) Int ernal Unshielded Header Connect or

Signal Nam e

Pin

Pin

Signal Nam e

GROUND

1

2

–DB(0)

GROUND

3

4

–DB(1)

GROUND

5

6

–DB(2)

GROUND

7

8

–DB(3)

GROUND

9

10

–DB(4)

GROUND

11

12

–DB(5)

GROUND

13

14

–DB(6)

GROUND

15

16

–DB(7)

GROUND

17

18

–DB(Parity)

GROUND

19

20

GROUND

GROUND

21

22

GROUND

RESERVED

23

24

RESERVED

Open

25

26

TERM PWR

RESERVED

27

28

RESERVED

GROUND

29

30

GROUND

GROUND

31

32

–ATN

GROUND

33

34

GROUND

GROUND

35

36

–BSY

GROUND

37

38

–ACK

GROUND

39

40

–RST

GROUND

41

42

–M SG

GROUND

43

44

–SEL

GROUND

45

46

–C/ D

GROUND

47

48

–REQ

GROUND

49

50

–I/ O

635

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Chapter 10—I/ O Interfaces

Table 10.14

A-Cable ( Single-Ended) Ext ernal Shielded Connect or

Signal Nam e

Pin

Pin

Signal Nam e

GROUND

1

26

–DB(0)

GROUND

2

27

–DB(1)

GROUND

3

28

–DB(2)

GROUND

4

29

–DB(3)

GROUND

5

30

–DB(4)

GROUND

6

31

–DB(5)

GROUND

7

32

–DB(6)

GROUND

8

33

–DB(7)

GROUND

9

34

–DB(Parity)

GROUND

10

35

GROUND

GROUND

11

36

GROUND

RESERVED

12

37

RESERVED

Open

13

38

TERM PWR

RESERVED

14

39

RESERVED

GROUND

15

40

GROUND

GROUND

16

41

–ATN

GROUND

17

42

GROUND

GROUND

18

43

–BSY

GROUND

19

44

–ACK

GROUND

20

45

–RST

GROUND

21

46

–M SG

GROUND

22

47

–SEL

GROUND

23

48

–C/ D

GROUND

24

49

–REQ

GROUND

25

50

–I/ O

IBM u sed th e SCSI in terface in virtu ally all PS/ 2 system s in trod u ced after 1990. Th ese system s u se a Micro-Ch an n el SCSI ad ap ter or h ave th e SCSI Host Ad ap ter bu ilt in to th e m oth erboard . In eith er case, IBM’s SCSI in terface u ses a sp ecial 60-p in m in i-Cen tron ics typ e extern al sh ield ed con n ector th at is u n iq u e in th e in d u stry. A sp ecial IBM cable is req u ired to ad ap t th is con n ector to th e stan d ard 50-p in Cen tron ics style con n ector u sed on m ost extern al SCSI d evices. Th e p in ou t of th e IBM 60-p in m in i-Cen tron ics style Extern al Sh ield ed con n ector is sh own in Table 10.15. Notice th at alth ou gh th e p in arran gem en t is u n iq u e, th e p in -n u m ber-to-sign al d esign ation s corresp on d with th e stan d ard u n sh ield ed in tern al p in h ead er typ e of SCSI con n ector. Table 10.15

IBM PS/ 2 SCSI Ext ernal Shielded 60-Pin Connect or

Signal Nam e

Pin

Pin

Signal Nam e

GROUND

1

60

Not Connected

–DB(0)

2

59

Not Connected

Small Computer System Interface (SCSI)

Signal Nam e

Pin

Pin

Signal Nam e

GROUND

3

58

Not Connected

–DB(1)

4

57

Not Connected

GROUND

5

56

Not Connected

–DB(2)

6

55

Not Connected

GROUND

7

54

Not Connected

–DB(3)

8

53

Not Connected

GROUND

9

52

Not Connected

–DB(4)

10

51

GROUND

GROUND

11

50

–I/ O

–DB(5)

12

49

GROUND

GROUND

13

48

–REQ

–DB(6)

14

47

GROUND

GROUND

15

46

–C/ D

–DB(7)

16

45

GROUND

GROUND

17

44

–SEL

–DB(Parity)

18

43

GROUND

GROUND

19

42

–M SG

GROUND

20

41

GROUND

GROUND

21

40

–RST

GROUND

22

39

GROUND

RESERVED

23

38

–ACK

RESERVED

24

37

GROUND

Open

25

36

–BSY

TERM PWR

26

35

GROUND

RESERVED

27

34

GROUND

RESERVED

28

33

GROUND

GROUND

29

32

–ATN

GROUND

30

31

GROUND

Th e P cable (Sin gle-en d ed ) an d con n ectors are u sed in 16-bit wid e SCSI-2 ap p lication s (see Table 10.16 for th e p in ou t). Table 10.16 Connect or

P Cable ( Single-ended) Int ernal or Ext ernal Shielded

Signal Nam e

Pin

Pin

Signal Nam e

GROUND

1

35

–DB(12)

GROUND

2

36

–DB(13)

GROUND

3

37

–DB(14)

GROUND

4

38

–DB(15) (continues)

637

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Chapter 10—I/ O Interfaces

Table 10.16 P Cable ( Single-ended) Int ernal or Ext ernal Shielded Connect or Cont inued Signal Nam e

Pin

Pin

Signal Nam e

GROUND

5

39

–DB(Parity 1)

GROUND

6

40

–DB(0)

GROUND

7

41

–DB(1)

GROUND

8

42

–DB(2)

GROUND

9

43

–DB(3)

GROUND

10

44

–DB(4)

GROUND

11

45

–DB(5)

GROUND

12

46

–DB(6)

GROUND

13

47

–DB(7)

GROUND

14

48

–DB(Parity 0)

GROUND

15

49

GROUND

GROUND

16

50

GROUND

TERM PWR

17

51

TERM PWR

TERM PWR

18

52

TERM PWR

RESERVED

19

53

RESERVED

GROUND

20

54

GROUND

GROUND

21

55

–ATN

GROUND

22

56

GROUND

GROUND

23

57

–BSY

GROUND

24

58

–ACK

GROUND

25

59

–RST

GROUND

26

60

–M SG

GROUND

27

61

–SEL

GROUND

28

62

–C/ D

GROUND

29

63

–REQ

GROUND

30

64

–I/ O

GROUND

31

65

–DB(8)

GROUND

32

66

–DB(9)

GROUND

33

67

–DB(10)

GROUND

34

68

–DB(11)

Th e Q Cable (Sin gle-en d ed ) an d con n ector is d efin ed on ly for 32-bit SCSI im p lem en tation s, wh ich also req u ire a P cable as well (see Table 10.17 for th e p in ou t). 32-bit SCSI ap p lication s are virtu ally n on existen t. Table 10.17

Q Cable ( Single-Ended) Int ernal or Ext ernal Shielded Connect or

Signal Nam e

Pin

Pin

Signal Nam e

GROUND

1

35

–DB(28)

GROUND

2

36

–DB(29)

Small Computer System Interface (SCSI)

Signal Nam e

Pin

Pin

Signal Nam e

GROUND

3

37

–DB(30)

GROUND

4

38

–DB(31)

GROUND

5

39

–DB(Parity 3)

GROUND

6

40

–DB(16)

GROUND

7

41

–DB(17)

GROUND

8

42

–DB(18)

GROUND

9

43

–DB(19)

GROUND

10

44

–DB(20)

GROUND

11

45

–DB(21)

GROUND

12

46

–DB(22)

GROUND

13

47

–DB(23)

GROUND

14

48

–DB(Parity 2)

GROUND

15

49

GROUND

GROUND

16

50

GROUND

TERM PWRQ

17

51

TERM PWRQ

TERM PWRQ

18

52

TERM PWRQ

RESERVED

19

53

RESERVED

GROUND

20

54

GROUND

GROUND

21

55

TERM INATED

GROUND

22

56

GROUND

GROUND

23

57

TERM INATED

GROUND

24

58

–ACKQ

GROUND

25

59

TERM INATED

GROUND

26

60

TERM INATED

GROUND

27

61

TERM INATED

GROUND

28

62

TERM INATED

GROUND

29

63

–REQQ

GROUND

30

64

TERM INATED

GROUND

31

65

–DB(24)

GROUND

32

66

–DB(25)

GROUND

33

67

–DB(26)

GROUND

34

68

–DB(27)

Different ial SCSI Signals. Differen tial SCSI is n ot n orm ally u sed in a PC en viron m en t, bu t is very p op u lar with m in icom p u ter in stallation s d u e to th e very lon g bu s len gth s th at are allowed . Term inat ion. All bu ses n eed to be electrically term in ated at each en d ; th e SCSI bu s is n o excep tion . Im p rop er term in ation still is on e of th e m ost com m on p roblem s in SCSI in stallation s. Th ree typ es of term in ators typ ically are available for th e SCSI bu s:

639

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Chapter 10—I/ O Interfaces

■ Passive ■ Active (also called Altern ative 2) ■ Forced Perfect Term in ation (FPT): FPT-3, FPT-18, an d FPT-27 Typ ical p assive term in ators (a n etwork of resistors) allow sign al flu ctu ation s in relation to th e term in ator p ower sign al on th e bu s. Usu ally, p assive term in atin g resistors su ffice over sh ort d istan ces, su ch as two or th ree feet, bu t for lon ger d istan ces, active term in ation is a real ad van tage. Active term in ation is req u ired with Fast SCSI. An active term in ator actu ally h as on e or m ore voltage regu lators to p rod u ce th e term in ation voltage, rath er th an resistor voltage d ivid ers. Th is arran gem en t h elp s en su re th at th e SCSI sign als always are term in ated to th e correct voltage level. Active term in ators will u su ally h ave som e sort of LED in d icatin g th e term in ation activity. Th e SCSI-2 sp ecification recom m en d s active term in ation on both en d s of th e bu s an d req u ires active term in ation wh en ever Fast or W id e SCSI d evices are u sed . Most h igh -p erform an ce h ost ad ap ters h ave an “au to-term in ation ” featu re so if it is th e en d of a ch ain , it will term in ate itself. A variation on active term in ation is available: Forced Perfect Term in ation . Forced Perfect Term ination is an even better form of active term in ation , in wh ich d iod e clam p s are ad d ed to elim in ate sign al oversh oot an d u n d ersh oot. Th e trick is th at in stead of clam p in g to +5 an d Grou n d , th ese term in ators clam p to th e ou tp u t of two regu lated voltages. Th is arran gem en t en ables th e clam p in g d iod es to elim in ate sign al oversh oot an d u n d ersh oot, esp ecially at h igh er sign alin g sp eed s an d over lon ger d istan ces. FPT term in ators are available in several version s. FPT-3 an d FPT-18 version s are available for 8-bit stan d ard SCSI, wh ile th e FPT-27 is available for 16-bit (W id e) SCSI. Th e FPT-3 version forces p erfect th e th ree m ost h igh ly active SCSI sign als on th e 8-bit SCSI bu s, wh ile th e FPT-18 forces p erfect all th e SCSI sign als on th e 8-bit bu s excep t grou n d s. FPT-27 also forces p erfect all th e 16-bit W id e SCSI sign als excep t grou n d s.

Not e Several companies make high-quality terminators for the SCSI bus, including Aeronics and the Data M ate division of M ethode. Both of these companies make a variety of terminators, but Aeronics is well-noted for some unique FPT versions that are especially suited to problem configurations that require longer cable runs or higher signal integrity. One of the best investments that you can make in any SCSI installation is in high-quality cables and terminators. Contact information for both of these companies is listed in Appendix A.

SCSI Drive Configurat ion SCSI d rives are n ot too d ifficu lt to con figu re, bu t th ey are m ore com p licated th an IDE d rives. Th e SCSI stan d ard con trols th e way th at th e d rives m u st be set u p . You n eed to set two or th ree item s wh en you con figu re an SCSI d rive: ■ SCSI ID settin g (0–7 or 0–15) ■ Term in atin g resistors

Small Computer System Interface (SCSI)

Th e SCSI ID settin g is very sim p le. Up to eigh t SCSI d evices can be u sed on a sin gle n arrow SCSI bu s or u p to fifteen d evices on a wid e SCSI bu s, an d each d evice m u st h ave a u n iq u e SCSI ID ad d ress. Th e h ost ad ap ter takes on e ad d ress, so th e rest are free for u p to seven SCSI p erip h erals. Most SCSI h ost ad ap ters are factory-set to ID 7 or 15, wh ich is th e h igh est-p riority ID. All oth er d evices m u st h ave u n iq u e IDs th at d o n ot con flict with on e an oth er. Som e h ost ad ap ters boot on ly from a h ard d isk set to a sp ecific ID. Old er Ad ap tec h ost ad ap ters req u ired th e boot h ard d isk to be ID 0; n ewer on es can boot from an y ID. Settin g th e ID u su ally in volves ch an gin g ju m p ers on th e d rive. If th e d rive is in stalled in an extern al ch assis, th e ch assis m ay h ave an ID selector switch th at is accessible at th e rear. Th is selector m akes ID selection a sim p le m atter of p ressin g a bu tton or rotatin g a wh eel u n til th e d esired ID n u m ber ap p ears. If n o extern al selector is p resen t, you m u st op en th e extern al d evice ch assis an d set th e ID via th e ju m p ers on th e d rive. Th ree ju m p ers are req u ired to set th e SCSI ID; th e p articu lar ID selected actu ally is d erived from th e bin ary rep resen tation of th e ju m p ers th em selves. For exam p le, settin g all th ree ID ju m p ers off resu lts in a bin ary n u m ber of 000b, wh ich tran slates to an ID of 0. A bin ary settin g of 001b eq u als ID 1, 010b eq u als 2, 011b eq u als 3, an d so on . (Notice th at as I list th ese valu es, I ap p en d a lowercase b to in d icate bin ary n u m bers.) Un fortu n ately, th e ju m p ers can ap p ear eith er forward or backward on th e d rive, d ep en d in g on h ow th e m an u factu rer set th em u p . To keep th in gs sim p le, I h ave record ed all th e d ifferen t ID ju m p er settin gs in th e followin g tables. Table 10.18 sh ows th e settin gs for d rives th at ord er th e ju m p ers with th e Most Sign ifican t Bit (MSB) to th e left; Table 10.19 sh ows th e settin gs for d rives th at h ave th e ju m p ers ord ered so th at th e MSB is to th e righ t. Table 10.18

SCSI ID Jumper Set t ings wit h t he M ost Significant Bit t o t he Left

SCSI

ID

Jum per

Set t ings

0

0

0

0

1

0

0

1

2

0

1

0

3

0

1

1

4

1

0

0

5

1

0

1

6

1

1

0

7

1

1

1

1 = Jum per On, 0 = Jum per Off

641

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Chapter 10—I/ O Interfaces

Table 10.19

SCSI ID Jumper Set t ings wit h t he M ost Significant Bit t o t he Right

SCSI

ID

Jum per

Set t ings

0

0

0

0

1

1

0

0

2

0

1

0

3

1

1

0

4

0

0

1

5

1

0

1

6

0

1

1

7

1

1

1

1 = Jum per On, 0 = Jum per Off

SCSI term in ation is very sim p le. Term in ation is req u ired at both en d s of th e bu s; th ere are n o excep tion s. If th e h ost ad ap ter is at on e en d of th e bu s, it m u st h ave term in ation en abled . If th e h ost ad ap ter is in th e m id d le of th e bu s, an d if both in tern al an d extern al bu s lin ks are p resen t, th e h ost ad ap ter m u st h ave its term in ation d isabled , an d th e d evices at each en d of th e bu s m u st h ave term in ators in stalled . Un fortu n ately, th e m ajority of p roblem s th at I see with SCSI in stallation s are th e resu lt of im p rop er term in ation . W h en in stallin g an extern al SCSI d evice, you will u su ally fin d th e d evice in a storage en closu re with both in p u t an d ou tp u t SCSI con n ectors, so th at you can u se th e d evice in a d aisy ch ain . If th e en closu re is at th e en d of th e SCSI bu s, an extern al term in ator m od u le m ost likely will h ave to be p lu gged in to th e secon d (ou tgoin g) SCSI p ort to p rovid e p rop er term in ation at th at en d of th e bu s (see Figu re 10.7).

FIG. 10.7 Extern al SCSI d evice term in ator. Extern al term in ator m od u les are available in a variety of con n ector con figu ration s, in clu d in g p ass-th rou gh d esign s, wh ich are n eed ed if on ly on e p ort is available. Passth rou gh term in ators also are com m on ly u sed in in tern al in stallation s in wh ich th e d evice d oes n ot h ave bu ilt-in term in atin g resistors. Man y h ard d rives u se p ass-th rou gh term in ators for in tern al in stallation s to save sp ace on th e logic-board assem bly (see Figu re 10.8).

Small Computer System Interface (SCSI)

FIG. 10.8 In tern al p in -h ead er con n ector p ass-th rou gh SCSI term in ator. Th e p ass-th rou gh m od els are req u ired wh en a d evice is at th e en d of th e bu s an d on ly on e SCSI con n ector is available. Oth er con figu ration item s on a SCSI d rive can be set via ju m p ers. Followin g are several of th e m ost com m on ad d ition al settin gs th at you will fin d : ■ Start on Com m an d (d elayed start) ■ SCSI Parity ■ Term in ator Power ■ Syn ch ron ou s Negotiation Th ese con figu ration item s are d escribed in th e followin g section s. St art On Com m and ( Delayed St art ) . If you h ave m u ltip le d rives in stalled in a system , it is wise to set th em u p so th at all th e d rives d o n ot start to sp in im m ed iately wh en th e system is p owered on . A h ard d isk d rive can con su m e th ree or fou r tim es m ore p ower d u rin g th e first few secon d s after p ower-on th an d u rin g n orm al op eration . Th e m otor req u ires th is ad d ition al p ower to get th e p latters sp in n in g q u ickly. If several d rives are d rawin g all th is p ower at th e sam e tim e, th e p ower su p p ly m ay be overload ed , wh ich can cau se th e system to h an g or to h ave in term itten t startu p p roblem s. Nearly all SCSI d rives p rovid e a way to d elay d rive sp in n in g so th at th is p roblem d oes n ot occu r. W h en m ost SCSI h ost ad ap ters in itialize th e SCSI bu s, th ey sen d ou t a com m an d called Start Unit to each of th e ID ad d resses in su ccession . By settin g a ju m p er on th e h ard d isk, you can p reven t th e d isk from sp in n in g u n til it receives th e Start Unit com m an d from th e h ost ad ap ter. Becau se th e h ost ad ap ter sen d s th is com m an d to all th e ID ad d resses in su ccession , from th e h igh est-p riority ad d ress (ID 7) to th e lowest (ID 0), th e h igh er-p riority d rives can be m ad e to start first, with each lower-p riority d rive sp in n in g u p seq u en tially. Becau se som e h ost ad ap ters d o n ot sen d th e Start Unit com m an d , som e d rives m ay sim p ly d elay sp in u p for a fixed n u m ber of secon d s rath er th an wait for a com m an d th at n ever will arrive. If d rives are in stalled in extern al ch assis with sep arate p ower su p p lies, you n eed n ot im p lem en t th e d elayed -start fu n ction . Th is fu n ction is best ap p lied to in tern al d rives th at m u st be ru n from th e sam e p ower su p p ly th at ru n s th e system . For in tern al

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in stallation s, I recom m en d settin g Start on Com m an d (d elayed start) even if you h ave on ly on e SCSI d rive; th is settin g will ease th e load on th e p ower su p p ly by sp in n in g th e d rive u p after th e rest of th e system h as fu ll p ower. Th is m eth od is esp ecially good for p ortable system s an d oth er system s in wh ich th e p ower su p p ly is lim ited . SCSI Parit y. SCSI Parity is a lim ited form of error ch eckin g th at h elp s en su re th at all d ata tran sfers are reliable. Virtu ally all h ost ad ap ters su p p ort SCSI p arity ch eckin g, so th is op tion sh ou ld be en abled on every d evice. Th e on ly reason wh y it exists as an op tion is th at som e old er h ost ad ap ters d o n ot work with SCSI p arity, so th e p arity m u st be tu rn ed off. Term inat or Pow er. Th e term in ators at each en d of th e SCSI bu s req u ire p ower from at least on e d evice on th e bu s. In m ost cases, th e h ost ad ap ter su p p lies th is term in ator p ower; in som e cases, h owever, it d oes n ot. For exam p le, p arallel p ort SCSI h ost ad ap ters typ ically d o n ot su p p ly term in ator p ower. It is n ot a p roblem if m ore th an on e d evice su p p lies term in ator p ower becau se each sou rce is d iod e-p rotected . For sim p licity’s sake, m an y will con figu re all d evices to su p p ly term in ator p ower. If n o d evice su p p lies term in ator p ower, th e bu s will n ot be term in ated correctly an d will n ot fu n ction p rop erly. SCSI Synchronous Negot iat ion. Th e SCSI bu s can ru n in two m od es: asynchronous (th e d efau lt) an d synchronous. Th e bu s actu ally switch es m od es d u rin g tran sfers th rou gh a p rotocol called synchronous negotiation. Before d ata is tran sferred across th e SCSI bu s, th e sen d in g d evice (called th e initiator) an d th e receivin g d evice (called th e target) n egotiate h ow th e tran sfer will take p lace. If both d evices su p p ort syn ch ron ou s tran sfers, th ey will d iscover th is fact th rou gh th e n egotiation , an d th e tran sfer will take p lace at th e faster syn ch ron ou s rate. Un fortu n ately, som e old er d evices d o n ot resp on d to a req u est for syn ch ron ou s tran sfer an d can actu ally be d isabled wh en su ch a req u est is m ad e. For th is reason , both h ost ad ap ters an d d evices th at su p p ort syn ch ron ou s n egotiation often h ave a ju m p er th at can be u sed to d isable th is n egotiation so it can work with old er d evices. By d efau lt, all d evices tod ay sh ou ld su p p ort syn ch ron ou s n egotiation , an d th is fu n ction sh ou ld be en abled . Plug-and-Play ( PnP) SCSI Plu g-an d -Play SCSI was origin ally released in Ap ril 1994. Th is sp ecification allows SCSI d evice m an u factu rers to bu ild Pn P p erip h erals th at will au tom atically con figu re wh en u sed with a Pn P op eratin g system . Th is will allow you to easily con n ect or recon figu re extern al p erip h erals, su ch as h ard d isk d rives, backu p tap es, an d CD-ROMs. To con n ect SCSI p erip h erals to th e h ost PC, th e sp ecification req u ires a Pn P SCSI h ost ad ap ter su ch as Pn P ISA or PCI. Pn P ad d -in card s en able a Pn P op eratin g system to au tom atically con figu re software d evice d rivers an d system resou rces for th e h ost bu s in terface.

Small Computer System Interface (SCSI)

Th e Pn P SCSI sp ecification version 1.0 in clu d es th ese tech n ical h igh ligh ts: ■ A sin gle cable-con n ector con figu ration ■ Au tom atic term in ation of th e SCSI bu s ■ SCAM (SCSI Con figu red Au tom agically) au tom atic ID assign m en t ■ Fu ll backward com p atibility of Pn P SCSI d evices with th e in stalled base of SCSI system s. Th is sh ou ld go a lon g way in m akin g SCSI easier to u se for th e n orm al u ser. Each SCSI p erip h eral th at you ad d to you r SCSI bu s (oth er th an h ard d isk d rives) req u ires an extern al d river to m ake th e d evice work. Hard d isks are th e excep tion ; d river su p p ort for th em n orm ally is p rovid ed as p art of th e SCSI h ost ad ap ter BIOS. Th ese extern al d rivers are sp ecific n ot on ly to a p articu lar d evice, bu t also to th e h ost ad ap ter. Recen tly, two typ es of stan d ard h ost ad ap ter in terface d rivers h ave becom e p op u lar, greatly red u cin g th is p roblem . By h avin g a stan d ard h ost ad ap ter d river to write to, p erip h eral m akers can m ore q u ickly create n ew d rivers th at su p p ort th eir d evices an d th en talk to th e u n iversal h ost ad ap ter d river. Th is arran gem en t elim in ates d ep en d en ce on on e p articu lar typ e of h ost ad ap ter. Th ese p rim ary or u n iversal d rivers lin k th e h ost ad ap ter an d th e op eratin g system . Th e Advanced SCSI Program m ing Interface (ASPI) cu rren tly is th e m ost p op u lar u n iversal d river, with m ost p erip h eral m akers writin g th eir d rivers to talk to ASPI. Th e A in ASPI u sed to stan d for Ad ap tec, th e com p an y th at in trod u ced it, bu t oth er SCSI d evice ven d ors h ave licen sed th e righ t to u se ASPI with th eir p rod u cts. DOS d oes n ot su p p ort ASPI d irectly, bu t it d oes wh en th e ASPI d river is load ed . W in d ows 95, W in d ows NT, an d OS/ 2 2.1 an d later version s p rovid e au tom atic ASPI su p p ort for several SCSI h ost ad ap ters. Fu tu re Dom ain an d NCR h ave created an oth er in terface d river called th e Com m on Access Method (CAM). CAM is an ANSI-ap p roved p rotocol th at en ables a sin gle d river to con trol several h ost ad ap ters. In ad d ition to ASPI, OS/ 2 2.1 an d later version s cu rren tly offer su p p ort for CAM. Fu tu re Dom ain also p rovid es a CAM-to-ASPI con verter in th e u tilities th at go with its h ost ad ap ters. SCSI Configurat ion Tips W h en you are in stallin g a ch ain of d evices on a sin gle SCSI bu s, th e in stallation can get com p licated very q u ickly. Here are som e tip s for gettin g you r setu p to fu n ction q u ickly an d efficien tly: ■ Start by adding one device at a tim e. Rath er th an p lu g n u m erou s p erip h erals in to a sin gle SCSI card an d th en try to con figu re th em at th e sam e tim e, start by in stallin g th e h ost ad ap ter an d a sin gle h ard d isk. Th en you can con tin u e in stallin g d evices on e at a tim e, ch eckin g to m ake su re th at everyth in g works before m ovin g on .

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■ Keep good docum entation. W h en you ad d a SCSI p erip h eral, write d own th e SCSI ID ad d ress an d an y oth er switch an d ju m p er settin gs, su ch as SCSI Parity, Term in ator Power, an d Delayed or Rem ote Start. For th e h ost ad ap ter, record th e BIOS ad d resses, In terru p t, DMA ch an n el, an d I/ O Port ad d resses u sed by th e ad ap ter, an d an y oth er ju m p er or con figu ration settin gs (su ch as term in ation ) th at m igh t be im p ortan t to kn ow later. ■ Use proper term ination. Each en d of th e bu s m u st be term in ated , p referably with active or Forced Perfect (FPT) term in ators. If you are u sin g an y Fast SCSI-2 d evice, you m u st u se active term in ators rath er th an th e ch eap er p assive typ es. Even with stan d ard (slow) SCSI d evices, active term in ation is h igh ly recom m en d ed . If you h ave on ly in tern al or extern al d evices on th e bu s, th e h ost ad ap ter an d last d evice on th e ch ain sh ou ld be term in ated . If you h ave extern al an d in tern al d evices on th e ch ain , you gen erally will term in ate th e first an d last of th ese d evices bu t n ot th e SCSI h ost ad ap ter (wh ich is in th e m id d le of th e bu s). ■ Use high-quality shielded SCSI cables. Make su re th at you r cable con n ectors m atch you r d evices. Use h igh -q u ality sh ield ed cables, an d observe th e SCSI bu s-len gth lim itation s. Use cables d esign ed for SCSI u se, an d if p ossible, stick to th e sam e bran d of cable th rou gh ou t a sin gle SCSI bu s. Differen t bran d s of cables h ave d ifferen t im p ed an ce valu es; th is situ ation som etim es cau ses p roblem s, esp ecially in lon g or h igh -sp eed SCSI im p lem en tation s. Followin g th ese sim p le tip s will h elp m in im ize p roblem s an d leave you with a trou blefree SCSI in stallation .

IDE Versus SCSI W h en you com p are th e p erform an ce an d cap abilities of IDE an d SCSI in terfaced d rives, you n eed to con sid er several factors. Th ese two typ es of d rives are th e m ost p op u lar d rives u sed in PC system s tod ay, an d a sin gle m an u factu rer m ay m ake id en tical d rives in both in terfaces. Decid in g wh ich d rive typ e is best for you r system is a d ifficu lt d ecision th at d ep en d s on m an y factors. In m ost cases, you will fin d th at an IDE d rive ou tp erform s an eq u ivalen t SCSI d rive at a given task or ben ch m ark, an d th at IDE d rives u su ally cost less th an SCSI d rives, th u s offerin g better valu e. In som e cases, h owever, SCSI d rives h ave sign ifican t p erform an ce an d valu e ad van tages over IDE d rives. It is in terestin g to see th at SCSI really evolved from IDE, or you cou ld say th at both evolved from th e ST-506/ 412 an d ESDI in terfaces th at were on ce u sed . SCSI Hard Disk Evolut ion and Const ruct ion SCSI is n ot a d isk in terface, bu t a bu s th at su p p orts SCSI bu s in terface ad ap ters con n ected to d isk an d oth er d evice con trollers. Th e first SCSI d rives for PCs were stan d ard ST-506/ 412 or ESDI d rives with a sep arate SCSI bu s in terface ad ap ter (som etim es called a bridge controller) th at con verted th e ST-506/ 412 or ESDI in terfaces to SCSI. Th is in terface origin ally was in th e form of a secon d ary logic board , an d th e en tire assem bly often was m ou n ted in an extern al case.

IDE Versus SCSI

Th e n ext step was to bu ild th e SCSI bu s in terface “con verter” board d irectly in to th e d rive’s own logic board . Tod ay, we call th ese d rives em bedded SCSI drives, becau se th e SCSI in terface is bu ilt in . At th at p oin t, th ere was n o n eed to con form to th e absolu te sp ecification s of ST-506/ 412 or ESDI on th e in tern al d isk in terface, becau se th e on ly oth er d evice th at th e in terface ever wou ld h ave to talk to was bu ilt in as well. Th u s, th e d isk-in terface an d con trollerch ip set m an u factu rers began to d evelop m ore cu stom ized ch ip sets th at were based on th e ST-506/ 412 or ESDI ch ip sets alread y available bu t offered m ore featu res an d h igh er p erform an ce. Tod ay, if you look at a typ ical SCSI d rive, you often can id en tify th e ch ip or ch ip set th at serves as th e d isk con troller on th e d rive as bein g exactly th e sam e kin d th at wou ld be u sed on an ST-506/ 412 or ESDI con troller or as som e evolu tion ary cu stom ized variation th ereof. Con sid er som e exam p les. An ATA IDE d rive m u st fu lly em u late th e system -level d iskcon troller in terface in trod u ced with th e W estern Digital W D1003 con troller series th at IBM u sed in th e AT. Th ese d rives m u st act as th ou gh th ey h ave a bu ilt-in ST-506/ 412 or ESDI con troller; in fact, th ey actu ally d o. Most of th ese bu ilt-in con trollers h ave m ore cap abilities th an th e origin al W D1003 series (u su ally in th e form of ad d ition al com m an d s), bu t th ey m u st at least resp on d to all th e origin al com m an d s th at were u sed with th e W D1003. If you follow th e h ard d rive m arket, you u su ally will see th at d rive m an u factu rers offer m ost of th eir n ewer d rives in both ATA-IDE an d SCSI version s. In oth er word s, if a m an u factu rer m akes a p articu lar 500M IDE d rive, you in variably will see th at th e com p an y also m ake a SCSI m od el with th e sam e cap acity an d sp ecification s, wh ich u ses th e sam e HDA (Head Disk Assem bly) an d even looks th e sam e as th e IDE version . If you stu d y th ese virtu ally id en tical d rives, th e on ly m ajor d ifferen ce you will fin d is th e ad d ition al ch ip on th e logic board of th e SCSI version , called a SCSI Bus Adapter Chip (SBIC). Figu res 10.9 an d 10.10 sh ow th e logic-block d iagram s of th e W D-AP4200 (a 200M ATAIDE d rive) an d W D-SP4200 (a 200M SCSI d rive), resp ectively. Th ese d rives u se th e sam e HDA; th ey d iffer on ly in th eir logic board s, an d even th e logic board s are th e sam e excep t for th e ad d ition of an SBIC on th e SCSI d rive’s logic board . Notice th at even th e circu it d esign s of th ese two d rives are alm ost id en tical. Both d rives u se an LSI (Large Scale In tegrated circu it) ch ip called th e W D42C22 Disk Con troller an d Bu ffer m an ager ch ip . In th e ATA d rive, th is ch ip is con n ected th rou gh a DMA con trol ch ip d irectly to th e AT bu s. In th e SCSI version , a W D33C93 SCSI bu s in terface con troller ch ip is ad d ed to in terface th e d isk-con troller logic to th e SCSI bu s. In fact, th e logic d iagram s of th ese two d rives d iffer on ly in th e fact th at th e SCSI version h as a com p lete su bset of th e ATA d rive, with th e SCSI bu s in terface con troller logic ad d ed . Th is essen tially is a very con d en sed version of th e sep arate d rive an d brid ge con troller setu p s th at were u sed in th e early d ays of PC SCSI.

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LED 12 MHZ OSC 16K X 16 ROM 1K X 16 RAM PSD301

BUS µP

SERVO µP

16K X 16 ROM

80C196

80C196

1K X 16 RAM PSD301

DISK CONTROL

SERVO MOTOR CONTROLLER

SPINDLE DRIVER

HDA

(LOBSTER) WD60C11 VANILLA AT BUS

ACTUATOR DRIVER

GAL20V8

DMA CONTROL

WD42C22C

READ CHANNEL DATA SEPARATOR 25.3122 MHZ

15 MHZ

POWER

648

+12V

SECTOR BUFFER 64K X 8

GND GND +5V

FIG. 10.9 W estern Digital W D-AP4200 200M ATA-IDE d rive logic-board block d iagram . To top off th is exam p le, stu d y th e followin g logic d iagram for th e W D 1006V-MM1, wh ich is an ST-506/ 412 con troller (see Figu re 10.11). You can clearly see th at th e m ain LSI ch ip on board is th e sam e W D42C22 d isk con troller ch ip u sed in th e IDE an d SCSI d rives. Here is wh at th e tech n ical referen ce literatu re says abou t th at ch ip : The W D42C22 integrates a high perform ance, low cost W inchester controller’s architecture. The W D42C22 integrates the central elem ents of a W inchester controller subsystem such as the host interface, buffer m anager, disk form atter/controller, encoder/decoder, CRC/ECC (Cyclic Redundancy Check/Error Correction Code) generator/checker, and drive interface into a single 84-pin PQFP (Plastic Quad Flat Pack) device.

IDE Versus SCSI

SCSI Bus SCSI Bus Interface Controller (SBIC) WD33C93A/B

16K X 16 ROM 1K X 16 RAM

Bus µC

Servo µC

Spindle Control

16K X 16 ROM 1K X 16 RAM J

J

Spindle Driver HDA Servo Motor Controller (Lobster) WD60C11

Disk Controller & Buffer Manager (Vanilla) WD42C22C

Actuator Driver

Pulse Detector Data Separator WD10C23

HDA Control

Sector Buffer RAM 64K X 8

FIG. 10.10 W estern Digital W D-SP4200 200M SCSI d rive logic-board block d iagram .

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H o s t I n t e r f a c e

Floppy Chip Select

SAO thru SA9 Address Decode Pal

Chip Select

Control/ Status

WD37C65A MFM Data

SD0 t hru SD7

F l o p p y I n t e r f a c e

BA0 thru BA13 SD8 thru SD15 WD42C22

BD0 thru BD7

Track Buffer Write Data WD10C22

Control/Status AD0 thru AD7 WD1017

Read Data

W i n c h e s t e r I n t e r f a c e

FIG. 10.11 W estern Digital W D1006V-MM1 ST-506/ 412 Disk Con troller block d iagram . Th e virtu ally id en tical d esign of ATA-IDE an d SCSI d rives is n ot u n iq u e to W estern Digital. Most d rive m an u factu rers d esign th eir ATA-IDE an d SCSI d rives th e sam e way, often u sin g th ese very sam e W D ch ip s, an d d isk con troller an d SCSI bu s in terface ch ip s from oth er m an u factu rers. You n ow sh ou ld be able to u n d erstan d th at m ost SCSI d rives are “regu lar” ATA-IDE d rives with SCSI bu s logic ad d ed . Th is fact will com e u p again later in th is ch ap ter in th e section “SCSI Versu s IDE: Ad van tages an d Lim itation s,” wh ich d iscu sses p erform an ce an d oth er issu es d ifferen tiatin g th ese in terfaces. For an oth er exam p le, I h ave several IBM 320M an d 400M em bed d ed SCSI-2 h ard d isks; each of th ese d rives h as on board a W D-10C00 Program m able Disk Con troller in th e form of a 68-p in PLCC (Plastic Lead ed Ch ip Carrier) ch ip . Th e tech n ical literatu re states: This chip supports ST412, ESDI, SMD and Optical interfaces. It has 27Mbit/sec m axim um transfer rate and an internal, fully program m able 48- or 32-bit ECC, 16-bit CRCCCITT or external user defined ECC polynom ial, fully program m able sector sizes, and 1.25 m icron low power CMOS design. In ad d ition , th ese p articu lar em bed d ed SCSI d rives in clu d e th e 33C93 SCSI Bu s In terface Con troller ch ip , wh ich also is u sed in th e oth er SCSI d rive th at I m en tion ed . Again , th ere is a d istin ctly sep arate d isk con troller, an d th e SCSI in terface is ad d ed on .

IDE Versus SCSI

So again , m ost em bed d ed SCSI d rives h ave a bu ilt-in d isk con troller (u su ally based on p reviou s ST-506/ 412 or ESDI d esign s) an d ad d ition al logic to in terface th at con troller to th e SCSI bu s (a bu ilt-in brid ge con troller, if you like). Now th in k abou t th is from a p erform an ce stan d p oin t. If virtu ally all SCSI d rives really are ATA-IDE d rives with a SCSI Bu s In terface Con troller ch ip ad d ed , wh at con clu sion s can you d raw? First, n o d rive can p erform su stain ed d ata tran sfers faster th an th e d ata can actu ally be read from th e d isk p latters. In oth er word s, th e HDA lim its p erform an ce to wh atever it is cap able of ach ievin g. Drives can tran sm it d ata in sh ort bu rsts at very h igh sp eed s, becau se th ey often h ave bu ilt-in cach e or read -ah ead bu ffers th at store d ata. Man y of th e n ewer h igh -p erform an ce SCSI an d ATA-IDE d rives h ave 1M or m ore of cach e m em ory on board . No m atter h ow big or in telligen t th e cach e is, h owever, su stain ed d ata tran sfer still will be lim ited by th e HDA. Data from th e HDA m u st p ass th rou gh th e d isk con troller circu its, wh ich , as you h ave seen , are virtu ally id en tical between sim ilar SCSI an d ATA-IDE d rives. In th e ATA-IDE d rive, th is d ata th en is p resen ted d irectly to th e system bu s. In th e SCSI d rive, h owever, th e d ata m u st p ass th rou gh a SCSI Bu s In terface ad ap ter on th e d rive, travel th rou gh th e SCSI bu s, an d th en p ass th rou gh an oth er SCSI Bu s In terface con troller in th e SCSI h ost ad ap ter card in you r system . Th e lon ger rou te th at a SCSI tran sfer m u st take m akes th is typ e of tran sfer slower th an th e m u ch m ore d irect ATA-IDE tran sfer. Th e con ven tion al wisd om h as been th at SCSI always is m u ch faster th an IDE; u n fortu n ately, th is wisd om is u su ally wron g. Th is in correct con clu sion was d erived by lookin g at th e raw SCSI an d ISA bu s p erform an ce cap abilities. An 8-bit Fast SCSI-2 bu s can tran sfer d ata at 10M/ sec, wh ereas th e 16-bit ISA bu s u sed d irectly by IDE d rives can tran sfer d ata at rates ran gin g from 2M to 8M/ sec. Based on th ese raw tran sfer rates, SCSI seem s to be faster, bu t th e raw tran sfer rate of th e bu s is n ot th e lim itin g factor. In stead , th e actu al HDA an d d isk-con troller circu itry p lace th e lim its on p erform an ce. An oth er p oin t to rem em ber is th at u n less you are u sin g a PCI, VL-Bu s, EISA, or 32-bit MCA SCSI ad ap ter, th e SCSI d ata-tran sfer sp eed s will be lim ited by th e h ost bu s p erform an ce an d by th e d rive p erform an ce. However, m od ern op eratin g system s are m u ltitaskin g, an d SCSI d evices (with all th eir ad d ition al con troller circu itry) fu n ction in d ep en d en tly of on e an oth er, u n like IDE. Th erefore, d ata can be read an d written to an y of th e SCSI d evices sim ultaneously. Th is allows for sm ooth er m u ltitaskin g an d in creased overall d ata th rou gh p u t. Th e m ost ad van ced op eratin g system s su ch as W in d ows NT even allow d rive strip in g. A striped drive set is two or m ore d rives th at ap p ear to th e u ser as on e d rive. Data is sp lit between th e d rives eq u ally, again in creasin g overall th rou gh p u t. Perform ance ATA IDE d rives cu rren tly are u sed in m ost PC con figu ration s on th e m arket, becau se th e cost of an IDE-d rive im p lem en tation is low an d th e p erform an ce cap abilities are h igh . In com p arin g an y given IDE an d SCSI d rive for p erform an ce, you h ave to look at th e cap abilities of th e HDAs th at are in volved .

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To m in im ize th e variables in th is typ e of com p arison , it is easiest to com p are IDE an d SCSI d rives from th e sam e m an u factu rer th at also u se th e id en tical HDA. You will fin d th at in m ost cases, a d rive m an u factu rer m akes a given d rive available in both IDE an d SCSI form s. For exam p le, m ost h ard d rive com p an ies m ake sim ilar SCSI an d IDE d rives th at u se id en tical HDAs an d th at d iffer on ly in th e logic board . Th e IDE version h as a logic board with a bu ilt-in d isk con troller an d a d irect AT Bu s in terface. Th e SCSI version h as th e sam e bu ilt-in d isk con troller an d bu s in terface circu its, an d also a SBIC ch ip . Th e SBIC ch ip is a SCSI ad ap ter th at p laces th e d rive on th e SCSI bu s. W h at you will fin d , in essen ce, is th at virtu ally all SCSI d rives actu ally are IDE d rives with th e SBIC ch ip ad d ed . Th e HDAs in th ese exam p le d rives are cap able of tran sferrin g d ata at a su stain ed rate of u p to 8M/ sec or m ore. Becau se th e SCSI version always h as th e ad d ition al overh ead of th e SCSI bu s to go th rou gh , in alm ost all cases th e d irectly attach ed IDE version p erform s sligh tly faster. SCSI Versus IDE: Advant ages and Lim it at ions IDE d rives h ave m u ch less com m an d overh ead for a given sector tran sfer th an d o SCSI d rives. In ad d ition to th e d rive-to-con troller com m an d overh ead th at both IDE an d SCSI m u st p erform , a SCSI tran sfer in volves n egotiatin g for th e SCSI bu s; selectin g th e target d rive; req u estin g d ata; term in atin g th e tran sfer over th e bu s; an d fin ally con vertin g th e logical d ata ad d resses to th e req u ired cylin d er, h ead , an d sector ad d resses. Th is arran gem en t gives IDE an ad van tage in seq u en tial tran sfers h an d led by a sin gle-taskin g op eratin g system . In a m u ltitaskin g system th at can take ad van tage of th e extra in telligen ce of th e SCSI bu s, SCSI can h ave th e p erform an ce ad van tage. SCSI d rives offer sign ifican t arch itectu ral ad van tages over IDE an d oth er d rives. Becau se each SCSI d rive h as its own em bed d ed d isk con troller th at can fu n ction in d ep en d en tly from th e system CPU, th e com p u ter can issu e sim u ltan eou s com m an d s to every d rive in th e system . Each d rive can store th ese com m an d s in a q u eu e an d th en p erform th e com m an d s sim u ltan eou sly with oth er d rives in th e system . Th e d ata cou ld be fu lly bu ffered on th e d rive an d tran sferred at h igh sp eed over th e sh ared SCSI bu s wh en a tim e slot was available. Alth ou gh IDE d rives also h ave th eir own con trollers, th ey d o n ot op erate sim u ltan eou sly, an d com m an d q u eu in g is n ot su p p orted . In effect, th e d u al con trollers in a d u al-d rive IDE in stallation work on e at a tim e so as n ot to step on each oth er. W h at are th e lim itation s of IDE? ■ IDE d oes n ot su p p ort overlap p ed , m u ltitasked I/ O. ■ IDE d oes n ot su p p ort com m an d q u eu in g. As you can see, SCSI h as som e ad van tages over IDE, esp ecially wh ere exp an sion is con cern ed , an d also with regard to su p p ort for m u ltitaskin g op eratin g system s. Un fortu n ately, it also costs m ore to im p lem en t. On e fin al ad van tage of SCSI is in th e p ortability of extern al d evices. It is easy to take an extern al SCSI CD-ROM, tap e d rive, scan n er, or even a h ard d isk an d q u ickly m ove it to

IDE Versus SCSI

an oth er system . Th is allows m ovin g p erip h erals m ore freely between system s an d can be a bon u s if you h ave several system s with wh ich you m igh t wan t to sh are a n u m ber of p erip h erals. It is easier to in stall a n ew extern al SCSI d evice on a system becau se you will n ot n orm ally n eed to op en it u p at all. Recom m ended SCSI Host Adapt ers For SCSI h ost ad ap ters, I n orm ally recom m en d Ad ap tec. Th eir ad ap ters work well an d com e with th e n ecessary form attin g an d op eratin g software. W in d ows 95, W in d ows 98, W in d ows NT, an d OS/ 2 h ave bu ilt-in su p p ort for Ad ap tec SCSI ad ap ters. Th is su p p ort is a con sid eration in m an y cases, becau se it frees you from h avin g to d eal with ad d ition al d rivers. Stan d ard or Fast SCSI is ad eq u ately su p p orted by th e ISA bu s, bu t if you are goin g to in stall a Fast-W id e SCSI bu s, or esp ecially an Ultra-W id e bu s, th en you sh ou ld con sid er som e form of local bu s SCSI ad ap ter, n orm ally PCI. Th is is becau se th e ISA bu s su p p orts a m axim u m tran sfer sp eed of abou t 8M/ sec, wh ile a Fast-W id e SCSI bu s ru n s u p to 20M/ sec, an d an Ultra-W id e SCSI bu s ru n s u p to a blazin g 40M/ sec! In m ost cases, a local bu s SCSI ad ap ter wou ld be a PCI bu s version , wh ich is su p p orted in m ost cu rren t PC system s. On e exam p le of a p op u lar SCSI ad ap ter for th e PCI bu s is th e Ad ap tec AHA-2940AU (see Figu re 10.12) an d 2940UW . Th e 2940AU is an Ultra-SCSI ad ap ter an d th e 2940UW is Ultra-W id e. Th ese ad ap ters are m ost n otable for th eir ease of in stallation an d u se. Virtu ally all fu n ction s on th e card can be con figu red an d set th rou gh software. No m ore d iggin g th rou gh m an u als or lookin g for In terru p t, DMA, I/ O Port, an d oth er ju m p er settin gs—everyth in g is con trolled by software an d saved in a flash m em ory m od u le on th e card . Followin g are som e of th e featu res of th is card : ■ Com p lete con figu ration u tility bu ilt in to th e ad ap ter’s ROM ■ Software-con figu rable IRQ, ROM ad d resses, DMA, I/ O Port ad d resses, SCSI Parity, SCSI ID, an d oth er settin gs ■ Software-selectable term in ation (n o resistors to p u ll ou t!) ■ En h an ced BIOS su p p ort for u p to 15 d rives ■ No d rivers req u ired for m ore th an two h ard d isks ■ Drive sp in u p on a p er-d rive basis available ■ Boots from an y SCSI ID Ad ap tec h as fu ll Pn P su p p ort on all th eir SCSI ad ap ters. Th ese ad ap ters will be au tom atically con figu red in an y PC th at su p p orts th e Pn P sp ecification , or th ey can be con figu red m an u ally th rou gh su p p lied software in n on -Pn P system s. Th e Pn P SCSI ad ap ters are h igh ly recom m en d ed becau se th ey can be con figu red with ou t op en in g u p th e PC! All fu n ction s are set by software, an d th ere are n o ju m p ers or switch es to atten d to. Most p erip h eral m an u factu rers write d rivers for Ad ap tec’s card s first, so you will n ot h ave m an y com p atibility or d river-su p p ort p roblem s with an y Ad ap tec card .

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FIG. 10.12 An Ad ap tec AHA-2940AU SCSI h ost ad ap ter.

Chapter 11

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Communications and Networking

Com m u n ication s between com p u ters is a m ajor p art of th e PC com p u tin g in d u stry. W h eth er by u sin g a m od em or a n etwork, th e m ajority of PCs are som eh ow con n ected to oth er com p u ters, en ablin g th em to sh are files, sen d an d receive electron ic m ail, an d access th e In tern et. Th is ch ap ter exp lores th e variou s tech n ologies you can u se to exp an d th e reach of you r PC across th e room or arou n d th e world .

It m ay su rp rise you to see m od em s an d n etworkin g covered in th e sam e ch ap ter of th is book, bu t a m od em con n ection is really ju st an oth er form of n etworkin g. In fact, th e W in d ows 9x an d W in d ows NT op eratin g system s h ave all bu t blen d ed th e two services in to a sin gle en tity. Th e reason for th is com bin ation is th at th e typ ical target for a m od em con n ection h as ch an ged over th e years. For a lon g tim e, PC u sers d ialed in to bulletin board system s (or BBSs)—p rop rietary services th at p rovid ed term in al access to oth er com p u ters. On lin e services su ch as Am erica On lin e an d Com p u Serve h ave also been arou n d for m an y years, bu t th ey u se p rop rietary clien ts an d p rotocols, q u ite d ifferen t from th ose fou n d on local area n etworks. W ith th e exp losive growth of th e In tern et, m od em an d n etwork tech n ologies were join ed , becau se both cou ld u se th e sam e clien t software an d p rotocols. Tod ay, th e m ost p op u lar su ite of n etworkin g p rotocols—TCP/ IP—is u sed on both local area n etworks an d th e In tern et. W h en you d ial in to an In tern et service p rovid er (or ISP), you are actu ally con n ectin g to a n etwork, u sin g a m od em in stead of a n etwork in terface card .

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Not e Computer networking is an enormous subject, worthy of far more coverage than can be provided here. For a much more detailed examination of networking concepts, refer to Que’s Upgrading and Repairing Networks, ISBN 0-7897-0181-2. An electronic copy of Upgrading and Repairing Networks is included on the CD-ROM with this book.

Asynchronous M odem s For PCs th at are n ot con n ected to a n etwork by som e oth er m ean s, a m od em h as becom e virtu ally a stan d ard p iece of eq u ip m en t. For m an y h om e u sers, con n ectin g to th e In tern et is th eir p rim ary reason for own in g a com p u ter. W h eth er for bu sin ess, en tertain m en t, or ju st keep in g in tou ch with frien d s an d fam ily, a m od em con n ection takes an isolated system an d m akes it a p art of a world wid e n etwork. Th e word m odem (from MOd u lator/ DEMod u lator) basically d escribes a d evice th at con verts th e d igital d ata u sed by com p u ters in to an alog sign als su itable for tran sm ission over a telep h on e lin e, an d con verts th e an alog sign als back to d igital d ata at th e d estin ation . Th e typ ical PC m od em is an asynchronous d evice, m ean in g th at it tran sm its d ata in an in term itten t stream of sm all p ackets. Th e receivin g system takes th e d ata in th e p ackets an d reassem bles it in to a form th e com p u ter can u se. Asyn ch ron ou s m od em s tran sm it each byte of d ata in d ivid u ally as a sep arate p acket. On e byte eq u als 8 bits, wh ich u sin g th e stan d ard ASCII cod es is en ou gh d ata to tran sm it a sin gle alp h an u m eric ch aracter. For a m od em to tran sm it asyn ch ron ou sly, it m u st id en tify th e begin n in g an d th e en d of each byte to th e receivin g m od em . It d oes th is by ad d in g a start bit before an d a stop bit after every byte of d ata, th u s u sin g 10 bits to tran sm it each byte (see Figu re 11.1). For th is reason , asyn ch ron ou s com m u n ication s h ave som etim es been referred to as start-stop com m unications. Th is is in con trast to syn ch ron ou s com m u n ication s, in wh ich a con tin u ou s stream of d ata is tran sm itted at a stead y rate.

Stop Bit

Data Bits

Start Bit

Stop Bit

Data Bits

Start Bit

Asynchronous

Data Bits

Synchronous

FIG. 11.1 Asyn ch ron ou s m od em s fram e each byte of d ata with a start bit an d a stop bit, wh ile syn ch ron ou s com m u n ication s u se an u n in terru p ted stream of d ata.

Asynchronous M odems

Not e During high-speed modem communications, the start and stop bits are usually not transmitted over the telephone line. Instead, they are eliminated by the data compression algorithm implemented by the modem. However, these bits are part of the data packets generated by the communications software in the computer, and they exist until they reach the modem hardware.

Th e u se of a sin gle start bit is req u ired in all form s of asyn ch ron ou s com m u n ication , bu t som e p rotocols u se m ore th an on e stop bit. To accom m od ate system s with d ifferen t p rotocols, com m u n ication s software p rod u cts u su ally en able you to m od ify th e form at of th e fram e u sed to tran sm it each byte. Th e stan d ard form at u sed to d escribe an asyn ch ron ou s com m u n ication s form at is parity–data bits–stop bits. Alm ost all asyn ch ron ou s con n ection s tod ay are th erefore abbreviated as N-8-1 (No p arity/ 8 d ata bits/ 1 stop bit). Th e m ean in gs for each of th ese p aram eters an d th eir p ossible variation s are as follows: ■ Parity. Before error-correction p rotocols becam e stan d ard m od em featu res, a sim p le p arity m ech an ism was u sed to p rovid e basic error ch eckin g at th e software level. Tod ay, th is is alm ost n ever u sed , an d th e valu e for th is p aram eter is n early always set to none. Oth er p ossible p arity valu es th at you m igh t see in a com m u n ication s software p ackage are odd, even, m ark, an d space. ■ Data Bits. Th is p aram eter in d icates h ow m an y bits are actu ally carried in th e d ata p ortion of th e p acket (exclu sive of th e start an d stop bits). PCs typ ically u se 8 d ata bits, bu t som e typ es of com p u ters u se a 7-bit byte, an d oth ers m ay call for oth er d ata len gth s. Com m u n ication s p rogram s p rovid e th is op tion to p reven t a system from con fu sin g a stop bit with a d ata bit. ■ Stop Bits. Th is p aram eter sp ecifies h ow m an y stop bits are ap p en d ed to each byte. PCs typ ically u se on e stop bit, bu t oth er typ es of p rotocols m ay call for th e u se of 1.5 or 2 stop bits. In m ost situ ation s, you will n ever h ave to m od ify th ese p aram eters m an u ally, bu t th e con trols are alm ost always p rovid ed . In W in d ows 9x, for exam p le, if you op en th e Mod em s Con trol Pan el an d look at th e Con n ection p age of you r m od em ’s Prop erties d ialog box, you will see Data Bits, Parity, an d Stop Bits selectors, as sh own in Figu re 11.2.

Not e Because it has become such a familiar term, even to inexperienced computers users, the word m odem is frequently used to describe devices that are, strictly speaking, not modems at all. Later in this chapter, you will learn about ISDN and cable modems, neither of which convert digital information to analog signals. However, because these devices look something like a standard modem and are used to connect PCs to the Internet or to other networks, they are called modems.

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FIG. 11.2 Th e W in d ows 9x Con trol Pan el en ables you to ad ju st th e con n ection p referen ces for you r m od em .

M odem St andards For two m od em s to com m u n icate, th ey m u st sh are th e sam e p rotocol. A protocol is sim p ly a sp ecification th at d eterm in es h ow two en tities will com m u n icate. Ju st as h u m an s m u st sh are a com m on lan gu age an d vocabu lary to sp eak with each oth er, two com p u ters or two m od em s m u st sh are a com m on p rotocol. In th e case of m od em s, th e p rotocol d eterm in es th e n atu re of th e an alog sign al th at th e d evice creates from th e com p u ter’s d igital d ata. Th rou gh th e years, th ere h ave been m an y stan d ard s for m od em com m u n ication s, m ost of th em d evelop ed by bip artisan com m ittees an d accep ted by n early all m od em m an u factu rers. As th e h ard ware tech n ology h as im p roved , m od em com m u n ication s h ave becom e faster an d m ore efficien t, an d n ew stan d ard s are con stan tly bein g d evelop ed to take ad van tage of th e h ard ware’s cap abilities. Bell Labs an d th e CCITT are two of th e bod ies th at h ave set stan d ard s for m od em p rotocols. CCITT is an acron ym for Com ité Consultatif International Téléphonique et Télégraphique, a Fren ch term th at tran slates in to En glish as th e Consultative Com m ittee on International Telephone and Telegraph. Th e organ ization was ren am ed th e In tern ation al Telecom m u n ication s Un ion (ITU) in th e early 1990s, bu t th e p rotocols d evelop ed u n d er th e old n am e are often referred to as su ch . Newly d evelop ed p rotocols are referred to as ITU-T stan d ard s, wh ich refers to th e Telecom m unication Standardization Sector of th e ITU. Bell Labs n o lon ger sets n ew stan d ard s for m od em s, alth ou gh several of its old er stan d ard s are still u sed . Most m od em s bu ilt in recen t years con form to th e stan d ard s d evelop ed by th e CCITT. Th e ITU is an in tern ation al bod y of tech n ical exp erts resp on sible for d evelop in g d ata com m u n ication s stan d ard s for th e world . Th e grou p falls u n d er th e organ ization al u m brella of th e Un ited Nation s, an d its m em bers in clu d e rep resen tatives from m ajor m od em m an u factu rers, com m on carriers (su ch as AT&T), an d govern m en tal bod ies. Th e ITU establish es com m u n ication s stan d ard s an d p rotocols in m an y areas, so on e m od em often ad h eres to m an y d ifferen t stan d ard s, d ep en d in g on its variou s featu res an d cap abilities. Mod em stan d ard s can be grou p ed in to th e followin g th ree areas:

Asynchronous M odems

■ Mod u lation stan d ard s Bell 103 Bell 212A CCITT V.21 CCITT V.22bis CCITT V.29 CCITT V.32 CCITT V.32bis CCITT V.34 ITU V.90 ■ Error-correction CCITT V.42 ■ Data-com p ression V.42bis Oth er stan d ard s h ave been d evelop ed by d ifferen t com p an ies (n ot Bell Labs or th e ITU). Th ese are som etim es called proprietary standards, even th ou gh m ost of th ese com p an ies p u blish th e fu ll sp ecification s of th eir p rotocols so th at oth er m an u factu rers can d evelop m od em s to work with th em . Th e followin g list sh ows som e of th e p rop rietary stan d ard s th at h ave been p op u lar over th e years: ■ Mod u lation HST PEP DIS X2 K56flex ■ Error correction MNP 1-4 Hayes V-series ■ Data com p ression MNP 5 CSP In th e in terests of backward -com p atibility, m od em m an u factu rers typ ically ad d su p p ort for n ew stan d ard s as th ey are d evelop ed , leavin g th e su p p ort for th e old stan d ard s in p lace. As a resu lt, wh en you evalu ate m od em s, you are likely to see lon g lists of th e stan d ard s th ey su p p ort, like th ose ju st sh own . In m ost cases, you will wan t to kn ow wh eth er a m od em su p p orts th e m ost recen t stan d ard s, so su p p ort for an arch aic an d seld om -u sed p rotocol sh ou ld n ot govern you r p u rch asin g d ecision .

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Alm ost all m od em s tod ay claim to be Hayes-com patible, a p h rase th at h as com e to be as m ean in gless as IBM-com patible wh en referrin g to PCs. It d oes n ot refer to an y com m u n ication p rotocol, bu t in stead to th e AT com m an d set th at op erates th e m od em . AT com m an d s are text strin gs sen t to th e m od em by software to activate th e m od em ’s featu res. For exam p le, th e ATDT com m an d , followed by a telep h on e n u m ber, cau ses th e m od em to d ial th at n u m ber u sin g ton e d ialin g m od e. Ap p lication s th at u se m od em s typ ically gen erate AT com m an d s for you , bu t you can con trol a m od em d irectly u sin g a com m u n ication s p rogram with a term in al m od e, or even th e DOS ECHO com m an d . Assu m in g th at you h ave a m od em con n ected to you r PC’s COM2 p ort, you can d em on strate th is cap ability by issu in g th e followin g com m an d from th e DOS com m an d lin e: ECHO ATH1 > COM2

Th is com m an d sen d s th e ATH1 com m an d strin g ou t th rou gh you r com p u ter’s COM2 p ort to th e m od em , cau sin g it to go “off h ook.” If you r m od em h as a sp eaker, you sh ou ld h ear a d ial ton e. To h an g u p , issu e th e followin g com m an d : ECHO ATH0 > COM2

Becau se alm ost every m od em u ses th e Hayes com m an d set, th is com p atibility is a given an d sh ou ld n ot really affect you r p u rch asin g d ecision s abou t m od em s. Th e basic m od em com m an d s m ay vary sligh tly from m an u factu rer to m an u factu rer, d ep en d in g on a m od em ’s sp ecial featu res, bu t th e basic AT com m an d set is all bu t u n iversal. Som e m od em s, m ost n otably U.S. Robotics, allow you to q u ery th e com m an d set by sim p ly sen d in g th e strin g AT$ to th e m od em .

Not e A list of the basic AT commands can be found in Appendix D, “ Technical Reference.” However, the best source for the commands used by your modem is the manual that came with the device.

Baud Versus Bit s per Second ( bps) When discussing modem transmission speeds, the terms baud rate and bit rate are often confused. Baud rate is the rate at which a signal between two devices changes in one second. If a signal

between two modems can change frequency or phase at a rate of 300 times per second, for example, that device is said to communicate at 300 baud. Sometimes a single modulation change is used to carry a single bit. In that case, 300 baud also equals 300 bits per second (bps). If the modem could signal two bit values for each signal change, the bits per second rate would be twice the baud rate, or 600bps at 300 baud. M ost modems transmit several bits per baud, so that the actual baud rate is much slower than the bits per second rate. In fact, people often use the term baud incorrectly. We normally are not interested in the raw baud rate, but in the bits per second rate, which is the true gauge of communications speed.

M odulat ion St andards. Mod em s start with m odulation, wh ich is th e electron ic sign alin g m eth od u sed by th e m od em (from m od u lator to d em od u lator). Mod u lation is a varian ce in som e asp ect of th e tran sm itted sign al. By m od u latin g th e sign al u sin g a

Asynchronous M odems

p red eterm in ed p attern , th e m od em en cod es th e com p u ter d ata an d sen d s it to an oth er m od em th at d em od u lates (or d ecod es) th e sign al. Mod em s m u st u se th e sam e m od u lation m eth od to u n d erstan d each oth er. Each d ata rate u ses a d ifferen t m od u lation m eth od , an d som etim es m ore th an on e m eth od exists for a p articu lar rate. Th e th ree m ost p op u lar m od u lation m eth od s are ■ Frequency-shift keying (FSK). A form of freq u en cy m od u lation , oth erwise kn own as FM. By cau sin g an d m on itorin g freq u en cy ch an ges in a sign al sen t over th e p h on e lin e, two m od em s can sen d in form ation . ■ Phase-shift keying (PSK). A form of p h ase m od u lation , in wh ich th e tim in g of th e carrier sign al wave is altered an d th e freq u en cy stays th e sam e. ■ Quadrature am plitude m odulation (QAM). A m od u lation tech n iq u e th at com bin es p h ase ch an ges with sign al-am p litu d e variation s, resu ltin g in a sign al th at can carry m ore in form ation th an th e oth er m eth od s. Table 11.1 lists th e p rotocols th at d efin e th e m od u lation stan d ard s u sed by asyn ch ron ou s m od em s, alon g with th eir m axim u m tran sm ission rates an d d u p lex m od es. A full duplex p rotocol is on e in wh ich com m u n ication s can travel in both d irection s at th e sam e tim e an d at th e sam e sp eed . A telep h on e call, for exam p le, is fu ll d u p lex, becau se both p arties can sp eak at th e sam e tim e. In half duplex m od e, com m u n ication s can travel in both d irection s, bu t on ly on e sid e can tran sm it at a tim e. A rad io call in wh ich on ly on e p arty can sp eak at a tim e is an exam p le of h alf d u p lex com m u n ication s. Table 11.1 Prot ocol

M odem M odulat ion St andards and Transm ission Rat es M axim um Transm ission Rat e ( Bit s per Second)

Duplex M ode

Bell 103

300bps

Full

CCITT V.21

300bps

Full

Bell 212A

1200bps

Full

ITU V.22

1200bps

Half

ITU V.22bis

2400bps

Full

ITU V.23

1200/ 75bps

Pseudo-Full

ITU V.29

9600bps

Half

ITU V.32

9600bps

Full

ITU V.32bis

14400bps (14.4Kbps)

Full

ITU V.32fast

28800bps (28.8Kbps)

Full

ITU V.34

28800bps (28.8Kbps)

Full

ITU V.90

56000bps (56Kbps)

Full

Be l l 1 0 3 . Bell 103 is a U.S. an d Can ad ian 300bp s m od u lation stan d ard . It u ses FSK m od u lation at 300 bau d to tran sm it 1 bit p er bau d . Most h igh er-sp eed m od em s are still cap able of com m u n icatin g u sin g th is p rotocol, even th ou gh it is obsolete.

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V.2 1 . V.21 is an in tern ation al d ata-tran sm ission stan d ard for 300bp s com m u n ication s, sim ilar to Bell 103. Becau se of som e d ifferen ces in th e freq u en cies th ey u se, Bell 103 m od em s are n ot com p atible with V.21 m od em s. Th is stan d ard was u sed p rim arily ou tsid e th e Un ited States. Be l l 2 1 2 A. Bell 212A is th e U.S. an d Can ad ian 1200bp s m od u lation stan d ard . It u ses d ifferen tial p h ase-sh ift keyin g (DPSK) at 600 bau d to tran sm it 2 bits p er bau d . V.2 2 . V.22 is an in tern ation al 1200bp s d ata-tran sm ission stan d ard . Th is stan d ard is sim ilar to th e Bell 212A stan d ard bu t is in com p atible in som e areas, esp ecially in an swerin g a call. Th is stan d ard was u sed p rim arily ou tsid e th e Un ited States. V.2 2 b i s. V.22bis is a d ata-tran sm ission stan d ard for 2400bp s com m u n ication s. Bis is d erived from th e Latin m ean in g second, in d icatin g th at th is d ata tran sm ission is an im p rovem en t to, or follows, V.22. Th is in tern ation al stan d ard is u sed in sid e an d ou tsid e th e Un ited States. V.22bis u ses QAM at 600 bau d an d tran sm its 4 bits p er bau d to ach ieve 2400bp s. V.2 3 . V.23 is a sp lit d ata-tran sm ission stan d ard , op eratin g at 1,200bp s in on e d irection an d 75bp s in th e reverse d irection . Th erefore, th e m od em is on ly pseudo-full-duplex, m ean in g th at it can tran sm it d ata in both d irection s sim u ltan eou sly, bu t n ot at th e m axim u m d ata rate. Th is stan d ard was d evelop ed to lower th e cost of 1200bp s m od em tech n ology, wh ich was exp en sive in th e early 1980s. Th is stan d ard was u sed p rim arily in Eu rop e. V.2 9 . V.29 is a d ata-tran sm ission stan d ard for 9600bp s com m u n ication s, wh ich d efin es a h alf-d u p lex (on e-way) m od u lation tech n iq u e. Th is stan d ard gen erally is u sed in Grou p III facsim ile (fax) tran sm ission s, an d on ly rarely in m od em s. Becau se V.29 is a h alfd u p lex m eth od , it is su bstan tially easier to im p lem en t th is h igh -sp eed stan d ard th an a h igh -sp eed fu ll-d u p lex stan d ard . As a m od em stan d ard , V.29 h as n ot been fu lly d efin ed , so V.29 m od em s of d ifferen t bran d s seld om can com m u n icate with each oth er. Th is d oes n ot affect fax m ach in es, h owever, wh ich h ave a fu lly d efin ed stan d ard . V.3 2 . V.32 is a fu ll-d u p lex (two-way) d ata tran sm ission stan d ard th at ru n s at 9600bp s. It is a fu ll m od em stan d ard an d also in clu d es forward error-correctin g an d n egotiation stan d ard s. V.32 u ses TCQAM (trellis coded quadrature am plitude m odulation) at 2400 bau d to tran sm it 4 bits p er bau d , resu ltin g in th e 9600bp s tran sm ission sp eed . Th e trellis cod in g is a sp ecial forward error-correction tech n iq u e th at creates an ad d ition al bit for each p acket of 4. Th is extra ch eck bit is u sed to allow on -th e-fly error correction to take p lace at th e receivin g en d of th e tran sm ission . It also greatly in creases th e resistan ce of V.32 to n oise on th e telep h on e lin e. In th e p ast, V.32 h as been exp en sive to im p lem en t becau se th e tech n ology it req u ires is com p lex. Becau se a on e-way, 9600bp s stream u ses alm ost th e en tire ban d wid th of th e p h on e lin e, V.32 m od em s im p lem en t ech o can cellation , m ean in g th at th ey can cel ou t th e overlap p in g sign al th at th eir own m od em s tran sm it an d ju st listen to th e oth er m od em ’s sign al. Th is p roced u re is com p licated an d was at on e tim e costly. Ad van ces in

Asynchronous M odems

lower-cost ch ip sets th en m ad e th ese m od em s in exp en sive, an d th ey were th e de facto 9,600bp s stan d ard for som e tim e. V.3 2 b i s. V.32bis is a 14,400bp s exten sion to V.32. Th is p rotocol u ses TCQAM m od u lation at 2,400 bau d to tran sm it 6 bits p er bau d , for an effective rate of 14,400bp s. Th e trellis cod in g m akes th e con n ection m ore reliable. Th is p rotocol is also a fu ll-d u p lex m od u lation p rotocol, with a fallback to V.32 if th e p h on e lin e is im p aired . V.3 2 f a st . V.32fast, or V.FC (Fast Class) as it is also called , is a stan d ard th at was d evelop ed by Rockwell an d in trod u ced before V.34. V.32fast is an exten sion to V.32 an d V.32bis, bu t offers a tran sm ission sp eed of 28,800bp s. It h as sin ce been su p ersed ed by V.34. If you bu y a u sed 28,800bp s m od em , m ake su re th at it is n ot on e of th e d evices th at su p p orts V.32fast an d n ot V.34. Mod em s like th is are in com p atible with m an y of th e V.34 d evices n ow in gen eral u se. V.3 4 . V.34 h as su p ersed ed all th e oth er 28.8Kbp s stan d ard s an d is th e cu rren t state-ofth e-art in p u rely an alog m od em com m u n ication s. It h as been p roven as th e m ost reliable stan d ard of com m u n ication at 28.8Kbp s. A recen t an n ex to th e V.34 stan d ard also d efin es op tion al h igh er sp eed s of 31.2 an d 33.6Kbp s. Most of th e V.34 m od em s n ow bein g p rod u ced are cap able of tran sm ittin g at th ese h igh er sp eed s, an d existin g V.34 m od em s th at are d esign ed u sin g sop h isticated Digital Sign al Processors (DSPs) can easily be u p grad ed to 33.6Kbp s. In m ost cases, you d o th is by d own load in g a Mod em ROM u p grad e from th e m an u factu rer an d th en ru n n in g a p rogram to “flash ” th e m od em ’s ROM with th e n ew cod e. V.34 is th e fastest com m u n ication n ow p ossible over an an alog serial con n ection . Becau se of lim itation s in h eren t in th e telep h on e system , it is also very likely to be th e fastest th at p u rely an alog com m u n ication s are goin g to get. Th e 56k stan d ard s th at rep resen t th e n ext in crem en t in m od em com m u n ication sp eed req u ire a d igital con n ection at on e en d , an d are th erefore n ot p u rely an alog. Oth er h igh -sp eed com m u n ication tech n ologies su ch as ISDN an d cable n etwork con n ection s esch ew an alog com m u n ication s en tirely, so th ey can n ot be called m od em s. V.9 0 . V.90 is th e ITU-T d esign ation for a 56Kbp s com m u n ication stan d ard th at recon ciles th e con flict between th e U.S. Robotics (3Com ) X2 an d Rockwell K56Flex m od em sp ecification s. See “56K Mod em s,” later in th is ch ap ter, for m ore in form ation . Error-Correct ion Prot ocols. Error correction refers to th e cap ability of som e m od em s to id en tify errors d u rin g a tran sm ission , an d to au tom atically resen d d ata th at ap p ears to h ave been d am aged in tran sit. Alth ou gh it is also p ossible to im p lem en t error correction u sin g software, th is p laces an ad d ition al bu rd en on th e com p u ter’s exp an sion bu s an d p rocessor. By p erform in g error correction u sin g d ed icated h ard ware in th e m od em , errors are d etected an d corrected before an y d ata is p assed to th e com p u ter’s CPU. As with m od u lation , both m od em s m u st ad h ere to th e sam e stan d ard for error correction to work. Fortu n ately, m ost m od em m an u factu rers u se th e sam e error correction p rotocols.

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MNP 1 -4 . Th is is a p rop rietary stan d ard th at was d evelop ed by Microcom to p rovid e basic error correction . Th e Microcom Networkin g Protocol (MNP) is exam in ed in greater d etail in th e “Prop rietary Stan d ard s” section , later in th is ch ap ter. V.4 2 . V.42 is an error-correction p rotocol, with fallback to MNP 4, an d version 4 is an error-correction p rotocol as well. Becau se th e V.42 stan d ard in clu d es MNP com p atibility th rou gh Class 4, all MNP 4-com p atible m od em s can establish error-con trolled con n ection s with V.42 m od em s. Th is stan d ard u ses a p rotocol called LAPM (Link Access Procedure for Modem s). LAPM, like MNP, cop es with p h on e-lin e im p airm en ts by au tom atically retran sm ittin g d ata corru p ted d u rin g tran sm ission , assu rin g th at on ly error-free d ata p asses between th e m od em s. V.42 is con sid ered to be better th an MNP 4 becau se it offers ap p roxim ately a 20% h igh er tran sfer rate d u e to its m ore in telligen t algorith m s. Dat a-Com pression St andards. Data com pression refers to a bu ilt-in cap ability in som e m od em s to com p ress th e d ata th ey’re sen d in g, th u s savin g tim e an d m on ey for m od em u sers. Dep en d in g on th e typ e of files th e m od em is sen d in g, d ata can be com p ressed to n early on e-fou rth its origin al size, effectively q u ad ru p lin g th e sp eed of th e m od em . For exam p le, a 14400bp s m od em with com p ression can yield tran sm ission rates of u p to 57600bp s, an d a 28800bp s can yield u p to 115200bp s. As with error correction , d ata com p ression can also be p erform ed with software. Data can on ly be com p ressed on ce, so if you are tran sm ittin g files th at are alread y in a com p ressed form , su ch as ZIP arch ives or GIF im ages, th ere will be n o p alp able in crease in sp eed from th e m od em ’s h ard ware com p ression . Th e tran sm ission of p lain text files an d u n com p ressed bitm ap s, h owever, is accelerated greatly by m od em com p ression . MNP 5 . Microcom con tin u ed th e d evelop m en t of its MNP p rotocols to in clu d e a com p ression p rotocol called MNP 5. Th is p rotocol is exam in ed m ore fu lly in th e section “Prop rietary Protocols,” later in th is ch ap ter. V.4 2 b i s. V.42bis is a CCITT d ata-com p ression stan d ard sim ilar to MNP Class 5, bu t p rovid in g abou t 35% better com p ression . V.42bis is n ot actu ally com p atible with MNP Class 5, bu t n early all V.42bis m od em s in clu d e th e MNP 5 d ata-com p ression cap ability as well. Th is p rotocol can som etim es q u ad ru p le th rou gh p u t, d ep en d in g on th e com p ression tech n iq u e. Th is fact h as led to som e d ecep tive ad vertisin g; for exam p le, a 2400bp s V.42bis m od em m igh t ad vertise “9600bp s th rou gh p u t” by in clu d in g V.42bis as well, bu t th is wou ld be p ossible in on ly extrem ely op tim istic cases, su ch as wh en sen d in g text files th at are very loosely p acked . In th e sam e m an n er, m an y 9600bp s V.42bis m akers n ow ad vertise “u p to 38.4Kbp s th rou gh p u t” by virtu e of th e com p ression . Ju st m ake su re th at you see th e tru th beh in d su ch claim s. V.42bis is su p erior to MNP 5 becau se it an alyzes th e d ata first an d th en d eterm in es wh eth er com p ression wou ld be u sefu l. V.42bis on ly com p resses d ata th at n eed s com p ression . MNP 5 always attem p ts to com p ress th e d ata, wh ich slows d own th rou gh p u t on p reviou sly com p ressed files.

Asynchronous M odems

To n egotiate a stan d ard con n ection u sin g V.42bis, V.42 also m u st be p resen t. Th erefore, a m od em with V.42bis d ata com p ression is assu m ed to in clu d e V.42 error correction . W h en com bin ed , th ese two p rotocols resu lt in an error-free con n ection th at h as th e m axim u m d ata com p ression p ossible. Propriet ary St andards. In ad d ition to th e in d u stry-stan d ard p rotocols for m od u lation , error correction , an d d ata com p ression th at are gen erally d efin ed an d ap p roved by th e ITU-T, several p rotocols in th ese areas were in ven ted by variou s com p an ies an d in clu d ed in th eir p rod u cts with ou t an y official en d orsem en t by an y stan d ard s bod y. Som e of th ese p rotocols h ave been q u ite p op u lar at tim es an d becam e p seu d o-stan d ard s of th eir own . Th e m ost su ccessfu l p rop rietary p rotocols are th e MNP (Microcom Networkin g Protocol) stan d ard s d evelop ed by Microcom . Th ese error-correction an d d ata-com p ression p rotocols are su p p orted wid ely by oth er m od em m an u factu rers as well. An oth er com p an y th at h as been su ccessfu l in establish in g p rop rietary p rotocols as lim ited stan d ard s is U.S. Robotics (n ow p art of 3COM), with its HST (h igh -sp eed tech n ology) m od u lation p rotocols. Becau se of an aggressive m arketin g cam p aign with BBS op erators, HST m od em s cap tu red a large p ortion of th e m arket in th e 1980s. Th e followin g section s exam in e th ese an d oth er p rop rietary m od em p rotocols. H ST. HST is a 14,400bp s an d 9,600bp s m od ified h alf-d u p lex p rop rietary m od u lation p rotocol d evelop ed by U.S. Robotics. Alth ou gh com m on ly u sed by BBSs in th e 1980s, th e HST was m ad e all bu t extin ct by th e in trod u ction of V.32 m od em s at very com p etitive p rices. HST m od em s ru n at 9,600bp s or 14,400bp s in on e d irection an d 300bp s or 450bp s in th e oth er d irection . Th is is an id eal p rotocol for in teractive session s. Becau se ech ocan cellation circu itry is n ot req u ired , costs are lower. U.S. Robotics also m arketed m od em s th at u sed th e ITU-T stan d ard p rotocols an d th e U.S. Robotics p rop rietary stan d ard . Th ese d u al-stan d ard m od em s in corp orated both V.32bis an d HST p rotocols, givin g you th e best of th e stan d ard an d p rop rietary world s an d en ablin g you to con n ect to virtu ally an y oth er system at th e m axim u m com m u n ication s rate. Th ey were at on e tim e am on g th e best m od em s available; I u sed an d recom m en d ed th em for m an y years. D IS. DIS is a 9,600bp s p rop rietary m od u lation p rotocol by Com p u Com , wh ich u ses dynam ic im pedance stabilization (DIS), with claim ed su p eriority in n oise rejection over V.32. Im p lem en tation was very in exp en sive, bu t like HST, on ly on e com p an y m ad e m od em s th at su p p orted th e DIS stan d ard . Becau se of th e lower costs of V.32 an d V.32bis, th is p rop rietary stan d ard q u ickly d isap p eared . MNP . MNP offers en d -to-en d error correction , m ean in g th at th e m od em s are cap able of d etectin g tran sm ission errors an d req u estin g retran sm ission of corru p ted d ata. Som e levels of MNP also p rovid e d ata com p ression . As MNP evolved , d ifferen t classes of th e stan d ard were d efin ed , d escribin g th e exten t to wh ich a given MNP im p lem en tation su p p orts th e p rotocol. Most cu rren t

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im p lem en tation s su p p ort Classes 1 th rou gh 5. High er classes u su ally are u n iq u e to m od em s m an u factu red by Microcom , In c. becau se th ey are p rop rietary. MNP gen erally is u sed for its error-correction cap abilities, bu t MNP Classes 4 an d 5 also p rovid e p erform an ce in creases, with Class 5 offerin g real-tim e d ata com p ression . Th e lower classes of MNP are n ot im p ortan t to tod ay’s m od em u ser, bu t th ey are in clu d ed in th e followin g list for th e sake of com p leten ess: ■ MNP Class 1 (block m ode) u ses asyn ch ron ou s, byte-orien ted , h alf-d u p lex (on e-way) tran sm ission . Th is m eth od p rovid es abou t 70% efficien cy an d error correction on ly, so it’s rarely u sed tod ay. ■ MNP Class 2 (stream m ode) u ses asyn ch ron ou s, byte-orien ted , fu ll-d u p lex (two-way) tran sm ission . Th is class also p rovid es error correction on ly. Becau se of p rotocol overh ead (th e tim e it takes to establish th e p rotocol an d op erate it), th rou gh p u t at Class 2 is on ly abou t 84% of th at for a con n ection with ou t MNP, d eliverin g abou t 202 cp s (ch aracters p er secon d ) at 2,400bp s (240 cp s is th e th eoretical m axim u m ). Class 2 is u sed rarely tod ay. ■ MNP Class 3 in corp orates Class 2 an d is m ore efficien t. It u ses asyn ch ron ou s, bitorien ted , fu ll-d u p lex m eth od . Th e im p roved p roced u re yield s th rou gh p u t abou t 108% of th at of a m od em with ou t MNP, d eliverin g abou t 254 cp s at 2,400bp s. ■ MNP Class 4 is a p erform an ce-en h an cem en t class th at u ses Ad ap tive Packet Assem bly an d Op tim ized Data Ph ase tech n iq u es. Class 4 im p roves th rou gh p u t an d p erform an ce by abou t 5%, alth ou gh actu al in creases d ep en d on th e typ e of call an d con n ection , an d can be as h igh as 25% to 50%. ■ MNP Class 5 is a d ata-com p ression p rotocol th at u ses a real-tim e ad ap tive algorith m . It can in crease th rou gh p u t u p to 50%, bu t th e actu al p erform an ce of Class 5 d ep en d s on th e typ e of d ata bein g sen t. Raw text files allow th e h igh est in crease, alth ou gh p rogram files can n ot be com p ressed as m u ch an d th e in crease in th rou gh p u t is sm aller. On p recom p ressed d ata (files alread y com p ressed with PKZIP, for exam p le), MNP 5 d ecreases p erform an ce, an d th erefore was often d isabled on BBS system s an d on lin e services th at d ealt p rim arily with p recom p ressed files. V-Se ri e s. Th e Hayes V-series is a p rop rietary error-correction p rotocol by Hayes th at was u sed in som e of its m od em s. However, th e ad ven t of lower-cost V.32 an d V.32bis m od em s (even from Hayes) m ad e th e V-series all bu t extin ct. Th ese m od em s u sed a m od ified V.29 p rotocol, wh ich is som etim es called a ping-pong protocol becau se it h as on e h igh -sp eed ch an n el an d on e low-sp eed ch an n el th at altern ate back an d forth . CSP . Th e CSP (Com puCom Speed Protocol) is an error-correction an d d ata-com p ression p rotocol available on Com p u Com DIS m od em s. Fax M odem St andards. Facsim ile tech n ology is a scien ce u n to itself, alth ou gh it h as m an y sim ilarities to d ata com m u n ication s. Th ese sim ilarities h ave led to th e com bin ation of d ata an d fax cap abilities in to th e sam e m od em . Virtu ally all th e m od em s on th e m arket tod ay su p p ort fax an d d ata com m u n ication s.

Asynchronous M odems

Over th e years, th e CCITT h as set in tern ation al stan d ard s for fax tran sm ission . Th is h as led to th e grou p in g of faxes in to on e of fou r grou p s. Each grou p (I th rou gh IV) u ses d ifferen t tech n ology an d stan d ard s for tran sm ittin g an d receivin g faxes. Grou p s I an d II are relatively slow an d p rovid e resu lts th at are u n accep table by tod ay’s stan d ard s, an d are th erefore n ot d iscu ssed in d etail h ere. Grou p III is th e u n iversal stan d ard in u se tod ay by virtu ally all fax m ach in es, in clu d in g th ose com bin ed with m od em s. Th e Gro u p III Fa x P ro t o c o l . Th e Grou p III p rotocol sp ecifies a m axim u m fax tran sm ission rate of 9,600 bau d an d two levels of im age resolu tion : stan d ard (203×98 p ixels) an d fin e (303×196 p ixels). Th e p rotocol also calls for th e u se of a d ata-com p ression p rotocol d efin ed by th e CCITT (called T.4.) an d V.29 m od u lation . Th ere are two gen eral su bd ivision s with in th e Grou p III fax stan d ard —Class 1 an d Class 2. Th e d ifferen ce between th e two is th at in Class 1 faxin g, th e fax software gen erates th e im ages an d h an d les th e session p rotocol an d tim in g with th e receivin g system . In Class 2, th e software gen erates an im age for each p age an d p asses it to th e fax m od em , wh ich h an d les th e session p rotocol an d tim in g. Th u s, with Class 1, com p atibility with oth er fax d evices is m ore th e resp on sibility of th e software, wh ile with Class 2, com p atibility is m ore th e resp on sibility of th e m od em . W h ile both classes call for ad d ition al fax-related AT com m an d s to be recogn ized an d acted u p on by th e m od em , th e Class 2 com m an d set is m u ch larger, con sistin g of over 40 n ew in stru ction s. Th e Class 1 sp ecification was read ily accep ted an d ratified by th e CCITT in 1988, bu t th e Class 2 d ocu m en t was rejected rep eated ly. However, som e m an u factu rers h ave d esign ed Class 2 m od em s u sin g th e d raft (th at is, u n ratified ) version of th e stan d ard . Tod ay, n early all fax m od em s su p p ort th e Grou p III, Class 1 stan d ard , an d th is sh ou ld be th e m in im u m accep table req u irem en t for an y fax m od em you in ten d to p u rch ase. Class 2 su p p ort is an ad d ition al ben efit, bu t by itself d oes n ot p rovid e th e alm ost u n iversal com p atibility of Class 1. Th e Gro u p IV Fa x P ro t o c o l . W h ereas Grou p s I th rou gh III are an alog in n atu re (su ch as m od em s) an d are d esign ed to u se stan d ard an alog telep h on e lin es, th e Grou p IV sp ecification calls for th e d igital tran sm ission of fax im ages an d req u ires an ISDN or oth er d igital con n ection to th e d estin ation system . Grou p IV su p p orts fax resolu tion s of u p to 400 d p i an d u ses a n ewer CCITT d ata com p ression p rotocol called T.6. For a d igital solu tion su ch as Grou p IV faxin g to fu n ction , th e con n ection between th e sou rce an d th e d estin ation system m u st be fu lly d igital. Th is m ean s th at even th ou gh you r office m ay u se a PBX-based telep h on e system th at is d igital, an d you r telep h on e carrier m ay u se d igital con n ection s, it is very likely th at th ere is at least som e an alog com m u n ication in volved in th e circu it, su ch as between th e PBX an d th e local telep h on e service. Un til th e telep h on e system h as been con verted to a fu lly d igital n etwork (a m on u m en tal task), Grou p IV fax system s will n ot be able to rep lace Grou p III system s. 56K M odem s In th e ever-con tin u in g q u est for sp eed , m od em m an u factu rers h ave overcom e wh at was con sid ered to be an u n breakable ceilin g for asyn ch ron ou s d ata tran sfer rates over

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stan d ard telep h on e lin es, an d h ave released m od em s th at su p p ort sp eed s of u p to 56,000bp s (or 56Kbp s). To u n d erstan d h ow th is ad d ition al sp eed was ach ieved , you m u st con sid er th e basic p rin cip le of m od em tech n ology, th at is, th e d igital-to-an alog con version . As you ’ve learn ed , a trad ition al m od em con verts d ata from d igital to an alog form so it can travel over th e Pu blic Switch ed Telep h on e Network (PSTN). At th e d estin ation system , an oth er m od em con verts th e an alog d ata back to its d igital form . Th is con version from d igital to an alog an d back cau ses som e sp eed loss. Even th ou gh th e p h on e lin e is p h ysically cap able of carryin g d ata at 56Kbp s or m ore, th e effective m axim u m sp eed becau se of th e con version s is abou t 33.6Kbp s. A m an by th e n am e of Sh an n on cam e u p with a law (Sh an n on ’s Law) statin g th at th e m axim u m p ossible error-free d ata com m u n ication s rate over th e PSTN is ap p roxim ately 35Kbp s, d ep en d in g on th e n oise p resen t. However, Sh an n on ’s Law assu m es a fu lly an alog con n ection between th e two m od em s. Th at is n ot th e case in m ost of th e Un ited States tod ay. In u rban areas, m ost circu its are d igital u n til th ey reach th e telep h on e com p an y’s cen tral office (CO), to wh ich you r p h on e lin e is con n ected . Th e CO con verts th e d igital sign al in to an an alog sign al before sen d in g it to you r h om e. Con sid erin g th e fact th at th e p h on e system is largely d igital, you can —in som e cases— om it th e in itial d igital-to-an alog con version an d sen d a p u rely d igital sign al over th e PSTN to th e recip ien t’s CO. Th u s, th ere is on ly on e d igital-to-an alog con version n eed ed , in stead of two or m ore. Th e resu lt is th at you can th eoretically in crease th e sp eed of th e d ata tran sm ission , in on e d irection on ly, beyon d th e 35Kbp s sp ecified by Sh an n on ’s Law, to n early th e 56Kbp s sp eed su p p orted by th e telep h on e n etwork. Th e tran sm ission in th e oth er d irection is still lim ited to th e V.34 m axim u m of 33.6Kbp s. 56K Lim it at ions. Th u s, 56K m od em s can in crease d ata tran sfer sp eed s beyon d th e lim its of V.34 m od em s, bu t th ey are su bject to certain lim itation s. Un like stan d ard m od em tech n ologies, you can n ot bu y two 56K m od em s, in stall th em on two com p u ters, an d ach ieve 56Kbp s sp eed s. On e sid e of th e con n ection m u st u se a sp ecial d igital m od em th at con n ects d irectly to th e PSTN with ou t a d igital-to-an alog con version . 56K m od em s, th erefore, can be u sed on ly to con n ect to In tern et service p rovid ers or oth er h ostin g services th at h ave in vested in th e n ecessary in frastru ctu re to su p p ort th e con n ection . Becau se th e ISP h as th e d igital con n ection to th e PSTN, its d own stream tran sm ission s to you r com p u ter are accelerated , wh ile you r com m u n ication s back to th e ISP are n ot. On a p ractical level, th is m ean s you can su rf th e W eb an d d own load files m ore q u ickly, bu t if you h ost a W eb server on you r PC, you r u sers will realize n o sp eed gain , becau se th e u p stream traffic is n ot accelerated . Also, th ere can on ly be on e d igital-to-an alog con version in th e d own stream con n ection from th e ISP to you r com p u ter. Th is is d ictated by th e n atu re of th e p h ysical con n ection to you r local telep h on e carrier. If ad d ition al con version s are in volved in you r con n ection , th en 56K tech n ology will n ot work for you ; 33.6Kbp s will be you r m axim u m

Asynchronous M odems

p ossible sp eed . Several m od em m an u factu rers h ave m ad e software available on th e In tern et th at tests you r p h on e lin e an d d eterm in es wh eth er it can accom m od ate 56Kbp s con n ection s.

Caut ion 56K modem communications are also highly susceptible to slowdowns caused by line noise. Your telephone line may be perfectly adequate for voice communications, and even lower-speed modem communications, but inaudible noise can easily degrade a 56K connection to the point at which there is only a marginal increase over a 33.6Kbps modem, or even no increase at all.

56K St andards. To ach ieve a h igh -sp eed con n ection , both m od em s an d you r ISP’s (or oth er h ostin g service to wh ich you con n ect), m u st su p p ort th e sam e 56K tech n ology, an d h ere rises th e biggest issu e su rrou n d in g 56K com p atibility. As is often th e case, m od em m an u factu rers were an xiou s to brin g th e latest tech n ology to m arket, so two com p an ies released p rod u cts u sin g com p etin g 56K stan d ard s. U.S. Robotics (n ow p art of 3COM) in trod u ced a lin e of 56K m od em s u sin g Texas In stru m en ts ch ip sets th at th ey called X 2, wh ile Rockwell, a m an u factu rer of m od em ch ip sets, released an oth er 56K stan d ard th at it called K56flex. Natu rally, th ese two stan d ard s were n ot com p atible, an d th e rest of th e m od em in d u stry rap id ly p olarized , su p p ortin g on e stan d ard or th e oth er. Th e resu lt was a latter-d ay version of th e Beta-VHS con flict of th e 1970s.

Not e To complicate matters further, it was discovered only days before U.S. Robotics shipped its first X2 modems that an old FCC regulation known as Part 68 specifies the maximum amount of power that you can run through a PSTN phone line. Because faster communications require more power, this regulation effectively limits modem communications to a maximum speed of approximately 53Kbps. The regulation was created because increasing the power transmitted over a line beyond a certain point causes increased interference, called crosstalk, on neighboring lines. The FCC implemented this regulation long ago, not intending it to apply specifically to modems, and is currently re-evaluating its position.

As a resu lt of h avin g two stan d ard s, u sers were forced eith er to wait an d see wh ich tech n ology th eir ISPs wou ld ad op t, or com m it to on e of th e two stan d ard s an d th en fin d an ISP th at su p p orted it. Becau se th e in vestm en t in 56K tech n ology was so m u ch m ore su bstan tial for an ISP, m an y of th em waited to see wh ich of th e two stan d ard s wou ld win ou t by becom in g eith er a de facto or a de jure stan d ard . V.90. Fortu n ately, th is p roblem is in th e p rocess of bein g resolved . On Febru ary 5, 1998, th e ITU-T ap p roved a “d eterm in ation ” for a 56K m od em stan d ard called V.90. A d eterm in ation in d icates th at th e tech n ical asp ects of th e stan d ard are in p lace, an d fin al ratification of th e stan d ard is exp ected in th e fall of 1998. Now th at an official stan d ard exists, all m od em m an u factu rers will u p grad e th eir p rod u cts to su p p ort V.90, an d in terop erability between d evices su p p ortin g th e two earlier stan d ard s sh ou ld be p ossible.

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Becau se th e X2 an d K56flex im p lem en tation s are fu n d am en tally sim ilar in th e h ard ware req u irem en ts d escribed earlier, it sh ou ld be p ossible to m od ify existin g m od em s of eith er typ e to su p p ort V.90 by u p grad in g th eir firm ware u sin g a flash u p d ate or a sim p le ch ip rep lacem en t. However, th is is for th e in d ivid u al m od em m an u factu rers to d ecid e. M odem Recom m endat ions A m od em for a PC can take th e form eith er of an extern al d evice with its own p ower su p p ly th at p lu gs in to a PC’s serial p ort, or an in tern al exp an sion card th at you in sert in to a bu s slot in sid e th e com p u ter. Most m an u factu rers of m od em s h ave both in tern al an d extern al version s of th e sam e m od els. Extern al version s are sligh tly m ore exp en sive becau se th ey in clu d e a sep arate case an d p ower su p p ly. Both are eq u ally fu n ction al, h owever, an d th e d ecision as to wh ich typ e you u se sh ou ld typ ically d ep en d on wh eth er you h ave a free bu s slot or serial p ort, h ow m u ch room you h ave on you r d esk, th e cap abilities of you r system ’s in tern al p ower su p p ly, an d h ow com fortable you are with op en in g u p you r com p u ter. I h ave often p referred extern al m od em s becau se of th e visu al feed back th ey p rovid e th rou gh in d icator ligh ts. Th ese ligh ts m ake it easy to see if th e m od em is still con n ected an d tran sm ittin g or receivin g d ata. However, som e com m u n ication p rogram s tod ay in clu d e on screen sim u lation s of th e ligh ts, p rovid in g th e sam e in form ation . Th ere are oth er situ ation s, too, wh ere an in tern al m od em is p referable. In case you r com p u ter’s serial p orts d o n ot h ave bu ffered UART ch ip s su ch as th e 16550, m an y in tern al m od em s in clu d e an on board 16550 UART. Th is on board UART with th e m od em saves you th e trou ble of u p grad in g th e UART serial p ort. Also, extern al 56K m od em s can be h am p ered from ach ievin g th eir fu ll sp eed by th e lim itation s of th e com p u ter’s serial p ort. An in tern al m od el m ay be p referable in stead . √√ See “ UARTs,” p. 587

Not all m od em s th at fu n ction at th e sam e sp eed h ave th e sam e fu n ction ality. Man y m od em m an u factu rers p rod u ce m od em s ru n n in g at th e sam e sp eed , bu t with d ifferen t featu re sets at d ifferen t p rice p oin ts. Th e m ore exp en sive m od em s u su ally su p p ort ad van ced featu res su ch as d istin ctive rin g su p p ort an d caller ID. W h en p u rch asin g a m od em , be su re th at it su p p orts all th e featu res you n eed . It’s also a good id ea to m ake su re th e software you p lan to u se, in clu d in g th e op eratin g system , h as been certified for u se with th e m od em you select. Most of th e bran d -n am e m od em s on th e m arket tod ay su p p ort a wid e ran ge of m od u lation , error-correction , an d d ata-con n ection stan d ard s. Th is is becau se m ost m od em s are auto-negotiating; th at is, wh en th ey con n ect to an oth er m od em th ey im p lem en t th e m ost efficien t set of p rotocols th ey h ave in com m on . Even if th e two m od em s d o n ot agree on th e m ost ad van ced p rotocol of a p articu lar typ e, th ey are likely to h ave at least on e p rotocol in com m on .

Integrated Services Digital Network (ISDN)

As to sp eed , th e on ly reason to avoid a 56K m od em was th e con flict between th e X2 an d K56flex stan d ard s. On ce th e m an u factu rers on both sid es h ave im p lem en ted V.90, th ere will be n o reason n ot to bu y th ese m od em s. Th e p rice d ifferen ce between a V.90 an d a V.34 will be m in im al, an d even if you can n ot im m ed iately m ake u se of 56K cap abilities, you still get th e 33.6Kbp s sp eed p rovid ed by V.34 an d th e cap ability to ru n at 56K wh en you r situ ation allows it.

Int egrat ed Services Digit al Net w ork ( ISDN) To get p ast th e sp eed lim itation s of asyn ch ron ou s m od em s, you h ave to go com p letely d igital, an d ISDN is th e n ext step in telecom m u n ication s. ISDN m akes th e break from th e old tech n ology of an alog d ata tran sfer to th e n ewer d igital d ata tran sfer. W ith ISDN, you can con n ect to th e In tern et at sp eed s of u p to 128Kbp s. ISDN h as been available for over 10 years bu t h as on ly recen tly becom e a p ractical solu tion for p rivate u sers. Th is was m ostly d u e to th e d ifficu lties in volved in arran gin g for th e in stallation of th e service with th e telep h on e com p an y. Two years ago, it was d ifficu lt to fin d som eon e at m ost region al p h on e com p an ies wh o h ad even h eard of ISDN, bu t th ere are n ow q u ite a few bu sin esses th at p rovid e tu rn key solu tion s, in clu d in g ISP services, ISDN h ard ware, an d n egotiation s with th e p h on e com p an y. W h ile it can be u sed for voice com m u n ication s, ISDN is n ot like a n orm al telep h on e con n ection , even th ou gh it u ses you r existin g telep h on e wirin g. To ach ieve h igh sp eed s, both en d s of th e con n ection m u st be d igital, so you wou ld typ ically set u p an ISDN lin e sp ecifically for con n ectin g to an In tern et service p rovid er th at also u ses ISDN. Bu sin esses also u se h igh er ban d wid th ISDN con n ection s for In tern et access or to con n ect local area n etworks in rem ote offices. ISDN is also n ot like a leased telep h on e lin e, h owever, wh ich p erm an en tly con n ects two sp ecific location s. You r software still d ials th e n u m ber of you r in ten d ed d estin ation (alth ou gh it is a sp ecial ISDN n u m ber), an d breaks th e con n ection (th at is, h an gs u p ) wh en th e session is fin ish ed . Th u s, you can ch an ge to a d ifferen t ISP th at su p p orts ISDN, if n ecessary, with ou t d ealin g with th e p h on e com p an y again . ISDN Services On an ISDN con n ection , ban d wid th is d ivid ed in to bearer channels (B ch an n els) th at ru n at 64Kbp s an d a delta channel (D ch an n el) th at ru n s at 16Kbp s or 64Kbp s, d ep en d in g on th e typ e of service. Th e B ch an n els carry voice tran sm ission s or u ser d ata, an d th e D ch an n el carries con trol traffic. Th ere are two typ es of ISDN service: Basic Rate In terface (BRI) an d Prim ary Rate In terface (PRI). Th e BRI service is in ten d ed for p rivate an d h om e u sers an d con sists of two B ch an n els an d on e 16Kbp s D ch an n el, for a total of 144Kbp s. Th e PRI service is orien ted m ore toward bu sin ess u se, su ch as for PBX con n ection s to th e telep h on e com p an y’s CO. In North Am erica an d Jap an , th e PRI service con sists of 23 B ch an n els an d on e 64Kbp s D ch an n el for a total of 1536Kbp s, ru n n in g over a stan d ard T1 in terface. In Eu rop e, th e PRI

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service is 30 B ch an n els an d on e 64Kbp s D ch an n el, totalin g 1,984Kbp s, corresp on d in g to th e E1 telecom m u n ication s stan d ard . For bu sin esses th at req u ire m ore ban d wid th th an on e PRI con n ection p rovid es, it’s p ossible to u se on e D ch an n el to su p p ort m u ltip le PRI ch an n els u sin g Non-Facility Associated Signaling (NFAS).

Not e When speaking of ISDN connections, one kilobyte equals 1,000 bytes, not 1,024 bytes as in standard computer applications.

It is p ossible to aggregate th e ban d wid th of m u ltip le B ch an n els u sin g a p rotocol su ch as Multilink PPP or BONDING (d evelop ed by th e Ban d wid th ON Dem an d INterop erability Grou p ), so you can u se th e BRI service to establish a sin gle 128Kbp s con n ection to th e In tern et. You can also con n ect m u ltip le d evices to a sin gle ISDN con n ection an d tran sm it m u ltip le sign als to d ifferen t d estin ation s at th e sam e tim e, th u s rep lacin g several stan d ard telep h on e lin es. To h ave an ISDN con n ection in stalled , you m u st be with in 18,000 feet (abou t 3.4 m iles or 5.5 km ) of th e CO for th e BRI service. For greater d istan ces, exp en sive rep eater d evices are n eed ed , an d som e telep h on e com p an ies m ay n ot offer th e service at all. Most of th e existin g telep h on e wirin g in th e Un ited States is cap able of su p p ortin g ISDN com m u n ication s, so you u su ally n eed n ot p ay for th e in stallation of n ew telep h on e cable. Prices for ISDN service vary wid ely, d ep en d in g on you r location . In th e Un ited States, th e in itial in stallation fee can be in th e area of $100–$150, d ep en d in g on wh eth er you are con vertin g an existin g lin e or in stallin g a n ew on e. Th e m on th ly ch arges are typ ically $30–$50, an d often th ere is a con n ect-tim e ch arge as well, ran gin g from 1 to 6 cen ts p er m in u te. Keep in m in d th at you also m u st p u rch ase an ISDN term in al ad ap ter for you r PC an d p ossibly oth er h ard ware as well, an d th at th ese ch arges are on ly for th e telep h on e com p an y’s ISDN service. You m u st also p ay you r ISP for access to th e In tern et at ISDN sp eed s. ISDN Hardw are To con n ect a PC to an ISDN con n ection , you m u st h ave a h ard ware com p on en t called a term inal adapter (TA). Th e term in al ad ap ter takes th e form of an exp an sion board or an extern al d evice con n ected to a serial p ort, m u ch like a m od em . In fact, term in al ad ap ters are often m istaken ly referred to as ISDN m od em s. Actu ally, th ey are n ot m od em s at all, becau se th ey d o n ot p erform an alog/ d igital con version s. Th ere are two d ifferen t in terfaces to th e ISDN service. Th e U-Interface con sists of a sin gle p air of wires lead in g to th e telep h on e com p an y’s CO. Th e Subscriber/Term ination (S/T) Interface con sists of two p airs of wires th at typ ically ru n from a wall jack to you r term in al ad ap ter. Th e d evice th at con verts th e U-In terface sign al to th e S/ T In terface is called a network term ination device, or NT-1. Som e term in al ad ap ters in clu d e an NT-1 in tegrated in to th e h ard ware, en ablin g you to con n ect th e U-In terface d irectly to th e com p u ter. Th is is an excellen t solu tion as lon g as th e com p u ter is th e on ly d evice th at you p lan to con n ect to th e ISDN lin e. If you wan t to

CATV Networks

con n ect m u ltip le d evices, or if you r term in al ad ap ter d oes n ot in clu d e an NT-1, th en you m u st p u rch ase an NT-1 sep arately. An oth er altern ative is to get a n etwork-read y term in al ad ap ter th at you can con n ect to you r cu rren t NIC. Th is is an esp ecially good altern ative if you h ave several PCs, as you can sh are on e TA am on g th em .

Caut ion When purchasing an ISDN terminal adapter, you will almost always want to purchase an internal version. A terminal adapter with compression can easily exceed a serial port’s capability to reliably send and receive data. Consider that even a moderate 2:1 compression ratio exceeds the maximum rated speed of 232Kbps that most high-speed COM ports support.

Leased Lines For u sers with h igh ban d wid th req u irem en ts (an d d eep p ockets), d ed icated leased lin es p rovid e d igital service between two location s at sp eed s th at can far exceed ISDN. A leased lin e is a p erm an en t 24-h ou r con n ection to a p articu lar location th at can on ly be ch an ged by th e telep h on e com p an y. Bu sin esses u se leased lin es to con n ect LANs in rem ote location s or to con n ect to th e In tern et th rou gh a service p rovid er. Leased lin es are available at variou s sp eed s, as d escribed in th e followin g section s. T-1 Connect ions To con n ect n etworks in d istan t location s, n etworks th at m u st su p p ort a large n u m ber of In tern et u sers, or esp ecially organ ization s th at will be h ostin g th eir own In tern et services, a T-1 con n ection m ay be th e wise in vestm en t. A T-1 is a d igital con n ection ru n n in g at 1.55Mbp s. Th is is m ore th an 10 tim es faster th an an ISDN lin k. A T-1 m ay be sp lit (or fractioned), d ep en d in g on h ow it is to be u sed . It can be sp lit in to 24 in d ivid u al 64Kbp s lin es, or left as a sin gle h igh -cap acity p ip elin e. Som e In tern et service p rovid ers allow you to lease an y p ortion of a T-1 con n ection th at you wan t (in 64Kbp s in crem en ts). T-1 lin ks in th e Un ited States u su ally cost several th ou san d d ollars p er m on th , p lu s a su bstan tial in stallation fee. Bu t, for a large organ ization th at req u ires a lot of ban d wid th , it can be m ore econ om ical to in stall a h igh er-cap acity service an d grow in to it, rath er th an con stan tly u p grad e th e lin k. T-3 Connect ions Eq u ivalen t in th rou gh p u t to ap p roxim ately 30 T-1 lin es, a T-3 con n ection ru n s at 45Mbp s, an d is su itable for u se by very large n etworks an d u n iversity cam p u ses. Pricin g in form ation falls in to th e “if you h ave to ask, you can ’t afford it” category.

CATV Net w orks Alth ou gh ISDN rep resen ts a sign ifican t in crease in sp eed over stan d ard m od em tech n ologies, th e in stallation d ifficu lties an d th e exp en se (esp ecially wh en th ere are con n ect-tim e ch arges) m ay n ot be ju stified . Th e n ext step u p in sp eed is a cable TV (CATV) n etwork con n ection , an d th is service, wh en available, is u su ally less exp en sive th an ISDN.

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Cable M odem s As with ISDN, th e d evice u sed to con n ect a PC to a CATV n etwork is som ewh at in accu rately called a m od em . In fact, th e so-called cable m od em (a n am e I will con tin u e to u se, for th e sake of con ven ien ce) is actu ally a great d eal m ore. Th e d evice d oes in d eed m od u late an d d em od u late, bu t it also fu n ction s as a tu n er, a n etwork brid ge, an en cryp tor, an SNMP agen t, an d a h u b. To con n ect you r PC to a CATV n etwork, you d o n ot u se a serial p ort as with stan d ard m od em tech n ologies. In stead , you m u st in stall a stan d ard Eth ern et n etwork in terface ad ap ter in to a bu s slot. Th e Eth ern et ad ap ter con n ects to th e cable m od em with th e sam e typ e of twisted -p air cable u sed on local area n etworks. In fact, you r PC an d th e cable m od em actu ally form a two-n od e LAN, with th e m od em fu n ction in g as a hub. Th e cable m od em also con n ects to th e CATV n etwork u sin g th e sam e coaxial cable con n ection as you r cable TV service. Th u s, th e cable m od em fu n ction s as a bridge between th e tin y twisted -p air n etwork in you r h om e an d th e hybrid fiber/coax (HFC) n etwork th at con n ects all th e cable cu stom ers in you r n eigh borh ood . CATV Bandw idt h Cable TV u ses wh at is kn own as a broadband n etwork, m ean in g th at th e ban d wid th of th e con n ection is sp lit to carry m an y sign als at th e sam e tim e. Th ese variou s sign als corresp on d to th e variou s ch an n els you see on you r TV. A typ ical HFC n etwork p rovid es ap p roxim ately 750MHz of ban d wid th , an d each ch an n el req u ires 6MHz. Th erefore, sin ce th e television ch an n els start at abou t 50MHz, you wou ld fin d ch an n el 2 in th e 50MHz– 56MHz ran ge, ch an n el 3 at 57MHz–63MHz, an d con tin u in g on u p th e freq u en cy sp ectru m . At th is rate, an HFC n etwork can su p p ort abou t 110 ch an n els. For d ata n etworkin g p u rp oses, cable system s typ ically allocate on e ch an n el’s worth of ban d wid th in th e 50MHz–750MHz ran ge for d own stream traffic (th at is, traffic com in g in to th e cable m od em from th e CATV n etwork). In th is way, th e cable m od em fu n ction s as a tuner, ju st like you r cable TV box, en su rin g th at you r PC receives sign als from th e correct freq u en cy. Up stream traffic (d ata sen t from you r PC to th e n etwork) u ses a d ifferen t ch an n el. Cable TV system s com m on ly reserve th e ban d wid th from 5MHz to 42MHz for u p stream sign als of variou s typ es (su ch as th ose gen erated by cable TV boxes th at en able you to ord er p ayp er-view p rogram m in g). Dep en d in g on th e ban d wid th available, you m ay fin d th at you r CATV p rovid er d oes n ot fu rn ish th e sam e h igh sp eed u p stream as it d oes d own stream . Th is is called an asym m etrical n etwork.

Not e Because the upstream speed often does not match the downstream speed, and for other networkrelated reasons, cable TV connections are usually not practical for hosting World Wide Web servers and other Internet services. This is largely deliberate, as most CATV providers are currently targeting their traditional home user market. As the technology matures, however, this type of Internet connection is likely to spread to the business world as well.

CATV Networks

Th e am ou n t of d ata th rou gh p u t th at th e sin gle 6MHz d own stream ch an n el can su p p ort is d ep en d en t on th e typ e of m od u lation u sed at th e head end (th at is, th e system to wh ich you r PC con n ects over th e n etwork). Usin g a tech n ology called 64 QAM (q u ad ratu re am p litu d e m od u lation ), th e ch an n el m ay be able to carry u p to 27Mbp s of d own stream d ata. A varian t called 256 QAM can boost th is to 36Mbp s. You m u st realize, h owever, th at you will n ot ach ieve an yth in g even ap p roach in g th is th rou gh p u t on you r PC. First of all, th e Eth ern et ad ap ter u sed to con n ect to th e cable m od em is lim ited to 10Mbp s, bu t even th is is well beyon d th e real-life resu lts you will ach ieve. As with an y local area n etwork, you are sh arin g th e available ban d wid th with oth er u sers. All of you r n eigh bors wh o also su bscribe to th e service m ake u se of th e sam e 6MHz ch an n el. As m ore u sers are ad d ed , m ore system s are con ten d in g for th e sam e ban d wid th , an d th rou gh p u t goes d own . CATV Securit y Becau se you r PC is sh arin g a n etwork with oth er u sers in you r n eigh borh ood , an d becau se th e traffic is bid irection al, th e secu rity of you r PC an d th e n etwork becom es an issu e. In m ost cases, som e form of en cryp tion is in volved to p reven t u n au th orized access to th e n etwork. As with you r cable TV box, th e cable m od em m ay con tain en cryp tion circu itry th at is n eed ed to access th e n etwork. You r CATV p rovid er m ay also su p p ly en cryp tion software th at u ses a sp ecial p rotocol to log you on to th e n etwork. Th is p rotects th e CATV p rovid er from n on -p ayin g u sers, bu t it d oesn ’t p rotect you . If you u se an op eratin g system su ch as W in d ows 9x th at h as bu ilt-in p eer n etworkin g cap abilities, you m ay be able to see you r n eigh bors’ com p u ters on th e n etwork. Th e op eratin g system h as settin gs th at en able you to sp ecify wh eth er oth er n etwork u sers can access you r d rives. If th ese settin gs are con figu red im p rop erly, you r n eigh bors m ay be able to view, access, an d even d elete th e files on you r h ard d rives. Be su re th at th e tech n ician from th e cable com p an y in stallin g th e service ad d resses th is p roblem . CATV Perform ance Th e fact th at you are sh arin g th e CATV n etwork with oth er u sers d oesn ’t m ean th at th e p erform an ce of a cable m od em isn ’t u su ally sp ectacu lar. Typ ically, th e realized th rou gh p u t h overs arou n d 512Kbp s, alm ost 10 tim es th at of th e fastest m od em con n ection an d fou r tim es th at of ISDN. You will fin d th e W orld W id e W eb to be an en tirely n ew exp erien ce at th is sp eed . Th ose h u ge au d io an d vid eo clip s you avoid ed in th e p ast n ow d own load in secon d s, an d you will soon fill you r h ard d rives with all th e free software available. Ad d to th is th e fact th at th e service is typ ically q u ite reason ably p riced . Rem em ber th at th e CATV p rovid er is rep lacin g both th e telep h on e com p an y an d you r ISP in you r In tern et access solu tion . Th e p rice m ay be abou t $40 p er m on th , twice th at of a n orm al d ial-u p ISP accou n t, bu t it is far less th an ISDN, d oes n ot req u ire a telep h on e lin e, an d p rovid es you with 24-h ou r access to th e In tern et. Th e on ly d rawback is th at th e service m ay n ot yet be available in you r area. In m y op in ion , th is tech n ology exceed s all th e oth er In tern et access solu tion s available tod ay in sp eed , econ om y, an d con ven ien ce.

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Direct Cable Connect ions W h en you h ave a large am ou n t of d ata th at you wan t to tran sfer from on e com p u ter to an oth er in th e sam e room , you h ave several p ossible solu tion s. You can cop y th e d ata to flop p y d isks, bu t for an y m ore th an a few m egabytes, th is is n ot con ven ien t. Zip d rives an d oth er rem ovable d isk tech n ologies h old m ore d ata, bu t you m u st h ave th e sam e typ e of d rive on both system s, or m ove th e d rive from on e system to an oth er. A n etwork con n ection wou ld be th e fastest solu tion bu t is n ot worth settin g u p for occasion al or on e-tim e u se. Fin ally, you cou ld u se m od em s to d ial u p on e com p u ter from th e oth er an d tran sfer files. Th is m eth od also works, bu t req u ires two m od em s an d two telep h on e lin es. As an altern ative, you can establish a “m od em ” con n ection between th e two com p u ters with ou t u sin g m od em s! Usin g a sp ecial typ e of cable called a null m odem (or lap lin k) cable, you can con n ect th e serial or p arallel p orts on two com p u ters, form in g a sim p le two-n od e n etwork, an d tran sfer files between th em . Th is is p articu larly u sefu l wh en you h ave both a d esktop an d a lap top system on wh ich you wan t to u se th e sam e d ata. Null M odem Cables A n u ll m od em cable is a sp ecial cable th at h as its circu its crossed so th e tran sm it d ata (TD) p in on each serial p ort con n ector lead s to th e receive d ata (RD) p in on th e oth er. A cable th at con n ects th e system s’ p arallel p orts in th is way is called a bid irection al p arallel cable. Cables like th ese are u su ally available at an y com p u ter store th at sells cables. Th ey are som etim es called lap lin k cables, after on e of th e first software p rod u cts to in trod u ce th e con cep t of th e d irect cable con n ection . You can also bu ild you r own n u ll m od em or bid irection al p arallel cable u sin g th e wirin g d iagram s th at follow. Table 11.2 sh ows th e p in s th at you m u st con n ect for a serial cable, u sin g eith er DB-9 (9-p in ) or DB-25 (25-p in ) con n ectors. Table 11.3 sh ows th e con n ection s for a p arallel p ort cable. Th e p arallel cable is sligh tly h ard er to bu ild , bu t is recom m en d ed becau se of its h igh er tran sfer sp eed an d becau se it will n ot in terfere with existin g m od em s an d m ou se d rivers on th e com p u ters. Table 11.2 PC#1

3-W ire Serial Null M odem Cable Pinout s

DB-9

DB-25

DB-25

DB-9

PC#2

TD

3

2 3

2

RD

RD

2

3 2

3

TD

SG

5

7 7

5

SG

Table 11.3 PC #1

11-W ire Parallel Null M odem Cable Pinout s PC #2

2 15 15 2 3 13

Direct Cable Connections

PC #1

PC #2

13 3 4 12 12 4 5 10 10 5 6 11 11 6 25 25

Direct Connect Soft w are After you h ave th e h ard ware in p lace, you n eed th e p rop er software for th e two system s to com m u n icate. At on e tim e, you h ad to p u rch ase a th ird -p arty p rod u ct (su ch as Lap Lin k) to d o th is, bu t th e cap ability is n ow p art of m ost op eratin g system s, in clu d in g DOS 6, W in d ows 9x, an d W in d ows NT. In DOS, th e software con sists of two execu table files, called INTERSVR.EXE an d INTERLNK.EXE. On W in d ows 9x an d W in d ows NT, th e featu re is called Direct Cable Con n ection . Th e software fu n ction s in basically th e sam e way in eith er case. On e com p u ter is d esign ated th e host, an d th e oth er th e guest. Th e software en ables a u ser, workin g at th e gu est m ach in e, to tran sfer files to an d from th e h ost. In th e DOS version , you ru n th e INTERSVR p rogram on th e h ost com p u ter. Th is system can be ru n n in g a d ifferen t version of DOS; you sim p ly h ave to cop y th e INTERSVR.EXE p rogram to it from a DOS 6 m ach in e (u sin g a flop p y d isk). On W in d ows 98, you click th e Start m en u an d th en select Program s, Accessories, Com m u n ication s, Direct Cable Con n ection . Th en ch oose th e Host op tion bu tton (see Figu re 11.3). In both cases, you are p rom p ted to select th e COM or LPT p ort to wh ich you h ave con n ected th e cable.

FIG. 11.3 W in d ows 9x en ables you to access an oth er com p u ter u sin g a serial or p arallel con n ection .

On th e oth er com p u ter, you ru n th e INTERLNK.EXE p rogram in DOS or select th e sam e Direct Cable Con n ection m en u item in W in d ows 9x an d ch oose th e Guest op tion bu tton . Again , you are p rom p ted to ch oose th e correct p ort, after wh ich th e software

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establish es a con n ection between th e two m ach in es. After th is is d on e, th e gu est com p u ter m ou n ts th e d rives from th e h ost in its own file system , assign in g th em th e n ext available d rive letters. At th is p oin t, you can u se th e d rive letters rep resen tin g th e h ost system ju st as th ou gh th ey were local resou rces. You can cop y files back an d forth u sin g an y stan d ard filem an agem en t tool, su ch as th e DOS COPY com m an d or W in d ows Exp lorer. Th e on ly d ifferen ce is th at file tran sfers will, of cou rse, be slower th an local h ard d rive op eration s.

Local Area Net w orks A local area n etwork (LAN) en ables you to sh are files, ap p lication s, p rin ters, d isk sp ace, m od em s, faxes, an d CD-ROM d rives am on g d ifferen t system s; u se clien t/ server software p rod u cts; sen d electron ic m ail; an d oth erwise m ake a collection of com p u ters work as a team . In tod ay’s world , th ere are m an y ways to con stru ct a LAN. As you h ave seen , a LAN can be as sim p le as two com p u ters con n ected via eith er th eir serial or p arallel p orts. Alth ou gh th e term network is n ot often u sed for th is sort of arran gem en t, it d oes satisfy th e d efin ition . Net w orking Basics In m ost cases, h owever, com p u ters are con n ected to a n etwork u sin g a network interface adapter th at eith er takes th e form of an exp an sion card (called a n etwork in terface card , or NIC) or is in tegrated in to th e com p u ter’s m oth erboard . Th e ad ap ter in each com p u ter th en con n ects to a cable in stallation in su ch a way as to p erm it an y com p u ter on th e n etwork to com m u n icate with an y oth er.

Not e Although the vast majority of networked computers are connected by cables, it is also possible to use various wireless technologies such as infrared, lasers, or microwaves as the network medium.

Nearly all LANs are baseband n etworks, m ean in g th at wh en a com p u ter tran sm its its d ata, th e sign al occu p ies th e en tire ban d wid th of th e n etwork m ed iu m . Th is is in con trast to a broadband n etwork, on wh ich m u ltip le sign als can travel as on e. A cable TV n etwork is an exam p le of a broad ban d n etwork, becau se th e sign als carryin g m an y d ifferen t TV ch an n els are all tran sm itted sim u ltan eou sly. Client / Server Versus Peer-t o-Peer. Alth ou gh every com p u ter on a LAN is con n ected to every oth er, th ey d o n ot n ecessarily all com m u n icate with each oth er. Th ere are two basic typ es of LANs, based on th e com m u n ication p attern s between th e m ach in es, called clien t/ server n etworks an d p eer-to-p eer n etworks. On a client/server network, every com p u ter h as a d istin ct role, eith er th at of a clien t or a server. A server is d esign ed to sh are its resou rces am on g th e clien t com p u ters on th e n etwork. Typ ically, servers are located in secu red areas, su ch as locked closets an d d ata cen ters, becau se th ey h old th e organ ization ’s m ost valu able d ata an d d o n ot h ave to be

Local Area Networks

accessed by op erators on a con tin u ou s basis. Th e rest of th e com p u ters on th e n etwork fu n ction as clien ts (see Figu re 11.4). Workstations Administration

Shipping and receiving

Accounting

Accounting

Sales

LAN cable

Shared printers

File server

FIG. 11.4 Th e com p on en ts of a clien t/ server LAN. A d ed icated server com p u ter typ ically h as a faster p rocessor, m ore m em ory, an d m ore storage sp ace th an a clien t, as it m ay h ave to service d ozen s or even h u n d red s of u sers at th e sam e tim e. Th e server ru n s a sp ecial n etwork op eratin g system , su ch as NetW are, th at is d esign ed solely to facilitate th e sh arin g of its resou rces. A clien t com p u ter com m u n icates on ly with servers, n ot with oth er clien ts. A clien t system is a stan d ard PC, ru n n in g an op eratin g system su ch as DOS or W in d ows. Th e on ly d ifferen ce is th e ad d ition of a clien t software p ackage th at en ables th e com p u ter to access th e resou rces sh ared by servers. By con trast, on a p eer-to-p eer n etwork, every com p u ter is eq u al an d can com m u n icate with an y oth er com p u ter on th e n etwork to wh ich it h as been gran ted access righ ts (see Figu re 11.5). Essen tially, every com p u ter on a p eer-to-p eer n etwork fu n ction s as both a server an d a clien t. Th is is wh y you m ay h ear abou t clien t an d server activities, even wh en th e d iscu ssion is abou t a p eer-to-p eer n etwork. Peer-to-p eer n etworks can be as sm all as two com p u ters or as large as h u n d red s of u n its. Peer-to-p eer n etworks are m ore com m on in sm all offices or with in a sin gle d ep artm en t of a larger organ ization . Th e ad van tage of a p eer-to-p eer n etwork is th at you d on ’t h ave to d ed icate a com p u ter to fu n ction as a file server. In stead , every com p u ter can sh are its resou rces with an y oth er. Th e p oten tial d isad van tages to a p eer-to-p eer n etwork are th at th ere is typ ically less secu rity an d less con trol becau se u sers n orm ally ad m in ister th eir own system s, wh ile clien t/ server n etworks h ave th e ad van tage of cen tralized ad m in istration .

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Workstation

Workstation

Workstation

Workstation

Workstation

FIG. 11.5 Th e logical arch itectu re of a typ ical p eer-to-p eer n etwork. W in d ows 9x an d W in d ows NT h ave p eer-to-p eer n etworkin g cap abilities bu ilt in to th em . Becau se of Plu g-an d -Play tech n ology, it is a relatively easy m atter to in stall n etwork in terface card s in a collection of W in d ows 9x system s, con n ect th em with th e righ t kin d of cable, an d bu ild you r own p eer-to-p eer n etwork. You can also n etwork two W in d ows 9x or W in d ows NT PCs u sin g m od em s an d th e op eratin g system ’s Dial-Up Networkin g featu re. Dial-Up Networkin g u ses th e sam e n etwork clien t software as stan d ard W in d ows 9x n etworkin g, bu t su bstitu tes a m od em con n ection for th e n etwork in terface ad ap ter. You can u se th is tech n ology to con n ect to you r office PC from you r h om e com p u ter, an d even access oth er resou rces on you r office n etwork. It is im p ortan t to kn ow th at clien t/ server an d p eer-to-p eer n etworks are n ot m u tu ally exclu sive. You can h ave d ed icated servers on you r n etwork an d still sh are you r local resou rces with oth er u sers, for exam p le. In fact, th is typ e of m ixed n etwork is very p op u lar tod ay, as m an y organ ization s are ru n n in g both NetW are (a clien t/ server op eratin g system ) an d W in d ows NT (a p eer-to-p eer op eratin g system ). Net w ork Client Soft w are. To access n etwork resou rces with a PC, wh eth er it is con n ected to a clien t/ server or a p eer-to-p eer n etwork, you m u st in stall n etwork clien t software on th e com p u ter. Th e n etwork clien t can be p art of th e op eratin g system or a sep arate p rod u ct, bu t it is th is software th at en ables th e system to u se th e n etwork in terface ad ap ter to com m u n icate with oth er m ach in es.

Local Area Networks

On a p rop erly con figu red n etwork workstation , accessin g n etwork resou rces is n o d ifferen t from accessin g local on es (excep t th at th ey m ay be sligh tly slower). You can op en a file on a n etwork d rive ju st as you wou ld op en th e sam e file on you r local h ard d isk. Th is is becau se th e n etwork clien t software is com p letely in tegrated in to every level of th e com p u ter’s op eratin g system . In m ost cases, th e n etwork clien t software is p art of th e op eratin g system . W in d ows 9x, for exam p le, in clu d es all th e software you n eed to p articip ate in a p eer-to-p eer W in d ows n etwork or to con n ect to W in d ows NT an d NetW are servers. To con n ect to a n etwork u sin g DOS or W in d ows 3.1, h owever, you m u st in stall a sep arate clien t software p ackage. Packet Sw it ching Versus Circuit Sw it ching. Th e com p u ters on a LAN m u st sh are th e sam e baseban d m ed iu m , so th eir com m u n ication s h ave to be d esign ed to p rovid e each system with th e op p ortu n ity to tran sm it its d ata. To m ake th is p ossible, com p u ters break d own th e d ata to be tran sm itted in to in d ivid u al u n its called packets. Th e system tran sm its th e p ackets on e at a tim e, an d th ey travel over th e n etwork to th e d estin ation , in term in gled with p ackets gen erated by oth er m ach in es. At th e d estin ation system , th e p ackets are reassem bled in to th eir origin al form . Th is typ e of n etwork is called a packet switching network. By con trast, a circuit switching network establish es a con n ection between th e two com m u n icatin g system s th at fu lly occu p ies a d esign ated ban d wid th all d u rin g th e session . Th e two system s tran sm it th eir sign als over th is con n ection in an u n broken stream , becau se th ey d o n ot h ave to sh are th e m ed iu m with oth er system s. Th e telep h on e system is an exam p le of a circu it switch in g n etwork. The Net w orking St ack. Becau se n etwork clien t software op erates at m an y levels with in each com p u ter, it is often referred to as a stack, th at is, a series of m od u les an d services layered atop on e an oth er. Earlier in th is ch ap ter, you learn ed abou t th e d ifferen t typ es of p rotocols th at m od em s u se to com m u n icate with on e an oth er. Networked com p u ters u se p rotocols, too, an d for th e sam e reason . For two system s to com m u n icate, th ey m u st be sp eakin g th e sam e lan gu age. A LAN con n ection is m ore com p licated th an a m od em con n ection , h owever, an d th ere are m an y m ore p rotocols in volved at every layer of th e n etworkin g stack. For th is reason , th e n etworkin g software is som etim es called th e protocol stack. W h en d esign in g a LAN, th ere are d ifferen t p rotocols available at th e variou s layers of th e stack th at a n etwork ad m in istrator can select to su it a p articu lar en viron m en t. The OSI Reference M odel. On e of th e m ost com m on ly u sed teach in g an d referen ce tools in local area n etworkin g is called th e OSI (Open System s Interconnection) Reference Model. Develop ed by th e In tern ation al Organ ization for Stan d ard ization (abbreviated as th e ISO) in th e 1980s, th e OSI m od el sp lits a com p u ter’s n etworkin g stack in to seven d iscrete layers (see Figu re 11.6). Each layer p rovid es sp ecific services to th e layers above an d below it.

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Application

Presentation

Session

Transport

Network

Logical Link (LLC) Data Link Media Access (MAC)

Physical Layer

FIG. 11.6 Th e OSI referen ce m od el. At th e bottom of th e m od el is th e p h ysical sid e of th e n etwork, in clu d in g cables, NICs, an d oth er h ard ware. At th e top of th e m od el is th e ap p lication in terface th at en ables you to u se you r word p rocessor to op en a file on a n etwork d rive as easily as you can op en on e on you r local d rive. In between are layers d escribin g ad d ition al services, all of wh ich com bin e to m ake n etwork com m u n ication s p ossible. Descrip tion s of th e seven layers follow: ■ Physical. Th is p art of th e OSI m od el sp ecifies th e p h ysical an d electrical ch aracteristics of th e con n ection s th at m ake u p th e n etwork (twisted -p air cables, fiber-op tic cables, coaxial cables, con n ectors, rep eaters, an d oth er h ard ware). You can th in k of th is layer as th e h ard ware layer. Alth ou gh th e rest of th e layers m ay be im p lem en ted as firm ware (th at is, ch ip -level fu n ction s on th e n etwork ad ap ter) rath er th an actu al software, th e oth er layers are software in relation to th is first layer.

Local Area Networks

■ Data Link. Th is layer con trols h ow th e electrical im p u lses en ter or leave th e n etwork cable. Th e n etwork’s electrical rep resen tation of you r d ata (bit p attern s, en cod in g m eth od s, an d token s) is kn own to th is layer an d on ly to th is layer. It is h ere th at m ost errors are d etected an d corrected (by req u estin g retran sm ission s of corru p ted p ackets). In som e n etworkin g system s, th e d ata lin k layer is su bd ivid ed in to a Med ia Access Con trol (MAC) layer an d a Logical Lin k Con trol (LLC) layer. Th e MAC layer d eals with n etwork access (token -p assin g or collision -sen sin g) an d n etwork con trol. Th e LLC layer, op eratin g ju st above th e MAC layer, is con cern ed with sen d in g an d receivin g th e u ser d ata m essages. Eth ern et an d Token Rin g are d ata lin k-layer p rotocols. ■ Network. Th is layer switch es an d rou tes th e p ackets as n ecessary to get th em to th eir d estin ation s an d is resp on sible for ad d ressin g an d d eliverin g m essage p ackets. W h ile th e d ata lin k layer is con sciou s on ly of th e im m ed iately ad jacen t com p u ters on th e n etwork, th e n etwork layer is resp on sible for th e en tire rou te of a p acket, from sou rce to d estin ation . IP an d IPX are exam p les of n etwork-layer p rotocols. ■ Transport. W h en m ore th an on e p acket is in p rocess at an y tim e, su ch as wh en a large file m u st be sp lit in to m u ltip le p ackets for tran sm ission , th e tran sp ort layer con trols th e seq u en cin g of th e m essage com p on en ts an d regu lates in bou n d traffic flow. If a d u p licate p acket arrives, th is layer recogn izes it as a d u p licate an d d iscard s it. TCP an d SPX are tran sp ort-layer p rotocols. ■ Session. Th e fu n ction s in th is layer en able ap p lication s ru n n in g at two workstation s to coord in ate th eir com m u n ication s in to a sin gle session (wh ich you can th in k of in term s of a h igh ly stru ctu red d ialogu e). Th e session layer su p p orts th e creation of th e session , th e m an agem en t of th e p ackets sen t back an d forth d u rin g th e session , an d th e term in ation of th e session . ■ Presentation. W h en IBM, Ap p le, DEC, NeXT, an d Bu rrou gh s com p u ters wan t to talk to on e an oth er, obviou sly a certain am ou n t of tran slation an d byte reord erin g n eed s to be d on e. Th e p resen tation layer con verts d ata in to an in terim form at for tran sm ission over th e n etwork, an d back in to th e m ach in e’s n ative form at afterward . ■ Application. Th is layer d efin es th e in terface to th e ap p lication s ru n n in g on a n etworked com p u ter. Ap p lication -layer p rotocols can be p rogram s in th em selves (su ch as FTP), or th ey can be u sed by oth er p rogram s (as SMTP, th e Sim p le Mail Tran sfer Protocol, is u sed by m ost e-m ail ap p lication s) to red irect d ata to th e n etwork. It is im p ortan t to u n d erstan d th at wh ile th e OSI m od el was d esign ed to be a m od el for th e d evelop m en t of actu al n etworkin g software, th e p rod u cts u sed on tod ay’s LANs d o n ot exactly corresp on d to th ese layers. W h ile you m ay fin d th at certain p rotocols fall n eatly with in th e bou n d aries between th e layers, oth ers m ay overlap or p rovid e services th at sp an several layers. As m en tion ed earlier, th e m od el is p rim arily u sed as a tool for teach in g n etworkin g an d as a referen ce tool for n etworkin g p rofession als.

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Dat a Encapsulat ion. Th e d ata p ackets tran sm itted over a LAN origin ate at th e top of a com p u ter’s p rotocol stack, at th e ap p lication layer of th e OSI m od el. Th is is th e ap p lication d ata in its sim p lest form , su ch as a req u est for a file stored on an oth er m ach in e or a p rin t job d estin ed for a n etwork p rin ter. As th e d ata travels d own th rou gh th e layers of th e p rotocol stack, it is p ackaged for its trip across th e n etwork. Th is p ackagin g con sists of in form ation p rovid ed by each p rotocol in th e stack, an d in ten d ed for th e eq u ivalen t p rotocol in th e d estin ation com p u ter. Each p rotocol ad d s its own in form ation to th e d ata it receives from th e layer above in th e form of a fram e. A fram e con sists of a h ead er an d som etim es a footer ad d ed to th e begin n in g (an d p ossibly th e en d ) of a p acket. Th e h ead er an d footer are sim p ly ad d ition al bytes of d ata con tain in g sp ecialized con trol in form ation u sed to get th e p acket to its d estin ation . Th u s, wh en a file req u est is p assed d own from th e ap p lication layer, th e n ext p rotocol it en cou n ters is u su ally at th e tran sp ort layer (becau se th ere are n o sp ecific p resen tation layer an d session -layer p rotocols). Th e tran sp ort layer takes th e d ata from th e ap p lication layer, ad d s its own h ead er, an d p asses it d own to th e n etwork layer. Th e n etwork takes th e tran sp ort-layer d ata (in clu d in g th e tran sp ort h ead er) an d ad d s its own h ead er before p assin g it d own to th e d ata lin k layer. Th e d ata lin k-layer p rotocol is u n iq u e in th at it ad d s a footer in ad d ition to a h ead er. Th is p rocess is called data encapsulation. By th e tim e th e p acket is in trod u ced to th e n etwork cable, it h as been en cap su lated th ree tim es or m ore, an d con sists of a fram e with in a fram e with in a fram e (see Figu re 11.7).

Header

Data

Application Layer

Header

Data

Transport Layer

Header

Header

Data

Network Layer

Header

Header

Data

Footer

Data Link Layer

FIG. 11.7 Each p rotocol in a com p u ter’s n etworkin g stack en cap su lates th e d ata it receives from th e layer above by ad d in g its own h ead er.

W h en th e p acket arrives at its d estin ation , it travels u p th rou gh th e p rotocol stack an d each fram e is rem oved in th e reverse ord er from wh ich it was ap p lied . In th is way, th e p rotocols at each layer in th e stack com m u n icate in d irectly with th eir eq u ivalen t p rotocols in th e oth er com p u ter (see Figu re 11.8). LAN Hardw are Com ponent s Alth ou gh you can con n ect virtu ally an y PC to a n etwork, you sh ou ld u se a d ifferen t set of h ard ware evalu ation criteria wh en bu ild in g or p u rch asin g a com p u ter sp ecifically for n etwork u se. Th e followin g section s exam in e th e typ es of com p u ters typ ically fou n d on n etworks, an d th e oth er h ard ware in volved , su ch as n etwork in terface ad ap ters an d cable typ es.

Local Area Networks

Computer A

Computer B

Protocols

FIG. 11.8 Protocols in th e n etworkin g stack com m u n icate in d irectly with th eir eq u ivalen t p rotocols in oth er com p u ters.

Alth ou gh all th e PCs on a n etwork u se th e sam e basic com p on en ts as a stan d alon e system , trad ition an d exp erien ce h ave resu lted in two m ajor h ard ware p rofiles: workstation s an d servers. W orkstation s are u su ally op erated by u sers on th eir in d ivid u al d esktop s, wh ile servers are u su ally located in a secu red area. On a clien t/ server n etwork, th e workstation is u sed on ly by th e p erson sittin g in fron t of it, wh ile a server allows m an y p eop le to sh are its resou rces. As a gen eral ru le, servers are m ore p owerfu l m ach in es th an workstation s, becau se th ey m u st service m an y d ifferen t u sers at on ce. On a p eer-to-p eer n etwork, h owever, th e d istin ction begin s to blu r. Sin ce workstation s m ay also fu n ction as servers, it can be n ecessary to eq u ip th em with m ore p owerfu l com p on en ts. Tech n ically, th ere is n o reason wh y you can n ot bu y a PC m arketed as a workstation or a stan d alon e system an d u se it as a server, as lon g as it h as su fficien t resou rces to ru n th e server software. However, m ost PC m an u factu rers sell com p u ters th at are sp ecifically d esign ed to fu n ction as servers. Th ese m ach in es m ay h ave sp ecialized com p on en ts d esign ed for h eavy u se an d fau lt toleran ce, an d you p ay m ore as a resu lt.

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W orkst at ions. Th e con figu ration of a workstation PC is largely d ep en d en t on th e op eratin g system th at you in ten d to u se. DOS an d W in d ows 3.1, for exam p le, can get by on 8M of RAM, wh ile W in d ows 9x n eed s at least 16–32M, an d W in d ows NT sh ou ld h ave a m in im u m of 32M. In th e sam e way, a W in d ows NT m ach in e sh ou ld h ave a faster p rocessor an d m ore h ard d rive sp ace. Tod ay, it is d ifficu lt to bu y a n ew system th at h as an yth in g less th an a Pen tiu m p rocessor, bu t workstation s ten d to u se th e lower-sp eed version s th at h ave been on th e m arket for a wh ile an d are th erefore lower in p rice. Th e big d ifferen ce between a workstation an d a stan d alon e system , h owever, is th at you sh ou ld con sid er wh at resou rces will be available on th e n etwork. If you p lan to h ave u sers storin g th eir d ata on n etwork d rives, for exam p le, you can eq u ip workstation s with sm aller h ard d rives. In th e sam e way, you m igh t wan t to q u estion wh eth er you r workstation s n eed CD-ROMs if you can p rovid e access to n etworked u n its. You also sh ou ld con sid er th e en viron m en t in wh ich th e workstation s will be u sed . It m ay n ot be a good id ea to eq u ip PCs with au d io ad ap ters an d sp eakers if you are goin g to h ave a lot of com p u ters in a sin gle room . Also, com p u ters th at u se a slim lin e case m igh t be ap p reciated by u sers with lim ited worksp ace. Servers. A n etwork server is far m ore likely to be a top -of-th e-lin e PC, with th e fastest p rocessor available, a lot of RAM, an d a large am ou n t of h ard d isk sp ace. Servers m u st be h igh -q u ality, h eavy-d u ty m ach in es becau se, in servin g th e wh ole n etwork, th ey d o m an y tim es th e work of an ord in ary workstation com p u ter. You m ay typ e on th e server’s keyboard on ly a cou p le of tim es a d ay, an d you m ay glan ce at its m on itor on ly in freq u en tly. Th e server’s CPU an d h ard d isk d rives, h owever, take th e bru n t of resp on d in g to th e fileservice req u ests of all th e workstation s on th e LAN. Se rv e r P ro c e sso rs. Th e p rocessor in a server sh ou ld be th e m ost ad van ced an d th e fastest th at you can afford . Righ t n ow, a Pen tiu m II is p referable, bu t n ew m od els are bein g released at sh orter an d sh orter in tervals. Servers d o m ore m u ltitaskin g th an an y workstation , an d th e faster th e p rocessor, th e m ore efficien t th e server will be. However, reliability sh ou ld also be a m ajor con cern . A server is n ot th e p lace to test ou t n ew tech n ology. √√ See “ P6 (686) Sixth-Generation Processors,” p. 127

Se rv e r Me m o ry . Servers often req u ire large am ou n ts of m em ory, m u ch m ore th an workstation s. Th e m in im u m is u su ally 64M th ese d ays, bu t you m ay n eed m ore, d ep en d in g on th e software you in ten d to ru n an d h ow m u ch d isk sp ace you h ave in stalled in th e server. Both W in d ows NT an d NetW are ru n better wh en th ey h ave m ore th an th e recom m en d ed am ou n t of m em ory. It’s also a good id ea, wh en sh op p in g for a server, to be aware of th e n u m ber of m em ory slots on th e m oth erboard an d th e m axim u m am ou n t of RAM th at it su p p orts. Ch eck also h ow th e m em ory th at com es with th e com p u ter is con figu red . A m ach in e with a sin gle 64M DIMM is easier to u p grad e th an on e with 16M m od u les fillin g all fou r slots.

Local Area Networks

√√ See “ Physical M emory,“ p. 323

Se rv e r St o ra g e . Hard d isk d rives are often th e m ost im p ortan t com p on en ts in a server. File sh arin g is on e of th e p rim ary reason s for n etworkin g com p u ters, an d th e server’s h ard d rives n eed to be d u rable an d reliable, an d geared to th e task of servin g m u ltip le u sers sim u ltan eou sly. For th is reason , SCSI h ard d rives are p referred over IDE d rives in tod ay’s servers. √√ See “ Small Computer System Interface (SCSI),” p. 626

Th e h ard d isk d rives sh ou ld be large an d fast, alth ou gh in som e cases th e h igh est cap acity d rive available is n ot n ecessarily th e best ch oice. W h en you con sid er th at th e server will be p rocessin g th e file req u ests of m an y u sers sim u ltan eou sly, it can be m ore efficien t to h ave, for exam p le, n in e 1G SCSI h ard d rives rath er th an on e 9G d rive. Th at way, th e req u ests can be sp read across several d ifferen t u n its, rath er th an q u eu ed u p waitin g for on e d evice. Asid e from stan d ard h ard d isk d rives, th ere are also m ore elaborate m ass storage p rod u cts on th e m arket th at are sp ecifically d esign ed for u se with servers. Hard d rive arrays can h ou se large n u m bers of d rives an d u se d isk m irrorin g or RAID (Red u n d an t Array of In exp en sive Disks) to p rovid e fau lt toleran ce. Th ese are tech n ologies th at au tom atically store m u ltip le cop ies of th e server d ata on variou s h ard d rives, so in th e even t of a d rive failu re, all th e d ata rem ain s available to u sers. On som e of th ese arrays, th e d rives m ay even be hot-swappable, m ean in g th at you can rep lace a m alfu n ction in g d rive wh ile th e m ach in e is still ru n n in g. W h ile a server will u su ally h ave a CD-ROM d rive in it to in stall software, if n oth in g else, you m ay wan t to h ave ad d ition al CD-ROM d rives to sh are with n etwork u sers. Th ere are m an y CD-ROM ch an ger an d d rive array p rod u cts on th e m arket th at en able you to p rovid e u sers with con tin u ou s access to large am ou n ts of CD-ROM-based in form ation . A CD-ROM ch an ger is a d evice th at h old s m u ltip le d isks an d swap s th em in an d ou t of on e or m ore d rives. A CD-ROM d rive array is a collection of d rives in a sin gle h ou sin g th at sh are on e p ower su p p ly. A d rive array is m ore exp en sive th an a ch an ger, bu t all th e d isks are im m ed iately available. Se rv e r Ba c k u p s. If you valu e th e d ata stored on you r server at all, th en m akin g regu lar backu p s of you r server d rives is a n ecessity. For th is p u rp ose, you will p robably wan t to in stall a SCSI tap e d rive on you r server. Not every server n eed s its own tap e d rive, h owever, becau se n etwork backu p software p rod u cts can u se a sin gle d rive to p rotect d ata from m u ltip le servers an d workstation s. Se rv e r P o w e r Su p p l i e s. In a server, th e p ower su p p ly is an im p ortan t bu t often overlooked item . As with an y PC, be su re th at th e p ower su p p ly d elivers en ou gh cu rren t to

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ru n all th e d evices in th e com p u ter. On a server, th is m ay req u ire a 400-watt su p p ly or m ore, as servers typ ically con tain m ore d rives th an workstation PCs d o. Power su p p ly failu res an d m alfu n ction s can also cau se p roblem s elsewh ere in th e com p u ter th at are d ifficu lt to d iagn ose. You r file server m ay d isp lay a m essage in d icatin g th at a RAM ch ip h as failed , an d th en stop ; th e cau se of th e p roblem m ay in d eed be a failed RAM ch ip , or th e p roblem m ay be in th e p ower su p p ly. √√ See “ Power Supply Troubleshooting,“ p. 426

Power su p p ly fan s som etim es stop workin g or becom e obstru cted with d u st an d d irt. As a resu lt, th e com p u ter overh eats an d fails com p letely or acts stran gely. Clean in g th e fan (s)—after u n p lu ggin g th e com p u ter from th e wall ou tlet, of cou rse—sh ou ld be a p art of th e regu lar m ain ten an ce of you r file server. Som e servers in clu d e red u n d an t fan s an d p ower su p p lies th at en able th e com p u ter to keep ru n n in g even wh en a p ower su p p ly fails. In oth er m od els, th e red u n d an t p ower su p p lies are h ot-swap p able, p rovid in g even m ore fau lt toleran ce. You sh ou ld also take step s to p rotect you r server from varian ces in th e voltage of its AC p ower su p p ly (sags an d sp ikes). To m ake you r server as reliable as p ossible, you sh ou ld in stall an u n in terru p tible p ower su p p ly (UPS) between th e electric p ower sou rce an d th e server. Th e UPS n ot on ly p rovid es electricity in case of a p ower failu re, bu t also con d ition s th e lin e to p rotect th e server from voltage flu ctu ation s. Man y UPSs also in clu d e a cable th at con n ects to th e server’s serial p ort an d software th at au tom atically sh u ts d own th e op eratin g system wh en th e AC p ower fails for a given p eriod of tim e. Th is en su res th at server d ata is n ot corru p ted by an im p rop er system sh u td own . Se rv e r Ke y b o a rd s, Mo n i t o rs, a n d Mi c e . On e area wh ere you can safely skim p wh en p u rch asin g a server is th e u ser in terface com p on en ts, su ch as th e keyboard , m on itor, an d m ou se (if an y). Becau se th ese item s receive far less u se th an th eir workstation cou n terp arts, you can u se lower q u ality, less-exp en sive com p on en ts h ere. A typ ical file server ru n s u n atten d ed an d m ay go for h ou rs or d ays with ou t in teraction from you . You can tu rn off th e m on itor for th ese lon g p eriod s. Net w ork Int erface Adapt ers. Th e n etwork in terface ad ap ter is th e PC’s lin k to all th e oth er com p u ters on th e n etwork. All file req u ests an d oth er n etwork com m u n ication s en ter an d leave th e com p u ter th rou gh th e n etwork ad ap ter. Figu re 11.9 sh ows a typ ical n etwork in terface ad ap ter card th at you m igh t in stall in a server or workstation . Un like m an y oth er com p on en ts, th e ad ap ters in servers an d workstation s are u su ally th e sam e. It serves n o p u rp ose to in stall a h igh -sp eed ad ap ter in a server if th e n etwork workstation s d o n ot also su p p ort th at sam e sp eed . Th e on ly d ifferen ce th at you m ay fin d is th at a server m igh t h ave m ore th an on e ad ap ter, to con n ect to m u ltip le n etworks.

Local Area Networks

FIG. 11.9 Th e n etwork in terface ad ap ter sen d s an d receives m essages to an d from all th e com p u ters on th e LAN.

All th e n etwork in terface ad ap ters on a LAN are d esign ed to u se Eth ern et, Token Rin g, or som e oth er d ata lin k-layer p rotocol. Before you p u rch ase ad ap ter card s (or n etwork cables, for th at m atter), you m u st d ecid e wh ich d ata lin k p rotocol you wan t to u se. You can fin d n etwork in terface ad ap ters for each of th ese p rotocols, h owever, th at p erform better th an oth ers. A p articu lar n etwork ad ap ter m ay be faster at p rocessin g m essages becau se it h as a large am ou n t of on board m em ory (RAM); becau se it con tain s its own m icrop rocessor; or p erh ap s becau se th e ad ap ter u ses a PCI bu s rath er th an ISA, an d th u s can tran sfer m ore d ata to an d from th e CPU at on e tim e. On m ost com p u ters, th e n etwork in terface ad ap ter takes th e form of a network interface card, or NIC, th at fits in to a slot in each com p u ter. Som e system s in corp orate th e n etwork in terface ad ap ter on to th e m oth erboard , bu t th is p ractice is m ore com m on ly fou n d in workstation s an d rarely in servers, becau se m ost n etwork ad m in istrators p refer to select th eir own . Eth ern et an d Token Rin g ad ap ters h ave u n iq u e h ard ware ad d resses cod ed in to th eir firm ware. Th e d ata lin k-layer p rotocol u ses th ese ad d resses to id en tify th e oth er system s on th e n etwork. A p acket gets to th e righ t d estin ation becau se its d ata lin k-layer p rotocol h ead er con tain s th e h ard ware ad d resses of both th e sen d in g an d receivin g system s. Network ad ap ters ran ge in p rice from well u n d er $100 to as m u ch as $1,000. W h at d o you get for you r m on ey? Prim arily sp eed . Th e faster ad ap ters can p u sh d ata faster on to th e cable, wh ich m ean s th at a server can receive a req u est m ore q u ickly an d sen d back a resp on se m ore q u ickly.

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Dat a-Transfer Speeds on a LAN Electrical engineers and networking professionals measure the speed of a network in megabits per second (M bps). Because a byte of information consists of 8 bits, you can divide the megabits per second rating by 8 to find out how many millions of characters (bytes) per second the network can theoretically handle. In practice, however, a LAN is slower than its rated speed. In fact, a LAN is no faster than its slowest component. A slow hard disk drive can make it seem as though the LAN is performing poorly, when the problem is actually inside one of the computers. This multitude of possible causes can make diagnosing networking problems difficult.

Ne t w o rk Ad a p t e r Co n n e c t o rs. Eth ern et ad ap ters typ ically h ave a con n ector th at looks like a large telep h on e jack called an RJ45 (for 10BaseT cables), a sin gle BNC con n ector (for Th in n et), or a D-sh ap ed 15-p in con n ector called a DB15 (for Th ickn et). Som e ad ap ters h ave a com bin ation of two or all th ree of th ese con n ector typ es. Token Rin g ad ap ters can h ave a 9-p in con n ector called a DB9, or som etim es an RJ45 jack. Figu re 11.10 sh ows a h igh -p erform an ce Token Rin g ad ap ter with both kin d s of con n ectors.

Onboard RAM sockets Node ID ROM Onboard RAM size selection jumper (JP1)

Socket for Boot ROM (optional)

Type 3 (RJ - type) cable connector Type 1 (DB9) cable connector

Cable connector selection jumper (JB1)

Status LEDs

FIG. 11.10 Th e Th om as-Con rad 16/ 4 Token Rin g ad ap ter (with DB9 an d RJ45 con n ectors). Card s with two or m ore con n ectors en able you to ch oose from a wid er variety of LAN cables. An Eth ern et card with two con n ectors, for exam p le, m ay en able you to u se eith er u n sh ield ed twisted -p air (UTP) or th in Eth ern et (Th in n et) cable. You can n ot u se both

Local Area Networks

con n ectors at th e sam e tim e, h owever, excep t on sp ecial ad ap ters d esign ed sp ecifically for th is p u rp ose. Ne t w o rk Ad a p t e r Fu n c t i o n s. Th e LAN ad ap ter card in you r PC receives all th e traffic goin g by on th e n etwork cable, accep ts on ly th e p ackets d estin ed for you r com p u ter, an d d iscard s th e rest. Th e ad ap ter th en h an d s th ese p ackets over to th e system CPU for fu rth er p rocessin g. Th e p ackets th en begin th eir jou rn ey u p th e rest of th e n etworkin g stack to th e ap p lication th at is th eir fin al d estin ation . W h en you r com p u ter wan ts to tran sm it d ata, th e n etwork ad ap ter waits for th e ap p rop riate tim e (d eterm in ed by wh ich d ata lin k-layer p rotocol it u ses), an d in serts th e p ackets in to th e d ata stream . Th e receivin g system n otifies you r com p u ter as to wh eth er th e m essage arrived in tact; if it was garbled , you r m ach in e resen d s. Th e n etwork ad ap ter, alon g with th e ad ap ter d river in stalled on th e com p u ter, also p articip ates in th e p rep aration of th e d ata for tran sm ission . A n etwork ad ap ter p erform s seven m ajor fu n ction s d u rin g th e p rocess of sen d in g or receivin g every p acket. W h en sen d in g d ata ou t to th e n etwork, th e ad ap ter p erform s th e step s in th e ord er p resen ted in th e followin g list. W h en it receives d ata, th e step s are reversed . Th e seven step s are as follows: 1. Data transfer. Data is tran sferred from PC m em ory (RAM) to th e n etwork in terface ad ap ter or from th e ad ap ter to PC m em ory via DMA, sh ared m em ory, or p rogram m ed I/ O. 2. Buffering. W h ile bein g p rocessed by th e n etwork ad ap ter, d ata is stored in a bu ffer. Th e bu ffer en ables th e ad ap ter to access an en tire fram e at on ce so th at it can m an age th e d ifferen ce between th e d ata rate of th e n etwork an d th e rate at wh ich th e PC can p rocess d ata. 3. Fram e form ation. Th e n etwork ad ap ter breaks u p th e d ata in to m an ageable ch u n ks (or, on recep tion , reassem bles it). On an Eth ern et n etwork, th ese ch u n ks are abou t 1,500 bytes. Token Rin g n etworks gen erally u se a fram e size of abou t 4K. Th e ad ap ter en cap su lates th e d ata p acket with a h ead er an d footer, form in g th e d ata lin k-layer fram e. At th is p oin t, th e p acket is com p lete an d read y for tran sm ission . (For in bou n d p ackets, th e ad ap ter read s an d rem oves th e h ead er an d footer at th is stage.) 4. Media access. Th e n etwork ad ap ter u ses th e ap p rop riate m ed ia access con trol m ech an ism for th e d ata lin k-layer p rotocol to regu late its tran sm ission s. On an Eth ern et n etwork, th e n etwork ad ap ter en su res th at th e lin e is q u iet before sen d in g its d ata (or retran sm its its d ata if a collision occu rs). On a Token Rin g n etwork, th e ad ap ter waits u n til it receives a token th at it can claim . On ce it h as a token , th e ad ap ter can tran sm it its d ata. (Th ese step s are n ot ap p licable to in com in g traffic, of cou rse.)

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5. Parallel/serial conversion. Th e n etwork ad ap ter receives (or sen d s) d ata over th e system bu s in p arallel fash ion , eith er 16 or 32 bits at a tim e, an d stores it in th e bu ffer. Th e d ata in th e bu ffer m u st be sen t or received th rou gh th e n etwork cables in serial fash ion , with on e bit followin g th e n ext. Th e ad ap ter card con verts between th ese two form ats in th e sp lit secon d before tran sm ission (or after recep tion ). 6. Encoding/decoding. Th e n etwork ad ap ter en cod es th e d ata it receives over th e system bu s in to th e electrical sign als th at are carried by th e n etwork cable, an d d ecod es th e sign als arrivin g from th e n etwork. Eth ern et ad ap ters u se a tech n iq u e called Manchester encoding, wh ile Token Rin g ad ap ters u se a sligh tly d ifferen t sch em e called Differential Manchester. Th ese tech n iq u es h ave th e ad van tage of in corp oratin g tim in g in form ation in to th e d ata th rou gh th e u se of bit p eriod s. In stead of rep resen tin g a 0 as th e absen ce of electricity an d a 1 as its p resen ce, th e 0s an d 1s are rep resen ted by ch an ges in p olarity as th ey occu r in relation to very sm all tim e p eriod s. 7. Sending/receiving im pulses. Th e ad ap ter takes th e electrically en cod ed im p u lses th at com p rise th e d ata (fram e), am p lifies th em , an d sen d s th em th rou gh th e wire. (On recep tion , th e ad ap ter p asses th e in com in g im p u lses to th e d ecod in g step .) Of cou rse, th e execu tion of all of th ese step s takes on ly a fraction of a secon d . W h ile you were read in g abou t th ese step s, th ou san d s of fram es cou ld h ave been sen t across th e LAN. Network ad ap ter card s an d th e su p p ort software recogn ize an d h an d le errors th at occu r wh en electrical in terferen ce, p acket collision s (in Eth ern et n etworks), or m alfu n ction in g eq u ip m en t cau se som e p ortion of a fram e to be corru p ted . Ad ap ters gen erally d etect errors th rou gh th e u se of a cyclic redundancy check (CRC) valu e com p u ted by th e sen d in g system an d in clu d ed in th e ou tgoin g fram e’s footer. Th e sam e CRC calcu lation is p erform ed by th e receivin g system . If its own calcu lated CRC d oesn ’t m atch th e valu e of th e CRC in th e fram e, th e receiver tells th e sen d er abou t th e error an d req u ests retran sm ission of th e bad fram e. Cables and Connect ors. Gen erally sp eakin g, th e cablin g system s d escribed in th e n ext few section s u se on e of th ree d istin ct cable typ es. Th ese are twisted -p air (in sh ield ed an d u n sh ield ed varieties kn own as STP an d UTP, 10BaseT, or 100BaseT), coaxial in th in an d th ick varieties (kn own as 10Base2 an d 10Base5, resp ectively), an d fiber-op tic. Th e kin d of cable you u se d ep en d s m ostly on th e d ata lin k-layer p rotocol th at you elect to u se, th e con d ition s at th e n etwork site, an d , of cou rse, you r bu d get. All th e m ajor d ata lin k-layer p rotocols u sed on LANs (su ch as Eth ern et an d Token Rin g) in clu d e h igh ly sp ecific gu id elin es for th e in stallation of th e n etwork cable as p art of th eir sp ecification s. Tech n ically, th ese gu id elin es are p art of th e p h ysical layer, bu t th is is on e exam p le of h ow p rotocols in th e real world d o n ot con form exactly to th e OSI m od el. Tw i st e d -P a i r Ca b l e . Twisted-pair cable is ju st wh at its n am e im p lies: in su lated wires with in a p rotective casin g, with a sp ecified n u m ber of twists p er foot. Twistin g th e wires red u ces th e effect of electrom agn etic in terferen ce (th at can be gen erated by n earby cables, electric m otors, an d flu orescen t ligh tin g) on th e sign als bein g tran sm itted .

Local Area Networks

Shielded twisted pair (STP) refers to th e am ou n t of in su lation arou n d th e clu ster of wires an d th erefore its im m u n ity to n oise. You are p robably fam iliar with unshielded twistedpair (UTP) cable; it is often u sed for telep h on e wirin g. Figu re 11.11 sh ows u n sh ield ed twisted -p air cable; Figu re 11.12 illu strates sh ield ed twisted -p air cable.

FIG. 11.11 An u n sh ield ed twisted -p air cable.

FIG. 11.12 A sh ield ed twisted -p air cable.

Shielded Versus Unshielded Tw ist ed Pair When cabling was being developed for use with computers, it was first thought that shielding the cable from external interference was the best way to reduce interference and allow for greater transmission speeds. However, it was discovered that twisting the pairs of wires is a more effective way to prevent interference from disrupting transmissions. As a result, earlier cabling scenarios relied on shielded cables rather than the unshielded cables more commonly in use today. Shielded cables also have some special grounding concerns because one—and only one—end of a shielded cable should be connected to an earth ground; issues arose where people inadvertently caused grounding loops to occur by connecting both ends, or caused the shield to act as an antenna because it wasn’t grounded. Grounding loops are situations where two different grounds are tied together. This is a bad situation

because each ground can have a slightly different potential, resulting in a circuit that has very low voltage but infinite amperage. This causes undue stress on electrical components and can be a fire hazard.

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Co a x i a l Ca b l e . Coaxial cable is fairly p revalen t in you r everyd ay life, as it is th e stan d ard m ed iu m u sed by cable TV n etworks an d for an ten n a con n ection s. Th in an d th ick, of cou rse, refer to th e d iam eter of th e coaxial cable itself. Stan d ard Eth ern et cable (Th ick Eth ern et), rarely u sed for n etworkin g tod ay, is as th ick as you r th u m b. Th in Eth ern et cable (som etim es called Th in n et or Ch eap erNet) is sligh tly n arrower th an you r little fin ger. Th e th ick cable h as a greater d egree of n oise im m u n ity, is m ore d ifficu lt to d am age, an d req u ires a vam pire tap (a con n ector with teeth th at p ierce th e tou gh ou ter in su lation ) an d a d rop cable to con n ect to a workstation . Alth ou gh th in coaxial cable carries th e sign al over sh orter d istan ces th an th e th ick cable, it is lower in cost (h en ce th e n am e Ch eap erNet) an d u ses a sim p le, bayon et-lockin g con n ector called a BNC (Bayon et-NeillCon celm an ) con n ector to attach to workstation s. Th in Eth ern et was at on e tim e th e stan d ard for Eth ern et n etworkin g, bu t it h as sin ce been rep laced by 10BaseT (u n sh ield ed twisted p air). Th in n et is wired d irectly to th e back of each com p u ter on th e n etwork an d gen erally in stalls m u ch m ore easily th an Th ickn et, bu t it is m ore p ron e to sign al in terferen ce an d p h ysical con n ection p roblem s. Figu re 11.13 sh ows an Eth ern et BNC coaxial T-con n ector, an d Figu re 11.14 illu strates th e d esign of coaxial cable.

FIG. 11.13 An Eth ern et coaxial cable T-con n ector.

Outer insulation

Inner insulation

Copper wire

FIG. 11.14 Coaxial cable.

Local Area Networks

Fi b e r-Op t i c Ca b l e . Fiber-op tic cable u ses p u lses of ligh t rath er th an electrical sign als to carry in form ation . It is th erefore com p letely resistan t to th e electrom agn etic in terferen ce th at lim its th e len gth of cop p er cables. Attenuation (th e weaken in g of a sign al as it traverses th e cable) is also less of a p roblem , en ablin g fiber to sen d d ata over h u ge d istan ces at h igh sp eed s. It is, h owever, very exp en sive an d d ifficu lt to in stall an d m ain tain . Sp licin g th e cable, in stallin g con n ectors, an d u sin g th e few available d iagn ostic tools for fin d in g cable fau lts are skills th at very few p eop le h ave.

Tip Fiber-optic cable is often used to connect buildings together in a campus network environment for two very important reasons. One is that fiber can travel approximately 2.2 km, while copper-based technologies are significantly more restricted. The other reason is that, because fiber does not use electrical signals, it eliminates the problems with differing ground sources.

Fiber-op tic cable is sim p ly d esign ed , bu t u n forgivin g of bad con n ection s. It u su ally con sists of a core of glass th read with a d iam eter m easu red in m icron s (m illion th s of a m eter), su rrou n d ed by a solid glass clad d in g. Th is, in tu rn , is covered by a p rotective sh eath . Th e first fiber-op tic cables were m ad e of glass, bu t p lastic fibers also h ave been d evelop ed . Th e ligh t sou rce for fiber-op tic cable is a ligh t-em ittin g d iod e (LED); in form ation u su ally is en cod ed by varyin g th e in ten sity of th e ligh t. A d etector at th e oth er en d of th e cable con verts th e in com in g sign al back in to electrical im p u lses. Two typ es of fiber-op tic cable exist: sin gle m od e an d m u ltim od e. Single m ode h as a sm aller d iam eter, is m ore exp en sive, an d can carry sign als over a greater d istan ce. Figu re 11.15 illu strates fiber-op tic cables an d th eir con n ectors. Mu ltim od e h as a d iam eter five to ten tim es greater th an sin gle m od e, m akin g it easier to con n ect. Th is ease of u se m akes it th e m ost com m on ly u sed fiber. However, m u ltim od e su ffers from h igh er d istortion an d lower ban d wid th .

FIG. 11.15 Fiber-op tic cables u se ligh t to carry LAN m essages. Th e ST con n ector is com m on ly u sed with fiber-op tic cables. Ne t w o rk To p o l o g i e s. Each com p u ter on th e n etwork is con n ected to th e oth er com p u ters with cable (or som e oth er m ed iu m ). Som etim es a sin gle p iece of cable win d s from station to station , visitin g all of th e n etwork’s com p u ters alon g th e way. Th is cablin g

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arran gem en t is called a bus topology, as sh own in Figu re 11.16. (A topology is sim p ly a d escrip tion of th e way th e workstation s an d servers are p h ysically con n ected .) Th e p oten tial d isad van tage to th is typ e of wirin g is th at if on e com p u ter or cable con n ection m alfu n ction s, it can cau se all th e station s beyon d it on th e bu s to lose th eir n etwork con n ection s. Th in an d th ick Eth ern et coaxial cables are typ ically in stalled u sin g a bu s top ology.

FIG. 11.16 Th e lin ear bu s top ology, attach in g all n etwork d evices to a com m on cable. An oth er typ e of top ology u ses sep arate cables to con n ect each com p u ter to a cen tral wirin g n exu s, often called a hub or a concentrator. Figu re 11.17 sh ows th is arran gem en t, wh ich is called a star topology. Becau se each com p u ter u ses a sep arate cable, th e failu re of a n etwork con n ection affects on ly th e sin gle m ach in e in volved . Th e oth er com p u ters can con tin u e to fu n ction n orm ally. Bu s cablin g sch em es u se less cable th an th e star, bu t are h ard er to d iagn ose or byp ass wh en p roblem s occu r. At th is tim e, Eth ern et u sin g 10BaseT cable in a star top ology is th e m ost com m on ly im p lem en ted typ e of LAN.

Hub

FIG. 11.17 Th e star top ology, lin kin g th e LAN’s com p u ters an d d evices to on e or m ore cen tral h u bs, or access u n its.

Local Area Networks

Th e oth er top ology often listed in d iscu ssion s of th is typ e is a ring, in wh ich each workstation is con n ected to th e n ext, an d th e last workstation is con n ected to th e first again (essen tially a bu s top ology with th e two en d s con n ected ). Data travels arou n d a Token Rin g n etwork in th is fash ion , for exam p le. However, th e rin g is n ot p h ysically evid en t in th e cablin g layou t for th e n etwork. In fact, th e rin g exists on ly with in th e h u b (called a m ultistation access unit or MSAU on a Token Rin g n etwork). Sign als gen erated from on e com p u ter travel to th e h u b, are sen t ou t to th e n ext com p u ter, an d th en back to th e h u b again . Th e d ata is th en p assed to each system in tu rn u n til it arrives back at th e com p u ter th at origin ated it, wh ere it is rem oved from th e n etwork. Th erefore, alth ou gh th e p h ysical wirin g top ology is a star, th e d ata p ath is th eoretically a rin g. Th is is called a logical ring. Th e logical rin g is p referable to a p h ysical rin g top ology becau se it afford s a greater d egree of fau lt toleran ce. As on a bu s n etwork, a cable break an ywh ere in a p h ysical rin g wou ld affect th e en tire n etwork. On a Token Rin g n etwork, th e MSAU can effectively rem ove a m alfu n ction in g com p u ter from th e logical rin g, allowin g th e rest of th e n etwork to fu n ction n orm ally. Th ese d ifferen t top ologies are often m ixed , form in g wh at is called a hybrid network. For exam p le, you can lin k th e h u bs of several star n etworks togeth er with a bu s, form in g a star-bu s n etwork. Rin gs can be con n ected in th e sam e way. Ne t w o rk Ca b l e In st a l l a t i o n s. If you h ave to ru n cables (of an y typ e) th rou gh existin g walls an d ceilin gs, th e cable in stallation can be th e m ost exp en sive p art of settin g u p a LAN. At every bran ch in g p oin t, sp ecial fittin gs con n ect th e in tersectin g wires. Som etim es you also n eed variou s ad d ition al com p on en ts alon g th e way, su ch as h u bs, rep eaters, or MSAUs.

Not e A few companies, such as M otorola, market LAN technologies that do not require cables at all. Wireless LAN uses infrared, lasers, or radio waves to carry network signals from computer to computer. These technologies are uniquely suited to certain specialized environments, but have not yet achieved the speed and reliability needed for general use.

Plan n in g th e cable layou t, cu ttin g th e cable, attach in g con n ectors, an d in stallin g th e cables an d fittin gs are jobs u su ally best left to exp erien ced workers. If th e fittin gs are n ot p erfect, you m ay get electron ic ech oes on th e n etwork, wh ich cau se tran sm ission errors. Th ere are also a great m an y p h ysical sp ecification s for each n etwork typ e th at m u st be observed if th e n etwork is to fu n ction p rop erly. On e of th e ad van tages of u sin g UTP cable is th at a great m an y telep h on e system con tractors are fam iliar with th e m ed iu m . In n ew con stru ction , you can h ave you r n etwork cablin g in stalled alon g with th e telep h on e cable. However, m ake su re th at th e con tractor you h ire is aware of th e req u irem en ts for d ata n etworkin g, wh ich are typ ically far m ore strin gen t th an th ose for telep h on e wirin g.

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Bu ild in g cod es alm ost always req u ire you to u se firep roof p len u m cables. (A plenum is th e air sp ace between a d rop ceilin g an d th e floor above it.) Plen u m cables are m ore fireresistan t th an som e oth er cables. A p rofession al cable in staller sh ou ld be fam iliar with th e bu ild in g cod es in you r area, bu t m ake su re of th is before sign in g a con tract. You wou ld be very u p set if you were to h ave ord in ary cable in stalled an d were later told by a bu ild in g in sp ector to rip ou t th e cable an d start over again with th e p rop er kin d . Becau se of th e exp en se an d th e m ess of a cable in stallation , it is a good id ea to h ave th e in staller ru n m ore cable th an you in itially n eed so th at you won ’t h ave to in stall m ore later. Con sid eration for you r n etwork’s growth p oten tial sh ou ld be a p art of every step in th e p lan n in g of you r n etwork. Th e on ly tim e th at you m igh t con sid er in stallin g LAN cable you rself is wh en you h ave a sm all grou p of com p u ters located on ad jacen t d esks an d you d o n ot h ave to p u ll cable th rou gh th e walls or ceilin g. Even in th is case, h owever, m ake su re th at you are aware of th e gu id elin es for th e cable typ e you select, su ch as th e m in im u m an d m axim u m allowed cable len gth s. Se l e c t i n g t h e P ro p e r Ca b l e . As th e d em an d s of n etwork u sers con tin u e for everin creasin g am ou n ts of ban d wid th , an d as m an u factu rers d evelop n ew n etworkin g system s to accom m od ate th em , it soon becom es n ecessary to exam in e th e cap abilities of th e m ost fu n d am en tal p art of th e n etwork in frastru ctu re: th e cable itself. Eth ern et over UTP cable, or 10BaseT, is th e m ed iu m of ch oice in th e m ajority of LAN in stallation s tod ay, alth ou gh 100BaseT (Fast Eth ern et) n etworks are becom in g in creasin gly p op u lar. Th e UTP cable u sed for Eth ern et n etworks was origin ally th e sam e as th at u sed for bu sin ess telep h on e wirin g. Th is is kn own as Category 3, or voice grade UTP cable, m easu red accord in g to a scale th at q u an tifies th e cable’s d ata-tran sm ission cap abilities. Th e cable itself is 24 AW G (Am erican W ire Gau ge, a stan d ard for m easu rin g th e d iam eter of a wire), cop p er tin n ed , with solid con d u ctors, 100–105 oh m ch aracteristic im p ed an ce, an d a m in im u m of two twists p er foot. Category 3 cable is ad eq u ate for n etworks ru n n in g at u p to 16Mbp s. Newer, faster n etwork typ es req u ire greater p erform an ce levels, h owever. Fast Eth ern et tech n ologies th at ru n at 100Mbp s u sin g th e sam e n u m ber of wires as stan d ard Eth ern et n eed a greater resistan ce to sign al crosstalk an d atten u ation . Th erefore, th e u se of Category 5 UTP cablin g is essen tial. If, wh en you are bu ild in g a LAN, you can u se Category 3 wirin g th at is alread y in p lace, by all m ean s d o so. If, h owever, you are p u llin g n ew cable for you r n etwork, th e u se of Category 5 cable is recom m en d ed . Even if you are n ot ru n n in g a h igh -sp eed n etwork tod ay, you will p robably wan t to con sid er it in th e fu tu re.

Caut ion A chain is only as strong as its weakest link, and the same rule holds true for a network cable installation. If you choose to install Category 5 UTP cable, make sure that all the connectors, wall plates, and other hardware components involved are also Category 5.

Local Area Networks

Th e p eop le wh o d esign com p u ter system s love to fin d ways to circu m ven t lim itation s. Man u factu rers of Eth ern et p rod u cts h ave m ad e it p ossible to bu ild n etworks in star, bran ch , an d tree d esign s th at overcom e th e basic lim itation s alread y m en tion ed . You can h ave th ou san d s of com p u ters on a com p lex Eth ern et n etwork. LANs are local becau se th e n etwork ad ap ters an d oth er h ard ware com p on en ts typ ically can n ot sen d LAN m essages m ore th an a few h u n d red feet. Table 11.4 lists th e d istan ce lim itation s of d ifferen t kin d s of LAN cable. In ad d ition to th e lim itation s sh own in th e table, keep in m in d th at you can n ot con n ect m ore th an 30 com p u ters on a sin gle Th in n et Eth ern et segm en t, m ore th an 100 com p u ters on a Th ickn et Eth ern et segm en t, m ore th an 72 com p u ters on a UTP Token Rin g cable, or m ore th an 260 com p u ters on an STP Token Rin g cable. Table 11.4

Net w ork Dist ance Lim it at ions

Net w ork Adapt er

Cable Type

M axim um

M inim um

Ethernet

Thin

607 ft.

20 in.

Thick (drop cable)

164 ft.

8 ft.

Thick (backbone)

1,640 ft.

8 ft.

UTP

328 ft.

8 ft.

STP

328 ft.

8 ft.

Token Ring

148 ft.

8 ft.

ARCnet (passive hub)

UTP

393 ft.

Depends on cable

ARCnet (active hub)

1,988 ft.

Depends on cable

Dat a Link-Layer Prot ocols Th e p rotocol th at you ch oose to ru n at th e d ata lin k layer is th e sin gle m ost im p ortan t d ecision you m ake wh en d esign in g a local area n etwork. Th is p rotocol d efin es th e sp eed of th e n etwork, th e m ed iu m access con trol m ech an ism it u ses, th e typ es of cables you can u se, th e n etwork in terface ad ap ters th at you m u st bu y, an d th e ad ap ter d rivers th at you in stall in th e n etwork clien t software. Th e In stitu te of Electrical an d Electron ic En gin eers (IEEE) h as d efin ed an d d ocu m en ted a set of stan d ard s for th e p h ysical ch aracteristics of both collision -sen sin g an d token p assin g n etworks. Th ese stan d ard s are kn own as IEEE 802.3 (Eth ern et) an d IEEE 802.5 (Token Rin g). Be aware, h owever, th at th e colloq u ial n am es Eth ern et an d Token Rin g actu ally refer to earlier version s of th ese p rotocols, u p on wh ich th e IEEE stan d ard s were based . Th ere are m in or d ifferen ces between th e fram e d efin ition s for tru e Eth ern et an d tru e IEEE 802.3. In term s of th e stan d ard s, IBM’s 16Mbp s Token Rin g p rod u cts are an exten sion of th e IEEE 802.5 stan d ard . Th ere is also an old er d ata lin k p rotocol called ARCn et th at is n ow rarely u sed . Th e followin g section s exam in e th ese d ata lin k-layer p rotocols.

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ARCnet . ARCnet is on e of th e old est typ es of LAN. It origin ally was a p rop rietary sch em e of th e Datap oin t Corp oration , bu t oth er com p an ies also began to m an u factu re ARCn etcom p atible h ard ware. By m od ern stan d ard s, ARCn et is very slow, bu t it is forgivin g of m in or errors in in stallation . It is kn own for solid reliability, an d ARCn et cable/ ad ap ter p roblem s are easy to d iagn ose. ARCn et gen erally costs less th an Eth ern et, bu t h ard ware p rices for Eth ern et ad ap ters h ave p lu m m eted so m u ch in recen t years th at th e d ifferen ce in p rice between th e two is n o lon ger th at great an issu e. ARCn et op erates som eth in g like Token Rin g, bu t at th e slower rate of 2.5Mbp s. Et hernet . W ith over 20 m illion in stalled com p u ters, Eth ern et is th e m ost wid ely u sed d ata lin k-layer p rotocol in th e world . Eth ern et-based LANs en able you to in tercon n ect a wid e variety of eq u ip m en t, in clu d in g UNIX workstation s, Ap p le com p u ters, p rin ters, an d PCs. You can bu y Eth ern et ad ap ters from d ozen s of com p etin g m an u factu rers, su p p ortin g all th ree of th e cable typ es d efin ed in th e stan d ard : Th in n et, Th ickn et, an d UTP. Trad ition al Eth ern et op erates at a sp eed of 10Mbp s, bu t th e m ore recen t “Fast Eth ern et” stan d ard s p u sh th is sp eed to 100Mbp s. Fast Eth ern et req u ires ad ap ters, h u bs, an d cables d esign ed to su p p ort th e h igh er sp eed , bu t you can bu y com bin ation d evices th at ru n at both 10Mbp s an d 100Mbp s, en ablin g you to grad u ally u p grad e you r n etwork by in stallin g n ew NICs an d h u bs over an exten d ed p eriod of tim e. Th e Eth ern et sp ecification con sists of th ree elem en ts: ■ Physical-layer specifications. A set of cablin g gu id elin es for th e in stallation of UTP, Th in n et, or Th ickn et cable. ■ The Ethernet Fram e. A fram e form at th at d efin es wh at in form ation goes in to th e h ead er an d footer ap p lied to every p acket of n etwork-layer d ata by th e Eth ern et p rotocol. Th e fram e in clu d es th e h ard ware ad d resses of th e system s sen d in g an d receivin g th e p acket an d th e CRC valu e u sed for error correction . ■ Media Access Control. A m ech an ism u sed to regu late access to th e sh ared n etwork m ed iu m by m u ltip le com p u ters. Becau se com p u ters on a LAN sh are a com m on n etwork m ed iu m (u su ally a cable), th ere m u st be a sch em e to arbitrate each system ’s access to th e n etwork. If two com p u ters tran sm it a p acket at th e sam e tim e, a collision can resu lt, garblin g both p ackets an d cau sin g d ata loss. Th is arbitration sch em e is called a m edia access control (or MAC) m ech an ism , an d Eth ern et n etworks u se a MAC m ech an ism called Carrier Sense, Multiple Access with Collision Detection (CSMA/CD). W h en a com p u ter on an Eth ern et n etwork wan ts to tran sm it, it first listen s to th e n etwork to see if th e n etwork is cu rren tly in u se. If an oth er com p u ter is tran sm ittin g, th e system waits for a wh ile an d th en listen s again . If th e n etwork is clear, th e system tran sm its its d ata. Th is is n ot a foolp roof m eth od , h owever, as it is p ossible for two com p u ters to d etect a clear n etwork an d tran sm it at th e sam e tim e, cau sin g a collision .

Local Area Networks

Collision s are a regu lar an d accep ted occu rren ce on an Eth ern et LAN, an d a good d eal of th e tech n ology is d evoted to d etectin g th em . W h en a com p u ter realizes th at its tran sm ission h as collid ed with an oth er p acket, it waits for a ran d om p eriod of tim e (called a backoff interval) an d tran sm its th e sam e p acket again . Sin ce th e two com p u ters in volved in th e collision u se d ifferen t backoff in tervals, th e ch an ces of a secon d collision are red u ced . W h ile a certain n u m ber of collision s are n orm al an d exp ected on an Eth ern et n etwork, with h igh er am ou n ts of traffic th e freq u en cy of collision s rises, an d resp on se tim es in crease. A satu rated Eth ern et n etwork actu ally can sp en d m ore tim e recoverin g from collision s th an it d oes sen d in g d ata. For th is reason , it is im p ortan t n ot to overbu rd en a sin gle Eth ern et segm en t with too m an y com p u ters. On an Eth ern et n etwork, th e n u m ber of com p u ter con n ection s an d th eir in terven in g d istan ces are th e n etwork’s lim itin g factors. Each cable typ e is su bject to its own d istan ce lim itation s, beyon d wh ich an electrical d evice called a repeater is n eed ed to am p lify th e sign al. W ith ou t rep eaters, stan d in g waves (ad d itive sign al reflection s) wou ld d istort th e sign al an d cau se errors. Becau se th e Eth ern et collision -d etection m ech an ism is h igh ly d ep en d en t on tim in g, you can h ave on ly five 200-m eter segm en ts an d fou r rep eaters wired in series, with a m axim u m of th ree segm en ts con n ected to com p u ters, before th e sign al p rop agation d elay becom es lon ger th an th e m axim u m allowed p eriod for th e d etection of a collision . Oth erwise, th e com p u ters farth est from th e sen d er wou ld be u n able to d eterm in e wh eth er a collision h ad occu rred . Th is is kn own as th e Ethernet 5-4-3 rule. Token Ring. Token Rin g n etworks d iffer su bstan tially from Eth ern et. Origin ally d esign ed by IBM to ru n at 4Mbp s over STP or UTP cable in a logical rin g top ology, th e stan d ard was revised to in clu d e a 16Mbp s version , wh ich is wh at m ost in stallation s u se tod ay. Token Rin g ad ap ters an d h u bs (MSAUs) are con sid erably m ore exp en sive th an th eir Eth ern et cou n terp arts, bu t th is cost can often be ju stified by th e p rotocol’s greater sp eed an d its excellen t p erform an ce even at h igh traffic levels. It takes several secon d s to op en th e ad ap ter con n ection on a Token Rin g LAN. Du rin g th is tim e, th e MSAU an d th e Token Rin g ad ap ter p erform a sm all d iagn ostic ch eck, after wh ich th e MSAU establish es th e com p u ter as a n ew n eigh bor on th e rin g. After bein g establish ed as an active workstation , you r com p u ter is lin ked on both sid es to you r u p stream an d d own stream n eigh bors (as d efin ed by you r p osition on th e MSAU). In its tu rn , you r Token Rin g ad ap ter card accep ts th e token or fram e, regen erates its electrical sign als, an d sen d s th e token or fram e th rou gh th e MSAU in th e d irection of you r d own stream n eigh bor. Token Rin g n etworks u se a d ifferen t typ e of MAC m ech an ism th an Eth ern et LANs, called token passing. On a Token Rin g n etwork, com p u ters con tin u ou sly p ass a sp ecial p acket called a token am on g th em selves. Th e token is ju st a sh ort m essage in d icatin g th at th e com p u ter p ossessin g it is allowed to tran sm it. If a com p u ter h as n o d ata to sen d , it p asses th e token on to th e n ext d own stream com p u ter as soon as it receives it. On ly th e com p u ter h old in g th e token can tran sm it d ata on to th e LAN.

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Every p acket tran sm itted on th e n etwork circu lates th rou gh all th e com p u ters on th e rin g, in clu d in g its in ten d ed d estin ation , an d even tu ally en d s u p back at th e com p u ter th at sen t it. Th e sen d er is th en resp on sible for rem ovin g th e p acket from th e n etwork an d gen eratin g a n ew token , th u s releasin g con trol of th e n etwork to th e n ext system . Becau se it is n ot p ossible for two com p u ters to tran sm it at th e sam e tim e on a p rop erly fu n ction in g Token Rin g n etwork, th ere are n o collision s, an d becau se every com p u ter h as an eq u al op p ortu n ity to tran sm it, n etwork p erform an ce d oes n ot d egrad e at h igh traffic levels. In sp ecial situ ation s, it is also p ossible to assign p riorities to certain com p u ters so th ey get m ore freq u en t access to th e LAN. Som etim es a station fu m bles an d “d rop s” th e token , h owever. W h en th is h ap p en s, th e com p u ters on th e LAN m on itor each oth er an d u se a p roced u re called beaconing to d etect th e location of th e p roblem an d regen erate a lost token .

Early Token Release On a momentarily idle Token Ring LAN, workstations circulate a token. The LAN becomes busy (carries information) when a computer takes possession of the token and transmits a data frame targeted at another computer on the network. After receipt by the target node, the data frame continues circulating around the LAN until it returns to its source node. The source node removes the data frame and generates a new token that circulates until a downstream node needs it. So far, so good—these are just standard Token Ring concepts. When a client sends a file request to a server, it consists of only a few bytes, far fewer than the transmission that returns the actual file to the client. If the request packet has to pass through many other systems to circulate the ring, and if the data frame is small, latency occurs. Latency is the unproductive delay that occurs while the source node waits for its upstream neighbor to return the data frame. During the latency period, the source node appends idle characters onto the LAN following the data frame until the frame circulates the entire LAN and arrives back at the source node. The typical latency period of a 16M bps ring will result in the transmission of 400 or more bytes‘ worth of idle characters. Early Token Release, available only on 16M bps networks, is a feature that enables the originating workstation to transmit a new token immediately after sending its data frame, thus avoiding the latency period. Downstream nodes pass along the data frame and then receive the token, giving them the opportunity to transmit data themselves. If you were to perform a protocol analysis of a network using Early Token Release, you would see tokens and other data frames immediately following the file request, instead of a long trail of idle characters.

High-Speed Net w orking Technologies If you h ave fast com p u ters on you r n etwork, you m ay wan t a fast n etwork as well. Even th e 16Mbp s of a Token Rin g n etwork m ay be too slow if you r ap p lication s are d atain ten sive. Th e exp losive growth of m u ltim ed ia, grou p ware, an d oth er tech n ologies th at req u ire en orm ou s am ou n ts of d ata h as forced n etwork ad m in istrators to con sid er th e n eed for h igh -sp eed n etwork con n ection s to in d ivid u al d esktop system s.

Local Area Networks

Networkin g tech n ologies th at ru n at sp eed s above 16Mbp s h ave been arou n d for several years, bu t th ey h ave p rim arily been lim ited to h igh -sp eed backbon e con n ection s between servers, d u e to th e ad d ition al exp en se. Several n ew tech n ologies are available tod ay, h owever, th at are d esign ed to d eliver d ata at h igh sp eed s—u p to 100Mbp s an d m ore—to stan d ard u ser workstation s. Real-tim e d ata feed s from fin an cial services, vid eocon feren cin g, vid eo ed itin g, an d h igh -color grap h ics p rocessin g are ju st som e of th e tasks n ow bein g p erform ed on PCs th at wou ld ben efit greatly from an in crease in n etwork tran sm ission sp eed . Fiber Dist ribut ed Dat a Int erface. FDDI h as been available for several years, bu t it is still a m u ch n ewer p rotocol th an Eth ern et or Token Rin g. Design ed by th e X3T9.5 Task Grou p of ANSI (th e Am erican Nation al Stan d ard s In stitu te), FDDI p asses token s an d d ata fram es arou n d a d ou ble rin g of op tical fiber cable at a rate of 100Mbp s. Two sep arate rin gs (called th e prim ary an d th e secondary) with traffic travelin g in op p osite d irection s p rovid e fau lt toleran ce in case of a cable break or oth er m alfu n ction . FDDI classifies th e com p u ters on th e n etwork as eith er Class A (con n ected to both rin gs) or Class B (con n ected to th e p rim ary rin g on ly). FDDI was d esign ed to be as m u ch like th e IEEE 802.5 Token Rin g stan d ard as p ossible, above th e p h ysical layer. Differen ces occu r on ly wh ere n ecessary to su p p ort th e faster sp eed s an d lon ger tran sm ission d istan ces of FDDI. If FDDI were to u se th e sam e bit-en cod in g sch em e u sed by Token Rin g, every bit wou ld req u ire two op tical sign als: a p u lse of ligh t an d th en a p au se of d arkn ess. Th is m ean s th at FDDI wou ld n eed to sen d 200 m illion sign als p er secon d to h ave a 100Mbp s tran sm ission rate. In stead , th e sch em e u sed by FDDI—called NRZI 4B/ 5B—en cod es 4 bits of d ata in to 5 bits for tran sm ission so th at fewer sign als are n eed ed to sen d a byte of in form ation . Th e 5-bit cod es (sym bols) were ch osen carefu lly to en su re th at th ey m eet n etwork tim in g req u irem en ts. Th e NRZI 4B/ 5B sch em e, at a 100Mbp s tran sm ission rate, sen d s 125 m illion sign als p er secon d (th is is 125 m egabau d ). Also, becau se each carefu lly selected ligh t p attern sym bol rep resen ts 4 bits (a h alf byte, or nibble), FDDI h ard ware can op erate at th e n ibble an d byte level rath er th an at th e bit level, m akin g it easier to ach ieve th e h igh d ata rate. Th ere are two m ajor d ifferen ces in th e way th at FDDI an d IEEE 802.5 Token Rin g m an age th eir resp ective token s. In trad ition al Token Rin g, a n ew token is circu lated on ly after a sen d in g system gets back th e fram e th at it sen t. In FDDI, a n ew token is circu lated im m ed iately by th e sen d in g system after it fin ish es tran sm ittin g a fram e, a tech n iq u e th at h as sin ce been ad ap ted for u se in Token Rin g n etworks an d called Early Token Release. FDDI classifies th e com p u ters on th e n etwork as eith er asynchronous (system s th at are n ot rigid abou t th e tim e p eriod s th at occu r between n etwork accesses) or synchronous (system s h avin g very strin gen t req u irem en ts regard in g th e tim in g between tran sm ission s). FDDI u ses a com p lex algorith m to allocate n etwork access to th e two classes of d evices.

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Alth ou gh it p rovid es su p erior p erform an ce, FDDI’s accep tan ce as a d esktop n etworkin g solu tion h as been h am p ered by its h igh er in stallation an d m ain ten an ce costs. An altern ative u sin g a m ore con ven tion al cop p er cable, called CDDI (Cop p er Distribu ted Data In terface), is easier to in stall an d m ain tain , bu t d oes n ot p rovid e th e resistan ce to in terferen ce th at en ables fiber-op tic cable to sp an su ch lon g d istan ces. 100M bps Et hernet On e of th e largest barriers to th e im p lem en tation of h igh -sp eed n etworkin g h as been th e n eed for a com p lete rep lacem en t of th e n etworkin g in frastru ctu re. Most com p an ies can n ot afford th e d own tim e n eed ed to rewire th e en tire n etwork, rep lace all th e h u bs an d NICs, an d th en con figu re everyth in g to op erate p rop erly. As a resu lt of th is, som e of th e n ew 100Mbp s tech n ologies are d esign ed to m ake th e u p grad e p rocess easier in several ways. First, th ey can often u se th e n etwork cable th at is alread y in p lace, an d secon d , th ey are com p atible en ou gh with th e existin g in stallation to allow a grad u al ch an geover to th e n ew tech n ology, system by system . Obviou sly, th ese factors also m in im ize th e exp en se associated with su ch an u p grad e. Th e two system s th at take th is ap p roach are 100BaseT , also kn own as Fast Eth ern et, first d evelop ed by th e Gran d Ju n ction Corp ., an d 100V G AnyLAN, ad vocated by HewlettPackard an d AT&T. Both of th ese system s ru n at 100Mbp s over stan d ard UTP cable, bu t th at is wh ere th e sim ilarities en d . In fact, of th e two, on ly 100BaseT can tru ly be called an Eth ern et n etwork. 100BaseT u ses th e sam e CSMA/ CD m ed ia access con trol m ech an ism an d th e sam e fram e layou t d efin ed in th e IEEE 802.3 stan d ard . In fact, 100BaseT h as been ratified as an exten sion to th at stan d ard , called 802.3u. To accom m od ate existin g cable in stallation s, th e 802.3u d ocu m en t d efin es th ree d ifferen t cablin g stan d ard s, as sh own in Table 11.5. Table 11.5

100BaseT Cabling St andards

St andard

Cable Type

Segm ent Lengt h

100BaseTX

Category 5 (2 pairs)

100 meters

100BaseT4

Category 3, 4, or 5 (4 pairs)

100 meters

100BaseFX

62.6 micrometer M ultimode fiber (2 strands)

400 meters

Sites with Category 3 cable alread y in stalled can u se th e system with ou t th e n eed for rewirin g, as lon g as th e fu ll fou r p airs in a typ ical ru n are available.

Not e Despite the apparent wastefulness, it is not recommended that data and voice traffic be mixed within the same cable, even if sufficient wire pairs are available. Digital phone traffic could possibly coexist, but normal analog voice lines will definitely inhibit the performance of the data network.

100BaseT also req u ires th e in stallation of n ew h u bs an d n ew NICs, bu t becau se th e fram e typ e u sed by th e n ew system is id en tical to th at of th e old , th is rep lacem en t can be

Local Area Networks

p erform ed grad u ally, to sp read th e labor an d exp en se over a p rotracted p eriod of tim e. You cou ld rep lace on e h u b with a 100BaseT m od el an d th en switch com p u ters over to it, on e at a tim e, as tim e p erm its. You can even p u rch ase NICs th at can op erate at both 10Mbp s an d 100Mbp s sp eed s to m ake th e ch an geover even easier. 100VG (voice grad e) An yLAN also ru n s at 100Mbp s, an d is sp ecifically d esign ed to u se existin g Category 3 UTP cablin g. Like 100BaseT4, it req u ires fou r p airs of cable stran d s for its com m u n ication s. Th ere is also a sep arate Category 5 cable op tion in th e stan d ard . Beyon d th e cablin g, 100VG An yLAN is q u ite d ifferen t from 100BaseT an d in d eed from Eth ern et. W h ile 10BaseT an d 100BaseT n etworks both reserve on e p air of wires for collision d etection , 100VG-An yLAN is able to tran sm it over all fou r p airs sim u ltan eou sly. Th is tech n iq u e is called quartet signaling. 100VG-An yLAN also u ses a d ifferen t sign al-en cod in g sch em e called 5B/ 6B NRZ, wh ich sen d s 2.5 tim es m ore bits p er cycle th an an Eth ern et n etwork’s Man ch ester en cod in g sch em e. Mu ltip lied by th e fou r p airs of wires (as com p ared to 10BaseT’s on e), you h ave a ten fold in crease in tran sm ission sp eed . Th e fou rth p air of wires is available for tran sm ittin g d ata becau se th ere is n o n eed for collision d etection on a 100VG-An yLAN n etwork. In stead of th e CSMA/ CD m ed ia access system th at d efin es an Eth ern et n etwork, 100VG-An yLAN u ses a bran d -n ew tech n iq u e called dem and priority. In d ivid u al n etwork com p u ters h ave to req u est an d be gran ted p erm ission to tran sm it by th e h u b before th ey can sen d th eir d ata. 100VG-An yLAN can u se th e sam e fram e form ats as IEEE 802.3 Eth ern et an d IEEE 802.5 Token Rin g so th at its traffic can coexist on a LAN with th at of existin g Eth ern et or Token Rin g system s. Like 100BaseT, com bin ation 10/ 100Mbp s NICs are available, an d th e n etwork can be grad u ally m igrated to th e n ew tech n ology. Su p p ort for 100VG-An yLAN h as alm ost com p letely d isap p eared from th e m arket d u e to th e cost of th e ad ap ters an d th e p op u larity of 10/ 100Mbp s Fast Eth ern et ad ap ters. Asynchronous Transfer M ode Asynchronous Transfer Mode, or ATM, is on e of th e n ewest of th e h igh -sp eed tech n ologies. It h as been in an “em ergin g” state for som e tim e n ow, with ou t h avin g d evelop ed in to its fu ll p oten tial. ATM d efin es a p h ysical-layer p rotocol in wh ich a stan d ard -size 53-byte p acket (called a cell ) is u sed to tran sm it voice, d ata, an d real-tim e vid eo over th e sam e cable, sim u ltan eou sly. Th e cells con tain id en tification in form ation th at allows h igh sp eed ATM switch es (wiring hubs) to sep arate th e d ata typ es an d en su re th at th e cells are reassem bled in th e righ t ord er. Th e basic ATM stan d ard ru n s at 155Mbp s, bu t som e im p lem en tation s can go as h igh as 660Mbp s. Th ere is also an ATM d esktop stan d ard th at ru n s at 25Mbp s, bu t th is d oesn ’t seem to be en ou gh of a gain over Token Rin g’s 16Mbp s to be worth th e ad op tion of an en tirely n ew n etworkin g tech n ology. ATM is a rad ically d ifferen t con cep t, an d th ere are n o con ven ien t u p grad e p ath s as th ere are with th e 100Mbp s stan d ard s d escribed earlier. All th e n etworkin g h ard ware m u st be

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rep laced , an d th e p rices of ATM p rod u cts are sign ifican tly h igh er th an th ose of Fast Eth ern et an d oth er h igh -sp eed tech n ologies. For th is reason , ATM is bein g u sed p rim arily for W AN lin ks at th is tim e. W h en th e d elivery of real-tim e vid eo over th e n etwork becom es m ore of a p ractical reality th an it is n ow, ATM m igh t fin d its righ tfu l p lace. For n ow, it rem ain s a n ich e tech n ology. Upper-Layer Prot ocols W h en you ad d n etwork clien t software to a PC, th e first step is to in stall a d river for th e n etwork in terface ad ap ter in th e m ach in e. Th is d river n ot on ly id en tifies th e ad ap ter h ard ware, bu t it im p lem en ts th e d ata lin k-layer p rotocol. Th e n ext step is to in stall su p p ort for th e p rotocols ru n n in g above th e d ata lin k layer. Th ere are u su ally several d ifferen t p rotocols op eratin g at th e u p p er layers, bu t for th e p u rp oses of a clien t in stallation th ey are treated as a sin gle en tity. For exam p le, after in stallin g a d river for th e Eth ern et ad ap ter in you r PC, you can select a p rotocol su ite su ch as TCP/ IP or IPX to work at th e u p p er layers. Both TCP/ IP an d IPX actu ally con sist of several d ifferen t p rotocols, bu t you in stall th em as on e m od u le th at op eratin g system s su ch as W in d ows 9x an d W in d ows NT som ewh at con fu sin gly refer to by th e term protocol. In n early all cases, you can also in stall m u ltip le p rotocol su ites to su p p ort d ifferen t n etworkin g clien ts on th e sam e com p u ter. For exam p le, a sin gle Eth ern et ad ap ter can u se IPX to access NetW are servers an d TCP/ IP to sh are W in d ows NT resou rces, both at th e sam e tim e. Th e followin g section s exam in e th e u p p er-layer p rotocols m ost com m on ly u sed on tod ay’s LANs.

TCP/ IP TCP/ IP stan d s for Transm ission Control Protocol/Internet Protocol. TCP an d IP are sep arate tran sp ort- an d n etwork-layer p rotocols, resp ectively, bu t TCP/ IP is th e colloq u ial n am e given to th e en tire su ite of n etworkin g p rotocols d evelop ed for u se by th e In tern et, of wh ich TCP an d IP are on ly two. Later, th e TCP/ IP p rotocols were ad op ted by th e UNIX op eratin g system s, an d th ey h ave n ow becom e th e m ost com m on ly u sed p rotocol su ite on PC LANs. Virtu ally every op eratin g system with n etworkin g cap abilities su p p orts TCP/ IP, an d it is well on its way to d isp lacin g all th e oth er com p etin g p rotocols. TCP/ IP is an exten sive collection of p rotocols op eratin g at th e ap p lication , tran sp ort, n etwork, an d d ata lin k layers. Th e p rotocols were origin ally d evelop ed by th e U.S. Dep artm en t of Defen se in th e 1970s as a p latform - an d h ard ware-in d ep en d en t m ed iu m for com m u n ication over wh at was to becom e kn own as th e In tern et. A good exam p le of th is in d ep en d en ce is th e cap ability of DOS, W in d ows 3.1, W in d ows 9x, an d W in d ows NT system s to access in form ation an d tran sfer files on th e In tern et, wh ich is a m ixed p latform en viron m en t. Th e p rim ary ad van tages of TCP/ IP are ■ Platform Independence. TCP/ IP is n ot d esign ed for u se in an y sin gle h ard ware or software en viron m en t. It can be u sed an d is bein g u sed on com p u ters an d n etworks of all typ es.

TCP/ IP

■ Absolute Addressing. TCP/ IP p rovid es a m ean s of u n iq u ely id en tifyin g every m ach in e on th e In tern et. ■ Open Standards. Th e TCP/ IP sp ecification s are p u blicly available to u sers an d d evelop ers alike. Su ggestion s for ch an ges to th e stan d ard can be su bm itted by an yon e. ■ Application Protocols. TCP/ IP allows d issim ilar en viron m en ts to com m u n icate. High level p rotocols su ch as FTP an d Teln et h ave becom e u biq u itou s in TCP/ IP en viron m en ts on all p latform s. Alth ou gh th ey h ave been th e p rotocols of ch oice on UNIX n etworks for m an y years, th e exp losive growth of th e In tern et h as brou gh t th e TCP/ IP p rotocols on to all kin d s of LANs as well. Man y n etwork ad m in istrators are fin d in g th at th ey can con figu re all th eir n etwork op eratin g system s to u se TCP/ IP an d th u s lessen th e n etwork traffic p roblem s th at can be cau sed by ru n n in g several d ifferen t sets of p rotocols on th e sam e n etwork. Som e of th e m ost im p ortan t p rotocols of th e TCP/ IP su ite are as follows: ■ Internet Protocol (IP). Op eratin g at th e n etwork layer, IP is th e m ain p rotocol of th e TCP/ IP su ite. It su p p lies n etwork d ata with ad d ressin g an d rou tin g in form ation , an d sp lits p ackets in to sm aller fragm en ts as n eed ed d u rin g th e trip to th eir d estin ation . Th e d ata gen erated by n early all th e oth er TCP/ IP p rotocols is carried with in IP p ackets, called datagram s. ■ Transm ission Control Protocol (TCP). TCP is a reliable, con n ection -orien ted p rotocol op eratin g at th e tran sp ort layer. A reliable p rotocol is on e in wh ich th e d estin ation system retu rn s ackn owled gm en t m essages to th e sen d er, verifyin g th at th e p ackets were received with ou t errors. A connection-oriented p rotocol is on e in wh ich th e two com p u ters exch an ge m essages before tran sm ittin g an y u ser d ata. Th ese m essages establish a con n ection th at rem ain s op en u n til th e d ata tran sm ission is com p leted . TCP is u sed to tran sm it relatively large am ou n ts of d ata, su ch as FTP file tran sfers an d HTTP W eb p age tran saction s. ■ User Datagram Protocol. Also op eratin g at th e tran sp ort layer, UDP is a con n ection less, u n reliable p rotocol, an d th e cou n terp art to TCP. A connectionless p rotocol tran sm its its d ata with ou t kn owin g if th e d estin ation system is read y to receive it, or even if th e d estin ation system exists. An unreliable p rotocol is on e in wh ich th e d estin ation system d oes n ot tran sm it exp licit ackn owled gm en t m essages. Actu ally, UDP is far from u n reliable in th e literal sen se, becau se it is m ostly u sed for sh ort q u ery/ resp on se tran saction s in wh ich th e resp on se fu n ction s as an ackn owled gm en t. Th e In tern et’s Dom ain Nam e System (DNS) u ses UDP for m u ch of its com m u n ication s. ■ Internet Control Message Protocol (ICMP). ICMP d oes n ot carry u ser d ata, bu t is in stead a con trol an d d iagn ostic p rotocol th at is u sed to in form oth er system s of con d ition s an d errors on th e n etwork. Th e TCP/ IP PING u tility u ses ICMP to d eterm in e if an oth er system on a TCP/ IP n etwork is fu n ction in g. ■ Address Resolution Protocol (ARP). ARP is a p rotocol th at IP u ses to con vert its own n etwork-layer ad d resses in to d ata lin k-layer h ard ware ad d resses.

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■ Point-to-Point Protocol (PPP). PPP is a d ata lin k-layer p rotocol, bu t n ot for u se on LANs. PPP is u sed to establish a d irect con n ection between two com p u ters, u su ally u sin g a m od em con n ection . If you u se W in d ows 9x or W in d ows NT’s Dial-Up Networkin g featu re to con n ect to th e In tern et, th en you are p robably u sin g PPP. ■ File Transfer Protocol (FTP). FTP is an ap p lication -layer p rotocol u sed to tran sfer files between TCP/ IP system s. Un like m ost p rotocols, FTP actu ally d efin es th e u ser in terface for an ap p lication . Virtu ally every TCP/ IP im p lem en tation in clu d es a textbased FTP p rogram , an d m an y of th e com m an d s are th e sam e n o m atter wh at op eratin g system you are u sin g. ■ Hypertext Transfer Protocol (HTTP). Op eratin g at th e ap p lication layer, HTTP is th e fu n d am en tal p rotocol of th e W orld W id e W eb. W h en you typ e a URL in you r W eb browser, th e p rogram tran sm its an HTTP req u est to th e server you ’ve sp ecified . Th e server th en resp on d s with an HTTP rep ly con tain in g th e file you req u ested . ■ Sim ple Mail Transfer Protocol (SMTP). SMTP is th e ap p lication -layer p rotocol u sed by m ost e-m ail ap p lication s to sen d m ail over th e In tern et. IPX. Th e IPX p rotocol su ite is th e collective term for th e p rop rietary p rotocols created by Novell for th eir NetW are op eratin g system . Alth ou gh based loosely on som e of th e TCP/ IP p rotocols, th e IPX p rotocol stan d ard s are p rivately h eld by Novell. However, th is h as n ot p reven ted Microsoft from creatin g its own IPX-com p atible p rotocol for th e W in d ows op eratin g system s. IPX (In tern etwork Packet Exch an ge) itself is a con n ection less, u n reliable, n etwork-layer p rotocol, eq u ivalen t in fu n ction to IP. Th e su ite’s eq u ivalen t to TCP is th e Seq u en ced Packet Exch an ge (SPX) p rotocol, wh ich p rovid es con n ection -orien ted , reliable service at th e tran sp ort layer. Th e IPX p rotocols are typ ically u sed tod ay on ly on n etworks with NetW are servers, an d are often in stalled alon g with an oth er p rotocol su ite su ch as TCP/ IP. Even NetW are, h owever, is p h asin g ou t its u se of IPX an d m akin g th e m ove over to TCP/ IP, alon g with th e rest of th e n etworkin g in d u stry. Net BEUI. NetBEUI (NetBIOS Exten d ed User In terface) is a p rotocol u sed p rim arily on sm all W in d ows NT n etworks. It was th e d efau lt p rotocol in W in d ows NT 3.1, th e first version of th at op eratin g system . Later version s, h owever, u se th e TCP/ IP p rotocols as th eir d efau lt. NetBEUI is a sim p le p rotocol th at lacks m an y of th e featu res th at en able p rotocol su ites like TCP/ IP to su p p ort n etworks of alm ost an y size. NetBEUI is n ot rou table, so it can n ot be u sed on large in tern etworks. It is su itable for sm all p eer-to-p eer n etworks, bu t an y seriou s W in d ows NT n etwork in stallation sh ou ld u se TCP/ IP.

Chapter 12

12

M agnetic Storage

Most of th e storage m ed ia in p erson al com p u ter system s op erate on m agn etic p rin cip les. Pu rely op tical d evices like CD-ROMs are often u sed as a secon d ary form of storage, bu t th e average PC typ ically relies on a m agn etic m ed iu m for its p rim ary d isk storage. Du e to th e h igh p erform an ce an d d en sity cap abilities of m agn etic storage, op tical d isk d rives an d m ed ia p robably will n ever totally rep lace m agn etic storage in PC system s. Th is ch ap ter exam in es th e variou s form s of m agn etic storage m ed ia u sed in com p u ter system s, from th e flop p y d isk d rives an d h ard d isk d rives fou n d in virtu ally every PC to th e rem ovable m ass storage m ed ia, like cartrid ge an d tap e d rives, th at are becom in g in creasin gly p op u lar op tion s. In th is ch ap ter you learn abou t h ow m agn etic d ata storage works an d h ow it can h elp you d evelop a feel for th e way you r com p u ter’s d rives op erate. ◊◊ See “ CD-ROM Disc and Drive Formats,” p. 838

Principles of M agnet ic St orage All m agn etic storage d evices, su ch as flop p y d isk d rives an d h ard d isk d rives, read an d write d ata by u sin g electrom agnetism . Th is basic p rin cip le of p h ysics states th at as an electric cu rren t flows th rou gh a con d u ctor, a m agn etic field is gen erated arou n d th e con d u ctor. Th is m agn etic field can th en exert an in flu en ce on m agn etic m aterial in th e field . W h en th e d irection of th e flow of electric cu rren t is reversed , th e m agn etic field ’s p olarity also is reversed . For exam p le, an electric m otor u ses electrom agn etism to exert p u sh in g an d p u llin g forces on m agn ets attach ed to a rotatin g sh aft. An oth er effect of electrom agn etism is th at if a con d u ctor is p assed th rou gh a ch an gin g m agn etic field , an electrical cu rren t is gen erated . As th e p olarity of th e m agn etic field ch an ges, so d oes th e d irection of th e electric cu rren t’s flow. For exam p le, a typ e of electrical gen erator u sed in au tom obiles, called an alternator, op erates by rotatin g electrom agn ets p ast coils of wire con d u ctors

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th at con tain large am ou n ts of electrical cu rren t. W h en ap p lied to m agn etic storage d evices, th is two-way op eration of electrom agn etism m akes it p ossible to record d ata on a d isk an d read th at d ata back later. Th e read / write h ead s in a m agn etic storage d evice are U-sh ap ed p ieces of con d u ctive m aterial, with th e en d s of th e U situ ated d irectly above (or n ext to) th e su rface of th e actu al d ata storage m ed iu m . Th e U-sh ap ed h ead is wrap p ed with coils of con d u ctive wire, th rou gh wh ich an electric cu rren t can flow. W h en th e d rive logic p asses a cu rren t th rou gh th ese coils, it gen erates a m agn etic field in th e d rive h ead . Reversin g th e p olarity of th e electric cu rren t cau ses th e p olarity of th e gen erated field to ch an ge also. In essen ce, th e h ead s are electrom agn ets wh ose voltage can be switch ed in p olarity very q u ickly. Th e d isk or tap e th at con stitu tes th e actu al storage m ed iu m con sists of som e form of su bstrate m aterial (su ch as Mylar for flop p y d isks or alu m in u m or glass for h ard d isks) on wh ich a layer of m agn etizable m aterial h as been d ep osited . Th is m aterial u su ally is a form of iron oxid e with variou s oth er elem en ts ad d ed . Each of th e in d ivid u al m agn etic p articles on th e storage m ed iu m h as its own m agn etic field . W h en th e m ed iu m is blan k, th e p olarities of th ose m agn etic field s are n orm ally in a state of ran d om d isarray. Becau se th e field s of th e in d ivid u al p articles p oin t in ran d om d irection s, each tin y m agn etic field is can celed ou t by on e th at p oin ts in th e op p osite d irection ; th e cu m u lative effect of th is is a su rface with n o observable field p olarity. W h en a m agn etic field is gen erated by th e d rive’s read / write h ead , th e field ju m p s th e gap between th e en d s of th e U-sh ap e. Becau se a m agn etic field p asses th rou gh a con d u ctor m u ch m ore easily th an th rou gh th e air, th e field ben d s ou tward from th e h ead an d actu ally u ses th e ad jacen t storage m ed iu m as th e p ath of least resistan ce to th e oth er sid e of th e gap . As th e field p asses th rou gh th e m ed iu m d irectly u n d er th e gap , it p olarizes th e m agn etic p articles th at it tou ch es so th ey are align ed with th e field . Th e field ’s p olarity—an d , th erefore, th e p olarity of th e m agn etic m ed iu m —are based on th e d irection of th e flow of electric cu rren t th rou gh th e coils. W h en th e m agn etic field p asses th rou gh th e m ed iu m , th e p articles in th e area below th e h ead gap are align ed in th e sam e d irection as th e field em an atin g from th e gap . W h en th e in d ivid u al m agn etic d om ain s of th e p articles are in align m en t, th ey n o lon ger can cel on e an oth er ou t, an d an observable m agn etic field exists in th at region of th e m ed iu m . Th is local field is gen erated by th e m an y m agn etic p articles th at n ow are op eratin g as a team to p rod u ce a d etectable cu m u lative field with a u n ified d irection . Th e term flux d escribes a m agn etic field th at h as a sp ecific d irection . As th e su rface of th e m ed iu m m oves across th e d rive h ead , th e h ead can create a m agn etic flu x over a sp ecific region of th e m ed iu m . W h en th e flow of electric cu rren t th rou gh th e coils in th e h ead is reversed , so is th e m agn etic field p olarity in th e h ead gap . Th is reversal also cau ses th e p olarity of th e flu x bein g created on th e m ed iu m to reverse. Th e flux reversal or flux transition is a ch an ge in th e p olarity of th e align ed m agn etic p articles on th e su rface of th e storage m ed iu m . A d rive h ead creates flu x reversals on th e m ed iu m to record d ata. For each d ata bit (or bits) th at a d rive writes, it creates a p attern

Principles of M agnetic Storage

of p ositive-to-n egative an d n egative-to-p ositive flu x reversals on th e m ed iu m in sp ecific areas kn own as bit or tran sition cells. A bit cell or transition cell is a sp ecific area of th e m ed iu m —con trolled by th e tim e an d sp eed at wh ich th e m ed iu m travels—in wh ich th e d rive h ead creates flu x reversals. Th e p articu lar p attern of flu x reversals with in th e tran sition cells th at are u sed to store a given d ata bit (or bits) is called th e encoding m ethod. Th e d rive logic or controller takes th e d ata to be stored an d en cod es it as a series of flu x reversals over a p eriod of tim e, accord in g to th e p attern d ictated by th e en cod in g m eth od it u ses.

Not e The two most popular encoding methods for magnetic media are M odified Frequency M odulation (M FM ) and Run Length Limited (RLL). All floppy disk drives and some older hard disk drives use the

M FM scheme. Today’s hard disk drives use one of several variations on the RLL encoding method. These encoding methods are described in more detail in the next section, “ Data Encoding Schemes.”

Du rin g th e write p rocess, voltage is ap p lied to th e h ead , an d as th e p olarity of th is voltage ch an ges, th e p olarity of th e m agn etic field bein g record ed also ch an ges. Th e flu x tran sition s are written p recisely at th e p oin ts wh ere th e record in g p olarity ch an ges. Stran ge as it m ay seem , d u rin g th e read p rocess, a h ead d oes n ot gen erate exactly th e sam e sign al th at was written . In stead , th e h ead gen erates a voltage p u lse or sp ike on ly wh en it crosses a flu x tran sition . W h en th e tran sition ch an ges from p ositive to n egative, th e p u lse th at th e h ead d etects is a n egative voltage. W h en th e tran sition ch an ges from n egative to p ositive, th e p u lse is a p ositive voltage sp ike. In essen ce, wh ile read in g from th e m ed iu m , th e h ead becom es a flu x tran sition d etector, em ittin g voltage p u lses wh en ever it crosses a tran sition . Areas of n o tran sition gen erate n o p u lse. Figu re 12.1 sh ows th e relation sh ip between th e read an d write waveform s an d th e flu x tran sition s record ed on a storage m ed iu m . You can th in k of th e write p attern as bein g a sq u are waveform th at is at a p ositive or n egative voltage level an d th at con tin u ou sly p olarizes th e storage m ed iu m in on e d irection or an oth er. W h ere th e waveform tran sition s go from p ositive to n egative voltage, or vice versa, th e m agn etic flu x on th e d isk also ch an ges p olarity. Du rin g a read , th e h ead sen ses th e flu x tran sition s an d gen erates a p u lsed waveform . In oth er word s, th e sign al is zero volts u n less th e h ead d etects a p ositive or n egative tran sition , in wh ich case it gen erates a p ositive or n egative p u lse. Pu lses ap p ear on ly wh en th e h ead is p assin g over flu x tran sition s on th e m ed iu m . By kn owin g th e clock tim in g th e d rive u ses, th e con troller circu itry can d eterm in e wh eth er a p u lse (an d th erefore a flu x tran sition ) falls with in a given tran sition cell. Th e electrical p u lse cu rren ts th at are gen erated in th e h ead wh ile it is p assin g over th e storage m ed iu m in read m od e are very weak an d can con tain sign ifican t n oise. Sen sitive electron ics in th e d rive an d con troller assem bly am p lify th e sign al above th e n oise level an d d ecod e th e train of weak p u lse cu rren ts back in to bin ary d ata th at is (th eoretically) id en tical to th e d ata origin ally record ed .

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Chapter 12—M agnetic Storage

Head coil windings

Read/write head and gap

Flux transition

S

Magnetic Media coating

Write waveform

N

N

S

S

N

N Disk rotation

+

-

+ Read waveform

-

FIG. 12.1 Magn etic write an d read p rocesses. So as you can see, h ard d isk d rives an d oth er storage d evices read an d write d ata by m ean s of basic electrom agn etic p rin cip les. A d rive writes d ata by p assin g electrical cu rren ts th rou gh an electrom agn et (th e d rive h ead ), gen eratin g a m agn etic field th at is stored on th e m ed iu m . Th e d rive read s d ata by p assin g th e h ead back over th e su rface of th e m ed iu m . As th e h ead en cou n ters ch an ges in th e stored m agn etic field , it gen erates a weak electrical cu rren t th at in d icates th e p resen ce or absen ce of flu x tran sition s in th e sign al as it was origin ally written . Dat a Encoding Schem es Magn etic storage is essen tially an an alog m ed iu m . Th e d ata th at a PC stores on it, h owever, is d igital in form ation —th at is, on es an d zeros. W h en th e d rive sen d s d igital in form ation to a m agn etic record in g h ead , th e h ead creates m agn etic d om ain s on th e storage m ed iu m with sp ecific p olarities corresp on d in g to th e p ositive an d n egative voltages th at th e d rive ap p lies to th e h ead . It is th e flu x reversals th at form th e bou n d aries between th e areas of p ositive an d n egative p olarity th at th e d rive con troller u ses to en cod e th e d igital d ata on to th e an alog m ed iu m . Du rin g a read op eration , each flu x reversal th at th e d rive d etects gen erates a p ositive or n egative p u lse th at th e d evice u ses to recon stru ct th e origin al bin ary d ata.

Principles of M agnetic Storage

To op tim ize th e p lacem en t of flu x tran sition s d u rin g m agn etic storage, th e d rive p asses th e raw d igital in p u t d ata th rou gh a d evice called an encoder/decoder (endec), wh ich con verts th e raw bin ary in form ation to a waveform th at is m ore con d u cive to th e op tim u m p lacem en t of th e flu x tran sition s (p u lses). Du rin g a read op eration , th e en d ec reverses th e p rocess an d d ecod es th e p u lse train back in to th e origin al bin ary d ata. Over th e years, several d ifferen t sch em es for en cod in g d ata in th is m an n er h ave been d evelop ed ; som e are better or m ore efficien t th an oth ers, wh ich you see later in th is section . Oth er d escrip tion s of th e d ata en cod in g p rocess m ay be m u ch sim p ler, bu t th ey om it th e facts th at m ake som e of th e issu es related to h ard d rive reliability so critical—n am ely, tim in g. En gin eers an d d esign ers are con stan tly “p u sh in g th e en velop e” to stu ff m ore an d m ore bits of in form ation in to th e lim ited q u an tity of m agn etic flu x reversals p er in ch . W h at th ey cam e u p with , essen tially, is a d esign in wh ich th e bits of in form ation are n ot on ly d ecod ed from th e p resen ce or absen ce of flu x reversals, bu t from th e tim in g between th em . Th e m ore accu rately th ey can tim e th e reversals, th e m ore in form ation th at can be en cod ed (an d su bseq u en tly d ecod ed ) from th at tim in g in form ation . In an y form of bin ary sign alin g, th e u se of tim in g is sign ifican t. W h en in terp retin g a read or write waveform , th e tim in g of each voltage tran sition even t is critical. If th e tim in g is off, a given voltage tran sition m ay be recogn ized at th e wron g tim e, an d bits m ay be m issed , ad d ed , or m isin terp reted . To en su re th at th e tim in g is p recise, th e tran sm ittin g an d receivin g d evices m u st be in syn ch . For exam p le, a con secu tive series of ten 0 bits can be in terp reted as n in e or eleven bits if th e tim in g is n ot exactly syn ch ron ized . Th is syn ch ron ization is often accom p lish ed by ad d in g a sep arate tim in g sign al, called a clock signal, to th e tran sm ission between th e two d evices. It is also p ossible for th e clock an d d ata sign als to be com bin ed an d tran sm itted as a sin gle sign al. Most m agn etic d ata en cod in g sch em es u se th is typ e of com bin ation of clock an d d ata sign als. Ad d in g a clock sign al to th e d ata en su res th at th e com m u n icatin g d evices can accu rately in terp ret th e in d ivid u al bit cells. Each bit cell is bou n d ed by two oth er cells con tain in g th e clock tran sition s. By sen d in g clock in form ation alon g with th e d ata, th e clocks rem ain in syn ch , even if th e m ed iu m con tain s a lon g strin g of id en tical 0 bits. Un fortu n ately, th e tran sition cells th at are u sed solely for tim in g take u p sp ace on th e m ed iu m th at cou ld oth erwise be u sed for d ata. Becau se th e n u m ber of flu x tran sition s th at a d rive can record on a p articu lar m ed iu m is lim ited by th e p h ysical n atu re of th e m ed iu m an d th e h ead tech n ology, d rive en gin eers h ave d evelop ed variou s ways of en cod in g th e d ata by u sin g a m in im u m n u m ber of flu x reversals (takin g in to con sid eration th e fact th at som e flu x reversals u sed solely for clockin g are req u ired ). Sign al en cod in g en ables th e system to m ake th e m axim u m u se of a given d rive h ard ware tech n ology. Alth ou gh variou s en cod in g sch em es h ave been tried , on ly a few are p op u lar tod ay. Over th e years, th ese th ree basic typ es h ave been th e m ost p op u lar: ■ Freq u en cy Mod u lation (FM) ■ Mod ified Freq u en cy Mod u lation (MFM)

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■ Ru n Len gth Lim ited (RLL) Th e followin g section s exam in e th ese cod es, d iscu sses h ow th ey work, wh ere th ey are u sed , an d an y ad van tages or d isad van tages th at ap p ly to th em . FM Encoding. On e of th e earliest tech n iq u es for en cod in g d ata for m agn etic storage is called Frequency Modulation (FM) en cod in g. Th is en cod in g sch em e, som etim es called Single Density en cod in g, was u sed in th e earliest flop p y d isk d rives in stalled in PC system s. Th e origin al Osborn e p ortable com p u ter, for exam p le, u sed th ese Sin gle Den sity flop p y d isk d rives, wh ich stored abou t 80K of d ata on a sin gle d isk. Alth ou gh it was p op u lar u n til th e late 1970s, FM en cod in g is n o lon ger u sed . M FM Encoding. Modified Frequency Modulation (MFM) en cod in g was d evised to red u ce th e n u m ber of flu x reversals u sed in th e origin al FM en cod in g sch em e an d , th erefore, to p ack m ore d ata on to th e d isk. MFM en cod in g m in im izes th e u se of clock tran sition cells, leavin g m ore room for th e d ata. MFM record s clock tran sition s on ly wh en a stored 0 bit is p reced ed by an oth er 0 bit; in all oth er cases, a clock tran sition is n ot req u ired . Becau se MFM m in im izes th e u se of clock tran sition s, it can d ou ble th e clock freq u en cy u sed by FM en cod in g, en ablin g it to store twice as m an y d ata bits in th e sam e n u m ber of flu x tran sition s. Becau se it is twice as efficien t as FM en cod in g, MFM en cod in g also h as been called Double Density recording. MFM is u sed in virtu ally all PC flop p y d isk d rives tod ay an d was u sed in n early all PC h ard d isks for a n u m ber of years. Tod ay, virtu ally all h ard d isks u se RLL (Ru n Len gth Lim ited ) en cod in g, wh ich p rovid es even greater efficien cy th an MFM. Becau se MFM en cod in g writes twice as m an y d ata bits by u sin g th e sam e n u m ber of flu x reversals as FM, th e clock sp eed of th e d ata is d ou bled , so th e d rive actu ally sees th e sam e n u m ber of total flu x reversals as with FM. Th is m ean s th at a d rive u sin g MFM en cod in g read s an d writes d ata at twice th e sp eed of FM, even th ou gh th e d rive sees th e flu x reversals arrivin g at th e sam e freq u en cy as in FM. Th e on ly caveat is th at MFM en cod in g req u ires im p roved d isk con troller an d d rive circu itry, becau se th e tim in g of th e flu x reversals m u st be m ore p recise th an in FM. Th ese im p rovem en ts were n ot d ifficu lt to ach ieve, an d MFM en cod in g becam e th e m ost p op u lar en cod in g sch em e for m an y years. Table 12.1 sh ows th e d ata bit to flu x reversal tran slation in MFM en cod in g. Table 12.1

M FM Dat a t o Flux Transit ion Encoding

Dat a Bit Value

Flux Encoding

1

NT

0 preceded by 0

TN

0 preceded by 1

NN

T = Flux transition N = No flux transition

Principles of M agnetic Storage

RLL Encoding. Tod ay’s m ost p op u lar en cod in g sch em e for h ard d isks, called RLL (Run Length Lim ited), p acks u p to 50% m ore in form ation on a given d isk th an MFM d oes an d th ree tim es as m u ch in form ation as FM. In RLL en cod in g, th e d rive com bin es grou p s of bits in to a u n it to gen erate sp ecific p attern s of flu x reversals. By com bin in g th e clock an d d ata sign als in th ese p attern s, th e clock rate can be fu rth er in creased wh ile m ain tain in g th e sam e basic d istan ce between th e flu x tran sition s on th e storage m ed iu m . IBM in ven ted RLL en cod in g an d first u sed th e m eth od in m an y of its m ain fram e d isk d rives. Du rin g th e late 1980s, th e PC h ard d isk in d u stry began u sin g RLL en cod in g sch em es to in crease th e storage cap abilities of PC h ard d isks. Tod ay, virtu ally every d rive on th e m arket u ses som e form of RLL en cod in g. In stead of en cod in g a sin gle bit, RLL n orm ally en cod es a grou p of d ata bits at a tim e. Th e term Run Length Lim ited is d erived from th e two p rim ary sp ecification s of th ese cod es, wh ich is th e m in im u m n u m ber (th e ru n len gth ) an d m axim u m n u m ber (th e ru n lim it) of tran sition cells allowed between two actu al flu x tran sition s. Several variation s of th e sch em e are ach ieved by ch an gin g th e len gth an d lim it p aram eters, bu t on ly two h ave ach ieved an y real p op u larity: RLL 2,7 an d RLL 1,7. You can even exp ress FM an d MFM en cod in g as a form of RLL. FM can be called RLL 0,1, becau se th ere are as few as zero an d as m an y as on e tran sition cells sep aratin g two flu x tran sition s. MFM can be called RLL 1,3, becau se th ere are as few as on e an d as m an y as th ree tran sition cells sep aratin g two flu x tran sition s. (Alth ou gh th ese cod es can be exp ressed as variation s of RLL form , it is n ot com m on to d o so.) RLL 2,7 was in itially th e m ost p op u lar RLL variation becau se it offers a h igh d en sity ratio with a tran sition d etection win d ow th at is th e sam e relative size as th at in MFM. Th is m eth od p rovid es h igh storage d en sity an d fairly good reliability. In very h igh -cap acity d rives, h owever, RLL 2,7 d id n ot p rove to be reliable en ou gh . Most of tod ay’s h igh estcap acity d rives u se RLL 1,7 en cod in g, wh ich offers a d en sity ratio 1.27 tim es th at of MFM an d a larger tran sition d etection win d ow relative to MFM. Becau se of th e larger relative win d ow size with in wh ich a tran sition can be d etected , RLL 1,7 is a m ore forgivin g an d m ore reliable cod e, wh ich is im p ortan t wh en m ed ia an d h ead tech n ology are bein g p u sh ed to th eir lim its. An oth er little-u sed RLL variation called RLL 3,9—som etim es called ARLL (Advanced RLL)—allows an even h igh er d en sity ratio th an RLL 2,7. Un fortu n ately, reliability su ffered too greatly u n d er th e RLL 3,9 sch em e; th e m eth od was u sed by on ly a few con trollers an d h as all bu t d isap p eared . It is d ifficu lt to u n d erstan d h ow RLL cod es work with ou t lookin g at an exam p le. W ith in a given RLL variation su ch as RLL 2,7 or 1,7, you can con stru ct m an y d ifferen t flu x tran sition en cod in g tables to d em on strate h ow p articu lar grou p s of bits are en cod ed in to flu x tran sition s. In th e con version table sh own in Table 12.2, sp ecific grou p s of d ata bits 2, 3, an d 4 bits lon g are tran slated in to strin gs of flu x tran sition s 4, 6, an d 8 tran sition cells lon g,

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Chapter 12—M agnetic Storage

resp ectively. Th e selected tran sition s for a p articu lar bit seq u en ce are d esign ed to en su re th at flu x tran sition s d o n ot occu r too close togeth er or too far ap art. It is n ecessary to lim it h ow close two flu x tran sition s can be becau se of th e fixed resolu tion cap abilities of th e h ead an d th e storage m ed iu m . Lim itin g h ow far ap art two flu x tran sition s can be en su res th at th e clocks in th e d evices rem ain in syn ch . Table 12.2

RLL 2,7 Dat a t o Flux Transit ion Encoding

Dat a Bit Values

Flux Encoding

10

NTNN

11

TNNN

000

NNNTNN

010

TNNTNN

011

NNTNNN

0010

NNTNNTNN

0011

NNNNTNNN

T = Flux transition N = No flux transition

In stu d yin g th is table, you m igh t th in k th at en cod in g a byte valu e su ch as 00000001b wou ld be im p ossible becau se n o com bin ation s of d ata bit grou p s fit th is byte. En cod in g th is typ e of byte is n ot a p roblem , h owever, becau se th e con troller d oes n ot tran sm it in d ivid u al bytes; in stead , th e con troller sen d s wh ole sectors, m akin g it p ossible to en cod e su ch a byte by in clu d in g som e of th e bits in th e followin g byte. Th e on ly real p roblem occu rs in th e last byte of a sector if ad d ition al bits are n eed ed to com p lete th e fin al grou p seq u en ce. In th ese cases, th e en d ec in th e con troller ad d s excess bits to th e en d of th e last byte. Th ese excess bits are tru n cated d u rin g an y read s so th e con troller always d ecod es th e last byte correctly. Encoding Schem e Com parisons Figu re 12.2 sh ows an exam p le of th e waveform written to store th e ASCII ch aracter X on a h ard d isk d rive by u sin g th ree d ifferen t en cod in g sch em es. In each of th ese en cod in g sch em e exam p les, th e top lin e sh ows th e in d ivid u al d ata bits (01011000b) in th eir bit cells sep arated in tim e by th e clock sign al, wh ich is sh own as a p eriod (.). Below th at lin e is th e actu al write waveform , sh owin g th e p ositive an d n egative voltages as well as h ead voltage tran sition s th at resu lt in th e record in g of flu x tran sition s. Th e bottom lin e sh ows th e tran sition cells, with T rep resen tin g a tran sition cell th at con tain s a flu x tran sition an d N rep resen tin g a tran sition cell th at is em p ty. Th e FM en cod in g exam p le is easy to exp lain . Each bit cell h as two tran sition cells: on e for th e clock in form ation an d on e for th e d ata itself. All th e clock tran sition cells con tain flu x tran sition s, an d th e d ata tran sition cells con tain a flu x tran sition on ly if th e d ata is a 1 bit. No tran sition is p resen t wh en th e d ata is a 0 bit. Startin g from th e left, th e first d ata bit is 0, wh ich d ecod es as a flu x tran sition p attern of TN. Th e n ext bit is a 1, wh ich d ecod es as TT. Th e n ext bit is 0, wh ich d ecod es as TN, an d so on .

Principles of M agnetic Storage

FM (RLL 0,1) Encoding (1xClock) . 0 . 1 . 0 . 1 . 1 . 0 . 0 . 0 . + + ----------- ----- ----- ----------- ----- ----- ----- ----- ----------- ----------- --------T N T T T N T T T T T N T N T N MFM (RLL 1,3) Encoding (2xClock) . 0 . 1 . 0 . 1 . 1 . 0 . 0 . 0 . + + -------- ----------- ----- -------- ----- -----T N N T N N N T N T N N T N T N RLL 2,7 Encoding (3xClock) . 0 . 1 . 0 . 1 . 1 . 0 . 0 . 0 . + + ----- ----- ------------- -----T N N T N N T N N N N N N T N N T = Transition (magnetic flux reversal) N = No transition . = Data bit window boundaries (Clock timing)

FIG. 12.2 ASCII ch aracter “X” write waveform s u sin g FM, MFM, an d RLL 2,7 en cod in g. Th e MFM en cod in g sch em e also h as clock an d d ata tran sition cells for each d ata bit to be record ed . As you can see, h owever, th e clock tran sition cells carry a flu x tran sition on ly wh en a 0 bit is stored after an oth er 0 bit. Startin g from th e left, th e first bit is a 0, an d th e p reced in g bit is u n kn own (assu m e 0), so th e flu x tran sition p attern is TN for th at bit. Th e n ext bit is a 1, wh ich always d ecod es to a tran sition -cell p attern of NT. Th e n ext bit is 0, wh ich was p reced ed by 1, so th e p attern stored is NN. By u sin g Table 12.1 sh own earlier, you can easily trace th e MFM en cod in g p attern to th e en d of th e byte. You can see th at th e m in im u m an d m axim u m n u m ber of tran sition cells between an y two flu x tran sition s is on e an d th ree, resp ectively, wh ich exp lain s wh y MFM en cod in g can also be called RLL 1,3. Th e RLL 2,7 p attern is m ore d ifficu lt to see becau se it en cod es grou p s of bits rath er th an in d ivid u al bits. Startin g from th e left, th e first grou p th at m atch es th e grou p s listed in Table 12.2 are th e first th ree bits, 010. Th ese bits are tran slated in to a flu x tran sition p attern of TNNTNN. Th e n ext two bits, 11, are tran slated as a grou p to TNNN; an d th e fin al grou p , 000 bits, is tran slated to NNNTNN to com p lete th e byte. As you can see in th is exam p le, n o ad d ition al bits were n eed ed to fin ish th e last grou p . Notice th at th e m in im u m an d m axim u m n u m ber of em p ty tran sition cells between an y two flu x tran sition s in th is exam p le are 2 an d 6, alth ou gh a d ifferen t exam p le cou ld sh ow a m axim u m of seven em p ty tran sition cells. Th is is wh ere th e RLL 2,7 d esign ation com es from . Becau se even fewer tran sition s are record ed th an in MFM, th e clock rate can be in creased to th ree tim es th at of FM or 1.5 tim es th at of MFM, th u s storin g m ore d ata in th e sam e sp ace. Notice, h owever, th at th e resu ltin g write waveform itself looks exactly like a typ ical FM or MFM waveform in term s of th e n u m ber an d sep aration of th e flu x tran sition s for a given p h ysical p ortion of th e d isk. In oth er word s, th e p h ysical m in im u m an d m axim u m d istan ces between an y two flu x tran sition s rem ain th e sam e in all th ree of th ese en cod in g sch em e exam p les.

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Chapter 12—M agnetic Storage

PRM L ( Part ial-Response, M axim um -Likelihood) An oth er n ew featu re in h igh -en d h ard d isk d rives in volves th e d isk read circu itry. Read ch an n el circu its u sin g Partial-Resp on se, Maxim u m -Likelih ood (PRML) tech n ology en able d isk d rive m an u factu rers to in crease th e am ou n t of d ata stored on a d isk p latter by u p to 40%. PRML rep laces th e stan d ard “d etect on e p eak at a tim e” ap p roach of trad ition al an alog p eak-d etect, read / write ch an n els with d igital sign al p rocessin g. As th e d ata d en sity of h ard d isks in creases, th e d rive m u st n ecessarily record th e flu x reversals closer togeth er on th e m ed iu m . Th is m akes it m ore d ifficu lt to read th e d ata on th e d isk, becau se th e m agn etic p eaks can begin to in terfere with each oth er. PRML m od ifies th e way th at th e d rive read s th e d ata from th e d isk. Th e con troller an alyzes th e an alog d ata stream it receives from th e h ead s by u sin g d igital sign al sam p lin g, p rocessin g, an d d etection algorith m s (th is is th e partial response elem en t) an d p red icts th e seq u en ce of bits th at th e d ata stream is m ost likely to rep resen t (th e m axim um likelihood elem en t). Th is m ay n ot sou n d like a very p recise m eth od of read in g d ata th at m u st be bit-p erfect to be u sable, bu t th e aggregate effect of th e d igital sign al p rocessin g filters ou t th e n oise efficien tly en ou gh to en able th e d rive to p lace th e flu x ch an ge p u lses m u ch closer togeth er on th e p latter, th u s ach ievin g greater d en sities. Capacit y M easurem ent s Th e in d u stry stan d ard abbreviation s for th e u n its u sed to m easu re th e cap acity of m agn etic (an d oth er) d rives are sh own in Table 12.3. Table 12.3

St andard Abbreviat ions and M eanings

Abbreviat ion Descript ion

Decim al Pow er

Decim al Value

Binary Pow er

Binary Value

Kbit or Kb

10 3

1,000

2 10

1,024

10

Kilobit

3

K or KB

Kilobyte

10

1,000

2

M bit or M b

M egabit

10 6

1,000,000

2 20

1,024

M or M B

M egabyte

10 6

1,000,000

2 20

1,048,576

Gbit or Gb

Gigabit

10 9

1,000,000,000

2 30

1,073,741,824

G or GB

Gigabyte

10 9

1,048,576

1,000,000,000

2 30

1,073,741,824

12

1,000,000,000,000

2 40

1,099,511,627,776

1,000,000,000,000

2 40

1,099,511,627,776

Tbit or Tb

Terabit

10

T or TB

Terabyte

10 12

As you can see, each of th ese u n its of m easu rem en t h as two p ossible valu es: a d ecim al (or m etric) on e an d a bin ary on e. Un fortu n ately, th ere are n o d ifferen ces in th e abbreviation s u sed to in d icate th ese two typ es of valu es. In oth er word s, M can in d icate both “m illion s of bytes” an d m egabytes. In gen eral, m em ory valu es are exp ressed by u sin g th e bin ary valu es, alth ou gh d isk cap acities can go eith er way. Th is often lead s to con fu sion in rep ortin g d isk cap acities, becau se m an y m an u factu rers ten d to u se wh ich ever valu e m akes th eir p rod u cts look better. Note also th at wh en bits an d bytes are u sed as p art of som e oth er m easu rem en t, th e d ifferen ce between bits an d bytes is often d istin gu ish ed by th e u se of a lower- or u p p ercase B. For exam p le, m egabits are typ ically abbreviated with a

Hard Disk Drives

lowercase b, resu ltin g in th e abbreviation Mbp s for m egabits p er secon d , wh ile MBp s in d icates m egabytes p er secon d . I h op e th at th is exam in ation of th e basic p rin cip les of m agn etic storage an d th e d ifferen t en cod in g sch em es th at m agn etic d evices u se h as taken som e of th e m ystery ou t of th e way d ata is record ed on a d rive. Th e followin g section s exam in e th e sp ecific d evices th at u se th ese p rin cip les, su ch as h ard d isk, flop p y d isk, rem ovable cartrid ge, an d tap e d rives.

Hard Disk Drives To m an y u sers, th e h ard d isk d rive is th e m ost im p ortan t, an d yet th e m ost m ysteriou s, p art of a com p u ter system . A hard disk drive is a sealed u n it th at a PC u ses for n on volatile d ata storage. Non volatile, or p erm an en t storage, in th is case, m ean s th at th e storage d evice retain s th e d ata even wh en th ere is n o p ower su p p lied to th e com p u ter. Becau se th e h ard d isk d rive is exp ected to retain its d ata u n til a u ser d eliberately erases it, th e PC u ses it to store its m ost cru cial p rogram m in g an d d ata. As a resu lt, wh en th e h ard d isk fails, th e con seq u en ces are u su ally very seriou s. To m ain tain , service, an d exp an d a PC system p rop erly, you m u st u n d erstan d h ow th e h ard d isk u n it fu n ction s. Most com p u ter u sers wan t to kn ow h ow h ard d isk d rives work an d wh at to d o wh en a p roblem occu rs. However, few books abou t h ard d isks cover th is su bject in th e d etail n ecessary for th e PC tech n ician or sop h isticated u ser. Th is section corrects th at situ ation , by th orou gh ly d escribin g th e h ard d isk d rive from a p h ysical, m ech an ical, an d electrical p oin t of view. Definit ion of a Hard Disk A h ard d isk d rive con tain s rigid , d isk-sh ap ed p latters, u su ally con stru cted of alu m in u m or glass. Un like flop p y d isks, th e p latters can n ot ben d or flex—h en ce th e term hard disk. In m ost h ard d isk d rives, you can n ot rem ove th e p latters, wh ich is wh y th ey are som etim es called fixed disk drives. Rem ovable h ard d isk d rives are also available. Som etim es th is term refers to a d evice in wh ich th e en tire d rive u n it (th at is, th e d isk an d th e d rive) is rem ovable, bu t it is m ore com m on ly u sed to refer to cartrid ge d rives, su ch as th e Iom ega Zip an d Jaz d rives, th at h ave rem ovable storage m ed ia.

Not e Hard disk drives were at one time called Winchester drives. This term dates back to the 1960s, when IBM developed a high-speed hard disk drive that had 30M of fixed-platter storage and 30M of removable-platter storage. That drive, the 30-30 drive, soon received the nickname Winchester after the famous Winchester 30-30 rifle. For a time after that, all drives that used a high-speed spinning platter with a floating head were known colloquially as Winchester drives.

Hard Drive Advancem ent s. In th e 15 or m ore years th at h ard d isks h ave com m on ly been u sed in PC system s, th ey h ave u n d ergon e trem en d ou s ch an ges. To give you an id ea of h ow far h ard d rives h ave com e in th at tim e, th e followin g are som e of th e m ost p rofou n d ch an ges in PC h ard d isk storage:

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■ Maxim u m storage cap acities h ave in creased from th e 10M 5 1/ 4-in ch fu ll-h eigh t d rives available in 1982 to 20G or m ore for sm all 3 1/ 2-in ch h alf-h eigh t d rives, an d 10G or m ore for n otebook system 2 1/ 2-in ch d rives. Hard d rives sm aller th an 2G are rare in tod ay’s p erson al com p u ters. ■ Data tran sfer rates from th e m ed ia (su stain ed ) h ave in creased from 85 to 102K/ sec for th e origin al IBM XT in 1983 to 30M/ sec or m ore for som e of th e fastest d rives tod ay. ■ Average seek tim es h ave d ecreased from m ore th an 85m s (m illisecon d s) for th e 10M XT h ard d isk in 1983 to fewer th an 8m s for som e of th e fastest d rives tod ay. ■ In 1982, a 10M d rive cost m ore th an $1,500 ($150 p er m egabyte). Tod ay, th e cost of h ard d rives h as d rop p ed to 3 cen ts p er m egabyte or less! Areal Densit y. Areal d en sity is often u sed as a tech n ology-growth -rate in d icator for th e h ard d isk d rive in d u stry. Areal density is d efin ed as th e p rod u ct of th e lin ear bits p er in ch (BPI), m easu red alon g th e len gth of th e tracks arou n d th e d isk, m u ltip lied by th e n u m ber of tracks p er in ch (TPI) m easu red rad ially on th e d isk. Th e resu lts are exp ressed in u n its of m egabits or gigabits p er sq u are in ch (Mbit/ sq -in ch or Gbit/ sq -in ch ) an d are u sed as a m easu re of efficien cy in d rive record in g tech n ology. Cu rren t h igh -en d 3 1/ 2-in ch d rives record at areal d en sities of n early 3Gb/ sq -in ch . Prototyp e d rives with d en sities as h igh as 10Gbit/ sq -in ch n ow exist, p rovid in g cap acities of m ore th an 20G on a sin gle 2 1/ 2-in ch p latter. Areal d en sity (an d , th erefore, d rive cap acity) h as been d ou blin g ap p roxim ately every two to th ree years, wh ich will soon en able m an u factu rers to bu ild 20 or 30G d rives th at fit in th e p alm of you r h an d . Com p an ies are also d evelop in g n ew m ed ia an d h ead tech n ologies to su p p ort th ese h igh er areal d en sities, su ch as ceram ic or glass p latters, MR (Magn eto-Resistive) h ead s, p seu d o-con tact record in g, an d PRML (Partial-Resp on se, Maxim u m -Likelih ood ) electron ics. Th e p rim ary ch allen ge in ach ievin g h igh er d en sities is m an u factu rin g d rive h ead s an d d isks to op erate at closer toleran ces. To fit m ore d ata on a p latter of a given size, th e tracks m u st be p laced closer togeth er, an d th e h ead s m u st be able to ach ieve greater p recision in th eir p lacem en t over th e tracks. Th is m ean s th at as h ard d isk cap acities in crease, h ead s m u st rid e ever closer to th e d isk su rface. Hard Disk Drive Operat ion Th e basic p h ysical con stru ction of a h ard d isk d rive con sists of sp in n in g d isks with h ead s th at m ove over th e d isks an d store d ata in tracks an d sectors. Th e h ead s read an d write d ata in con cen tric rin gs called tracks, wh ich are d ivid ed u p in to segm en ts called sectors, wh ich n orm ally store 512 bytes each (see Figu re 12.3). Hard d isk d rives u su ally h ave m u ltip le d isks, called platters, th at are stacked on top of each oth er an d sp in in u n ison , each with two sid es on wh ich th e d rive stores d ata. Most d rives h ave at least two or th ree p latters, resu ltin g in fou r or six sid es, an d som e d rives h ave u p to 11 or m ore p latters. Th e id en tically p osition ed tracks on each sid e of every p latter togeth er m ake u p a cylinder (see Figu re 12.4). A h ard d isk d rive n orm ally h as on e h ead p er p latter sid e, with all th e h ead s m ou n ted on a com m on carrier d evice, or rack.

Hard Disk Drives

Th e h ead s m ove rad ially in an d ou t across th e d isk in u n ison ; th ey can n ot m ove in d ep en d en tly, becau se th ey are m ou n ted on th e sam e rack.

One Track

One Sector

FIG. 12.3 Th e tracks an d sectors of a h ard d isk d rive.

These tracks on each platter form a cylinder

FIG. 12.4 A h ard d isk cylin d er.

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Origin ally, m ost h ard d isks sp u n at 3,600 RPM—ap p roxim ately 10 tim es faster th an a flop p y d isk d rive. Un til recen tly, 3,600 RPM was p retty m u ch a con stan t am on g h ard d rives. Now, h owever, q u ite a few h ard d rives sp in th e d isks even faster. Th e Tosh iba 3.3G d rive in m y n otebook com p u ter sp in s at 4,852 RPM; oth er d rives sp in as fast as 5,400, 5,600, 6,400, 7,200, an d even 10,000 RPM. High rotation al sp eed s com bin ed with a fast h ead -p osition in g m ech an ism an d m ore sectors p er track are wh at m ake on e h ard d isk faster th an an oth er. Th e h ead s in m ost h ard d isk d rives d o n ot (an d sh ou ld n ot!) tou ch th e p latters d u rin g n orm al op eration . W h en th e h ead s are p owered off, h owever, th ey lan d on th e p latters as th ey stop sp in n in g. W h ile th e d rive is ru n n in g, a very th in cu sh ion of air keep s each h ead su sp en d ed a sh ort d istan ce above or below th e p latter. If th e air cu sh ion is d istu rbed by a p article of d u st or a sh ock, th e h ead m ay com e in to con tact with th e p latter wh ile it is sp in n in g at fu ll sp eed . W h en con tact with th e sp in n in g p latters is forcefu l en ou gh to d o d am age, th e even t is called a head crash. Th e resu lt of a h ead crash m ay be an yth in g from a few lost bytes of d ata to a com p letely ru in ed d rive. Most d rives h ave sp ecial lu brican ts on th e p latters an d h ard en ed su rfaces th at can with stan d th e d aily “takeoffs an d lan d in gs” as well as m ore severe abu se. Becau se th e p latter assem blies are sealed an d n on -rem ovable, th e track d en sities on th e d isk can be very h igh . Man y d rives h ave 3,000 or m ore TPI (tracks p er in ch ) of m ed ia. Head Disk Assem blies (HDAs), wh ich con tain th e p latters, are assem bled an d sealed in clean room s u n d er absolu tely san itary con d ition s. Becau se few com p an ies rep air HDAs, rep air or rep lacem en t of th e p arts in sid e a sealed HDA can be exp en sive. Every h ard d isk ever m ad e even tu ally fails. Th e on ly q u estion s are wh en th e failu re will occu r an d wh eth er you r d ata is backed u p .

Caut ion It is strongly recommended that you do not even attempt to open a hard disk drive’s HDA unless you have the equipment and the expertise to make repairs inside. M ost manufacturers deliberately make the HDA difficult to open, to discourage the intrepid do-it-yourselfer, and opening the HDA almost certainly voids the drive’s warranty.

Man y PC u sers th in k th at h ard d isks are fragile, an d com p aratively sp eakin g, th ey are on e of th e m ore fragile com p on en ts in you r PC. In m y weekly PC Hard ware an d Trou blesh ootin g or Data Recovery sem in ars, h owever, I h ave ru n variou s h ard d isks for d ays with th e lid s off, an d h ave even rem oved an d in stalled th e covers wh ile th e d rives were op eratin g. Th ose d rives con tin u e to store d ata p erfectly to th is d ay with th e lid s eith er on or off. Of cou rse, I d o n ot recom m en d th at you try th is test with you r own d rives, n or wou ld I d o th is with m y larger, m ore exp en sive d rives. The Ult im at e Hard Disk Drive Analogy. I’m su re th at you h ave h eard th e trad ition al an alogy th at com p ares th e in teraction of th e h ead s an d th e m ed iu m in a typ ical h ard d isk d rive as bein g sim ilar in scale to a 747 flyin g a few feet off th e grou n d at cru isin g sp eed (500+ m p h ). I h ave h eard th is an alogy u sed over an d over again for years, an d I’ve

Hard Disk Drives

even u sed it in m y sem in ars m an y tim es with ou t ch eckin g to see wh eth er th e an alogy is tech n ically accu rate with resp ect to m od ern h ard d rives. It isn ’t. On e h igh ly in accu rate asp ect of th e 747 an alogy h as always both ered m e—th e u se of an airp lan e of an y typ e to d escribe th e h ead -an d -p latter in teraction . Th is an alogy im p lies th at th e h ead s fly very low over th e su rface of th e d isk—bu t tech n ically, th is is n ot tru e. Th e h ead s d o n ot fly at all, in th e trad ition al aerod yn am ic sen se; in stead , th ey float on a cu sh ion of air th at’s bein g d ragged arou n d by th e p latters. A m u ch better an alogy wou ld u se a h overcraft in stead of an airp lan e; th e action of a h overcraft m u ch m ore closely em u lates th e action of th e h ead s in a h ard d isk d rive. Like a h overcraft, th e d rive h ead s rely som ewh at on th e sh ap e of th e bottom of th e h ead to cap tu re an d con trol th e cu sh ion of air th at keep s th em floatin g over th e d isk. By n atu re, th e cu sh ion of air on wh ich th e h ead s float form s on ly in very close p roxim ity to th e p latter an d is often called an air bearing by th e d isk d rive in d u stry. I th ou gh t it was tim e to com e u p with a n ew an alogy th at m ore correctly d escribes th e d im en sion s an d sp eed s at wh ich a h ard d isk d rive op erates tod ay. I looked u p th e sp ecification s on a sp ecific h ard d isk d rive, an d th en m agn ified an d rescaled all th e d im en sion s in volved to m ake th e h ead floatin g h eigh t eq u al to 1 in ch . For m y exam p le, I u sed a Seagate m od el ST-12550N Barracu d a 2 d rive, wh ich is a 2G (form atted cap acity), 3 1/ 2in ch SCSI-2 d rive, h ard ly state of th e art by tod ay’s rap id ly ch an gin g stan d ard s. Table 12.4 sh ows th e sp ecification s of th e Barracu d a d rive, as listed in th e tech n ical d ocu m en tation . Table 12.4

Seagat e ST-12550N Barracuda 2, 3 1/ 2-inch, SCSI-2 Drive

Specificat ions Specificat ion

Value

Unit of M easure

Linear density

52,187

Bits Per Inch (BPI)

Bit spacing

19.16

M icro-inches ( µ-in)

Track density

3,047

Tracks Per Inch (TPI)

Track spacing

328.19

M icro-inches ( µ-in)

Total tracks

2,707

Tracks

Rotational speed

7,200

Revolutions per minute (RPM )

Average head linear speed

53.55

M iles per hour (M PH)

Head slider length

0.08

Inches

Head slider height

0.02

Inches

Head floating height

5

M icro-inches ( µ-in)

Average seek time

8

M illiseconds (ms)

By in terp retin g th ese sp ecification s, you can see th at in th is d rive, th e h ead slid ers are abou t 0.08-in ch lon g an d 0.02-in ch h igh . Th e h ead s float on a cu sh ion of air abou t 5 µ-in (m illion th s of an in ch ) from th e su rface of th e d isk wh ile travelin g at an average sp eed of 53.55 MPH (figu rin g an average track d iam eter of 2 1/ 2 in ch es). Th ese h ead s

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Chapter 12—M agnetic Storage

read an d write in d ivid u al bits sp aced on ly 19.16 µ-in ap art on tracks sep arated by on ly 328.19 µ-in . Th e h ead s can m ove from on e track to an y oth er in on ly 8m s d u rin g an average seek op eration . To create m y an alogy, I m agn ified th e scale to m ake th e h ead floatin g h eigh t eq u al to 1 in ch . Becau se 1 in ch is 200,000 tim es greater th an 5 µ-in , I scaled u p everyth in g else by th e sam e am ou n t. Magn ified to su ch a scale, th e h ead s of th is typ ical h ard d isk in m y an alogy wou ld be m ore th an 1,300 feet lon g an d 300 feet h igh (abou t th e size of th e Sears Tower lyin g sid eways!) Th e h ead s wou ld float on a cu sh ion of air th at travels at a sp eed of m ore th an 10.7 m illion MPH (2,975 m iles p er secon d ) on ly 1 in ch above th e grou n d an d read s d ata bits sp aced a m ere 3.83 in ch es ap art on tracks sep arated by on ly 5.47 feet. Becau se th e average seek tim e of 8m s (.008 secon d s) is d efin ed as th e tim e it takes to m ove th e h ead s over on e-th ird of th e total tracks (abou t 902, in th is case), each skyscrap er-size h ead cou ld m ove sid eways to an y track with in a d istan ce of 0.93 m iles (902 tracks×5.47 feet). Th is resu lts in an average sid eways velocity of m ore th an 420,000 MPH (116 m iles p er secon d )! Th e forward sp eed of th is im agin ary h ead is d ifficu lt to com p reh en d , so I’ll elaborate. Th e d iam eter of th e Earth at th e eq u ator is 7,926 m iles, wh ich m ean s a circu m feren ce of abou t 24,900 m iles. At 2,975 m iles p er secon d , th is im agin ary h ead wou ld circle th e Earth abou t on ce every 8 secon d s! Th is an alogy sh ou ld give you a n ew ap p reciation of th e tech n ological m arvel th at th e m od ern h ard d isk d rive actu ally rep resen ts. It m akes th e 747 an alogy look rath er arch aic (n ot to m en tion totally in accu rate), d oesn ’t it? Sect ors. A d isk track is too large to m an age d ata effectively as a sin gle storage u n it. Man y d isk tracks can store 50,000 or m ore bytes of d ata, wh ich wou ld be very in efficien t for storin g sm all files. For th at reason , tracks are d ivid ed in to several n u m bered d ivision s kn own as sectors. Th ese sectors rep resen t slices of th e track. Variou s typ es of d isk d rives sp lit th eir d isk tracks in to d ifferen t n u m bers of sectors, d ep en d in g on th e d en sity of th e tracks. For exam p le, flop p y d isk form ats u se 8–36 sectors p er track, alth ou gh h ard d isks u su ally store d ata at a h igh er d en sity an d can u se 17–100 or m ore sectors p er track. Th e sectors created by th e stan d ard form attin g p roced u re on a PC system h ave a cap acity of 512 bytes, bu t th is cap acity m ay ch an ge in th e fu tu re. Th e sectors on a track are n u m bered startin g with 1, u n like th e h ead s or cylin d ers th at are n u m bered startin g with 0. For exam p le, a 1.44M flop p y d isk con tain s 80 cylin d ers n u m bered from 0 to 79 an d two h ead s n u m bered 0 an d 1, wh ile each track on each cylin d er h as 18 sectors n u m bered from 1 to 18. W h en a d isk is form atted , th e form attin g p rogram creates ID areas on th e d isk th at th e d isk con troller u ses for sector n u m berin g an d for id en tifyin g th e start an d en d of each sector. Th ese areas p reced e an d follow each sector’s d ata area, wh ich accou n ts for th e d ifferen ce between a d isk’s u n form atted an d form atted cap acities.

Hard Disk Drives

Each sector on a d isk h as a prefix portion, or h ead er, th at id en tifies th e start of th e sector an d con tain s th e sector n u m ber, as well as a suffix portion, or trailer, th at con tain s a checksum (wh ich h elp s en su re th e in tegrity of th e d ata con ten ts). Each sector also con tain s 512 bytes of d ata. Th e low-level form attin g p rocess n orm ally fills th e d ata bytes with som e sp ecific valu e, su ch as F6h (h ex). In m an y cases, th e low-level form at fills th e d ata bytes with a sp ecific p attern th at is con sid ered to be d ifficu lt to write so as to flu sh ou t an y m argin al sectors.

Not e The type of disk formatting discussed here is a physical or low-level format, not the high-level format that you perform when you use the Windows 9x Explorer or the DOS FORMAT program on a disk. See the “ Disk Formatting” section later in this chapter to learn about the difference between these two types of formatting.

Th e sector h ead ers an d trailers are in d ep en d en t of th e op eratin g system , th e file system , an d th e files stored on th e d rive. In ad d ition to th e h ead ers an d trailers, th ere are gap s with in th e sectors, between th e sectors on each track, an d also between tracks, bu t n on e of th ese gap s con tain s u sable d ata sp ace. Th e p refix, su ffix, an d gap s accou n t for th e lost sp ace between th e u n form atted cap acity of a d isk an d th e form atted cap acity. For exam p le, a 4M flop p y d isk (3 1/ 2-in ch ) h as a cap acity of 2.88M wh en it is form atted , a 2M flop p y h as a form atted cap acity of 1.44M, an d an old er 38M h ard d isk h as a cap acity of on ly 32M wh en it is form atted . Becau se th e IDE an d SCSI h ard d rives you p u rch ase tod ay are low-level form atted at th e factory, th e m an u factu rers n ow on ly ad vertise th e form atted cap acity. Even so, n early all d rives u se som e reserved sp ace for m an agin g th e d ata th at will be stored on th e d rive. Th u s, wh ile I stated earlier th at each d isk sector is 512 bytes in size, th is statem en t is tech n ically n ot tru e. Each sector d oes allow for th e storage of 512 bytes of d ata, bu t th e d ata area is on ly a p ortion of th e sector. Each sector on a d isk typ ically occu p ies 571 bytes of th e d isk, of wh ich on ly 512 bytes are available for th e storage of u ser d ata. Th e actu al n u m ber of bytes req u ired for th e sector h ead er an d trailer can vary from d rive to d rive, bu t th is figu re is typ ical. A few m od ern d rives n ow u se an ID-less record in g sch em e th at virtu ally elim in ates th e storage overh ead of th e sector h ead er in form ation . In an IDless record in g, virtu ally all th e sp ace on th e track is occu p ied by d ata. You m ay fin d it h elp fu l to th in k of each d isk sector as bein g a p age in a book. In a book, each p age con tain s text, bu t th e en tire p age is n ot filled with text; rath er, each p age h as top , bottom , left, an d righ t m argin s. In form ation su ch as ch ap ter titles (track an d cylin d er n u m bers) an d p age n u m bers (sector n u m bers) is p laced in th e m argin s. Th e “m argin ” areas of a sector are created an d written to d u rin g th e low-level form attin g p rocess. Form attin g also fills th e d ata area of each sector with d u m m y valu es. After you p erform a h igh -level form at on th e d isk, th e PC’s file system can write to th e d ata area of each sector, bu t th e sector h ead er an d trailer in form ation can n ot be altered d u rin g n orm al write op eration s u n less th e d isk is low-level form atted again .

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Chapter 12—M agnetic Storage

Table 12.5 sh ows th e form at for each track an d sector on a typ ical h ard d isk d rive with 17 sectors p er track. Table 12.5

Typical 17-Sect or/ 17-Track Disk Sect or Form at

Byt es

Nam e

Descript ion

POST INDEX GAP

All 4Eh, at the track beginning after the Index mark.

16

The following sector data (shown between the lines in this table) is repeated 17 times for an M FM encoded track. 13

ID VFO LOCK

All 00h; synchronizes the VFO for the sector ID.

1

SYNC BYTE

A1h; notifies the controller that data follows.

1

ADDRESS M ARK

FEh; defines that ID field data follows.

2

CYLINDER NUM BER

A value that defines the actuator position.

1

HEAD NUM BER

A value that defines the head selected.

1

SECTOR NUM BER

A value that defines the sector.

2

CRC

Cyclic Redundancy Check to verify ID data.

3

WRITE TURN-ON GAP

00h written by format to isolate the ID from DATA.

13

DATA SYNC VFO LOCK

All 00h; synchronizes the VFO for the DATA.

1

SYNC BYTE

A1h; notifies the controller that data follows.

1

ADDRESS M ARK

F8h; defines that user DATA field follows.

DATA

The area for user DATA.

CRC

Cyclic Redundancy Check to verify DATA.

512 2 3 15 693

571 512 10,416 8,704

WRITE TURN-OFF GAP

00h; written by DATA update to isolate DATA.

INTER-RECORD GAP

All 00h; a buffer for spindle speed variation.

PRE-INDEX GAP

All 4Eh, at track end before Index mark.

Total bytes per sector Data bytes per sector Total bytes per track Data bytes per track

Th is table refers to a h ard d isk track with 17 sectors. Alth ou gh th is cap acity was typ ical d u rin g th e m id 1980s, m od ern h ard d isks p lace as m an y as 150 or m ore sectors p er track, an d th e sp ecific form ats of th ose sectors m ay d iffer sligh tly from th is exam p le. As you can see, th e u sable sp ace on each track is abou t 16% less th an its u n form atted cap acity. Th is is tru e for m ost d isks, alth ou gh th e p ercen tage m ay vary sligh tly. Th e followin g p aragrap h s d etail each p iece of th e sector d ata listed in Table 12.5. Th e POST INDEX GAP p rovid es a h ead -switch in g recovery p eriod , so wh en switch in g from on e track to an oth er, th e h ead s can read seq u en tial sectors with ou t waitin g for an ad d ition al revolu tion of th e d isk. Becau se th e d isk is con tin u ou sly sp in n in g an d th e h ead s take som e sm all am ou n t of tim e to m ove rad ially from track to track, it is n ot p ossible to read con secu tive sectors on two d ifferen t tracks on e righ t after th e oth er. By th e tim e th e h ead m oves to th e n ew track, th e begin n in g of th e secon d sector h as alread y sp u n p ast it. Leavin g a gap between sectors p rovid es th e h ead s with tim e to m ove to an oth er track.

Hard Disk Drives

In som e d rives, th is gap d oes n ot p rovid e su fficien t tim e for th e h ead s to m ove. W h en th is is th e case, it is p ossible for a d rive to gain ad d ition al tim e by skewin g th e sectors on d ifferen t tracks so th e arrival of th e first sector is d elayed . In oth er word s, th e low-level form attin g p rocess offsets th e sector n u m berin g, so in stead of th e sam e n u m bered sectors on each track bein g ad jacen t to each oth er, sector 9 on on e track m ay be n ext to sector 8 of th e n ext track, wh ich is n ext to sector 7 on th e n ext, an d so forth . Th e op tim u m skew valu e is based on th e rotation al sp eed of th e d isk as com p ared to th e lateral sp eed of th e h ead s.

Not e At one time, the head skew was a parameter that you could set yourself while low-level formatting a drive. Today’s IDE and SCSI drives are low-level formatted at the factory with the optimum skew values.

Th e Sector ID d ata con sists of th e Cylin d er, Head , an d Sector Nu m ber field s, as well as a CRC field u sed to verify th e ID d ata. Most con trollers u se bit 7 of th e Head Nu m ber field to m ark a sector as bad d u rin g a low-level form at or su rface an alysis. Th is con ven tion is n ot absolu te, h owever. Som e con trollers u se oth er m eth od s to m ark a bad sector, bu t u su ally th e m ark in volves on e of th e ID field s. Th e W RITE TURN-ON GAP follows th e ID field ’s CRC bytes an d p rovid es a p ad to en su re a p rop er record in g of th e u ser d ata area th at follows, as well as to allow fu ll recovery of th e ID CRC. Th e u ser DATA field con sists of all 512 bytes of d ata stored in th e sector. Th is field is followed by a CRC field to verify th e d ata. Alth ou gh m an y con trollers u se two bytes of CRC h ere, th e con troller m ay im p lem en t a lon ger Error Correction Cod e (ECC) th at req u ires m ore th an two CRC bytes to store. Th e ECC d ata stored h ere p rovid es th e p ossibility of correctin g errors in th e DATA field as well as d etectin g th em . Th e correction / d etection cap abilities d ep en d on th e ECC cod e th e d rive u ses an d on its im p lem en tation by th e con troller. Th e W RITE TURN-OFF GAP is a p ad th at en ables th e ECC (CRC) bytes to be fu lly recovered . Th e INTER-RECORD GAP p rovid es a m ean s to accom m od ate varian ces in d rive sp in d le sp eed s. A track m ay h ave been form atted wh ile th e d isk was ru n n in g sligh tly slower th an n orm al an d th en written to wh ile th e d isk was ru n n in g sligh tly faster th an n orm al. In su ch cases, th is gap p reven ts th e accid en tal overwritin g of an y in form ation in th e n ext sector. Th e actu al size of th is p ad d in g varies, d ep en d in g on th e sp eed of th e DATA d isk’s rotation wh en th e track was form atted an d each tim e th e DATA field is u p d ated . Th e PRE-INDEX GAP allows for sp eed toleran ce over th e en tire track. Th is gap varies in size, d ep en d in g on th e varian ces in d isk-rotation sp eed an d write-freq u en cy toleran ce at th e tim e of form attin g. Th is sector p refix in form ation is extrem ely im p ortan t, becau se it con tain s th e n u m berin g in form ation th at d efin es th e cylin d er, h ead , an d sector. So th is in form ation —excep t th e

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DATA field , DATA CRC bytes, an d W RITE TURN-OFF GAP—is written on ly d u rin g a lowlevel form at. Disk Form at t ing. Th ere are two form attin g p roced u res req u ired before you can write u ser d ata to a d isk: ■ Ph ysical, or low-level form attin g ■ Logical, or high-level form attin g W h en you form at a flop p y d isk, th e W in d ows 9x Exp lorer or th e DOS FORMAT com m an d p erform s both kin d s of form ats sim u ltan eou sly. A h ard d isk, h owever, req u ires two sep arate form attin g op eration s. Moreover, a h ard d isk req u ires a th ird step , between th e two form attin g p roced u res, to write th e p artition in g in form ation to th e d isk. Partitioning is req u ired becau se a h ard d isk is d esign ed to be u sed with m ore th an on e op eratin g system . It is p ossible to u se m u ltip le op eratin g system s on on e h ard d rive by sep aratin g th e p h ysical form attin g in to a p roced u re th at is always th e sam e, regard less of th e op eratin g system u sed an d th e h igh -level form at (wh ich is d ifferen t for each op eratin g system ). Partition in g en ables a sin gle h ard d isk d rive to ru n m ore th an on e typ e of op eratin g system or it can en able a sin gle op eratin g system to u se th e d isk as several volu m es or logical d rives. A volum e or logical drive is an y section of th e d isk to wh ich th e op eratin g system assign s a d rive letter or n am e. Con seq u en tly, p rep arin g a h ard d isk d rive for d ata storage in volves th ree step s: 1. Low-Level Form attin g (LLF) 2. Partition in g 3. High -Level Form attin g (HLF) Lo w -Le v e l Fo rm a t t i n g . Du rin g a low-level form at, th e form attin g p rogram d ivid es th e d isk’s tracks in to a sp ecific n u m ber of sectors, creatin g th e in tersector an d in tertrack gap s an d record in g th e sector h ead er an d trailer in form ation . Th e p rogram also fills each sector’s d ata area with a d u m m y byte valu e or a p attern of test valu es. For flop p y d isks, th e n u m ber of sectors record ed on each track d ep en d s on th e typ e of d isk an d d rive. For h ard d isks, th e n u m ber of sectors p er track d ep en d s on th e d rive an d th e con troller in terface. Origin ally, PC h ard d isk d rives u sed a sep arate con troller th at took th e form of an exp an sion card or was in tegrated in to th e m oth erboard . Becau se th e con troller cou ld be u sed with variou s d isk d rives an d m ay even h ave been m ad e by a d ifferen t m an u factu rer, th ere h ad to be som e u n iform ity in th e com m u n ication s between th e con troller an d th e d rive. For th is reason , th e n u m ber of sectors written to a track ten d ed to be relatively con sisten t. Th e origin al ST-506/ 412 MFM con trollers always p laced 17 sectors p er track on a d isk, alth ou gh ST-506/ 412 con trollers with RLL en cod in g in creased th e n u m ber of sectors to 25 or 26 p er track an d ESDI d rives h ad 32 or m ore sectors p er track. Th e IDE an d SCSI d rives fou n d in PCs tod ay can h ave an ywh ere from 17 to 100 or m ore sectors p er track

Hard Disk Drives

becau se th ese d rives h ave th e con troller in tegrated in to th e d rive u n it. Th is is wh at In tegrated Drive Electron ics (IDE) m ean s. A SCSI d rive is basically th e sam e as an IDE, excep t for th e ad d ition of a SCSI Bu s Ad ap ter circu it. Becau se th e d rive an d th e con troller are a m atch ed set, th ere is n o n eed for m an u factu rers to m ain tain an y u n iform ity in th e com m u n ication s between th em , an d th ey can u se an y n u m ber of sectors p er track th ey wan t. Virtu ally all IDE an d SCSI d rives u se a tech n iq u e called Zoned Recording, wh ich writes a variable n u m ber of sectors p er track. Th e ou term ost tracks h old m ore sectors th an th e in n er tracks d o becau se th ey are lon ger. Becau se of lim itation s in th e PC BIOS, th ese d rives still h ave to beh ave as th ou gh th ey h ave a fixed n u m ber of sectors p er track. Th is situ ation is h an d led by tran slation algorith m s th at are im p lem en ted in th e con troller. On e way to in crease th e cap acity of a h ard d rive d u rin g th e low-level form at is to create m ore sectors on th e d isks’ ou ter cylin d ers th an on th e in n er on es. Becau se th ey h ave a larger circu m feren ce, th e ou ter cylin d ers can h old m ore d ata. Drives with ou t Zon ed Bit Record in g store th e sam e am ou n t of d ata on every cylin d er, even th ou gh th e tracks of th e ou ter cylin d ers m ay be twice as lon g as th ose of th e in n er cylin d ers. Th e resu lt is wasted storage cap acity, becau se th e d isk m ed ia m u st be cap able of storin g d ata reliably at th e sam e d en sity as on th e in n er cylin d ers. W h en th e n u m ber of sectors p er track is fixed , as in old er con trollers, th e d rive cap acity is lim ited by th e d en sity of th e in n erm ost (sh ortest) track. Drives th at u se Zon ed Bit Record in g sp lit th e cylin d ers in to grou p s called zones, with each su ccessive zon e h avin g m ore sectors p er track as you m ove ou tward s from th e cen ter of th e d isk. All th e cylin d ers in a p articu lar zon e h ave th e sam e n u m ber of sectors p er track. Th e n u m ber of zon es varies with sp ecific d rives, bu t m ost d rives h ave 10 or m ore zon es. An oth er effect of Zon ed Bit Record in g is th at tran sfer sp eed s vary d ep en d in g on wh at zon e th e h ead s are in . Th e rotation al sp eed of th e d isk is always th e sam e, bu t becau se th ere are m ore sectors in th e ou ter zon es, th e tran sfer rate is h igh er th ere. As an exam p le, see Table 12.6, wh ich sh ows th e zon es d efin ed for on e p articu lar 3.8G Qu an tu m d rive, th e sectors p er track for each zon e, an d its d ata tran sfer rate. Table 12.6

Zoned Bit Recording Inform at ion for t he Quant um Fireball 3.8G

Hard Disk Drive Zone

Tracks in Zone

Sect ors Per Track

Dat a Transfer Rat e ( M bit / s)

0

454

232

92.9

1

454

229

91.7

2

454

225

90.4

3

454

225

89.2

4

454

214

85.8 (continues)

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Chapter 12—M agnetic Storage

Table 12.6

Zoned Bit Recording Inform at ion for t he Quant um Fireball 3.8G

Hard Disk Drive Cont inued Zone

Tracks in Zone

Sect ors Per Track

Dat a Transfer Rat e ( M bit / s)

5

454

205

82.1

6

454

195

77.9

7

454

185

74.4

8

454

180

71.4

9

454

170

68.2

10

454

162

65.2

11

454

153

61.7

12

454

142

57.4

13

454

135

53.7

14

454

122

49.5

Th is d rive h as a total of 6,810 tracks on each p latter su rface an d , as you can see, th e tracks are d ivid ed in to 15 zon es of 454 tracks each . It is n ot essen tial for all th e zon es to be th e sam e size; th is is sim p ly h ow th is d rive is arran ged . Zon e 0 con sists of th e ou term ost 454 tracks, wh ich are th e lon gest an d con tain th e m ost sectors: 232. Each track in th is zon e can th erefore p rovid e 118,784 bytes or 116K of u ser d ata storage, alth ou gh th e 122 sector tracks in zon e 14 can h old on ly 62,464 bytes, or 61K. Th u s, with Zon ed Bit Record in g, each p latter su rface in th is d isk d rive con tain s 1,259,396 sectors, for a storage cap acity of 644,810,752 bytes or 614.94M. W ith ou t Zon ed Bit Record in g, th e n u m ber of sectors p er track wou ld be lim ited to 122 over th e en tire su rface of each p latter, for a total of 830,820 sectors, storin g 425,379,840 bytes or 405.67M. Zon ed Bit Record in g, th erefore, p rovid es a 51.59% in crease in th e storage cap acity of th is p articu lar d rive. Notice also th e d ifferen ce in th e d ata tran sfer rates for each of th e zon es. Th e tracks in th e ou term ost zon e (0) yield a tran sfer rate of 92.9 Mbit/ sec, wh ich is 87.67% h igh er th an th e 49.5 Mbit/ sec of th e in n erm ost zon e (14). Th is is on e reason wh y you m ay n otice h u ge d iscrep an cies in th e resu lts p rod u ced by d isk d rive ben ch m ark p rogram s. A test th at read s or writes files on th e ou ter tracks of th e d isk n atu rally yield s far better resu lts th an on e con d u cted on th e in n er tracks. It m ay ap p ear as th ou gh you r d rive is ru n n in g slower, wh en th e p roblem is actu ally th at th e test resu lts you are com p arin g resu lt from d isk activity on d ifferen t zon es. Th e d rives with sep arate con trollers u sed in th e p ast cou ld n ot h an d le Zon ed Bit Record in g becau se th ere was n o stan d ard way to com m u n icate in form ation abou t th e zon es from th e d rive to th e con troller. W ith SCSI an d IDE d isks, h owever, it is p ossible to form at in d ivid u al tracks with d ifferen t n u m bers of sectors, d u e to th e fact th at th ese d rives h ave th e d isk con troller bu ilt in . Th e bu ilt-in con trollers on th ese d rives are fu lly aware of th e zon in g algorith m , an d can tran slate th e p h ysical Cylin d er, Head , an d Sector n u m bers to logical Cylin d er, Head , an d Sector n u m bers so th e d rive ap p ears to h ave th e sam e n u m ber of sectors on each track. Becau se th e

Hard Disk Drives

PC BIOS is d esign ed to h an d le on ly a sin gle n u m ber of sectors p er track th rou gh ou t th e en tire d rive, a zon ed d rive m u st ru n by u sin g a sector tran slation sch em e. Th e u se of Zon ed Bit Record in g en ables d rive m an u factu rers to in crease th e cap acity of th eir h ard d rives by between 20% an d 50% com p ared with a fixed -sector-p er-track arran gem en t. Virtu ally all IDE an d SCSI d rives tod ay u se Zon ed Bit Record in g. P a rt i t i o n i n g . Creatin g a p artition on a h ard d isk d rive en ables it to su p p ort sep arate file system s, each in its own p artition . Each file system can th en u se its own m eth od to allocate file sp ace in logical u n its called clusters or allocation units. Every h ard d isk d rive m u st h ave at least on e p artition on it an d can h ave u p to fou r p artition s, each of wh ich can su p p ort th e sam e or d ifferen t typ e file system s. Th ere are th ree com m on file system s u sed by PC op eratin g system s tod ay: ■ FAT (File Allocation Table). Th e stan d ard file system su p p orted by DOS, W in d ows 9x, an d W in d ows NT. FAT p artition s su p p ort file n am es of 11 ch aracters m axim u m (8+3 ch aracter exten sion ) u n d er DOS, an d 255 ch aracters u n d er W in d ows 9x or W in d ows NT 4.0 (or later). Th e stan d ard FAT file system u ses 12- or 16-bit n u m bers to id en tify clu sters, resu ltin g in a m axim u m volu m e size of 2G. You can create on ly two p h ysical FAT p artition s on a h ard d isk d rive, called p rim ary an d exten d ed , bu t you can su bd ivid e th e exten d ed p artition in to as m an y as 25 logical volu m es. ■ FAT32 (File Allocation Table, 32-bit). An op tion al file system su p p orted by W in d ows 95 OSR2 (OEM Service Release 2), W in d ows 98, an d W in d ows NT 5.0. FAT32 u ses 32-bit n u m bers to id en tify clu sters, resu ltin g in a m axim u m sin gle volu m e size of 2T or 2,048G in size. ■ NTFS (W indows NT File System ). Th e n ative file system for W in d ows NT th at su p p orts file n am es u p to 256 ch aracters lon g an d p artition s u p to (a th eoretical) 16 exabytes (1 exabyte = 2 64 bytes = 17,179,869,184 terabytes). NTFS also p rovid es exten d ed attribu tes an d file system secu rity featu res th at d o n ot exist in th e FAT file system . Of th ese th ree file system s, th e FAT file system still is by far th e m ost p op u lar an d is accessible by n early every op eratin g system , wh ich m akes it th e m ost com p atible as well. FAT32 an d NTFS p rovid e ad d ition al featu res bu t are n ot u n iversally accessible by oth er op eratin g system s. ◊◊ See “ FAT Disk Structures,” p. 1065 and “ FAT32,” p. 1082

H i g h -Le v e l Fo rm a t t i n g . Du rin g th e h igh -level form at, th e op eratin g system (su ch as W in d ows 9x, W in d ows NT, or DOS) writes th e stru ctu res n ecessary for m an agin g files an d d ata on th e d isk. FAT p artition s h ave a Volu m e Boot Sector (VBS), two cop ies of a file allocation table (FAT), an d a root d irectory on each form atted logical d rive. Th ese d ata stru ctu res en able th e op eratin g system to m an age th e sp ace on th e d isk, keep track of files, an d even m an age d efective areas so th ey d o n ot cau se p roblem s.

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High -level form attin g is n ot really a p h ysical form attin g of th e d rive, bu t rath er th e creation of a table of con ten ts for th e d isk. In low-level form attin g, wh ich is th e real p h ysical form attin g p rocess, tracks an d sectors are written on th e d isk. As m en tion ed , th e DOS FORMAT com m an d can p erform both low-level an d h igh -level form at op eration s on a flop p y d isk, bu t it p erform s on ly th e h igh -level form at for a h ard d isk. Low-level form ats of IDE an d SCSI h ard d isk d rives are p erform ed by th e m an u factu rer, an d sh ou ld alm ost n ever be p erform ed by th e en d u ser. Basic Hard Disk Drive Com ponent s Man y typ es of h ard d isk d rives are on th e m arket, bu t n early all of th em sh are th e sam e basic p h ysical com p on en ts. Th ere m ay be som e d ifferen ces in th e im p lem en tation of th ese com p on en ts (an d in th e q u ality of th e m aterials u sed to m ake th em ), bu t th e op eration al ch aracteristics of m ost d rives are sim ilar. Th e basic com p on en ts of a typ ical h ard d isk d rive (see Figu re 12.5) are as follows: ■ Disk p latters

■ Logic board

■ Read / write h ead s

■ Cables an d con n ectors

■ Head actu ator m ech an ism

■ Con figu ration item s (su ch as ju m p ers or switch es)

■ Sp in d le m otor Th e p latters, sp in d le m otor, h ead s, an d h ead actu ator m ech an ism s are u su ally con tain ed in a sealed ch am ber called th e Head Disk Assem bly (HDA). Th e HDA is u su ally treated as a sin gle com p on en t; it is rarely op en ed . Oth er p arts extern al to th e d rive’s HDA—su ch as th e logic board s, bezel, an d oth er con figu ration or m ou n tin g h ard ware—can be d isassem bled from th e d rive. Hard Disk Plat t ers ( Disks) . A typ ical h ard d isk d rive h as on e or m ore p latters, or disks. Hard d isks for PC system s h ave been available in a n u m ber of form factors over th e years. Norm ally, th e p h ysical size of a d rive is exp ressed as th e size of th e p latters. Followin g are th e p latter sizes th at h ave been associated with PC h ard d isk d rives: ■ 5 1/ 4-in ch (actu ally 130m m , or 5.12 in ch es) ■ 3 1/ 2-in ch (actu ally 95m m , or 3.74 in ch es) ■ 2 1/ 2-in ch ■ 1.8-in ch Larger h ard d isk d rives th at h ave 8-in ch , 14-in ch , or even larger p latters are available, bu t th ese d rives are n ot u sed with PC system s. Cu rren tly, th e 3 1/ 2-in ch d rives are th e m ost p op u lar for d esktop an d som e p ortable system s, wh ile th e 2 1/ 2-in ch an d sm aller d rives are very p op u lar in p ortable or n otebook system s. Th ese little d rives are q u ite am azin g, with cu rren t cap acities typ ically in th e 1G–4G ran ge, an d cap acities of 20G exp ected by th e year 2000.

Hard Disk Drives

Top of case/ sealed chamber Breather holes (Breather filter is on underside)

Head arm Head actuator

Disk platters

Mounting chassis

Read/write head

Mounting holes

Drive controller PCB

Power connector from controller to drive motor Power connector

Connectors from controller to drive

Interface connector

FIG. 12.5 Hard d isk d rive com p on en ts. Most h ard d isk d rives h ave two or m ore p latters, alth ou gh som e of th e sm aller d rives h ave on ly on e. Th e n u m ber of p latters th at a d rive can h ave is lim ited by th e d rive’s vertical p h ysical size. Th e m axim u m n u m ber of p latters th at I h ave seen in an y 3 1/ 2in ch d rive is 11. Platters h ave trad ition ally been m ad e from an alu m in u m alloy th at p rovid es both stren gth an d ligh t weigh t. However, m an u factu rers’ d esire for h igh er an d h igh er d en sities an d sm aller d rives h as led to th e u se of p latters m ad e of glass (or, m ore tech n ically, a glass-ceram ic com p osite). On e su ch m aterial, p rod u ced by th e Dow Corn in g Corp oration , is called Mem Cor. Mem Cor is com p osed of glass with ceram ic im p lan ts, en ablin g it to resist crackin g better th an p u re glass. Glass p latters offer greater rigid ity th an m etal (becau se m etal can be ben t an d glass can n ot) an d can th erefore be m ach in ed to on e-h alf

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th e th ickn ess of con ven tion al alu m in u m d isks—som etim es less. Glass p latters are also m u ch m ore th erm ally stable th an alu m in u m p latters, wh ich m ean s th at th ey d o n ot exp an d or con tract very m u ch with ch an ges in tem p eratu re. Several h ard d isk d rives m ad e by com p an ies su ch as Seagate, Tosh iba, Areal Tech n ology, Maxtor, an d HewlettPackard cu rren tly u se glass or glass-ceram ic p latters. For m ost m an u factu rers, glass d isks will p robably rep lace th e stan d ard alu m in u m su bstrate over th e n ext few years, esp ecially in h igh -p erform an ce 2 1/ 2- an d 3 1/ 2-in ch d rives. Recording M edia. No m atter wh at su bstrate is u sed , th e p latters are covered with a th in layer of a m agn etically reten tive su bstan ce, called th e m ed iu m , on wh ich m agn etic in form ation is stored . Two p op u lar typ es of m agn etic m ed ia are u sed on h ard d isk p latters: ■ Oxid e m ed ia ■ Th in -film m ed ia Th e oxide m edia is m ad e of variou s com p ou n d s, con tain in g iron oxid e as th e active in gred ien t. Th e m agn etic layer is created on th e d isk by coatin g th e alu m in u m p latter with a syru p con tain in g iron -oxid e p articles. Th is syru p is sp read across th e d isk by sp in n in g th e p latters at h igh sp eed ; cen trifu gal force cau ses th e m aterial to flow from th e cen ter of th e p latter to th e ou tsid e, creatin g an even coatin g of th e m aterial on th e p latter. Th e su rface is th en cu red an d p olish ed . Fin ally, a layer of m aterial th at p rotects an d lu bricates th e su rface is ad d ed an d bu rn ish ed sm ooth . Th e oxid e coatin g is n orm ally abou t 30 m illion th s of an in ch th ick. If you cou ld p eer in to a d rive with oxid e-coated p latters, you wou ld see th at th e p latters are brown ish or am ber. As d rive d en sity in creases, th e m agn etic m ed ia n eed s to be th in n er an d m ore p erfectly form ed . Th e cap abilities of oxid e coatin gs h ave been exceed ed by m ost h igh er-cap acity d rives. Becau se th e oxid e m ed ia is very soft, d isks th at u se it are su bject to h ead -crash d am age if th e d rive is jolted d u rin g op eration . Most old er d rives, esp ecially th ose sold as low-en d m od els, u se oxid e m ed ia on th e d rive p latters. Oxid e m ed ia, wh ich h ave been u sed sin ce 1955, rem ain ed p op u lar becau se of th eir relatively low cost an d ease of ap p lication . Tod ay, h owever, very few d rives u se oxid e m ed ia. Th e thin-film m edia is th in n er, h ard er, an d m ore p erfectly form ed th an oxid e m ed ia. Th in film was d evelop ed as a h igh -p erform an ce m ed iu m th at en abled a n ew gen eration of d rives to h ave lower h ead floatin g h eigh ts, wh ich in tu rn m ad e in creases in d rive d en sity p ossible. Origin ally, th in -film m ed ia were u sed on ly in h igh er-cap acity or h igh er-q u ality d rive system s, bu t tod ay, virtu ally all d rives u se th in -film m ed ia. Th e th in -film m ed ia is ap tly n am ed . Th e coatin g is m u ch th in n er th an can be ach ieved by th e oxid e-coatin g m eth od . Th in -film m ed ia are also kn own as plated, or sputtered, m ed ia becau se of th e variou s p rocesses u sed to d ep osit th e th in film on th e p latters. Thin-film plated m edia are m an u factu red by d ep ositin g th e m agn etic m ed ia on th e d isk with an electrop latin g m ech an ism , in m u ch th e sam e way th at ch rom e p latin g is d ep osited on th e bu m p er of a car. Th e alu m in u m p latter is im m ersed in a series of ch em ical

Hard Disk Drives

bath s th at coat th e p latter with several layers of m etallic film . Th e m agn etic m ed iu m layer itself is a cobalt alloy abou t 3 µ-in th ick. Thin-film sputtered m edia are created by first coatin g th e alu m in u m p latters with a layer of n ickel p h osp h oru s an d th en ap p lyin g th e cobalt-alloy m agn etic m aterial in a con tin u ou s vacu u m -d ep osition p rocess called sputtering. Th is p rocess d ep osits m agn etic layers as th in as 1 or 2 µ-in on th e d isk, in a fash ion sim ilar to th e way th at silicon wafers are coated with m etallic film s in th e sem icon d u ctor in d u stry. Th e sam e sp u tterin g tech n iq u e is th en u sed again to lay d own an extrem ely h ard , 1 µ-in p rotective carbon coatin g. Th e n eed for a n ear-p erfect vacu u m m akes sp u tterin g th e m ost exp en sive of th e p rocesses d escribed h ere. Th e su rface of a sp u ttered p latter con tain s m agn etic layers as th in as 1 µ-in . Becau se th is su rface also is very sm ooth , th e h ead can float closer to th e d isk su rface th an was p ossible p reviou sly. Floatin g h eigh ts as sm all as 3 µ-in above th e su rface are p ossible. W h en th e h ead is closer to th e p latter, th e d en sity of th e m agn etic flu x tran sition s can be in creased to p rovid e greater storage cap acity. Ad d ition ally, th e in creased in ten sity of th e m agn etic field d u rin g a closer-p roxim ity read p rovid es th e h igh er sign al am p litu d es n eed ed for good sign al-to-n oise p erform an ce. Both th e sp u tterin g an d p latin g p rocesses resu lt in a very th in , very h ard film of m agn etic m ed ia on th e p latters. Becau se th e th in -film m ed ia is so h ard , it h as a better ch an ce of su rvivin g con tact with th e h ead s at h igh sp eed . In fact, m od ern th in -film m ed ia are virtu ally u n crash able. If you cou ld op en a d rive to p eek at th e p latters, you wou ld see th at p latters coated with th e th in -film m ed ia look like th e silver su rfaces of m irrors. Th e sp u tterin g p rocess resu lts in th e m ost p erfect, th in n est, an d h ard est d isk su rface th at can be p rod u ced com m ercially, wh ich is wh y it h as largely rep laced p latin g as th e p referred m eth od of creatin g th in -film m ed ia. Havin g a th in -film m ed ia su rface on a d rive resu lts in in creased storage cap acity in a sm aller area with fewer h ead crash es—an d in a d rive th at typ ically will p rovid e m an y years of trou ble-free u se. Read/ W rit e Heads. A h ard d isk d rive u su ally h as on e read / write h ead for each p latter su rface (m ean in g th at each p latter h as two sets of read / write h ead s—on e for th e top sid e an d on e for th e bottom sid e of th e p latter). Th ese h ead s are con n ected , or ganged, on a sin gle m ovem en t m ech an ism . Th e h ead s, th erefore, m ove across th e p latters in u n ison . Mech an ically, read / write h ead s are sim p le. Each h ead is on an actu ator arm th at is sp rin g-load ed to force th e h ead in to con tact with a p latter. Few p eop le realize th at each p latter actu ally is “sq u eezed ” by th e h ead s above an d below it. If you cou ld op en a d rive safely an d lift th e top h ead with you r fin ger, th e h ead wou ld sn ap back d own in to th e p latter wh en you released it. If you cou ld p u ll d own on on e of th e h ead s below a p latter, th e sp rin g ten sion wou ld cau se it to sn ap back u p in to th e p latter wh en you released it. Figu re 12.6 sh ows a typ ical h ard d isk h ead -actu ator assem bly from a voice coil d rive.

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Actuator shaft

Voice coil

Read/write heads Magnet

Magnet housing

FIG. 12.6 Read / write h ead s an d rotary voice coil actu ator assem bly. W h en th e d rive is at rest, th e h ead s are forced in to d irect con tact with th e p latters by sp rin g ten sion , bu t wh en th e d rive is sp in n in g at fu ll sp eed , air p ressu re d evelop s below th e h ead s an d lifts th em off th e su rface of th e p latter. On a d rive sp in n in g at fu ll sp eed , th e d istan ce between th e h ead s an d th e p latter can be an ywh ere from 3 to 20 µ-in or m ore. In th e early 1960s, h ard d isk d rive record in g h ead s op erated at floatin g h eigh ts as large as 200–300 µ-in ; tod ay’s d rive h ead s are d esign ed to float as low as 3–5 µ-in above th e su rface of th e d isk. To su p p ort h igh er d en sities in fu tu re d rives, th e p h ysical sep aration between th e h ead an d d isk is exp ected to be as little as 0.5 µ-in by th e en d of th e cen tu ry.

Caut ion The small size of the gap between the platters and the heads is why you should never open the disk drive’s HDA except in a clean-room environment. Any particle of dust or dirt that gets into this mechanism could cause the heads to read improperly, or possibly even to strike the platters while the drive is running at full speed. The latter event could scratch the platter or the head.

To en su re th e clean lin ess of th e in terior of th e d rive, th e HDA is assem bled in a class-100 or better clean room . Th is sp ecification m ean s th at a cu bic foot of air can n ot con tain m ore th an 100 p articles th at m easu re u p to 0.5 m icron s (19.7 µ-in ). A sin gle p erson breath in g wh ile stan d in g m otion less sp ews ou t 500 su ch p articles in a sin gle m in u te! Th ese room s con tain sp ecial air-filtration system s th at con tin u ou sly evacu ate an d refresh th e air. A d rive’s HDA sh ou ld n ot be op en ed u n less it is in sid e su ch a room . Alth ou gh m ain tain in g a clean -room en viron m en t m ay seem to be exp en sive, m an y com p an ies m an u factu re tabletop or ben ch -size clean room s th at sell for on ly a few th ou san d d ollars. Som e of th ese d evices op erate like a glove box; th e op erator first in serts th e d rive an d an y tools req u ired , an d th en closes th e box an d tu rn s on th e filtration system . In sid e

Hard Disk Drives

th e box, a clean -room en viron m en t is m ain tain ed , an d a tech n ician can u se th e bu ilt-in gloves to work on th e d rive. In oth er clean -room variation s, th e op erator stan d s at a ben ch wh ere a forced -air cu rtain m ain tain s a clean en viron m en t on th e ben ch top . Th e tech n ician can walk in an d ou t of th e clean -room field by walkin g th rou gh th e air cu rtain . Th is air cu rtain is m u ch like th e cu rtain of air u sed in som e stores an d wareh ou ses to p reven t h eat from escap in g in th e win ter wh ile leavin g a p assage wid e op en . Becau se th e clean en viron m en t is exp en sive to p rod u ce, few com p an ies, excep t th ose th at m an u factu re th e d rives, are p rop erly eq u ip p ed to service h ard d isk d rives. Read/ W rit e Head Designs. As d isk d rive tech n ology h as evolved , so h as th e d esign of th e read / write h ead . Th e earliest h ead s were sim p le iron cores with coil win d in gs (electrom agn ets). By tod ay’s stan d ard s, th e origin al h ead d esign s were en orm ou s in p h ysical size an d op erated at very low record in g d en sities. Over th e years, h ead d esign s h ave evolved from th e first sim p le Ferrite Core d esign s in to th e several typ es an d tech n ologies available tod ay. Th is section d iscu sses th e d ifferen t typ es of h ead s fou n d in PC h ard d isk d rives, in clu d in g th e ap p lication s an d relative stren gth s an d weakn esses of each . Fou r typ es of h ead s h ave been u sed in h ard d isk d rives over th e years: ■ Ferrite

■ Th in Film (TF)

■ Metal-In -Gap (MIG)

■ Magn eto-Resistive (MR)

Fe rri t e . Ferrite heads, th e trad ition al typ e of m agn etic-h ead d esign , evolved from th e origin al IBM 30-30 “W in ch ester” d rive. Th ese h ead s h ave an iron -oxid e core wrap p ed with electrom agn etic coils. Th e d rive p rod u ces a m agn etic field by en ergizin g th e coils or by p assin g a m agn etic field n ear th em . Th is gives th e h ead s fu ll read an d write cap ability. Ferrite h ead s are larger an d h eavier th an th in -film h ead s an d th erefore req u ire a larger floatin g h eigh t to p reven t con tact with th e d isk wh ile it is sp in n in g. Man u factu rers h ave m ad e m an y refin em en ts to th e origin al (m on olith ic) ferrite h ead d esign . On e typ e of ferrite h ead called a com posite ferrite head h as a sm aller ferrite core bon d ed with glass in a ceram ic h ou sin g. Th is d esign p erm its a sm aller h ead gap , wh ich allows h igh er track d en sities. Th ese h ead s are less su scep tible to stray m agn etic field s th an th e old er m on olith ic d esign h ead s. Du rin g th e 1980s, com p osite ferrite h ead s were p op u lar in m an y low-en d d rives, su ch as th e Seagate ST-225. As d en sity d em an d s grew, th e com p etin g MIG an d th in -film h ead d esign s cam e to be u sed in p lace of ferrite h ead s, wh ich are virtu ally obsolete tod ay. Ferrite h ead s can n ot write to th e h igh er coercivity m ed ia n eed ed for h igh -d en sity d isk d esign s an d h ave p oor freq u en cy resp on se with h igh er n oise levels. Th e m ain ad van tage of ferrite h ead s is th at th ey are th e ch eap est typ e available. Me t a l -In -Ga p . Metal-In-Gap (MIG) heads are a sp ecially en h an ced version of th e com p osite ferrite d esign . In MIG h ead s, a m etal su bstan ce is ap p lied to th e h ead ’s record in g gap . Two version s of MIG h ead s are available: sin gle-sid ed an d d ou ble-sid ed . Sin gle-sid ed

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MIG h ead s are d esign ed with a layer of m agn etic alloy p laced alon g th e trailin g ed ge of th e gap . Dou ble-sid ed MIG d esign s ap p ly th e layer to both sid es of th e gap . Th e m etal alloy is ap p lied th rou gh a vacu u m -d ep osition p rocess called sp u tterin g, wh ich was d iscu ssed in th e p reviou s section on record in g m ed ia. Th is m agn etic alloy h as twice th e m agn etization cap ability of raw ferrite an d en ables th e h ead to write to th e h igh er-coercivity th in -film m ed ia n eed ed at th e h igh er d en sities. MIG h ead s also p rod u ce a sh arp er grad ien t in th e m agn etic field for a better-d efin ed m agn etic p u lse. Dou ble-sid ed MIG h ead s offer even h igh er coercivity cap ability th an th e sin gle-sid ed d esign s d o. Becau se of th ese in creases in cap abilities th rou gh im p roved d esign s, MIG h ead s were for a tim e th e m ost p op u lar h ead d esign , an d were u sed in all bu t very h igh -cap acity d rives. Du e to m arket p ressu res d em an d in g h igh er an d h igh er d en sities, h owever, MIG h ead s h ave been largely d isp laced in favor of th in -film h ead s. Th i n Fi l m . Thin-film (TF) heads are m an u factu red in m u ch th e sam e m an n er as a sem icon d u ctor ch ip —th at is, th rou gh a p h otolith ograp h ic p rocess. Th is p rocess creates m an y th ou san d s of h ead s on a sin gle circu lar wafer, an d p rod u ces a very sm all, h igh -q u ality p rod u ct. TF h ead s h ave an extrem ely n arrow an d con trolled h ead gap th at is created by sp u tterin g a h ard alu m in u m m aterial. Becau se th is m aterial com p letely en closes th e gap , th e area is very well p rotected , m in im izin g th e ch an ce of d am age from con tact with th e sp in n in g d isk. Th e core is a com bin ation of iron an d n ickel alloy th at h as two to fou r tim es m ore m agn etic p ower th an a ferrite h ead core. TF h ead s p rod u ce a sh arp ly d efin ed m agn etic p u lse th at en ables th em to write at extrem ely h igh d en sities. Becau se th ey d o n ot h ave a con ven tion al coil, TF h ead s are m ore im m u n e to variation s in coil im p ed an ce. Th ese sm all, ligh tweigh t h ead s can float at a m u ch lower h eigh t th an th e ferrite an d MIG h ead s; in som e d esign s, th e floatin g h eigh t is 2 µ-in or less. Becau se th e red u ced h eigh t en ables th e h ead s to p ick u p an d tran sm it a m u ch stron ger sign al from th e p latters, th e sign al-to-n oise ratio in creases, im p rovin g accu racy. At th e h igh track an d lin ear d en sities of som e d rives, a stan d ard ferrite h ead wou ld n ot be able to p ick ou t th e d ata sign al from th e backgrou n d n oise. An oth er ad van tage of TF h ead s is th at th eir sm all size en ables th e p latters to be stacked closer togeth er, m akin g it p ossible to fit m ore p latters in to th e sam e sp ace. Un til th e p ast few years, TF h ead s were relatively exp en sive com p ared with old er tech n ologies, su ch as ferrite an d MIG. Better m an u factu rin g tech n iq u es an d th e n eed for h igh er d en sities, h owever, h ave d riven th e m arket to TF h ead s. Th e wid esp read u se of th ese h ead s h as also m ad e th em cost-com p etitive with , if n ot ch eap er th an , MIG h ead s. Man y of th e d rives in th e 100M to 1,000M ran ge m an u factu red tod ay u se TF h ead s, esp ecially in th e sm aller form factors. TF h ead s d isp laced MIG h ead s as th e m ost p op u lar h ead d esign , bu t th ey are n ow th em selves bein g d isp laced by n ewer tech n ologies, su ch as m agn eto-resistive h ead s.

Hard Disk Drives

Ma g n e t o -Re si st i v e . Magneto-Resistive (MR) heads are th e latest tech n ology. In ven ted an d p ion eered by IBM, MR h ead s cu rren tly offer th e h igh est p erform an ce available. Most 3 1/ 2-in ch d rives with cap acities in excess of 1G cu rren tly u se MR h ead s. As areal d en sities con tin u e to in crease, th e MR h ead even tu ally will becom e th e h ead of ch oice for n early all h ard d rives, d isp lacin g th e p op u lar MIG an d TF h ead d esign s. MR h ead s rely on th e fact th at th e resistan ce of a con d u ctor ch an ges sligh tly wh en an extern al m agn etic field is p resen t. Rath er th an p u t ou t a voltage by p assin g th rou gh a m agn etic-field flu x reversal, as a n orm al h ead wou ld , th e MR h ead sen ses th e flu x reversal an d ch an ges resistan ce. A sm all cu rren t flows th rou gh th e h ead s, an d th is sen se cu rren t m easu res th e ch an ge in resistan ce. Th is d esign p rovid es an ou tp u t th at is th ree or m ore tim es m ore p owerfu l th an a TF h ead d u rin g a read . In effect, MR h ead s are p owerread h ead s, actin g m ore like sen sors th an gen erators. MR h ead s are m ore costly an d com p lex to m an u factu re th an oth er typ es of h ead s, becau se several sp ecial featu res or step s m u st be ad d ed . Am on g th em are ■ Ad d ition al wires m u st be ru n to an d from th e h ead to carry th e sen se cu rren t. ■ Fou r to six m ore m askin g step s are req u ired . ■ Becau se MR h ead s are so sen sitive, th ey are very su scep tible to stray m agn etic field s an d m u st be sh ield ed . Becau se th e MR p rin cip le can on ly read d ata an d is n ot u sed for writin g, MR h ead s really are two h ead s in on e. Th e assem bly in clu d es a stan d ard in d u ctive TF h ead for writin g d ata, an d an MR h ead for read in g. Becau se two sep arate h ead s are bu ilt in to on e assem bly, each h ead can be op tim ized for its task. Ferrite, MIG, an d TF h ead s are kn own as single-gap heads becau se th e sam e gap is u sed for both read in g an d writin g, wh ile th e MR h ead u ses a sep arate gap for each op eration . Th e p roblem with sin gle-gap h ead s is th at th e gap len gth is always a com p rom ise between wh at is best for read in g an d wh at is best for writin g. Th e read fu n ction n eed s a th in gap for h igh er resolu tion ; th e write fu n ction n eed s a th icker gap for d eep er flu x p en etration to switch th e m ed iu m . In a d u al-gap MR h ead , th e read an d write gap s can be op tim ized for both fu n ction s in d ep en d en tly. Th e write (TF) gap writes a wid er track th an th e read (MR) gap read s. Th u s, th e read h ead is less likely to p ick u p stray m agn etic in form ation from ad jacen t tracks. Drives with MR h ead s req u ire better sh ield in g from stray m agn etic field s, wh ich can affect th ese h ead s m ore easily th an th ey d o th e oth er h ead d esign s. All in all, h owever, th e d rawback is m in or com p ared with th e ad van tages th at th e MR h ead s offer. Head Sliders. Th e term slider is u sed to d escribe th e bod y of m aterial th at su p p orts th e actu al d rive h ead itself. Th e slid er is wh at actu ally floats or slid es over th e su rface of th e d isk, carryin g th e h ead at th e correct d istan ce from th e m ed iu m for read in g an d writin g. Most slid ers resem ble a catam aran , with two ou tboard p od s th at float alon g th e su rface of th e d isk m ed ia an d a cen tral “ru d d er” p ortion th at actu ally carries th e h ead an d th e read / write gap .

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Th e tren d toward sm aller an d sm aller form factor d rives h as forced slid ers to becom e sm aller an d sm aller as well. Th e typ ical m in i-W in ch ester slid er d esign is abou t .160×.126×.034 in ch es in size. Most h ead m an u factu rers h ave n ow sh ifted to 50% sm aller n an oslid ers, wh ich h ave d im en sion s of abou t .08×.063×.017 in ch es. Th e n an oslid er is bein g u sed in both h igh -cap acity an d sm all-form -factor d rives. Th e n ext evolu tion in slid er d esign , called th e picoslider, is sm aller still: 70% sm aller th an th e origin al d esign . Picoslid ers are assem bled by u sin g flex in tercon n ect cable (FIC) an d ch ip on ceram ic (COC) tech n ology th at en ables th e p rocess to be com p letely au tom ated . Sm aller slid ers red u ce th e m ass carried at th e en d of th e h ead actu ator arm s, p rovid in g in creased acceleration an d d eceleration , lead in g to faster seek tim es. Th e sm aller slid ers also req u ire less area for a lan d in g zon e, th u s in creasin g th e u sable area of th e d isk p latters. Fu rth er, th e sm aller slid er con tact area red u ces th e sligh t wear on th e p latter su rface th at occu rs d u rin g n orm al startu p an d sp in d own of th e d rive p latters. Th e n ewer n an oslid er d esign s also h ave sp ecially m od ified su rface p attern s th at are d esign ed to m ain tain th e sam e floatin g h eigh t above th e d isk su rface, wh eth er th e slid er is p osition ed above th e in n er or ou ter cylin d ers. Con ven tion al slid ers in crease or d ecrease th eir floatin g h eigh t con sid erably, accord in g to th e velocity of th e d isk su rface travelin g ben eath th em . Above th e ou ter cylin d ers, th e velocity an d floatin g h eigh t are h igh er. Th is arran gem en t is u n d esirable in n ewer d rives th at u se Zon ed Bit Record in g, in wh ich th e bit d en sity is th e sam e on all th e cylin d ers. W h en th e bit d en sity is u n iform th rou gh ou t th e d rive, th e h ead floatin g h eigh t sh ou ld be relatively con stan t as well for m axim u m p erform an ce. Sp ecial textu red su rface p attern s an d m an u factu rin g tech n iq u es en able th e n an oslid ers to float at a m u ch m ore con sisten t h eigh t, m akin g th em id eal for Zon ed Bit Record in g d rives. Head Act uat or M echanism s. Possibly m ore im p ortan t th an th e h ead s th em selves is th e m ech an ical system th at m oves th em : th e head actuator. Th is m ech an ism m oves th e h ead s across th e d isk an d p osition s th em accu rately above th e d esired cylin d er. Th ere are m an y variation s on h ead actu ator m ech an ism s in u se, bu t all of th em fall in to on e of two basic categories: ■ Step p er m otor actu ators ■ Voice coil actu ators Th e u se of on e or th e oth er typ e of actu ator h as p rofou n d effects on a d rive’s p erform an ce an d reliability. Th e effects are n ot lim ited to sp eed ; th ey also in clu d e accu racy, sen sitivity to tem p eratu re, p osition , vibration , an d overall reliability. Th e h ead actu ator is th e sin gle m ost im p ortan t sp ecification in th e d rive, an d th e typ e of h ead actu ator m ech an ism in a d rive tells you a great d eal abou t th e d rive’s p erform an ce an d reliability ch aracteristics. Table 12.7 sh ows th e two typ es of h ard d isk d rive h ead actu ators an d th e affected p erform an ce ch aracteristics.

Hard Disk Drives

Table 12.7

Charact erist ics of St epper M ot or Versus Voice Coil Drives

Charact erist ic

St epper M ot or

Voice Coil

Relative access speed

Slow

Fast

Temperature sensitive

Yes (very)

No

Positionally sensitive

Yes

No

Automatic head parking

Not usually

Yes

Preventive maintenance

Periodic format

None required

Relative reliability

Poor

Excellent

Gen erally, a step p er m otor d rive h as a slower average access ratin g, is tem p eratu resen sitive d u rin g read an d write op eration s, is sen sitive to p h ysical orien tation d u rin g read an d write op eration s, d oes n ot au tom atically p ark its h ead s above a save zon e d u rin g p ower-d own , an d u su ally req u ires an n u al or bian n u al reform ats to realign th e sector d ata with th e sector h ead er in form ation d u e to m istrackin g. To p u t it blu n tly, a d rive eq u ip p ed with a step p er m otor actu ator is m u ch less reliable (by a large m argin ) th an a d rive eq u ip p ed with a voice coil actu ator. Flop p y d isk d rives p osition th eir h ead s by u sin g a step p er m otor actu ator. Th e accu racy of th e step p er m ech an ism is su ited to a flop p y d isk d rive, becau se th e track d en sities are u su ally n owh ere n ear th ose of a h ard d isk. Th e track d en sity of a 1.44M flop p y d isk is 135 tracks p er in ch , wh ile h ard d isk d rives h ave d en sities of over 5000 tracks p er in ch . Virtu ally all th e h ard d isk d rives bein g m an u factu red tod ay u se voice coil actu ators, becau se step p er m otors can n ot ach ieve th e d egree of accu racy n eed ed . St e p p e r Mo t o r Ac t u a t o rs. A stepper m otor is an electrical m otor th at can “step ,” or m ove from p osition to p osition , with m ech an ical d eten ts or click-stop p osition s. If you were to grip th e sp in d le of on e of th ese m otors an d sp in it by h an d , you wou ld h ear a clickin g or bu zzin g sou n d as th e m otor p assed each d eten t p osition with a soft click. Step p er m otors can n ot p osition th em selves between step p osition s; th ey can stop on ly at th e p red eterm in ed d eten t p osition s. Th e m otors are sm all (between 1 an d 3 in ch es) an d can be sq u are, cylin d rical, or flat. Step p er m otors are ou tsid e th e sealed HDA, alth ou gh th e sp in d le of th e m otor p en etrates th e HDA th rou gh a sealed h ole. Step p er m otor m ech an ism s are affected by a variety of p roblem s. Th e greatest p roblem is tem p eratu re. As th e d rive p latters h eat an d cool, th ey exp an d an d con tract, an d th e tracks on th e p latters m ove in relation to a p red eterm in ed track p osition . Th e step p er m ech an ism can n ot m ove in in crem en ts of less th an a sin gle track to correct for th ese tem p eratu re-in d u ced errors. Th e d rive p osition s th e h ead s to a p articu lar cylin d er accord in g to a p red eterm in ed n u m ber of step s from th e step p er m otor, with n o room for n u an ce. Vo i c e Co i l Ac t u a t o rs. Th e voice coil actuators u sed in virtu ally all h ard d isk d rives m ad e tod ay, u n like step p er m otor actu ators, u se a feed back sign al from th e d rive to accu rately d eterm in e th e h ead p osition s an d to ad ju st th em , if n ecessary. Th is arran gem en t p rovid es sign ifican tly greater p erform an ce, accu racy, an d reliability th an trad ition al step p er m otor actu ator d esign s.

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A voice coil actu ator works by p u re electrom agn etic force. Th e con stru ction of th e m ech an ism is sim ilar to th at of a typ ical au d io sp eaker, from wh ich th e term voice coil is d erived . An au d io sp eaker u ses a station ary m agn et su rrou n d ed by a voice coil, wh ich is con n ected to th e sp eaker’s p ap er con e. En ergizin g th e coil cau ses it to m ove relative to th e station ary m agn et, wh ich p rod u ces sou n d from th e con e. In a typ ical h ard d isk d rive’s voice coil system , th e electrom agn etic coil is attach ed to th e en d of th e h ead rack an d p laced n ear a station ary m agn et. Th ere is n o p h ysical con tact between th e coil an d th e m agn et; in stead , th e coil m oves by p u re m agn etic force. As th e electrom agn etic coils are en ergized , th ey attract or rep u lse th e station ary m agn et an d m ove th e h ead rack. System s like th ese are extrem ely q u ick an d efficien t, an d u su ally m u ch q u ieter th an system s d riven by step p er m otors. Un like a step p er m otor, a voice coil actu ator h as n o click-stop s, or d eten t p osition s; rath er, a sp ecial gu id an ce system stop s th e h ead rack above a p articu lar cylin d er. Becau se it h as n o d eten ts, th e voice coil actu ator can slid e th e h ead s in an d ou t sm ooth ly to an y p osition d esired . Voice coil actu ators u se a gu id an ce m ech an ism called a servo to tell th e actu ator wh ere th e h ead s are in relation to th e cylin d ers an d to p lace th e h ead s accu rately at th e d esired p osition s. Th is p osition in g system often is called a closed loop feedback m echanism . Th is system works by sen d in g th e in d ex (or servo) sign al to th e p osition in g electron ics, wh ich retu rn a feed back sign al th at is u sed to p osition th e h ead s accu rately. Th e system is also called servo-controlled, wh ich refers to th e in d ex or th e servo in form ation th at is u sed to d ictate or con trol h ead -p osition in g accu racy. A voice coil actu ator with servo con trol is n ot affected by tem p eratu re ch an ges, as a step p er m otor is. W h en tem p eratu re ch an ges cau se th e d isk p latters to exp an d or con tract, th e voice coil system com p en sates au tom atically becau se it n ever p osition s th e h ead s in p red eterm in ed track p osition s. Rath er, th e voice coil system search es for th e sp ecific track, gu id ed by th e p rewritten servo in form ation , an d th en p osition s th e h ead rack p recisely above th e d esired track, wh erever it h ap p en s to be. Becau se of th e con tin u ou s feed back of servo in form ation , th e h ead s ad ju st to th e cu rren t p osition of th e track at all tim es. For exam p le, as a d rive warm s u p an d th e p latters exp an d , th e servo in form ation en ables th e h ead s to “follow” th e track. As a resu lt, a voice coil actu ator is som etim es called a track following system . Th e two m ain typ es of voice-coil p osition er m ech an ism s are ■ Lin ear voice-coil actu ators ■ Rotary voice-coil actu ators Th e two typ es d iffer on ly in th e p h ysical arran gem en t of th e m agn ets an d coils. A linear actuator (see Figu re 12.7) m oves th e h ead s in an d ou t over th e p latters in a straigh t lin e. Th e coil m oves in an d ou t on a track su rrou n d ed by th e station ary m agn ets. Th e p rim ary ad van tage of th e lin ear d esign is th at it elim in ates th e h ead azim u th variation s th at occu r with rotary p osition in g system s. (Azim uth refers to th e an gu lar m easu rem en t of th e h ead p osition relative to th e tan gen t of a given cylin d er.) A lin ear actu ator d oes n ot rotate th e h ead as it m oves from on e cylin d er to an oth er, th u s elim in atin g th is p roblem .

Hard Disk Drives

Servo head

Head travel

Read write heads Magnets

Coils

FIG. 12.7 A lin ear voice coil actu ator. Alth ou gh th e lin ear actu ator seem s to be a good d esign , it h as on e fatal flaw: Th e d evices are m u ch too h eavy. As d rive p erform an ce h as in creased , th e d esire for ligh tweigh t actu ator m ech an ism s h as becom e very im p ortan t. Th e ligh ter th e m ech an ism , th e faster it can accelerate an d d ecelerate from on e cylin d er to an oth er. Becau se th ey are m u ch h eavier th an rotary actu ators, lin ear actu ators were p op u lar on ly for a sh ort tim e; th ey are virtu ally n on existen t in d rives m an u factu red tod ay. Rotary actuators (refer to Figu re 12.6) also u se station ary m agn ets an d a m ovable coil, bu t th e coil is attach ed to th e en d of an actu ator arm . As th e coil m oves relative to th e station ary m agn et, it swin gs th e h ead arm s in an d ou t over th e su rface of th e d isk. Th e p rim ary ad van tage of th is m ech an ism is its ligh t weigh t, wh ich m ean s th at th e h ead s can accelerate an d d ecelerate very q u ickly, resu ltin g in very fast average seek tim es. Becau se of th e lever effect on th e h ead arm , th e h ead s m ove faster th an th e actu ator, wh ich also h elp s to im p rove access tim es. Th e d isad van tage of a rotary system is th at as th e h ead s m ove from th e ou ter to th e in n er cylin d ers, th ey rotate sligh tly with resp ect to th e tan gen t of th e cylin d ers. Th is rotation resu lts in an azim u th error an d is on e reason wh y th e area of th e p latter in wh ich th e cylin d ers are located is som ewh at lim ited . By lim itin g th e total m otion of th e actu ator, th e azim u th error is con tain ed to with in reason able sp ecification s. Virtu ally all voice coil d rives tod ay u se rotary actu ator system s.

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Se rv o Me c h a n i sm s. Th ree servo m ech an ism d esign s h ave been u sed to con trol voice coil p osition ers over th e years: ■ W ed ge servo ■ Em bed d ed servo ■ Ded icated servo Th e th ree d esign s are sligh tly d ifferen t, bu t th ey accom p lish th e sam e basic task: Th ey en able th e h ead p osition er to ad ju st con tin u ou sly so it is p recisely p osition ed above a given cylin d er on th e d isk. Th e m ain d ifferen ce between th ese servo d esign s is wh ere th e gray cod e in form ation is actu ally written on th e d rive. All servo m ech an ism s rely on sp ecial in form ation th at is written to th e d isk wh en it is m an u factu red . Th is in form ation is u su ally in th e form of a sp ecial cod e called a gray cod e. A gray code is a sp ecial bin ary n otation al system in wh ich an y two ad jacen t n u m bers are rep resen ted by a cod e th at d iffers in on ly on e bit p lace or colu m n p osition . Th is system m akes it easy for th e h ead to read th e in form ation an d q u ickly d eterm in e its p recise p osition . At th e tim e of m an u factu re, a sp ecial m ach in e called a servowriter writes th e servo gray cod e on th e d isk. Th e servowriter is basically a jig th at m ech an ically m oves th e h ead s to a given referen ce p osition an d th en writes th e servo in form ation at th at p osition . Man y servowriters are th em selves gu id ed by a laser-beam referen ce th at calcu lates its own p osition by calcu latin g d istan ces in wavelen gth s of ligh t. Becau se th e servowriter m u st be cap able of m ovin g th e h ead s m ech an ically, th e p rocess req u ires eith er th at th e lid of th e d rive be rem oved or th at access be available th rou gh sp ecial access p orts in th e HDA. After th e servowritin g is com p lete, th ese p orts are u su ally covered with sealin g tap e. You often see th ese tap e-covered h oles on th e HDA, u su ally accom p an ied by warn in gs th at you will void th e warran ty if you rem ove th e tap e. Becau se servowritin g exp oses th e in terior of th e HDA, it req u ires a clean -room en viron m en t. A servowriter is an exp en sive p iece of m ach in ery, costin g u p to $50,000 or m ore, an d often m u st be cu stom -m ad e for a p articu lar m ake or m od el of d rive. Som e d rive-rep air com p an ies h ave servowriting capability, wh ich m ean s th at th ey can rewrite th e servo in form ation on a d rive if it becom es d am aged . If a servowriter is n ot available, a d rive with servo-cod e d am age m u st be sen t back to th e d rive m an u factu rer for th e servo in form ation to be rewritten . Fortu n ately, it is im p ossible to d am age th e servo in form ation th rou gh d isk read an d write p rocesses. Drives are d esign ed so th e h ead s can n ot overwrite th e servo in form ation , even d u rin g a low-level form at. On e m yth th at h as been circu latin g (esp ecially with resp ect to IDE d rives) is th at you can d am age th e servo in form ation by im p rop er lowlevel form attin g. Th is is n ot tru e. An im p rop er low-level form at m ay com p rom ise th e p erform an ce of th e d rive, bu t th e servo in form ation is totally p rotected an d can n ot be overwritten . Th e track-followin g cap abilities of a servo-con trolled voice coil actu ator elim in ates th e p osition in g errors th at occu r over tim e with step p er m otor d rives. Voice coil d rives are

Hard Disk Drives

n ot affected by con d ition s su ch as th erm al exp an sion an d con traction of th e p latters. In fact, m an y voice coil d rives tod ay p erform a sp ecial th erm al-recalibration p roced u re at p red eterm in ed in tervals wh ile th ey ru n . Th is p roced u re u su ally in volves seekin g th e h ead s from cylin d er 0 to som e oth er cylin d er on e tim e for every h ead on th e d rive. As th is seq u en ce occu rs, th e con trol circu itry in th e d rive m on itors h ow m u ch th e track p osition s h ave m oved sin ce th e last tim e th e seq u en ce was p erform ed , an d a th erm alrecalibration ad ju stm en t is calcu lated an d stored in th e d rive’s m em ory. Th is in form ation is th en u sed every tim e th e d rive p osition s th e h ead s to en su re th e m ost accu rate p osition in g p ossible. Most d rives p erform th e th erm al-recalibration seq u en ce every five m in u tes for th e first h alf-h ou r th at th e d rive is p owered on an d th en on ce every 25 m in u tes after th at. W ith som e d rives, th is th erm al-recalibration seq u en ce is very n oticeable; th e d rive essen tially stop s wh at it is d oin g, an d you h ear rap id tickin g for a secon d or so. Som e p eop le th in k th at th is is an in d ication th at th eir d rive is h avin g a p roblem read in g som eth in g an d p erh ap s is con d u ctin g a read retry, bu t th is is n ot tru e. Most of th e n ewer in telligen t d rives (IDE an d SCSI) em p loy th is th erm al-recalibration p roced u re to m ain tain p osition in g accu racy. As m u ltim ed ia ap p lication s grew in p op u larity, th erm al recalibration becam e a p roblem with som e m an u factu rers’ d rives. Th e th erm al-recalibration seq u en ce som etim es in terru p ted th e tran sfer of a large d ata file, su ch as an au d io or vid eo file, wh ich resu lted in au d io or vid eo p layback jitter. Som e com p an ies released sp ecial A/ V (Au d io Visu al) d rives th at h id e th e th erm al-recalibration seq u en ces so th ey n ever in terru p t a file tran sfer. Most of th e n ewer IDE an d SCSI d rives are A/ V cap able, wh ich m ean s th at th e th erm alrecalibration seq u en ces will n ot in terru p t a tran sfer su ch as a vid eo p layback. W h ile we are on th e su bject of au tom atic d rive fu n ction s, m ost of th e d rives th at p erform th erm al-recalibration seq u en ces also au tom atically p erform a fu n ction called a disk sweep. Also called wear leveling by som e m an u factu rers, th is p roced u re is an au tom atic h ead seek th at occu rs after th e d rive h as been id le for a p eriod of tim e. Th e d isk-sweep fu n ction m oves th e h ead s to a cylin d er in th e ou ter p ortion of th e p latters, wh ich is wh ere th e h ead float-h eigh t is h igh est (becau se th e h ead -to-p latter velocity is h igh est). Th en , if th e d rive con tin u es to rem ain id le for an oth er p eriod , th e h ead s m ove to an oth er cylin d er in th is area, an d th e p rocess con tin u es in d efin itely as lon g as th e d rive is p owered on . Th e d isk-sweep fu n ction is d esign ed to p reven t th e h ead from rem ain in g station ary above on e cylin d er in th e d rive for too lon g, wh ere friction between th e h ead an d p latter even tu ally wou ld d ig a tren ch in th e m ed iu m . Alth ou gh th e h ead s are n ot in d irect con tact with th e m ed iu m , th ey are so close th at th e con stan t air p ressu re from th e h ead floatin g above a sin gle cylin d er cou ld cau se friction an d excessive wear. W ed ge Ser vo . Som e early servo-con trolled d rives u sed a tech n iq u e called a wedge servo. In th ese d rives, th e gray-cod e gu id an ce in form ation is con tain ed in a “wed ge” slice of th e d rive in each cylin d er im m ed iately p reced in g th e in d ex m ark. Th e in d ex m ark in d icates th e begin n in g of each track, so th e wed ge-servo in form ation was written in th e PREINDEX GAP, wh ich is at th e en d of each track. Th is area is p rovid ed for sp eed toleran ce

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Chapter 12—M agnetic Storage

an d n orm ally is n ot u sed by th e con troller. Figu re 12.8 sh ows th e servo-wed ge in form ation on a d rive. Servo “wedge”

Gray code information on radial position

Gray code information for fine radial positioning

Sectors

FIG. 12.8 A wed ge servo. Som e con trollers h ad to be n otified th at th e d rive was u sin g a wed ge servo so th ey cou ld sh orten th e sector tim in g to allow for th e wed ge-servo area. If th ey were n ot correctly con figu red , th ese con trollers wou ld n ot work p rop erly with th e d rive. An oth er p roblem was th at th e servo in form ation ap p ears on ly on e tim e every revolu tion , wh ich m ean s th at th e d rive often n eed ed several revolu tion s before it cou ld accu rately d eterm in e an d ad ju st th e h ead p osition . Becau se of th ese p roblem s, th e wed ge servo n ever was a p op u lar d esign ; it n o lon ger is u sed in d rives. Em b ed d ed Ser vo . An em bedded servo (see Figu re 12.9) is an en h an cem en t of th e wed ge servo. In stead of p lacin g th e servo cod e before th e begin n in g of each cylin d er, an em bed d ed servo d esign writes th e servo in form ation before th e start of each sector. Th is arran gem en t en ables th e p osition er circu its to receive feed back m an y tim es in a sin gle

Hard Disk Drives

revolu tion , m akin g th e h ead p osition in g m u ch faster an d m ore p recise. An oth er ad van tage is th at every track on th e d rive h as its own p osition in g in form ation , so each h ead can q u ickly an d efficien tly ad ju st p osition to com p en sate for an y ch an ges in th e p latter or h ead d im en sion s, esp ecially for ch an ges d u e to th erm al exp an sion or p h ysical stress. Start of track (index)

Sectors of data

Gray code information Gray code information for fine radial positioning

FIG. 12.9 An em bed d ed servo. Most d rives tod ay u se an em bed d ed servo to con trol th e p osition in g system . As in th e wed ge servo d esign , th e em bed d ed servo in form ation is p rotected by th e d rive circu its, an d an y write op eration s are blocked wh en ever th e h ead s are above th e servo in form ation . Th u s, it is im p ossible to overwrite th e servo in form ation with a low-level form at, as som e p eop le in correctly believe. Alth ou gh th e em bed d ed servo works m u ch better th an th e wed ge servo becau se th e servo feed back in form ation is m ad e available several tim es in a sin gle d isk revolu tion , a system th at offered con tin u ou s servo feed back in form ation wou ld be better.

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D ed i ca t ed Ser vo . A dedicated servo is a d esign in wh ich th e servo in form ation is written con tin u ou sly th rou gh ou t th e en tire track, rath er th an ju st on ce p er track or at th e begin n in g of each sector. Un fortu n ately, if th is p roced u re were u sed on th e en tire d rive, n o room wou ld be left for d ata. For th is reason , a d ed icated servo u ses on e sid e of on e of th e p latters exclu sively for th e servo-p osition in g in form ation . Th e term dedicated com es from th e fact th at th is p latter sid e is com p letely d ed icated to th e servo in form ation an d can n ot con tain an y d ata. W h en bu ild in g a d ed icated servo d rive, th e m an u factu rer d ed u cts on e sid e of on e p latter from n orm al read / write u sage, an d record s a sp ecial set of gray-cod e d ata th ere th at in d icates th e p rop er track p osition s. Becau se th e h ead th at rests above th is su rface can n ot be u sed for n orm al read in g an d writin g, th e gray cod e can n ever be erased , an d th e servo in form ation is p rotected , as in th e oth er servo d esign s. No low-level form at or oth er p roced u re can p ossibly overwrite th e servo in form ation . W h en th e d rive m oves th e h ead s to a sp ecific cylin d er, th e in tern al d rive electron ics u se th e sign als received by th e servo h ead to d eterm in e th e p osition of th e read / write h ead s. As th e h ead s m ove, th e track cou n ters are read from th e d ed icated servo su rface. W h en th e servo h ead d etects th e req u ested track, th e actu ator stop s. Th e servo electron ics th en fin e-tu n e th e p osition so th e h ead s are p osition ed p recisely above th e d esired cylin d er before an y writin g is p erm itted . Alth ou gh on ly on e h ead is u sed for servo trackin g, th e oth er h ead s are attach ed to th e sam e rack so if on e h ead is above th e d esired cylin d er, all th e oth ers will be as well. On e way of tellin g if a d rive u ses a d ed icated servo p latter is if it h as an od d n u m ber of h ead s. For exam p le, th e Tosh iba MK-538FB 1.2G d rive th at I h ave on m y com p u ter h as 8 p latters, bu t on ly 15 read / write h ead s. Th e d rive u ses a d ed icated -servo p osition in g system , an d th e 16th h ead is th e servo h ead . Th e ad van tage of th e d ed icated servo con cep t is th at th e servo in form ation is con tin u ou sly available to th e d rive, m akin g th e h ead p osition in g p rocess faster an d m ore p recise. Th e d rawback is th at d ed icatin g an en tire p latter su rface to servo in form ation can be wastefu l. More d rives tod ay u se em bed d ed servo in form ation th an d ed icated servo. Som e d rives com bin e a d ed icated servo with an em bed d ed servo, bu t th is typ e of h ybrid d esign is rare. Of cou rse, as m en tion ed earlier, tod ay’s IDE an d SCSI d rives h ave h ead , track, an d sectorp er-track p aram eters th at are tran slated from th e actu al p h ysical n u m bers. Th erefore, it is n ot u su ally p ossible to tell from th e p u blish ed n u m bers exactly h ow m an y h ead s or p latters are con tain ed with in a d rive. Au t o m a t i c H e a d P a rk i n g . W h en you p ower off a h ard d isk d rive, th e sp rin g ten sion in each h ead arm p u lls th e h ead s in to con tact with th e p latters. Th e d rive is d esign ed to su stain th ou san d s of takeoffs an d lan d in gs, bu t it is wise to en su re th at th e lan d in g occu rs at a sp ot on th e p latter th at con tain s n o d ata. Som e am ou n t of abrasion occu rs d u rin g th e lan d in g an d takeoff p rocess, rem ovin g ju st a “m icro p u ff” from th e m agn etic m ed iu m ; bu t if th e d rive is jarred d u rin g th e lan d in g or takeoff p rocess, real d am age can occu r.

Hard Disk Drives

On e ben efit of u sin g a voice coil actu ator is autom atic head parking. In a d rive th at h as a voice coil actu ator, th e h ead s are p osition ed an d h eld by m agn etic force. W h en th e p ower to th e d rive is rem oved , th e m agn etic field th at h old s th e h ead s station ary over a p articu lar cylin d er d issip ates, en ablin g th e h ead rack to skitter across th e d rive su rface an d p oten tially cau se d am age. In th e voice coil d esign , th e h ead rack is attach ed to a weak sp rin g at on e en d an d a h ead stop at th e oth er en d . W h en th e system is p owered on , th e sp rin g is overcom e by th e m agn etic force of th e p osition er. W h en th e d rive is p owered off, h owever, th e sp rin g gen tly d rags th e h ead rack to a p ark-an d -lock p osition before th e d rive slows d own an d th e h ead s lan d . On som e d rives, you can actu ally h ear th e “tin g…tin g…tin g…tin g” sou n d as th e h ead s literally bou n ce-p ark th em selves, d riven by th is sp rin g. On a d rive with a voice coil actu ator, you activate th e p arkin g m ech an ism by tu rn in g off th e com p u ter; you d o n ot n eed to ru n a p rogram to p ark or retract th e h ead s. In th e even t of a p ower ou tage, th e h ead s p ark th em selves au tom atically. (Th e d rives u n p ark au tom atically wh en th e system is p owered on .) Air Filt ers. Nearly all h ard d isk d rives h ave two air filters. On e filter is called th e recirculating filter, an d th e oth er is called eith er a barom etric or breather filter. Th ese filters are p erm an en tly sealed in sid e th e d rive an d are d esign ed n ever to be ch an ged for th e life of th e d rive, u n like m an y old er m ain fram e h ard d isks th at h ad ch an geable filters. A h ard d isk on a PC system d oes n ot circu late air from in sid e to ou tsid e th e HDA, or vice versa. Th e recircu latin g filter th at is p erm an en tly in stalled in sid e th e HDA is d esign ed to filter on ly th e sm all p articles scrap ed off th e p latters d u rin g h ead takeoffs an d lan d in gs (an d p ossibly an y oth er sm all p articles d islod ged in sid e th e d rive). Becau se PC h ard d isk d rives are p erm an en tly sealed an d d o n ot circu late ou tsid e air, th ey can ru n in extrem ely d irty en viron m en ts (see Figu re 12.10). Recirculating filter

Air flow path

FIG. 12.10 Air circu lation in a h ard d isk.

Rotary voice coil

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Th e HDA in a h ard d isk d rive is sealed bu t n ot airtigh t. Th e HDA is ven ted th rou gh a barom etric or breath er filter elem en t th at allows for p ressu re eq u alization (breath in g) between th e in sid e an d ou tsid e of th e d rive. For th is reason , m ost h ard d rives are rated by th e d rive’s m an u factu rer to ru n in a sp ecific ran ge of altitu d es, u su ally from 1,000 feet below to 10,000 feet above sea level. In fact, som e h ard d rives are n ot rated to exceed 7,000 feet wh ile op eratin g, becau se th e air p ressu re wou ld be too low in sid e th e d rive to float th e h ead s p rop erly. As th e en viron m en tal air p ressu re ch an ges, air bleed s in to or ou t of th e d rive so in tern al an d extern al p ressu res are id en tical. Alth ou gh air d oes bleed th rou gh a ven t, con tam in ation u su ally is n ot a con cern , becau se th e barom etric filter on th is ven t is d esign ed to filter ou t all p articles larger th an 0.3 m icron s (abou t 12 µ-in ) to m eet th e sp ecification s for clean lin ess in sid e th e d rive. You can see th e ven t h oles on m ost d rives, wh ich are covered in tern ally by th is breath er filter. Som e d rives u se even fin er-grad e filter elem en ts to keep ou t even sm aller p articles. I con d u cted a sem in ar in Hawaii several years ago, an d several of th e stu d en ts were from th e Mau n a Kea astron om ical observatory. Th ey in d icated th at virtu ally all th e h ard d isk d rives th ey h ad tried to u se at th e observatory site h ad failed very q u ickly, if th ey worked at all. Th is was n o su rp rise, becau se th e observatory is at th e 13,800-foot p eak of th e m ou n tain , an d at th at altitu d e, even p eop le d on ’t fu n ction very well! At th e tim e, it was su ggested th at th e stu d en ts look in to solid -state (RAM) d isks, tap e d rives, or even flop p y d isk d rives as th eir p rim ary storage m ed iu m . Sin ce th is tim e, IBM’s Ad star d ivision (wh ich p rod u ces all IBM h ard d rives) in trod u ced a lin e of ru gged 3 1/ 2-in ch d rives th at are h erm etically sealed (airtigh t), alth ou gh th ey d o h ave air in sid e th e HDA. Becau se th ey carry th eir own in tern al air u n d er p ressu re, th ese d rives can op erate at an y altitu d e, an d can also with stan d extrem es of sh ock an d tem p eratu re. Th e d rives are d esign ed for m ilitary an d in d u strial ap p lication s, su ch as system s u sed aboard aircraft an d in extrem ely h arsh en viron m en ts. Hard Disk Tem perat ure Acclim at ion. Becau se h ard d rives h ave a filtered p ort to bleed air in to or ou t of th e HDA, m oistu re can en ter th e d rive, an d after som e p eriod of tim e, it m u st be assu m ed th at th e h u m id ity in sid e an y h ard d isk is sim ilar to th at ou tsid e th e d rive. Hu m id ity can becom e a seriou s p roblem if it is allowed to con d en se—an d esp ecially if you p ower u p th e d rive wh ile th is con d en sation is p resen t. Most h ard d isk m an u factu rers h ave sp ecified p roced u res for acclim atin g a h ard d rive to a n ew en viron m en t with d ifferen t tem p eratu re an d h u m id ity ran ges, an d esp ecially for brin gin g a d rive in to a warm er en viron m en t in wh ich con d en sation can form . Th is situ ation sh ou ld be of sp ecial con cern to u sers of lap top or p ortable system s. If you leave a p ortable system in an au tom obile tru n k d u rin g th e win ter, for exam p le, it cou ld be catastrop h ic to brin g th e m ach in e in sid e an d p ower it u p with ou t allowin g it to acclim ate to th e tem p eratu re in d oors. Th e followin g text an d Table 12.8 are taken from th e factory p ackagin g th at Con trol Data Corp oration (later Im p rim is an d even tu ally Seagate) u sed to sh ip its h ard d rives:

Hard Disk Drives

If you h ave ju st received or rem oved th is u n it from a clim ate with tem p eratu res at or below 50°F (10°C) d o n ot op en th is con tain er u n til th e followin g con d ition s are m et, oth erwise con d en sation cou ld occu r an d d am age to th e d evice an d / or m ed ia m ay resu lt. Place th is p ackage in th e op eratin g en viron m en t for th e tim e d u ration accord in g to th e tem p eratu re ch art. Table 12.8

Hard Disk Drive Environm ent al Acclim at ion Table

Previous Clim at e Tem perat ure

Acclim at ion Tim e

+40°F (+4°C)

13 hours

+30°F (–1°C)

15 hours

+20°F (–7°C)

16 hours

+10°F (–12°C)

17 hours

0°F (–18°C)

18 hours

–10°F (–23°C)

20 hours

–20°F (–29°C) –30°F (–34°C) or less

22 hours 27 hours

As you can see from th is table, you m u st p lace a h ard d isk d rive th at h as been stored in a cold er-th an -n orm al en viron m en t in to its n orm al op eratin g en viron m en t for a sp ecified am ou n t of tim e to allow it to acclim ate before you p ower it on . Spindle M ot ors. Th e m otor th at sp in s th e p latters is called th e spindle m otor becau se it is con n ected to th e sp in d le arou n d wh ich th e p latters revolve. Sp in d le m otors in h ard d isk d rives are always con n ected d irectly; th ere are n o belts or gears in volved . Th e m otor m u st be free of n oise an d vibration ; oth erwise, it can tran sm it a ru m ble to th e p latters th at can d isru p t read in g an d writin g op eration s. Th e sp in d le m otor m u st also be p recisely con trolled for sp eed . Th e p latters in h ard d isk d rives revolve at sp eed s ran gin g from 3,600 to 7,200 RPM or m ore, an d th e m otor h as a con trol circu it with a feed back loop to m on itor an d con trol th is sp eed p recisely. Becau se th e sp eed con trol m u st be au tom atic, h ard d rives d o n ot h ave a m otor-sp eed ad ju stm en t. Som e d iagn ostics p rogram s claim to m easu re h ard d rive rotation sp eed , bu t all th at th ese p rogram s d o is estim ate th e rotation al sp eed by th e tim in g at wh ich sectors p ass u n d er th e h ead s. Th ere is actu ally n o way for a p rogram to m easu re th e h ard d isk d rive’s rotation al sp eed ; th is m easu rem en t can be m ad e on ly with sop h isticated test eq u ip m en t. Don ’t be alarm ed if som e d iagn ostics p rogram tells you th at you r d rive is sp in n in g at an in correct sp eed ; m ost likely th e p rogram is wron g, n ot th e d rive. Platter rotation an d tim in g in form ation is n ot p rovid ed th rou gh th e h ard d isk con troller in terface. In th e p ast, software cou ld give ap p roxim ate rotation al sp eed estim ates by p erform in g m u ltip le sector read req u ests an d tim in g th em , bu t th is was valid on ly wh en all d rives h ad th e sam e n u m ber of sectors p er track an d sp u n at th e sam e sp eed . Zon ed Bit Record in g—com bin ed with th e m an y d ifferen t rotation al sp eed s u sed by m od ern d rives, n ot to m en tion bu ilt-in

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bu ffers an d cach es—m ean s th at th ese calcu lation estim ates can n ot be p erform ed accu rately by software. On m ost d rives, th e sp in d le m otor is on th e bottom of th e d rive, ju st below th e sealed HDA. Man y d rives tod ay, h owever, h ave th e sp in d le m otor bu ilt d irectly in to th e p latter h u b in sid e th e HDA. By u sin g an in tern al h u b sp in d le m otor, th e m an u factu rer can stack m ore p latters in th e d rive, becau se th e sp in d le m otor takes u p n o vertical sp ace.

Not e Spindle motors, particularly on the larger form-factor drives, can consume a great deal of 12-volt power. M ost drives require two to three times the normal operating power when the motor first spins the platters. This heavy draw lasts only a few seconds, or until the drive platters reach operating speed. If you have more than one drive, you should try to sequence the start of the spindle motors so the power supply does not have to provide such a large load to all the drives at the same time. M ost SCSI and IDE drives have a delayed spindle-motor start feature.

Logic Boards. All h ard d isk d rives h ave on e or m ore logic board s m ou n ted on th em . Th e logic boards con tain th e electron ics th at con trol th e d rive’s sp in d le an d h ead actu ator system s an d th at p resen t d ata to th e con troller in som e agreed -u p on form . On IDE d rives, th e board s in clu d e th e con troller itself, wh ile SCSI d rives in clu d e th e con troller an d th e SCSI bu s ad ap ter circu it. Man y d isk d rive failu res occu r in th e logic board , n ot in th e m ech an ical assem bly. (Th is statem en t d oes n ot seem logical, bu t it is tru e.) Th erefore, you can som etim es rep air a failed d rive by rep lacin g ju st th e logic board , rath er th an th e en tire d rive. Rep lacin g th e logic board , m oreover, en ables you to regain access to th e d ata on th e d rive—som eth in g th at rep lacin g th e en tire d rive d oes n ot. In m an y cases, logic board s p lu g in to th e d rive an d are easily rep laceable. Th ese board s are u su ally m ou n ted with stan d ard screw h ard ware. If a d rive is failin g an d you h ave a sp are, you m ay be able to verify a logic-board failu re by takin g th e board off th e kn own good d rive an d m ou n tin g it on th e bad on e. If you r su sp icion s are con firm ed , you can ord er a n ew logic board from th e d rive m an u factu rer, bu t u n less you h ave d ata on th e d rive you n eed to recover, it m ay m ake m ore sen se to ju st bu y a n ew d rive, con sid erin g tod ay’s low d isk d rive costs. To red u ce costs fu rth er, m an y th ird -p arty ven d ors can also su p p ly rep lacem en t logicboard assem blies. Th ese com p an ies often ch arge m u ch less th an th e d rive m an u factu rers for th e sam e com p on en ts. (See Ap p en d ix A, “Ven d or List,” for ven d ors of d rive com p on en ts, in clu d in g logic board s.) Cables and Connect ors. Hard d isk d rives typ ically h ave several con n ectors for in terfacin g to th e com p u ter, receivin g p ower, an d som etim es grou n d in g to th e system ch assis. Most d rives h ave at least th ese th ree typ es of con n ectors: ■ In terface con n ector(s)

Hard Disk Drives

■ Power con n ector ■ Op tion al grou n d con n ector (tab) Of th ese, th e interface connectors are th e m ost im p ortan t, becau se th ey carry th e d ata an d com m an d sign als between th e system an d th e d rive. In m ost cases, th e d rive in terface cables can be con n ected in a daisy chain or bu s-typ e con figu ration . Most in terfaces su p p ort at least two d evices, an d SCSI (Sm all Com p u ter System In terface) can su p p ort u p to seven (W id e SCSI-2 can su p p ort u p to 15) d evices in th e ch ain , in ad d ition to th e h ost ad ap ter. Old er in terfaces, su ch as ST-506/ 412 or ESDI (En h an ced Sm all Device In terface), u sed sep arate cables for d ata an d con trol sign als, bu t tod ay’s SCSI an d IDE (In tegrated Drive Electron ics) d rives h ave a sin gle con n ector. √√ See “ ATA I/ O Connector,” p. 615, and “ SCSI Cables and Connectors,” p. 634

Th e power connector is u su ally th e sam e 4-p in typ e th at is u sed in flop p y d isk d rives, an d th e sam e p ower-su p p ly con n ector p lu gs in to it. Most h ard d isk d rives u se both 5- an d 12volt p ower, alth ou gh som e of th e sm aller d rives d esign ed for p ortable ap p lication s u se on ly 5-volt p ower. In m ost cases, th e 12-volt p ower ru n s th e sp in d le m otor an d h ead actu ator, an d th e 5-volt p ower ru n s th e circu itry. Make su re th at you r p ower su p p ly can su p p ly ad eq u ate p ower for th e h ard d isk d rives in stalled in you r system . Th e 12-volt p ower con su m p tion of a d rive u su ally varies with th e p h ysical size of th e u n it. Th e larger th e d rive is, th e faster it sp in s, an d th e m ore p latters th ere are to sp in , th e m ore p ower th at it req u ires. For exam p le, m ost of th e 3 1/ 2-in ch d rives on th e m arket tod ay u se rou gh ly on e-h alf to on e-fou rth th e p ower (in watts) of th e old er 5 1/ 4-in ch d rives. Som e of th e very sm all (2 1/ 2- or 1.8-in ch ) h ard d isks barely sip electrical p ower an d actu ally u se 1 watt or less! A grounding tab p rovid es a p ositive grou n d con n ection between th e d rive an d th e system ’s ch assis. In m ost com p u ters, th e h ard d isk d rive is m ou n ted d irectly to th e ch assis u sin g screws so th e grou n d wire is u n n ecessary. On som e system s, th e d rives are in stalled on p lastic or fiberglass rails, wh ich d o n ot p rovid e p rop er grou n d in g. Th ese system s m u st p rovid e a grou n d in g wire p lu gged in to th e d rive at th is grou n d in g tab. Failu re to grou n d th e d rive m ay resu lt in im p rop er op eration , in term itten t failu re, or gen eral read an d write errors. Configurat ion It em s. To con figu re a h ard d isk d rive for in stallation in a system , you u su ally m u st set several ju m p ers (an d , p ossibly, term in atin g resistors) p rop erly. Th ese item s vary from in terface to in terface an d often from d rive to d rive as well. A com p lete d iscu ssion of th e con figu ration settin gs for each in terface ap p ears in th e section “Hard Disk In stallation Proced u res” later in th is ch ap ter. The Faceplat e or Bezel. Man y h ard d isk d rives offer as an op tion a fron t facep late, or bezel (see Figu re 12.11). A bezel u su ally is su p p lied as an op tion for th e d rive rath er th an as a stan d ard item . In m ost cases tod ay, th e bezel is a p art of th e case an d n ot th e d rive itself.

753

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Chapter 12—M agnetic Storage

FIG. 12.11 Typ ical 5 1/ 4- an d 3 1/ 2-in ch h ard d rives bezel sh own from th e fron t (as seen on th e ou tsid e of th e PC case) (top ) an d from th e back (bottom ) (th e in sid e m ou n tin g an d LED wirin g). Old er system s h ad th e d rive in stalled so it was visible ou tsid e th e system case. To cover th e h ole in th e case, you wou ld u se an op tion al bezel or facep late. Bezels often com e in several sizes an d colors to m atch variou s PC system s. Man y facep late con figu ration s for 3 1/ 2-in ch d rives are available, in clu d in g bezels th at fit 3 1/ 2-in ch d rive bays as well as 5 1/ 4-in ch d rive bays. You even h ave a ch oice of colors (u su ally black, cream , or wh ite). Som e bezels featu re a Ligh t-Em ittin g Diod e (LED) th at flickers wh en you r h ard d isk is in u se. Th e LED is m ou n ted in th e bezel; th e wire h an gin g off th e back of th e LED p lu gs in to th e d rive. In som e d rives, th e LED is p erm an en tly m ou n ted on th e d rive, an d th e bezel h as a clear or colored win d ow so you can see th e LED flicker wh ile th e d rive is bein g accessed . In system s in wh ich th e h ard d isk is h id d en by th e u n it’s cover, a bezel is n ot n eed ed . In fact, u sin g a bezel m ay p reven t th e cover from restin g on th e ch assis p rop erly, in wh ich case th e bezel will h ave to be rem oved . If you are in stallin g a d rive th at d oes n ot h ave a p rop er bezel, fram e, or rails to attach to th e system , ch eck Ap p en d ix A of th is book; several listed ven d ors offer th ese accessories for a variety of d rives. Hard Disk Feat ures To m ake th e best d ecision in p u rch asin g a h ard d isk for you r system , or to u n d erstan d wh at d ifferen tiates on e bran d of h ard d isk from an oth er, you m u st con sid er m an y featu res. Th is section exam in es som e of th e issu es th at you sh ou ld con sid er wh en you evalu ate d rives: ■ Reliability

■ Sh ock m ou n tin g

■ Sp eed

■ Cost

Hard Disk Drives

Reliabilit y. W h en you sh op for a d rive, you m ay n otice a statistic called th e Mean Tim e Between Failures (MTBF) d escribed in th e d rive sp ecification s. MTBF figu res u su ally ran ge from 20,000 h ou rs to 500,000 h ou rs or m ore. I u su ally ign ore th ese figu res becau se th ey are d erived th eoretically. In u n d erstan d in g th e MTBF claim s, it is im p ortan t to u n d erstan d h ow th e m an u factu rers arrive at th em an d wh at th ey m ean . Most m an u factu rers h ave a lon g h istory of bu ild in g d rives an d th eir d rives h ave seen m illion s of h ou rs of cu m u lative u se. Th ey can look at th e failu re rate for p reviou s d rive m od els with th e sam e com p on en ts an d calcu late a failu re rate for a n ew d rive based on th e com p on en ts u sed to bu ild th e d rive assem bly. For th e electron ic circu it board , th ey can also u se in d u stry stan d ard tech n iq u es for p red ictin g th e failu re of th e in tegrated electron ics. Th is en ables th em to calcu late th e p red icted failu re rate for th e en tire d rive u n it. To u n d erstan d wh at th ese n u m bers m ean , it is im p ortan t to kn ow th at th e MTBF claim s ap p ly to a population of d rives, n ot an in d ivid u al d rive. Th is m ean s th at if a d rive claim s to h ave a MTBF of 500,000 h ou rs, you can exp ect a failu re in th at p op u lation of d rives in 500,000 h ou rs of total ru n n in g tim e. If th ere are 1,000,000 d rives of th is m od el in service an d all 1,000,000 are ru n n in g at on ce, you can exp ect on e failu re ou t of th is en tire p op u lation every 1/ 2 h ou r. MTBF statistics are n ot u sefu l for p red ictin g th e failu re of an y in d ivid u al d rive or a sm all sam p le of d rives. It is also im p ortan t to u n d erstan d th e m ean in g of th e word failure in th is u se. In th is sen se, a failu re is a fau lt th at req u ires th e d rive to be retu rn ed to th e m an u factu rer for rep air, n ot an occasion al failu re to read or write a file correctly. Fin ally, as som e d rive m an u factu rers p oin t ou t, th is m easu re of MTBF sh ou ld really be called m ean tim e to first failure. “Between failu res” im p lies th at th e d rive fails, is retu rn ed for rep air, an d th en at som e p oin t fails again . Th e in terval between rep air an d th e secon d failu re h ere wou ld be th e MTBF. Becau se in m ost cases, a failed h ard d rive th at wou ld n eed m an u factu rer rep air is rep laced rath er th an rep aired , th e wh ole MTBF con cep t is m isn am ed . Th e bottom lin e is th at I d o n ot really p lace m u ch em p h asis on MTBF figu res. For an in d ivid u al d rive, th ey are n ot accu rate p red ictors of reliability. However, if you are an in form ation system s m an ager con sid erin g th e p u rch ase of th ou san d s of PCs or d rives p er year, or a system ven d or bu ild in g an d su p p ortin g th ou san d s of system s, it is worth you r wh ile to exam in e th ese n u m bers an d stu d y th e m eth od s u sed to calcu late th em by each ven d or. If you can u n d erstan d th e ven d or’s calcu lation s an d com p are th e actu al reliability of a large sam p le of d rives, th en you can p u rch ase m ore reliable d rives an d save tim e an d m on ey in service an d su p p ort. Perform ance. W h en you select a h ard d isk d rive, on e of th e im p ortan t featu res you sh ou ld con sid er is th e p erform an ce (sp eed ) of th e d rive. Hard d rives can h ave a wid e ran ge of p erform an ce cap abilities. As is tru e of m an y th in gs, on e of th e best in d icators of a d rive’s relative p erform an ce is its p rice. An old sayin g from th e au tom obile-racin g in d u stry is ap p rop riate h ere: “Sp eed costs m on ey. How fast d o you wan t to go?”

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You can m easu re th e sp eed of a d isk d rive in two ways: ■ Average seek tim e ■ Tran sfer rate Average seek tim e, n orm ally m easu red in m illisecon d s (m s), is th e average am ou n t of tim e it takes to m ove th e h ead s from on e cylin d er to an oth er cylin d er a ran d om d istan ce away. On e way to m easu re th is sp ecification is to ru n m an y ran d om track-seek op eration s an d th en d ivid e th e tim ed resu lts by th e n u m ber of seeks p erform ed . Th is m eth od p rovid es an average tim e for a sin gle seek. Th e stan d ard m eth od u sed by m an y d rive m an u factu rers to m easu re th e average seek tim e in volves m easu rin g th e tim e th at it takes th e h ead s to m ove across on e-th ird of th e total cylin d ers. Average seek tim e d ep en d s on ly on th e d rive itself; th e typ e of in terface or con troller h as little effect on th is sp ecification . Th e ratin g is a gau ge of th e cap abilities of th e h ead actu ator.

Not e Be wary of benchmarks that claim to measure drive seek performance. M ost IDE and SCSI drives use a scheme called sector translation, so any commands that the drive receives to move the heads to a specific cylinder may not actually result in the intended physical movement. This situation renders some benchmarks meaningless for those types of drives. SCSI drives also require an additional step, because the commands first must be sent to the drive over the SCSI bus. These drives may seem to have the fastest access times because the command overhead is not factored in by most benchmarks. However, when this overhead is factored in by benchmark programs, these drives receive poor performance figures.

A sligh tly d ifferen t m easu rem en t, called average access tim e, in volves an oth er elem en t, called laten cy. Latency is th e average tim e (in m illisecon d s) th at it takes for a sector to be available after th e h ead s h ave reach ed a track. On average, th is figu re is h alf th e tim e th at it takes for th e d isk to rotate on ce, wh ich is 8.33m s at 3,600 RPM. A d rive th at sp in s twice as fast wou ld h ave h alf th e laten cy. A m easu rem en t of a d rive’s average access tim e is th e su m of its average seek tim e an d its laten cy. Th is n u m ber p rovid es th e average am ou n t of tim e req u ired before th e d rive can access a ran d om ly req u ested sector. Laten cy is a factor in d isk read an d write p erform an ce. Decreasin g th e laten cy in creases th e sp eed of access to d ata or files an d is accom p lish ed on ly by sp in n in g th e d rive p latters faster. I h ave a d rive th at sp in s at 4,318 RPM, for a laten cy of 6.95m s. Som e d rives sp in at 7,200 RPM, resu ltin g in an even sh orter laten cy tim e of on ly 4.17m s, wh ile oth ers sp in at 10,000 rp m , resu ltin g in an in cred ible 3.00m s laten cy. In ad d ition to in creasin g p erform an ce wh ere real-world access to d ata is con cern ed , sp in n in g th e p latters faster also in creases th e d ata-tran sfer rate after th e h ead s arrive at th e d esired sectors. Th e tran sfer rate is p robably m ore im p ortan t to overall system p erform an ce th an an y oth er statistic. Transfer rate is th e rate at wh ich th e d rive an d con troller can sen d d ata to th e system . Th e tran sfer rate d ep en d s p rim arily on th e d rive’s HDA an d secon d arily on th e con troller. Tran sfer rates u sed to be bou n d m ore to th e lim its of th e con troller,

Hard Disk Drives

m ean in g th at d rives th at were con n ected to n ewer con trollers often ou tp erform ed th ose con n ected to old er con trollers. Th is situ ation is wh ere th e con cep t of in terleavin g sectors cam e from . Interleaving refers to th e ord erin g of th e sectors so th ey are n ot seq u en tial, en ablin g a slow con troller to keep u p with ou t m issin g th e n ext sector. Mod ern d rives with in tegrated con trollers are fu lly cap able of keep in g u p with th e raw d rive tran sfer rate. In oth er word s, th ey n o lon ger h ave to in terleave th e sectors to slow th e d ata for th e con troller. An oth er p erform an ce issu e is th e raw in terface p erform an ce wh ich , in IDE or SCSI d rives, is u su ally far h igh er th an an y of th e d rives th em selves are able to su stain . Be wary of tran sfer sp ecification s th at are q u oted for th e in terface an d n ot th e d rive, becau se th ey m ay h ave little effect on wh at th e d rive can actu ally p rod u ce. Th e d rive in terface lim its th e m axim u m th eoretical tran sfer rate; th e actu al d rive an d con troller gen erate th e real lim its on p erform an ce. To calcu late th e tru e tran sfer rate of a d rive, you h ave to kn ow several im p ortan t sp ecification s. Th e two m ost im p ortan t sp ecification s are th e tru e rotation al sp eed of th e d rive (in RPM) an d th e average n u m ber of p h ysical sectors on each track (SPT). I say “average” becau se m ost d rives tod ay u se a Zon ed Bit Record in g tech n iq u e th at creates d ifferen t n u m bers of sectors on th e cylin d ers. Th e tran sfer rate on Zon ed Bit Record in g d rives always is fastest in th e ou term ost zon e, wh ere th e sector p er track cou n t is h igh est. Also, be aware th at m an y d rives (esp ecially Zon ed Bit Record in g d rives) are con figu red with sector tran slation , so th e n u m ber of sectors p er track rep orted by th e BIOS h as little to d o with th e actu al p h ysical ch aracteristics of th e d rive. You m u st kn ow th e d rive’s tru e p h ysical p aram eters, rath er th an th e valu es th at th e BIOS u ses. W h en you kn ow th ese figu res, you can u se th e followin g form u la to d eterm in e th e m axim u m d ata tran sfer rate in m illion s of bits p er secon d (Mbp s): Maxim u m Tran sfer Rate (Mbp s) = SPT×512 bytes×RPM/ 60 secon d s/ 1,000,000 bits For exam p le, th e Seagate ST-12551N 2G 3 1/ 2-in ch d rive sp in s at 7,200 RPM an d h as an average of 81 sectors p er track. Th e m axim u m tran sfer rate for th is d rive is figu red as follows: 81×512×7,200/ 60/ 1,000,000 = 4.98Mbp s Usin g th is form u la, you can calcu late th e tru e m axim u m su stain ed tran sfer rate of an y d rive. Ca c h e P ro g ra m s a n d Ca c h i n g Co n t ro l l e rs. At th e software level, d isk cach e p rogram s su ch as SMARTDRV (in DOS) or VCACHE (in W in d ows 9x) can h ave a m ajor effect on d isk d rive p erform an ce. Th ese cach e p rogram s h ook in to th e BIOS h ard d rive in terru p t an d in tercep t th e read an d write calls to th e d isk BIOS from ap p lication p rogram s an d d evice d rivers.

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W h en an ap p lication p rogram wan ts to read d ata from a h ard d rive, th e cach e p rogram in tercep ts th e read req u est, p asses th e read req u est to th e h ard d rive con troller in th e u su al way, saves th e d ata read from th e d isk in its cach e m em ory bu ffer, an d th en p asses th e d ata back to th e ap p lication p rogram . Dep en d in g on th e size of th e cach e bu ffer, d ata from n u m erou s sectors can be read in to an d saved in th e bu ffer. W h en th e ap p lication wan ts to read m ore d ata, th e cach e p rogram again in tercep ts th e req u est an d exam in es its bu ffers to see wh eth er th e req u ested d ata is still in th e cach e. If so, th e p rogram p asses th e d ata back from th e cach e to th e ap p lication im m ed iately, with ou t an oth er h ard d rive op eration . Becau se th e cach ed d ata is stored in m em ory, th is m eth od sp eed s access trem en d ou sly an d can greatly affect d isk d rive p erform an ce m easu rem en ts. Most con trollers n ow h ave som e form of bu ilt-in h ard ware bu ffer or cach e th at d oesn ’t in tercep t or u se an y BIOS in terru p ts. In stead , th e d rive cach es d ata at th e h ard ware level, wh ich is in visible to n orm al p erform an ce-m easu rem en t software. Man u factu rers origin ally in clu d ed track read -ah ead bu ffers in con trollers to p erm it 1:1 in terleave p erform an ce. Som e m an u factu rers n ow in crease th e size of th ese read -ah ead bu ffers in th e con troller, wh ile oth ers ad d in telligen ce by u sin g a cach e in stead of a sim p le bu ffer. Man y IDE an d SCSI d rives h ave cach e m em ory bu ilt d irectly in to th e d rive’s on -board con troller. For exam p le, th e Seagate Hawk 4G d rive on wh ich I am savin g th is ch ap ter h as 512K of bu ilt-in cach e m em ory. Oth er d rives h ave even larger bu ilt-in cach es, su ch as th e Seagate Barracu d a 4G with 1M of in tegrated cach e m em ory. I rem em ber wh en 640K was a lot of m em ory for an en tire system . Now, tin y 3 1/ 2-in ch h ard d isk d rives h ave m ore th an th at bu ilt righ t in ! Th ese in tegrated cach es are p art of th e reason m an y IDE an d SCSI d rives p erform so well. Alth ou gh software an d h ard ware cach es can m ake a d rive faster for rou tin e tran sfer op eration s, a cach e will n ot affect th e tru e m axim u m tran sfer rate th at th e d rive can su stain . In t e rl e a v e Se l e c t i o n . In a d iscu ssion of d isk p erform an ce, th e issu e of in terleave often com es u p . Alth ou gh trad ition ally th is was m ore a con troller p erform an ce issu e th an a d rive issu e, m od ern IDE an d SCSI h ard d isk d rives with bu ilt-in con trollers are fu lly cap able of p rocessin g th e d ata as fast as th e d rive can sen d it. In oth er word s, virtu ally all m od ern IDE an d SCSI d rives are form atted with n o in terleave (som etim es exp ressed as a 1:1 in terleave ratio). On old er h ard d rive typ es, su ch as MFM an d ESDI, you cou ld m od ify th e in terleave d u rin g a low-level form at to op tim ize th e d rive’s p erform an ce. Tod ay, d rives are low-level form atted at th e factory an d in terleave ad ju stm en ts are a m oot top ic. H e a d a n d Cy l i n d e r Sk e w i n g . An oth er p erform an ce ad ju stm en t th at you cou ld m ake at on e tim e d u rin g a low-level form at of a d rive was to ad ju st th e skew of th e d rive’s h ead s an d cylin d ers. Head skew is th e offset in logical sector n u m berin g between th e sam e p h ysical sectors on two tracks below ad jacen t h ead s of th e sam e cylin d er. Th e n u m ber of sectors skewed wh en switch in g from h ead to h ead with in a sin gle cylin d er

Hard Disk Drives

com p en sates for h ead switch in g an d con troller overh ead tim e. Cylinder skew is th e offset in logical sector n u m berin g between th e sam e p h ysical sectors on two ad jacen t tracks on two ad jacen t cylin d ers. Tod ay’s IDE an d SCSI d rives h ave th eir in terleave an d skew factors set to th eir op tim u m valu es by th e m an u factu rer. In m ost cases, you can n ot even ch an ge th ese valu es. In th e cases wh ere you can , th e m ost likely resu lt is d ecreased p erform an ce. For th is reason , m ost IDE d rive m an u factu rers recom m en d again st low-level form attin g th eir d rives. W ith som e IDE d rives, u n less you u se th e righ t software, you m igh t alter th e op tim u m skew settin gs an d slow d own th e d rive’s tran sfer rate. Drives th at u se Zon ed Bit Record in g can n ot ever h ave th e in terleave or skew factors ch an ged , an d as su ch , th ey are fu lly p rotected . No m atter h ow you try to form at th ese d rives, th e in terleave an d skew factors can n ot be altered . Shock M ount ing. Most h ard d isks m an u factu red tod ay h ave a shock-m ounted HDA, wh ich m ean s th at th ere is a ru bber cu sh ion p laced between th e d isk d rive bod y an d th e m ou n tin g ch assis. Som e d rives u se m ore ru bber th an oth ers, bu t for th e m ost p art, a sh ock m ou n t is a sh ock m ou n t. Som e d rives d o n ot h ave a sh ock-isolated HDA d u e to p h ysical or cost con strain ts. Be su re th at th e d rive you are u sin g h as ad eq u ate sh ockisolation m ou n ts for th e HDA, esp ecially if you are u sin g th e d rive in a p ortable PC system or in a system u sed in a n on -office en viron m en t wh ere con d ition s m ay be less favorable. I u su ally n ever recom m en d a d rive th at lacks at least som e form of sh ock m ou n tin g. Cost . Th e cost of h ard d isk storage is con tin u ally fallin g an d can n ow be as little as 4 cen ts p er m egabyte or less. You can n ow p u rch ase a 4G IDE d rive for u n d er $170. Th at p laces th e valu e of th e 10M d rive I bou gh t in 1983 at abou t 42 cen ts. (Too bad th at I p aid $1,800 for it at th e tim e!) Of cou rse, th e cost of d rives con tin u es to fall, an d even tu ally, even 4 cen ts p er m egabyte will seem exp en sive. Becau se of th e low costs of d isk storage tod ay, n ot m an y d rives with cap acities of less th an 1G are even bein g m an u factu red . Capacit y. Th ere are fou r figu res com m on ly u sed in ad vertisin g d rive cap acity: ■ Un form atted cap acity, in m illion s of bytes ■ Form atted cap acity, in m illion s of bytes ■ Un form atted cap acity, in m egabytes ■ Form atted cap acity, in m egabytes Th e term form atted , in th ese figu res, refers to th e low-level (or p h ysical) form attin g of th e d rive. Most m an u factu rers of IDE an d SCSI d rives n ow rep ort on ly th e form atted cap acities becau se th ese d rives are d elivered p reform atted . Most of th e tim e, ad vertisem en ts an d sp ecification s refer to th e u n form atted or form atted cap acity in m illion s of bytes, becau se th ese figu res are larger th an th e sam e cap acity exp ressed in m egabytes. Th is situ ation gen erates a great d eal of con fu sion wh en th e u ser ru n s FDISK (wh ich

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rep orts total d rive cap acity in m egabytes) an d won d ers wh ere th e m issin g sp ace is. Th is q u estion can seem trou blin g. Fortu n ately, th e an swer is easy; it on ly in volves a little m ath to figu re it ou t. Perh ap s th e m ost com m on q u estion s I get are con cern in g “m issin g” d rive cap acity. Con sid er th e followin g exam p le: “I ju st in stalled a n ew W estern Digital AC2200 d rive, billed as 212M. W h en I en tered th e d rive p aram eters (989 cylin d ers, 12 h ead s, 35 sectors p er track), both th e BIOS Setu p rou tin e an d FDISK rep ort th e d rive as on ly 203M! W h at h ap p en ed to th e oth er 9M?” Th e an swer is on ly a few calcu lation s away. By m u ltip lyin g th e d rive sp ecification p aram eters, you get th is resu lt: Cylin d ers:

989

Head s:

12

Sectors p er track:

35

Bytes p er sector:

512

Total bytes (in m illion s):

212.67

Total m egabytes:

202.82

Th e resu lt figu res to a cap acity of 212.67 m illion bytes or 202.82 m egabytes. Drive m an u factu rers u su ally rep ort d rive cap acity in m illion s of bytes, becau se th ey resu lt in larger, m ore im p ressive sou n d in g n u m bers, alth ou gh you r BIOS an d th e FDISK p rogram u su ally rep ort th e cap acity in m egabytes. On e m egabyte eq u als 1,048,576 bytes (or 1,024K in wh ich each kilobyte is 1,024 bytes). So th e bottom lin e is th at, becau se th e sam e abbreviation s are often u sed for both m illion s of bytes an d m egabytes, th is 212.67M d rive also is a 202.82M d rive! On e ad d ition al item to n ote abou t th is p articu lar d rive is th at it is a Zon ed Bit Record in g d rive an d th e actu al p h ysical p aram eters are d ifferen t. Ph ysically, th is d rive h as 1,971 cylin d ers an d 4 h ead s; h owever, th e total n u m ber of sectors on th e d rive (an d , th erefore, th e cap acity) is th e sam e n o m atter h ow you tran slate th e p aram eters. Alth ou gh W estern Digital d oes n ot rep ort th e u n form atted cap acity of th is p articu lar d rive, u n form atted cap acity u su ally works ou t to be abou t 19% larger th an a d rive’s form atted cap acity. Th e Seagate ST-12550N Barracu d a 2G d rive, for exam p le, is ad vertised as h avin g th e followin g cap acities: Un form atted cap acity:

2,572.00 m illion bytes

Un form atted cap acity:

2,452.85 m egabytes

Form atted cap acity:

2,139.00 m illion bytes

Form atted cap acity:

2,039.91 m egabytes

Each of th ese fou r figu res is a correct an swer to th e q u estion “W h at is th e storage cap acity of th e d rive?” As you can see, h owever, th e n u m bers are very d ifferen t. In fact, th ere

Hard Disk Installation Procedures

is yet an oth er n u m ber you can u se. Divid e th e 2,039.91 m egabytes by 1,024, an d th e d rive’s cap acity is 1.99G! So wh en you are com p arin g or d iscu ssin g d rive cap acities, m ake su re th at you are workin g with a con sisten t u n it of m easu re, or you r com p arison s will be m ean in gless. Specific Recom m endat ions. If you are goin g to ad d a h ard d isk to a system tod ay, I can give you a few recom m en d ation s. For th e d rive in terface, th ere really are on ly two typ es to con sid er: ■ IDE (In tegrated Drive Electron ics) ■ SCSI (Sm all Com p u ter System In terface) SCSI offers great exp an d ability, cross-p latform com p atibility, h igh cap acity, p erform an ce, an d flexibility. IDE is less exp en sive th an SCSI an d also offers a very h igh -p erform an ce solu tion , bu t exp an sion , com p atibility, cap acity, an d flexibility are m ore lim ited wh en com p ared with SCSI. I u su ally recom m en d IDE for m ost p eop le for two reason s. First, th e in terface is alread y in tegrated in to virtu ally every m oth erboard an d BIOS sold tod ay. Secon d , m ost u sers will n ot n eed m ore cap acity th an th e fou r d evices su p p orted by th e stan d ard p rim ary an d secon d ary IDE in terfaces fou n d in m ost system s. SCSI offers ad d ition al p erform an ce p oten tial with a m u ltith read ed op eratin g system like W in d ows NT, as well as su p p ort for m ore d evices, bu t it also req u ires th e p u rch ase of a sep arate h ost ad ap ter card , wh ich is in ad d ition to th e h igh er cost for th e d rive itself.

Not e Note that the current IDE standard is ATA-4 (AT Attachment), otherwise loosely called Fast ATA or Enhanced IDE. SCSI-3 is the most current SCSI standard, which although not fully approved, is nearing completion.

Hard Disk Inst allat ion Procedures Th is section d escribes th e h ard d isk d rive in stallation p rocess, p articu larly th e con figu ration , p h ysical in stallation , an d form attin g of a h ard d isk d rive. To in stall a h ard d rive in a PC, you m u st p erform som e or all of th e followin g p roced u res: ■ Con figu re th e d rive ■ Con figu re th e h ost ad ap ter ■ Ph ysically in stall th e d rive ■ Con figu re th e system ■ Partition th e d rive ■ High -level form at th e d rive

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As you p erform th e setu p p roced u re, you m ay n eed to kn ow variou s d etails abou t th e h ard d isk d rive, th e h ost ad ap ter, an d th e system ROM BIOS, as well as m an y of th e oth er d evices in th e system . Th is in form ation u su ally ap p ears in th e variou s OEM m an u als th at com e with th ese d evices. Make su re wh en you p u rch ase th ese item s th at th e ven d or in clu d es th ese m an u als. (Man y ven d ors d o n ot in clu d e th e m an u als u n less you ask for th em .) For m ost eq u ip m en t sold tod ay, you will get en ou gh d ocu m en tation from th e ven d or or reseller of th e eq u ip m en t to en able you to p roceed . If you are like m e, h owever, an d wan t all th e tech n ical d ocu m en tation on th e d evice, you will wan t to con tact th e origin al m an u factu rer of th e d evice an d ord er th e tech n ical sp ecification m an u al. For exam p le, if you p u rch ase a system th at com es with a W estern Digital IDE h ard d isk, th e seller p robably will give you som e lim ited in form ation on th e d rive, bu t n ot n early th e am ou n t th at th e actu al W estern Digital tech n ical sp ecification m an u al p rovid es. To get th is d ocu m en tation , you h ave to call W estern Digital an d ord er it. Th e sam e ru le ap p lies for an y of th e oth er com p on en ts in m ost of th e system s sold tod ay. I fin d th e OEM tech n ical m an u als to be essen tial in p rovid in g th e h igh est level of tech n ical su p p ort p ossible. For referen ce, you can look u p th e h ard d isk m an u factu rer n am es in Ap p en d ix A, “Ven d or List,” an d you will fin d n u m bers to call for tech n ical su p p ort, as well as URLs for th eir W eb sites. Drive Configurat ion Before you p h ysically in stall a h ard d isk d rive in to th e com p u ter, you m u st be su re th at it is p rop erly con figu red . For an IDE d rive, th is gen erally m ean s d esign atin g th e d rive as a m aster or a slave, d ep en d in g on wh eth er th ere are oth er d evices in stalled in th e system . For SCSI d rives, you m u st set th e d evice’s SCSI ID an d p ossibly its SCSI bu s term in ation state. √√ These procedures are covered in “ The IDE Interface,” p. 610, and “ SCSI Drive Configuration,” p. 640

Host Adapt er Configurat ion Old er h ard d isk d rive typ es u sed sep arate d isk con troller card s th at you h ad to in stall in a bu s slot. Th e IDE an d SCSI h ard d isk d rives u sed in tod ay’s PCs h ave th e d isk con troller in tegrated in to th e d rive assem bly. For IDE d rives, th e I/ O in terface is n early always in tegrated in to th e system ’s m oth erboard , an d you con figu re th e in terface th rou gh th e system BIOS. Th ere is n o sep arate h ost ad ap ter, th erefore, if you h ave an IDE d rive you can p roceed to “Ph ysical In stallation ,” later in th is ch ap ter. SCSI d rives, h owever, u su ally req u ire a h ost ad ap ter card th at you m u st in stall in a bu s slot like an y oth er card . A few m oth erboard s h ave in tegrated SCSI ad ap ters, bu t th ese are rare. Con figu rin g a SCSI h ost ad ap ter card in volves settin g th e d ifferen t system resou rces th at th e ad ap ter req u ires. As with m ost exp an sion card s, a SCSI h ost ad ap ter will req u ire som e com bin ation of th e followin g system resou rces: ■ ROM ad d resses

Hard Disk Installation Procedures

■ In terru p t req u ests (IRQ) ■ DMA (Direct Mem ory Access) ch an n el (DRQ) ■ I/ O p ort ad d resses Not all ad ap ters u se every on e of th ese resou rces, bu t som e m ay u se th em all. In m ost cases, you m u st con figu re th ese resou rces so th ey are u n iq u e an d can n ot be sh ared with oth er d evices. For exam p le, if a d isk con troller is u sin g I/ O p ort ad d resses from 1F0 to 1F7h , n o oth er d evice in th e system can u se th ose ad d resses. W h en you in stall a h ost ad ap ter th at su p p orts Plu g an d Play in a system with a Plu g-an d Play BIOS an d op eratin g system , like W in d ows 9x, th e con figu ration p rocess is com p letely au tom atic. Th e com p u ter sets th e req u ired h ard ware resou rce settin gs to valu es th at d o n ot con flict with oth er d evices in th e com p u ter. If you r h ard ware or op eratin g system d oes n ot su p p ort Plu g an d Play, you h ave to m an u ally con figu re th e ad ap ter to u se th e ap p rop riate resou rces. Som e ad ap ters p rovid e software th at en ables you to recon figu re or ch an ge th e h ard ware resou rces, wh ile oth ers u se ju m p ers or DIP switch es. √√ See “ System Resources,” p. 270

Th e IDE in terface is p art of th e stan d ard PC BIOS, wh ich m akes it p ossible to boot from an IDE d rive. Th e BIOS p rovid es th e d evice d river fu n ction ality th at th e system n eed s to access th e d rive before an y files can be load ed from d isk. Th e SCSI in terface is n ot p art of th e stan d ard PC BIOS, so m ost SCSI h ost ad ap ters h ave th eir own ROM BIOS th at en ables SCSI d rives to fu n ction as boot d evices. Use of th e SCSI BIOS is u su ally op tion al. If you are n ot bootin g from a SCSI d rive, you can load a stan d ard d evice d river for you r op eratin g system to access th e SCSI d evices. Most h ost ad ap ters h ave DIP switch es th at you u se to en able or d isable SCSI BIOS su p p ort. In ad d ition to p rovid in g boot fu n ction ality, th e SCSI BIOS can p rovid e m an y oth er fu n ction s, in clu d in g an y or all of th e followin g: ■ Low-level form attin g ■ Drive-typ e (p aram eter) con trol ■ Host ad ap ter con figu ration ■ SCSI d iagn ostics ■ Su p p ort for n on stan d ard I/ O p ort ad d resses an d in terru p ts If th e ad ap ter’s on -board BIOS is en abled , it will u se sp ecific m em ory ad d ress sp ace in th e Up p er Mem ory Area (UMA). Th e UMA is th e top 384K in th e first m egabyte of system m em ory. Th e UMA is d ivid ed in to th ree areas of two 64K segm en ts each , with th e first an d last areas bein g u sed by th e vid eo-ad ap ter circu its an d th e m oth erboard BIOS,

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resp ectively. Segm en ts C000h an d D000h are reserved for u se by ad ap ter ROMs su ch as th ose fou n d on d isk con trollers or SCSI h ost ad ap ters.

Not e You must ensure that any adapters using space in these segments of the HM A (High M emory Area) do not overlap with another adapter that uses this space. No two adapters can share this memory space. M ost adapters have software, jumpers, or switches that can adjust the configuration of the board and change the addresses it uses to prevent conflict.

Physical Inst allat ion Th e p roced u re for th e p h ysical in stallation of a h ard d isk d rive is m u ch th e sam e as th at for in stallin g a flop p y d isk d rive. You m u st h ave th e correct screws, brackets, an d facep lates for th e sp ecific d rive an d system before you can in stall th e d rive. Som e com p u ter cases req u ire p lastic rails th at are secu red to th e sid es of a h ard d isk d rive so it can slid e in to th e p rop er p lace in th e system (see Figu re 12.12). W h en you p u rch ase a d rive, ven d ors often give you th e op tion to p u rch ase a kit as op p osed to th e bare d rive. For sligh tly m ore m on ey, th e kit in clu d es m ou n tin g rails, screws, an d often a ribbon cable th at you sh ou ld be able to u se in m ost system s. Be carefu l wh en p u rch asin g a SCSI d rive, h owever, as th e kit m ay in clu d e a h ost ad ap ter th at can ad d su bstan tially to th e p rice.

Screw holes Disk drive mounting rail

FIG. 12.12 A typ ical h ard d isk with m ou n tin g rails. If you can n ot p u rch ase a d rive kit, th ere are several com p an ies listed in Ap p en d ix A th at sp ecialize in d rive-m ou n tin g brackets, cables, an d oth er h ard ware accessories. Also, m an y n ewer after-m arket com p u ter cases h ave elim in ated th e n eed for d rive rails altogeth er by bu ild in g th e exp an sion slot itself to th e 3 1/ 2- or 5 1/ 4-in ch d rive sp ecification , en ablin g you to bolt th e n ew d rive d irectly to th e case itself. Most 3 1/ 2-in ch h ard d rives sold in boxed p ackagin g in retail ou tlets d o in clu d e th e m ou n tin g bracket req u ired to m ou n t a 3 1/ 2-in ch d rive in a 5 1/ 4-in ch bay (as sh own in Figu re 12.13).

Hard Disk Installation Procedures

Not e You should also note the length of the drive cable itself when you plan on adding a hard disk drive. It can be very annoying to assemble everything that you think you’ll need to install a drive, and then find that the drive cable is not long enough to reach the new drive location. You can try to reposition the drive to a location closer to the interface connector on the host adapter or motherboard, or just get a longer cable.

FIG. 12.13 A typ ical bracket u sed to m ou n t a 3 1/ 2-in ch d rive in a 5 1/ 4-in ch d rive bay. Th e bracket is screwed to th e d rive an d th en m ou n ted in th e bay by u sin g screws or rails as d eterm in ed by th e case. Differen t facep late, or bezel, op tion s are also available. Make su re th at you h ave th e correct bezel for you r ap p lication . Som e system s, for exam p le, d o n ot n eed a bezel; if th ere is a bezel on th e d rive, you m u st rem ove it.

Caut ion M ake sure you use only the screws that come with your new drive. M any drives come with a special short-length screw that can have the same size thread as other screws you might use in your system. If you use screws that are too long, they might protrude too far into the drive casing and cause problems.

Syst em Configurat ion On ce you r d rive is p h ysically in stalled , you can begin con figu rin g th e system to u se it. You h ave to p rovid e th e com p u ter with basic in form ation abou t th e d rive so th e system can access it an d boot from it. How you set an d store th is in form ation d ep en d s on th e typ e of d rive an d system you h ave. Stan d ard (IDE) setu p p roced u res ap p ly for m ost h ard d isks excep t SCSI d rives. SCSI d rives n orm ally follow a cu stom setu p p roced u re th at varies d ep en d in g on th e h ost ad ap ter th at you are u sin g. If you h ave a SCSI d rive, follow th e in stru ction s in clu d ed with th e h ost ad ap ter to con figu re th e d rives.

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Aut om at ic Drive Typing. For IDE d rives, virtu ally all n ew BIOS version s in tod ay’s PCs h ave au tom atic typ in g. Th e BIOS sen d s a sp ecial Id en tify Drive com m an d to all th e d evices con n ected to th e IDE in terface d u rin g th e system startu p seq u en ce, an d th e d rives are in telligen t en ou gh to resp on d with th e correct p aram eters. Th e BIOS th en au tom atically en ters th e p aram eter in form ation retu rn ed by th e d rive. Th is p roced u re elim in ates errors or con fu sion in p aram eter selection . However, even with au tom atic d rive typ in g, som e BIOSs will alert you th at you n eed to en ter th e system setu p p rogram an d con figu re th e d rive. In th ese situ ation s, ju st en ter th e system BIOS con figu ration u tility an d save th e settin gs th at th e BIOS h as d etected for th e d rive. You d on ’t n eed to en ter an y settin gs you rself. M anual Drive Typing. If you are d ealin g with a m oth erboard th at d oes n ot su p p ort au tom atic typ in g, you m u st en ter th e ap p rop riate d rive in form ation in th e system BIOS m an u ally. Th e BIOS h as a selection of p re-con figu red d rive typ es, bu t th ese are woefu lly ou td ated in m ost cases, p rovid in g su p p ort on ly for d rives h old in g a few h u n d red m egabytes or less. In n early every case, you will h ave to select th e u ser-d efin ed d rive typ e an d p rovid e valu es for th e followin g settin gs: ■ Cylin d ers ■ Head s ■ Sectors p er track ■ W rite p recom p en sation Th e valu es th at you u se for th ese settin gs sh ou ld be p rovid ed in th e d ocu m en tation for th e h ard d isk d rive, or m ay even be p rin ted on th e d rive itself. It’s a good id ea to ch eck for th ese settin gs an d write th em d own , becau se th ey m ay n ot be visible on ce you ’ve in stalled th e d rive in th e com p u ter. You sh ou ld also m ain tain a cop y of th ese settin gs in case you r system BIOS sh ou ld lose its d ata d u e to a battery failu re. On e of th e best p laces to store th is in form ation is in sid e th e com p u ter itself. Tap in g a n ote with vital settin gs like th ese to th e in sid e of th e case can be a lifesaver.

Not e The setup parameters for over 1,000 popular drive models are included in Appendix D, “ Technical Reference.” Additionally, there is a generic table of parameters included in the appendix that will work (although they may not work optimally) with any IDE drive up to 528M .

Dep en d in g on th e m aker an d th e version of you r system BIOS, th ere m ay be oth er settin gs to con figu re as well, su ch as wh at tran sfer m od e to u se, an d wh eth er or n ot th e BIOS sh ou ld u se Logical Block Ad d ressin g. √√ See “ Increased Drive Capacity,” p. 621

Hard Disk Installation Procedures

Form at t ing Prop er setu p an d form attin g are critical to a d rive’s p erform an ce an d reliability. Th is section d escribes th e p roced u res u sed to form at a h ard d isk d rive correctly. Use th ese p roced u res wh en you in stall a n ew d rive in a system or im m ed iately after you recover d ata from a h ard d isk th at h as been exh ibitin g p roblem s. Th ere are th ree m ajor step s in th e form attin g p rocess for a h ard d isk d rive su bsystem : 1. Low-level form attin g 2. Partition in g 3. High -level form attin g Low -Level Form at t ing. All n ew h ard d isk d rives are low-level form atted by th e m an u factu rer, an d you d o n ot h ave to p erform an oth er LLF before you in stall th e d rive. In fact, u n d er n orm al circu m stan ces, you sh ou ld n ot ever h ave to p erform a low-level form at on an IDE or SCSI d rive. Most m an u factu rers n o lon ger recom m en d th at you lowlevel form at an y IDE typ e d rive. Th is recom m en d ation h as been th e sou rce of som e m yth s abou t IDE. Man y p eop le say, for exam p le, th at you can n ot p erform a low-level form at on an IDE d rive, an d th at if you d o, you will d estroy th e d rive. Th is statem en t is u n tru e! W h at can h ap p en is th at you m ay lose th e op tim al h ead an d cylin d er skew factors for th e d rive th at were set by th e m an u factu rer, as well as th e m ap of d rive d efects. Th is situ ation is n ot good an d will d efin itely h ave a n egative effect on th e d rive’s p erform an ce, bu t you still can u se th e d rive with n o p roblem s. Desp ite th is recom m en d ation , h owever, th ere m ay be tim es wh en you m u st p erform a low-level form at on an IDE or SCSI d rive. Th e followin g section s d iscu ss th e software th at you can u se to d o th is. SCSI Lo w -Le v e l Fo rm a t So f t w a re . If you are u sin g a SCSI d rive, you m u st u se th e LLF p rogram p rovid ed by th e m an u factu rer of th e SCSI h ost ad ap ter. Th e d esign of th ese d evices varies en ou gh th at a register-level p rogram can work on ly if it is tailored to th e in d ivid u al con troller. Fortu n ately, all SCSI h ost ad ap ters in clu d e low-level form at software, eith er in th e h ost ad ap ter’s BIOS or in a sep arate d isk-based p rogram . Th e in terface to th e SCSI d rive is th rou gh th e h ost ad ap ter. SCSI is a stan d ard , bu t th ere are n o tru e stan d ard s for wh at a h ost ad ap ter is su p p osed to look like. Th is m ean s th at an y form attin g or con figu ration software will be sp ecific to a p articu lar h ost ad ap ter.

Not e Notice that SCSI format and configuration software is keyed to the host adapter and is not specific in any way to the particular SCSI hard disk drive that you are using.

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ID E Lo w -Le v e l Fo rm a t So f t w a re . IDE d rive m an u factu rers h ave d efin ed exten sion s to th e stan d ard W D1002/ 1003 AT in terface, wh ich was fu rth er stan d ard ized for IDE d rives as th e ATA (AT Attach m en t) in terface. Th e ATA sp ecification p rovid es for ven d oru n iq u e com m an d s, wh ich are m an u factu rer p rop rietary exten sion s to th e stan d ard . To p reven t im p rop er low-level form attin g, m an y of th ese IDE d rives h ave sp ecial cod es th at m u st be sen t to th e d rive to u n lock th e form at rou tin es. Th ese cod es vary am on g m an u factu rers. If p ossible, you sh ou ld obtain LLF an d d efect-m an agem en t software from th e d rive m an u factu rer; th is software u su ally is sp ecific to th at m an u factu rer’s p rod u cts. Most ATA IDE d rives are p rotected from an y alteration to th e skew factors or d efect m ap erasu re becau se th ey are in a tran slated m od e. Zon ed Bit Record in g d rives are always in tran slation m od e an d are fu lly p rotected . Most ATA d rives h ave a cu stom com m an d set th at m u st be u sed in th e form at p rocess; th e stan d ard form at com m an d s d efin ed by th e ATA sp ecification u su ally d o n ot work, esp ecially with in telligen t or Zon ed Bit Record in g IDE d rives. W ith ou t th e p rop er m an u factu rer-sp ecific form at com m an d s, you can ’t p erform th e d efect m an agem en t by th e m an u factu rer-sp ecified m eth od , in wh ich bad sectors often can be sp ared . If form attin g software is n ot available from you r d rive’s m an u factu rer, I recom m en d Disk Man ager by On track, as well as th e MicroScop e p rogram by Micro 2000. Th ese p rogram s can form at m an y IDE d rives becau se th ey kn ow th e m an u factu rer-sp ecific IDE form at com m an d s an d rou tin es. Th ey also can p erform d efect-m ap p in g an d su rface-an alysis p roced u res. No n d e st ru c t i v e Fo rm a t t e rs. Gen eral-p u rp ose, BIOS-level, n on d estru ctive form atters, su ch as Calibrate an d Sp in Rite, are n ot recom m en d ed in m ost situ ation s wh ere a real LLF is req u ired . Th ese p rogram s h ave several lim itation s an d p roblem s th at lim it th eir effectiven ess; in som e cases, th ey can even cau se p roblem s with th e way th at d efects are h an d led on a d rive. Th ese p rogram s attem p t to p erform a track-by-track LLF by u sin g BIOS fu n ction s, wh ile backin g u p an d restorin g th e track d ata as th ey go. Th ese p rogram s d o n ot actu ally p erform a com p lete LLF, becau se th ey d o n ot even try to low-level form at th e first track (Cylin d er 0, Head 0) d u e to p roblem s with som e con troller typ es th at store h id d en in form ation on th e first track. Th ese p rogram s also d o n ot p erform d efect m ap p in g in th e way th at stan d ard LLF p rogram s d o, an d th ey can even rem ove th e carefu lly ap p lied sector h ead er d efect m arks d u rin g a p rop er LLF. Th is situ ation p oten tially allows d ata to be stored in sectors th at origin ally were m arked d efective an d m ay actu ally void th e m an u factu rer’s warran ty on som e d rives. An oth er p roblem is th at th ese p rogram s on ly work on d rives th at h ave alread y been form atted an d can form at on ly d rives th at are form attable th rou gh BIOS fu n ction s. A tru e LLF p rogram byp asses th e system BIOS an d sen d s com m an d s d irectly to th e d isk con troller h ard ware. For th is reason , m an y LLF p rogram s are sp ecific to th e d isk con troller h ard ware for wh ich th ey are d esign ed . It is virtu ally im p ossible to h ave a sin gle form at p rogram th at will ru n on all d ifferen t typ es of con trollers. Man y h ard d rives h ave

Hard Disk Installation Procedures

been in correctly d iagn osed as bein g d efective becau se th e wron g form at p rogram was u sed an d th e p rogram d id n ot op erate p rop erly. Drive Part it ioning w it h FDISK. Partitioning a h ard d isk is th e act of d efin in g areas of th e d isk for an op eratin g system to u se as a volu m e. W h en you p artition a d isk, th e p artition in g software writes a m aster p artition boot sector at cylin d er 0, h ead 0, sector 1—th e first sector on th e h ard d isk. Th is sector con tain s d ata th at d escribes th e p artition s by th eir startin g an d en d in g cylin d er, h ead , an d sector location s. Th e p artition table also in d icates to th e ROM BIOS wh ich of th e p artition s is bootable an d , th erefore, wh ere to look for an op eratin g system to load . ◊◊ See “ File Systems and Data Recovery,” p. 1065

Th e FDISK p rogram is th e accep ted stan d ard for p artition in g h ard d isk d rives for u se with all version s of W in d ows 9x an d DOS. Partition in g p rep ares th e boot sector of th e d isk in su ch a way th at th e FORMAT.COM p rogram or th e W in d ows GUI Form at u tility can op erate correctly. FDISK also m akes it p ossible for d ifferen t op eratin g system s to coexist on a sin gle h ard d isk. High-Level ( Operat ing-Syst em ) Form at t ing. Th e fin al step in th e in stallation of a h ard d isk d rive is th e h igh -level form at. Like th e p artition in g p rocess, th e h igh -level form at is sp ecific to th e file system you ’ve ch osen to u se on th e d rive. On W in d ows 9x an d DOS system s, th e p rim ary fu n ction of th e h igh -level form at is to create a FAT an d a d irectory system on th e d isk so th e op eratin g system can m an age files. Usu ally, you p erform th e h igh -level form at with th e FORMAT.COM p rogram or th e form attin g u tility in W in d ows 9x Exp lorer. FORMAT.COM u ses th e followin g syn tax: FORMAT C: /S /V

Th is com m an d h igh -level form ats d rive C, writes th e h id d en op eratin g-system files in th e first p art of th e p artition , an d p rom p ts for th e en try of a volu m e label to be stored on th e d isk at th e com p letion of th e p rocess. Th e FAT h igh -level form at p rogram p erform s th e followin g fu n ction s an d p roced u res: 1. Scan s th e d isk (read on ly) for tracks an d sectors m arked as bad d u rin g th e LLF, an d n otes th ese tracks as bein g u n read able. 2. Retu rn s th e d rive h ead s to th e first cylin d er of th e p artition , an d at th at cylin d er (h ead 1, sector 1) writes a DOS volu m e boot sector. 3. W rites a FAT at h ead 1, sector 2. Im m ed iately after th is FAT, it writes a secon d cop y of th e FAT. Th ese FATs essen tially are blan k excep t for bad -clu ster m arks n otin g areas of th e d isk th at were fou n d to be u n read able d u rin g th e m arked -d efect scan . 4. W rites a blan k root d irectory.

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5. If th e /S p aram eter is sp ecified , cop ies th e system files, IO.SYS an d MSDOS.SYS (or IBMBIO.COM an d IBMDOS.COM, d ep en d in g on wh ich DOS you ru n ) an d COMMAND.COM to th e d isk (in th at ord er). 6. If th e /V p aram eter is sp ecified , p rom p ts th e u ser for a volu m e label, wh ich is written as th e fou rth file en try in th e root d irectory. Now, th e op eratin g system can u se th e d isk for storin g an d retrievin g files, an d th e d isk is a bootable d isk. Du rin g th e first p h ase of th e h igh -level form at, th e p rogram p erform s a m arked d efect scan . Defects m arked by th e LLF op eration sh ow u p d u rin g th is scan as bein g u n read able tracks or sectors. W h en th e h igh -level form at en cou n ters on e of th ese areas, it au tom atically p erform s u p to five retries to read th ese tracks or sectors. If th e u n read able area was m arked by th e LLF, th e read fails on all attem p ts. After five retries, th e DOS FORMAT p rogram gives u p on th is track or sector an d m oves to th e n ext on e. Areas th at rem ain u n read able after th e in itial read an d th e five retries are n oted in th e FAT as bein g bad clu sters. Hard Disk Drive Troubleshoot ing and Repair If a h ard d isk d rive h as a p roblem in sid e its sealed HDA, rep airin g th e d rive u su ally is n ot feasible. If th e failu re is in th e logic board , you can rep lace th at assem bly with a n ew or rebu ilt assem bly easily an d at a m u ch lower cost th an rep lacin g th e en tire d rive. Most h ard d isk p roblem s really are n ot h ard ware p roblem s; in stead , th ey are soft p roblem s th at can be solved by a n ew LLF an d d efect-m ap p in g session . Soft problem s are ch aracterized by a d rive th at sou n d s n orm al bu t p rod u ces variou s read an d write errors. Hard problem s are m ech an ical, su ch as wh en th e d rive sou n d s as th ou gh it con tain s loose m arbles. Con stan t scrap in g an d grin d in g n oises from th e d rive, with n o read in g or writin g cap ability, also q u alify as h ard errors. In th ese cases, it is u n likely th at an LLF will p u t th e d rive back in to service. If a h ard ware p roblem is in d icated , first rep lace th e logicboard assem bly. You can m ake th is rep air you rself an d , if su ccessfu l, you can recover th e d ata from th e d rive. If rep lacin g th e logic assem bly d oes n ot solve th e p roblem , con tact th e m an u factu rer or a sp ecialized rep air sh op th at h as clean -room facilities for h ard d isk rep air. (See Ap p en d ix A for a list of d rive m an u factu rers an d com p an ies th at sp ecialize in h ard d isk d rive rep air.)

Floppy Disk Drives Th is section exam in es flop p y d isk d rives an d d isks. It exp lores h ow flop p y d isk d rives an d d isks fu n ction , wh at typ es of d isk d rives an d d isks are available, an d h ow to p rop erly in stall an d service d rives an d d isks.

Floppy Disk Drives

Developm ent of t he Floppy Disk Drive Alan Sh u gart is gen erally cred ited with in ven tin g th e flop p y d isk d rive in 1967 wh ile workin g for IBM. On e of Sh u gart’s sen ior en gin eers, David Noble, actu ally p rop osed th e flexible m ed ia (th en 8 in ch es in d iam eter) an d th e p rotective jacket with th e fabric lin in g. Sh u gart left IBM in 1969, an d in 1974, h is com p an y, Sh u gart Associates, in trod u ced th e m in i-flop p y (5 1/ 4-in ch ) d isk d rive, wh ich , of cou rse, becam e th e stan d ard even tu ally u sed by p erson al com p u ters, rap id ly rep lacin g th e 8-in ch d rives. He also h elp ed create th e Sh u gart Associates System In terface (SASI), wh ich was later ren am ed SCSI (Sm all Com p u ter System In terface) wh en ap p roved as an ANSI stan d ard . Sh u gart left Sh u gart Associates in 1974 an d togeth er with Fin is Con n er form ed Seagate Tech n ology in 1978. At Seagate, h e created th e ST-506/ 412 in terface, wh ich becam e th e d e facto stan d ard PC h ard d isk in terface, an d wh ich also served as th e basis for th e later ESDI an d even th e IDE in terface. Seagate wen t on to becom e th e world ’s largest m an u factu rer of h ard d isk d rives. Note th at all PC flop p y d isk d rives are still based on (an d m ostly com p atible with ) th e origin al Sh u gart d esign s. Com p ared to oth er p arts of th e PC, th e flop p y d isk d rive h as u n d ergon e relatively few ch an ges. Drive Com ponent s Th is section d escribes th e com p on en ts th at m ake u p a typ ical flop p y d isk d rive an d exam in es h ow th ese com p on en ts op erate togeth er to read an d write d ata—th e p h ysical op eration of th e d rive. All flop p y d isk d rives, regard less of typ e, con sist of several basic com m on com p on en ts. To p rop erly in stall an d service a d isk d rive, you m u st be able to id en tify th ese com p on en ts an d u n d erstan d th eir fu n ction (see Figu re 12.14). Read/ W rit e Heads. A flop p y d isk d rive n orm ally h as two read / write h ead s, on e for each sid e of th e d isk, with both h ead s bein g u sed for read in g an d writin g on th eir resp ective d isk sid es (see Figu re 12.15). At on e tim e, sin gle-sid ed d rives were available for PC system s (th e origin al PC h ad su ch d rives), bu t tod ay sin gle-sid ed d rives are a fad in g m em ory.

Not e M any people do not realize that the first head on a floppy disk drive is the bottom one. Singlesided drives, in fact, used only the bottom head; the top head was replaced by a felt pressure pad. Another bit of disk trivia is that the top head (Head 1) is not directly over the bottom head (Head 0)—the top head is located either four or eight tracks inward from the bottom head, depending on the drive type.

Th e h ead m ech an ism is m oved by a m otor called a head actuator. Th e h ead s can m ove in an d ou t over th e su rface of th e d isk in a straigh t lin e to p osition th em selves over variou s tracks. Th e h ead s m ove in an d ou t tan gen tially to th e tracks th at th ey record on th e d isk. Becau se th e top an d bottom h ead s are m ou n ted on th e sam e rack, or m ech an ism , th ey m ove in u n ison an d can n ot m ove in d ep en d en tly of each oth er. Th e h ead s are m ad e of soft ferrou s (iron ) com p ou n d s with electrom agn etic coils. Each h ead is a com p osite d esign , with a read / write h ead cen tered with in two tu n n el-erase h ead s in th e sam e p h ysical assem bly (see Figu re 12.16).

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Chapter 12—M agnetic Storage

drive cover

head actuator left and right disk guide stepper motor spring loaded access door

4

2Z4

772

read/write head

disk ejector screw mounting holes

faceplate/bezel LED window

controller connector disk eject button spring loaded disk catch write protect sensor power connector activity LED

interface circuit board spindle media type sensor

drive motor magnet (motor coil is hidden under spindle)

FIG. 12.14 A typ ical flop p y d isk d rive.

Read/write head (Side 1)

Read/write head (Side 0)

FIG. 12.15 A d ou ble-sid ed d rive h ead assem bly.

Head carriage assembly (double sided)

Floppy Disk Drives

Head assembly

Read/Write head

Direction of head travel over a track

Tunnel–erase head

FIG. 12.16 Com p osite con stru ction of a typ ical flop p y d isk d rive h ead . Flop p y d isk d rives u se a record in g m eth od called tunnel erasure. As th e d rive writes to a track, th e trailin g tu n n el-erase h ead s erase th e ou ter ban d s of th e track, trim m in g it clean ly on th e d isk. Th e h ead s force th e d ata in to a sp ecified n arrow “tu n n el” on each track. Th is p rocess p reven ts th e sign al from on e track from bein g con fu sed with th e sign als from ad jacen t tracks, wh ich wou ld h ap p en if th e sign al were allowed to n atu rally “tap er off” to each sid e. Alignm ent is th e p lacem en t of th e h ead s with resp ect to th e tracks th ey m u st read an d write. Head align m en t can be ch ecked on ly again st som e sort of referen ce-stan d ard d isk record ed by a p erfectly align ed m ach in e. Th ese typ es of d isks are available, an d you can u se on e to ch eck you r d rive’s align m en t. However, th is is u su ally n ot p ractical for th e en d u ser, becau se on e calibrated an alog align m en t d isk can cost m ore th an a n ew d rive. Th e flop p y d isk d rive’s two h ead s are sp rin g-load ed an d p h ysically grip th e d isk with a sm all am ou n t of p ressu re, wh ich m ean s th at th ey are in d irect con tact with th e d isk su rface wh ile read in g an d writin g to th e d isk. Becau se flop p y d isk d rives sp in at on ly 300 or 360 RPM, th is p ressu re d oes n ot p resen t an excessive friction p roblem . Som e n ewer d isks are sp ecially coated with Teflon or oth er com p ou n d s to fu rth er red u ce friction an d en able th e d isk to slid e m ore easily u n d er th e h ead s. Becau se of th e con tact between th e h ead s an d th e d isk, a bu ild u p of th e m agn etic m aterial from th e d isk even tu ally form s on th e h ead s. Th e bu ild u p sh ou ld p eriod ically be clean ed off th e h ead s as p art of a p reven tive-m ain ten an ce or n orm al service p rogram . To read an d write to th e d isk p rop erly, th e h ead s m u st be in d irect con tact with th e m agn etic m ed iu m . Very sm all p articles of loose oxid e, d u st, d irt, sm oke, fin gerp rin ts, or h air can cau se p roblem s with read in g an d writin g th e d isk. Disk an d d rive m an u factu rers’ tests h ave fou n d th at a sp acin g as little as .000032 in ch (32 m illion th s of an in ch ) between th e h ead s an d th e m ed iu m can cau se read / write errors. You n ow can u n d erstan d

773

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Chapter 12—M agnetic Storage

wh y it is im p ortan t to h an d le d isks carefu lly an d avoid tou ch in g or con tam in atin g th e su rface of th e d isk m ed iu m in an y way. Th e rigid jacket an d p rotective sh u tter for th e h ead access ap ertu re on 3 1/ 2-in ch d isks is excellen t for p reven tin g p roblem s cau sed by con tam in ation . 5 1/ 4-in ch d isks d o n ot h ave th e sam e p rotective elem en ts, wh ich is on e reason wh y th ey h ave fallen in to d isu se. If you still u se 5 1/ 4-in ch flop p y d isks, you sh ou ld exercise m ore care in th eir h an d lin g. The Head Act uat or. Th e head actuator for a flop p y d isk d rive u ses a sp ecial kin d of m otor, a stepper m otor, th at m oves in both d irection s in an in crem en t called a step. Th is typ e of m otor d oes n ot sp in arou n d con tin u ou sly; rath er, th e m otor tu rn s a p recise sp ecified d istan ce an d stop s. Step p er m otors are n ot in fin itely variable in th eir p osition in g; th ey m ove in fixed in crem en ts, or detents, an d m u st stop at a p articu lar d eten t p osition . Th e location of each track on th e d isk is d efin ed by on e or m ore in crem en ts of th e m otor’s m otion . Th e d isk con troller can in stru ct th e m otor to p osition itself accord in g to an y relative in crem en t with in th e ran ge of its travel. To p osition th e h ead s at track 25, for exam p le, th e con troller in stru cts th e m otor to go to th e 25th d eten t p osition . Th e step p er m otor can be lin ked to th e h ead rack in on e of two ways. In th e first, th e lin k is a coiled , sp lit-steel ban d . Th e ban d win d s an d u n win d s arou n d th e sp in d le of th e step p er m otor, tran slatin g th e rotary m otion in to lin ear m otion . Som e d rives, h owever, u se a worm -gear arran gem en t rath er th an a ban d . In th is typ e of d rive, th e h ead assem bly rests on a worm gear d riven d irectly off th e step p er m otor sh aft. Becau se th is arran gem en t is m ore com p act, you n orm ally fin d worm -gear actu ators on th e sm aller 3 1/ 2-in ch d rives. Most step p er m otors u sed in flop p y d isk d rives can step in sp ecific in crem en ts th at relate to th e track sp acin g on th e d isk. Old er 48 Track Per In ch (TPI) d rives h ave a m otor th at step s in in crem en ts of 3.6°. Th is m ean s th at each 3.6° of step p er m otor rotation m oves th e h ead s from on e track to th e n ext. Most 96 or 135 TPI d rives h ave a step p er m otor th at m oves in 1.8° in crem en ts, wh ich is exactly h alf of wh at th e 48 TPI d rives u se. Som etim es you see th is in form ation actu ally p rin ted or stam p ed righ t on th e step p er m otor itself, wh ich is u sefu l if you are tryin g to figu re ou t wh at typ e of d rive you h ave. 5 1/ 4in ch 360K d rives were th e on ly 48 TPI d rives th at u sed th e 3.6° in crem en t step p er m otor. All oth er d rive typ es n orm ally u se th e 1.8° step p er m otor. On m ost d rives, th e step p er m otor is a sm all cylin d rical object n ear on e corn er of th e d rive. A step p er m otor u su ally h as a fu ll travel tim e of abou t 1/ 5 of a secon d —abou t 200m s. On average, a h alf-stroke is 100m s, an d a on e-th ird stroke is 66m s. Th e tim in g of a on e-h alf or on e-th ird stroke of th e h ead -actu ator m ech an ism is often u sed to d eterm in e th e rep orted average-access tim e for a d isk d rive. Average-access tim e is th e n orm al am ou n t of tim e th e h ead s sp en d m ovin g at ran d om from on e track to an oth er. The Spindle M ot or. Th e spindle m otor sp in s th e d isk. Th e n orm al sp eed of rotation is eith er 300 or 360 RPM, d ep en d in g on th e typ e of d rive. Th e 5 1/ 4-in ch h igh -d en sity (HD) d rive is th e on ly d rive th at sp in s at 360 RPM; all oth ers, in clu d in g th e 5 1/ 4-in ch d ou ble-d en sity (DD), 3 1/ 2-in ch DD, 3 1/ 2-in ch HD, an d 3 1/ 2-in ch extra-h igh d en sity (ED) d rives, sp in at 300 RPM. Th is is q u ite a slow sp eed wh en com p ared to a h ard d isk

Floppy Disk Drives

d rive, wh ich h elp s to exp lain wh y flop p y d isk d rives h ave m u ch lower d ata tran sfer rates. However, th is slow sp eed also m akes it p ossible for th e d rive h ead s to be in p h ysical con tact with th e d isk wh ile it is sp in n in g, with ou t cau sin g friction d am age. Most earlier d rives u sed a m ech an ism by wh ich th e sp in d le m otor p h ysically tu rn ed th e d isk sp in d le with a belt, bu t all m od ern d rives u se a d irect-d rive system with n o belts. Th e d irect-d rive system s are m ore reliable an d less exp en sive to m an u factu re, as well as sm aller in size. Th e earlier belt-d riven system s d id h ave m ore rotation al torq u e available to tu rn a sticky d isk becau se of th e torq u e m u ltip lication factor of th e belt system . Most n ewer d irect-d rive system s u se an au tom atic torq u e-com p en sation cap ability th at au tom atically sets th e d isk-rotation sp eed to a fixed 300 or 360 RPM, an d com p en sates with ad d ition al torq u e for sticky d isks or less torq u e for slip p ery on es. Th is arran gem en t elim in ates th e n eed to ad ju st th e rotation al sp eed of th e d rive. Circuit Boards. A d isk d rive always in corp orates on e or m ore logic boards, wh ich are circu it board s th at con tain th e circu itry u sed to con trol th e h ead actu ator, read / write h ead s, sp in d le m otor, d isk sen sors, an d oth er com p on en ts on th e d rive. Th e logic board im p lem en ts th e d rive’s in terface to th e con troller board in th e system u n it. Th e stan d ard in terface u sed by all PC flop p y d isk d rives is th e Sh u gart Associates SA-400 in terface, wh ich was in ven ted in th e 1970s an d is based on th e NEC 765 con troller ch ip . Th is in d u stry-stan d ard in terface is wh y you can p u rch ase “off-th e-sh elf” d rives (raw, or bare, d rives) th at can p lu g d irectly in to you r con troller.

Tip Logic boards for a drive can fail and usually are difficult to obtain as a spare part. One board often costs more than replacing the entire drive. I recommend keeping failed or misaligned drives that might otherwise be discarded so they can be used for their remaining good parts—such as logic boards. You can use the parts to restore a failing drive very cost-effectively.

The Cont roller. At on e tim e, th e con troller for a com p u ter’s flop p y d isk d rives took th e form of a d ed icated exp an sion card in stalled in an ISA bu s slot. Later im p lem en tation s u sed a m u ltifu n ction card th at p rovid ed th e IDE/ ATA, p arallel, an d serial p ort in terfaces in ad d ition to th e flop p y d isk d rive con troller. Tod ay’s PCs h ave th e flop p y con troller in tegrated in to th e m oth erboard , u su ally in th e form of a Su p er I/ O ch ip th at also in clu d es th e p arallel an d serial in terfaces. Un like th e m oth erboard ’s IDE in terface, th e flop p y d isk con troller h as n ot ch an ged very m u ch in recen t years. Virtu ally th e on ly th in g th at h as ch an ged is th e con troller’s m axim u m sp eed . As th e d ata d en sity of flop p y d isks (an d th eir cap acity) h as in creased over th e years, th e con troller sp eed h as h ad to in crease, as well. Nearly all flop p y d isk con trollers in com p u ters tod ay su p p ort sp eed s of u p to 1Mbit/ sec, wh ich su p p orts all th e stan d ard flop p y d isk d rives. 500Kbit/ sec con trollers can su p p ort all flop p y d isk d rives excep t for th e 2.88M extra-h igh d en sity m od els. Old er com p u ters u sed 250Kbit/ sec con trollers th at cou ld su p p ort on ly 360K 5 1/ 4-in ch an d 720K 3 1/ 2-in ch d rives. To in stall a

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Chapter 12—M agnetic Storage

stan d ard 1.44M 3 1/ 2-in ch d rive in an old er m ach in e, you m ay h ave to rep lace th e flop p y con troller with a faster m od el.

Tip The best way to determine the speed of the floppy disk drive controller in your computer is to examine the floppy disk drive options provided by the system BIOS.

Even if you d o n ot in ten d to u se a 2.88M flop p y d isk d rive, you still m ay wan t to m ake su re th at you r com p u ter h as th e fastest p ossible con troller. Som e of th e tap e d rives on th e m arket u se th e flop p y d isk in terface to con n ect to th e system , an d in th is case th e con troller h as a p rofou n d effect on th e overall th rou gh p u t of th e d rive. The Faceplat e. Th e faceplate, or bezel, is th e p lastic p iece th at com p rises th e fron t of th e d rive. Th ese p ieces, u su ally rem ovable, com e in d ifferen t colors an d con figu ration s. Most d rives u se a bezel th at is sligh tly wid er th an th e d rive. You h ave to in stall th ese typ es of d rives from th e fron t of a system becau se th e facep late is sligh tly wid er th an th e h ole in th e com p u ter case. Oth er d rive facep lates are th e sam e wid th as th e d rive’s ch assis; you can in stall th ese d rives from th e rear—an ad van tage in som e cases.

+12

Gnd

Gnd

+5

Black

Black

Red

Connect ors. Nearly all flop p y d isk d rives h ave two con n ectors—on e for p ower to ru n th e d rive, an d th e oth er to carry th e con trol an d d ata sign als to an d from th e d rive. Th ese con n ectors are fairly stan d ard ized in th e com p u ter in d u stry; a fou r-p in in -lin e con n ector (called Mate-N-Lock, by AMP), in both a large an d sm all style, is u sed for p ower (see Figu re 12.17); an d a 34-p in con n ector in both ed ge an d p in h ead er d esign s is u sed for th e d ata an d con trol sign als. 5 1/ 4-in ch d rives n orm ally u se th e large style p ower con n ector an d th e 34-p in ed ge typ e con n ector, wh ile m ost 3 1/ 2-in ch d rives u se th e sm aller version of th e p ower con n ector an d th e 34-p in h ead er typ e logic con n ector. Th e d rive con troller an d logic con n ectors an d p in ou ts are d etailed later in th is ch ap ter as well as in Ap p en d ix A. Yellow

776

1

2

3

4

FIG. 12.17 A d isk d rive fem ale p ower su p p ly cable con n ector. Both th e large an d sm all p ower con n ectors from th e p ower su p p ly are fem ale p lu gs. Th ey p lu g in to th e m ale p ortion , wh ich is attach ed to th e d rive itself. On e com m on p roblem with u p grad in g an old er system with 3 1/ 2-in ch d rives is th at you r p ower su p p ly on ly h as th e large style con n ectors, wh ile th e d rive h as th e sm all style. An ad ap ter cable is

Floppy Disk Drives

available from Rad io Sh ack (Cat. No. 278-765) an d oth er sou rces th at con verts th e largestyle p ower con n ector to th e p rop er sm all style u sed on m ost 3 1/ 2-in ch d rives. Most stan d ard PCs u se 3 1/ 2-in ch d rives with a 34-p in sign al con n ector an d a sep arate sm all-style p ower con n ector. For old er system s, m an y d rive m an u factu rers also sell 3 1/ 2in ch d rives in stalled in a 5 1/ 4-in ch fram e assem bly with a sp ecial ad ap ter bu ilt in th at en ables you to u se th e larger p ower con n ector an d stan d ard ed ge-typ e sign al con n ectors. Becau se n o cable ad ap ters are req u ired an d th ey in stall in a 5 1/ 4-in ch h alf-h eigh t bay, th ese typ es of d rives are id eal for u p grad in g earlier system s. Most 3 1/ 2-in ch d riveu p grad e kits sold tod ay are sim ilar an d in clu d e th e d rive, ap p rop riate ad ap ters for th e p ower an d con trol an d d ata cables, a 5 1/ 4-in ch fram e ad ap ter an d facep late, an d m ou n tin g rails. Th e fram e ad ap ter an d facep late en able you to in stall th e d rive wh ere a 5 1/ 4in ch h alf-h eigh t d rive wou ld n orm ally go. The Floppy Disk Drive Cable. Th e 34-p in con n ector on a flop p y d isk d rive takes th e form of eith er an ed ge con n ector (on 5 1/ 4-in ch d rives) or a p in con n ector (on 3 1/ 2in ch d rives). Th e p in ou ts for th e con n ector are sh own in Table 12.9. Table 12.9

Pinout s for t he St andard Floppy Disk Drive Connect or

Pin

Signal

Pin

Signal

1

Ground

18

Direction (Stepper M otor)

2

Unused

19

Ground

3

Ground

20

Step Pulse

4

Unused

21

Ground

5

Ground

22

Write Data

6

Unused

23

Ground

7

Ground

24

Write Enable

8

Index

25

Ground

9

Ground

26

Track 0

10

M otor Enable A

27

Ground

11

Ground

28

Write Protect

12

Drive Select B

29

Ground

13

Ground

30

Read Data

14

Drive Select A

31

Ground

15

Ground

32

Select Head 1

16

M otor Enable B

33

Ground

17

Ground

34

Ground

Th e cable u sed to con n ect th e flop p y d isk d rive(s) to th e con troller on th e m oth erboard is q u ite stran ge. To su p p ort variou s d rive con figu ration s, th e cable typ ically h as five con n ectors on it, two ed ge con n ectors an d two p in con n ectors to attach to th e d rives, an d on e p in con n ector to con n ect to th e con troller. Th e cable h as red u n d an t con n ectors for each of th e two d rives (A an d B) su p p orted by th e stan d ard flop p y d isk d rive con troller, so you can in stall an y com bin ation of 5 1/ 4-in ch an d 3 1/ 2-in ch d rives (see Figu re 12.18).

777

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Chapter 12—M agnetic Storage

Motherboard Connector

5.25" Drive “B” Connector

Pin 34

“Twist” Pin 1 (Colored Wire)

3.5" Drive “A” Connector

3.5" Drive “B” Connector

5.25" Drive “A” Connector

FIG. 12.18 Stan d ard five-con n ector flop p y in terface cable. In ad d ition to th e con n ectors, th e cable on m ost system s h as a sp ecial twist th at in verts th e sign als of wires 10 th rou gh 16. Th ese are th e wires carryin g th e Drive Select an d Motor En able sign als for each of th e two d rives. Flop p y d isk d rives h ave DS (Drive Select) ju m p ers th at were d esign ed to en able you to select wh eth er a given d rive sh ou ld be recogn ized as A or B. You m ay n ot even kn ow th at th ese ju m p ers exist, becau se th e twist in th e cable p reven ts you from h avin g to ad ju st th em . W h en in stallin g two flop p y d isk d rives in on e system (ad m itted ly a rarity n owad ays), th e cable electrically ch an ges th e DS con figu ration of th e d rive th at is p lu gged in after th e twist. Th u s, th e twist cau ses a d rive p h ysically set to th e secon d DS p osition (B) to ap p ear to th e con troller to be set to th e first DS p osition (A) an d vice versa. Th e ad op tion of th is cable h as m ad e it p ossible to u se a stan d ard ju m p er con figu ration for all flop p y d isk d rives, regard less of wh eth er you in stall on e or two d rives in a com p u ter. If you in stall on ly a sin gle flop p y d isk d rive, you u se th e con n ector after th e twist, wh ich will cau se th e d rive to be recogn ized as d rive A. Disk Physical Specificat ions and Operat ion Most of th e PCs sold tod ay are eq u ip p ed with a 3 1/ 2-in ch 1.44M flop p y d isk d rive. You m ay ru n in to an old er system th at h as a 5 1/ 4-in ch 1.2M d rive in stead of, or in ad d ition to, th e 3 1/ 2-in ch d rive. Th ere are also PC system s th at h ave a 2.88M 3 1/ 2-in ch d rive th at can also read an d write 1.44M d isks. Th e old er d rive typ es: 5 1/ 4-in ch 360K an d 3 1/ 2-in ch 720K d rives are obsolete, an d rarely fou n d an ym ore.

Floppy Disk Drives

Not e For information on older floppy disk drives and media, see Chapter 13, “ Floppy Disk Drives,” in Upgrading and Repairing PCs, Eighth Edition , found on the CD included with this book.

Th e p h ysical op eration of a d isk d rive is fairly sim p le to d escribe. Th e d isk rotates in th e d rive at eith er 300 or 360 RPM. Most d rives sp in at 300 RPM; on ly th e 5 1/ 4-in ch 1.2M d rives sp in at 360 RPM. W ith th e d isk sp in n in g, th e h ead s can m ove in an d ou t ap p roxim ately 1 in ch an d write 80 tracks. Th e tracks are written on both sid es of th e d isk an d are th erefore som etim es called cylinders. A sin gle cylin d er com p rises th e tracks on th e top an d bottom of th e d isk. Th e h ead s record by u sin g a tu n n el-erase p roced u re th at writes a track to a sp ecified wid th , an d th en erases th e ed ges of th e track to p reven t in terferen ce with an y ad jacen t tracks. Differen t d rives record tracks at d ifferen t wid th s. Table 12.10 sh ows th e track wid th s in both m illim eters an d in ch es for th e d ifferen t typ es of flop p y d isk d rives fou n d in m od ern PC system s. Table 12.10

Floppy Disk Drive Track-W idt h Specificat ions

Drive Type

No. of Tracks

Track W idt h

5 1/ 4-inch 360K

40 per side

0.300 mm

0.0118 in.

5 1/ 4-inch 1.2M

80 per side

0.155 mm

0.0061 in.

3 1/ 2-inch 720K

80 per side

0.115 mm

0.0045 in.

3 1/ 2-inch 1.44M

80 per side

0.115 mm

0.0045 in.

3 1/ 2-inch 2.88M

80 per side

0.115 mm

0.0045 in.

How t he Operat ing Syst em Uses a Disk. To th e op eratin g system , d ata on you r PC d isks is organ ized in tracks an d sectors, ju st as on a h ard d isk d rive. Tracks are n arrow, con cen tric circles on a d isk. Sectors are p ie-sh ap ed slices of th e in d ivid u al tracks. Table 12.11 su m m arizes th e stan d ard d isk form ats for PC flop p y d isk d rives. Table 12.11

3 1/ 2-Inch and 5 1/ 4-Inch Floppy Disk Drive Form at s

5.25-Inch Floppy Disks

Double Densit y 360K ( DD)

High Densit y 1.2M ( HD)

Bytes per Sector

512

512

Sectors per Track

9

15

Tracks per Side

40

80

Sides

2

2

Capacity (Kilobytes)

360

1,200

Capacity (M egabytes)

0.352

1.172

Capacity (M illion Bytes)

0.369

1.229 (continues)

779

780

Chapter 12—M agnetic Storage

Table 12.11 Cont inued

3 1/ 2-Inch and 5 1/ 4-Inch Floppy Disk Drive Form at s

3 1/ 2-Inch Floppy Disks

Double Densit y 720K ( DD)

High Densit y 1.44M ( HD)

Ext ra-High Densit y 2.88M ( ED)

Bytes per Sector

512

512

512

Sectors per Track

9

18

36

Tracks per Side

80

80

80

Sides

2

2

2

Capacity (Kilobytes)

720

1,440

2,880

Capacity (M egabytes)

0.703

1.406

2.813

Capacity (M illion Bytes)

0.737

1.475

2.949

You can calcu late th e cap acity d ifferen ces between d ifferen t form ats by m u ltip lyin g th e sectors p er track by th e n u m ber of tracks p er sid e togeth er with th e con stan ts of two sid es an d 512 bytes p er sector. Note th at th e flop p y d isk’s cap acity can actu ally be exp ressed in d ifferen t ways. Th e trad ition al m eth od is to refer to th e cap acity of a flop p y by th e n u m ber of kilobytes (1,024 bytes eq u als 1K). Th is works fin e for th e old -style 360K an d 720K d isks bu t is stran ge wh en ap p lied to th e 1.44M an d 2.88M d isks. As you can see, a 1.44M d isk is really 1,440K, an d n ot actu ally 1.44 m egabytes. Becau se a m egabyte is 1,024K, wh at we call a 1.44M d isk actu ally h as a cap acity of 1.406M. An oth er way of exp ressin g d isk cap acity is in m illion s of bytes. In th at case, th e 1.44M d isk h as 1.475 m illion bytes of cap acity. Again , as with h ard d isk d rives, both m egabyte an d m illion s of bytes are abbreviated as MB or M, often resu ltin g in a great d eal of con fu sion . Like blan k sh eets of p ap er, n ew d isks con tain n o in form ation . Form attin g a d isk is sim ilar to ad d in g lin es to th e p ap er so you can write straigh t across. Form attin g th e d isk writes th e in form ation th at th e op eratin g system n eed s to m ain tain a d irectory an d file table of con ten ts. On a flop p y d isk, th ere is n o d istin ction between a h igh -level an d a low-level form at, n or d o you h ave to create an y p artition s. W h en you form at a flop p y d isk with W in d ows 9x Exp lorer or th e DOS FORMAT.COM p rogram , both th e h igh - an d low-level form ats are p erform ed at th e sam e tim e. W h en you form at a flop p y d isk, th e op eratin g system reserves th e track n earest to th e ou tsid e ed ge of a d isk (track 0) alm ost en tirely for its p u rp oses. Track 0, Sid e 0, Sector 1 con tain s th e DOS Boot Record (DBR), or Boot Sector, th at th e system n eed s to begin op eration . Th e n ext few sectors con tain th e FATs, wh ich keep s record s of wh ich clu sters or allocation u n its on th e d isk con tain file in form ation an d wh ich are em p ty. Fin ally, th e n ext few sectors con tain th e root d irectory, in wh ich th e op eratin g system stores in form ation abou t th e n am es an d startin g location s of th e files on th e d isk.

Floppy Disk Drives

Cylinders. Th e cylinder n u m ber is som etim es u sed in p lace of track num ber. A cylinder is all th e tracks u n d er a d rive’s read / write h ead s at on e tim e. Becau se a d isk can n ot h ave m ore th an two sid es an d th e d rive h as two h ead s, th ere are always two tracks p er cylin d er for flop p y d isks. Hard d isk d rives, you will recall, can h ave m an y d isk p latters, each with two (or m ore) h ead s, for m an y tracks p er sin gle cylin d er. In eith er case, becau se a cylin d er is com p rised of all tracks with th e sam e n u m ber, th e cylin d er n u m ber an d track n u m ber (of all th e tracks in th at cylin d er) will always be th e sam e. Clust ers or Allocat ion Unit s. A cluster also is called an allocation unit in DOS version 4.0 an d h igh er. Th e term is ap p rop riate becau se a sin gle clu ster is th e sm allest u n it of th e d isk th at DOS can allocate wh en it writes a file. A clu ster or allocation u n it con sists of on e or m ore sectors—u su ally a p ower of two (1, 2, 4, 8, an d so on ). Havin g m ore th an on e sector p er clu ster red u ces th e FAT size an d en ables DOS to ru n faster becau se it h as fewer in d ivid u al clu sters to m an age. Th e trad eoff is in som e wasted d isk sp ace. Becau se DOS can m an age sp ace on ly in th e clu ster size u n it, every file con su m es sp ace on th e d isk in in crem en ts of on e clu ster. Table 12.12 lists th e d efau lt clu ster sizes u sed by DOS an d W in d ows for d ifferen t flop p y d isk form ats. Table 12.12

Default Clust er and Allocat ion Unit Sizes

Floppy Disk Capacit y

Clust er/ Allocat ion Unit Size

FAT Type

5 1/ 4-inch, 360K

2 sectors

1,024 bytes

12-bit

5 1/ 4-inch, 1.2M

1 sector

512 bytes

12-bit

3 1/ 2-inch, 720K

2 sectors

1,024 bytes

12-bit

3 1/ 2-inch, 1.44M

1 sector

512 bytes

12-bit

3 1/ 2-inch, 2.88M

2 sectors

1,024 bytes

12-bit

K = 1,024 bytes M = 1,048,576 bytes

Disket t e Changeline. Th e stan d ard PC flop p y con troller an d d rive u se a sp ecial sign al on p in 34 called Diskette Changeline to d eterm in e wh eth er th e d isk h as been ch an ged , or m ore accu rately, wh eth er th e sam e d isk load ed d u rin g th e p reviou s d isk access is still in th e d rive. Disk Change is a p u lsed sign al th at ch an ges a statu s register in th e con troller to let th e system kn ow th at a d isk h as been eith er in serted or ejected . Th is register is set to in d icate th at a d isk h as been in serted or rem oved (ch an ged ) by d efau lt. Th e register is cleared wh en th e con troller sen d s a step p u lse to th e d rive an d th e d rive resp on d s, ackn owled gin g th at th e h ead s h ave m oved . At th is p oin t, th e system kn ows th at a sp ecific d isk is in th e d rive. If th e d isk ch an ge sign al is n ot received before th e n ext access, th e system can assu m e th at th e sam e d isk is still in th e d rive. An y in form ation read in to m em ory d u rin g th e p reviou s access can th erefore be reu sed with ou t reread in g th e d isk.

781

782

Chapter 12—M agnetic Storage

Becau se of th is p rocess, system s can bu ffer or cach e th e con ten ts of th e file allocation table (FAT) or d irectory stru ctu re of a d isk in th e system ’s m em ory. By elim in atin g u n n ecessary reread s of th ese areas of th e d isk, th e ap p aren t sp eed of th e d rive is in creased . If you m ove th e d oor lever or eject bu tton on a d rive th at su p p orts th e d isk ch an ge sign al, th e DC p u lse is sen t to th e con troller, th u s resettin g th e register an d in d icatin g th at th e d isk h as been ch an ged . Th is p roced u re cau ses th e system to p u rge bu ffered or cach ed d ata th at h ad been read from th e d isk becau se th e system th en can n ot be su re th at th e sam e d isk is still in th e d rive. On e in terestin g p roblem can occu r wh en certain d rives are in stalled in a 16-bit or greater system . As m en tion ed , som e d rives u se p in 34 for a “Read y” (RDY) sign al. Th e RDY sign al is sen t wh en ever a d isk is in stalled an d rotatin g in th e d rive. If you in stall a d rive th at h as p in 34 set to sen d RDY, th e system “th in ks” th at it is con tin u ou sly receivin g a d isk ch an ge sign al, wh ich cau ses p roblem s. Usu ally th e d rive fails with a Drive not ready error an d is in op erable. Th e on ly reason th at th e RDY sign al exists on som e d rives is th at it h ap p en s to be a p art of th e stan d ard Sh u gart SA-400 d isk in terface; h owever, it h as n ever been u sed in PC system s. Th e biggest p roblem occu rs if th e d rive is n ot sen d in g th e DC sign al on p in 34, an d it sh ou ld . If a system is told (th rou gh CMOS setu p ) th at th e d rive is an y oth er typ e th an a 360K (wh ich can n ot ever sen d th e DC sign al), th e system exp ects th e d rive to sen d DC wh en ever a d isk h as been ejected . If th e d rive is n ot con figu red p rop erly to sen d th e sign al, th e system n ever recogn izes th at a d isk h as been ch an ged . Th erefore, even if you d o ch an ge th e d isk, th e system still acts as th ou gh th e first d isk is in th e d rive an d h old s th e first d isk’s d irectory an d FAT in form ation in RAM. Th is can be d an gerou s becau se th e FAT an d d irectory in form ation from th e first d isk can be p artially written to an y su bseq u en t d isks written to in th e d rive.

Caut ion If you ever have seen a system with a floppy disk drive that shows “ phantom directories” of the previously installed disk, even after you have changed or removed it, you have experienced this problem firsthand. The negative side effect is that all disks after the first one you place in this system are in extreme danger. You likely will overwrite the directories and FATs of many disks with information from the first disk. If even possible at all, data recovery from such a catastrophe can require quite a bit of work with utility programs such as Norton Utilities. These problems with Disk Change most often are traced to an incorrectly configured drive.

If th e d rive you are in stallin g is a 5 1/ 4-in ch 1.2M or 3 1/ 2-in ch 720K, 1.44M, or 2.88M d rive, be su re to set p in 34 to sen d th e Disk Ch an ge (DC) sign al. Types of Floppy Disk Drives Th e ch aracteristics of th e flop p y d isk d rives you m igh t en cou n ter in PC-com p atible system s are su m m arized in Table 12.13. As you can see, th e d ifferen t d isk cap acities are d eterm in ed by several p aram eters, som e of wh ich seem to rem ain con stan t on all d rives,

Floppy Disk Drives

alth ou gh oth ers ch an ge from d rive to d rive. For exam p le, all d rives u se 512-byte p h ysical sectors, wh ich is tru e for h ard d isks, as well. Table 12.13

Floppy Disk Logical Form at t ed Param et ers Current Form at s

Obsolet e Form at s

Disk Size ( inches)

3 1/ 2

3 1/ 2

3 1/ 2

5 1/ 4

5 1/ 4

5 1/ 4

5 1/ 4

5 1/ 4

Disk Capacit y ( K)

2,880

1,440

720

1,200

360

320

180

160

M edia Descriptor Byte

F0h

F0h

F9h

F9h

FDh

FFh

FCh

FEh

Sides (Heads)

2

2

2

2

2

2

1

1

Tracks per Side

80

80

80

80

40

40

40

40

Sectors per Track

36

18

9

15

9

8

9

8

Bytes per Sector

512

512

512

512

512

512

512

512

Sectors per Cluster

2

1

2

1

2

2

1

1

FAT Length (Sectors)

9

9

3

7

2

1

2

1

Number of FATs

2

Root Dir. Length (Sectors) 15

2

2

2

2

2

2

2

14

7

14

7

7

4

4

M axim um Root Entries

240

224

112

224

112

112

64

64

Total Sectors per Disk

5,760

2,880

1,440

2,400

720

640

360

320

Total Available Sectors

5,726

2,847

1,426

2,371

708

630

351

313

Total Available Clusters

2,863

2,847

713

2,371

354

315

351

313

The 1.44M 3 1/ 2-Inch Drive. Th e 3 1/ 2-in ch , 1.44M, High Den sity (HD) d rives first ap p eared from IBM in th e PS/ 2 p rod u ct lin e in trod u ced in 1987. Most oth er com p u ter ven d ors started offerin g th e d rives as an op tion in th eir system s im m ed iately afterward s. Th is typ e of d rive is still th e m ost p op u lar in system s tod ay. Th e d rive record s 80 cylin d ers con sistin g of two tracks each with 18 sectors p er track, resu ltin g in a form atted cap acity of 1.44M. Som e d isk m an u factu rers label th ese d isks as 2.0M d isks, an d th e d ifferen ce between th is u n form atted cap acity an d th e form atted u sable resu lt is lost d u rin g th e form at. Note th at th e 1,440K of total form atted cap acity d oes n ot accou n t for th e areas th at th e FAT file system reserves for file m an agem en t, leavin g on ly 1423.5K of actu al file-storage area. Th e d rive sp in s at 300 RPM, an d in fact m u st sp in at th at sp eed to op erate p rop erly with existin g h igh - an d low-d en sity con trollers. To u se th e 500KHz d ata rate (th e m axim u m from m ost stan d ard h igh - an d low-d en sity flop p y con trollers), th ese d rives m u st sp in at a m axim u m of 300 RPM. If th e d rives were to sp in at th e faster 360 RPM rate of th e 5 1/ 4in ch d rives, th ey wou ld h ave to red u ce th e total n u m ber of sectors p er track to 15, or else th e con troller cou ld n ot keep u p . In sh ort, th e 1.44M 3 1/ 2-in ch d rives store 1.2 tim es th e d ata of th e 5 1/ 4-in ch 1.2M d rives, an d th e 1.2M d rives sp in exactly 1.2 tim es faster th an th e 1.44M d rives. Th e d ata rates u sed by both of th ese HD d rives are id en tical an d com p atible with th e sam e con trollers. In fact, becau se th ese 3 1/ 2-in ch HD d rives can ru n at th e 500KHz d ata rate, a con troller th at can su p p ort a 1.2M 5 1/ 4-in ch d rive can su p p ort th e 1.44M d rives also.

783

784

Chapter 12—M agnetic Storage

The 2.88M 3 1/ 2-Inch Drive. Th e 3 1/ 2-in ch , 2.88M d rive was d evelop ed by Tosh iba Corp oration in th e 1980s an d was officially an n ou n ced in 1987. Tosh iba began p rod u ction m an u factu rin g of th e d rives an d d isks in 1989, an d several ven d ors began sellin g th e d rives as u p grad es for th eir system s. IBM officially ad op ted th ese d rives in th eir PS/ 2 system s in 1991, an d a n u m ber of m an u factu rers began m akin g th em , in clu d in g Tosh iba, Mitsu bish i, Son y, an d Pan ason ic. Becau se a 2.88M d rive can fu lly read an d write 1.44M d isks, th e ch an ge is an easy on e bu t, u n fortu n ately, d u e to h igh m ed ia costs, th ese d rives h ave n ot cau gh t on wid ely, alth ou gh virtu ally all system s tod ay h ave bu ilt-in su p p ort for th em . DOS version 5.0 or later is req u ired to su p p ort th e 2.88M d rives. Th e 2.88M Extra-h igh Den sity (ED) d rive u ses a tech n iq u e called vertical recording to ach ieve its great lin ear d en sity of 36 sectors p er track. Th is tech n iq u e in creases d en sity by m agn etizin g th e d om ain s p erp en d icu lar to th e record in g su rface. By essen tially p lacin g th e m agn etic d om ain s on th eir en d s an d stackin g th em sid e by sid e, th e d isk d en sity in creases en orm ou sly. Th e tech n ology for p rod u cin g h ead s th at can p erform a vertical or p erp en d icu lar record in g h as been arou n d for som e tim e, bu t it is n ot th e h ead s or even th e d rive th at rep resen t th e m ajor breakth rou gh in tech n ology; rath er, it is th e m ed ia th at is sp ecial. Stan d ard d isks h ave m agn etic p articles sh ap ed like tin y n eed les th at lie on th e su rface of th e d isk. Orien tin g th ese acicu lar p articles in a p erp en d icu lar m an n er to en able vertical record in g is very d ifficu lt. Th e p articles on a bariu m -ferrite flop p y d isk are sh ap ed like tin y, flat, h exagon al p latelets th at can m ore easily be arran ged to h ave th eir axes of m agn etization p erp en d icu lar to th e p lan e of record in g. Tosh iba p erfected a glass-crystallization p rocess for m an u factu rin g th e u ltra-fin e p latelets u sed in coatin g th e bariu m -ferrite d isks. Th is tech n ology, p aten ted by Tosh iba, is bein g licen sed to a n u m ber of d isk m an u factu rers, all of wh om are p rod u cin g bariu m -ferrite d isks by u sin g Tosh iba’s p rocess. Tosh iba also m ad e certain m od ification s to th e d esign of stan d ard d isk d rive h ead s to en able th em to read an d write th e n ew bariu m -ferrite d isks, as well as stan d ard cobalt or ferrite d isks. Th is tech n ology is bein g u sed n ot on ly in flop p y d isk d rives bu t also is ap p earin g in a variety of tap e d rive form ats. Th e d isks are called 4M disks in referen ce to th eir u n form atted cap acity. Th e actu al form atted cap acity is 2,880K, or 2.88M. Becau se of sp ace lost in th e form attin g p rocess, as well as sp ace occu p ied by th e volu m e boot sector, FATs, an d root d irectory, th e total u sable storage sp ace is 2,863K. To su p p ort th e 2.88M d rive, m od ification s to th e d isk con troller circu itry were req u ired , becau se th ese d rives sp in at th e sam e 300 RPM bu t h ave an aston ish in g 36 sectors p er track. Becau se all flop p y d isks are form atted with con secu tively n u m bered sectors (1:1 in terleave), th e d rive h as to read an d write 36 sectors in th e sam e tim e it takes a 1.44M d rive to read an d write 18 sectors. Th is req u ires th at th e con troller su p p ort a m u ch h igh er d ata tran sm ission rate of 1MHz (1 m illion bp s). Most old er flop p y con trollers su p p ort on ly th e m axim u m of 500KHz d ata rate u sed by th e 1.44M d rives. To u p grad e to a 2.88M d rive req u ires th at th e con troller be ch an ged to on e th at su p p orts th e h igh er 1MHz d ata rate.

Floppy Disk Drives

An ad d ition al su p p ort issu e is th e ROM BIOS. Th e BIOS m u st h ave su p p ort for th e con troller an d th e cap ability to sp ecify an d accep t th e 2.88M d rive as a CMOS settin g. Som e n ewer m oth erboard BIOS sets from com p an ies like Ph oen ix, AMI, an d Award h ave su p p ort for ED con trollers. Virtu ally all m od ern PCs h ave bu ilt-in flop p y con trollers an d ROM BIOS software th at fu lly su p p ort th e 2.88M d rives. Ad d in g or u p grad in g to a 2.88M d rive in th ese system s is as easy as p lu ggin g in th e d rive an d ru n n in g th e CMOS Setu p p rogram . For system s th at d o n ot h ave th is bu ilt-in su p p ort, th e u p grad e p rocess is m u ch m ore d ifficu lt. Several com p an ies offer n ew con trollers an d BIOS u p grad es as well as th e 2.88M d rives sp ecifically for u p grad in g old er system s. Alth ou gh th e 2.88M d rives th em selves are n ot m u ch m ore exp en sive th an th e 1.44M d rives th ey rep lace, th e d isk m ed ia can be exp en sive an d h ard to fin d , as th is form at n ever really cau gh t on in th e m ain stream , alth ou gh all m od ern PCs su p p ort it. The 720K 3 1/ 2-Inch Drive. Th e 720K, 3 1/ 2-in ch , DD d rives first ap p eared in an IBM system with th e IBM Con vertible lap top system in trod u ced in 1986. In fact, all IBM system s in trod u ced sin ce th at tim e h ave 3 1/ 2-in ch d rives as th e stan d ard su p p lied d rives. Th is typ e of d rive also is offered by IBM as an in tern al or extern al d rive for th e AT or XT system s.

Not e Outside the PC-compatible world, other computer-system vendors (Apple, Hewlett-Packard, and so on) offered 3 1/ 2-inch drives for their systems well before the PC-compatible world “ caught on.”

Th e 720K, 3 1/ 2-in ch , DD d rive n orm ally record s 80 cylin d ers of two tracks each , with n in e sectors p er track, resu ltin g in th e form atted cap acity of 720K. It is in terestin g to n ote th at m an y d isk m an u factu rers label th ese d isks as 1.0M d isks, wh ich is tru e. Th e d ifferen ce between th e actu al 1.0M of cap acity an d th e u sable 720K after form attin g is th at som e sp ace on each track is occu p ied by th e h ead er an d trailer of each sector, th e in ter-sector gap s, an d th e in d ex gap at th e start of each track before th e first sector. Th ese sp aces are n ot u sable for d ata storage, an d accou n t for th e d ifferen ces between th e u n form atted an d form atted cap acities. Most m an u factu rers rep ort th e u n form atted cap acities becau se th ey d o n ot kn ow on wh ich typ e of system you will form at th e d isk. Ap p le Macin tosh system s, for exam p le, can store 800K of d ata on th e sam e d isk becau se of a d ifferen t form attin g tech n iq u e. Note also th at th e 720K of u sable sp ace d oes n ot accou n t for th e d isk areas DOS reserves for m an agin g th e d isk (boot sectors, FATs, d irectories, an d so on ) an d th at becau se of th ese areas, on ly 713K rem ain s for file d ata storage. PC-com p atible system s h ave u sed 720K, 3 1/ 2-in ch , DD d rives p rim arily in XT-class system s becau se th e d rives op erate from an y low-d en sity con troller. Th e d rives sp in at 300

785

786

Chapter 12—M agnetic Storage

RPM, an d th erefore req u ire on ly a 250KHz d ata rate from th e con troller to op erate p rop erly. Th is d ata rate is th e sam e as th e 360K d isk d rives, wh ich m ean s th at an y con troller th at su p p orts a 360K d rive also su p p orts th e 720K d rives. An IBM system with a ROM BIOS d ate of 06/ 10/ 85 or later h as bu ilt-in su p p ort for 720K d rives an d req u ires n o d river to u se th em . If you r system h as an earlier ROM BIOS d ate, th e DRIVER.SYS p rogram from DOS V3.2 or later—as well as th e DRIVPARM CONFIG.SYS com m an d in som e OEM DOS version s—is all you n eed to p rovid e th e n ecessary software su p p ort to op erate th ese d rives. The 1.2M 5 1/ 4-Inch Drive. Th e 1.2M h igh -d en sity flop p y d isk d rive first ap p eared in th e IBM AT system in trod u ced in Au gu st 1984. Th e d rive req u ired th e u se of a n ew typ e of d isk to ach ieve th e 1.2M form at cap acity, bu t it still cou ld read an d write (alth ou gh n ot always reliably) th e lower-d en sity 360K d isks. Th e 1.2M 5 1/ 4-in ch d rive n orm ally record ed 80 cylin d ers of two tracks each , startin g with cylin d er 0, at th e ou tsid e of th e d isk. Th is situ ation d iffers from th e low-d en sity 5 1/ 4-in ch d rive in its cap ability to record twice as m an y cylin d ers in ap p roxim ately th e sam e sp ace on th e d isk. Th is cap ability alon e su ggests th at th e record in g cap acity for a d isk wou ld d ou ble, bu t th at is n ot all. Each track n orm ally is record ed with 15 sectors of 512 bytes each , in creasin g th e storage cap acity even m ore. In fact, th ese d rives store n early fou r tim es th e d ata of th e 360K d isks. Th e d en sity in crease for each track req u ired th e u se of sp ecial d isks with a m od ified m ed ia d esign ed to h an d le th is typ e of record in g. Becau se th ese d isks in itially were exp en sive an d d ifficu lt to obtain , m an y u sers attem p ted in correctly to u se th e low-d en sity d isks in th e 1.2M 5 1/ 4-in ch d rives an d form at th em to th e h igh er 1.2M-d en sity form at, wh ich resu lts in d ata loss an d u n n ecessary d ata-recovery op eration s. A com p atibility p roblem with th e 360K d rives stem s from th e 1.2M d rive’s cap ability to write twice as m an y cylin d ers in th e sam e sp ace as th e 360K d rives. Th e 1.2M d rives p osition th eir h ead s over th e sam e 40 cylin d er p osition s u sed by th e 360K d rives th rou gh double stepping, a p roced u re in wh ich th e h ead s are m oved every two cylin d ers to arrive at th e correct p osition s for read in g an d writin g th e 40 cylin d ers on th e 360K d isks. Th e p roblem is th at becau se th e 1.2M d rive n orm ally h as to write 80 cylin d ers in th e sam e sp ace in wh ich th e 360K d rive writes 40, th e h ead s of th e 1.2M u n its h ad to be m ad e d im en sion ally sm aller. Th ese n arrow h ead s can h ave p roblem s overwritin g tracks p rod u ced by a 360K d rive th at h as a wid er h ead becau se th e n arrower h ead s on th e 1.2M d rive can n ot “cover” th e en tire track area written by th e 360K d rive. Th e 1.2M 5 1/ 4-in ch d rives sp in at 360 RPM, or six revolu tion s p er secon d , or 166.67m s p er revolu tion . Th e d rives sp in at th is rate n o m atter wh at typ e of d isk is in serted —eith er low- or h igh -d en sity. To sen d or receive 15 sectors (p lu s req u ired overh ead ) six tim es p er secon d , a con troller m u st u se a d ata-tran sm ission rate of 500,000bp s (500KHz). All stan d ard h igh - an d low-d en sity con trollers su p p ort th is d ata rate an d , th erefore, th ese d rives. Th is su p p ort d ep en d s also on p rop er ROM BIOS su p p ort of th e con troller in th is m od e of op eration . W h en a stan d ard 360K d isk is ru n n in g in an HD d rive, it also is sp in n in g at 360 RPM; a d ata rate of 300,000bp s (300KHz), th erefore, is req u ired to work p rop erly. All

Floppy Disk Drives

stan d ard AT-style low- an d h igh -d en sity con trollers su p p ort th e 250KHz, 300KHz, an d 500KHz d ata rates. Th e 300KHz rate is u sed on ly for HD 5 1/ 4-in ch d rives read in g or writin g to low-d en sity 5 1/ 4-in ch d isks. Virtu ally all stan d ard AT-style system s h ave a ROM BIOS th at su p p orts th e con troller’s op eration of th e 1.2M d rive, in clu d in g th e 300KHz d ata rate. The 360K 5 1/ 4-Inch Drive. Th e 5 1/ 4-in ch d ou ble-d en sity d rive is d esign ed to create a stan d ard -form at d isk with 360K cap acity. Th e term double-density arose from th e u se of th e term single density to in d icate a typ e of d rive th at u sed freq u en cy m od u lation (FM) en cod in g to store ap p roxim ately 90K on a d isk. Th is typ e of obsolete d rive n ever was u sed in an y PC-com p atible system s, bu t was u sed in som e old er system s su ch as th e origin al Osborn e-1 p ortable com p u ter. W h en d rive m an u factu rers ch an ged th e d rives to u se Mod ified Freq u en cy Mod u lation (MFM) en cod in g, th ey began u sin g th e term doubledensity to in d icate it, as well as th e (ap p roxim ately d ou bled ) in crease in record in g cap acity realized from th is en cod in g m eth od . Th e 360K 5 1/ 4-in ch d rives sp in at 300 RPM, wh ich eq u als exactly five revolu tion s p er secon d , or 200m s p er revolu tion . All stan d ard flop p y con trollers su p p ort a 1:1 in terleave, in wh ich each sector on a sp ecific track is n u m bered (an d read ) con secu tively. To read an d write to a d isk at fu ll sp eed , a con troller sen d s d ata at a rate of 250,000bp s. All stan d ard PC-com p atible system s in clu d e ROM BIOS su p p ort for th ese d rives; th erefore, you u su ally d o n ot n eed sp ecial software or d river p rogram s to u se th em . Analyzing Floppy Disk Const ruct ion Th e 5 1/ 4-in ch an d 3 1/ 2-in ch d isks each h ave u n iq u e con stru ction an d p h ysical p rop erties. Th e flexible (or flop p y) d isk is con tain ed with in a p lastic jacket. Th e 3 1/ 2-in ch d isks are covered by a m ore rigid jacket th an th e 5 1/ 4-in ch d isks; th e d isks with in th e jackets, h owever, are virtu ally id en tical excep t, of cou rse, for th e size. W h en you look at a typ ical 5 1/ 4-in ch flop p y d isk, you see several th in gs (see Figu re 12.19). Most p rom in en t is th e large rou n d h ole in th e cen ter. W h en you close th e d isk d rive’s “d oor,” a con e-sh ap ed clam p grabs an d cen ters th e d isk th rou gh th e cen ter h ole. Man y d isks com e with hub-ring reinforcem ents—th in , p lastic rin gs th at h elp th e d isk with stan d th e m ech an ical forces of th e clam p in g m ech an ism . Th e HD d isks u su ally lack th ese rein forcem en ts becau se th e d ifficu lty in accu rately p lacin g th em on th e d isk m ean s th ey can cau se align m en t p roblem s. On th e righ t sid e, ju st below th e cen ter of th e h u b h ole, is a sm aller rou n d h ole called th e index hole. If you carefu lly tu rn th e d isk with in its p rotective jacket, you can see a sm all h ole in th e d isk itself. Th e d rive u ses th e in d ex h ole as th e startin g p oin t for all th e sectors on th e d isk—sort of th e “p rim e m erid ian ” for th e d isk sectors. A d isk with a sin gle in d ex h ole is a soft-sectored d isk; th e software (op eratin g system ) d ecid es th e actu al n u m ber of sectors on th e d isk. Som e old er eq u ip m en t, su ch as W an g word p rocessors, u se h ard -sectored d isks, wh ich h ave an in d ex h ole to d em arcate in d ivid u al sectors. Do n ot u se h ard -sectored d isks in a PC.

787

Chapter 12—M agnetic Storage

Stress–relief notches

0.25 ± 0.01 Inch (6.30 ± 0.25 mm)

0.140 Inch (3.56 mm)

3.80 ± 0.01 Inch (86.5 ± 0.25 mm)

788

5.25 Inch (133.4 mm)

Oxide–coated Mylar disk

Write– enable notch 5.25 Inch (133.4 mm) Liner

Spindle–access hole Head aperture

Index hole

Courtesy of IBM Corporation

FIG. 12.19 Con stru ction of a 5 1/ 4-in ch flop p y d isk. Below th e h u b h ole is a slot sh ap ed som ewh at like a lon g racetrack th rou gh wh ich you can see th e d isk su rface. Th rou gh th is m ed ia-access h ole, th e d isk d rive h ead s read an d write d ata to th e d isk su rface. On th e righ t sid e, abou t on e in ch from th e top , is a rectan gu lar p u n ch from th e sid e of th e d isk cover. If th is write-en able n otch is p resen t, writin g to th e d isk h as been en abled . Disks with ou t th is n otch (or with th e n otch tap ed over) are write-p rotected d isks. Th e n otch m igh t n ot be p resen t on all d isks, p articu larly th ose p u rch ased with p rogram s on th em . On th e rear of th e d isk jacket at th e bottom , two very sm all oval n otch es flan k th e h ead slot. Th ese n otch es relieve stress on th e d isk an d h elp p reven t it from warp in g. Th e d rive m igh t also u se th ese n otch es to assist in keep in g th e d isk in th e p rop er p osition in th e d rive. Becau se th e 3 1/ 2-in ch d isks u se a m u ch m ore rigid p lastic case, wh ich h elp s stabilize th e m agn etic m ed iu m in sid e, th ese d isks can record at track an d d ata d en sities greater th an th e 5 1/ 4-in ch d isks (see Figu re 12.20). A m etal sh u tter p rotects th e m ed ia-access h ole. Th e d rive m an ip u lates th e sh u tter, leavin g it closed wh en ever th e d isk is n ot in a d rive. Th e m ed ia is th en com p letely in su lated from th e en viron m en t an d from you r fin gers. Th e sh u tter also obviates th e n eed for a d isk jacket. Becau se th e sh u tter is n ot n ecessary for th e d isk to work, you can rem ove it from th e p lastic case if it becom es ben t or d am aged . Pry it off of th e d isk case; it will p op off with a sn ap . You sh ou ld rem ove th e sp rin g th at p u sh es it closed , as well. After rem ovin g th e d am aged sh u tter, it wou ld be a good id ea to cop y th e d ata from th e d am aged d isk to a n ew on e. Rath er th an an in d ex h ole in th e d isk, th e 3 1/ 2-in ch d isks u se a m etal cen ter h u b with an align m en t h ole. Th e d rive “grasp s” th e m etal h u b, an d th e h ole in th e h u b en ables th e d rive to p osition th e d isk p rop erly.

Floppy Disk Drives

Access to magnetic surface (only when retracted)

90 mm (3.5”)

Retractable metal sheath

94 mm (3.7”)

Extra High–density media–sensor hole High-density media-sensor hole Write–protect switch(underneath)

Actual magnetic disk

Hard–plastic outer case

FIG. 12.20 Con stru ction of a 3 1/ 2-in ch flop p y d isk. On th e lower-left p art of th e d isk is a h ole with a p lastic slid er—th e write-protect/-enable hole. W h en th e slid er is p osition ed so th e h ole is visible, th e d isk is write-p rotected ; th e d rive is p reven ted from record in g on th e d isk. W h en th e slid er is p osition ed to cover th e h ole, writin g is en abled , an d you can save d ata to th e d isk. For m ore p erm an en t writep rotection , som e com m ercial software p rogram s are su p p lied on d isks with th e slid er rem oved so you can n ot easily en able record in g on th e d isk, wh ich is exactly op p osite of a 5 1/ 4-in ch flop p y in wh ich Covered eq u als W rite Protect, n ot W rite En able. On th e oth er (righ t) sid e of th e d isk from th e write-p rotect h ole, th ere is u su ally an oth er h ole called th e m edia-density-selector hole. If th is h ole is p resen t, th e d isk is con stru cted of a sp ecial m ed iu m an d is th erefore an HD or ED d isk. If th e m ed ia-sen sor h ole is exactly op p osite th e write-p rotect h ole, it in d icates a 1.44M HD d isk. If th e m ed ia-sen sor h ole is located m ore toward th e top of th e d isk (th e m etal sh u tter is at th e top of th e d isk), it in d icates an ED d isk. No h ole on th e righ t sid e m ean s th at th e d isk is a low-d en sity d isk. Most 3 1/ 2-in ch d rives h ave a m ed ia sen sor th at con trols record in g cap ability based on th e absen ce or p resen ce of th ese h oles. Th e actu al m agn etic m ed iu m in both th e 3 1/ 2-in ch an d 5 1/ 4-in ch d isks is con stru cted of th e sam e basic m aterials. Th ey u se a p lastic base (u su ally Mylar) coated with a m agn etic com p ou n d . High d en sity d isks u se a cobalt-ferric com p ou n d , an d exten d ed d en sity d isks u se a bariu m -ferric m ed ia com p ou n d . Th e rigid jacket m aterial on th e 3 1/ 2in ch d isks often cau ses p eop le to believe in correctly th at th ese d isks are som e sort of “h ard d isk” an d n ot really a flop p y d isk. Th e d isk “cookie” in sid e th e 3 1/ 2-in ch case is ju st as flop p y as th e 5 1/ 4-in ch variety. Floppy Disk M edia Types and Specificat ions. Th is section exam in es th e typ es of d isks you can p u rch ase for you r system . Esp ecially in terestin g are th e tech n ical sp ecification s th at can sep arate on e typ e of d isk from an oth er, as Table 12.14 sh ows. Th e followin g section s d efin e all th e sp ecification s u sed to d escribe a typ ical d isk.

789

790

Chapter 12—M agnetic Storage

Table 12.14

Floppy Disk M edia Specificat ions 5 1/ 4-Inch

M edia Param et ers

Double Quad Densit y Densit y ( DD) ( QD)

3 1/ 2-Inch

High Densit y ( HD)

Double Densit y ( DD)

High Densit y ( HD)

Ext raHigh Densit y ( ED)

Tracks Per Inch (TPI)

48

96

96

135

135

135

Bits Per Inch (BPI)

5,876

5,876

9,646

8,717

17,434

34,868

M edia Formulation

Ferrite

Ferrite

Cobalt

Cobalt

Cobalt

Barium

Coercivity (Oersteds)

300

300

600

600

720

750

Thickness (M icro-In.)

100

100

50

70

40

100

Recording Polarity

Horiz.

Horiz.

Horiz.

Horiz.

Horiz.

Vert.

D e n si t y . Density, in sim p lest term s, is a m easu re of th e am ou n t of in form ation th at can be p acked reliably in to a sp ecific area of a record in g su rface. Th e keyword h ere is reliably. Disks h ave two typ es of d en sities: lon gitu d in al d en sity an d lin ear d en sity. Longitudinal density is in d icated by h ow m an y tracks can be record ed on th e d isk, often exp ressed as a n u m ber of tracks p er in ch (TPI). Linear density is th e cap ability of an in d ivid u al track to store d ata, often in d icated as a n u m ber of bits p er in ch (BPI). Un fortu n ately, th ese typ es of d en sities are often con fu sed wh en d iscu ssin g d ifferen t d isks an d d rives. Me d i a Co e rc i v i t y a n d Th i c k n e ss. Th e coercivity sp ecification of a d isk refers to th e m agn etic-field stren gth req u ired to m ake a p rop er record in g. Coercivity, m easu red in oersted s, is a valu e in d icatin g m agn etic stren gth . A d isk with a h igh er coercivity ratin g req u ires a stron ger m agn etic field to m ake a record in g on th at d isk. W ith lower ratin gs, th e d isk can be record ed with a weaker m agn etic field . In oth er word s, th e lower th e coercivity ratin g, th e m ore sen sitive th e d isk. HD m ed ia d em an d s h igh er coercivity ratin gs so th e ad jacen t m agn etic d om ain s d on ’t in terfere with each oth er. For th is reason , HD m ed ia is actu ally less sen sitive an d req u ires a stron ger record in g sign al stren gth . An oth er factor is th e th ickn ess of th e d isk. Th e th in n er th e d isk, th e less in flu en ce a region of th e d isk h as on an oth er ad jacen t region . Th e th in n er d isks, th erefore, can accep t m an y m ore bits p er in ch with ou t even tu ally d egrad in g th e record in g. Caring for and Handling Floppy Disks and Drives. Most com p u ter u sers kn ow th e basics of d isk care. Disks can be d am aged or d estroyed easily by th e followin g: ■ Tou ch in g th e record in g su rface with you r fin gers or an yth in g else ■ W ritin g on a d isk label with a ball-p oin t p en or p en cil ■ Ben d in g th e d isk ■ Sp illin g coffee or oth er su bstan ces on th e d isk

Floppy Disk Drives

■ Overh eatin g a d isk (leavin g it in th e h ot su n or n ear a rad iator, for exam p le) ■ Exp osin g a d isk to stray m agn etic field s Desp ite all th ese cau tion s, d isks are rath er h ard y storage d evices; I can ’t say th at I h ave ever d estroyed on e by ju st writin g on it with a p en , becau se I d o so all th e tim e. I am carefu l, h owever, n ot to p ress too h ard , wh ich can p u t a crease in th e d isk. Also, tou ch in g a d isk d oes n ot n ecessarily ru in it bu t rath er gets th e d isk an d you r d rive h ead d irty with oil an d d u st. Th e real d an ger to you r d isks com es from m agn etic field s th at, becau se th ey are u n seen , can som etim es be fou n d in p laces you n ever im agin ed . For exam p le, all color m on itors (an d color TV sets) h ave a d egau ssin g coil arou n d th e face of th e tu be th at d em agn etizes th e sh ad ow m ask wh en you tu rn th e m on itor on . If you keep you r d isks an ywh ere n ear (with in on e foot) of th e fron t of th e color m on itor, you exp ose th em to a stron g m agn etic field every tim e you tu rn on th e m on itor. Keep in g d isks in th is area is n ot a good id ea becau se th e field is d esign ed to d em agn etize objects, an d in d eed works well for d em agn etizin g d isks. Th e effect is cu m u lative an d irreversible. An oth er sou rce of p owerfu l m agn etic field s is an electric m otor, fou n d in vacu u m clean ers, h eaters or air con d ition ers, fan s, electric p en cil sh arp en ers, an d so on . Do n ot p lace th ese d evices n ear areas wh ere you store d isks. Au d io sp eakers also con tain m agn ets, bu t m ost of th e sp eakers sold for u se with PCs are sh ield ed to m in im ize d isk corru p tion . Airport X-Ray M achines and M et al Det ect ors. Peop le associate m yth s with th in gs th ey can n ot see, an d we certain ly can n ot see d ata as it is stored on a d isk, n or th e m agn etic field s th at can alter th e d ata. On e of m y favorite m yth s to d isp el is th at th e airp ort X-ray m ach in e som eh ow d am ages d isks. I h ave a great d eal of exp erien ce in th is area from h avin g traveled arou n d th e cou n try for th e p ast 10 years or so with d isks an d p ortable com p u ters in h an d . I fly abou t 150,000 m iles p er year, an d m y p ortable com p u ter eq u ip m en t an d d isks h ave been th rou gh X-ray m ach in es m ore th an 100 tim es each year. Th e biggest p roblem p eop le h ave wh en th ey ap p roach th e airp ort X-ray m ach in es with d isks or com p u ters is th at th ey d on ’t p ass th e stu ff th rou gh ! Seriou sly, X-rays are essen tially ju st a form of ligh t, an d d isks an d com p u ters are n ot affected by X-rays at an ywh ere n ear th e levels fou n d in th ese m ach in es. W h at can d am age you r m agn etic m ed ia is th e m etal d etector. Tim e an d tim e again , som eon e with m agn etic m ed ia or a p ortable com p u ter ap p roach es th e secu rity ch eck. Th ey freeze an d say, “Oh n o, I h ave d isks an d a com p u ter—th ey h ave to be h an d in sp ected .” Th e p erson th en refu ses to p lace th e d isk an d com p u ter on th e X-ray belt, an d eith er walks th rou gh th e m etal d etector with d isks an d com p u ter in h an d or p asses th e item s over to th e secu rity gu ard , in very close p roxim ity to th e m etal d etector. Metal d etectors work by m on itorin g d isru p tion s in a weak m agn etic field . A m etal object in serted in th e field area cau ses th e field ’s sh ap e to ch an ge, wh ich th e d etector observes. Th is p rin cip le, wh ich is th e reason th at th e d etectors are sen sitive to m etal objects, can be d an gerou s to you r d isks; th e X-ray m ach in e, h owever, is th e safest area th rou gh wh ich to p ass eith er you r d isk or you r com p u ter.

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Th e X-ray m ach in e is n ot d an gerou s to m agn etic m ed ia becau se it m erely exp oses th e m ed ia to electrom agn etic rad iation at a p articu lar (very h igh ) freq u en cy. Blue light is an exam p le of electrom agn etic rad iation of a d ifferen t freq u en cy. Th e on ly d ifferen ce between X-rays an d blu e ligh t is in th e freq u en cy, or wavelen gth , of th e em ission . Som e p eop le worry abou t th e effect of X-ray rad iation on th eir system ’s EPROM (Erasable Program m able Read-Only Mem ory) chips. Th is con cern m igh t actu ally be m ore valid th an worryin g abou t d isk d am age becau se EPROMs are erased by certain form s of electrom agn etic rad iation . In reality, h owever, you d o n ot n eed to worry abou t th is effect, eith er. EPROMs are erased by d irect exp osu re to very in ten se u ltraviolet ligh t. Sp ecifically, to be erased , an EPROM m u st be exp osed to a 12,000 u w/ cm 2 UV ligh t sou rce with a wavelen gth of 2,537 an gstrom s for 15 to 20 m in u tes, an d at a d istan ce of 1 in ch . In creasin g th e p ower of th e ligh t sou rce or d ecreasin g th e d istan ce from th e sou rce can sh orten th e erasu re tim e to a few m in u tes. Th e airp ort X-ray m ach in e is d ifferen t by a factor of 10,000 in wavelen gth , an d th e field stren gth , d u ration , an d d istan ce from th e em itter sou rce are n owh ere n ear wh at is n ecessary for EPROM erasu re. Man y circu it-board m an u factu rers even u se X-ray in sp ection on circu it board s (with com p on en ts in clu d in g EPROMs in stalled ) to test an d ch eck q u ality con trol d u rin g m an u factu re. In m y own exp erien ces, I h ave p assed on e d isk th rou gh d ifferen t airp ort X-ray m ach in es for two years, averagin g two or th ree p asses a week. Th e sam e d isk still rem ain s in tact with all th e origin al files an d d ata an d h as n ever been reform atted . I also h ave a p ortable com p u ter th at h as gon e th rou gh X-ray m ach in es safely every week for m ore th an fou r years. I p refer to p ass com p u ters an d d isks th rou gh th e X-ray m ach in e becau se it offers th e best sh ield in g from th e m agn etic field s p rod u ced by th e m etal d etector stan d in g n ext to it. Doin g so m ay also lessen th e “h assle factor” with th e secu rity p erson n el becau se if I h ave th e com p u ter X-rayed , th ey often d o n ot req u ire th at I u n p ack it an d tu rn it on . Un fortu n ately, with th e greater em p h asis on airp ort secu rity th ese d ays, even wh en th e com p u ter is X-rayed , som e airlin es req u ire th at th e system be d em on strated (tu rn ed on ) an yway. Now you m ay n ot wan t to take m y word for it, bu t th ere h as been scien tific research p u blish ed th at corroborates wh at I h ave stated . A few years ago, a stu d y was p u blish ed by two scien tists, on e of wh om actu ally d esign s X-ray tu bes for a m ajor m an u factu rer. Th eir stu d y was titled “Airp ort X-rays an d flop p y d isks: n o cau se for con cern ,” an d was p u blish ed in 1993 in th e jou rn al Com puter Methods and Program s in Biom edicine. Accord in g to th e abstract, A con trolled stu d y was d on e to test th e p ossible effects of X-rays on th e in tegrity of d ata stored on com m on sizes of flop p y d isks. Disks were exp osed to d oses of X-rays u p to seven tim es th at to be exp ected d u rin g airp ort exam in ation of baggage. Th e read ability of n early 14 m egabytes of d ata was u n altered by X-irrad iation , in d icatin g th at flop p y d isks n eed n ot be given sp ecial h an d lin g d u rin g X-ray in sp ection of baggage.

Floppy Disk Drives

In fact, th e d isks were retested after two years of storage, an d th ere h as still been n o m easu rable d egrad ation sin ce th e exp osu re. Drive-Inst allat ion Procedures In m ost cases, in stallin g a flop p y d isk d rive is a m atter of attach in g th e d rive to th e com p u ter ch assis or case an d th en p lu ggin g th e p ower an d sign al cables in to th e d rive. Som e typ e of bracket an d screws are n orm ally req u ired to attach th e d rive to th e ch assis. Th ese are n orm ally in clu d ed with th e ch assis or case itself. Several com p an ies listed in Ap p en d ix A, “Ven d or List,” sp ecialize in cases, cables, brackets, screw h ard ware, an d oth er item s u sefu l in assem blin g system s or in stallin g d rives.

Not e Because floppy disk drives are generally installed into the same half-height bays as hard disk drives, the physical mounting of the drive in the computer case is the same for both units. See “ Hard Disk Installation Procedures,” earlier in this chapter, for more information on the process.

W h en you con n ect a d rive, m ake su re th e p ower cable is in stalled p rop erly. Th e cable is n orm ally keyed so you can n ot p lu g it in backward . Also, in stall th e d ata an d con trol cable. If th ere is n o key is in th is cable, u se th e colored wire in th e cable as a gu id e to th e p osition of p in 1. Th is cable is orien ted correctly wh en you p lu g it in so th e colored wire is p lu gged in to th e d isk d rive con n ector toward th e cu t-ou t n otch in th e d rive ed ge con n ector. Repairing Floppy Disk Drives Attitu d es abou t rep airin g flop p y d isk d rives h ave ch an ged over th e years, p rim arily becau se of th e d ecreasin g cost of d rives. W h en d rives were m ore exp en sive, p eop le often con sid ered rep airin g th e d rive rath er th an rep lacin g it. W ith th e cost of d rives d ecreasin g every year, h owever, certain labor- or p arts-in ten sive rep air p roced u res h ave becom e alm ost as exp en sive as rep lacin g th e d rive with a n ew on e. Becau se of cost con sid eration s, rep airin g flop p y d isk d rives u su ally is lim ited to clean in g th e d rive an d h ead s an d lu bricatin g th e m ech an ical m ech an ism s. Cleaning Floppy Disk Drives. Som etim es read an d write p roblem s are cau sed by d irty d rive h ead s. Clean in g a d rive is easy; you can p roceed in two ways: ■ Use on e of th e sim p le h ead -clean in g kits available from com p u ter- or office-su p p ly stores. Th ese d evices are easy to op erate an d d on ’t req u ire you to op en th e com p u ter case to access th e d rive. ■ Th e m an u al m eth od : Use a clean in g swab with a liq u id su ch as p u re alcoh ol or trich loroeth an e. W ith th is m eth od , you m u st op en th e system u n it to exp ose th e d rive an d , in m an y cases (esp ecially in earlier fu ll-h eigh t d rives), also rem ove an d p artially d isassem ble th e d rive. Th e m an u al m eth od can resu lt in a better overall job, bu t u su ally th e work req u ired is n ot worth th e d ifferen ce.

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Th e clean in g kits com e in two styles: Th e wet typ e u ses a liq u id sq u irted on a clean in g d isk to wash off th e h ead s; th e d ry kit relies on abrasive m aterial on th e clean in g d isk to rem ove h ead d ep osits. I recom m en d th at you n ever u se th e d ry d rive-clean in g kits. Always u se a wet system in wh ich a liq u id solu tion is ap p lied to th e clean in g d isk. Th e d ry d isks can p rem atu rely wear th e h ead s if u sed im p rop erly or too often ; wet system s are very safe to u se. Th e m an u al d rive-clean in g m eth od req u ires th at you h ave p h ysical access to th e h ead s to swab th em m an u ally with a lin t-free foam swab soaked in a clean in g solu tion . Th is m eth od req u ires som e level of exp ertise: Sim p ly jabbin g at th e h ead s in correctly with a clean in g swab m igh t kn ock th e d rive h ead s ou t of align m en t. You m u st u se a carefu l in an d -ou t m otion , an d ligh tly swab th e h ead s. No sid e-to-sid e m otion (relative to th e way th e h ead s travel) sh ou ld be u sed ; th is m otion can sn ag a h ead an d kn ock it ou t of align m en t. Becau se of th e d ifficu lty an d d an ger of th is m an u al clean in g, for m ost ap p lication s I recom m en d a sim p le wet-d isk clean in g kit becau se it is th e easiest an d safest m eth od . On e q u estion th at com es u p rep eated ly in m y sem in ars is “How often sh ou ld you clean a d isk d rive?” On ly you can an swer th at q u estion . W h at typ e of en viron m en t is th e system in ? Do you sm oke cigarettes n ear th e system ? If so, m ore freq u en t clean in g is req u ired . Usu ally, a safe ru le of th u m b is to clean d rives abou t on ce a year if th e system is in a clean office en viron m en t in wh ich n o sm oke or oth er p articu late m atter is in th e air. In a h eavy-sm okin g en viron m en t, you m igh t h ave to clean every six m on th s or p erh ap s even m ore often . In d irty in d u strial en viron m en ts, you m igh t h ave to clean every m on th or so. You r own exp erien ce is you r gu id e in th is m atter. If th e op eratin g system rep orts d rive errors su ch as th e fam iliar DOS Abort, Retry, Ignore p rom p t, you sh ou ld clean you r d rive to try to solve th e p roblem . If clean in g d oes solve th e p roblem , you p robably sh ou ld step u p th e in terval between p reven tive-m ain ten an ce clean in gs. In som e cases, you m igh t wan t to p lace a very sm all am ou n t of lu brican t on th e d oor m ech an ism or oth er m ech an ical con tact p oin t in sid e th e d rive. Do n ot u se oil; u se a p u re silicon e lu brican t. Oil collects d u st rap id ly after you ap p ly it an d u su ally cau ses th e oiled m ech an ism to gu m u p later. Silicon e d oes n ot attract d u st in th e sam e m an n er an d can be u sed safely. Use very sm all am ou n ts of silicon e; d o n ot d rip or sp ray silicon e in sid e th e d rive. You m u st m ake su re th at th e lu brican t is ap p lied on ly to th e p art th at n eed s it. If th e lu brican t gets all over th e in sid e of th e d rive, it m ay cau se u n n ecessary p roblem s. Aligning Floppy Disk Drives. If you r d isk d rives are m isalign ed , you will n otice th at oth er d rives can n ot read d isks created in you r d rive, an d you m igh t n ot be able to read d isks created in oth er d rives. Th is situ ation can be d an gerou s if you allow it to p rogress u n ch ecked . If th e m isalign m en t is bad en ou gh , you will p robably n otice it first in th e d rive’s in ability to read origin al ap p lication -p rogram d isks, wh ile still bein g able to read th e d isks you h ave created you rself. To solve th is p roblem , you can h ave th e d rive realign ed . I u su ally d on ’t recom m en d realign in g d rives becau se of th e low cost of rep lacin g th e d rive com p ared to align in g on e. Also, an u n foreseen circu m stan ce catch es m an y p eop le off-gu ard : You m igh t fin d th at you r n ewly align ed d rive m igh t n ot be able to read all th e d isks you created wh ile th e

Floppy Disk Drives

d rive was ou t of align m en t. If you rep lace th e m isalign ed d rive with a n ew on e an d keep th e m isalign ed d rive, you can u se it for DISKCOPY p u rp oses to tran sfer th e d ata to n ewly form atted d isks in th e n ew d rive. Align in g d isk d rives is u su ally n o lon ger p erform ed becau se of th e h igh relative cost. In th e p ast, align in g a d rive p rop erly req u ired access to an oscilloscop e (for abou t $500), a sp ecial an alog-align m en t d isk ($75), an d th e OEM service m an u al for th e d rive; also, you m u st sp en d h alf an h ou r to an h ou r align in g th e d rive. Som e p rogram s on th e m arket evalu ate th e con d ition of flop p y d isk d rives by u sin g a d isk created or form atted on th e sam e d rive. A p rogram th at u ses th is tech n iq u e can n ot m ake a p rop er evalu ation of a d isk d rive’s align m en t. To d o th is, you m u st u se a sp ecially created d isk p rod u ced by a tested an d calibrated m ach in e. You can u se th is typ e of d isk as a referen ce stan d ard by wh ich to ju d ge a d rive’s p erform an ce. Accu rite, th e p rim ary m an u factu rer of referen ce stan d ard flop p y d isks, h elp s sp ecify flop p y d isk in d u stry stan d ard s. Accu rite p rod u ces th e followin g th ree m ain typ es of referen ce stan d ard d isks u sed for testin g d rive fu n ction an d align m en t: ■ Digital Diagn ostic Diskette (DDD) ■ An alog Align m en t Diskette (AAD) ■ High -Resolu tion Diagn ostic Diskette (HRD) Th e HRD d isk, in trod u ced in 1989, rep resen ted a breakth rou gh in flop p y d isk d rive testin g an d align m en t. Th e d isk is accu rate to with in 50 µ-in ch es (m illion th s of an in ch )— accu rate en ou gh to u se n ot on ly for p recise testin g of flop p y d isk d rives, bu t also for align in g d rives. W ith software th at u ses th is HRD d isk, you can align a flop p y d isk d rive with ou t h avin g to u se sp ecial tools or an oscilloscop e. Oth er th an th e p rogram an d th e HRD d isk, you n eed on ly a PC to wh ich to con n ect th e d rive. Th is p rod u ct h as sign ifican tly lowered th e cost of align in g a flop p y d isk d rive an d h as elim in ated th e n eed for sp ecial test eq u ip m en t. Th e Accu rite p rogram Drive Probe is d esign ed to work with th e HRD d isks. Drive Probe is th e m ost accu rate an d cap able flop p y d isk testin g p rogram on th e m arket, th an ks to th e u se of HRD d isks. Un til oth er p rogram s u tilize th e HRD d isks for testin g, Drive Probe is m y software of ch oice for flop p y d isk d rive testin g an d align m en t. Becau se th e Drive Probe software also acts as a d isk exerciser, for u se with AAD d isks an d an oscilloscop e, you can m ove th e h ead s to sp ecific tracks for con trolled testin g. W ith th e p rice of m ost typ es of flop p y d isk d rives h overin g at or below th e $35 m ark, align in g d rives u su ally is n ot a cost-ju stified altern ative to rep lacem en t. Th e Drive Probe an d HRD system can m ake align m en t m ore cost-effective th an before, bu t it is still a labor- an d cost-in ten sive op eration . W eigh th is cost again st th e rep lacem en t cost an d age of th e d rive. I h ave p u rch ased bran d -n ew 1.44M flop p y d isk d rives for as low as $25. At th ese p rices, align m en t is n o lon ger a viable op tion .

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Rem ovable St orage Drives Th e reason for th e sh ortage of storage sp ace on tod ay’s PCs is easy en ou gh to u n d erstan d . Ju st take a look at th e sh eer n u m ber an d size of th e files stored in th e two m ain d irectories u sed by W in d ows 9x (u su ally C:\ W INDOW S an d C:\ W INDOW S\ SYSTEM). Th e am ou n t of d isk sp ace u sed by th e files in th ose two d irectories alon e can q u ickly balloon to 100M or m ore after you also in stall a few W in d ows ap p lication s. Th e reason is sim p le: Nearly all W in d ows ap p lication s p lace files in on e of th e W in d ows d irectories th at th e ap p lication will u se later. Th ese files in clu d e th ose with exten sion s like DLL, 386, VBX, DRV, TTF, an d m an y oth ers. Sim ilarly, W in d ows NT, OS/ 2, an d UNIX, as well as th e software ap p lication s th at ru n in th ese op eratin g system s, can req u ire en orm ou s am ou n ts of storage sp ace. Th is section focu ses on som e of th e m ore ad van ced d ata storage op tion s on th e m arket: rem ovable m ed ia large-cap acity cartrid ge d rives. Som e rem ovable m ed ia d rives u se m ed ia as sm all as a 3 1/ 2-in ch flop p y d isk, wh ile oth ers u se m ed ia abou t th e size of a 5 1/ 4-in ch flop p y. Th ese d rives, wh ose cap acities ran ge from 35M to 2G or m ore, offer fairly sp eed y p erform an ce, th e cap ability to store d ata or less freq u en tly u sed p rogram s on a rem ovable d isk, an d th e cap ability to easily tran sp ort h u ge d ata files—Com p u ter Aid ed Drawin g (CAD) files an d grap h ics files, for exam p le—from on e com p u ter to an oth er. Or, you can u se a rem ovable cartrid ge to take sen sitive d ata away from you r office so you can lock it safely away from p ryin g eyes.

Not e Removable media drives can also be used as system backup devices. However, the higher price of the medium itself (disks or cartridges) can make this use somewhat prohibitive.

Tip There are literally dozens of removable storage devices currently on the market. Be sure to compare your chosen solution against the competition before making a final purchase. Be especially wary of missing statistics in press releases and product packaging—manufacturers are apt to omit a specification if their drive doesn’t measure up to the competition.

Types of Rem ovable M edia Drives Th ere are two com m on ly u sed typ es of rem ovable m ed ia d rives: m agn etic m ed ia an d op tical m ed ia, also called m agneto-optical m edia. Magn etic m ed ia d rives u se tech n ology very m u ch like th at of a flop p y or h ard d isk d rive to en cod e d ata for storage. Magn etoop tical m ed ia d rives en cod e in form ation on d isk by u sin g n ewer tech n ology, a com bin ation of trad ition al m agn etic an d laser tech n ologies. Magn etic m ed ia d rives are con sid erably faster th an m agn eto-op tical d rives an d offer sim ilar cap acities. Th e Syq u est m agn etic m ed ia d rives, for exam p le, offer 14m s average access tim es, com p ared to th e 30m s (or slower) access tim es of m agn eto-op tical d rives.

Removable Storage Drives

Magn eto-op tical d rives can also be m ore th an twice as exp en sive as m agn etic m ed ia d rives. If you h ave a great d eal of d ata to store, h owever, th e com p arative cost of u sin g a m agn eto-op tical d rive d rop s becau se m agn eto-op tical m ed ia cartrid ges are con sid erably less exp en sive th an m agn etic m ed ia. For exam p le, 270M Syq u est cartrid ges can cost rou gh ly $40 each , wh ile 230M m agn eto-op tical cartrid ges can cost as little as $13 ap iece. Th ere are also several con n ection op tion s for th e lead in g rem ovable d rives. Alth ou gh SCSI h as been , an d con tin u es to be, a p op u lar solu tion , m an y d rives tod ay con n ect to th e com p u ter’s p arallel p ort. Th is op tion allows you to sh are on e d rive between several d ifferen t com p u ters, bu t th e p arallel p ort d rives gen erally p rovid e relatively p oor p erform an ce levels. Of cou rse, in tern al SCSI an d IDE solu tion s rem ain ju st as p op u lar for th e sin gle m ach in e in stallation .

Not e Connection and/ or installation of removable media drives is very similar to connecting and installing other internal and external peripherals. The installation of an external parallel port drive is the simplest of the available interfaces, requiring a special cable that comes with the drive and installation of special software drivers. See the instructions that come with each drive for the specifics of its installation.

Th e followin g section s p rovid e in form ation on m agn etic m ed ia an d m agn eto-op tical d rive typ es. M agnet ic M edia Drives A sm all grou p of com p an ies d om in ate th e m arket for m agn etic rem ovable m ed ia d rives. 3M’s sp in off com p an y Im ation , Iom ega, an d Syq u est are th e lead in g n am es in rem ovable m agn etic m ed ia d rives. Rem ovable m agn etic m ed ia d rives are u su ally flop p y or h ard d isk based . For exam p le, th e p op u lar Zip d rive is a 3 1/ 2-in ch version of th e origin al Bern ou lli flop p y d isk d rive m ad e by Iom ega. Th e n ew 3M LS-120 d rive is a flop p y-based d rive th at stores 120M on a d isk th at looks exactly like a 1.44M flop p y! Th e Syq u est d rive an d Iom ega Jaz d rive are both h ard d isk-based d esign s. Both th e Iom ega an d Syq u est d esign s are th eir own p rop rietary stan d ard , wh ile th e LS120 is a tru e in d u stry stan d ard su p p orted by m an y com p an ies. However, th e Iom ega Zip d rive is well on its way to becom in g a d e facto stan d ard in th e in d u stry. Man y of th e n ew PCs sold tod ay in clu d e a Zip d rive as stan d ard eq u ip m en t. Flopt ical Drives. Th ere is a sp ecial typ e of h igh -cap acity flop p y d isk d rive bein g m arketed by several com p an ies th at is called a floptical drive. Th ese d rives are u n iq u e in th at th ey can both read an d write stan d ard flop p y d isks as well as h igh er-cap acity flop tical d isks. A 21M version was origin ally available bu t m ore recen tly a 120M version h as becom e p op u lar, an d th e 21M version h as becom e obsolete. Th e old er 21M version was created by In site Perip h erals, an d p acked 21M of d ata on th e sam e size d isk as a 3 1/ 2in ch flop p y. More recen tly, 3M an d Matsu sh ita h ave in trod u ced a d rive called th e LS-120

797

798

Chapter 12—M agnetic Storage

th at can store 120M on a sin gle 3 1/ 2-in ch flop p y d isk! In ad d ition , all flop tical d rives can read an d write 1.44M an d 720K flop p y d isks (alth ou gh th ey can n ot h an d le 2.88M d isks). Becau se of th eir greatly in creased storage cap acity an d cap ability to u se com m on flop p y d isks, th e n ewer 120M flop ticals are con sid ered by m an y as th e p erfect rep lacem en t flop p y d isk d rive. Th e n am e “flop tical” m igh t su ggest th e u se of laser beam s to bu rn or etch d ata on to th e d isk or to excite th e m ed ia in p rep aration for m agn etic record in g—as is th e case with th e CD-R an d W rite On ce, Read Man y (W ORM) d rives, bu t th is su ggestion is erron eou s. Th e read / write h ead s of a flop tical d rive u se m agn etic record in g tech n ology, m u ch like th at of flop p y d isk d rives. Th e flop tical d isk itself is com p osed of th e sam e ferrite m aterials com m on to flop p y an d h ard d isks. Flop tical d rives are cap able of su ch in creased cap acity becau se m an y m ore tracks are p acked on each d isk, com p ared with a stan d ard 1.44M flop p y. Obviou sly, to fit so m an y tracks on th e flop tical d isk, th e tracks m u st be m u ch m ore n arrow th an th ose on a flop p y d isk. Th at’s wh ere op tical tech n ology com es in to p lay. Flop ticals u se a sp ecial op tical m ech an ism to p rop erly p osition th e d rive read / write h ead s over th e d ata tracks on th e d isk. Servo inform ation, wh ich sp ecifically d efin es th e location of each track, is em bed d ed in th e d isk d u rin g th e m an u factu rin g p rocess. Each track of servo in form ation is actu ally etch ed or stam p ed on th e d isk an d is n ever d istu rbed d u rin g th e record in g p rocess. Each tim e th e flop tical d rive writes to th e d isk, th e record in g m ech an ism (in clu d in g th e read / write h ead s) is gu id ed by a laser beam p recisely in to p lace by th is servo in form ation . W h en th e flop tical d rive read s th e en cod ed d ata, th e laser u ses th is servo in form ation again to gu id e th e read / write h ead s p recisely in to p lace. 2 1 M Fl o p t i c a l D ri v e s. Th e origin al In site 21M flop tical d isks u sed tracks form atted to 27 sectors of 512 bytes. Th e d isks revolved at 720 RPM. Flop ticals are cap able of n early 10M p er m in u te d ata th rou gh p u t, u sin g a SCSI in terface. Un fortu n ately, th e 21M d rives by In site n ever really cau gh t on d u e to several reason s. On e is th at n o lead in g m an u factu rer h as in clu d ed th ese d rives in a stan d ard con figu ration with bu ilt-in BIOS d rivers an d su p p ort. Also, Microsoft, IBM, an d Ap p le h ave n ot bu ilt su p p ort for th ese d rives d irectly in to th eir op eratin g system s. LS-1 2 0 (1 2 0 M) Fl o p t i c a l D ri v e s. Th e LS-120 d rive (also called a Su p erDisk d rive) was d esign ed to becom e th e n ew stan d ard flop p y d isk d rive in th e PC in d u stry. LS-120 tech n ology was d evelop ed by Im ation (3M) Corp oration , Matsu sh ita-Kotobu ki In d u stries, Ltd . (MKE), an d O.R. Tech n ology, an d stores 120M of d ata, or abou t 83 tim es m ore d ata th an cu rren t 1.44M flop p y d isks. In ad d ition to storin g m ore, th ese d rives read an d write at u p to five tim es th e sp eed of stan d ard flop p y d isk d rives. Th e LS-120 flop p y d isk d rive can act as th e PC’s bootable A: d rive an d is fu lly com p atible with W in d ows NT, W in d ows 95 OSR2, an d W in d ows 98. In ad d ition to th e n ew 120M flop p y d isks, th e LS-120 d rive accep ts stan d ard 720K an d 1.44M flop p y d isks, an d actu ally read s an d writes th ose d isks u p to th ree tim es faster th an stan d ard flop p y d isk d rives. Iom ega Zip d rives are n ot backward -com p atible an d can n ot u se existin g flop p y d isks; th e

Removable Storage Drives

p rop rietary Zip m ed ia stores less an d is m ore exp en sive th an th e 3M LS-120 m ed ia. Man y p eop le in th e com p u ter in d u stry believe th at LS-120 tech n ology will rep lace th e 1.44M flop p y d isk in n ew com p u ters. Th e LS-120 u ses th e stan d ard IDE in terface, wh ich is alread y bu ilt in to m ost existin g system s, an d it is p erfect for p ortable system s. Th e LS-120 p rovid es a solu tion th at n ot on ly rep laces th e existin g flop p y, bu t it can even rep lace th e flop p y d isk d rive in tern ally. Havin g on e of th ese h igh -cap acity d rives in a p ortable allows th e u se of th e relatively in exp en sive 120M rem ovable d isks wh ile on th e road . Th ey are p erfect for storin g en tire ap p lication s or d atasets an d can be rem oved an d secu red wh en th e p ortable system is n ot in u se. LS-120 sp ecification s are com p ared to stan d ard 1.44M flop p y d isks in Table 12.15. Table 12.15

LS-120 Specificat ions

Drive Type

LS-120 Floppy

St andard 1.44M Floppy Disk

Formatted Capacity

120M

1.44M

Transfer Rate: parallel port

290K/ sec

45K/ sec

Transfer Rate: internal IDE

484K/ sec

Not Applicable

Average seek time

70ms

84ms

Disk rotational speed

720 RPM

300 RPM

Track density

2,490 TPI

135 TPI

Number of tracks

1,736 X 2 sides

80 X 2 sides

Th e 3M LS-120 d isk h as th e sam e sh ap e an d size as a stan d ard 1.44M 3 1/ 2-in ch flop p y d isk; h owever, it u ses a com bin ation of m agn etic an d op tical tech n ology to en able greater cap acity an d p erform an ce. Nam ed after th e Laser Servo (LS) m ech an ism it em p loys, LS-120 tech n ology p laces op tical referen ce tracks on th e d isk th at are both written an d read by a laser system . Th e op tical sen sor in th e d rive en ables th e read -write h ead to be p recisely p osition ed over th e m agn etic d ata tracks, en ablin g track d en sities of 2,490 TPI versu s th e 135 TPI for a 1.44M flop p y d isk. Virtu ally all n ew PCs n ow com e with LS-120 su p p ort d irectly in th e BIOS, wh ich m ean s th at th ese d rives are n ot on ly easy to in stall, bu t th ey can d irectly rep lace th e A: flop p y d isk d rive an d are bootable, as well. Man y n ewer lap top system s com e with LS-120 d rives th at rep lace an d yet are fu lly com p atible with th e stan d ard flop p y d isk d rive. Un like Zip , you can in stall th e LS-120 in you r lap top an d leave th e stan d ard flop p y d isk d rive at h om e. Man y PC m an u factu rers are in corp oratin g LS-120 d rives in th eir p rod u cts as stan d ard eq u ip m en t. Besid es com in g in n ew system s, th ese d rives are also available sep arately at a cost of abou t $75 or less in in tern al or extern al version s for u p grad in g old er system s. Th e 120M flop p y d isks are available for abou t $10 p er d isk or less, alm ost h alf th e cost of th e p rop rietary Zip m ed ia. Rem ovable Cart ridge Drives. Back in th e early 1980s, Iom ega in trod u ced th e Bern ou lli d rive. Th e d isk u sed in th e origin al Bern ou lli d rive was a th ick cartrid ge rou gh ly th e sam e size as a 5 1/ 4-in ch flop p y d isk, alth ou gh a large sh u tter, sim ilar to th e sh u tter on a

799

800

Chapter 12—M agnetic Storage

3 1/ 2-in ch flop p y d isk, easily d ifferen tiated Bern ou lli d isks from stan d ard flop p y d isks. Bern ou lli cartrid ges were origin ally available in 10M cap acities, bu t th ose were rep laced by 35M, 65M, 105M, an d 150M cap acities. Bern ou lli d isks are wid ely kn own as th e m ost d u rable of th e rem ovable m ed ia d rive typ es. It is p robably safer to m ail a Bern ou lli cartrid ge th an an oth er typ e of rem ovable d isk becau se th e m ed ia is well-p rotected in sid e th e cartrid ge. Bern ou lli en cases a m agn etic-m ed ia-covered flexible d isk (in effect, a flop p y d isk) in a rigid cartrid ge in th e sam e way th e th in d isk of a 1.44M flop p y is en cased in a rigid p lastic sh ell. W h en it rotates in th e d rive, th e d isk is p u lled by air p ressu re toward th e d rive h ead s. Man y p eop le d o n ot th in k th at th ere is h ead -to-d isk con tact in a Bern ou lli d rive, bu t in d eed th ere is. As th e d isk sp in s, th e airflow gen erated by th e d isk m ovem en t en cou n ters wh at is called a Bernoulli plate, a station ary p late d esign ed to con trol th e air flow so th e d isk is p u lled toward th e read / write h ead . At fu ll sp eed , th e h ead d oes tou ch th e d isk, wh ich cau ses wear. Bern ou lli d rives h ave bu ilt-in ran d om seek fu n ction s th at p reven t an y sin gle track on th e d isk from wearin g excessively d u rin g p eriod s of in activity. Bern ou lli d isk cartrid ges sh ou ld be rep laced p eriod ically becau se th ey can wear ou t. Th e d isk itself sp in s at sp eed s ap p roach in g th e 3,600 RPM of relatively slow h ard d rives. Th e d rive h as an average seek tim e of 18m s, n ot a great d eal slower th an tod ay’s m ed iu m -p riced h ard d rives. Zi p D ri v e s. An oth er form of Bern ou lli d rive from Iom ega is th e p op u lar Zip d rive. Th is d evice is available as a in tern al SCSI or IDE u n it, or as an extern al SCSI or p arallel p ort d evice. Th ere is also a low-p ower version d esign ed for u se in n otebook com p u ters. Th e d rive is cap able of storin g u p to 100M of d ata on a sm all rem ovable m agn etic cartrid ge th at resem bles a 3 1/ 2-in ch flop p y d isk, an d h as ap p roxim ately a 29m s access tim e an d a 1M/ sec tran sfer rate wh en u sed with a SCSI con n ection . W h en u sin g th e p arallel con n ection , th e d rive’s sp eed is often lim ited by th e sp eed of th e p arallel p ort. Th e Zip d rives u se a p rop rietary 3 1/ 2-in ch d isk m ad e by Iom ega. It is abou t twice as th ick as a stan d ard 3 1/ 2-in ch flop p y d isk. Th e Zip d rives d o n ot accep t stan d ard 1.44M or 720K flop p y d isks, m akin g th is an u n likely can d id ate for a flop p y d isk d rive rep lacem en t. In tern al Zip d rives h ave becom e p op u lar op tion s in n ew PCs, an d th e extern al m od els are an effective solu tion for exch an gin g d ata between system s, bu t th e m ajor PC m an u factu rers h ave n ot recogn ized th e p rop rietary form at d irectly in th e system BIOS, m ean in g you can n ot boot from a Zip d rive, n or can it rep lace th e A: flop p y d isk d rive. Zip d rives h ave also su ffered from reliability p roblem s, su ch as th e so called “click d eath ,” wh ich occu rs wh en th e d rive begin s a rh yth m ic tickin g sou n d . At th is p oin t, th e d ata on th e d isk can be corru p ted an d both th e d rive an d th e m ed ia m u st be rep laced . Fin ally, th e m ed ia costs of Zip are alm ost d ou ble th at of th e h igh er-cap acity LS-120 d rives, wh ich are an in d u stry stan d ard fu lly su p p orted by th e system BIOS in m od ern PCs. Table 12.16 lists th e Zip sp ecification s.

Removable Storage Drives

Table 12.16

Zip Specificat ions

M odel ( Int erface)

SCSI and/ or Parallel

EIDE

Formatted Capacity

100 M

100 M

Sustained transfer rate maximum

1.40 M / sec

1.40 M / sec

Sustained transfer rate minimum

0.79 M / sec

0.79 M / sec

M aximum Throughput

60 M / min (SCSI); 20 M / min (parallel)

84M / min

Average seek time

29 msec

29 msec

Disk Rotational speed

2941 RPM

2941 RPM

Buffer size

32 K

16 K

Sy q u e st D ri v e s. Syq u est m an u factu res som e d rives th at u se 5 1/ 4-in ch cartrid ges an d oth ers th at u se 3 1/ 2-in ch cartrid ges. Bu t th e Syq u est d isks, like th e Bern ou lli cartrid ges, are easily d ifferen tiated from flop p y d isks. Th e 5 1/ 4-in ch 44M an d 88M cartrid ges u sed in som e SyDOS d rives are en cased in clear p lastic, as are th e SyDOS 3 1/ 2-in ch 105M an d Syq u est 270M cartrid ges. Th e d isk sp in s in sid e th e cartrid ge at several th ou san d RPM. Syq u est claim s a 14m s average access tim e for th e d rives it m an u factu res. Th e d isks for th e Syq u est an d SyDOS d rives are com p osed of a rigid p latter in sid e a p lastic cartrid ge bu t are n ot as well-p rotected as th e d isk in a Bern ou lli cartrid ge. Som e p eop le con sid er th ese d isks fragile. If th e Syq u est an d SyDOS cartrid ges are n ot severely jostled or d rop p ed , h owever, th ey can be tran sp orted safely. Th ese cartrid ges m u st be carefu lly p rotected wh en you m ail or sh ip th em . Th e Syq u est/ SyDOS d rives are available in in tern al an d extern al m od els. Th e in tern al m od els req u ire a con n ection to th e existin g IDE h ard d rive in terface card . Th e extern al m od els req u ire a SCSI in terface card with an extern al con n ector an d are p owered by a tran sform er th at con n ects to a grou n d ed AC wall p lu g. Ja z D ri v e s. An oth er typ e of rem ovable h ard d isk d rive is th e Jaz drive from Iom ega. Th is is p h ysically an d fu n ction ally id en tical to th e Syq u est d rives in th at it is a tru e rem ovable cartrid ge h ard d isk, excep t th at th e cap acity of th e cartrid ge h as been in creased ; 1G an d 2G m od els are available. Un fortu n ately, th e cartrid ges th em selves cost $100 to $125, wh ich is abou t seven tim es th e cost of a DAT (Digital Au d io Tap e) cartrid ge th at stores u p to fou r tim es m ore d ata! Th e h igh cost of th e m ed ia m akes th e Jaz d rive u n su itable for backu p wh en com p ared to trad ition al tap e m ed ia, bu t p ossibly u sefu l as an ad d -on extern al SCSI h ard d isk d rive. Table 12.17 lists th e sp ecification s for Jaz d rives. Table 12.17

Jaz Specificat ions

M odel

1 Gig

2 Gig

Formatted Capacity

1070 million bytes

2000 million bytes

M aximum

6.62 M / sec

8.7 M / sec

Average

5.4 M / sec

7.35 M / sec

Transfer rate:

(continues)

801

802

Chapter 12—M agnetic Storage

Table 12.17

Jaz Specificat ions Cont inued

M odel

1 Gig

2 Gig

M inimum

3.41 M / sec

3.41 M / sec

Burst

10 M / sec

20 M / sec

Average seek time read

10 msec

10 msec

Average seek time write

12 msec

12 msec

Access Time

15.5–17.5 msec

15.5–17.5 msec

Disk Rotational speed

5400 RPM

5394 RPM

Buffer size

256 K

512 K

Interface

Fast SCSI II

Ultra SCSI

Sp a rQ D ri v e s. Th e Sp arQ d rive is a rem ovable h ard d isk d rive by Syq u est th at is d esign ed to be a low-cost altern ative to oth er tech n ologies with sim ilar cap acities, su ch as th e Jaz an d th e SyJet. Th e m ed iu m is a p rop rietary cartrid ge con tain in g a sin gle d isk p latter with a 1G cap acity. At $99 for a th ree-p ack of cartrid ges, th e cost p er m egabyte of th e Sp arQ is su bstan tially less th an th at of com p arable rem ovable h ard d isk m ed ia, alth ou gh it still d oes n ot ap p roach th at of tap e or CD-R. Th e d rive is available in in tern al IDE an d extern al p arallel p ort version s. Th e p arallel p ort version , like all d rives u sin g th is in terface, is lim ited by th e th rou gh p u t of th e p ort itself, bu t th e IDE version of th e Sp arQ p rovid es d ata tran sfer rates th at are faster th an m ost com p etin g d rives. EIDE bu rst tran sfer rates can be as h igh as 16.6M/ sec by u sin g PIO m od e 4, with su stain ed rates ran gin g from 3.7 to 6.8M/ sec. Table 12.18 lists th e sp ecification s for th e Sp arQ d rive. Table 12.18

SparQ Specificat ions

Form at t ed Capacit y

1008 m illion byt es

Transfer rate: EIDE version M aximum

6.9 M / sec

M inimum

3.7 M / sec

Burst (PIO mode 4)

16.6 M / sec

Sustained Transfer rate: parallel version

1.25 M / sec

Average seek time

12 msec

Disk Rotational speed

5400 RPM

Com paring Rem ovable Drives. Decid in g on a rem ovable d rive is gettin g tou gh er, as th ere are m an y rem ovable d rives cu rren tly on th e m arket. Iom ega an d Syq u est lead th e p ack, bu t n ew en tries from Exabyte an d Avatar Perip h erals p rovid e th eir own p rop rietary d rives, as well. Un fortu n ately, all th ese d rives u se th eir own p rop rietary m ed ia th at are u n iversally in com p atible. If you wan t to exch an ge files with an oth er u ser, th ey m u st

Removable Storage Drives

h ave a d rive m ad e by th e sam e m an u factu rer. Th e ease of p ortability is on e reason wh y th e p arallel p ort m od els of m an y of th ese d rives are p op u lar. Table 12.19 sh ows a d irect com p arison between th e m ost p op u lar rem ovable d rives on th e m arket. Table 12.19 Drive Type

Rem ovable Drive Specificat ions Disk/ Cart ridge Capacit y

Average Seek Tim e

Dat a Transfer Rat e

100M

29ms

1.4M / sec

100M

29ms

1.4M / sec

100M

29ms

1.4M / sec

120M

70ms

4.0M / sec

235M

13.5ms

1.25M / sec

250M

12ms

1.2 M / sec

250M

12ms

2.0M / sec

235M

13.5ms

2.4M / sec

2G

12ms

5.4M / sec

250M

12ms

2.5M / sec

1.5G

12ms

5.3M / sec

1.5G

12ms

5.3M / sec

1G

12ms

6.9M / sec

Parallel

1G

12ms

1.25M / sec

CD-R Drives

650M

FFFFh

4-3-3

3Ah

Interval timer Channel 2 test or failure

4-3-4

3Bh

Time-of-day clock test or failure

4-4-1

3Ch

Serial port test or failure

4-4-2

3Dh

Parallel port test or failure

4-4-3

3Eh

M ath coprocessor test or failure

Low 1-1-2

41h

System board select failure

Low 1-1-3

42h

Extended CM OS RAM failure

POST Visual Error Codes. On m ost PCs, th e POST also d isp lays th e resu lts of its system m em ory test on th e m on itor. Th e last n u m ber d isp layed is th e am ou n t of m em ory th at tested su ccessfu lly. For exam p le, a system m igh t d isp lay th e followin g m essage: 32768 KB OK

Th e n u m ber d isp layed by th e m em ory test sh ou ld agree with th e total am ou n t of m em ory in stalled on th e system m oth erboard . Som e old er system s d isp lay a sligh tly lower total becau se th ey d ed u ct p art or all of th e 384K of UMA (Up p er Mem ory Area) from th e cou n t. On old system s th at u se exp an d ed m em ory card s, th e m em ory on th e card is n ot tested by th e POST an d d oes n ot cou n t in th e n u m bers rep orted . Also, th is m em ory test is p erform ed before an y system software load s, so m an y m em ory m an agers or d evice d rivers you m ay h ave in stalled d o n ot affect th e resu lts of th e test. If th e POST m em ory test stop s sh ort of th e exp ected total, th e n u m ber d isp layed can in d icate h ow far in to th e system m em ory array a m em ory error lies. Th is n u m ber can h elp you to id en tify th e exact m od u le th at is at fau lt an d can be a valu able trou blesh ootin g aid in itself. If an error is d etected d u rin g th e POST p roced u res, an error m essage m ay be d isp layed on screen . Th ese m essages u su ally are in th e form of a n u m eric cod e several d igits lon g; for exam p le, 1790-Disk 0 Error. You sh ou ld ch eck th e d ocu m en tation for you r m oth erboard or system BIOS for in form ation abou t th ese errors. Th e m ajor BIOS m an u factu rers also m ain tain W eb sites wh ere th is in form ation sh ou ld be available. I/ O Port POST Codes. A lesser-kn own featu re of th e POST is th at at th e begin n in g of each POST, th e BIOS sen d s test cod es to a sp ecial I/ O p ort ad d ress. Th ese POST cod es can be read on ly by a sp ecial ad ap ter card p lu gged in to on e of th e system slots. Th ese card s origin ally were d esign ed to be u sed by system m an u factu rers for bu rn -in testin g of th e

Diagnostics Software

m oth erboard , to p reven t th e n eed for a vid eo d isp lay ad ap ter an d d isp lay. Several com p an ies n ow m ake th ese card s available to tech n ician s. Micro 2000, JDR Microd evices, Data Dep ot, Ultra-X, an d Trin itech are ju st a few m an u factu rers th at m arket th ese POST card s. W h en you p lu g on e of th ese POST card s in to a slot, d u rin g th e POST you see two-d igit h exad ecim al n u m bers flash on th e card ’s d isp lay. If th e system stop s u n exp ected ly or h an gs, you can id en tify th e test in p rogress d u rin g th e h an g from th e two-d igit cod e. Th is step u su ally id en tifies th e m alfu n ction in g com p on en t. Most of th e system BIOSs on th e m arket in com p u ters with an ISA or EISA bu s ou tp u t th e POST cod es to I/ O p ort ad d ress 80h . Th e two m ost com m on typ es of POST card s are th ose th at p lu g in to th e 8-bit con n ector th at is a p art of th e ISA or EISA bu s, an d th ose th at p lu g in to th e MCA bu s. Som e com p an ies offer both typ es of POST card s—on e for MCA bu s system s an d on e for ISA/ EISA bu s system s. Micro 2000 an d Data Dep ot d o n ot offer a sep arate MCA bu s card ; rath er, th ey h ave slot ad ap ters th at en able th eir existin g ISA bu s card s to work in MCA bu s system s an d in ISA an d EISA system s. Most oth er com p an ies offer on ly ISA/ EISA POST card s an d ign ore th e MCA bu s, wh ich h as n ow been d iscon tin u ed . Th ere are also POST card s th at are d esign ed to work in PCI slots. Th ese will certain ly becom e m ore p revalen t as m ore PCI-on ly system s (n o ISA slots) com e on th e m arket. Th e POSTPlu s from ForeFron t Direct h as two ed ge con n ectors so it can be u sed in eith er an ISA or PCI slot. Th e POST I/ O p ort error cod es for variou s BIOSs are listed in th e 6th ed ition of th is book, located on th e CD. Hardw are Diagnost ics Th ere are m an y typ es of d iagn ostic software th at are in ten d ed for u se with sp ecific h ard ware p rod u cts. Th is software m ay be in tegrated in to th e h ard ware, in clu d ed with th e h ard ware p u rch ase, or sold as a sep arate p rod u ct. Th e followin g section s exam in e several d ifferen t typ es of h ard ware-sp ecific d iagn ostics.

Not e IBM includes specialized diagnostic software with their PCs that is designed for use by both end users and repair technicians. For more information on this software, see the 6th edition of “ Upgrading and Repairing PCs” on the CD-ROM included with this book.

SCSI Diagnost ics. Un like th e IDE d rive su p p ort th at is bu ilt in to th e system BIOS of virtu ally every PC, SCSI is an ad d -on tech n ology, an d m ost SCSI h ost ad ap ters con tain th eir own BIOS th at en ables you to boot th e system from a SCSI h ard d rive. In som e cases, th e SCSI BIOS also con tain s con figu ration software for th e ad ap ter’s variou s featu res, an d d iagn ostics software as well.

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Th e m ost p op u lar m an u factu rer of SCSI h ost ad ap ters is Ad ap tec, an d m ost of th eir h ost ad ap ters con tain th ese featu res. An Ad ap tec SCSI ad ap ter typ ically con tain s a ban k of eigh t DIP switch es n ext to th e extern al SCSI con n ector. Settin g switch es 6, 7, an d 8 to th e ON p osition en ables th e ad ap ter’s on board BIOS. W h en th e BIOS is activated , you see a m essage on th e m on itor as th e system boots, id en tifyin g th e m od el of th e ad ap ter an d th e revision n u m ber of th e BIOS. Th e m essage also in stru cts you to p ress CTRL-A to access wh at Ad ap tec calls its SCSISelect™ u tility. Th e SCSISelect u tility id en tifies th e Ad ap ter h ost ad ap ters in stalled in th e system , an d if th ere is m ore th an on e, en ables you to ch oose th e ad ap ter you wan t to work with by selectin g its p ort ad d ress. After you d o th is, you are p resen ted with a m en u of th e fu n ction s bu ilt in to th e ad ap ter’s BIOS. Every ad ap ter BIOS con tain s a con figu ration p rogram an d a SCSI Disk Utilities featu re th at scan s th e SCSI bu s, id en tifyin g th e d evices con n ected to it. For each h ard d isk d rive con n ected to th e bu s, you can p erform a low-level d isk form at or scan th e d isk for d efects, rem ap p in g an y bad blocks th at are fou n d . For SCSI ad ap ters th at u se DMA (Direct Mem ory Access), th ere is also a Host Ad ap ter Diagn ostics featu re th at tests th e com m u n ication between th e ad ap ter an d th e m ain system m em ory array by p erform in g a series of DMA tran sfers. If th is test sh ou ld fail, you are in stru cted h ow to con figu re th e ad ap ter to u se a lower DMA tran sfer rate. Net w ork Int erface Diagnost ics. As with SCSI ad ap ters, m an y n etwork in terface ad ap ters are eq u ip p ed with th eir own d iagn ostics, d esign ed to test th eir own sp ecialized fu n ction s. Th e EZSTART p rogram in clu d ed with all SMC n etwork in terface card s, for exam p le, con tain s two ad ap ter test m od es. Th e Basic m od e p erform s th e followin g in tern al tests on th e SMC8000 ad ap ter: ■ Bu s In terface Con troller Test ■ LAN Ad d ress ROM Test ■ Network In terface Con troller Test ■ RAM Test ■ ROM Test ■ In terru p t Gen eration ■ Loop back Test Th e Two Nod e test seq u en ce req u ires th at you h ave an oth er n od e in stalled on th e sam e n etwork with an SMC ad ap ter. By ru n n in g th e EZSTART software on both com p u ters, you can con figu re on e ad ap ter as th e Resp on d er an d th e oth er as th e In itiator. Th e In itiator tran sm its test m essages to th e Resp on d er th at ech oes th e sam e m essages back again . If th e ad ap ters an d th e n etwork are fu n ction in g p rop erly, th e m essages sh ou ld retu rn to th e In itiator system in exactly th e sam e form as th ey were tran sm itted . Oth er n etwork ad ap ters h ave sim ilar testin g cap abilities, alth ou gh th e n am es of th e tests m ay n ot be exactly th e sam e. Th e software for th e 3COM 3C509B ad ap ter, for exam p le, p erform s th e followin g tests:

Diagnostics Software

■ Register Access Test ■ EEPROM Vital Data Test ■ EEPROM Con figu rable Data Test ■ FIFO Loop back Test ■ In terru p t Test ■ Eth ern et Core Loop back Test ■ En cod er/ Decod er Loop back Test ■ Ech o Exch an ge Test (req u ires two ad ap ters on th e sam e n etwork) Both th e SMC an d 3COM d iagn ostics p rogram s are in tegrated in to th e software you u se to con figu re th e h ard ware resou rces u sed by th e ad ap ters an d th eir oth er featu res. Th e software is n ot in tegrated in to th e h ard ware; it takes th e form of a sep arate p rogram th at sh ip s with th e d evices an d th at you can also d own load free of ch arge from th e m an u factu rers’ resp ective W eb sites. General-Purpose Diagnost ics Program s A large n u m ber of th ird -p arty d iagn ostics p rogram s are available for PC system s. Sp ecific p rogram s are available also to test m em ory, flop p y d rives, h ard d isks, vid eo ad ap ters, an d m ost oth er areas of th e system . Alth ou gh som e of th ese u tility p ackages sh ou ld be con sid ered essen tial in an y toolkit, m an y fall sh ort of th e level n eed ed by p rofession al-level trou blesh ooters. Man y p rod u cts, geared m ore toward en d u sers, lack th e accu racy, featu res, an d cap abilities n eed ed by tech n ically p roficien t p eop le wh o are seriou s abou t trou blesh ootin g. Most of th e better d iagn ostics on th e m arket offer several ad van tages over en d -u ser p rod u cts. Th ey are u su ally better at d eterm in in g wh ere a p roblem lies with in a system , an d often in clu d e th e serial- an d p arallel-p ort loop back con n ectors th at are req u ired to p rop erly d iagn ose an d test serial an d p arallel p orts. Man y of th ese p rogram s can ru n in a batch m od e, wh ich en ables you to ru n a series of tests with ou t op erator in terven tion . You th en can set u p au tom ated test su ites, wh ich can be esp ecially u sefu l wh en bu rn in g in a system or execu tin g th e sam e tests on m an y system s. Th ese p rogram s test all typ es of m em ory, in clu d in g con ven tion al (base) m em ory, exten d ed m em ory, an d exp an d ed m em ory. Failu res can u su ally be id en tified d own to th e in d ivid u al m em ory ch ip or m od u le (SIMM or DIMM).

Tip Before trying a commercial diagnostic program to solve your problem, look in your operating system. M ost operating systems today provide at least some of the diagnostic functions that diagnostic programs do. You may be able to save some time and money. Operating system-based diagnostics are covered in Chapter 18, “ Operating Systems Software and Troubleshooting.”

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Un fortu n ately, th ere is n o clear lead er in th e area of d iagn ostic software. Each p rogram p resen ted h ere h as u n iq u e ad van tages. As a resu lt, n o p rogram is u n iversally better th an an oth er. W h en d ecid in g wh ich d iagn ostic p rogram s, if an y, to in clu d e in you r arsen al, look for th e featu res th at you n eed . AM IDiag. AMI (Am erican Megatren d s, In c.) is on e of th e largest m an u factu rers of PC ROM BIOS software tod ay. Th e AMI BIOS can be fou n d on m an y PCs, an d if you ’ve seen th e AMI BIOS, you kn ow th at m ost version s h ave a bu ilt-in d iagn ostic p rogram . Few p eop le kn ow, h owever, th at AMI also m arkets an en h an ced d isk-based version of th e sam e d iagn ostic software th at is bu ilt in to th e AMI ROM. AMIDiag, as th e p rogram is called , h as n u m erou s featu res an d en h an cem en ts n ot fou n d in th e sim p ler ROM version . AMIDiag is a com p reh en sive, gen eral-p u rp ose d iagn ostic th at is d esign ed for u se on an y PC, n ot ju st th ose with an AMI ROM BIOS. Regu larly u p d ated over th e years, AMIDiag’s exten sive rep ortin g an d d iagn ostics fu n ction s su p p ort virtu ally all th e latest h ard ware fou n d in PCs tod ay, in clu d in g th e latest MMX p rocessors, system s with m u ltip le (u p to 16) p rocessors, m em ory arrays u p to 4G in size, th e In tel Un iversal Serial Bu s con troller, SCSI d evices, PCI, Ad van ced Power Man agem en t, an d Plu g an d Play. AMIDiag also p rovid es an exten sive su ite of m u ltim ed ia d iagn ostics th at can isolate p roblem s with CD-ROM d rives, au d io ad ap ters, an d vid eo d isp lays, as well as m od em an d n etwork tests. Checkit Pro. Tou ch ston e Software Corp oration ’s Ch eckit p rod u cts offer an excellen t su ite of testin g cap abilities, in clu d in g tests of th e system CPU; con ven tion al, exten d ed , an d exp an d ed m em ory; h ard an d flop p y d rives; an d vid eo ad ap ter an d m on itor (in clu d in g VESA-Stan d ard card s an d m on itors, m ou se, an d keyboard ). Several version s of th e Ch eckit p rod u ct are available—Ch eckit Profession al Ed ition is th e com p an y’s m ost com p lete h ard ware d iagn ostic p rogram . Th e p ackage in clu d es Ch eckit version s for both W in d ows 9x an d DOS, Tou ch ston e’s PC-cillin an ti-viru s p rogram , an d loop back p lu gs for testin g p arallel an d serial p orts. Ch eckit Profession al Ed ition p rovid es ben ch m arkin g cap abilities an d d iagn ostic tests for m ost system com p on en ts, an d gives d etailed in form ation abou t you r system h ard ware su ch as total in stalled m em ory, h ard d rive typ e an d size, cu rren t m em ory allocation (in clu d in g u p p er m em ory u sage), IRQ availability an d u sage, m od em / fax m od em sp eed , an d a variety of oth er item s im p ortan t to som eon e trou blesh ootin g a PC. Th e p rod u ct also in clu d es a variety of featu res th at en able you to track th e state of you r op eratin g system , su ch as a u tility th at rep orts on ch an ges m ad e to im p ortan t system files an d a backu p an d restore ap p lication for th e W in d ows 9x Registry. Alth ou gh th e p ackage cen ters arou n d th e W in d ows 9x version of th e p rogram , th e in clu sion of th e DOS version is a th ou gh tfu l ad d ition , in case a system p roblem p reven ts you from load in g th e W in d ows in terface.

Diagnostics Software

M icro-Scope. Micro-Scop e by Micro 2000 is a fu ll-featu red , gen eral p u rp ose d iagn ostic p rogram for PC system s. It h as m an y featu res an d cap abilities th at can be very h elp fu l in trou blesh ootin g or d iagn osin g h ard ware p roblem s. Micro-Scop e h as a h ard ware in terru p t an d I/ O p ort ad d ress ch eck featu re th at is m ore accu rate th an th e sam e featu re in m ost oth er d iagn ostic software p rod u cts. It en ables you to accu rately id en tify th e in terru p t or I/ O p ort ad d ress th at a certain ad ap ter or h ard ware d evice in you r system is u sin g—a valu able cap ability in solvin g con flicts between ad ap ters. Som e u ser-level d iagn ostics p rogram s h ave th is featu re, bu t th e in form ation th ey rep ort can be grossly in accu rate, an d th ey often m iss item s in stalled in th e system . Micro-Scop e is p articu larly u sefu l becau se th e p rogram h as its own p rop rietary op eratin g system , byp assin g DOS, an d its tests can byp ass th e ROM BIOS wh en n ecessary. Th is elim in ates th e m askin g th at occu rs wh en th ese elem en ts op erate in between th e system h ard ware an d a d iagn ostics p rogram . For th is reason , th e p rogram is also u sefu l for PCs th at ru n oth er op eratin g system s, su ch as UNIX or Novell NetW are. For con ven ien ce, you can also in stall Micro-Scop e on a h ard d isk an d ru n it u n d er regu lar DOS. Like oth er d iagn ostics p ackages, Micro-Scop e is u p d ated regu larly to accom m od ate n ew h ard ware as it is released . Th e cu rren t version d etects an d tests th e latest p rocessors by In tel, AMD, an d Cyrix, an d th e latest m oth erboard an d vid eo BIOS releases. It also p rovid es su p p ort for h ard ware p erip h erals su ch as CD-ROM an d DVD-ROM d rives an d au d io ad ap ters. Micro-Scop e in clu d es d isk rep air tools, su ch as a sector ed itor th at can ed it an d rep air th e m aster an d volu m e boot sectors on a h ard d isk d rive. Micro-Scop e com es com p lete with th e serial an d p arallel p ort loop back p lu gs th at you n eed to com p letely an d accu rately test th ese d evices. A loop back p lu g is a wireless m od u le th at attach es to th e p ort an d d iverts all th e sign als tran sm itted th rou gh th e p ort’s ou tp u ts righ t back to its in p u ts. W ith testin g software like th at in clu d ed in Micro-Scop e, you can verify th at every elem en t of a p arallel or serial p ort is op eratin g p rop erly. Fin ally, Micro 2000 offers excellen t telep h on e tech n ical su p p ort. Its op erators d o m u ch m ore th an exp lain h ow to op erate th e software—th ey h elp you with real trou blesh ootin g p roblem s. Th is in form ation is au gm en ted by good d ocu m en tation an d on lin e h elp bu ilt in to th e software so th at, in m an y cases, you d on ’t h ave to refer to th e m an u al. Nort on Ut ilit ies Diagnost ics. W h en you con sid er th at Norton Diagn ostics (NDIAGS) com es with th e Norton Utilities, an d th at Norton Utilities is alread y an essen tial collection of system d ata safegu ard in g, trou blesh ootin g, testin g, an d rep airin g u tilities, NDIAGS p robably is on e of th e best valu es in d iagn ostic p rogram s. Th e cu rren t version s of Norton Utilities are 8.0 for th e DOS/ W in d ows version an d 3.0 for th e W in d ows 95 version . If you d on ’t alread y h ave Norton Utilities, you ’ll wan t to stron gly con sid er th is p ackage, n ot on ly for NDIAGS, bu t also for th e oth er u tilities su ch as Sp eed isk, Disk Doctor, an d Calibrate. Th ese th ree h ard d rive u tilities basically rep resen t th e state of th e art in h ard d rive d iagn ostics an d software-level rep air. SYSINFO still h an d les ben ch m arkin g for th e Norton Utilities, an d it d oes as good a job as an y oth er d iagn ostic p ackage on th e m arket.

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NDIAGS ad d s d iagn ostic cap abilities th at p reviou sly were n ot p rovid ed by th e Norton Utilities, in clu d in g com p reh en sive in form ation abou t th e overall h ard ware con figu ration of you r system —th e CPU, system BIOS, m ath cop rocessor, vid eo ad ap ter, keyboard an d m ou se typ e, h ard an d flop p y d rive typ es, am ou n t of in stalled m em ory, bu s typ e, an d th e n u m ber of serial an d p arallel p orts. Un like som e oth er p rogram s, loop back p lu gs d o n ot com e in th e box for NDIAGS, bu t a cou p on is in clu d ed th at en titles you to free p lu gs by m ail. Note th at th is p rogram u ses loop back p lu gs th at are wired sligh tly d ifferen tly from th ose u sed by m ost oth er p rogram s. Th e d ifferen t wirin g en ables you to ru n som e ad d ition al tests. Fortu n ately, th e d ocu m en tation in clu d es a d iagram for th ese p lu gs, wh ich you can u se to m ake you r own if you d esire. NDIAGS th orou gh ly tests th e m ajor system com p on en ts an d en ables you to ch eck m in or d etails su ch as th e Nu m Lock, Cap sLock, an d ScrollLock LEDs on you r keyboard . NDIAGS also p rovid es an on screen grid you can u se to cen ter th e im age on you r m on itor an d test for variou s kin d s of d istortion th at m ay in d icate a fau lty m on itor. PC Technician. PC Tech n ician by W in d sor Tech n ologies was on e of th e first PC d iagn ostics p rod u cts on th e m arket in 1984, an d sin ce th en , it h as been h igh ly refin ed an d con tin u ou sly u p d ated to reflect th e ch an gin g PC m arket. PC Tech n ician is a fu ll-featu red com p reh en sive h ard ware d iagn ostic an d trou blesh ootin g tool, an d tests all m ajor areas of a system . Like several of th e oth er m ore cap able p rogram s, PC Tech n ician h as its own op eratin g system th at isolates it from p roblem s cau sed by software con flicts. Th e p rogram is written in assem bly lan gu age an d h as d irect access to th e h ard ware in th e system for testin g. Th is p rogram also in clu d es all th e loop back p lu gs n eed ed for testin g serial an d p arallel p orts. PC Tech n ician h as lon g been a favorite with field service com p an ies wh o eq u ip th eir tech n ician s with th e p rod u ct for trou blesh ootin g. Th is p rogram was d esign ed for th e p rofession al service tech n ician ; h owever, it is easy for th e am ateu r to u se. As a bon u s, PC Tech n ician costs m u ch less th an m an y of th e oth er p rogram s in its class. PC Tech n ician is d eliberately d esign ed to con cen trate on th e basic PC h ard ware, an d in clu d es a large battery of d iagn ostic tests for p rocessors, m em ory, d isk d rives, I/ O p orts, an d vid eo ad ap ters. You will n ot fin d tests for m u ltim ed ia d evices an d oth er p erip h erals in PC Tech n ician , bu t you will fin d core system testin g cap abilities th at m eet or exceed th e oth er p rod u cts d escribed in th is section , in m ost areas. Alth ou gh PC Tech n ician is d esign ed for th e PC h ard ware p rofession al, W in d sor also h as a p rod u ct called PC-Diagn osys th at is geared m ore toward th e en d u ser. PC-Diagn osys in clu d es m an y of th e sam e tests an d featu res as PC Tech n ician , bu t lacks th e loop back testin g an d som e of th e m ore ad van ced featu res of th e larger p rod u ct. W in d sor also h as a low-en d d iagn ostic p rod u ct called #1-Tu ffTEST in both en d -u ser an d p rofession al version s th at you can d own load from th e com p an y’s W eb site for a low fee. QAPlus/ FE. QAPlu s/ FE by Diagsoft is an ad van ced d iagn ostic p rogram for In tel-based com p u ters. Its testin g is th orou gh , an d its m en u -based in terface m akes it easy to u se,

Diagnostics Software

even for som eon e wh o is n ot p articu larly exp erien ced with d iagn osin g p roblem s with p erson al com p u ters. QAPlu s/ FE also in clu d es som e of th e m ost accu rate system ben ch m arks you can get, wh ich can be u sed to fin d ou t if th at n ew system you are th in kin g of bu yin g is really th at m u ch faster th an th e on e you alread y h ave. More im p ortan tly, QAPlu s/ FE com es on bootable 3 1/ 2- an d 5 1/ 4-in ch d isks th at (regard less of you r op eratin g system ) can start th e com p u ter system wh en p roblem s are so severe th at you r system h ard ware can n ot even fin d th e h ard d rive. Man y p eop le alread y h ave a less com p reh en sive version of th is p rogram called QAPlu s, wh ich is orien ted toward en d u sers. Th e basic QAPlu s version is often in clu d ed with system s sold by a n u m ber of d ifferen t PC system ven d ors. Alth ou gh th e sim p le QAPlu s p rogram is okay, th e fu ll-blown QAPlu s/ FE (Field En gin eer) version is m u ch better for seriou s trou blesh ootin g. QAPlu s/ FE can test you r m oth erboard , system RAM, vid eo ad ap ter, h ard d rive, flop p y d rives, CD-ROM d rive, m ou se, keyboard , p rin ter, an d p arallel an d serial p orts (th e QAPlu s/ FE p ackage in clu d es loop back p lu gs for fu ll testin g of th ese p orts). QAPlu s/ FE also p rovid es exh au stive in form ation on you r system con figu ration , in clu d in g th e h ard ware in stalled on you r system , its CPU, an d th e total am ou n t of RAM in stalled on you r system . It p rovid es fu ll in terru p t m ap p in g—cru cial wh en in stallin g n ew ad ap ter board s an d oth er h ard ware d evices—an d gives you a fu ll p ictu re of th e d evice d rivers an d oth er p rogram s load ed in m em ory, as well as oth er in form ation abou t DOS an d system m em ory u se. QAPlu s/ FE also in clu d es variou s oth er u tilities th at are m ore likely to ap p eal to th e seriou s PC trou blesh ooter th an to th e average PC u ser. Th ese sp ecial cap abilities in clu d e a CMOS ed itor th at can be u sed to ch an ge system d ate an d tim e, th e h ard d rive typ e, in stalled m em ory size, an d oth er CMOS in form ation ; a COM p ort d ebu gger; a h ard d rive test an d low-level form attin g u tility; a flop p y d rive test u tility; an d a con figu ration file ed itor. Th e p rod u ct also in clu d es a rem ote system com m u n ication h ost p rogram th at en ables service p eop le with th e fu ll rem ote p ackage to op erate you r com p u ter via m od em . Un like som e d iagn ostics p rogram s, QAPlu s/ FE h as a system bu rn -in cap ability, m ean in g it can be u sed to ru n you r system n on -stop u n d er a fu ll load of com p u tation s an d h ard ware activity for th e p u rp ose of d eterm in in g wh eth er an y system com p on en t is likely to fail in real life u se. Man y p eop le u se a bu rn -in u tility wh en th ey receive a n ew system , an d th en again ju st before th e warran ty ru n s ou t. A tru e system bu rn -in u su ally lasts 48– 72 h ou rs, or even lon ger. You can con figu re th e am ou n t of tim e th at QAPlu s/ FE will bu rn in a system by settin g th e n u m ber of tim es th at th e selected tests are to ru n . Operat ing Syst em Diagnost ics In m an y cases, it m ay n ot be n ecessary to p u rch ase th ird -p arty d iagn ostic software, becau se you r op eratin g system h as all th e d iagn ostic tools you n eed . W in d ows 95, 98, an d NT in clu d e a large selection of p rogram s th at en able you to view, m on itor, an d trou blesh oot th e h ard ware in you r system . Th e followin g section s exam in e som e of th ese tools an d th eir fu n ction s.

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M icrosoft Diagnost ics ( M SD) . MS-DOS 6.x, W in d ows 3.1, an d W in d ows for W orkgrou p s all in clu d e a basic tool called Microsoft Diagn ostics (MSD). MSD is a sim p le, DOS-based p rogram th at d isp lays in form ation abou t you r system h ard ware. Design ed in 1993 for u se with th ese old er op eratin g system s, h owever, MSD d oes n ot recogn ize m u ch of th e n ew h ard ware in u se tod ay, su ch as Pen tiu m p rocessors. Alth ou gh MSD h as garn ered a rep u tation for in correctly id en tifyin g certain h ard ware, su ch as th e UART ch ip s in PC serial p orts an d th e in terru p t u sage listin g, it is on e of th e best tools for id en tifyin g m em ory u sage in th e Up p er Mem ory Area—a com m on sou rce of con flicts between ad d -on ad ap ter card s. It is also q u ite u sefu l for d ocu m en tin g th e version n u m bers of th e system BIOS, Vid eo BIOS, an d oth er d rivers. MSD also sh ip s on th e W in d ows 9x CD-ROM, alth ou gh it is som ewh at h id d en an d is n ot au tom atically in stalled d u rin g th e W in d ows setu p p roced u re. You can cop y MSD from th e CD-ROM d irectly to you r h ard d rive an d ru n it from an y DOS p rom p t. It d oes p rovid e better in form ation , h owever, if you first sh u t d own W in d ows an d ch oose Restart th e com p u ter in MS-DOS Mod e. W indow s 9x Device M anager. W in d ows 9x’s Device Man ager is a far m ore u sefu l h ard ware in ven tory tool th an MSD. W h en you select th e Device Man ager p age from th e System Con trol Pan el, you see an exp an d able list of th e typ es of d evices fou n d in th e system (see Figu re 17.1). Exp an d in g each typ e d isp lays th e actu al h ard ware in stalled in th e com p u ter. Each en try h as a Prop erties d ialog box th at en ables you to con figu re th e d evice, view th e h ard ware resou rces th at it is u sin g, an d u p d ate its d river.

FIG. 17.1 Th e W in d ows 9x Device Man ager. By clickin g th e View Devices By Con n ection op tion bu tton , th e d isp lay is sorted by th e com p u ter’s variou s p orts an d in terfaces. An oth er lesser-kn own featu re of th e Device Man ager is th at wh en you d ou ble-click th e Com p u ter en try at th e top of th e list, you see th e Com p u ter Prop erties d ialog box,

Diagnostics Software

sh own in Figu re 17.2. From th is d ialog box, you can exam in e all th e IRQs, I/ O p orts, DMA ch an n els, an d m em ory ad d resses in you r system , an d th e d evices th at are u sin g th em .

FIG. 17.2

Th e Com p u ter Prop erties d ialog box.

In cases wh ere W in d ows 9x’s Plu g-an d -Play featu re can n ot assign system resou rces for you , th e Device Man ager is an excellen t tool for resolvin g d evice con flicts. Th e Prop erties d ialog box for each d evice d isp lays th e resou rces su p p orted by th at p articu lar d evice an d in d icates wh eth er oth er d evices are alread y u sin g th ose resou rces, an d wh ich resou rces th e d evice h ard ware is con figu red to u se. W indow s 9x Resource M et er. Th e W in d ows 9x Resou rce Meter lau n ch es as an icon in th e tray area of th e toolbar. Th is ap p lication con tin u ou sly m on itors th e W in d ows 9x system , u ser, an d GDI (grap h ics d evice in terface) resou rces. As you load m ore p rogram s an d op en m ore win d ows, th e icon in th e tray in d icates th e d im in ish in g available resou rces in th e system by growin g sm aller. W h en you d ou ble-click th e tray icon , you see a m ore d etailed p resen tation , as sh own in Figu re 17.3.

FIG. 17.3 Th e W in d ows 9x Resou rce Meter. Syst em M onit or/ Perform ance M onit or. Th e W in d ows 9x System Mon itor an d th e W in d ows NT Perform an ce Mon itor p erform rou gh ly th e sam e fu n ction . Both p rogram s track sp ecific elem en ts of a system ’s p erform an ce an d d isp lay th em in a grap h ical form at, as sh own in Figu re 17.4. By d efau lt, you can ch oose to d isp lay variou s statistics p ertain in g to th e com p u ter’s kern el, m em ory m an ager, file system , an d oth er core fu n ction s.

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FIG. 17.4 Th e W in d ows 9x System Mon itor. Both of th ese p rogram s, h owever, are exten sible. In stallin g ad d ition al ap p lication s an d services on th e com p u ter can ad d n ew categories of statistics. For exam p le, in stallin g a NetW are clien t on th e system ad d s a collection of statistics regard in g in com in g an d ou tgoin g traffic gen erated by th at clien t. Syst em Inform at ion and Diagnost ics. W in d ows 98’s System In form ation p rogram is an excellen t ad d ition to th e op eratin g system th at p rovid es an exten sive p rofile of th e com p u ter’s h ard ware an d software, rivalin g som e of th e best th ird -p arty p rod u cts on th e m arket (see Figu re 17.5). An d , alth ou gh it u ses a d ifferen t d isp lay form at, W in d ows NT Diagn ostics p rovid es m u ch of th e sam e in form ation . Th ese p rogram s en able you to save, exp ort, or p rin t th e in form ation th ey d iscover, m akin g it a sim p le m atter to d ocu m en t th e en tire con figu ration of a W in d ows 98 or W in d ows NT system in great d etail. If you sh ou ld ever h ave to rein stall th e op eratin g system d u e to a d isk failu re or oth er m alfu n ction , h avin g th is in form ation h an d y can sim p lify th e p rocess con sid erably. W indow s NT Event View er. Th e Even t Viewer is W in d ows NT’s p rim ary system m essage an d loggin g tool. W h en ever a sign ifican t even t occu rs in on e of th ree areas—system op eration , secu rity, or ap p lication execu tion —it is en tered in to on e of th ree sep arate logs.

PC M aintenance Tools

FIG. 17.5 W in d ows 98 System In form ation .

PC M aint enance Tools To trou blesh oot an d rep air PC system s p rop erly, you n eed a few basic tools. If you in ten d to trou blesh oot an d rep air PCs p rofession ally, th ere are m an y m ore sp ecialized tools you will wan t to p u rch ase. Th ese ad van ced tools en able you to m ore accu rately d iagn ose p roblem s an d m ake jobs easier an d faster. Th e basic tools th at sh ou ld be in every trou blesh ooter’s toolbox are ■ Sim p le h an d tools for basic d isassem bly an d reassem bly p roced u res, in clu d in g a flat blad e an d Ph illip s screwd rivers (both m ed iu m an d sm all sizes), tweezers, an IC extraction tool, an d a p arts grabber or hem ostat ■ Diagn ostics software an d h ard ware for testin g com p on en ts in a system ■ A m u ltim eter th at p rovid es accu rate m easu rem en ts of voltage an d resistan ce ■ Ch em icals, su ch as con tact clean ers, com p on en t freeze sp rays, an d com p ressed air for clean in g th e system ■ Foam swabs, or lin t-free cotton swabs if foam isn ’t available ■ Sm all wire ties for “d ressin g” or organ izin g wires

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Som e en viron m en ts m ay also h ave th e resou rces to p u rch ase th e followin g d evices, alth ou gh th ey’re n ot req u ired for m ost work: ■ Mem ory testin g m ach in es, u sed to evalu ate th e op eration of SIMMs (Sin gle In lin e Mem ory Mod u les), DIMMs (Du al In lin e Mem ory Mod u les), DIP (Du al In lin e Pin ) ch ip s, an d oth er m em ory m od u les ■ Serial an d p arallel loop back (or wrap ) p lu gs to test serial an d p arallel p orts ■ A n etwork cable scan n er (if you work with n etworked PCs) ■ A serial breakou t box (if you u se system s th at op erate over serial cables, su ch as UNIX d u m b term in als) In ad d ition , an exp erien ced trou blesh ooter will p robably wan t to h ave sold erin g an d d esold erin g tools to fix bad serial cables. Th ese tools are d iscu ssed in m ore d etail in th e followin g section s. Hand Tools W h en you work with PC system s, th e tools req u ired for n early all service op eration s are sim p le an d in exp en sive. You can carry m ost of th e req u ired tools in a sm all p ou ch . Even a top -of-th e-lin e “m aster m ech an ics” set fits in sid e a briefcase-size con tain er. Th e cost of th ese tool kits ran ges from abou t $20 for a sm all service kit to $500 for on e of th e briefcase-size d elu xe kits. Com p are th ese costs with wh at m igh t be n ecessary for an au tom otive tech n ician . An au tom otive service tech n ician wou ld h ave to sp en d $5,000 to $10,000 or m ore for a com p lete set of tools. Not on ly are PC tools m u ch less exp en sive, bu t I can tell you from exp erien ce th at you d on ’t get n early as d irty workin g on com p u ters as you d o workin g on cars. In th is section , you learn abou t th e tools req u ired to assem ble a kit th at is cap able of p erform in g basic, board -level service on PC system s. On e of th e best ways to start su ch a set of tools is to p u rch ase a sm all kit sold esp ecially for servicin g PCs. Th e followin g list sh ows th e basic tools th at you can fin d in on e of th e sm all PC tool kits th at sell for abou t $20. ■ 3/ 16-in ch n u t d river ■ 1/ 4-in ch n u t d river ■ Sm all Ph illip s screwd river ■ Sm all flat-blad e screwd river ■ Med iu m Ph illip s screwd river ■ Med iu m flat-blad e screwd river ■ Ch ip extractor

PC M aintenance Tools

■ Ch ip in serter ■ Tweezers ■ Claw-typ e p arts grabber ■ T10 an d T15 Torx d rivers

Not e Some tools aren’t recommended because they are of limited use. However, they normally come with these types of kits.

You u se n u t d rivers to rem ove th e h exagon al-h ead ed screws th at secu re th e system -u n it covers, ad ap ter board s, d isk d rives, an d p ower su p p lies in m ost system s. Th e n u t d rivers work m u ch better th an con ven tion al screwd rivers. Becau se som e m an u factu rers h ave su bstitu ted slotted or Ph illip s-h ead screws for th e m ore stan d ard h exagon al-h ead screws, stan d ard screwd rivers can be u sed for th ose system s.

Caut ion When working in a cramped environment such as the inside of a computer case, screwdrivers with magnetic tips can be a real convenience, especially for retrieving that screw you dropped into the case. However, although I have used these types of screwdrivers many times with no problems, you must be aware of the damage that a magnetic field can cause to memory chips and magnetic storage devices such as hard drives and floppy disks. Laying the screwdriver down on or near a floppy or working too close to a hard drive can damage the data on the disk.

Ch ip -extraction an d in sertion tools are rarely n eed ed th ese d ays, becau se m em ory ch ip s are m ou n ted on SIMMs or DIMMs an d p rocessors u se ZIF (Zero Insertion Force) sockets or oth er u ser-frien d ly con n ectors. Th e ZIF socket h as a lever th at, wh en raised , releases th e grip on th e p in s of th e ch ip , allowin g you to easily lift it ou t with you r fin gers. However, if you work with old er system s, you m u st u se a ch ip extractor (see Figu re 17.6) to in stall or rem ove m em ory ch ip s (or oth er sm aller ch ip s) with ou t ben d in g an y p in s on th e ch ip . Usu ally, you p ry ou t larger ch ip s, su ch as m icrop rocessors or ROMs, with th e sm all screwd river. Larger p rocessors req u ire a ch ip extractor if th ey are m ou n ted in th e old er LIF (Low Insertion Force) socket. Th ese ch ip s h ave so m an y p in s on th em th at a large am ou n t of force is req u ired to rem ove th em , d esp ite th e fact th at th ey call th e socket “low in sertion force.” If you u se a screwd river on a large p h ysical size ch ip su ch as a 486, you risk crackin g th e case of th e ch ip an d p erm an en tly d am agin g it. Th e ch ip extractor tool for rem ovin g th ese ch ip s h as a very wid e en d with tin es th at fit between th e p in s on th e ch ip to d istribu te th e force even ly alon g th e ch ip ’s u n d ersid e. Th is will m in im ize th e likelih ood of breakage. Most of th ese typ es of extraction tools m u st be p u rch ased sp ecially for th e ch ip you ’re tryin g to rem ove.

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FIG. 17.6 Th e ch ip extractor wou ld be u sed to rem ove an in d ivid u al RAM or ROM ch ip from a socket bu t it wou ld n ot be u sefu l for a larger p rocessor.

Th e tweezers an d p arts grabber can be u sed to h old an y sm all screws or ju m p er blocks th at are d ifficu lt to h old in you r h an d . Th e p arts grabber (see Figu re 17.7) is esp ecially u sefu l wh en you d rop a sm all p art in to th e in terior of a system ; u su ally, you can rem ove th e p art with ou t com p letely d isassem blin g th e system .

FIG. 17.7 Th e p arts grabber h as th ree sm all m etal p ron gs th at can be exten d ed to grab a p art.

PC M aintenance Tools

Fin ally, th e Torx d river is a sp ecial, star-sh ap ed d river th at m atch es th e sp ecial screws fou n d in m ost Com p aq system s an d in m an y oth er system s as well. You can also p u rch ase tam p erp roof Torx d rivers th at can rem ove Torx screws with th e tam p er-resistan t p in in th e cen ter of th e screw. A tam p erp roof Torx d river h as a h ole d rilled in it to allow clearan ce for th e p in . Alth ou gh th is basic set is u sefu l, you sh ou ld su p p lem en t it with som e oth er sm all h an d tools, su ch as: ■ Need len ose p liers

■ Vise or clam p

■ Hem ostat

■ File

■ W ire cu tter or wire strip p er

■ Sm all flash ligh t

Pliers are u sefu l for straigh ten in g p in s on ch ip s, ap p lyin g or rem ovin g ju m p ers, crim p in g cables, or grabbin g sm all p arts. Hem ostats are esp ecially u sefu l for grabbin g sm all com p on en ts, su ch as ju m p ers. Th e wire cu tter or strip p er, obviou sly, is u sefu l for m akin g or rep airin g cables or wirin g. You can u se a vise to in stall con n ectors on cables, to crim p cables to th e sh ap e you wan t, an d to h old p arts d u rin g d elicate op eration s. In ad d ition to th e vise, Rad io Sh ack sells a n ifty “extra h an d s” d evice th at h as two m ovable arm s with alligator clip s on th e en d . Th is typ e of d evice is very u sefu l for m akin g cables or for oth er d elicate op eration s wh ere an extra set of h an d s to h old som eth in g m igh t be u sefu l. You can u se th e file to sm ooth rou gh m etal ed ges on cases an d ch assis an d to trim th e facep lates on d isk d rives for a p erfect fit. You m ay often n eed a flash ligh t to illu m in ate system in teriors, esp ecially wh en th e system is cram p ed an d th e room ligh tin g is n ot good , or wh en you are workin g on a system u n d ern eath a u ser’s d esk. I con sid er th is tool to be essen tial. An oth er con sid eration for you r tool kit is an ESD (electrostatic discharge) protection kit. Th is kit con sists of a wrist strap with a grou n d wire an d a sp ecially con d u ctive m at with its own grou n d wire. Usin g a kit like th is wh en workin g on a system will h elp en su re th at you n ever accid en tally d am age an y of th e com p on en ts with a static d isch arge.

Not e You can work without an ESD protection kit, if you’re disciplined and careful about working on systems. If you don’t have an ESD kit available, you should discharge yourself by touching some metallic part of the case while the computer is still plugged in to the AC power source, and then unplug the computer. M any systems today continue to feed power to the motherboard through the soft off connection whenever the computer is plugged in, even when the power switch is turned off. It can be very dangerous to work inside a PC that is still connected to a power source.

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Th e ESD kits, as well as all th e oth er tools an d m u ch m ore, are available from a variety of tool ven d ors. Sp ecialized Prod u cts Com p an y an d Jen sen Tools are two of th e m ost p op u lar ven d ors of com p u ter an d electron ic tools an d of service eq u ip m en t. Th eir catalogs sh ow an exten sive selection of very h igh -q u ality tools. (Th ese com p an ies an d several oth ers are listed in Ap p en d ix A, “Ven d or List.”) W ith a sim p le set of h an d tools, you will be eq u ip p ed for n early every PC rep air or in stallation situ ation . Th e total cost of th ese tools sh ou ld be less th an $150, wh ich is n ot m u ch con sid erin g th e cap abilities th ey give you . A W ord About Hardw are Th is section d iscu sses som e p roblem s th at you m ay en cou n ter with th e h ard ware (screws, n u ts, bolts, an d so on ) u sed in assem blin g a system . Types of Hardw are. On e of th e biggest aggravation s th at you en cou n ter in d ealin g with variou s system s is th e d ifferen t h ard ware typ es an d d esign s th at h old th e u n its togeth er. For exam p le, m ost system s u se screws th at fit 1/ 4-in ch or 3/ 16-in ch h exagon al n u t d rivers. IBM u sed th ese screws in all its origin al PC, XT, an d AT system s, an d m ost oth er system m an u factu rers u se th is stan d ard h ard ware as well. Som e m an u factu rers u se d ifferen t h ard ware, h owever. Com p aq , for exam p le, u ses Torx screws exten sively in m an y of its system s. A Torx screw h as a star-sh ap e h ole d riven by th e correct-size Torx d river. Th ese d rivers carry size d esign ation s su ch as T-8, T-9, T-10, T-15, T-20, T-25, T-30, an d T-40. A variation on th e Torx screw is th e tam p erp roof Torx screw fou n d in p ower su p p lies an d oth er assem blies. Th ese screws are id en tical to th e regu lar Torx screws, excep t th at a p in sticks u p from th e m id d le of th e star-sh ap e h ole in th e screw. Th is p in p reven ts th e stan d ard Torx d river from en terin g th e h ole to grip th e screw; a sp ecial tam p erp roof d river with a corresp on d in g h ole for th e p in is req u ired . An altern ative is to u se a sm all ch isel to kn ock ou t th e p in in th e screw. Usu ally, a d evice th at is sealed with th ese typ es of screws is con sid ered to be a rep laceable u n it th at rarely, if ever, n eed s to be op en ed . Man y m an u factu rers also u se th e m ore stan d ard slotted -h ead an d Ph illip s-h ead screws. Usin g tools on th ese screws is relatively easy, bu t tools d o n ot grip th ese fasten ers as well as h exagon al h ead or Torx screws d o, an d th e h ead s can be strip p ed m ore easily th an th e oth er typ es. Extrem ely ch eap version s ten d to lose bits of m etal as th ey’re tu rn ed with a d river, an d th e m etal bits can fall on to th e m oth erboard . Stay away from ch eap fasten ers wh en ever p ossible; th e h ead ach es of d ealin g with strip p ed screws aren ’t worth it. Som e system m an u factu rers n ow u se cases th at sn ap togeth er or u se th u m b screws. Th ese are u su ally ad vertised as “n o-tool” cases becau se you literally d o n ot n eed an y tools to take off th e cover an d access th e m ajor assem blies. A com p an y called Cu rtis sells sp ecial n ylon p lastic th u m b screws th at fit m ost n orm al cases an d can be u sed to rep lace th e existin g screws to m ake op en in g th e case a n o-tool p rop osition . However, you sh ou ld still always u se m etal screws to in stall in tern al com p on en ts su ch as ad ap ter card s, d isk d rives, p ower su p p lies, an d th e m oth erboard becau se th e m etal screws p rovid e a grou n d p oin t for th ese d evices.

PC M aintenance Tools

English Versus M et ric. An oth er area of aggravation with h ard ware is th e fact th at th ere are two typ es of th read system s: En glish an d m etric. IBM u sed m ostly En glish -th read ed fasten ers in its origin al lin e of system s—bu t m an y oth er m an u factu rers u sed m etricth read ed fasten ers. Th e d ifferen ce between th e two becom es esp ecially ap p aren t with d isk d rives. Am erican m an u factu red d rives typ ically u se En glish fasten ers, wh ereas d rives m ad e in Jap an or Taiwan u su ally u se m etric. W h en ever you rep lace a flop p y d rive in an old er PC, you en cou n ter th is p roblem . Try to bu y th e correct screws an d an y oth er h ard ware, su ch as brackets, with th e d rive, becau se th ey m ay be d ifficu lt to fin d as sep arate item s. Man y d rive m an u factu rers offer retail d rive kits th at in clu d e all th e req u ired m ou n tin g com p on en ts. Th e OEM’s d rive m an u al lists th e correct d ata abou t a sp ecific d rive’s h ole location s an d th read size. Hard d isks can u se eith er En glish or m etric fasten ers; ch eck you r p articu lar d rive to see wh ich typ e it u ses. Most d rives tod ay u se m etric h ard ware.

Caut ion Some screws in a system may be length-critical, especially screws that are used to retain hard disk drives. You can destroy some hard disks by using a mounting screw that’s too long; the screw can puncture or dent the sealed disk chamber when you install the drive and fully tighten the screw. When you install a new drive in a system, always make a trial fit of the hardware to see how far the screws can be inserted into the drive before they interfere with its internal components. When you’re in doubt, the drive manufacturer’s OEM documentation will tell you precisely what screws are required and how long they should be.

Soldering and Desoldering Tools In certain situ ation s—su ch as rep airin g a broken wire, m akin g cables, reattach in g a com p on en t to a circu it board , rem ovin g an d in stallin g ch ip s th at are n ot in a socket, or ad d in g ju m p er wires or p in s to a board —you m u st u se a sold erin g iron to m ake th e rep air. Alth ou gh virtu ally all rep airs th ese d ays are d on e by sim p ly rep lacin g th e en tire failed board , an d m an y PC tech n ician s n ever tou ch a sold erin g iron , you m ay fin d on e u sefu l in som e situ ation s. Th e m ost com m on case wou ld be wh ere th ere was p h ysical d am age to a system , su ch as wh en som eon e rip s th e keyboard con n ector off of a m oth erboard by p u llin g on th e cable im p rop erly. Sim p le sold erin g skills can save th e m oth erboard in th is case. Most m oth erboard s th ese d ays in clu d e I/ O com p on en ts su ch as serial an d p arallel p orts. Man y of th ese p orts are fu se-p rotected on th e board ; h owever, th e fu se is u su ally a sm all sold ered -in com p on en t. Th ese fu ses are d esign ed to p rotect th e m oth erboard circu its from bein g d am aged by an extern al sou rce. If a sh ort circu it or static ch arge from an extern al d evice blows th ese fu ses, th e m oth erboard can be saved if you can rep lace th em . To p erform m in or rep airs su ch as th ese, you n eed a low-wattage sold erin g iron —u su ally, abou t 25 watts. More th an 30 watts gen erates too m u ch h eat an d can d am age th e com p on en ts on th e board . Even with a low-wattage u n it, you m u st lim it th e am ou n t of h eat

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to wh ich you su bject th e board an d its com p on en ts. You can d o th is with q u ick an d efficien t u se of th e sold erin g iron an d with th e u se of h eat-sin kin g d evices clip p ed to th e lead s of th e d evice bein g sold ered . A heat sink is a sm all m etal clip -on d evice d esign ed to absorb excessive h eat before it reach es th e com p on en t th at th e h eat sin k is p rotectin g. In som e cases, you can u se a p air of h em ostats as an effective h eat sin k wh en you sold er a com p on en t. To rem ove com p on en ts th at are sold ered in to p lace on a p rin ted circu it board , you can u se a sold erin g iron with a solder sucker. Th is d evice n orm ally takes th e form of a sm all tu be with an air ch am ber an d a p lu n ger-an d -sp rin g arran gem en t. (I d o n ot recom m en d th e sq u eeze-bu lb typ e of sold er su cker.) Th e u n it is “cocked ” wh en you p ress th e sp rin gload ed p lu n ger in to th e air ch am ber. W h en you wan t to rem ove a d evice from a board , you u se th e sold erin g iron from th e u n d ersid e of th e board , an d h eat th e p oin t at wh ich on e of th e com p on en t lead s join s th e circu it board u n til th e sold er m elts. As soon as m eltin g occu rs, m ove th e sold er-su cker n ozzle in to p osition , an d p ress th e actu ator. W h en th e p lu n ger retracts, it creates a m om en tary su ction th at d raws th e liq u id sold er away from th e con n ection an d leaves th e com p on en t lead d ry in th e h ole. Always d o th e h eatin g an d su ction in g from th e u n d ersid e of a board , n ot from th e com p on en t sid e. Rep eat th is action for every com p on en t lead join ed to th e circu it board . W h en you m aster th is tech n iq u e, you can rem ove a sm all com p on en t in a m in u te or two with on ly a sm all likelih ood of d am age to th e board or oth er com p on en ts. Larger ch ip s th at h ave m an y p in s can be m ore d ifficu lt to rem ove an d resold er with ou t d am agin g oth er com p on en ts or th e circu it board .

Tip These procedures are intended for Through-Hole devices only. These are components whose pins extend all the way through holes in the board to the underside. Surface mount devices are removed with a completely different procedure, using much more expensive tools. Working on surface-mounted components is beyond the capabilities of all but the most well-equipped shops.

If you in ten d to ad d sold erin g an d d esold erin g skills to you r arsen al of abilities, you sh ou ld p ractice. Take a u seless circu it board an d p ractice rem ovin g variou s com p on en ts from th e board ; th en , rein stall th e com p on en ts. Try to rem ove th e com p on en ts from th e board by u sin g th e least am ou n t of h eat p ossible. Also, p erform th e sold er-m eltin g op eration s as q u ickly as p ossible, lim itin g th e tim e th at th e iron is ap p lied to th e join t. Before you in stall an y com p on en ts, clean ou t th e h oles th rou gh wh ich th e lead s m u st p roject an d m ou n t th e com p on en t in p lace. Th en , ap p ly th e sold er from th e u n d ersid e of th e board , u sin g as little h eat an d sold er as p ossible. Attem p t to p rod u ce join ts as clean as th e join ts th at th e board m an u factu rer p rod u ced by m ach in e. Sold ered join ts th at d o n ot look clean m ay keep th e com p on en t from m akin g a good con n ection with th e rest of th e circu it. Th is “cold -sold er join t” is n orm ally created becau se you h ave n ot u sed en ou gh h eat. Rem em ber that you should not practice your new soldering skills on the m otherboard of a system that you are attem pting to repair! Don ’t at-

PC M aintenance Tools

tem p t to work on real board s u n til you are su re of you r skills. I always keep a few ju n k board s arou n d for sold erin g p ractice an d exp erim en tation .

Tip When first learning to solder, you may be tempted to set the iron on the solder and leave it there until the solder melts. If the solder doesn’t melt immediately when applying the iron to it, you’re not transferring the heat from the iron to the solder efficiently. This means that either the iron is dirty, or there is debris between it and the solder. To clean the iron, take a wet sponge and drag it across the tip of the iron. If after cleaning the iron there’s still some resistance, try to scratch the solder with the iron when it’s hot. Generally, this removes any barriers to heat flow and will instantly melt the solder.

No m atter h ow good you get at sold erin g an d d esold erin g, som e jobs are best left to p rofession als. Com p on en ts th at are su rface-m ou n ted to a circu it board , for exam p le, req u ire sp ecial tools for sold erin g an d d esold erin g, as d o oth er com p on en ts th at h ave h igh p in d en sities. Test Equipm ent In som e cases, you m u st u se sp ecialized d evices to test a system board or com p on en t. Th is test eq u ip m en t is n ot exp en sive or d ifficu lt to u se, bu t it can ad d m u ch to you r trou blesh ootin g abilities. Elect rical Test ing Equipm ent . I con sid er a voltm eter to be req u ired gear for p rop er system testin g. A m ultim eter can serve m an y p u rp oses, in clu d in g ch eckin g for voltage sign als at d ifferen t p oin ts in a system , testin g th e ou tp u t of th e p ower su p p ly, an d ch eckin g for con tin u ity in a circu it or cable. An ou tlet tester is an in valu able accessory th at can ch eck th e electrical ou tlet for p rop er wirin g. Th is cap ability is u sefu l if you believe th at th e p roblem lies ou tsid e th e com p u ter system . Loopback Connect ors ( W rap Plugs) . For d iagn osin g serial- an d p arallel-p ort p roblem s, you n eed loop back con n ectors (also called wrap plugs), wh ich are u sed to circu late, or wrap , sign als. Th e p lu gs en able th e serial or p arallel p ort to sen d d ata to itself for d iagn ostic p u rp oses. Differen t typ es of loop back con n ectors are available. To accom m od ate all th e p orts you m igh t en cou n ter, you will n eed on e for th e 25-p in serial p ort, on e for th e 9-p in serial p ort, an d on e for th e 25-p in p arallel p ort. Man y com p an ies, in clu d in g IBM, sell th e p lu gs sep arately, bu t be aware th at you also n eed d iagn ostic software th at can m ake u se of th em . Som e d iagn ostic software p rod u cts, su ch as Micro 2000’s Micro-Scop e, in clu d e loop back con n ectors with th e p rod u ct. IBM sells a sp ecial com bin ation p lu g th at in clu d es all th ree con n ector typ es in on e com p act u n it. Th e d evice costs ap p roxim ately $30 from IBM. If you ’re h an d y, you can even m ake you r own wrap p lu gs for testin g. I in clu d e wirin g d iagram s for th e th ree typ es of wrap p lu gs in Ch ap ter 10, “I/ O In terfaces.” In th at ch ap ter, you also will fin d a d etailed d iscu ssion of serial an d p arallel p orts.

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Besid es sim p le loop back con n ectors, you m ay also wan t to h ave a breakout box for you r toolkit. A breakou t box is a DB25 con n ector d evice th at en ables you to m ake cu stom tem p orary cables or even to m on itor sign als on a cable. For m ost PC trou blesh ootin g u ses, a “m in i” breakou t box works well an d is in exp en sive. M et ers. Som e trou blesh ootin g p roced u res req u ire th at you m easu re voltage an d resistan ce. You take th ese m easu rem en ts by u sin g a h an d h eld Digital Mu lti-Meter (DMM). Th e m eter can be an an alog d evice (u sin g an actu al m eter) or a d igital-read ou t d evice. Th e DMM h as a p air of wires called test leads or probes. Th e test lead s m ake th e con n ection s so th at you can take read in gs. Dep en d in g on th e m eter’s settin g, th e p robes m easu re electrical resistan ce, d irect-cu rren t (DC) voltage, or altern atin g-cu rren t (AC) voltage. Usu ally, each system -u n it m easu rem en t settin g h as several ran ges of op eration . DC voltage, for exam p le, u su ally can be read in several scales, to a m axim u m of 200 m illivolts (m v), 2v, 20v, 200v, an d 1,000v. Becau se com p u ters u se both +5v an d +12v for variou s op eration s, you sh ou ld u se th e 20v m axim u m scale for m akin g you r m easu rem en ts. Makin g th ese m easu rem en ts on th e 200m v or 2v scale cou ld “p eg th e m eter” an d p ossibly d am age it, becau se th e voltage wou ld be m u ch h igh er th an exp ected . Usin g th e 200v or 1,000v scale works, bu t th e read in gs at 5v an d 12v are so sm all in p rop ortion to th e m axim u m th at accu racy is low. If you are takin g a m easu rem en t an d are u n su re of th e actu al voltage, start at th e h igh est scale an d work you r way d own . Most of th e better m eters h ave au toran gin g cap ability— th e m eter au tom atically selects th e best ran ge for an y m easu rem en t. Th is typ e of m eter is m u ch easier to op erate. You ju st set th e m eter to th e typ e of read in g you wan t, su ch as DC volts, an d attach th e p robes to th e sign al sou rce. Th e m eter selects th e correct voltage ran ge an d d isp lays th e valu e. Becau se of th eir d esign , th ese typ es of m eters always h ave a d igital d isp lay rath er th an a m eter n eed le.

Caut ion Whenever using a multimeter to test any voltage that could potentially be 110v or above, always use one hand to do the testing, not two. Either clip one lead to one of the sources and probe with the other, or hold both leads in one hand. If you are holding a lead in each hand and accidentally slip, you can very easily become a circuit, allowing power to conduct or flow through you. When the power is flowing from arm to arm, the path of the current is directly across the heart. Hearts have a tendency to quit working when subjected to high voltages. They’re funny that way.

I p refer th e sm all d igital m eters; you can bu y th em for on ly sligh tly m ore th an th e an alog style, an d th ey’re extrem ely accu rate an d m u ch safer for d igital circu its. Som e of th ese m eters are n ot m u ch bigger th an a cassette tap e; th ey fit in a sh irt p ocket. Rad io Sh ack sells a good u n it (m ad e for Rad io Sh ack by Beckm an ) in th e $25 p rice ran ge; th e m eter is a h alf-in ch th ick, weigh s 3 1/ 2 ou n ces, an d is d igital an d au toran gin g, as well. Th is typ e of m eter works well for m ost, if n ot all, PC trou blesh ootin g an d test u ses.

PC M aintenance Tools

Caut ion You should be aware that many analog meters can be dangerous to digital circuits. These meters use a 9v battery to power the meter for resistance measurements. If you use this type of meter to measure resistance on some digital circuits, you can damage the electronics, because you essentially are injecting 9v into the circuit. The digital meters universally run on 3–5v or less.

Logic Probes and Logic Pulsers. A logic probe can be u sefu l for d iagn osin g p roblem s in d igital circu its. In a digital circuit, a sign al is rep resen ted as eith er h igh (+5v) or low (0v). Becau se th ese sign als are p resen t for on ly a sh ort tim e (m easu red in m illion th s of a secon d ) or oscillate (switch on an d off) rap id ly, a sim p le voltm eter is u seless. A logic p robe is d esign ed to d isp lay th ese sign al con d ition s easily. Logic p robes are esp ecially u sefu l for trou blesh ootin g a d ead system . By u sin g th e p robe, you can d eterm in e wh eth er th e basic clock circu itry is op eratin g an d wh eth er oth er sign als n ecessary for system op eration are p resen t. In som e cases, a p robe can h elp you cross-ch eck th e sign als at each p in on an In tegrated Circu it ch ip . You can com p are th e sign als p resen t at each p in with th e sign als th at a kn own -good ch ip of th e sam e typ e wou ld sh ow—a com p arison th at is h elp fu l in isolatin g a failed com p on en t. Logic p robes can also be u sefu l for trou blesh ootin g som e d isk d rive p roblem s by en ablin g you to test th e sign als p resen t on th e in terface cable or d rive-logic board . A com p an ion tool to th e p robe is th e logic p u lser. A pulser is d esign ed to test circu it reaction by d eliverin g a logical h igh (+5v) p u lse in to a circu it, u su ally lastin g 1 1/ 2–10 m illion th s of a secon d . Com p are th e reaction with th at of a known-functional circuit. Th is typ e of d evice n orm ally is u sed m u ch less freq u en tly th an a logic p robe, bu t in som e cases, it can be h elp fu l for testin g a circu it. Out let Test ers. Outlet testers are very u sefu l test tools. Th ese sim p le, in exp en sive d evices, sold in h ard ware stores, are u sed to test electrical ou tlets. You sim p ly p lu g th e d evice in , an d th ree LEDs ligh t in variou s com bin ation s, in d icatin g wh eth er th e ou tlet is wired correctly. Alth ou gh you m ay th in k th at bad ly wired ou tlets wou ld be a rare p roblem , I h ave seen a large n u m ber of in stallation s in wh ich th e ou tlets were wired in correctly. Most of th e tim e, th e p roblem is in th e grou n d wire. An im p rop erly wired ou tlet can resu lt in u n stable system op eration , su ch as ran d om p arity ch ecks an d locku p s. W ith an im p rop er grou n d circu it, cu rren ts can begin flowin g on th e electrical grou n d circu its in th e system . Becau se th e system u ses th e voltage on th e grou n d circu its as a com p arative sign al to d eterm in e wh eth er bits are 0 or 1, a floatin g grou n d can cau se d ata errors in th e system . On ce, wh ile ru n n in g on e of m y PC trou blesh ootin g sem in ars, I was u sin g a system th at I literally cou ld n ot ap p roach with ou t lockin g it u p . W h en ever I walked p ast th e system , th e electrostatic field gen erated by m y bod y in terfered with th e system , an d th e PC locked u p , d isp layin g a p arity-ch eck error m essage. Th e p roblem was th at th e h otel at wh ich I was givin g th e sem in ar was very old an d h ad n o grou n d ed ou tlets in th e room . Th e on ly way I cou ld p reven t th e system from lockin g u p was to ru n th e class in m y stockin g feet, becau se m y leath er-soled sh oes were gen eratin g th e static ch arge.

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Chapter 17—Diagnostics, Testing, and M aintenance

Oth er sym p tom s of bad grou n d wirin g in electrical ou tlets are con tin u ou s electrical sh ocks wh en you tou ch th e case or ch assis of th e system . Th ese sh ocks in d icate th at voltages are flowin g wh ere th ey sh ou ld n ot be. Th is p roblem can also be cau sed by bad or im p rop er grou n d s with in th e system . By u sin g th e sim p le ou tlet tester, you can q u ickly d eterm in e wh eth er th e ou tlet is at fau lt. If you ju st walk u p to a system an d receive an in itial sh ock, it’s p robably ju st static electricity. Tou ch th e ch assis again with ou t m ovin g you r feet. If you receive an oth er sh ock, th ere is som eth in g very wron g. In th is case, th e grou n d wire actu ally h as voltage ap p lied to it. You sh ou ld h ave a p rofession al electrician ch eck th e ou tlet im m ed iately. If you d on ’t like bein g a h u m an rat in an electrical exp erim en t, you can test th e ou tlets with you r m u ltim eter. First, rem em ber to h old both lead s in on e h an d . Test from on e blad e h ole to an oth er. Th is sh ou ld read between 110–125v d ep en d in g u p on th e electrical service in th e area. Th en ch eck from each blad e to th e grou n d (th e rou n d h ole). On e blad e h ole, th e sm aller on e, sh ou ld sh ow a voltage alm ost id en tical to th e on e th at you got from th e blad e h ole to blad e h ole test. Th e larger blad e h ole wh en m easu red to grou n d sh ou ld sh ow less th an 0.5v. Becau se grou n d an d n eu tral are su p p osed to be tied togeth er at th e electrical p an el, a large d ifferen ce in th ese read in gs in d icates th at th ey are n ot tied togeth er. However, sm all d ifferen ces can be accou n ted for by cu rren t from oth er ou tlets d own th e lin e flowin g on th e n eu tral, wh en th ere isn ’t an y on th e grou n d . If you d on ’t get th e resu lts you exp ect, call an electrician to test th e ou tlets for you . More weird com p u ter p roblem s are cau sed by im p rop er grou n d in g an d oth er p ower p roblem s th an p eop le like to believe. M em ory Test ers. I n ow con sid er a m em ory test m ach in e an all bu t m an d atory p iece of eq u ip m en t for an yon e seriou s abou t p erform in g PC trou blesh ootin g an d rep air as a p rofession . Th e tester is a sm all d evice d esign ed to evalu ate SIMMs, DIMMs, an d oth er typ es of m em ory m od u les, in clu d in g in d ivid u al ch ip s su ch as th ose u sed as cach e m em ory. Th ese testers can be som ewh at exp en sive, costin g u p ward s of $1,000 to $2,500, bu t th ese m ach in es are th e on ly tru ly accu rate way to test m em ory. W ith ou t on e of th ese testers, you are red u ced to testin g m em ory by ru n n in g a d iagn ostic p rogram on th e PC an d testin g th e m em ory as it is in stalled . Th is can be very p roblem atic, as th e m em ory d iagn ostic p rogram can on ly d o two th in gs to th e m em ory—write an d read . A SIMM tester can d o m an y th in gs th at a m em ory d iagn ostic ru n n in g in a PC can n ot d o, su ch as: ■ Id en tify th e typ e of m em ory ■ Id en tify th e m em ory sp eed ■ Id en tify wh eth er th e m em ory h as p arity, or is u sin g bogu s p arity em u lation ■ Vary th e refresh tim in g an d access sp eed tim in g ■ Locate sin gle bit failu res

Preventive M aintenance

■ Detect p ower- an d n oise-related failu res ■ Detect sold er op en s an d sh orts ■ Isolate tim in g-related failu res ■ Detect d ata reten tion errors No con ven tion al m em ory d iagn ostic software can d o th ese th in gs becau se it h as to rely on th e fixed access p aram eters set u p by th e m em ory con troller h ard ware in th e m oth erboard ch ip set. Th is p reven ts th e software from bein g able to alter th e tim in g an d m eth od s u sed to access th e m em ory. You m ay h ave m em ory th at fails in on e system an d works in an oth er wh en th e ch ip s are actu ally bad . Th is typ e of in term itten t p roblem is alm ost im p ossible to d etect with d iagn ostic software. Th e bottom lin e is th at th ere is n o way th at you can test m em ory with tru e accu racy wh ile it is in stalled in a PC; a m em ory tester is req u ired for com p reh en sive an d accu rate testin g. Alth ou gh th e p rice of a typ ical 32M m em ory m od u le m ay be less th an $50, th e p rice of a m em ory tester can be ju stified very easily in a sh op en viron m en t wh ere a lot of PCs are tested , as m an y software an d h ard ware u p grad es tod ay req u ire th e ad d ition of n ew m em ory. W ith th e large in creases in th e am ou n t of m em ory in tod ay’s system s an d stricter tim in g req u irem en ts of n ewer m oth erboard d esign s, it h as becom e even m ore im p ortan t to be able to id en tify or ru le ou t m em ory as a cau se of system failu re. On e of th e m em ory testers I recom m en d th e m ost is th e SIGMA LC by Darkh orse System s. See th e ven d or list in Ap p en d ix A for m ore in form ation . Also see Ch ap ter 5, “Mem ory,” for m ore in form ation on m em ory in gen eral.

Prevent ive M aint enance Preven tive m ain ten an ce is th e key to obtain in g years of trou ble-free service from you r com p u ter system . A p rop erly ad m in istered p reven tive m ain ten an ce p rogram p ays for itself by red u cin g p roblem beh avior, d ata loss, com p on en t failu re, an d by en su rin g a lon g life for you r system . In several cases, I h ave “rep aired ” an ailin g system with n oth in g m ore th an a p reven tive m ain ten an ce session . Preven tive m ain ten an ce can also in crease you r system ’s resale valu e becau se it will look an d ru n better. Develop in g a p reven tive m ain ten an ce p rogram is im p ortan t to everyon e wh o u ses or m an ages p erson al com p u ter system s. Th ere are two typ es of p reven tive m ain ten an ce p roced u res: active an d p assive. An active p reven tive m ain ten an ce p rogram in clu d es p roced u res th at p rom ote a lon ger, trou ble-free life for you r PC. Th is typ e of p reven tive m ain ten an ce p rim arily in volves th e p eriod ic clean in g of th e system an d its com p on en ts. Th e followin g section s d escribe several active p reven tive m ain ten an ce p roced u res, in clu d in g clean in g an d lu bricatin g all m ajor com p on en ts, reseatin g ch ip s an d con n ectors, an d reform attin g h ard d isks. Passive p reven tive m ain ten an ce in clu d es step s you can take to p rotect a system from th e en viron m en t, su ch as u sin g p ower-p rotection d evices; en su rin g a clean , tem p eratu recon trolled en viron m en t; an d p reven tin g excessive vibration . In oth er word s, p assive p reven tive m ain ten an ce m ean s treatin g you r system well.

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Act ive Prevent ive M aint enance Procedures How often you sh ou ld p erform active p reven tive m ain ten an ce p roced u res d ep en d s on th e system ’s en viron m en t an d th e q u ality of th e system ’s com p on en ts. If you r system is in a d irty en viron m en t, su ch as a m ach in e sh op floor or a gas station service area, you m igh t n eed to clean you r system every th ree m on th s or less. For n orm al office en viron m en ts, clean in g a system every on e to two years is u su ally fin e. However, if you op en you r system after on e year an d fin d d u st bu n n ies in sid e, you sh ou ld p robably sh orten th e clean in g in terval. Oth er h ard d isk p reven tive m ain ten an ce p roced u res in clu d e m akin g p eriod ic backu p s of you r d ata an d critical areas su ch as boot sectors, file allocation tables (FATs), an d d irectory stru ctu res on th e d isk. Also, h ard d isk d efragm en tation s sh ou ld be p erform ed p eriod ically, to m ain tain d isk efficien cy an d sp eed . Syst em Backups. On e of th e m ost im p ortan t p reven tive m ain ten an ce p roced u res is th e p erform an ce of regu lar system backu p s. A sad reality in th e com p u ter rep air an d servicin g world is th at h ard ware can always be rep aired or rep laced , bu t d ata can n ot. Man y h ard d isk trou blesh ootin g an d service p roced u res, for exam p le, req u ire th at you rep artition or reform at th e d isk, wh ich overwrites all existin g d ata. Th e h ard d isk d rive cap acity in a typ ical PC h as grown far beyon d th e p oin t at wh ich flop p y d isks are a viable backu p solu tion . Backu p solu tion s th at em p loy flop p y d isk d rives, su ch as th e DOS backu p software, are in su fficien t an d too costly for h ard d isk backu p s in tod ay’s system s. It wou ld take 2,867 1.44M flop p y d isks, for exam p le, to back u p th e 4G h ard d isk in m y p ortable system ! Th at wou ld cost m ore th an $1,000 in d isks, n ot to m en tion th e tim e in volved . Th e trad ition al altern ative to flop p ies is m agn etic tap e. A DAT (Digital Au d io Tap e) or Travan tap e system can store 4G to 8G or m ore on a sin gle tap e costin g less th an $30. Th e in creasin g p op u larity of rem ovable cartrid ge (su ch as Iom ega Zip an d Jaz d rives) an d writable CD-ROM d rives p resen ts even m ore altern atives. Alth ou gh a tap e d rive m ay cost u p to $500 or m ore, th e m ed ia costs are really far m ore sign ifican t th an th e cost of th e d rive. If you are d oin g resp on sible backu p s, you sh ou ld h ave at least th ree sets of m ed ia for each system you are backin g u p . You sh ou ld u se each m ed ia set on a rotatin g basis, an d store on e of th em offsite at all tim es, in case of fire or th eft. You sh ou ld also in trod u ce n ew m ed ia to th e rotation after ap p roxim ately a year to p reven t excessive wear. If you are backin g u p m u ltip le system s, th ese m ed ia costs can ad d u p q u ickly. You sh ou ld also factor in th e cost of you r tim e. If a backu p req u ires m an u al in terven tion to ch an ge th e m ed ia d u rin g th e job, th en I d on ’t recom m en d it. A backu p system sh ou ld be able to fit a com p lete backu p on a sin gle tap e so you can sch ed u le th e job to ru n u n atten d ed . If som eon e h as to h an g arou n d to switch tap es every so often , backu p s becom e a real ch ore an d are m ore likely to be overlooked . Also, every tim e a m ed ia ch an ge occu rs, th ere is a su bstan tial in crease in th e likelih ood of errors an d p roblem s th at you m ay n ot see u n til you attem p t to p erform a restore op eration . Backu p s are far m ore im p ortan t

Preventive M aintenance

th an m ost p eop le realize, an d sp en d in g a little m ore on a q u ality p iece of h ard ware su ch as a Travan or DAT d rive will p ay off in th e lon g ru n with greater reliability, lower m ed ia costs, h igh er p erform an ce, an d u n atten d ed backu p s th at con tain th e en tire system file stru ctu re. W ith th e in creasin g p op u larity of rem ovable bu lk storage m ed ia like cartrid ge d rives, su ch as Iom ega’s Zip an d Jaz d rives, an d rewritable CD-ROMs (CD-RW s), m an y p eop le are u sin g th ese d evices to p erform system backu p s. In m ost cases, h owever, alth ou gh th ese d rives are excellen t for storin g backu p cop ies of selected d ata, th ey are im p ractical solu tion s for regu lar system backu p s. Th is can be d u e both to th e cap acity of th e m ed ia in relation to tod ay’s h ard d isk d rives, an d to th e cost of th e m ed ia. Alth ou gh th e m ed ia for a CD-RW d rive are q u ite in exp en sive, it wou ld take several d iscs to back u p a m u lti-gigabyte h ard d rive, ad d in g a m easu re of in con ven ien ce to th e backu p p rocess th at m akes it far less likely to be p erform ed on a regu lar basis. Even th e Iom ega Jaz d rive th at can store u p to 2G on a sin gle cartrid ge, can req u ire several m ed ia ch an ges to com p lete a sin gle system backu p . Ad d th is to th e fact th at th e Jaz cartrid ges can cost $150 or m ore each , an d you h ave a backu p solu tion th at is both in con ven ien t an d exp en sive.

Tip No matter what backup solution you use, the entire exercise is pointless if you cannot restore your data from the storage medium. You should test your backup system by performing random file restores at regular intervals, to ensure the viability of your data.

Cleaning a Syst em . On e of th e m ost im p ortan t op eration s in a good p reven tive m ain ten an ce p rogram is regu lar an d th orou gh clean in g of th e system . Du st bu ild u p on th e in tern al com p on en ts can lead to several p roblem s. On e is th at th e d u st acts as a th erm al in su lator, wh ich p reven ts p rop er system coolin g. Excessive h eat sh orten s th e life of system com p on en ts an d ad d s to th e th erm al stress p roblem cau sed by greater tem p eratu re ch an ges between th e system ’s p ower-on an d p ower-off states. Ad d ition ally, th e d u st m ay con tain con d u ctive elem en ts th at can cau se p artial sh ort circu its in a system . Oth er elem en ts in d u st an d d irt can accelerate corrosion of electrical con tacts, resu ltin g in im p rop er con n ection s. In all, th e regu lar rem oval of an y layer of d u st an d d ebris from with in a com p u ter system ben efits th at system in th e lon g ru n . Most n on -ATX an d som e ATX PCs u se a forced -air coolin g system th at p rovid es even coolin g in sid e th e case. A fan is m ou n ted in , on , or n ear th e p ower su p p ly an d p u sh es air ou tsid e. Th is d ep ressu rizes th e in terior of th e system relative to th e ou tsid e en viron m en t. Th e lower p ressu re in sid e th e system cau ses ou tsid e air to be d rawn in th rou gh op en in gs in th e system ch assis an d cover. Th is d raw-th rou gh , or d ep ressu rization , is th e m ost efficien t coolin g system th at can be d esign ed with ou t an air filter. Air filters typ ically are n ot u sed with d ep ressu rization system s becau se th ere is n o easy way to lim it th e air in take to a sin gle p ort th at can be covered by a filter.

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Som e in d u strial com p u ters an d ATX (as well as NLX) system s u se a forced -air system th at u ses th e fan to p ressu rize, rath er th an to d ep ressu rize, th e case. Th is system forces air to exh au st from an y h oles in th e ch assis an d case or cover. Th e key to th e p ressu rization system is th at all air in take for th e system is at a sin gle location —th e fan . You can th erefore filter th e air flowin g in to th e system by in tegratin g a filter assem bly in to th e fan h ou sin g. Th e filter m u st be clean ed or ch an ged p eriod ically, h owever, to p reven t it from becom in g clogged with d u st. Becau se th e in terior of th e case is p ressu rized relative to th e ou tsid e air, airborn e con tam in an ts are n ot d rawn in to th e system even th ou gh it m ay n ot be com p letely sealed . An y air en terin g th e system m u st p ass th rou gh th e fan an d filter h ou sin g, wh ich rem oves th e con tam in an ts. Pressu rization coolin g system s were origin ally d esign ed for u se in in d u strial com p u ter m od els in ten d ed for extrem ely h arsh en viron m en ts. However, with th e growin g p op u larity of th e ATX an d NLX arch itectu res, p ressu rization system s are m ore com m on . A recen t tren d in ATX case an d p ower su p p ly d esign , h owever, h as reverted to th e n egative-p ressu rization d esign . It is claim ed th at u sin g th e fan in th e p ower su p p ly to cool th e CPU d irectly is n ot effective sin ce th e air is p reh eated by th e p ower su p p ly, esp ecially if it is h eavily load ed . An oth er im p ortan t reason is th at th e sin gle biggest ad van tage of th e p ositive-p ressu re system , th e cap ability to filter th e in com in g air, is eith er n ot in clu d ed in th e system d esign or n ot m ain tain ed p rop erly. Most of th e PCs n ow in u se are d ep ressu rization system s. Mou n tin g an y sort of air filter on th ese typ es of system s is im p ossible becau se air en ters th e system from too m an y sou rces. W ith an y coolin g system in wh ich in com in g air is n ot filtered , d u st an d oth er ch em ical m atter in th e en viron m en t is d rawn in an d bu ild s u p in sid e th e com p u ter. Th is bu ild u p can cau se severe p roblem s if left u n ch ecked .

Tip Cigarette smoke contains chemicals that can conduct electricity and cause corrosion of computer parts. The smoke residue can infiltrate the entire system, causing corrosion and contamination of electrical contacts and sensitive components such as floppy drive read/ write heads and optical drive lens assemblies. You should avoid smoking near computer equipment and encourage your company to develop and enforce a similar policy.

Flop p y d isk d rives are p articu larly vu ln erable to th e effects of d irt an d d u st. A flop p y d rive is essen tially a large “h ole” in th e system case th rou gh wh ich air con tin u ou sly flows. Th erefore, th ey accu m u late a large am ou n t of d u st an d ch em ical bu ild u p with in a sh ort tim e. Hard d isk d rives d o n ot p resen t q u ite th e sam e p roblem . Becau se th e h ead d isk assem bly (HDA) in a h ard d isk is a sealed u n it with a sin gle barom etric ven t, n o d u st or d irt can en ter with ou t p assin g th rou gh th e barom etric ven t filter. Th is filter en su res th at con tam in atin g d u st or p articles can n ot en ter th e in terior of th e HDA. Th u s, clean in g a h ard d isk req u ires sim p ly blowin g th e d u st an d d irt off from ou tsid e th e d rive. No in tern al clean in g is req u ired .

Preventive M aintenance

Disassem bly and Cleaning Tools. To p rop erly clean th e system an d all th e board s in sid e req u ires certain su p p lies an d tools. In ad d ition to th e tools req u ired to d isassem ble th e u n it, you sh ou ld h ave th ese item s: ■ Con tact clean in g solu tion ■ Can n ed air ■ A sm all bru sh ■ Lin t-free foam clean in g swabs ■ An ti-static wrist-grou n d in g strap You also m igh t wan t to acq u ire th ese op tion al item s: ■ Foam tap e ■ Low-volatile room -tem p eratu re vu lcan izin g (RTV) sealer ■ Silicon e typ e lu brican t ■ Com p u ter vacu u m clean er Th ese sim p le clean in g tools an d ch em ical solu tion s will allow you to p erform m ost com m on p reven tive m ain ten an ce tasks. Chem icals. Ch em icals can be u sed to h elp clean , trou blesh oot, an d even rep air a system . You can u se several d ifferen t typ es of clean in g solu tion s with com p u ters an d electron ic assem blies. Most fall in to th e followin g categories: ■ Stan d ard clean ers ■ Con tact clean er/ lu brican ts ■ Du sters

Tip The makeup of many of the chemicals used for cleaning electronic components has been changing because many of the chemicals originally used are now considered environmentally unsafe. They have been attributed to damaging the earth’s ozone layer. Chlorine atoms from chlorofluorocarbons (CFCs) and chlorinated solvents attach themselves to ozone molecules and destroy them. M any of these chemicals are now strictly regulated by federal and international agencies in an effort to preserve the ozone layer. M ost of the companies that produce chemicals used for system cleaning and maintenance have had to introduce environmentally safe replacements. The only drawback is that many of these safer chemicals cost more and usually do not work as well as those they replace.

St a n d a rd Cl e a n e rs. For th e m ost basic fu n ction —clean in g com p on en ts, electrical con n ectors, an d con tacts—on e of th e m ost u sefu l ch em icals is 1,1,1 trich loroeth an e. Th is su bstan ce is a very effective clean er th at was at on e tim e u sed to clean electrical con tacts an d com p on en ts, becau se it d oes n ot d am age m ost p lastics an d board m aterials.

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In fact, trich loroeth an e cou ld be very u sefu l for clean in g stain s on th e system case an d keyboard as well. Un fortu n ately, trich loroeth an e is n ow bein g regu lated as a ch lorin ated solven t, alon g with CFCs (ch loroflu orocarbon s) su ch as freon , bu t electron ic ch em icalsu p p ly com p an ies are offerin g several rep lacem en ts. Altern ative clean in g solu tion s are available in a variety of typ es an d con figu ration s. You can u se p u re isop rop yl alcoh ol, aceton e, freon , trich loroeth an e, or a variety of oth er ch em icals. Most board m an u factu rers an d service sh op s are n ow lean in g toward th e alcoh ol, aceton e, or oth er ch em icals th at d o n ot cau se ozon e d ep letion an d com p ly with govern m en t regu lation s an d en viron m en tal safety. Recen tly, n ew biod egrad able clean ers d escribed as “citru s-based clean ers” h ave becom e p op u lar in th e in d u stry, an d in m an y cases are m ore effective an d m ore econ om ical for circu it board an d con tact clean in g. Th ese clean ers are com m on ly kn own as d-lim onene or citrus terpenes an d are d erived from oran ge p eels, wh ich gives it a stron g (bu t p leasan t) citric od or. An oth er typ e of terp en e is called a-pinene, an d is d erived from p in e trees. You m u st exercise care wh en u sin g th ese clean ers, h owever, as th ey can cau se swellin g of som e p lastics, esp ecially silicon e ru bber an d PVC. You sh ou ld be su re th at you r clean in g solu tion is d esign ed to clean com p u ters or electron ic assem blies. In m ost cases, th is m ean s th at th e solu tion sh ou ld be ch em ically p u re an d free from con tam in an ts or oth er u n wan ted su bstan ces. You sh ou ld n ot, for exam p le, u se d ru gstore ru bbin g alcoh ol for clean in g electron ic p arts or con tacts becau se it is n ot p u re an d cou ld con tain water or p erfu m es. Th e m aterial m u st be m oistu re-free an d resid u e-free. Th e solu tion s sh ou ld be in liq u id form , n ot a sp ray. Sp rays can be wastefu l, an d you alm ost n ever sp ray th e solu tion d irectly on com p on en ts. In stead , wet a foam or ch am ois swab u sed for wip in g th e com p on en t. Th ese electron ic-com p on en t clean in g solu tion s are available at an y good electron ics p arts store. Co n t a c t Cl e a n e r/ Lu b ri c a n t s. Th ese ch em icals are sim ilar to th e stan d ard clean ers bu t in clu d e a lu bricatin g com p on en t. Th e lu brican t eases th e force req u ired wh en p lu ggin g an d u n p lu ggin g cables an d con n ectors, red u cin g strain on th e d evices. Th e lu brican t coatin g also acts as a con d u ctive p rotectan t th at in su lates th e con tacts from corrosion . Th ese ch em icals can greatly p rolon g th e life of a system by p reven tin g in term itten t con tacts in th e fu tu re. A u n iq u e typ e of con tact en h an cer an d lu brican t called Stabilant 22 is cu rren tly on th e m arket. Th is ch em ical, wh ich you ap p ly to electrical con tacts, greatly en h an ces th e con n ection an d lu bricates th e con tact p oin t; it is m u ch m ore effective th an con ven tion al con tact clean ers or lu brican ts. Stabilan t 22 is a liq u id -p olym er sem icon d u ctor; it beh aves like liq u id m etal an d con d u cts electricity in th e p resen ce of an electric cu rren t. Th e su bstan ce also fills th e air gap s between th e m atin g su rfaces of two item s th at are in con tact, m akin g th e su rface area of th e con tact larger an d also keep in g ou t oxygen an d oth er con tam in an ts th at can corrod e th e con tact p oin t.

Preventive M aintenance

Th is ch em ical is available in several form s. Stabilan t 22 is th e con cen trated version , wh ereas Stabilan t 22a is a version d ilu ted with isop rop an ol in a 4:1 ratio. An even m ore d ilu ted 8:1-ratio version is sold in m an y h igh -en d stereo an d au d io sh op s u n d er th e n am e Tweek. Ju st 15m l of Stabilan t 22a sells for abou t $40; a liter of th e con cen trate costs abou t $4,000! As you can p lain ly see, Stabilan t 22 is fairly exp en sive, bu t very little is req u ired in an ap p lication , an d n oth in g else h as been fou n d to be as effective in p reservin g electrical con tacts. (NASA u ses th e ch em ical on sp acecraft electron ics.) An ap p lication of Stabilan t can p rovid e p rotection for u p to 16 years, accord in g to its m an u factu rer, D.W . Electroch em icals. You will fin d th e com p an y’s ad d ress an d p h on e n u m ber in th e ven d or list in Ap p en d ix A. Stabilan t is esp ecially effective on I/ O slot con n ectors, ad ap ter-card ed ge an d p in con n ectors, d isk d rive con n ectors, p ower-su p p ly con n ectors, an d virtu ally an y con n ector in th e PC. In ad d ition to en h an cin g th e con tact an d p reven tin g corrosion , an ap p lication of Stabilan t lu bricates th e con tacts, m akin g in sertion an d rem oval of th e con n ector easier. D u st e rs. Com p ressed gas often is u sed as an aid in system clean in g. You u se th e com p ressed gas as a blower to rem ove d u st an d d ebris from a system or com p on en t. Origin ally, th ese d u sters u sed CFCs su ch as freon , wh ereas m od ern d u sters n ow u se HFCs (su ch as d iflu oroeth an e) or carbon d ioxid e, n eith er of wh ich is d am agin g to th e ozon e layer. Be carefu l wh en you u se th ese d evices becau se som e of th em can gen erate a static ch arge wh en th e com p ressed gas leaves th e n ozzle of th e can . Be su re th at you are u sin g th e kin d ap p roved for clean in g or d u stin g off com p u ter eq u ip m en t, an d con sid er wearin g a static grou n d in g strap as a p recau tion . Th e typ e of com p ressed -air can s u sed for clean in g cam era eq u ip m en t can som etim es d iffer from th e typ e u sed for clean in g staticsen sitive com p u ter com p on en ts. W h en u sin g th ese com p ressed air p rod u cts, m ake su re you h old th e can u p righ t so th at on ly gas is ejected from th e n ozzle. If you tip th e can , th e raw p rop ellan t will com e ou t as a cold liq u id , wh ich is n ot on ly wastefu l, bu t can d am age or d iscolor p lastics. You sh ou ld on ly u se com p ressed gas on eq u ip m en t th at is p owered off, to m in im ize an y ch an ce of d am age th rou gh sh ort circu its. Closely related to com p ressed -air p rod u cts are chem ical-freeze sprays. Th ese sp rays are u sed to q u ickly cool d own a su sp ected failin g com p on en t, wh ich often tem p orarily restores it to n orm al op eration . Th ese su bstan ces are n ot u sed to rep air a d evice, bu t to con firm th at you h ave fou n d a failed d evice. Often , a com p on en t’s failu re is h eat-related an d coolin g it tem p orarily restores it to n orm al op eration . If th e circu it begin s op eratin g n orm ally, th e d evice you are coolin g is th e su sp ect d evice. Va c u u m Cl e a n e rs. Som e p eop le p refer to u se a vacu u m clean er in stead of can n ed gas d u sters for clean in g a system . Can n ed gas is u su ally better for clean in g in sm all areas. A vacu u m clean er is m ore u sefu l wh en you are clean in g a system load ed with d u st an d d irt. You can u se th e vacu u m clean er to su ck ou t th e d u st an d d ebris in stead of ju st blowin g it

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arou n d on th e oth er com p on en ts, wh ich som etim es h ap p en s with can n ed air. For on site servicin g (wh en you are goin g to th e location of th e eq u ip m en t in stead of th e eq u ip m en t com in g to you ), can n ed air is easier to carry in a tool kit th an a sm all vacu u m clean er. Th ere are also tin y vacu u m clean ers available for system clean in g. Th ese sm all u n its are easy to carry an d m ay serve as an altern ative to com p ressed air can s. Th ere are sp ecial vacu u m clean ers sp ecifically d esign ed for u se on an d arou n d electron ic com p on en ts. Th ey are d esign ed to m in im ize ESD wh ile in u se. If you are u sin g a regu lar vacu u m clean er an d n ot on e sp ecifically d esign ed with ESD p rotection , th en you sh ou ld take p recau tion s su ch as wearin g a grou n d in g wrist strap . Also, if th e clean er h as a m etal n ozzle, be carefu l n ot to tou ch it to th e circu it board s or com p on en ts you are clean in g. Bru sh e s a n d Sw a b s. You can u se a sm all m akeu p , p h otograp h ic, or p ain t bru sh to carefu lly loosen th e accu m u lated d irt an d d u st in sid e a PC before sp rayin g it with can n ed air or u sin g th e vacu u m clean er. Be carefu l abou t gen eratin g static electricity, h owever. In m ost cases, you sh ou ld n ot u se a bru sh d irectly on circu it board s, bu t on ly on th e case in terior an d oth er p arts su ch as fan blad es, air ven ts, an d keyboard s. W ear a grou n d ed wrist strap if you are bru sh in g on or n ear an y circu it board s, an d bru sh slowly an d ligh tly to p reven t static d isch arges from occu rrin g. Use clean in g swabs to wip e off electrical con tacts an d con n ectors, d isk d rive h ead s, an d oth er sen sitive areas. Th e swabs sh ou ld be m ad e of foam or syn th etic ch am ois m aterial th at d oes n ot leave lin t or d u st resid u e. Un fortu n ately, p rop er foam or ch am ois clean in g swabs are m ore exp en sive th an th e typ ical cotton swabs. Do n ot u se cotton swabs becau se th ey leave cotton fibers on everyth in g th ey tou ch . Cotton fibers are con d u ctive in som e situ ation s an d can rem ain on d rive h ead s, wh ich can scratch d isks. Foam or ch am ois swabs can be p u rch ased at m ost electron ics su p p ly stores. On e item to avoid is an eraser for clean in g con tacts. Man y p eop le (in clu d in g m yself) h ave recom m en d ed u sin g a soft p en cil-typ e eraser for clean in g circu it-board con tacts. Testin g h as p roven th is to be bad ad vice for several reason s. On e reason is th at an y su ch abrasive wip in g on electrical con tacts gen erates friction an d an ESD. Th is ESD can be d am agin g to board s an d com p on en ts, esp ecially th e n ewer low-voltage d evices. Th ese d evices are esp ecially static-sen sitive, an d clean in g th e con tacts with ou t a p rop er liq u id solu tion is n ot recom m en d ed . Also, th e eraser will wear off th e gold coatin g on m an y con tacts, exp osin g th e tin con tact u n d ern eath , wh ich will rap id ly corrod e wh en exp osed to air. Som e com p an ies sell p rem oisten ed con tact clean in g p ad s th at are soaked in a p rop er con tact clean er an d lu brican t. Th ese p ad s are safe to wip e on con d u ctor an d con tacts with n o likelih ood of ESD d am age or abrasion of th e gold p latin g. Si l i c o n e Lu b ri c a n t s. You can u se a silicon e lu brican t su ch as W D40 to lu bricate th e d oor m ech an ism s on flop p y d isk d rives an d an y oth er p art of th e system th at m ay req u ire clean , n on -oily lu brication . Oth er item s th at you can lu bricate are th e d isk d rive h ead slid er rails an d even p rin ter-h ead slid er rails, to p rovid e sm ooth er op eration . Usin g silicon e in stead of con ven tion al oils is im p ortan t becau se silicon e d oes n ot gu m u p an d collect d u st an d oth er d ebris. Always u se th e silicon e sp arin gly. Do n ot sp ray it

Preventive M aintenance

an ywh ere n ear th e eq u ip m en t as it ten d s to m igrate an d will en d u p wh ere it d oesn ’t belon g (su ch as on d rive h ead s). In stead , ap p ly a sm all am ou n t to a tooth p ick or foam swab an d d ab th e silicon e lu brican t on th e com p on en ts wh ere n eed ed . You can u se a lin t-free clean in g stick soaked in silicon e to lu bricate th e m etal p rin t-h ead rails in a p rin ter. Obt aining Required Tools and Accessories. You can obtain m ost of th e clean in g ch em icals an d tools d iscu ssed in th is ch ap ter from an electron ics su p p ly h ou se, or even you r local Rad io Sh ack. A com p an y called Ch em tron ics sp ecializes in ch em icals for th e com p u ter an d electron ics in d u stry. Th ese an d oth er com p an ies th at su p p ly tools, ch em icals, an d oth er com p u ter an d electron ic clean in g su p p lies are listed in th e ven d or list in Ap p en d ix A. W ith all th ese item s on h an d , you sh ou ld be eq u ip p ed for m ost p reven tive m ain ten an ce op eration s. Disassem bling and Cleaning Procedures. To p rop erly clean you r system , you m u st at least p artially d isassem ble it. Som e p eop le go as far as to rem ove th e m oth erboard . Rem ovin g th e m oth erboard resu lts in th e best p ossible access to oth er areas of th e system ; bu t in th e in terest of savin g tim e, you p robably n eed to d isassem ble th e system on ly to th e p oin t at wh ich th e m oth erboard is com p letely visible. To d o th is, rem ove all th e system ’s p lu g-in ad ap ter card s an d th e d isk d rives. Alth ou gh you can clean th e h ead s of a flop p y d rive with a clean in g d isk with ou t op en in g th e system u n it’s cover, you p robably will wan t to d o m ore th orou gh clean in g. In ad d ition to th e d rive h ead s, you also sh ou ld clean an d lu bricate th e d oor m ech an ism an d clean an y logic board s an d con n ectors on th e d rive. Th is p roced u re u su ally req u ires rem ovin g th e d rive. Next, d o th e sam e th in g with th e h ard d isk d rives: Clean th e logic board s an d con n ectors, an d lu bricate th e grou n d in g strap . To d o th is, you m u st rem ove th e h ard d isk assem bly. As a p recau tion , be su re you r d ata is backed u p first. Reseat ing Socket ed Chips. An oth er p rim ary p reven tive m ain ten an ce fu n ction is to u n d o th e effects of ch ip creep . As you r system h eats an d cools, it exp an d s an d con tracts, an d th e p h ysical exp an sion an d con traction can cau se com p on en ts th at are p lu gged in to sockets to grad u ally work th eir way ou t of th ose sockets. Th is p rocess is called chip creep. To correct its effects, you m u st fin d all socketed com p on en ts in th e system an d m ake su re th at th ey are p rop erly reseated . In m ost of tod ay’s system s, th e m em ory ch ip s are in stalled in socketed SIMMs or DIMMs. SIMM/ DIMM d evices are retain ed secu rely in th eir sockets by a p ositive latch in g m ech an ism an d can n ot creep ou t. Th e Mem ory SIPP (Single Inline Pin Package) devices (SIMMs with p in s rath er th an con tacts) u sed in old er system s are n ot retain ed by a latch in g m ech an ism , h owever, an d th erefore can creep ou t of th eir sockets. Stan d ard socketed m em ory ch ip s are p rim e can d id ates for ch ip creep . Most oth er logic com p on en ts are sold ered in . On an old er system , you m ay also fin d th e ROM ch ip s, a m ath cop rocessor, an d even th e m ain system p rocessor in sockets. Newer system s p lace th e CPU in a ZIF

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socket, wh ich h as a lever th at releases th e grip of th e socket on th e ch ip . In m ost cases, th ere is very little creep with a ZIF socket. In m ost cu rren t system s, th e m em ory (in SIMMs or DIMMs) an d th e p rocessor are th e on ly com p on en ts th at you will fin d in sockets; all oth ers are sold ered in . Excep tion s, h owever, m igh t exist. A socketed com p on en t in on e system m igh t n ot be socketed in an oth er—even if both are from th e sam e m an u factu rer. Som etim es th is d ifferen ce resu lts from a p arts-availability p roblem wh en th e board s are m an u factu red . Rath er th an h alt th e assem bly lin e wh en a p art is n ot available, th e m an u factu rer ad d s a socket in stead of th e com p on en t. W h en th e com p on en t becom es available, it is p lu gged in an d th e board is fin ish ed . To m ake su re th at all com p on en ts are fu lly seated in th eir sockets, p lace you r h an d on th e u n d ersid e of th e board an d th en ap p ly d own ward p ressu re with th e th u m b of you r oth er h an d (from th e top ) on th e ch ip to be seated . For larger ch ip s, seat th e ch ip carefu lly in th e socket, an d p ress sep arately on each en d of th e ch ip with you r th u m b to be su re th at th e ch ip is fu lly seated . (Th e p rocessor an d m ath cop rocessor ch ip s can u su ally be seated in th is m an n er.) In m ost cases, you sh ou ld h ear a cru n ch in g sou n d as th e ch ip m akes its way back in to th e socket. Becau se of th e great force th at is som etim es req u ired to reseat th e ch ip s, th is op eration is d ifficu lt if you d o n ot rem ove th e board . For m oth erboard s, forcibly seatin g ch ip s can be d an gerou s if you d o n ot d irectly su p p ort th e board from th e u n d ersid e with you r h an d . Too m u ch p ressu re on th e board can cau se it to bow or ben d in th e ch assis, an d th e p ressu re can crack it before th e ch ip is fu lly seated . Th e p lastic stan d offs th at h old th e board u p off th e m etal ch assis are sp aced too far ap art to p rop erly su p p ort th e board u n d er th is kin d of stress. Try th is op eration on ly if you can rem ove an d su p p ort th e board ad eq u ately from u n d ern eath . You m ay be su rp rised to kn ow th at, even if you fu lly seat each ch ip , th ey m igh t n eed reseatin g again with in a year. Th e creep u su ally is n oticeable with in a year or less. Cleaning Boards. After reseatin g an y socketed d evices th at m ay h ave crep t ou t of th eir sockets, th e n ext step is to clean th e board s an d all con n ectors in th e system . For th is step , u se th e clean in g solu tion s an d th e lin t-free swabs m en tion ed earlier. First, clean th e d u st an d d ebris off th e board an d th en clean an y con n ectors on th e board . To clean th e board s, it is u su ally best to u se a vacu u m clean er d esign ed for electron ic assem blies an d circu it board s or a d u ster can of com p ressed gas. Th e d u sters are esp ecially effective at blastin g an y d u st an d d irt off th e board s. Also, blow an y d u st ou t of th e p ower su p p ly, esp ecially arou n d th e fan in take an d exh au st areas. You d o n ot n eed to d isassem ble th e p ower su p p ly to d o th is; ju st u se a d u ster can an d blast th e com p ressed air in to th e su p p ly th rou gh th e fan exh au st p ort. Th is will blow th e d u st ou t of th e su p p ly an d clean off th e fan blad es an d grill, wh ich will h elp with system airflow.

Preventive M aintenance

Caut ion Be careful with ESD, which can cause damage when you are cleaning electronic components. Take extra precautions in the dead of winter or in extremely dry, high-static environments. You can apply anti-static sprays and treatments to the work area to reduce the likelihood of ESD damage. An anti-static wrist-grounding strap is recommended. This should be connected to a ground on the card or board you are wiping. This strap ensures that no electrical discharge occurs between you and the board. An alternative method is to keep a finger or thumb on the ground of the motherboard or card as you wipe it off.

Cl e a n i n g Co n n e c t o rs a n d Co n t a c t s. Clean in g th e con n ectors an d con tacts in a system p rom otes reliable con n ection s between d evices. On a m oth erboard , you will wan t to clean th e slot con n ectors, p ower su p p ly con n ectors, keyboard an d m ou se con n ectors, an d th e sp eaker con n ector. For m ost p lu g-in card s, you will wan t to clean th e ed ge con n ectors th at p lu g in to slots on th e m oth erboard an d an y oth er con n ectors, su ch as extern al on es m ou n ted on th e card bracket. Su bm erge th e lin t-free swabs in th e liq u id clean in g solu tion . If you are u sin g th e sp ray, h old th e swab away from th e system an d sp ray a sm all am ou n t on th e foam en d u n til th e solu tion starts to d rip . Th en , u se th e soaked foam swab to wip e th e con n ectors on th e board s. Pre-soaked wip es are th e easiest to u se. Sim p ly wip e th em alon g th e con tacts to rem ove an y accu m u lated d irt an d leave a p rotective coatin g beh in d . On th e m oth erboard , p ay sp ecial atten tion to th e slot con n ectors. Be liberal with th e liq u id ; resoak th e foam swab rep eated ly, an d vigorou sly clean th e con n ectors. Don ’t worry if som e of th e liq u id d rip s on th e su rface of th e m oth erboard . Th ese solu tion s are en tirely safe for th e wh ole board an d will n ot d am age th e com p on en ts. Use th e solu tion to wash th e d irt off th e gold con tacts in th e slot con n ectors, an d th en clean an y oth er con n ectors on th e board . Clean th e keyboard an d m ou se con n ectors, th e grou n d in g p osition s wh ere screws grou n d th e board to th e system ch assis, p ower-su p p ly con n ectors, sp eaker con n ectors, an d th e battery con n ectors. If you are clean in g a p lu g-in board , p ay sp ecial atten tion to th e ed ge con n ector th at m ates with th e slot con n ector on th e m oth erboard . W h en p eop le h an d le p lu g-in card s, th ey often tou ch th e gold con tacts on th ese con n ectors. Tou ch in g th e gold con tacts coats th em with oils an d d ebris, wh ich p reven ts p rop er con tact with th e slot con n ector wh en th e board is in stalled . Make su re th ese gold con tacts are free of all fin ger oils an d resid u e. It is a good id ea to u se on e of th e con tact clean ers th at h as a con d u ctive lu brican t, wh ich m akes it easier to p u sh th e ad ap ter in to th e slot an d also p rotects th e con tacts from corrosion . You will also wan t to u se th e swab an d solu tion to clean th e en d s of ribbon cables or oth er typ es of cables or con n ectors in a system . Clean th e flop p y d rive cables an d con n ectors, th e h ard d isk cables an d con n ectors, an d an y oth ers you fin d . Don ’t forget to clean th e ed ge con n ectors th at are on th e d isk d rive logic board s, as well as th e p ower con n ectors to th e d rives.

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Cl e a n i n g t h e Ke y b o a rd a n d Mo u se . Keyboard s an d m ice are n otoriou s for p ickin g u p d irt an d garbage. If you h ave ever op en ed u p an old er keyboard , you often will be am azed at th e ju n k you will fin d in th ere. To p reven t p roblem s, it is a good id ea to p eriod ically clean th e keyboard with a vacu u m clean er. An altern ative m eth od is to tu rn th e keyboard u p sid e d own an d sh oot it with a can of com p ressed air. Th is will blow ou t th e d irt an d d ebris th at h as accu m u lated in sid e th e keyboard an d p ossibly p reven t fu tu re p roblem s with stickin g keys or d irty keyswitch es. If a p articu lar key is stu ck or m akin g in term itten t con tact, you can soak or sp ray th at switch with con tact clean er. Th e best way to d o th is is to first rem ove th e keycap an d th en sp ray th e clean er in to th e switch . Th is u su ally d oes n ot req u ire com p lete d isassem bly of th e keyboard . Period ic vacu u m in g or com p ressed gas clean in g will p reven t m ore seriou s p roblem s with stickin g keys an d keyswitch es. Most m ice are easy to clean . In m ost cases, th ere is a twist-off lockin g retain er th at keep s th e m ou se ball retain ed in th e bod y of th e m ou se. By rem ovin g th e retain er, th e ball will d rop ou t. After rem ovin g th e ball, you sh ou ld clean it with on e of th e electron ic clean ers. I wou ld recom m en d a p u re clean er in stead of a con tact clean er with lu brican t becau se you d o n ot wan t an y lu brican t on th e m ou se ball. Th en you sh ou ld wip e off th e rollers in th e bod y of th e m ou se with th e clean er an d som e swabs. Period ic clean in g of a m ou se in th is m an n er will elim in ate or p reven t skip p in g or erratic m ovem en t. I also recom m en d a m ou se p ad for m ost ball-typ e m ice becau se th e p ad will p reven t th e m ou se ball from p ickin g u p d ebris from you r d esk. Oth er p oin tin g d evices req u irin g little or n o m ain ten an ce are th e IBM-d esign ed Trackp oin t an d sim ilar system s in trod u ced by oth er m an u factu rers, su ch as th e Glid ep oin t by Alp s. Th ese d evices are totally sealed , an d u se p ressu re tran sd u cers to con trol p oin ter m ovem en t. Becau se th ey are sealed , clean in g n eed on ly be p erform ed extern ally, an d is as sim p le as wip in g th e d evice off with a m ild clean in g solu tion to rem ove oils an d oth er d ep osits th at h ave accu m u lated from h an d lin g th em . Hard Disk M aint enance. Certain p reven tive m ain ten an ce p roced u res p rotect you r d ata an d en su re th at you r h ard d isk works efficien tly. Som e of th ese p roced u res actu ally m in im ize wear an d tear on you r d rive, wh ich will p rolon g its life. Ad d ition ally, a h igh level of d ata p rotection can be im p lem en ted by p erform in g som e sim p le com m an d s p eriod ically. Th ese com m an d s p rovid e m eth od s for backin g u p (an d p ossibly later restorin g) critical areas of th e h ard d isk th at, if d am aged , wou ld d isable access to all you r files. D e f ra g m e n t i n g Fi l e s. Over tim e, as you d elete an d save files to a h ard d isk, th e files becom e fragm ented. Th is m ean s th at th ey are sp lit in to m an y n on con tigu ou s areas on th e d isk. On e of th e best ways to p rotect both you r h ard d isk an d th e d ata on it is to p eriod ically d efragm en t th e files on th e d isk. Th is serves two p u rp oses. On e is th at by en su rin g th at all th e files are stored in con tigu ou s sectors on th e d isk, h ead m ovem en t an d d rive wear an d tear will be m in im ized . Th is h as th e ad d ed ben efit of im p rovin g th e sp eed at wh ich th e d rive retrieves files by red u cin g th e h ead th rash in g th at occu rs every tim e it accesses a fragm en ted file.

Preventive M aintenance

Th e secon d m ajor ben efit, an d in m y estim ation th e m ore im p ortan t of th e two, is th at in th e case of a d isaster wh ere th e FATs an d root d irectory are severely d am aged , th e d ata on th e d rive can u su ally be recovered easily if th e files are con tigu ou s. On th e oth er h an d , if th e files are sp lit u p in m an y p ieces across th e d rive, it is virtu ally im p ossible to figu re ou t wh ich p ieces belon g to wh ich files with ou t an in tact FAT an d d irectory system . For th e p u rp oses of d ata in tegrity an d p rotection , I recom m en d d efragm en tin g you r h ard d isk d rives on a m on th ly basis. Th ere are th ree m ain fu n ction s in m ost d efragm en tation p rogram s: ■ File d efragm en tation ■ File p ackin g (Free Sp ace Con solid ation ) ■ File sortin g Defragm en tation is th e basic fu n ction , bu t m ost oth er p rogram s also ad d file p ackin g. Packin g th e files is op tion al on som e p rogram s becau se it u su ally takes ad d ition al tim e to p erform . Th is fu n ction p acks th e files at th e begin n in g of th e d isk so th at all free sp ace is con solid ated at th e en d of th e d isk. Th is featu re m in im izes fu tu re file fragm en tation by elim in atin g an y em p ty h oles on th e d isk. Becau se all free sp ace is con solid ated in to on e large area, an y n ew files written to th e d isk will be able to be written in a con tigu ou s m an n er with n o fragm en tation . Th e last fu n ction , file sortin g (som etim es called disk optim izing), is n ot u su ally n ecessary an d is p erform ed as an op tion by m an y d efragm en tin g p rogram s. Th is fu n ction ad d s a trem en d ou s am ou n t of tim e to th e op eration , an d h as little or n o effect on th e sp eed at wh ich in form ation is accessed . It can be som ewh at ben eficial for d isaster recovery p u rp oses becau se you will h ave an id ea of wh ich files cam e before or after oth er files if a d isaster occu rs. Not all d efragm en tin g p rogram s offer file sortin g, an d th e extra tim e it takes is p robably n ot worth an y ben efits you will receive. Oth er p rogram s can sort th e ord er th at files are listed in d irectories, wh ich is a q u ick an d easy op eration com p ared to sortin g th e file ord erin g th e d isk. W in d ows 9x in clu d es a d isk d efragm en tation p rogram with th e op eratin g system th at you can u se on both th e FAT16 an d FAT32 file system s th at th e OS su p p orts. For DOS an d W in d ows system s, you m u st p u rch ase a th ird -p arty d efragm en tation p rogram . Norton Utilities in clu d es a d isk d efragm en ter, as d o m an y oth er u tility p ackages. If you elect to u se a th ird -p arty p rod u ct on a W in d ows 9x system , be certain th at it su p p orts th e file system you u se on you r d rives. Ru n n in g a FAT16 d efragm en tation p rogram on a FAT32 d rive can cau se severe p roblem s. Before you d efragm en t you r d isks, it is a good id ea to ru n a d isk rep air p rogram su ch as W in d ows 9x’s Scan Disk or Norton Disk Doctor, even if you are n ot exp erien cin g an y p roblem s. Th is en su res th at you r d rives are in good workin g ord er before you begin th e d efragm en tation p rocess.

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W indow s 98 M aint enance W izard Windows 98 includes a Task Scheduler program that enables you to schedule programs for automatic execution at specified times. The Windows 98 M aintenance Wizard walks you through the steps of scheduling regular disk defragmentations, disk error scans, and deletions of unnecessary files. You can schedule these processes to execute during non-working hours, so regular system activities are not disturbed.

Vi ru s Ch e c k i n g . Viru ses are a d an ger to an y system , an d it’s a good id ea to m ake scan s with an an ti-viru s p rogram a regu lar p art of you r p reven tive m ain ten an ce p rogram . Alth ou gh both Microsoft an d IBM p rovid e an ti-viru s software in MS- an d PC-DOS, resp ectively, if you ru n W in d ows 9x or W in d ows NT, you m u st obtain a th ird -p arty p rogram to scan you r system . Th ere are m an y afterm arket u tility p ackages available th at will scan for an d rem ove viru ses. No m atter wh ich of th ese p rogram s you u se, you sh ou ld p erform a scan for viru s p rogram s p eriod ically, esp ecially before m akin g h ard d isk backu p s. Th is will h elp en su re th at you catch an y p oten tial viru s p roblem before it sp read s an d becom es a m ajor catastrop h e. In ad d ition , it is im p ortan t to select an an ti-viru s p rod u ct from a ven d or th at p rovid es regu lar u p d ates to th e p rogram ’s viru s sign atu res. Th e sign atu res d eterm in e wh ich viru ses th e software can d etect an d cu re, an d becau se th ere are n ew viru ses con stan tly bein g in trod u ced , th ese u p d ates are essen tial. Passive Prevent ive M aint enance Procedures Passive p reven tive m ain ten an ce in volves takin g care of th e system by p rovid in g th e best p ossible en viron m en t—both p h ysical an d electrical—for th e system . Ph ysical con cern s are con d ition s su ch as am bien t tem p eratu re, th erm al stress from p ower cyclin g, d u st an d sm oke con tam in ation , an d d istu rban ces su ch as sh ock an d vibration . Electrical con cern s are item s su ch as ESD, p ower-lin e n oise, an d rad io-freq u en cy in terferen ce. Each of th ese en viron m en tal con cern s is d iscu ssed in th e followin g section s. Exam ining t he Operat ing Environm ent . Od d ly en ou gh , on e of th e m ost overlooked asp ects of m icrocom p u ter p reven tive m ain ten an ce is p rotectin g th e h ard ware—an d th e sizable fin an cial in vestm en t it rep resen ts—from en viron m en tal abu se. Com p u ters are relatively forgivin g, an d th ey are gen erally safe in an en viron m en t th at is com fortable for p eop le. Com p u ters, h owever, are often treated with n o m ore resp ect th an d esktop calcu lators. Th e resu lt of th is typ e of abu se is m an y system failu res. Before you set u p a n ew PC, p rep are a p rop er location for it th at is free of airborn e con tam in an ts su ch as sm oke or oth er p ollu tion . Do n ot p lace you r system in fron t of a win d ow; th e com p u ter sh ou ld n ot be exp osed to d irect su n ligh t or tem p eratu re variation s. Th e en viron m en tal tem p eratu re sh ou ld be as con stan t as p ossible. Power sh ou ld be p rovid ed th rou gh p rop erly grou n d ed ou tlets an d sh ou ld be stable an d free from electrical n oise an d in terferen ce. Keep you r system away from rad io tran sm itters or oth er sou rces of rad io freq u en cy en ergy. Heat ing and Cooling. Th erm al exp an sion an d con traction from am bien t tem p eratu re ch an ges p laces stress on a com p u ter system . Th erefore, keep in g th e tem p eratu re in you r

Preventive M aintenance

office or room relatively con stan t is im p ortan t to th e su ccessfu l op eration of you r com p u ter system . Tem p eratu re variation s can lead to seriou s p roblem s. You m igh t en cou n ter excessive ch ip creep , for exam p le. If extrem e variation s occu r over a sh ort p eriod , sign al traces on circu it board s can crack an d sep arate, sold er join ts can break, an d con tacts in th e system can u n d ergo accelerated corrosion . Solid -state com p on en ts su ch as ch ip s can be d am aged also, an d a h ost of oth er p roblem s can d evelop . Tem p eratu re variation s can p lay h avoc with h ard d isk d rives. W ritin g to a d isk at d ifferen t am bien t tem p eratu res can , on som e d rives, cau se d ata to be written at d ifferen t location s relative to th e track cen ters. Th is can cau se read an d write p roblem s at a later tim e. To en su re th at you r system op erates in th e correct am bien t tem p eratu re, you m u st first d eterm in e you r system ’s sp ecified fu n ction al ran ge. Most m an u factu rers p rovid e d ata abou t th e correct op eratin g tem p eratu re ran ge for th eir system s. Two tem p eratu re sp ecification s m igh t be available, on e in d icatin g allowable tem p eratu res d u rin g op eration an d an oth er in d icatin g allowable tem p eratu res u n d er n on -op eratin g con d ition s. IBM, for exam p le, in d icates th e followin g tem p eratu re ran ges as accep table for m ost of its system s: System on : 60 to 90° Fah ren h eit System off: 50 to 110° Fah ren h eit For th e safety of th e d isk an d th e d ata it con tain s, avoid rap id ch an ges in am bien t tem p eratu res. If rap id tem p eratu re ch an ges occu r—for exam p le, wh en a n ew d rive is sh ip p ed to a location d u rin g th e win ter an d th en brou gh t in d oors—let th e d rive acclim ate to room tem p eratu re before tu rn in g it on . In extrem e cases, con d en sation can form on th e p latters in sid e th e d rive HDA—d isastrou s for th e d rive if you tu rn it on before th e con d en sation h as a ch an ce to evap orate. Most d rive m an u factu rers sp ecify a tim etable to u se as a gu id e in acclim atin g a d rive to room tem p eratu re before op eratin g it. You u su ally m u st wait several h ou rs to a d ay before a d rive is read y to u se after it h as been sh ip p ed or stored in a cold en viron m en t. Th ey n orm ally ad vise th at you leave th e d rive in its p ackin g u n til it is acclim ated . Rem ovin g th e d rive from a sh ip p in g carton wh en extrem ely cold will in crease th e likelih ood of con d en sation form in g as th e d rive warm s u p . Most office en viron m en ts p rovid e a stable tem p eratu re in wh ich to op erate a com p u ter system , bu t som e d o n ot. Be su re to give som e con sid eration to th e p lacem en t of you r eq u ip m en t. Pow er Cycling ( On/ Off) . As you h ave ju st learn ed , th e tem p eratu re variation s th at a system en cou n ters greatly stress th e system ’s p h ysical com p on en ts. Th e largest tem p eratu re variation s a system en cou n ters, h owever, are th ose th at occu r d u rin g th e warm u p p eriod righ t after you tu rn th e com p u ter on . Powerin g on a cold system su bjects it to th e greatest p ossible in tern al tem p eratu re variation s. If you wan t a system to h ave th e lon gest an d m ost trou ble-free life p ossible, you sh ou ld lim it th e tem p eratu re variation s in its en viron m en t. You can lim it th e extrem e tem p eratu re cyclin g in two sim p le ways d u rin g

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a cold startu p —leave th e system off all th e tim e or leave it on all th e tim e. Of th ese two p ossibilities, of cou rse, you will p robably wan t to ch oose th e latter op tion . Leavin g th e p ower on is th e best way I kn ow to p rom ote system reliability. If you r on ly con cern is system lon gevity, th e sim p le recom m en d ation wou ld be to keep th e system u n it p owered on (or off!) con tin u ou sly. In th e real world , h owever, th ere are m ore variables to con sid er, su ch as th e cost of electricity, th e p oten tial fire h azard of u n atten d ed ru n n in g eq u ip m en t, an d oth er con cern s, as well. If you th in k abou t th e way ligh t bu lbs typ ically fail, you can begin to u n d erstan d h ow th erm al cyclin g can be d an gerou s. Ligh t bu lbs bu rn ou t m ost often wh en you first tu rn th em on , becau se th e filam en t m u st en d u re in cred ible th erm al stress as it ch an ges tem p eratu re—in less th an on e secon d —from am bien t to several th ou san d s of d egrees. A bu lb th at rem ain s on con tin u ou sly lasts lon ger th an on e th at is tu rn ed on an d off rep eated ly. Th e p lace wh ere p roblem s are m ost likely to occu r im m ed iately at p ower-on is in th e p ower su p p ly. Th e start-u p cu rren t d raw for th e system d u rin g th e first few secon d s of op eration is very h igh com p ared to th e n orm al op eratin g-cu rren t d raw. Becau se th e cu rren t m u st com e from th e p ower su p p ly, th e su p p ly h as an extrem ely d em an d in g load to carry for th e first few secon d s of op eration , esp ecially if several d isk d rives m u st be started . Motors h ave an extrem ely h igh p ower-on cu rren t d raw. Th is d em an d often overload s a m argin al circu it or com p on en t in th e su p p ly an d cau ses it to bu rn or break with a “sn ap .” I h ave seen several p ower su p p lies d ie th e in stan t a system was p owered u p . To en able you r eq u ip m en t to h ave th e lon gest p ossible life, try to keep th e tem p eratu re of solid -state com p on en ts relatively con stan t, an d lim it th e n u m ber of startu p s on th e p ower su p p ly. Th e on ly way I kn ow to d o th is is to leave th e system on . Alth ou gh it sou n d s like I am tellin g you to leave all you r com p u ter eq u ip m en t on 24 h ou rs a d ay, seven d ays a week, I n o lon ger recom m en d th is typ e of op eration . A cou p le of con cern s h ave tem p ered m y u rge to leave everyth in g ru n n in g con tin u ou sly. On e is th at an u n atten d ed system th at is p owered on rep resen ts a fire h azard . I h ave seen m on itors catch fire after in tern ally sh ortin g, an d system s wh ose coolin g fan s h ave frozen , cau sin g th e p ower su p p ly an d th e en tire system to overh eat. I d o n ot leave an y system ru n n in g in an u n atten d ed bu ild in g. An oth er p roblem is wasted electrical p ower. Man y com p an ies h ave ad op ted au sterity p rogram s th at in volve tu rn in g ligh ts an d oth er item s off wh en n ot in u se. Th e p ower con su m p tion of som e of tod ay’s h igh -p owered system s an d accessories is n ot trivial. Also, an u n atten d ed op eratin g system is m ore of a secu rity risk th an on e th at is p owered off an d locked . Realities—su ch as th e fire h azard of u n atten d ed system s ru n n in g d u rin g n igh t or weeken d h ou rs, secu rity p roblem s, an d p ower-con su m p tion issu es—m igh t p reven t you from leavin g you r system on all th e tim e. Th erefore, you m u st com p rom ise. Power on th e system on ly on e tim e d aily. Don ’t p ower th e system on an d off several tim es every d ay. Th is good ad vice is often ign ored , esp ecially wh en several u sers sh are system s. Each u ser p owers on th e system to p erform work on th e PC an d th en p owers off th e system . Th ese system s ten d to h ave m an y m ore p roblem s with com p on en t failu res. If you are in a bu ild in g with a p rogram m able th erm ostat, you h ave an oth er reason to be con cern ed abou t tem p eratu res an d d isk d rives. Som e bu ild in gs h ave th erm ostats

Preventive M aintenance

p rogram m ed to tu rn off th e h eat overn igh t or over th e weeken d . Th ese th erm ostats are p rogram m ed also to q u ickly raise th e tem p eratu re ju st before bu sin ess h ou rs every d ay. In Ch icago, for exam p le, ou tsid e tem p eratu res in th e win ter can d ip to –20° (n ot in clu d in g th e win d -ch ill factor). An office bu ild in g’s in terior tem p eratu re can d rop as low as 50° d u rin g th e weeken d . W h en you arrive Mon d ay m orn in g, th e h eat h as been on for on ly an h ou r or so, bu t th e h ard d isk p latters m igh t n ot yet h ave reach ed even 60° wh en you tu rn on th e system . Du rin g th e first 20 m in u tes of op eration , th e d isk p latters rap id ly rise in tem p eratu re to 120° or m ore. If you h ave an in exp en sive step p er m otor h ard d isk an d begin writin g to th e d isk at th ese low tem p eratu res, you are settin g you rself u p for trou ble.

Tip If you do not leave a system on continuously; at least give it 15 minutes or more to warm up after a cold start before writing to the hard disk. This practice does wonders for the reliability of the data on your disk.

If you d o leave you r system on for lon g p eriod s of tim e, m ake su re th at th e screen is blan k or d isp lays a ran d om im age if th e system is n ot in u se. Th e p h osp h or on th e p ictu re tu be can bu rn if a station ary im age is left on screen con tin u ou sly. High er-p ersisten ce p h osp h or m on och rom e screen s are m ost su scep tible, an d th e color d isp lays with lowp ersisten ce p h osp h ors are th e least su scep tible. Most of th e m on itors u sed with tod ay’s PCs will n ot sh ow th e effect of a screen bu rn . If you ever h ave seen a m on och rom e d isp lay with th e im age of som e p rogram p erm an en tly bu rn ed in —even with th e d isp lay off—you kn ow wh at I m ean . Look at th e m on itors th at d isp lay fligh t in form ation at th e airp ort—th ey u su ally sh ow som e of th e effects of p h osp h or bu rn . Most m od ern d isp lays th at h ave p ower-savin g featu res can au tom atically en ter a stan d by m od e on com m an d by th e system . If you r system h as th ese p ower-savin g fu n ction s, en able th em , as th ey will h elp to red u ce en ergy costs an d p reserve th e m on itor. St at ic Elect ricit y. Static electricity can cau se n u m erou s p roblem s with in a system . Th e p roblem s u su ally ap p ear d u rin g th e win ter m on th s wh en h u m id ity is low or in extrem ely d ry clim ates wh ere th e h u m id ity is low year-rou n d . In th ese cases, you m igh t n eed to take sp ecial p recau tion s to en su re th at you r PC is n ot d am aged . Static d isch arges ou tsid e a system -u n it ch assis are rarely a sou rce of p erm an en t p roblem s with in th e system . Usu ally, th e worst p ossible effect of a static d isch arge to th e case, keyboard , or even a location n ear th e com p u ter, is a p arity ch eck (m em ory) error or a system locku p . In som e cases, I h ave been able to cau se p arity ch ecks or system locku p s by sim p ly walkin g p ast a PC. Most static-sen sitivity p roblem s su ch as th is are cau sed by im p rop er grou n d in g of th e system p ower. Be su re th at you always u se a th ree-p ron g, grou n d ed p ower cord p lu gged in to a p rop erly grou n d ed ou tlet. If you are u n su re abou t th e ou tlet, you can bu y an ou tlet tester like th ose d escribed earlier in th is ch ap ter at m ost electron ics su p p ly or h ard ware stores for on ly a few d ollars. W h en ever you op en a system u n it or h an d le circu its rem oved from th e system , you m u st be m u ch m ore carefu l with static. You can p erm an en tly d am age a com p on en t with a

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static d isch arge if th e ch arge is n ot rou ted to a grou n d . I u su ally recom m en d h an d lin g board s an d ad ap ters first by a grou n d in g p oin t su ch as th e bracket to m in im ize th e p oten tial for static d am age. An easy way to p reven t static p roblem s is with good p ower-lin e grou n d in g, wh ich is extrem ely im p ortan t for com p u ter eq u ip m en t. A p oorly d esign ed p ower-lin e grou n d in g system is on e of th e p rim ary cau ses of p oor com p u ter d esign . Th e best way to p reven t static d am age is to p reven t th e static ch arge from gettin g in to th e com p u ter in th e first p lace. Th e ch assis grou n d in a p rop erly d esign ed system serves as a static gu ard for th e com p u ter th at red irects th e static ch arge safely to th e grou n d . For th is grou n d to be com p lete, th erefore, th e system m u st be p lu gged in to a p rop erly grou n d ed th ree-wire ou tlet. If th e static p roblem is extrem e, you can resort to oth er m easu res. On e is to u se a grou n d ed static m at u n d ern eath th e com p u ter. Tou ch th e m at first before you tou ch th e com p u ter to en su re th at an y static ch arges are rou ted to grou n d an d away from th e system u n it’s in tern al p arts. If p roblem s still p ersist, you m igh t wan t to ch eck ou t th e bu ild in g’s electrical grou n d . I h ave seen in stallation s th at h ad th ree-wire ou tlets th at were ren d ered u seless by th e bu ild in g’s u n grou n d ed electrical service. Pow er-Line Noise. To ru n p rop erly, a com p u ter system req u ires a stead y su p p ly of clean n oise-free p ower. In som e in stallation s, h owever, th e p ower lin e servin g th e com p u ter serves h eavy eq u ip m en t also, an d th e voltage variation s resu ltin g from th e on -off cyclin g of th is eq u ip m en t can cau se p roblem s for th e com p u ter. Certain typ es of eq u ip m en t on th e sam e p ower lin e also can cau se voltage spikes—sh ort tran sien t sign als of som etim es 1,000v or m ore—th at can p h ysically d am age a com p u ter. Alth ou gh th ese sp ikes are rare, th ey can be crip p lin g. Even a d ed icated electrical circu it u sed on ly by a sin gle com p u ter can exp erien ce sp ikes an d tran sien ts, d ep en d in g on th e q u ality of th e p ower su p p lied to th e bu ild in g or circu it. Du rin g th e site-p rep aration p h ase of a system in stallation , you sh ou ld be aware of th ese factors to en su re a stead y su p p ly of clean p ower: ■ If p ossible, th e com p u ter system sh ou ld be on its own circu it with its own circu it breaker. Th is setu p d oes n ot gu aran tee freed om from in terferen ce, bu t it h elp s. ■ Th e circu it sh ou ld be ch ecked for a good , low-resistan ce grou n d , p rop er lin e voltage, freed om from in terferen ce, an d freed om from brownouts (voltage d ip s). ■ A th ree-wire circu it is a m u st, bu t som e p eop le su bstitu te grou n d in g-p lu g ad ap ters to ad ap t a grou n d ed p lu g to a two-wire socket. Th is setu p is n ot recom m en d ed ; th e grou n d is th ere for a reason . ■ Power-lin e n oise p roblem s in crease with th e resistan ce of th e circu it, wh ich is a fu n ction of wire size an d len gth . To d ecrease resistan ce, th erefore, avoid exten sion cord s u n less absolu tely n ecessary, an d th en u se on ly h eavy-d u ty exten sion cord s. ■ In evitably, you will wan t to p lu g in oth er eq u ip m en t later. Plan ah ead to avoid th e tem p tation to con n ect too m an y item s to a sin gle ou tlet. If p ossible, p rovid e a sep arate p ower circu it for n on com p u ter-related d evices.

Preventive M aintenance

Air con d ition ers, coffee m akers, cop y m ach in es, laser p rin ters, sp ace h eaters, vacu u m clean ers, an d p ower tools are som e of th e worst corru p ters of a PC system ’s p ower. An y of th ese item s can d raw an excessive am ou n t of cu rren t an d p lay h avoc with a PC system on th e sam e electrical circu it. I’ve seen offices in wh ich all th e com p u ters begin to crash at abou t 9:05 a.m . d aily, wh ich is wh en all th e coffee m akers are tu rn ed on ! Also, try to en su re th at cop y m ach in es an d laser p rin ters d o n ot sh are a circu it with oth er com p u ter eq u ip m en t. Th ese d evices d raw a large am ou n t of p ower. An oth er m ajor p roblem in som e com p an ies is p artition ed offices. Man y of th ese p artition s are p rewired with th eir own electrical ou tlets an d are p lu gged in to on e an oth er in a sort of p ower-lin e d aisy ch ain , sim ilar to ch ain in g p ower strip s togeth er. I p ity th e p erson in th e cu bicle at th e en d of th e electrical d aisy ch ain , wh o is likely to h ave very erratic p ower! As a real-world exam p le of too m an y d evices sh arin g a sin gle circu it, I can d escribe several in stan ces in wh ich a p erson al com p u ter h ad a rep eatin g p arity ch eck p roblem . All efforts to rep air th e system h ad been u n su ccessfu l. Th e rep orted error location s from th e p arity ch eck m essage were in con sisten t, wh ich n orm ally in d icates a p roblem with p ower. Th e p roblem cou ld h ave been th e p ower su p p ly in th e system u n it or th e extern al p ower su p p lied from th e wall ou tlet. Th is p roblem was solved on e d ay as I stood watch in g th e system . Th e p arity ch eck m essage was d isp layed at th e sam e in stan t som eon e two cu bicles away tu rn ed on a cop y m ach in e. Placin g th e com p u ters on a sep arate lin e solved th e p roblem . By followin g th e gu id elin es in th is section , you can create th e p rop er p ower en viron m en t for you r system s an d h elp to en su re trou ble-free op eration . Radio-Frequency Int erference. Radio-frequency interference (RFI) is easily overlooked as a p roblem factor. Th e in terferen ce is cau sed by an y sou rce of rad io tran sm ission s n ear a com p u ter system . Livin g n ext d oor to a 50,000-watt com m ercial rad io station is on e su re way to get RFI p roblem s, bu t less p owerfu l tran sm itters can cau se p roblem s, too. I kn ow of m an y in stan ces in wh ich cord less telep h on es h ave cau sed sp orad ic ran d om keystrokes to ap p ear, as th ou gh an in visible en tity were typ in g on th e keyboard . I also h ave seen RFI cau se a system to lock u p . Solu tion s to RFI p roblem s are m ore d ifficu lt to state becau se every case m u st be h an d led d ifferen tly. Som etim es, sim p ly m ovin g th e system elim in ates th e p roblem becau se rad io sign als can be d irection al in n atu re. At oth er tim es, you m u st in vest in sp ecially sh ield ed cables for extern al d evices su ch as th e keyboard an d th e m on itor. On e typ e of solu tion to an RFI n oise p roblem with cables is to p ass th e cable th rou gh a toroidal iron core, a d ou gh n u t-sh ap ed p iece of iron p laced arou n d a cable to su p p ress both th e recep tion an d tran sm ission of electrom agn etic in terferen ce (EMI). Man y m on itors in clu d e a toroid on th e cable th at con n ects to th e com p u ter. If you can isolate an RFI n oise p roblem in a p articu lar cable, you often can solve th e p roblem by p assin g th e cable th rou gh a toroid al core. Becau se th e cable m u st p ass th rou gh th e cen ter h ole of th e core, it often is d ifficu lt, if n ot im p ossible, to ad d a toroid to a cable th at alread y h as en d con n ectors in stalled .

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Rad io Sh ack sells a sp ecial sn ap -togeth er toroid d esign ed sp ecifically to be ad d ed to cables alread y in u se. Th is toroid looks like a th ick-walled tu be th at h as been sliced in h alf. You ju st lay th e cable in th e cen ter of on e of th e h alves, an d sn ap th e oth er h alf over th e first. Th is typ e of con stru ction m akes it easy to ad d th e n oise-su p p ression featu res of a toroid to virtu ally an y existin g cable. Th e best, if n ot th e easiest, way to elim in ate an RFI p roblem is to correct it at th e sou rce. It is n ot likely th at you ’ll be able to con vin ce th e com m ercial rad io station n ear you r office to sh u t d own , bu t if you are d ealin g with a sm all rad io tran sm itter th at is gen eratin g RFI, som etim es you can ad d a filter to th e tran sm itter th at su p p resses sp u riou s em ission s. Un fortu n ately, p roblem s som etim es p ersist u n til th e tran sm itter is eith er switch ed off or m oved som e d istan ce away from th e affected com p u ter. Dust and Pollut ant s. Dirt, sm oke, d u st, an d oth er p ollu tan ts are bad for you r system . Th e p ower-su p p ly fan carries airborn e p articles th rou gh you r system , an d th ey collect in sid e. If you r system is u sed in an extrem ely h arsh en viron m en t, you m igh t wan t to in vestigate som e of th e in d u strial system s on th e m arket d esign ed for h arsh con d ition s. Man y com p an ies m ake sp ecial h ard en ed version s of th eir system s for h arsh en viron m en ts. In d u strial system s u su ally u se a d ifferen t coolin g system from th e on e u sed in a regu lar PC. A large coolin g fan is u sed to p ressu rize th e case rath er th an d ep ressu rize it. Th e air p u m p ed in to th e case p asses th rou gh a filter u n it th at m u st be clean ed an d ch an ged p eriod ically. Th e system is p ressu rized so th at n o con tam in ated air can flow in to it; air flows on ly ou tward . Th e on ly way air can en ter is th rou gh th e fan an d filter system . Th ese system s also m igh t h ave sp ecial keyboard s im p erviou s to liq u id s an d d irt. Som e flat-m em bran e keyboard s are d ifficu lt to typ e on , bu t are extrem ely ru gged ; oth ers resem ble th e stan d ard typ es of keyboard s bu t h ave a th in , p lastic m em bran e th at covers all th e keys. You can ad d th is m em bran e to n orm al typ es of keyboard s to seal th em from th e en viron m en t. A n ew breed of h u m id ifier can cau se p roblem s with com p u ter eq u ip m en t. Th is typ e of h u m id ifier u ses u ltrason ics to gen erate a m ist of water sp rayed in to th e air. Th e extra h u m id ity h elp s cu re p roblem s with static electricity resu ltin g from a d ry clim ate, bu t th e airborn e water con tam in an ts can cau se m an y p roblem s. If you u se on e of th ese system s, you m igh t n otice a wh ite ash -like d ep osit form in g on com p on en ts. Th e d ep osit is th e resu lt of abrasive an d corrosive m in erals su sp en d ed in th e vap orized water. If th ese d ep osits collect on th e system com p on en ts, th ey can cau se all kin d s of p roblem s. Th e on ly safe way to ru n on e of th ese u ltrason ic h u m id ifiers is to u se d istilled water. If you u se a h u m id ifier, be su re it d oes n ot gen erate th ese d ep osits. If you d o you r best to keep th e en viron m en t for you r com p u ter eq u ip m en t clean , you r system will ru n better an d last lon ger. Also, you will n ot h ave to op en you r u n it as often for com p lete p reven tive m ain ten an ce clean in g.

Chapter 18

18

Operating Systems Software and Troubleshooting

Th is ch ap ter focu ses on th e op eratin g system s u sed m ost com m on ly on PCs tod ay, an d th eir relation sh ip s to th e PC h ard ware. In form ation abou t op eratin g system s m ay seem ou t of p lace in a book abou t h ard ware u p grad e an d rep air, bu t if you ign ore th e op eratin g system an d oth er software wh en you trou blesh oot a system , you can m iss a n u m ber of p roblem s. Th e best system trou blesh ooters an d d iagn ostician s kn ow th e en tire system —h ard ware an d software.

Most of th e PCs in u se tod ay ru n eith er DOS (u su ally in com bin ation with W in d ows 3.1 or W in d ows for W orkgrou p s) or W in d ows 9x. W in d ows NT is a m ore ad van ced altern ative th at is con stan tly growin g in p op u larity, m ostly in n etwork en viron m en ts. Th is ch ap ter exam in es th e basic stru ctu re of th ese op eratin g system s, th eir com p on en ts, th e system boot p rocess, an d h ow to d istin gu ish a software p roblem from a h ard ware p roblem .

Disk Operat ing Syst em ( DOS) DOS is th e origin al an d m ost basic of PC op eratin g system s. By itself, it is con sid ered to be u n d erp owered an d u n able to su p p ort th e fu ll cap abilities of m u ch of tod ay’s h ard ware. However, th e u n d erlyin g con cep ts of DOS form th e basis for th e m ore ad van ced op eratin g system s u sed tod ay, like W in d ows 95 an d W in d ows 98. W ith th e excep tion of W in d ows NT, all th e op eratin g system s d iscu ssed in th is ch ap ter rely on DOS stru ctu res for th eir basic fu n ction s. Operat ing Syst em Basics DOS is ju st on e com p on en t in a total system arch itectu re. A PC system h as a d istin ct h ierarch y of software th at con trols th e system at all tim es. Even wh en you are workin g in an ap p lication su ch as a word p rocessor or sp read sh eet, th ere are several oth er p rogram m in g layers always execu tin g u n d ern eath th e ap p lication . Ultim ately, th ese software layers p rovid e access to th e h ard ware,

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su ch as storage m ed ia, m em ory, an d th e system p rocessor. Usu ally th e layers can be d efin ed d istin ctly, bu t som etim es th e bou n d aries are vagu e. In m ost cases, com m u n ication s occu r on ly between ad join in g layers in th e system arch itectu re, bu t th is ru le is n ot absolu te. Som e p rogram s ign ore th e services p rovid ed by th e layer d irectly ben eath th em an d elim in ate th e m id d lem an by skip p in g on e or m ore layers. An exam p le of th is is wh en a p rogram ign ores th e DOS an d ROM BIOS vid eo rou tin es an d com m u n icates d irectly with th e vid eo d isp lay h ard ware in th e in terest of th e h igh est p ossible screen p erform an ce. Alth ou gh th e h igh p erform an ce goal is ad m irable, som e op eratin g system s (su ch as OS/ 2 an d W in d ows NT) n o lon ger p erm it d irect access to th e h ard ware. Th is gen erally resu lts in a m ore stable op eratin g en viron m en t with fewer crash es an d system con flicts. Program s th at d o n ot p lay by th e ru les m u st be rewritten to ru n in th ese n ew en viron m en ts. Th e h ard ware is at th e lowest level of th e system h ierarch y. By p lacin g variou s bytes of in form ation at certain p orts or location s with in a system ’s m em ory stru ctu re, you can con trol virtu ally an y d evice con n ected to th e CPU. Main tain in g con trol at th e h ard ware level is d ifficu lt; d oin g so req u ires a com p lete an d accu rate kn owled ge of th e system arch itectu re. Th e atten tion to d etail req u ired to write software op eratin g at th is level is m ost in ten se. To issu e com m an d s to th e system at th is level, you m u st u se m achine language, wh ich con sists of bin ary grou p s of in form ation ap p lied d irectly to th e m icrop rocessor. Mach in e lan gu age in stru ction s are lim ited in th eir fu n ction ; a great m an y of th em are req u ired to p erform even th e sm allest am ou n t of u sefu l work. However, th e large n u m ber of in stru ction s req u ired is n ot a great bu rd en on th e system becau se th ese in stru ction s are execu ted extrem ely rap id ly, wastin g few system resou rces. Program m ers can write cod e con sistin g of m ach in e lan gu age in stru ction s, bu t gen erally th ey u se a tool—an assem bler—to ease th e p rocess. Th ey write p rogram s u sin g an editor an d th en u se th e assem bler to con vert th e ed itor’s ou tp u t to p u re m ach in e lan gu age. Assem bler com m an d s are still very low-level, an d u sin g th em effectively req u ires th at th e p rogram m er be extrem ely kn owled geable. No on e (in th eir righ t m in d ) writes d irectly in m ach in e cod e an ym ore; assem bly lan gu age is th e lowest-level p rogram m in g en viron m en t typ ically u sed tod ay. Even assem bly lan gu age, h owever, is losin g favor am on g p rogram m ers becau se of th e am ou n t of kn owled ge an d work req u ired to com p lete even sim p le tasks, an d becau se of th e d ifficu lty in tran slatin g (or porting) th e cod e to work with an oth er system . W h en you start a PC system , a series of m ach in e cod e p rogram s, th e ROM BIOS, assu m es con trol. Th is set of p rogram s, always p resen t in a system , com m u n icates d irectly (u sin g m ach in e cod e) to th e h ard ware. Th e BIOS accep ts or in terp rets com m an d s gen erated by p rogram s above it in th e system h ierarch y. It th en tran slates th em to m ach in e cod e com m an d s th at are p assed on to th e m icrop rocessor. Com m an d s at th is level typ ically are called interrupts or services. A p rogram m er can u se n early an y lan gu age to su p p ly th ese in stru ction s to th e BIOS.

Disk Operating System (DOS)

DOS is m ad e u p of several com p on en ts. It attach es to th e BIOS so th at p art of DOS actu ally becom es an exten sion of th e BIOS, p rovid in g m ore in terru p ts an d services for oth er p rogram s to u se. DOS p rovid es a com m u n ication bu ffer between th e ROM BIOS an d software ru n n in g at h igh er layers in th e system h ierarch y (su ch as ap p lication s). Becau se DOS p rovid es th e ap p lication p rogram m er with in terru p ts an d services th ey can u se in ad d ition to th ose p rovid ed by th e ROM BIOS, a lot of “rein ven tin g th e wh eel” in p rogram m in g rou tin es is elim in ated . For exam p le, DOS p rovid es a rich set of fu n ction s th at can op en , close, fin d , d elete, create, an d ren am e files, an d can p erform oth er fileh an d lin g tasks. W h en p rogram m ers wan t to in clu d e th ese fu n ction s in th eir p rogram s, th ey can rely on DOS to d o m ost of th e work, rath er th an h ave to d evelop rou tin es th at p erform th ese fu n ction s th em selves.

Not e This integration of hardware functions into the operating system has been one of the basic tenets of operating system development over the years. Successive versions of Windows have built on the DOS model by adding more hardware functions to the OS, thus preventing applications from having to address the hardware directly.

Th is stan d ard set of fu n ction s th at ap p lication s u se to read d ata from an d write it to d isks m akes d ata recovery op eration s p ossible. Im agin e h ow tou gh writin g p rogram s an d u sin g com p u ters wou ld be if every ap p lication p rogram h ad to im p lem en t its own cu stom d isk in terface, with a p rop rietary d irectory an d file retrieval system . Every ap p lication wou ld req u ire its own sp ecial d isks. Fortu n ately, DOS p rovid es a stan d ard set of d ocu m en ted file storage an d retrieval rou tin es th at all software ap p lication s can u se. An oth er p rim ary fu n ction of DOS is to load an d ru n oth er p rogram s. As it p erform s th at fu n ction , DOS is th e shell, or com m an d p rocessor in terface, with in wh ich th e oth er p rogram is execu ted . DOS p rovid es th e fu n ction s an d en viron m en t req u ired by oth er software—in clu d in g op eratin g en viron m en ts su ch as W in d ows 3.x—to ru n on PC system s in a stan d ard way. W in d ows 9x fin ally m arry DOS an d th e W in d ows en viron m en t in to a m ore seam less op eratin g system . However, wh ile th e grap h ical in terface is n ow th e op eration al stan d ard in W in d ows 9x, you can still boot th e op eratin g system to a DOS com m an d p rom p t. The Syst em ROM BIOS Th in k of th e ROM BIOS in a system as a form of com p atibility glu e th at sits between th e PC h ard ware an d th e op eratin g system . W h y is it th at th e sam e DOS op eratin g system can ru n on th e origin al IBM PC an d on th e latest Pen tiu m II system s—two very d ifferen t h ard ware p latform s? If DOS were written to com m u n icate d irectly with th e h ard ware on all system s, it wou ld be a very h ard ware-sp ecific p rogram an d wou ld req u ire exten sive m od ification s for d ifferen t h ard ware con figu ration s. In stead , IBM d evelop ed a set of stan d ard services an d fu n ction s th at each system sh ou ld be cap able of p erform in g, an d cod ed th em as p rogram s in th e ROM BIOS. Each system th en gets a com p letely cu stom ized ROM BIOS th at can talk d irectly to th e h ard ware in th e system an d kn ows exactly h ow to p erform each sp ecific fu n ction on th at h ard ware on ly.

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√√ See “ BIOS,” p. 208

Th is con ven tion en ables th e op eratin g system to be written to wh at is essen tially a stan d ard in terface th at can su p p ort m an y d ifferen t typ es of h ard ware. An y ap p lication s written to th e op eratin g system can u se th at stan d ard in terface to access th e system h ard ware. Figu re 18.1 sh ows th at two very d ifferen t h ard ware p latform s can each h ave a cu stom ROM BIOS th at can talk d irectly to th e h ard ware an d still p rovid e a stan d ard in terface to an op eratin g system . Th e two d ifferen t h ard ware p latform s d escribed in Figu re 18.1 can ru n n ot on ly th e exact sam e version of DOS, bu t also th e sam e ap p lication p rogram s, becau se of th e stan d ard in terfaces p rovid ed by th e ROM BIOS an d DOS. Keep in m in d , h owever, th at th e actu al ROM BIOS cod e d iffers am on g th e sp ecific m ach in es an d th at it is u su ally n ot p ossible to ru n a ROM BIOS d esign ed for on e system in a d ifferen t system . ROM BIOS u p grad es m u st com e from a sou rce th at h as an in tim ate u n d erstan d in g of th e sp ecific m oth erboard on wh ich th e ch ip will be in stalled , becau se th e ROM m u st be cu stom written for th at p articu lar h ard ware. √√ See “ Upgrading the ROM BIOS,” p. 215

System "B" Hardware

System "A" Hardware Non-standard Interface

System "A" ROM BIOS

System "B" ROM BIOS Standard Interface

MS-DOS

MS-DOS Standard Interface

Application Program

Application Program

FIG. 18.1 A rep resen tation of th e software layers in a PC system . Th e p ortion of DOS sh own in Figu re 18.1 is th e system p ortion , or core, of DOS. Th is core is p h ysically m an ifested as th e two system files on an y bootable DOS d isk. Th ese h id d en system files are called IO.SYS an d MSDOS.SYS in MS-DOS an d all version s of DOS licen sed from Microsoft by origin al eq u ip m en t m an u factu rers (OEMs). In IBM DOS, th e files are called IBMBIO.COM an d IBMDOS.COM.

Disk Operating System (DOS)

Figu re 18.1 rep resen ts a sim p lified view of th e system ; som e su btle bu t im p ortan t d ifferen ces exist. Id eally, ap p lication p rogram s are in su lated from th e h ard ware by th e ROM BIOS an d by DOS, bu t in reality m an y p rogram m ers write p ortion s of th eir p rogram s to com m u n icate d irectly with th e h ard ware, circu m ven tin g both DOS an d th e ROM BIOS. A p rogram m ay th erefore work on ly with sp ecific h ard ware, even if th e p rop er DOS an d ROM BIOS in terfaces for th e h ard ware in th e m ach in e are p resen t. Program s d esign ed to com m u n icate d irectly with th e h ard ware u su ally are written th at way to in crease p erform an ce. For exam p le, som e DOS p rogram s access th e vid eo h ard ware d irectly to im p rove screen u p d ate p erform an ce. Ap p lication s like th ese typ ically h ave in stallation p rogram s th at req u ire you to sp ecify exactly wh at h ard ware is p resen t in th e system so th e p rogram can load th e correct h ard ware-d ep en d en t rou tin es in to th e ap p lication . Som e u tility p rogram s absolu tely m u st com m u n icate d irectly with th e system h ard ware to p erform th eir fu n ction . An oth er typ e of system -sp ecific u tility, called a m em ory m anager, en ables exten d ed m em ory in a DOS system to fu n ction as exp an d ed m em ory. Th ese d rivers work by accessin g th e system p rocessor d irectly an d u sin g sp ecific featu res of th e ch ip . An oth er way th at reality m igh t d iffer from th e sim p le view is th at DOS som etim es com m u n icates d irectly with th e h ard ware. Th e DOS system files can con tain low-level d rivers d esign ed to su p p lan t an d su p ersed e p arts of th e ROM BIOS cod e in th e system . W h en DOS load s, it ascertain s th e system typ e an d ID in form ation by q u eryin g th e ROM. It th en load s d ifferen t rou tin es d ep en d in g on wh ich version of ROM it fin d s. For exam p le, th ere are at least fou r d ifferen t h ard d isk cod e section s in PC-DOS, bu t on ly on e is load ed for a sp ecific system . DOS Com ponent s DOS con sists of two p rim ary com p on en ts: th e in p u t/ ou tp u t (I/ O) system an d th e sh ell. Th e I/ O system con sists of th e u n d erlyin g p rogram s th at resid e in m em ory wh ile th e system is ru n n in g; th ese p rogram s load wh en DOS first boots. Th e I/ O system is stored in th e IO.SYS an d MSDOS.SYS (or IBMBIO.COM an d IBMDOS.COM) files th at are flagged with th e h id d en attribu te on a bootable DOS d isk. No m atter wh at th e exact n am es are, th e fu n ction of th ese two files is basically th e sam e for all version s of DOS. Th e u ser in terface p rogram , or sh ell, is stored in th e COMMAND.COM file, wh ich also load s d u rin g a n orm al DOS boot seq u en ce. Th e sh ell is th e p ortion of DOS th at th e u ser em p loys to com m u n icate with th e system , p rovid in g th e DOS p rom p t an d in tern al com m an d s like COPY an d DIR. Th e followin g section s exam in e th e DOS I/ O system an d sh ell in m ore d etail to h elp you p rop erly id en tify an d solve p roblem s th at are related to DOS rath er th an to h ard ware. Also in clu d ed is a d iscu ssion on h ow DOS allocates d isk file sp ace. IO.SYS ( or IBM BIO.COM ) IO.SYS is on e of th e h id d en files fou n d on an y DOS system (bootable) d isk. Th is file con tain s th e low-level p rogram s th at in teract d irectly with d evices on th e system an d th e

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ROM BIOS. Du rin g bootu p , th e DOS volu m e boot sector load s th e file in to low m em ory an d gives it con trol of th e system . Th e en tire file, excep t for th e system in itializer p ortion , rem ain s in m em ory d u rin g n orm al system op eration . For a d isk to be bootable, IO.SYS or its eq u ivalen t m u st be listed as th e first file in th e d irectory of th e d isk an d m u st occu p y at least th e first clu ster on th e d isk (clu ster n u m ber 2). Th e rem ain d er of th e file m igh t be p laced in clu sters an ywh ere across th e rest of th e d isk. Th e file n orm ally is m arked with h id d en , system , an d read -on ly attribu tes, an d p laced on a d isk by th e FORMAT u tility (with th e /S switch ) or by th e SYS u tility.

Creat ing a Boot Disk Writing the DOS system boot files to a hard or floppy disk is a process that involves more than simply copying the files. To create a bootable disk, you must use either the DOS FORM AT.COM program or the SYS.COM program. When you run FORM AT with the /S switch, as in FORMAT A: /S, the program proceeds to format the disk in the usual manner. It then copies the IO.SYS, M SDOS.SYS, and COM M AND.COM files from the drive used to boot the computer, setting the appropriate attributes. The SYS.COM program copies the same files and sets the same attributes, but without formatting the disk first. You must have sufficient space on the disk for SYS.COM to store the boot files. Windows 9x includes the FORM AT.COM and SYS.COM utilities as well, but also provides a GUI alternative for creating boot disks. When you select a drive in Windows 9x Explorer and choose Format from the context menu, you are given the option to copy the system files to the disk as part of the formatting process. You can also create a boot disk by launching the Add/ Remove Programs Control Panel and following the instructions on the Startup Disk page.

M SDOS.SYS ( or IBM DOS.COM ) MSDOS.SYS, th e core of DOS, con tain s th e DOS d isk- an d d evice-h an d lin g p rogram s. MSDOS.SYS is load ed in to low m em ory at system bootu p by th e DOS volu m e boot sector an d rem ain s resid en t in m em ory d u rin g n orm al system op eration . MSDOS.SYS or its eq u ivalen t origin ally h ad to be listed as th e secon d en try in th e root d irectory of an y bootable d isk. Most file m an agem en t u tilities list th e files in a given d irectory in alp h abetical ord er, bu t th is is n ot n ecessarily th e ord er in wh ich th ey are stored on th e d rive. At on e tim e, th e on ly way for th e IO.SYS an d MSDOS.SYS files to be read seq u en tially was for th em to be th e first two p h ysical files on th e d isk. Th e MSDOS.SYS file is flagged with th e h id d en , system , an d read -on ly attribu tes, an d like IO.SYS is p laced on a d isk by th e FORMAT /S com m an d or th e SYS com m an d . Th ere are n ow n o sp ecial req u irem en ts for th e p h ysical p osition in g of th is file on a d isk. The Shell or Com m and Processor ( COM M AND.COM ) Th e DOS com m an d p rocessor COMMAND.COM is th e p ortion of DOS with wh ich u sers n orm ally in teract. Th is file is also written to a system d isk by th e FORMAT /S an d SYS com m an d s, bu t th e file is left visible, u n like IO.SYS an d MSDOS.SYS. DOS load s COMMAND.COM in to m em ory after th e two system files, p rovid in g th e com m an d p rom p t an d access to DOS system com m an d s. Th ese com m an d s can be categorized in to two typ es accord in g to h ow th ey are m ad e available: resident or transient.

Disk Operating System (DOS)

Resident com m ands are bu ilt in to COMMAND.COM an d are available wh en ever th e DOS p rom p t is p resen t. Th ey are gen erally th e sim p ler, freq u en tly u sed com m an d s su ch as COPY, CLS, an d DIR. Resid en t com m an d s execu te rap id ly becau se th e in stru ction s for th em are alread y load ed in to m em ory; th ey are m em ory-resident. W h en you look u p a com m an d in a DOS m an u al, you gen erally fin d som e in d ication of wh eth er th e com m an d is resid en t or tran sien t. You can th en d eterm in e wh at is req u ired to execu te th at com m an d . A sim p le ru le is th at, at a DOS p rom p t, all resid en t com m an d s are in stan tly available for execu tion , with n o load in g of ad d ition al files req u ired . Resid en t com m an d s are also som etim es called internal com m an d s. Com m an d s th at ru n from a sep arate p rogram on d isk are term ed external, or transient com m an d s, an d are also often called utilities. Transient com m ands are n ot resid en t in th e com p u ter’s m em ory; th e in stru ction s to execu te th ese com m an d s m u st be located on a d isk. Becau se th e in stru ction s are load ed in to m em ory on ly for th e execu tion of th e com m an d an d th en are overwritten in m em ory after th ey are u sed , th ey are called tran sien t com m an d s. Most DOS com m an d s are tran sien t; oth erwise, th e m em ory req u irem en ts for DOS wou ld be m u ch larger th an th ey are. Tran sien t com m an d s are u sed less freq u en tly th an resid en t com m an d s an d take lon ger to execu te, becau se th eir d isk files m u st be fou n d an d load ed before th ey can ru n . DOS’ tran sien t com m an d s take th e form of in d ivid u al execu table files, su ch as FORMAT.COM an d XCOPY.COM, th at are located in th e DOS h om e d irectory (typ ically C:\ DOS, or C:\ W INDOW S\ COMMAND in W in d ows 9x). Most execu table files op erate like tran sien t DOS com m an d s. Th e in stru ction s to execu te th e com m an d m u st be located on a d isk. Th e in stru ction s are load ed in to m em ory on ly for execu tion an d are overwritten in m em ory after th e p rogram is n o lon ger bein g u sed . DOS Com m and File Search Procedure On e of th e m ost com m on DOS errors is th e Bad command or filename m essage th at ap p ears wh en you attem p t to issu e a com m an d th at DOS can n ot p rocess. Th is can h ap p en for a n u m ber of reason s, an d you r trou blesh ootin g efforts sh ou ld begin at th e h igh est level, th e software, before you begin to su sp ect th at a h ard ware p roblem m ay be at fau lt. W h en ever you issu e a tran sien t com m an d or ru n a software ap p lication ’s execu table file, DOS attem p ts to fin d th e in stru ction s n eed ed to execu te th at com m an d by lookin g in several p laces, in a sp ecific ord er. Th e in stru ction s th at rep resen t th e com m an d or p rogram are located in files on on e or m ore d isk d rives. Files th at con tain execu tion in stru ction s h ave an exten sion of eith er COM (com m an d files), EXE (execu table files), or BAT (batch files). COM an d EXE files are m ach in e cod e p rogram s; BAT files con tain ASCII text sp ecifyin g a series of com m an d s an d in stru ction s u sin g th e DOS batch facilities. DOS attem p ts to locate th ese execu table files by search in g th e cu rren t d irectory an d th e d irectories sp ecified in th e PATH com m an d . In oth er word s, if you typ e several ch aracters, like W IN, at th e DOS p rom p t an d p ress th e En ter key, DOS attem p ts to fin d an d ru n a p rogram n am ed W IN by p erform in g a two- or th ree-level search for th e p rogram in stru ction s (th e file). Th e first step in lookin g

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for com m an d in stru ction s is to see wh eth er th e com m an d is resid en t in COMMAND.COM an d , if so, to ru n it from th e p rogram cod e alread y load ed in m em ory. If th e com m an d is n ot resid en t, DOS looks in th e cu rren t d irectory for a file called W IN with a COM, EXE, or BAT exten sion (in th at ord er), an d load s an d execu tes th e first file it fin d s with th e sp ecified n am e. Th erefore, if two files in th at d irectory are called W IN.COM an d W IN.BAT, th e W IN.COM file will always be execu ted in resp on se to th e WIN com m an d . If th e com m an d is n ot resid en t an d n o file by th at n am e is fou n d in th e cu rren t d irectory, DOS looks in each of th e d irectories sp ecified in th e DOS PATH en viron m en t variable in tu rn , search in g for th e file u sin g th e sam e exten sion ord er ju st in d icated . (You sp ecify th e d irectories for th e PATH en viron m en t variable u sin g th e PATH com m an d , u su ally from th e AUTOEXEC.BAT file.) Fin ally, if DOS still fails to locate th e req u ired in stru ction s, it d isp lays th e error m essage Bad command or filename. As you can see, th is error m essage can be m islead in g. You m ay p u zzle at th e in ability of DOS to ru n a com m an d file th at clearly is on th e d isk. Th is m igh t lead you to su sp ect a h ard ware p roblem con cern in g th e d isk d rive itself, wh en th e p roblem actu ally stem s from th e fact th at th e com m an d in stru ction s are sim p ly m issin g from th e search areas. A com m on p ractice is to p lace all sim p le com m an d files or u tility p rogram s (tran sien t com m an d s) in on e d irectory an d set th e PATH to p oin t to th at d irectory. Each of th ose p rogram s (or com m an d s) is th en in stan tly available sim p ly by typ in g its n am e from an y DOS p rom p t, ju st as th ou gh it were resid en t in m em ory. Th is p ractice works well on ly for sin gle-load p rogram s su ch as DOS tran sien t com m an d s an d oth er u tilities. Major ap p lication s often con sist of m an y in d ivid u al files an d m igh t h ave p roblem s if th ey are called u p from a rem ote d irectory or d rive u sin g th e DOS PATH. Th is is becau se th e PATH variable h as n o effect wh en th e ap p lication looks for its overlay an d accessory files. On a h ard d isk system , u sers typ ically in stall all tran sien t com m an d s an d u tilities in su bd irectories an d en su re th at th e PATH p oin ts to th ose d irectories. Th e p ath literally is a list of d irectories an d su bd irectories sp ecified in th e AUTOEXEC.BAT file th at tells DOS wh ere to search for files wh en th e com m an d can n ot be fou n d in th e cu rren t d irectory. A p ath on su ch a h ard d rive m ay look like th is: PATH=C:\DOS;C:\BAT;C:\UTILS;

In th e p reviou s exam p le, all th e an cillary p rogram s in clu d ed with th e DOS op eratin g system will be im m ed iately locatable becau se of th e in clu sion of C:\ DOS in th e PATH com m an d . Th e PATH n orm ally can n ot exceed 128 ch aracters in len gth (in clu d in g sp aces, colon s, sem icolon s, an d backslash es). As a resu lt of th is lim itation , you can n ot h ave a PATH th at con tain s all you r d irectories if th e d irectory n am es exceed 128 ch aracters.

Disk Operating System (DOS)

Not e On Windows 9x systems, directories can have names up to 255 characters in length and can contain spaces and other characters that DOS directories cannot. However, since the file system always maintains a truncated directory name using the standard DOS 8.3 naming convention, you can use these short names in the PATH command. To include directory names containing spaces in the PATH command, you must enclose the name in quotes, as in “ C:\ Program Files” .

You can also com p letely sh ort circu it th e DOS com m an d search p roced u re sim p ly by en terin g th e com p lete p ath to th e file at th e com m an d p rom p t. For exam p le, rath er th an in clu d e C:\ DOS in th e PATH an d en ter th is com m an d : CH KD SK you can en ter th e fu ll n am e of th e p rogram : C:\ D OS\ CH KD SK.COM Th e latter com m an d im m ed iately locates an d load s th e CHKDSK p rogram with n o search th rou gh th e cu rren t d irectory or PATH settin g. Th is m eth od of callin g u p a p rogram sp eed s th e location an d execu tion of th e p rogram an d works esp ecially well to in crease th e sp eed of DOS batch file execu tion . It also en ables you to im m ed iately elim in ate p ath p roblem s as th e sou rce of th e Bad command m essage. DOS Versions In m ore th an a d ecad e an d a h alf of d evelop m en t, a great m an y DOS version s h ave been released . IBM released version 1.0 of th e op eratin g system in 1981, bu t by version 3.x Microsoft too began releasin g its own DOS, u sin g th e sam e version n u m bers as IBM in m ost cases. Early version s of DOS were freq u en tly d esign ed for th e h ard ware con figu ration s of sp ecific m ach in es. At on e tim e, IBM, Com p aq , an d oth er origin al eq u ip m en t m an u factu rers wou ld h ave th eir own version s of DOS (created by IBM or Microsoft), d esign ed to su p p ort on ly th eir h ard ware. You cou ld n ot, in m an y cases, boot an IBM com p u ter u sin g a Com p aq DOS boot d isk an d still gain fu ll fu n ction ality. DOS 5.x. By th e tim e th at DOS 5.0 was released by Microsoft, h owever, th is situ ation was all bu t elim in ated . DOS 5.0 was th e first version of th e op eratin g system to be m arketed on a retail level, an d u sers tu rn ed ou t in d roves to u p grad e th eir system s. Both th e IBM an d Microsoft version s of DOS 5.0 an d later can be u sed on alm ost an y system , alth ou gh later version s m ay be req u ired to u se som e of th e latest h ard ware available. DOS 5.0 offered vastly im p roved m em ory m an agem en t an d in corp orated m an y of th e featu res in to th e op eratin g system th at u sers h ad grown u sed to fin d in g in th ird -p arty u tilities. At th is tim e, th ere are som e p eop le wh o still swear by DOS 5.0 an d resist u p grad in g to DOS 6 (or h igh er), wh ich , tru th to tell, is m ore of an en h an cem en t th an a m ajor overh au l. However, th ere is n o reason an y DOS version below 5.0 sh ou ld still be in u se on an y com p u ter (excep t for m u seu m p ieces th at can h an d le n oth in g bu t th eir n ative version s).

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IBM and M S DOS 6.xx. After DOS 5.0, th ere were several d ifferen t version s of DOS 6.xx from both Microsoft an d IBM. Th e origin al release of MS DOS 6.0 cam e from Microsoft. On e of th e n ew featu res in clu d ed in 6.0 was Dou bleSp ace d isk com p ression , an au tom atic com p ression en gin e th at cou ld effectively d ou ble th e com p u ter’s d isk sp ace, in m ost cases. Un fortu n ately, Dou bleSp ace h ad som e p roblem s with certain system con figu ration s an d h ard ware typ es. In th e m ean tim e, IBM took DOS 6.0 from Microsoft, u p d ated it to fix several sm all p roblem s, rem oved th e d isk com p ression featu re, an d sold it as IBM DOS 6.1. Microsoft h ad m an y p roblem s with th e Dou bleSp ace d isk com p ression u sed in 6.0 an d released 6.2 as a free bu g-fix u p grad e. Microsoft th en ran in to legal p roblem s in th e form of a lawsu it brou gh t by Stacker Corp oration th at accu sed Microsoft of h avin g in frin ged on its righ ts to th e com p ression algorith m u sed by its Stacker software p rod u ct. As a resu lt of th e su it, Microsoft rem oved th e Dou bleSp ace com p ression featu re from DOS 6.2, wh ich was re-released as 6.21. Microsoft th en q u ickly d evelop ed a n on -in frin gin g d isk com p ression u tility called DriveSp ace, wh ich th ey released in version 6.22, alon g with several m in or bu g fixes. IBM skip p ed over th e 6.2 version n u m ber an d released DOS 6.3 (n ow called PC DOS), wh ich also in clu d ed a d ifferen t typ e of com p ression p rogram th an th at u sed by Microsoft. By avoid in g th e Dou bleSp ace software, IBM also avoid ed th e bu gs an d legal p roblem s th at Microsoft h ad en cou n tered . Also in clu d ed in th e u p d ated IBM releases were en h an ced PCMCIA an d p ower m an agem en t com m an d s. Th e d evelop m en t of DOS as a stan d alon e p rod u ct effectively ceased with MS-DOS 6.22 an d PC-DOS 7. However, th e W in d ows 95 an d 98 op eratin g system s are based on th e DOS m od el. If you ru n a u tility like MS-DOS 6.x’s MSD (Microsoft Diagn ostics) on a W in d ows 95 or W in d ows 98 m ach in e, you will see th at th e op eratin g system id en tifies itself as MS-DOS version 7.0 or 7.10, th e n ext step in th e evolu tion of th e op eratin g system . Pot ent ial DOS Upgrade Problem s You alread y kn ow th at th e DOS system files h ave sp ecial p lacem en t req u irem en ts on a h ard d isk. Som etim es th ese sp ecial req u irem en ts cau se p roblem s wh en you are u p grad in g from on e version of DOS to an oth er. If you h ave attem p ted to u p grad e a PC system from on e version of DOS to an oth er, you kn ow th at you u se th e DOS SYS com m an d to rep lace th e old system files with n ew on es. Th e SYS com m an d cop ies th e existin g system files (stored on a bootable d isk with h id d en , system , an d read -on ly attribu tes) to th e d isk, in th e correct p osition an d with th e correct n am es an d attribu tes. Th e COPY com m an d d oes n ot cop y h id d en or system files (n or wou ld it p lace th e system files in th e req u ired p osition s on th e d estin ation d isk if you m od ify th e file attribu tes to u se COPY). In ad d ition to tran sferrin g th e two h id d en system files from on e d isk to an oth er, SYS also cop ies th e COMMAND.COM file an d u p d ates th e DOS volu m e boot sector on th e d estin ation d isk so it is correct for th e n ew version of DOS.

Disk Operating System (DOS)

W h en you execu te th e SYS com m an d , you are u su ally greeted by on e of two m essages: System transferred

or No room for system on destination disk

In DOS version s 3.3 an d earlier, if a d isk h as d ata on it before you try to write th e system files to it, th e SYS com m an d will p robably fail, becau se it is n ot cap able of m ovin g oth er files ou t of th e way. Th e SYS com m an d in DOS 4.0 an d h igh er version s rarely fails, becau se it can m ove files ou t of th e way to p u t th e system files in th e correct p laces. Som e u sers th in k th at th e cau se of th e No room m essage on a system with an old er version of DOS is th at th e system files in th e n ewer DOS version are larger th an th ose of th e p reviou s version , an d th at th e n ew files can n ot fit in to th e sp ace allocated for th e old er version s. Th ey believe th at th e com m an d fails becau se th is sp ace can n ot be p rovid ed at th e begin n in g of th e d isk with ou t m ovin g oth er d ata away. Th is is in correct. Th e SYS com m an d fails in th ese cases becau se you are tryin g to in stall a version of DOS th at h as file n am es d ifferen t from th ose alread y on th e d isk. Th ere is n o n orm al reason for th e SYS com m an d to fail wh en you u p d ate th e system files on a d isk th at alread y h as th em . Th e system files can be located virtu ally an ywh ere on th e d isk, excep t th at th e first clu ster (or allocation u n it) of th e d isk m u st con tain th e first clu ster of th e IO.SYS file (or its eq u ivalen t). As lon g as th at req u irem en t is m et, th e IO.SYS an d MSDOS.SYS files can be fragm en ted an d scattered abou t on th e d isk like an y oth er files, an d th e SYS com m an d im p lem en ts th em with n o p roblem s wh atsoever. Th e on ly oth er req u irem en t is th at th e n am es IO.SYS an d MSDOS.SYS (or th eir eq u ivalen ts) m u st u se th e first an d secon d d irectory en tries. DOS 4.0 and Lat er Versions. Becau se th e system files m u st u se th e first two en tries in th e root d irectory of th e d isk an d th e first clu ster (clu ster 2) of th e d isk, th e version s of th e SYS com m an d in DOS version s 4.0 an d later au tom atically m ove an y files occu p yin g th e first two en tries oth er th an th e two system files to oth er available en tries in th e root d irectory. Th e SYS com m an d also m oves th e p ortion of an y foreign file occu p yin g th e first clu ster to oth er clu sters on th e d isk. Th e SYS com m an d in DOS version s 5.0 an d 6.x go on e step fu rth er: Th ey rep lace old system files with th e n ew on es. Even if th e old system files h ad oth er n am es, DOS 5.0 an d h igh er en su re th at th ey are overwritten by th e n ew system files. W ith th e en h an ced SYS com m an d in DOS 4.0 an d later version s, it is d ifficu lt to m ake a DOS u p grad e fail. W indow s 95. W h en you in stall W in d ows 95 on a system ru n n in g DOS, th e Setu p p rogram ren am es th e existin g system files with a DOS exten sion an d rep laces th em with th e W in d ows 95 version s of IO.SYS an d MSDOS.SYS. On ce th e op eratin g system is in stalled , you can in voke a boot m en u by p ressin g th e F8 key as th e com p u ter starts, wh ich en ables you to boot th e system to th e old DOS version , if n eed ed . To d o th is, th e OS sim p ly ren am es th e W in d ows 95 system files with th e exten sion W 95 an d ren am es th e DOS files back to SYS.

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The Boot Process Th e term boot com es from th e word bootstrap an d d escribes th e m eth od by wh ich th e PC becom es op eration al. Ju st as you p u ll on a large boot by th e sm all strap attach ed to th e back, a PC load s a large op eratin g system by first load in g a sm all p rogram th at can th en p u ll th e op eratin g system in to m em ory. Th e ch ain of even ts begin s with th e ap p lication of p ower, an d fin ally resu lts in a fu lly fu n ction al com p u ter system with software load ed an d ru n n in g. Each even t is triggered by th e even t before it an d in itiates th e even t after it. Tracin g th e system boot p rocess m igh t h elp you fin d th e location of a p roblem if you exam in e th e error m essages th at th e system d isp lays wh en th e p roblem occu rs. If you see an error m essage th at is d isp layed on ly by a p articu lar p rogram , you can be su re th at th e p rogram in q u estion was at least load ed an d p artially ru n n in g. Com bin e th is in form ation with th e kn owled ge of th e boot seq u en ce, an d you can at least tell h ow far alon g th e system ’s startu p p roced u re h as p rogressed before th e p roblem occu rred . You u su ally wan t to look at wh atever files or d isk areas were bein g accessed d u rin g th e failu re in th e boot p rocess. Error m essages d isp layed d u rin g th e boot p rocess an d th ose d isp layed d u rin g n orm al system op eration can be h ard to d ecip h er. However, th e first step in d ecod in g an error m essage is to kn ow wh ere th e m essage cam e from —wh at p rogram actu ally gen erated or d isp layed it. Th e followin g p rogram s are cap able of d isp layin g error m essages d u rin g th e boot p rocess: ■ Moth erboard ROM BIOS ■ Ad ap ter card ROM BIOS exten sion s ■ Master p artition boot sector ■ DOS volu m e boot sector ■ System files (IO.SYS./ IBMBIO.COM an d MSDOS.SYS/ IBMDOS.COM) ■ Device d rivers (load ed th rou gh CONFIG.SYS or th e W in 9x Registry SYSTEM.DAT) ■ Sh ell p rogram (COMMAND.COM in DOS) ■ Program s ru n by AUTOEXEC.BAT, th e W in d ows 9x Startu p grou p , an d th e Registry ■ W in d ows (W IN.COM) Th e followin g section exam in es th e system startu p seq u en ce an d p rovid es a d etailed accou n t of m an y of th e error m essages th at m igh t occu r d u rin g th is p rocess. How DOS Loads and St art s If you h ave a p roblem with you r system d u rin g startu p an d you can d eterm in e wh ere in th is seq u en ce of even ts you r system h as stalled , you kn ow wh at even ts h ave occu rred an d you p robably can elim in ate each of th em as a cau se of th e p roblem . Th e followin g step s occu r in a typ ical system startu p :

Disk Operating System (DOS)

1. You switch on electrical p ower to th e system . 2. Th e p ower su p p ly p erform s a self-test (kn own as th e POST—Power On Self Test). W h en all voltages an d cu rren t levels are accep table, th e su p p ly in d icates th at th e p ower is stable an d sen d s th e Power_Good sign al to th e m oth erboard . Th e tim e from switch -on to Power_Good is n orm ally between .1 an d .5 secon d s. 3. Th e m icrop rocessor tim er ch ip receives th e Power_Good sign al, wh ich cau ses it to stop gen eratin g a reset sign al to th e m icrop rocessor. √√ See “ The Power_Good Signal,” p. 409

4. Th e m icrop rocessor begin s execu tin g th e ROM BIOS cod e, startin g at m em ory ad d ress FFFF:0000. Becau se th is location is on ly 16 bytes from th e very en d of th e available ROM sp ace, it con tain s a JMP (ju m p ) in stru ction to th e actu al ROM BIOS startin g ad d ress. √√ See “ ROM ,” p. 304

5. Th e ROM BIOS p erform s a test of th e cen tral h ard ware to verify basic system fu n ction ality. An y errors th at occu r are in d icated by au d io “beep ” cod es becau se th e vid eo system h as n ot yet been in itialized . 6. Th e BIOS p erform s a vid eo ROM scan of m em ory location s C000:0000 th rou gh C780:0000, lookin g for vid eo ad ap ter ROM BIOS p rogram s con tain ed on a vid eo ad ap ter fou n d eith er on a card p lu gged in to a slot or in tegrated in to th e m oth erboard . If th e scan locates a vid eo ROM BIOS, it is tested by a ch ecksu m p roced u re. If th e vid eo BIOS p asses th e ch ecksu m test, th e ROM is execu ted ; th e vid eo ROM cod e in itializes th e vid eo ad ap ter an d a cu rsor ap p ears on -screen . If th e ch ecksu m test fails, th e followin g m essage ap p ears: C000 ROM Error

7. If th e BIOS fin d s n o vid eo ad ap ter ROM, it u ses th e m oth erboard ROM vid eo d rivers to in itialize th e vid eo d isp lay h ard ware, an d a cu rsor ap p ears on -screen . 8. Th e m oth erboard ROM BIOS scan s m em ory location s C800:0000 th rou gh DF80:0000 in 2K in crem en ts for an y oth er ROMs located on an y oth er ad ap ter card s (su ch as SCSI ad ap ters). If an y ROMs are fou n d , th ey are ch ecksu m -tested an d execu ted . Th ese ad ap ter ROMs can alter existin g BIOS rou tin es an d establish n ew on es. 9. Failu re of a ch ecksu m test for an y of th ese ROM m od u les cau ses th is m essage to ap p ear: XXXX ROM Error

wh ere th e ad d ress XXXX in d icates th e segm en t ad d ress of th e failed ROM m od u le.

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10. Th e ROM BIOS ch ecks th e word valu e at m em ory location 0000:0472 to see wh eth er th is start is a cold start or a warm start. A word valu e of 1234h in th is location is a flag th at in d icates a warm start, wh ich cau ses th e BIOS to skip th e m em ory test p ortion of th e POST (Power On Self Test). An y oth er word valu e in th is location in d icates a cold start an d th e BIOS p erform s th e fu ll POST p roced u re. Som e system BIOSs let you con trol variou s asp ects of th e POST p roced u re, m akin g it p ossible to skip th e m em ory test, for exam p le, wh ich can be len gth y on a system with a lot of RAM. √√ See “ POST Audio Error Codes,” p. 985

11. If th is is a cold start, th e POST execu tes. An y errors fou n d d u rin g th e POST are rep orted by a com bin ation of au d io an d d isp layed error m essages. Su ccessfu l com p letion of th e POST is in d icated by a sin gle beep . 12. Th e ROM BIOS search es for a DOS volu m e boot sector at cylin d er 0, h ead 0, sector 1 (th e very first sector) on th e d efau lt boot d rive. At on e tim e, th e d efau lt boot d rive was always th e first flop p y d isk, or A: d rive. However, th e BIOSs on tod ay’s system s often en able you to select th e d efau lt boot d evice an d th e ord er th at th e BIOS will look for oth er d evices to boot from if n eed ed , u sin g eith er a flop p y d isk, h ard d isk, or even a CD-ROM d rive in an y ord er you ch oose. Th is sector is load ed in to m em ory at 0000:7C00 an d tested . If a d isk is in th e d rive bu t th e sector can n ot be read , or if n o d isk is p resen t, th e BIOS con tin u es with th e n ext step . 13. If th e first byte of th e DOS volu m e boot sector load ed from th e d isk in th e d efau lt boot d rive is less th an 06h , or if th e first byte is greater th an or eq u al to 06h an d th e first n in e word s con tain th e sam e d ata p attern , th is error m essage ap p ears an d th e system stop s: 602-Diskette Boot Record Error

14. If th e d isk was p rep ared with FORMAT or SYS u sin g DOS 3.3 or an earlier version an d th e sp ecified system files are n ot th e first two files in th e d irectory, or if a p roblem was en cou n tered load in g th em , th e followin g m essage ap p ears: Non-System disk or disk error Replace and strike any key when ready

15. If th e d isk was p rep ared with FORMAT or SYS u sin g DOS 3.3 or an earlier version an d th e boot sector is corru p t, you m igh t see th is m essage: Disk Boot failure

16. If th e d isk was p rep ared with FORMAT or SYS u sin g DOS 4.0 an d later version s, an d th e sp ecified system files are n ot th e first two files in th e d irectory, or if a p roblem was en cou n tered load in g th em , or th e boot sector is corru p t, th is m essage ap p ears: Non-System disk or disk error Replace and press any key when ready

Disk Operating System (DOS)

17. If n o DOS volu m e boot sector can be read from d rive A:, th e BIOS looks for a m aster p artition boot sector at cylin d er 0, h ead 0, sector 1 (th e very first sector) of th e first fixed d isk. If th is sector is fou n d , it is load ed in to m em ory ad d ress 0000:7C00 an d tested for a sign atu re. 18. If th e last two (sign atu re) bytes of th e m aster p artition boot sector are n ot eq u al to 55AAh , software in terru p t 18h (In t 18h ) is in voked on m ost system s. Th is cau ses th e BIOS to d isp lay an error m essage th at can vary for d ifferen t BIOS m an u factu rers, bu t wh ich is often som eth in g like on e of th e followin g fou r m essages: Non-System disk or disk error replace and strike any key when ready DISK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS ENTER No boot device available strike F1 to retry boot, F2 for setup utility No boot sector on fixed disk strike F1 to retry boot, F2 for setup utility

Alth ou gh th e m essages vary from BIOS to BIOS, th e cau se for each relates to sp ecific bytes in th e Master Boot Record , wh ich is th e first sector of a h ard d isk at th e p h ysical location Cylin d er 0, Head 0, Sector 1. Th e p roblem in volves a d isk th at h as eith er n ever been p artition ed or h as h ad th e Master Boot Sector corru p ted . Du rin g th e boot p rocess, th e BIOS ch ecks th e last two bytes in th e Master Boot Record (first sector of th e d rive) for a “sign atu re” valu e of 55AAh . If th e last two bytes are n ot 55AAh , an In terru p t 18h is in voked , wh ich calls th e su brou tin e th at d isp lays on e of th e error m essages ju st sh own . Th e Master Boot Sector (in clu d in g th e sign atu re bytes) is written to th e h ard d isk by th e DOS FDISK p rogram . Im m ed iately after a h ard d isk is low-level form atted , all th e sectors are in itialized with a p attern of bytes, an d th e first sector d oes not con tain th e 55AAh sign atu re. In oth er word s, th ese ROM error m essages are exactly wh at you see if you attem p t to boot from a h ard d isk th at h as been low-level form atted , bu t h as n ot yet been p artition ed . 19. Th e m aster p artition boot sector p rogram search es its p artition table for an en try with a system in d icator byte in d icatin g an exten d ed p artition . If th e p rogram fin d s su ch an en try, it load s th e exten d ed p artition boot sector at th e location in d icated . Th e exten d ed p artition boot sector also h as a table th at is search ed for an oth er exten d ed p artition . If an oth er exten d ed p artition en try is fou n d , th at exten d ed p artition boot sector is load ed from th e location in d icated . Th e search con tin u es u n til eith er n o m ore exten d ed p artition s are in d icated or th e m axim u m n u m ber of 24 total p artition s h as been reach ed .

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20. Th e m aster p artition boot sector search es its p artition table for a boot in d icator byte m arkin g an active p artition . 21. If n on e of th e p artition s is m arked active (bootable), th e BIOS d isp lays a d isk error m essage. 22. If an y boot in d icator in th e m aster p artition boot record table is in valid , or if m ore th an on e in d icates an active p artition , th e followin g m essage is d isp layed , an d th e system stop s: Invalid partition table

23. If an active p artition is fou n d in th e m aster p artition boot sector, th e volu m e boot sector from th e active p artition is load ed an d tested . 24. If th e DOS volu m e boot sector can n ot be read su ccessfu lly from th e active p artition with in five retries becau se of read errors, th is m essage ap p ears an d th e system stop s: Error loading operating system

25. Th e h ard d isk’s DOS volu m e boot sector is tested for a sign atu re. If th e DOS volu m e boot sector d oes n ot con tain a valid sign atu re of 55AAh as th e last two bytes in th e sector, th is m essage ap p ears an d th e system stop s: Missing operating system

26. Th e volu m e boot sector is execu ted as a p rogram . Th is p rogram ch ecks th e root d irectory to en su re th at th e first two files are IO.SYS (or IBMBIO.COM) an d MSDOS.SYS (or IBMDOS.COM). If th ese files are p resen t, th ey are load ed . 27. If th e d isk was p rep ared with FORMAT or SYS u sin g DOS 3.3 or an earlier version an d th e sp ecified system files are n ot th e first two files in th e d irectory, or if a p roblem is en cou n tered load in g th em , th e followin g m essage ap p ears: Non-System disk or disk error Replace and strike any key when ready

28. If th e d isk was p rep ared with FORMAT or SYS u sin g DOS 3.3 or an earlier version an d th e boot sector is corru p t, you m igh t see th is m essage: Disk Boot failure

29. If th e d isk was p rep ared with FORMAT or SYS u sin g DOS 4.0 or a later version an d th e sp ecified system files are n ot th e first two files in th e d irectory, or if a p roblem is en cou n tered load in g th em , or th e boot sector is corru p t, th e followin g m essage ap p ears: Non-System disk or disk error Replace and press any key when ready

30. If n o p roblem s occu r, th e DOS volu m e boot sector execu tes IO.SYS/ IBMBIO.COM. On a W in d ows 9x system , if you activate th e boot m en u by p ressin g th e F8 key at th is tim e, you can select th e op eratin g system files th at you wan t to load .

Disk Operating System (DOS)

31. Th e in itialization cod e in IO.SYS/ IBMBIO.COM cop ies itself in to th e h igh est region of con tigu ou s DOS m em ory an d tran sfers con trol to th e cop y. Th e in itialization cod e cop y th en relocates MSDOS.SYS over th e p ortion of IO.SYS in low m em ory th at con tain s th e in itialization cod e, becau se th e in itialization cod e n o lon ger n eed s to be in th at location . W in d ows 9x’s IO.SYS com bin es th e fu n ction s of DOS’s IO.SYS an d MSDOS.SYS. 32. Th e in itialization cod e execu tes MSDOS.SYS (or IBMDOS.COM), wh ich in itializes th e base d evice d rivers, d eterm in es eq u ip m en t statu s, resets th e d isk system , resets an d in itializes attach ed d evices, an d sets th e system d efau lt p aram eters. 33. Th e fu ll DOS file system is active, an d con trol is retu rn ed to th e IO.SYS in itialization cod e. 34. Th e IO.SYS in itialization cod e read s th e CONFIG.SYS file m u ltip le tim es. In W in d ows 9x, IO.SYS also looks for th e SYSTEM.DAT Registry file. 35. W h en load in g CONFIG.SYS, th e DEVICE statem en ts are first p rocessed in th e ord er in wh ich th ey ap p ear. An y d evice d river files n am ed in th ose DEVICE statem en ts are load ed an d execu ted . Th en an y INSTALL statem en ts are p rocessed in th e ord er in wh ich th ey ap p ear; th e p rogram s n am ed are load ed an d execu ted . Th e SHELL statem en t is p rocessed an d load s th e sp ecified com m an d p rocessor with th e sp ecified p aram eters. If th e CONFIG.SYS file con tain s n o SHELL statem en t, th e d efau lt \ COMMAND.COM p rocessor is load ed with d efau lt p aram eters. Load in g th e com m an d p rocessor overwrites th e in itialization cod e in m em ory (becau se th e job of th e in itialization cod e is fin ish ed ). In W in d ows 9x, th e system looks in th e Registry’s Hkey_Local_Mach in e\ System \ Cu rren tCon trolSet key to load th e d evice d rivers an d oth er p aram eters sp ecified th ere before execu tin g th e CONFIG.SYS file. Th e COMMAND.COM p rogram is load ed at th is tim e on ly if an AUTOEXEC.BAT file exists, so it can p rocess th e com m an d s con tain ed with in it. Th e W in d ows 9x boot m en u also p rovid es a safe m ode op tion . Th is op tion byp asses th e load in g of th e d rivers for th e sp ecific h ard ware in th e system an d in stead load s a set of gen eric d rivers d esign ed to get th e system u p an d ru n n in g with on ly m in im al fu n ction ality. Th is en ables th e com p u ter to boot th e W in d ows GUI in situ ation s wh ere a m alfu n ction in g d river or d evice wou ld oth erwise p reven t access to th e system . Du rin g th e fin al read s of CONFIG.SYS, all of th e rem ain in g statem en ts are read an d p rocessed in a p red eterm in ed ord er. Th u s, th e ord er of ap p earan ce for statem en ts oth er th an DEVICE, INSTALL, an d SHELL in CONFIG.SYS is of n o sign ifican ce. 36. If AUTOEXEC.BAT is p resen t, COMMAND.COM load s an d ru n s AUTOEXEC.BAT. After th e com m an d s in AUTOEXEC.BAT h ave been execu ted , th e DOS p rom p t ap p ears (u n less th e AUTOEXEC.BAT calls an ap p lication p rogram or sh ell of som e kin d , in wh ich case th e u ser m igh t op erate th e system with ou t ever seein g a DOS p rom p t).

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37. If n o AUTOEXEC.BAT file is p resen t, COMMAND.COM execu tes th e in tern al DATE an d TIME com m an d s, d isp lays a cop yrigh t m essage, an d d isp lays th e DOS p rom p t. In W in d ows 9x, IO.SYS au tom atically load s HIMEM.SYS, IFSHLP.SYS, an d SETVER.EXE. Fin ally, it load s W IN.COM an d W in d ows 9x is officially started . Som e m in or variation s from th is scen ario are p ossible, su ch as th ose in trod u ced by oth er ROM p rogram s in th e variou s ad ap ters th at m igh t be p lu gged in to an exp an sion slot. Also, d ep en d in g on th e exact ROM BIOS p rogram s in volved , som e of th e error m essages an d seq u en ces m igh t vary. Gen erally, h owever, a com p u ter follows th is ch ain of even ts wh ile “com in g to life.” You can m od ify th e system startu p p roced u res by alterin g th e CONFIG.SYS an d AUTOEXEC.BAT files, or th e W in d ows 9x Registry. Th ese files con trol th e con figu ration of DOS or W in d ows 9x an d allow sp ecial startu p p rogram s to be execu ted every tim e th e system starts. File M anagem ent DOS u ses several elem en ts an d stru ctu res to store an d retrieve in form ation on a d isk. Th ese elem en ts an d stru ctu res en able DOS to com m u n icate p rop erly with both th e ROM BIOS an d with ap p lication p rogram s to p rocess file storage an d retrieval req u ests. Un d erstan d in g th ese stru ctu res an d h ow th ey in teract h elp you to trou blesh oot an d even rep air th ese stru ctu res. On d em an d DOS allocates d isk sp ace for a file (sp ace is n ot p reallocated ). Th e sp ace is allocated on e cluster (or allocation u n it) at a tim e. A clu ster always con sists of on e or m ore sectors. √√ See “ Sectors,” p. 724

Th e clu sters are arran ged on a d isk to m in im ize h ead m ovem en t for m u ltisid ed m ed ia. DOS allocates all th e sp ace on a d isk cylin d er before m ovin g to th e n ext cylin d er. It d oes th is by u sin g th e sectors u n d er th e first h ead an d th en all th e sectors u n d er each su ccessive h ead , u n til all sectors of all h ead s of th e cylin d er are u sed . Th e n ext sector DOS u ses is sector 1 of h ead 0 on th e n ext cylin d er. Th e algorith m th at DOS 3.0 an d later version s u se for file allocation is called th e Next Available Cluster algorithm . In th is algorith m , th e search for available clu sters in wh ich to write a file starts n ot at th e begin n in g of th e d isk, as in p reviou s DOS version s, bu t rath er from wh ere th e last write occu rred . Th erefore, th e d isk sp ace freed by erasin g a file is n ot n ecessarily reu sed im m ed iately. Rath er, DOS m ain tain s a Last W ritten Cluster pointer an d begin s its search from th at p oin t. Th is p oin ter is m ain tain ed in system RAM an d is lost wh en th e system is reset or rebooted , or wh en a d isk is ch an ged in a flop p y d rive. Th e Next Available Clu ster algorith m is faster th an th e First Available Clu ster algorith m of earlier DOS version s an d h elp s to m in im ize fragm en tation . Som etim es th is typ e of algorith m is called elevator seeking becau se write op eration s occu r at h igh er an d h igh er

Disk Operating System (DOS)

clu sters u n til th e h ead s reach th e en d of th e d isk area. At th at tim e, th e p oin ter is reset, an d write op eration s work th eir way from th e begin n in g of th e d isk again . Files still en d u p becom in g fragm en ted u sin g th e Next Available Clu ster algorith m , becau se th e p oin ter is reset after a reboot, a d isk ch an ge op eration , or wh en th e en d of th e d isk is reach ed . Neverth eless, a great ben efit of th e m eth od is th at it m akes u n erasin g files m ore likely to su cceed even if th e d isk h as been written to sin ce th e erasu re, becau se th e file ju st erased is n ot likely to be th e target of th e n ext write op eration . In fact, it m igh t be som e tim e before th e clu sters occu p ied by th e erased file are reu sed . Even wh en DOS overwrites a file, it d oes n ot reu se th e clu sters occu p ied by th e origin al file d u rin g th e overwrite. For exam p le, if you accid en tally save a file u sin g th e sam e n am e as an im p ortan t file th at alread y exists, DOS m arks th e existin g file clu sters as available, an d writes th e n ew file (with th e sam e n am e) to th e d isk in oth er clu sters. It is often p ossible, th erefore, to recover th e origin al cop y of th e file. Th is is often h ow u n d elete u tilities su ch as th e UNDELETE com m an d in DOS an d oth er th ird p arty p rod u cts are able to recover d eleted files. Safety u tilities like th e W in d ows 9x Recycle Bin , h owever, d o n ot work in th e sam e way. Th e Recycle Bin is actu ally ju st a d irectory to wh ich th e system m oves d eleted files. Th e file system con tin u es to register th e sp ace occu p ied by th e “d eleted ” files as in u se. Th e Recycle Bin d irectory is con figu red with a m axim u m p ossible size th at, wh en reach ed , cau ses th e system to d elete th e old est files stored th ere. Int erfacing t o Disk Drives DOS u ses a com bin ation of d isk m an agem en t com p on en ts to m ake files accessible. Th ese com p on en ts d iffer sligh tly between flop p ies an d h ard d isks an d between d isks of d ifferen t sizes. Th ey d eterm in e h ow a d isk ap p ears to DOS an d to ap p lication s. Each com p on en t u sed to d escribe th e d isk system fits as a layer in to th e com p lete system . Each layer com m u n icates with th e layer above an d below it. W h en all th e com p on en ts work togeth er, an ap p lication can access th e d isk to fin d an d store d ata. Th ere are fou r p rim ary in terface layers between an ap p lication p rogram ru n n in g on a system an d th e d isk d rives attach ed to th e system . Th ey con sist of software rou tin es th at can p erform variou s fu n ction s, u su ally to com m u n icate with th e ad jacen t layers. Th ese layers are as follows: ■ DOS In terru p t 21h (In t 21h ) rou tin es ■ DOS In terru p t 25/ 26h (In t 25/ 26h ) rou tin es ■ ROM BIOS d isk In terru p t 13h (In t 13h ) rou tin es ■ Disk con troller I/ O p ort com m an d s Each layer accep ts variou s com m an d s, p erform s d ifferen t fu n ction s, an d gen erates resu lts. Th ese in terfaces are available for both flop p y d isk d rives an d h ard d isks, alth ou gh th e flop p y d isk an d h ard d isk In t 13h rou tin es d iffer wid ely. Th e flop p y d isk con trollers an d h ard d isk con trollers are very d ifferen t as well, bu t all th e layers p erform th e sam e fu n ction s for both flop p y d isks an d h ard d isks.

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Int errupt 21h. Th e DOS In t 21h rou tin es exist at th e h igh est level an d p rovid e th e m ost fu n ction ality with th e least am ou n t of work. For exam p le, if an ap p lication p rogram n eed s to create a su bd irectory on a d isk, it can call In t 21h , Fu n ction 39h . Th is fu n ction p erform s all th e op eration s n ecessary to create th e su bd irectory, in clu d in g u p d atin g th e ap p rop riate d irectory an d FAT sectors. Th e on ly in form ation th is fu n ction n eed s is th e n am e of th e su bd irectory to create. DOS In t 21h wou ld d o m u ch m ore work by u sin g on e of th e lower-level access m eth od s to create a su bd irectory. Most ap p lication s access th e d isk th rou gh th is level of in terface. Int errupt 25h and 26h. Th e DOS In t 25h an d In t 26h rou tin es p rovid e m u ch lowerlevel access to th e d isk th an th e In t 21h rou tin es. In t 25h read s on ly sp ecified sectors from a d isk, an d In t 26h on ly writes sp ecified sectors to a d isk. If you were to write a p rogram th at u sed th ese fu n ction s to create a su bd irectory on a d isk, th e am ou n t of work wou ld be m u ch greater th an th at req u ired by th e In t 21h m eth od . For exam p le, you r p rogram wou ld h ave to p erform all of th ese tasks: ■ Calcu late exactly wh ich d irectory an d FAT sectors n eed to be u p d ated . ■ Use In t 25h to read th ese sectors. ■ Mod ify th e sectors ap p rop riately to ad d th e n ew su bd irectory in form ation . ■ Use In t 26h to write th e sectors back to th e d isk. Th e n u m ber of step s is even greater wh en you factor in th e d ifficu lty in d eterm in in g exactly wh at sectors h ave to be m od ified . Accord in g to In t 25/ 26h , th e en tire DOSad d ressable area of th e d isk con sists of sectors n u m bered seq u en tially from 0. A p rogram d esign ed to access th e d isk u sin g In t 25h an d In t 26h m u st kn ow th e correct d isk location s by sector n u m ber. A p rogram d esign ed th is way m igh t h ave to be m od ified to h an d le d isks with d ifferen t n u m bers of sectors or d ifferen t d irectory an d FAT sizes an d location s. Becau se of all th e overh ead req u ired to get th e job d on e, m ost p rogram m ers d o n ot ch oose to access th e d isk in th is m an n er an d in stead u se th e h igh er-level In t 21h — wh ich d oes all th e work au tom atically. Typ ically, on ly d isk- an d sector-ed itin g p rogram s th at access d isk d rives at th e In t 25h an d In t 26h level. Program s th at work at th is level of access can ed it on ly areas of a d isk th at h ave been d efin ed to DOS as a logical volu m e (d rive letter). For exam p le, th e DOS DEBUG p rogram can read sectors from an d write sectors to d isks with th is level of access. Int errupt 13h. Th e n ext lower level of com m u n ication s with d rives, th e ROM BIOS In t 13h rou tin es, u su ally are fou n d in ROM ch ip s on th e m oth erboard or on an ad ap ter card in an exp an sion slot. However, an In t 13h h an d ler also can be im p lem en ted by u sin g a d evice d river load ed at boot tim e. Becau se DOS req u ires In t 13h access to boot from a d rive (an d a d evice d river can n ot be load ed u n til after boot-u p ), on ly d rives with ROM BIOS-based In t 13h su p p ort can be bootable. In t 13h rou tin es com m u n icate d irectly with th e con troller u sin g th e I/ O p orts on th e con troller.

Disk Operating System (DOS)

Table 18.1 lists th e d ifferen t fu n ction s available at th e In terru p t 13h BIOS in terface. Som e fu n ction s are available to flop p y d rives or h ard d rives on ly, wh ereas oth ers are available to both typ es of d rives. Table 18.1 Funct ion

Int 13h BIOS Disk Funct ions Floppy Disk

Hard Disk

00h

X

X

Reset disk system

01h

X

X

Get status of last operation

02h

X

X

Read sectors

03h

X

X

Write sectors

04h

X

X

Verify sectors

05h

X

X

Format track

06h

X

Format bad track

07h

X

Format drive

08h

X

Descript ion

X

Read drive parameters

09h

X

Initialize drive characteristics

0Ah

X

Read long

0Bh

X

Write long

0Ch

X

Seek

0Dh

X

Alternate hard disk reset

0Eh

X

Read sector buffer

0Fh

X

Write sector buffer

10h

X

Test for drive ready

11h

X

Recalibrate drive

12h

X

Controller RAM diagnostic

13h

X

Controller drive diagnostic

X

Controller internal diagnostic

X

Get disk type

14h 15h

X

16h

X

Get floppy disk change status

17h

X

Set floppy disk type for format

18h

X

Set media type for format

19h

X

Park hard disk heads

1Ah

X

ESDI—Low-level format

1Bh

X

ESDI—Get manufacturing header

1Ch

X

ESDI—Get configuration

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Table 18.2 sh ows th e error cod es th at m ay be retu rn ed by th e BIOS INT 13h rou tin es. In som e cases, you m ay see th ese cod es wh en ru n n in g a low-level form at p rogram , d isk ed itor, or oth er p rogram th at can d irectly access a d isk d rive th rou gh th e BIOS. Table 18.2

BIOS INT 13h Error Codes

Code

Descript ion

00h

No error

01h

Bad command

02h

Address mark not found

03h

Write protect

04h

Request sector not found

05h

Reset failed

06h

Media change error

07h

Initialization failed

09h

Cross 64K DMA boundary

0Ah

Bad sector flag detected

0Bh

Bad track flag detected

10h

Bad ECC on disk read

11h

ECC corrected data error

20h

Controller has failed

40h

Seek operation failed

80h

Drive failed to respond

AAh

Drive not ready

BBh

Undefined error

CCh

Write fault

0Eh

Register error

FFh

Sense operation failed

Few h igh -p owered d isk u tility p rogram s, oth er th an som e basic d isk form attin g ap p lication s, can talk to th e d isk at th e In t 13h level. Th e DOS FDISK p rogram com m u n icates at th e In t 13h level, as d oes th e Norton Utilities’ DISKEDIT p rogram wh en it is in its absolu te sector m od e; th ese are som e of th e few d isk-rep air u tilities th at can d o so. Th ese p rogram s are im p ortan t becau se you can u se th em for th e worst d ata recovery situ ation s, in wh ich th e p artition tables h ave been corru p ted . Becau se th e p artition tables, an d an y n on -DOS p artition s, exist ou tsid e th e area of a d isk th at is d efin ed by DOS, on ly p rogram s th at work at th e In t 13h level can access th em . Most u tility p rogram s for d ata recovery work on ly at th e DOS In t 25/ 26h level, wh ich m akes th em u seless for accessin g areas of a d isk ou tsid e of DOS’ d om ain . Disk Cont roller I/ O Port Com m ands. At th e lowest in terface level, p rogram s com m u n icate d irectly with th e d isk con troller in th e con troller’s own sp ecific n ative lan gu age. To d o th is, a p rogram m u st sen d con troller com m an d s th rou gh th e I/ O p orts to wh ich th e con troller resp on d s.

Windows 3.1

√√ See “ IDE Origins,” p. 612

Figu re 18.2 sh ows th at m ost ap p lication p rogram s work th rou gh th e In t 21h in terface. Th is in terface p asses com m an d s to th e ROM BIOS as In t 13h com m an d s; th e ROM BIOS th en con verts th ese com m an d s in to d irect con troller com m an d s. Th e con troller execu tes th e com m an d s an d retu rn s th e resu lts th rou gh th e layers u n til th e d esired in form ation reach es th e ap p lication . Th is p rocess en ables d evelop ers to write ap p lication s with ou t worryin g abou t su ch low-level system d etails, leavin g th em in stead u p to DOS an d th e ROM BIOS. Th is also en ables ap p lication s to ru n on wid ely d ifferen t typ es of h ard ware, as lon g as th e correct ROM BIOS an d DOS su p p ort is in p lace.

Application Program

DOS INT 21h

DOS INT 25/26h ROM BIOS INT 13h Disk Controller I/O Ports

Floppy XT ST-412 AT ST-412 3F0-3F7 320-323 1F0-1F7 Floppy Drive

PS/2 ST-412 PS/2 ESDI PS/2 SCSI 320-324 3510-3517 3540-3457

Hard Disk Drive

FIG. 18.2 Relation sh ip s between variou s in terface levels. An y software can byp ass an y level of in terface an d com m u n icate with th e level below it, bu t d oin g so req u ires m u ch m ore work. Th e lowest level of in terface available is d irect com m u n ication with th e con troller u sin g I/ O p ort com m an d s. As Figu re 18.2 sh ows, each typ e of con troller h as d ifferen t I/ O p ort location s. W ith d ifferen t con trollers th ere are also d ifferen ces am on g th e com m an d s p resen ted at th e p orts. On ly th e con troller can talk d irectly to th e d isk d rive. If n ot for th e ROM BIOS In t 13h in terface, a u n iq u e DOS wou ld h ave to be written for each available typ e of h ard an d flop p y d isk d rive. In stead , DOS com m u n icates with th e ROM BIOS u sin g stan d ard In t 13h fu n ction calls tran slated by th e In t 13h in terface in to com m an d s for th e sp ecific h ard ware. Becau se of th e stan d ard ROM BIOS in terface, DOS is relatively in d ep en d en t from th e d isk h ard ware an d can su p p ort m an y d ifferen t typ es of d rives an d con trollers.

W indow s 3.1 Th e 16-bit W in d ows p latform s—W in d ows 3.1, W in d ows 3.11, an d W in d ows for W orkgrou p s—can n ot strictly be called op eratin g system s. Th ey are in stead grap h ical

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en viron m en ts th at op erate on top of DOS, u sin g m u ch of th e sam e d isk access tech n ology d escribed earlier in th is ch ap ter. W in d ows, h owever, takes ad van tage of m icrop rocessor cap abilities first in trod u ced in th e In tel 80386 ch ip in ways th at DOS can n ot. √√ See “ Processor M odes,” p. 43

W in d ows also exp an d s u p on som e of th e basic con cep ts in trod u ced in DOS to m ake th e ap p lication p rogram m er’s job easier. You read earlier h ow DOS, in com bin ation with th e system ROM BIOS, p rovid es an in terface to th e PC d isk storage d evices. Th is in terface en ables p rogram m ers to u se gen eral fu n ction calls for d isk access th at can be ap p lied to an y typ e of h ard ware by th e op eratin g system . However, wh en you in stall a DOS ap p lication , you often h ave to select d rivers for com p on en ts like you r vid eo d isp lay ad ap ter, au d io ad ap ter, an d p rin ter, becau se DOS d oes n ot p rovid e an yth in g bu t th e m ost ru d im en tary access to th ese d evices. W in d ows, on th e oth er h an d , d oes su p p ort th e u n iq u e cap abilities of you r system h ard ware. W h en you in stall W in d ows, you select d rivers for you r sp ecific vid eo, au d io, an d p rin ter h ard ware th at su p p ort all th e cap abilities of th ese d evices. As a resu lt, W in d ows ap p lication s d o n ot n eed th eir own d rivers for th ese d evices, becau se th e en viron m en t p rovid es a stan d ard set of fu n ction calls th at p rovid es a u n iversal in terface to wh atever h ard ware you h ave in stalled in th e system . 16-bit W indow s Versions Th e en viron m en t th at is com m on ly referred to as 16-bit W in d ows or W in d ows 3.1 can actu ally be an y on e of th ree p rod u cts. Th e d ifferen ces between th e version s are rath er sligh t, an d th e th ree are largely in d istin gu ish able in term s of th e u ser in terface. In gen eral, wh en th is ch ap ter refers to W in d ows 3.1, an y on e of th e th ree p rod u cts can be in ferred . W in d ows 3.1 was released in 1992, an d is th e stan d ard grap h ical 16-bit p latform for In tel-based system s. W in d ows 3.11 was released in 1994, an d con sisted of u p d ates to th e followin g key W in d ows files: ■ COMMDLG.DLL ■ GDI.EXE ■ KRNL386.EXE ■ PSCRIPT.DRV ■ SHELL.DLL ■ UNIDRV.DLL ■ USER.EXE

Windows 3.1

Th e W in d ows 3.11 u p grad e d id n ot resu lt in sign ifican t im p rovem en ts in system p erform an ce, an d was th erefore ign ored by m an y u sers an d ad m in istrators resp on sible for th e m ain ten an ce of W in d ows system s. Both W in d ows 3.1 an d 3.11 con tain n o n etworkin g su p p ort wh atsoever. At th e tim e th ey were released , NetW are was th e d om in an t n etworkin g p latform in th e bu sin ess world , an d su p p lied th e clien t software n eed ed to con n ect a DOS or W in d ows system to NetW are servers. At th e sam e tim e, h owever, Microsoft began to p rom ote th eir own n etworkin g en viron m en t, cu lm in atin g in th e in itial release of W in d ows NT in 1993. W in d ows for W orkgrou p s is an en viron m en t alm ost id en tical to W in d ows 3.1, excep t th at it in clu d es a W in d ows n etwork clien t th at en ables th e system to con n ect eith er to W in d ows NT servers or to oth er W in d ows for W orkgrou p system s on a p eer-to-p eer basis. W in d ows for W orkgrou p s also su p p orts extern al clien ts like th ose for NetW are, m akin g it p ossible to ru n a h eterogen eou s n etwork con tain in g both Microsoft an d Novell n etwork resou rces. At th e tim e of its in itial release, W in d ows for W orkgrou p s an d oth er Microsoft n etworkin g p rod u cts relied on th e NetBEUI p rotocol for n etwork com m u n ication s. As tim e p assed , h owever, TCP/ IP grew to be th e in d u stry stan d ard p rotocol su ite, an d Microsoft released a TCP/ IP clien t ad d -in for W in d ows for W orkgrou p s called TCP/ IP-32. Th ere are still a great m an y PCs tod ay th at u se th is com bin ation of p rod u cts for bu sin ess n etworkin g. Loading W indow s 3.1 As m en tion ed earlier, W in d ows 3.1 is n ot an op eratin g system in itself. You m u st always boot th e PC to a stan d ard DOS p rom p t before load in g th e W in d ows en viron m en t. Th e system boot p rocess, th erefore, is id en tical to th at ou tlin ed earlier in th is ch ap ter. However, as W in d ows load s, it ch an ges th e op eratin g m od e of th e system p rocessor an d p rovid es an ad d ition al in terface layer between th e system h ard ware an d you r ap p lication s. W h en you load W in d ows 3.1 by typ in g W IN at th e DOS p rom p t, th e system execu tes th e W IN.COM p rogram th at exam in es th e cap abilities of th e h ard ware in th e system an d load s W in d ows in th e ap p rop riate m od e to su p p ort th at h ard ware. At th e tim e W in d ows 3.1 was first released , th e PC world was on th e cu sp between th e eras of th e 80286 p rocessor an d th e 80386. If you h ad a 286-based system , W in d ows load ed in stan d ard m od e; 386-based an d h igh er system s load ed in 386 en h an ced m od e. Tod ay, of cou rse, th e 286 is all bu t extin ct an d n early all system s ru n W in d ows in 386 en h an ced m od e. Both W in d ows m od es req u ire access to XMS (exten d ed m em ory sp ecification ) m em ory, as p rovid ed by an exten d ed m em ory m an ager like HIMEM.SYS, th at is load ed by th e CONFIG.SYS file d u rin g th e system boot seq u en ce. To access XMS, W IN.COM sh ifts th e p rocessor from real m od e to p rotected m od e, som eth in g th at DOS can n ot d o. In protected m ode, a p rogram can be allotted a sp ecific area of m em ory th at is p rotected from in terferen ce by oth er p rogram s.

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Not e Note that real mode and protected mode are attributes of the system processor and should be distinguished from the terms standard mode and 386 enhanced mode, which are Windows software states.

W h en W IN.COM d etects a 286 p rocessor or less, it load s W in d ows in stan d ard m od e by execu tin g a file called DOSX.EXE (th e MS-DOS Exten d ed for W in d ows). In standard m ode, a W in d ows system is cap able of accessin g exten d ed m em ory for th e p u rp ose of task swap p in g. Task swap p in g is wh en th e system is ru n n in g two or m ore ap p lication s, bu t on ly th e active win d ow actu ally h as access to th e system p rocessor. Th e system execu tes two files, W SW AP.EXE an d DSW AP.EXE, to su p p ort th e task swap p in g of W in d ows ap p lication s an d DOS ap p lication s, resp ectively. W h en W in d ows load s in 386 enhanced m ode, W IN.COM execu tes a file called W IN386.EXE th at in tu rn load s th e d rivers sp ecified in th e [386en h ] section of th e SYSTEM.INI file. 386 en h an ced m od e m akes it p ossible for W in d ows to u se virtual m em ory, th at is, d isk sp ace on a local h ard d rive th at em u lates RAM to p rovid e a greater m em ory ad d ress sp ace in wh ich to ru n ap p lication s. W ith th e aid of th is virtu al m em ory, a W in d ows system in 386 en h an ced m od e can m ultitask, th at is, ru n m u ltip le p rogram s at th e sam e tim e with each p rogram receivin g regu lar access to th e p rocessor.

Not e Although true multitasking requires a separate processor for each task, the term has come to be used to refer to the sharing of a single processor’s clock cycles, as in a typical Windows PC.

Disk access tim es are obviou sly far slower th an m em ory access tim es (th e two bein g m easu red in m illisecon d s, th ou san d th s of a secon d , versu s n an osecon d s, billion th s of a secon d ), so virtu al m em ory is n owh ere n ear as efficien t as actu al RAM. However, th e cap ability to swap d ata from active m em ory to virtu al m em ory at will gives th e system th e cap ability to ru n m ore cod e th an it wou ld with RAM alon e. Core W indow s Files After load in g th e files to su p p ort th e ap p rop riate m od e, W in d ows load s th e core com p on en ts th at p rovid e th e basic fu n ction s of th e en viron m en t. Th ese com p on en ts are as follows: ■ KRNL286.EX E or KRNL386.EX E. Th e kern el file (ap p rop riate to th e p rocessor in th e system ) is resp on sible for m an agin g system resou rces like m em ory an d p rocessor cycles, as well as load in g ap p lication s an d sch ed u lin g system even ts. ■ USER.EX E. User is resp on sible for th e m an ip u lation of th e win d ows, icon s, an d oth er elem en ts th at m ake u p th e W in d ows u ser in terface. W h en you u se th e m ou se or th e keyboard to op en , close, m ove, or resize a win d ow, USER.EXE p asses th e in p u t to th e ap p lication associated with th e win d ow.

Windows 3.1

■ GDI.EX E. GDI is th e grap h ical d evice in terface, resp on sible for th e gen eration of screen im ages an d oth er grap h ics op eration s. After th e core files execu te, W in d ows load s an array of d evice d rivers to su p p ort th e h ard ware in stalled in th e system . Th ese d rivers p rovid e th e in terface th at W in d ows ap p lication s u se to access th e system h ard ware. Un like DOS, few W in d ows ap p lication s access th e system h ard ware d irectly. Th e excep tion s, again like DOS, ten d to be d isk u tilities th at req u ire lower level access th an th e W in d ows d isk d rivers p rovid e. 32-bit Disk Access Un d er n orm al con d ition s, th e h ard ware in terface p rovid ed by th e W in d ows d evice d rivers op erates in ad d ition to th e oth er in terfaces p rovid ed by DOS an d th e system BIOS. W h en a W in d ows ap p lication n eed s access to th e vid eo d isp lay, for exam p le, it m akes a fu n ction call to th e W in d ows vid eo d river. However, for access to a h ard d isk d rive, th e sam e ap p lication wou ld typ ically u se a stan d ard In t 21h req u est, ju st like a DOS ap p lication . DOS th en gen erates an In t 13h req u est to th e system BIOS, wh ich th en com m u n icates with th e h ard d rive con troller. Th e p roblem with th is arran gem en t is th at alth ou gh W in d ows an d its ap p lication s ru n th e system p rocessor in p rotected m od e, DOS an d th e BIOS req u ire th at th e p rocessor ru n in real m od e (called virtual 8086 m od e in W in d ows). Th u s, d u rin g th e d isk access p roced u re, th e p rocessor th at is op eratin g in p rotected m od e to ru n th e ap p lication m u st switch to virtu al m od e to p rocess th e In t 21h req u est, th en revert back to p rotected m od e. W h en DOS fin ish es p rocessin g th e In t 21h req u est, it gen erates th e In t 13h req u est for th e BIOS, an d again th e p rocessor m u st switch to virtu al m od e an d back again to trap th at in terru p t. On ce th e req u est reach es th e d isk con troller, th e h ard d rive read s th e d esired in form ation from th e d isk an d th e wh ole p rocess begin s again in reverse to retu rn th e req u ested d isk d ata to th e ap p lication . All th is m od e switch in g by th e p rocessor slows d own th e d isk access rou tin e, as d oes th e relatively slow sp eed of m ost system BIOS im p lem en tation s. W in d ows 3.1 in clu d es a featu re called 32-bit d isk access (or fastdisk) th at sp eed s u p th e p rocess by elim in atin g th e calls to th e system BIOS an d som e of th e p rocessor m od e sh ifts. Fastd isk is essen tially a p rotected m od e d evice d river th at com m u n icates d irectly with th e h ard d isk d rive con troller, rep lacin g th e system BIOS. Ap p lication s op erate as th ey n orm ally d o, by gen eratin g DOS In t 21h req u ests, forcin g th e p rocessor to switch to virtu al m od e. However, wh en th e p rocessor switch es back to p rotected m od e to trap th e In t 13h req u est gen erated by DOS, it d oes n ot p ass th is req u est to th e system BIOS. In stead , th e fastd isk d river p rocesses th e In t 13h req u est an d com m u n icates d irectly with th e d isk con troller, all th e tim e in p rotected m od e. Becau se th e fastd isk d river com m u n icates d irectly with th e d isk con troller, it on ly su p p orts h ard ware th at con form s to th e W estern Digital 1003 con troller m od el, wh ich is u sed by all m an u factu rers of IDE d rives. You can n ot u se fastd isk with SCSI d rives. √√ See “ ATA Commands,” p. 617

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Man y system s sh ow a d istin ct im p rovem en t in th eir W in d ows d isk access tim es as a resu lt of u sin g fastd isk. Fastd isk also m akes it p ossible to ru n m ore n on -W in d ows p rogram s in th e sam e am ou n t of m em ory. Becau se DOS is n ot occu p ied by com m u n ication s with th e BIOS, it is m ore read ily available for u se by th e virtu al m ach in es.

Hardw are Problem s Versus Soft w are Problem s One of the most aggravating situations in computer repair is opening up a system and troubleshooting all the hardware, just to find that the cause of the problem is a software program, not the hardware. M any people have spent large sums of money on replacement hardware, all on the assumption that the hardware was causing problems, when software was actually the culprit. To eliminate these aggravating, sometimes embarrassing, and often expensive situations, you should be able to distinguish a hardware problem from a software problem. Fortunately, making this distinction can be relatively simple. Software problems often are caused by the device drivers and memory-resident programs loaded from the CONFIG.SYS and AUTOEXEC.BAT files on many systems. One of the first things to do when you begin having problems with your system is to boot the system from a DOS disk that has no CONFIG.SYS or AUTOEXEC.BAT configuration files on it. Then test for the problem. If it has disappeared, the cause was probably something in one or both of those files. To find the problem, begin restoring device drivers and memory-resident programs to CONFIG.SYS and AUTOEXEC.BAT one at a time (starting with CONFIG.SYS). For example, add one program back to CONFIG.SYS, reboot your system, and then determine if the problem has reappeared. When you discover the device driver or memory-resident program causing the problem, you might be able to solve the problem by editing CONFIG.SYS and AUTOEXEC.BAT to change the order in which device drivers and memory-resident programs are loaded. Or, you might have to upgrade or even eliminate the problem device driver or memory-resident program.

W indow s 9x W in d ows 9x is th e n ext step in th e evolu tion of th e op eratin g system s th at began with DOS. Alth ou gh it is a fu lly 32-bit op eratin g system an d im p roves on W in d ows 3.1 in m an y ways, W in d ows 9x is n ot th e rad ical in n ovation th at it was p u rp orted to be before its release. In fact, W in d ows 95 is actu ally a com bin ation of a n ew version of MS-DOS (called DOS 7.00, accord in g to th e VER com m an d ) an d a n ew W in d ows in terface (called th e Explorer). As su ch , W in d ows 9x can in d eed be called an op eratin g system , as it m arries DOS an d th e W in d ows en viron m en t in to a m ore coh esive en viron m en t th an th e DOS/ W in d ows 3.1 com bin ation . Bootin g a W in d ows 9x system au tom atically load s th e GUI, bu t ch an gin g on e ch aracter of th e MSDOS.SYS text file cau ses th e com p u ter to boot to a DOS p rom p t, after wh ich you m u st typ e W IN to load th e W in d ows in terface. Sou n d fam iliar? W indow s 9x and DOS Com pared Mu ch of W in d ows 9x is based on th e sam e con cep ts as DOS an d W in d ows 3.1, bu t d evelop ed to th e n ext logical stage. Th e sam e two system files, IO.SYS an d MSDOS.SYS, still exist in W in d ows 9x, excep t th at all of th e system file cod e is n ow located in IO.SYS.

Windows 9x

Th e MSDOS.SYS file is n ow an ASCII text file th at con tain s con figu ration settin gs for th e system ’s boot beh avior. Du rin g th e system startu p p rocess, th e in itial p roced u res are very like th ose of a DOS system , as ou tlin ed earlier in th is ch ap ter. In W in d ows 9x, h owever, IO.SYS au tom atically load s th e eq u ivalen ts of HIMEM.SYS, IFSHLP.SYS, an d SETVER.EXE in to m em ory. You can still u se CONFIG.SYS an d AUTOEXEC.BAT files to load real m od e d evice d rivers an d m em ory-resid en t p rogram s, bu t th e 32-bit d evice d rivers d esign ed sp ecifically for u se with W in d ows 9x, as well as m ost of its con figu ration settin gs, are load ed from en tries in th e W in d ows 9x Registry. Fin ally, th e W IN.COM file is execu ted an d W in d ows 9x is officially started . Th e Registry is a d atabase of referen ce in form ation , con figu ration settin gs, an d ap p lication p aram eters th at is con tin u ou sly available to all W in d ows 9x m od u les. It rep laces n ot on ly th e fu n ction ality of th e CONFIG.SYS an d AUTOEXEC.BAT files, bu t th e W in d ows 3.1 INI files as well.

Not e Be aware that when upgrading a Windows 3.1 computer to Windows 9x, many of the application and operating system settings located in configuration files like SYSTEM .INI and WIN.INI are copied to the Windows 9x Registry. Once this has occurred, changing those settings in these INI files has no effect on the system, because the actual operative setting is located in the Registry.

Th e Registry takes th e form of two d isk files called SYSTEM.DAT an d USER.DAT. SYSTEM.DAT con tain s m ach in e-sp ecific settin gs, wh ile USER.DAT con tain s th e settin gs sp ecific to th e u ser wh o logs in to th e system . By m ain tain in g m u ltip le USER.DAT files, d ifferen t p eop le can sh are th e sam e com p u ter, with each u ser m ain tain in g h is or h er own system con figu ration an d d esktop p referen ces. Registry files can be im p orted , exp orted , m od ified , backed u p , an d restored to m ain tain , m od ify, an d p rotect th e settin gs for a p articu lar u ser or m ach in e. As far as d isk storage is con cern ed , W in d ows 9x by d efau lt still u ses th e sam e FAT file system th at DOS d oes, m ain tain in g fam iliar stru ctu res su ch as th e Master Boot Record (MBR), DOS Boot Record (DBR), FATs, an d d irectories. Th e p rim ary en h an cem en t to th e file system is th e cap ability to u se file an d d irectory n am es th at are u p to 255 ch aracters in len gth , wh ile retain in g backward com p atibility with existin g FAT file system s an d u tilities. W in d ows 9x d oes th is by m ain tain in g two n am es for every file an d d irectory—a lon g n am e an d a tru n cated n am e th at fits th e stan d ard DOS 8.3 form at. Th is way, you can op en a W in d ows 9x file with an y DOS or W in d ows 3.1 ap p lication , alth ou gh savin g th e file again will strip away th e lon g file n am e. If, for exam p le, you ran an old er version of a d isk rep air u tility like Norton Disk Doctor on a W in d ows 9x FAT volu m e, you cou ld effectively lose th e lon g n am es of all th e files an d d irectories on you r system .

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Versions Sin ce th e in itial release of W in d ows 95, q u ite a few p atch es an d featu re u p d ates h ave been released by Microsoft, as well as two m ajor releases. Th e W in d ows 95 OEM Service Release 2 (OSR2) is cu rren tly available on ly with th e p u rch ase of a n ew com p u ter or h ard d rive from an au th orized Microsoft OEM (origin al eq u ip m en t m an u factu rer). Th is is largely d u e to th e fact th at th e m ost im p ortan t featu re in th e u p grad e is a n ew file system called FAT32 th at is d esign ed to su p p ort with greater efficien cy th e larger h ard d isk d rives n ow bein g fou n d in PCs. Th e OSR2 version of W in d ows 95 was released in th is way n ot to th wart an d irritate m illion s of u sers (wh ich it h as), bu t to p reven t a backlash of in com p atibilities th at m ay occu r wh en th e op eratin g system is in stalled on old er h ard ware. Most of th e oth er p atch es an d im p rovem en ts to th e op eratin g system th at are in clu d ed in th e OSR2 release can be ap p lied to W in d ows 95 in stallation s an d are freely available from Microsoft’s W eb site. Th e W in d ows 98 release ad d s FAT32 as p art of a retail p rod u ct for th e first tim e, an d m akes it p ossible to con vert existin g FAT16 p artition s to FAT32. Th ere are also n u m erou s oth er n ew featu res an d accessories in W in d ows 98, bu t very little else abou t th e op eratin g system ’s relation sh ip to th e PC h ard ware is ch an ged from th e OSR2 p rod u ct. W indow s 9x Archit ect ure Mu ch of th e W in d ows 9x system arch itectu re is sim ilar to th at of W in d ows 3.1, bu t rewritten in 32-bit cod e. Th e core elem en ts of th e op eratin g system are still th e Kern el, th e User, an d th e GDI, bu t all th ree n ow exist in both 32-bit an d 16-bit version s. Th e 32-bit version s gen erally p rovid e better p erform an ce an d su p p ort for 32-bit ap p lication s, wh ile th e 16-bit version s are retain ed for backward com p atibility. Virt ual M achine M anager. W in d ows 9x ru n s ap p lication s in sep arate, isolated en viron m en ts called virtual m achines. Created by th e Virtu al Mach in e Man ager (wh ich rep laces th e W in d ows 3.1 W IN386.EXE m od u le), each virtu al m ach in e con tain s all th e services n eed ed for an ap p lication to ru n . By isolatin g each ap p lication in its own en viron m en t, W in d ows 9x is able to p reven t th e rest of th e system from bein g affected by a sin gle m alfu n ction in g ap p lication . Plug and Play. Perh ap s th e largest im p rovem en t in W in d ows 9x from a h ard ware stan d p oin t is th e in trod u ction of su p p ort for Plu g an d Play (Pn P). Plu g an d Play is a stan d ard th at en ables th e op eratin g system to au tom atically n egotiate for th e system resou rces n eed ed by a p articu lar d evice an d con figu re th e h ard ware to u se th em . Most of th e PC p erip h erals m an u factu red tod ay su p p ort Pn P, m akin g th e in stallation of n ew h ard ware as sim p le as in sertin g an exp an sion card in to a slot or p lu ggin g it in to a p ort. To im p lem en t th is fu n ction ality, W in d ows 9x u ses a m od u le called th e Con figu ration Man ager. Th e Con figu ration Man ager con sists of m u ltip le bus enum erators th at are resp on sible for scan n in g th e system ’s variou s exp an sion bu ses for th e d evices con n ected to th em . Th e en u m erators th en bu ild a h ard ware tree con tain in g all th e bu ses an d d evices in th e system .

Windows 9x

On ce th is in ven tory of th e system h ard ware is com p leted , th e Con figu ration Man ager load s a d river for each d evice in th e h ard ware tree. Th e W in d ows 9x d rivers are all 32-bit, p rotected m od e m od u les, p erm ittin g th em to be load ed in to system m em ory m u ch m ore easily th an th eir real m od e cou n terp arts from W in d ows 3.1, wh ich req u ire con ven tion al m em ory (m em ory below 640K) to load . W ith th e d rivers load ed , th e Con figu ration Man ager th en u ses resource arbitrators to n egotiate th e h ard ware resou rces th at are to be allocated to each d evice. Th ese arbitrators recon cile an y resou rce con flicts th at m ay exist between d evices an d d eterm in e th e best com bin ation of op eration al settin gs for th e h ard ware. FAT32 Th e p rim ary ad van tage of th e FAT32 file system is its cap ability to su p p ort larger h ard d rives. Su rely n o on e in volved in th e d evelop m en t of th e origin al FAT file system cou ld ever h ave d ream ed th at a m od est h om e com p u ter wou ld com e with a 2G h ard d rive, bu t th at is n ow th e m in im u m . Th e largest d isk p artition su p p orted by th e FAT file system is also 2G. Th e oth er p roblem with FAT is th at th e larger clu ster sizes u sed with h igh cap acity h ard d rives are extrem ely wastefu l in term s of th e d isk sp ace lost to th e slack cau sed by u n u sed bits in allocated clu sters. FAT32 ad d resses both of th ese p roblem s, by su p p ortin g d rives u p to 2T (2 terabytes, or 2,000G) in size, an d with m u ch sm aller clu sters. A 2G FAT16 p artition u ses 32K clu sters, wh ile th e clu sters on th e sam e size FAT32 p artition are on ly 4K. Th is resu lts in a file system th at is m ore efficien t, by a factor of 10 to 15 p ercen t wh en it com es to storin g th e m axim u m p ossible am ou n t of d ata on a h ard d rive.

Not e Although 2T may seem to be an outrageously large amount of data, consider that a typical PC hard drive has gone from 10M to 2G in less than 15 years, an increase of 20,000 percent. At this rate of growth, your home computer in the year 2010 should be equipped with a 400T hard drive (probably running the FAT256 file system).

FAT32 also overcom es som e of th e oth er obviou s lim itation s of th e FAT system . For exam p le, FAT32 still h as two file allocation tables, bu t it can n ow m ake u se of eith er on e, switch in g to th e backu p if th e first table is corru p ted . Also, th e root d irectory of a d rive is n o lon ger restricted to a sp ecific size. It is com p osed of clu ster ch ain s like an y oth er d irectory, an d can be located an ywh ere on th e d isk. FAT32 volu m es are im p lem en ted by th e FDISK p rogram in clu d ed with th e OSR2 W in d ows 95 an d W in d ows 98 releases. W h en you attem p t to create a p artition larger th an 512M, th e p rogram asks if you wan t to en able large d isk su p p ort. An swerin g yes cau ses all p artition s larger th an 512M to u se th e FAT32 file system . FAT32, like W in d ows 9x, is d esign ed to p rovid e th e greatest p ossible backward com p atibility, alon g with its ad van ced featu res. It will con tin u e to su p p ort real m od e DOS p rogram s an d tod ay’s p rotected m od e ap p lication s. Th is m ean s th at you will be able to boot

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from an y DOS d isk an d still access FAT32 d rives. However, ap p lication s d esign ed for u se on FAT16 d rives th at ad d ress th e h ard ware d irectly, su ch as d isk rep air p rogram s, will n ot fu n ction on (an d m ay d am age) FAT32 volu m es.

W indow s NT W h ereas DOS, W in d ows 3.1, an d W in d ows 9x can be seen as su ccessive step s in th e con tin u in g evolu tion of an op eratin g system , W in d ows NT is a wh olly n ew con cep t W in d ows NT is a 32-bit op eratin g system th at was d esign ed from th e grou n d u p to p oin t toward th e fu tu re of both n etwork an d d esktop com p u tin g. Th e p rim ary p roblem th at con sisten tly h old s back th e ad van cem en t of com p u tin g tech n ology is backward com p atibility. It is d ifficu lt to sell a p rod u ct th at forces u sers to ju n k th e in vestm en t th at th ey h ave alread y m ad e in software or h ard ware. W in d ows 9x is m u ch closer to DOS/ W in d ows 3.1 th an it is to W in d ows NT for th is very reason . Corp oration s h esitate to con vert to a n ew op eratin g system on a large scale if it forces th em to waste m illion s of d ollars sp en t on 16-bit software an d u ser train in g. W in d ows NT is ju st su ch a p rod u ct, an d its accep tan ce in th e m arketp lace sin ce its origin al release in 1993 h as been grad u al bu t stead y. W in d ows NT 4.0 is n ow a viable com p etitor to W in d ows 9x in th e d esktop m arketp lace, largely becau se of th e W in d ows 9x m arketin g p rogram th at led to a m assive 32-bit software d evelop m en t effort. Most 32-bit W in d ows ap p lication s can ru n on eith er W in d ows 9x or W in d ows NT, an d th e backward com p atibility issu e is fad in g stead ily as 16-bit ap p lication s are p h ased ou t. W in d ows NT is a com p letely d ifferen t op eratin g system from DOS. Alth ou gh you can op en a DOS session win d ow from with in th e GUI, it is n ot a sh ell in th e trad ition al sen se. It is rath er a DOS em u lation th at is d esign ed to p rovid e a fam iliar com m an d lin e in terface to u sers wh o wan t it. Man y DOS p rogram s will n ot ru n in a W in d ows NT DOS session , n or is it p ossible to boot th e W in d ows NT op eratin g system to a ch aracter-based state th at p reced es th e load in g of th e grap h ical in terface, as with W in d ows 9x. Like W in d ows 9x, W in d ows NT u ses a Registry to load d evice d rivers an d store its con figu ration settin gs. Th ere are n o CONFIG.SYS, AUTOEXEC.BAT, or INI files. W in d ows NT can u se th e FAT16 file system , wh ich en ables you to boot th e com p u ter u sin g a DOS d isk an d still access its d rives. Som e of W in d ows NT’s m ost ad van ced featu res, h owever, are p rovid ed by th e NT File System (NTFS). NTFS (like FAT32) allows you to create p artition s u p to 2T in size, bu t it also p rovid es th e file com p ression , secu rity, an d au d itin g featu res th at are im p ortan t to W in d ows NT com p u ters in n etwork en viron m en ts. Begin n in g in W in d ows NT 5.0, su p p ort will be p rovid ed for th e FAT32 file system as well. Du rin g th e W in d ows NT in stallation p rocess, th e in itial setu p is p erform ed on a FAT d rive, wh ich can be con verted to NTFS at th e en d of th e in stallation p rocess, if you so d esire. You can also con vert th e d rives later, u sin g a CONVERT.EXE u tility p rovid ed with th e op eratin g system . From th e tim e th at a p artition is con verted to NTFS, h owever, it is n ot accessible by an y oth er op eratin g system . If you u se a DOS d isk to boot a system with NTFS p artition s, you will h ave access to th e flop p y d rive on ly, ju st as if th ere were n o h ard d rives in stalled in th e com p u ter. To switch th e m ach in e back to W in d ows 9x,

Windows NT

W in d ows 3.1, or DOS, you m u st d elete th e NTFS p artition s (an d th eir d ata) an d create n ew FAT p artition s from scratch . Versions Th e first version of W in d ows NT was called 3.1, becau se it was released in 1993 wh en W in d ows 3.1 was th e cu rren t 16-bit W in d ows p rod u ct. Th e grap h ical in terface was id en tical to th at of W in d ows 3.1, even if th e u n d erlyin g in frastru ctu re was com p letely d ifferen t. Su bseq u en t version s (3.5 an d 3.51) d rew greater d istin ction s between th e Server an d W orkstation version s of th e op eratin g system by ad d in g th e cap ability to create grou p in gs of W in d ows NT m ach in es called d om ain s. Th ese version s also p rovid ed bu g fixes, im p lem en ted som e arch itectu ral ch an ges, su ch as m akin g TCP/ IP th e d efau lt n etworkin g p rotocol, an d ad d ed n ew services like DHCP an d W INS. W in d ows NT 4.0 was th e first release to m ake su bstan tial ch an ges to th e ap p earan ce of th e op eratin g system , by ad d in g th e sam e Exp lorer in terface u sed by W in d ows 9x. W indow s NT St art up W h en you start a W in d ows NT system , th e boot p rocess is id en tical to th at of a DOS system , u p u n til th e tim e wh en th e system read s th e volu m e boot sector from th e active p artition . In stead of th e IO.SYS an d MSDOS.SYS files, W in d ows NT u ses an OS load er p rogram called NTLDR th at begin s th e h ard ware d etection p rocess an d en ables you to select th e op eratin g system to load . If, for exam p le, you h ave in stalled W in d ows NT on a system alread y ru n n in g an oth er OS, you h ave th e op tion of bootin g eith er op eratin g system . Th e boot op tion s are stored in a file called BOOT.INI. On ce you elect to load th e W in d ows NT op eratin g system , a file called NTDETECT.COM load s an d d etects th e h ard ware in th e com p u ter. After th is, th e W in d ows NT Kern el (NTOSKRNL.EXE) an d th e h ard ware abstraction layer (HAL.DLL) are load ed in to m em ory. Th e kern el is resp on sible for in itializin g m ost of th e op eratin g system , in clu d in g th e d evice d rivers, th e W in d ows NT su bsystem s an d services, an d th e m em ory p agin g file. It isn ’t u n til you p ress th e Ctrl+Alt+Delete key com bin ation an d log on to th e system th at th e startu p p rocess is con sid ered to be com p lete. W indow s NT Com ponent s Th e W in d ows NT kernel is resp on sible for sch ed u lin g tasks an d m an agin g th read s. Th e th read is th e sm allest u n it of p rocessor activity W in d ows NT can h an d le. Becau se W in d ows NT is a m u ltith read ed op eratin g system , th e kern el is resp on sible for seein g to it th at th e th read s of th e variou s p rocesses ru n n in g on th e system at an y on e tim e receive th e ap p rop riate access to th e p rocessor, based on th eir p riorities. W in d ows NT was d esign ed to be a m od u lar op eratin g system an d to be p ortable to d ifferen t h ard ware (th at is, p rocessor) p latform s. To m ake th is p ossible, a m od u le called th e hardware abstraction layer (HAL) creates a virtu al in terface to th e system h ard ware. Th e op eratin g system kern el an d th e d evice d rivers th en u se th is in terface to com m u n icate with th e h ard ware, rath er th an accessin g it d irectly. Becau se th e in terface is

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m ach in e-in d ep en d en t, it is a relatively sim p le m atter to p ort th e kern el, d rivers, an d oth er com p on en ts to oth er p latform s, su ch as Digital’s Alp h a p rocessor. W in d ows NT h as two op eration al m od es: kern el m od e an d u ser m od e. Kern el m od e p rovid es access to all system resou rces an d p rocessor in stru ction s. Th e OS kern el an d th e HAL both ru n in kern el m od e, as d oes th e W in d ows NT Execu tive. Th e Execu tive con sists of th e followin g op eratin g system com p on en ts: ■ Object Manager. All W in d ows NT resou rces, in clu d in g files an d d irectories, th read s an d p rocesses, an d m em ory segm en ts an d section s, are rep resen ted by abstract form ation s kn own as objects. Th e Object Man ager p rovid es an h ierarch ical n am in g system for th ese objects, wh ich m akes it p ossible to track th eir creation an d u se. ■ I/O Manager. Th e I/ O Man ager is resp on sible for all of W in d ows NT’s in p u t an d ou tp u t fu n ction s an d m ain tain s com m u n ication s with th e variou s d evice d rivers for th e system h ard ware to m ake th is p ossible. ■ Security Reference Monitor. Th e Secu rity Referen ce Mon itor (SRM) works togeth er with th e u ser m od e secu rity su bsystem to con trol access to W in d ows NT objects. All req u ests for access to an object p ass th rou gh th e SRM, wh ich ch ecks its access con trol list for th e ap p rop riate righ ts. ■ Process Manager. Th e Process Man ager con trols th e creation an d d eletion of p rocess objects an d th e th read s th at m ake u p th e p rocesses. ■ V irtual Mem ory Manager. Th e Virtu al Mem ory Man ager is resp on sible for allocatin g a p rotected m em ory ad d ress sp ace to each p rocess ru n n in g on th e system . As with W in d ows 9x, W in d ows NT can u se d isk sp ace as virtu al m em ory, an d allocate a total am ou n t of m em ory th at is larger th an th e RAM in stalled in th e system . ■ Local Procedure Call. Th e Local Proced u re Call facility p rovid es com m u n ication s between clien t an d server p rocesses on th e sam e system , ju st as Rem ote Proced u re Calls are u sed for clien t/ server com m u n ication s between d ifferen t system s. User m od e is a less p riveled ged m od e th at keep s th e p rocesses ru n n in g in it isolated from p arts of th e OS th at cou ld be crash ed , User m od e in teracts with th e u ser an d th e u ser ap p lication s. Th is sp lit in m od es allows ap p lication s d esign ed for W in d ows as well as som e n ative OS/ 2 an d POSIX ap p lication s to ru n with ou t givin g th ese oth er ap p lication s d irect access to th e kern el.

Chapter 19

19

File Systems and Data Recovery

Hard d isks an d oth er m ed ia p rovid e th e basic tech n ology for storin g d ata. However, it is th e file system th at p rovid es th e h ierarch ical stru ctu re of volu m es an d d irectories in wh ich you store in d ivid u al files an d th e organ ization al m od el th at m akes it p ossible for th e system to locate d ata an ywh ere on th e d isk. File system s are u su ally in tegrated in to an op eratin g system (OS), alth ou gh som e OSs p rovid e su p p ort for several file system s from wh ich you can ch oose.

Th e m ost com m on ly u sed file system tod ay is based on a file allocation table, or FAT, th at keep s track of th e d ata stored in each clu ster on a d isk. Th is is th e file system origin ally u sed by DOS an d it is still su p p orted by virtu ally every oth er PC op eratin g system in u se tod ay. Th is ch ap ter exam in es th e d isk stru ctu res th at DOS u ses to im p lem en t th e FAT file system , an d th en d iscu sses th e ad d ition al cap abilities p rovid ed by n ewer file system s su ch as FAT32 an d W in d ows NT’s NTFS.

FAT Disk St ruct ures To m an age files on a d isk an d en able all ap p lication p rogram s to see a con sisten t in terface to th e file system n o m atter wh at typ e of storage h ard ware is bein g u sed , DOS creates several stru ctu res on th e d isk. Th ese stru ctu res are th e sam e for an y OS th at su p p orts th e FAT file system , in clu d in g W in d ows 9x an d W in d ows NT. Th e followin g list sh ows all th e stru ctu res an d areas th at DOS d efin es an d u ses to m an age a d isk, in rou gh ly th e sam e ord er th at th ey ap p ear: ■ Master an d exten d ed p artition boot sectors ■ Volu m e boot sector ■ Root d irectory ■ File allocation tables (FAT) ■ Clu sters (allocation u n its)

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■ Data area ■ Diagn ostic read -an d -write cylin d er A h ard d isk h as all th ese d isk-m an agem en t stru ctu res, an d a flop p y d isk h as all bu t th e m aster an d exten d ed p artition boot sectors an d th e d iagn ostic cylin d er. Th ese stru ctu res are created on h ard d isk d rives by th e FDISK p rogram in clu d ed with all version s of DOS an d W in d ows 9x. You can n ot u se FDISK on a flop p y d isk becau se flop p y d isks can n ot be p artition ed . Figu re 19.1 is a sim p le d iagram sh owin g th e relative location s of th ese DOS d isk-m an agem en t stru ctu res on a 2111M W estern Digital h ard d isk.

Not e Some removable cartridge drives, such as the Iomega Zip drive, function like high-capacity floppy disk drives. They lack a master boot sector and diagnostic cylinder and cannot be partitioned like hard disk drives. Other higher-capacity drives, such as the Iomega Jaz, can be partitioned like a hard disk drive.

Western Digital Caviar AC 12100 2111M Disk - 4092 Cylinders, 16 Heads, 63 Sectors/Track: Location

Disk Area Name

Cyl 0, Hd 0

Master partition boot sector Hidden (wasted) sectors

Cyl 0, Hd 1

DOS Volume Boot Sector File Allocation Table #1 File Allocation Table #2 Root Directory Data Area (Clusters)

2111 Meg C:

Part. Table Ranges

#1

Cylinder 4090, Head 15 Cylinder 4091

Diagnostic Cylinder

FIG. 19.1 DOS d isk m an agem en t stru ctu res on a W estern Digital Caviar AC12100.

FAT Disk Structures

Each d isk area h as a p u rp ose an d fu n ction . If on e of th ese sp ecial areas is d am aged , seriou s con seq u en ces can resu lt. Dam age to on e of th ese sen sitive stru ctu res u su ally cau ses a d om in o effect, lim itin g access to oth er areas of th e d isk or cau sin g fu rth er p roblem s in u sin g th e d isk. For exam p le, DOS can n ot read an d write files if th e FAT is d am aged or corru p ted . Th erefore, you sh ou ld u n d erstan d th ese d ata stru ctu res well en ou gh to be able to rep air th em wh en n ecessary. Rebu ild in g th ese sp ecial tables an d areas of th e d isk is essen tial to th e art of d ata recovery. M ast er Part it ion Boot Sect or To u se a h ard d isk with d ifferen t op eratin g system s, you can logically d ivid e th e d isk by creatin g u p to fou r p artition s. You can , for exam p le, u se FDISK to create on e or m ore FAT p artition s for u se with DOS or W in d ows 9x, an d leave th e rest of th e d isk storage area for u se by an oth er OS’s file system . Each of th e FAT p artition s will ap p ear to th e OS as a sep arate d rive letter. In form ation abou t each of th e p artition s on th e d isk is stored in a p artition (or volu m e) boot sector at th e begin n in g of each p artition . Th ere is also a m ain table listin g th e p artition s em bed d ed in th e m aster p artition boot sector. Th e m aster partition boot sector (or m aster boot record ) is always located in th e first sector of th e en tire d isk (cylin d er 0, h ead 0, sector 1) an d con sists of th e followin g stru ctu res: ■ Master partition table. Con tain s a list of th e p artition s on th e d isk an d th e location s of th eir volu m e boot sectors. Th is table is very sm all an d can con tain on ly fou r en tries at th e m ost. Th erefore, to accom m od ate m ore p artition s, op eratin g system s su ch as DOS can d ivid e a sin gle exten d ed p artition in to m u ltip le logical volu m es. ■ Master boot code. A sm all p rogram th at is execu ted by th e system BIOS, th e m ain fu n ction of wh ich is to p ass con trol of th e system to th e p artition th at h as been d esign ated as active (or bootable).

Prim ary and Ext ended DOS Part it ions DOS is designed to support up to 24 partitions on a single hard disk drive (represented by the drive letters C: through Z:), but the partition table in the master partition boot sector can have a maximum of only four entries. To resolve this discrepancy, the FDISK program enables you to create two types of FAT partitions: a primary DOS partition and an extended DOS partition. The first FAT partition that you create on a disk should be the primary, which is listed in the master partition table and appears to the operating system as a single drive letter. An extended DOS partition is listed in the master partition table like the primary, but it differs in that you can use its disk space to create multiple logical partitions, or volumes. You can create only one extended DOS partition on a single drive, meaning that there will never be more than two entries in the master partition table devoted to FAT drives. The logical volumes that you create in the extended DOS partition appear as separate drive letters to the operating system, but they are not listed in the master partition table. Logical volumes also cannot be active partitions, and are therefore not bootable. You can create up to 23 volumes out of a single extended DOS partition (assuming that you have already created a primary DOS partition, which brings the total to 24). (continues)

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Chapter 19—File Systems and Data Recovery (continued) Each of the logical partitions (or volumes) in an extended DOS partition includes an extended partition table that contains information about that volume. The master partition table’s entry for the extended DOS partition contains a reference to the first volume’s extended partition table. This table in turn contains a reference detailing the location of the second volume’s table. This chain of references continues, linking all the volumes in the extended DOS partition to the master partition table. Of course, few people have any reason to create 24 FAT partitions on a single disk drive, but the extended DOS partition makes it possible to exceed the four-entry limitation of the master partition table.

Becau se th e m aster boot sector con tain s th e first p rogram th at th e system execu tes wh en you boot a PC, it is freq u en tly a target for creators of com p u ter viru ses. A viru s th at in fects or d estroys th e m aster boot sector can m ake it im p ossible for th e BIOS to fin d th e active p artition , th u s p reven tin g th e op eratin g system from load in g. Becau se th e m aster boot sector con tain s th e first p rogram execu ted by th e system , a viru s stored th ere load s before an y an ti-viru s cod e can d etect it. To rem ove a m aster boot sector viru s, you m u st first boot th e system from a clean , u n in fected flop p y d isk an d th en ru n an an ti-viru s p rogram . Each p artition on a d isk con tain s a volu m e boot sector as its first sector, wh ich is listed in th e m aster p artition table. W ith th e FDISK u tility, you can d esign ate a sin gle p artition as active (or bootable). Th e m aster p artition boot sector cau ses th e active p artition ’s volu m e boot sector to receive con trol wh en ever th e system is started or reset. You can also create ad d ition al d isk p artition s for Novell NetW are, W in d ows NT’s NTFS, OS/ 2’s HPFS, AIX (UNIX), XENIX, or oth er file system s, u sin g d isk u tilities p rovid ed with th e op eratin g system s th at su p p ort th em . Th ese p artition s are listed in th e m aster p artition table, even th ou gh th ey m ay u se d ifferen t stru ctu res with in th e p artition . However, you can n ot access th e d ata stored on th ese foreign op eratin g system p artition s with DOS. In som e cases, you can n ot access FAT p artition s u sin g oth er op eratin g system s eith er, alth ou gh OS/ 2 an d W in d ows NT d o su p p ort FAT in ad d ition to th eir own file system s: HPFS an d NTFS. You m u st create at least on e p artition on a h ard d isk for it to be accessible by an op eratin g system . Creatin g a p artition ad d s an en try to th e m aster p artition table. Table 19.1 sh ows th e form at of th e Master Boot Record (MBR) an d its p artition tables. Th e table lists th e field s in each of th e m aster p artition table’s fou r en tries, th e location on th e d isk wh ere each field begin s (th e offset), an d its len gth . Table 19.1

M ast er Boot Record ( Part it ion Table)

M ast er Part it ion Table Ent ry #1 Offset

Lengt h

1BEh 446

1 byte

Descript ion Boot Indicator Byte (80h = Active, else 00h)

1BFh 447

1 byte

Starting Head (or Side) of Partition

1C0h 448

16 bits

Starting Cylinder (10 bits) and Sector (6 bits)

FAT Disk Structures

Offset

Lengt h

Descript ion

1C2h 450

1 byte

System Indicator Byte (see Table 19.2)

1C3h 451

1 byte

Ending Head (or Side) of Partition

1C4h 452

16 bits

Ending Cylinder (10 bits) and Sector (6 bits)

1C6h 454

1 dword

Relative Sector Offset of Partition

1CAh 458

1 dword

Total Number of Sectors in Partition

Part it ion Table Ent ry #2 Offset

Lengt h

Descript ion

1CEh 462

1 byte

Boot Indicator Byte (80h = Active, else 00h)

1CFh 463

1 byte

Starting Head (or Side) of Partition

1D0h 464

16 bits

Starting Cylinder (10 bits) and Sector (6 bits)

1D2h 466

1 byte

System Indicator Byte (see Table 19.2)

1D3h 467

1 byte

Ending Head (or Side) of Partition

1D4h 468

16 bits

Ending Cylinder (10 bits) and Sector (6 bits)

1D6h 470

1 dword

Relative Sector Offset of Partition

1DAh 474

1 dword

Total Number of Sectors in Partition

Part it ion Table Ent ry #3 Offset

Lengt h

Descript ion

1DEh 478

1 byte

Boot Indicator Byte (80h = Active, else 00h)

1DFh 479

1 byte

Starting Head (or Side) of Partition

1E0h 480

16 bits

Starting Cylinder (10 bits) and Sector (6 bits)

1E2h 482

1 byte

System Indicator Byte (see Table 19.2)

1E3h 483

1 byte

Ending Head (or Side) of Partition

1E4h 484

16 bits

Ending Cylinder (10 bits) and Sector (6 bits)

1E6h 486

1 dword

Relative Sector Offset of Partition

1EAh 490

1 dword

Total Number of Sectors in Partition

Part it ion Table Ent ry #4 Offset

Lengt h

Descript ion

1EEh 494

1 byte

Boot Indicator Byte (80h = Active, else 00h)

1EFh 495

1 byte

Starting Head (or Side) of Partition

1F0h 496

16 bits

Starting Cylinder (10 bits) and Sector (6 bits)

1F2h 498

1 byte

System Indicator Byte (see Table 19.2)

1F3h 499

1 byte

Ending Head (or Side) of Partition

1F4h 500

16 bits

Ending Cylinder (10 bits) and Sector (6 bits)

1F6h 502

1 dword

Relative Sector Offset of Partition

1FAh 506

1 dword

Total Number of Sectors in Partition (continues)

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Chapter 19—File Systems and Data Recovery

Table 19.1

M ast er Boot Record ( Part it ion Table) Cont inued

Signat ure Byt es Offset

Lengt h

Descript ion

1FEh 510

2 bytes

Boot Sector Signature (55AAh)

A W ORD equals 2 bytes read in reverse order, and a DW ORD equals two W ORDs read in reverse order.

Each en try in th e Master Partition Table con tain s a System In d icator Byte th at id en tifies th e typ e of p artition referen ced by th at en try. Table 19.2 sh ows th e stan d ard valu es an d m ean in gs of th e System In d icator Byte. Table 19.2

Part it ion Table Syst em Indicat or Byt e Values

Value

Descript ion

00h

No allocated partition in this entry

01h

Primary DOS, 12-bit FAT (Partition < 16M )

04h

Primary DOS, 16-bit FAT (16M DEBUG -D FFFF:5 L 8 FFFF:0000 -Q

30 31 2F-32 32 2F 39 37

01/22/97

In th is exam p le, th e system q u eried sh ows a BIOS d ate of 01/22/97. XT Technical Specificat ions Tech n ical in form ation for th e XT system , d escribed in th is section , p rovid es in form ation abou t th e system arch itectu re, m em ory con figu ration s an d cap acities, stan d ard system featu res, d isk storage, exp an sion slots, keyboard sp ecification s, an d also p h ysical an d en viron m en tal sp ecification s. Figu re 20.6 sh ows th e layou t an d com p on en ts on th e XT m oth erboard . Clock chip trimmer

Keyboard I/O

8-bit ISA bus slots

J1

J2

J3

J4

J5

J6

J7

J8

J9

System-board power connections Intel 8087 math coprocessor INTEL 8088 processor ROM BASIC

ROM BIOS 8259 Interrupt controller

System Configuration DIP switches

8237 DMA controller

As much as 640K read/ write memory with parity checking

{

P3

Pin 1

Speaker output

FIG. 20.6 Th e XT m oth erboard .

An Introduction to the XT (5160)

Syst em Archit ect ure M icroprocessor

8088

Clock speed

4.77M Hz

Bus type

ISA (Industry Standard Architecture)

Bus width

8-bit

Interrupt levels

8 (6 usable)

Type

Edge-triggered

Shareable

No

DM A channels

4 (3 usable)

Bus masters supported

No

Upgradable processor complex

No

M em ory Standard on system board

256K or 640K

M aximum on system board

256K or 640K

M aximum total memory

640K

M emory speed (ns) and type

200ns dynamic RAM chips

System board memory-socket type

16-pin DIP

Number of memory-module sockets

36 (4 banks of 9)

M emory used on system board

36 64K×1-bit DRAM chips in 4 banks of 9, or 2 banks of 9 256K×1-bit and 2 banks of 9 64K×1-bit chips

M emory cache controller

No

Wait states: System board

1

Adapter

1

St andard Feat ures ROM size

40K or 64K

ROM shadowing

No

Optional math coprocessor

8087

Coprocessor speed

4.77M Hz

Standard graphics

None standard

RS232C serial ports

1 (some models)

UART chip used

NS8250B

M aximum speed (bits per second)

9,600bps

M aximum number of ports supported

2

Pointing device (mouse) ports

None standard

Parallel printer ports

1 (some models)

Bidirectional

No

M aximum number of ports supported

3

CM OS real-time clock (RTC)

No

CM OS RAM

None (continues)

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Chapter 20—IBM Personal Computer Family Hardware

(continued)

Disk St orage Internal disk and tape drive bays

2 full-height or 4 half-height

Number of 3 1/ 2-inch or 5 1/ 4-inch bays

0/ 2 or 0/ 4

Standard floppy drives

1 ×360K

Optional floppy drives: 5 1/ 4-inch 360K

Optional

5 1/ 4-inch 1.2M

No

3 1/ 2-inch 720K

Optional

3 1/ 2-inch 1.44M

No

3 1/ 2-inch 2.88M

No

Hard disk controller included

ST-506/ 412 (Xebec M odel 1210)

ST-506/ 412 hard disks available

10/ 20M

Drive form factor

5 1/ 4-inch

Drive interface

ST-506/ 412

Drive capacity

10M

20M

Average access rate (ms)

85

65

Encoding scheme

M FM

M FM

BIOS drive type number

1

2

Cylinders

306

615

Heads

4

4

Sectors per track

17

17

Rotational speed (RPM s)

3600

3600

Interleave factor

6:1

6:1

Data transfer rate (kilobytes/ second)

85

85

Automatic head parking

No

No

Expansion Slot s Total adapter slots

8

Number of long/ short slots

6/ 2

Number of 8-/ 16-/ 32-bit slots

8/ 0/ 0

Available slots (with video)

4

Keyboard Specificat ions 101-key Enhanced keyboard

Yes

Fast keyboard speed setting

No

Keyboard cable length

6 feet

An Introduction to the XT (5160)

Physical Specificat ions Footprint type

Desktop

Dimensions: Height

5.5 inches

Width

19.5 inches

Depth

16.0 inches

Weight

32 pounds

Environm ent al Specificat ions Power-supply output

130 watts

Worldwide (110v/ 60Hz, 220v/ 50Hz)

No

Auto-sensing/ switching

No

M aximum current: 90-137 VAC

4.2 amps

Operating range: Temperature

60–90 degrees F

Relative humidity

8–80 percent

M aximum operating altitude

7,000 feet

Heat (BTUs/ hour)

717

Noise (Average db, operating, 1m)

56

FCC classification

Class B

Table 20.6 sh ows th e XT m oth erboard switch settin gs. Th e XT m oth erboard u ses a sin gle eigh t-p osition switch block to con trol variou s fu n ction s, as d etailed in th e table. Table 20.6

IBM PC/ XT M ot herboard Sw it ch Set t ings

Sw it ch Block 1 ( PC and XT) Sw it ch 1

IBM PC Funct ion ( PC Only)

Off

Boot From Floppy Drives

On

Do Not Boot From Floppy Drives

Sw it ch 1

IBM XT Funct ion ( XT Only)

Off

Normal POST (Power-On Self Test)

On

Continuous Looping POST

Sw it ch 2

M at h Coprocessor ( PC/ XT)

Off

Installed

On

Not Installed

Sw it ch 3

Sw it ch 4

Inst alled M ot herboard M em ory ( PC/ XT)

On

On

Bank 0 Only

Off

On

Banks 0 and 1

On

Off

Banks 0, 1, and 2

Off

Off

All 4 Banks (continues)

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Table 20.6

IBM PC/ XT M ot herboard Sw it ch Set t ings Cont inued

Sw it ch Block 1 ( PC and XT) Sw it ch 5

Sw it ch 6

Video Adapt er Type ( PC/ XT) :

Off

Off

M onochrome (M DA)

Off

On

Color (CGA); 40×25 mode

On

Off

Color (CGA); 80×25 mode

On

On

Any Video Card w/ onboard BIOS (EGA/ VGA)

Sw it ch 7

Sw it ch 8

Num ber of Floppy Drives ( PC/ XT) :

On

On

1 floppy drive

Off

On

2 floppy drives

On

Off

3 floppy drives

Off

Off

4 floppy drives

Table 20.7 sh ows th e p art n u m bers of th e XT system u n its. Table 20.7

IBM XT M odel Part Num bers

Descript ion

Num ber

XT system unit/ 83-key keyboard, 256K: One full-height 360K drive

5160068

One half-height 360K drive

5160267

Two full-height 360K drives

5160078

Two half-height 360K drives

5160277

XT system unit/ 101-key keyboard, 256K: One half-height 360K drive

5160268

Two half-height 360K drives

5160278

XT system unit/ 83-key keyboard, 256K, one serial, one full-height 360K drive, 10M hard disk

5160086

XT system unit/ 83-key keyboard, 640K, one serial, one half-height 360K drive, 20M fixed disk

5160088

XT system unit/ 101-key keyboard, 640K, one serial, one half-height 360K drive, 20M fixed disk

5160089

Opt ion Num bers PC expansion-unit M odel 002, 20M fixed disk

5161002

20M fixed disk drive

6450326

20M fixed disk adapter

6450327

10M fixed disk drive

1602500

10M fixed disk adapter

1602501

5 1/ 4-inch, half-height, 360K drive

6450325

5 1/ 4-inch, full-height, 360K drive

1503810

3 1/ 2-inch, half-height, 720K internal drive

6450258

3 1/ 2-inch, half-height, 720K external drive

2683190

An Introduction to the Portable PC

Opt ion Num bers 8087 math coprocessor option

1501002

Asynchronous serial adapter

1502074

Enhanced Keyboard Accessories Clear keycaps (60) with paper inserts

6341707

Blank light keycaps

1351710

Blank dark keycaps

1351728

Paper inserts (300)

6341704

Keycap-removal tools (6)

1351717

An Int roduct ion t o t he Port able PC IBM in trod u ced th e Portable PC on Febru ary 16, 1984. Th e IBM Portable PC, a “tran sp ortable” p erson al com p u ter, is a sm all su itcase-sized system th at h as a bu ilt-in 9-in ch am ber com p osite vid eo m on itor; on e 5 1/ 4-in ch h alf-h eigh t flop p y d isk d rive (with sp ace for an op tion al secon d d rive); an 83-key keyboard ; two ad ap ter card s; a flop p y d isk con troller; an d a CGA. Th e u n it also h as a u n iversal-voltage p ower su p p ly cap able of overseas op eration on 220-volt p ower. Figu re 20.7 sh ows th e Portable PC exterior. CRT Brightness and contrast controls

9" Amber CRT

360K Floppy drives

Keyboard cable connector

FIG. 20.7 Th e IBM Portable PC. Th e system board u sed in th e IBM Portable PC is th e sam e board u sed in th e origin al IBM XTs, with 256K of m em ory. Becau se th e XT m oth erboard was u sed , eigh t exp an sion slots are available for th e con n ection of ad ap ter board s, alth ou gh on ly two slots can accep t a fu ll-len gth ad ap ter card d u e to in tern al sp ace restriction s. Th e p ower su p p ly is basically th e sam e as an XT’s, with p h ysical ch an ges for p ortability an d a sm all am ou n t of p ower d rawn to ru n th e bu ilt-in m on itor. In fu n ction an d p erform an ce, th e Portable PC system u n it h as id en tical ch aracteristics to an eq u ivalen tly con figu red IBM PC XT system u n it. Figu re 20.8 sh ows th e Portable PC in terior view. IBM with d rew th e Portable PC from th e m arket on Ap ril 2, 1986, a d ate th at coin cid es with th e in trod u ction of th e IBM Con vertible lap top PC. Th e Portable PC is rare becau se n ot m an y were sold , alth ou gh it com p ared to, an d in m an y ways was better th an , th e h igh ly su ccessfu l Com p aq Portable th at was available at th e tim e. Th e system was largely m isu n d erstood by th e trad e p ress an d u ser com m u n ity. Most d id n ot u n d erstan d th at th e

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system was really a p ortable XT an d h ad m ore to offer th an th e stan d ard IBM PC. Maybe if IBM h ad called th e system th e Portable XT, it wou ld h ave sold better! 9" Amber CRT

Color graphics adaptor

Power switch

Disk drives Power supply

FIG. 20.8 Th e IBM Portable PC in terior. Th e Portable PC system u n it h as th ese m ajor fu n ction al com p on en ts: ■ In tel 8088 4.77MHz m icrop rocessor ■ ROM-based d iagn ostics (POST) ■ BASIC lan gu age in terp reter in ROM ■ 256K of d yn am ic RAM ■ Eigh t exp an sion slots (two lon g slots, on e 3/ 4-len gth slot, an d five sh ort slots) ■ Socket for 8087 m ath cop rocessor ■ Color/ Grap h ics Mon itor Ad ap ter ■ 9-in ch am ber com p osite vid eo m on itor ■ Flop p y d isk in terface ■ On e or two h alf-h eigh t 360K flop p y d rives ■ 114-watt u n iversal p ower su p p ly (115–230V, 50–60Hz) ■ Ligh tweigh t 83-key keyboard ■ En closu re with carryin g h an d le ■ Carryin g bag for th e system u n it Figu re 20.6 sh owed th e XT m oth erboard , wh ich is also u sed in th e Portable PC. Th e followin g is th e tech n ical d ata for th e Portable PC system :

An Introduction to the Portable PC

Syst em Archit ect ure M icroprocessor

8088

Clock speed

4.77M Hz

Bus type

ISA (Industry Standard Architecture)

Bus width

8-bit

Interrupt levels

8 (6 usable)

Type

Edge-triggered

Shareable

No

DM A channels

4 (3 usable)

Bus masters supported

No

Upgradable processor complex

No

M em ory Standard on system board

256K

M aximum on system board

256K

M aximum total memory

640K

M emory speed (ns) and type

200ns dynamic RAM chips

System board memory-socket type

16-pin DIP

Number of memory-module sockets

36 (4 banks of 9)

M emory used on system board

36 64K×1-bit DRAM chips in 4 banks of 9 chips

M emory cache controller

No

Wait states: System board

1

Adapter

1

St andard Feat ures ROM size

40K

ROM shadowing

No

Optional math coprocessor

8087

Coprocessor speed

4.77M Hz

Standard graphics

CGA adapter with built-in 9-inch amber CRT

RS232C serial ports

None standard

UART chip used

NS8250B

M aximum speed (bits per second)

9,600bps

M aximum number of ports supported

2

Pointing device (mouse) ports

None standard

Parallel printer ports

None standard

Bidirectional

No

M aximum number of ports supported

3

CM OS real-time clock (RTC)

No

CM OS RAM

None (continues)

1127

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Chapter 20—IBM Personal Computer Family Hardware

(continued)

Disk St orage Internal disk and tape drive bays

2 half-height

Number of 3 1/ 2-inch / 5 1/ 4-inch bays 0/ 2 Standard floppy drives

1 or 2 ×360K

Optional floppy drives: 5 1/ 4-inch 360K

Optional

5 1/ 4-inch 1.2M

No

3 1/ 2-inch 720K

Optional

3 1/ 2-inch 1.44M

No

3 1/ 2-inch 2.88M

No

Hard disk controller included

None

Expansion Slot s Total adapter slots

8

Number of long/ short slots

2/ 6

Number of 8-/ 16-/ 32-bit slots

8/ 0/ 0

Available slots (with video)

6

Keyboard Specificat ions 101-key Enhanced keyboard

No

Fast keyboard speed setting

No

Keyboard cable length

6 feet

Physical Specificat ions Footprint type

Desktop

Dimensions: Height

8.0 inches

Width

20.0 inches

Depth

17.0 inches

Weight

31 pounds

Environm ent al Specificat ions Power-supply output

114 watts

Worldwide (110/ 60,220/ 50)

Yes

Auto-sensing/ switching

No

M aximum current: 90-137 VAC

4.0 amps

Operating range: Temperature

60–90 degrees F

Relative humidity

8–80 percent

M aximum operating altitude

7,000 feet

An Introduction to the AT

Environm ent al Specificat ions Heat (BTUs/ hour)

650

Noise (Average db, operating, 1m)

42

FCC classification

Class B

Table 20.8 sh ows th e p art n u m bers for th e Portable PC. Table 20.8

IBM Port able PC M odel Part Num bers

Descript ion

Num ber

256K, one 360K half-height drive

5155068

256K, two 360K half-height drives

5155076

Half-height 360K floppy disk drive

6450300

Th e d isk d rive u sed in th e Portable PC was a h alf-h eigh t d rive, th e sam e u n it sp ecified for u se in th e PCjr. W h en th e Portable PC was in trod u ced , PCjr was th e on ly oth er IBM sold with th e sam e h alf-h eigh t d rive.

An Int roduct ion t o t he AT IBM in trod u ced th e Personal Com puter AT (Advanced Technology) on Au gu st 14, 1984. Th e IBM AT system in clu d ed m an y featu res p reviou sly u n available in IBM’s PC system s, su ch as in creased p erform an ce, an ad van ced 16-bit m icrop rocessor, h igh -d en sity flop p y d isk an d h ard d isk d rives, larger m em ory sp ace, an d an ad van ced cop rocessor. Desp ite its n ew d esign , th e IBM AT in cred ibly retain ed com p atibility with m ost existin g h ard ware an d software p rod u cts for th e earlier system s. In m ost cases, IBM AT system p erform an ce was from th ree to five tim es faster th an th e IBM XT for sin gle ap p lication s ru n n in g DOS on both com p u ters. Th e p erform an ce in crease was d u e to th e com bin ation of a red u ced cycle cou n t for m ost in stru ction s by th e 80286 p rocessor, an in creased system clock rate, 16-bit m em ory, an d a faster h ard d isk an d con troller. Th e AT system u n it h as been available in several m od els: a flop p y-d isk-eq u ip p ed base m od el (068) an d several h ard -d isk-en h an ced m od els. Based on a h igh -p erform an ce 16-bit In tel 80286 m icrop rocessor, each com p u ter in clu d es Cassette BASIC lan gu age in ROM an d a CMOS (Com p lem en tary Metal Oxid e Sem icon d u ctor) clock an d calen d ar with battery backu p . All m od els are eq u ip p ed with a h igh -d en sity (1.2M) flop p y d isk d rive, a keyboard , an d a lock. For stan d ard m em ory, th e base m od el offers 256K, an d th e en h an ced m od els offer 512K. In ad d ition , th e en h an ced m od els h ave a 20M or a 30M h ard d isk d rive an d a serial/ p arallel ad ap ter. Each system can be exp an d ed th rou gh cu stom er-in stallable op tion s. You can ad d m em ory (u p to 512K) for th e base m od el by ad d in g ch ip s to th e system board . You can exp an d all m od els to 16M by in stallin g m em ory card s.

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Besid es th e stan d ard d rives in clu d ed with th e system , IBM on ly offered two d ifferen t h ard d isks as u p grad es for th e AT: ■ 30M h ard d isk d rive ■ 20M h ard d isk d rive IBM also offered on ly th ree d ifferen t typ es of flop p y d rives for th e AT: ■ A secon d , h igh -d en sity (1.2M) flop p y d isk d rive ■ A d ou ble-d en sity (320/ 360K) flop p y d isk d rive ■ A n ew 3 1/ 2-in ch 720K d rive Th e origin al 068 an d 099 m od els of th e AT d id n ot su p p ort th e 720K d rive in th e BIOS; you h ad to ad d a sp ecial d river (DRIVER.SYS—su p p lied with DOS) for th e d rive to work p rop erly. Th e later-m od el ATs su p p orted th e 720K d rive d irectly in th e BIOS, an d also ad d ed su p p ort for th e 1.44M h igh -d en sity 3 1/ 2-in ch flop p y d rive, alth ou gh IBM n ever sold or officially su p p orted su ch a d rive in th e AT. You can in stall as m an y as two flop p y d isk d rives an d on e h ard d isk d rive or on e flop p y d isk d rive an d two h ard d isk d rives in th e system u n it. To u se th e h igh -d en sity 5 1/ 4in ch flop p y d isk d rives p rop erly, you m u st h ave sp ecial flop p y d isks—5 1/ 4-in ch , h igh coercivity, d ou ble-sid ed , soft-sectored d isks. Du e to track wid th p roblem s between th e h igh -d en sity (1.2M) d rives an d th e d ou ble-d en sity (360K) d rives, a d ou ble-d en sity flop p y d isk d rive (320/ 360K) was available for com p atibility with th e stan d ard PC or XT system s. You can exch an ge d isks reliably between th e 1.2M an d th e stan d ard 360K d rives if you u se th e p rop er m eth od an d u n d erstan d th e record in g p rocess. For tran sferrin g d ata between a system with a 1.2M d rive to a system with a 360K d rive, you m u st start with a blan k (n ever p reviou sly form atted ) 360K d isk, wh ich m u st be form atted an d written on ly by th e 1.2M d rive. No sp ecial p recau tion s are n eed ed to tran sfer th e d ata th e oth er way. Th is in form ation is covered in Ch ap ter 13, “Op tical Storage.” For com p lete in terch an ge reliability an d to sim p lify th e p rocess, h owever, IBM recom m en d s th at you p u rch ase th e 360K d rive. Th e AT m oth erboard h as eigh t slots th at su p p ort card s for ad d ition al d evices, featu res, or m em ory. Six slots su p p ort th e ad van ced 16-bit or 8-bit card s. Two slots su p p ort on ly 8-bit card s. All system -u n it m od els u se on e 16-bit slot for th e fixed d isk an d flop p y d isk d rive ad ap ter. Th e en h an ced m od els u se an ad d ition al 8-bit slot for th e serial/ p arallel ad ap ter. Th e resu lt is seven available exp an sion slots for th e base m od el an d six available exp an sion slots for en h an ced m od els. Figu re 20.9 sh ows th e in terior of an AT system u n it. All AT m od els in clu d e a 192-watt u n iversal p ower su p p ly; a tem p eratu re-con trolled , variable-sp eed coolin g fan ; an d a secu rity lock with key. Th e u ser selects th e p ower su p p ly for a cou n try’s voltage ran ge. Th e coolin g fan sign ifican tly red u ces th e n oise in m ost en viron m en ts; th e fan ru n s slower wh en th e system u n it is cool an d faster wh en th e system u n it is h ot. W h en th e system is locked , n o on e can rem ove th e system -u n it cover, boot th e system , or en ter com m an d s or d ata from th e keyboard , th ereby en h an cin g th e system ’s secu rity.

An Introduction to the AT

Battery Power supply

Keylock

Control panel Speaker Hard disk drive bays Floppy disk drive bays

FIG. 20.9 Th e IBM AT u n it in terior. Th e keyboard is attach ed to th e system u n it by a 9-foot coiled cable th at en ables th e AT to ad ap t to a variety of worksp ace con figu ration s. Th e keyboard in clu d es key-location en h an cem en ts an d m od e in d icators for im p roved keyboard u sability. Figu re 20.10 sh ows th e rear p an el of an AT. Keyboard connector

Adapter slots

Power switch Power supply selector switch 115-230 VAC

Power connector

Back panel

FIG. 20.10 Th e IBM AT rear p an el. Every system u n it for th e AT m od els h as th ese m ajor fu n ction al com p on en ts: ■ In tel 80286 (6MHz or 8MHz) m icrop rocessor ■ Socket for 80287 m ath cop rocessor

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■ Eigh t I/ O exp an sion slots (six 16-bit, two 8-bit) ■ 256K of d yn am ic RAM (base m od el) ■ 512K of d yn am ic RAM (en h an ced m od els) ■ ROM-based d iagn ostics (POST) ■ BASIC lan gu age in terp reter in ROM ■ Hard / flop p y d isk con troller ■ 1.2M h ard d isk flop p y d rive ■ 20M or 30M h ard d isk d rive (en h an ced m od els) ■ Serial/ p arallel in terface (en h an ced m od els) ■ CMOS clock-calen d ar an d con figu ration with battery backu p ■ Keylock ■ 84-key keyboard or En h an ced 101-key keyboard (stan d ard on n ewer m od els) ■ Switch able world wid e p ower su p p ly AT M odels and Feat ures Sin ce th e in trod u ction of th e AT, several m od els h ave becom e available. First, IBM an n ou n ced two system s: a base m odel (068) an d an enhanced m odel (099). Th e p rim ary d ifferen ce between th e two system s is th e stan d ard h ard d isk th at cam e with th e en h an ced m od el. IBM h as in trod u ced two oth er AT system s sin ce th e first system s, each offerin g n ew featu res. Th e first gen eration of AT system s h as a 6MHz system clock th at d ictates th e p rocessor cycle tim e. Th e cycle tim e, th e system ’s sm allest in terval of tim e, rep resen ts th e sp eed at wh ich op eration s occu r. Every op eration in a com p u ter takes at least on e or (u su ally) several cycles to com p lete. Th erefore, if two com p u ters are th e sam e in every way excep t for th e clock sp eed , th e system with th e faster clock rate execu tes th e sam e op eration s in a sh orter tim e p rop ortion al to th e d ifferen ce in clock sp eed . Cycle tim e an d clock sp eed are two d ifferen t ways of d escribin g th e sam e th in g. Discu ssion s of clock sp eed are sign ifican t wh en you ’re con sid erin g bu yin g th e AT, becau se n ot all m od els h ave th e sam e clock sp eed . All m od els of th e AT in clu d e a com bin ation h ard / flop p y d isk con troller th at is really two sep arate con trollers on th e sam e circu it board . Th e board was d esign ed by IBM an d W estern Digital (W D) an d m an u factu red for IBM by W D. Th is con troller h as n o on board ROM BIOS like th e Xebec h ard d isk con troller u sed in th e XT. In th e AT, IBM bu ilt fu ll su p p ort for th e h ard d isk con troller d irectly in to th e m oth erboard ROM BIOS. To su p p ort d ifferen t typ es of h ard d isks, IBM en cod ed a table in to th e m oth erboard ROM th at listed th e p aram eters of variou s d rives th at cou ld be in stalled . In th e first version of th e AT, with a ROM BIOS d ated 01/ 10/ 84, on ly th e first 14 typ es in th e table were filled in . Typ e 15 was reserved for in tern al reason s, an d was n ot u sable. Oth er table

An Introduction to the AT

en tries from 16 th rou gh 47 were left u n u sed an d were actu ally filled with zeros. Later version s of th e AT ad d ed n ew d rive typ es to th e tables, startin g from Typ e 16 an d u p . Th e first two AT m od els were th e 068 (base) m od el, wh ich h ad 256K on th e m oth erboard an d a sin gle 1.2M flop p y d isk d rive; an d th e m od el 099 (en h an ced ), wh ich h ad a 20M h ard d isk d rive, a serial/ p arallel ad ap ter, an d 512K on th e m oth erboard . IBM d esign ated th e m oth erboard on th ese com p u ters as Typ e 1, wh ich is larger th an th e later Typ e 2 board an d u sed an u n u su al m em ory layou t. Th e m em ory is con figu red as fou r ban ks of 128K ch ip s—a total of 512K on th e board . Th is con figu ration sou n d s reason able u n til you realize th at a 128K ch ip d oes n ot really exist in th e p h ysical form factor th at IBM u sed . IBM actu ally created th is typ e of m em ory d evice by stackin g a 64K ch ip on top of an oth er on e an d sold erin g th e two togeth er. My gu ess is th at IBM h ad m an y 64K ch ip s to u se, an d th e AT was available to take th em . On October 2, 1985, IBM an n ou n ced a n ew m od el of th e AT, th e Person al Com p u ter AT Mod el 239. Th e system h as all th e stan d ard featu res of th e AT Mod el 099, bu t also h as a 30M h ard d isk rath er th an a 20M h ard d isk. A secon d , op tion al 30M h ard d isk d rive exp an d s th e Mod el 239’s h ard d isk storage to 60M. Th is u n it’s m oth erboard , a secon d gen eration d esign IBM calls Typ e 2, is abou t 25 p ercen t sm aller th an th e Typ e 1 bu t u ses th e sam e m ou n tin g location s, for p h ysical com p atibility. All im p ortan t item s, su ch as th e slots an d con n ectors, rem ain in th e sam e location s. Oth er m ajor im p rovem en ts in th is board are in th e m em ory. Th e 128K m em ory ch ip s h ave been rep laced by 256K d evices. Now on ly two ban ks of ch ip s were n eed ed to get th e sam e 512K on th e board . Th e AT Mod el 239 in clu d es th ese item s: ■ 512K of RAM (stan d ard ) ■ 6MHz Typ e 2 m oth erboard with 256K m em ory ch ip s ■ Serial/ p arallel ad ap ter (stan d ard ) ■ 30M h ard d isk (stan d ard ) ■ New ROM BIOS (d ated 06/ 10/ 85). ROM su p p orts 3 1/ 2-in ch 720K flop p y d rives with ou t u sin g extern al d river p rogram s, an d 22 u sable h ard d isk typ es (u p to Typ e 23), in clu d in g th e su p p lied 30M d isk. POST “fixes” clock rate to 6MHz. Th e Typ e 2 m oth erboard ’s d esign is m u ch im p roved over Typ e 1’s; th e Typ e 2 m oth erboard im p roved in tern al-circu it tim in g an d layou t. Im p rovem en ts in th e m oth erboard in d icated th at th e system wou ld be p u sh ed to h igh er sp eed s—exactly wh at h ap p en ed with th e n ext rou n d of in trod u ction s. In ad d ition to obviou s p h ysical d ifferen ces, th e Mod el 239 in clu d es sign ifican tly d ifferen t ROM software from th e p reviou s m od els. Th e n ew ROM su p p orts m ore typ es of h ard an d flop p y d isks, an d its n ew POST p reven ts alteration of th e clock rate from th e stan d ard 6MHz m od els. Becau se su p p ort for th e 30M h ard d isk is bu ilt in to th e n ew ROM, IBM sold a 30M h ard d isk u p grad e kit th at in clu d ed th e n ew ROM for th e origin al AT system s. Th is $1,795 kit rep resen ted th e on ly legal way to obtain th e n ewer ROM.

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Th e 30M h ard d isk d rive u p grad e kit for th e Person al Com p u ter AT Mod els 068 an d 099 in clu d ed all th e featu res in th e 30M h ard d isk d rive an n ou n ced for th e AT Mod el 239. Th e u p grad e kit also h ad a n ew basic in p u t-ou tp u t su bsystem (BIOS), essen tial to AT op eration . Th e n ew ROM BIOS su p p orts 22 d rive typ es (com p ared to th e origin al 14 in earlier ATs), in clu d in g th e n ew 30M d rive. To su p p ort th e 30M h ard d isk d rive, a n ew d iagn ostics flop p y d isk an d an u p d ated gu id e-to-op eration s m an u al were sh ip p ed with th is kit. Th e 30M u p d ate kit in clu d ed th ese item s: ■ 30M h ard d isk d rive ■ Two n ew ROM BIOS m od u les ■ Ch an n el keep er bar (a bracket for th e fixed d isk) ■ Data cable for th e h ard d isk ■ Diagn ostics an d Setu p d isk ■ An in sert to th e AT gu id e-to-op eration s m an u al Som e p eop le were u p set in itially th at IBM h ad “fixed ” th e m icrop rocessor clock to 6MHz in th e n ew m od el, th ereby d isallowin g an y p ossible “h ot rod ” or overclockin g m od ification s. Man y p eop le realized th at th e clock crystal on th e AT m od els was socketed so th at th e crystal cou ld be rep laced easily by a faster on e. More im p ortan tly, becau se th e AT circu it d esign is m od u lar, ch an gin g th e clock crystal d oes n ot h ave rep ercu ssion s th rou gh ou t th e rest of th e system , as is th e case in th e PC an d PC XT. For th e p rice of a n ew crystal (from $1 to $30) an d th e tim e n eed ed to p lu g it in , som eon e easily cou ld in crease an AT’s sp eed by 30 p ercen t, an d som etim es m ore. Un fortu n ately, d u e to th e POST in th e n ewer m od el’s BIOS, you n o lon ger can im p lem en t a sim p le sp eed u p alteration with ou t also ch an gin g th e ROM BIOS as well. Man y p eop le believed th at th is ch an ge was m ad e to p reven t th e AT from bein g “too fast” an d th erefore com p etin g with IBM’s m in icom p u ters. In reality, th e earlier m oth erboard was in ten tion ally ru n at 6MHz becau se IBM d id n ot believe th at th e ROM BIOS software an d critical system tim in g was fu lly op eration al at a h igh er sp eed . Also, IBM u sed som e com p on en ts th at were rated on ly for 6MHz op eration , startin g, of cou rse, with th e CPU. Users wh o in creased th e sp eed of th eir early com p u ters often received DOS error m essages from tim in g p roblem s, an d in som e cases, total system locku p s d u e to com p on en ts n ot fu n ction in g p rop erly at th e h igh er sp eed s. Man y com p an ies sellin g sp eed u p kits sold software to h elp sm ooth over som e of th ese p roblem s, bu t IBM’s official solu tion was to im p rove th e ROM BIOS software an d m oth erboard circu itry, an d to in trod u ce a com p lete n ew system ru n n in g at th e faster sp eed . If you wan t in creased sp eed n o m atter wh at m od el you h ave, several com p an ies u sed to sell clock-crystal rep lacem en ts th at are freq u en cy syn th esizers rath er th an a fixed typ e of crystal. Th e u n its can wait u n til th e POST is fin ish ed an d ch an ge m id stream to an in creased op eratin g sp eed . Un fortu n ately, I d on ’t kn ow of an yon e wh o is still m akin g or sellin g th ese u p grad es.

An Introduction to the AT

If you really wan t to sp eed u p you r AT by in stallin g a faster clock crystal, in stru ction s can be fou n d on th e CD accom p an yin g th is book on h ow to bu rn you r own set of BIOS with ou t th e ch eck. However, it req u ires th e u se of a sp ecialized PROM or EPROM bu rn er, or access to on e. On Ap ril 2, 1986, IBM in trod u ced th e Person al Com p u ter AT Mod els 319 an d 339. Th ese were th e last an d best AT m od els, an d were an en h an cem en t of th e earlier Mod el 239. Th e p rim ary d ifferen ce from th e Mod el 239 is a faster clock crystal th at p rovid es 8MHz op eration . Th e Mod el 339 h as a n ew keyboard —th e En h an ced keyboard —with 101 keys rath er th an th e u su al 84. Mod el 319 is th e sam e as Mod el 339, bu t in clu d es th e origin al keyboard . High ligh ts of th e Mod els 319 an d 339 are sh own in th is list: ■ Faster p rocessor sp eed (8MHz) ■ Typ e 2 m oth erboard , with 256K ch ip s ■ 512K of RAM (stan d ard ) ■ Serial/ p arallel ad ap ter (stan d ard ) ■ 30M h ard d isk (stan d ard ) ■ New ROM BIOS (d ated 11/ 15/ 85). ROM su p p ort for 22 u sable typ es (u p to typ e 23) of h ard d isks, an d 3 1/ 2-in ch d rives, at both 720K an d 1.44M cap acities. POST “fixes” clock rate to 8MHz. ■ 101-key En h an ced keyboard (stan d ard on Mod el 339) Th e m ost sign ifican t p h ysical d ifferen ce in th ese n ew system s is th e En h an ced keyboard on th e Mod el 339. Th is keyboard , sim ilar to a 3270 keyboard , h as 101 keys. It cou ld be called th e IBM “corp orate” keyboard becau se it is stan d ard on all n ew d esktop system s. Th e 84-key PC keyboard still was available, with a n ew 8MHz m od el, as th e Mod el 319. Th ese n ew 8MHz system s were available on ly in an en h an ced con figu ration with a stan d ard 30M h ard d rive. If you wan ted a h ard d isk larger th an IBM’s 30M, you cou ld eith er ad d a secon d d rive or sim p ly rep lace th e 30M u n it with som eth in g larger. ROM su p p ort for 3 1/ 2-in ch d isk d rives at both 720K an d 1.44M exists on ly in Mod els 339 an d 319. In p articu lar, th e 1.44M d rive, alth ou gh d efin itely su p p orted by th e ROM BIOS an d con troller, was n ever offered as an op tion by IBM. Th is m ean s th at th e IBM Setu p p rogram fou n d on th e Diagn ostics an d Setu p d isk d id n ot offer th e 1.44M flop p y d rive as a ch oice wh en con figu rin g th e system . An ybod y ad d in g su ch a d rive h ad to u se on e of th e m an y Setu p rep lacem en t p rogram s available in th e p u blic d om ain , or “borrow” on e from an IBM-com p atible system th at u sed a flop p y d isk–based setu p p rogram . Ad d in g th e 1.44M d rive becam e on e of th e m ost p op u lar u p grad es for th e AT system s becau se m an y n ewer system s cam e with th at typ e of d rive as stan d ard eq u ip m en t. Earlier AT system s still can u se th e 720K an d 1.44M d rives, bu t th ey n eed to eith er u p grad e th e ROM to su p p ort th em (recom m en d ed ) or p ossibly u se software d rivers to m ake th em work.

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AT BIOS Versions Th ree d ifferen t BIOS version s h ave been u sed in th e IBM AT. Th ey can be id en tified by th eir d ate an d su m m arized as follows: ■ Jan u ary 1, 1984: Th e first AT BIOS version su p p orted on ly 1.2M an d 360K flop p y d rives d irectly. On ly 14 h ard d isk typ es were su p p orted . It cam e on th e Mod el 068 an d 099 system s with th e Typ e 1 m oth erboard . ■ Ju n e 10, 1985: Th e secon d AT BIOS ad d ed su p p ort for 720K 3 1/ 2-in ch d rives d irectly (n o d rivers were req u ired ). Also, m ore h ard d isk d rive typ es were ad d ed , for a total of 22 u sable typ es. A n ew test was ad d ed to th e POST th at cau sed th e POST to fail if th e clock sp eed was altered from 6MHz. Th is BIOS was u sed on th e Mod el 239 with a Typ e 2 m oth erboard . ■ Novem ber 15, 1985: Th e th ird an d fin al AT BIOS ad d ed su p p ort for 1.44M 3 1/ 2in ch d rives (n o d rivers req u ired ). En h an ced 101-key keyboard su p p ort was ad d ed . Th e POST test ch ecked for 8MHz op eration , an d failed if th e system was ru n n in g at an y oth er sp eed . Th is BIOS was u sed on Mod el 319 an d 339 system s, an d cam e on a Typ e 2 m oth erboard . Table 20.2 lists th e d ifferen t IBM Fam ily/ 1 (PC, XT, an d AT) BIOS version s. It also sh ows th e ID, su bm od el, an d revision bytes th at can be d eterm in ed by a software fu n ction call Int 15h, C0 = Return System Configuration Parameters

Som e of th e system s su ch as th e PC an d earlier XT an d AT system s on ly su p p ort th e ID byte; th e su bm od el an d revision bytes h ad n ot been establish ed wh en th ose system s were d evelop ed . Th e table also sh ows th e n u m ber of d rive typ es su p p orted in th e AT an d XT286 system s BIOS. Th e BIOS d ate is stored in all PC-com p atible system s at m em ory ad d ress FFFF5h . To d isp lay th e d ate of you r BIOS, a sim p le DEBUG com m an d can be u sed to view th is ad d ress. DEBUG is a com m an d p rogram su p p lied with MS-DOS. At th e DOS p rom p t, execu te th e followin g com m an d s to ru n DEBUG, d isp lay th e d ate stored in you r BIOS, an d th en exit back to DOS: C:\>DEBUG -D FFFF:5 L 8 FFFF:0000 -Q

30 31 2F-32 32 2F 39 37

01/22/97

In th is exam p le, th e system q u eried sh ows a BIOS d ate of 01/22/97. AT M ot herboard BIOS Hard Drive Tables. Th e AT BIOS con tain s a sp ecial table th at is u sed by th e h ard d isk con troller d river to d eterm in e th e h ard d rive p aram eters. W h en a h ard d isk is in stalled in to th is typ e of system , th e “typ e” of d rive is en tered in to th e CMOS RAM by wh oever h as in stalled th e d rive. Th en , every tim e th e system boots, it looks u p th e p aram eters by con su ltin g th e CMOS RAM for th e p articu lar typ e th at h as been selected .

An Introduction to the AT

Old er system s were th erefore lim ited to wh at d ifferen t d rives th ey cou ld su p p ort or recogn ize by th e en tries bu rn ed in to th eir BIOS table. Th e table u sed in IBM AT an d PS/ 2 system s is sh own in th is section . Th e variou s IBM AT an d PS/ 2 system s th at u se a BIOS d rive table d o n ot n ecessarily h ave all of th e en tries sh own h ere. Th e n u m ber of table en tries con tain ed in a p articu lar system BIOS can vary from on e version to th e n ext. For exam p le, th e origin al AT BIOS (01/ 10/ 84) on ly h ad Typ es 1–14 u sable, wh ile th e later AT BIOS version s (06/ 10/ 85 an d 11/ 15/ 85) h ad 1–14 an d 16–23 u sable. Th e XT-286 h ad 1–14 an d 16–24 as u sable typ es. Som e of th e PS/ 1 an d PS/ 2 system s h ad th e table filled in as far as Typ e 44. Non -IBM system s q u ickly ad op ted sp ecial “User Defin able” or even “Au to-Detect” typ es wh ere you cou ld eith er m an u ally en ter th e com p lete table en try (rath er th an selectin g a p red eterm in ed “typ e”), or th e system wou ld au tom atically read th e typ e in form ation d irectly from th e d rive.

Not e If you have a non-IBM PC-compatible system, note that the IBM table may be inaccurate for many of the entries past Type 15. Instead, you should consult your CM OS Setup program; most will show the available types as you scroll through them. Another option is to consult your system, motherboard, or BIOS documentation to see if it shows the correct table entries. A final alternative is a program such as the Seagate FINDTYPE program that will scan your BIOS, locate the table, and display or print it for viewing. This program can be downloaded from the Seagate Web site or BBS. M ost compatibles follow the IBM table for at least the first 15 entries.

Most PS/ 2 system s h ave th e d rive’s d efect m ap written as d ata on th e d rive on e cylin d er beyon d th e h igh est rep orted cylin d er. Th is sp ecial d ata is read by th e IBM PS/ 2 Ad van ced Diagn ostics low-level form at p rogram . Th is p rocess au tom ates th e en try of th e d efect list an d elim in ates th e ch an ce of h u m an error, as lon g as you u se on ly th e IBM PS/ 2 Ad van ced Diagn ostics for h ard d isk low-level form attin g on th ose system s. Th is typ e of table d oes n ot ap p ly to IBM En h an ced Sm all Device In terface (ESDI) or SCSI h ard d isk con trollers, h ost ad ap ters, an d d rives. Becau se th e ESDI an d SCSI con trollers or h ost ad ap ters q u ery th e d rive d irectly for th e req u ired p aram eters, n o table-en try selection is n ecessary. Note, h owever, th at th e table for th e ST-506/ 412 d rives can still be fou n d cu rren tly in th e ROM BIOS of m ost of th e PS/ 2 system s, even if th e m od el cam e stan d ard with an ESDI or SCSI d isk su bsystem . Table 20.9 sh ows th e IBM m oth erboard ROM BIOS h ard d isk p aram eters for AT or PS/ 2 system s u sin g ST-506/ 412 (stan d ard or IDE) con trollers.

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Chapter 20—IBM Personal Computer Family Hardware

Table 20.9

IBM AT and PS/ 2 BIOS Hard Disk Table

Type

Cylinders

Heads

W PC

Ct rl

LZ

S/ T

M

Byt es

1

306

4

128

00h

305

17

10.16

10.65

2

615

4

300

00h

615

17

20.42

21.41

3

615

6

300

00h

615

17

30.63

32.12

4

940

8

512

00h

940

17

62.42

65.45

5

940

6

512

00h

940

17

46.82

49.09

6

615

4

65535

00h

615

17

20.42

21.41

7

462

8

256

00h

511

17

30.68

32.17

8

733

5

65535

00h

733

17

30.42

31.90

9

900

15

65535

08h

901

17

112.06

117.50

10

820

3

65535

00h

820

17

20.42

21.41

11

855

5

65535

00h

855

17

35.49

37.21

12

855

7

65535

00h

855

17

49.68

52.09

13

306

8

128

00h

319

17

20.32

21.31

14

733

7

65535

00h

733

17

42.59

44.66

15*

0

0

0

00h

0

0

0

0

16

612

4

0

00h

663

17

20.32

21.31

17

977

5

300

00h

977

17

40.55

42.52

18

977

7

65535

00h

977

17

56.77

59.53

19

1024

7

512

00h

1023

17

59.50

62.39

20

733

5

300

00h

732

17

30.42

31.90

21

733

7

300

00h

732

17

42.59

44.66

22

733

5

300

00h

733

17

30.42

31.90

23

306

4

0

00h

336

17

10.16

10.65

24

612

4

305

00h

663

17

20.32

21.31

25

306

4

65535

00h

340

17

10.16

10.65

26

612

4

65535

00h

670

17

20.32

21.31

27

698

7

300

20h

732

17

40.56

42.53

28

976

5

488

20h

977

17

40.51

42.48

29

306

4

0

00h

340

17

10.16

10.65

30

611

4

306

20h

663

17

20.29

21.27

31

732

7

300

20h

732

17

42.53

44.60

32

1023

5

65535

20h

1023

17

42.46

44.52

33

614

4

65535

20h

663

25

29.98

31.44

34

775

2

65535

20h

900

27

20.43

21.43

35

921

2

65535

20h

1000

33

29.68

31.12

36

402

4

65535

20h

460

26

20.41

21.41

37

580

6

65535

20h

640

26

44.18

46.33

38

845

2

65535

20h

1023

36

29.71

31.15

39

769

3

65535

20h

1023

36

40.55

42.52

An Introduction to the AT

Type

Cylinders

Heads

W PC

Ct rl

LZ

S/ T

M

Byt es

40

531

4

65535

20h

532

39

40.45

42.41

41

577

2

65535

20h

1023

36

20.29

21.27

42

654

2

65535

20h

674

32

20.44

21.43

43

923

5

65535

20h

1023

36

81.12

85.06

44

531

8

65535

20h

532

39

80.89

84.82

45

0

0

0

00h

0

0

0.00

0.00

46

0

0

0

00h

0

0

0.00

0.00

47

0

0

0

00h

0

0

0.00

0.00

*Table entry 15 is reserved to act as a pointer to indicate that the type is greater than 15. Type = Table entry num ber Cylinders = Total num ber of cylinders Heads = Total num ber of heads W PC = W rite Pre-Com pensation starting cylinder 65535 = No W rite Pre-Com pensation (also shown as –1) 0 = W rite Pre-Com pensation on all cylinders Ctrl = Control byte, with values according to the following table

Bit Num ber

Hex

M eaning

Bit 0

01h

Not used (XT = drive step rate)

Bit 1

02h

Not used (XT = drive step rate)

Bit 2

04h

Not used (XT = drive step rate)

Bit 3

08h

M ore than eight heads

Bit 4

10h

Not used (XT = imbedded servo drive)

Bit 5

20h

OEM defect map at (cylinders + 1)

Bit 6

40h

Disable ECC retries

Bit 7

80h

Disable disk access retries

LZ = Landing-Zone cylinder used for head parking S/T = Num ber of Sectors per Track M = Drive capacity in Megabytes Bytes = in Millions

M odifying ROM BIOS Hard Disk Drive Param et er Tables. Becau se th e IBM tables in th e AT an d XT-286 system s (as well as m an y of th e com p atibles of th e d ay) were fixed , tech n ician s back th en often fou n d it n ecessary to m od ify th e BIOS in th ose system s to ad d d rive typ es for n ew d rives th ey wan ted to in stall. For exam p le, I ad d ed two n ew d rive typ es to on e of m y old AT system s. Th ose typ es—25 an d 26—h ave th ese p aram eters: Type

Cylinders

Heads

W PC

Ct rl

LZ

S/ T

M

Byt es

25

918

15

65535

08h

918

17

114.30

119.85

26

918

15

65535

08h

918

26

174.81

183.31

W PC = W rite Pre-Com pensation start cylinder Ctrl = Control byte, 08h = More than 8 heads, else 00h LZ = Landing Zone or head-parking cylinder S/T = Sectors per Track M = Megabytes Bytes = in Millions

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Chapter 20—IBM Personal Computer Family Hardware

In m y old AT system , th ese table en tries origin ally were u n u sed (zeros), as are th e rem ain d er of typ es from 27–47. By bu rn in g a n ew set of ROMs with th ese two n ew com p leted en tries, I was able to u se a Maxtor XT-1140 d rive to m axim u m cap acity with an MFM 17-sector-p er-track con troller (as Typ e 25) or an RLL 26-sector-p er-track con troller (as Typ e 26). Th is m eth od p reclu d ed th e n eed for a con troller with its own sep arate on board BIOS to overrid e th e m oth erboard table valu es. It also saved m em ory in th e C000 or D000 UMA segm en ts, wh ere su ch a h ard d isk con troller ROM n orm ally wou ld resid e.

Tip If you are interested in performing this modification, get the IBM AT Technical Reference M anual (sold by IBM or Annabooks), which documents the position and format of the drive tables in the BIOS.

Changing t he Hard Disk Cont roller Head St ep Rat e. An oth er m ore com p licated m od ification th at you can p erform to th e AT BIOS is to in crease th e step p in g rate of th e h ard d isk con troller. Th e first ed ition of th is book briefly m en tion ed th is m od ification , an d a read er wrote to m e to exp ress in terest in it. Details of th e m od ification can be fou n d on th e CD. However, th e p erform an ce in crease is relatively sligh t. AT Technical Specificat ions Tech n ical in form ation for th e AT system is d escribed in th is section . You will fin d in form ation abou t th e system arch itectu re, m em ory con figu ration s an d cap acities, stan d ard system featu res, d isk storage, exp an sion slots, an d keyboard sp ecification s, as well as p h ysical an d en viron m en tal sp ecification s. Th is typ e of in form ation can be u sefu l in d eterm in in g wh at typ es of p arts are n eed ed wh en you are u p grad in g or rep airin g th ese system s. Figu res 20.11 an d 20.12 sh ow th e layou t an d com p on en ts on th e two d ifferen t AT m oth erboard s. Syst em Archit ect ure M icroprocessor

80286

Clock speed

6M Hz or 8M Hz

Bus type

ISA (Industry Standard Architecture)

Bus width

16-bit

Interrupt levels

16 (11 usable)

Type

Edge-triggered

Shareable

No

DM A channels

8 (7 usable)

Bus masters supported

Yes

Upgradable processor complex

No

An Introduction to the AT

Keyboard connector Battery connector

Math coprocessor connector

8/16-bit ISA bus slots Display switch

CMOS RAM/RTC

8042 keyboard controller

8259 interrupt controllers

286 processor

Clock crystal

ROM BIOS sockets

8237 DMA controllers

Variable capacitor clock trimmer Keylock connector

128K Memory modules Speaker connector

FIG. 20.11 Th e IBM AT Typ e 1 m oth erboard . M em ory Standard on system board

512K

M aximum on system board

512K

M aximum total memory

16M

M emory speed (ns) and type

150ns dynamic RAM chips

System board memory-socket type

16-pin DIP

Number of memory-module sockets

18 or 36 (2 or 4 banks of 18)

M emory used on system board

36 128K×1-bit DRAM chips in 2 banks of 18, or 18 256K×1-bit chips in one bank (continues)

1141

1142

Chapter 20—IBM Personal Computer Family Hardware (continued)

M em ory M emory cache controller

No

Wait states: System board

1

Adapter

1

St andard Feat ures ROM size

64K

ROM shadowing

No

Optional math coprocessor

80287

Coprocessor speed

4 or 5.33M Hz

Standard graphics

None standard

RS232C serial ports

1 (some models)

UART chip used

NS16450

M aximum speed (bits per second)

9,600bps

M aximum number of ports supported

2

Pointing device (mouse) ports

None standard

Parallel printer ports

1 (some models)

Bidirectional

Yes

M aximum number of ports supported

3

CM OS real-time clock (RTC)

Yes

CM OS RAM

64 bytes

Battery life

5 years

Disk St orage Internal disk and tape drive bays

1 full-height and 2 half-height

Number of 3 1/ 2-inch and 5 1/ 4-inch bays

0/ 3

Standard floppy drives

1 ×1.2M

Optional floppy drives: 5 1/ 4-inch 360K

Optional

5 1/ 4-inch 1.2M

Standard

3 1/ 2-inch 720K

Optional

3 1/ 2-inch 1.44M

Optional (8M Hz models)

3 1/ 2-inch 2.88M

No

Hard disk controller included

ST-506/ 412 (Western Digital WD1002-WA2 or WD1003-WA2)

ST-506/ 412 hard disks available

20/ 30M

Drive form factor

5 1/ 4-inch

Drive interface

ST-506/ 412

Drive capacity

20M

30M

Average access rate (ms)

40

40

Encoding scheme

M FM

M FM

An Introduction to the AT

Disk St orage BIOS drive type number

2

Cylinders

615

20 733

Heads

4

5

Sectors per track

17

17

Rotational speed (RPM s)

3600

3600

Interleave factor

3:1

3:1

Data transfer rate (kilobytes/ second)

170

170

Automatic head parking

Yes

Yes Keyboard connector

Battery connector

Math coprocessor connector

8/16-bit ISA bus slots

CMOS RAM/RTC Power-supply connector

Display switch

8042 keyboard controller 8259 interrupt controllers

Variable capacitor clock trimmer

Clock crystal 286 processor

ROM BIOS sockets 8237 DMA controllers

Keylock connector 256K Memory modules Speaker connector

FIG. 20.12 Th e IBM AT Typ e 2 m oth erboard .

1143

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Chapter 20—IBM Personal Computer Family Hardware

Expansion Slot s Total adapter slots

8

Number of long and short slots

8/ 0

Number of 8-/ 16-/ 32-bit slots

2/ 6/ 0

Available slots (with video)

5

Keyboard Specificat ions 101-key Enhanced keyboard

Yes (8M Hz models)

Fast keyboard speed setting

Yes

Keyboard cable length

6 feet

Physical Specificat ions Footprint type

Desktop

Dimensions: Height

6.4 inches

Width

21.3 inches

Depth

17.3 inches

Weight

43 pounds

Environm ent al Specificat ions Power-supply output

192 watts

Worldwide (110/ 60,220/ 50)

Yes

Auto-sensing/ switching

No

M aximum current: 90-137 VAC

5.0 amps

Operating range: Temperature

60–90 degrees F

Relative humidity

8–80 percent

M aximum operating altitude

7,000 feet

Heat (BTUs/ hour)

1229

Noise (Average db, operating, 1m)

42

FCC classification

Class B

Table 20.12 sh ows th e AT system -u n it p art-n u m ber in form ation . Table 20.12

IBM AT M odel Part Num bers

Descript ion

Num ber

AT 6M Hz/ 84-key keyboard, 256K One 1.2M floppy drive

5170068

AT 6M Hz/ 84-key keyboard, 512K, serial/ parallel One 1.2M floppy drive, 20M hard disk

5170099

One 1.2M floppy drive, 30M hard disk

5170239

An Introduction to the XT M odel 286

Descript ion

Num ber

AT 8M Hz/ 84-key keyboard, 512K, serial/ parallel One 1.2M floppy drive, 30M hard disk

5170319

AT 8M Hz/ 101-key, 512K, serial/ parallel One 1.2M floppy drive, 30M hard disk

5170339

Syst em Opt ions 20M fixed disk drive

6450205

30M fixed disk

6450210

30M fixed disk drive upgrade kit

6450468

360K half-height floppy disk drive (AT)

6450207

1.2M high-density drive

6450206

3 1/ 2-inch, half-height, 720K external drive (AT)

2683191

Serial/ parallel adapter

6450215

80287 math coprocessor option

6450211

Floor-standing enclosure

6450218

Enhanced Keyboard Accessories Clear keycaps (60) with paper inserts

6341707

Blank light keycaps

1351710

Blank dark keycaps

1351728

Paper keycap inserts (300)

6341704

Keycap-removal tools (6)

1351717

An Int roduct ion t o t he XT M odel 286 On Sep tem ber 9, 1986, IBM in trod u ced a n ew AT-typ e system d isgu ised in sid e th e ch assis an d case of an XT. Th is XT Mod el 286 system featu red in creased m em ory, an In tel 80286 m icrop rocessor, an d as m an y as th ree in tern al d rives stan d ard . Th e com p u ter com bin ed an XT’s cost-effectiven ess, flexibility, an d ap p earan ce with th e h igh -sp eed , h igh p erform an ce tech n ology of th e In tel 80286 m icrop rocessor. Th is m od el looked like an XT, bu t u n d ern eath th e cover, it was all AT. Th e IBM XT Mod el 286 can op erate as m u ch as th ree tim es faster th an earlier m od els of th e XT in m ost ap p lication s. It h as a stan d ard 640K of m em ory. Variou s m em oryexp an sion op tion s en able u sers to in crease its m em ory to 16M. Stan d ard featu res in th is system in clu d e a h alf-h eigh t, 1.2M, 5 1/ 4-in ch , h igh -d en sity flop p y d isk d rive; a 20M h ard d isk d rive; a serial/ p arallel ad ap ter card ; an d th e IBM En h an ced keyboard . You can select an op tion al, in tern al, secon d flop p y d isk d rive from th e followin g list: ■ Half-h eigh t, 3 1/ 2-in ch , 720K flop p y d rive ■ Half-h eigh t, 3 1/ 2-in ch , 1.44M flop p y d rive ■ Half-h eigh t, 5 1/ 4-in ch , 1.2M flop p y d rive ■ Half-h eigh t, 5 1/ 4-in ch , 360K flop p y d rive

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Chapter 20—IBM Personal Computer Family Hardware

Th e IBM XT Mod el 286’s p erform an ce stem s p rim arily from th e AT m oth erboard d esign , with 16-bit I/ O slots an d an In tel 80286 p rocessor ru n n in g at 6MHz. In ad d ition to th e typ e of p rocessor u sed , clock sp eed an d m em ory arch itectu re are th e p rim ary factors in d eterm in in g system p erform an ce. Dep en d in g on th e m od el, th e IBM AT’s clock sp eed is 6MHz or 8MHz, with on e wait state; th e XT Mod el 286 p rocesses d ata at 6MHz, with zero wait states. Th e elim in ation of a wait state im p roves p erform an ce by in creasin g p rocessin g sp eed for system m em ory access. Th e zero-wait-state d esign m akes th e XT Mod el 286 d efin itely faster th an th e origin al AT m od els th at ran at 6MHz an d abou t eq u al in sp eed to th e 8MHz AT system s. Based on tests, th e XT Mod el 286 also is abou t th ree tim es faster th an an actu al XT. Becau se th e XT Mod el 286 is an AT-class system , th e p rocessor su p p orts both real an d p rotected m od es. Op eratin g in real ad d ress m od e, th e 80286 is 8088-com p atible; th erefore, you can u se m ost software th at ru n s on th e stan d ard PC system s. In real ad d ress m od e, th e system can ad d ress as m u ch as 1M of RAM. Protected m od e p rovid es a n u m ber of ad van ced featu res to facilitate m u ltitaskin g op eration s. Protected m od e p rovid es sep aration an d p rotection of p rogram s an d d ata in m u ltitaskin g en viron m en ts. In p rotected m od e, th e 80286 can ad d ress as m u ch as 16M of real m em ory an d 1G of virtu al m em ory. In th is m od e, th e XT Mod el 286 can ru n ad van ced op eratin g system s su ch as OS/ 2 an d UNIX. W h en th e XT Mod el 286 was in trod u ced , it was th e least-exp en sive IBM system cap able of ru n n in g a tru e m u ltitaskin g op eratin g system . Th e IBM XT Mod el 286 h as a stan d ard 640K of RAM. Mem ory op tion s en able th e system to grow to 15 1/ 2M, m u ch h igh er th an th e 640K lim it in oth er PC XTs. If you ad d an op eratin g system su ch as OS/ 2 or W in d ows, you can take ad van tage of th e larger m em ory cap acities th at th e XT Mod el 286 p rovid es. A 20M h ard d isk d rive is a stan d ard featu re in th e XT Mod el 286, as is a 5 1/ 4-in ch , 1.2M, h igh -d en sity flop p y d isk d rive. A sim ilar flop p y d isk d rive is stan d ard on all m od els of th e AT. Flop p y d isks form atted on a 1.2M flop p y d isk d rive th erefore can be read by an AT or an XT Mod el 286. Th e 1.2M flop p y d isk d rive also can read flop p y d isks form atted with PC-fam ily m em bers th at u se a 360K flop p y d isk d rive. Figu re 20.13 sh ows th e in terior of an XT-286 system u n it. Th e XT Mod el 286 featu res th e IBM En h an ced keyboard with in d icator ligh ts. Man y IBM p erson al com p u ters u se th e En h an ced keyboard , bu t th e XT Mod el 286 was th e first PC XT to featu re keyboard in d icator ligh ts. Five slots su p p ort th e ad van ced 16-bit card s or 8-bit card s; th ree su p p ort on ly 8-bit card s. Two of th e th ree 8-bit slots su p p ort on ly sh ort card s. A h ard d isk an d flop p y d rive ad ap ter card are stan d ard featu res in th e XT Mod el 286. Th is m u ltifu n ction card takes on ly on e 16-bit slot an d su p p orts as m an y as fou r d isk d rives (two flop p y d isk d rives an d two h ard d isk d rives). Th e serial/ p arallel ad ap ter, an oth er stan d ard featu re, is a com bin ation card th at req u ires on ly on e slot (eith er typ e) an d p rovid es a serial an d a p arallel p ort. Th e p arallel p ortion of th e ad ap ter h as th e cap acity to attach d evices, su ch as a p arallel p rin ter, th at accep t

An Introduction to the XT M odel 286

eigh t bits of p arallel d ata. Th e fu lly p rogram m able serial p ortion su p p orts asyn ch ron ou s com m u n ication s from 50bp s to 9,600bp s, alth ou gh even h igh er sp eed s are p ossible with th e righ t software. Th e serial p ortion req u ires an op tion al serial-ad ap ter cable or a serialad ap ter con n ector. W h en on e of th ese op tion s is con n ected to th e ad ap ter, all th e sign als in a stan d ard EIA RS-232C in terface are available. You can u se th e serial p ort for in terfacin g a m od em , a rem ote d isp lay term in al, a m ou se, or oth er serial d evice. Th e XT Mod el 286 su p p orts u p to two serial/ p arallel ad ap ters. Power supply Chassis assembly Battery holder

Speaker assembly

System board

FIG. 20.13 Th e IBM XT-286 in terior. A stan d ard IBM XT Mod el 286 offers th ese featu res: ■ 80286 p rocessor at 6MHz with 0 wait states ■ 640K of m oth erboard m em ory ■ 1.2M flop p y d rive ■ 20M h ard d isk ■ Five 16-bit an d th ree 8-bit exp an sion slots ■ Fixed d isk/ flop p y d isk d rive ad ap ter (occu p ies on e 16-bit exp an sion slot) ■ Serial/ p arallel ad ap ter (occu p ies on e 16-bit exp an sion slot) ■ En h an ced 101-key keyboard with in d icator ligh ts ■ CMOS tim e-an d -d ate clock with battery backu p XT M odel 286 M odels and Feat ures Th e XT Mod el 286 p rocessor is as m u ch as th ree tim es faster in tern ally th an th e p reced in g XT fam ily an d as m u ch as 25 p ercen t faster th an th e AT Mod el 239, d ep en d in g on sp ecific ap p lication s. A 20M fixed d isk an d a 1.2M 5 1/ 4-in ch flop p y d isk d rive were stan d ard on th e XT Mod el 286. On e ad d ition al flop p y d isk d rive can be in stalled in tern ally as d rive B. You can ad d as a secon d h alf-h eigh t flop p y d rive an y typ e of flop p y

1147

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Chapter 20—IBM Personal Computer Family Hardware

d rive, in clu d in g both th e d ou ble an d h igh -d en sity version s of th e 5 1/ 4- an d 3 1/ 2-in ch d rives. If you wan t to be able to read stan d ard 5 1/ 4-in ch d ata or p rogram flop p y d isks created by th e XT Mod el 286 on oth er PC system s, you m igh t wan t to ad d a 5 1/ 4-in ch 360K flop p y d isk d rive, wh ich p rovid es fu ll read / write com p atibility with th ose system s. Th is is d u e to th e fact th at th e 1.2M d rives write a n arrower track th an th e 360K d rives an d are u n able to p rop erly overwrite a flop p y d isk written on first by a 360K d rive. If fu ll read / write com p atibility with 360K d rives is n ot im p ortan t, you can ad d a secon d 1.2M h igh d en sity flop p y d isk d rive. You can ad d an y 3 1/ 2-in ch d rive, in clu d in g th e 720K an d 1.44M version s. Becau se th e 1.44M d oes n ot h ave an y read / write com p atibility p roblem s with th e 720K d rives, h owever, an d th e 1.44M d rives always can op erate in 720K m od e, I su ggest ad d in g on ly th e 1.44M 3 1/ 2-in ch d rives rath er th an th e 720K version s. Th e h igh er-d en sity d rive is on ly a sm all extra exp en se com p ared to th e d ou ble-d en sity version . Most p eop le d o n ot kn ow th at fu ll ROM BIOS su p p ort for th ese 1.44M d rives is p rovid ed in th e XT Mod el 286. Un fortu n ately, becau se IBM n ever offered th e 1.44M d rive as an op tion , th e su p p lied Setu p p rogram d oes n ot offer th e 1.44M d rive as a ch oice in th e Setu p rou tin e. In stead , you h ave to u se on e of th e m an y available p u blic d om ain AT typ e setu p p rogram s, or “borrow” su ch a p rogram from an AT-com p atible system . XT M odel 286 Technical Specificat ions Th e tech n ical in form ation for th e XT-286 system d escribed in th is section covers th e system arch itectu re, m em ory con figu ration s an d cap acities, stan d ard system featu res, d isk storage, exp an sion slots, keyboard sp ecification s, an d also p h ysical an d en viron m en tal sp ecification s. You can u se th is in form ation to d eterm in e th e p arts you n eed wh en you are u p grad in g or rep airin g th ese system s. Figu re 20.14 sh ows th e layou t an d com p on en ts on th e XT-286 m oth erboard . Syst em Archit ect ure M icroprocessor

80286

Clock speed

6M Hz

Bus type

ISA (Industry Standard Architecture)

Bus width

16-bit

Interrupt levels

16 (11 usable)

Type

Edge-triggered

Shareable

No

DM A channels

8 (7 usable)

Bus masters supported

Yes

Upgradable processor complex

No

M em ory Standard on system board

640K

M aximum on system board

640K

An Introduction to the XT M odel 286

M em ory M aximum total memory

16M

M emory speed (ns) and type

150ns dynamic RAM chips/ SIM M s

System board memory-socket type

30-pin (9-bit) SIM M

Number of memory-module sockets

2

M emory used on system board

One bank of 4 64K×4-bit and 2 64K×1-bit DRAM parity chips, and one bank of 2 9-bit SIM M s

M emory cache controller

No

Wait states: System board

0

Adapter

1

St andard Feat ures ROM size

64K

ROM shadowing

No

Optional math coprocessor

80287

Coprocessor speed

4.77M Hz

Standard graphics

None standard

RS232C serial ports

1

UART chip used

NS16450

M aximum speed (bits per second)

9,600bps

M aximum number of ports supported

2

Pointing device (mouse) ports

None standard

Parallel printer ports

1

Bidirectional

Yes

M aximum number of ports supported

3

CM OS real-time clock (RTC)

Yes

CM OS RAM

64 bytes

Battery life

5 years

Disk St orage Internal disk and tape drive bays

1 full-height and 2 half-height

Number of 3 1/ 2-inch and 5 1/ 4-inch bays

0/ 3

Standard floppy drives

1 ×1.2M

Optional floppy drives: 5 1/ 4-inch 360K

Optional

5 1/ 4-inch 1.2M

Standard

3 1/ 2-inch 720K

Optional

3 1/ 2-inch 1.44M

Optional

3 1/ 2-inch 2.88M

No

Hard disk controller included

ST-506/ 412 (Western Digital WD1003-WA2)

ST-506/ 412 hard disks available

20M

Drive form factor

5 1/ 4-inch (continues)

1149

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Chapter 20—IBM Personal Computer Family Hardware

(continued)

Disk St orage Drive interface

ST-506/ 412

Drive capacity

20M

Average access rate (ms)

65

Encoding scheme

M FM

BIOS drive type number

2

Cylinders

615

Heads

4

Sectors per track

17

Rotational speed (RPM s)

3600

Interleave factor

3:1

Data transfer rate (kilobytes/ second)

170

Automatic head parking

No

Expansion Slot s Total adapter slots

8

Number of long and short slots

6/ 2

Number of 8-/ 16-/ 32-bit slots

3/ 5/ 0

Available slots (with video)

5

Keyboard Specificat ions 101-key Enhanced keyboard

Yes

Fast keyboard speed setting

Yes

Keyboard cable length

6 feet

Physical Specificat ions Footprint type

Desktop

Dimensions: Height

5.5 inches

Width

19.5 inches

Depth

16.0 inches

Weight

28 pounds

Environm ent al Specificat ions Power-supply output

157 watts

Worldwide (110v/ 60Hz, 220v/ 50Hz)

Yes

Auto-sensing/ switching

Yes

M aximum current: 90-137 VAC

4.5 amps

Operating range: Temperature

60–90 degrees F

Relative humidity

8–80 percent

An Introduction to the XT M odel 286

Environm ent al Specificat ions M aximum operating altitude

7,000 feet

Heat (BTUs/ hour)

824

Noise (Average db, operating, 1m)

42

FCC classification

Class B

8/16-bit ISA bus slots

30-pin 256K SIMMs Keyboard connector Battery connector

Power-supply connector

128K memory chips

Display switch

8237 DMA controllers

CMOS RAM/RTC

8259 Interrupt controllers

80286 processor

80287 math coprocessor

FIG. 20.14 Th e IBM XT-286 m oth erboard . Table 20.13 lists th e XT Mod el 286 system -u n it p art n u m bers.

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Chapter 20—IBM Personal Computer Family Hardware

Table 20.13

IBM XT-286 M odel Part Num bers

Descript ion

Num ber

XT M odel 286 system unit, 6M Hz 0 wait state, 640K, serial/ parallel, 1.2M floppy drive, one 20M hard disk

5162286

Opt ional Accessories 5 1/ 4-inch, half-height 360K drive

6450325

3 1/ 2-inch, half-height 720K internal drive

6450258

3 1/ 2-inch, half-height 720K external drive

2683190

80287 math coprocessor option

6450211

Enhanced Keyboard Accessories Clear keycaps (60) with paper inserts

6341707

Blank light keycaps

1351710

Blank dark keycaps

1351728

Paper keycap inserts (300)

6341704

Keycap removal tools (6)

1351717

21

Chapter 21

A Final Word

Th e con ten ts of th is book cover th e com p on en ts of a PC-com p atible system . In th is book, you h ave d iscovered h ow all th e com p on en ts op erate an d in teract, an d h ow th ey sh ou ld be set u p an d in stalled . You h ave seen th e ways th at com p on en ts fail an d learn ed th e sym p tom s of th ese failu res. You reviewed step s in d iagn osin g an d trou blesh ootin g th e m ajor com p on en ts in a system so you can locate an d rep lace a failin g com p on en t. You also learn ed abou t u p grad es for com p on en ts, in clu d in g wh at u p grad es are available, th e ben efits of an u p grad e, an d h ow to obtain an d p erform th e actu al u p grad e. Becau se failin g com p on en ts so often are tech n ically obsolete, it is often d esirable to com bin e rep air an d u p grad e p roced u res to rep lace a failin g p art with an u p grad ed or h igh er-p erform an ce p art. Th e in form ation I h ave p resen ted in th is book rep resen ts m an y years of research , alon g with years of h an d s-on , p ractical exp erien ce with PC-com p atible system s. A great d eal of research an d in vestigation h ave gon e in to each section . Th is in form ation an d kn owled ge h ave saved m an y com p an ies an d even in d ivid u als m an y th ou san d s of d ollars. By read in g th is book, you can also take ad van tage of th is wealth of in form ation ; th e in form ation p resen ted m ay save you an d you r com p an y tim e, en ergy, an d , m ost im p ortan tly, m on ey! Brin gin g PC service an d su p p ort in -h ou se is on e of th e best ways to save m on ey. Elim in atin g service con tracts for m ost system s an d red u cin g d own tim e are ju st two of th e ben efits of ap p lyin g th e in form ation p resen ted in th is book. As I h ave in d icated m an y tim es in th is book, you can also save a lot of m on ey on com p on en t p u rch ases by elim in atin g th e m id d lem an an d p u rch asin g th e com p on en ts d irectly from d istribu tors or m an u factu rers. Ap p en d ix A, “Ven d or List,” p rovid es th e best of th ese sou rces for you to con tact. If you in ten d to bu ild you r own system s, th e ven d or list will be extrem ely u sefu l, as I h ave listed sou rces for all th e com p on en ts n eed ed to assem ble a com p lete system —from th e screws an d brackets all th e way to th e cases, p ower su p p lies, an d m oth erboard s. I h ave fou n d th at th is list is on e of th e m ost freq u en tly u sed p arts of th is book; I u se it m yself all th e tim e. In th e

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p ast, p eop le h ave been u n able to m ake d irect p u rch ases becau se d oin g so req u ired a n ew level of u n d erstan d in g of th e com p on en ts in volved . Also, m an y of th e m an u factu rers an d d irect d istribu tors of p rod u cts are u n able to p rovid e su p p ort for begin n in g u sers; th is is wh y th ey often rely on th e m id d lem en to sell an d su p p ort th eir p rod u cts. Of cou rse, arm ed with th is kn owled ge, you can n ow p u rch ase p rod u cts from m ore d irect sou rces, elim in atin g th e m id d lem an an d p ayin g less for th e p rod u cts in th e p rocess. Th is book can give you th e d eep er level of kn owled ge an d u n d erstan d in g you n eed so you can p u rch ase th e com p on en ts you wan t d irectly from th e ven d ors wh o m an u factu re an d d istribu te th em , savin g a great d eal of m on ey in th e lon g ru n . Not on ly can you u se th is book to save m on ey, bu t th e in form ation con tain ed with in will allow you to h ave th e kn owled ge an d con fid en ce to select exactly th e com p on en ts you n eed to bu ild a cu stom an d yet n on p rop rietary system to you r own sp ecification s. Su ch a system wou ld be fu lly u p grad able an d m ain tain able u sin g in exp en sive in d u strystan d ard com p on en ts. I u sed m an y sou rces to gath er th e in form ation in th is book, startin g with m y own realworld exp erien ces. I h ave also tau gh t th is in form ation to th ou san d s of p eop le in th e h u n d red s of sem in ars p resen ted over th e last 17 years by m y com p an y, Mu eller Tech n ical Research . In fact, m y PC Hard ware sem in ars are th e lon gest-ru n n in g sem in ars on th e su bject. Du rin g th ese sem in ars, I am often asked wh ere m ore tech n ical in form ation can be obtain ed an d wh eth er I h ave an y “secrets” for acq u irin g th is kn owled ge. W ell, I won ’t keep an y secrets! I can freely sh are th e followin g five key sou rces of in form ation th at can h elp you becom e a verifiable exp ert in PC u p grad in g an d rep airin g: ■ Man u als (d ocu m en tation )

■ Magazin es

■ Mod em s (on lin e resou rces su ch as th e In tern et)

■ Meetin gs (sem in ars)

■ Mach in es (h an d s-on work with actu al system s) Th e last th in g I’ll sh ow you in th is ch ap ter is h ow th is book can be a great resou rce to p rep are for th e Com p TIA A+ certification exam . Th ou san d s of A+-certified PC Tech n ician s h ave u sed th is book as p art of th eir train in g (an d con tin u e to u se it in th eir jobs).

M anuals ( Docum ent at ion) Man u als an d d ocu m en tation are th e sin gle m ost im p ortan t sou rces of com p u ter in form ation . Un fortu n ately, th ese also are th e m ost freq u en tly overlooked sou rces of in form ation . Mu ch of m y kn owled ge h as com e from p orin g over tech n ical-referen ce m an u als an d oth er origin al eq u ip m en t m an u factu rers’ (OEM) m an u als.

M anuals (Documentation)

On e of th e biggest p roblem s in trou blesh ootin g, servicin g, or u p grad in g a system is h avin g p rop er d ocu m en tation . I believe th at good d ocu m en tation is critical for system su p p ort an d fu tu re u p grad e cap ability. Becau se it can be a p roblem gettin g d ocu m en tation on old er system s or com p on en ts, th e best tim e to acq u ire d ocu m en tation is wh en th e system or com p on en ts are n ew. Often tim es, th ese m an u als m u st be obtain ed from th e OEM of th e eq u ip m en t you p u rch ase, m ean in g th e ven d or or reseller will n ot su p p ly th em . W h erever p ossible, you sh ou ld m ake an effort to d iscover wh o th e real OEM of each com p on en t in you r system is, so you can obtain d ocu m en tation on th e p rod u ct or com p on en t. A sim p le an alogy exp lain s th e im p ortan ce of m an u als an d oth er issu es con cern in g rep air an d m ain ten an ce of a system . Com p are you r bu sin ess u se of com p u ters to a taxicab com p an y. Th e com p an y h as to p u rch ase au tom obiles to u se as cabs. Th e own ers p u rch ase n ot on e car bu t an en tire fleet of cars. Do you th in k th at th ey wou ld p u rch ase a fleet of au tom obiles based solely on reliability, p erform an ce, or even gas-m ileage statistics? W ou ld th ey n eglect to con sid er on goin g m ain ten an ce an d service of th ese au tom obiles? W ou ld th ey p u rch ase a fleet of cars th at cou ld be serviced on ly by th e origin al m an u factu rer an d for wh ich p arts cou ld n ot be obtain ed easily or in exp en sively? Do you th in k th at th ey wou ld bu y a car th at d id n ot h ave available a d etailed service an d rep air m an u al? W ou ld th ey bu y an au tom obile for wh ich p arts were scarce an d th at was su p p orted by a sp arse d ealer n etwork with few service an d p arts ou tlets, m akin g lon g waits for p arts an d service in evitable? Th e an swer (of cou rse) to all th ese q u estion s is n o, n o, n o! You can see wh y m ost taxicab com p an ies an d p olice d ep artm en ts u se “stan d ard ” au tom obiles su ch as th e Ch evrolet Cap rice or Ford Crown Victoria. If ever th ere were “gen eric” cars, th ese m od els wou ld q u alify! Dealers, p arts, an d d ocu m en tation for th ese p articu lar m od els are everywh ere. Th ese cars sh are p arts with m an y oth er au tom obiles as well, wh ich m akes th em easy to service an d m ain tain . You r bu sin ess (esp ecially if it is large) also am ou n ts to a “fleet” of com p u ters. Th in k of th is fleet as bein g sim ilar to th e cars of a cab com p an y, wh ich wou ld go ou t of bu sin ess q u ickly if th ese cars cou ld n ot be kep t ru n n in g sm ooth ly an d in exp en sively. Now you kn ow wh y th e old Ch ecker Marath on au tom obile u sed to be so p op u lar with cab com p an ies: Its d esign barely ch an ged from th e tim e it was in trod u ced in 1956 u n til it was d iscon tin u ed in Ju ly 1982. Th is m ean t th at p arts in terch an ged an d service p roced u res rem ain ed largely th e sam e over th e en tire 26-year life of th e p rod u ct. In m an y ways, th e in d u stry-stan d ard PC-com p atible system s are like th e ven erable Ch ecker Marath on . You can get tech n ical in form ation by th e sh elffu l for th ese system s. You can get p arts an d u p grad e m aterial from so m an y sou rces th at an yth in g you n eed is always im m ed iately available an d at a d iscou n ted p rice. Th ese are th e ben efits of p u rch asin g in d u stry-stan d ard system s u sin g stan d ard m oth erboard an d ch assis form factors. Th is resu lts in system s th at are easily su p p orted , rep aired , an d u p grad ed . An ad d ition al ben efit is th at wh en th ese stan d ard s are followed , th e system s in a com p an y can be easily m ain tain ed u sin g largely in terch an geable p arts.

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Several typ es of d ocu m en tation are available to cover a given system : ■ System -level docum entation. Th e system -sp ecific m an u al(s) p u t togeth er by th e system m an u factu rer or assem bler. Som e com p an ies break th is d own fu rth er in to Op eration s, Tech n ical Referen ce, an d Service m an u als. ■ Com ponent-level docum entation. Th e sp ecific OEM (Origin al Eq u ip m en t Man u factu rer) m an u als for each m ajor com p on en t, su ch as th e m oth erboard , vid eo card , h ard d isk, flop p y d isk d rive, CD-ROM d rive, m od em , n etwork card , SCSI ad ap ter, an d so on . ■ Chip- and chipset-level docum entation. Th e m ost sp ecific an d tech n ical m an u als th at cover item s su ch as th e p rocessor, m oth erboard ch ip set, Su p er I/ O ch ip , BIOS, m em ory m od u les, vid eo ch ip set, an d variou s d isk con troller, SCSI bu s in terface, n etwork in terface, an d oth er ch ip s u sed th rou gh ou t th e system . Th e system - an d com p on en t-level d ocu m en tation is essen tial for even th e m ost basic trou blesh ootin g an d u p grad in g tasks. More tech n ical literatu re, su ch as th e ch ip - an d ch ip set-level d ocu m en tation , is p robably n ecessary on ly for software an d h ard ware d evelop ers wh o h ave m ore sp ecial req u irem en ts. However, if you are like m e an d really wan t to kn ow as m u ch abou t a system as p ossible, you will fin d th at h avin g th e ch ip - an d ch ip set-level d ocu m en tation can give you in sigh ts an d in form ation abou t a system you sim p ly can ’t get oth erwise. Th is section will exam in e all th is d ocu m en tation an d , m ost im p ortan tly, exp lain h ow to get it! Basic Syst em Docum ent at ion W h en you p u rch ase a com p lete system , it sh ou ld in clu d e a basic set of d ocu m en tation . W h at you actu ally get will vary wid ely, d ep en d in g on wh at typ e of system you get an d wh o p u t it togeth er. Nam e-bran d m an u factu rers su ch as IBM, Com p aq , Hewlett-Packard , Tosh iba, Packard Bell, an d oth ers will alm ost certain ly in clu d e cu stom u ser-level m an u als th ey h ave d evelop ed sp ecifically for each system th ey sell. Th ese m an u als are often very basic an d con tain on ly en ou gh in form ation for basic system setu p , in stallation , an d m in or trou blesh ootin g. Most of th e bigger n am e m an u factu rers wh o d esign an d m an u factu re th eir own m oth erboard s h ave m u ch m ore tech n ical d ocu m en tation available. For exam p le, IBM, HP, Tosh iba, an d Com p aq h ave available tech n ical referen ce an d service m an u als for th eir system s th at con tain m u ch m ore in form ation th an th e books th at com e free with th eir system s. Th ese tech n ical referen ce m an u als con tain d etailed in form ation abou t th e com p on en ts u sed in th e system —in form ation th at wou ld be u sefu l to tech n ician s or sop h isticated u sers wish in g to kn ow m ore d etails. Service m an u als con tain d etailed in stru ction s on system d isassem bly an d reassem bly, an d trou blesh ootin g flowch arts, p roblem -solvin g gu id es, an d a com p lete p arts listin g. Service m an u als are p articu larly u sefu l for lap top an d n otebook com p u ters, wh ere th e d isassem bly an d reassem bly is often n ot in tu itive an d wh ere virtu ally all th e p arts are cu stom . You sh ou ld con tact th e m an u factu rer or a m an u factu rer-au th orized service cen ter to fin d ou t abou t an y service or tech n ical referen ce d ocu m en tation th at m igh t be available.

M anuals (Documentation)

Com p an ies wh o assem ble or bu ild system s ou t of in d u stry-stan d ard com p on en ts su ch as m ost of th e well-kn own m ail-ord er bran d s m ay eith er p rod u ce th eir own d ocu m en tation or sim p ly in clu d e th e d ocu m en tation th at is su p p lied with th e com p on en ts th ey in stall in th eir system s. Most of th e larger system assem blers, su ch as Gateway, Dell, Micron , Mid west Micro, Qu an tex, an d oth ers, will also h ave th eir own cu stom -p rod u ced d ocu m en tation for th e m ain system u n it, an d m ay even h ave cu stom m an u als for m an y of th e in d ivid u al system com p on en ts. Th is typ e of d ocu m en tation is u sefu l for p eop le settin g u p a system for th e first tim e or for p erform in g sim p le u p grad es, bu t it often lacks th e d etailed tech n ical referen ce in form ation n eed ed by som ebod y wh o m igh t be trou blesh ootin g th e system or u p grad in g it beyon d wh at th e m an u factu rer or assem bler h ad origin ally in ten d ed . In th at case, you are better off with an y of th e OEM com p on en t m an u als th at are available d irectly from th e com p on en t or p erip h eral m an u factu rers th em selves. Most of th e sm aller system assem blers will forego an y cu stom -p rod u ced system d ocu m en tation an d sim p ly in clu d e th e com p on en t-level m an u als for th e com p on en ts th ey are in clu d in g in th e assem bled system . For exam p le, if an Asu s m oth erboard an d STB vid eo card were in clu d ed in a p articu lar system , th e m an u als from Asu s an d STB th at origin ally cam e with th ose p rod u cts wou ld be in clu d ed with th e assem bled system .

Get t ing Docum ent at ion from an Assem bler Some system assemblers like to keep the component documentation and not include it with the systems they build. This forces the purchaser of the systems to go back to the assembler for any support or technical information. It also tends to make the purchaser believe that the assembler actually manufactured the system rather than simply assembling it using off-the-shelf components. In other cases, system assemblers use special OEM versions of products that come in plain white boxes with little or no documentation. In that case, the system assembler is expected to provide the documentation in their custom manual. If you get the generic OEM product versions with your system, I would recommend contacting the actual OEM component manufacturer for more detailed and specific documentation.

Th e stan d ard m an u als in clu d ed with m ost system com p on en ts an d p erip h erals con tain basic in stru ction s for system setu p , op eration , testin g, relocation , an d op tion in stallation . Som e sort of basic d iagn ostics d isk (som etim es called a Diagnostics and Setup or Reference Disk) n orm ally is in clu d ed with a system as well. Often th e d iagn ostics are sim p ly a cu stom -labeled version of a com m on ly available com m ercial d iagn ostic p rogram .

Tip M ost system vendors and equipment manufacturers have jumper settings and manuals available on their Web sites in downloadable form. Appendix B, “ Useful Hardware Web Sites,” contains a list of vendors and their Web sites.

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Com ponent and Peripheral Docum ent at ion It is a well-kn own fact th at m an y system s sold tod ay are n ot really m an u factu red as a cu stom u n it by a sin gle com p an y bu t in stead are assem bled ou t of stan d ard off-th e-sh elf com p on en ts th at are available on th e op en m arket. In fact, I n orm ally recom m en d th at p eop le p u rch ase exactly th at typ e of system , becau se all th e com p on en ts con form to kn own stan d ard s an d can easily be rep laced or u p grad ed later. Even p rop rietary m an u factu red system s su ch as IBM, Com p aq , Hewlett-Packard , Packard Bell, an d oth ers u se at least som e off-th e-sh elf stan d ard com p on en ts (d isk d rives, for exam p le). To fu lly d ocu m en t a system , I recom m en d you take an in ven tory of th e stan d ard com p on en ts u sed an d th en collect all th e OEM d ocu m en tation or p rod u ct m an u als for th em . Th is p rocess is sim p le; wh en I am su p p ortin g a given system , I first d isassem ble it an d write d own all th e in form ation on each of th e com p on en ts in sid e. Som etim es, you will n eed to d o a little m ore in vestigatin g or even ask th e com p an y th at assem bled th e system exactly wh at com p on en ts th ey in clu d ed . Most com p on en ts, su ch as h ard d isks, CDROM d rives, vid eo card s, sou n d card s, n etwork card s, an d m ore, are p retty easy to id en tify. Som ewh ere on th e d evice or card th ere sh ou ld be a label in d icatin g at least th e m an u factu rer an d u su ally also th e m od el n u m ber. From th is, you can look u p th e m an u factu rer in th e ven d or listin g in Ap p en d ix A of th is book. Usin g th at in form ation , you can con tact th e com p an y via telep h on e, fax, or In tern et W eb site to obtain th e com p lete d ocu m en tation on th eir p rod u cts. If you are ru n n in g a fu lly Plu g-an d -Play-com p atible op eratin g system su ch as W in d ows 95/ 98 or W in d ows NT 5.0, you can fin d ou t th e m an u factu rers an d m od el n u m bers of m an y of th e d evices in you r system by u sin g th e Device Man ager p rogram . Moth erboard s can be tricky to id en tify becau se n ot all m an u factu rers m ark th em clearly. In fact, th e largest m an u factu rer of m oth erboard s, In tel, d oes n ot m ark its board s with eith er th e n am e or th e m od el n u m ber! Th is is becau se th e m ajor system assem blers wh o u se th e board s (Gateway, Dell, Micron , an d m an y oth ers) d on ’t really wan t p eop le to kn ow wh ere th e board origin ally cam e from . In som e cases, th e system assem bler will even stam p th eir own n am e on th e board , even th ou gh th ey d id n ot m an u factu re it. If th ere are n o m oth erboard m an u factu rer m arkin gs, you sh ou ld con tact th e com p an y th at sold you th e com p u ter to ask th em exactly wh at m oth erboard you h ave. I wou ld n ot even con sid er p u rch asin g a n ew system u n less I kn ew exactly wh ose m oth erboard was bein g in clu d ed an d exactly wh at m od el it was. Don ’t be afraid to ask th e system assem bler com p an y exactly wh at m oth erboard or oth er com p on en ts th ey are in stallin g in th e system s th ey sell. If th ey can ’t or won ’t an swer, you m ay be better off p u rch asin g from a d ifferen t com p an y in th e fu tu re. If th e com p an y wh o sold th e system is n o lon ger available or can n ot h elp , ch eck th e p ap erwork th at cam e with th e system . Som etim es th ere are clu es in th e origin al p ap erwork th at m igh t in d icate wh at m oth er-board you r system in clu d es. Most of th e p op u lar m oth erboard m an u factu rers are listed in th e ven d or list in Ap p en d ix A.

M anuals (Documentation)

Th e Micro Hou se CD in clu d ed with th is book h as a very u sefu l referen ce to over 150 com m on PC m oth erboard s. Part of th e Micro Hou se Su p p ort Sou rce for Hard ware p rod u ct, th is referen ce h as sp ecification s, ju m p er settin gs, m em ory con figu ration s, an d sch em atics for som e of th e m ost p op u lar 486, Pen tiu m , Pen tiu m Pro, an d Pen tiu m II m oth erboard s available. Th ese 150 m oth erboard s cover m an y of th e system s in u se tod ay. Man y of th e m oth erboard s are from In tel, an d m an y m ore are from m ajor system ven d ors su ch as IMB, Hewlett-Packard , an d Com p aq . As a last resort, you m igh t be able to id en tify you r board by com p arin g it to th ose sh own in th is referen ce. Th e version of Su p p ort Sou rce for Hard ware in clu d ed on th e CD also in clu d es d ocu m en tation on h u n d red s of d rives, d rive con trollers, NICs, an d m od em s.

Not e Every electronic component in your computer is required to have an FCC ID number. If you are having trouble determining the original manufacturer of a component, use the FCC ID locator function of the M icro House Support Source product on the CD to look up the FCC ID number and find the name of the manufacturer.

As an exam p le, on e system I worked on is a Gateway P6 (Pen tiu m Pro) 200MHz system th at in clu d ed th e followin g in d u stry-stan d ard com p on en ts: Moth erboard :

In tel VS440FX “Ven u s”

Vid eo Card :

STB Velocity 3D

Hard Disk:

Qu an tu m Fireball TM3840A

Flop p y Disk Drive:

Pan ason ic JU-256

CD-ROM Drive:

Mitsu m i FX120

Most of th e larger system assem blers like Gateway, Dell, Micron , an d oth ers h ave been u sin g In tel m oth erboard s. Most m oth erboard s tod ay u se In tel p rocessors an d ch ip sets, bu t som e p eop le m ay n ot be aware th at In tel m akes com p lete PC m oth erboard s, as well. Even so, Gateway d id n ot in clu d e th e actu al In tel m oth erboard or oth er com p on en t m an u als bu t in stead in clu d ed th eir own cu stom m an u als for th e m oth erboard , vid eo card , h ard d isk, an d CD-ROM d rive. By con tactin g th e in d ivid u al com p an ies d irectly over th e In tern et an d via th e telep h on e, I was able to obtain m ore d etailed d ocu m en tation on all th ese p rod u cts. Man y tim es, th e OEM d ocu m en tation or p rod u ct m an u als can be d own load ed d irectly from th e resp ective com p an ies’ W eb sites, often in th e form of Ad obe Acrobat .PDF files, wh ich you can read with th e Acrobat read er available for free d own load in g from Ad obe.

Not e Not all these manuals are available online, and even if they are, it is still nice to have the printed manuals or datasheets in your documentation library for future reference.

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Chip and Chipset Docum ent at ion If you really wan t th e u ltim ate in d ocu m en tation for you r system , I h igh ly recom m en d gettin g th e d ocu m en tation for th e variou s ch ip s an d ch ip sets in you r system . Th is wou ld in clu d e sp ecific m an u als for each of th e m ajor ch ip -level com p on en ts in th e system — su ch as th e p rocessor, m oth erboard ch ip set, BIOS, Su p er I/ O ch ip set, an d so on . Before you can get th is d ocu m en tation , you m u st first id en tify all th e relevan t ch ip s an d ch ip sets in you r system . Th e p rocess is relatively sim p le. Look at th e d ocu m en tation for each m ajor com p on en t, esp ecially th e m oth erboard . Th e OEM m oth erboard d ocu m en tation sh ou ld tell you wh ich ch ip set is u sed on th e board , wh ich p rocessors are su p p orted , an d wh ich Su p er I/ O ch ip is u sed . From th e OEM d ocu m en tation you h ave on you r system com p on en ts, you sh ou ld be able to fin d ou t wh at th e followin g m ajor ch ip an d ch ip sets are: Processor Moth erboard Ch ip set ROM BIOS Su p er I/ O Ch ip Vid eo Ch ip set If you r m oth erboard h as an in tegrated vid eo card , th e vid eo ch ip set typ e will be listed th ere also. If you h ave a sep arate vid eo card , look in th e vid eo card m an u al, wh ich sh ou ld clearly id en tify th e vid eo ch ip set u sed . Th e m ost im p ortan t ch ip s you will wan t to id en tify are on th e m oth erboard . Th e first th in g you wou ld wan t to id en tify is th e p rocessor. Th is sh ou ld be relatively easy; m ost PC system s u se In tel p rocessors. A sm all p ercen tage of system s u se AMD or Cyrix p rocessors, or version s of th ese p rocessors sold u n d er oth er n am es. Th e d ocu m en tation th at com es with th e system will n orm ally id en tify wh ich bran d of p rocessor you h ave an d wh ich m od el an d sp eed it is. If you aren ’t su re wh at p rocessor is in th e system , software p rogram s su ch as th e MSD (Microsoft Diagn ostics) p rogram can tell you . It’s in clu d ed with W in d ows 3.1, th e System Con trol Pan el in W in d ows 9x, or a system d iagn ostic you p u rch ase, su ch as th e Norton Utilities. Com m ercial u tilities like th e Norton Utilities can give you m ore d etailed in form ation abou t you r p rocessor, often in clu d in g th e sp eed it is ru n n in g at an d oth er p ertin en t in fo, su ch as wh eth er it su p p orts MMX in stru ction s or n ot. Norm ally, th e p rocessor is th e largest ch ip on th e m oth erboard , an d can often be id en tified by sim p ly read in g th e in form ation stam p ed on it. In som e cases, th e p rocessor will h ave a h eat sin k or fan attach ed to th e top . In th is case, you m ay h ave to eith er rem ove th e h eat sin k or fan to read th e in form ation stam p ed on top of th e ch ip , or sim p ly rem ove th e en tire p rocessor an d h eat sin k or fan assem bly to read th e in form ation stam p ed on th e bottom of th e ch ip .

M anuals (Documentation)

Not e You should check to see that the processor in your system is really rated to run at the speed your system is set for. M any of the smaller system assemblers have been installing overclocked CPUs in their systems. For example, they might have sold you a 266M Hz system but only have a 233M Hz processor installed. The only way to verify the actual chip rating is to check the chip manufacturer markings stamped or printed on the chip. Some vendors have even resorted to wiping off the original markings and remarking the chips at a higher speed, or carefully placing an official-looking sticker over the original marks. Unfortunately, these remarked chips can be difficult to spot for the less experienced. These types of scams are one reason for recommending the bigger name-brand system assemblers. Intel has more recently been building overclock protection circuitry into their chips that is designed to prevent this.

Th e m oth erboard ch ip set typ e can be d ifficu lt for software to d eterm in e, so you will n orm ally h ave to fin d ou t wh ich ch ip set you h ave from th e m oth erboard d ocu m en tation or by firsth an d in sp ection . Th e m oth erboard ch ip set u su ally con sists of two or m ore large ch ip s on th e board ; h owever, th ere are ch ip sets th at u se an ywh ere from on e to six ch ip s. Gen erally, each ch ip in th e set will h ave a p art n u m ber stam p ed on it, bu t th e ch ip set will be n am ed after th e m ain ch ip . Th e Pen tiu m Pro board I m en tion ed h ad two ch ip s labeled 82441FX an d 82442FX; th ese two ch ip s are called th e North Bridge or p rim ary com p on en ts of th e ch ip set. Th ere was also an 82371SB South Bridge ch ip th at is also called th e PIIX3 (PCI/ IDE/ ISA eXcelerator). All th ree ch ip s are a p art of wh at In tel calls th e 440FX chipset. Most of th eir n ewer ch ip sets su ch as th e 440LX an d 440BX, con sist of on ly two ch ip s—on e for th e North Brid ge an d on e for th e Sou th Brid ge. √√ See “ Chipsets,” p. 183

Fin d in g ou t th e m an u factu rer of th e m oth erboard BIOS is easy; th at is n orm ally fou n d in th e m oth erboard m an u al. It is also n orm ally d isp layed , alon g with th e exact version n u m ber you h ave, every tim e you p ower th e system on . Most system s tod ay u se an AMI, Award , or Ph oen ix BIOS, bu t th ere are several oth er m an u factu rers as well. Virtu ally all m oth erboard s bu ilt in th e ’90s an d later in clu d e a sp ecial in terface ch ip called a Su p er I/ O ch ip . Th is is a sin gle-ch ip d evice th at n orm ally in clu d es th e followin g com p on en ts: ■ Prim ary an d secon d ary IDE h ost ad ap ters ■ Flop p y d isk d rive con troller ■ Two serial p orts ■ On e p arallel p ort Man y of th e m ore recen t Su p er I/ O ch ip s d o n ot in clu d e th e IDE h ost ad ap ters, su ch as th e Nation al Sem icon d u ctor 87308 or 87309 u sed in th e In tel Pen tiu m Pro an d Pen tiu m II m oth erboard s. Th at is becau se th e IDE p orts are alread y bu ilt in to th e variou s In tel 82371 Sou th Brid ge ch ip s. Th e Nation al Sem icon d u ctor Su p er I/ O ch ip s also in clu d e an

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8042-style keyboard an d m ou se con troller. Som e Su p er I/ O ch ip s in clu d e an MC146818style real-tim e clock with n on volatile CMOS RAM, alth ou gh th at is also n orm ally a p art of th e In tel ch ip set Sou th Brid ge. Oth er Su p er I/ O ch ip s m ay in clu d e a gam e (joystick) in terface as well. Obtain in g th e d ocu m en tation for you r p articu lar Su p er I/ O ch ip will, of cou rse, tell you exactly wh at its cap abilities are. An oth er im p ortan t ch ip set in a system is th e video chipset. Th is is n orm ally fou n d on th e vid eo card , or on th e m oth erboard if th e m oth erboard h as bu ilt-in vid eo. Th e OEM vid eo card or m oth erboard d ocu m en tation sh ou ld tell you exactly wh ich vid eo ch ip set you h ave. If n ot, you can u se free software su ch as MSD or com m ercial p rogram s su ch as Norton Utilities to id en tify wh ich ch ip set you h ave with ou t even op en in g u p th e case. A last resort wou ld be to op en th e system an d read th e p art n u m ber righ t off of th e vid eo ch ip set, wh ich is u su ally th e largest ch ip on th e vid eo card . Usin g a Pen tiu m Pro 200MHz system as an exam p le, I fou n d it con tain ed th e followin g m ain ch ip an d ch ip set com p on en ts: Processor:

In tel Pen tiu m Pro

Moth erboard Ch ip set:

In tel 440FX “Natom a”

ROM BIOS:

AMI

Su p er I/ O Ch ip :

Nation al Sem icon d u ctor PC87308

Vid eo Ch ip set:

S3 In c. ViRGE/ VX

Note th at th is p articu lar m oth erboard d id n ot h ave th e vid eo in tegrated , so th e vid eo ch ip set was on th e vid eo card . From th is d ocu m en tation , I learn ed abou t th e cap ability to in crease th e clock m u ltip lier settin g on th e m oth erboard to an oth erwise u n d ocu m en ted 3.5x, wh ich resu lted in ru n n in g th e Pen tiu m Pro 200 ch ip at 233MHz! I was also able to get m ore in form ation on th e variou s serial, p arallel, an d d isk con trollers con tain ed in th e Su p er I/ O ch ip , an d I learn ed m ore abou t th e ad van ced CMOS settin gs in th e BIOS Setu p rou tin es. For exam p le, I often get q u estion s abou t th e Ad van ced CMOS settin gs. Most p eop le assu m e th at th ese settin gs are d escribed in th eir ROM BIOS d ocu m en tation , becau se th e ROM-based CMOS Setu p p rogram in th eir system con trols th ese settin gs. If you con tact th e BIOS m an u factu rer or read th e BIOS d ocu m en tation , you will q u ickly fin d ou t th at th e ROM BIOS m an u factu rer kn ows little or n oth in g abou t th ese settin gs. In fact, th ese settin gs actu ally h ave little or n oth in g to d o with th e p articu lar ROM BIOS u sed an d everyth in g to d o with th e p articu lar m oth erboard chipset u sed . You can fin d d escrip tion s of all th ese settin gs in th e d ocu m en tation for you r m oth erboard ch ip set, wh ich can be obtain ed from th e ch ip set m an u factu rer.

M agazines

M anufact urer Syst em -Specific Docum ent at ion If you r system is from a n am e-bran d m an u factu rer—su ch as IBM, Com p aq , HewlettPackard , Tosh iba, an d oth ers—th ere m ay be a wealth of in form ation available in m an u factu rer-sp ecific m an u als an d d ocu m en tation . Becau se of th e sp ecific n atu re of th e in form ation in th ese typ es of m an u als, you m ost likely will h ave to obtain it from th e m an u factu rer of th e system . Large m an u factu rers su ch as In tel, IBM, Com p aq , Hewlett-Packard , an d oth ers both m an u factu re th eir own com p on en ts an d p u rch ase com p on en ts from oth er sou rces. Man y of th ese m an u factu rers also m ake available com p lete libraries of tech n ical d ocu m en tation for th eir system s. IBM, HP, an d Com p aq also m ake th eir tech n ical libraries available in CD-ROM version s, wh ich are n ot on ly very com p reh en sive bu t also very con ven ien t an d easy to search . Th ese CD-ROMs con tain d etailed in form ation abou t PC system s an d p erip h erals from th ese com p an ies. If you h ave an IBM, Com p aq , or HP system , con tact th e m an u factu rer to see abou t ord erin g th eir CD-ROM referen ce library. Norm ally, th ese are offered as su bscrip tion s for $250 or so an n u ally. Th e p rocess of obtain in g oth er m an u factu rers’ m an u als m ay (or m ay n ot) be easy. Most large com p an ies ru n resp on sible service an d su p p ort op eration s th at p rovid e tech n ical d ocu m en tation . Oth er com p an ies eith er d o n ot h ave or are u n willin g to p art with su ch d ocu m en tation , in an effort to p rotect th eir service d ep artm en ts (an d th eir d ealers’ service d ep artm en ts) from com p etition . Con tact th e m an u factu rer d irectly; th e m an u factu rer can d irect you to th e correct d ep artm en t so th at you can in q u ire abou t th is in form ation . In form ation on h ow to con tact m ost PC m an u factu rers can be fou n d in th e ven d or listin g in Ap p en d ix A of th is book.

M agazines Th e n ext sou rce of in form ation , m agazin es, is on e of th e best sou rces of u p -to-d ate reviews an d tech n ical d ata. Featu red are “bu g fixes,” p roblem alerts, an d gen eral in d u stry n ews. Keep in g a p rin ted book u p -to-d ate with th e latest even ts in th e com p u ter in d u stry is extrem ely d ifficu lt or even im p ossible. Th in gs m ove so fast th at th e m agazin es th em selves barely keep p ace. I su bscribe to m ost of th e m ajor com p u ter m agazin es an d am h ard -p ressed to p ick on e as th e best. Th ey all are im p ortan t to m e, an d each on e p rovid es d ifferen t in form ation or th e sam e in form ation with a d ifferen t an gle or twist. Alth ou gh th e reviews u su ally leave m e wan tin g, th e m agazin es still are a valu able way to at least h ear abou t p rod u cts, m ost of wh ich I n ever wou ld h ave kn own abou t with ou t th e m agazin es’ rep orts an d ad vertisem en ts. Most com p u ter m agazin es are also available on CDROM, wh ich can ease th e fran tic search for a sp ecific p iece of in form ation you rem em ber read in g abou t. If CD-ROM version s are too m u ch for you r n eed s, be aware th at you can access an d search m ost m ajor m agazin es on th e In tern et. Th is cap ability is valu able wh en you wan t to research everyth in g you can abou t a sp ecific su bject. On e of th e best kep t secrets in th e com p u ter in d u stry is th e excellen t trad e m agazin es th at offer free su bscrip tion s. Alth ou gh m an y of th ese m agazin es are d irected toward th e wh olesale or tech n ical en d of th e in d u stry, I like to su bscribe to th em . Som e of m y favorite m agazin es in th is category in clu d e th e followin g:

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■ Com puter Design ■ Com puter Hotline

■ Electronic News

■ Com puter Reseller News

■ Electronic Products

■ Electronic Design News

■ Processor

■ Electronic Buyer’s News

■ Service News

■ Electronic Engineering Tim es

■ Test and Measurem ent W orld

Most of th ese m agazin es offer free su bscrip tion s to an yon e wh o q u alifies. Aim ed at p eop le in th e com p u ter an d electron ics in d u stries, th ese m agazin es offer a m u ch greater d ep th an d bread th of tech n ical an d in d u stry in form ation th an th e m ore “p u blic” m agazin es th at m ost p eop le are fam iliar with . You ’ll fin d th ese an d oth er recom m en d ed m agazin es in th e ven d or list in Ap p en d ix A.

Online Resources W ith a m od em , you can tie in to everyth in g from th e In tern et (W orld W id e W eb) to local electron ic bu lletin board system s (BBSs) to m ajor in form ation n etworks su ch as Com p u Serve an d AOL. Man y h ard ware an d software com p an ies offer tech n ical su p p ort an d even software u p grad es over th e In tern et. Th rou gh th e In tern et an d oth er on lin e resou rces, you can reach com p u ter en th u siasts an d tech n ical-su p p ort p eop le from variou s organ ization s, an d exp erts in virtu ally all areas of com p u ter h ard ware an d software. You can also collect u sefu l u tility an d h elp p rogram s th at can m ake you r job m u ch easier. Th e world of p u blic-d om ain an d u ser-su p p orted software awaits, as d o m ore tech n ical in form ation an d related exp erien ces th an you can im agin e. Ap p en d ix A in clu d es n ot on ly th e n am e, ad d ress, an d voice p h on e n u m ber for th e com p an y, bu t also th e In tern et ad d resses (W eb sites) or BBS n u m bers, wh ere available. If you n eed m ore in form ation on a ven d or’s p rod u cts, or n eed tech n ical su p p ort, try u sin g th e ven d or’s on lin e con n ection . Man y com p an ies tod ay p rovid e on lin e services to facilitate obtain in g u p d ated software or d river files th at you can d own load q u ickly an d easily. W h en a ven d or p rovid es an on lin e con n ection , I con sid er th at service a m ajor ad van tage in com p arison to oth er ven d ors wh o d o n ot p rovid e su ch a service. Usin g ven d orp rovid ed on lin e con n ection s eith er th rou gh th e In tern et or via a p rivate BBS or even Com p u Serve h as saved m e m on ey an d cou n tless h ou rs of tim e. In fact, th e In tern et is p robably th e m ost efficien t m eth od of reach in g m e. My e-m ail ad d ress is sc o t t m u e l l e r@c o m p u se rv e .c o m . If you h ave q u estion s or ju st a com m en t or u sefu l in form ation you th in k I m igh t be in terested in , sen d m e a m essage. Becau se of th e extra step s in p rocessin g, m y stan d ard m ail can get backed u p , an d it can take m e q u ite a wh ile to an swer a regu lar p ostal letter. Electron ic m ail, h owever, in volves fewer step s for m e to sen d , an d always seem s to h ave a h igh er p riority. If you d o sen d a regu lar letter, be su re to in clu d e a SASE (Self-Ad d ressed , Stam p ed En velop e) so I will be able to rep ly.

M achines

Sem inars Pu blic an d p rivate sem in ars are a very valu able resou rce. Th is is, in fact, h ow I got m y start writin g; I teach PC h ard ware sem in ars, an d I h ad to write a cou rse book to go alon g with th e sem in ars! Sem in ars are an excellen t way to h ave in form ation exp lain ed in p erson , often fillin g in gap s an d ad d in g visu al in form ation th at isn ’t n early as easy to p resen t in a p rin ted book alon e. Sem in ars com e in two m ain typ es, p u blic an d on -site. A p u blic cou rse is ju st th at, offered to th e gen eral p u blic so an ybod y can sign u p an d atten d . Th ese are m ost often con d u cted in h otels or at sp ecific train in g facilities arou n d th e cou n try. On -site sem in ars are con d u cted at a p articu lar com p an y’s location an d on ly for em p loyees of th at com p an y. Th ese sem in ars are often cu stom ized with th at com p an y’s in d ivid u al n eed s in m in d .

M achines Th e term m achines refers to th e system s th em selves—th at is, h an d s-on exp erien ce. Actu al exp erien ce on live system s is on e of m y best sou rces of in form ation . For exam p le, su p p ose th at I n eed to an swer th e q u estion “W ill th e XYZ SCSI h ost ad ap ter work with th e ABC tap e d rive?” Th e an swer is as sim p le as p lu ggin g everyth in g in an d flip p in g th e switch . (Sim p le to talk abou t, th at is; actu al testin g can take q u ite a bit of tim e!) Seriou sly, exp erim en tin g with an d observin g ru n n in g system s are som e of th e best learn in g tools at you r d isp osal. I recom m en d th at you try everyth in g; rarely will an yth in g you try h arm th e eq u ip m en t. Harm in g valu able d ata is d efin itely p ossible, if n ot likely, h owever, so m ake regu lar backu p s as in su ran ce. You sh ou ld n ot u se a system you d ep en d on for d ay-to-d ay op eration s as an exp erim en tal system ; if p ossible, u se a secon d ary m ach in e. Peop le som etim es are relu ctan t to exp erim en t with system s th at cost a lot of m on ey, bu t m u ch can be learn ed th rou gh d irect tests an d stu d ies of th e system . I often fin d th at ven d or claim s abou t a p rod u ct are som ewh at m islead in g wh en I actu ally in stall it an d ru n som e tests. If you are u n su re th at som eth in g will really work, m ake su re th at th e com p an y h as a retu rn p olicy th at allows you to retu rn th e item for a refu n d if it d oes n ot m eet you r exp ectation s. Su p p ort p eop le in larger com p an ies h ave access to q u an tities of h ard ware an d software I can on ly d ream abou t. Som e larger com p an ies h ave toy stores, wh ere th ey regu larly p u rch ase eq u ip m en t solely for evalu ation an d testin g. Dealers an d m an u factu rers also h ave access to an en orm ou s variety of eq u ip m en t. If you are in th is p osition , take ad van tage of th is access to eq u ip m en t, an d learn from th is resou rce. W h en n ew system s are p u rch ased , take n otes on th eir con stru ction an d com p on en ts. Every tim e I en cou n ter a system I h ave n ot p reviou sly worked with , I im m ed iately op en it u p an d start takin g n otes. I wan t to kn ow th e m ake an d m od el of all th e in tern al com p on en ts, su ch as d isk d rives, p ower su p p lies, an d m oth erboard s. As far as m oth erboard s are con cern ed , I like to record th e n u m bers of th e p rim ary IC ch ip s on th e board , su ch as th e p rocessor (of cou rse), in tegrated ch ip sets, flop p y d rive con troller ch ip s, keyboard

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con troller ch ip s, vid eo ch ip sets, an d an y oth er m ajor ch ip s on th e board . By kn owin g wh ich ch ip set you r system u ses, you can often in fer oth er cap abilities of th e system , su ch as en h an ced setu p or con figu ration cap abilities. I like to kn ow wh ich BIOS version is in th e system , an d I even m ake a cop y of th e BIOS on d isk for backu p an d fu rth er stu d y p u rp oses. I wan t to kn ow th e h ard d rive tables from th e BIOS, an d an y oth er p articu lars in volved in settin g u p an d in stallin g a system . W rite d own th e typ e of battery a system u ses so th at you can obtain sp ares. Note an y u n iq u e brackets or con stru ction tech n iq u es su ch as sp ecialized h ard ware (Torx screws, for exam p le) so th at you can be p rep ared for servicin g th e system later. Som e p rogram s h ave been d esign ed to h elp you m ain tain an in ven tory of system s an d com p on en ts, bu t I fin d th at th ese fall far sh ort of th e d etail I am talkin g abou t h ere. Th is d iscu ssion brin gs u p a p et p eeve of m in e. Noth in g bu rn s m e u p as m u ch as read in g a review of com p u ter system s in a m ajor m agazin e, in wh ich reviewers test system s an d p rod u ce ben ch m ark an d p erform an ce resu lts for, let’s say, th e h ard d isks or vid eo d isp lays in a system . Th en , th ey d o n ot op en u p th e m ach in es an d tell m e (an d th e world ) exactly wh ich com p on en ts th e m an u factu rer of th e system is u sin g! I wan t to kn ow exactly wh ich d isk con troller, h ard d rive, BIOS, m oth erboard , vid eo ad ap ter, an d so on are fou n d in each system . W ith ou t th is in form ation , th eir review an d ben ch m ark tests are u seless to m e. Th en th ese reviewers ru n a test of d isk p erform an ce between two system s with th e sam e d isk con troller an d d rives an d say (with a straigh t face) th at th e on e th at cam e ou t a few m illisecon d s ah ead of th e oth er win s th e test. W ith th e statistical variation th at n orm ally occu rs in an y m an u factu red com p on en ts, th ese resu lts are m ean in gless. Th e p oin t is p erh ap s to be very carefu l of wh om you tru st in a n orm al m agazin e review. If it tells m e exactly wh ich com p on en ts were tested , I can d raw m y own con clu sion s an d even m ake com p arison s to oth er system s n ot in clu d ed in th at review. You can always search th e Net for u n biased reviews written by in d ivid u als abou t a given p rod u ct. Som e p rod u cts with p oor su p p ort or reliability p roblem s often h ave an tip rod u ct W eb sites p u t u p by d isgru n tled in d ivid u als. Alth ou gh on e p erson ’s exp erien ce with a p rod u ct m ay n ot be in d icative of th e n orm al p erform an ce, wh en you see h u n d red s of m essages or sites com p lain in g abou t som eth in g, you u su ally get th e id ea. Sim ilarly, you m ay also fin d great p raise for a p rod u ct, or m essages in d icatin g h ow p eop le h ave fou n d u ses th at are ou t of th e ord in ary.

The Appendixes Th e ap p en d ixes p rovid e a collection of tech n ical in form ation , tables, ch arts, an d lists esp ecially u sefu l to p eop le in a com p u ter su p p ort, trou blesh ootin g, service, or u p grad in g role. W h eth er you ’re lookin g for th e m ean in g of a word in th e glossary, seekin g th e ad d ress an d p h on e n u m ber of a com p an y or ven d or in th e ven d or list, or search in g for an arcan e table n ot fou n d in th e n orm al ch ap ter text, you ’ll m ost likely fin d th e in form ation in th e ap p en d ixes.

CompTIA A+ Core Examination Objective M ap

Th e ap p en d ixes started ou t as a brief collection of essen tial in form ation bu t h ave grown in to a referen ce resou rce of th eir own .

Com pTIA A+ Core Exam inat ion Object ive M ap Com p TIA is th e organ ization th at sets th e objectives for th e A+ certification . As with m an y com p u tin g field s, earn in g you r certification can in crease you r job secu rity or in crease you r valu e to p rosp ective em p loyers. Com p TIA released a n ew set of exam objectives an d a n ew exam in Ju ly ’98. Th is n ew exam is u p d ated to slan t th e coverage m ore toward n ewer h ard ware an d n ewer op eratin g system s. If you aren ’t yet A+ certified , n ow is th e p erfect tim e to stu d y for an d p ass th e tests, as th e objectives are m ore relevan t th an ever before. Even if you are certified , an y em p loyer or p rosp ective em p loyer wou ld be im p ressed to see you recertify on th e n ew objectives. Th e A+ exam con sists of two p arts. Th e p art th at is m ost closely related to th e top ics in th is book is th e Core exam , wh ich m ostly covers h ard ware. To becom e A+ certified , you m u st also p ass th e DOS/ W in d ows Mod u le Exam in ation . Alth ou gh th is book d oes cover m an y of th e top ics tested by th e DOS/ W in d ows m od u le in th e cou rse of d iscu ssin g h ard ware, th is book d oes n ot p reten d to be a th orou gh referen ce to DOS or W in d ows, so th ose objectives are n ot listed h ere. I h igh ly recom m en d th e A+ Certification Training Guide p u blish ed by New Rid ers Pu blish in g (ISBN: 1-56205-896-7).

Tip The CD-ROM that comes with this book includes test preparation software with 150 questions to help you prepare for the A+ Core exam. These 150 questions are part of a larger test prep program from M arcraft. Their complete program covers both components of the A+ exam and contains over 900 sample questions. For more information about this program and a special discount offer for purchasers of this book, see the page describing it near the end of the book.

Th e Com p TIA organ ization h as establish ed th e followin g objectives for th e Core p ortion of th e A+ Certification exam in ation . 1.0 Inst allat ion, Configurat ion, and Upgrading Th is section ch allen ges th e test taker to id en tify, in stall, con figu re, an d u p grad e m icrocom p u ter m od u les an d p erip h erals. Establish ed p roced u res for system assem bly an d d isassem bly m u st be followed . Test elem en ts in clu d e th e ability to id en tify an d con figu re IRQs, DMAs, an d I/ O ad d resses, an d to p rop erly set con figu ration switch es an d ju m p ers. 1.1 Id en tify basic term s, con cep ts, an d fu n ction s of system m od u les, in clu d in g h ow each m od u le sh ou ld work d u rin g n orm al op eration . Exam p les of con cep ts an d m od u les in clu d e th e followin g:

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■ System board ■ Power su p p ly ■ CPU/ m icrop rocessor ■ Mem ory ■ Storage d evices ■ Mon itor ■ Mod em ■ Firm ware ■ Boot p rocess ■ BIOS ■ CMOS 1.2 Id en tify basic p roced u res for ad d in g an d rem ovin g field -rep laceable m od u les. Exam p les of m od u les in clu d e ■ System board ■ Power su p p ly ■ CPU/ m icrop rocessor ■ Mem ory ■ Storage d evices ■ In p u t d evices 1.3 Id en tify available IRQs, DMAs, an d I/ O ad d resses with p roced u res for con figu rin g th em for d evice in stallation . Exam p les in clu d e ■ Stan d ard IRQ settin gs ■ Mod em s ■ Flop p y d isk d rives ■ Hard d rives 1.4 Id en tify com m on p erip h eral p orts, associated cables, an d th eir con n ectors. Exam p les in clu d e ■ Cable typ es ■ Cable orien tation ■ Serial versu s p arallel ■ Pin con n ection s

CompTIA A+ Core Examination Objective M ap

Exam p les of con n ector typ es in clu d e ■ DB-9 ■ DB-25 ■ RJ-11 ■ BNC ■ RJ-45 ■ PS2/ Min i-DIN 1.5 Id en tify p rop er p roced u res for in stallin g an d con figu rin g IDE/ EIDE d evices. Exam p les in clu d e ■ Master/ slave ■ Devices p er ch an n el 1.6 Id en tify p rop er p roced u res for in stallin g an d con figu rin g SCSI d evices. Top ics in clu d e ■ Ad d ress/ term in ation con flicts ■ Cablin g ■ Typ es (stan d ard , wid e, fast, u ltra wid e) ■ In tern al versu s extern al ■ Switch an d ju m p er settin gs 1.7 Id en tify p rop er p roced u res for in stallin g an d con figu rin g p erip h eral d evices. Top ics in clu d e ■ Mon itor/ vid eo card ■ Mod em ■ Storage d evices 1.8 Id en tify p roced u res for u p grad in g BIOS. Top ics in clu d e ■ Meth od s for u p grad in g ■ W h en to u p grad e 1.9 Id en tify h ard ware m eth od s of system op tim ization an d wh en to u se th em . Exam p les in clu d e ■ Mem ory ■ Hard d rives ■ CPU/ m icrop rocessors ■ Cach e m em ory

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2.0 Diagnosing and Troubleshoot ing Th is item req u ires th e test taker to ap p ly kn owled ge relatin g to d iagn osin g an d trou blesh ootin g com m on m od u le p roblem s an d system m alfu n ction s. Th is in clu d es kn owled ge of th e sym p tom s relatin g to com m on p roblem s. 2.1 Id en tify com m on sym p tom s an d p roblem s associated with each m od u le an d h ow to trou blesh oot an d isolate th e p roblem s. Con ten ts m ay in clu d e ■ Processor/ m em ory sym p tom s ■ Keyboard s/ m ou se/ trackball/ p en / m icrop h on es/ tou ch p ad ■ Flop p y d rive failu res ■ Parallel p orts/ scan n ers/ tap e d rives ■ Hard d rives ■ Sou n d s card / au d io ■ Mon itor/ vid eo ■ Moth erboard s ■ Mod em s ■ BIOS ■ CMOS ■ Power su p p ly ■ Slot covers ■ POST au d ible/ visu al error cod es ■ Trou blesh ootin g tools; for exam p le, m u ltim eter 2.2 Id en tify basic trou blesh ootin g p roced u res an d good p ractices for elicitin g p roblem sym p tom s from cu stom ers. Top ics in clu d e ■ Trou blesh ootin g/ isolation / p roblem d eterm in ation ■ Determ in e wh eth er h ard ware or software p roblem Gath er in form ation from th e u ser regard in g ■ Cu stom er en viron m en t ■ Sym p tom s/ error cod es ■ Situ ation wh en th e p roblem occu rred 3.0 Safet y and Prevent ive M aint enance Th is section req u ires th e test taker to sh ow kn owled ge of safety an d p reven tive m ain ten an ce. W ith regard to safety, it in clu d es th e p oten tial h azard s to p erson n el an d eq u ip m en t wh en workin g with lasers, h igh -voltage eq u ip m en t, ESD (Electrostatic Disch arge),

CompTIA A+ Core Examination Objective M ap

an d item s th at req u ire sp ecial d isp osal p roced u res th at com p ly with en viron m en tal gu id elin es. W ith regard to p reven tive m ain ten an ce, th is in clu d es kn owled ge of p reven tive m ain ten an ce p rod u cts, p roced u res, en viron m en tal h azard s, an d p recau tion s wh en workin g on m icrocom p u ter system s. 3.1 Id en tify th e p u rp ose of variou s typ es of p reven tive m ain ten an ce p rod u cts an d p roced u res, an d wh en to u se or p erform th em . Exam p les in clu d e ■ Liq u id clean in g com p ou n d s ■ Typ es of m aterials to clean con tacts an d con n ection s ■ Vacu u m -ou t system s, p ower su p p lies, fan s 3.2 Id en tify p roced u res an d d evices for p rotectin g again st en viron m en tal h azard s. Exam p les in clu d e ■ UPS (u n in terru p tible p ower su p p ly)/ su p p ressors/ n oise filters/ p lu g strip s ■ Determ in in g th e sign s of p ower issu es ■ Prop er m eth od s of com p on en t storage for fu tu re u se 3.3 Id en tify th e p oten tial h azard s an d p rop er safety p roced u res relatin g to lasers an d h igh -voltage eq u ip m en t. Exam p les in clu d e ■ Lasers can cau se blin d n ess. ■ High -voltage eq u ip m en t can cau se electrocu tion ; for exam p le, p ower su p p ly/ CRT. 3.4 Id en tify item s th at req u ire sp ecial d isp osal p roced u res th at com p ly with en viron m en tal gu id elin es. Exam p les in clu d e ■ Batteries ■ Ton er kits/ cartrid ges ■ Ch em ical solven ts an d can s ■ CRTs ■ MSDS (Material Safety Data Sh eet) 3.5 Id en tify ESD (Electrostatic Disch arge) p recau tion s an d p roced u res, in clu d in g th e u se of ESD p rotection d evices. Exam p les in clu d e ■ W h at ESD can d o, an d h ow it m ay be ap p aren t or h id d en ■ Com m on ESD p rotection d evices ■ Situ ation s th at cou ld p resen t a d an ger or h azard 4.0 M ot herboard/ Processors/ M em ory Th is section req u ires th e test taker to d em on strate kn owled ge of sp ecific term in ology, an d facts, ways, an d m ean s of d ealin g with classification s, categories, an d p rin cip les of m oth erboard s, p rocessors, an d m em ory in m icrocom p u ter system s.

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4.1 Distin gu ish between th e p op u lar CPU ch ip s in term s of th eir basic ch aracteristics. Pop u lar CPU ch ip s in clu d e ■ Pop u lar CPU ch ip s Ch aracteristics in clu d e ■ Ph ysical size ■ Voltage ■ Sp eed s ■ On board cach e or n ot ■ Sockets ■ Nu m ber of p in s 4.2 Id en tify th e categories of RAM (Ran d om Access Mem ory) term in ology, th eir location s, an d p h ysical ch aracteristics. Term in ology in clu d es ■ EDO RAM (Exten d ed Data Ou tp u t RAM) ■ DRAM (Dyn am ic Ran d om Access Mem ory) ■ SRAM (Static RAM) ■ VRAM (Vid eo RAM) ■ W RAM (W in d ows Accelerator Card RAM) Location s an d p h ysical ch aracteristics in clu d e ■ Mem ory ban k ■ Mem ory ch ip s (8-bit, 16-bit, an d 32-bit) ■ SIMMS (Sin gle In lin e Mem ory Mod u le) ■ DIMMS (Du al In lin e Mem ory Mod u le) ■ Parity ch ip s versu s n on -p arity ch ip s 4.3 Id en tify th e m ost p op u lar typ e of m oth erboard s, th eir com p on en ts, an d th eir arch itectu re (for exam p le, bu s stru ctu res an d p ower su p p lies). Typ es of m oth erboard s in clu d e ■ AT (Fu ll an d Baby) ■ ATX Moth erboard com p on en ts in clu d e ■ Com m u n ication p orts ■ SIMM an d DIMM

CompTIA A+ Core Examination Objective M ap

■ Processor sockets ■ Extern al cach e m em ory (Level 2) Bu s arch itectu re in clu d es ■ ISA ■ EISA ■ PCI ■ USB (Un iversal Serial Bu s) ■ VESA local bu s (VL-BUS) ■ PC Card (PCMCIA) Basic com p atibility gu id elin es 4.4 Id en tify th e p u rp ose of CMOS (Com p lem en tary Metal-Oxid e Sem icon d u ctor), wh at it con tain s, an d h ow to ch an ge its basic p aram eters. Exam p les in clu d e ■ Prin ter p arallel p ort: Un id irection al/ bid irection al, d isable/ en able, ECP/ EPP ■ COM/ serial p ort: m em ory ad d ress, in terru p t req u est, d isable ■ Hard d rive: size an d d rive typ e ■ Flop p y d rive: en able/ d isable d rive or boot, sp eed , d en sity ■ Boot seq u en ce ■ Mem ory: p arity, n on -p arity ■ Date/ tim e ■ Password s 5.0 Print ers Th is d om ain req u ires kn owled ge of basic typ es of p rin ters, basic con cep ts, p rin ter com p on en ts, h ow th ey work, h ow th ey p rin t on to a p age, p ap er p ath , care an d service tech n iq u es, an d com m on p roblem s. 5.1 Id en tify basic con cep ts, p rin ter op eration s, p rin ter com p on en ts, an d field -rep laceable u n its in p rim ary p rin ter typ es. Typ es of p rin ters in clu d e ■ Laser ■ In kjet ■ Dot m atrix Pap er feed er m ech an ism s

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5.2 Id en tify care an d service tech n iq u es an d com m on p roblem s with p rim ary p rin ter typ es. Exam p les in clu d e ■ Feed an d ou tp u t ■ Errors ■ Pap er jam ■ Prin t q u ality ■ Safety p recau tion s ■ Preven tive m ain ten an ce 5.3 Id en tify th e typ es of p rin ter con n ection s an d con figu ration s. Top ics in clu d e ■ Parallel ■ Serial ■ Network 6.0 Port able Syst em s Th is section req u ires th e test taker to d em on strate kn owled ge of p ortable com p u ters an d th eir u n iq u e com p on en ts an d p roblem s. 6.1 Id en tify th e u n iq u e com p on en ts of p ortable system s an d th eir u n iq u e p roblem s. Exam p les in clu d e ■ Battery ■ LCD ■ AC ad ap ter ■ Dockin g station s ■ Hard d rive ■ Typ es I, II, III card s ■ Network card s ■ Mem ory 7.0 Basic Net w orking Th is section req u ires th e test taker to d em on strate kn owled ge of basic n etwork con cep ts an d term in ology, ability to d eterm in e wh eth er a com p u ter is n etworked , kn owled ge of p roced u res for swap p in g an d con figu rin g n etwork in terface card s, an d kn owled ge of th e ram ification s of rep airs wh en a com p u ter is n etworked . 7.1 Id en tify basic n etworkin g con cep ts, in clu d in g h ow a n etwork works. Exam p les in clu d e th e followin g:

In Conclusion

■ Network access ■ Protocol ■ Network In terface Card s ■ Fu ll d u p lexin g ■ Cablin g/ Twisted -Pair, Coaxial, Fiber-Op tic ■ W ays to n etwork a PC 7.2 Id en tify p roced u res for swap p in g an d con figu rin g n etwork in terface card s. 7.3 Id en tify ram ification s of rep airs on th e n etwork. Exam p les in clu d e ■ Red u ced ban d wid th ■ Loss of d ata ■ Network slowd own 8.0 Cust om er Sat isfact ion No on e can u n d erestim ate th e valu e an d im p ortan ce of cu stom er satisfaction , esp ecially p erson al com p u ter rep air tech n ician s wh o m u st d eal with cu stom ers wh o are often u n d er stress becau se th eir com p u ter h as crash ed . Th e Com p TIA A+ Core Exam h as several objectives d ealin g with cu stom er service. As im p ortan t as th is top ic is, it is n ot covered in th is book, wh ich is really abou t th e n u ts an d bolts of PC rep air.

In Conclusion Th is ed ition m arks a m ileston e in com p u ter book p u blish in g. Th is year m arks th e 10th an n iversary of th is book! Th is was th e first book of its kin d on th e m arket, an d it h as sin ce sp awn ed an en tire series of clon e books from oth er com p etitors, m an y with su rp risin gly sim ilar n am es. Desp ite th e sim ilar com p etitor books, th is is still th e lon gestru n n in g, best-sellin g, m ost p op u lar book of its kin d . Actu ally, th is book was p reviou sly p u blish ed as m y sem in ar m an u al for several years p rior to th is in carn ation , so it h as been arou n d in on e form or an oth er even lon ger th an th is an n iversary ed ition in d icates. No oth er book cu rren tly on th e m arket con tain s su ch a com p lete an d in form ative tech n ical referen ce, wh ich is on e reason wh y so m an y large com p an ies an d ed u cation al in stitu tion s h ave stan d ard ized on th is book for th eir tech n ician s an d stu d en ts. Th is book is cu rren tly bein g u sed as an official textbook for m an y corp orate an d college-level com p u ter train in g cou rses, as well as for m y own PC train in g sem in ars, for wh ich th e book was origin ally d esign ed . I’d like to p erson ally th an k all th e p eop le wh o h ave su p p orted th e book over th e years, esp ecially th ose wh o h ave written with com m en ts an d su ggestion s.

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I h op e th at Upgrading and Repairing PCs, Tenth Anniversary Edition, is ben eficial to you , an d I h op e th at you h ave en joyed read in g it as m u ch as I h ave en joyed writin g it over th e last 10 years. If you h ave q u estion s abou t th is book, or if you h ave id eas for fu tu re version s, I can be reach ed at th e followin g ad d ress: Scott Mu eller Mu eller Tech n ical Research 21 Sp rin g Lan e Barrin gton Hills, IL 60010-9009 Ph on e: (847) 854-6794 Fax: (847) 854-6795 E-m ail: sc o t t m u e l l e r@c o m p u se rv e .c o m W eb Ad d ress: h t t p :/ / w w w .m -t r.c o m Rem em ber th at th e best way to con tact m e is th rou gh e-m ail; tim e con strain ts n orm ally p reven t m e from resp on d in g to regu lar m ail. If you d o n eed a resp on se th rou gh th e m ail, p lease in clu d e a self-ad d ressed , stam p ed en velop e so th at I can rep ly to you . If you are in terested in on e of m y m an y in ten sive PC train in g sem in ars or vid eotap es, p lease call m y office. Th an k you again for read in g th is book, an d a sp ecial th an ks to th ose p eop le wh o h ave been loyal read ers sin ce th e first ed ition cam e ou t in Decem ber 1988. Sin cerely, Scott Mu eller

A

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Appendix A

Vendor List

On e of th e m ost fru stratin g th in gs abou t su p p ortin g PCs is fin d in g a sp ecific ad ap ter board , p art, d river p rogram , or wh atever you n eed to m ake a system work. If you are su p p ortin g or in stallin g p rod u cts, you will n eed access to tech n ical su p p ort or d ocu m en tation for p rod u cts you m ay n ot h ave p u rch ased . Over th e years, I h ave com p iled a list of com p an ies wh ose p rod u cts are p op u lar or wh ose p rod u cts I h ave fou n d to work excep tion ally well. I u se th ese con tacts regu larly to p rovid e in form ation an d com p on en ts th at en able m e to su p p ort PC system s effectively. Man y of th ese com p an ies h ave been m en tion ed in th is book, bu t oth ers n ot sp ecifically m en tion ed h ave been ad d ed h ere. Th ese com p an ies carry m an y com p u ter p rod u cts you will h ave con tact with or th at I sim p ly recom m en d . I h ave tried to list as m an y ven d ors as p ossible. Th ese ven d ors are im p ortan t in d ay-tod ay work with PC system s an d can su p p ly d ocu m en tation for you r com p on en ts, p rovid e p arts an d service, an d be u sed as a sou rce for n ew eq u ip m en t an d software. Th is list is as u p -to-d ate as p ossible, bu t com p an ies m ove or go ou t of bu sin ess all th e tim e. If you fin d an y in form ation in th is list th at is n o lon ger accu rate, p lease call m e or leave m e a m essage on Com p u Serve at sc o t t m u e l l e r@c o m p u se rv e .c o m . Man y of th e com p an ies listed also p rovid e su p p ort via electron ic bu lletin board system s (BBSes) an d th e W orld W id e W eb (W W W ). Alth ou gh origin ally exclu sively th e d om ain of com p u ter en th u siasts, tod ay m an y com p an ies u se In tern et W eb sites an d BBS system s to p rovid e a h igh level of tech n ical su p p ort. Th rou gh a com p an y-ru n W eb site or BBS, you can receive d etailed tech n ical su p p ort on th at com p an y’s p rod u cts an d d own load p rod u ct literatu re an d referen ce m aterials. I u su ally fin d th e level of su p p ort I can obtain on lin e is su p erior to trad ition al p h on e su p p ort, esp ecially becau se I d on ’t h ave to wait on h old ! W ith each com p an y listin g, I h ave in clu d ed both stan d ard p h on e n u m bers an d 800 n u m bers wh ere p ossible, so U.S. an d in tern ation al read ers can easily con tact th ese com p an ies. Also in clu d ed are fax n u m bers, In tern et ad d resses, an d BBS

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n u m bers, wh ere available. I h ave n ot in clu d ed an y com m u n ication s p aram eter settin gs, bu t virtu ally all BBS system s su p p ort 28.8K (V.34) con n ection s. Som e com p an ies ru n a FAX back system , an au tom ated system th rou gh wh ich you can req u est p rod u ct an d tech n ical in form ation to be sen t d irectly to you r own fax m ach in e. FAXback system s are an excellen t way to get im m ed iate d ocu m en tation or tech n ical su p p ort to solve tou gh p roblem s. I h ave tried to in clu d e Net an d W W W ad d resses for an y com p an ies th at offer th is access. Com p an ies are ad d in g th is typ e of access rap id ly th ese d ays, so m an y com p an ies m ay h ave ad d ed In tern et sites after th is book was p rin ted . If you d iscover an y su ch in form ation th at I h ave n ot in clu d ed , p lease e-m ail m e d etailin g wh at you h ave fou n d . Fin ally, each listin g in clu des a sh ort description of th e produ cts or services th e com pan y provides. I u se th is ven dor list con stan tly m yself; I h ope you fin d th is list as u sefu l as I do! As an im p rovem en t to th is Tenth Anniversary Edition, I’ve ad d ed a categorical listin g of p rod u cts an d services at th e en d of th e ven d or list. Th is way, if you n eed to fin d a p rod u ct bu t you d on ’t kn ow wh at com p an ies m ake th em , look u p th e category at th e en d of th e ven d or list, fin d th e ven d ors th ere th at m ake or sell th is typ e of p rod u ct, an d th en look u p th e con tact in form ation for th ose ven d ors. #1-PC Diagnost ics Com pany ( The ESD Division of W indsor Technologies, Inc.) 130 Alto St. San Rafael, CA 94901 Ph on e Fax W eb E-m ail

(415) 456-2200 (415) 456-2244 w w w .t u f f t e st .c o m sa l e s@t u f f t e st .c o m

Man u factu res Tu ffTEST-Pro™, an excellen t h igh -en d service tech n ician -level, PC d iagn ostics, an d trou blesh ootin g p rogram th at can be d own load ed from th eir W eb site. 3Com Corp. 5400 Bayfron t Plaza P.O. Box 58145 San ta Clara, CA 95052-8145 Ph on e Sales Fax W eb

(408) 764-5000 (800) 638-3266 (408) 764-5001 w w w .3 c o m .c o m

Man u factu res n etwork adapters, servers, m odem s, an d oth er n etworkin g equ ipm en t.

3D Labs 181 Metro Drive, Su ite 520 San Jose, CA 95110 Ph on e Fax W eb E-m ail

(408) 436-3455 (408) 436-3458 w w w .3 d l a b s.c o m su p p o rt @3 D l a b s.c o m

Creates 3D grap h ics accelerators in clu d in g a p op u lar lin e called “Glin t,” in clu d ed in m an y OEM grap h ics card s. 3Dfx 4435 Fortran Drive San Jose, CA 95134 Ph on e Fax W eb

(408) 935-4400 (408) 262-8874 w w w .3 d f x .c o m

Creates 3D grap h ics accelerators in clu d in g a p op u lar lin e called “Vood oo,” in clu d ed in m an y OEM grap h ics card s.

Acme Electric/ Electronics Division

3M Dat a St orage Product s Division 1 Im ation Place Oakd ale, MN 55128 Sales Tech Su p p ort W eb

(612) 704-4000 (800) 328-9438 w w w .Im a t i o n .c o m

Man u factu res m agn etic d isk an d tap e m ed ia. Aavid Therm al Technologies, Inc. On e Kool Path P.O. Box 400 Lacon ia, NH 03247-0400 Ph on e Fax W eb

(603) 528-3400 (603) 528-1478 w w w .a a v i d .c o m

Man u factu res a lin e of h eat sin ks an d th erm al m an agem en t m aterials. ABIT Com put er ( USA) Corporat ion 46808 Lakeview Blvd . Frem on t, CA 94538 Ph on e Fax W eb E-m ail

(510) 623-0500 (510) 623-1092 w w w .a b i t -u sa .c o m sa l e s@a b i t -u sa .c o m

Man u factu res an excellen t lin e of PC m oth erboard s in ATX an d Baby-AT form factors. Th eir m oth erboard s are kn own for h avin g ju m p er an d switch less software con figu ration . Accurit e Technologies, Inc. 48460 Lakeview Blvd . Frem on t, CA 94538-6532 Ph on e Fax W eb E-m ail

(510) 668-4900 (510) 668-4905 w w w .a c c u ri t e .c o m sa l e s@a c c u ri t e .c o m

Man u factu res floppy drive diagn ostic produ cts, PCMCIA diagn ostic produ cts, an d PCMCIA floppy drive su bsystem s. Floppy

drive diagn ostic produ cts in clu de th e Accu rite Drive Probe floppy drive diagn ostics program an d HRD, DDD, an d AAD in du stry stan dard test disks. PCMCIA produ cts in clu de th e PC Exten derCard, th e PC ReportCard (a PCMCIA diagn ostic card), th e HeadstartCard (a PCMCIA developers’ kit) an d th e Travel Floppy 144 (a PCMCIA in terfaced floppy drive su bsystem ). Acer Am erica Corp. 2641 Orch ard Pkwy. San Jose, CA 95134-2073 Ph on e Tech Su p p ort Fax W eb

(408) 432-6200 (800) 445-6495 (408) 922-2933 w w w .a c e r.c o m / AAC/

Th e secon d -largest worldwide m oth erboard an d PC system com pon en t m an u factu rer. Man u factu res everyth in g from com pon en ts to com plete desktop an d n otebook system s, as well as m on itors an d prin ters. Acer Laborat ories, Inc. ( ALi) Pacific Tech n ology Grou p 4701 Patrick Hen ry Dr., Ste. 2101 San ta Clara, CA 95054 Ph on e Fax W eb

(408) 764-0644 (408) 496-6142 w w w .a l i .c o m .t w

Man u factu res ch ip sets in clu d in g PC m oth erboard , Su p er I/ O, d isk con troller, an d oth ers. Th ey m ake th e Alad d in series ch ip s for Pen tiu m system s. Acm e Elect ric/ Elect ronics Division 9962 Rou te 446 Cu ba, NY 14727 Ph on e (716) 968-2400 Live W ire Exp ress (800) 325-5848 (Rep airs) Fax (716) 968-3948 Man u factu res u n in terru ptible power su pplies (UPS) system s an d power con dition ers.

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Adapt ec 691 S. Milp itas Blvd . Milp itas, CA 95035 Ph on e FaxBack Fax Tech Su p p ort W eb

(408) 945-8600 (800) 934-2766 (408) 262-2533 (408) 945-2550 w w w .a d a p t e c .c o m

A lead in g su p p lier of h igh -p erform an ce in p u t/ ou tp u t solu tion s, in clu d in g a broad array of SCSI h ost ad ap ters an d software solu tion s. Th eir SCSI h ost ad ap ters h ave becom e a de facto stan d ard an d h ave an en orm ou s am ou n t of th ird -p arty su p p ort. Acq u ired Tran tor System s, Ltd . com p an y, an d n ow m an u factu res th e Min iSCSI Parallel Port SCSI ad ap ters, in clu d in g h ard d isk an d CD-ROM d rivers for a variety of d evices. Also acq u ired Fu tu re Dom ain . Adobe Syst em s, Inc. 345 Park Ave. San Jose, CA 95110-2704 Ph on e Fax Tech Su p p ort W eb

(408) 536-6000 (408) 537-6000 (800) 833-6687 w w w .a d o b e .c o m

Man u factu res (an d created ) th e PostScrip t lan gu age an d a variety of grap h ics software. Pu blish er of PageMaker, Pagem ill, Illu strator, an d PostScrip t fon ts (for DOS an d Macin tosh system s). ADP Hollander Com pany 14800 28th Aven u e North , Ste. 190 Plym ou th , MN 55447 Ph on e Fax

(800) 825-0644 (612) 553-0270

Pu blish es au tom otive p arts in terch an ge m an u als.

Advanced Digit al Inform at ion Corporat ion 11431 W illows Rd . Red m on d , W A 98052 Ph on e Fax W eb

(800) 336-1233 (206) 881-2296 w w w .a d i c .c o m

Man u factu res h igh -cap acity tap e-backu p su bsystem s. Advanced Int egrat ion Research ( AIR) 2188 Del Fran co St. San Jose, CA 95131 Ph on e Fax BBS W eb

(408) 428-0800 (408) 428-0950 (408) 428-1735 w w w .a i rw e b s.c o m

Man u factu res a lin e of Pen tiu m , Pen tiu m Pro, an d Pen tiu m II-class h igh p erform an ce m oth erboard s. Advanced Logic Research ( ALR) 9401 Jeron im o St. Irvin e, CA 92618 Ph on e Sales Tech Su p p ort BBS Fax W eb

(714) 581-6770 (800) 444-4257 (800) 257-1230 (714) 458-6834 (714) 581-9240 w w w .a l r.c o m

Man u factu res h igh -p erform an ce bu sin ess d esktop s, workstation s, an d server system s.

ALPS Electric

Advanced M icro Devices ( AM D) On e AMD Place P.O. Box 3453 Su n n yvale, CA 94088-3453 Ph on e Toll Free Tech Su p p ort Fax W eb

(408) 732-2400 (800) 538-8450 (800) 222-9323 (408) 749-4753 w w w .a m d .c o m

Man u factu res In tel-com patible ch ips an d m ath coprocessors. Th ey h ave h igh -en d processors in clu din g a Pen tiu m -class ch ip called th e K5 an d th eir K6 tech n ology rivals Pen tiu m II in speed an d perform an ce. Advanced Personal Syst em s 105 Serra W ay, Ste. 418 Milp itas, CA 95035 Ph on e Fax W eb

(408) 298-3703 (408) 945-0242 w w w .sy sc h k .c o m

Man u factu res th e excellen t SysCh k d iagn ostics p rogram , wh ich p rovid es valu able in form ation abou t d evices in stalled in you r system . Aeronics, Inc. 12741 Research Blvd ., Ste. #500 Au stin , TX 78759 Ph on e Fax

(512) 258-2303 (512) 258-4392

Man u factu res th e h igh est-q u ality active an d forced -p erfect term in ators for u se in SCSI-bu s system s. Th ey are kn own for solvin g p roblem s with lon ger d istan ces or m u ltip le-SCSI d evices. AIW A Am erica, Inc. Com put er Syst em s Division 16969 Von Karm an , Ste. 260 Irvin e, CA 92612 Ph on e Fax W eb

(949) 862-0200 (949) 862-0213 w w w .a i w a .c o m / c sd

Markets an d sells m ass storage solu tion s for n etwork system s an d p erson al workstation s. AllM icro, Inc. ( Purchased by ForeFront Direct ) 25400 US Hwy 19 N., Ste. 285 Clearwater, FL 33763 Ph on e Fax Sales BBS W eb E-m ail

(813) 539-7283 (813) 531-0200 (800) 653-4933 (813) 535-9042 w w w .a l l m i c ro .c o m a l l m i c ro @a l l m i c ro .c o m

Man u factu rer an d d istribu tor of th e Rescu e d ata recovery software, th e Post Plu s, Discovery Card , Alert Card , an d oth er variou s h ard ware an d software d iagn ostic u tilities an d trou blesh ootin g tools. Alloy Com put er Product s 165 Forest St. Marlborou gh , MA 01752 Ph on e Tech Su p p ort Fax BBS

(978) (900) (978) (978)

486-0001 680-2556 481-7711 486-4044

Man u factu res tap e-backu p su bsystem s. ALPS Elect ric 3553 N. First St. San Jose, CA 95134 Ph on e Sales Tech Su p p ort Cu stom er Service Fax BBS W eb

(408) 432-6000 (800) 950-ALPS (2577) (800) 449-ALPS (2577) (800) 825-ALPS (2577) (408) 432-6035 (408) 432-6424 w w w .a l p su sa .c o m

Man u factu res h igh -q u ality keyboard s an d keyboard switch es. Th ey h ave an excellen t m ech an ical keyswitch d esign with a q u ality tactile feed back. Also m akes p rin ters, flop p y d rives, m ice, an d keyp ad s.

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Alt ex Elect ronics, Inc. 11342 IH 35 North San An ton io, TX 78233 Ph on e Fax

W eb

(210) 655-8882 (210) 637-3264 or (210) 637-3276 (Attn : Jim Mu n d t) w w w .a l t e x .c o m

Su p p lies m ail-ord er com p u ter/ electron ics p arts. Am dek Corporat ion ( A Division of W yse Technology) 1901 Zan ker Rd . San Jose, CA 95112 Ph on e Sales Tech Su p p ort Fax BBS W eb

(408) 473-1200 (800) 722-W YSE (9973) (408) 435-2770 (408) 473-1972 (408) 922-4400 w w w .w y se .c o m

Man u factu res m on itors. Am erica Online 2200 AOL W ay Du lles, VA 20166 Ph on e Head q u arters W eb

(703) 448-8700 (703) 265-2120 w w w .a o l .c o m

Provid es a p op u lar on lin e service th at allows access to th eir own n etwork an d th e In tern et.

As a core tech n ology p rovid er, Am erican Megatren d s d evelop s an d p rovid es su p erior system -level tech n ologies in clu d in g RAID p rod u cts, BIOS, m oth erboard s, an d u tilities. Am erican Nat ional St andards Inst it ut e ( ANSI) 11 W est 42n d St. 13th Floor New York, NY 10036 Ph on e Fax W eb

(212) 642-4900 (212) 398-0023 w w w .a n si .o rg

ANSI com m ittees set stan d ard s th rou gh ou t th e com p u ter in d u stry. Cop ies of an y ANSI-ap p roved stan d ard can be ord ered h ere. Am erican Pow er Conversion ( APC) 132 Fairgrou n d s Rd . W est Kin gston , RI 02892 Ph on e Tech Su p p ort Fax W eb

(401) 789-5735 (800) 800-4272 (401) 789-3710 w w w .a p c c .c o m

Man u factu res a lin e of p ower p rotection eq u ip m en t. AM P, Inc. AMP Bu ild in g P.O. Box 3608 Harrisbu rg, PA 17105

Am erican M egat rends, Inc. ( AM I) 6145-F North belt Pkwy. Norcross, GA 30071

Ph on e Sales Fax W eb

Ph on e Sales BBS W eb

Man u factu res a variety of com p u ter con n ectors, sockets, voltage ad ap ters, an d cables u sed by m an y OEMs.

(770) 246-8600 (800) 828-9264 (770) 246-8780 w w w .a m i .c o m

(717) 564-0100 (800) 522-6752 (717) 986-7605 w w w .a m p .c o m

Arrowfield International, Inc.

Androm eda Research P.O. Box 222 Milford , OH 45150 Ph on e Fax W eb

(513) 831-9708 (513) 831-7562 w w w .a rl a b s.c o m

Man u factu res an excellen t EPROM p rogram m er th at ru n s from a PC p arallel p ort. Th e d evice can p rogram u p to 16M UV an d FLASH EPROMS, p lu s m ore. Th e in clu d ed software ru n s u n d er DOS, W in 3.1 an d W INGS on an y PC-com p atible com p u ter. Annabooks/ Annasoft Syst em s 11838 Bern ard o Plaza Ct., Ste. 102 San Diego, CA 92128-2417 Ph on e Sales Fax W eb E-m ail

(619) 673-0870 (800) 462-1042 (619) 673-1432 w w w .a n n a b o o k s.c o m i n f o @a n n a b o o k s.c o m

Pu blish es an d sells an excellen t lin e of tech n ical books an d in form ation on PC h ard ware an d software d esign . Teach es worksh op s on PCI, Card bu s, an d USB d esign .

Fax W eb

(800) 505-0171 w w w .a p p l e .c o m

Man u factu res a lin e of p erson al com p u ters u n d er th e Macin tosh (Mac) bran d n am e, p erip h erals, an d software. Arco Com put er Product s, Inc. 2750 N. 29th Ave., Ste. 316 Hollywood , FL 33020 Ph on e Fax BBS W eb E-m ail

(954) 925-2688 (954) 925-2889 (954) 925-2791 w w w .a rc o i d e .c o m a rc o @a rc o i d e .c o m

Sp ecializes in IDE RAID 1 d isk m irrorin g ad ap ters for th e PC. Arrow Elect ronic 1350 McCan d less Drive, Bld g. 3 Milp itas, CA 95035 Ph on e Toll Free Fax W eb

(408) 441-4050 (888) 263-7720 (408) 441-4451 w w w .a rro w a m e ri c a s.c o m

A large distribu tor of Hewlett-Packard DAT tape an d h ard disk drives. Th ey also distribu te oth er h ard disk an d storage produ cts.

Anvil Cases 15650 Salt Lake Ave. In d u stry, CA 91745

Arrow field Int ernat ional, Inc. 2812-A W aln u t Ave. Tu stin , CA 92780

Ph on e Sales Fax W eb

Sales Ph on e Fax W eb E-m ail

(626) 968-4100 (800) 359-2684 (626) 968-1703 w w w .a n v i l d e a l e r.c o m

Man u factu res h eavy-d u ty eq u ip m en t cases. Apple Com put er, Inc. 1 In fin ite Loop Cu p ertin o, CA 95014 Ph on e Sales

(408) 996-1010 (800) 538-9696

(800) 227-9628 (714) 669-0101 (714) 669-0526 w w w .a rro w f i e l d i n c .c o m a ro w f l d @i x .n e t c o m .c o m

Man ufactures an in credible array of disk drive brackets, rails, slides, cable adapters, bezels, cabin ets, an d com plete drive upgrade an d repair assem blies for PC-com patible an d Com paq proprietary system s.

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Associat ion of Sharew are Professionals ( ASP) 157-F Love Ave. Green wood , IN 46142

Asus Com put er Int ernat ional ( ASUSt ek) 721 Ch arcot Ave. San Jose, CA 95013

Ph on e Fax W eb E-m ail

Ph on e W eb

(317) 888-2194 (317) 888-2195 w w w .a sp -sh a re w a re .o rg e x e c d i r@a sp -sh a re w a re .o rg

Th e ASP sets stan dards for sh areware products an d provides an om budsm an for disputes between users an d auth ors as well as m arketin g in form ation for sh areware auth ors. AST Research, Inc. 16225 Alton Pkwy. Irvin e, CA 92618 Ph on e Sales Fax BBS W eb

(714) 727-4141 (800) 876-4278 (714) 727-9355 (817) 230-6850 w w w .a st .c o m

Man u factu res an exten sive lin e of ad ap ter board s an d p erip h erals for PC system s, an d a lin e of PC system s. Ast ec Am erica, Inc. 6339 Paseo Del Lago Carlsbad , CA 92009 Ph on e Fax W eb

(760) 930-4600 (760) 930-4700 w w w .a st e c .c o m

Man u factu res h igh -en d p ower su p p lies for PC system s an d m an y oth er ap p lication s. Astec p ower su p p lies are u sed as OEM eq u ip m en t in m an y of th e top m an u factu rers’ system s, in clu d in g IBM an d oth ers.

(510) 739-3777 w w w .a su s.c o m .t w

Man u factu res a lin e of PC-com p atible m oth erboard s, in clu d in g Pen tiu m - an d Pen tiu m II-class m oth erboard s. AT&T Nat ional Part s Sales Cent er/ Lucent Technologies 7424 Scott Ham ilton Dr. Little Rock, AR 72209 Ph on e Tech Su p p ort Fax

(800) 222-7278 (800) 628-2888 (800) 527-4360

Su p p lies p arts an d com p on en ts for AT&T com p u ter system s. Call an d ask for th e free AT&T p arts catalog. ATI Technologies, Inc. 33 Com m erce Valley Dr. East Th orn h ill, ONT L3T 7N6 Can ad a Ph on e Tech Su p p ort Fax BBS W eb

(905) 882-2600 (905) 882-2626 (905) 882-2620 (905) 764-9404 w w w .a t i t e c h .c a

Man u factu res a p op u lar lin e of h igh p erform an ce PC vid eo ad ap ters an d ch ip sets. Aut odesk, Inc. 111 McIn n is Pkwy. San Rafael, CA 94903 Ph on e Sales Fax W eb

(415) 507-5000 (800) 445-5415 (415) 507-5100 w w w .a u t o d e sk .c o m

Man u factu res Au toCAD software.

Bitstream, Inc.

Aut ot im e Corporat ion 6605 SW Macad am Ave. Portlan d , OR 97201 Ph on e Fax W eb E-m ail

(503) 452-8577 (503) 452-8495 w w w .a u t o t i m e .c o m i n f o @a u t o t i m e .c o m

Man u factu res th e Hyp ercable, wh ich tran sm its h igh -sp eed p arallel d ata u p to 200 feet. Th e n ew bid irection al cable su p p orts p arallel-p orted CD-ROM an d tap e backu p p erip h erals. Th ey also con vert DIP ch ip s to SIMMs an d sell 30-p in to 72-p in SIMM ad ap ters. Aw ard Soft w are Int ernat ional, Inc. 777 E. Mid d lefield Rd . Mou n tain View, CA 94043 Ph on e Fax BBS W eb

(650) 237-6800 (650) 968-0274 (415) 968-0249 w w w .a w a rd .c o m

Man u factu res a lin e of PC ROM BIOS software. Recen tly m erged with Ph oen ix. AZ-COM , Inc. 3343 Vin cen t Rd ., Ste. D Pleasan t Hills, CA 94523 Ph on e Tech Su p p ort Fax W eb E-m ail

(800) 209-2418 (510) 947-1000 (510) 947-1900 w w w .a z -c o m .c o m sa l e s@a z -c o m .c o m

Man u factu res a com p lete lin e of Bu sExten d er card s for ISA, EISA, MCA, VL-Bu s, PCI, an d oth ers. Th ese exten d ers allow you to easily in sert an d rem ove ad ap ter card s for testin g with th e p ower on . Belden W ire and Cable P.O. Box 1980 Rich m on d , IN 47375

Ph on e Sales Fax W eb E-m ail

(317) 983-5200 (800) 235-3362 (317) 983-5656 w w w .b e l d e n .c o m i n f o @b e l d e n .c o m

Man u factu res cable an d wire p rod u cts. Berkshire Product s P.O. Box 1015 Su wan ee, GA 30024 Ph on e Fax W eb

(770) 271-0088 (770) 932-0082 w w w .b e rk p ro d .c o m

Man u factu res th e PC W atch d og system m on itor, in clu d in g an op tion al tem p eratu re alarm . Th is board can au tom atically restart a server or oth er system th at h as locked u p . Best Pow er ( A Division of General Signal Pow er) P.O. Box 280 Neced ah , W I 54646 Ph on e Sales Fax W eb

(608) 565-7200 (800) 356-5794 (608) 565-2221 w w w .b e st p o w e r.c o m

Man u factu res an excellen t lin e of com p u ter p ower p rotection eq u ip m en t from h igh -en d ferroreson an t UPS system s to lin e con d ition ers an d stan d by p ower p rotection system s. Bit st ream , Inc. 215 First St. Cam brid ge, MA 02142 Ph on e Sales Fax W eb E-m ail

(617) 497-6222 (800) 522-3668 (617) 868-0784 w w w .b i t st re a m .c o m sa l e s@b i t st re a m .c o m

Man u factu res fon ts an d fon t software.

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Appendix A—Vendor List

Black Box Corporat ion 1000 Park Drive Lawren ce, PA 15055 Ph on e Fax W eb E-m ail

(724) 746-5500 (724) 746-0746 w w w .b l a c k b o x .c o m i n f o @b l a c k b o x .c o m

A lead in g d irect m arketer of com p u ter com m u n ication s an d n etworkin g p rod u cts an d services, in clu d in g n etwork eq u ip m en t, cables, an d con n ectors for a variety of ap p lication s. Boca Research, Inc. 1377 Clin t Moore Boca Raton , FL 33487 Ph on e Tech Su p p ort Fax BBS W eb

(561) 997-6227 (561) 241-8088 (561) 994-5848 (561) 241-1601 w w w .b o c a re se a rc h .c o m

Man u factu res a low-cost lin e of ad ap ter card p rod u cts for PCs. Borland Int ernat ional ( Now Inprise) 100 En terp rise W ay Scotts Valley, CA 95066-3249 Ph on e Sales Tech Su p p ort BBS W eb

(408) 431-1000 (800) 331-0877 (800) 523-7070 (408) 431-5096 w w w .i n p ri se .c o m

Software m an u factu rer th at featu res Tu rbo lan gu age p rod u cts, Parad ox, an d d BASE. Also th e software m an u factu rer of Delp h i. Bose Corp. Th e Mou n tain Fram in gh am , MA 01701-9168 Ph on e Fax W eb

(508) 879-7330 (508) 879-1157 w w w .b o se .c o m

Man u factu res sp eakers an d in tegrated am p lifiers. Bost on Com put er Exchange 210 Sou th Street Boston , MA 02111 Ph on e Fax W eb

(617) 542-4414 (617) 542-8849 w w w .b o c o e x .c o m

A broker for u sed PC com p u ters. Brookt ree Corporat ion ( Purchased by Rockw ell) 9868 Scran ton Rd . San Diego, CA 92121-3707 Ph on e Sales Fax W eb

(619) 452-7580 (800) 228-2777 (619) 452-2104 w w w .n b .ro c k w e l l .c o m

Man u factu res a lin e of d igital-to-an alog con verter (DAC) ch ip s an d m u ltim ed ia ch ip sets. Buerg, Vernon D. 850 Petalu m a Blvd . North Petalu m a, CA 94952 Ph on e Fax BBS W eb

(707) 778-1811 (707) 769-5479 (707) 778-8944 w w w .b u e rg .c o m

Man u factu res an excellen t lin e of u tility p rogram s, in clu d in g th e p op u lar LIST p rogram . Bu erg software is d istribu ted on lin e th rou gh BBSes an d th e In tern et. Byt e Inform at ion Exchange ( BIX) 1030 Massach u setts Ave. Cam brid ge, MA 02138 Ph on e Fax W eb E-m ail

(800) 695-4775 (617) 491-6642 w w w .b i x .c o m i n f o @b i x .c o m

An on lin e com p u ter in form ation an d m essagin g system .

Centon Electronics, Inc.

Byte M agazine/ M cGraw -Hill

On e Ph oen ix Mill Ln . Peterborou gh , NH 03458 Ph on e Cu stom er Service BBS E-m ail

(603) 924-9281 (603) 924-7507 (617) 861-9764 e d i t o rs@b i x .c o m

A m on th ly m agazin e coverin g all lin es of m icrocom p u ters. Byt e Runner Technologies 1316 W illow Grove Drive Kn oxville, TN 37922 Ph on e Sales Tech Su pport Fax W eb E-m ail

(423) 470-4938 (800) 274-7897 (423) 693-5560 (423) 693-6785 w w w .b y t e ru n n e r.c o m sd u d l e y @b y t e ru n n e r.c o m

Carries a lin e of h igh -p erform an ce I/ O card s featu rin g FIFO (16550/ 16650/ 16750 typ e) serial p ort UART ch ip s, an d EPP/ ECP p arallel p orts. Th ey also carry ad ap ters th at allow an y IRQ settin g (in clu d in g IRQs 9–15) to p reven t con flicts with oth er existin g p orts, an d m an y card s th at allow IRQ sh arin g.

W eb E-m ail

w w w .c a i g .c o m c a i g 1 2 3 @a o l .c o m

Man u factu res an d sells clean ers an d lu brican ts for electron ic ap p lication s, featu rin g ProGold con tact en h an cer for p lated con tacts an d con n ectors. Cal-Abco 6041 Variel Ave. W ood lan d Hills, CA 91367 Ph on e Fax

(800) 669-2226 (818) 704-7733

Distribu tes com p u ter system s an d p erip h erals. Canon USA, Inc. On e Can on Plaza Lake Su ccess, NY 11042 Ph on e Fax BBS

(516) 488-6700 (516) 354-5805 (516) 488-6528

Man u factu res a lin e of p rin ter an d vid eo eq u ip m en t as well as flop p y d rives. Casio, Inc. 570 Mt. Pleasan t Ave. Dover, NJ 07801

Cables t o Go ( CTG) 1501 W ebster St. Dayton , OH 45404

Ph on e Sales Fax W eb

Ph on e Sales Fax W eb

Man u factu res d igital cam eras, p erson al d ata system s, an d d igital watch es.

(513) 224-8646 (800) 826-7904 (800) 331-2841 w w w .c a b l e st o g o .c o m

(973) 361-5400 (800) 962-2746 (201) 361-3819 w w w .c a si o -u sa .c o m

Man u factu res a variety of cable, con n ector, an d switch p rod u cts.

Cent on Elect ronics, Inc. 20 Morgan Irvin e, CA 92718

CAIG Laborat ories 16744 W . Bern ard o Dr. San Diego, CA 92127-1904

Ph on e Fax W eb

Ph on e Sales Fax

Man u factu res m em ory en h an cem en t kits, SIMM an d DIMM m od u les, exp an sion board s, cred it card s, an d PCMCIA card s.

(619) 451-1799 (800) CAIG-123 (224-4123) (619) 451-2799

(714) 855-9111 (714) 855-3132 w w w .c e n t o n .c o m

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Chem t ronics, Inc. 8125 Cobb Cen ter Dr. Ken n esaw, GA 30152 Ph on e Sales Fax W eb

(770) 424-4888 (800) 645-5244 (770) 424-4267 w w w .c h e m t ro n i c s.c o m

Man u factu res an d sells a com p lete lin e of com p u ter an d electron ic grad e ch em icals, m aterials, an d su p p lies, as well as sold er wick an d clean room item s. Cherry Elect rical Product s 3600 Su n set Ave. W au kegan , IL 60087 Ph on e Fax W eb

(847) 662-9200 (847) 360-3498 w w w .i n d u st ry .n e t / c h e rry .e l e c t ri c a l

Man u factu res a lin e of h igh -q u ality keyboard s for PC system s. Also p rod u ces a lin e of in d u strial Gas Plasm a d isp lays. Chicago Case Com pany 4446 S. Ash lan d Ave. Ch icago, IL 60609 Ph on e Fax

(312) 927-1600 (800) 333-8172

Man u factu res eq u ip m en t-sh ip p in g an d travel cases. Chilt on Book Com pany Ch ilton W ay Rad n or, PA 19089-0230 Ph on e

(610) 964-4743

Man ufactures a n um ber of excellen t autom otive service m an uals an d docum en tation . Chinon Am erica, Inc. 615 Hawaii Torran ce, CA 90503 Ph on e Sales

(310) 533-0274 (800) 441-0222

Fax BBS

(310) 533-1727 (310) 320-4160

Man u factu res a lin e of flop p y d isk an d CD-ROM d rives. Chips and Technologies, Inc. 2950 Zan ker Rd . San Jose, CA 95134 Ph on e Fax BBS W eb

(408) 434-0600 (408) 894-2079 (408) 456-0721 w w w .c h i p s.c o m

A wh olly own ed su bsid iary of In tel Corp oration th at d evelop s sem icon d u ctor an d software solu tion s for lead in g m an u factu rers of p erson al com p u ters. In tegrated solu tion s p rod u ct lin e p rovid es en h an ced grap h ics, fu ll-m otion vid eo, an d oth er ad van ced d isp lay cap abilities for both n otebook an d d esktop com p u ters. Ch ip s an d Tech n ologies is a su p p lier of flat-p an el vid eo grap h ics con trollers an d accelerators to th e p ortable com p u ter m arket. Chrysler M ot ors Service Publicat ions Service Pu blication s P.O Box 360450 Stron gsville, OH 44136 Ph on e Fax

(800) 890-4038 (216) 572-0725 (216) 572-0815

Pu blish es Ch rysler service m an u als an d d ocu m en tation . CI Design Com pany 1695 W . McCarth er Blvd . Costa Mesa, CA 92626 Ph on e Fax

(714) 556-0888 (714) 556-0890

Man u factu res cu stom -m ad e 3 1/ 2-in ch d rive m ou n tin g kits u sed by Tosh iba, Pan ason ic, an d NEC for th eir d rive p rod u cts. Also m akes d rive facep lates, en closu res, an d cu stom cable assem blies.

CompTIA (Computing Technology Industry Association)

CIE Am erica 2701 Dow Ave. Tu stin , CA 92680 Ph on e Sales Fax BBS W eb

(714) 573-2942 (800) 877-1421 (714) 757-4488 (714) 573-2645 w w w .c i t o h .c o m

Man u factu res PC p rin ters an d oth er p erip h erals. Cirrus Logic, Inc. 3100 W . W arren Ave. Frem on t, CA 94538 Ph on e Fax FAXBack BBS W eb

(510) 623-8300 (510) 252-6020 (800) 359-6414 (510) 440-9080 w w w .c i rru s.c o m

Man u factu res PC m oth erboard ch ip sets for m obile an d d esktop system s an d a lin e of ch ip sets for d isk con troller, vid eo, an d com m u n ication s circu its. Cit izen Am erica Corporat ion 2450 Broad way, Ste. 600 San ta Mon ica, CA 90404 Ph on e Fax W eb

(310) 453-0614 (310) 453-2814 w w w .c i t i z e n -a m e ri c a .c o m

Man u factu res a lin e of p rin ters an d flop p y d isk d rives. CM D Technology, Inc. 1 Van d erbilt Irvin e, CA 92618 Ph on e Sales Fax BBS W eb

(714) 454-0800 (800) 426-3832 (714) 455-1656 (714) 454-0795 w w w .c m d .c o m

Man u factu res EISA ad ap ters, PCI an d VL-Bu s IDE, an d SCSI d isk ad ap ters. Colorado M em ory Syst em s, Inc. See Hewlett-Packard (Storage Division ) Colum bia Dat a Product s 1070B Rain er Dr. Altam on te Sp rin gs, FL 32714 Ph on e Fax BBS W eb

(407) 869-6700 (407) 862-4725 (407) 862-4724 w w w .c d p .c o m

Man u factu res im age backu p software for all PC p latform s an d tools for q u ick rep lication of servers an d workstation s. Com paq Com put er Corporat ion P.O. Box 692000 Hou ston , TX 77269-2000 Ph on e Sales Tech Su p p ort Prod u ct In fo Fax BBS W eb E-m ail

(281) 370-0670 (800) 231-0900 (800) 652-6672 (800) 345-1518 (281) 378-8754 (281) 378-1418 w w w .c o m p a q .c o m su p p o rt @c o m p a q .c o m

Man u factu res d esktop , n otebook, an d server PC com p u ter system s. Com pTIA ( Com put ing Technology Indust ry Associat ion) 450 E. 22n d St., Ste. 230 Lom bard , IL 60148-6158 Ph on e Fax W eb E-m ail

(630) 268-1818 (630) 268-1384 w w w .c o m p t i a .o rg i n f o @c o m p t i a .o rg

A n on p rofit trad e association wh o sp on sors th e A+ Certification p rogram .

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Appendix A—Vendor List

Com pt on’s New M edia, Inc. ( A Division of Soft key Int ernat ional, Inc.) 1 Ath en aeu m St. Cam brid ge, MA 02142

Distribu tes a large n u m ber of com p u ter com p on en ts for rep air. Sp ecializes in d isp lay p arts su ch as flyback tran sform ers an d oth er com p on en ts.

Ph on e Fax W eb

Computer Design M agazine

(617) 494-1200 (617) 494-1279 w w w .so f t k e y .c o m

Prod u ces en tertain m en t, m u ltim ed ia, an d ed u tain m en t software for flop p y an d CDROM u sers. CD-ROM titles in clu d e Com pton’s Interactive Encyclopedia. Com pUSA, Inc. 14951 N. Dallas Pkwy. Dallas, TX 75240 Ph on e Sales Fax

(972) 982-4000 (800) 266-7872 (800) 329-2212

Com p u ter retail su p erstore an d m ail-ord er ou tlet. Com puServe Inform at ion Service ( CIS) 5000 Arlin gton Cen tre Blvd . Colu m bu s, OH 43220 Ph on e (614) 457-8600 Cu stom er Service (800) 848-8990 Fax (614) 529-1610 Largest on lin e in form ation an d m essagin g service; offers In tern et access an d m an u factu rer- an d ven d or-sp on sored foru m s for tech n ical su p p ort. Recen tly p u rch ased by Am erica On lin e. Com put er Com ponent Source, Inc. 7 Oser Aven u e Hau p p au ge, NY 11788 Ph on e Sales Fax

(516) 496-8727 (800) 356-1227 (800) 926-2062

Pen n W ell Pu blish in g Co. Ad van ced Tech n ology Division 10 Tara Blvd ., 5th Floor Nash u a, NH 03062-2801 Ph on e Fax W eb

(603) 891-0123 (603) 891-0539 a t d .p e n n w e l l .c o m

An excellen t in d u stry m agazin e for electron ic en gin eers an d en gin eerin g m an agers, featu rin g articles on all typ es of com p u ter com p on en ts an d h ard ware. Com put er Discount W arehouse ( CDW ) 200 N. Milwau kee Aven u e Vern on Hills, IL 60061 Ph on e Sales Tech Su p p ort Fax BBS W eb

(708) 465-6000 (800) 726-4239 (800) 383-4239 (708) 465-6800 (708) 465-6899 w w w .c d w .c o m

Com p u ter retail su p erstore an d m ail-ord er catalog ou tlet. Computer Graphics World M agazine

Pen n W ell Pu blish in g Co. Ad van ced Tech n ology Grou p 10 Tara Blvd ., 5th Floor Nash u a, NH 03062-2801 Ph on e Fax W eb

(603) 891-0123 (603) 891-0539 w w w .c g w .c o m

An in d u stry m agazin e coverin g grap h ics h ard ware, software, an d ap p lication s.

Comtech Publishing Ltd.

Computer Hotline M agazine

15400 Kn oll Trail Ste. #500 Dallas, TX 75248 Ph on e Sales Fax

(214) 233-5131 (800) 999-5131 (214) 233-5514

A p u blication th at featu res ad vertisers offerin g excellen t sou rces of rep lacem en t an d rep air p arts an d n ew an d u sed eq u ip m en t at wh olesale p rices. Com put er Library 1 Park Ave. New York, NY 10016 Ph on e Sales Fax W eb

(212) 503-4400 (800) 419-0313 (212) 503-4414 w w w .i a c n e t .c o m

Man u factu res th e Com p u ter Select CDROM d atabase in clu d in g fu ll text an d abstracts from m ore th an 120 com p u ter p u blication s. Th is is a valu able research tool. Computer Reseller News

CMP Med ia, In c. 1 Jerich o Plaza Jerich o, NY 11753 Ph on e (516) 733-6700 Ed itorial Dep t. Fax (516) 733-8636 W eb w w w .c rn .c o m An excellen t in d u stry trad e weekly n ews m agazin e featu rin g n ews for com p u ter p rofession als in volved in valu e-ad d ed resellin g of com p u ter eq u ip m en t. Su bscrip tion s are free to th ose wh o q u alify. Computer Retail Week M agazine

CMP Pu blication s, In c. 1 Jerich o Plaza Jerich o, NY 11753

Ph on e Fax W eb

(516) 733-6700 (516) 733-8577 w w w .c rw .c o m

An excellen t in d u stry trad e weekly n ews m agazin e featu rin g n ews for com p u ter su p erstores, m ass m erch an ts, an d retailers. Su bscrip tion s are free to th ose wh o q u alify. Computer Shopper M agazine

Ziff-Davis Pu blish in g On e Park Ave. New York, NY 10016 Ph on e W eb

(212) 503-3500 w w w .z d n e t .c o m / c sh o p p e r

Mon th ly m agazin e for exp erim en ters an d bargain h u n ters; featu res a large n u m ber of ad vertisem en ts. Computer Technology Review M agazine

W est W orld Prod u ction s, In c. 924 W estwood Blvd ., Ste. 650 Los An geles, CA 90024-2910 Ph on e Fax

(310) 208-1335 (310) 208-1054

An excellen t m on th ly tech n ical m agazin e for system s in tegrators, valu e-ad d ed resellers, an d origin al eq u ip m en t m an u factu rers. Su bscrip tion s are free to th ose wh o q u alify. Com t ech Publishing Lt d. P.O. Box 12340 Ren o, NV 89510 Ph on e Sales Fax W eb

(702) 825-9000 (800) 456-7005 (702) 825-1818 w w w .a c c u t e k .c o m / c o m t e c h

Man u factu res d Salvage Profession al, th e best an d m ost com p reh en sive Xbase d atarecovery an d file rep air software available.

1191

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Appendix A—Vendor List

Connect or Resources Unlim it ed ( CRU) 1005 Am es Ave. Milp itas, CA 95035

CS Elect ronics 1342 Bell Ave. Tu stin , CA 92780

Ph on e Sales Fax W eb

Ph on e Fax W eb E-m ail

(408) 957-5757 (800) 260-9800 (408) 942-0862 w w w .c ru i n c .c o m

Man u factu res rem ovable h ard d rive m od u les. Th e origin al p aten ted Am erican -m ad e Datap ort. Datap ort su p p orts all h ard -d rive in terfaces an d h as sp ecial coolin g for com p lex, h igh -RPM d rives. Conner Peripherals, Inc. See Seagate Tech n ology Corel Syst em s, Inc. 1600 Carlin g Ave. Ottawa, ONT K1Z 8R7 Can ad a Ph on e Fax BBS W eb

(613) 728-8200 (613) 728-9790 (613) 728-4752 w w w .c o re l .c o m

Man u factu res th e CorelDRAW ! grap h ics p rogram an d Corel SCSI, a SCSI d river kit featu rin g d rivers for a variety of SCSI h ost ad ap ters an d d evices. Also m an u factu res th e W ord Perfect Su ite. Creat ive Labs, Inc. 1901 McCarth y Blvd . Milp itas, CA 95035 Ph on e Sales Cu stom er Service Tech Su p p ort Fax BBS W eb

(408) 428-6600 (800) 544-6146 (800) 998-1000 (408) 742-6600 (408) 428-6611 (405) 742-6660 w w w .c re a f .c o m

Man u factu res th e Sou n d Blaster series of au d io card s for m u ltim ed ia an d sou n d ap p lication s.

(714) 259-9100 (714) 259-0911 w w w .sc si -c a b l e s.c o m / sc si c a b l e sc s@a o l .c o m

Man u factu res a very h igh -q u ality lin e of d isk an d tap e d rive cables, sp ecializin g in SCSI-1, SCSI-2, an d SCSI-3 ap p lication s. Th ey offer cu stom len gth s, con n ectors, an d im p ed an ces for a p rop er m atch with an existin g in stallation , an d u se th e h igh est-q u ality raw cable available. CST 2336 Lu Field Rd . Dallas, TX 75229 Ph on e Fax BBS W eb

(972) 241-2662 (972) 241-2661 (972) 241-3782 w w w .si m m t e st e r.c o m

Man u factu rer of m em ory/ SIMMs testers. CTX Int ernat ional, Inc. 20470 W aln u t Dr. W aln u t, CA 91789 Ph on e Sales Fax W eb

(909) 595-6146 (800) 888-9052 (909) 595-6293 w w w .c t x i n t l .c o m

Man u factu res a lin e of h igh -p erform an ce n otebook com p u ters.

Dallas Semiconductor

Curt is Com put er Product s 492 Heller Park Cou rt Dayton , NJ 08810

D.W . Elect rochem icals, Lt d. 97 Newkirk Rd . North , Un it 3 Rich m on d Hill, ONT L4C 3G4 Can ad a

Ph on e Fax

Ph on e Fax E-m ail W eb

(732) 438-9436 (732) 438-9437

Man u factu res a com p lete lin e of com p u ter accessories, in clu d in g cop y h old ers, glare filters, keyboard d rawers, m ed ia storage, p rin ter stan d s, d ata switch es, clean in g an d toolkits, n otebook cases, travel accessories, an d su rge p rotectors.

(905) 508-7500 (905) 508-7502 d w e l @st a b i l a n t .c o m w w w .st a b i l a n t .c o m

Man u factu res an d sells Stabilan t 22 con tact en h an cer an d treatm en t. Stabilan t 22 is th e gel con cen trate, an d Stabilan t 22a is a 4-to-1 isop rop an ol d ilu ted form .

CyberM edia 3000 Ocean Park Blvd ., Ste. 2001 San ta Mon ica, CA 90405

DakTech 4900 Ritter Rd . Mech an icsbu rg, PA 17055

Ph on e Fax W eb

Ph on e Sales Fax W eb E-m ail

(800) 721-7824 (800) 833-120 or (310) 581-4700 w w w .c y b e rm e d i a .c o m

Man u factu res d iagn ostic software for W in d ows, in clu d in g First Aid 9X. Cypress Sem iconduct or Corporat ion 3901 N. First St. San Jose, CA 95134 Ph on e W eb

(408) 943-2600 w w w .c y p re ss.c o m

Man u factu res PC ch ip sets an d oth er sem icon d u ctor d evices. Cyrix Corporat ion 2703 N. Cen tral Exp ressway Rich ard son , TX 75080 Ph on e Sales Fax FAXBack W eb

(972) 968-8388 (800) 462-9749 (972) 699-9857 (800) GO-CYRIX (462-9749) w w w .c y ri x .c o m

Man u factu res th e 6x86MX an d MII lin e of Pen tiu m -com p atible p rocessors.

(717) 795-9544 (800) 325-3238 (717) 795-9420 w w w .d a k t e c h .c o m d a k t e c h @i x .n e t c o m .c o m

Distribu tor of n ew an d u sed origin al eq u ip m en t IBM an d Com p aq p arts. Da-Lit e Screen Co. 3100 N. Detroit St. P.O. Box 137 W arsaw, IN 46581-0137 Ph on e Sales W eb

(219) 267-8101 (800) 622-3737 w w w .d a -l i t e .c o m

Man u factu res a lin e of p rojection screen s an d com p u ter fu rn itu re. Dallas Sem iconduct or 4401 S. Beltwood Pkwy. Dallas, TX 75244-3292 Ph on e Cu stom er Service Fax W eb

(972) 371-4000 (972) 371-4969 (972) 371-4470 w w w .d a l se m i .c o m

Man u factu res real-tim e clock an d n on volatile RAM m od u les u sed by a n u m ber of OEMs.

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Appendix A—Vendor List

Dam ark Int ernat ional, Inc. 7101 W in n etka Ave. North Min n eap olis, MN 55428 Ph on e Sales Fax W eb

(612) 531-0066 (800) 729-9000 (612) 549-2098 w w w .d a m a rk .c o m

Liq u id ates an d d istribu tes a variety of d iscon tin u ed p rod u cts, in clu d in g PCcom p atible system s an d p erip h erals. Darkhorse Syst em s, Inc. 12201 Tech n ology Blvd ., Ste. 130 Au stin , TX 78727 Ph on e Tech Su p p ort Fax BBS

(512) (800) (888) (512) (512)

335-4440 533-1744 255-2210 257-0296 257-5087

Man u factu res th e SIGMA.LC m em ory test system . Th is is a h igh -q u ality m em ory test d evice th at can accu rately test SIMMs, in d ivid u al ch ip s, an d oth er typ es of m em ory m od u les. Data Base Advisor M agazine

Data Communications M agazine

McGraw-Hill Com p an ies 1221 Aven u e of th e Am ericas New York, NY 10020 Ph on e Su bscrip tion s Fax W eb

(212) 512-2000 (800) 525-5003 (212) 512-6833 w w w .d a t a .c o m

An excellen t in d u stry p u blication featu rin g articles on n etworkin g an d com m u n ication s. Dat a Depot 1710 Drew St. Clearwater, FL 33755 Ph on e Sales Fax W eb E-m ail

(813) 446-3402 (800) SOS-DIAG (767-3424) (813) 443-4377 w w w .d a t a d e p o .c o m / d a t a d e p o .h t m d a t a d e p o @i x .n e t _c o m .c o m

Man u factu res th e PocketPOST d iagn ostic card for ISA an d EISA system s, an d several oth er excellen t d iagn ostics h ard ware an d software p rod u cts.

Ad visor Pu blication s 4010 Moren a Blvd ., Ste. 200 San Diego, CA 92117

Dat a Exchange Corporat ion 3600 Via Pescad or Cam arillo, CA 93012

Ph on e Fax Su bscrip tion s W eb E-m ail

Ph on e Sales Fax W eb E-m ail

(619) 483-6400 (619) 483-9851 (800) 336-6060 w w w .a d v i so r.c o m 7 0 0 0 7 .1 6 1 4 @c o m p u se rv e .c o m

An excellen t m agazin e featu rin g articles on d atabase ap p lication s software an d p rogram m in g rou tin es. Th ey also p u blish Access V isual Basic Advisor, Internet Advisor, FoxPro Advisor, Lotus Notes Advisor, an d Power Builder Advisor.

(805) 388-1711 (800) 237-7911 (805) 482-4856 w w w .d e x .c o m sa l e s@d e x .c o m

Sp ecializes in con tract m an u factu rin g, en d -of-life su p p ort, d ep ot rep air, logistic services, an d sp are p arts an d u n it sales. A com p lete rep air an d refu rbish m en t facility p rovid in g ISO 9002 certified d ep ot rep air of h igh -tech electron ics an d com p u terrelated p rod u cts from all m ajor m an u factu rers.

Diamond Flower, Inc. (DFI)

Dat a Ret rieval Services, Inc. 1040 Kap p Dr. Clearwater, FL 34625

Dell Com put er Corporat ion 1 Dellway Rou n d Rock, TX 78682

Ph on e Fax

Ph on e Sales Tech Su p p ort Fax BBS W eb

(813) 461-5900 (813) 461-5668

Sp ecialists in d ata retrieval from h ead crash ed d isk p acks, d am aged d isk d rives, flop p ies, an d tap es. Dat a Technology Corporat ion ( DTC) 1515 Cen tre Poin te Dr. Milp itas, CA 95035-8010 Ph on e Tech Su p p ort Fax FAXBack BBS W eb

(408) 942-4000 (408) 262-7700 (408) 942-4027 (408) 942-4005 (408) 942-4197 w w w .d a t a t e c h n o l o g y .c o m

Man u factu res a com p lete lin e of PC p erip h erals an d m u ltim ed ia p rod u cts. Dat ast orm Technologies, Inc. ( Purchased by Quart erdeck Corporat ion) 2401 Lem on e Blvd . Colu m bia, MO 65205 Ph on e Sales Tech Su p p ort Fax BBS W eb

(573) 443-3282 (800) 474-1573 (573) 875-0530 (573) 875-0595 (573) 875-0503 w w w .d a t a st o rm .c o m

Man u factu res ProCOMM, ProCOMM Plu s, an d ProCOMM Plu s for W in d ows In tern et, fax, an d d ata com m u n ication s software. Datastorm h as been p u rch ased by Qu arterd eck Corp oration , wh ich h as in tegrated Datastorm ’s p rod u ct lin e in to Qu arterd eck’s.

(512) 338-4400 (800) 426-5150 (800) 624-9896 (800) 727-8320 (512) 338-8528 w w w .d e l l .c o m

Man u factu res a lin e of low-cost, h igh p erform an ce PC com p u ter system s. DiagSoft , Inc. 5615 Scotts Valley Dr., Ste. 140 Scotts Valley, CA 95066 Ph on e Sales Fax W eb

(408) 438-8247 (800) 342-4763 (408) 438-7113 w w w .d i a g so f t .c o m

Ta m p a Of f i c e 6200 Cou rtn ey Cam p bell Cau seway, Ste. 320 Tam p a, FL 33607 Ph on e Fax

(813) 207-7000 (813) 207-7001

Man u factu res th e QAPlu s u ser-level PC d iagn ostics software an d th e h igh -en d QAPlu s/ FE (Field En gin eer) software, wh ich is an excellen t p rogram th at in clu d es com p lete h igh -resolu tion flop p y d rive testin g an d th e Power Meter ben ch m arkin g u tility. Diam ond Flow er, Inc. ( DFI) 135 Main Ave. Sacram en to, CA 95838 Ph on e Fax W eb

(916) 568-1234 (916) 568-1233 w w w .d f i u sa .c o m

Man u factu res a lin e of PC-com p atible system s, m oth erboard s, ad ap ter card s, an d oth er p rod u cts.

1195

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Appendix A—Vendor List

Diam ond M ult im edia Syst em s, Inc. 2880 Ju n ction Ave. San Jose, CA 95134-1922 Ph on e Sales Fax W eb

(408) 325-7000 (800) 468-5846 (408) 325-7070 w w w .d i a m o n d m m .c o m

Man u factu res a lin e of h igh -p erform an ce vid eo an d m u ltim ed ia ad ap ters. Also m akes an d sells th e Su p ra lin e of m od em an d telep h on y p rod u cts. Digi-Key Corporat ion 701 Brooks Ave. Sou th P.O. Box 677 Th ief River Falls, MN 56701-0677 Ph on e Sales Fax W eb

(218) 681-6674 (800) 344-4539 (218) 681-3380 w w w .d i g i k e y .c o m

Man u factu res in d u strial an d rack-m ou n t PC-com p atible system s an d a variety of backp lan e-d esign CPU board s an d m u ltifu n ction ad ap ters. Dolch Com put er Syst em s 3178 Lau relview Ct. Frem on t, CA 94538 Ph on e Fax W eb

(510) 661-2220 (510) 490-2360 w w w .d o l c h .c o m

Man u factu res a series of very p owerfu l p ortable com p u ters th at are also very exp an d able an d ru gged . If you n eed som eth in g m ore p owerfu l th an a lap top , th ey h ave lu n ch box-sized p ortables with large h ard d isks an d h igh -en d vid eo d isp lays. DTK Com put er, Inc. 770 Ep p erson Dr. City of In d u stry, CA 91748

Sells an en orm ou s variety of electron ic an d com p u ter com p on en ts, tools, an d test eq u ip m en t. Pu blish es a com p lete catalog listin g all item s.

Ph on e Fax BBS W eb

Dist ribut ed Processing Tech. ( DPT) 140 Can d ace Dr. Maitlan d , FL 32751

Man u factu res PC-com p atible system s an d BIOS software.

Ph on e Sales Fax BBS W eb

(407) 830-5522 (800) 322-4378 (407) 260-6690 (407) 831-6432 w w w .d p t .c o m

Man u factu res h igh -p erform an ce cach in g SCSI h ost ad ap ters an d d isk array (RAID) con trollers. Diversified Technology P.O. Box 748 Rid gelan d , MS 39158 Ph on e Sales Fax

(601) 856-4121 (800) 443-2667 (601) 856-2888

(818) 810-0098 (818) 810-0090 (818) 854-0797 w w w .d t k .c o m

Dukane Corporat ion 2900 Du kan e Dr. St. Ch arles, IL 60174 Ph on e Sales Fax W eb

(630) 584-2300 (800) 676-2485 (630) 584-5156 w w w .i n d u st ry .n e t / d u k a n e .a v

Man u factu res a com p lete lin e of h igh in ten sity overh ead p rojectors, LCD p an els, an d LCD d ata/ vid eo p rojectors. Th ey sp ecialize in p ortable h igh -brigh tn ess overh ead p rojector u n its d esign ed for LCD-p an el p rojection ap p lication s.

Electroservice Laboratories

Duracell, Inc. Berksh ire In d u strial Park Beth el, CT 06801 Ph on e Fax Sales W eb

(203) 796-4000 (203) 791-3386 (203) 791-3257 w w w .d u ra c e l l .c o m

Man u factu res h igh -p erform an ce con su m er ap p lication batteries in clu d in g alkalin e, lith iu m , an d stan d ard -sized n ickel-m etal h yd rid e rech argeable batteries. Edm und Scient ific 101 E. Glou cester Pike Barrin gton , NJ 08007-1380 Ph on e Fax Sales W eb

(609) 573-6280 (609) 573-6233 (609) 573-6250 w w w .e d sc i .c o m

Th ey offer a wide ran ge of optical com pon en ts an d scien tific equ ipm en t for in du stry an d research . Volu m e discou n ts offered. Free catalog offered to th ose wh o qu alify. Elect rocut ion P.O. Box 52083 W in n ip eg MB R2M 5P9 Can ad a Ph on e W eb

(204) 889-8430 w w w .e l e c t ro c u t i o n .c o m

Pu blish es The BIOS Com panion, an in valu able book coverin g in d etail th e d ifferen t BIOS version s on th e m arket in clu d in g d etailed setu p , con figu ration , an d d iagn ostics in form ation . Electronic Buyers’ News

CMP Pu blication s, In c. 600 Com m u n ity Dr. Man h asset, NY 11030-3875 Ph on e Su bscrip tion s Fax W eb

(516) 562-5899 (800) 291-5215 (516) 562-5123 t e c h w e b .c m p .c o m / e b n

An excellen t in d u stry trad e weekly m agazin e featu rin g n ews an d in form ation for th ose in volved in electron ics p u rch asin g, m aterials, an d m an agem en t. Su bscrip tion s are free to th ose wh o q u alify. Electronic Engineering Times M agazine

CMP Pu blication s, In c. 600 Com m u n ity Dr. Man h asset, NY 11030-3875 Ph on e Su bscrip tion s Fax W eb

(516) 562-5000 (800) 291-5215 (516) 562-5325 w w w .e e t i m e s.c o m

An excellen t in d u stry trad e weekly n ews m agazin e featu rin g n ews for en gin eers an d tech n ical m an agem en t. Su bscrip tion s are free to th ose wh o q u alify. Electronic Products M agazine

Hearst Bu sin ess Pu blication s, In c. 645 Stewart Ave. Gard en City, NY 11530 Ph on e Fax W eb

(516) 227-1300 (516) 227-1444 w w w .e l e c t ro n i c p ro d u c t s.c o m

An excellen t in d u stry trad e m agazin e featu rin g en gin eerin g-typ e in form ation on electron ic an d com p u ter com p on en ts an d in -d ep th tech n ical articles. Su bscrip tion s are free to th ose wh o q u alify. Elect roservice Laborat ories 6085 Sikorsky St. Ven tu ra, CA 93003 Ph on e Fax BBS W eb

(805) 644-2944 (805) 644-5006 (805) 644-7810 w w w .e sl .c o m

Provid es rep air p arts for m ost m ajor com p u ter OEMs, in clu d in g all m ajor PC com p on en ts.

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Elit egroup Com put er Syst em s, Inc. 45401 Research Ave. Frem on t, CA 94539 Ph on e Sales Fax W eb E-m ail

(510) 226-7333 (800) 829-8890 (510) 226-7350 w w w .e c su sa .c o m i n f o @e c su sa .c o m

On e of th e largest Taiwan -based PC m oth erboard m an u factu rers. Endl Publicat ions 14426 Black W aln u t Ct. Saratoga, CA 95070 Ph on e Fax FAXBack E-m ail

(408) 867-6642 (408) 867-2115 (408) 741-1600 2 5 0 1 7 5 2 @m c l m a i l .c o m

Pu blish es th e SSF Reflector, con tain in g sp ecs for local bu s d isk d rive attach m en ts. Also p u blish es SCSI tech n ical d ocu m en tation su ch as The SCSI Bench Reference an d The SCSI Encyclopedia. Epson Am erica, Inc. ( OEM Division) 20770 Mad ron a Ave. Torran ce, CA 90509-2842 Ph on e Fax FAXBack BBS W eb

(310) 787-6300 (310) 782-5350 (800) 922-8911 (408) 782-4531 w w w .e p so n .c o m

Man u factu res p rin ters an d com p lete PCcom p atible system s. Everex Syst em s, Inc. 5020 Bran d in Ct. Frem on t, CA 94538 Ph on e Sales Tech Su p p ort Fax BBS W eb

(510) 498-1111 (800) 821-0806 (510) 498-4411 (510) 683-2062 (510) 226-9694 w w w .e v e re x .c o m

Man u factu res PC-com p atible system s an d p erip h erals. Exabyt e Corporat ion 1685 38th St. Bou ld er, CO 80301 Ph on e Fax W eb

(303) 442-4333 (303) 417-7170 w w w .e x a b y t e .c o m

Man u factu res h igh -p erform an ce 8m m an d m in icartrid ge tap e-backu p system s an d 8m m an d 4m m tap e libraries. Also p rod u ces th e Eagle Nest m od u lar storage system s. Ext ron Elect ronics 1230 S. Lewis St. An ah eim , CA 92805 Ph on e Sales Fax W eb

(714) 491-1500 (800) 633-9876 (714) 491-1517 w w w .e x t ro n .c o m

Man u factu res com p u ter-vid eo in terface p rod u cts u sed to con n ect PCs to largescreen vid eo p rojectors an d m on itors. Th e com p an y also m an u factu res VGA, Mac, an d RGB d istribu tion am p lifiers an d switch ers u sed to con n ect m u ltim ed ia classroom an d board room eq u ip m en t, an d VGA- an d Mac-to-NTSC/ PAL con verters for record in g com p u ter in form ation an d grap h ics on vid eotap e. Fant asy Product ions ( A Division of Fort ner & Associat es) 1305 Bert St. Clarem ore, OK 74017 Ph on e Sales Tech Su p p ort

(918) 341-4577 (800) 358-5887 (918) 341-4577

Th e sou rce for d iscon tin u ed IBM referen ce m an u als an d tech n ical su p p ort. Call for a com p lete listin g.

ForeFront Direct

FCI Elect ronics - Am erica 50 Gru m bach er Road York, PA 17402 Ph on e Fax

(717) 767-8492 (717) 767-8056 (Attn : Scott Rolan d )

Man u factu res electron ic con n ector p rod u cts for p ortable an d d esktop PCs an d workstation s. Fedco Elect ronics, Inc. 1363 Cap ital Drive Fon d d u Lac, W I 54937 Ph on e Sales Fax

(414) 922-6490 (800) 542-9761 (414) 922-6750

Man u factu res an d su p p lies a large variety of com p u ter batteries. Fessenden Technologies 116 N. 3rd St. Ozark, MO 65721 Ph on e Fax W eb E-m ail

(417) 485-2501 (417) 485-3133 w w w .o z n e t .c o m / f e sse n d e n / 7 6 6 6 0 .1 0 3 5 @Co m p u se rv e .c o m

Service com p an y th at offers m on itor an d term in al d ep ot rep air. Th ey also rep air h ard d rives for old er Seagate an d Min iscribe MFM/ RLL d rives. First Int ernat ional Com put er, Inc. ( FIC) 980-A Mission Ct. Frem on t, CA 94539 Ph on e Sales Fax W eb

(510) 252-7777 (800) FICA-OEM (342-2636) (510) 252-8888 w w w .f i c a .c o m

Th e largest Taiwan -based m an u factu rer of PC-com p atible m oth erboard s.

Fluke, John M anufact uring Com pany, Inc. 6920 Seaway Blvd . P.O. Box 9090 Everett, W A 98206-9090 Ph on e Sales Fax W eb

(206) 347-6100 (800) 443-5853 (206) 356-5019 w w w .f l u k e .c o m

Man u factu res a lin e of h igh -en d d igital trou blesh ootin g tools, in clu d in g th e Scop em eter h an d h eld scop e. Folio Corporat ion 5072 N. 300 W . Provo, UT 84604 Ph on e Fax Sales W eb

(801) 229-6700 (801) 229-6787 (800) 543-6546 w w w .f o l i o .c o m

Man u factu res th e Folio VIEW S in fobase software. Also p u blish es th e an n u al COMDEX exh ibitors’ list on d isk. ForeFront Direct 25400 U.S. High way 19 North Su ite 285 Clearwater, FL 33763 Sales Su p p ort W eb

(800) 475-5831 (813) 725-2755 w w w .f f g .c o m

Makers of train in g software an d vid eos for PC tech n ician s an d d iagn ostic an d trou blesh ootin g h ard ware an d software.

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Fujit su Com put er Product s of Am erica, Inc. 2904 Orch ard Dr. San Jose, CA 95134-2009 Ph on e Fax W eb

(800) 626-4686 (408) 432-6333 w w w .f c p a .c o m

Man u factu res a lin e of h igh -cap acity h ard d isk d rives. Also m an u factu res scan n ers, laser an d d ot-m atrix p rin ters, rewritable op tical d rives, an d h igh -en d tap e d rives. Fut ure Dom ain Corporat ion ( Purchased by Adapt ec) 691 Sou th Milp itas Blvd . Milp itas, CA 95035 Sales Tech Su p p ort CD Record able Software Tech Su p p ort Fax BBS W eb

(800) 959-7274 (408) 934-7274 (408) 934-7283 (408) 957-6776 (408) 945-7727 w w w .a d a p t e c .c o m

Man u factu res a lin e of h igh -p erform an ce SCSI h ost ad ap ters an d software. Acq u ired by Ad ap tec. Gat ew ay 2000 P.O. Box 2000 610 Gateway Dr. North Siou x City, SD 57049 Ph on e Sales Tech Su p p ort Fax BBS W eb

(605) 232-2000 (800) 523-2000 (800) 846-2000 (605) 232-2023 (605) 232-2224 w w w .g w 2 k .c o m

Man u factu res a p op u lar lin e of PC system s sold by m ail-ord er an d n ew ou tlet stores in som e cities.

Gazelle/ GTM Soft w are P.O. Box 1930 Orem , UT 84059 Ph on e Fax W eb

(801) 235-7000 (801) 235-7099 w w w .g t m so f t w a re .c o m

Man u factu res th e Op tu n e d isk d efragm en ter an d d isk p erform an ce u tility p rogram . Giga-Byt e Technology Co., Lt d. 18305 Valley Blvd ., Ste. A LaPu en te, CA 91744 Ph on e Fax W eb

(626) 854-9338 (626) 854-9339 w w w .g i g a -b y t e .c o m

On e of th e top 10 largest Taiwan -based m oth erboard m an u factu rers. GigaTrend, Inc. 2234 Ru th erford Rd . Carlsbad , CA 92008 Ph on e Sales Fax BBS W eb

(760) 931-9122 (800) 743-4442 (760) 931-9959 (760) 931-9469 w w w .g i g a t re n d .c o m

Man u factu res h igh -cap acity tap e d rives. Global Engineering Docum ent s 15 In vern ess W ay East En glewood , CO 80112-5704 Ph on e Sales Fax W eb

(303) 792-2181 (800) 854-7179 (303) 792-2192 g l o b a l .i h s.c o m

A sou rce for variou s ANSI an d oth er in d u stry stan d ard d ocu m en ts, in clu d in g SCSI-1, 2, an d 3, ATA IDE, ESDI, an d m an y oth ers. Un like ANSI, th ey sell d raft d ocu m en ts of stan d ard s th at are n ot yet fu lly ANSI ap p roved .

Hayes M icrocomputer Products

Globe M anufact uring, Inc. 1159 Rou te 22 Mou n tain sid e, NJ 07092 Ph on e Sales Fax W eb

(908) 232-7301 (800) 227-3258 (908) 232-4729 w w w .a k st a m p i n g .c o m

Man u factu res assorted PC ad ap ter card brackets. Golden Bow Syst em s P.O. Box 3039 San Diego, CA 92163-1039 Ph on e Sales Fax W eb

(619) 298-9349 (800) 284-3269 (619) 298-9950 w w w .g o l d e n b o w .c o m

lates. Th ey also m an u factu re room tem p eratu re, h eat-cu red , UV-cu red system s, an d circu it board fabrication m aterials. Th ese in clu d e sold er m ask, sold er resist, an d p olym er th ick film s. GSI, Inc. 17951-H Skyp ark Circle Irvin e, CA 92614-6343 Ph on e Sales Su p p ort Fax W eb

(714) 261-7949 (800) 486-7800 (714) 757-9744 (714) 757-1778 w w w .g si -i n c .c o m or w w w .h o t p o rt .c o m

Man u factu res VOPT, th e best an d fastest d isk op tim izer software available. Th ey also offer Vcach e, VQ , an d VLock.

Develop s an d m an u factu res in tern al an d extern al EIDE solu tion s. Also m an u factu res flop p y, tap e, an d I/ O ad ap ters for u p grad in g old er PCs. New p rod u cts are cable select (CSEL) cables an d Hotp ort extern al IDE con n ectivity solu tion s.

GoldSt ar Technology, Inc. 1000 Sylvan Ave. En glewood Cliffs, NJ 07632

Hauppauge Com put er W orks, Inc. 91 Cabot Ct. Hau p p au ge, NY 11788

Ph on e Fax

Ph on e (516) 434-1600 Sales (800) 443-6284 Cu stom er Service (516) 434-3197 Fax (516) 434-3198 BBS (516) 434-8454 W eb w w w .h a u p p a u g e . c o m / h c w / i n d e x .h t m

(201) 816-2000 (201) 816-0636

Man u factu res a lin e of color m on itors an d a fu ll lin e of com p u ter an d electron ics p rod u cts. GRACE Specialt y Polym ers/ W R GRACE, Em erson & Cum ing, Inc. 869 W ash in gton St. Can ton , MA 02021 Ph on e Sales Tech Su p p ort Ord ers Fax

(617) (800) (800) (800) (617)

828-3300 472-2391 832-4929 225-9936 828-3104

Man u factu res stru ctu rally, th erm ally, an d electron ically con d u ctive ep oxy an d silicon e ad h esives, coatin gs, an d en cap su -

Man u factu res vid eo cap tu re card s. Hayes M icrocom put er Product s 5835 Peach tree Corn ers East Norcross, GA 30092-3405 Ph on e Sales Fax FAXBack BBS W eb

(770) 840-9200 (800) 874-3734 (770) 441-1213 (800) 429-3739 (770) 429-3734 w w w .h a y e s.c o m

Man u factu res a com p lete lin e of m od em s.

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Appendix A—Vendor List

Heat hkit Educat ion Syst em s Heath Com p an y 455 Riverview Dr. Ben ton Harbor, MI 49023 Ph on e Sales Fax W eb

(616) 925-6000 (800) 253-0570 (616) 925-2982 w w w .h e a t h k i t .c o m

Sells cou rses an d train in g m aterials for learn in g electron ics an d com p u ter d esign in clu d in g A+ Certification for Com p u ter Tech n ician s. Helm , Inc. Pu blication s Division P.O. Box 07130 Detroit, MI 48207 Ph on e Fax

(313) 865-5000 (313) 865-5927

Pu blish es Gen eral Motors service m an u als an d d ocu m en tation . Hew let t -Packard Com pany 800 Sou th Taft Lovelan d , CO 80537 Ph on e Fax W eb

(970) 635-1500 (970) 667-0997 w w w .h p .c o m / st o ra g e /

Man u factu res tap e-backu p su bsystem s, sp ecializin g in Travan , SCSI, IDE, an d flop p y-based system s th at attach via an in terface card , flop p y con troller, or p arallel p ort con n ection . Hew let t -Packard ( Disk M em ory Division) 1311 Ch in d en Blvd . Boise, ID 83714 Sales Ph on e Fax W eb

(800) 826-4111 (208) 396-6000 (208) 396-2896 w w w .h p .c o m

Man u factu res h igh -cap acity 3 1/ 2-in ch h ard d isk d rives. Hew let t -Packard ( St orage Division) 800 S. Taft Ave. Lovelan d , CO 80537 Ph on e Fax

(970) 635-1500 (970) 667-0997

Man u factu res tap e-backu p su bsystem s sp ecializin g in Travan , SCSI, an d flop p y system s th at attach th rou gh an in terface card , flop p y con troller, or p arallel p ort con n ection . Hit achi Am erica, Lt d. ( Sem iconduct or & IC Division) 2000 Sierra Poin t Pkwy. Brisban e, CA 94005 Ph on e Fax W eb

(650) 589-8300 (650) 583-4207 w w w .h i t a c h i .c o m

Man u factu res a variety of m em ory an d oth er sem icon d u ctor d evices. Also m an u factu res com p u ter p erip h erals, in clu d in g Office au tom ation , d igital grap h ics p rod u cts, an d LCD d evices. Hypert ech 1910 Th om as Rd . Mem p h is, TN 38134 Ph on e Fax

(901) 382-8888 (901) 373-5290

Man u factu res an d sells a wid e variety of well-en gin eered , h igh -p erform an ce au tom otive com p u ter EPROM rep lacem en ts for m an y d ifferen t typ es of veh icles. Also m akes th e Power Program m er for rep rogram m in g veh icle PCMs with EEPROMs (Flash ROMs).

IBM PC Direct

Hyundai Elect ronics Am erica 3101 N. 1st St. San Jose, CA 95134

IBM OEM Division 44 S. Broad way Rd . W h ite Plain s, NY 10601

Ph on e W eb

Ph on e

(408) 232-8000 w w w .h e a .c o m

Man u factu res PC-com p atible system s. Hyu n d ai also m akes m on itors, m em ory, ch ip s, an d oth er p erip h erals. IBM Fullfilm ent Cent er P.O. Box 1900 Dep t EZE/ 010J Bou ld er, CO 80303 Ph on e (800) 426-7282 Develop er Con n ection (800) 633-8266 Th e sou rce for OS/ 2 software d evelop er kits, reseller literatu re, an d ord ers for server gu id es. IBM M icroelect ronics 3605 Hwy. 52 North Roch ester, MN 55901 Ph on e Fax W eb

(507) 253-4011 (507) 253-3256 w w w .c h i p s.i b m .c o m

Th e IBM d ivision resp on sible for d evelop m en t, m an u factu rin g, an d m arketin g of sem icon d u ctor an d electron ic p ackagin g p rod u cts, services, an d solu tion s. IBM Nat ional Publicat ions 4800 Falls of Th e Neau se Raleigh , NC 27609 Ph on e Fax

(800) 879-2755 (800) 445-9269

Th e sou rce for cu rren t books, referen ce m an u als, d ocu m en tation , software toolkits, an d lan gu age p rod u cts for IBM system s. For d iscon tin u ed p u blication s, con tact Fan tasy Prod u ction s or An n abooks.

(914) 288-3000

Man u factu res an d d istribu tes IBM p rod u cts su ch as h igh -cap acity 3 1/ 2-in ch h ard d isk d rives, n etworkin g, an d ch ip set p rod u cts. IBM Part s Order Cent er 6300 Diagon al High way Bou ld er, CO 80301 Ph on e

(303) 924-6300 (Ord ers)

IBM’s n ation wid e service p arts ord erin g cen ter. IBM PC Com pany 11400 Bu rn et Rd . Au stin , TX 78758 Ph on e Sales FAXBack BBS W eb

(512) 823-0000 (800) IBM-3333 (800) 426-4329 (919) 517-0001 w w w .i b m .c o m

Man u factu res an d su p p orts IBM p erson al com p u ters. IBM PC Direct 3039 Corn wallis Rd . Bu ild in g 203 Research Trian gle Park, NC 27709-9766 Sales

(800) IBM-2YOU (426-2968) Can ad a Sales (800) 465-7999 Fax (800) 426-4182 Gen eral In form ation (800) 426-3332 Tech Su p p ort (800) 772-2227 Ord ers (800) 426-2968 W eb w w w .p c .i b m .c o m IBM PC Com p an y’s d irect m ail-ord er catalog sales d ivision . Th ey sell IBM an d ap p roved th ird -p arty system s an d p erip h erals at a d iscou n t from list p rice, an d p u blish a catalog listin g all item s.

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IBM Personal Systems Technical Solutions

M agazine NCM P.O. Box 165447 Irvin g, TX 75016 Sales Ph on e Fax

(800) 678-8014 (972) 550-0433 (972) 518-2507

Pu blish es an excellen t bim on th ly m agazin e coverin g IBM p erson al com p u ter system s an d software. Illinois Lock 301 W est Hin tz Rd . W h eelin g, IL 60090-5754 Ph on e Fax E-m ail

(847) 537-1800 (847) 537-1881 i i l l o c k @a o l .c o m

Man u factu res keylocks u sed in m an y d ifferen t PC system s. Inform at ion Access Com pany On e Park Ave. New York, NY 10016 Ph on e W eb

(212) 503-4400 w w w .i a c n e t .c o m

Man u factu res th e Com p u ter Library an d Com p u ter Select CD-ROM in form ation d atabases. InfoWorld M agazine

375 Coch itu ate Rd . Fram in gh am , MA 01701 Ph on e Sales Fax W eb

(508) 879-0700 (800) 227-8365 (508) 879-0446 w w w .i n f o w o rl d .c o m

Featu res excellen t p rod u ct reviews. Inline, Inc. 22860 Savi Ran ch Pkwy. Yorba Lin d a, CA 92887

Ph on e Sales Fax

(714) 921-4100 (800) 882-7117 (714) 921-4160

Man u factu res a com p lete lin e of vid eocon n ection accessories, in clu d in g d istribu tion am p lifiers, scan con verters, lin e d rivers, p rojector in terfaces, an d cables. Th ey also offer in teractive train in g system s for com p u ter-based train in g facilities. Innerw orks Technology, Inc. 319 Su n d an ce Dr. Bartlett, IL 60103 Man u factu res an excellen t PC d iagn ostic p rogram called th e Th ird Degree. Int egrat ed Device Technology, Inc. 2975 Sten d er W ay San ta Clara, CA 95054-3090 Ph on e Sales W eb

(408) 727-6116 (800) 345-7015 w w w .i d t .c o m

Man u factu res ch ip sets an d oth er sem icon d u ctor d evices. Int el Corporat ion 2200 Mission College Blvd . San ta Clara, CA 95054-1537 Ph on e Cu stom er Service Tech Su p p ort Fax W eb

(408) 765-8080 (800) 468-3548 (800) 321-4044 (408) 765-9904 w w w .i n t e l .c o m

Man u factu res m icrop rocessors u sed in PC system s. Also m akes a lin e of m em ory an d accelerator board s, an d on e of th e m ost p op u lar lin es of PC-com p atible Pen tiu m , Pen tiu m Pro, an d Pen tiu m II m oth erboard s an d ch ip sets.

JDR M icrodevices

Int el PC and LAN Enhancem ent Product Division 5200 N.E. Elam You n g Pkwy. Hillsboro, OR 97124-6427 Ph on e Sales Cu stom er Service Tech Su p p ort Fax BBS

(503) (800) (800) (800) (503) (503)

629-7354 538-3373 321-4044 628-8686 264-7969 264-7999

Man u factu res OverDrive CPU u p grad es an d n etworkin g d evices. Int ernat ional Elect ronic Research Corp. ( IERC) 135 W . Magn olia Blvd . Bu rban k, CA 91502 Ph on e Fax W eb

(818) 842-7277 (818) 848-8872 w w w .i e rc d y a .c o m

Man u factu res a lin e of excellen t CPU h eat sin k p rod u cts, in clu d in g clip -on , lowp rofile m od els esp ecially for 486 an d Pen tiu m p rocessors th at d o n ot req u ire a sp ecial socket. Iom ega Corporat ion 1821 W est Iom ega W ay Roy, UT 84067 Ph on e Sales Fax BBS W eb

(801) 778-1000 (800) 777-6654 (801) 778-3461 (801) 778-5888 w w w .i o m e g a .c o m

Man u factu res th e Jaz, Ditto, an d Zip d rive rem ovable-cartrid ge d rives. IX M icro Solut ions, Inc. 2085 Ham ilton Ave, 3rd Floor San Jose, CA 95125 Ph on e (408) 369-8282 Sales Fax (408) 369-0128 W eb u se rs.a o l .c o m \ i m st e k su p

Man u factu res grap h ic accelerator ch ip s an d board s, an d ATM n etwork p rod u cts. J. Bond Com put er Syst em s 93 W . Mon tagu e Exp ressway Milp itas, CA 95035 Ph on e Fax W eb

(408) 946-9622 (408) 946-2898 w w w .jb o n d .c o m

Man u factu res PC m oth erboard s. Jam eco Com put er Product s 1355 Sh oreway Rd . Belm on t, CA 94002 Ph on e Sales Fax BBS W eb

(415) 592-8097 (800) 831-4242 (415) 592-2503 (415) 637-9025 w w w .ja m e c o .c o m

Su p p lies com p u ter com p on en ts, p arts, an d p erip h erals by m ail ord er. JC W hit ney & Com pany 1104 S. W abash Street Ch icago, IL 60605 Ph on e (312) 431-6100 Fax (312) 431-5625 W eb w w w .jc w h i t n e y u sa .c o m Distribu tes an en orm ou s collection of bargain -p riced tools an d eq u ip m en t. Its p rod u cts are p rim arily for au tom otive ap p lication s, bu t m an y of th e tools h ave u n iversal u ses. JDR M icrodevices 1850 S. 10th San Jose, CA 95112 Ph on e Sales BBS W eb

(408) 494-1400 (800) 538-5000 (408) 494-1430 w w w .jd r.c o m

A ven d or for ch ip s, d isk d rives, an d variou s com p u ter an d electron ic p arts an d com p on en ts.

1205

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Appendix A—Vendor List

Jensen Tools, Inc. 7815 S. 46th St. Ph oen ix, AZ 85044

Fax BBS W eb

Ph on e Sales Fax W eb

Man u factu res a variety of h igh -q u ality keyboard s an d m ice for PC-com p atible system s. Acq u ired th e Hon eywell Keyboard d ivision . Th e Hon eywell m ou se u ses revolu tion ary n ew tech n ology th at n ever n eed s clean in g an d works on an y su rface, u n like trad ition al ball an d roller m ice. Su p p lies Com p aq an d Microsoft with keyboard s.

(602) 968-6231 (800) 426-1194 (800) 366-9662 w w w .je n se n t o o l s.c o m

Catalog d istribu tor of n etworkin g tools an d PC test eq u ip m en t. JTS Corporat ion 166 Bayp oin t Pkwy. San Jose, CA 95134 Ph on e Fax W eb

(408) 468-1800 (408) 468-1801 w w w .jt sc o rp .c o m

Man u factu res a lin e of low-cost 3 1/ 2-in ch h ard d isk d rives. JVC Inform at ion Product s 5665 Corp orate Drive Cyp ress, CA 90630 Ph on e Sales Fax

(714) 816-6500 (714) 816-6519

Man u factu res CD-Record able an d CDROM d rives. Kensingt on Technology Group 2855 Cam p u s Dr. San Mateo, CA 94403 Ph on e Tech Su p p ort Reseller Su p p ort Fax W eb

(650) 572-2700 (800) 535-4242 (800) 280-8318 (650) 572-9675 w w w .k e n si n g t o n .c o m

Man u factu res an d su p p lies com p u ter accessories. Key Tronic Corporat ion P.O. Box 14687 Sp okan e, W A 99214 Ph on e Sales

(509) 928-8000 (800) 262-6006

(509) 927-5248 (509) 927-5288 w w w .k e y t ro n i c .c o m

Kingst on Technology Corporat ion 17600 Newh op e St. Fou n tain Valley, CA 92708 Ph on e Sales Fax W eb

(714) 435-2600 (800) 835-6575 (714) 435-2699 w w w .k i n g st o n .c o m

Th ey are th e world ’s largest ven d or of m em ory m od u les. Th ey also m an u factu re an excellen t lin e of d irect p rocessor u p grad e m od u les. Labconco Corporat ion 8811 Prosp ect Kan sas City, MO 64132 Ph on e Sales Fax

(816) 333-8811 (800) 821-5525 (816) 363-0130

Man u factu res a variety of clean room cabin ets an d clean ben ch es for u se in h ard d isk d rive an d oth er sen sitive com p on en t rep air. Labt ec Ent erprises, Inc. 1499 SE Tech Cen ter Place, Ste. 350 Van cou ver, W A 98683 Ph on e Fax W eb

(360) 896-2000 (360) 896-2020 w w w .l a b t e c .c o m

Im p orts am p lified sp eakers for m u ltim ed ia ap p lication s.

Longshine M icrosystems, Inc.

Lant ronix 15353 Barran ca Pkwy. Irvin e, CA 92718-2216

Libi Indust ries, Lt d. 1983 Marcu s Ave. Lake Su ccess, NY 11042

Ph on e Sales Fax W eb

Ph on e Fax W eb

(714) 453-3990 (800) 422-7055 (714) 453-3995 w w w .l a n t ro n i x .c o m

(516) 326-2000 (516) 326-1100 w w w .l i b i .c o m

Man u factu res a variety of n etwork h ard ware in clu d in g servers, brid ges, rep eaters, h u bs, con verters, an d tran sceivers.

Distribu tes a com p lete lin e of h ard ware an d software d iagn ostics, m em ory u p grad es, an d th e Mu ltim ed ia CPU Up grad e Kit.

Laser M agnet ic St orage 4425 Arrowswest Dr. Colorad o Sp rin gs, CO 80907

Liebert 1050 Dearborn Dr. Colu m bu s, OH 43229

Ph on e Fax BBS

Ph on e Sales Fax W eb

(719) 593-7900 (719) 599-8713 (719) 593-4081

Division of DPMG th at m an u factu res a variety of op tical an d tap e d isk p rod u cts. LearnKey, Inc. 1845 W . Su n set Blvd . St George, UT 84770 Ph on e Sales Fax W eb

(801) 674-9733 (800) 937-3279 (801) 674-9734 w w w .l e a rn k e y .c o m

Prod u ces an d d istribu tes th e h igh est q u ality com p u ter train in g vid eos. Lexm ark 740 New Circle Rd . Lexin gton , KY 40511 Ph on e Fax BBS W eb

(606) 232-2000 (606) 232-3557 (606) 232-5238 w w w .l e x m a rk .c o m

Man u factu res IBM keyboard s an d p rin ters for retail d istribu tion . Sp u n off from IBM in 1991, n ow sells to oth er OEMs an d d istribu tors.

(614) 888-0246 (800) 877-9222 (614) 841-6022 w w w .l i e b e rt .c o m

Man u factu res a lin e of com p u ter p owerp rotection d evices. Liuski Int ernat ional 6585 Crescen t Dr. Norcross, GA 30071 Ph on e W eb

(770) 447-9454 w w w .l i u sk i .c o m

Hard ware d istribu tor th at carries a variety of p erip h erals an d system s. Th ey are th e exclu sive d istribu tor of Magitron ic PC system s an d m oth erboard s. Longshine M icrosyst em s, Inc. 10400-9 Pion eer Blvd . San ta Fe Sp rin gs, CA 90670 Ph on e Fax

(310) 903-0899 (310) 944-2201

Man u factu res PC in terface board s in clu d in g d isk con trollers, Su p er I/ O ad ap ters, n etwork card s, an d m ore.

1207

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Appendix A—Vendor List

Lot us Developm ent Corporat ion ( A Division of IBM ) 55 Cam brid ge Pkwy. Cam brid ge, MA 02142 Ph on e Cu stom er Service Fax BBS W eb

(617) 577-8500 (800) 343-5414 (617) 693-3899 (617) 693-7000 w w w .l o t u s.c o m

Man u factu res Lotu s 1-2-3, Sym p h on y, an d Magellan software. Acq u ired by IBM. LSI Logic, Inc. 1551 McCarth y Blvd . Milp itas, CA 95035 Ph on e Sales Fax W eb

(408) 433-8000 (800) 433-8778 (408) 433-2882 w w w .l si l o g i c .c o m

M AG InnoVision 2801 S. Yale St. San ta An a, CA 92704 Ph on e Sales Fax W eb

(714) 751-2008 (800) 827-3998 (714) 751-5522 w w w .m a g i n n o v i si o n .c o m

Man u factu res Flat Sq u are Tech n ology m on itors with ad van ced p erform an ce featu res. M AGNI Syst em s, Inc. 22965 NW Evergreen Pkwy. Hillsboro, OR 97124 Ph on e Sales Fax W eb

(503) 615-1900 (800) 624-6465 (503) 615-1999 w w w .m a g n i sy st e m s.c o m

Man u factu res m oth erboard logic an d ch ip sets.

Man u factu res a lin e of p rod u cts for con vertin g VGA grap h ics screen s to eith er NTSC (VHS) or S-vid eo (S-VHS).

M a Laborat ories, Inc. 1972 Con cou rse Dr. San Jose, CA 95131

M apInfo Corporat ion On e Global View Troy, NY 12180

Ph on e Fax W eb

Ph on e Fax Sales W eb

(408) 954-8188 (408) 954-0944 w w w .m a l a b s.c o m

Man u factu res an d su pplies CPUs an d SIMMs, PC boards, h ard disk drives, floppy drives, m oth erboards, an d m ath coprocessors. Th ey also m an u factu re a du m m y parity ch ip th at allows fake parity SIMMs to be con stru cted, wh ich th ey also sell. M acw orld Com m unicat ions, Inc. 501 Secon d St. San Fran cisco, CA 94107 Ph on e Fax W eb

(415) 243-0505 (415) 442-1891 m a c w o rl d .z d n e t .c o m

Prod u ces an excellen t p u blication coverin g n ews in th e Macin tosh u n iverse.

(518) 285-6000 (518) 285-6070 (800) 552-2511 w w w .m a p i n f o .c o m

Prod u ces d esktop , em bed d ed object, an d In tern et/ in tran et m ap p in g software an d d ata for p u blic an d p rivate sector in form ation d iscovery. M at rox Graphics, Inc. 1025 St. Regis Blvd . Dorval, PQ H9P 2T4 Can ad a Ph on e Fax Sales W eb

(514) 969-6300 (514) 969-6363 (514) 969-6330 w w w .m a t ro x .c o m

Man u factu res a lin e of h igh -p erform an ce PC grap h ics ch ip sets an d ad ap ters.

M egahertz Corporation (A Division of 3Com)

M axell Corporat ion of Am erica 22-08 Rou te 208 Fair Lawn , NJ 07410 Ph on e Fax

(800) 533-2836 (201) 796-8790

Man u factu res m agn etic m ed ia p rod u cts, in clu d in g d isks an d tap e cartrid ges, as well as op tical p rod u cts, in clu d in g CD-R m ed ia. M axi Sw it ch, Inc. 2901 East Elvira Rd . Tu cson , AZ 85706 Ph on e Fax BBS W eb

(602) 294-5450 (602) 294-6890 (602) 741-9230 w w w .m a x i sw i t c h .c o m

Man u factu res a lin e of h igh -q u ality PC keyboard s, in clu d in g som e d esign ed for h arsh or in d u strial en viron m en ts an d p rogram m able keyboard s. Maxi Switch keyboard s are u sed by m an y com p atible system m an u factu rers, in clu d in g Gateway 2000. M axopt ix Corporat ion 3342 Gateway Blvd . Frem on t, CA 94538 Ph on e Toll Free Fax BBS W eb E-m ail

(510) 353-9700 (800) 848-3092 (510) 353-1845 (510) 353-1448 w w w .m a x o p t i x .c o m m a x sa l e s@m a x o p t i x .c o m

A lead in g su p p lier of h igh -p erform an ce 5.25-in ch m agn eto-op tical d rives, ju keboxes, an d m ed ia. Join t ven tu re with Maxtor an d Ku bota Corp oration s. M axt or Corporat ion 211 River Oaks Pkwy. San Jose, CA 95134

Ph on e Sales Fax BBS W eb

(408) 432-1700 (800) 262-9867 (408) 432-4510 (303) 678-2222 w w w .m a x t o r.c o m

Man u factu res a lin e of large-cap acity, h igh -q u ality h ard d isk d rives. M cAfee Associat es 2710 W alsh Ave. San ta Clara, CA 95051 Ph on e Sales Fax BBS W eb

(408) 988-3832 (800) 707-1274 (408) 970-9727 (408) 988-4044 w w w .m c a f e e .c o m

Man u factu res th e fam ou s McAfee an tiviru s software an d a d iagn ostic p rogram called PC Med ic 97. M cKenzie Technology 910 Page Ave. Frem on t, CA 94538 Ph on e Fax

(510) 651-2700 (510) 651-1020

Man u factu res sockets for p rocessors an d IC ch ip s. M egahert z Corporat ion ( A Division of 3Com ) 605 N 5600 W Salt Lake City, UT 84116 Ph on e Sales FAXBack Fax W eb

(801) 320-7000 (800) 527-8677 (800) 856-1045 (801) 320-6022 w w w .m e g a h e rt z .c o m

Man u factu res lap top m od em s an d extern al n etwork ad ap ters. Also m akes AT-sp eed u p p rod u cts.

1209

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Appendix A—Vendor List

M erisel 200 N. Con tin en tal Blvd . El Segu n d o, CA 90245

M icro 2000, Inc. 1100 E. Broad way, 3rd Floor Glen d ale, CA 91205

Ph on e Sales Cu stom er Service Fax W eb

Ph on e Fax W eb

(310) 615-3080 (800) 542-9955 (800) 462-5241 (800) 845-3744 w w w .m e ri se l .c o m

W orld ’s largest d istribu tor of PC h ard ware an d software p rod u cts from m an y m an u factu rers. M erit ec 1359 W est Jackson St. P.O. Box 8003 Pain esville, OH 44077 Ph on e Fax Sales W eb

(440) 354-3148 (440) 354-0509 (800) 627-7752 w w w .m e ri t e c .c o m

Man u factu res a lin e of SCSI 8-bit to 16-bit (W id e SCSI) ad ap ters in a variety of con figu ration s. Th ese ad ap ters allow W id e SCSI d evices to be in stalled in a stan d ard 8-bit SCSI bu s an d vice versa. M errit t Com put er Product s, Inc. 5565 Red Bird Cen ter Dr., #150 Dallas, TX 75237 Ph on e Fax

(214) 339-0753 (214) 339-1313

Man u factu res th e SafeSkin keyboard p rotector. M et hode Elect ronics, Inc. DataMate Division 7444 W . W ilson Ave. Ch icago, IL 60656 Ph on e Fax web

(708) 867-9600 (708) 867-3149 w w w .m e t h o d e .c o m

Man u factu res an d sells a com p lete lin e of SCSI term in ators.

(818) 547-0125 (818) 547-0397 w w w .m i c ro 2 0 0 0 .c o m

Man u factu res th e MicroScop e PC d iagn ostics p rogram an d th e POSTProbe ISA, EISA, an d MCA POST d iagn ostics card . M icro Accessories, Inc. 6036 Stewart Ave. Frem on t, CA 94538 Ph on e Sales Fax W eb

(510) 226-6310 (800) 777-6687 (510) 226-6316 w w w .m i c ro -a .c o m

Man u factu res a variety of cables an d d isk d rive m ou n tin g brackets an d accessories, in clu d in g PS/ 2 ad ap ter kits. M icro Channel Developers Associat ion 169 Hartn ell Ave., Ste. 200 Red d in g, CA 96002 Ph on e Sales Fax W eb

(916) 222-2262 (800) GET-MCDA (438-6232) (916) 222-2528 w w w .m i c ro c h a n n e l .i n t e r .n e t / m i c ro c h a n n e l

An in d ep en d en t organ ization establish ed to facilitate th e evolu tion an d su p p ort of th e Micro Ch an n el Arch itectu re (MCA). Th e association also p rovid es m icroch an n el p rod u cts d irect to en d u sers. Th ey p u blish th e International Catalog of Micro Channel Products and Services.

M icro Solutions, Inc.

M icro Com put er Cable Com pany, Inc. 12200 Delta Dr. Taylor, MI 48180 Ph on e Fax W eb

(313) 946-9700 (313) 946-9645 w w w .m i c ro c c c .c o m

Man u factu res an d sells a com p lete lin e of com p u ter cables, con n ectors, switch boxes, an d cablin g accessories. M icro Design Int ernat ional ( M DI) 6985 Un iversity Blvd . W in ter Park, FL 32792 Ph on e Sales Fax BBS W eb

(407) 677-8333 (800) 228-0891 (407) 677-8365 (407) 677-4854 w w w .m d i .c o m

Man u factu res th e SCSI Exp ress d river software for in tegration of SCSI p erip h erals in a variety of en viron m en ts. Recen tly acq u ired PC-Kwik Corp oration . M icro Firm w are, Inc. 330 W est Gray St., Ste. 170 Norm an , OK 73069-7111 Sales Fax BBS W eb

(800) 767-5465 (405) 573-5535 (405) 573-5538 w w w .f i rm w a re .c o m

Th e largest d istribu tor of Ph oen ix ROM BIOS u p grad es. Develop s cu stom version s for sp ecific m oth erboard s an d su p p lies m an y oth er BIOS ven d ors with p rod u cts. M icro House Int ernat ional 2477 N. 55th St. Bou ld er, CO 80301 Ph on e Sales Fax BBS W eb

(303) 443-3388 (800) 926-8299 (303) 443-3323 (303) 443-9957 w w w .m i c ro h o u se .c o m

Pu blish es th e Micro Hou se Tech n ical Library on CD-ROM. Th e tech n ical library is a W in d ows-com p atible referen ce tool d esign ed for PC service tech n ician s th at covers ad ap ter card s, n etwork card s, m oth erboard s, an d d isk d rives. Also p rod u ces DrivePro, EZ Drive, EZ Cop y, an d m an y oth er h ard -d rive form attin g an d p rotection p rod u cts. EZ Drive is th e u tility sh ip p ed with m an y of th e n ew large IDE h ard d rives (allows byp ass of th e BIOS). M icro Indust ries Corporat ion 8399 Green Mead ows Dr. North North W esterville, OH 43081-9486 Ph on e (614) 548-7878 Fax (614) 548-6184 W eb w w w .m i c ro i n d u st ri e s.c o m Man u factu res PC-com p atible m oth erboard s. M icro Solut ions, Inc. 132 W . Lin coln Hwy. DeKalb, IL 60115 Ph on e Sales Fax W eb

(815) 756-3411 (800) 890-7227 (815) 756-9100 w w w .m i c ro -so l u t i o n s.c o m

Man u factu res a com plete lin e of floppy con trollers an d su bsystem s, in clu din g 2.88M version s. Also offers floppy drive an d tape-backu p system s th at ru n from a stan dard parallel port, u sin g n o expan sion slots. Also m akes th e backpack lin e of h ard drives, CD-ROMS, disk drives, an d tape drives.

1211

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Appendix A—Vendor List

M icro Solut ions, Inc. 40 Old Rid gebu ry Rd ., Ste. 106 Dan bu ry, CT 06810 Ph on e Fax W eb

(203) 748-4633 (203) 797-9849 w w w .m i c so l .c o m

A Prem ier Service cen ter for Tosh iba Am erica, specializin g in sales, service, an d upgrades for laptop an d portable com puters. M icro W arehouse 535 Con n ecticu t Ave. Norwalk, CT 06854 Ph on e Fax Sales W eb

(203) 899-4000 (203) 853-2267 (800) 547-5444 w w w .w a re h o u se .c o m

Distribu tes a large variety of com p u ters, com p u ter su p p lies, flop p y d isks, cables, an d so on . M icrocom , Inc. 500 River Rid ge Dr. Norwood , MA 02062 Ph on e Sales Fax W eb

(781) 551-1000 (800) 822-8224 (781) 255-1125 w w w .m i c ro c o m .c o m

Man u factu res error-correctin g m odem s an d rem ote access produ cts; created an d develops th e MNP com m u n ication s protocols. M icroDat a Corporat ion 2727 Ulm erton Road , Ste. 300 Clearwater, FL 33762 Ph on e Fax W eb

(800) 539-0123 (813) 573-5900 (813) 572-5085 w w w .q u i c k t e c h .c o m

Man u factu res an d d istribu tes a com p lete lin e of h ard ware an d software d iagn ostic tools in clu d in g Ultra-X, Qu ickTech PRO,

Qu ickTech 98, P.H.D. Plu s, Th e Exam in er, an d P.C. In sp ector. M icrografx, Inc. 1303 E. Arap ah o Rd . Rich ard son , TX 75081 Ph on e Sales an d Cu stom er Service Tech Su pport Fax BBS W eb

(972) 234-1769 (800) 733-3729 (972) 234-2694 (972) 994-6476 (972) 644-4194 w w w .m i c ro g ra f x .c o m

Man u factu res th e Micrografx Design er, W in d ows Draw, ABC Toolkit, Ph otom agic, an d Ch arism a software. Sp ecializes in W in d ows an d OS/ 2 d evelop m en t. M icron Technologies ( Parent Com pany of M icron Elect ronics and M icron Cust om M anufact uring) 8000 S. Fed eral W ay Boise, ID 83707 Ph on e Sales Fax BBS W eb

(208) 368-3900 (800) 388-6334 (208) 368-3809 (208) 368-4530 w w w .m i c ro n .c o m

Man u factu res variou s m em ory board s, m em ory ch ip s, SIMMs, DRAM, SRAM, an d oth er sem icon d u ctors, an d a lin e of PC system s. M icronics Com put ers, Inc. 45365 North p ort Loop W est Frem on t, CA 94538 Ph on e Fax Sales Tech Su p p ort FAXBack BBS W eb

(510) 651-2300 (510) 651-6692 (800) 577-0977 (510) 661-3000 (510) 661-3199 (510) 651-6837 w w w .m i c ro n i c s.c o m

Man u factu res PC m oth erboard s.

M icroWay, Inc.

M icropolis Corporat ion 21211 Nord h off St. Ch atsworth , CA 91311

M icroSyst em s Developm ent , Inc. 4100 Moorp ark Ave. #104 San Jose, CA 95117

Ph on e Sales Fax BBS

Ph on e Fax BBS W eb

(818) (800) (818) (818)

709-3300 395-DRIV (3748) 709-3396 709-3310

Man u factu red a lin e of h igh -cap acity 5 1/ 4- an d 3 1/ 2-in ch h ard d isk d rives. Recen tly acq u ired by Sin gap ore Tech n ologies an d sin ce liq u id ated . M icroprocessors Unlim it ed, Inc. 24000 S. Peoria Ave. Beggs, OK 74421 Ph on e Fax

(918) 267-4961 (918) 267-3879

Distribu tes m em ory ch ip s, SIMMs, m ath cop rocessors, UART ch ip s, an d oth er in tegrated circu its. M icrosoft Corporat ion On e Microsoft W ay Red m on d , W A 98052-6399 Ph on e Sales Fax BBS W eb

(425) 882-8080 (800) 426-9400 (425) 936-7329 (425) 936-6735 w w w .m i c ro so f t .c o m

(408) 296-4000 (408) 296-5877 (408) 296-4200 w w w .m sd .c o m / d i a g s

Man u factu res a lin e of excellen t h ard ware d iagn ostics p rod u cts in clu d in g Post Cod e Master, Port Test, an d Test Drive. M icrot est Ent erprises 22 Cotton Rd . Nash u a, NH 03063 Ph on e Sales Fax W eb

(603) 880-0300 (800) 880-5644 (603) 880-7229 w w w .m i c ro t e st .c o m

Man u factu rer of CD-ROM n etworkin g an d optical storage solu tion s for th e DOS, W in dows, W in dow 95, W in dows NT, an d Macin tosh en viron m en ts. Th e com pan y’s produ cts provide fast access to CD-ROM databases over a wide ran ge of n etworks an d tech n ologies in th e in du stry, featu rin g th e FastCD Person alEdition . FastCD h as been ren am ed Virtu al CD, wh ich also allows CD-based program s to be ru n from an y local or n etwork disk.

Man u factu res MS-DOS, W in d ows 9x, W in d ows NT, an d a variety of ap p lication s software.

M icroW ay, Inc. Research Park Box 79 Kin gston , MA 02364

M icro-St ar Int ernat ional 4059 Clip p er Ct. Frem on t, CA 94538

Ph on e BBS W eb

Ph on e Fax BBS W eb

Man u factu res a lin e of Digital Alp h a Based Scream er workstation s, an d NDP Fortran an d C com p ilers.

(510) 623-8818 (510) 623-8585 (510) 623-7398 w w w .a c h m e .c o m

On e of th e top 10 largest Taiwan -based m oth erboard m an u factu rers.

(508) 746-7341 (508) 746-7946 w w w .m i c ro w a y .c o m

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Appendix A—Vendor List

M ini M icro Supply 4900 Patrick Hen ry Dr., Bld g. B San ta Clara, CA 95054

M it sum i Elect ronics Corporat ion 5808 W . Cam p u s Circle Drive Irvin g, TX 75063

Ph on e Sales Fax BBS W eb

Ph on e Fax W eb

(408) 327-0388 (800) 275-4642 (408) 327-0389 (408) 434-9319 w w w .m i n i -m i c ro .c o m

Partly own ed by Green leaf Corp oration , a wh olesale d istribu tor of Con n er Perip h erals, In c. M it subishi Com put ers, Lt d. 3500 Parksid e Birm in gh am Bu sin ess Park Birm in gh am , B37 7YS En glan d Ph on e Fax W eb

+44 (121) 717-7171 +44 (021) 717-7799 w w w .m i t su b i sh i c o m p u t e rs.c o m

Man u factu res a p op u lar lin e of PC system s sold p rim arily in Eu rop e. Acq u ired by Mitsu bish i Electric in 1990. M it subishi Elect ronics Am erica, Inc. Electron ic Device Grou p 1050 E. Arq u es Ave. Su n n yvale, CA 94086 Ph on e Sales Tech Su p p ort W eb

(408) 730-5900 (800) 843-2515 (800) 344-6352 w w w .m i t su b i sh i c h i p s. co m

Man u factu res m on itors, p rin ters, an d con su m ables. For h ard d isks an d flop p y d isk storage p rod u cts, con tact th e Electron ic Device Grou p .

(214) 550-7300 (214) 550-7424 w w w .m i t su m i .c o m

Man u factu res a lin e of CD-ROM an d flop p y d rives an d keyboard s an d m ice. M olex, Inc. 2222 W ellin gton Ct. Lisle, IL 60532 Ph on e Sales Fax W eb

(630) 969-4550 (800) 78MOLEX (786-6539) (630) 969-2321 w w w .m o l e x .c o m

Man u factu res a variety of con n ectors u sed in PC system s. M osel Vit elic 3910 N. First St. San Jose, CA 95134 Ph on e Fax W eb

(408) 433-6000 (408) 433-0331 w w w .m o se l v i t e l i c .c o m

Man u factu res m em ory m od u les. M otor M agazine

Hearst Corp oration 645 Stewart Ave. Gard en City, NY 11530 Ph on e Sales Fax

(516) 227-1300 (800) 426-6867 (516) 227-1444

Th e essen tial trad e m agazin e for th e au tom otive tech n ician , in clu d in g trou blesh ootin g tip s an d service p rod u ct in form ation . Su bscrip tion s are free to th ose wh o q u alify.

National Semiconductor Corporation

M ot orola, Inc. Microp rocessor an d Mem ory Tech n ology Grou p 3501 Ed Blu estein Blvd . Au stin , TX 78762 Ph on e Sales Fax W eb

(512) 895-2000 (800) 521-6274 (512) 895-2652 w w w .m o t .c o m

Man u factu res PC m em ory in clu d in g fast static RAM for cach e. Also m akes th e Macin tosh , Power PC, an d Motorola p rocessors. M ount ain Net w ork Solut ions, Inc. ( Subsidiary of NCE St ar Solut ions) 9717 Pacific Heigh ts Blvd . San Diego, CA 92121 Ph on e Fax BBS

(800) 458-0300 (408) 438-7623 (408) 438-2665

Man u factu res tap e d rives an d backu p su bsystem s, in clu d in g h ard ware an d software. M ueller Technical Research 21 Sp rin g Lan e Barrin gton Hills, IL 60010 Ph on e Fax W eb E-m ail

(847) 854-6794 (847) 854-6795 w w w .m -t r.c o m sc o t t m u e l l e r@c o m p u se rv e . co m

You fou n d m e! I ru n a service com p an y th at offers th e best in cu stom on site PC h ard ware an d software tech n ical sem in ars an d train in g, sp ecializin g in all asp ects of PC h ard ware, software, an d d ata recovery. W e can p resen t a cu stom sem in ar for you r organ ization . Scott Mueller.

M ust ang Soft w are P.O. Box 2264 Bakersfield , CA 93303 Ph on e Sales Tech n ical Su p p ort Fax BBS W eb

(805) 873-2500 (800) 999-9619 (805) 873-2550 (805) 873-2599 (805) 873-2400 w w w .m u st a n g .c o m

Man u factu res W ild cat! BBS software. M ylex Corporat ion 34551 Ard en wood Blvd . Frem on t, CA 94555-3067 Ph on e Sales Fax W eb

(510) 796-6100 (800) 776-9539 (510) 745-8016 w w w .m y l e x .c o m

Man u factu res h igh -p erform an ce m oth erboard s, SCSI RAID, an d SCSI h ost ad ap ters. M yoda Com put er Cent ers 1070 N Roselle Rd . Hoffm an Estates, IL 60195 Ph on e Fax W eb

(847) 885-7600 (847) 885-7661 w w w .m y o d a .c o m

Assem bles PC system s for retail sale. Nat ional Sem iconduct or Corporat ion 2900 Sem icon d u ctor Dr. San ta Clara, CA 95051 Ph on e BBS W eb

(408) 721-5000 (408) 245-0671 w w w .n sc .c o m

Man u factu res a variety of ch ip s for PC circu it ap p lication s. Kn own esp ecially for its UART an d Su p er I/ O ch ip s.

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Appendix A—Vendor List

NCR M icroelect ronics 1635 Aerop laza Colorad o Sp rin gs, CO 80916 Ph on e Sales Fax BBS W eb

(719) 596-5795 (800) 334-5454 (719) 573-3286 (719) 574-0424 w w w .n c r.c o m

Man u factu res a variety of in tegrated circu its for PC system s, in clu d in g SCSI p rotocol ch ip s u sed by m an y OEMs. Th ey also sp on sor th e SCSI BBS, an excellen t sou rce for stan d ard d ocu m en ts coverin g SCSI, IDE, an d oth er in terfaces. NEC Elect ronics, Inc. 2880 Scott Blvd . San ta Clara, CA 95052 Ph on e W eb

(408) 588-6000 w w w .n e c .c o m

Man u factu res m em ory an d oth er sem icon d u ctor d evices. NEC Technologies, Inc. 1414 Massach u setts Ave. Boxborou gh , MA 01719 Ph on e Sales Fax BBS W eb

(978) 264-8000 (800) 632-4636 (978) 264-8245 (708) 860-2602 w w w .n e c .c o m

Man u factu res m u ltisyn c m on itors, CDROM d rives, vid eo ad ap ters, p rin ters, an d oth er p erip h erals as well as com p lete PCcom p atible system s. New ark Elect ronics 4801 N. Raven swood Ch icago, IL 60640-4496 Ph on e Fax W eb

(773) 784-5100 (773) 907-5217 w w w .n e w a rk .c o m

An electron ic com p on en t an d p rod u ct su p p lier with a h u ge catalog of p rod u cts. Its 1500+ p age catalog is an excellen t sou rce of com p on en ts an d in form ation . NexGen, Inc. ( A Division of AM D) 1623 Bu ckeye Dr. Milp itas, CA 95035 Ph on e W eb

(408) 260-0117 w w w .a m d .c o m

Man u factu red th e Nx586 fam ily of p rocessors, wh ich were m arketed as altern atives to th e In tel Pen tiu m fam ily. NexGen featu res are n ow in corp orated in to som e lin es of AMD p rocessors. Novell, Inc. 122 E. 1700 Sou th Provo, UT 84606 Ph on e Sales Tech Su p p ort BBS W eb

(801) 379-5588 (800) 526-7937 (800) 858-4000 (801) 429-3030 w w w .n o v e l l .c o m

Man u factu res th e NetW are LAN op eratin g system . Num ber Nine Visual Technology Corporat ion 18 Hartwell Ave. Lexin gton , MA 02173 Ph on e Fax BBS W eb

(781) 674-0009 (781) 674-2919 (781) 862-7502 w w w .n u m b e rn i n e .c o m

Man u factu res a lin e of h igh -en d PC vid eo grap h ics accelerator card s.

Opti, Inc.

nVidia Corporat ion 1226 Tiros W ay Su n n yvale, CA 94086 Ph on e Fax W eb E-m ail

(408) 617-4000 (408) 617-4100 w w w .n v i d i a .c o m i n f o @n v i d i a .c o m

Ph on e Sales Fax BBS W eb

(609) 235-2600 (800) OKIDATA (654-3282) (609) 222-5010 (800) 283-5474 w w w .o k i d a t a .c o m

Man u factu rer of p rin ters, faxes, an d m u ltifu n ction p erip h erals.

A lead in g p rovid er of 3D grap h ics p rocessors u sed in m an y OEM bran d ed grap h ics ad ap ters.

Olivet t i 765 U.S. Hwy. 202 Brid gewater, NJ 08807

Oak Technology, Inc. 139 Kifer Ct. Su n n yvale, CA 94086

Ph on e Fax W eb

Ph on e Fax BBS W eb

Man u factu res Olivetti an d m an y AT&T PC system s.

(408) 737-0888 (408) 737-3838 (408) 774-5308 w w w .o a k t e c h .c o m

Man u factu res sem icon d u ctors. Ocean Inform at ion Syst em s 688 Arrow Gran d Circle Covin a, CA 91722 Ph on e Fax W eb

(626) 339-8888 (626) 859-7668 w w w .o c e a n -u sa .c o m / o c e a n

Man u factu res h igh -p erform an ce PC m oth erboard s. OEM M agazine

CMP Pu blication s 600 Com m u n ity Dr. Man h asset, NY 11030 Ph on e W eb

(516) 562-5000 t e c h w e b .c m p .c o m / o e m

An excellen t m agazin e for th e system s in tegrator or system s assem bler. Free su bscrip tion for th ose wh o q u alify. Okidat a 532 Fellowsh ip Rd . Mou n t Lau rel, NJ 08054

(908) 526-8200 (908) 526-8405 w w w .o l i v e t t i .c o m

Ont rack Dat a Int ernat ional, Inc. ( Form erly Ont rack Com put er Syst em s) 6321 Bu ry Dr., Ste. 13-21 Ed en Prairie, MN 55346 Ph on e Fax Sales Tech Su p p ort BBS W eb

(612) 937-5161 (612) 937-5750 (800) 872-2599 (612) 937-2121 (612) 937-8567 w w w .o n t ra c k .c o m

Man u factu res th e Disk Man ager h ard d isk u tilities for PC, PS/ 2, an d Macin tosh . Disk Man ager is th e m ost com p reh en sive an d flexible low-level form at p rogram available, su p p ortin g even IDE d rives. Also p rovid es exten sive d ata recovery services. Opt i, Inc. 888 Tasm an Dr. Milp itas, CA 95035 Ph on e Sales Fax BBS W eb

(408) 486-8000 (800) 398-6784 (408) 486-8001 (408) 486-8051 w w w .o p t i .c o m

Man ufactures PC m oth erboard ch ipsets in cludin g th e Viper series for Pen tium system s.

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Appendix A—Vendor List

Orchid Technology ( A Division of M icronics) 45365 North p ort Loop W est Frem on t, CA 94538 Ph on e Cu stom er Service Sales Tech Su p p ort Fax FAXBack BBS W eb

(510) 683-0300 (800) 767-2443 (510) 651-2300 (510) 661-3000 (510) 651-5612 (510) 661-3199 (510) 651-6837 w w w .o rc h i d .c o m

Man u factu res a lin e of vid eo an d m em ory board p rod u cts for PC system s. Also p rod u ces 32-bit sou n d card s. Pacific Dat a Product s 9855 Scran ton Rd . San Diego, CA 92121 Ph on e Fax BBS

(619) 229-9900 (619) 552-0889 (619) 452-6329

Man u factu res th e Pacific Page XL an d Pacific Page PE PostScrip t-com p atible en h an cem en t p rod u cts for HP LaserJet p rin ters. Packard Bell 6041 Variel Aven u e W ood lan d Hills, CA 91367 Ph on e Service Sales Fax Cu stom er Service W eb

(818) (800) (818) (800)

673-4800 733-4411 673-4883 244-0049

w w w .p a c k a rd b e l l .c o m

Man u factu res a p op u lar lin e of low-cost PC-com p atible com p u ter system s. Palo Alt o Design Group 567 Un iversity Ave. Palo Alto, CA 94301

Ph on e W eb

(650) 327-9444 w w w .p a d g .c o m

Man u factu res en closu res th at accep t In tel ATX m oth erboard s. For OEMs. Panasonic Com m unicat ions & Syst em s 2 Pan ason ic W ay Secau cu s, NJ 07094 Ph on e W eb

(201) 348-7000 w w w .p a n a so n i c .c o m

Man u factu res m on itors, op tical d rive p rod u cts, flop p y d rives, p rin ters, an d PCcom p atible lap top system s. Panasonic Indust rial Co. 2 Pan ason ic W ay Secau cu s, NJ 07094 Ph on e

(201) 348-7000

Man u factu res IC m em ory card s; batteries (n ickel m etal h yd rid e); cellu lar com p on en ts (p lan ar filters an d reson ators); op tical an d flop p y d isk d rives; CD-ROM d rives; p rin ter m ech an ism s; p ower su p p lies (cu stom AC ad ap ters); sem icon d u ctors (vid eo d igital sign al p rocessors, CCD card cam eras); m icrop h on es; sp eakers; h igh resolu tion color m on itors; TV tu n ers; ceram ic receivers; an d vid eo cam era m od u les. Parallel Technologies, Inc. 4240 B Street NW Au bu rn , W A 98001 Ph on e Fax W eb

(253) 813-8728 (253) 813-3730 w w w .l p t .c o m

Man u factu res th e Parallel Port In form ation Utility an d a lin e of cables an d software su p p ortin g th e W in d ows 95 Direct Cable Con n ection (DCC). It sells a sp ecial Un iversal Cable offerin g th e h igh est p ossible sp eed con n ection u sin g DCC.

PC World M agazine

PARTS NOW !, Inc. 3517 W est Beltlin e Hwy. Mad ison , W I 53713

PC Pow er & Cooling, Inc. 5995 Aven id a En cin as Carlsbad , CA 92008

Ph on e Fax

Ph on e Sales Fax W eb

(608) 276-8688 (608) 276-9134

Sells a large variety of laser p rin ter p arts for HP, Can on , Ap p le, an d oth er laser p rin ters u sin g Can on en gin es. PC & M AC Connect ion 528 Rt 13 Sou th Milford , NH 03055 Ph on e Sales Fax W eb

(603) 446-7721 (800) 800-5555 (603) 446-7791 w w w .p c c o n n e c t i o n .c o m

Distribu tes m an y d ifferen t h ard ware an d software p ackages by way of m ail ord er. PC M agazine

Ziff-Davis Com m u n ication s Co. On e Park Ave. New York, NY 10016 Ph on e Fax W eb

(212) 503-3500 (212) 503-5799 w w w .z d n e t .c o m / p c m a g

Magazin e featu rin g p rod u ct reviews an d com p arison s. PC Port able M anufact urer, Inc. 1431 Potrero Ave., Un it E El Mon te, CA 91733 Ph on e Sales Fax

(616) 444-3585 (800) 966-7237 (616) 444-1027

Man u factu res a lin e of p ortable cases th at accep t stan d ard Baby-AT an d ATX m oth erboard s, wh ich are id eal for bu ild in g you r own p ortable system s.

(760) 931-5700 (800) 722-6555 (760) 931-6988 w w w .p c p o w e rc o o l i n g .c o m

Man u factu res a lin e of h igh -q u ality, h igh ou tp u t p ower su p p lies an d coolin g fan s for PC system s. Kn own for h igh -p ower ou tp u t an d q u iet fan op eration . PC Week M agazine

10 Presid en ts Lan d in g Med ford , MA 02155 Ph on e Fax W eb

(781) 393-3700 (781) 393-3859 w w w .z d n e t .c o m / p c w e e k

W eekly m agazin e featu rin g in d u stry n ews an d in form ation . PC World M agazine

P.O. Box 9208 Fram in gh am , MA 01701 Ph on e Fax W eb

(508) 820-0440 (508) 620-7739 w w w .p c w o rl d .c o m

A m on th ly m agazin e featu rin g p rod u ct reviews an d com p arison s.

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Appendix A—Vendor List

PCI Special Int erest Group 2575 NE Kath ryn #17 Hillsboro, OR 97124

Phoenix Technologies, Lt d. 411 East Plu m eria Drive San Jose, CA 95134

Ph on e Sales Fax W eb

Ph on e Fax BBS W eb

(503) 693-6232 (800) 433-5177 (503) 693-8344 w w w .p c i si g .c o m

(408) 570-1000 (408) 570-1001 (714) 440-8026 w w w .p h o e n i x .c o m

Form ed in Ju n e 1992, th e PCI SIG (Perip h eral Com p on en t In tercon n ect Sp ecial In terest Grou p ) is th e in d u stry organ ization th at own s an d m an ages th e PCI Local Bu s Sp ecification . More th an 500 in d u strylead in g com p an ies are active PCI SIG m em bers. Th e organ ization is ch artered to su p p ort n ew req u irem en ts, wh ile m ain tain in g backward com p atibility for all PCI revision s; m ain tain th e sp ecification as an easy-to-im p lem en t, stable tech n ology; an d con tribu te to th e tech n ical lon gevity of PCI an d its establish m en t as an in d u strywid e stan d ard .

Design s PC BIOS software for all typ es of PC system s an d p rocessors. Recen tly m erged with Award .

PCM CIA—Personal Com put er M em ory Card Int ernat ional Associat ion 2635 N. First St., Ste. 209 San Jose, CA 95134

PKW are, Inc. 9025 N. Deerwood Dr. Brown Deer, W I 53223

Ph on e Fax BBS W eb

(408) 433-2273 (408) 433-9558 (408) 433-2270 w w w .p c -c a rd .c o m

An in d ep en d en t organ ization th at m ain tain s th e PC card stan d ard for cred it card sized exp an sion ad ap ters. Philips Consum er Elect ronics P.O. Box 14810 On e Ph ilip s Dr. Kn oxville, TN 37914 Ph on e Fax W eb

(423) 521-4316 (423) 521-4586 w w w .m a g v a v o x .c o m

Man u factu res Magn avox PCs, m on itors, an d CD-ROM d rives.

Pivar Com put ing Services, Inc. 165 Arlin gton Heigh ts Rd . Bu ffalo Grove, IL 60089 Ph on e Sales Fax W eb

(847) 459-6010 (800) Con vert (266-8378) (847) 459-6095 w w w .c o n v e rt .c o m

Service com p an y th at sp ecializes in d ata an d m ed ia con version .

Ph on e Fax BBS W eb

(414) 354-8699 (414) 354-8559 (414) 354-8670 w w w .p k w a re .c o m

Origin ated an d in trod u ced th e Zip file com p ression form at. PKW are m an u factu res d ata com p ression p rod u cts su ch as PKZip , PKLite, an d th e PKW are Data Com p ression Library, wh ich are all available for m u ltip le op eratin g system s an d p rocessors. W id ely u sed on th e In tern et an d BBS System s, an d by m an u factu rers for software d istribu tion .

Public Software Library

Plext or 4255 Bu rton Dr. San ta Clara, CA 95054

Pract ical Enhanced Logic 22695 Old Can al Rd . Yorba Lin d a, CA 92887

Ph on e Sales Fax BBS W eb

Ph on e Fax Sales W eb

(408) 980-1838 (800) 886-3935 (408) 986-1010 (408) 986-1569 w w w .p l e x t o r.c o m

Man u factu res a lin e of h igh -p erform an ce CD-ROM d rives. PlugIn Datamation

(714) 282-6188 (714) 282-6199 (800) 345-7274 w w w .p e l o g i c .c o m

Man u factu res th e Systo Tek CPU fan failu re alarm , as well as th e SCSI-Lin k p arallelto-SCSI con verter an d oth er h igh -p erform an ce SCSI ad ap ters.

Cah n ers Bu sin ess In form ation 275 W ash in gton St. Newton , MA 02158-1630

Precision Plast ics 340 Roeblin g Rd . San Fran cisco, CA 94080

Ph on e Fax W eb E-m ail

Ph on e Fax

(617) 964-3030 (617) 558-4506 w w w .d a t a m a t i o n .c o m rt w i ss@c a h n e rs.c o m

An excellen t in d u stry p u blication , featu rin g articles on n etworkin g an d com m u n ication s. Pow erQuest Corporat ion 1359 N. Research W ay, Bld g. K Orem , UT 84097 Ph on e Sales Fax W eb

(801) 437-8900 (800) 379-2566 (801) 226-8941 w w w .p o w e rq u e st .c o m

Lead in g d evelop er of h ard d isk m an agem en t software for n etwork servers an d d esktop com p u ters. PowerQu est is th e m aker of Partition Magic Drive Cop y, Drive Im age Drive, Im age Profession al, Gu ard ian An gel, Server Max, an d Server Magic for Netware.

(415) 588-4450 (415) 588-5336

A su p p lier of test an d em u lation PC card s. Processor M agazine

P.O. Box 85518 Lin coln , NE 68501 Sales Fax W eb

(800) 247-4880 (402) 479-2120 w w w .p ro c e sso r.c o m

Pu blication th at offers excellen t sou rces of rep lacem en t an d rep air p arts an d n ew eq u ip m en t at d iscou n t p rices. Public Soft w are Library P.O. Box 35705 Hou ston , TX 77235 Ph on e Sales Fax W eb

(713) 524-6394 (800) 242-4775 (713) 524-6398 w w w .p sl w e b .c o m

Distribu tor of h igh -q u ality p u blic d om ain an d sh areware software. Its library is th e m ost well-research ed an d well-tested available. Also offers an excellen t n ewsletter th at reviews th e software.

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Appendix A—Vendor List

Qlogic Corporat ion 3545 Harbor Blvd . P.O. Box 5001 Costa Mesa, CA 92626 Ph on e Tech Su p p ort Fax W eb

(714) 438-2200 (714) 668-5037 (714) 668-5324 w w w .q l c .c o m

Man u factu res a lin e of h igh -en d PCI SCSI ad ap ters. Qualit as, Inc. 8601 Georgia Ave. #908 Silver Sp rin g, MD 20910 W eb

w w w .q u a l i t a s.c o m

Man u factu res th e Qu alitas Max 8 m em orym an ager u tility p rogram s. Quant um Corporat ion 500 McCarth y Blvd . Milp itas, CA 95035 Ph on e Sales Tech Su p p ort FAXBack BBS W eb

(408) 894-4000 (800) 624-5545 (800) 826-8022 (800) 434-7532 (800) 894-3214 w w w .q u a n t u m .c o m

Man u factu res a lin e of 5.25- an d 3.5-in ch h ard d isk d rives. Su p p lies d rives to Ap p le Com p u ter, Com p aq , IBM, Dell, an d HP. Also p rod u ces DLT an d SSD (solid state d isk). Quart erdeck Corporat ion 13160 Min d an ao Marin a Del Rey, CA 90292 Ph on e Fax BBS W eb

(310) 309-3700 (310) 314-4218 (310) 309-3227 w w w .q u a rt e rd e c k .c o m

Man u factu res th e p op u lar ProCom m Plu s/ Rap id Rem ote, Clean Sweep , Iware Con n ect, QEMM, HiJaak Pro, W in p robe, Zip It, Fix It, Partition It, an d Rem ove It u tility an d d iagn ostics software. Quart er-Inch Cart ridge Drive St andards, Inc. ( QIC) 311 E. Carrillo St. San ta Barbara, CA 93101 Ph on e Fax W eb

(805) 963-3853 (805) 962-1541 w w w .q i c .o rg

An in d ep en d en t in d u stry grou p th at sets an d m ain tain s Qu arter-In ch Cartrid ge (QIC) tap e d rive stan d ard s for backu p an d arch ivin g p u rp oses. Que Corporat ion 201 W . 103rd St. In d ian ap olis, IN 46290 Ph on e Sales Fax W eb

(317) 581-3500 (800) 428-5331 (800) 448-3804 w w w .m c p .c o m

Pu blish es th e h igh est-q u ality com p u ter software an d h ard ware books in th e in d u stry. Radio Shack ( A Division of Tandy Corporat ion) 100 G Th rockm orton Street #1700 Fort W orth , TX 76102 Ph on e Fax W eb

(817) 390-3011 (817) 390-2774 w w w .ra d i o sh a c k .c o m

Man ages th e Rad io Sh ack electron ics stores, wh ich sell n u m erou s electron ics d evices, p arts, an d su p p lies. Also m an u factu res a lin e of PC-com p atible com p u ters an d com p u ter accessories an d su p p lies.

Rosenthal Engineering

Ram t ron Int ernat ional Corporat ion 1850 Ram tron Dr. Colorad o Sp rin gs, CO 80921

Rockw ell Sem iconduct or Syst em s 4311 Jam boree Rd . Newp ort Beach , CA 92660-3095

Ph on e W eb

Ph on e Fax W eb

(719) 481-7000 w w w .ra m t ro n .c o m

Man u factu res sp ecial m em ory com p on en ts in clu d in g EDRAM d yn am ic RAM p rod u cts th at com bin e h igh -sp eed DRAM with an even faster SRAM cach e on a sin gle ch ip . Rancho Technology, Inc. 10783 Bell Ct. Ran ch o Cu cam on ga, CA 91730 Ph on e Fax BBS W eb E-m ail

(909) 987-3966 (909) 989-2365 (909) 980-7699 w w w .ra n c h o .c o m sc si @ra n c h o .c o m

Design s an d m an u factu res SCSI exp an d er p rod u cts, su ch as Sin gle to Differen tialEn d ed Con verters, Exten d ers, LVD SCSI, ASIC, an d oth ers. Also sp ecializes in Cu stom (OEM) Solu tion s. Rendit ion 999 East Arq u es Aven u e Su n n yvale, CA 94086 Ph on e Fax W eb E-m ail

(408) 822-0100 (408) 822-0199 w w w .re n d i t i o n .c o m i n f o @re n d i t i o n .c o m

Man u factu res low-cost, h igh -p erform an ce 2D/ 3D grap h ics acceleration ch ip s for th e m ain stream p erson al com p u ter m arket. Rip-Tie Com pany P.O. Box 77394 San Fran cisco, CA 94107 Ph on e Fax W eb

(415) 543-0170 (415) 777-9868 w w w .ri p t i e .c o m

Man u factu res cable m an agem en t p rod u cts m ad e from velcro.

(714) 221-4600 (714) 221-4078 w w w .ro c k w e l l .c o m / se m i .h t m l

Man u factu res com m u n ication s ch ip sets u sed in m an y PC-com p atible m od em s an d h igh -sp eed d ata, fax, bu sin ess au d io, voicem ail an d m obile-com m u n ication ap p lication s. Roland Corporat ion U.S. 7200 Dom in ion Circle Los An geles, CA 90040 Ph on e Fax W eb

(213) 685-5141 (213) 722-0911 w w w .ro l a n d u s.c o m

Man u factu res a variety of m u sical eq u ip m en t an d MIDI in terfaces for com p u ters. Rosent hal Engineering P.O. Box 1650 San Lu is Obisp o, CA 93406 Ph on e Fax W eb

(805) 541-0910 (805) 541-2676 sl o n e t .o rg / ~ d o re n /

Man u factu res a u n iq u e lin e of system an d d isk u tilities in clu d in g Th e Disk Drive Clean er, Con flict Resolver, System W orkou t, R-Form at, Year 2000 Fix, an d Un in stall.

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Rupp Technology Corporat ion ( Ret ail Locat ions – M obilscape) 2240 N. Scottsd ale Road Tem p e, AZ 85281 Ph on e Sales Tech Su p p ort Fax W eb

(602) 941-4789 (800) 852-7877 (800) 941-5602 (602) 224-0898 w w w .ru p p .c o m

Developer of th e DOS In terlin k software u sed in MS- an d PC-DOS. Also sells a com m ercial version called Fastlyn x Lite for DOS th at offers m an y en h an cem en ts over In terlin k. W in Lyn x is a fu ll win dows file tran sfer an d m an agem en t program . Also m akes cu stom -len gth parallel tran sfer cables u sin g a h igh -speed, 18-wire design su pported by virtu ally all parallel tran sfer program s. S3, Inc. 2841 Mission College Blvd . P.O. Box 58058 San ta Clara, CA 95052-8058 Ph on e Fax W eb

(408) 588-8000 (408) 980-5444 w w w .s3 .c o m

Man u factu res a lin e of very p op u lar h igh p erform an ce vid eo ch ip sets. Safew are Insurance Agency, Inc. P.O. Box 656 5760 N. High St. Colu m bu s, OH 43085 Ph on e Sales Fax W eb

(614) 781-1492 (800) 848-3469 (614) 781-0559 w w w .sa f e w a re -i n s.c o m

In su ran ce com p an y th at sp ecializes in in su ran ce for com p u ter eq u ip m en t.

Sam s 201 W . 103rd St. In d ian ap olis, IN 46290 Ph on e W eb

(317) 581-3500 w w w .m c p .c o m

Pu blish es tech n ical books on com p u ters an d electron ic eq u ip m en t. Sam sung Sem iconduct or, Inc. 3655 N. First St. San Jose, CA 95134 Ph on e W eb

(408) 544-4000 w w w .sa m su n g se m i .c o m or w w w .se c .sa m su n g .c o m

Man u factu res m em ory an d sem icon d u ctor d evices. Seagat e Soft w are 400 In tern ation al Pkwy. Heath row, FL 32746 Ph on e Au tom ated Tech Su p p ort FAXBack Fax BBS TDD W eb

(407) 333-7500 (800) 821-8782 (800) 732-4283 (407) 262-4225 (407) 263-3662 (408) 438-5382 w w w .se a g a t e .c o m

Man u factu res a lin e of tap e-backu p p rod u cts. Acq u ired by Seagate Tech n ologies. Seagat e Soft w are St orage M anagem ent Group ( Form erly Syt ron) 400 In tern ation al Pkwy. Heath row, FL 32746 Ph on e Fax Sales W eb

(407) 333-7500 (407) 531-7770 (800) 327-2232 w w w .se a g a t e so f t w a re .c o m

Man u factu res th e SyTOS tap e-backu p software for DOS an d OS/ 2, th e m ost wid ely u sed tap e software in th e in d u stry.

Sharp M icroelectronics Group

Seagat e Technology 920 Disc Dr. Scotts Valley, CA 95066

SGS-Thom son M icroelect ronics, Inc. 55 Old Bed ford Rd . Lin coln , MA 01773

Ph on e (714) 641-2500 Fax (408) 429-6356 Cu stom er Service (800) 468-3472 FAXBack (408) 438-2620 BBS (408) 438-8771 W eb w w w .se a g a t e .c o m

Ph on e Fax W eb

Th e largest h ard d isk m an u factu rer in th e world . Offers th e m ost exten sive p rod u ct lin e of an y d isk m an u factu rer, ran gin g from low-cost u n its to th e h igh estp erform an ce, -cap acity, an d -q u ality d rives available. Also a com p lete lin e of backu p software in clu d in g Backu p Exec for W in d ows 95. Sencore 3200 Sen core Dr. Siou x Falls, SD 57107 Ph on e Sales Fax W eb

(605) 339-0100 (800) 736-2673 (605) 335-6379 w w w .se n c o re .c o m

Man u factu res a lin e of com p u ter m on itor sign al gen erators an d rep air eq u ip m en t. Service News M agazine

106 Lafayette Street Yarm ou th , ME 04096 Ph on e Fax W eb

(207) 846-0600 (207) 846-0657 w w w .se rv i c e n e w s.c o m

An excellen t m on th ly n ewsp ap er for com p u ter service an d su p p ort p erson n el featu rin g articles coverin g PC service an d rep air p rod u cts. Service n ews boasts a circu lation of 45,000 IT su p p ort p rofession als across th e Un ited States.

(617) 259-0300 (617) 259-4421 w w w .st .c o m

Man u factu res a variety of m em ory an d sem icon d u ctor d evices. Sharp Elect ronics Corporat ion Sh arp Plaza Mah wah , NJ 07430-2135 Ph on e Fax Sales W eb

(201) 529-8200 (201) 529-8413 (800) BE SHARP (237-4277) w w w .sh a rp -u sa .c o m

Man u factu res a wid e variety of electron ic an d com p u ter eq u ip m en t, in clu d in g th e best LCD m on och rom e an d active m atrix color d isp lays an d p an els, as well as scan n ers, p rin ters, an d com p lete lap top an d n otebook system s. Sharp M icroelect ronics Group 5700 NW Pacific Rim Blvd . Cam as, W A 98607 Ph on e W eb

(800) 642-0261 w w w .sh a rp m e g .c o m

Man u factu res m em ory an d sem icon d u ctor d evices.

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Appendix A—Vendor List

Sigm a Dat a 26 Newp ort Rd . New Lon d on , NH 03257-4565

Sim ple Technology 3001 Daim ler St. San ta An a, CA 92705

Ph on e Sales Fax W eb

Ph on e Sales Fax W eb

(603) 526-6909 (800) 446-4525 (603) 526-6915 w w w .si g m a d a t a .c o m

Man u factu rer/ d istribu tor of p erson al com p u ter ad d -on an d p erip h eral p rod u cts sp ecializin g in easy-to-in stall h ard d rives, p rocessors, an d m em ory u p grad es. It offers a u n iq u e lin e of “Qu ick Easy” u p grad es in clu d in g th e QED (Qu ick Easy Disk) an d QEP (Qu ick Easy Processor). Its p rod u ct lin e also in clu d es h igh -sp eed , h igh cap acity d rives for a variety of p op u lar p ortable, lap top , an d n otebook com p u ters. Silicon Int egrat ed Syst em s Corp. ( SiS) 240 N. W olfe Rd . Su n n yvale, CA 94086 Ph on e Fax W eb

(408) 730-5600 (408) 730-5639 w w w .si s.c o m .t w

Man u factu res PC m oth erboard ch ip sets. Silicon Valley Research 6360 San Ign acio Ave. San Jose, CA 95119 Ph on e Fax W eb

(408) 361-0333 (408) 361-0330 w w w .sv ri .c o m

Man u factu res a com p lete lin e of IDE in terface ad ap ters, in clu d in g a u n iq u e m od el th at su p p orts 16-bit IDE (ATA) d rives on PC an d XT system s (8-bit ISA bu s) an d m od els, in clu d in g flop p y d rive su p p ort an d serial an d p arallel p orts.

(714) 476-1180 (800) 854-3900 (714) 476-1209 w w w .si m p l e t e c h .c o m

Man u factu res th e SIMMswitch , wh ich replaces th e soldered resistors on a SIMM, allowin g it to be easily recon figu red. It also sells SIMMs with th e switch already in stalled. SL W aber 520 Fellowsh ip Rd . #306 Mt. Lau rel, NJ 08054 Ph on e W eb

(609) 866-8888 w w w .w a b e r.c o m

Man u factu res a com p lete lin e of p ower p rotection eq u ip m en t for PC com p u ters. Sm art Cable Inc. 13625 NE 126th Place, Ste. 400 Kirklan d , W A 98034 Ph on e Sales Fax

(206) 823-2273 (800) 752-6526 (206) 821-3961

Man u factu res th e Sm artCable u n iversal serial RS-232 cable. Sof Touch Syst em s, Inc. 1300 S. Merid ian , Ste. 600 Oklah om a City, OK 73108-1751 Ph on e Fax W eb

(405) 947-8080 (405) 947-8169 w w w .so f t o u c h .c o m

Man u factu res Gam m aTech Utilities for OS/ 2 th at can u n d elete an d recover files ru n n in g u n d er OS/ 2 even on an OS/ 2 HPFS p artition , an d Un iMain t, a d esktop rep air an d recovery p rogram .

Stac Incorporated

Sola Heavy Dut y Elect ric ( Acquired by Best Pow er, a Division of General Signal Pow er) P.O. Box 280 Neced ah , W I 54646 Ph on e Sales Fax W eb

(800) 289-7652 (800) 356-5794 (608) 565-2221 w w w .b e st p o w e r.c o m

Man u factu res a lin e of com p u ter p owerp rotection d evices. SONERA Technologies P.O. Box 565 Ru m son , NJ 07760 Ph on e Sales Fax W eb

(732) 747-6886 (800) 932-6323 (732)747-4523 w w w .d i sp l a y m a t e .c o m

Man u factu res th e Disp layMate vid eo d isp lay u tility an d d iagn ostic p rogram . Disp layMate exercises, trou blesh oots, an d d iagn oses vid eo d isp lay ad ap ter an d m on itor p roblem s. Sony Corporat ion of Am erica Son y Drive Park Rid ge, NJ 07656 Ph on e Fax BBS W eb

(800) 326-9551 (408) 955-5171 (408) 955-5107 w w w .so n y .c o m

Man u factu res all typ es of h igh -q u ality electron ic an d com p u ter eq u ip m en t, in clu d in g d isp lays an d m agn etic- an d op tical-storage d evices. SOYO Tek, Inc. 1209 Joh n Reed Ct. City of In d u stry, CA 91745 Ph on e Fax W eb

(818) 330-1712 (818) 968-4164 w w w .so y o .c o m

On e of th e top 10 largest Taiwan -based m oth erboard m an u factu rers. Specialized Product s Com pany 1100 S. Kim ball Aven u e Sou th lake, TX 76092 Ph on e Sales Fax W eb

(817) 329-6647 (800) 866-5353 (800) 234-8286 w w w .sp e c i a l i z e d p ro d u c t s. co m

Distribu tes a variety of tools an d test eq u ip m en t. Sprague M agnet ics, Inc. 12806 Brad ley Ave. Sylm ar, CA 91342 Ph on e Fax Sales W eb

(818) 364-1800 (818) 364-1810 (800) 553-8712 w w w .sp ra g u e -m a g n e t i c s.c o m

Distribu tes a u n iq u e an d in terestin g m agn etic d evelop er flu id th at can be u sed to view sectors an d tracks on a m agn etic d isk or tap e. Also rep airs com p u ter tap e d rives. St ac Incorporat ed 12636 High Blu ff Dr. San Diego, CA 92130 Ph on e Sales Fax BBS W eb

(619) 794-4300 (800) 522-7822 (619) 794-3715 (619) 794-3711 w w w .st a c .c o m

Prod u cts in clu d e Rep lica an d Reach Ou t En terp rise rem ote/ con trol access for cen trally m an aged W in d ows n etworks. Th ey also offer Rep lica 3, backu p an d d isaster recovery for d istribu ted W in d ows NT an d Netware servers (to tap e).

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Appendix A—Vendor List

St andard M icrosyst em s Corporat ion ( SM SC) 80 Arkay Dr. Hau p p au ge, NY 11788 Ph on e Fax FAXBack BBS W eb

(516) 273-3100 (516) 273-1803 (800) 762-8329 (516) 434-3162 w w w .sm c .c o m

Man u factu res com p on en t-based p rod u cts. (Sold th eir system -based p rod u cts d ivision , SMC Networks, In c.) SM C Net w orks, Inc. ( Form erly a Division W it hin St andard M icrosyst em s Corp.) 350 Ken n ed y Drive Hau p p au ge, NY 11788 Ph on e

(516) 435-6000

Man u factu res variou s system -based p rod u cts su ch as Eth ern et an d ARCn et n etwork ad ap ters, as well as h u bs, board s, an d PC card s. St ar M icronics Am erica, Inc. 70-D Eth el Rd . W est Piscataway, NJ 08854 Ph on e (732) 572-6597 Fax (732) 572-5095 W eb w w w .st a rm i c ro n i c s.c o m Man u factu res a lin e of low-cost p rin ters, receip t p rin ters, an d visu al card system s. STB Syst em s, Inc. 1651 N. Glen ville Su ite 210 Rich ard son , TX 75085-0957 Ph on e Fax BBS W eb

(972) 234-8750 (972) 234-1306 (214) 437-9615 w w w .st b .c o m

Man u factu res variou s ad ap ter board s, an d sp ecializes in a lin e of h igh -resolu tion VGA vid eo ad ap ters. St orage Dim ensions, Inc. 1656 McCarth y Blvd . Milp itas, CA 95035 Ph on e Fax BBS W eb

(408) 954-0710 (408) 944-1200 (408) 944-1221 w w w .a rt e c o m .c o m

Man u factu res h igh -p erform an ce d isk an d tap e storage solu tion s for op en system en viron m en ts. Distribu tes Maxtor h ard d isk an d op tical d rives as com p lete su bsystem s. Sun M oon St ar 1941 Rin gwood Ave. San Jose, CA 95131 Ph on e W eb

(408) 452-7811 w w w .su n -m o o n -st a r.c o m

Man u factu res CD-ROM, m u ltim ed ia kits, an d p ower su p p lies for PC com p atibles. Superm icro Com put er, Inc. 2051 Ju n ction Ave. San Jose, CA 95131 Ph on e Fax BBS W eb

(408) 895-2000 (408) 895-2008 (408) 895-2022 w w w .su p e rm i c ro .c o m

Man u factu res a h igh -q u ality lin e of Pen tiu m -class m oth erboard s. Superpow er Supply, Inc. 990 Norcross In d u strial Ct. Norcross, GA 30071 Ph on e W eb

(770) 263-9647 w w w .sp o w e r.c o m

Man u factu res a lin e of PC-com p atible p ower su p p lies an d cases. Th ey also d istribu te PC com p on en ts.

Teac America, Inc.

Sym ant ec Corporat ion W orld Head q u arters 10201 Torre Aven u e Cu p ertin o, CA 95014 Ph on e Fax BBS W eb

(800) 441-7234 (541) 984-8020 (541) 484-6669 w w w .sy m a n t e c .c o m

Man u factu res a lin e of u tility an d ap p lication s software featu rin g th e Norton Utilities for PC system s an d PC Tools. Also d istribu tes W in fax Pro. SyQuest Technology 47071 Baysid e Pkwy. Frem on t, CA 94538 Ph on e Sales Tech Su p p ort Fax BBS W eb

(510) 226-4000 (800) 245-2278 (510) 226-5400 (510) 226-4102 (510) 226-4120 w w w .sy q u e st .c o m

Man u factu res rem ovable-cartrid ge h ard d isk d rives. Tadiran 2 Seaview Blvd . #102 Port W ash in gton , NY 11050 Ph on e Sales Fax W eb

(516) 621-4980 (800) 537-1368 (516) 621-4517 w w w .t a d ri a n b a t .c o m

Man u factu res a variety of lith iu m batteries for com p u ter an d oth er ap p lication s. Tandy Corporat ion 100 Th rockm orton Street Fort W orth , TX 76102 Ph on e Fax W eb

(817) 390-3700 (817) 390-2647 w w w .t a n d y .c o m

Man u factu res a lin e of PC system s, p erip h erals, an d accessories. Tat ung Com pany of Am erica, Inc. 2850 El Presid io St. Lon g Beach , CA 90810 Ph on e Sales Fax W eb

(310) 637-2105 (800) 827-2850 (310) 637-8484 w w w .t a t u n g u sa .c o m

Man u factu res m on itors an d com p lete com p atible system s. TDK Corporat ion of Am erica 12 Harbor Park Dr. Port W ash in gton , NY 11050 Ph on e Fax W eb

(516) 625-0100 (516) 625-0651 w w w .t d k .c o m

Man u factu res a lin e of m agn etic an d op tical m ed ia, in clu d in g d isk an d tap e cartrid ges. Also p rod u ces m od em s, ICs, sem icon d u ctors, an d p ower su p p ly p rod u cts. Teac Am erica, Inc. 7733 Telegrap h Rd . Mon tebello, CA 90640 Ph on e Fax BBS FAXBack W eb

(213) 726-0303 (213) 727-7656 (213) 727-7660 (213) 727-7629 w w w .t e a c .c o m

Man u factu res a lin e of flop p y an d tap e d rives, in clu d in g a u n it th at com bin es both 3 1/ 2-in ch an d 5 1/ 4-in ch d rives in on e h alf-h eigh t p ackage.

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Tech Dat a Corporat ion 5350 Tech Data Dr. Clearwater, FL 34620 Ph on e Sales Fax BBS W eb

(813) 539-7429 (800) 237-8931 (813) 538-7876 (813) 538-7090 w w w .t e c h d a t a .c o m

Distribu tes com p u ter eq u ip m en t an d su p p lies. Tech Spray, Inc. P.O. Box 949 Am arillo, TX 79105-0949 Ph on e Fax W eb

(806) 372-8523 (806) 372-8750 w w w .t e c h sp ra y .c o m

Man u factu res a com p lete lin e of com p u ter an d electron ic clean in g ch em icals an d p rod u cts. Tecm ar Technologies, Inc. 1900 Pike Rd . Lon gm on t, CO 80501 Ph on e Sales

(303) 682-3700 (800) 4-BACKUP (422-2587) Tech Su p p ort (800) 344-4463 Cu stom er Service (800) 992-9916 Fax (303) 776-7706 W eb w w w .t e c m a r.c o m Man u factu res W an gtech , W an gDAT, an d Prolin e tap e back u p d rives. Tekram Technologies 11500 Metric Blvd ., Ste. 190 Au stin , TX 78758 Ph on e Fax W eb

(512) 833-6550 (512) 833-7276 w w w .t e k ra m .c o m

Man u factu res a com p lete lin e of cach in g an d n on cach in g d isk con trollers, PCI m oth erboard s, m u ltim ed ia p rod u cts, CDROM servers, p rin ter servers, an d vid eo card s. Sp ecializes in IDE an d SCSI ad ap ters th at are fast an d flexible. Test and M easurement World M agazine

275 W ash in gton St. Newton , MA 02158-1611 Ph on e Fax E-m ail

(617) 558-4671 (617) 558-4470 t m w @c a h n e i s.c o m

A m agazin e for q u ality con trol an d testin g in th e electron ics in d u stry. Free for th ose wh o q u alify. Texas Inst rum ent s, Inc. Box 14149 12501 Research Blvd . Au stin , TX 78714-9149 Ph on e Sales W eb

(512) 250-7111 (800) TI-TEXAS (848-3927) w w w .t i .c o m

Man u factu res m em ory an d oth er sem icon d u ctor d evices. The Learning Com pany 1 Ath en aeu m St. Cam brid ge, MA 02142 Ph on e Fax BBS W eb

(617) 494-1200 (617) 494-5898 (423) 670-2023 w w w .l e a rn i n g c o .c o m

Man u factu res W ord Star 7, an d d istribu tes m ore th an 500 oth er software p rogram s in clu d in g Com pton’s Encyclopedia an d variou s ed u cation al titles.

Trident M icrosystems

Therm alloy, Inc. 2021 W . Valley View Ln . P.O. Box 810839 Dallas, TX 75234 Ph on e Fax W eb

(972) 243-4321 (972) 241-4656 w w w .t h e rm a l l o y .c o m

Man u factu res a lin e of excellen t CPU h eatsin k p rod u cts, in clu d in g version s with bu ilt-in fan m od u les. Toshiba Am erica, Inc. 9740 Irvin e Blvd . Irvin e, CA 92718 Ph on e Sales Fax BBS W eb

(714) 583-3926 (800) 999-4273 (800) 950-4373 (714) 837-2116 w w w .c o m p u t e rs.t o sh i b a .c o m

Man u factu res a com plete lin e of 5 1/ 4- an d 3 1/ 2-in ch floppy an d h ard disk drives, CDROM drives, display produ cts, prin ters, an d a popu lar lin e of laptop an d n otebook PC system s.

Trace Research and Developm ent Cent er Un iversity of W iscon sin S-151 W aism an Cen ter 1500 High lan d Ave. Mad ison , W I 53705 Ph on e TDD E-m ail

(608) 263-2309 (608) 263-5408 i n f o @t ra c e .w i sc .e d u

An in terd iscip lin ary research , d evelop m en t, an d resou rce cen ter on tech n ology an d d isability. Traveling Soft w are, Inc. 18702 N. Creek Pkwy. #102 Both ell, W A 98011 Ph on e Sales Fax BBS W eb

(425) 483-8088 (800) 662-2652 (425) 485-6786 (425) 485-1736 w w w .t ra v so f t .c o m

Man u factu res th e Lap Lin k file-tran sfer p rogram for PC an d Mac system s as well as several oth er u tility p rogram s.

TouchSt one Soft w are Corporat ion 2124 Main St. Hu n tin gton Beach , CA 92648

Trident M icrosyst em s 189 N. Bern ad o Ave. Mou n tain View, CA 94043

Ph on e Sales Fax W eb

Ph on e Fax BBS W eb

(714) 969-7746 (800) 531-0450 (714) 959-1886 w w w .t o u c h st o n e so f t w a re .c o m

Man u factu res th e Ch eckIt lin e of p rod u cts in clu d in g Ch eckIt v5.0 for W in d ows 95 an d Ch eckIt Profession al Ed ition , wh ich p rovid es rep air tech n ician s with Ch eckIt v5.0, Ch eckIt DOS, PC-Cillan An ti-Viru s, an d toolkit.

(650) 691-9211 (650) 691-9260 (650) 961-1016 w w w .t ri d e n t m i c ro .c o m

Man u factu res a lin e of h igh -en d vid eo ch ip sets an d m u ltim ed ia vid eo ad ap ters.

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TriniTech, Inc. 8751 Ulm erton , Bld g. 101 Largo, FL 33771

Tyan Com put er Corporat ion 1753 S. Main St. Milp itas, CA 95035

Ph on e Sales Fax W eb

Ph on e Fax Tech Su p p ort BBS W eb

(813) 532-4151 (800) 909-3424 (813) 532-0457 w w w .p c a n a l y z e r.c o m

Man u factu res a com p lete lin e of PC d iagn ostics p rod u cts in clu d in g th e Om n iPOST, IRQu est Plu s PC Power Sen try d iagn ostics card s, Om n i An alyzer, PC Ch eck, viru s W eb MCSC, A+ Certification Software, CNE Certificate Cou rse, an d Exp ertrace d iagn ostics software. Tripp Lit e M anufact uring 11 W est 35th Street Ch icago, IL 60609 Ph on e Fax W eb

(773) 329-1777 (773) 869-1329 w w w .t ri p p l i t e .c o m

Man u factu res a com p lete lin e of com p u ter p ower-p rotection d evices. TTI Technologies 2101 Au to Cen ter Drive, #150 Oxn ard , CA 93030 Ph on e Sales Fax

(805) 988-4711 (800) 541-1943 (805) 988-2437

(408) 956-8000 (408) 956-8044 (408) 942-5526 (408) 956-8171 w w w .t y a n .c o m

Man u factu res an excellen t lin e of PC m oth erboard s in ATX an d Baby-AT form factors. Ult ra-X, Inc. 1765 Scott Blvd ., Ste. 101 San ta Clara, CA 95050 Ph on e Sales Fax W eb

(408) 261-7090 (800) 722-3789 (408) 261-7077 w w w .u x d .c o m

Man u factu res th e excellen t Qu ickPost PC, Qu ickPost PCIS/ 2, Qu ickPost PRO, Ph D+ PC In sp ector, an d Racer II d iagn ostic card s, as well as th e Qu ickTech PRO, Qu ickTech 98, Ram stress Test (RST), an d Diagn ostic Referen ce d iagn ostic software p ackages. Th e Racer II is on e of th e m ost com p lete trou blesh ootin g h ard ware card s on th e m arket.

Distribu tes AMI, Award , Ph oen ix MR BIOS u p grad es, an d m icroid research .

Underw rit ers Laborat ories, Inc. Corp orate Head q u arters 333 Pfin gsten Rd . North brook, IL 60062-2096

Tw inhead Corporat ion 48295 Frem on t Blvd . Frem on t, CA 94538

Ph on e Fax W eb

Ph on e Sales W eb

Th e lead in g th ird -p arty p rod u ct safety certification organ ization in th e Un ited States, an d th e largest in North Am erica. Establish ed in 1894.

(510) 492-0828 (800) 552-8946 w w w .t w i n h e a d .c o m

Man u factu res n otebook, su bn otebook, an d d esktop com p u ter system s.

(847) 272-8800 (847) 272-8129 w w w .u l .c o m

Verbatim Corporation

Unicom p, Inc. 2501 W . Fifth St. San ta An a, CA 92703 Ph on e Fax

(800) 359-5092 (714) 571-1909

Distribu tes n ew an d refu rbish ed p rin ter rep air p arts for all typ es of p rin ters. Unicore Soft w are, Inc. 1538 Tu rn p ike St. North An d over, MA 01845 Ph on e Fax W eb

(978) 685-6468 (978) 683-1630 w w w .m rb i o s.c o m

Man u factu res th e MR BIOS, on e of th e m ost flexible an d con figu rable BIOS version s available. Th ey h ave version s available for a variety of d ifferen t ch ip sets an d m oth erboard s. UNISYS Town sh ip Lin e an d Un ion Meetin g Rd . Blu e Bell, PA 19424 Ph on e Fax W eb

(800) 448-1424 (716) 742-6671 w w w .u n i sy s.c o m

Man u factu res PC-com p atible system s th at are p art of th e govern m en t Desktop IV con tract. Also offers a com p lete lin e of in form ation m an agem en t software solu tion s. U.S. Robot ics, Inc. ( M erged w it h 3Com ) 8100 N. McCorm ick Blvd . Skokie, IL 60076 Ph on e Sales Fax FAXBack BBS W eb

(847) 982-5010 (800) 550-7800 (847) 933-5300 (800) 762-6163 (847) 982-5092 w w w .3 c o m .c o m

Man u factu res a com p lete lin e of m od em s an d ISDN com m u n ication s p rod u cts. V Com m unicat ions, Inc. 2290 N. 1st Street #101 San Jose, CA 95131 Ph on e Fax Tech Su p p ort W eb

(408) 296-4224 (408) 965-4014 (408) 965-4018 w w w .v -c o m .c o m

Man u factu res th e Sou rcer d isassem bler an d oth er p rogram m in g tools. Vart a Bat t eries, Inc. 300 Execu tive Blvd . Elm sford , NY 10523 Ph on e Fax W eb

(914) 592-2500 (914) 592-2667 w w w .v a rt a .c o m

Man u factu res a com p lete lin e of com p u ter batteries. Verbat im Corporat ion 1200 W T Harris Blvd . Ch arlotte, NC 28262 Ph on e W eb

(704)547-6500 w w w .v e rb a t i m c o rp .c o m

Man u factu res a lin e of storage m ed ia, in clu d in g op tical an d m agn etic d isks an d tap es.

1233

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Appendix A—Vendor List

VESA St andards 2150 N. First St., Ste. 440 San Jose, CA 95131-2029 Ph on e Fax W eb E-m ail

(408) 435-0333 (408) 435-8225 w w w .v e sa .o rg m a rk e t i n g @v e sa .o rg

Lead in g world wid e op en trad e association with m ore th an 360 m em ber com p an ies. VESA’s m ission is to p rom ote an d d evelop tim ely, relevan t, op en d isp lay an d d isp lay in terface stan d ard s en su rin g in terop erability an d en cou ragin g in n ovation an d m arket growth . Mem bersh ip in clu d es h ard ware, software, PC d isp lay an d com p on en t m an u factu rers, cable an d telep h on e com p an ies, an d service p rovid ers.

Man u factu res form -fittin g clear keyboard covers an d oth er com p u ter accessories. VLSI Technology, Inc. 1109 McKay Dr. San Jose, CA 95131 Ph on e W eb

(408)434-3000 w w w .v l si .c o m

Man u factu res ch ip sets an d circu its for PCcom p atible m oth erboard s an d ad ap ters. Volpe, Hank P.O. Box 43214 Baltim ore, MD 21236 Ph on e BBS W eb

(410) 256-5767 (410) 256-3631 w w w .m o d e m d o c t o r.c o m

VIA Technologies, Inc. 1045 Mission Cou rt Frem on t, CA 94539

Man u factu res th e Mod em Doctor Version 6 serial p ort an d m od em d iagn ostics p rogram .

Ph on e Fax W eb

W alling Com pany 4401 Ju n ip er St. Tem p e, AZ 85282

(510) 683-3300 (510) 683-3301 w w w .v i a t e c h .c o m

Man u factu res PC m oth erboard ch ip sets.

Ph on e/ Fax

View Sonic 381 Brea Can yon Road W aln u t, CA 91789

Man u factu res th e DataRase EPROM eraser, wh ich can erase as m an y as fou r EPROM ch ips sim u ltan eou sly u sin g u ltraviolet ligh t.

Ph on e Fax BBS W eb

W ang Laborat ories, Inc. 600 Tech n ology Park Dr. Billerica, MA 01821-4130

(909) 869-7976 (909) 869-7958 (909) 444-5219 w w w .v i e w so n i c .c o m

Man u factu res a lin e of h igh -q u ality m on itors an d d isp lays with Plu g an d Play an d en ergy star com p lian ce. Also p rod u ces n etwork-level p ower backu p system s. Visiflex Seals 16 E. Lafayette St. Hacken sack, NJ 07601 Ph on e

(201) 487-8080

Ph on e

(602) 838-1277

(800) 225-0654

Man u factu res a variety of PC-com patible system s, in clu din g som e with MCA bu s slots.

Xircom

W at ergat e Soft w are 2000 Powell St. #1200 Em eryville, CA 94608 Ph on e Fax W eb

(510) 596-2080 (510) 596-2092 w w w .w s.c o m

W ordPerfect ( A Division of Corel Soft w are) P.O. Box 1036 Bu ffalo, NY 14240 Ph on e W eb

(800) 772-6735 w w w .c o re l .c o m

Man u factu res th e excellen t PC-Doctor d iagn ostic p rogram for PC trou blesh ootin g an d rep air.

Man u factu res th e p op u lar W ord Perfect word p rocessin g p rogram . Acq u ired by Novell, th en sold to Corel.

W ave Tech 9145 Balboa Ave. San Diego, CA 92123

W yse Technology 3471 N. 1st St. San Jose, CA 95134

Ph on e Sales Fax BBS W eb

Ph on e Sales Fax BBS W eb

(619) 279-2200 (800) 854-2708 (619) 627-0132 (619) 278-5034 w w w .w a v e t e c h .c o m

(408) 473-1200 (800) 438-9973 (408) 473-1972 (408) 922-4400 w w w .w y se .c o m

Man u factu res d iagn ostics an d test eq u ip m en t.

Man u factu res gen eral p u rp ose term in als an d W IN TERM W in d ows-based term in als.

W est ern Digit al Corporat ion 8105 Irvin e Cen ter Dr. Irvin e, CA 92618

Xerox Corporat ion Xerox Sq u are Roch ester, NY 14644

Ph on e Sales Fax FAXBack BBS W eb

Ph on e Fax

(714) 932-5000 (800) 832-4778 (714) 932-4012 (714) 932-4300 (714) 753-1068 w w w .w e st e rn d i g i t a l .c o m

Lead er in in form ation storage m an agem en t, p rovid in g a broad array of h ard d rive p rod u cts for both p erson al an d en terp risewid e com p u tin g. W inbond ( Form erly Sym phony Laborat ories) 2730 Orch ard Pkwy. San Jose, CA 95134 Ph on e Fax W eb

(408) 943-6666 (408) 474-1600 w w w .w i n b o n d .c o m .t w

Man u factu res PC m oth erboard ch ip sets.

(203) 968-3000 (203) 968-3368

Man u factu res an exten sive lin e of com p u ter eq u ip m en t, cop iers, an d p rin ters. Xircom 2300 Corp orate Cen ter Dr. Th ou san d Oaks, CA 91320 Ph on e Sales Tech Su p p ort Fax BBS W eb

(805) 376-9300 (800) 438-4562 (805) 376-9220 (805) 376-9311 (805) 376-9130 w w w .x i rc o m .c o m

Man u factu res extern al Token Rin g an d Eth ern et ad ap ters th at attach to a p arallel p ort, an d PCMCIA card s for lap top s.

1235

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Appendix A—Vendor List

Y-E Dat a Am erica, Inc. 5824 Peach tree Corn ers East, Ste. A Norcross, GA 30092 Ph on e

(404) 237-5615

Man u factu res a lin e of flop p y d isk d rives, tap e d rives, an d p rin ters. Su p p lied 5 1/ 4in ch flop p y d rives to IBM for u se in XT, AT, an d PS/ 2 system s. ZD Com dex and Forum s 300 First Ave. Need h am , MA 02194-2722 Ph on e Fax W eb

(781) 433-1500 (781) 449-2674 w w w .c o m d e x .c o m

Prod u cer of th e world ’s lead in g com p u ter trad esh ows.

Vendors by Product or Service Cat egory If you are lookin g for a p rod u ct or service bu t d on ’t kn ow a sp ecific ven d or th at p rovid es it, u se th is p art of th e ven d or list to fin d a ven d or th at p rovid es wh at you n eed . Th en look u p th e ven d or’s con tact in form ation in th e earlier p art of th is ap p en d ix. Audio Adapt ers ( Sound Cards) Creative Labs, In c. Orch id Tech n ology (A Division of Micron ics) Rolan d Corp oration U.S. Bat t eries Du racell, In c. Fed co Electron ics, In c.

Zenit h Dat a Syst em s P.O. Box 36 Magn a, UT 84044

Pan ason ic In d u strial Co.

Ph on e W eb

Varta Batteries, In c.

(916) 388-0101 w w w .z d s.c o m

Man u factu res a lin e of PC system s. Zeos Int ernat ional, Lt d. ( Purchased by M icron Elect ronics) 900 E. Karch er Rd . Nap a, ID 83687 Ph on e Sales Fax BBS W eb

(208) 893-3434 (800) 438-3343 (208) 893-3424 (208) 893-8982 w w w .m e i .m i c ro n .c o m

Man u factu red a lin e of good , low-cost, PC system s sold by way of m ail ord er.

Tad iran

BIOS Am erican Megatren d s, In c. (AMI) Award Software In tern ation al, In c. DTK Com p u ter, In c. Micro Firm ware, In c. Ph oen ix Tech n ologies, Ltd . TTI Tech n ologies Un icore Software, In c. Books, M agazines, Docum ent at ion An n abooks Byte Magazine/ McGraw-Hill Com puter Design Magazine Com puter Graphics W orld Magazine Com puter Hotline Magazine Com puter Reseller News

Vendors by Product or Service Category

Com puter Retail W eek Magazine Com puter Shopper Magazine Com puter Technology Review Magazine Com tech Pu blish in g, Ltd . Data Base Advisor Magazine Data Com m unications Magazin e Electrocu tion Electronic Buyers’ News Electronic Engineering Tim es Magazine Electronic Products Magazine En d l Pu blication s Fan tasy Prod u ction s (A Division of Fortn er & Associates) Global En gin eerin g Docu m en ts IBM Fu llfilm en t Cen ter IBM Nation al Pu blication s IBM Personal System s Technical Solutions Magazin e InfoW orld Magazin e Macworld Com m u n ication s In c. Motor Magazine OEM Magazine PC Magazine PC W eek Magazine PC W orld Magazine PlugIn Datam ation Processor Magazine Qu e Corp oration Sam s

Cables and Connect ors AMP, In c. Au totim e Corp oration Beld en W ire an d Cable Cables to Go (CTG) CS Electron ics FCI Electron ics - Am ericas Micro Accessories, In c. Micro Com p u ter Cable Com p an y, In c. Sm art Cable In c. Cases Palo Alto Design Grou p PC Portable Man u factu rer, In c. Su p erp ower Su p p ly, In c. CD-ROM Drives and M edia Ch in on Am erica, In c. Creative Labs, In c. JVC In form ation Prod u cts Maxell Corp oration of Am erica Microtest En terp rises Mitsu m i Electron ics Corp oration NEC Tech n ologies, In c. Pan ason ic In d u strial Co. Ph ilip s Con su m er Electron ics Plextor Su n Moon Star Tosh iba Am erica, In c. Chipset s Acer Laboratories, In c. (ALi)

Service News Magazin e

Au ctor Corp oration

Test and Measurem ent W orld Magazin e

Cirru s Logic, In c.

1237

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Appendix A—Vendor List

Cyp ress Sem icon d u ctor Corp oration

Micro 2000, In c.

In tegrated Device Tech n ology, In c.

MicroSystem s Develop m en t, In c.

In tel Corp oration

On track Data In tern ation al, In c. (Form erly On track Com p u ter System s)

LSI Logic, In c. Nation al Sem icon d u ctor Corp oration Oak Tech n ology, In c. Op ti, In c. Rockwell Sem icon d u ctor System s Silicon In tegrated System s Corp . (SiS) VIA Tech n ologies, In c. VLSI Tech n ology, In c. W in bon d (Form erly Sym p h on y Laboratories) Diagnost ics Soft w are and Hardw are #1-PC Diagn ostics Com p an y (Th e ESD Division of W in d sor Tech n ologies, In c.) Accu rite Tech n ologies In c. Ad van ced Person al System s AllMicro, In c. (Pu rch ased by ForeFron t Direct) Am erican Megatren d s, In c. (AMI) Bu erg, Vern on D. CST CyberMed ia Darkh orse System s Data Dep ot DiagSoft, In c. Flu ke, Joh n Man u factu rin g Com p an y, In c. Gazelle/ GTM Software Gold en Bow System s In n erworks Tech n ology, In c.

Parallel Tech n ologies, In c. Precision Plastics Qu arterd eck Corp oration Rosen th al En gin eerin g Sen core SONERA Tech n ologies Tou ch Ston e Software Corp oration Trin iTech , In c. Ultra-X, In c. Volp e, Han k W allin g Com p an y W atergate Software W ave Tech Dist ribut ors Arrow Electron ic Cal-Abco Com p u ter Com p on en t Sou rce, In c. DakTech Liu ski In tern ation al Merisel Min i Micro Su p p ly Tech Data Corp oration Floppy Drives ALPS Electric Can on USA, In c. Ch in on Am erica, In c.

Vendors by Product or Service Category

Citizen Am erica Corp oration Ma Laboratories, In c. Micro Solu tion s, In c. Mitsu m i Electron ics Corp oration Pan ason ic Com m u n ication s & System s

Hard Disk Drives and Drive Cont rollers Ad ap tec AIW A Am erica, In c. Com p u ter System s Division Fu jitsu Com p u ter Prod u cts of Am erica, In c.

Teac Am erica, In c.

Hewlett-Packard (Disk Mem ory Division )

Tosh iba Am erica, In c.

IBM OEM Division

Y-E Data Am erica, In c.

Iom ega Corp oration

Graphics Adapt ers 3D Labs 3Dfx Alaris ATI Tech n ologies, In c. Boca Research , In c. Ch ip s an d Tech n ologies, In c. Cirru s Logic, In c. Creative Labs, In c. Diam on d Mu ltim ed ia System s, In c. Hau p p au ge Com p u ter W orks, In c. IX Micro Solu tion s, In c. Matrox Grap h ics, In c. Nu m ber Nin e Visu al Tech n ology Corp oration

JTS Corp oration Lon gsh in e Microsystem s, In c. Ma Laboratories, In c. Maxop tix Corp oration Maxtor Corp oration Qu an tu m Corp oration Seagate Tech n ology Sigm a Data SyQu est Tech n ology Tekram Tech n ologies Tosh iba Am erica, In c. W estern Digital Corp oration Hardw are ( Screw s, M ount ing Bracket s, and So On) Arrowfield In tern ation al, In c.

n Vid ia Corp oration

CI Design Com p an y

Orch id Tech n ology (A Division of Micron ics)

Con n ector Resou rces Un lim ited (CRU)

Ren d ition

Globe Man u factu rin g, In c.

S3 In c.

Micro Accessories, In c.

STB System s, In c.

Rad io Sh ack (A Division of Tan d y Corp oration )

Trid en t Microsystem s

1239

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Appendix A—Vendor List

Keyboards ALPS Electric Ch erry Electrical Prod u cts Key Tron ic Corp oration

Microsoft Corp oration Mitsu m i Electron ics Corp oration M iscellaneous Aavid Th erm al Tech n ologies, In c.

Lexm ark

An d rom ed a Research

Maxi Switch , In c.

An vil Cases

Microsoft Corp oration

AT&T Nation al Parts Sales Cen ter/ Lu cen t Tech n ologies

Mitsu m i Electron ics Corp oration M em ory An d rom ed a Research

AZ-COM, In c. Berksh ire Prod u cts

Cen ton Electron ics, In c.

Byte Ru n n er Tech n ologies

Dallas Sem icon d u ctor

Casio, In c.

Hitach i Am erica, Ltd . (Sem icon d u ctor & IC Division )

Ch icago Case Com p an y

IBM Microelectron ics Kin gston Tech n ology Corp oration Ma Laboratories, In c. Micron Tech n ologies (Paren t Com p an y of Micron Electron ics an d Micron Cu stom Man u factu rin g)

Cu rtis Com p u ter Prod u cts Da-Lite Screen Co. Data Exch an ge Corp oration Data Retrieval Services, In c. Data Tech n ology Corp oration (DTC) Digi-Key Corp oration

Mosel Vitelic

Ed m u n d Scien tific

NEC Electron ics, In c.

Extron Electron ics

Pan ason ic In d u strial Co.

Heath kit Ed u cation System s

Ram tron In tern ation al Corp oration

Hyp ertech

Sam su n g Sem icon d u ctor, In c.

IBM Parts Ord er Cen ter

SGS-Th om son Microelectron ics, In c.

Illin ois Lock

Sh arp Microelectron ics Grou p

In lin e, In c.

Sigm a Data

In tern ation al Electron ic Research Corp . (IERC)

Sim p le Tech n ology Texas In stru m en ts, In c.

JC W h itn ey & Com p an y Labcon co Corp oration

M ice ALPS Electric Key Tron ic Corp oration

Learn Key, In c.

Vendors by Product or Service Category

MAGNI System s, In c.

Gold Star Tech n ology, In c.

McKen zie Tech n ology

Hitach i Am erica, Ltd . (Sem icon d u ctor & IC Division )

Merritt Com p u ter Prod u cts, In c. Molex, In c. NCR Microelectron ics Pivar Com p u tin g Services, In c. Rip -Tie Com p an y Safeware In su ran ce Agen cy, In c. Sp ecialized Prod u cts Com p an y Sp ragu e Magn etics, In c. Tan d y Corp oration Th erm alloy In c. Trace Research an d Develop m en t Cen ter Visiflex Seals W yse Tech n ology ZD Com d ex an d Foru m s M odem s 3Com Corp . Boca Research , In c. Creative Labs, In c. Diam on d Mu ltim ed ia System s, In c. Hayes Microcom p u ter Prod u cts Megah ertz Corp oration (A Division of 3Com ) Microcom , In c. Motorola, In c. TDK Corp oration of Am erica M onit ors and Display Devices Am d ek Corp oration (A Division of W yse Tech n ology) Du kan e Corp oration

MAG In n oVision Mitsu bish i Electron ics Am erica, In c. NEC Tech n ologies, In c. Pan ason ic Com m u n ication s & System s Ph ilip s Con su m er Electron ics Sh arp Electron ics Corp oration Son y Corp oration of Am erica Tatu n g Com p an y of Am erica, In c. Tosh iba Am erica, In c. ViewSon ic M ot herboards ABIT Com p u ter (USA) Corp oration Acer Laboratories, In c. (ALi) Ad van ced In tegration Research (AIR) Am erican Megatren d s, In c. (AMI) Diam on d Flower, In c (DFI) Elitegrou p Com p u ter System s, In c. First In tern ation al Com p u ter, In c. (FIC) Giga-Byte Tech n ology Co., Ltd . In tel Corp oration J. Bon d Com p u ter System s Ma Laboratories, In c. Micro In d u stries Corp oration Micron ics Com p u ters, In c. Micro-Star In tern ation al Mylex Corp oration Ocean In form ation System s

1241

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Appendix A—Vendor List

SOYO Tek, In c.

Liebert

Su p erm icro Com p u ter, In c.

SL W aber

Tyan Com p u ter Corp oration

Sola Heavy Du ty Electric (Acq u ired by Best Power, a Division of Gen eral Sign al Power)

Net w orking 3Com Corp . IBM OEM Division In tel PC an d LAN En h an cem en t Prod u ct Division IX Micro Solu tion s, In c. Lan tron ix Lon gsh in e Microsystem s, In c. SMC Networks, In c. (Form erly a Division W ith in Stan d ard Microsystem s Corp .) Xircom Online Services Am erica On lin e Byte In form ation Exch an ge (BIX) Com p u Serve In form ation Service (CIS) Opt ical Drives and M edia Fu jitsu Com p u ter Prod u cts of Am erica, In c.

Trip p Lite Man u factu rin g ViewSon ic Pow er Supplies Astec Am erica, In c. Pan ason ic In d u strial Co. PC Power & Coolin g, In c. Su n Moon Star Su p erp ower Su p p ly, In c. Print ers, Print er Part s, and Supplies ALPS Electric Can on USA, In c. CIE Am erica Citizen Am erica Corp oration Ep son Am erica, In c. (OEM Division ) Fu jitsu Com p u ter Prod u cts of Am erica, In c. Hewlett-Packard Com p an y

Laser Magn etic Storage

Lexm ark

Maxop tix Corp oration

Mitsu bish i Electron ics Am erica, In c.

Microtest En terp rises

NEC Tech n ologies, In c.

Pan ason ic Com m u n ication s & System s

Okid ata

Son y Corp oration of Am erica TDK Corp oration of Am erica Pow er Prot ect ion and UPS Acm e Electric/ Electron ics Division Am erican Power Con version (APC) Best Power (A Division of Gen eral Sign al Power)

Pacific Data Prod u cts Pan ason ic Com m u n ication s & System s PARTS NOW !, In c. Sh arp Electron ics Corp oration Star Micron ics Am erica, In c.

Vendors by Product or Service Category

Un icom p , In c. Y-E Data Am erica, In c. Processors and Processor Upgrades Ad van ced Micro Devices (AMD)

Com p u ter Discou n t W areh ou se (CDW ) Dam ark In tern ation al, In c. IBM PC Direct

Cyrix Corp oration

Jam eco Com p u ter Prod u cts

IBM Microelectron ics

JDR Microd evices

In tel Corp oration

Jen sen Tools, In c.

Kin gston Tech n ology Corp oration

Micro W areh ou se

Ma Laboratories, In c.

Microp rocessors Un lim ited , In c.

Motorola, In c.

Newark Electron ics

Sigm a Data

PC & MAC Con n ection

Texas In stru m en ts, In c. RAID

SCSI Accessories Aeron ics, In c.

Am erican Megatren d s, In c. (AMI)

Meritec

Arco Com p u ter Prod u cts, In c.

Meth od e Electron ics, In c.

Distribu ted Processin g Tech . (DPT)

Micro Design In tern ation al (MDI)

Mylex Corp oration

Mylex Corp oration

Rem ovable M edia 3M Data Storage Prod u cts Division Maxell Corp oration of Am erica Son y Corp oration of Am erica TDK Corp oration of Am erica

Practical En h an ced Logic Qlogic Corp oration Ran ch o Tech n ology, In c. Soft w are Ad obe System s, In c.

Verbatim Corp oration

Au tod esk, In c.

Repair Services Electroservice Laboratories

Bitstream , In c.

Fessen d en Tech n ologies Micro Solu tion s, In c. Ret ail and Direct M ail Altex Electron ics, In c. Black Box Corp oration Boston Com p u ter Exch an ge Com p USA, In c.

Borlan d In tern ation al (Now In p rise) Colu m bia Data Prod u cts Com p ton ’s New Med ia, In c. (A Division of Softkey In tern ation al, In c.) Com p u ter Library Corel System s, In c. Datastorm Tech n ologies, In c. Folio Corp oration

1243

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Appendix A—Vendor List

In form ation Access Com p an y Lotu s Develop m en t Corp oration (A Division of IBM) Map In fo Corp oration McAfee Associates Micro Hou se In tern ation al Micrografx, In c. Microsoft Corp oration Mu stan g Software Novell, In c. PKW are, In c. PowerQu est Corp oration Pu blic Software Library

Com p TIA (Com p u tin g Tech n ology In d u stry Association ) Micro Ch an n el Develop ers Association PCI Sp ecial In terest Grou p PCMCIA—Person al Com p u ter Mem ory Card In tern ation al Association Qu arter-In ch Cartrid ge Drive Stan d ard s, In c. (QIC) Un d erwriters Laboratories, In c. VESA Stan d ard s Supplies ( Chem icals, Cleaners, and So On) CAIG Laboratories

Qu alitas, In c.

Ch em tron ics, In c.

Qu arterd eck Corp oration

D.W . Electroch em icals, Ltd .

Ru p p Tech n ology Corp oration (Retail Location s - Mobilscap e)

GRACE Sp ecialty Polym ers/ W R GRACE, Em erson & Cu m in g In c.

Seagate Software

Tech Sp ray In c.

Sof Tou ch System s, In c. Stac In corp orated Sym an tec Corp oration Th e Learn in g Com p an y Travelin g Software, In c. V Com m u n ication s, In c. Speakers Bose Corp . Labtec En terp rises, In c. St andards Bodies and Organizat ions Am erican Nation al Stan d ard s In stitu te (ANSI) Association of Sh areware Profession als (ASP)

Syst em s ( Deskt op, Server, and M obile) Acer Am erica Corp . Ad van ced Logic Research (ALR) Alaris Ap p le Com p u ter, In c. AST Research , In c. Com p aq Com p u ter Corp oration CTX In tern ation al, In c. Dell Com p u ter Corp oration Diam on d Flower, In c. (DFI) Diversified Tech n ology Dolch Com p u ter System s DTK Com p u ter, In c.

Vendors by Product or Service Category

Ep son Am erica, In c. (OEM Division ) Everex System s, In c. Fu jitsu Com p u ter Prod u cts of Am erica, In c. Gateway 2000 Hewlett-Packard Com p an y Hyu n d ai Electron ics Am erica IBM PC Com p an y Micron Tech n ologies (Paren t Com p an y of Micron Electron ics an d Micron Cu stom Man u factu rin g) Micron ics Com p u ters, In c. MicroW ay, In c. Mitsu bish i Com p u ters, Ltd . Mosel Vitelic Myod a Com p u ter Cen ters NEC Tech n ologies, In c. Olivetti Packard Bell Pan ason ic Com m u n ication s & System s Ph ilip s Con su m er Electron ics Rad io Sh ack (A Division of Tan d y Corp oration ) Sh arp Electron ics Corp oration Tan d y Corp oration Tatu n g Com p an y of Am erica, In c. Tosh iba Am erica, In c. Twin h ead Corp oration UNISYS W an g Laboratories, In c. Zen ith Data System s

Tape Drives and M edia Ad van ced Digital In form ation Corp oration Alloy Com p u ter Prod u cts Exabyte Corp oration GigaTren d , In c. Hewlett-Packard Com p an y Hewlett-Packard (Storage Division ) Laser Magn etic Storage Micro Solu tion s, In c. Mou n tain Network Solu tion s, In c. (Su bsid iary of NCE Star Solu tion s) Seagate Software Storage Man agem en t Grou p (Form erly Sytron ) Storage Dim en sion s, In c. Tecm ar Tech n ologies, In c. Y-E Data Am erica, In c.

1245

B

Appendix B—Useful Hardware Web Sites

Appendix B

Useful Hardware Web Sites

Most of th e ven d ors listed in th e ven d or list in Ap p en d ix A, “Ven d or List,” h ave th eir own W eb sites wh ere you can fin d in form ation abou t th eir sp ecific p rod u cts, services, an d tech n ologies. In ad d ition to th ose, th ere are m an y W eb sites n ot affiliated with an y sp ecific p rod u ct. Th ese ran ge from p rofession al stan d ard s organ ization s th at p u blish d ocu m en ts abou t th e h ard ware th ey write sp ecification s for, to in d ivid u als wh o collect an d d issem in ate u sefu l h ard ware in form ation as a h obby or p et p roject, to ven d ors wh o d istribu te gen eral in form ation th at isn ’t su p p ortin g a sp ecific p rod u ct. An d several of th ese are “m eta-sites” th at collect an d in d ex in form ation from oth er sites. Th is ap p en d ix lists th e sites in th ose areas th at I h ave fou n d m ost u sefu l. Address

Descript ion

elaine.t eleport .com / % 7Ecurt / m odem s.ht m l

High speed modem FAQ

hardw are.pairnet .com

Links to hardware news and reviews

infopad.eecs.berkeley.edu/ CIC

CPU Information

pclt .cis.yale.edu/ pclt / PCHW / PLATYPUS.HTM

General overview of PC hardware technologies

t x.scit exdv.com / SCSI2/ SCSI2.ht m l W eb.idirect .com / ~ frank/ index.ht m l

SCSI 2 Specification Hard drive and CD-ROM specifications

w w w .56k.com

News and information on KFlex, X2, and v.90 standard modems

w w w .agpforum .org

AGP Specifications and information

w w w .anandt ech.com

Reviews of motherboards, processors, and more

w w w .at ipa.com / InfoSheet s/ irqs.sht m l

Troubleshooting COM and IRQ conflicts

w w w .cd-info.com

Compact disc development and production technology (continues)

1247

1248

Appendix B—Useful Hardware Web Sites

(continued)

Address

Descript ion

w w w .chipanalyst .com / q/

M icroprocessor design resources

w w w .chipset .com

Links to chipset vendor Web sites

w w w .cis.ohio-st at e.edu/ hypert ext / faq/ usenet / scsi-faq/ t op.ht m l

SCSI FAQs from USENET

w w w .cis.ohio-st at e.edu/ hypert ext / faq/ usenet -faqs / bygroup/ com p/ sys/ ibm / pc/ hardw are/ t op.ht m l

Links to several hardwarerelated Usenet group FAQs

w w w .cpu-cent ral.com

CPU specifications, information, and reviews

w w w .drivershq.com

Links to hardware drivers

w w w .driverupdat e.com

Windows 95 and 3.1 hardware drivers

w w w .erols.com / chare/ m ain.ht m

Links to processors specifications and FAQs

w w w .firew ire.org

FireWire specification and information

w w w .hardw arecent ral.com

Reviews, FAQs, and more about most PC hardware components

w w w .heart lab.rri.uw o.ca/ vidfaq/ chipset .ht m l

Video chipset FAQ

w w w .irda.org

Infrared technology standards

w w w .isdn.ocn.com

ISDN information and FAQs

w w w .it u.ch

International Telecommunication Union (standards body for modems and other telecommunications)

w w w .k56.org

Specifications on the KFlex version of 56K modems

w w w .lem ig.um ont real.ca/ bios/ bios_sg.ht m

The BIOS survival guide

w w w .m ot herboards.org

M otherboard reviews, tips, and performance comparisons

w w w .m rdriver.com

Links to hardware drivers for many operating systems

w w w .pc-card.com

PCCard and PCM CIA standards

w w w .pcengines.com / sim m .ht m

M emory buyer’s guide

w w w .pcguide.com

General PC hardware information

w w w .pcisig.com

PCI specifications and developments

w w w .pcW ebopedia.com

PC technology encyclopedia and search engine

w w w .ping.be/ bios/ num bers.sht m l

Identifies BIOS by ID numbers

w w w .scsit a.org

SCSI Trade Association’s SCSI information

w w w .sig.net / ~ slogan/ hardw are.ht m

Hardware advice, reviews, and links

Appendix B—Useful Hardware Web Sites

Address

Descript ion

w w w .sldram .com

Information on new SLDRAM memory technology

w w w .spa.org

M PC specifications

w w w .st oragereview .com

Reviews and benchmarks of SCSI and ATA IDE hard drives

w w w .sym bios.com / x3t 10

I/ O information, mainly about SCSI

w w w .sysopt .com

System optimization and performance with special emphasis on motherboards

w w w .t eleport .com / ~ nlx/

NLX motherboard specifications

w w w .t he-view .com

Hardware reviews and news

w w w .t om shardw are.com

Reviews and analysis of motherboards, processors, video cards, and more

w w w .t w eakit .com

Reviews and performance comparisons of new hardware

w w w .t w inight .org/ chipdir/

Directory of chips, manufacturers, pinouts, and so on

w w w .usb.org

USB specifications and information

w w w .vesa.org

VESA standards

w w w .w est .net / ~ jay/ m odem

M odem initialization strings

w w w .w indrivers.com

Hardware drivers for all Windows versions

w w w .w infiles.com / drivers

Windows 95 hardware drivers

w w w .x86.org

“ Secrets” about Intel processors and technologies

w w w csif.cs.ucdavis.edu/ ~ w en/ int el.ht m l

Guide to Intel chipsets

1249

C Glossary

Glossary

Th is glossary con tain s com p u ter an d electron ics term s th at are ap p licable to th e su bject m atter in th is book. Th e glossary is m ean t to be as com p reh en sive as p ossible on th e su bject of u p grad in g or rep airin g PCs. Man y term s corresp on d to th e latest tech n ology in d isk in terfaces, m od em s, vid eo an d d isp lay eq u ip m en t, an d stan d ard s th at govern th e PC in d u stry. Alth ou gh a glossary is a resou rce n ot d esign ed to be read from begin n in g to en d , you sh ou ld fin d th at scan n in g th rou gh th is on e is in terestin g, if n ot en ligh ten in g, with resp ect to som e of th e n ewer PC tech n ology.

Th e com p u ter in d u stry is filled with acron ym s u sed as sh orth an d for a n u m ber of term s. Th is glossary d efin es m an y acron ym s, as well as th e term on wh ich th e acron ym is based . Th e d efin ition of an acron ym u su ally is in clu d ed u n d er th e acron ym . For exam p le, V ideo Graphics Array is d efin ed u n d er th e acron ym V GA rath er th an u n d er V ideo Graphics Array. Th is organ ization m akes it easier to look u p a term —IDE, for exam p le—even if you d o n ot kn ow in ad van ce wh at it stan d s for (Integrated Drive Electronics). For ad d ition al referen ce, Qu e’s Com puter Dictionary (ISBN: 0-7897-1670-4) is a com p reh en sive d iction ary of com p u ter term in ology. Th ese W eb sites can also h elp you with term s th at are n ot in clu d ed in th is ch ap ter: h t t p :/ / z e p p o .c n e t .c o m / Re so u rc e s/ In f o / Gl o ssa ry / h t t p :/ / w w w -e d l a b .u c d a v i s.e d u / e d 1 8 0 / h a rd w a re p ra c t i c u m .h t m l 1 0 Ba se 2 IEEE stan d ard for baseban d Eth ern et at 10Mbp s over RG-58 coaxial cable to a m axim u m d istan ce of 185 m eters. Also kn own as Thin Ethernet (Thinnet) or IEEE 802.3. 1 0 Ba se 5 IEEE stan d ard for baseban d Eth ern et at 10Mbp s over th ick coaxial cable to a m axim u m d istan ce of 500 m eters. Also kn own as Thick Ethernet or Thicknet. 1 0 Ba se T A 10Mbp s CSMA/ CD Eth ern et local area n etwork th at works on Category 3 or better twisted -p air wirin g th at is very sim ilar to stan d ard telep h on e cablin g. 10BaseT Eth ern et local area n etworks work on a “star” con figu ration in wh ich th e wire from each workstation rou tes d irectly to a 10BaseT h u b. Hu bs m ay be join ed togeth er. 1 0 0 Ba se T A 100Mbp s CSMA/ CD Eth ern et local area n etwork th at works on Category 5 twisted -p air wirin g. 100BaseT Eth ern et local area n etworks work on a “star” con figu ration in wh ich th e wire from each workstation rou tes d irectly to a cen tral 100BaseT h u b. Th is is th e n ew stan d ard for 100Mbp s Eth ern et.

1251

1252

Glossary

1 0 0 Ba se VG Th e join t Hewlett-Packard -AT&T p rop osal for Fast Eth ern et ru n n in g at 100Mbp s. It u ses fou r p airs of Category 5 cable u sin g th e 10BaseT twisted -p air wirin g sch em e to tran sm it or receive. 100BaseVG sp lits th e sign al across th e fou r wire p airs at 25MHz each . Th is stan d ard h as n ot fou n d favor with corp oration s an d h as been alm ost totally rep laced by 100BaseT. 56K

Th e gen eric term for m od em s th at can receive d ata at 56Kbp s. See also V .90, X 2, Kflex.

286

See 80286.

386

See 80386.

486

See 80486.

586

A gen eric term u sed to refer to fifth -gen eration p rocessors sim ilar to th e In tel Pen tiu m .

6 4 0 K b a rri e r Th e lim it im p osed by th e PC-com p atible m em ory m od el u sin g DOS m od e. DOS p rogram s can ad d ress on ly 1M total m em ory, an d PC-com p atibility gen erally req u ires th e top 384K to be reserved for th e system , leavin g on ly th e lower 640K for DOS or oth er real-m od e ap p lication s. 8086

An In tel m icrop rocessor with 16-bit registers, a 16-bit d ata bu s, an d a 20-bit ad d ress bu s. Th is p rocessor can op erate on ly in real m od e.

8087

An In tel m ath cop rocessor d esign ed to p erform floatin g-p oin t m ath with m u ch greater sp eed an d p recision th an th e m ain CPU. Th e 8087 can be in stalled in m ost 8086- an d 8088-based system s, an d ad d s m ore th an 50 n ew in stru ction s to th ose available in th e p rim ary CPU alon e.

8088

An In tel m icrop rocessor with 16-bit registers, an 8-bit d ata bu s, an d a 20-bit ad d ress bu s. Th is p rocessor can op erate on ly in real m od e, an d was d esign ed as a low-cost version of th e 8086.

8 5 1 4 / A An an alog vid eo d isp lay ad ap ter from IBM for th e PS/ 2 lin e of p erson al com p u ters. Com p ared to p reviou s d isp lay ad ap ters su ch as EGA an d VGA, it p rovid es a h igh resolu tion of 1,024×768 p ixels with as m an y as 256 colors or 64 sh ad es of gray. It p rovid es a vid eo cop rocessor th at p erform s two-d im en sion al grap h ics fu n ction s in tern ally, th u s relievin g th e CPU of grap h ics tasks. It u ses an in terlaced m on itor; it scan s every oth er lin e every tim e th e screen is refresh ed . 8 0 2 8 6 An In tel m icrop rocessor with 16-bit registers, a 16-bit d ata bu s, an d a 24-bit ad d ress bu s. It can op erate in both real an d p rotected virtu al m od es. 8 0 2 8 7 An In tel m ath cop rocessor d esign ed to p erform floatin g-p oin t m ath with m u ch greater sp eed an d p recision th an th e m ain CPU. Th e 80287 can be in stalled in m ost 286- an d som e 386DX-based system s, an d ad d s m ore th an 50 n ew in stru ction s to wh at is available in th e p rim ary CPU alon e. 80386

See 80386DX .

8 0 3 8 6 D X An In tel m icrop rocessor with 32-bit registers, a 32-bit d ata bu s, an d a 32-bit ad d ress bu s. Th is p rocessor can op erate in real, p rotected virtu al, an d virtu al real m od es.

Glossary

8 0 3 8 6 SX An In tel m icrop rocessor with 32-bit registers, a 16-bit d ata bu s, an d a 24-bit ad d ress bu s. Th is p rocessor, d esign ed as a low-cost version of th e 386DX, can op erate in real, p rotected virtu al, an d virtu al real m od es. 8 0 3 8 7 An In tel m ath cop rocessor d esign ed to p erform floatin g-p oin t m ath with m u ch greater sp eed an d p recision th an th e m ain CPU. Th e 80387 can be in stalled in m ost 386DX-based system s, an d ad d s m ore th an 50 n ew in stru ction s to th ose available in th e p rim ary CPU alon e. 80486

See 80486DX .

8 0 4 8 6 D X An In tel m icrop rocessor with 32-bit registers, a 32-bit d ata bu s, an d a 32-bit ad d ress bu s. Th e 486DX h as a bu ilt-in cach e con troller with 8K of cach e m em ory as well as a bu ilt-in m ath cop rocessor eq u ivalen t to a 387DX. Th e 486DX can op erate in real, p rotected virtu al, an d virtu al real m od es. 8 0 4 8 6 D X2 A version of th e 486DX with an in tern al clock d ou blin g circu it th at cau ses th e ch ip to ru n at twice th e m oth erboard clock sp eed . If th e m oth erboard clock is 33MHz, th e DX2 ch ip will ru n at 66MHz. Th e DX2 d esign ation ap p lies to ch ip s sold th rou gh th e OEM m arket, wh ile a retail version of th e DX2 is sold as an overd rive p rocessor. 8 0 4 8 6 D X4 A version of th e 486DX with an in tern al clock trip lin g circu it th at cau ses th e ch ip to ru n at th ree tim es th e m oth erboard clock sp eed . If th e m oth erboard clock is 33.33MHz, th e DX4 ch ip will ru n at 100MHz. 8 0 4 8 6 SX An In tel m icrop rocessor with 32-bit registers, a 32-bit d ata bu s, an d a 32-bit ad d ress bu s. Th e 486SX is th e sam e as th e 486DX excep t th at it lacks th e bu ilt-in m ath cop rocessor fu n ction , an d was d esign ed as a low-cost version of th e 486DX. Th e 486SX can op erate in real, p rotected virtu al, an d virtu al real m od es. a b e n d Sh ort for abnorm al end. A con d ition occu rrin g wh en th e execu tion of a p rogram or task is term in ated u n exp ected ly becau se of a bu g or crash . a b so l u t e a d d re ss An exp licit id en tification of a m em ory location , d evice, or location with in a d evice. AC Altern atin g cu rren t. Th e freq u en cy is m easu red in cycles p er secon d s (cp s), or h ertz (Hz). Th e stan d ard valu e ru n n in g th rou gh th e wall ou tlet is 120 volts at 60Hz, th rou gh a fu se or circu it breaker th at u su ally can h an d le abou t 15 or 20 am p s. a c c e l e ra t o r b o a rd An ad d -in board rep lacin g th e com p u ter’s CPU with circu itry th at en ables th e system to ru n faster. See graphics accelerator. a c c e ss l i g h t Th e LED on th e fron t of a d rive or oth er d evice (or on th e fron t p an el of th e system ) th at in d icates th e com p u ter is read in g or writin g d ata on th e d evice. a c c e ss m e c h a n i sm

See actuator.

a c c e ss t i m e Th e tim e th at elap ses from th e in stan t in form ation is req u ested to th e p oin t th at d elivery is com p leted . Usu ally d escribed in n an osecon d s (n s) for m em ory ch ip s, an d in m illisecon d s (m s) for d isk d rives. Most m an u factu rers rate average access tim e on a h ard d isk as th e tim e req u ired for a seek across on e th ird of th e total n u m ber of cylin d ers p lu s on e h alf of th e tim e for a sin gle revolu tion of th e d isk p latters (laten cy).

1253

1254

Glossary

accu m u lat o r form ed .

A register (tem p orary storage) in wh ich th e resu lt of an op eration is

a c o u st i c c o u p l e r A d evice u sed to con n ect a com p u ter m od em to a p h on e lin e by con n ectin g to th e h an d set of a stan d ard AT&T-style p h on e. Th e au d ible sou n d s to an d from th e m od em are tran sm itted to th e h an d set th rou gh th e cou p ler wh ile th e h an d set is restin g in th e cou p ler. Alth ou gh often th ou gh t of as obsolete, an acou stic cou p ler can be u sed to en su re th e availability of a m od em con n ection wh en travelin g an d access to an RJ-11 jack is u n available. ACP I

Ad van ced Con figu ration an d Power In terface. A stan d ard d evelop ed by In tel, Microsoft, an d Tosh iba th at is d esign ed to im p lem en t p ower m an agem en t fu n ction s in th e op eratin g system . ACPI is a rep lacem en t for APM. See also APM.

a c t i v e h i g h Design ates a d igital sign al th at h as to go to a h igh valu e to be tru e. Syn on ym ou s with positive. a c t i v e l o w Design ates a d igital sign al th at h as to go to a low valu e to be tru e. Syn on ym ou s with negative. a c t i v e m a t ri x A typ e of LCD screen th at con tain s at least on e tran sistor for every p ixel on th e screen . Color active m atrix screen s u se th ree tran sistors for each p ixel, on e each for th e red , green , an d blu e d ots. Th e tran sistors are arran ged on a grid of con d u ctive m aterial, with each con n ected to a h orizon tal an d a vertical m em ber. See also TFT. a c t u a t o r Th e d evice th at m oves a d isk d rive’s read / write h ead s across th e p latter su rfaces. Also kn own as an access m echanism . a d a p t e r Th e d evice th at serves as an in terface between th e system u n it an d th e d evices attach ed to it. Often syn on ym ou s with circu it board , circu it card , or card , bu t m ay also refer to a con n ector or cable ad ap ter, wh ich ch an ges on e typ e of con n ector to an oth er. a d a p t e r d e sc ri p t i o n f i l e s (AD F) Refers to th e setu p an d con figu ration files, an d d rivers n ecessary to in stall an ad ap ter card su ch as a n etwork ad ap ter card . Prim arily u sed with Micro Ch an n el Arch itectu re bu s card s. a d d -i n b o a rd

See expansion card.

a d d re ss Refers to wh ere a p articu lar p iece of d ata or oth er in form ation is fou n d in th e com p u ter. Also can refer to th e location of a set of in stru ction s. a d d re ss b u s On e or m ore electrical con d u ctors u sed to carry th e bin ary-cod ed ad d ress from th e m icrop rocessor th rou gh ou t th e rest of th e system . AGP

Accelerated Grap h ics Port. Develop ed by In tel, a fast d ed icated in terface between th e vid eo ad ap ter or ch ip set an d th e m oth erboard ch ip set North Brid ge. AGP is 32 bits wid e, ru n s at 66MHz, an d can tran sfer 1 or 2 bits p er cycle (1x or 2x m od es).

a l i a si n g Un d esirable visu al effects (som etim es called artifacts) in com p u ter-gen erated im ages, cau sed by in ad eq u ate sam p lin g tech n iq u es. Th e m ost com m on effect is jagged ed ges alon g d iagon al or cu rved object bou n d aries. See also anti-aliasing. allo cat io n u n it

See cluster.

Glossary

a l p h a n u m e ri c c h a ra c t e rs A ch aracter set th at con tain s on ly letters (A–Z) an d d igits (0–9). Oth er ch aracters, su ch as p u n ctu ation m arks, m ay also be allowed . a m p e re

Th e basic u n it for m easu rin g electrical cu rren t. Also called am p.

a n a l o g Th e rep resen tation of n u m erical valu es by p h ysical variables su ch as voltage, cu rren t, an d so on ; con tin u ou sly variable q u an tities wh ose valu es corresp on d to th e q u an titative m agn itu d e of th e variables. See also digital. a n a l o g l o o p b a c k A m od em self-test in wh ich d ata from th e keyboard is sen t to th e m od em ’s tran sm itter, m od u lated in to an alog form , loop ed back to th e receiver, d em od u lated in to d igital form , an d retu rn ed to th e screen for verification . a n a l o g si g n a l s Con tin u ou sly variable sign als. An alog circu its are m ore su bject to d istortion an d n oise th an are d igital circu its bu t are cap able of h an d lin g com p lex sign als with relatively sim p le circu itry. See also digital signals. a n a l o g -t o -d i g i t a l c o n v e rt e r d igital form . AND

An electron ic d evice th at con verts an alog sign als to

A logic op erator h avin g th e p rop erty th at if P is a statem en t, Q is a statem en t, R is a statem en t…, th en th e AND of P, Q, R… is tru e if all statem en ts are tru e an d is false if an y statem en t is false.

AND g a t e

A logic gate in wh ich th e ou tp u t is 1 on ly if all in p u ts are 1.

a n i m a t i o n Th e p rocess of d isp layin g a seq u en tial series of still im ages to ach ieve a m otion effect. ANSI

Am erican Nation al Stan d ard s In stitu te. A n on govern m en tal organ ization fou n d ed in 1918 to p rop ose, m od ify, ap p rove, an d p u blish d ata p rocessin g stan d ard s for volu n tary u se in th e Un ited States. Also th e U.S. rep resen tative to th e In tern ation al Stan d ard s Organ ization (ISO) in Paris an d th e In tern ation al Electrotech n ical Com m ission (IEC). For m ore in form ation , see Ap p en d ix A, “Ven d or List.” Con tact ANSI, 1430 Broad way, New York, NY 10018.

a n sw e r m o d e A state in wh ich th e m od em tran sm its at th e p red efin ed h igh freq u en cy of th e com m u n ication s ch an n el an d receives at th e low freq u en cy. Th e tran sm it/ receive freq u en cies are th e reverse of th e callin g m od em , wh ich is in origin ate m od e. See also originate m ode. a n t i -a l i a si n g Software ad ju stm en t to m ake d iagon al or cu rved lin es ap p ear sm ooth an d con tin u ou s in com p u ter-gen erated im ages. See also aliasing. a n t i -st a t i c m a t A p ad p laced n ext to a com p u ter u p on wh ich com p on en ts are p laced wh ile servicin g th e system to p reven t static d am age. Also can refer to a larger sized m at below an en tire com p u ter d esk an d ch air to d isch arge static from a u ser before h e tou ch es th e com p u ter. a n t i -v i ru s Software th at p reven ts files con tain in g viru ses from ru n n in g on a com p u ter or software th at d etects, rep airs, clean s, or rem oves viru s-in fected files. AP A

All p oin ts ad d ressable. A m od e in wh ich all p oin ts of a d isp layable im age can be con trolled by th e u ser or a p rogram .

a p e rt u re g ri l l e A typ e of sh ad ow m ask u sed in CRTs. Th e m ost com m on is u sed in Son y’s Trin itron m on itors, wh ich u se vertical p h osp h or strip es an d vertical slots in

1255

1256

Glossary

th e m ask, com p ared to th e trad ition al sh ad ow m ask th at u ses p h osp h or d ots an d rou n d h oles in th e m ask. See also shadow m ask. AP I

Ap p lication Program In terface. A system call (rou tin e) th at gives p rogram m ers access to th e services p rovid ed by th e op eratin g system . In IBM-com p atible system s, th e ROM BIOS an d DOS togeth er p resen t an API th at a p rogram m er can u se to con trol th e system h ard ware.

AP M

Ad van ced Power Man agem en t. A sp ecification sp on sored by In tel an d Microsoft origin ally p rop osed to exten d th e life of batteries in battery-p owered com p u ters. It is n ow u sed in d esktop com p u ters, as well. APM allows ap p lication p rogram s, th e system BIOS, an d th e h ard ware to work togeth er to red u ce p ower con su m p tion . An APM-com p lian t BIOS p rovid es bu ilt-in p ower m an agem en t services to th e op eratin g system . Th e ap p lication software com m u n icates p ower-savin g d ata via p red efin ed APM in terfaces. Rep laced in n ewer system s by ACPI. See also ACPI.

a p p l i c a t i o n En d -u ser orien ted software su ch as a word p rocessor, sp read sh eet, d atabase, grap h ics ed itor, gam e, or W eb browser. a rb i t ra t i o n A m eth od by wh ich m u ltip le d evices attach ed to a sin gle bu s can bid or arbitrate to get con trol of th at bu s. a rc h i v e b i t Th e bit in a file’s attribu te byte th at sets th e arch ive attribu te. Tells wh eth er th e file h as been ch an ged sin ce it last was backed u p . a rc h i v e m e d i u m A storage m ed iu m (flop p y d isk, tap e cartrid ge, or rem ovable cartrid ge) to h old files th at n eed n ot be accessible in stan tly. ARCn e t Attach ed Resou rce Com p u ter Network. A baseban d , token -p assin g local area n etwork tech n ology offerin g a flexible bu s/ star top ology for con n ectin g p erson al com p u ters. Op eratin g at 2.5Mbit/ sec, it is on e of th e old est LAN system s an d was p op u lar in low-cost n etworks. Origin ally d evelop ed by Joh n Mu rp h y of Datap oin t Corp oration , alth ou gh ARCn et in terface card s are available from a variety of ven d ors. a re a l d e n si t y A calcu lation of th e bit d en sity (bits p er in ch , or BPI) m u ltip lied by th e track d en sity (tracks p er in ch , or TPI), wh ich resu lts in a figu re in d icatin g h ow m an y bits p er sq u are in ch are p resen t on th e d isk su rface. ARQ

Au tom atic rep eat req u est. A gen eral term for error-con trol p rotocols th at featu re error d etection an d au tom atic retran sm ission of d efective blocks of d ata.

ASCII Am erican Stan d ard Cod e for In form ation In terch an ge. A stan d ard 7-bit cod e created in 1965 by Robert W . Bem er to ach ieve com p atibility am on g variou s typ es of d ata p rocessin g eq u ip m en t. Th e stan d ard ASCII ch aracter set con sists of 128 d ecim al n u m bers ran gin g from 0 th rou gh 127, wh ich are assign ed to letters, n u m bers, p u n ctu ation m arks, an d th e m ost com m on sp ecial ch aracters. In 1981, IBM in trod u ced th e exten d ed ASCII ch aracter set with th e IBM PC, exten d in g th e cod e to 8 bits an d ad d in g ch aracters from 128 th rou gh 255 to rep resen t ad d ition al sp ecial m ath em atical, grap h ics, an d foreign ch aracters. ASCII c h a ra c t e r A 1-byte ch aracter from th e ASCII ch aracter set, in clu d in g alp h abetic an d n u m eric ch aracters, p u n ctu ation sym bols, an d variou s grap h ics ch aracters. ASME Am erican Society of Mech an ical En gin eers (h t t p :/ / w w w .a sm e .o rg / ). ASME In tern ation al h as n early 600 cod es an d stan d ard s in p rin t, an d its m an y

Glossary

com m ittees in volve m ore th an 3,000 in d ivid u als, m ostly en gin eers bu t n ot n ecessarily m em bers of th e society. Th e stan d ard s are u sed in m ore th an 90 cou n tries th rou gh ou t th e world . a sp e c t ra t i o Th e m easu rem en t of a film or television viewin g area in term s of relative h eigh t an d wid th . Th e asp ect ratio of m ost m od ern m otion p ictu res varies between 3:5 to as large as 3:7, wh ich creates a p roblem wh en a wid e-form at m otion p ictu re is tran sferred to th e m ore sq u are-sh ap ed television screen , with its asp ect ratio of 3:4. a sse m b l e Th e act of tran slatin g a p rogram exp ressed in an assem bler lan gu age in to a com p u ter m ach in e lan gu age. a sse m b l e r l a n g u a g e A com p u ter-orien ted lan gu age wh ose in stru ction s are u su ally in on e-to-on e corresp on d en ce with m ach in e lan gu age in stru ction s. a sy m m e t ri c a l m o d u l a t i o n A d u p lex tran sm ission tech n iq u e th at sp lits th e com m u n ication s ch an n el in to on e h igh -sp eed ch an n el an d on e slower ch an n el. Du rin g a call u n d er asym m etrical m od u lation , th e m od em with th e greater am ou n t of d ata to tran sm it is allocated th e h igh -sp eed ch an n el. Th e m od em with less d ata is allocated th e slow, or back, ch an n el. Th e m od em s d yn am ically reverse th e ch an n els d u rin g a call if th e volu m e of d ata tran sfer ch an ges. a sy n c h ro n o u s c o m m u n i c a t i o n Data tran sm ission in wh ich th e len gth of tim e between tran sm itted ch aracters m ay vary. Tim in g is d ep en d en t on th e actu al tim e for th e tran sfer to take p lace, as op p osed to syn ch ron ou s com m u n ication , wh ich is tim ed rigid ly by an extern al clock sign al. Becau se th e receivin g m od em m u st be sign aled abou t wh en th e d ata bits of a ch aracter begin an d en d , start an d stop bits are ad d ed to each ch aracter. See also synchronous com m unication. a sy n c h ro n o u s m e m o ry Mem ory th at ru n s u sin g a d ifferen t tim in g or clock rate (u su ally slower) th an th e m oth erboard sp eed . AT c l o c k Refers to th e Motorola 146818 realtim e clock (RTC) an d CMOS RAM ch ip wh ich first d ebu ted in th e IBM AT an d wh ose fu n ction h as been p resen t in all PCcom p atible system s sin ce. Keep s track of th e tim e of d ay an d m akes th is d ata available to th e op eratin g system or oth er software. ATA

AT Attach m en t in terface. An IDE d isk in terface stan d ard in trod u ced in March 1989 th at d efin es a com p atible register set an d a 40-p in con n ector an d its associated sign als. See also IDE.

ATA-2 Th e secon d gen eration AT Attach m en t in terface sp ecification . Th is version d efin es faster tran sfer m od es an d Logical Block Ad d ressin g sch em es to allow h igh p erform an ce large-cap acity d rives. Also called Fast ATA, Fast ATA-2, an d Enhanced IDE (EIDE). ATAP I AT Attach m en t Packet In terface. A sp ecification th at d efin es d evice-sid e ch aracteristics for an IDE-con n ected p erip h eral, su ch as CD-ROM or tap e d rives. ATAPI is essen tially an ad ap tation of th e SCSI com m an d set to th e IDE in terface. ATM

Asyn ch ron ou s Tran sfer Mod e. A h igh -ban d wid th , low-d elay, p acket-like switch in g an d m u ltip lexin g tech n iq u e. Usable cap acity is segm en ted in to fixed -size cells con sistin g of h ead er an d in form ation field s, allocated to services on d em an d .

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a t t ri b u t e b y t e A byte of in form ation , h eld in th e d irectory en try of an y file, th at d escribes variou s attribu tes of th e file, su ch as wh eth er it is read -on ly or h as been backed u p sin ce it last was ch an ged . Attribu tes can be set by th e DOS ATTRIB com m an d . ATX

A m oth erboard an d p ower su p p ly form -factor stan d ard d esign ed by In tel an d in trod u ced in 1995 th at is ch aracterized by a d ou ble row of rear extern al I/ O con n ectors on th e m oth erboard ; a sin gle keyed p ower su p p ly con n ector; m em ory an d p rocessor location s th at are d esign ed n ot to in terfere with th e in stallation of ad ap ter card s; an d an im p roved coolin g flow.

a u d i o A sign al th at can be h eard , su ch as th rou gh th e sp eaker of th e PC. Man y PC d iagn ostics tests u se both visu al (on screen ) cod es an d au d io sign als. a u d i o f re q u e n c i e s 20–20,000Hz).

Freq u en cies th at can be h eard by th e h u m an ear (ap p roxim ately

a u t o a n sw e r A settin g in m od em s en ablin g th em to an swer in com in g calls over th e p h on e lin es au tom atically. a u t o d i a l A featu re in m od em s en ablin g th em to d ial p h on e n u m bers with ou t h u m an in terven tion . a u t o -d i sc o n n e c t A m od em featu re th at allows a m od em to h an g u p th e telep h on e lin e wh en th e m od em at th e oth er en d h an gs u p . AUTOEXEC.BAT A sp ecial batch file th at DOS execu tes at startu p . Con tain s an y n u m ber of DOS com m an d s th at are execu ted au tom atically, in clu d in g th e cap ability to start p rogram s at startu p . See also batch file. a u t o m a t i c h e a d p a rk i n g Disk d rive h ead p arkin g p erform ed wh en ever th e d rive is p owered off. Fou n d in all m od ern h ard d isk d rives with a voice-coil actu ator. a u t o -re d i a l A m od em or software featu re th at au tom atically red ials th e last n u m ber d ialed if th e n u m ber is bu sy or d oes n ot an swer. a v a i l a b l e m e m o ry Mem ory cu rren tly n ot in u se by th e op eratin g system , d rivers, or ap p lication s th at m ay be u sed to load ad d ition al software. a v e ra g e a c c e ss t i m e Th e average tim e it takes a d isk d rive to begin read in g an y d ata p laced an ywh ere on th e d rive. Th is in clu d es th e average seek tim e, wh ich is wh en th e h ead s are m oved , as well as th e laten cy, wh ich is th e average am ou n t of tim e req u ired for an y given d ata sector to p ass u n d ern eath th e h ead s. Togeth er, th ese factors m ake u p th e average access tim e. See also average seek tim e an d latency. a v e ra g e l a t e n c y Th e average tim e req u ired for an y byte of d ata stored on a d isk to rotate u n d er th e d isk d rive’s read / write h ead . Eq u al to on e h alf th e tim e req u ired for a sin gle rotation of a p latter. a v e ra g e se e k t i m e Th e average am ou n t of tim e it takes to m ove th e h ead s from on e ran d om cylin d er location to an oth er, u su ally in clu d in g an y h ead settlin g tim e. In m an y cases, th e average seek tim e is d efin ed as th e seek tim e across on e th ird of th e total n u m ber of cylin d ers. AVI

Au d io Vid eo In terleave. A storage tech n iq u e d evelop ed by Microsoft for its Vid eo for W in d ows p rod u ct th at com bin es au d io an d vid eo in to a sin gle fram e or track,

Glossary

savin g valu able d isk sp ace an d keep in g au d io in syn ch ron ization with th e corresp on d in g vid eo. b a c k b o n e Th e p ortion of th e In tern et or wid e area n etwork (W AN) tran sm ission wirin g th at con n ects th e m ain In tern et/ W AN servers an d rou ters an d is resp on sible for carryin g th e bu lk of th e In tern et/ W AN d ata. b a c k p l a n e A rarely u sed m oth erboard d esign in wh ich th e com p on en ts n orm ally fou n d on a m oth erboard are located in stead on an exp an sion ad ap ter card p lu gged in to a slot. In th ese system s, th e board with th e slots is th e backp lan e. b a c k u p Th e p rocess of d u p licatin g a file or library on to a sep arate p iece of m ed ia. Good in su ran ce again st th e loss of an origin al. b a c k u p d i sk Con tain s in form ation cop ied from an oth er d isk. Used to m ake su re th at origin al in form ation is n ot d estroyed or altered . b a c k w a rd c o m p a t i b i l i t y Th e d esign of software an d h ard ware to work with p reviou s version s of th e sam e software or h ard ware. b a d se c t o r A d isk sector th at can n ot h old d ata reliably becau se of a m ed ia flaw or d am aged form at m arkin gs. b a d t ra c k t a b l e A label affixed to th e casin g of a h ard d isk d rive th at tells wh ich tracks are flawed an d can n ot h old d ata. Th e listin g is en tered in to th e low-level form attin g p rogram . b a l a n c e d si g n a l Refers to sign als con sistin g of eq u al cu rren ts m ovin g in op p osite d irection s. W h en balan ced or n early balan ced sign als p ass th rou gh twisted -p air lin es, th e electrom agn etic in terferen ce effects su ch as crosstalk cau sed by th e two op p osite cu rren ts largely can cel each oth er ou t. Differential signaling is a m eth od th at u ses balan ced sign als. b a l u n Sh ort for balan ced / u n balan ced . A typ e of tran sform er th at en ables balan ced cables to be join ed with u n balan ced cables. Twisted -p air (balan ced ) cables, for exam p le, can be join ed with coaxial (u n balan ced ) cables if th e p rop er balu n tran sform er is u sed . b a n d w i d t h 1) Gen erally, th e m easu re of th e ran ge of freq u en cies with in a rad iation ban d req u ired to tran sm it a p articu lar sign al. Th e d ifferen ce between th e lowest an d h igh est sign al freq u en cies. Th e ban d wid th of a com p u ter m on itor is a m easu re of th e rate th at a m on itor can h an d le in form ation from th e d isp lay ad ap ter. Th e wid er th e ban d wid th , th e m ore in form ation th e m on itor can carry, an d th e greater th e resolu tion . 2) Used to d escribe th e d ata-carryin g cap acity of a given com m u n ication s circu it or p ath way. Th e ban d wid th of a circu it is a m easu re of th e rate at wh ich in form ation can be p assed . ban k

Th e collection of m em ory ch ip s or m od u les th at m ake u p a block of m em ory read able or writable by th e p rocessor in a sin gle cycle. Th is block, th erefore, m u st be as large as th e d ata bu s of th e p articu lar m icrop rocessor. In PC system s, th e p rocessor d ata bu s (an d th erefore th e ban k size) is u su ally 8, 16, 32, or 64 bits wid e. Op tion ally, som e system s also in corp orate an ad d ition al p arity or ECC bit for each 8 d ata bits, resu ltin g in a total of 9, 18, 36, or 72 bits (resp ectively) for each ban k. Mem ory in a PC m u st always be ad d ed or rem oved in fu ll-ban k in crem en ts.

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Glossary

b a r c o d e Th e cod e u sed on con su m er p rod u cts an d in ven tory p arts for id en tification p u rp oses. Con sists of bars of varyin g th ickn ess th at rep resen t ch aracters an d n u m erals th at are read with an op tical read er. Th e m ost com m on version is called th e Universal Product Code (UPC). b a se -2 Refers to th e com p u ter n u m berin g system th at con sists of two n u m erals: 0 an d 1. Also called binary. b a se a d d re ss p orts.

Startin g location for con secu tive strin g of m em ory or I/ O ad d resses/

b a se m e m o ry Th e am ou n t of m em ory available to th e op eratin g system or ap p lication p rogram s with in th e first m egabyte, accessible in th e p rocessor’s real m od e. b a se b a n d t ra n sm i ssi o n Th e tran sm ission of d igital sign als over a lim ited d istan ce. ARCn et an d Eth ern et local area n etworks u se baseban d sign alin g. Con trasts with broadband transm ission, wh ich refers to th e tran sm ission of an alog sign als over a greater d istan ce. BASIC Begin n er’s All-p u rp ose Sym bolic In stru ction Cod e. A p op u lar com p u ter p rogram m in g lan gu age. Origin ally d evelop ed by Joh n Kem en y an d Th om as Ku rtz in th e m id -1960s at Dartm ou th College. Norm ally, an in terp retive lan gu age, m ean in g th at each statem en t is tran slated an d execu ted as it is en cou n tered , bu t can be a com p iled lan gu age, in wh ich all th e p rogram statem en ts are com p iled before execu tion . b a t c h f i l e A set of com m an d s stored in a d isk file for execu tion by th e op eratin g system . A sp ecial batch file called AUTOEX EC.BAT is execu ted by DOS each tim e th e system is started . All DOS batch files h ave a BAT file exten sion . baud

A u n it of sign alin g sp eed d en otin g th e n u m ber of d iscrete sign al elem en ts th at can be tran sm itted p er secon d . Th e word baud is d erived from th e n am e of J.M.E. Bau d ot (1845-1903), a Fren ch p ion eer in th e field of p rin tin g telegrap h y an d th e in ven tor of Bau d ot cod e. Alth ou gh tech n ically in accu rate, baud rate com m on ly is u sed to m ean bit rate. Becau se each sign al elem en t or bau d m ay tran slate in to m an y in d ivid u al bits, bits per second (bps) n orm ally d iffers from bau d rate. A rate of 2400 bau d m ean s th at 2,400 freq u en cy or sign al ch an ges p er secon d are bein g sen t, bu t each freq u en cy ch an ge m ay sign al several bits of in form ation . For exam p le, 33.6Kbp s m od em s actu ally tran sm it at on ly 2,400 bau d .

Ba u d o t c o d e A 5-bit cod e u sed in m an y typ es of d ata com m u n ication s, in clu d in g teletyp e (TTY), rad io teletyp e (RTTY), an d telecom m u n ication s d evices for th e d eaf (TDD). Bau d ot cod e h as been revised an d exten d ed several tim es. See also baud. bay

An op en in g in a com p u ter case or ch assis th at h old s d isk d rives.

B-c h a n n e l Th e two bearer ch an n els in ISDN th at ru n at 64Kbp s each an d th at carry th e d ata. BBS

bezel

Bu lletin board system . A com p u ter th at op erates with a p rogram an d a m od em to en able oth er com p u ters with m od em s to com m u n icate with it, often on a rou n d th e-clock basis. Th ou san d s of PC IBM- an d Ap p le-related BBSs offer a wealth of in form ation an d p u blic-d om ain software th at can be d own load ed . A cosm etic p an el th at covers th e face of a d rive or som e oth er d evice.

Glossary

Bé z i e r c u rv e A m ath em atical m eth od for d escribin g a cu rve, often u sed in illu stration an d CAD p rogram s to d raw com p lex sh ap es. b i d i re c t i o n a l 1) Refers to lin es over wh ich d ata can m ove in two d irection s, su ch as a d ata bu s or a telep h on e lin e. 2) Refers to th e cap ability of a p rin ter to p rin t from righ t to left an d from left to righ t altern ately. b i n a ry Refers to th e com p u ter n u m berin g system th at con sists of two n u m erals: 0 an d 1. Also called base-2. BIOS

Basic In p u t/ Ou tp u t System . Th e p art of an op eratin g system th at h an d les th e com m u n ication s between th e com p u ter an d its p erip h erals. Often bu rn ed in to read -on ly m em ory (ROM) ch ip s or rewritable flash (EEPROM) m em ory ch ip s.

b i p o l a r A category of sem icon d u ctor circu it d esign , wh ich was u sed to create th e first tran sistor an d th e first in tegrated circu it. Bip olar an d CMOS are th e two m ajor tran sistor tech n ologies. Most all p erson al com p u ters u se CMOS tech n ology ch ip s. CMOS u ses far less en ergy th an bip olar. b i sy n c h ro n o u s Bin ary syn ch ron ou s con trol. An earlier p rotocol d evelop ed by IBM for software ap p lication s an d com m u n icatin g d evices op eratin g in syn ch ron ou s en viron m en ts. Th e p rotocol d efin es op eration s at th e lin k level of com m u n ication s— for exam p le, th e form at of d ata fram es exch an ged between m od em s over a p h on e lin e. bit

Bin ary d igit. Rep resen ted logically by 0 or 1 an d electrically by 0 volts an d (typ ically) 5 volts. Oth er m eth od s are u sed to rep resen t bin ary d igits p h ysically (ton es, d ifferen t voltages, ligh ts, an d so on ), bu t th e logic is always th e sam e.

b i t d e n si t y Exp ressed as bits p er in ch (BPI). Defin es h ow m an y bits can be written on to on e lin ear in ch of a track. Som etim es also called linear density. b i t d e p t h Th e n u m ber of bits u sed to d escribe th e color of each p ixel on a com p u ter d isp lay. For exam p le, a bit d ep th of two m ean s th at th e m on itor can d isp lay on ly black an d wh ite p ixels; a bit d ep th of fou r m ean s th e m on itor can d isp lay 16 d ifferen t colors; a bit d ep th of eigh t allows for 256 colors; an d so on . b i t m a p A m eth od of storin g grap h ics in form ation in m em ory in wh ich a bit d evoted to each p ixel (p ictu re elem en t) on screen in d icates wh eth er th at p ixel is on or off. A bit m ap con tain s a bit for each p oin t or d ot on a vid eo d isp lay screen an d allows for fin e resolu tion becau se an y p oin t or p ixel on screen can be ad d ressed . A greater n u m ber of bits can be u sed to d escribe each p ixel’s color, in ten sity, an d oth er d isp lay ch aracteristics. b l a n k or b l a n k i n g i n t e rv a l A p eriod in wh ich n o vid eo sign al is received by a m on itor, wh ile th e vid eod isc or d igital vid eo p layer search es for th e n ext vid eo segm en t or fram e to d isp lay. b l o c k A strin g of record s, word s, or ch aracters form ed for tech n ical or logic reason s an d to be treated as an en tity. b l o c k d i a g ra m Th e logical stru ctu re or layou t of a system in grap h ics form . Does n ot n ecessarily m atch th e p h ysical layou t an d d oes n ot sp ecify all th e com p on en ts an d th eir in tercon n ection s.

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BMP

A W in d ows grap h ics form at th at m ay be d evice d ep en d en t or in d ep en d en t. Device-in d ep en d en t BMP files (DIB) are cod ed for tran slation to a wid e variety of d isp lays an d p rin ters.

BNC Bayon et-Neill-Con celm an . Also kn own as British -Naval-Con n ector, Baby-N-Con n ector, or Bayon et-Nu t-Cou p ler; n obod y seem s to be q u ite su re wh at th e actu al n am e is. Th is bayon et-lockin g con n ector is n oted for its excellen t sh ield in g an d im p ed an ce-m atch in g ch aracteristics, resu ltin g in low n oise an d m in im al sign al loss at an y freq u en cy u p to 4GHz. It is u sed in Eth ern et 10Base2 n etworks (also kn own as IEEE 802.3, or Thinnet) to term in ate coaxial cables. It is also u sed for som e h igh en d vid eo m on itors. bon din g

In ISDN, join in g two 64Kbp s B-ch an n els to ach ieve 128Kbp s sp eed .

Bo o l e a n o p e ra t i o n An y op eration in wh ich each of th e op eran d s an d th e resu lt take on e of two valu es. boot

To load a p rogram in to th e com p u ter. Th e term com es from th e p h rase “p u llin g a boot on by th e bootstrap .”

b o o t re c o rd Th e first sector on a d isk or p artition th at con tain s d isk p aram eter in form ation for th e BIOS an d op eratin g system as well as bootstrap load er cod e th at in stru cts th e system h ow to load th e op eratin g system files in to m em ory, th u s begin n in g th e in itial boot seq u en ce to boot th e m ach in e. b o o t se c t o r

See boot record.

b o o t se c t o r v i ru s A viru s d esign ed to occu p y th e boot sector of a d isk. An y attem p t to start or boot a system from th is d isk will tran sfer th e viru s to th e h ard d isk, after wh ich it will su bseq u en tly be load ed every tim e th e system is started . Most PC viru ses are boot sector viru ses. b o o t st ra p A tech n iq u e or d evice d esign ed to brin g itself in to a d esired state by m ean s of its own action . Th e term is u sed to d escribe th e p rocess by wh ich a d evice su ch as a PC goes from its in itial p ower-on con d ition to a ru n n in g con d ition with ou t h u m an in terven tion . See also boot. b o u l e Pu rified , cylin d rical silicon crystals from wh ich sem icon d u ctin g electron ic ch ip s in clu d in g m icrop rocessors, m em ory, an d oth er ch ip s in a PC are m an u factu red . bps

Bits p er secon d . Th e n u m ber of bin ary d igits, or bits, tran sm itted p er secon d . Som etim es con fu sed with baud.

b ra n c h p re d i c t i o n A featu re of fifth -gen eration (Pen tiu m an d h igh er) p rocessors th at attem p ts to p red ict wh eth er a p rogram bran ch will be taken or n ot an d th en fetch es th e ap p rop riate followin g in stru ction s. b ri d g e In local area n etworks, an in tercon n ection between two sim ilar n etworks. Also th e h ard ware eq u ip m en t u sed to establish su ch an in tercon n ection . b ro a d b a n d t ra n sm i ssi o n A term u sed to d escribe an alog tran sm ission . Req u ires m od em s for con n ectin g term in als an d com p u ters to th e n etwork. Usin g freq u en cy d ivision m u ltip lexin g, m an y d ifferen t sign als or sets of d ata can be tran sm itted sim u ltan eou sly. Th e altern ate tran sm ission sch em e is baseban d , or d igital, tran sm ission .

Glossary

b ro w n o u t An AC su p p ly voltage d rop in wh ich th e p ower d oes n ot sh u t off en tirely bu t con tin u es to be su p p lied at lower th an n orm al levels. b u b b l e m e m o ry A sp ecial typ e of n on volatile read / write m em ory in trod u ced by In tel in wh ich m agn etic region s are su sp en d ed in crystal film an d d ata is m ain tain ed wh en th e p ower is off. A typ ical bu bble m em ory ch ip con tain s abou t 512K, or m ore th an 4 m illion bu bbles. Bu bble m em ory failed to catch on becau se of slow access tim es m easu red in several m illisecon d s. It h as, h owever, fou n d a n ich e u se as solid -state “d isk” em u lators in en viron m en ts wh ere con ven tion al d rives are u n accep table, su ch as in m ilitary or factory u se. b u f f e r A block of m em ory u sed as a h old in g tan k to store d ata tem p orarily. Often p osition ed between a slower p erip h eral d evice an d th e faster com p u ter. All d ata m ovin g between th e p erip h eral an d th e com p u ter p asses th rou gh th e bu ffer. A bu ffer en ables th e d ata to be read from or written to th e p erip h eral in larger ch u n ks, wh ich im p roves p erform an ce. A bu ffer th at is x bytes in size u su ally h old s th e last x bytes of d ata th at m oved between th e p erip h eral an d CPU. Th is m eth od con trasts with th at of a cache, wh ich ad d s in telligen ce to th e bu ffer so th at th e m ost often accessed d ata rath er th an th e last accessed d ata rem ain s in th e bu ffer (cach e). A cach e can im p rove p erform an ce greatly over a p lain bu ffer. bug

An error or d efect in a p rogram .

b u rn -i n Th e op eration of a circu it or eq u ip m en t to establish th at its com p on en ts are stable an d to screen ou t d efective p orts or assem blies. b u rst m o d e A m em ory cyclin g tech n ology th at takes ad van tage of th e fact th at m ost m em ory accesses are con secu tive in n atu re. After settin g u p th e row an d colu m n ad d resses for a given access, u sin g bu rst m od e can th en access th e n ext th ree ad jacen t ad d resses with n o ad d ition al laten cy. Bu rst St a t i c RAMs (BSRAMs) Sh ort for Pip elin e Bu rst SRAM, BSRAMs are a com m on typ e of static RAM ch ip u sed for m em ory cach es wh ere access to su bseq u en t m em ory location s after th e first byte is accessed takes fewer m ach in e cycles. bus

A lin ear electrical sign al p ath way over wh ich p ower, d ata, an d oth er sign als travel. It is cap able of con n ectin g to th ree or m ore attach m en ts. A bu s is gen erally con sid ered to be d istin ct from rad ial or p oin t-to-p oin t sign al con n ection s. Th e term com es from th e Latin “om n ibu s” m ean in g “for all.” W h en u sed to d escribe a top ology, bu s always im p lies a lin ear stru ctu re.

b u s m o u se An obsolete typ e of m ou se u sed in th e ’80s th at p lu gs in to a sp ecial m ou se exp an sion board in stead of a serial p ort or m oth erboard m ou se p ort. Th e bu s m ou se con n ector looks like a m oth erboard m ou se (som etim es called PS/ 2 m ou se) con n ector, bu t th e p in con figu ration s are d ifferen t an d n ot com p atible. b u sm a st e r An in telligen t d evice th at wh en attach ed to th e Micro Ch an n el, EISA, VLB, or PCI bu s can bid for an d gain con trol of th e bu s to p erform its sp ecific task with ou t p rocessor in terven tion . byte

A collection of bits th at m akes u p a ch aracter or oth er d esign ation . Gen erally, a byte is 8 d ata bits. W h en referrin g to system RAM, an ad d ition al p arity (errorch eckin g) bit is also stored (see parity), m akin g th e total 9 bits.

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Glossary

C A h igh -level com p u ter p rogram m in g lan gu age. A freq u en tly u sed p rogram m in g lan gu age on m ain fram es, m in is, an d PC com p u ter system s. C++ is a p op u lar varian t. c a c h e An in telligen t bu ffer. By u sin g an in telligen t algorith m , a cach e con tain s th e d ata th at is accessed m ost often between a slower p erip h eral d evice an d th e faster CPU. See also L2 cache, L1 cache, an d disk cache. CAM

Com m on Access Meth od . A com m ittee form ed in 1988 th at con sists of a n u m ber of com p u ter p erip h eral su p p liers an d is d ed icated to d evelop in g stan d ard s for a com m on software in terface between SCSI p erip h erals an d h ost ad ap ters.

c a p a c i t o r A d evice con sistin g of two p lates sep arated by in su latin g m aterial an d d esign ed to store an electrical ch arge. c a rd

A p rin ted circu it board con tain in g electron ic com p on en ts th at form an en tire circu it, u su ally d esign ed to p lu g in to a con n ector or slot. Som etim es also called an adapter.

c a rd e d g e c o n n e c t o r

See edge connector.

Ca rd Bu s A PC Card sp ecification for a 32-bit in terface th at ru n s at 33MHz an d p rovid es 32-bit d ata p ath s to th e com p u ter’s I/ O an d m em ory system s, as well as a n ew sh ield ed con n ector th at p reven ts Card Bu s d evices from bein g in serted in to slots th at d o n ot su p p ort th e latest version of th e PC Card stan d ard . c a rp a l t u n n e l sy n d ro m e A p ain fu l h an d in ju ry th at gets its n am e from th e n arrow tu n n el in th e wrist th at con n ects ligam en t an d bon e. W h en u n d u e p ressu re is p u t on th e ten d on s, th ey can swell an d com p ress th e m ed ian n erve, wh ich carries im p u lses from th e brain to th e h an d , cau sin g n u m bn ess, weakn ess, tin glin g, an d bu rn in g in th e fin gers an d h an d s. Com p u ter u sers get carp al tu n n el syn d rom e p rim arily from im p rop er keyboard ergon om ics th at resu lt in u n d u e strain on th e wrist an d h an d . c a rri e r A con tin u ou s freq u en cy sign al cap able of bein g eith er m od u lated or im p ressed with an oth er in form ation -carryin g sign al. Th e referen ce sign al u sed for th e tran sm ission or recep tion of d ata. Th e m ost com m on u se of th is sign al with com p u ters in volves m od em com m u n ication s over p h on e lin es. Th e carrier is u sed as a sign al on wh ich th e in form ation is su p erim p osed . c a rri e r d e t e c t si g n a l A m od em in terface sign al th at in d icates to th e attach ed d ata term in al eq u ip m en t (DTE) th at it is receivin g a sign al from th e d istan t m od em . Defin ed in th e RS-232 sp ecification . Sam e as th e received lin e-sign al d etector. c a t h o d e ra y t u b e (CRT) A d evice th at con tain s electrod es su rrou n d ed by a glass sp h ere or cylin d er an d d isp lays in form ation by creatin g a beam of electron s th at strike a p h osp h or coatin g in sid e th e d isp lay u n it. Th is d evice is m ost com m on ly u sed in com p u ter m on itors an d term in als. CAV

Con stan t An gu lar Velocity. An op tical d isk record in g form at wh ere th e d ata is record ed on th e d isk in con cen tric circles. CAV d isks are rotated at a con stan t sp eed . Th is is sim ilar to th e record in g tech n iq u e u sed on flop p y d isk d rives. CAV lim its th e total record ed cap acity com p ared to CLV (Con stan t Lin ear Velocity), wh ich is also u sed in op tical record in g.

CCITT An acron ym for th e Com ité Con su ltatif In tern ation al d e Télégrap h iq u e et Télép h on iq u e (in En glish , th e In tern ation al Telegrap h an d Telep h on e Con su ltative

Glossary

Com m ittee or th e Con su ltative Com m ittee for In tern ation al Telegrap h an d Telep h on e). Ren am ed ITU (In tern ation al Telecom m u n ication s Un ion ). See ITU. CCS

Com m on Com m an d Set. A set of SCSI com m an d s sp ecified in th e ANSI SCSI-1 Stan d ard X3.131-1986 Ad d en d u m 4.B. All SCSI d evices m u st be cap able of u sin g th e CCS to be fu lly com p atible with th e ANSI SCSI-1 stan d ard .

CD

Com p act Disc or com p act au d io d isc. A 4.75-in ch (12cm ) op tical d isc th at con tain s in form ation en cod ed d igitally in th e con stan t lin ear velocity (CLV) form at. Th is p op u lar form at for h igh -fid elity m u sic offers 90 d ecibels sign al/ n oise ratio, 74 m in u tes of d igital sou n d , an d n o d egrad ation of q u ality from p layback. Th e stan d ard s for th is form at (d evelop ed by NV Ph ilip s an d Son y Corp oration ) are kn own as th e Red Book. Th e official (an d rarely u sed ) d esign ation for th e au d io-on ly form at is CDDA (com p act d isc-d igital au d io). Th e sim p le au d io form at is also kn own as CD-A (com p act d isc-au d io). A sm aller (3-in ch ) version of th e CD is kn own as CD-3.

CD Vi d e o A CD form at in trod u ced in 1987 th at com bin ed 20 m in u tes of d igital au d io an d 6 m in u tes of an alog vid eo on a stan d ard 4.75-in ch CD. Up on in trod u ction , m an y firm s ren am ed 8-in ch an d 12-in ch vid eod iscs as CDV, in an attem p t to cap italize on th e con su m er p op u larity of th e au d io CD. Th e term fell ou t of u se in 1990 an d was rep laced in som e p art by laserdisc an d m ore recen tly, DV D. CD +G Com p act Disc-Grap h ics. A CD form at th at in clu d es exten d ed grap h ics cap abilities as written in to th e origin al CD-ROM sp ecification s. In clu d es lim ited vid eo grap h ics en cod ed in to th e CD su bcod e area. Develop ed an d m arketed by W arn er New Med ia. CD +MID I Com p act Disc-Mu sical In stru m en t Digital In terface. A CD form at th at ad d s to th e CD+G form at d igital au d io, grap h ics in form ation , an d m u sical in stru m en t d igital in terface (MIDI) sp ecification s an d cap abilities. Develop ed an d m arketed by W arn er New Med ia. CD -D A Com p act Disc Digital Au d io. Also kn own as Red Book Audio an d is th e d igital sou n d form at u sed by au d io CDs. CD-DA u ses a sam p lin g rate of 44.1KHz an d stores 16 bits of in form ation for each sam p le. CD au d io is n ot p layed th rou gh th e com p u ter, bu t th rou gh a sp ecial ch ip in th e CD-ROM d rive. Fifteen m in u tes of CDDA sou n d can req u ire abou t 80M. Th e h igh est q u ality sou n d th at can be u sed by m u ltim ed ia PC is th e CD-DA form at at 44.1KHz sam p le rate. See CD. CD -I

Com p act Disc-In teractive. A com p act d isc form at released in October 1991 th at p rovid es au d io, d igital d ata, still grap h ics, an d m otion vid eo. Th e stan d ard s for th is form at (d evelop ed by NV Ph ilip s an d Son y Corp oration ) are kn own as th e Green Book. CD-I d id n ot catch on with con su m ers an d is n ow con sid ered obsolete.

CD -R

Com p act Disc-Record able, som etim es also called CD-W ritable. CD-R d isks are com p act d iscs th at can be record ed an d read as m an y tim es as d esired . CD-R is p art of th e Oran ge Book Stan d ard d efin ed by ISO. CD-R tech n ology is u sed for m ass p rod u ction of m u ltim ed ia ap p lication s. CD-R d iscs can be com p atible with CDROM, CD-ROM XA, an d CD au d io. Oran ge Book sp ecifies m u lti-session cap abilities, wh ich allow d ata record in g on th e d isc at d ifferen t tim es in several record in g session s. Kod ak’s Ph oto CD is an exam p le of CD-R tech n ology an d fits u p to 100 d igital p h otograp h s on a sin gle CD. Mu lti-session cap ability allows several rolls of 35m m film to be ad d ed to a sin gle d isc on d ifferen t occasion s.

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Glossary

CD -ROM Com p act Disc-Read On ly Mem ory. A 4.75-in ch laser-en cod ed op tical m em ory storage m ed iu m with th e sam e con stan t lin ear velocity (CLV) sp iral form at as au d io CDs an d som e vid eod iscs, CD-ROMs can h old abou t 650M of d ata. CD-ROMs req u ire m ore error-correction in form ation th an th e stan d ard p rerecord ed com p act au d io d isc. Th e stan d ard s for th is form at (d evelop ed by NV Ph ilip s an d Son y Corp oration ) are kn own as th e Yellow Book. See also CD-ROM X A. CD -ROM d ri v e A d evice th at retrieves d ata from a CD-ROM d isc; d iffers from a stan d ard au d io CD p layer by th e in corp oration of ad d ition al error-correction circu itry. CD-ROM d rives u su ally can also p lay m u sic from au d io CDs. CD -ROM XA Com p act Disc-Read On ly Mem ory eXten d ed Arch itectu re. Th e XA stan d ard was d evelop ed join tly by Son y, Ph ilip s, an d Microsoft in 1988 an d is n ow p art of th e Yellow Book stan d ard . XA is a bu ilt-in featu re of n ewer CD-ROM d rives, an d su p p orts sim u ltan eou s sou n d p layback with d ata tran sfer. Non -XA d rives su p p ort eith er sou n d p layback or d ata tran sfer, bu t n ot both sim u ltan eou sly. XA also p rovid es for d ata com p ression righ t on th e d isk, wh ich can also in crease d ata tran sfer rates. CD -RW Com p act Disc-ReW ritable A typ e of rewritable CD-ROM tech n ology d efin ed in Part III of th e Oran ge Book Stan d ard th at u ses a d ifferen t typ e of d isc th at th e d rive can rewrite at least on e th ou san d tim es. CD-RW d rives can also be u sed to write CD-R d iscs, an d th ey can read CD-ROMs. CD-RW d iscs h ave a lower reflectivity th an stan d ard CD-ROMs, an d CD-ROM d rives m u st be of th e n ewer m u ltiread variety to read th em . CD-RW was in itially kn own as CD-E (for CD-Erasable). CD -W O Com p act Disc-W rite On ce. A varian t on CD-ROM th at can be written to on ce an d read m an y tim es; d evelop ed by NV Ph ilip s an d Son y Corp oration . Also kn own as CD-W ORM (CD-write on ce/ read m an y), CD-Record able, or CD-W ritable. Stan d ard s for th is form at are kn own as th e Orange Book. CD -W ORM

See CD-W O.

Ce n t ro n i c s c o n n e c t o r Refers to on e of two typ es of cable con n ectors u sed with eith er p arallel or SCSI d evices. c e ra m i c su b st ra t e A th in , flat, fired ceram ic p art u sed to h old an IC ch ip (u su ally m ad e of berylliu m oxid e or alu m in u m oxid e). CERN Con seil Eu rop éen p ou r la Rech erch e Nu cléaire (Th e Eu rop ean Laboratory for Particle Ph ysics). Th e site in Gen eva wh ere th e W orld W id e W eb was created in 1989. CGA

Color Grap h ics Ad ap ter. A typ e of PC vid eo d isp lay ad ap ter in trod u ced by IBM on Au gu st 12, 1981, th at su p p orts text an d grap h ics. Text is su p p orted at a m axim u m resolu tion of 80×25 ch aracters in 16 colors with a ch aracter box of 8×8 p ixels. Grap h ics is su p p orted at a m axim u m resolu tion of 320×200 p ixels in 16 colors or 640×200 p ixels in two colors. Th e CGA ou tp u ts a TTL (d igital) sign al with a h orizon tal scan n in g freq u en cy of 15.75KHz, an d su p p orts TTL color or NTSC com p osite d isp lays.

c h a n n e l 1) An y p ath alon g wh ich sign als can be sen t. 2) In ISDN, d ata ban d wid th is d ivid ed in to two B-ch an n els th at bear d ata an d on e D-ch an n el th at carries in form ation abou t th e call.

Glossary

c h a ra c t e r bol.

A rep resen tation , cod ed in bin ary d igits, of a letter, n u m ber, or oth er sym -

c h a ra c t e r se t All th e letters, n u m bers, an d ch aracters th at a com p u ter can u se to rep resen t d ata. Th e ASCII stan d ard h as 256 ch aracters, each rep resen ted by a bin ary n u m ber from 1 to 256. Th e ASCII set in clu d es all th e letters in th e alp h abet, n u m bers, m ost p u n ctu ation m arks, som e m ath em atical sym bols, an d oth er ch aracters. c h a rg e c o u p l e d d e v i c e A ligh t sen sin g an d storage d evice u sed in scan n ers an d d igital cam eras to cap tu re th e p ixels. ch eck bit

See parity.

c h e c k su m Sh ort for sum m ation check, a tech n iq u e for d eterm in in g wh eth er a p ackage of d ata is valid . Th e p ackage, a strin g of bin ary d igits, is ad d ed u p an d com p ared with th e exp ected n u m ber. ch ip

An oth er n am e for an IC, or integrated circuit. Hou sed in a p lastic or ceram ic carrier d evice with p in s for m akin g electrical con n ection s.

c h i p c a rri e r

A ceram ic or p lastic p ackage th at carries an in tegrated circu it.

c h i p se t A sin gle ch ip or p air of ch ip s th at in tegrates in to it th e Clock Gen erator, Bu s Con troller, System Tim er, In terru p t Con troller, DMA Con troller, CMOS RAM/ Clock, an d Keyboard Con troller. See also North Bridge an d South Bridge. CH S

Cylin d er Head Sector. Th e term u sed to d escribe th e n on tran slatin g sch em e u sed by th e BIOS to access IDE d rives th at are less th an or eq u al to 528M in cap acity. See LBA.

CIF Com m on Im age Form at. Th e stan d ard sam p le stru ctu re th at rep resen ts th e p ictu re in form ation of a sin gle fram e in d igital HDTV, in d ep en d en t of fram e rate an d syn c/ blan k stru ctu re. Th e u n com p ressed bit rate for tran sm ittin g CIF at 29.97 fram es/ sec is 36.45Mbp s. c i rc u i t

A com p lete electron ic p ath .

c i rc u i t b o a rd Th e collection of circu its gath ered on a sh eet of p lastic, u su ally with all con tacts m ad e th rou gh a strip of p in s. Th e circu it board u su ally is m ad e by ch em ically etch in g m etal-coated p lastic. CISC Com p lex In stru ction Set Com p u ter. Refers to trad ition al com p u ters th at op erate with large sets of p rocessor in stru ction s. Most m od ern com p u ters, in clu d in g th e In tel 80xxx p rocessors, are in th is category. CISC p rocessors h ave exp an d ed in stru ction sets th at are com p lex in n atu re an d req u ire several to m an y execu tion cycles to com p lete. Th is stru ctu re con trasts with RISC (reduced instruction set com puter) processors, wh ich h ave far fewer in stru ction s th at execu te q u ickly. c l e a n ro o m 1) A d u st-free room in wh ich certain electron ic com p on en ts (su ch as ch ip s or h ard d isk d rives) m u st be m an u factu red an d serviced to p reven t con tam in ation . Room s are rated by Class n u m bers. A Class 100 clean room m u st h ave fewer th an 100 p articles larger th an 0.5 m icron s p er cu bic foot of sp ace. 2) A legal ap p roach to cop yin g software or h ard ware wh ere on e team an alyzes th e p rod u ct an d writes a d etailed d escrip tion , followed by a secon d team wh o read s th e d escrip tion written by th e first an d wh o th en d evelop s a com p atible version of th e p rod u ct. W h en d on e correctly, su ch a d esign m eth od ology will su rvive a legal attack.

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Glossary

c l i e n t / se rv e r A typ e of n etwork in wh ich every com p u ter is eith er a server with a d efin ed role of sh arin g resou rces with clien ts or a clien t th at can access th e resou rces on th e server. c l o c k Th e sou rce of a com p u ter’s tim in g sign als. Syn ch ron izes every op eration of th e CPU. c l o c k m u l t i p l i e r A p rocessor featu re wh ere th e in tern al core ru n s at a h igh er sp eed th an th e m oth erboard or p rocessor bu s. See also overclocking. c l o c k sp e e d A m easu rem en t of th e rate at wh ich th e clock sign al for a d evice oscillates, u su ally exp ressed in m illion s of cycles p er secon d (MHz). c l o n e Origin ally referred to an IBM-com p atible com p u ter system th at p h ysically as well as electrically em u lates th e d esign of on e of IBM’s p erson al com p u ter system s. More cu rren tly, it refers to an y PC system ru n n in g an In tel or com p atible p rocessor in th e 80x86 fam ily. c l u st e r Also called allocation unit. A grou p of on e or m ore sectors on a d isk th at form s a fu n d am en tal u n it of storage to th e op eratin g system . Clu ster or allocation u n it size is d eterm in ed by th e op eratin g system wh en th e d isk is form atted . Larger clu sters gen erally offer faster system p erform an ce bu t waste d isk sp ace. CLV

Con stan t Lin ear Velocity. An op tical record in g form at wh ere th e sp acin g of d ata is con sisten t th rou gh ou t th e d isk, an d th e rotation al sp eed of th e d isk varies d ep en d in g on wh at track is bein g read . Ad d ition ally, m ore sectors of d ata are p laced on th e ou ter tracks com p ared to th e in n er tracks of th e d isk, wh ich is sim ilar to Zon e Record in g on h ard d rives. CLV d rives will ad ju st th e rotation al sp eed to m ain tain a con stan t track velocity as th e d iam eter of th e track ch an ges. CLV d rives rotate faster n ear th e cen ter of th e d isk an d slower toward th e ed ge. Rotation al ad ju stm en t m axim izes th e am ou n t of d ata th at can be stored on a d isk. CD au d io an d CD-ROM u se CLV record in g.

CMOS Com p lem en tary Metal-Oxid e Sem icon d u ctor. A typ e of ch ip d esign th at req u ires little p ower to op erate. In PCs, a battery-p owered CMOS m em ory an d clock ch ip is u sed to store an d m ain tain th e clock settin g an d system con figu ration in form ation . CMYK Cyan Magen ta Yellow Black. Th e stan d ard fou r-color m od el u sed for p rin tin g. c o a t e d m e d i a Hard d isk p latters coated with a red d ish iron -oxid e m ed iu m on wh ich d ata is record ed . c o a x i a l c a b l e Also called coax cable. A d ata-tran sm ission m ed iu m n oted for its wid e ban d wid th , im m u n ity to in terferen ce, an d h igh cost com p ared to oth er typ es of cable. Sign als are tran sm itted in sid e a fu lly sh ield ed en viron m en t, in wh ich an in n er con d u ctor is su rrou n d ed by a solid in su latin g m aterial an d th en an ou ter con d u ctor or sh ield . Used in m an y local area n etwork system s su ch as Ethernet an d ARCnet. COBOL Com m on Bu sin ess-Orien ted Lan gu age. A h igh -level com p u ter p rogram m in g lan gu age p rim arily u sed by som e larger com p an ies. It h as n ever ach ieved p op u larity on p erson al an d sm all bu sin ess com p u ters. c o d e p a g e A table u sed in DOS 3.3 an d later th at sets u p th e keyboard an d d isp lay ch aracters for variou s foreign lan gu ages.

Glossary

c o d e p a g e sw i t c h i n g A DOS featu re in version s 3.3 an d later th at ch an ges th e ch aracters d isp layed on screen or p rin ted on an ou tp u t d evice. Prim arily u sed to su p p ort foreign -lan gu age ch aracters. Req u ires an EGA or better vid eo system an d an IBMcom p atible grap h ics p rin ter. COD EC CODer-DECod er. A d evice th at con verts voice sign als from th eir an alog form to d igital sign als accep table to m ore m od ern d igital PBXs an d d igital tran sm ission system s. It th en con verts th ose d igital sign als back to an alog so th at you m ay h ear an d u n d erstan d wh at th e oth er p arty is sayin g. c o e rc i v i t y A m easu rem en t in u n its of oersted s of th e am ou n t of m agn etic en ergy to switch or “coerce” th e flu x ch an ge in th e m agn etic record in g m ed ia. High coercivity d isk m ed ia req u ires a stron ger write cu rren t. c o l d b o o t Startin g or restartin g a com p u ter by resettin g or tu rn in g on th e p ower su p p ly. See also warm boot. c o l l i si o n In a LAN, if two com p u ters tran sm it a p acket of d ata at th e sam e tim e on th e n etwork, th e d ata m ay becom e garbled , wh ich is kn own as a collision . c o l l i si o n d e t e c t i o n / a v o i d a n c e A p rocess u sed on a LAN to p reven t d ata p ackets from in terferin g with each oth er an d to d eterm in e wh eth er d ata p ackets h ave en cou n tered a collision an d in itiate a resen d of th e affected p ackets. Co l o r Gra p h i c s Ad a p t e r co lo r p alet t e COM p o rt

See CGA.

Th e colors available to a grap h ics ad ap ter for d isp lay.

A serial p ort on a PC th at con form s to th e RS-232 stan d ard . See also RS-232.

COMD EX Th e largest in tern ation al com p u ter trad e sh ow an d con feren ce in th e world . COMDEX/ Fall is h eld in Las Vegas d u rin g October, an d COMDEX/ Sp rin g u su ally is h eld in Ch icago or Atlan ta d u rin g Ap ril. co m m an d tion .

An in stru ction th at tells th e com p u ter to start, stop , or con tin u e an op era-

c o m m a n d i n t e rp re t e r Th e op eratin g system p rogram th at con trols a com p u ter’s sh ell or u ser in terface. Th e com m an d in terp reter for MS-DOS is COMMAND.COM. Th e com m an d in terp reter for W in d ows is W IN.COM. COMMAND .COM An op eratin g system file th at is load ed last wh en th e com p u ter is booted . Th e com m an d in terp reter or u ser in terface an d p rogram -load er p ortion of DOS. c o m m o n Th e grou n d or retu rn p ath for an electrical sign al. If a wire, it u su ally is colored black. c o m m o n m o d e n o i se Noise or electrical d istu rban ces th at can be m easu red between a cu rren t- or sign al-carryin g lin e an d its associated grou n d . Com m on m od e n oise is freq u en tly in trod u ced to sign als between sep arate com p u ter eq u ip m en t com p on en ts th rou gh th e p ower d istribu tion circu its. It can be a p roblem wh en sin gleen d ed sign als are u sed to con n ect d ifferen t eq u ip m en t or com p on en ts th at are p owered by d ifferen t circu its. c o m p a t i b l e 1) In th e early d ays of th e PC in d u stry wh en IBM d om in ated th e m arket, a term u sed to refer to com p u ters from oth er m an u factu rers th at h ad th e sam e

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Glossary

featu res as a given IBM m od el. 2) In gen eral, software or h ard ware th at con form s to in d u stry stan d ard s or oth er d e facto stan d ard s so th at it can be u sed in con ju ction with or in lieu of oth er version s of software or h ard ware from oth er ven d ors in a like m an n er. c o m p i l e r A p rogram th at tran slates a p rogram written in a h igh -level lan gu age in to its eq u ivalen t m ach in e lan gu age. Th e ou tp u t from a com p iler is called an object program . co m p let e back u p tree stru ctu re.

A backu p of all in form ation on a h ard d isk, in clu d in g th e d irectory

c o m p o si t e v i d e o Television p ictu re in form ation an d syn c p u lses com bin ed . Th e com p lete wave form of th e color vid eo sign al com p osed of ch rom in an ce an d lu m in an ce p ictu re in form ation ; blan kin g p ed estal; field , lin e, an d color syn c p u lses; an d field eq u alizin g p u lses. Som e vid eo card s h ave an RCA jack th at ou tp u ts a com p osite vid eo sign al. See also RGB. c o m p re sse d f i l e tech n iq u es.

A file th at h as been red u ced in size via on e or m ore com p ression

c o m p u t e r Device cap able of accep tin g d ata, ap p lyin g p rescribed p rocesses to th is d ata, an d d isp layin g th e resu lts or in form ation p rod u ced . c o m p u t e r-b a se d t ra i n i n g CBT. Th e u se of a com p u ter to d eliver in stru ction or train in g; also kn own as Com p u ter-Aid ed (or Assisted ) In stru ction (CAI), Com p u terAid ed Learn in g (CAL), Com p u ter-Based In stru ction (CBI), an d Com p u ter-Based Learn in g (CBL). CONFIG.SYS A file th at can be created to tell DOS h ow to con figu re itself wh en th e m ach in e starts u p . Can load d evice d rivers, set th e n u m ber of DOS bu ffers, an d so on . c o n f i g u ra t i o n f i l e A file kep t by ap p lication software to record variou s asp ects of th e software’s con figu ration , su ch as th e p rin ter it u ses. c o n so l e Th e u n it, su ch as a term in al or a keyboard , in you r system with wh ich you com m u n icate with th e com p u ter. co n t ig u o u s

Tou ch in g or join ed at th e ed ge or bou n d ary, in on e p iece.

c o n t i n u i t y In electron ics, an u n broken p ath way. Testin g for con tin u ity n orm ally m ean s testin g to d eterm in e wh eth er a wire or oth er con d u ctor is com p lete an d u n broken (by m easu rin g 0 oh m s). A broken wire sh ows in fin ite resistan ce (or in fin ite oh m s). c o n t ro l c a b l e Th e wid er of th e two cables th at con n ect an ST-506/ 412 or ESDI h ard d isk d rive to a con troller card . A 34-p in cable th at carries com m an d s an d ackn owled gm en ts between th e d rive an d con troller. c o n t ro l l e r Th e electron ics th at con trol a d evice su ch as a h ard d isk d rive an d in term ed iate th e p assage of d ata between th e d evice an d th e com p u ter. c o n t ro l l e r c a rd An ad ap ter h old in g th e con trol electron ics for on e or m ore d evices su ch as h ard d isks. Ord in arily occu p ies on e of th e com p u ter’s slots.

Glossary

c o n v e n t i o n a l m e m o ry Th e first m egabyte or first 640K of system m em ory accessible by an In tel p rocessor in real m od e. Som etim es called base m em ory. c o n v e rg e n c e Describes th e cap ability of a color m on itor to focu s th e th ree colored electron beam s on a sin gle p oin t. Poor con vergen ce cau ses th e ch aracters on screen to ap p ear fu zzy an d can cau se h ead ach es an d eyestrain . c o p ro c e sso r An ad d ition al com p u ter p rocessin g u n it d esign ed to h an d le sp ecific tasks in con ju n ction with th e m ain or cen tral p rocessin g u n it. c o p y p ro t e c t i o n p rogram . c o re

A h ard ware or software sch em e to p roh ibit m akin g illegal cop ies of a

An “old -fash ion ed ” term for com p u ter m em ory.

c o re sp e e d Th e in tern al sp eed of a p rocessor. W ith all m od ern p rocessors, th is sp eed is faster th an th e system bu s sp eed an d th at sp eed relation sh ip is regu lated by th e clock m u ltip lier in th e p rocessor. CP / M Con trol Program for Microcom p u ters, origin ally Con trol Program / Mon itor. An op eratin g system created by Gary Kild all, th e fou n d er of Digital Research . Created for th e old 8-bit m icrocom p u ters th at u sed th e 8080, 8085, an d Z-80 m icrop rocessors. W as th e d om in an t op eratin g system in th e late 1970s an d early 1980s for sm all com p u ters u sed in a bu sin ess en viron m en t. cp s

Ch aracters p er secon d . A d ata tran sfer rate gen erally estim ated from th e bit rate an d th e ch aracter len gth . At 2,400bp s, for exam p le, 8-bit ch aracters with start an d stop bits (for a total of 10 bits p er ch aracter) are tran sm itted at a rate of ap p roxim ately 240cp s. Som e p rotocols, su ch as V.42 an d MNP, em p loy ad van ced tech n iq u es su ch as lon ger tran sm ission fram es an d d ata com p ression to in crease ch aracters p er secon d .

CP U

Cen tral Processin g Un it. Th e com p u ter’s m icrop rocessor ch ip ; th e brain s of th e ou tfit. Typ ically, an IC u sin g VLSI (very-large-scale in tegration ) tech n ology to p ack several d ifferen t fu n ction s in to a tin y area. Th e m ost com m on electron ic d evice in th e CPU is th e tran sistor, of wh ich several th ou san d to several m illion or m ore are fou n d .

c ra sh A m alfu n ction th at brin gs work to a h alt. A system crash u su ally is cau sed by a software m alfu n ction , an d ord in arily you can restart th e system by rebootin g th e m ach in e. A head crash, h owever, en tails p h ysical d am age to a d isk an d p robable d ata loss. CRC Cyclic Red u n d an cy Ch eckin g. An error-d etection tech n iq u e con sistin g of a cyclic algorith m p erform ed on each block or fram e of d ata by both sen d in g an d receivin g m od em s. Th e sen d in g m od em in serts th e resu lts of its com p u tation in each d ata block in th e form of a CRC cod e. Th e receivin g m od em com p ares its resu lts with th e received CRC cod e an d resp on d s with eith er a p ositive or n egative ackn owled gm en t. In th e ARQ p rotocol im p lem en ted in h igh -sp eed m od em s, th e receivin g m od em accep ts n o m ore d ata u n til a d efective block is received correctly. c ro sst a l k Th e electrom agn etic cou p lin g of a sign al on on e lin e with an oth er n earby sign al lin e. Crosstalk is cau sed by electrom agn etic in d u ction , wh ere a sign al travelin g th rou gh a wire creates a m agn etic field th at in d u ces a cu rren t in oth er n earby wires.

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Glossary

CRT

Cath od e-Ray Tu be. A term u sed to d escribe a television or m on itor screen tu be.

c u rre n t

Th e flow of electron s, m easu red in am p eres, or am p s.

c u rso r Th e sm all flash in g h yp h en th at ap p ears on screen to in d icate th e p oin t at wh ich an y in p u t from th e keyboard will be p laced . cycle

Tim e for a sign al to tran sition from lead in g ed ge to th e n ext lead in g ed ge.

c y c l i c re d u n d a n c y c h e c k i n g

See CRC.

c y l i n d e r Th e set of tracks on a d isk th at are on each sid e of all th e d isk p latters in a stack an d are th e sam e d istan ce from th e cen ter of th e d isk. Th e total n u m ber of tracks th at can be read with ou t m ovin g th e h ead s. A flop p y d rive with two h ead s u su ally h as 160 tracks, wh ich are accessible as 80 cylin d ers. A typ ical 4G h ard d isk h as 10 p latters with 20 h ead s (19 for d ata an d on e servo h ead ) an d 4,000 cylin d ers, in wh ich each cylin d er is com p osed of 19 tracks. D / A Co n v e rt e r

DAC. A d evice th at con verts d igital sign als to an alog form .

d a i sy c h a i n Strin gin g u p com p on en ts in su ch a m an n er th at th e sign als m ove serially from on e to th e oth er. Most m icrocom p u ter m u ltip le d isk d rive system s are d aisych ain ed . Th e SCSI bu s system is a d aisy-ch ain arran gem en t, in wh ich th e sign als m ove from com p u ter to d isk d rives to tap e u n its, an d so on . d a i sy w h e e l p ri n t e r An im p act p rin ter th at p rin ts fu lly form ed ch aracters on e at a tim e by rotatin g a circu lar p rin t elem en t com p osed of a series of in d ivid u al sp okes, each con tain in g two ch aracters th at rad iate from a cen ter h u b. Prod u ces letterq u ality ou tp u t. D AT

Digital Au d io Tap e. A sm all cassette con tain in g 4m m -wid e tap e u sed for storin g large am ou n ts of d igital in form ation . DAT tech n ology em erged in Eu rop e an d Jap an in 1986 as a way to p rod u ce h igh -q u ality, d igital au d io record in gs an d was m od ified in 1988 to con form to th e DDS (Digital Data Storage) stan d ard for storin g com p u ter d ata. Raw cap acities for a sin gle tap e are 2G for DDS, 4G for DDS-2, an d 12G for DDS-3, with d ou ble th at for com p ressed d ata.

data

1) Grou p s of facts p rocessed in to in form ation . A grap h ic or textu ral rep resen tation of facts, con cep ts, n u m bers, letters, sym bols, or in stru ction s u sed for com m u n ication or p rocessin g. 2) An an d roid from th e 24th cen tu ry with a p rocessin g sp eed of 60 trillion op eration s p er secon d an d a storage cap acity of 800 q u ad rillion bits, an d wh o serves on th e USS Enterprise NCC-1701-D with th e ran k of lieu ten an t com m an d er.

d a t a b u s Th e con n ection th at tran sm its d ata between th e p rocessor an d th e rest of th e system . Th e wid th of th e d ata bu s d efin es th e n u m ber of d ata bits th at can be m oved in to or ou t of th e p rocessor in on e cycle. d a t a c a b l e Gen erically, a cable th at carries d ata. Sp ecific to HD con n ection s, th e n arrower (20 p in ) of two cables th at con n ects an ST-506/ 412 or ESDI h ard d isk d rive to a con troller card . d a t a c o m m u n i c a t i o n s A typ e of com m u n ication in wh ich com p u ters an d term in als can exch an ge d ata over an electron ic m ed iu m .

Glossary

d a t a c o m p re ssi o n A tech n iq u e wh ere m ath em atical algorith m s are ap p lied to th e d ata in a file to elim in ate red u n d an cies an d th erefore red u ce th e size of th e file. See lossy com pression an d lossless com pression. d a t a l i n k l a y e r In n etworkin g, th e layer of th e OSI referen ce m od el th at con trols h ow th e electrical im p u lses en ter or leave th e n etwork cable. Eth ern et an d Token Rin g are th e two m ost com m on exam p les of d ata lin k layer p rotocols. d a t a se p a ra t o r A d evice th at sep arates d ata an d clock sign als from a sin gle en cod ed sign al p attern . Usu ally, th e sam e d evice d oes both d ata sep aration an d com bin ation an d is som etim es called an endec, or encoder/decoder. d a t a t ra n sf e r ra t e Th e m axim u m rate at wh ich d ata can be tran sferred from on e d evice to an oth er. d a u g h t e rb o a rd Ad d -on board to in crease fu n ction ality an d / or m em ory. Attach es to existin g board . D -c h a n n e l In ISDN, a 16Kbp s ch an n el th at is u sed to tran sm it con trol d ata abou t a con n ection . D B-9

9-p in D-sh ell con n ector, p rim arily u sed for PC serial p orts.

D B-2 5

25-p in D-sh ell con n ector, p rim arily u sed for PC p arallel p orts.

D C Direct cu rren t, su ch as th at p rovid ed by a p ower su p p ly or batteries. D C-6 0 0 Data Cartrid ge 600, a d ata-storage m ed iu m in ven ted by 3M in 1971 th at u ses a q u arter-in ch -wid e tap e 600 feet in len gth . D CE

Data Com m u n ication s Eq u ip m en t. Th e h ard ware th at p erform s th e com m u n ication —u su ally a d ial-u p m od em th at establish es an d con trols th e d ata lin k th rou gh th e telep h on e n etwork. See also DTE.

DDE

Dyn am ic Data Exch an ge. A form of in terp rocess com m u n ication s u sed by Microsoft W in d ows to su p p ort th e exch an ge of com m an d s an d d ata between two ap p lication s ru n n in g sim u ltan eou sly. Th is cap ability h as been en h an ced fu rth er with Object Lin kin g an d Em bed d in g (OLE).

d e f a c t o st a n d a rd A software or h ard ware tech n ology th at is n ot officially m ad e a stan d ard by an y recogn ized stan d ard s organ ization bu t th at is u sed as a referen ce for con su m ers an d ven d ors d u e to its d om in an ce in th e m arketp lace. D EBUG Th e n am e of a u tility p rogram in clu d ed with DOS u sed for sp ecialized p u rp oses su ch as alterin g m em ory location s, tracin g p rogram execu tion , p atch in g p rogram s an d d isk sectors, an d p erform in g oth er low-level tasks. d e c i b e l (d B) A logarith m ic m easu re of th e ratio between two p owers, voltages, cu rren ts, sou n d in ten sities, an d so on . Sign al-to-n oise ratios are exp ressed in d ecibels. d e d i c a t e d l i n e A u ser-in stalled telep h on e lin e th at con n ects a sp ecified n u m ber of com p u ters or term in als with in a lim ited area, su ch as a sin gle bu ild in g. Th e lin e is a cable rath er th an a p u blic-access telep h on e lin e. Th e com m u n ication s ch an n el also m ay be referred to as n on switch ed becau se calls d o n ot go th rou gh telep h on e com p an y switch in g eq u ip m en t.

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d e d i c a t e d se rv o su rf a c e In voice-coil-actu ated h ard d isk d rives, on e sid e of on e p latter given over to servo d ata th at is u sed to gu id e an d p osition th e read / write h ead s. d e f a u l t An y settin g assu m ed at startu p or reset by th e com p u ter’s software an d attach ed d evices an d op eration al u n til ch an ged by th e u ser. An assu m p tion th e com p u ter m akes wh en n o oth er p aram eters are sp ecified . W h en you typ e DIR with ou t sp ecifyin g th e d rive to search , for exam p le, th e com p u ter assu m es th at you wan t it to search th e d efau lt d rive. Th e term is u sed in software to d escribe an y action th e com p u ter or p rogram takes on its own with em bed d ed valu es. d e f e c t m a p A list of u n u sable sectors an d tracks cod ed on to a d rive d u rin g th e lowlevel form at p rocess. d e f ra g m e n t a t i o n Th e p rocess of rearran gin g d isk sectors so files are stored on con secu tive sectors in ad jacen t tracks. d e g a u ss 1) To rem ove m agn etic ch arges, or to erase m agn etic im ages. Norm al ap p lication s in clu d e m on itors an d d isks or tap es. Most m on itors in corp orate a d egau ssin g coil, wh ich su rrou n d s th e CRT, an d au tom atically en ergize th is coil for a few secon d s wh en p owered u p to rem ove color or im age d istortin g m agn etic field s from th e m etal m ask in sid e th e tu be. Som e m on itors in clu d e a bu tton or con trol th at can be u sed for ad d ition al ap p lication s of th is coil to rem ove m ore stu bborn m agn etic traces. 2) Also th e act of erasin g or d em agn etizin g a m agn etic d isk or tap e u sin g a sp ecial tool called a d egau ssin g coil. d e n si t y Th e am ou n t of d ata th at can be p acked in to a certain area on a sp ecific storage m ed ia. d e sk t o p

A p erson al com p u ter th at sits on a d esk.

d e v i c e d ri v e r A m em ory-resid en t p rogram load ed by CONFIG.SYS th at con trols an u n u su al d evice, su ch as an exp an d ed m em ory board . D h ry st o n e A ben ch m ark p rogram u sed as a stan d ard figu re of m erit in d icatin g asp ects of a com p u ter system ’s p erform an ce in areas oth er th an floatin g-p oin t m ath p erform an ce. Becau se th e p rogram d oes n ot u se an y floatin g-p oin t op eration s, p erform s n o I/ O, an d m akes n o op eratin g system calls, it is m ost u sefu l for m easu rin g th e p rocessor p erform an ce of a system . Th e origin al Dh ryston e p rogram was d evelop ed in 1984 an d was written in Ad a, alth ou gh th e C an d Pascal version s becam e m ore p op u lar by 1989. d i a g n o st i c s Program s u sed to ch eck th e op eration of a com p u ter system . Th ese p rogram s en able th e op erator to ch eck th e en tire system for an y p roblem s an d to in d icate in wh at area th e p roblem s lie. d i a l -u p a d a p t e r In W in d ows 9x, a software p rogram th at u ses a m od em to em u late a n etwork in terface card for n etworkin g. Most com m on ly u sed to con n ect to an In tern et service p rovid er or a d ial-u p server for rem ote access to a LAN. die

An in d ivid u al ch ip (p rocessor, RAM, or oth er in tegrated circu it) cu t from a fin ish ed silicon ch ip wafer an d bu ilt in to th e p h ysical p ackage th at will con n ect it to th e rest of th e PC or a circu it board .

Glossary

d i f f e re n t i a l An electrical sign alin g m eth od wh ere a p air of lin es are u sed for each sign al in “p u sh -p u ll” fash ion . In m ost cases, d ifferen tial sign als are balan ced so th at th e sam e cu rren t flows on each lin e in op p osite d irection s. Th is is u n like sin gleen d ed sign als, wh ich u se on ly on e lin e p er sign al referen ced to a sin gle grou n d . Differen tial sign als h ave a large toleran ce for com m on -m od e n oise an d little crosstalk wh en u sed with twisted -p air wires even in lon g cables. Differen tial sign alin g is exp en sive becau se two p in s are req u ired for each sign al. d i g i t a l l o o p b a c k A test th at ch ecks th e m od em ’s RS-232 in terface an d th e cable th at con n ects th e term in al or com p u ter an d th e m od em . Th e m od em receives d ata (in th e form of d igital sign als) from th e com p u ter or term in al an d im m ed iately retu rn s th e d ata to th e screen for verification . d i g i t a l si g n a l s Discrete, u n iform sign als. In th is book, th e term refers to th e bin ary d igits 0 an d 1. d i g i t i z e To tran sform an an alog wave to a d igital sign al th at a com p u ter can store. Con version to d igital d ata an d back is p erform ed by a Digital to Analog Converter (DAC), often a sin gle-ch ip d evice. How closely a d igitized sam p le rep resen ts an an alog wave d ep en d s on th e n u m ber of tim es th e am p litu d e of a wave is m easu red an d record ed (th e rate of d igitization ) as well as th e n u m ber of d ifferen t levels th at can be sp ecified at each in stan ce. Th e n u m ber of p ossible sign al levels is d ictated by th e resolu tion in bits. D IMM Du al In lin e Mem ory Mod u le. A 64-bit wid e, 168-p in m em ory m od u le u sed in Pen tiu m an d n ewer PCs. Th ey are available in several version s, in clu d in g 5v or 3v, bu ffered or u n bu ffered , with FPM/ EDO or SDRAM m em ory, an d in 64-bit (n on ECC/ p arity) or 72-bit (ECC/ p arity) form . Most Pen tiu m an d n ewer PCs req u ire 3.3v u n bu ffered SDRAM DIMMs in eith er n on -ECC or ECC version s (ECC recom m en d ed ). D IP

Du al In lin e Package. A fam ily of rectan gu lar, in tegrated -circu it flat p ackages th at h ave lead s on th e two lon ger sid es. Package m aterial is p lastic or ceram ic.

D IP sw i t c h A tin y switch (or grou p of switch es) on a circu it board . Nam ed for th e form factor of th e carrier d evice in wh ich th e switch is h ou sed . d i re c t m e m o ry a c c e ss (D MA) A p rocess by wh ich d ata m oves between a d isk d rive (or oth er d evice) an d system m em ory with ou t d irect con trol of th e cen tral p rocessin g u n it, th u s freein g it u p for oth er tasks. D i re c t Ra m b u s D RAM

See RDRAM.

d i re c t o ry An area of a d isk th at stores th e titles given to th e files saved on th e d isk an d serves as a table of con ten ts for th ose files. Con tain s d ata th at id en tifies th e n am e of a file, th e size, th e attribu tes (system , h id d en , read -on ly, an d so on ), th e d ate an d tim e of creation , an d a p oin ter to th e location of th e file. Each en try in a d irectory is 32 bytes lon g. d i sc

Flat, circu lar, rotatin g m ed iu m th at can store variou s typ es of in form ation , both an alog an d d igital. “Disc” is often u sed in referen ce to op tical storage m ed ia, wh ile “d isk” refers to m agn etic storage m ed ia. Disc is often u sed as a sh ort form for vid eod isc or com p act au d io d isc (CD).

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1276

Glossary

d i sk

Altern ative sp ellin g for “d isc” th at gen erally refers to m agn etic storage m ed iu m on wh ich in form ation can be accessed at ran d om . Flop p y d isks an d h ard d isks are exam p les.

d i sk a c c e ss t i m e

See access tim e.

d i sk c a c h e A p ortion of m em ory on th e PC m oth erboard or on a d rive in terface card or con troller u sed to store freq u en tly accessed in form ation from th e d rive (su ch as th e file allocation table (FAT) or d irectory stru ctu re) to sp eed u p d isk access. W ith a larger d isk cach e, ad d ition al d ata from th e d ata p ortion of a d rive can be cach ed as well. See also cache, L1 cache, an d L2 cache. d i sk p a rt i t i o n

See partition.

d i sp l a y a d a p t e r Th e in terface between th e com p u ter an d th e m on itor th at tran sm its th e sign als th at ap p ear as im ages on th e d isp lay. Th is can take th e form of an exp an sion card or a ch ip bu ilt in to th e m oth erboard . d i t h e ri n g Th e p rocess of creatin g m ore colors an d sh ad es from a given color p alette. In m on och rom e d isp lays or p rin ters, d ith erin g will vary th e black an d wh ite d ot p attern s to sim u late sh ad es of gray. Grayscale d ith erin g is u sed to p rod u ce d ifferen t sh ad es of gray wh en th e d evice can on ly p rod u ce lim ited levels of black or wh ite ou tp u ts. Color screen s or p rin ters u se d ith erin g to create ad d ition al colors by m ixin g an d varyin g th e d ot sizin g an d sp acin g. For exam p le, wh en con vertin g from 24bit color to 8-bit color (an 8-bit p alette h as on ly 256 colors com p ared to th e 24-bit p alette’s m illion s), d ith erin g ad d s p ixels of d ifferen t colors to sim u late th e origin al color. Dith erin g is also kn own as error diffusion. D LL Dyn am ic Lin k Library. An execu table d river p rogram m od u le for Microsoft W in d ows th at can be load ed on d em an d an d lin ked in at ru n tim e an d su bseq u en tly u n load ed wh en th e d river is n o lon ger n eed ed . D MA D MI

See direct m em ory access. Desktop Man agem en t In terface. DMI is an op eratin g system - an d p rotocolin d ep en d en t stan d ard d evelop ed by th e Desktop Man agem en t Task Force (DMTF) for m an agin g d esktop system s an d servers. DMI p rovid es a bid irection al p ath to in terrogate all th e h ard ware an d software com p on en ts with in a PC, allowin g h ard ware an d software con figu ration s to be m on itored from a cen tral station in a n etwork.

d o c k i n g st a t i o n Eq u ip m en t th at allows a lap top or n otebook com p u ter to u se p erip h erals an d accessories n orm ally associated with d esktop system s. d o p i n g Ad d in g ch em ical im p u rities to silicon (wh ich is n atu rally a n on con d u ctor), creatin g a m aterial with sem icon d u ctor p rop erties th at is th en u sed in th e m an u factu rin g of electron ic ch ip s. D OS

Disk Op eratin g System . A collection of p rogram s stored on th e DOS d isk th at con tain rou tin es en ablin g th e system an d u ser to m an age in form ation an d th e h ard ware resou rces of th e com p u ter. DOS m u st be load ed in to th e com p u ter before oth er p rogram s can be started .

d o t p i t c h A m easu rem en t of th e wid th of th e d ots th at m ake u p a p ixel. Th e sm aller th e d ot p itch , th e sh arp er th e im age.

Glossary

d o t -m a t ri x p ri n t e r An im p act p rin ter th at p rin ts ch aracters com p osed of d ots. Ch aracters are p rin ted on e at a tim e by p ressin g th e en d s of selected wires again st an in ked ribbon an d p ap er. d o u b l e d e n si t y (D D ) An in d ication of th e storage cap acity of a flop p y d rive or d isk in wh ich eigh t or n in e sectors p er track are record ed u sin g MFM en cod in g. See MFM. dow n tim e

Op eratin g tim e lost becau se of a com p u ter m alfu n ction .

D P MI DOS Protected Mod e In terface. An in d u stry stan d ard in terface th at allows DOS ap p lication s to execu te p rogram cod e in th e p rotected m od e of th e 286 or later In tel p rocessor. Th e DPMI sp ecification is available from In tel. D P MS Disp lay Power Man agem en t Sign alin g. A VESA stan d ard for sign alin g a m on itor or d isp lay to switch in to en ergy con servation m od es. DPMS p rovid es for two low en ergy m od es: stan d by an d su sp en d . D RAM Dyn am ic Ran d om Access Mem ory. Th e m ost com m on typ e of com p u ter m em ory, DRAM can be m ad e very in exp en sively com p ared to oth er typ es of m em ory. DRAM ch ip s are sm all an d in exp en sive becau se th ey n orm ally req u ire on ly on e tran sistor an d a cap acitor to rep resen t each bit. Th e cap acitors m u st be en ergized every 15m s or so (h u n d red s of tim es p er secon d ) to m ain tain th eir ch arges. DRAM is volatile, m ean in g it will lose d ata with n o p ower or with ou t regu lar refresh cycles. d ri v e

A m ech an ical d evice th at m an ip u lates d ata storage m ed ia.

d ri v e r A p rogram d esign ed to in terface a p articu lar p iece of h ard ware to an op eratin g system or oth er stan d ard software. d ru m Th e cylin d rical p h otorecep tor in a laser p rin ter th at receives th e d ocu m en t im age from th e laser an d ap p lies it to th e p age as it slowly rotates. D SM

Digital Storage Med ia. A d igital storage or tran sm ission d evice or system .

D SP

Digital Sign al Processor. Ded icated , lim ited fu n ction p rocessor often fou n d in m od em s, sou n d card s, cellu lar p h on es, an d so on .

D TE

Data Term in al (or Term in atin g) Eq u ip m en t. Th e d evice, u su ally a com p u ter or term in al, th at gen erates or is th e fin al d estin ation of d ata. See also DCE.

d u a l c a v i t y p i n g ri d a rra y Ch ip p ackagin g d esign ed by In tel for u se with th e Pen tiu m Pro p rocessor th at h ou ses th e p rocessor d ie in on e cavity of th e p ackage an d th e L2 cach e m em ory in a secon d cavity with in th e sam e p ackage. D u a l In d e p e n d e n t Bu s (D IB) Arc h i t e c t u re A p rocessor tech n ology with th e existen ce of two in d ep en d en t bu ses on th e p rocessor—th e L2 cach e bu s an d th e p rocessor-to-m ain -m em ory system bu s. Th e p rocessor can u se both bu ses sim u ltan eou sly, th u s gettin g as m u ch as two tim es m ore d ata in to an d ou t of th e p rocessor th an a sin gle bu s arch itectu re p rocessor. Th e In tel Pen tiu m Pro, Pen tiu m II, an d n ewer p rocessors h ave DIB arch itectu re. d u a l sc a n d i sp l a y A lower q u ality bu t econ om ical typ e of LCD color d isp lay th at h as an array of tran sistors ru n n in g d own th e x an d y axes of two sid es of th e screen . Th e n u m ber of tran sistors d eterm in es th e screen ’s resolu tion .

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1278

Glossary

d u p l e x In d icates a com m u n ication s ch an n el cap able of carryin g sign als in both d irection s. D VD

Digital Versatile Disc, origin ally called Digital Vid eo Disc. A n ew typ e of h igh cap acity CD-ROM d isc an d d rive form at with u p to 28 tim es th e cap acity of stan d ard CD-ROM. Th e d isc is th e sam e d iam eter as a CD-ROM bu t can be record ed on both sid es an d on two layers for each sid e. Each sid e h old s 4.7G on a sin gle layer d isc, wh ile d u al-layer version s h old 8.5G p er sid e, for a m axim u m of 17G total if both sid es an d both layers are u sed , wh ich is th e eq u ivalen t of 28 CD-ROMs. DVD d rives can read stan d ard au d io CDs an d CD-ROMs.

D VI

Digital Vid eo In teractive. A stan d ard th at was origin ally d evelop ed at RCA Laboratories an d sold to In tel in 1988. DVI in tegrates d igital m otion , still vid eo, sou n d , grap h ics, an d sp ecial effects in a com p ressed form at. DVI is a h igh ly sop h isticated h ard ware com p ression tech n iq u e u sed in in teractive m u ltim ed ia ap p lication s.

D v o ra k k e y b o a rd A keyboard d esign by Au gu st Dvorak th at was p aten ted in 1936 an d ap p roved by ANSI in 1982. Provid es in creased sp eed an d com fort an d red u ces th e rate of errors by p lacin g th e m ost freq u en tly u sed letters in th e cen ter for u se by th e stron gest fin gers. Fin ger m otion s an d awkward strokes are red u ced by m ore th an 90 p ercen t in com p arison with th e fam iliar QW ERTY keyboard . Th e Dvorak keyboard h as th e five vowel keys, AOEUI, togeth er u n d er th e left h an d in th e cen ter row an d th e five m ost freq u en tly u sed con son an ts, DHTNS, u n d er th e fin gers of th e righ t h an d . d y n a m i c e x e c u t i o n A p rocessin g tech n iq u e th at allows th e p rocessor to d yn am ically p red ict th e ord er of in stru ction s an d execu te th em ou t of ord er in tern ally if n ecessary for an im p rovem en t in sp eed . Makes u se of th e th ree tech n iq u es Mu ltip le Bran ch Pred iction , Data Flow An alysis, an d Sp ecu lative Execu tion . EBCD IC Exten d ed Bin ary Cod ed Decim al In terch an ge Cod e. An IBM-d evelop ed 8-bit cod e for th e rep resen tation of ch aracters. It allows 256 p ossible ch aracter com bin ation s with in a sin gle byte. EBCDIC is th e stan d ard cod e on IBM m in i-com p u ters an d m ain fram es, bu t n ot on th e IBM m icrocom p u ters, wh ere ASCII is u sed in stead . ECC Error Correctin g Cod e. A typ e of system m em ory or cach e th at is cap able of d etectin g an d correctin g som e typ es of m em ory errors with ou t in terru p tin g p rocessin g. ECP

En h an ced Cap abilities Port. A typ e of h igh -sp eed p arallel p ort join tly d evelop ed by Microsoft an d Hewlett-Packard th at offers im p roved p erform an ce for th e p arallel p ort an d req u ires sp ecial h ard ware logic.

e d g e c o n n e c t o r Th e p art of a circu it board con tain in g a series of p rin ted con tacts th at is in serted in to an exp an sion slot or con n ector. ED O (Ex t e n d e d D a t a Ou t ) RAM A typ e of RAM ch ip s th at allow for a tim in g overlap between su ccessive accesses, th u s im p rovin g m em ory cycle tim e. EEP ROM Electrically Erasable Program m able Read On ly Mem ory. A typ e of n on volatile m em ory ch ip u sed to store sem ip erm an en t in form ation in a com p u ter su ch as th e BIOS. An EEPROM can be erased an d rep rogram m ed d irectly in th e h ost system with ou t sp ecial eq u ip m en t. Th is is u sed so m an u factu rers can u p grad e th e ROM cod e in a system by su p p lyin g a sp ecial p rogram th at erases an d rep rogram s th e EEPROM ch ip with th e n ew cod e. Also called a flash ROM.

Glossary

EGA

En h an ced Grap h ics Ad ap ter. A typ e of PC vid eo d isp lay ad ap ter first in trod u ced by IBM on Sep tem ber 10, 1984, th at su p p orts text an d grap h ics. Text is su p p orted at a m axim u m resolu tion of 80×25 ch aracters in 16 colors with a ch aracter box of 8×14 p ixels. Grap h ics is su p p orted at a m axim u m resolu tion of 640×350 p ixels in 16 (from a p alette of 64) colors. Th e EGA ou tp u ts a TTL (d igital) sign al with a h orizon tal scan n in g freq u en cy of 15.75, 18.432, or 21.85KHz, an d su p p orts TTL color or TTL m on och rom e d isp lays.

EIA

Electron ic In d u stries Association . An organ ization th at d efin es electron ic stan d ard s in th e Un ited States.

EID E

En h an ced In tegrated Drive Electron ics. A sp ecific W estern Digital im p lem en tation of th e ATA-2 sp ecification . See ATA-2.

EISA

Exten d ed In d u stry Stan d ard Arch itectu re. An exten sion of th e In d u stry Stan d ard Arch itectu re (ISA) bu s d evelop ed by IBM for th e AT. Th e EISA d esign was led by Com p aq Corp oration . Later, eigh t oth er m an u factu rers (AST, Ep son , HewlettPackard , NEC, Olivetti, Tan d y, W yse, an d Zen ith ) join ed Com p aq in a con sortiu m fou n d ed Sep tem ber 13, 1988. Th is grou p becam e kn own as th e “gan g of n in e.” Th e EISA d esign was p attern ed largely after IBM’s Micro Ch an n el Arch itectu re (MCA) in th e PS/ 2 system s, bu t u n like MCA, EISA allows for backward com p atibility with old er p lu g-in ad ap ters.

e l e c t ro n i c m a i l (e -m a i l ) an oth er.

A m eth od of tran sferrin g m essages from on e com p u ter to

e l e c t ro st a t i c d i sc h a rg e (ESD ) Th e grou n d in g of static electricity. A su d d en flow of electricity between two objects at d ifferen t electrical p oten tials. ESD is a p rim ary cau se of in tegrated circu it d am age or failu re. e m b e d d e d c o n t ro l l e r In d isk d rives, a con troller bu ilt in to th e sam e p h ysical u n it th at h ou ses th e d rive rath er th an on a sep arate ad ap ter card . IDE an d SCSI d rives both u se em bed d ed con trollers. e m b e d d e d se rv o d a t a Magn etic m arkin gs em bed d ed between or in sid e tracks on d isk d rives th at u se voice-coil actu ators. Th ese m arkin gs en able th e actu ator to fin etu n e th e p osition of th e read / write h ead s. EMM

Exp an d ed Mem ory Man ager. A d river th at p rovid es a software in terface to exp an d ed m em ory. EMMs were origin ally created for exp an d ed m em ory board s, bu t can also u se th e m em ory m an agem en t cap abilities of th e 386 or later p rocessors to em u late an exp an d ed m em ory board . EMM386.EXE is an exam p le of an EMM th at com es with DOS.

EMS

Exp an d ed Mem ory Sp ecification . Som etim es also called th e LIM spec becau se it was d evelop ed by Lotu s, In tel, an d Microsoft. Provid es a way for m icrocom p u ters ru n n in g u n d er DOS to access ad d ition al m em ory. EMS m em ory m an agem en t p rovid es access to a m axim u m of 32M of exp an d ed m em ory th rou gh a sm all (u su ally 64K) win d ow in con ven tion al m em ory. EMS is a cu m bersom e access sch em e d esign ed p rim arily for p re-286 system s th at cou ld n ot access exten d ed m em ory.

e m u l a t o r A p iece of test ap p aratu s th at em u lates or im itates th e fu n ction of a p articu lar ch ip . en co d in g

Th e p rotocol by wh ich d ata is carried or stored by a m ed iu m .

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1280

Glossary

e n c ry p t i o n

Th e tran slation of d ata in to u n read able cod es to m ain tain secu rity.

e n d e c (e n c o d e r/ d e c o d e r) A d evice th at takes d ata an d clock sign als an d com bin es or en cod es th em u sin g a p articu lar en cod in g sch em e in to a sin gle sign al for tran sm ission or storage. Th e sam e d evice also later sep arates or d ecod es th e d ata an d clock sign als d u rin g a receive or read op eration . Som etim es called a data separator. En e rg y St a r A certification p rogram started by th e En viron m en tal Protection Agen cy. En ergy Star certified com p u ters an d p erip h erals are d esign ed to d raw less th an 30 watts of electrical en ergy from a stan d ard 110-volt AC ou tlet d u rin g p eriod s of in activity. Also called Green PCs. En h a n c e d Gra p h i c s Ad a p t e r

See EGA.

En h a n c e d Sm a l l D e v i c e In t e rf a c e EP P

See ESDI.

En h an ced Parallel Port. A typ e of p arallel p ort d evelop ed by In tel, Xircom , an d Zen ith Data System s th at op erates alm ost at ISA bu s sp eed an d offers a ten fold in crease in th e raw th rou gh p u t cap ability over a con ven tion al p arallel p ort. EPP is esp ecially d esign ed for p arallel p ort p erip h erals su ch as LAN ad ap ters, d isk d rives, an d tap e backu p s.

EP ROM Erasable p rogram m able read -on ly m em ory. A typ e of read -on ly m em ory (ROM) in wh ich th e d ata p attern can be erased to allow a n ew p attern . EPROM u su ally is erased by u ltraviolet ligh t an d record ed by a h igh er-th an -n orm al voltage p rogram m in g sign al. e q u a l i z a t i o n A com p en sation circu it d esign ed in to m od em s to cou n teract certain d istortion s in trod u ced by th e telep h on e ch an n el. Two typ es are u sed : fixed (com p rom ise) eq u alizers an d th ose th at ad ap t to ch an n el con d ition s (ad ap tive). Good q u ality m od em s u se ad ap tive eq u alization . e rro r c o n t ro l Variou s tech n iq u es th at ch eck th e reliability of ch aracters (p arity) or blocks of d ata. V.42, MNP, an d HST error-con trol p rotocols u se error d etection (CRC) an d retran sm ission of error fram es (ARQ). e rro r m e ssa g e A word or com bin ation of word s to in d icate to th e u ser th at an error h as occu rred som ewh ere in th e p rogram . ESCD Exten d ed System Con figu ration Data. Area in CMOS or Flash / NVRAM wh ere Plu g-an d -Play in form ation is stored . ESD I

En h an ced Sm all Device In terface. A h ard ware stan d ard d evelop ed by Maxtor an d stan d ard ized by a con sortiu m of 22 d isk d rive m an u factu rers on Jan u ary 26, 1983. A grou p of 27 m an u factu rers form ed th e ESDI steerin g com m ittee on Sep tem ber 15, 1986, to en h an ce an d im p rove th e sp ecification . A h igh -p erform an ce in terface u sed p rim arily with h ard d isks, ESDI p rovid es for a m axim u m d ata tran sfer rate to an d from a h ard d isk of between 10 an d 24Mbit/ sec.

Et h e rn e t A typ e of n etwork p rotocol d evelop ed in th e late 1970s by Bob Metcalf at Xerox Corp oration an d en d orsed by th e IEEE. On e of th e old est LAN com m u n ication s p rotocols in th e p erson al com p u tin g in d u stry, Eth ern et n etworks u se a collision -d etection p rotocol to m an age con ten tion .

Glossary

e x p a n d e d m e m o ry Oth erwise kn own as EMS m em ory, m em ory th at con form s to th e EMS sp ecification . Req u ires a sp ecial d evice d river an d con form s to a stan d ard d evelop ed by Lotu s, In tel, an d Microsoft. e x p a n si o n c a rd An in tegrated circu it card th at p lu gs in to an exp an sion slot on a m oth erboard to p rovid e access to ad d ition al p erip h erals or featu res n ot bu ilt in to th e m oth erboard . Also referred to as an add-in board. e x p a n si o n sl o t A slot on th e m oth erboard th at p h ysically an d electrically con n ects an exp an sion card to th e m oth erboard an d th e system bu ses. e Xt e n d e d g ra p h i c s a rra y

See X GA.

e x t e n d e d m e m o ry Direct p rocessor-ad d ressable m em ory th at is ad d ressed by an In tel (or com p atible) 286, 386, or 486 p rocessor in th e region beyon d th e first m egabyte. Ad d ressable on ly in th e p rocessor’s p rotected m od e of op eration . e x t e n d e d p a rt i t i o n A n on bootable DOS p artition con tain in g DOS volu m es. Startin g with DOS v3.3, th e DOS FDISK p rogram can create two p artition s th at serve DOS: an ord in ary, bootable p artition (called th e p rim ary p artition ) an d an exten d ed p artition , wh ich m ay con tain as m an y as 23 volu m es from D: th rou gh Z:. e x t e rn a l d e v i c e

A p erip h eral th at is in stalled ou tsid e of th e system case.

e x t ra -h i g h d e n si t y (ED ) An in d ication of th e storage cap acity of a flop p y d rive or d isk in wh ich 36 sectors p er track are record ed u sin g a vertical record in g tech n iq u e with MFM en cod in g. f a st ATA Fast AT Attach m en t in terface. Also called Fast ATA-2, th ese are sp ecific Seagate an d Qu an tu m im p lem en tation s of th e ATA-2 in terface. See ATA-2. Fa st P a g e Mo d e RAM A typ e of RAM th at im p roves on stan d ard DRAM sp eed by allowin g for faster access to all th e d ata with in a given row of m em ory by keep in g th e row ad d ress th e sam e an d ch an gin g on ly th e colu m n . FAT

File Allocation Table. A table h eld n ear th e ou ter ed ge of a d isk th at tells wh ich sectors are allocated to each file an d in wh at ord er.

FAT 3 2 A d isk file allocation system from Microsoft th at u ses 32-bit valu es for FAT en tries in stead of 16-bit valu es u sed by th e origin al FAT system , en ablin g p artition sizes u p to 2T (terabytes). FAT32 first ap p eared in W in d ows 95B an d is also fou n d in W in d ows 98 an d W in d ows NT 5.0. f a x / m o d e m A p erip h eral th at in tegrates th e cap abilities of a fax m ach in e an d a m od em in on e exp an sion card or extern al u n it. FD ISK Th e n am e of th e d isk-p artition in g p rogram u n d er several op eratin g system s to create th e m aster boot record an d allocate p artition s for th e op eratin g system ’s u se. f e a t u re c o n n e c t o r On a vid eo ad ap ter, a con n ector th at allows an ad d ition al vid eo featu re card su ch as a sep arate 3D accelerator, vid eo cap tu re card , or MPEG d ecod er to be con n ected to th e m ain vid eo ad ap ter an d d isp lay. FIFO

First-in , first-ou t. A m eth od of storin g an d retrievin g item s from a list, table, or stack so th at th e first elem en t stored is th e first on e retrieved .

1281

1282

Glossary

file

A collection of in form ation kep t som ewh ere oth er th an in ran d om -access m em ory.

f i l e a t t ri b u t e

In form ation h eld in th e attribu te byte of a file’s d irectory en try.

f i l e c o m p re ssi o n

See com pressed file.

f i l e n a m e Th e n am e given to th e d isk file. For DOS, it m u st be on e to eigh t ch aracters lon g an d m ay be followed by a file n am e exten sion , wh ich can be on e to th ree ch aracters lon g. W in d ows 95 eases th ese con strain ts by allowin g file n am es of u p to 255 ch aracters. Fi re W i re Also called IEEE 1394. A serial I/ O in terface stan d ard th at is extrem ely fast, with d ata tran sfer rates u p to 400M/ sec, 800M/ sec, or 3.2G/ sec, d ep en d in g on th e version of stan d ard u sed . f i rm w a re Software con tain ed in a read -on ly m em ory (ROM) d evice. A cross between h ard ware an d software. f i x e d d i sk Also called a hard disk, a d isk th at can n ot be rem oved from its con trollin g h ard ware or h ou sin g. Mad e of rigid m aterial with a m agn etic coatin g an d u sed for th e m ass storage an d retrieval of d ata. f l a sh ROM A typ e of EEPROM d evelop ed by In tel th at can be erased an d rep rogram m ed in th e h ost system . See EEPROM. f l i c k e r A m on itor con d ition cau sed by refresh rates th at are too low in wh ich th e d isp lay flash es visibly. Th is can cau se eyestrain or m ore severe p h ysical p roblem s. f l o a t i n g -p o i n t u n i t (FP U) Som etim es called th e m ath cop rocessor; h an d les th e m ore com p lex calcu lation s of th e p rocessin g cycle. f l o p p y d i sk A rem ovable d isk u sin g flexible m agn etic m ed ia en closed in a sem irigid or rigid p lastic case. f l o p p y d i sk c o n t ro l l e r th e system .

Th e logic an d in terface th at con n ects a flop p y d isk d rive to

f l o p p y t a p e A tap e stan d ard th at u ses d rives con n ectin g to an ord in ary flop p y d isk con troller. f l o p t i c a l d ri v e A sp ecial typ e of h igh -cap acity rem ovable d isk d rive th at u ses an op tical m ech an ism to p rop erly p osition th e d rive read / write h ead s over th e d ata tracks on th e d isk, allowin g for m ore p recise con trol of th e read / write p osition in g an d th erefore n arrower track sp acin g an d m ore d ata p acked in to a sm aller area th an trad ition al flop p y d isks. f l o w c o n t ro l A m ech an ism th at com p en sates for d ifferen ces in th e flow of d ata in p u t to an d ou tp u t from a m od em or oth er d evice. FM e n c o d i n g Freq u en cy m od u lation en cod in g. An ou td ated m eth od of en cod in g d ata on th e d isk su rface th at u ses u p h alf th e d isk sp ace with tim in g sign als. FM sy n t h e si s An au d io tech n ology th at u ses on e sin e wave op erator to m od ify an oth er an d create an artificial sou n d th at m im ics an in stru m en t. f o l d e r In a grap h ical u ser in terface, a sim u lated file fold er th at h old s d ocu m en ts (text, d ata, or grap h ics), ap p lication s, an d oth er fold ers. A fold er is like a DOS su bd irectory.

Glossary

f o rm f a c t o r Th e p h ysical d im en sion s of a d evice. Two d evices with th e sam e form factor are p h ysically in terch an geable. Th e IBM PC, XT, an d XT Mod el 286, for exam p le, all u se p ower su p p lies th at are in tern ally d ifferen t bu t h ave exactly th e sam e form factor. FORMAT Th e DOS form at p rogram th at p erform s both low- an d h igh -level form attin g on flop p y d isks bu t on ly h igh -level form attin g on h ard d isks. f o rm a t t e d c a p a c i t y Th e total n u m ber of bytes of d ata th at can fit on a form atted d isk. Th e u n form atted cap acity is h igh er becau se sp ace is lost d efin in g th e bou n d aries between sectors. f o rm a t t i n g Prep arin g a d isk so th at th e com p u ter can read or write to it. Ch ecks th e d isk for d efects an d con stru cts an organ ization al system to m an age in form ation on th e d isk. FORTRAN Form u la tran slator. A h igh -level p rogram m in g lan gu age d evelop ed in 1954 by Joh n Backu s at IBM, p rim arily for p rogram s d ealin g with m ath em atical form u las an d exp ression s sim ilar to algebra an d u sed p rim arily in scien tific an d tech n ical ap p lication s. f ra g m e n t a t i o n Th e state of h avin g a file scattered arou n d a d isk in p ieces rath er th an existin g in on e con tigu ou s area of th e d isk. Fragm en ted files are slower to read th an files stored in con tigu ou s areas an d can be m ore d ifficu lt to recover if th e FAT or a d irectory becom es d am aged . f ra m e 1) A d ata com m u n ication s term for a block of d ata with h ead er an d trailer in form ation attach ed . Th e ad d ed in form ation u su ally in clu d es a fram e n u m ber, block size d ata, error-ch eck cod es, an d start/ en d in d icators. 2) Also a sin gle, com p lete p ictu re in a vid eo or film record in g. A vid eo fram e con sists of two in terlaced field s of eith er 525 lin es (NTSC) or 625 lin es (PAL/ SECAM), ru n n in g at 30 fram es p er secon d (NTSC) or 25 fram es p er secon d (PAL/ SECAM). f ra m e b u f f e r A m em ory d evice th at stores, p ixel by p ixel, th e con ten ts of an im age. Fram e bu ffers are u sed to refresh a raster im age. Som etim es th ey in corp orate local p rocessin g cap ability. Th e “d ep th ” of th e fram e bu ffer is th e n u m ber of bits p er p ixel, wh ich d eterm in es th e n u m ber of colors or in ten sities th at can be d isp layed . f ra m e ra t e Th e sp eed at wh ich vid eo fram es are scan n ed or d isp layed , 30 fram es p er secon d for NTSC, 25 fram es a secon d for PAL/ SECAM. FTP

File Tran sfer Protocol. A m eth od of tran sferrin g files over th e In tern et. FTP can be u sed to tran sfer files between two m ach in es on wh ich th e u ser h as accou n ts. An on ym ou s FTP can be u sed by a u ser to retrieve a file from a server with ou t h avin g an accou n t on th at server.

f u l l d u p l e x Sign al flow in both d irection s at th e sam e tim e. In m icrocom p u ter com m u n ication s, also m ay refer to th e su p p ression of th e on lin e local ech o. f u l l -h e i g h t d ri v e in ch es d eep .

A d rive u n it th at is 3.25 in ch es h igh , 5.75 in ch es wid e, an d 8

f u l l -m o t i o n v i d e o A vid eo seq u en ce d isp layed at fu ll television stan d ard resolu tion s an d fram e rates. In th e U.S., th is wou ld eq u ate to NTSC vid eo at 30 fram es p er secon d .

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Glossary

f u n c t i o n k e y s Sp ecial-p u rp ose keys th at can be p rogram m ed to p erform variou s op eration s. Serve m an y d ifferen t fu n ction s d ep en d in g on th e p rogram bein g u sed . g a s-p l a sm a d i sp l a y Com m on ly u sed in p ortable system s, a typ e of d isp lay th at op erates by excitin g a gas, u su ally n eon or an argon -n eon m ixtu re, th rou gh th e ap p lication of a voltage. W h en su fficien t voltage is ap p lied at th e in tersection of two electrod es, th e gas glows an oran ge-red . Becau se gas-p lasm a d isp lays gen erate ligh t, th ey req u ire n o backligh tin g. g a t e w a y Officially, an ap p lication -to-ap p lication con version p rogram or system . For exam p le, an e-m ail gateway wou ld con vert between SMTP (In tern et) e-m ail form at to MHS (Novell) e-m ail form at. Th e term gateway is also u sed as a slan g term for rou ter. See also router. g e n d e r W h en d escribin g con n ectors for PCs, con n ectors are d escribed as m ale if th ey h ave p in s or fem ale if th ey h ave recep tacles d esign ed to accep t th e p in s of a m ale con n ector. g e n l o c k i n g Th e p rocess of align in g th e d ata rate of a vid eo im age with th at of a d igital d evice to d igitize th e im age an d en ter it in to com p u ter m em ory. Th e m ach in e th at p erform s th is fu n ction is kn own as a genlock. GIF Grap h ics In terch an ge Form at. A p op u lar raster grap h ics file form at d evelop ed by Com p u Serve th at h an d les 8-bit color (256 colors) an d u ses th e LZW m eth od to ach ieve com p ression ratios of ap p roxim ately 1.5:1 to 2:1. giga

A m u ltip lier in d icatin g 1 billion (1,000,000,000) of som e u n it. Abbreviated as g or G. W h en u sed to in d icate a n u m ber of bytes of m em ory storage, th e m u ltip lier d efin ition ch an ges to 1,073,741,824. On e gigabit, for exam p le, eq u als 1,000,000,000 bits, an d on e gigabyte eq u als 1,073,741,824 bytes.

g i g a b y t e (G)

A u n it of in form ation storage eq u al to 1,073,741,824 bytes.

g ra p h i c s a c c e l e ra t o r A vid eo p rocessor or ch ip set sp ecially d esign ed to sp eed d isp lay an d ren d erin g of grap h ical objects on screen . g ra p h i c s a d a p t e r

See video adapter.

Gre e n Bo o k Th e stan d ard for Com p act Disc-In teractive (CD-I). Ph ilip s d evelop ed CD-I tech n ology for th e con su m er m arket, to be con n ected to a television in stead of a com p u ter m on itor. CD-I is n ot a com p u ter system bu t a con su m er d evice th at m ad e a sm all sp lash in th e m arket an d d isap p eared . CD-I d isks req u ire sp ecial cod e an d are n ot com p atible with stan d ard CD-ROMs. A CD-ROM can n ot be p layed on th e CD-I m ach in e, bu t Red Book au d io can be p layed on CD-I d evices. GUI

Grap h ical User In terface. A typ e of p rogram in terface th at allows u sers to ch oose com m an d s an d fu n ction s by p oin tin g to a grap h ical icon u sin g eith er a keyboard or p oin tin g d evice su ch as a m ou se. W in d ows an d OS/ 2 are th e m ost p op u lar GUIs available for PC system s.

h a l f d u p l e x Sign al flow in both d irection s bu t on ly on e way at a tim e. In m icrocom p u ter com m u n ication s, h alf d u p lex m ay refer to activation of th e on lin e local ech o, wh ich cau ses th e m od em to sen d a cop y of th e tran sm itted d ata to th e screen of th e sen d in g com p u ter.

Glossary

h a l f -h e i g h t d ri v e A d rive u n it th at is 1.625 in ch es h igh , an d eith er 5.75 or 4 in ch es wid e an d 4 or 8 in ch es d eep . h a l f t o n i n g A p rocess th at u ses d ith erin g to sim u late a con tin u ou s ton e im age su ch as a p h otograp h or sh ad ed d rawin g u sin g variou s sizes of d ots. Newsp ap ers, m agazin es, an d m an y books u se h alfton in g. Th e h u m an eye will m erge th e d ots to give th e im p ression of gray sh ad es. h a rd d i sk A h igh -cap acity d isk storage u n it ch aracterized by a n orm ally n on rem ovable rigid su bstrate m ed iu m . Th e p latters in a h ard d isk n orm ally are con stru cted of alu m in u m or glass/ ceram ic. Also som etim es called a fixed disk. h a rd e rro r

An error in read in g or writin g d ata th at is cau sed by d am aged h ard ware.

h a rd w a re Ph ysical com p on en ts th at m ake u p a m icrocom p u ter, m on itor, p rin ter, an d so on . H D LC High -Level Data Lin k Con trol. A stan d ard p rotocol d evelop ed by th e ISO for software ap p lication s an d com m u n icatin g d evices op eratin g in syn ch ron ou s en viron m en ts. Defin es op eration s at th e lin k level of com m u n ication s—for exam p le, th e form at of d ata fram es exch an ged between m od em s over a p h on e lin e. h ead

A sm all electrom agn etic d evice in sid e a d rive th at read s, record s, an d erases d ata on th e m ed ia.

h e a d a c t u a t o r Th e d evice th at m oves read / write h ead s across a d isk d rive’s p latters. Most d rives u se a step p er-m otor or a voice-coil actu ator. h e a d c ra sh A (u su ally) rare occu rren ce in wh ich a read / write h ead strikes a p latter su rface with su fficien t force to d am age th e m agn etic m ed iu m . h e a d p a rk i n g A p roced u re in wh ich a d isk d rive’s read / write h ead s are m oved to an u n u sed track so th at th ey will n ot d am age d ata in th e even t of a h ead crash or oth er failu re. h e a d se e k

Th e m ovem en t of a d rive’s read / write h ead s to a p articu lar track.

h e a t si n k A m ass of m etal attach ed to a ch ip carrier or socket for th e p u rp ose of d issip atin g h eat. h e l i c a l sc a n A typ e of record in g tech n ology th at h as vastly in creased th e cap acity of tap e d rives. In ven ted for u se in broad cast system s an d n ow u sed in VCRs. Con ven tion al lon gitu d in al record in g record s a track of d ata straigh t across th e wid th of a sin gle-track tap e. Helical scan record in g p acks m ore d ata on th e tap e by p osition in g th e tap e at an an gle to th e record in g h ead s. Th e h ead s sp in to record d iagon al strip es of in form ation on th e tap e. h e x a d e c i m a l n u m b e r A n u m ber en cod ed in base-16, su ch th at d igits in clu d e th e letters A th rou gh F as well as th e n u m erals 0 th rou gh 9 (for exam p le, 8BF3, wh ich eq u als 35,827 in base-10). h i d d e n f i l e A file th at is n ot d isp layed in DOS d irectory listin gs becau se th e file’s attribu te byte h old s a sp ecial settin g. h i g h d e n si t y (H D ) An in d ication of th e storage cap acity of a flop p y d rive or d isk in wh ich 15 or 18 sectors p er track are record ed u sin g MFM en cod in g.

1285

1286

Glossary

h i g h si e rra f o rm a t A stan d ard form at for p lacin g files an d d irectories on CD-ROMs, p rop osed by an ad h oc com m ittee of com p u ter ven d ors, software d evelop ers, an d CD-ROM system in tegrators. (W ork on th e form at p rop osal began at th e High Sierra Hotel at Lake Tah oe, Nevad a.) A revised version of th e form at was ad op ted by th e ISO as ISO 9660. h i g h -d e f i n i t i o n t e l e v i si o n HDTV. Vid eo form ats offerin g greater visu al accu racy (or resolu tion ) th an cu rren t NTSC, PAL, or SECAM broad cast stan d ard s. HDTV form ats gen erally ran ge in resolu tion from 655 to 2,125 scan n in g lin es, h avin g an asp ect ration of 5:3 (or 1.67:1) an d a vid eo ban d wid th of 30 to 50MHz (5+ tim es greater th an NTSC stan d ard ). Digital HDTV h as a ban d wid th of 300MHz. HDTV is su bjectively com p arable to 35m m film . h i g h -l e v e l f o rm a t t i n g Form attin g p erform ed by th e DOS FORMAT p rogram . Am on g oth er th in gs, it creates th e root d irectory an d FATs. h i st o ry f i l e A file created by u tility software to keep track of earlier u se of th e software. Man y backu p p rogram s, for exam p le, keep h istory files d escribin g earlier backu p session s. h i t ra t i o In d escribin g th e efficien cy of a d isk or m em ory cach e, th e ratio of th e n u m ber of tim es th e d ata is fou n d in th e cach e to th e total n u m ber of d ata req u ests is th e h it ratio. 1:1 wou ld be a p erfect h it ratio, m ean in g th at every d ata req u est was fou n d in th e cach e. Th e closer to 1:1 th e ratio is, th e m ore efficien t th e cach e. H MA

High Mem ory Area. Th e first 64K of exten d ed m em ory, wh ich is con trolled typ ically by th e HIMEM.SYS d evice d river. Real-m od e p rogram s can be load ed in to th e HMA to con serve con ven tion al m em ory. Norm ally, DOS 5.0 an d later u se th e HMA exclu sively to red u ce th e DOS con ven tion al m em ory footp rin t.

h o ri z o n t a l sc a n ra t e In m on itors, th e sp eed at wh ich th e electron beam m oves laterally across th e screen . Norm ally exp ressed as a freq u en cy; typ ical m on itors ran ge from 31.5KHz to 90KHz, with th e h igh er freq u en cies bein g m ore d esirable. HPT

High -Pressu re Tin . A PLCC socket th at p rom otes h igh forces between socket con tacts an d PLCC con tacts for a good con n ection .

H ST

High -Sp eed Tech n ology. Th e USRobotics p rop rietary h igh -sp eed m od em -sign alin g sch em e, d evelop ed as an in terim p rotocol u n til th e V.32 p rotocol cou ld be im p lem en ted in a cost-effective m an n er.

H TML Hyp ertext Marku p Lan gu age. A lan gu age u sed to d escribe an d form at p lain -text files on th e W eb. HTML is based on p airs of tags th at allow you to m ix grap h ics with text, ch an ge th e ap p earan ce of text, an d create h yp ertext d ocu m en ts with lin ks to oth er d ocu m en ts. H TTP Hyp ertext Tran sfer Protocol. Th e p rotocol th at d escribes th e ru les th at a browser an d server u se to com m u n icate over th e W orld W id e W eb. HTTP allows a W eb browser to req u est HTML d ocu m en ts from a W eb server. See also hypertext. H u f f m a n c o d i n g A tech n iq u e th at m in im izes th e average n u m ber of bytes req u ired to rep resen t th e ch aracters in a text. Hu ffm an cod in g works for a given ch aracter d istribu tion by assign in g sh ort cod es to freq u en tly occu rrin g ch aracters an d lon ger cod es to in freq u en tly occu rrin g ch aracters.

Glossary

h y p e rt e x t A tech n ology th at allows for q u ick an d easy n avigation between an d with in large d ocu m en ts. Hyp ertext lin ks are p oin ters to oth er section s with in th e sam e d ocu m en t, oth er d ocu m en ts, or oth er resou rces su ch as FTP sites, im ages, or sou n d s. Hz

An abbreviation for h ertz, a freq u en cy m easu rem en t u n it u sed in tern ation ally to in d icate on e cycle p er secon d .

I/ O

In p u t/ Ou tp u t. A circu it p ath th at en ables in d ep en d en t com m u n ication s between th e p rocessor an d extern al d evices.

I/ O p o rt In p u t/ Ou tp u t p ort. Used to com m u n icate to an d from d evices, su ch as a p rin ter or d isk. IBMBIO.COM On e of th e DOS system files req u ired to boot th e m ach in e. Th e first file load ed from d isk d u rin g th e boot. Con tain s exten sion s to th e ROM BIOS. IBMD OS.COM On e of th e DOS system files req u ired to boot th e m ach in e. Con tain s th e p rim ary DOS rou tin es. Load ed by IBMBIO.COM, it in tu rn load s COMMAND.COM. IC In tegrated Circu it. A com p lete electron ic circu it con tain ed on a sin gle ch ip . May con sist of on ly a few or th ou san d s of tran sistors, cap acitors, d iod es, or resistors, an d gen erally is classified accord in g to th e com p lexity of th e circu itry an d th e ap p roxim ate n u m ber of circu its on th e ch ip . SSI (sm all-scale in tegration ) eq u als 2 to 10 circu its. MSI (m ed iu m -scale in tegration ) eq u als 10 to 100 circu its. LSI (largescale in tegration ) eq u als 100 to 1,000 circu its. VLSI (very-large-scale in tegration ) eq u als 1,000 to 10,000 circu its. ULSI (u ltra-large-scale in tegration ) eq u als m ore th an 10,000 circu its. IEEE 8 0 2 .3

See 10Base2.

IEEE 1 3 9 4

See FireW ire.

ID E

In tegrated Drive Electron ics. Describes a h ard d isk with th e d isk con troller circu itry in tegrated with in it. Th e first IDE d rives com m on ly were called h ard card s. Also refers to th e ATA interface standard, th e stan d ard for attach in g h ard d isk d rives to ISA bu s IBM-com p atible com p u ters. IDE d rives typ ically op erate as th ou gh th ey were stan d ard ST-506/ 412 d rives. See also ATA.

i n c re m e n t a l b a c k u p

A backu p of all files th at h ave ch an ged sin ce th e last backu p .

i n d u c t i v e A p rop erty wh ere en ergy can be tran sferred from on e d evice to an oth er via th e m agn etic field gen erated by th e d evice even th ou gh n o d irect electrical con n ection is establish ed between th e two. .INF f i l e A W in d ows d river an d d evice in form ation file u sed to in stall n ew d rivers or services. i n i t i a t o r A d evice attach ed to th e SCSI bu s th at sen d s a com m an d to an oth er d evice (th e target) on th e SCSI bu s. Th e SCSI h ost ad ap ter p lu gged in to th e system bu s is an exam p le of a SCSI in itiator. i n k je t p ri n t e r A typ e of p rin ter th at sp rays on e or m ore colors of in k on th e p ap er. Can p rod u ce ou tp u t with q u ality ap p roach in g th at of a laser p rin ter at a lower cost.

1287

1288

Glossary

i n p u t Data sen t to th e com p u ter from th e keyboard , telep h on e, vid eo cam era, an oth er com p u ter, p ad d les, joysticks, an d so on . i n st ru c t i o n

Program step th at tells th e com p u ter wh at to d o for a sin gle op eration .

i n t e g ra t e d c i rc u i t

See IC.

i n t e rf a c e A com m u n ication s d evice or p rotocol th at en ables on e d evice to com m u n icate with an oth er. Match es th e ou tp u t of on e d evice to th e in p u t of th e oth er d evice. i n t e rl a c i n g A m eth od of scan n in g altern ate lin es of p ixels on a d isp lay screen . Th e od d lin es are scan n ed first from top to bottom an d left to righ t. Th e electron gu n goes back to th e top an d m akes a secon d p ass, scan n in g th e even lin es. In terlacin g req u ires two scan p asses to con stru ct a sin gle im age. Becau se of th is ad d ition al scan n in g, in terlaced screen s often seem to flicker u n less a lon g p ersisten ce p h osp h or is u sed in th e d isp lay. i n t e rl e a v e ra t i o Th e n u m ber of sectors th at p ass ben eath th e read / write h ead s before th e “n ext” n u m bered sector arrives. W h en th e in terleave ratio is 3:1, for exam p le, a sector is read , two p ass by, an d th en th e n ext is read . A p rop er in terleave ratio, laid d own d u rin g low-level form attin g, en ables th e d isk to tran sfer in form ation with ou t excessive revolu tion s d u e to m issed sectors. i n t e rl e a v e d m e m o ry Th e p rocess of altern atin g access between two ban ks of m em ory to overlap accesses, th u s sp eed in g u p d ata retrieval. i n t e rn a l c o m m a n d In DOS, a com m an d con tain ed in COMMAND.COM so th at n o oth er file m u st be load ed to p erform th e com m an d . DIR an d COPY are two exam p les of in tern al com m an d s. i n t e rn a l d e v i c e A p erip h eral d evice th at is in stalled in sid e th e m ain system case eith er in an exp an sion slot or in a d rive bay. i n t e rn a l d ri v e A d isk or tap e d rive m ou n ted in sid e on e of a com p u ter’s d isk d rive bays (or a h ard d isk card , wh ich is in stalled in on e of th e com p u ter’s slots). In t e rn e t A com p u ter n etwork th at join s m an y govern m en t, u n iversity, an d p rivate com p u ters togeth er over p h on e lin es. Th e In tern et traces its origin s to a n etwork set u p in 1969 by th e Dep artm en t of Defen se. You can con n ect to th e In tern et th rou gh m an y on lin e services su ch as Com p u Serve an d Am erica On lin e, or you can con n ect th rou gh local In tern et service p rovid ers (ISPs). In tern et com p u ters u se th e TCP/ IP com m u n ication s p rotocol. Th ere are several m illion h osts on th e In tern et. A host is a m ain fram e, m in i, or workstation th at d irectly su p p orts th e In tern et p rotocol (th e IP in TCP/ IP). i n t e rp re t e r A p rogram for a h igh -level lan gu age th at tran slates an d execu tes th e p rogram at th e sam e tim e. Th e p rogram statem en ts th at are in terp reted rem ain in th eir origin al sou rce lan gu age, th e way th e p rogram m er wrote th em —th at is, th e p rogram d oes n ot n eed to be com p iled before execu tion . In terp reted p rogram s ru n slower th an com p iled p rogram s an d always m u st be ru n with th e in terp reter load ed in m em ory. i n t e rru p t A su sp en sion of a p rocess, su ch as th e execu tion of a com p u ter p rogram , cau sed by an even t extern al to th at p rocess an d p erform ed in su ch a way th at th e p rocess can be resu m ed . An in terru p t can be cau sed by in tern al or extern al

Glossary

con d ition s su ch as a sign al in d icatin g th at a d evice or p rogram h as com p leted a tran sfer of d ata. i n t e rru p t v e c t o r A p oin ter in a table th at gives th e location of a set of in stru ction s th at th e com p u ter sh ou ld execu te wh en a p articu lar in terru p t occu rs. IO.SYS On e of th e DOS system files req u ired to boot th e m ach in e. Th e first file load ed from d isk d u rin g th e boot. Con tain s exten sion s to th e ROM BIOS. IP X

In tern et Packet eXch an ge. Novell NetW are’s n ative LAN com m u n ication s p rotocol u sed to m ove d ata between server an d / or workstation p rogram s ru n n in g on d ifferen t n etwork n od es. IPX p ackets are en cap su lated an d carried by th e p ackets u sed in Eth ern et an d th e sim ilar fram es u sed in Token -Rin g n etworks.

IRQ

In terru p t req u est. Ph ysical con n ection s between extern al h ard ware d evices an d th e in terru p t con trollers. W h en a d evice su ch as a flop p y con troller or a p rin ter n eed s th e atten tion of th e CPU, an IRQ lin e is u sed to get th e atten tion of th e system to p erform a task. On PC an d XT IBM-com p atible system s, eigh t IRQ lin es are in clu d ed , n u m bered IRQ0 th rou gh IRQ7. On th e AT an d PS/ 2 system s, 16 IRQ lin es are n u m bered IRQ0 th rou gh IRQ15. IRQ lin es m u st be u sed on ly by a sin gle ad ap ter in th e ISA bu s system s, bu t Micro Ch an n el Arch itectu re (MCA) ad ap ters can sh are in terru p ts.

ISA

In d u stry Stan d ard Arch itectu re. Th e bu s arch itectu re th at was in trod u ced as an 8-bit bu s with th e origin al IBM PC in 1981 an d later exp an d ed to 16 bits with th e IBM PC/ AT in 1984. ISA slots are still fou n d in PC system s tod ay.

ISA b u s c l o c k

Clock th at op erates th e ISA bu s at n orm ally 8.33MHz.

ISD N

In tegrated Services Digital Network. An in tern ation al telecom m u n ication s stan d ard th at en ables a com m u n ication s ch an n el to carry d igital d ata sim u ltan eou sly with voice an d vid eo in form ation .

ISO

In tern ation al Stan d ard s Organ ization . Th e ISO, based in Paris, d evelop s stan d ard s for in tern ation al an d n ation al d ata com m u n ication s. Th e U.S. rep resen tative to th e ISO is th e Am erican Nation al Stan d ard s In stitu te (ANSI). See also high sierra form at.

ISO 9 6 6 0 An in tern ation al stan d ard th at d efin es file system s for CD-ROM d isks, in d ep en d en t of th e op eratin g system . ISO (In tern ation al Stan d ard s Organ ization ) 9660 h as two levels. Level on e p rovid es for DOS file system com p atibility, wh ile Level two allows file n am es of u p to 32 ch aracters. See also high sierra form at. ITU

In tern ation al Telecom m u n ication s Un ion . Form erly called CCITT. An in tern ation al com m ittee organ ized by th e Un ited Nation s to set in tern ation al com m u n ication s recom m en d ation s, wh ich freq u en tly are ad op ted as stan d ard s, an d to d evelop in terface, m od em , an d d ata n etwork recom m en d ation s. Th e Bell 212A stan d ard for 1,200bp s com m u n ication in North Am erica, for exam p le, is observed in tern ation ally as CCITT V.22. For 2,400bp s com m u n ication , m ost U.S. m an u factu rers observe V.22bis, wh ile V.32, V.32bis, V34 an d V34+ are stan d ard s for 9,600, 14,400, 28,800, an d 33,600bp s, resp ectively. Th e V.90 stan d ard recen tly was d efin ed for 56Kbp s m od em s.

J-l e a d J-sh ap ed lead s on ch ip carriers, wh ich can be su rface-m ou n ted on a PC board or p lu gged in to a socket th at th en is m ou n ted on a PC board , u su ally on .050-in ch cen ters.

1289

1290

Glossary

Ja v a

An object-orien ted p rogram m in g lan gu age an d en viron m en t sim ilar to C or C++. Java was d evelop ed by Su n Microsystem s an d is u sed to create n etwork-based ap p lication s.

Ja z d riv e A proprietary type of rem ovable m edia drive with a m agn etic h ard disk platter in a rigid plastic case. Developed by Iom ega an d curren tly available in 1G an d 2G sizes. JED EC Join t Electron ic Devices En gin eerin g Cou n cil. A grou p th at establish es stan d ard s for th e electron ics in d u stry. jo y st i c k An in p u t d evice gen erally u sed for gam e software u su ally con sistin g of a cen tral u p righ t stick th at con trols h orizon tal an d vertical m otion an d on e or m ore bu tton s to con trol d iscrete even ts su ch as firin g gu n s. More com p lex m od els m ay resem ble fligh t yokes an d steerin g wh eels or m ay in corp orate tactile feed back. JP EG

Join t Ph otograp h ic Exp erts Grou p . Th e in tern ation al con sortiu m of h ard ware, software, an d p u blish in g in terests wh o, u n d er th e au sp ices of th e ISO, h as d efin ed a u n iversal stan d ard for d igital com p ression an d d ecom p ression of still im ages for u se in com p u ter system s. JPEG com p resses at abou t a 20:1 ratio before visible im age d egrad ation occu rs. A lossy d ata com p ression stan d ard th at was origin ally d esign ed for still im ages bu t can also com p ress real-tim e vid eo (30 fram es p er secon d ) an d an im ation . Lossy com p ression p erm an en tly d iscard s u n n ecessary d ata, resu ltin g in som e loss of p recision .

ju k e b o x A typ e of CD-ROM d rive th at allows several CD-ROM d isks to be in th e d rive at th e sam e tim e. Th e d rive itself d eterm in es wh ich d isk is n eed ed by th e system an d load s th e d isks in to th e read in g m ech an ism as n eed ed . ju m p e r A sm all, p lastic-covered m etal clip th at slip s over two p in s p rotru d in g from a circu it board . Som etim es also called a shunt. W h en in p lace, th e ju m p er con n ects th e p in s electrically an d closes th e circu it. By d oin g so, it con n ects th e two term in als of a switch , tu rn in g it “on .” Ke rm i t A p rotocol d esign ed for tran sferrin g files between m icrocom p u ters an d m ain fram es. Develop ed by Fran k DaCru z an d Bill Catch in gs at Colu m bia Un iversity (an d n am ed after th e talkin g frog on The Muppet Show), Kerm it is wid ely accep ted in th e acad em ic world . k e rn e l

Op eratin g system core com p on en t.

k e y d i sk In software cop y p rotection , a d istribu tion flop p y d isk th at m u st be p resen t in a flop p y d isk d rive for an ap p lication p rogram to ru n . k e y b o a rd Th e p rim ary in p u t d evice for m ost com p u ters con sistin g of keys with letters of th e alp h abet, d igits, p u n ctu ation , an d fu n ction con trol keys. k e y b o a rd m a c ro p ressed .

A series of keystrokes au tom atically in p u t wh en a sin gle key is

k e y l o c k Ph ysical lockin g m ech an ism to p reven tin g in tern al access to th e system u n it or p erip h erals. KFl e x A p rop rietary stan d ard for 56Kbp s m od em tran sm ission s d evelop ed by Rockwell an d im p lem en ted in m od em s from a variety of ven d ors. Su p ersed ed by th e official V.90 stan d ard for 56Kbp s m od em s. See also X 2 an d V .90.

Glossary

k ilo

A m u ltip lier in d icatin g on e th ou san d (1,000) of som e u n it. Abbreviated as k or K. W h en u sed to in d icate a n u m ber of bytes of m em ory storage, th e m u ltip lier d efin ition ch an ges to 1,024. On e kilobit, for exam p le, eq u als 1,000 bits, an d on e kilobyte eq u als 1,024 bytes.

k i l o b y t e (K)

A u n it of in form ation storage eq u al to 1,024 bytes.

L1 c a c h e (l e v e l o n e ) A m em ory cach e th at is bu ilt in to th e CPU core of 486 an d later gen eration p rocessors. See cache an d disk cache. L2 c a c h e (l e v e l t w o ) A secon d -level m em ory cach e th at is extern al to th e p rocessor core, u su ally larger an d slower th an L1. Norm ally fou n d on th e m oth erboard of 386, 486, an d Pen tiu m system s an d in sid e th e p rocessor p ackage or m od u le in Pen tiu m Pro an d Pen tiu m II system s. Movin g th e L2 cach e on to th e p rocessor in th e Pen tiu m Pro an d Pen tiu m II allows it to ru n at sp eed s u p to fu ll p rocessor sp eed rath er th an m oth erboard sp eed . See SEC (single edge contact) cartridge, cache, an d disk cache. l a n d i n g z o n e An u n u sed track on a d isk su rface on wh ich th e read / write h ead s can lan d wh en p ower is sh u t off. Th e p lace th at a p arkin g p rogram or a d rive with an au top ark m ech an ism p arks th e h ead s. LAP M Lin k-access p roced u re for m od em s. An error-con trol p rotocol in corp orated in CCITT Recom m en d ation V.42. Like th e MNP an d HST p rotocols, u ses cyclic red u n d an cy ch eckin g (CRC) an d retran sm ission of corru p ted d ata (ARQ) to en su re d ata reliability. l a p t o p c o m p u t e r A com p u ter system sm aller th an a briefcase bu t larger th an a n otebook th at u su ally h as a clam sh ell d esign in wh ich th e keyboard an d d isp lay are on sep arate h alves of th e system , wh ich are h in ged togeth er. Th ese system s n orm ally ru n on battery p ower. l a rg e m o d e An oth er n am e for th e LBA tran slation sch em e u sed by IDE d rives to tran slate th e cylin d er, h ead , an d sector sp ecification s of th e d rive to th ose u sable by an en h an ced BIOS. l a rg e sc a l e i n t e g ra t i o n

See IC.

l a se r p ri n t e r A typ e of p rin ter th at is a com bin ation of an electrostatic cop yin g m ach in e an d a com p u ter p rin ter. Th e ou tp u t d ata from th e com p u ter is con verted by an in terface in to a raster feed , sim ilar to th e im p u lses th at a TV p ictu re tu be receives. Th e im p u lses cau se th e laser beam to scan a sm all d ru m th at carries a p ositive electrical ch arge. W h ere th e laser h its, th e d ru m is d isch arged . A ton er, wh ich also carries a p ositive ch arge, is th en ap p lied to th e d ru m . Th is ton er, a fin e black p owd er, sticks on ly to th e areas of th e d ru m th at h ave been d isch arged electrically. As it rotates, th e d ru m d ep osits th e ton er on a n egatively ch arged sh eet of p ap er. An oth er roller th en h eats an d bon d s th e ton er to th e p age. l a t e n c y 1) Th e am ou n t of tim e req u ired for a d isk d rive to rotate h alf of a revolu tion . Rep resen ts th e average am ou n t of tim e to locate a sp ecific sector after th e h ead s h ave arrived at a sp ecific track. Laten cy is p art of th e average access tim e for a d rive. 2) Th e in itial setu p tim e req u ired for a m em ory tran sfer in DRAM to select th e row an d colu m n ad d resses for th e m em ory to be read / written .

1291

1292

Glossary

LBA

Logical Block Ad d ressin g. A m eth od u sed with SCSI an d IDE d rives to tran slate th e cylin d er, h ead , an d sector sp ecification s of th e d rive to th ose u sable by an en h an ced BIOS. LBA is u sed with d rives th at are larger th an 528M an d cau ses th e BIOS to tran slate th e d rive’s logical p aram eters to th ose u sable by th e system BIOS.

LCC Lead less Ch ip Carrier. A typ e of in tegrated circu it p ackage th at h as in p u t an d ou tp u t p ad s rath er th an lead s on its p erim eter. LCD

Liq u id Crystal Disp lay. A d isp lay th at u ses liq u id crystal sealed between two p ieces of p olarized glass. Th e p olarity of th e liq u id crystal is ch an ged by an electric cu rren t to vary th e am ou n t of ligh t th at can p ass th rou gh . Becau se LCD d isp lays d o n ot gen erate ligh t, th ey d ep en d on eith er th e reflection of am bien t ligh t or backligh tin g th e screen . Th e best typ e of LCD, th e active-m atrix or th in -film tran sistor (TFT) LCD, offers fast screen u p d ates an d tru e color cap ability.

LED

Ligh t-Em ittin g Diod e. A sem icon d u ctor d iod e th at em its ligh t wh en a cu rren t is p assed th rou gh it.

LIF Low In sertion Force. A typ e of socket th at req u ires on ly a m in im u m of force to in sert a ch ip carrier. l i g h t p e n A h an d h eld in p u t d evice with a ligh t-sen sitive p robe or stylu s con n ected to th e com p u ter’s grap h ics ad ap ter board by a cable. Used for writin g or sketch in g on screen or as a p oin tin g d evice for m akin g selection s. Un like m ice, n ot wid ely su p p orted by software ap p lication s. lin e voltage

Th e AC voltage available at a stan d ard wall ou tlet, n om in ally 110-120v.

Li t h i u m Io n A p ortable system battery typ e th at is lon ger-lived th an eith er NiCad or NiMH tech n ologies, can n ot be overch arged , an d h old s a ch arge well wh en n ot in u se. Lith iu m Ion batteries are also ligh ter weigh t th an th e eith er NiCad or NiMH tech n ologies. Becau se of th ese su p erior featu res, Li-ion batteries h ave com e to be u sed in all bu t th e very low en d of th e p ortable system m arket. l o c a l a re a n e t w o rk (LAN) Th e con n ection of two or m ore com p u ters, u su ally via a n etwork ad ap ter card or NIC. l o c a l b u s A gen eric term u sed to d escribe a bu s th at is d irectly attach ed to a p rocessor an d wh ich op erates at th e p rocessor’s sp eed an d d ata tran sfer wid th . l o c a l e c h o A m od em featu re th at en ables th e m od em to sen d cop ies of keyboard com m an d s an d tran sm itted d ata to th e screen . W h en th e m od em is in com m an d m od e (n ot on lin e to an oth er system ), th e local ech o n orm ally is in voked th rou gh an ATE1 com m an d , wh ich cau ses th e m od em to d isp lay you r typ ed com m an d s. W h en th e m od em is on lin e to an oth er system , th e local ech o is in voked by an ATF0 com m an d , wh ich cau ses th e m od em to d isp lay th e d ata it tran sm its to th e rem ote system . l o g i c a l d ri v e A d rive as n am ed by a DOS d rive sp ecifier, su ch as C: or D:. Un d er DOS 3.3 or later, a sin gle p h ysical d rive can act as several logical d rives, each with its own sp ecifier. lo g ical u n it n u m ber

See LUN .

Glossary

l o ssl e ss c o m p re ssi o n A com p ression tech n iq u e th at p reserves all th e origin al in form ation in an im age or oth er d ata stru ctu res. l o ssy c o m p re ssi o n A com p ression tech n iq u e th at ach ieves op tim al d ata red u ction by d iscard in g red u n d an t an d u n n ecessary in form ation in an im age. l o st c l u st e rs Clu sters th at h ave been m arked accid en tally as “u n available” in th e FAT even th ou gh th ey d on ’t belon g to an y file listed in a d irectory. See also clusters an d allocation units. l o w -l e v e l f o rm a t t i n g Form attin g th at d ivid es tracks in to sectors on th e p latter su rfaces. Places sector-id en tifyin g in form ation before an d after each sector an d fills each sector with n u ll d ata (u su ally h ex F6). Sp ecifies th e sector in terleave an d m arks d efective tracks by p lacin g in valid ch ecksu m figu res in each sector on a d efective track. LP T p o rt LP X

A sem i-p rop rietary m oth erboard d esign u sed in m an y Low Profile or Slim lin e case system s. Becau se th ere is n o form al stan d ard , th ese are typ ically n ot in terch an geable between ven d ors an d are often d ifficu lt to fin d rep lacem en t p arts for rep air or u p grad e.

lu m in an ce LUN

LZH

Lin e Prin ter p ort, a com m on system abbreviation for a p arallel p rin ter p ort.

Measu re of brigh tn ess u su ally u sed in sp ecifyin g m on itor brigh tn ess.

Logical Un it Nu m ber. A n u m ber given to a d evice (a logical u n it) attach ed to a SCSI p h ysical u n it an d n ot d irectly to th e SCSI bu s. Alth ou gh as m an y as eigh t logical u n its can be attach ed to a sin gle p h ysical u n it, n orm ally a sin gle logical u n it is a bu ilt-in p art of a sin gle p h ysical u n it. A SCSI h ard d isk, for exam p le, h as a bu iltin SCSI bu s ad ap ter th at is assign ed a p h ysical u n it n u m ber or SCSI ID, an d th e con troller an d d rive p ortion s of th e h ard d isk are assign ed a LUN (u su ally 0). Also see PUN. Lem p el Zev W elch . A com p ression sch em e u sed in th e GIF grap h ic form at.

m a c h i n e a d d re ss

A h exad ecim al (h ex) location in m em ory.

m a c h i n e l a n g u a g e Hexad ecim al p rogram cod e th at a com p u ter can u n d erstan d an d execu te. It can be ou tp u t from assem bler or com p iler. m a g n e t i c d o m a i n A tin y segm en t of a track ju st large en ou gh to h old on e of th e m agn etic flu x reversals th at en cod e d ata on a d isk su rface. m a g n e t o -o p t i c a l re c o rd i n g An erasable op tical d isk record in g tech n iq u e th at u ses a laser beam to h eat p its on th e d isk su rface to th e p oin t at wh ich a m agn et can m ake flu x ch an ges. m a g n e t o re si st i v e A tech n ology origin ally d evelop ed by IBM an d com m on ly u sed for th e read elem en t of a read / write h ead on a h igh -d en sity m agn etic d isk. Based on th e p rin cip le th at th e resistan ce to electricity ch an ges in a m aterial wh en brou gh t in con tact with a m agn etic field , in th is case, th e read elem en t m aterial an d th e m agn etic bit. Su ch d rives u se a m agn etoresistive read sen sor for read in g an d a stan d ard in d u ctive elem en t for writin g. A m agn etoresistive read h ead is m ore sen sitive to m agn etic field s th an in d u ctive read h ead s.

1293

1294

Glossary

m a sk A p h otograp h ic m ap of th e circu its for a p articu lar layer of a sem icon d u ctor ch ip u sed in m an u factu rin g th e ch ip . m a st e r p a rt i t i o n b o o t se c t o r On h ard d isks, a on e-sector record th at gives essen tial in form ation abou t th e d isk an d tells th e startin g location s of th e variou s p artition s. Always th e first p h ysical sector of th e d isk. m a t h c o p ro c e sso r A p rocessin g ch ip d esign ed to q u ickly h an d le com p lex arith m etic com p u tation s in volvin g floatin g-p oin t arith m etic, offload in g th ese from th e m ain p rocessor. Origin ally con tain ed in a sep arate cop rocessor ch ip , startin g with th e 486 fam ily of p rocessors, In tel h as in corp orated th e m ath cop rocessor in to th e m ain p rocessors in wh at is called th e floatin g-p oin t u n it. MCA

Micro Ch an n el Arch itectu re. Develop ed by IBM for th e PS/ 2 lin e of com p u ters an d in trod u ced on Ap ril 2, 1987. Featu res in clu d e a 16- or 32-bit bu s wid th an d m u ltip le m aster con trol. By allowin g several p rocessors to arbitrate for resou rces on a sin gle bu s, th e MCA is op tim ized for m u ltitaskin g, m u ltip rocessor system s. Offers switch less con figu ration of ad ap ters, wh ich elim in ates on e of th e biggest h ead ach es of in stallin g old er ad ap ters.

MCGA Mu ltiColor Grap h ics Array. A typ e of PC vid eo d isp lay circu it in trod u ced by IBM on Ap ril 2, 1987, th at su p p orts text an d grap h ics. Text is su p p orted at a m axim u m resolu tion of 80×25 ch aracters in 16 colors with a ch aracter box of 8×16 p ixels. Grap h ics is su p p orted at a m axim u m resolu tion of 320×200 p ixels in 256 (from a p alette of 262,144) colors or 640×480 p ixels in two colors. Th e MCGA ou tp u ts an an alog sign al with a h orizon tal scan n in g freq u en cy of 31.5KHz, an d su p p orts an alog color or an alog m on och rom e d isp lays. MCI

Med ia Con trol In terface. A d evice-in d ep en d en t sp ecification for con trollin g m u ltim ed ia d evices an d files. MCI is a p art of th e m u ltim ed ia exten sion s an d offers a stan d ard in terface set of d evice con trol com m an d s. MCI com m an d s are u sed for au d io record in g an d p layback an d an im ation p layback. Device typ es in clu d e CD au d io, d igital au d io tap e p layers, scan n ers, MIDI seq u en cers, vid eotap e p layers or record ers, an d au d io d evices th at p lay d igitized waveform files.

MD A

Mon och rom e Disp lay Ad ap ter (also, MGA—Mon o Grap h ics Ad ap ter). A typ e of PC vid eo d isp lay ad ap ter in trod u ced by IBM on Au gu st 12, 1981, th at su p p orts text on ly. Text is su p p orted at a m axim u m resolu tion of 80×25 ch aracters in fou r colors with a ch aracter box of 9×14 p ixels. Colors, in th is case, in d icate black, wh ite, brigh t wh ite, an d u n d erlin ed . Grap h ics m od es are n ot su p p orted . Th e MDA ou tp u ts a d igital sign al with a h orizon tal scan n in g freq u en cy of 18.432KHz, an d su p p orts TTL m on och rom e d isp lays. Th e IBM MDA also in clu d ed a p arallel p rin ter p ort.

m e a n t i m e b e t w e e n f a i l u re m e a n t i m e t o re p a i r m ed iu m

See MTBF.

See MTTR.

Th e m agn etic coatin g or p latin g th at covers a d isk or tap e.

m e g a A m u ltip lier in d icatin g 1 m illion (1,000,000) of som e u n it. Abbreviated as m or M. W h en u sed to in d icate a n u m ber of bytes of m em ory storage, th e m u ltip lier d efin ition ch an ges to 1,048,576. On e m egabit, for exam p le, eq u als 1,000,000 bits, an d on e m egabyte eq u als 1,048,576 bytes.

Glossary

m e g a b y t e (M) m e m o ry

A u n it of in form ation storage eq u al to 1,048,576 bytes.

An y com p on en t in a com p u ter system th at stores in form ation for fu tu re u se.

m e m o ry c a c h i n g A service p rovid ed by extrem ely fast m em ory ch ip s th at keep s cop ies of th e m ost recen t m em ory accesses. W h en th e CPU m akes a su bseq u en t access, th e valu e is su p p lied by th e fast m em ory rath er th an by relatively slow system m em ory. m e m o ry -re si d e n t p ro g ra m A p rogram th at rem ain s in m em ory after it h as been load ed , con su m in g m em ory th at oth erwise m igh t be u sed by ap p lication software. m e n u so f t w a re Utility software th at m akes a com p u ter easier to u se by rep lacin g DOS com m an d s with a series of m en u selection s. MFM e n c o d i n g Mod ified Freq u en cy Mod u lation en cod in g. A m eth od of en cod in g d ata on th e su rface of a d isk. Th e cod in g of a bit of d ata varies by th e cod in g of th e p reced in g bit to p reserve clockin g in form ation . MH z

An abbreviation for m egah ertz, a u n it of m easu rem en t in d icatin g th e freq u en cy of on e m illion cycles p er secon d . On e h ertz (Hz) is eq u al to on e cycle p er secon d . Nam ed after Hein rich R. Hertz, a Germ an p h ysicist wh o first d etected electrom agn etic waves in 1883.

MI/ MIC Mod e In d icate/ Mod e In d icate Com m on . Also called forced or m anual originate. Provid ed for in stallation s in wh ich eq u ip m en t oth er th an th e m od em d oes th e d ialin g. In su ch in stallation s, th e m od em op erates in d u m b m od e (n o au to-d ial cap ability), yet m u st go off-h ook in origin ate m od e to con n ect with an swerin g m od em s. m i c ro (µ )

A p refix in d icatin g on e m illion th (1/ 1,000,000 or .000001) of som e u n it.

Mi c ro n A u n it of m easu rem en t eq u alin g on e m illion th of a m eter. Often u sed in m easu rin g th e size of circu its in ch ip m an u factu rin g p rocesses. Cu rren t state-of-th e-art ch ip fabrication bu ild s ch ip s with 0.25 m icron circu its. m i c ro p ro c e sso r A solid -state cen tral p rocessin g u n it m u ch like a com p u ter on a ch ip . An in tegrated circu it th at accep ts cod ed in stru ction s for execu tion . m i c ro se c o n d (µ s) secon d .

A u n it of tim e eq u al to on e m illion th (1/ 1,000,000 or .000001) of a

MID I Mu sical In stru m en t Digital In terface. An in terface an d file form at stan d ard for con n ectin g a m u sical in stru m en t to a m icrocom p u ter an d storin g m u sical in stru m en t d ata. Mu ltip le m u sical in stru m en ts can be d aisy-ch ain ed an d p layed sim u ltan eou sly with th e h elp of th e com p u ter an d related software. Th e variou s op eration s of th e in stru m en ts can be cap tu red , saved , ed ited , an d p layed back. A MIDI file con tain s n ote in form ation , tim in g (h ow lon g a n ote is h eld ), volu m e, an d in stru m en t typ e for as m an y as 16 ch an n els. Seq u en cer p rogram s are u sed to con trol MIDI fu n ction s su ch as record in g, p layback, an d ed itin g. MIDI files store on ly n ote in stru ction s an d n ot actu al sou n d d ata. m i l l i (m )

A p refix in d icatin g on e th ou san d th (1/ 1,000 or .001) of som e u n it.

m i l l i se c o n d (m s) secon d .

A u n it of tim e eq u al to on e th ou san d th (1/ 1,000 or .001) of a

1295

1296

Glossary

m i n i -t o w e r

A typ e of PC system case th at is sh orter th an a fu ll or m id -sized tower.

MIP S Million In stru ction s Per Secon d . Refers to th e average n u m ber of m ach in elan gu age in stru ction s a com p u ter can p erform or execu te in on e secon d . Becau se d ifferen t p rocessors can p erform d ifferen t fu n ction s in a sin gle in stru ction , MIPS sh ou ld be u sed on ly as a gen eral m easu re of p erform an ce am on g d ifferen t typ es of com p u ters. MMX An In tel p rocessor en h an cem en t th at ad d s 57 n ew in stru ction s d esign ed to im p rove m u ltim ed ia p erform an ce. MMX also im p lies a d ou blin g of th e in tern al L1 p rocessor cach e. m n e m o n i c An abbreviated n am e for som eth in g th at is u sed in a m an n er sim ilar to an acron ym . Com p u ter p rocessor in stru ction s are often abbreviated with a m n em on ic su ch as JMP (Ju m p ), CLR (Clear), STO (Store), INIT (In itialize). A m n em on ic n am e for an in stru ction or an op eration m akes it easy to rem em ber an d con ven ien t to u se. MNP

Microcom Networkin g Protocol. Asyn ch ron ou s error-con trol an d d ata-com p ression p rotocols d evelop ed by Microcom , In c., an d n ow in th e p u blic d om ain . En su res error-free tran sm ission th rou gh error d etection (CRC) an d retran sm ission of erred fram es. MNP Levels 1 th rou gh 4 cover error con trol an d h ave been in corp orated in to CCITT Recom m en d ation V.42. MNP Level 5 in clu d es d ata com p ression bu t is eclip sed in su p eriority by V.42bis, an in tern ation al stan d ard th at is m ore efficien t. Most h igh -sp eed m od em s will con n ect with MNP Level 5 if V.42bis is u n available.

MO

Magn eto-Op tical. MO d rives u se both m agn etic an d op tical storage p rop erties. MO tech n ology is erasable an d record able, as op p osed to CD-ROM (Read On ly) an d W ORM (W rite On ce) d rives. MO u ses laser an d m agn etic field tech n ology to record an d erase d ata.

Mo b i l e m o d u l e (MMO) A typ e of p rocessor p ackin g from In tel for m obile com p u ters con sistin g of a Pen tiu m or Pen tiu m II p rocessor in its TCP form , m ou n ted on a sm all d au gh terboard alon g with th e p ower su p p ly for th e p rocessor’s u n iq u e voltage req u irem en ts, th e system ’s Level 2 cach e m em ory, an d th e “North Brid ge” p art of th e m oth erboard ch ip set. m o d e m Mod u lator-d em od u lator. A d evice th at con verts electrical sign als from a com p u ter in to an au d io form tran sm ittable over telep h on e lin es, or vice versa. Mod u lates, or tran sform s, d igital sign als from a com p u ter in to th e an alog form th at can be carried su ccessfu lly on a p h on e lin e; also d em od u lates sign als received from th e p h on e lin e back to d igital sign als before p assin g th em to th e receivin g com p u ter. m odu le

An assem bly th at con tain s a com p lete circu it or su bcircu it.

Mo n o c h ro m e D i sp l a y Ad a p t e r MOS

See MDA.

Metal-Oxid e Sem icon d u ctor. Refers to th e th ree layers u sed in form in g th e gate stru ctu re of a field -effect tran sistor (FET). MOS circu its offer low-p ower d issip ation an d en able tran sistors to be jam m ed close togeth er before a critical h eat p roblem arises. PMOS, th e old est typ e of MOS circu it, is a silicon -gate P-ch an n el MOS p rocess th at u ses cu rren ts m ad e u p of p ositive ch arges. NMOS is a silicon -gate Nch an n el MOS p rocess th at u ses cu rren ts m ad e u p of n egative ch arges an d is at least twice as fast as PMOS. CMOS, Com p lem en tary MOS, is n early im m u n e to n oise,

Glossary

ru n s off alm ost an y p ower su p p ly, an d is an extrem ely low-p ower circu it tech n iq u e. m o t h e rb o a rd Th e m ain circu it board in th e com p u ter. Also called planar, system board, or backplane. m o u se An in p u t d evice in ven ted by Dou glas En gelbart of Stan ford Research Cen ter in 1963 an d p op u larized by Xerox in th e 1970s. A m ou se con sists of a roller ball an d a trackin g m ech an ism on th e u n d ersid e th at relays th e m ou se’s h orizon tal an d vertical p osition to th e com p u ter, allowin g p recise con trol of th e p oin ter location on th e screen . Th e top sid e featu res 2 or 3 bu tton s an d p ossibly a sm all wh eel u sed to select or click item s on screen . MP C A trad em arked abbreviation for Mu ltim ed ia Person al Com p u ter. Th e origin al MPC sp ecification was d evelop ed by Tan d y Corp oration an d Microsoft as th e m in im u m p latform cap able of ru n n in g m u ltim ed ia software. In th e su m m er of 1995, th e MPC Marketin g Cou n cil in trod u ced an u p grad ed MPC 3 stan d ard . Th e MPC 1 Sp ecification d efin es th e followin g m in im u m stan d ard req u irem en ts: a 386SX or 486 CPU; 2M RAM; 30M h ard d isk; VGA vid eo d isp lay; 8-bit d igital au d io su bsystem ; CD-ROM d rive; an d system s software com p atible with th e ap p lication s p rogram m in g in terfaces (APIs) of Microsoft W in d ows version 3.1 or later. Th e MPC 2 Sp ecification d efin es th e followin g m in im u m stan d ard req u irem en ts: 25MHz 486SX with 4M RAM; 160M h ard d isk; 16-bit sou n d card ; 65,536 color vid eo d isp lay; d ou ble-sp eed CD-ROM d rive; an d system s software com p atible with th e ap p lication s p rogram m in g in terfaces (APIs) of Microsoft W in d ows version 3.1 or later. Th e MPC 3 Sp ecification d efin es th e followin g m in im u m stan d ard req u irem en ts: 75MHz Pen tiu m with 8M RAM; 540M h ard d isk; 16-bit sou n d card ; 65,536 color vid eo d isp lay; q u ad sp eed CD-ROM d rive; OM-1-com p lian t MPEG-1 vid eo, an d system s software com p atible with th e ap p lication s p rogram m in g in terfaces (APIs) of Microsoft W in d ows version 3.1 an d DOS 6.0 or later. MP EG Motion Pictu re Exp erts Grou p . A workin g ISO com m ittee th at h as d efin ed stan d ard s for lossy d igital com p ression an d d ecom p ression of m otion vid eo/ au d io for u se in com p u ter system s. Also see lossy. Th e MPEG-1 stan d ard d elivers d ecom p ression d ata at 1.2 to 1.5M/ sec, allowin g CD p layers to p lay fu ll-m otion color m ovies at 30 fram es p er secon d . MPEG-1 com p resses at abou t a 50:1 ratio before im age d egrad ation occu rs, bu t com p ression ratios as h igh as 200:1 are attain able. MPEG-2 exten d s to th e h igh er d ata rates (2 to 15Mbp s) n eed ed for sign als d elivered from rem ote sou rces (su ch as broad cast, cable, or satellite). MPEG-2 is d esign ed to su p p ort a ran ge of p ictu re asp ect ratios, in clu d in g 4:3 an d 16:9. MPEG com p ression p rod u ces abou t a 50 p ercen t volu m e red u ction in file size. MP R

Th e Swed ish govern m en t stan d ard for m axim u m vid eo term in al rad iation . Th e cu rren t version is called MPR II.

MSD OS.SYS On e of th e DOS system files req u ired to boot th e m ach in e. Con tain s th e p rim ary DOS rou tin es. Load ed by IO.SYS, it in tu rn load s COMMAND.COM. MTBF Mean Tim e Between Failu re. A statistically d erived m easu re of th e p robable tim e a d evice will con tin u e to op erate before a h ard ware failu re occu rs, u su ally given in h ou rs. Becau se n o stan d ard tech n iq u e exists for m easu rin g MTBF, a d evice from on e m an u factu rer can be sign ifican tly m ore or sign ifican tly less reliable th an a d evice with th e sam e MTBF ratin g from an oth er m an u factu rer.

1297

1298

Glossary

MTTR Mean Tim e To Rep air. A m easu re of th e p robable tim e it will take a tech n ician to service or rep air a sp ecific d evice, u su ally given in h ou rs. Mu l t i Co l o r Gra p h i c s Arra y

See MCGA.

m u l t i m e d i a Th e in tegration of sou n d , grap h ic im ages, an im ation , m otion vid eo, an d text in on e en viron m en t on a com p u ter. It is a set of h ard ware an d software tech n ologies th at are rap id ly ch an gin g an d en h an cin g th e com p u tin g en viron m en t. m u l t i se ssi o n A term u sed in CD-ROM record in g to d escribe a record in g even t. Mu ltisession cap abilities allow d ata record in g on th e d isk at d ifferen t tim es in several record in g session s. Kod ak’s Ph oto CD is an exam p le of CD-R tech n ology. See also session (single or m ultisession). m u l t i t a sk

To ru n several p rogram s sim u ltan eou sly.

m u l t i t h re a d To con cu rren tly p rocess m ore th an on e m essage by an ap p lication p rogram . OS/ 2, W in d ows 95, an d W in d ows NT are exam p les of m u ltith read ed op eratin g system s. Each p rogram can start two or m ore th read s, wh ich carry ou t variou s in terrelated tasks with less overh ead th an two sep arate p rogram s wou ld req u ire. m u l t i u se r sy st e m A system in wh ich several com p u ter term in als sh are th e sam e cen tral p rocessin g u n it (CPU). n a n o (n ) A p refix in d icatin g on e billion th (1/ 1,000,000,000 or .000000001) of som e u n it. n a n o se c o n d (n s) A u n it of tim e eq u al to on e billion th (1/ 1,000,000,000 or .000000001) of a secon d . Ne t BEUI NetBIOS Exten d ed User In terface. A n etwork p rotocol u sed p rim arily by W in d ows NT an d m ost su itable for sm all p eer-to-p eer n etworks. Ne t BIOS Network Basic In p u t/ Ou tp u t System . A com m on ly u sed n etwork p rotocol origin ally d evelop ed by IBM an d Sytek for PC local area n etworks. NetBIOS p rovid es session an d tran sp ort services (layers 4 an d 5 of th e OSI m od el). n e t w o rk A system in wh ich a n u m ber of in d ep en d en t com p u ters are lin ked to sh are d ata an d p erip h erals, su ch as h ard d isks an d p rin ters. Ne t w o rk In t e rf a c e Ca rd (NIC)

An ad ap ter th at con n ects a PC to a n etwork.

n e t w o rk l a y e r In th e OSI referen ce m od el, th e layer th at switch es an d rou tes th e p ackets as n ecessary to get th em to th eir d estin ation s. Th is layer is resp on sible for ad d ressin g an d d eliverin g m essage p ackets. Ni Ca d Th e old est of th e th ree battery tech n ologies u sed in p ortable system s, n ickel cad m iu m batteries are rarely u sed in p ortable system s tod ay becau se of th eir sh orter life an d th eir sen sitivity to im p rop er ch argin g an d d isch argin g. See also NiMH an d Lithium Ion. Ni MH A battery tech n ology u sed in p ortable system s. Nickel Metal-Hyd rid e batteries h ave ap p roxim ately a 30% lon ger life th an NiCad s, are less sen sitive to th e m em ory effect cau sed by im p rop er ch argin g an d d isch argin g, an d d o n ot u se th e en viron m en tally d an gerou s su bstan ces fou n d in NiCad s. Newer Lith iu m Ion (Li-ion ) batteries are far su p erior.

Glossary

NLX

A n ew low-p rofile m oth erboard form factor stan d ard th at is basically an im p roved version of th e sem ip rop rietary LPX d esign . Design ed to accom m od ate larger p rocessor an d m em ory form factors an d in corp orate n ewer bu s tech n ologies su ch as AGP an d USB. Besid es d esign im p rovem en ts, it is fu lly stan d ard ized , wh ich m ean s you sh ou ld be able to rep lace on e NLX board with an oth er from a d ifferen t m an u factu rer, som eth in g th at was n ot n orm ally p ossible with LPX.

n o n i n t e rl a c e d m o n i t o r A d esirable m on itor d esign wh ere th e electron beam sweep s th e screen in lin es from top to bottom , on e lin e after th e oth er, com p letin g th e en tire screen in on e p ass. n o n v o l a t i l e m e m o ry (NVRAM) Ran d om -access m em ory wh ose d ata is retain ed wh en p ower is tu rn ed off. Som etim es NVRAM is retain ed with ou t an y p ower wh atsoever, as in EEPROM or flash m em ory d evices. In oth er cases, th e m em ory is m ain tain ed by a sm all battery. NVRAM th at is battery m ain tain ed is som etim es also called CMOS m em ory. CMOS NV RAM is u sed in IBM-com p atible system s to store con figu ration in form ation . True NV RAM often is u sed in in telligen t m od em s to store a u ser-d efin ed d efau lt con figu ration load ed in to n orm al m od em RAM at p ower-u p . n o n v o l a t i l e RAM d i sk A RAM d isk p owered by a battery su p p ly so th at it con tin u es to h old its d ata d u rin g a p ower ou tage. No rt h Bri d g e Th e In tel term for th e m ain p ortion of th e m oth erboard ch ip set th at in corp orates th e in terface between th e p rocessor an d th e rest of th e m oth erboard . Th e North Brid ge con tain s th e cach e, m ain m em ory, an d AGP con trollers as well as th e in terface between th e h igh -sp eed (n orm ally 66MHz or 100MHz) p rocessor bu s an d th e 33MHz PCI (Perip h eral Com p on en t In tercon n ect) or 66MHz AGP (Accelerated Grap h ics Port) bu ses. See also chipset an d South Bridge. n o t ebo o k co m p u t er n otebook.

A very sm all p erson al com p u ter ap p roxim ately th e size of a

NTSC Th e Nation al Television Stan d ard s Com m ittee, wh ich govern s th e stan d ard for television an d vid eo p layback an d record in g in th e Un ited States. Th e NTSC was origin ally organ ized in 1941 wh en TV broad castin g first began on a wid e scale in black an d wh ite, an d th e form at was revised in 1953 for color. Th e NTSC form at h as 525 scan lin es, a field freq u en cy of 60Hz, a broad cast ban d wid th of 4MHz, lin e freq u en cy of 15.75KHz, fram e freq u en cy of 1/ 30 of a secon d , an d a color su bcarrier freq u en cy of 3.58MHz. It is an in terlaced sign al, wh ich m ean s th at it scan s every oth er lin e each tim e th e screen is refresh ed . Th e sign al is gen erated as a com p osite of red , green , an d blu e sign als for color an d in clu d es an FM freq u en cy for au d io an d a sign al for stereo. See also PAL an d SECAM, wh ich are in com p atible system s u sed in Eu rop e. NTSC is also called com posite video. n u l l m o d e m A serial cable wired so th at two d ata term in al eq u ip m en t (DTE) d evices, su ch as p erson al com p u ters, or two d ata com m u n ication eq u ip m en t (DCE) d evices, su ch as m od em s or m ice, can be con n ected . Also som etim es called a m odem elim inator or a Lap Lin k cable. To m ake a n u ll-m od em cable with DB-25 con n ectors, you wire th ese p in s togeth er: 1-1, 2-3, 3-2, 4-5, 5-4, 6-8-20, 20-8-6, an d 7-7. n u m e ri c c o p ro c e sso r

See m ath coprocessor.

1299

1300

Glossary

NVRAM Non volatile Ran d om Access Mem ory. Mem ory th at retain s d ata with ou t p ower. Flash m em ory an d battery-backed CMOS RAM are exam p les of NVRAM. o b je c t h i e ra rc h y Occu rs in a grap h ical p rogram wh en two or m ore objects are lin ked an d on e object’s m ovem en t is d ep en d en t on th e oth er object. Th is is kn own as a parent-child hierarchy. In an exam p le u sin g a h u m an figu re, th e fin gers wou ld be ch ild objects to th e h an d , wh ich is a ch ild object to th e arm , wh ich is a ch ild to th e sh ou ld er, an d so on . Object h ierarch y p rovid es m u ch con trol for an an im ator in m ovin g com p lex figu res. OCR

Op tical Ch aracter Recogn ition . An in form ation -p rocessin g tech n ology th at con verts h u m an -read able text in to com p u ter d ata. Usu ally a scan n er is u sed to read th e text on a p age, an d OCR software con verts th e im ages to ch aracters.

OD I

Op en Data-lin k In terface. A d evice d river stan d ard from Novell th at allows you to ru n m u ltip le p rotocols on th e sam e n etwork ad ap ter card . ODI ad d s fu n ction ality to Novell’s NetW are an d n etwork com p u tin g en viron m en ts by su p p ortin g m u ltip le p rotocols an d d rivers.

OEM

Origin al Eq u ip m en t Man u factu rer. An y m an u factu rer th at sells its p rod u ct to a reseller. Usu ally refers to th e origin al m an u factu rer of a p articu lar d evice or com p on en t. Most Com p aq h ard d isks, for exam p le, are m ad e by Con n er Perip h erals, wh o is con sid ered th e OEM.

OLE Object Lin kin g an d Em bed d in g. An en h an cem en t to th e origin al Dyn am ic Data Exch an ge (DDE) p rotocol th at allows you to em bed or lin k d ata created in on e ap p lication in a d ocu m en t created in an oth er ap p lication an d su bseq u en tly ed it th at d ata d irectly from th e fin al d ocu m en t. o n l i n e f a l l b a c k A featu re th at en ables h igh -sp eed error-con trol m od em s to m on itor lin e q u ality an d fall back to th e n ext lower sp eed if lin e q u ality d egrad es. Som e m od em s fall forward as lin e q u ality im p roves. o p e n a rc h i t e c t u re A system d esign in wh ich th e sp ecification s are m ad e p u blic to en cou rage th ird -p arty ven d ors to d evelop ad d -on p rod u cts. Th e PC is a tru e op en arch itectu re system , bu t th e Macin tosh is p rop rietary. o p e ra t i n g sy st e m (OS) A collection of p rogram s for op eratin g th e com p u ter. Op eratin g system s p erform h ou sekeep in g tasks su ch as in p u t an d ou tp u t between th e com p u ter an d p erip h erals an d accep tin g an d in terp retin g in form ation from th e keyboard . DOS an d OS/ 2 are exam p les of p op u lar OSs. o p t i c a l d i sk A d isk th at en cod es d ata as a series of reflective p its th at are read (an d som etim es written ) by a laser beam . Ora n g e Bo o k Th e stan d ard for record able com p act d iscs (like CD-ROM, bu t record able in stead of read -on ly). Record able com p act d iscs are called CD-R an d are becom in g p op u lar with th e wid esp read u se of m u ltim ed ia. Part of th e Oran ge Book stan d ard d efin es rewritable Magn eto-Op tical d isks an d an oth er section d efin es op tical W rite On ce Read Man y (W ORM) d isks. o ri g i n a t e m o d e A state in wh ich th e m od em tran sm its at th e p red efin ed low freq u en cy of th e com m u n ication s ch an n el an d receives at th e h igh freq u en cy. Th e tran sm it/ receive freq u en cies are th e reverse of th e called m od em , wh ich is in an swer m od e. See also answer m ode.

Glossary

OS/ 2

An op eratin g system origin ally d evelop ed th rou gh a join t effort by IBM an d Microsoft Corp oration an d later by IBM alon e. Origin ally released in 1987, OS/ 2 is a 32-bit op eratin g system d esign ed to ru n on com p u ters u sin g th e In tel 386 or later m icrop rocessors. Th e OS/ 2 W orkp lace Sh ell, an in tegral p art of th e system , is a grap h ical in terface sim ilar to Microsoft W in d ows an d th e Ap p le Macin tosh system .

OSI (Op e n Sy st e m s In t e rc o n n e c t i o n ) Re f e re n c e Mo d e l Develop ed by th e In tern ation al Organ ization for Stan d ard ization (abbreviated as th e ISO) in th e 1980s, th e OSI m od el sp lits a com p u ter’s n etworkin g stack in to seven d iscrete layers. Each layer p rovid es sp ecific services to th e layers above an d below it. o u t p u t In form ation p rocessed by th e com p u ter, or th e act of sen d in g th at in form ation to a m ass storage d evice su ch as a vid eo d isp lay, a p rin ter, or a m od em . o v e r-c l o c k i n g Th e p rocess of ru n n in g a p rocessor at a sp eed faster th an th e officially m arked sp eed by u sin g a h igh er clock m u ltip lier or faster bu s sp eed . Not recom m en d ed or en d orsed by p rocessor m an u factu rers. See also clock m ultiplier. Ov e rD ri v e o v e rl a y

An In tel trad em ark n am e for its lin e of u p grad e p rocessors.

Part of a p rogram th at is load ed in to m em ory on ly wh en it is req u ired .

o v e rru n A situ ation in wh ich d ata m oves from on e d evice faster th an a secon d d evice can accep t it. o v e rsc a n n i n g A tech n iq u e u sed in con su m er d isp lay p rod u cts th at exten d s th e d eflection of a CRT’s electron beam beyon d th e p h ysical bou n d aries of th e screen to en su re th at im ages will always fill th e d isp lay area. See also underscanning. o v e rw ri t e p ack ag e

To write d ata on top of existin g d ata, th u s erasin g th e existin g d ata. A d evice th at in clu d es a ch ip m ou n ted on a carrier an d sealed .

p a i ri n g Com bin in g p rocessor in stru ction s for op tim al execu tion on su p erscalar p rocessors. P AL 1) Ph ase Altern atin g Lin e system . In ven ted in 1961, a system of TV broad castin g u sed in En glan d an d oth er Eu rop ean cou n tries (excep t Fran ce). PAL’s im age form at is 4:3, 625 lin es, 50Hz, an d 4MHz vid eo ban d wid th with a total 8MHz of vid eo ch an n el wid th . W ith its 625-lin e p ictu re d elivered at 25 fram es p er secon d , PAL p rovid es a better im age an d an im p roved color tran sm ission over th e NTSC system u sed in North Am erica. 2) PAL also stan d s for Program m able Array Logic, a typ e of ch ip th at h as logic gates sp ecified by a d evice p rogram m er. p a l m t o p c o m p u t e r A com p u ter system sm aller th an a n otebook th at is d esign ed so th at it can be h eld in on e h an d wh ile bein g op erated by th e oth er. Man y are n ow called PDAs or personal digital assistants. p a ra l l e l A m eth od of tran sferrin g d ata ch aracters in wh ich th e bits travel d own p arallel electrical p ath s sim u ltan eou sly—for exam p le, eigh t p ath s for 8-bit ch aracters. Data is stored in com p u ters in p arallel form bu t m ay be con verted to serial form for certain op eration s.

1301

1302

Glossary

p a ri t y A m eth od of error ch eckin g in wh ich an extra bit is sen t to th e receivin g d evice to in d icate wh eth er an even or od d n u m ber of bin ary 1 bits were tran sm itted . Th e receivin g u n it com p ares th e received in form ation with th is bit an d can obtain a reason able ju d gm en t abou t th e valid ity of th e ch aracter. Th e sam e typ e of p arity (even or od d ) m u st be u sed by two com m u n icatin g com p u ters, or both m ay om it p arity. W h en p arity is u sed , a p arity bit is ad d ed to each tran sm itted ch aracter. Th e bit’s valu e is 0 or 1, to m ake th e total n u m ber of 1s in th e ch aracter even or od d , d ep en d in g on wh ich typ e of p arity is u sed . p a rk p ro g ra m A p rogram th at execu tes a seek to th e h igh est cylin d er or ju st p ast th e h igh est cylin d er of a d rive so th at th e p oten tial of d ata loss is m in im ized if th e d rive is m oved . p a rt i t i o n A section of a h ard d isk d evoted to a p articu lar op eratin g system . Most h ard d isks h ave on ly on e p artition , d evoted to DOS. A h ard d isk can h ave as m an y as fou r p artition s, each occu p ied by a d ifferen t op eratin g system . DOS v3.3 or later can occu p y two of th ese fou r p artition s. P a sc a l A h igh -level p rogram m in g lan gu age n am ed for th e Fren ch m ath em atician Blaise Pascal (1623-1662). Develop ed in th e early 1970s by Niklau s W irth for teach in g p rogram m in g an d d esign ed to su p p ort th e con cep ts of stru ctu red p rogram m in g. p a ssi v e m a t ri x

An oth er n am e for dual scan display typ e LCDs.

P C Ca rd (P CMCIA) Person al Com p u ter Mem ory Card In tern ation al Association . A cred it card -sized exp an sion ad ap ter for n otebook an d lap top PCs. PC Card is th e official PCMCIA trad em ark; h owever, both PC Card an d PCMCIA card are u sed to refer to th ese stan d ard s. PCMCIA card s are rem ovable m od u les th at can h old n u m erou s typ es of d evices in clu d in g m em ory, m od em s, fax/ m od em s, rad io tran sceivers, n etwork ad ap ters, solid state d isks, an d h ard d isks. P CI Perip h eral Com p on en t In tercon n ect. A stan d ard bu s sp ecification in itially d evelop ed by In tel th at byp asses th e stan d ard ISA I/ O bu s an d u ses th e system bu s to in crease th e bu s clock sp eed an d take fu ll ad van tage of th e CPU’s d ata p ath . P CL Prin ter Con trol Lan gu age. Develop ed by Hewlett-Packard in 1984 as a lan gu age for th e HP LaserJet p rin ter. PCL is n ow th e d e facto in d u stry stan d ard for PC p rin tin g. PCL d efin es a stan d ard set of com m an d s, en ablin g ap p lication s to com m u n icate with HP or HP-com p atible p rin ters, an d is su p p orted by virtu ally all p rin ter m an u factu rers. p e e r-t o -p e e r A typ e of n etwork in wh ich an y com p u ter can act as both a server (by p rovid in g access to its resou rces to oth er com p u ters) an d a clien t (by accessin g sh ared resou rces from oth er com p u ters). P EL See pixel. P e n t i u m An In tel m icrop rocessor with 32-bit registers, a 64-bit d ata bu s, an d a 32-bit ad d ress bu s. Th e Pen tiu m h as a bu ilt-in Level 1 cach e th at is segm en ted in to a sep arate 8K cach e for cod e an d an oth er 8K cach e for d ata. Th e Pen tiu m in clu d es an FPU (floatin g-p oin t u n it) or m ath cop rocessor. Th e Pen tiu m is backward -com p atible with th e 486 an d can op erate in real, p rotected virtu al, an d virtu al real m od es.

Glossary

P e n t i u m II An In tel sixth -gen eration p rocessor sim ilar to th e Pen tiu m Pro, bu t with MMX cap abilities an d sin gle ed ge con tact (SEC) cartrid ge p ackagin g tech n ology. P e n t i u m P ro An In tel sixth -gen eration p rocessor with 32-bit registers, a 64-bit d ata bu s, an d a 36-bit ad d ress bu s. Th e Pen tiu m Pro h as th e sam e segm en ted Level 1 cach e as th e Pen tiu m bu t also in clu d es a 256K, 512K, or 1M of Level 2 cach e on sep arate d ie(s) in sid e th e p rocessor p ackage. Th e Pen tiu m Pro in clu d es a FPU (floatin g-p oin t u n it) or m ath cop rocessor. Th e Pen tiu m Pro is backward -com p atible with th e Pen tiu m an d can op erate in real, p rotected , an d virtu al real m od es. p e ri p h e ra l An y p iece of eq u ip m en t u sed in com p u ter system s th at is an attach m en t to th e com p u ter. Disk d rives, term in als, an d p rin ters are all exam p les of p erip h erals. p e rsi st e n c e In a m on itor, th e q u ality of th e p h osp h or ch em ical th at in d icates h ow lon g th e glow cau sed by th e electron s strikin g th e p h osp h or will rem ain on screen . P GA

1) Pin -Grid Array. A ch ip p ackage th at h as a large n u m ber of p in s on th e bottom d esign ed for socket m ou n tin g. 2) Also a Profession al Grap h ics Ad ap ter, a lim ited p rod u ction , h igh -resolu tion grap h ics card for XT an d AT system s from IBM.

P h o t o CD A tech n ology d evelop ed by Eastm an Kod ak an d Ph ilip s th at stores p h otograp h ic im ages on a CD-R record able com p act d isc. Im ages stored on th e Ph oto CD m ay h ave resolu tion s as h igh as 2,048×3,072 p ixels. Up to 100 tru e-color im ages (24-bit color) can be stored on on e d isk. Ph oto CD im ages are created by scan n in g film an d d igitally record in g th e im ages on com p act d iscs (CDs). Th e d igitized im ages are in d exed (given a 4-d igit cod e), an d th u m bn ails of each im age on th e d isc are sh own on th e fron t of th e case alon g with its in d ex n u m ber. Mu ltisession cap ability allows several rolls of film to be ad d ed to a sin gle d isk on d ifferen t occasion s. p h o t o l i t h o g ra p h y Th e p h otograp h ic p rocess u sed in electron ic ch ip m an u factu rin g th at creates tran sistors an d circu it an d sign al p ath ways in sem icon d u ctors by d ep ositin g d ifferen t layers of variou s m aterials on th e ch ip . p h o t o re si st A ch em ical u sed to coat a silicon wafer in th e sem icon d u ctor m an u factu rin g p rocess th at m akes th e silicon sen sitive to ligh t for p h otolith ograp h y. p h y si c a l d ri v e A sin gle d isk d rive. DOS d efin es logical d rives, wh ich are given a sp ecifier, su ch as C: or D:. A sin gle p h ysical d rive m ay be d ivid ed in to m u ltip le logical d rives. Con versely, sp ecial software can sp an a sin gle logical d rive across two p h ysical d rives. p h y si c a l u n i t n u m b e r

See PUN.

P IF Program In form ation File. A file th at con tain s in form ation abou t a n on -W in d ows ap p lication sp ecifyin g op tim u m settin gs for ru n n in g th e p rogram u n d er W in d ows 3.x. Th ese are called property sheets in W in d ows 95. pin

1) Th e lead on a con n ector, ch ip , m od u le or d evice. 2) Person al Id en tification Nu m ber. A p erson al p assword u sed for id en tification p u rp oses.

p in co m p at ible

Ch ip s h avin g th e sam e p in ou t fu n ction s.

p i n o u t A listin g of wh ich p in s h ave wh at fu n ction s on a ch ip , socket, slot, or oth er con n ector.

1303

1304

Glossary

P IO m o d e Program m ed In p u t/ Ou tp u t m od e. Th e stan d ard d ata tran sfer m od es u sed by IDE d rives th at u se th e p rocessor’s registers for d ata tran sfer. Th is is in con trast with DMA m od es, wh ich tran sfer d ata d irectly between m ain m em ory an d th e d evice. Th e slowest PIO m od e is 0 an d th e fastest cu rren t m od e is m od e 4. p ip elin e p ix el

A p ath for in stru ction s or d ata to follow.

A m n em on ic term m ean in g p ictu re elem en t. An y of th e tin y elem en ts th at form a p ictu re on a vid eo d isp lay screen . Also called a pel.

p l a n a r b o a rd

A term eq u ivalen t to m otherboard, u sed by IBM in som e of its literatu re.

p l a t e d m e d i a Hard d isk p latters p lated with a form of th in m etal film m ed iu m on wh ich d ata is record ed . p l a t t e r A d isk con tain ed in a h ard d isk d rive. Most d rives h ave two or m ore p latters, each with d ata record ed on both sid es. P LCC Plastic Lead ed -Ch ip Carrier. A p op u lar ch ip -carrier p ackage with J-lead s arou n d th e p erim eter of th e p ackage. P l u g a n d P l a y (P n P ) A h ard ware an d software sp ecification d evelop ed by In tel th at allows a Pn P system an d Pn P ad ap ter card s to au tom atically con figu re th em selves. Pn P card s are free from switch es an d ju m p ers an d are con figu red via th e Pn P BIOS in th e h ost system , or via su p p lied p rogram s for n on -Pn P system s. p o l l i n g A com m u n ication s tech n iq u e th at d eterm in es wh en a d evice is read y to sen d d ata. Th e system con tin u ally in terrogates p olled d evices in a rou n d -robin seq u en ce. If a d evice h as d ata to sen d , it sen d s back an ackn owled gm en t an d th e tran sm ission begin s. Con trasts with in terru p t-d riven com m u n ication s, in wh ich th e d evice gen erates a sign al to in terru p t th e system wh en it h as d ata to sen d . p o rt

Plu g or socket th at en ables an extern al d evice su ch as a p rin ter to be attach ed to th e ad ap ter card in th e com p u ter. Also a logical ad d ress u sed by a m icrop rocessor for com m u n ication s between it an d variou s d evices.

p o rt a d d re ss On e of a system of ad d resses u sed by th e com p u ter to access d evices su ch as d isk d rives or p rin ter p orts. You m ay n eed to sp ecify an u n u sed p ort ad d ress wh en in stallin g an y ad ap ter board s in a system u n it. p o rt re p l i c a t o r For m obile com p u ters, a d evice th at p lu gs in to th e lap top an d p rovid es all of th e p orts for con n ectin g extern al d evices. Th e ad van tage of u sin g a p ort rep licator is th at th e extern al d evices can be left con n ected to th e rep licator an d th e m obile com p u ter con n ected to th em all at on ce by con n ectin g to th e rep licator, rath er th an con n ectin g to each in d ivid u al d evice. A p ort rep licator d iffers from a d ockin g station in th at th e latter can p rovid e ad d ition al d rive bays an d exp an sion slots n ot fou n d in p ort rep licators. p o rt a b l e c o m p u t e r A com p u ter system sm aller th an a tran sp ortable system bu t larger th an a lap top system . Most p ortable system s con form to th e lu n ch box style p op u larized by Com p aq or th e briefcase style p op u larized by IBM, each with a fold d own (rem ovable) keyboard an d bu ilt-in d isp lay. Th ese system s ch aracteristically ru n on AC p ower an d n ot on batteries, in clu d e several exp an sion slots, an d can be as p owerfu l as fu ll d esktop system s.

Glossary

P OS

Program m able Op tion Select. Th e Micro Ch an n el Arch itectu re’s POS elim in ates switch es an d ju m p ers from th e system board an d ad ap ters by rep lacin g th em with p rogram m able registers. Au tom atic con figu ration rou tin es store th e POS d ata in a battery-p owered CMOS m em ory for system con figu ration an d op eration s. Th e con figu ration u tilities rely on ad ap ter d escrip tion files (ADF) th at con tain th e setu p d ata for each card .

P OST Power-On Self Test. A series of tests ru n by th e com p u ter at p ower-on . Most com p u ters scan an d test m an y of th eir circu its an d sou n d a beep from th e in tern al sp eaker if th is in itial test in d icates p rop er system p erform an ce. P o st Sc ri p t A p age-d escrip tion lan gu age d evelop ed p rim arily by Joh n W arn ock of Ad obe System s for con vertin g an d m ovin g d ata to th e laser-p rin ted p age. In stead of u sin g th e stan d ard m eth od of tran sm ittin g grap h ics or ch aracter in form ation to a p rin ter, tellin g it wh ere to p lace d ots on e-by-on e on a p age, PostScrip t p rovid es a way for th e laser p rin ter to in terp ret m ath em atically a fu ll p age of sh ap es an d cu rves. P OTS

Plain Old Telep h on e Service. Stan d ard an alog telep h on e service.

p o w e r m a n a g e m e n t System s u sed in itially in m obile com p u ters (an d n ow also u sed in d esktop system s) to d ecrease p ower con su m p tion by tu rn in g off or slowin g d own d evices d u rin g p eriod s of in activity. See APM. p o w e r su p p l y An electrical/ electron ic circu it th at su p p lies all op eratin g voltage an d cu rren t to th e com p u ter system . P P GA Plastic Pin Grid Array. A ch ip -p ackagin g form factor u sed by In tel as an altern ative to trad ition al ceram ic p ackagin g. PPP

Poin t-to-Poin t Protocol. A p rotocol th at allows a com p u ter to u se th e In tern et with a stan d ard telep h on e lin e an d a h igh -sp eed m od em . PPP is a n ew stan d ard th at rep laces SLIP. PPP is less com m on th an SLIP; h owever, it is in creasin g in p op u larity.

p re c o m p e n sa t i o n A d ata write m od ification req u ired by som e old er d rives on th e in n er cylin d ers to com p en sate for th e h igh er d en sity of d ata on th e (sm aller) in n er cylin d ers. p ri m a ry p a rt i t i o n partition. p ro c e sso r

An ord in ary, sin gle-volu m e bootable p artition . See also extended

See m icroprocessor.

p ro c e sso r sp e e d Th e clock rate at wh ich a m icrop rocessor p rocesses d ata. A typ ical Pen tiu m PC, for exam p le, op erates at 200MHz (200 m illion cycles p er secon d ). p ro g ra m A set of in stru ction s or step s tellin g th e com p u ter h ow to h an d le a p roblem or task. P ROM Program m able Read -On ly Mem ory. A typ e of m em ory ch ip th at can be p rogram m ed to store in form ation p erm an en tly—in form ation th at can n ot be erased .

1305

1306

Glossary

p ro p ri e t a ry An yth in g in ven ted by on e com p an y an d th at u ses com p on en ts on ly available from th at on e com p an y. Esp ecially ap p lies to cases in wh ich th e in ven tin g com p an y goes to len gth s to h id e th e sp ecification s of th e n ew in ven tion or to p reven t oth er m an u factu rers from m akin g sim ilar or com p atible item s. Th e op p osite of standard or open architecture. Com p u ters with n on stan d ard com p on en ts th at are available on ly from th e origin al m an u factu rer, su ch as Ap p le Macin tosh system s, are kn own as p rop rietary. p ro t e c t e d m o d e A m od e available in all In tel an d com p atible p rocessors excep t th e first-gen eration 8086 an d 8088. In th is m od e, m em ory ad d ressin g is exten d ed beyon d th e 1M lim its of th e 8088 an d real m od e, an d restricted p rotection levels can be set to trap software crash es an d con trol th e system . p ro t o c o l A system of ru les an d p roced u res govern in g com m u n ication s between two or m ore d evices. Protocols vary, bu t com m u n icatin g d evices m u st follow th e sam e p rotocol to exch an ge d ata. Th e d ata form at, read in ess to receive or sen d , error d etection , an d error correction are som e of th e op eration s th at m ay be d efin ed in p rotocols. P S/ 2 m o u se A m ou se d esign ed to p lu g in to a d ed icated m ou se p ort (a rou n d , 6-p in DIN con n ector) on th e m oth erboard , rath er th an p lu g in to a serial p ort. Th e n am e com es from th e fact th at th is p ort was first in trod u ced on th e IBM PS/ 2 system s. P UN

Ph ysical Un it Nu m ber. A term u sed to d escribe a d evice attach ed d irectly to th e SCSI bu s. Also kn own as a SCSI ID. As m an y as eigh t SCSI d evices can be attach ed to a sin gle SCSI bu s, an d each m u st h ave a u n iq u e PUN or ID assign ed from 7 to 0. Norm ally, th e SCSI h ost ad ap ter is assign ed th e h igh est-p riority ID, wh ich is 7. A bootable h ard d isk is assign ed an ID of 0, an d oth er n on bootable d rives are assign ed h igh er p riorities.

QAM

Qu ad ratu re Am p litu d e Mod u lation . A m od u lation tech n iq u e u sed by h igh -sp eed m od em s th at com bin es both p h ase an d am p litu d e m od u lation . Th is tech n iq u e en ables m u ltip le bits to be en cod ed in a sin gle tim e in terval.

QIC Qu arter-In ch Com m ittee. An in d u stry association th at sets h ard ware an d software stan d ard s for tap e-backu p u n its th at u se q u arter-in ch -wid e tap es. QW ERTY k e y b o a rd Th e stan d ard typ ewriter or com p u ter keyboard , with th e ch aracters Q, W , E, R, T, an d Y on th e top row of alp h a keys. Becau se of th e h ap h azard p lacem en t of ch aracters, th is keyboard can h in d er fast typ in g. ra i l s

Plastic strip s attach ed to th e sid es of d isk d rives m ou n ted in IBM ATs an d com p atibles so th at th e d rives can slid e in to p lace. Th ese rails fit in to ch an n els in th e sid e of each d isk d rive bay p osition .

RAM

Ran d om -Access Mem ory. All m em ory accessible at an y in stan t (ran d om ly) by a m icrop rocessor.

RAM d i sk A “p h an tom d isk d rive” in wh ich a section of system m em ory (RAM) is set asid e to h old d ata, ju st as th ou gh it were a n u m ber of d isk sectors. To DOS, a RAM d isk looks like an d fu n ction s like an y oth er d rive. RAMBUS D y n a m i c RAM

See RDRAM.

Glossary

ra n d o m -a c c e ss f i l e A file in wh ich all d ata elem en ts (or record s) are of eq u al len gth an d written in th e file en d to en d , with ou t d elim itin g ch aracters between . An y elem en t (or record ) in th e file can be fou n d d irectly by calcu latin g th e record ’s offset in th e file. ra n d o m -a c c e ss m e m o ry

See RAM.

ra st e r A p attern of h orizon tal scan n in g lin es n orm ally on a com p u ter m on itor. An electrom agn etic field cau ses th e beam of th e m on itor’s tu be to illu m in ate th e correct d ots to p rod u ce th e req u ired ch aracters. ra st e r g ra p h i c s A tech n iq u e for rep resen tin g a p ictu re im age as a m atrix of d ots. It is th e d igital cou n terp art of th e an alog m eth od u sed in TV. Th ere are several raster grap h ics stan d ard s. RCA ja c k Also called a phono connector. A p lu g an d socket for a two-wire coaxial cable u sed to con n ect au d io an d vid eo com p on en ts. Th e p lu g is a 1/ 8-in ch th ick p ron g th at sticks ou t 5/ 16-in ch from th e m id d le of a cylin d er. RD RAM Ram bu s DRAM. A h igh -sp eed d yn am ic RAM tech n ology d evelop ed by Ram bu s, In c., wh ich will be su p p orted by In tel’s 1999 an d later m oth erboard ch ip sets. RDRAM tran sfers d ata at 1G/ sec or faster, wh ich is sign ifican tly faster th an SDRAM an d oth er tech n ologies an d wh ich will be able to keep u p with fu tu regen eration h igh -sp eed p rocessors. Mem ory m od u les with RDRAM ch ip s are called RIMMs (Ram bu s In lin e Mem ory Mod u les). Ram bu s licen ses its tech n ology to oth er sem icon d u ctor com p an ies, wh o m an u factu re th e ch ip s an d RIMMs. re a d / w ri t e h e a d

A tin y m agn et th at read s an d writes d ata on a d isk track.

re a d -o n l y f i l e A file wh ose attribu te settin g in th e file’s d irectory en try tells DOS n ot to allow software to write in to or over th e file. re a d -o n l y m e m o ry

See ROM.

re a l m o d e A m od e available in all In tel 8086-com p atible p rocessors th at en ables com p atibility with th e origin al 8086. In th is m od e, m em ory ad d ressin g is lim ited to 1M. re a l t i m e Th e actu al tim e in wh ich a p rogram or even t takes p lace. In com p u tin g, real tim e refers to an op eratin g m od e u n d er wh ich d ata is received an d p rocessed an d th e resu lts retu rn ed so q u ickly th at th e p rocess ap p ears in stan tan eou s to th e u ser. Th e term is also u sed to d escribe th e p rocess of sim u ltan eou s d igitization an d com p ression of au d io an d vid eo in form ation . re b o o t

Th e p rocess of restartin g a com p u ter an d reload in g th e op eratin g system .

Re d Bo o k More com m on ly kn own as Com p act Disc-Digital Au d io (CD-DA), an d is on e of fou r com p act d isc stan d ard s. Red Book got its n am e from th e color of th e m an u al u sed to d escribe th e CD Au d io sp ecification s. Th e Red Book au d io stan d ard req u ires th at d igital au d io be sam p led at a 44.1KHz sam p le rate u sin g 16 bits for each sam p le. Th is is th e stan d ard u sed by au d io CDs an d m an y CD-ROMs. See also CD-A an d CD-DA. re f re sh c y c l e A cycle in wh ich th e com p u ter accesses all m em ory location s stored by DRAM ch ip s so th at th e in form ation rem ain s in tact. DRAM ch ip s m u st be accessed several tim es a secon d , or else th e in form ation fad es.

1307

1308

Glossary

re f re sh ra t e

An oth er term for th e vertical scan freq u en cy of m on itors.

re g i st e r Storage area in m em ory h avin g a sp ecified storage cap acity, su ch as a bit, a byte, or a com p u ter word , an d in ten d ed for a sp ecial p u rp ose. Re g i st ry Th e system con figu ration files u sed by W in d ows 9x an d W in d ows NT to store settin gs abou t in stalled h ard ware an d d rivers, u ser p referen ces, in stalled software, an d oth er settin gs req u ired to keep W in d ows ru n n in g correctly. Rep laces th e W IN.INI an d SYSTEM.INI files from W in d ows 3.x. re m o t e d i g i t a l l o o p b a c k A test th at ch ecks th e p h on e lin k an d a rem ote m od em ’s tran sm itter an d receiver. Data en tered from th e keyboard is tran sm itted from th e in itiatin g m od em , received by th e rem ote m od em ’s receiver, loop ed th rou gh its tran sm itter, an d retu rn ed to th e local screen for verification . re m o t e e c h o A cop y of th e d ata received by th e rem ote system , retu rn ed to th e sen d in g system , an d d isp layed on screen . A fu n ction of th e rem ote system . re so l u t i o n 1) A referen ce to th e size of th e p ixels u sed in grap h ics. In m ed iu m resolu tion grap h ics, p ixels are large. In h igh -resolu tion grap h ics, p ixels are sm all. 2) A m easu re of th e n u m ber of h orizon tal an d vertical p ixels th at can be d isp layed by a vid eo ad ap ter an d m on itor. RFI

Rad io Freq u en cy In terferen ce. A h igh freq u en cy sign al rad iated by im p rop erly sh ield ed con d u ctors, p articu larly wh en sign al p ath len gth s are com p arable to or lon ger th an th e sign al wavelen gth s. Th e FCC n ow regu lates RFI in com p u ter eq u ip m en t sold in th e U.S. u n d er FCC Regu lation s Part 15, Su bp art J.

RGB

Red -Green -Blu e. A typ e of com p u ter color d isp lay ou tp u t sign al com p rised of sep arately con trollable red , green , an d blu e sign als; as op p osed to com p osite vid eo, in wh ich sign als are com bin ed p rior to ou tp u t. RGB m on itors typ ically offer h igh er resolu tion th an com p osite m on itors.

ri b b o n c a b l e Flat cable with wires ru n n in g in p arallel, su ch as th ose u sed for in tern al IDE or SCSI. RISC Red u ced In stru ction Set Com p u ter. Differen tiated from CISC, Com p lex In stru ction Set Com p u ter. RISC p rocessors h ave sim p le in stru ction sets req u irin g on ly on e or a few execu tion cycles. Th ese sim p le in stru ction s can be u sed m ore effectively th an CISC system s with ap p rop riately d esign ed software, resu ltin g in faster op eration s. See also CISC. RJ-1 1

Th e stan d ard 2-wire con n ector typ e u sed for sin gle-lin e telep h on e con n ection s.

RJ-1 4

Th e stan d ard 4-wire con n ector typ e u sed for two-lin e telep h on e con n ection s.

RJ-4 5 A stan d ard con n ector typ e u sed in n etworkin g with twisted -p air cablin g. Resem bles an RJ-11/ 14 telep h on e jack, bu t RJ-45 is larger with m ore wires. RLL Ru n -Len gth Lim ited . A typ e of en cod in g th at d erives its n am e from th e fact th at th e tech n iq u es u sed lim it th e d istan ce (ru n len gth ) between m agn etic flu x reversals on th e d isk p latter. Several typ es of RLL en cod in g tech n iq u es exist, alth ou gh on ly two are com m on ly u sed . (1,7)RLL en cod in g in creases storage cap acity by abou t 30% over MFM en cod in g an d is m ost p op u lar in th e very h igh est cap acity d rives d u e to a better win d ow m argin , wh ile (2,7)RLL en cod in g in creases storage cap acity

Glossary

by 50% over MFM en cod in g an d is u sed in th e m ajority of RLL im p lem en tation s. Most IDE, ESDI, an d SCSI h ard d isks u se on e of th ese form s of RLL en cod in g. RMA n u m b e r Retu rn -Merch an d ise Au th orization Nu m ber. A n u m ber given to you by a ven d or wh en you arran ge to retu rn an item for rep airs. Used to track th e item an d th e rep air. ROM

Read -On ly Mem ory. A typ e of m em ory th at h as valu es p erm an en tly or sem ip erm an en tly bu rn ed in . Th ese location s are u sed to h old im p ortan t p rogram s or d ata th at m u st be available to th e com p u ter wh en th e p ower in itially is tu rn ed on .

ROM BIOS Read On ly Mem ory-Basic In p u t Ou tp u t System . A BIOS en cod ed in a form of read -on ly m em ory for p rotection . Often ap p lied to im p ortan t startu p p rogram s th at m u st be p resen t in a system for it to op erate. ro o t d i re c t o ry Th e m ain d irectory of an y h ard or flop p y d isk. Has a fixed size an d location for a p articu lar d isk volu m e an d can n ot be resized d yn am ically th e way su bd irectories can . ro u t e r Hard ware th at rou tes m essages from on e local area n etwork to an oth er. It is u sed to in tern etwork sim ilar an d d issim ilar n etworks an d can select th e m ost exp ed ien t rou te based on traffic load , lin e sp eed s, costs, an d n etwork failu res. ro u t i n e Set of freq u en tly u sed in stru ction s. May be con sid ered as a su bd ivision of a p rogram with two or m ore in stru ction s th at are related fu n ction ally. RS-2 3 2 An in terface in trod u ced in Au gu st 1969 by th e Electron ic In d u stries Association . Th e RS-232 in terface stan d ard p rovid es an electrical d escrip tion for con n ectin g p erip h eral d evices to com p u ters. S-Vi d e o (Y/ C) Typ e of vid eo sign al u sed in th e Hi8 an d S-VHS vid eotap e form ats in wh ich th e lu m in an ce an d ch rom in an ce (Y/ C) com p on en ts are kep t sep arate, p rovid in g greater con trol an d q u ality of each im age. S-vid eo tran sm its lu m in an ce an d color p ortion s sep arately, th u s avoid in g th e NTSC en cod in g p rocess an d its in evitable loss of p ictu re q u ality. sc a n c o d e s Th e h exad ecim al cod es actu ally sen t by th e keyboard to th e m oth erboard wh en a key is p ressed . sc a n l i n e s Th e p arallel lin es across a vid eo screen , alon g wh ich th e scan n in g sp ot travels in p ain tin g th e vid eo in form ation th at m akes u p a m on itor p ictu re. NTSC system s u se 525 scan lin es to a screen ; PAL system s u se 625. sc a n n i n g f re q u e n c y A m on itor m easu rem en t th at sp ecifies h ow often th e im age is refresh ed . See also vertical scan frequency. sc ra t c h d i sk A d isk th at con tain s n o u sefu l in form ation an d can be u sed as a test d isk. IBM h as a rou tin e on th e Ad van ced Diagn ostics d isks th at creates a sp ecially form atted scratch d isk to be u sed for testin g flop p y d rives. SCSI

Sm all Com p u ter System In terface. A stan d ard origin ally d evelop ed by Sh u gart Associates (th en called SASI for Sh u gart Associates System In terface) an d later ap p roved by ANSI in 1986. SCSI-2 was ap p roved in 1994, an d SCSI-3 is cu rren tly in th e d evelop m en t p rocess. Norm ally u ses a 50-p in con n ector an d p erm its m u ltip le d evices (u p to eigh t in clu d in g th e h ost) to be con n ected in d aisy-ch ain fash ion .

1309

1310

Glossary

SD LC Syn ch ron ou s Data Lin k Con trol. A p rotocol d evelop ed by IBM for software ap p lication s an d com m u n icatin g d evices op eration in IBM’s System s Network Arch itectu re (SNA). Defin es op eration s at th e lin k level of com m u n ication s—for exam p le, th e form at of d ata fram es exch an ged between m od em s over a p h on e lin e. SD RAM Syn ch ron ou s DRAM. RAM th at ru n s at th e sam e sp eed as th e m ain system bu s. SEC (Si n g l e Ed g e Co n t a c t ) c a rt ri d g e An In tel processor packagin g design in wh ich th e processor alon g with several L2 cach e ch ips are m ou n ted on a sm all circu it board (m u ch like an oversized m em ory SIMM), wh ich is th en sealed in a m etal an d plastic cartridge. Th e cartridge is th en plu gged in to th e m oth erboard th rou gh an edge con n ector called Slot 1 or Slot 2, wh ich looks very m u ch like an adapter card slot. SECAM SEq u en tial Cou leu r A Mém oire (seq u en tial color with m em ory), th e Fren ch color TV system also ad op ted in Ru ssia. Th e basis of op eration is th e seq u en tial record in g of p rim ary colors in altern ate lin es. Th e im age form at is 4:3, 625 lin es, 50Hz, an d 6MHz vid eo ban d wid th with a total 8MHz of vid eo ch an n el wid th . se c t o r A section of on e track d efin ed with id en tification m arkin gs an d an id en tification n u m ber. Most sectors h old 512 bytes of d ata. se c u ri t y so f t w a re Utility software th at u ses a system of p assword s an d oth er d evices to restrict an in d ivid u al’s access to su bd irectories an d files. se e k t i m e Th e am ou n t of tim e req u ired for a d isk d rive to m ove th e h ead s across on e th ird of th e total n u m ber of cylin d ers. Rep resen ts th e average tim e it takes to m ove th e h ead s from on e cylin d er to an oth er ran d om ly selected cylin d er. Seek tim e is a p art of th e average access tim e for a d rive. se m i c o n d u c t o r A su bstan ce, su ch as germ an iu m or silicon , wh ose con d u ctivity is p oor at low tem p eratu res bu t is im p roved by m in u te ad d ition s of certain su bstan ces or by th e ap p lication of h eat, ligh t, or voltage. Dep en d in g on th e tem p eratu re an d p ressu re, a sem icon d u ctor can con trol a flow of electricity. Sem icon d u ctors are th e basis of m od ern electron ic-circu it tech n ology. se q u e n c e r A software p rogram th at con trols MIDI file m essages an d keep s track of m u sic tim in g. Becau se MIDI files store n ote in stru ction s in stead of actu al sou n d s, a seq u en cer is n eed ed to p lay, record , an d ed it MIDI sou n d s. Seq u en cer p rogram s allow for record in g an d p layback of MIDI files by storin g th e in stru m en t, n ote p itch (freq u en cy), d u ration (in real tim e) th at each n ote is h eld , an d lou d n ess (am p litu d e) of each m u sical or sou n d -effect n ote. se q u e n t i a l f i l e A file in wh ich varyin g-len gth d ata elem en ts are record ed en d to en d , with d elim itin g ch aracters p laced between each elem en t. To fin d a p articu lar elem en t, you m u st read th e wh ole file u p to th at elem en t. se ri a l Th e tran sfer of d ata ch aracters on e bit at a tim e, seq u en tially, u sin g a sin gle electrical p ath . se ri a l m o u se se ri a l p o rt

A m ou se d esign ed to con n ect to a com p u ter’s serial p ort. An I/ O con n ector u sed to con n ect to serial d evices.

se rv o Th e m ech an ism in a d rive th at en ables th e h ead p osition er to ad ju st con tin u ou sly so th at it is p recisely p laced above a given cylin d er in th e d rive.

Glossary

se rv o d a t a Magn etic m arkin gs written on d isk p latters to gu id e th e read / write h ead s in d rives th at u se voice-coil actu ators. se ssi o n (si n g l e o r m u l t i se ssi o n ) A term u sed in CD-ROM record in g to d escribe a record in g even t. In a sin gle session , d ata is record ed on a CD-ROM d isc an d an in d ex is created . If ad d ition al sp ace is left on th e d isc, an oth er session can be u sed to record ad d ition al files alon g with an oth er in d ex. Som e old er CD-ROM d rives d o n ot exp ect ad d ition al record in g session s an d th erefore will be u n able to read th e ad d ition al session d ata on th e d isk. Th e ad ven t of Kod ak’s Ph oto CD p rop elled th e d esire for m u ltisession CD-ROM XA (exten d ed arch itectu re) d rives. se t t l i n g t i m e Th e tim e req u ired for read / write h ead s to stop vibratin g after th ey h ave been m oved to a n ew track. sh a d o w m a sk A th in screen fu ll of h oles th at ad h eres to th e in sid e of a color CRT. Th e electron beam is aim ed th rou gh th e h oles in th e m ask on to th e p h osp h or d ots. See also aperture grille. sh a d o w ROM A cop y of a system ’s slower access ROM BIOS p laced in faster access RAM, u su ally d u rin g th e startu p or boot p roced u re. Th is setu p en ables th e system to access BIOS cod e with ou t th e p en alty of ad d ition al wait states req u ired by th e slower ROM ch ip s. Also called shadow RAM. sh e l l

Th e gen eric n am e of an y u ser in terface software. COMMAND.COM is th e stan d ard sh ell for DOS. OS/ 2 com es with th ree sh ells: a DOS com m an d sh ell, an OS/ 2 com m an d sh ell, an d th e OS/ 2 Presen tation Man ager, a grap h ical sh ell.

sh i e l d e d t w i st e d -p a i r (STP ) Un sh ield ed twisted -p air (UTP) n etwork cablin g with a m etal sh eath or braid arou n d it to red u ce in terferen ce, u su ally u sed in Token -Rin g n etworks. sh o c k ra t i n g A ratin g (u su ally exp ressed in G force u n its) of h ow m u ch sh ock a d isk d rive can su stain with ou t d am age. Usu ally two d ifferen t sp ecification s exist for a d rive p owered on or off. si g n a l -t o -n o i se (S/ N) ra t i o Th e stren gth of a vid eo or au d io sign al in relation to in terferen ce (n oise). Th e h igh er th e S/ N ratio, th e better th e q u ality of th e sign al. SIMM Sin gle In lin e Mem ory Mod u le. An array of m em ory ch ip s on a sm all PC board with a sin gle row of I/ O con tacts. si n g l e -e n d e d An electrical sign alin g m eth od wh ere a sin gle lin e is referen ced by a grou n d p ath com m on to oth er sign als. In a sin gle-en d ed bu s in ten d ed for m od erately lon g d istan ces, th ere is com m on ly on e grou n d lin e between grou p s of sign al lin es to p rovid e som e resistan ce to sign al crosstalk. Sin gle-en d ed sign als req u ire on ly on e d river or receiver p in p er sign al, p lu s on e grou n d p in p er grou p of sign als. Sin gle-en d ed sign als are vu ln erable to com m on m od e n oise an d crosstalk bu t are m u ch less exp en sive th an d ifferen tial sign alin g m eth od s. SIP

Sin gle In lin e Package. A DIP-like p ackage with on ly on e row of lead s.

sk i n n y d i p Twen ty-fou r- an d twen ty-eigh t-p osition DIP d evices with .300-in ch rowto-row cen terlin es. sl e e p

See suspend.

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Glossary

SLIP

Serial Lin e In tern et Protocol. An In tern et p rotocol th at is u sed to ru n th e In tern et Protocol (IP) over serial lin es su ch as telep h on e circu its. IP allows a p acket to traverse m u ltip le n etworks on th e way to its fin al d estin ation .

sl o t

A p h ysical con n ector on a m oth erboard to h old an exp an sion card , SIMMs an d DIMMs, or a p rocessor card in p lace an d m ake con tact with th e electrical con n ection s.

Sl o t 1 Th e m oth erboard con n ector d esign ed by In tel to accep t its SEC cartrid ge p rocessor d esign u sed by th e Pen tiu m II. Sl o t 2 A m oth erboard con n ector for Pen tiu m II Xeon p rocessors in ten d ed m ain ly for fileserver ap p lication s. Slot 2 system s su p p ort u p to 4-way sym m etric m u ltip rocessin g. SMBIOS A BIOS th at in corp orates system m an agem en t fu n ction s an d rep ortin g com p atible with th e Desktop Man agem en t In terface (DMI). SMP TE t i m e c o d e An 80-bit stan d ard ized ed it tim e cod e ad op ted by SMPTE, th e Society of Motion Pictu re an d Television En gin eers. Th e SMPTE tim e cod e is a stan d ard u sed to id en tify in d ivid u al vid eo fram es in th e vid eo-ed itin g p rocess. SMPTE tim e cod e con trols su ch fu n ction s as p lay, record , rewin d , an d forward of vid eo tap es. SMPTE tim e cod e d isp lays vid eo in term s of h ou rs, m in u tes, secon d s, an d fram es for accu rate vid eo ed itin g. sn o w

A flu rry of brigh t d ots th at can ap p ear an ywh ere on screen on a m on itor.

so c k e t A recep tacle, u su ally on a m oth erboard alth ou gh som etim es also fou n d on exp an sion card s, th at p rocessors or ch ip s can be p lu gged in to. So c k e t 1 –8 Th e In tel sp ecification s for eigh t d ifferen t sockets to accep t variou s In tel p rocessors in th e 486, Pen tiu m , an d Pen tiu m Pro fam ilies. so f t e rro r An error in read in g or writin g d ata th at occu rs sp orad ically, u su ally becau se of a tran sien t p roblem su ch as a p ower flu ctu ation . so f t w a re A series of in stru ction s load ed in th e com p u ter’s m em ory th at in stru cts th e com p u ter in h ow to accom p lish a p roblem or task. SO-J Sm all Ou tlin e J-lead . A sm all DIP p ackage with J-sh ap ed lead s for su rface m ou n tin g or socketin g. So u t h Bri d g e Th e In tel term for th e lower-sp eed com p on en t in th e ch ip set th at h as always been a sin gle in d ivid u al ch ip . Also called th e PIIX (PCI, ISA, IDE eXcelerator), th e Sou th Brid ge con n ects to th e 33MHz PCI bu s an d con tain s th e IDE in terface p orts an d th e in terface to th e 8MHz ISA bu s. It also n orm ally con tain s th e USB (Un iversal Serial Bu s) in terface an d even th e CMOS RAM an d real-tim e clock fu n ction s. Th e Sou th Brid ge con tain s all of th e com p on en ts th at m ake u p th e ISA bu s, in clu d in g th e in terru p t an d DMA con trollers. See also chipset an d North Bridge. sp i n d l e

Th e cen tral p ost on wh ich a d isk d rive’s p latters are m ou n ted .

sp i n d l e c o u n t In n otebook an d lap top com p u ters with in terch an geable d rives, sp in d le cou n t refers to h ow m an y d rives can be in stalled an d u sed at th e sam e tim e.

Glossary

SRAM Static Ran d om Access Mem ory. A form of h igh -sp eed m em ory. SRAM ch ip s d o n ot req u ire a refresh cycle like DRAM ch ip s an d can be m ad e to op erate at very h igh -access sp eed s. SRAM ch ip s are very exp en sive becau se th ey n orm ally req u ire six tran sistors p er bit. Th is also m akes th e ch ip larger th an con ven tion al DRAM ch ip s. SRAM is volatile, m ean in g it will lose d ata with n o p ower. ST-5 0 6 / 4 1 2 A h ard d isk in terface in ven ted by Seagate Tech n ology an d in trod u ced in 1980 with th e ST-506 5M h ard d rive. st a i r-st e p p i n g aliasin g.

Jagged raster rep resen tation of d iagon als or cu rves; corrected by an ti-

st a n d b y Defin es an op tion al op eratin g state of m in im al p ower red u ction with th e sh ortest recovery tim e. st a n d b y p o w e r su p p l y A backu p p ower su p p ly th at q u ickly switch es in to op eration d u rin g a p ower ou tage. St a n d o f f In a m oth erboard an d case d esign , sm all n on con d u ctive sp acers (u su ally p lastic or n ylon ) u sed to keep th e u n d ersid e of th e m oth erboard from con tactin g th e m etallic case, th erefore p reven tin g sh ort circu its of th e m oth erboard . st a rt / st o p b i t s Th e sign alin g bits attach ed to a ch aracter before an d after th e ch aracter is tran sm itted d u rin g asyn ch ron ou s tran sm ission . st a rt i n g c l u st e r Th e n u m ber of th e first clu ster occu p ied by a file. Listed in th e d irectory en try of every file. st e p p e r m o t o r a c t u a t o r An assem bly th at m oves d isk d rive read / write h ead s across p latters by a seq u en ce of sm all p artial tu rn s of a step p er m otor. st e p p i n g Th e cod e u sed to id en tify th e revision of a p rocessor. New m asks are in trod u ced to bu ild each su ccessive step p in g, in corp oratin g an y ch an ges n eed ed to fix kn own bu gs in p rior step p in gs. st o ra g e Device or m ed iu m on or in wh ich d ata can be en tered or h eld an d retrieved at a later tim e. Syn on ym ou s with m em ory. st re a m i n g In tap e backu p , a con d ition in wh ich d ata is tran sferred from th e h ard d isk as q u ickly as th e tap e d rive can record th e d ata so th at th e d rive d oes n ot start an d stop or waste tap e. st ri n g

A seq u en ce of ch aracters.

su b d i re c t o ry as files.

A d irectory listed in an oth er d irectory. Su bd irectories th em selves exist

su b ro u t i n e A segm en t of a p rogram th at can be execu ted by a sin gle call. Also called program m odule. su p e rsc a l a r e x e c u t i o n stru ction at a tim e. su rf a c e m o u n t board .

Th e cap ability of a p rocessor to execu te m ore th an on e in -

Ch ip carriers an d sockets d esign ed to m ou n t to th e su rface of a PC

su rg e p ro t e c t o r A d evice in th e p ower lin e th at feed s th e com p u ter an d p rovid es p rotection again st voltage sp ikes an d oth er tran sien ts.

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Glossary

su sp e n d Refers to a level of p ower m an agem en t in wh ich su bstan tial p ower red u ction is ach ieved by th e d isp lay or oth er com p on en ts. Th e com p on en ts can h ave a lon ger recovery tim e from th is state th an from th e stan d by state. SVGA (Su p e r VGA) Origin ally, th is referred to a vid eo ad ap ter or m on itor cap able of 800×600 resolu tion . However, th is term is n ow often m isu sed an d u sed to refer to an y vid eo ad ap ter or m on itor th at can d isp lay an y resolu tion greater th an 640×480. SW ED AC Swed ish Board for Tech n ical Accred itation . Regu latory agen cy establish in g stan d ard s su ch as MPR1 an d MPR2, wh ich sp ecify m axim u m valu es for both altern atin g electric field s an d m agn etic field s an d p rovid e m on itor m an u factu rers with gu id elin es in creatin g low-em ission m on itors. sy n c h ro n o u s c o m m u n i c a t i o n A form of com m u n ication in wh ich blocks of d ata are sen t at strictly tim ed in tervals. Becau se th e tim in g is u n iform , n o start or stop bits are req u ired . Com p are with asyn ch ron ou s com m u n ication . Som e m ain fram es su p p ort on ly syn ch ron ou s com m u n ication s u n less a syn ch ron ou s ad ap ter an d ap p rop riate software h ave been in stalled . See also asynchronous com m unication. sy st e m c ra sh A situ ation in wh ich th e com p u ter freezes u p an d refu ses to p roceed with ou t rebootin g. Usu ally cau sed by fau lty software. Un like a h ard d isk crash , n o p erm an en t p h ysical d am age occu rs. sy st e m f i l e s Files with th e system attribu te. Norm ally, th e h id d en files th at are u sed to boot th e op eratin g system . Th e MS-DOS an d W in d ows 9x system files in clu d e IO.SYS an d MSDOS.SYS; th e IBM DOS system files are IBMBIO.COM an d IBMDOS.COM. Sy st e m Ma n a g e m e n t Mo d e (SMM) Circu itry in tegrated in to In tel p rocessors th at op erates in d ep en d en tly to con trol th e p rocessor’s p ower u se based on its activity level. It allows th e u ser to sp ecify tim e in tervals after wh ich th e CPU will be p owered d own p artially or fu lly an d also su p p orts th e su sp en d / resu m e featu re th at allows for in stan t p ower on an d p ower off. t a rg e t A d evice attach ed to a SCSI bu s th at receives an d p rocesses com m an d s sen t from an oth er d evice (th e in itiator) on th e SCSI bu s. A SCSI h ard d isk is an exam p le of a target. TCM

Trellis-cod ed m od u lation . An error-d etection an d correction tech n iq u e em p loyed by h igh -sp eed m od em s to en able h igh er-sp eed tran sm ission s th at are m ore resistan t to lin e im p airm en ts.

TCO

1) Refers to th e Swed ish Con fed eration of Profession al Em p loyees, wh ich h as set strin gen t stan d ard s for d evices th at em it rad iation . See MPR II. 2) Total Cost of Own ersh ip . Th e cost of u sin g a com p u ter. It in clu d es th e cost of th e h ard ware, software, an d u p grad es as well as th e cost of th e in -h ou se staff an d con su ltan ts th at p rovid e train in g an d tech n ical su p p ort.

TCP

Tap e Carrier Package. A m eth od of p ackagin g p rocessors for u se in p ortable system s th at red u ces th e size, th e p ower con su m ed , an d th e h eat gen erated by th e ch ip . A p rocessor in th e TCP form factor is essen tially a raw d ie en cased in an oversized p iece of p olyam id e film . Th e film is lam in ated with cop p er foil th at is etch ed to form th e lead s th at will con n ect th e p rocessor to th e m oth erboard .

Glossary

TCP / IP Tran sm ission Con trol Protocol/ In tern et Protocol. A set of p rotocols d evelop ed by th e U.S. Dep artm en t of Defen se (DoD) to lin k d issim ilar com p u ters across m an y kin d s of n etworks. Th is is th e p rim ary p rotocol u sed by th e In tern et. t e m p o ra ry b a c k u p A secon d cop y of a work file, u su ally h avin g th e exten sion BAK. Created by ap p lication software so th at you easily can retu rn to a p reviou s version of you r work. t e m p o ra ry f i l e own u se. t e ra

A file tem p orarily (an d u su ally in visibly) created by a p rogram for its

A m u ltip lier in d icatin g 1 trillion (1,000,000,000,000) of som e u n it. Abbreviated as t or T. W h en u sed to in d icate a n u m ber of bytes of m em ory storage, th e m u ltip lier d efin ition ch an ges to 1,099,511,627,776. On e terabit, for exam p le, eq u als 1,000,000,000,000 bits, an d on e terabyte eq u als 1,099,511,627,776 bytes.

t e ra b y t e (T)

A u n it of in form ation storage eq u al to 1,099,511,627,776 bytes.

t e rm i n a l A d evice wh ose keyboard an d d isp lay are u sed for sen d in g an d receivin g d ata over a com m u n ication s lin k. Differs from a m icrocom p u ter in th at it h as n o in tern al p rocessin g cap abilities. Used to en ter d ata in to or retrieve p rocessed d ata from a system or n etwork. t e rm i n a l m o d e An op eration al m od e req u ired for m icrocom p u ters to tran sm it d ata. In term in al m od e, th e com p u ter acts as th ou gh it were a stan d ard term in al su ch as a teletyp ewriter rath er th an a d ata p rocessor. Keyboard en tries go d irectly to th e m od em , wh eth er th e en try is a m od em com m an d or d ata to be tran sm itted over th e p h on e lin es. Received d ata is ou tp u t d irectly to th e screen . Th e m ore p op u lar com m u n ication s software p rod u cts con trol term in al m od e an d en able m ore com p lex op eration s, in clu d in g file tran sm ission an d savin g received files. t e rm i n a t o r Hard ware or circu its th at m u st be attach ed to or en abled at both en d s of an electrical bu s. Fu n ction s to p reven t th e reflection or ech oin g of sign als th at reach th e en d s of th e bu s an d to en su re th at th e correct im p ed an ce load is p laced on th e d river circu its on th e bu s. Most com m on ly u sed with th e SCSI bu s. TFT

Th in Film Tran sistor. Th e h igh est q u ality an d brigh test LCD color d isp lay typ e. A m eth od for p ackagin g on e to fou r tran sistors p er p ixel with in a flexible m aterial th at is th e sam e size an d sh ap e as th e LCD d isp lay, so th at th e tran sistors for each p ixel lie d irectly beh in d th e liq u id crystal cells th at th ey con trol.

t h i n Et h e rn e t

See 10base2 or IEEE 802.3.

t h i n -f i l m m e d i a Hard d isk p latters th at h ave a th in film (u su ally th ree-m illion th s of an in ch ) of m ed iu m d ep osited on th e alu m in u m su bstrate th rou gh a sp u tterin g or p latin g p rocess. Th i n n e t

See 10base2 or IEEE 802.3.

t h ro u g h -h o l e Ch ip carriers an d sockets eq u ip p ed with lead s th at exten d th rou gh h oles in a PC board . t h ro u g h p u t Th e am ou n t of u ser d ata tran sm itted p er secon d with ou t th e overh ead of p rotocol in form ation su ch as start an d stop bits or fram e h ead ers an d trailers.

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1316

Glossary

TIFF Tagged Im age File Form at. A way of storin g an d exch an gin g d igital im age d ata. Develop ed by Ald u s Corp oration , Microsoft Corp oration , an d m ajor scan n er ven d ors to h elp lin k scan n ed im ages with th e p op u lar d esktop p u blish in g ap p lication s. Su p p orts th ree m ain typ es of im age d ata: black-an d -wh ite d ata, h alfton es or d ith ered d ata, an d grayscale d ata. t i m e c o d e A fram e-by-fram e ad d ress cod e tim e referen ce record ed on th e sp are track of a vid eotap e or in serted in th e vertical blan kin g in terval. Th e tim e cod e is an eigh t-d igit n u m ber en cod in g tim e in h ou rs, m in u tes, secon d s, an d vid eo fram es. To k e n Ri n g A typ e of local area n etwork in wh ich th e workstation s relay a p acket of d ata called a token in a logical rin g con figu ration . W h en a station wan ts to tran sm it, it takes p ossession of th e token , attach es its d ata, an d th en frees th e token after th e d ata h as m ad e a com p lete circu it of th e electrical rin g. Tran sm its at sp eed s of 16Mbp s. Becau se of th e token -p assin g sch em e, access to th e n etwork is con trolled , u n like th e slower 10BaseX Eth ern et system in wh ich collision s of d ata can occu r, wh ich wastes tim e. Th e Token -Rin g n etwork u ses sh ield ed twisted -p air wirin g, wh ich is ch eap er th an th e coaxial cable u sed by 10Base2 an d 10Base5 Eth ern et an d ARCn et. t o n e r Th e u ltrafin e colored p lastic p owd er u sed in laser p rin ters an d p h otocop iers to p rod u ce th e im age on p ap er. t o w e r A p erson al com p u ter th at n orm ally sits on th e floor an d th at is m ou n ted vertically rath er th an h orizon tally. TP I

Tracks Per In ch . Used as a m easu rem en t of m agn etic track d en sity. Stan d ard 5 1/ 4in ch 360K flop p y d isks h ave a d en sity of 48 TPI, an d th e 1.2M d isks h ave a 96 TPI d en sity. All 3 1/ 2-in ch d isks h ave a 135.4667 TPI d en sity, an d h ard d isks can h ave d en sities greater th an 3,000 TPI.

t ra c k On e of th e m an y con cen tric circles th at h old s d ata on a d isk su rface. Con sists of a sin gle lin e of m agn etic flu x ch an ges an d is d ivid ed in to som e n u m ber of 512-byte sectors. t ra c k d e n si t y Exp ressed as tracks p er in ch (TPI); d efin es h ow m an y tracks are record ed in 1 in ch of sp ace m easu red rad ially from th e cen ter of th e d isk. Som etim es also called radial density. t ra c k -t o -t ra c k se e k t i m e ad jacen t tracks.

Th e tim e req u ired for read / write h ead s to m ove between

t ra n sp o rt l a y e r In th e OSI referen ce m od el, wh en m ore th an on e p acket is in p rocess at an y tim e, su ch as wh en a large file m u st be sp lit in to m u ltip le p ackets for tran sm ission , th is is th e layer th at con trols th e seq u en cin g of th e m essage com p on en ts an d regu lates in bou n d traffic flow. t ra n sp o rt a b l e c o m p u t e r A com p u ter system larger th an a p ortable system an d sim ilar in size an d sh ap e to a p ortable sewin g m ach in e. Most tran sp ortables con form to a d esign sim ilar to th e origin al Com p aq p ortable, with a bu ilt-in CRT d isp lay. Th ese system s are ch aracteristically very h eavy an d ru n on ly on AC p ower. Becau se of ad van ces p rim arily in LCD an d p lasm a-d isp lay tech n ology, th ese system s are largely obsolete an d h ave been rep laced by p ortable system s.

Glossary

t ro u b l e sh o o t i n g

Th e task of d eterm in in g th e cau se of a p roblem .

t ru e -c o l o r i m a g e s Tru e-color im ages are also called 24-bit color im ages becau se each p ixel is rep resen ted by 24 bits of d ata, allowin g for 16.7 m illion colors. Th e n u m ber of colors p ossible is based on th e n u m ber of bits u sed to rep resen t th e color. If 8 bits are u sed , th ere are 256 p ossible color valu es (2 to th e 8th p ower). To obtain 16.7 m illion colors, each of th e p rim ary colors (red , green , an d blu e) is rep resen ted by 8 bits p er p ixel, wh ich allows for 256 p ossible sh ad es for each of th e p rim ary red , green , an d blu e colors or 256×256×256 = 16.7 m illion total colors. TSR

Term in ate-an d -Stay-Resid en t. A p rogram th at rem ain s in m em ory after bein g load ed . Becau se th ey rem ain in m em ory, TSR p rogram s can be reactivated by a p red efin ed keystroke seq u en ce or oth er op eration wh ile an oth er p rogram is active. Usu ally called resident program s.

TTL Tran sistor-to-Tran sistor Logic. Digital sign als often are called TTL sign als. A TTL d isp lay is a m on itor th at accep ts d igital in p u t at stan d ard ized sign al voltage levels. t w i st e d p a i r A typ e of wire in wh ich two sm all, in su lated cop p er wires are wrap p ed or twisted arou n d each oth er to m in im ize in terferen ce from oth er wires in th e cable. Two typ es of twisted -p air cables are available: u n sh ield ed an d sh ield ed . Un sh ield ed twisted -p air (UTP) wirin g com m on ly is u sed in telep h on e cables an d p rovid es little p rotection again st in terferen ce. Sh ield ed twisted -p air (STP) wirin g is u sed in som e n etworks or an y ap p lication in wh ich im m u n ity from electrical in terferen ce is m ore im p ortan t. Twisted -p air wire is m u ch easier to work with th an coaxial cable an d is ch eap er as well. t y p e m a t i c Th e keyboard rep eated ly sen d in g th e keyp ress cod e to th e m oth erboard for a key th at is h eld d own . Th e d elay before th e cod e begin s to rep eat an d th e sp eed at wh ich it rep eats are u ser ad ju stable. UART Un iversal Asyn ch ron ou s Receiver Tran sm itter. A ch ip d evice th at con trols th e RS-232 serial p ort in a PC-com p atible system . Origin ally d evelop ed by Nation al Sem icon d u ctor, several UART version s are in PC-com p atible system s: Th e 8250B is u sed in PC- or XT-class system s, an d th e 16450 an d 16550A are u sed in AT-class system s. u n f o rm a t t e d c a p a c i t y Th e total n u m ber of bytes of d ata th at can fit on a d isk. Th e form atted cap acity is lower becau se sp ace is lost d efin in g th e bou n d aries between sectors. u n i n t e rru p t i b l e p o w e r su p p l y (UP S) A d evice th at su p p lies p ower to th e com p u ter from batteries so th at p ower will n ot stop , even m om en tarily, d u rin g a p ower ou tage. Th e batteries are rech arged con stan tly from a wall socket. Un i v e rsa l Asy n c h ro n o u s Re c e i v e r Tra n sm i t t e r

See UART.

UP C Un iversal Prod u ct Cod e. A 10-d igit com p u ter-read able bar cod e u sed in labelin g retail p rod u cts. Th e cod e in th e form of vertical bars in clu d es a five-d igit m an u factu rer id en tification n u m ber an d a five-d igit p rod u ct cod e n u m ber. u p d a t e To m od ify in form ation alread y con tain ed in a file or p rogram with cu rren t in form ation .

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Glossary

Up p e r Me m o ry Are a (UMA)

Th e 384K of m em ory between 640K an d 1M.

URL Un iform Resou rce Locator. Th e p rim ary n am in g sch em e u sed to id en tify a p articu lar site or file on th e W orld W id e W eb. URLs com bin e in form ation abou t th e p rotocol bein g u sed , th e ad d ress of th e site wh ere th e resou rce is located , th e su bd irectory location at th e site, an d th e n am e of th e p articu lar file (or p age) in q u estion . USB

Un iversal Serial Bu s. A 12Mbit/ sec (1.5M/ sec) in terface over a sim p le 4-wire con n ection . Th e bu s su p p orts u p to 127 d evices an d u ses a tiered star top ology bu ilt on exp an sion h u bs th at can resid e in th e PC, an y USB p erip h eral, or even stan d alon e h u b boxes.

u tility

Program s th at carry ou t rou tin e p roced u res to m ake com p u ter u se easier.

UTP

Un sh ield ed Twisted Pair. A typ e of wire often u sed in d oors to con n ect telep h on es or com p u ter d evices. Com es with two or fou r wires twisted in sid e a flexible p lastic sh eath or con d u it an d u ses m od u lar p lu gs an d p h on e jacks.

V.2 1

An ITU stan d ard for m od em com m u n ication s at 300bp s. Mod em s m ad e in th e U.S. or Can ad a follow th e Bell 103 stan d ard bu t can be set to an swer V.21 calls from overseas. Th e actu al tran sm ission rate is 300 bau d an d em p loys FSK (freq u en cy sh ift keyin g) m od u lation , wh ich en cod es a sin gle bit p er bau d .

V.2 2

An ITU stan d ard for m od em com m u n ication s at 1,200bp s, with an op tion al fallback to 600bp s. V.22 is p artially com p atible with th e Bell 212A stan d ard observed in th e U.S. an d Can ad a. Th e actu al tran sm ission rate is 600 bau d , u sin g DPSK (d ifferen tial-p h ase sh ift keyin g) to en cod e as m u ch as 2 bits p er bau d .

V.2 2 b i s An ITU stan d ard for m od em com m u n ication s at 2,400bp s. In clu d es an au tom atic lin k-n egotiation fallback to 1,200bp s an d com p atibility with Bell 212A/ V.22 m od em s. Th e actu al tran sm ission rate is 600 bau d , u sin g QAM (q u ad ratu re am p litu d e m od u lation ) to en cod e as m u ch as 4 bits p er bau d . V.2 3

An ITU stan d ard for m od em com m u n ication s at 1,200 or 600bp s with a 75bp s back ch an n el. Used in th e Un ited Kin gd om for som e vid eotext system s.

V.2 5

An ITU stan d ard for m od em com m u n ication s th at sp ecifies an an swer ton e d ifferen t from th e Bell an swer ton e u sed in th e U.S. an d Can ad a. Most in telligen t m od em s can be set with an ATB0 com m an d so th at th ey u se th e V.25 2,100Hz ton e wh en an swerin g overseas calls.

V.3 2

An ITU stan d ard for m od em com m u n ication s at 9,600bp s an d 4,800bp s. V.32 m od em s fall back to 4,800bp s wh en lin e q u ality is im p aired an d fall forward again to 9,600bp s wh en lin e q u ality im p roves. Th e actu al tran sm ission rate is 2,400 bau d u sin g QAM (q u ad ratu re am p litu d e m od u lation ) an d op tion al TCM (trellis-cod ed m od u lation ) to en cod e as m u ch as 4 d ata bits p er bau d .

V.3 2 b i s An ITU stan d ard th at exten d s th e stan d ard V.32 con n ection ran ge an d su p p orts 4,800; 7,200; 9,600; 12,000; an d 14,400bp s tran sm ission rates. V.32bis m od em s fall back to th e n ext lower sp eed wh en lin e q u ality is im p aired , fall back fu rth er as n ecessary, an d fall forward to th e n ext h igh er sp eed wh en lin e q u ality im p roves. Th e actu al tran sm ission rate is 2,400 bau d u sin g QAM (q u ad ratu re am p litu d e m od u lation ) an d TCM (trellis-cod ed m od u lation ) to en cod e as m u ch as 6 d ata bits p er bau d .

Glossary

V.3 2 t e rb o A p rop rietary stan d ard p rop osed by several m od em m an u factu rers th at will be ch eap er to im p lem en t th an th e stan d ard V.32 fast p rotocol bu t th at will on ly su p p ort tran sm ission sp eed s of u p to 18,800bp s. Becau se it is n ot an in d u stry stan d ard , it is n ot likely to h ave wid esp read in d u stry su p p ort. V.3 4

An ITU stan d ard th at exten d s th e stan d ard V.32bis con n ection ran ge, su p p ortin g 28,800bp s tran sm ission rates as well as all th e fu n ction s an d rates of V.32bis. Th is was called V.32fast or V.fast wh ile u n d er d evelop m en t.

V.3 4 + An ITU stan d ard th at exten d s th e stan d ard V.34 con n ection ran ge, su p p ortin g 33,600bp s tran sm ission rates as well as all th e fu n ction s an d rates of V.34. V.4 2

An ITU stan d ard for m od em com m u n ication s th at d efin es a two-stage p rocess of d etection an d n egotiation for LAPM error con trol. Also su p p orts MNP error-con trol p rotocol, Levels 1 th rou gh 4.

V.4 2 b i s An exten sion of CCITT V.42 th at d efin es a sp ecific d ata-com p ression sch em e for u se with V.42 an d MNP error con trol. V.9 0

ITU-T d esign ation for a d efin in g th e stan d ard for 56Kbp s com m u n ication . Su p erced es th e p rop rietary X2 sch em es from U.S. Robotics (3Com ) an d K56Flex from Rockwell.

v a c c i n e A typ e of p rogram u sed to locate an d erad icate viru s cod e from in fected p rogram s or system s. VCP I

Virtu al Con trol Program In terface. A 386 an d later p rocessor m em ory m an agem en t stan d ard created by Ph ar Lap software in con ju n ction with oth er software d evelop ers. VCPI p rovid es an in terface between ap p lication s u sin g DOS exten d ers an d 386 m em ory m an agers.

Ve rt i c a l Bl a n k i n g In t e rv a l (VBI) Th e top an d bottom lin es in th e vid eo field , in wh ich fram e n u m bers, p ictu re stop s, ch ap ter stop s, wh ite flags, closed cap tion s, an d m ore m ay be en cod ed . Th ese lin es d o n ot ap p ear on th e d isp lay screen bu t m ain tain im age stability an d en h an ce im age access. v e rt i c a l sc a n f re q u e n c y Th e rate at wh ich th e electron gu n in a m on itor scan s or refresh es th e en tire screen each secon d . Ve ry La rg e Sc a l e In t e g ra t i o n

See IC.

VESA Vid eo Electron ics Stan d ard s Association . Fou n d ed in th e late 1980s by NEC Hom e Electron ics an d eigh t oth er lead in g vid eo board m an u factu rers, with th e m ain goal to stan d ard ize th e electrical, tim in g, an d p rogram m in g issu es su rrou n d in g 800×600 resolu tion vid eo d isp lays, com m on ly kn own as Super V GA. VESA h as also d evelop ed th e Vid eo Local Bu s (VL-Bu s) stan d ard for con n ectin g h igh -sp eed ad ap ters d irectly to th e local p rocessor bu s. VGA

Vid eo Grap h ics Array. A typ e of PC vid eo d isp lay circu it (an d ad ap ter) first in trod u ced by IBM on Ap ril 2, 1987, th at su p p orts text an d grap h ics. Text is su p p orted at a m axim u m resolu tion of 80×25 ch aracters in 16 colors with a ch aracter box of 9×16 p ixels. Grap h ics is su p p orted at a m axim u m resolu tion of 320×200 p ixels in 256 (from a p alette of 262,144) colors or 640×480 p ixels in 16 colors. Th e VGA ou tp u ts an an alog sign al with a h orizon tal scan n in g freq u en cy of 31.5KHz an d su p p orts an alog color or an alog m on och rom e d isp lays.

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Glossary

VH S

Vid eo Hom e System . A p op u lar con su m er vid eotap e form at d evelop ed by Matsu sh ita an d JVC.

v i d e o A system of record in g an d tran sm ittin g p rim arily visu al in form ation by tran slatin g m ovin g or still im ages in to electrical sign als. Th e term vid eo p rop erly refers on ly to th e p ictu re, bu t as a gen eric term , vid eo u su ally em braces au d io an d oth er sign als th at are p art of a com p lete p rogram . Vid eo n ow in clu d es n ot on ly broad cast television bu t m an y n on broad cast ap p lication s su ch as corp orate com m u n ication s, m arketin g, h om e en tertain m en t, gam es, teletext, secu rity, an d even th e visu al d isp lay u n its of com p u ter-based tech n ology. Vi d e o 8 o r 8 m m Vi d e o Vid eo form at based on th e 8m m vid eotap es p op u larized by Son y for cam cord ers. v i d e o a d a p t e r An exp an sion card or ch ip set bu ilt in to a m oth erboard th at p rovid es th e cap ability to d isp lay text an d grap h ics on screen . If th e ad ap ter is p art of an exp an sion card , it also in clu d es th e p h ysical con n ector for th e m on itor cable. If th e ch ip set is on th e m oth erboard , th e vid eo con n ector will be on th e m oth erboard as well. v i d e o g ra p h i c s a rra y

See V GA.

v i d e o -o n -CD o r v i d e o CD A fu ll-m otion d igital vid eo form at u sin g MPEG vid eo com p ression an d in corp oratin g a variety of VCR-like con trol cap abilities. See also W hite Book. v i rt u a l d i sk A RAM d isk or “p h an tom d isk d rive” in wh ich a section of system m em ory (u su ally RAM) is set asid e to h old d ata, ju st as th ou gh it were a n u m ber of d isk sectors. To DOS, a virtu al d isk looks like an d fu n ction s like an y oth er “real” d rive. v i rt u a l m e m o ry A tech n iq u e by wh ich op eratin g system s (in clu d in g OS/ 2) load m ore p rogram s an d d ata in to m em ory th an th ey can h old . Parts of th e p rogram s an d d ata are kep t on d isk an d con stan tly swap p ed back an d forth in to system m em ory. Th e ap p lication s’ software p rogram s are u n aware of th is setu p an d act as th ou gh a large am ou n t of m em ory is available. v i rt u a l re a l m o d e A m od e available in all In tel 80386-com p atible p rocessors. In th is m od e, m em ory ad d ressin g is lim ited to 4,096M, restricted p rotection levels can be set to trap software crash es an d con trol th e system , an d in d ivid u al real-m od e com p atible session s can be set u p an d m ain tain ed sep arately from on e an oth er. v i ru s A typ e of resid en t p rogram d esign ed to rep licate itself. Usu ally at som e later tim e wh en th e viru s is ru n n in g, it cau ses an u n d esirable action to take p lace. VL-Bu s VESA Local Bu s. A stan d ard 32-bit exp an sion slot bu s sp ecification u sed in 486 PCs. Now rep laced by PCI bu s. VMM Virtu al Mem ory Man ager. A facility in W in d ows en h an ced m od e th at m an ages th e task of swap p in g d ata in an d ou t of 386 an d later p rocessor virtu al real-m od e m em ory sp ace for m u ltip le n on -W in d ows ap p lication s ru n n in g in virtu al real m od e. v o i c e -c o i l a c t u a t o r A d evice th at m oves read / write h ead s across h ard d isk p latters by m agn etic in teraction between coils of wire an d a m agn et. Fu n ction s som ewh at like an au d io sp eaker, from wh ich th e n am e origin ated .

Glossary

v o l t a g e re d u c t i o n t e c h n o l o g y An In tel p rocessor tech n ology th at allows a p rocessor to d raw th e stan d ard voltage from th e m oth erboard bu t ru n th e in tern al p rocessor core at a lower voltage. v o l t a g e re g u l a t o r A d evice th at sm ooth es ou t voltage irregu larities in th e p ower fed to th e com p u ter. v o l u m e A p ortion of a d isk sign ified by a sin gle d rive sp ecifier. Un d er DOS v3.3 an d later, a sin gle h ard d isk can be p artition ed in to several volu m es, each with its own logical d rive sp ecifier (C:, D:, E:, an d so on ). vo lu m e label

An id en tifier or n am e of u p to 11 ch aracters th at n am es a d isk.

VRAM Vid eo Ran d om -Access Mem ory. VRAM ch ip s are m od ified DRAMs on vid eo board s th at en able sim u ltan eou s access by th e h ost system ’s p rocessor an d th e p rocessor on th e vid eo board . A large am ou n t of in form ation th u s can be tran sferred q u ickly between th e vid eo board an d th e system p rocessor. Som etim es also called dual-ported RAM. Vx D

Virtu al Device Driver. A sp ecial typ e of W in d ows d river. VxDs ru n at th e m ost p rivileged CPU m od e (rin g 0) an d allow low-level in teraction with th e h ard ware an d in tern al W in d ows fu n ction s.

w a f e r A th in circu lar p iece of silicon from wh ich p rocessors, m em ory, an d oth er sem icon d u ctor electron ics are m an u factu red . w a i t st a t e s Pau se cycles d u rin g system op eration th at req u ire th e p rocessor to wait on e or m ore clock cycles u n til m em ory can resp on d to th e p rocessor’s req u est. En ables th e m icrop rocessor to syn ch ron ize with lower-cost, slower m em ory. A system th at ru n s with “zero wait states” req u ires n on e of th ese cycles becau se of th e u se of faster m em ory or a m em ory cach e system . w a rm b o o t Rebootin g a system by m ean s of a software com m an d rath er th an tu rn in g th e p ower off an d back on . See also cold boot. w a v e t a b l e sy n t h e si s A m eth od of creatin g syn th etic sou n d on a sou n d card th at u ses actu al m u sical in stru m en t sou n ds sam pled an d stored on ROM (or RAM) on th e sou n d card. Th e sou n d card th en m odifies th is sam ple to create an y n ote n eeded for th at in stru m en t. Produ ces m u ch better sou n d qu ality th an FM syn th esis. W h e t st o n e A ben ch m ark p rogram d evelop ed in 1976 an d d esign ed to sim u late arith m etic-in ten sive p rogram s u sed in scien tific com p u tin g. Rem ain s com p letely CPU-bou n d an d p erform s n o I/ O or system calls. Origin ally written in ALGOL, alth ou gh th e C an d Pascal version s becam e m ore p op u lar by th e late 1980s. Th e sp eed at wh ich a system p erform s floatin g-p oin t op eration s often is m easu red in u n its of W h etston es. W h i t e Bo o k A stan d ard sp ecification d evelop ed by Ph ilip s an d JVC in 1993 for storin g MPEG stan d ard vid eo on CDs. An exten sion of th e Red Book stan d ard for d igital au d io, Yellow Book stan d ard for CD-ROM, Green Book stan d ard for CD-I, an d Oran ge Book stan d ard for CD W rite On ce. W h i t n e y t e c h n o l o g y A term referrin g to a m agn etic d isk d esign th at u su ally h as oxid e or th in film m ed ia, th in film read / write h ead s, low floatin g-h eigh t slid ers, an d low-m ass actu ator arm s th at togeth er allow h igh er-bit d en sities th an th e old er

1321

1322

Glossary

W in ch ester tech n ology. W h itn ey tech n ology was first in trod u ced with th e IBM 3370 d isk d rive, circa 1979. w i d e a re a n e t w o rk (W AN) bu ild in g.

A LAN th at exten d s beyon d th e bou n d aries of a sin gle

W i n c h e st e r d ri v e An y ord in ary, n on rem ovable (or fixed ) h ard d isk d rive. Th e n am e origin ates from a p articu lar IBM d rive in th e 1960s th at h ad 30M of fixed an d 30M of rem ovable storage. Th is 30-30 d rive m atch ed th e caliber figu re for a p op u lar series of rifles m ad e by W in ch ester, so th e slan g term W inchester was ap p lied to an y fixed -p latter h ard d isk. W i n c h e st e r t e c h n o l o g y Th e term W inchester is loosely ap p lied to m ean an y d isk with a fixed or n on rem ovable record in g m ed iu m . More p recisely, th e term ap p lies to a ferrite read / write h ead an d slid er d esign with oxid e m ed ia th at was first em p loyed in th e IBM 3340 d isk d rive, circa 1973. Most d rives tod ay actu ally u se W h itn ey tech n ology. W i n t e l Th e com m on n am e given to com p u ters ru n n in g Microsoft W in d ows u sin g In tel p rocessors. A slan g term for th e PC stan d ard . w i re f ra m e s Th e m ost com m on tech n iq u e u sed to con stru ct a th ree-d im en sion al object for an im ation . A wire fram e is given coord in ates of len gth , h eigh t, an d wid th . W ire fram es are th en filled with textu res, colors, an d m ovem en t. Tran sform in g a wire fram e in to a textu red object is called rendering. w o rd l e n g t h

Th e n u m ber of bits in a d ata ch aracter with ou t p arity, start, or stop bits.

W o rl d W i d e W e b Also called sim p ly th e W eb. A grap h ical in form ation system based on h yp ertext th at en ables a u ser to easily access d ocu m en ts located on th e In tern et. W ORM W rite On ce, Read Man y (or Mu ltip le). An op tical m ass-storage d evice cap able of storin g m an y m egabytes of in form ation bu t th at can be written to on ly on ce on an y given area of th e d isk. A W ORM d isk typ ically h old s m ore th an 200M of d ata. Becau se a W ORM d rive can n ot write over an old version of a file, n ew cop ies of files are m ad e an d stored on oth er p arts of th e d isk wh en ever a file is revised . W ORM d isks are u sed to store in form ation wh en a h istory of old er version s m u st be m ain tain ed . Record in g on a W ORM d isk is p erform ed by a laser writer th at bu rn s p its in a th in m etallic film (u su ally tellu riu m ) em bed d ed in th e d isk. Th is bu rn in g p rocess is called ablation. W ORM d rives are freq u en tly u sed for arch ivin g d ata. w ri t e p re c o m p e n sa t i o n A m od ification ap p lied to write d ata by a con troller to alleviate p artially th e p roblem of bit sh ift, wh ich cau ses ad jacen t 1s written on m agn etic m ed ia to read as th ou gh th ey were farth er ap art. W h en ad jacen t 1s are sen sed by th e con troller, p recom p en sation is u sed to write th em closer togeth er on th e d isk, th u s en ablin g th em to be read in th e p rop er bit cell win d ow. Drives with bu ilt-in con trollers n orm ally h an d le p recom p en sation au tom atically. Precom p en sation n orm ally is req u ired for th e in n er cylin d ers of oxid e m ed ia d rives. w ri t e p ro t e c t Preven tin g a rem ovable d isk from bein g overwritten by m ean s of coverin g a n otch or rep osition in g a slid in g switch , d ep en d in g on th e typ e of m ed ia.

Glossary

X2

A p rop rietary m od em stan d ard d evelop ed by U.S. Robotics (sin ce acq u ired by 3Com ) th at allows m od em s to receive d ata at u p to 56Kbp s. Th is h as been su p ersed ed by th e V.90 stan d ard . See also X 2 an d V .90.

x86

A gen eric term referrin g to In tel an d In tel-com p atible PC m icrop rocessors. Alth ou gh th e Pen tiu m , Pen tiu m Pro, an d Pen tiu m II d o n ot h ave a n u m eric d esign ation d u e to trad em ark law, th ey are later gen eration s of th is fam ily.

XGA

eXten d ed Grap h ics Array. A typ e of PC vid eo d isp lay circu it (an d ad ap ter) first in trod u ced by IBM on October 30, 1990, th at su p p orts text an d grap h ics. Text is su p p orted at a m axim u m resolu tion of 132×60 ch aracters in 16 colors with a ch aracter box of 8×6 p ixels. Grap h ics is su p p orted at a m axim u m resolu tion of 1024×768 p ixels in 256 (from a p alette of 262,144) colors or 640×480 p ixels in 65,536 colors. Th e XGA ou tp u ts an an alog sign al with a h orizon tal scan n in g freq u en cy of 31.5 or 35.52KHz an d su p p orts an alog color or an alog m on och rom e d isp lays.

XMM eXten d ed Mem ory Man ager. A d river th at con trols access to exten d ed m em ory on 286 an d later p rocessor system s. HIMEM.SYS is an exam p le of an XMM th at com es with DOS. Xm o d e m A file-tran sfer p rotocol—with error ch eckin g—d evelop ed by W ard Ch risten sen in th e m id -1970s an d p laced in th e p u blic d om ain . Design ed to tran sfer files between m ach in es ru n n in g th e CP/ M op eratin g system an d u sin g 300 or 1,200 bp s m od em s. Un til th e late 1980s, becau se of its sim p licity an d p u blicd om ain statu s, Xm od em rem ain ed th e m ost wid ely u sed m icrocom p u ter filetran sfer p rotocol. In stan d ard Xm od em , th e tran sm itted blocks are 128 bytes. 1K-Xm od em is an exten sion to Xm od em th at in creases th e block size to 1,024 bytes. Man y n ewer file-tran sfer p rotocols th at are m u ch faster an d m ore accu rate th an Xm od em h ave been d evelop ed , su ch as Ym od em an d Zm od em . XMS

eXten d ed Mem ory Sp ecification . A Microsoft-d evelop ed stan d ard th at p rovid es a way for real-m od e ap p lication s to access exten d ed m em ory in a con trolled fash ion . Th e XMS stan d ard is available from Microsoft.

XON/ XOFF Stan d ard ASCII con trol ch aracters u sed to tell an in telligen t d evice to stop or resu m e tran sm ittin g d ata. In m ost system s, typ in g Ctrl+S sen d s th e XOFF ch aracter. Most d evices u n d erstan d Ctrl+Q as XON; oth ers in terp ret th e p ressin g of an y key after Ctrl+S as XON. Y-c o n n e c t o r sign als.

A Y-sh ap ed sp litter cable th at d ivid es a sou rce in p u t in to two ou tp u t

Ye l l o w Bo o k Th e stan d ard u sed by Com p act Disc-Read On ly Mem ory (CD-ROM). Mu ltim ed ia ap p lication s m ost com m on ly u se th e Yellow Book stan d ard , wh ich sp ecifies h ow d igital in form ation is to be stored on th e CD-ROM an d read by a com p u ter. EXten d ed Arch itectu re (XA) is cu rren tly an exten sion of th e Yellow Book th at allows for th e com bin ation of d ifferen t d ata typ es (au d io an d vid eo, for exam p le) on to on e track in a CD-ROM. W ith ou t XA, a CD-ROM can access on ly on e d ata typ e at a tim e. Man y CD-ROM d rives are n ow XA cap able. Ye l l o w Bo o k st a n d a rd s

See CD-ROM.

1323

1324

Glossary

Ym o d e m A file-tran sfer p rotocol first released as p art of Ch u ck Forsberg’s YAM (yet an oth er m od em ) p rogram . An exten sion to Xm od em d esign ed to overcom e som e of th e lim itation s of th e origin al. En ables in form ation abou t th e tran sm itted file, su ch as th e file n am e an d len gth , to be sen t alon g with th e file d ata an d in creases th e size of a block from 128 to 1,024 bytes. Ym od em -batch ad d s th e cap ability to tran sm it “batch es” or grou p s of files with ou t op erator in terru p tion . Ym od em G is a variation th at sen d s th e en tire file before waitin g for an ackn owled gm en t. If th e receivin g sid e d etects an error in m id stream , th e tran sfer is aborted . Ym od em G is d esign ed for u se with m od em s th at h ave bu ilt-in error-correctin g cap abilities. ZIF Zero In sertion Force. Sockets th at req u ire n o force for th e in sertion of a ch ip carrier. Usu ally accom p lish ed th rou gh m ovable con tacts an d u ses p rim arily 486, Pen tiu m , an d Pen tiu m Pro p rocessor system s. ZIP

Zigzag In lin e Package. A DIP p ackage th at h as all lead s on on e ed ge in a zigzag p attern an d m ou n ts in a vertical p lan e.

z i p d ri v e An extern al d rive m an u factu red by Iom ega th at su p p orts 100M m agn etic m ed ia on a 3 1/ 2-in ch rem ovable d rive. Zm o d e m A file-tran sfer p rotocol com m ission ed by Telen et an d p laced in th e p u blic d om ain . Like Ym od em , it was d esign ed by Ch u ck Forsberg an d d evelop ed as an exten sion to Xm od em to overcom e th e in h eren t laten cy wh en u sin g Sen d / Ack-based p rotocols su ch as XMod em an d YMod em . It is a stream in g, slid in gwin d ow p rotocol. z o n e d re c o rd i n g In h ard d rives, a way to in crease th e cap acity of a h ard d rive is to form at m ore sectors on th e ou ter cylin d ers th an on th e in n er on es. Zon ed record in g sp lits th e cylin d ers in to grou p s called zon es, with each su ccessive zon e h avin g m ore an d m ore sectors p er track as you m ove ou t from th e in n er rad iu s of th e d isk. All th e cylin d ers in a p articu lar zon e h ave th e sam e n u m ber of sectors p er track. z o o m e d v i d e o A d irect vid eo bu s con n ection between th e PC Card ad ap ter an d a m obile system ’s VGA con troller, allowin g h igh -sp eed vid eo d isp lays for vid eocon feren cin g ap p lication s an d MPEG d ecod ers.

D

1325

Appendix D

Technical Reference

General Inform at ion

ASCII Charact er Code Chart s Figu re D.1 lists ASCII con trol ch aracter valu es. Figu re D.2 sh ows th e IBM exten d ed ASCII lin e-d rawin g ch aracters in an easy-to-u se form at. I freq u en tly u se th ese exten d ed ASCII lin e-d rawin g ch aracters for visu al en h an cem en t in d ocu m en ts I create. DEC 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

HEX 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1FA

CHAR

o

o

!!

FIG. D.1 ASCII con trol cod es.

NAME Ctrl-@ Ctrl-A Ctrl-B Ctrl-C Ctrl-D Ctrl-E Ctrl-F Ctrl-G Ctrl-H Ctrl-I Ctrl-J Ctrl-K Ctrl-L Ctrl-M Ctrl-N Ctrl-O Ctrl-P Ctrl-Q Ctrl-R Ctrl-S Ctrl-T Ctrl-U Ctrl-V Ctrl-W Ctrl-X Ctrl-Y Ctrl-Z Ctrl-[ Ctrl-\ Ctrl-] Ctrl-^ Ctrl-_

CONTROL CODE NUL SOH STX ETX EOT ENQ ACK BEL BS HT LF VT FF CR SO SI DLE DC1 DC2 DC3 DC4 NAK SYN ETB CAN EM SUB ESC FS GS RS US

Null Start of Heading Start of Text End of Text End of Transit Enquiry Acknowledge Bell Back Space Horizontal Tab Line Feed Vertical Tab Form Feed Carriage Return Shift Out Shift In Data Line Escape Device Control 1 Device Control 2 Device Control 3 Device Control 4 Negative Acknowledge Synchronous Idle End of Transmit Block Cancel End of Medium Substitute Escape File Separator Group Separator Record Separator Unit Separator

1326

Appendix D—Technical Reference

218 DA

195 C3

191 C2 196 C4

179 B3

197 C5

192 C0

213 D5 198 C6

193 C1

209 D1 205 CD

179 B3

216 D8

212 D4

207 CF

191 BF

201 C9

180 B4

204 CC

217 D9

200 C8

184 B8

214 D6

181 B5

199 C7

190 BE

211 D3

203 CB 205 CD 186 BA

206 CE 202 CA

210 D2 196 C4

186 BA

215 D7 208 D0

187 BB 185 B9 188 BC

183 B7 182 B6

176

B0

177

B1

178

B2

219

DB

220

DC

221

DD

222

DE

223

DF

254

FE

189 BD

FIG. D.2 Exten d ed ASCII lin e-d rawin g ch aracters. Hexadecim al/ ASCII Conversions Table D.1

Hexadecim al/ ASCII Conversions

Dec

Hex

Oct al

Binary

Nam e

Charact er

0

00

000

0000 0000

blank

1

01

001

0000 0001

happy face

A

2

02

002

0000 0010

inverse happy face

B

3

03

003

0000 0011

heart

♥

4

04

004

0000 0100

diamond

♦

5

05

005

0000 0101

club

♣

6

06

006

0000 0110

spade

♠

7

07

007

0000 0111

bullet

•

8

08

010

0000 1000

inverse bullet

H

9

09

011

0000 1001

circle

o

10

0A

012

0000 1010

inverse circle

•

11

0B

013

0000 1011

m ale sign

K

12

0C

014

0000 1100

female sign

L

13

0D

015

0000 1101

single note

M

14

0E

016

0000 1110

double note

N

15

0F

017

0000 1111

sun

O

16

10

020

0001 0000

right triangle

17

11

021

0001 0001

left triangle

P Q

18

12

022

0001 0010

up/ down arrow

↕

19

13

023

0001 0011

double exclam ation

!!

20

14

024

0001 0100

paragraph sign

¶

General Information

Dec

Hex

Oct al

Binary

Nam e

Charact er

21

15

025

0001 0101

section sign

§

22

16

026

0001 0110

rectangular bullet

■

23

17

027

0001 0111

up/ down to line

↕

24

18

030

0001 1000

up arrow

↑

25

19

031

0001 1001

down arrow

↓

26

1A

032

0001 1010

right arrow

→

27

1B

033

0001 1011

left arrow

←

28

1C

034

0001 1100

lower left box

¿

29

1D

035

0001 1101

left/ right arrow

↔

30

1E

036

0001 1110

up triangle

31

1F

037

0001 1111

down triangle

32

20

040

0010 0000

space

Space

33

21

041

0010 0001

exclamation point

!

34

22

042

0010 0010

quotation mark

“

35

23

043

0010 0011

num ber sign

#

36

24

044

0010 0100

dollar sign

$

37

25

045

0010 0101

percent sign

%

38

26

046

0010 0110

am persand

&

d e

39

27

047

0010 0111

apostrophe

‘

40

28

050

0010 1000

opening parenthesis

(

41

29

051

0010 1001

closing parenthesis

)

42

2A

052

0010 1010

asterisk

*

43

2B

053

0010 1011

plus sign

+

44

2C

054

0010 1100

com m a

,

45

2D

055

0010 1101

hyphen or minus sign

-

46

2E

056

0010 1110

period

.

47

2F

057

0010 1111

slash

/

48

30

060

0011 0000

zero

0

49

31

061

0011 0001

one

1

50

32

062

0011 0010

two

2

51

33

063

0011 0011

three

3

52

34

064

0011 0100

four

4

53

35

065

0011 0101

five

5

54

36

066

0011 0110

six

6

55

37

067

0011 0111

seven

7

56

38

070

0011 1000

eight

8

57

39

071

0011 1001

nine

9

58

3A

072

0011 1010

colon

:

59

3B

073

0011 1011

sem icolon

;

60

3C

074

0011 1100

less-than sign

< (continues)

1327

1328

Appendix D—Technical Reference

Table D.1 Dec

Hexadecim al/ ASCII Conversions Cont inued

Hex

Oct al

Binary

Nam e

Charact er

61

3D

075

0011 1101

equal sign

=

62

3E

076

0011 1110

greater-than sign

>

63

3F

077

0011 1111

question mark

?

64

40

100

0100 0000

at sign

@

65

41

101

0100 0001

capital A

A

66

42

102

0100 0010

capital B

B

67

43

103

0100 0011

capital C

C

68

44

104

0100 0100

capital D

D

69

45

105

0100 0101

capital E

E

70

46

106

0100 0110

capital F

F

71

47

107

0100 0111

capital G

G

72

48

110

0100 1000

capital H

H

73

49

111

0100 1001

capital I

I

74

4A

112

0100 1010

capital J

J

75

4B

113

0100 1011

capital K

K

76

4C

114

0100 1100

capital L

L

77

4D

115

0100 1101

capital M

M

78

4E

116

0100 1110

capital N

N

79

4F

117

0100 1111

capital O

O

80

50

120

0101 0000

capital P

P

81

51

121

0101 0001

capital Q

Q

82

52

122

0101 0010

capital R

R

83

53

123

0101 0011

capital S

S

84

54

124

0101 0100

capital T

T

85

55

125

0101 0101

capital U

U

86

56

126

0101 0110

capital V

V

87

57

127

0101 0111

capital W

W

88

58

130

0101 1000

capital X

X

89

59

131

0101 1001

capital Y

Y

90

5A

132

0101 1010

capital Z

Z

91

5B

133

0101 1011

opening bracket

[

92

5C

134

0101 1100

backward slash

\

93

5D

135

0101 1101

closing bracket

]

94

5E

136

0101 1110

caret

^

95

5F

137

0101 1111

underscore

_

96

60

140

0110 0000

grave

`

97

61

141

0110 0001

lowercase A

a

98

62

142

0110 0010

lowercase B

b

99

63

143

0110 0011

lowercase C

c

General Information

Dec

Hex

Oct al

Binary

Nam e

Charact er

100

64

144

0110 0100

lowercase D

d

101

65

145

0110 0101

lowercase E

e

102

66

146

0110 0110

lowercase F

f

103

67

147

0110 0111

lowercase G

g

104

68

150

0110 1000

lowercase H

h

105

69

151

0110 1001

lowercase I

i

106

6A

152

0110 1010

lowercase J

j

107

6B

153

0110 1011

lowercase K

k

108

6C

154

0110 1100

lowercase L

l

109

6D

155

0110 1101

lowercase M

m

110

6E

156

0110 1110

lowercase N

n

111

6F

157

0110 1111

lowercase O

o

112

70

160

0111 0000

lowercase P

p

113

71

161

0111 0001

lowercase Q

q

114

72

162

0111 0010

lowercase R

r

115

73

163

0111 0011

lowercase S

s

116

74

164

0111 0100

lowercase T

t

117

75

165

0111 0101

lowercase U

u

118

76

166

0111 0110

lowercase V

v

119

77

167

0111 0111

lowercase W

w

120

78

170

0111 1000

lowercase X

x

121

79

171

0111 1001

lowercase Y

y

122

7A

172

0111 1010

lowercase Z

z

123

7B

173

0111 1011

opening brace

{

124

7C

174

0111 1100

vertical line

|

125

7D

175

0111 1101

closing brace

}

126

7E

176

0111 1110

tilde

~

127

7F

177

0111 1111

sm all house

f

128

80

200

1000 0000

C cedilla

Ç

129

81

201

1000 0001

u um laut

ü

130

82

202

1000 0010

e acute

é

131

83

203

1000 0011

a circum flex

â

132

84

204

1000 0100

a um laut

ä

133

85

205

1000 0101

a grave

à

134

86

206

1000 0110

a ring

å

135

87

207

1000 0111

c cedilla

ç

136

88

210

1000 1000

e circum flex

ê

137

89

211

1000 1001

e um laut

ë

138

8A

212

1000 1010

e grave

è

139

8B

213

1000 1011

I um laut

Ï (continues)

1329

1330

Appendix D—Technical Reference

Table D.1

Hexadecim al/ ASCII Conversions Cont inued

Dec

Hex

Oct al

Binary

Nam e

Charact er

140

8C

141

8D

214

1000 1100

I circumflex

Î

215

1000 1101

I grave

142

8E

216

Ì

1000 1110

A umlaut

Ä

143

8F

144

90

217

1000 1111

A ring

Å

220

1001 0000

E acute

É

145

91

221

146

92

222

1001 0001

ae ligature

æ

1001 0010

AE ligature

Æ

147

93

148

94

223

1001 0011

o circum flex

ô

224

1001 0100

o um laut

ö

149 150

95

225

1001 0101

o grave

ò

96

226

1001 0110

u circum flex

û

151

97

227

1001 0111

u grave

ù

152

98

230

1001 1000

y um laut

ÿ

153

99

231

1001 1001

O um laut

Ö

154

9A

232

1001 1010

U um laut

Ü

155

9B

233

1001 1011

cent sign

¢

156

9C

234

1001 1100

pound sign

£

157

9D

235

1001 1101

yen sign

¥

158

9E

236

1001 1110

Pt

û

159

9F

237

1001 1111

function

ƒ

160

A0

240

1010 0000

a acute

á

161

A1

241

1010 0001

I acute

Í

162

A2

242

1010 0010

o acute

ó

163

A3

243

1010 0011

u acute

ú

164

A4

244

1010 0100

n tilde

ñ

165

A5

245

1010 0101

N tilde

166

A6

246

1010 0110

a m acron

167

A7

247

1010 0111

o m acron

Ñ _ a _ o

168

A8

250

1010 1000

opening question mark

¿

169

A9

251

1010 1001

upper-left box

⁄

170

AA

252

1010 1010

upper-right box

ø

171

AB

253

1010 1011

1/ 2

1

⁄2

172

AC

254

1010 1100

1/ 4

1

⁄4

173

AD

255

1010 1101

opening exclamation

¡

174

AE

256

1010 1110

opening guillemets

«

175

AF

257

1010 1111

closing guillemets

»

176

B0

260

1011 0000

light block

177

B1

261

1011 0001

m edium block

178

B2

262

1011 0010

dark block

179

B3

263

1011 0011

single vertical

≥

General Information

Dec

Hex

Oct al

Binary

Nam e

Charact er

180

B4

264

181

B5

265

1011 0100

single right junction

¥

1011 0101

2 to 1 right junction

µ

182

B6

183

B7

266

1011 0110

1 to 2 right junction

∂

267

1011 0111

1 to 2 upper-right

184

∑

B8

270

1011 1000

2 to 1 upper-right

185

∏

B9

271

1011 1001

double right junction

π

186

BA

272

1011 1010

double vertical

∫

187

BB

273

1011 1011

double upper-right

ª

188

BC

274

1011 1100

double lower-right

º

189

BD

275

1011 1101

1 to 2 lower-right

Ω

190

BE

276

1011 1110

2 to 1 lower-right

æ

191

BF

277

1011 1111

single upper-right

ø

192

C0

300

1100 0000

single lower-left

¿

193

C1

301

1100 0001

single lower junction

¡

194

C2

302

1100 0010

single upper junction

¬

195

C3

303

1100 0011

single left junction

√

196

C4

304

1100 0100

single horizontal

ƒ

197

C5

305

1100 0101

single intersection

≈

198

C6

306

1100 0110

2 to 1 left junction

∆

199

C7

307

1100 0111

1 to 2 left junction

«

200

C8

310

1100 1000

double lower-left

»

201

C9

311

1100 1001

double upper-left

…

202

CA

312

1100 1010

double lower junction

g

203

CB

313

1100 1011

double upper junction

“

204

CC

314

1100 1100

double left junction

Ã

205

CD

315

1100 1101

double horizontal

=

206

CE

316

1100 1110

double intersection

Œ

207

CF

317

1100 1111

1 to 2 lower junction

œ

208

D0

320

1101 0000

2 to 1 lower junction

–

209

D1

321

1101 0001

1 to 2 upper junction

—

210

D2

322

1101 0010

2 to 1 upper junction

“

211

D3

323

1101 0011

1 to 2 lower-left

”

212

D4

324

1101 0100

2 to 1 lower-left

‘

213

D5

325

1101 0101

2 to 1 upper-left

’

214

D6

326

1101 0110

1 to 2 upper-left

÷

215

D7

327

1101 0111

2 to 1 intersection

◊

216

D8

330

1101 1000

1 to 2 intersection

ÿ

217

D9

331

1101 1001

single lower-right

218

DA

332

1101 1010

single upper-right

⁄

219

DB

333

1101 1011

inverse space

¤

Ÿ

(continues)

1331

1332

Appendix D—Technical Reference

Table D.1

Hexadecim al/ ASCII Conversions Cont inued

Dec

Hex

Oct al

Binary

Nam e

Charact er

220

DC

334

1101 1100

lower inverse

‹

221

DD

335

1101 1101

left inverse

›

222

DE

336

1101 1110

right inverse

fi

223

DF

337

1101 1111

upper inverse

fl

224

E0

340

1110 0000

alpha

α

225

E1

341

1110 0001

beta

β

226

E2

342

1110 0010

Gamma

Γ

227

E3

343

1110 0011

pi

π

228

E4

344

1110 0100

Sigma

Σ

229

E5

345

1110 0101

sigma

σ

230

E6

346

1110 0110

mu

µ

231

E7

347

1110 0111

tau

τ

232

E8

350

1110 1000

Phi

Φ

233

E9

351

1110 1001

theta

θ

234

EA

352

1110 1010

Om ega

Ω

235

EB

353

1110 1011

delta

δ

236

EC

354

1110 1100

infinity

∞

237

ED

355

1110 1101

phi

φ

238

EE

356

1110 1110

epsilon

ε

239

EF

357

1110 1111

intersection of sets

Ô

240

F0

360

1111 0000

is identical to



241

F1

361

1111 0001

plus/ minus sign

±

242

F2

362

1111 0010

greater/ equal sign

Ú

243

F3

363

1111 0011

less/ equal sign

Û

244

F4

364

1111 0100

top half integral

Ù

245

F5

365

1111 0101

lower half integral

ı

246

F6

366

1111 0110

division sign

ˆ

247

F7

367

1111 0111

approximately

˜

248

F8

370

1111 1000

degree

¯

249

F9

371

1111 1001

filled-in degree

˘

250

FA

372

1111 1010

small bullet

˙

251

FB

373

1111 1011

square root

˚

252

FC

374

1111 1100

superscript n

¸

253

FD

375

1111 1101

superscript 2

˝

254

FE

376

1111 1110

box

˛

255

FF

377

1111 1111

phantom space

ˇ

General Information

Ext ended ASCII Keycodes for ANSI.SYS Table D.2

Ext ended ASCII Keycodes for ANSI.SYS

Code

Keyst roke

Code

Keyst roke

Code

Keyst roke

0;1

Esc

0;53

/

0;98

0;3

Null Character

0;55

Keypad *

0;99

F6

0;14

Backspace

0;59

F1

0;100

F7

0;15

Tab

0;60

F2

0;101

F8

0;16

Q

0;61

F3

0;102

F9

0;17

W

0;62

F4

0;103

F10

0;18

E

0;63

F5

0;104

F1

0;19

R

0;64

F6

0;105

F2

0;20

T

0;65

F7

0;106

F3

0;21

Y

0;66

F8

0;107

F4

0;22

U

0;67

F9

0;108

F5

0;23

I

0;68

F10

0;109

F6

0;24

O

0;71

Home

0;110

F7

0;25

P

0;72

Up Arrow

0;111

F8

0;26

[

0;73

Page Up

0;112

F9

0;27

]

0;74

Keypad -

0;113

F10

0;28

Enter

0;75

Left Arrow

0;114

Print Screen

0;30

A

0;76

Keypad 5

0;115

Left Arrow

0;31

S

0;77

Right Arrow

0;116

Right Arrow

0;32

D

0;78

Keypad +

0;117

End

0;33

F

0;79

End

0;118

Page Down

0;34

G

0;80

Down Arrow

0;119

Home

0;35

H

0;81

Page Down

0;120

1

0;36

J

0;82

Insert

0;121

2

0;37

K

0;83

Delete

0;122

3

0;38

L

0;84

F1

0;123

4

0;39

;

0;85

F2

0;124

5

0;40

‘

0;86

F3

0;125

6

0;41

‘

0;87

F4

0;126

7

0;43

\

0;88

F5

0;127

8

0;44

Z

0;89

F6

0;128

9

0;45

X

0;90

F7

0;129

0

0;46

C

0;91

F8

0;130

-

0;47

V

0;92

F9

0;131

=

0;48

B

0;93

F10

0;132

Page Up

0;49

N

0;94

F1

0;133

F11

0;50

M

0;95

F2

0;134

F12

0;51

,

0;96

F3

0;135

F11

0;52

.

0;97

F4

0;136

F12

F5

(continues)

1333

1334

Appendix D—Technical Reference

Table D.2

Ext ended ASCII Keycodes for ANSI.SYS Cont inued

Code

Keyst roke

Code

Keyst roke

Code

Keyst roke

0;137

F11

0;146

Insert

0;157

Right Arrow

0;138

F12

0;147

Delete

0;159

End

0;139

F11

0;148

Tab

0;160

Down Arrow

0;140

F12

0;149

Keypad /

0;161

Page Down

0;141

Up Arrow

0;150

Keypad *

0;162

Insert

0;142

Keypad -

0;151

Home

0;163

Delete

0;143

Keypad 5

0;152

Up Arrow

0;164

Keypad /

0;144

Keypad +

0;153

Page Up

0;165

Tab

0;145

Down Arrow

0;155

Left Arrow

0;166

Keypad Enter

EBCDIC Charact er Codes Table D.3

EBCDIC Charact er Codes

Dec

Hex

Oct al

Binary

Nam e

0

00

000

0000 0000

NUL

1

01

001

0000 0001

SOH

2

02

002

0000 0010

STX

3

03

003

0000 0011

ETX

4

04

004

0000 0100

SEL

5

05

005

0000 0101

HT

6

06

006

0000 0110

RNL

7

07

007

0000 0111

DEL

8

08

010

0000 1000

GE

9

09

011

0000 1001

SPS

10

0A

012

0000 1010

RPT

11

0B

013

0000 1011

VT

12

0C

014

0000 1100

FF

13

0D

015

0000 1101

CR

14

0E

016

0000 1110

SO

15

0F

017

0000 1111

SI

16

10

020

0001 0000

DLE

17

11

021

0001 0001

DC1

18

12

022

0001 0010

DC2

19

13

023

0001 0011

DC3

20

14

024

0001 0100

RES/ ENP

21

15

025

0001 0101

NL

22

16

026

0001 0110

BS

23

17

027

0001 0111

POC

24

18

030

0001 1000

CAN

Charact er

General Information

Dec

Hex

Oct al

Binary

Nam e

25 26

19

031

0001 1001

EM

1A

032

0001 1010

UBS

27

1B

033

0001 1011

CU1

28

1C

034

0001 1100

IFS

29

1D

035

0001 1101

IGS

30

1E

036

0001 1110

IRS

31

1F

037

0001 1111

IUS/ ITB

32

20

040

0010 0000

DS

33

21

041

0010 0001

SOS

34

22

042

0010 0010

FS

35

23

043

0010 0011

WUS

36

24

044

0010 0100

BYP/ INP

37

25

045

0010 0101

LF

38

26

046

0010 0110

ETB

39

27

047

0010 0111

ESC

40

28

050

0010 1000

SA

41

29

051

0010 1001

SFE

42

2A

052

0010 1010

SM / SW

43

2B

053

0010 1011

CSP

44

2C

054

0010 1100

M FA

45

2D

055

0010 1101

ENQ

46

2E

056

0010 1110

ACK

47

2F

057

0010 1111

BEL

48

30

060

0011 0000

49

31

061

0011 0001

50

32

062

0011 0010

SYN

51

33

063

0011 0011

IR

52

34

064

0011 0100

PP

53

35

065

0011 0101

TRN

54

36

066

0011 0110

NBS

55

37

067

0011 0111

EOT

56

38

070

0011 1000

SBS

57

39

071

0011 1001

IT

58

3A

072

0011 1010

RFF

59

3B

073

0011 1011

CU3

60

3C

074

0011 1100

DC4

61

3D

075

0011 1101

NAK

62

3E

076

0011 1110

63

3F

077

0011 1111

Charact er

SUB (continues)

1335

1336

Appendix D—Technical Reference

Table D.3

EBCDIC Charact er Codes Cont inued

Dec

Hex

Oct al

Binary

Nam e

Charact er

64

40

100

0100 0000

SP

65

41

101

0100 0001

RSP

66

42

102

0100 0010

67

43

103

0100 0011

68

44

104

0100 0100

69

45

105

0100 0101

70

46

106

0100 0110

71

47

107

0100 0111

72

48

110

0100 1000

73

49

111

0100 1001

74

4A

112

0100 1010

75

4B

113

0100 1011

.

76

4C

114

0100 1100




111

6F

157

0110 1111

?

112

70

160

0111 0000

113

71

161

0111 0001

114

72

162

0111 0010

115

73

163

0111 0011

116

74

164

0111 0100

117

75

165

0111 0101

118

76

166

0111 0110

119

77

167

0111 0111

120

78

170

0111 1000

121

79

171

0111 1001

`

122

7A

172

0111 1010

:

123

7B

173

0111 1011

#

124

7C

174

0111 1100

@

125

7D

175

0111 1101

'

126

7E

176

0111 1110

=

127

7F

177

0111 1111

"

128

80

200

1000 0000

129

81

201

1000 0001

a

130

82

202

1000 0010

b

131

83

203

1000 0011

c

132

84

204

1000 0100

d

133

85

205

1000 0101

e

134

86

206

1000 0110

f

135

87

207

1000 0111

g

136

88

210

1000 1000

h

137

89

211

1000 1001

i

138

8A

212

1000 1010

139

8B

213

1000 1011

140

8C

214

1000 1100

141

8D

215

1000 1101

142

8E

216

1000 1110 (continues)

1337

1338

Appendix D—Technical Reference

Table D.3

EBCDIC Charact er Codes Cont inued

Dec

Hex

Oct al

Binary

Nam e

Charact er

143

8F

217

1000 1111

144

90

220

1001 0000

145

91

221

1001 0001

j

146

92

222

1001 0010

k

147

93

223

1001 0011

l

148

94

224

1001 0100

m

149

95

225

1001 0101

n

150

96

226

1001 0110

o

151

97

227

1001 0111

p

152

98

230

1001 1000

q

153

99

231

1001 1001

r

154

9A

232

1001 1010

155

9B

233

1001 1011

156

9C

234

1001 1100

157

9D

235

1001 1101

158

9E

236

1001 1110

159

9F

237

1001 1111

160

A0

240

1010 0000

161

A1

241

1010 0001

~

162

A2

242

1010 0010

s

163

A3

243

1010 0011

t

164

A4

244

1010 0100

u

165

A5

245

1010 0101

v

166

A6

246

1010 0110

w

167

A7

247

1010 0111

x

168

A8

250

1010 1000

y

169

A9

251

1010 1001

z

170

AA

252

1010 1010

171

AB

253

1010 1011

172

AC

254

1010 1100

173

AD

255

1010 1101

174

AE

256

1010 1110

175

AF

257

1010 1111

176

B0

260

1011 0000

177

B1

261

1011 0001

178

B2

262

1011 0010

179

B3

263

1011 0011

180

B4

264

1011 0100

181

B5

265

1011 0101

General Information

Dec

Hex

Oct al

Binary

Nam e

Charact er

182

B6

266

1011 0110

183

B7

267

1011 0111

184

B8

270

1011 1000

185

B9

271

1011 1001

186

BA

272

1011 1010

187

BB

273

1011 1011

188

BC

274

1011 1100

189

BD

275

1011 1101

190

BE

276

1011 1110

191

BF

277

1011 1111

192

C0

300

1100 0000

{

193

C1

301

1100 0001

A

194

C2

302

1100 0010

B

195

C3

303

1100 0011

C

196

C4

304

1100 0100

D

197

C5

305

1100 0101

E

198

C6

306

1100 0110

F

199

C7

307

1100 0111

G

200

C8

310

1100 1000

H

201

C9

311

1100 1001

202

CA

312

1100 1010

203

CB

313

1100 1011

204

CC

314

1100 1100

205

CD

315

1100 1101

206

CE

316

1100 1110

207

CF

317

1100 1111

208

D0

320

1101 0000

}

209

D1

321

1101 0001

J

210

D2

322

1101 0010

K

211

D3

323

1101 0011

L

212

D4

324

1101 0100

M

213

D5

325

1101 0101

N

214

D6

326

1101 0110

O

215

D7

327

1101 0111

P

216

D8

330

1101 1000

Q

217

D9

331

1101 1001

R

218

DA

332

1101 1010

219

DB

333

1101 1011

220

DC

334

1101 1100

221

DD

335

1101 1101

I SHY

(continues)

1339

1340

Appendix D—Technical Reference

Table D.3

EBCDIC Charact er Codes Cont inued

Dec

Hex

Oct al

Binary

Nam e

Charact er

222

DE

336

1101 1110

223

DF

337

1101 1111

224

E0

340

1110 0000

225

E1

341

1110 0001

226

E2

342

1110 0010

S

227

E3

343

1110 0011

T

228

E4

344

1110 0100

U

229

E5

345

1110 0101

V

230

E6

346

1110 0110

W

231

E7

347

1110 0111

X

232

E8

350

1110 1000

Y

233

E9

351

1110 1001

Z

234

EA

352

1110 1010

235

EB

353

1110 1011

236

EC

354

1110 1100

237

ED

355

1110 1101

238

EE

356

1110 1110

239

EF

357

1110 1111

240

F0

360

1111 0000

0

241

F1

361

1111 0001

1

242

F2

362

1111 0010

2

243

F3

363

1111 0011

3

244

F4

364

1111 0100

4

245

F5

365

1111 0101

5

246

F6

366

1111 0110

6

247

F7

367

1111 0111

7

248

F8

370

1111 1000

8

249

F9

371

1111 1001

9

250

FA

372

1111 1010

251

FB

373

1111 1011

252

FC

374

1111 1100

253

FD

375

1111 1101

254

FE

376

1111 1110

255

FF

377

1111 1111

\ NSP

EO

General Information

M et ric Syst em ( SI) Prefixes Table D.4

M et ric Syst em Prefixes

M ult iplier

Exponent Form

Prefix

SI Sym bol

1 000 000 000 000 000 000 000 000

10 24

yotta

Y

1 000 000 000 000 000 000 000

21

zetta

Z

10

1 000 000 000 000 000 000

10 18

exa

E

1 000 000 000 000 000

10 15

peta

P

1 000 000 000 000

10 12

tera

T

1 000 000 000

10

9

giga

G

mega

M

1 000 000

10 6

1 000

10 3

Kilo

k

100

10 2

hecto

h

10

10 1

deca

da

0.1

10 -1

deci

d

0.01

10 -2

centi

c

0.001

10 -3

milli

m

0.000 001

-6

0.000 000 001

10

10 -9

micro

µ

nano

n

0.000 000 000 001

10 -12

pico

p

0.000 000 000 000 001

10 -15

femto

f

0.000 000 000 000 000 001

10 -18

atto

a

0.000 000 000 000 000 000 001

10 -21

zepto

z

0.000 000 000 000 000 000 000 001

10 -24

yocto

y

U.S.—M et ric Unit s of Lengt h Conversions Table D.5

Conversions from U.S. t o M et ric

1 Inch = 2.54 centimeters = 25.4 millimeters 1 foot = 30.48 centimeters = .3048 meter 1 yard = .914 meter 1 mile = 1.609 kilometers

Table D.6

Conversions from M et ric t o U.S.

1 millimeter = .03937 inch 1 centimeter = .3937 inch 1 meter = 3.2808 feet = 1.0936 yards = 39.37 inches 1 kilometer = .621 mile

1341

1342

Appendix D—Technical Reference

Pow ers of 2 Table D.7

Pow ers of 2 n

Hexadecim al

0

1

1

1

2

2

2

4

4

3

8

8

4

16

10

5

32

20

6

64

40

7

128

80

8

256

100

n

9

2

512

200

10

1,024

400

11

2,048

800

12

4,096

1000

13

8,192

2000

14

16,384

4000

15

32,768

8000

16

65,536

10000

17

131,072

20000

18

262,144

40000

19

524,288

80000

20

1,048,576

100000

21

2,097,152

200000

22

4,194,304

400000

23

8,388,608

800000

24

16,777,216

1000000

25

33,554,432

2000000

26

67,108,864

4000000

27

134,217,728

8000000

28

268,435,456

10000000

29

536,870,912

20000000

30

1,073,741,824

40000000

31

2,147,483,648

80000000

32

4,294,967,296

100000000

33

8,589,934,592

200000000

34

17,179,869,184

400000000

35

34,359,738,368

800000000

36

68,719,476,736

1000000000

37

137,438,953,472

2000000000

General Information

n

Hexadecim al

38

274,877,906,944

4000000000

39

549,755,813,888

8000000000

40

1,099,511,627,776

10000000000

41

2,199,023,255,552

20000000000

42

4,398,046,511,104

40000000000

43

8,796,093,022,208

80000000000

44

17,592,186,044,416

100000000000

45

35,184,372,088,832

200000000000

46

70,368,744,177,664

400000000000

47

140,737,488,355,328

800000000000

48

281,474,976,710,656

1000000000000

49

562,949,953,421,312

2000000000000

50

1,125,899,906,842,624

4000000000000

51

2,251,799,813,685,248

8000000000000

52

4,503,599,627,370,496

10000000000000

53

9,007,199,254,740,992

20000000000000

54

18,014,398,509,481,984

40000000000000

55

36,028,797,018,963,968

80000000000000

n

2

56

72,057,594,037,927,936

100000000000000

57

144,115,188,075,855,872

200000000000000

58

288,230,376,151,711,744

400000000000000

59

576,460,752,303,423,488

800000000000000

60

1,152,921,504,606,846,976

1000000000000000

61

2,305,843,009,213,693,952

2000000000000000

62

4,611,686,018,427,387,904

4000000000000000

63

9,223,372,036,854,775,808

8000000000000000

64

18,446,744,073,709,551,616

10000000000000000

Elect rom agnet ic Spect rum Th e electrom agn etic sp ectru m p lays a cru cial role in m ost com p u ter tech n ologies. An obviou s ap p lication is th e ligh t in th e visible sp ectru m p rod u ced by a m on itor. In ad d ition , CD-ROM d rives u se ligh t in th e in frared region to read CDs; wireless keyboard s an d m ice u se in frared to com m u n icate with th e PC; wireless n etworks com m on ly u se a p ortion of th e UHF ban d at 2.4GHz; an d u ltraviolet ligh t is u sed in p h otolith ograp h y to create ch ip s on silicon wafers. Table D.8 lists all th e broad region s of th e electrom agn etic sp ectru m an d breaks th em d own in to th eir com m on ly n am ed ban d s. Th ere is som e overlap in th ese d efin ed region s.

1343

1344

Appendix D—Technical Reference

Table D.8

Regions of t he Elect rom agnet ic Spect rum

Broad Region

Band

Frequency ( Hz)

W avelengt h ( cm , m m , µm , nm )

ultra-low (ULF)

3–30Hz

10 7–10 8 m

extremely low (ELF)

30–300Hz

10 6–10 7 m

voice frequencies (VF)

300Hz–3KHz

10 5–10 6 m

very low (VLF)

3–30KHz

10 4–10 5 m

low (LF)

30–300KHz

10 3–10 4 m

medium (M F) (shortwave radio and AM radio)

300KHz–3M Hz

10 2–10 3 m

high (HF) (shortwave radio)

3–30M Hz

10–100 m

very high (VHF) (television and FM radio)

30–300M Hz

1–10 m

ultra high (UHF) (television)

300M Hz–3GHz

100 cm–1 m

super high (SHF)

3–30GHz

10–100 cm

extremely high (EHF)

30–300GHz

1- 10 cm

Radio Waves

microwave

1–300GHz

1 mm–30 cm

3 ×10 11 –4×10 14 Hz

0.75–1000 µm

red

3.9×10 14 –4.8×10 14Hz

622–770 nm

orange

4.8×10 14 –5×10 14 Hz

597–622 nm

yellow

5 ×10 14 –5.2×10 14Hz

577–597 nm

green

5.2× 10 14 –6.1×10 14Hz

492–577 nm

blue

6.1×10 14 –6.6×10 14Hz

455–492 nm

violet

6.6×10 14 –7.7×10 14Hz

390–455 nm

UV

7.5×10 14 –3×10 16 Hz

10–400 nm

UV-A

7.5×10 14 –9.4×10 14Hz

320–400 nm

UV-B

9.4×10 14 –1.1×10 15Hz

280–320 nm

10 16–10 21 Hz

3 ×10 –8–3 ×10 –13 m

Infrared Visible

Ultraviolet

X ray Gamma ray

18

23

10 –10 Hz

3 ×10 –10–3 ×10 –15 m

M odem Control Codes

M odem Cont rol Codes Th is section lists th e com m an d an d con trol cod es for p op u lar m od em s. Most m od em s u se a stan d ard AT com m an d set th at was d evelop ed by Hayes an d au gm en ted by U.S. Robotics. Table D.9 com es in h an d y wh en you n eed to recon figu re a m od em with ou t th e origin al m an u al. Even if you r m od em is n ot Hayes or U.S. Robotics, it p robably follows m ost of th ese com m an d s becau se th is com m an d set h as becom e som ewh at of a stan d ard . S-register valu es listed at th e en d of th e table are also som ewh at stan d ard bu t are m ore su bject to variation in th e d efau lts by bran d an d m od el. Table D.9

M odem AT Com m ands and S-Regist er Feat ures

Com m and

M odem Funct ions and Opt ions

&

See Extended Command Set

%

See Extended Command Set

A

Force Answer mode when modem has not received an incoming call

A/

Reexecute last command once

A>

Repeat last command continuously

Any key

Terminate current connection attempt; exit Repeat mode

AT

Attention: must precede all other commands, except A/ , A>, and +++

Bn

Cn

Dn

Handshake options B0

CCITT answer sequence

B1

Bell answer tone

Transmitter On/ Off C0

Transmitter Off

C1

Transmitter On—Default

Dial number n and go into originate mode Use any of these options: P

Pulse dial—Default

T

Touch-Tone dial

,

(Comma) Pause for 2 seconds

;

Return to command state after dialing

“…

Dial the letters that follow

!

Flash switch-hook to transfer call

W

Wait for 2nd dial tone (if X3 or higher is set)

@

Wait for an answer (if X3 or higher is set)

R Reverse frequencies S Dial stored number DL

Dial the last-dialed number

DSn

Dial number stored in NVRAM at position n

En

Fn

Command mode local echo; not applicable after a connection has been made E0

Echo Off

E1

Echo On

Local echo On/ Off when a connection has been made (continues)

1345

1346

Appendix D—Technical Reference

Table D.9 Com m and

Hn

In

Kn

Ln

Mn

O

M odem AT Com m ands and S-Regist er Feat ures Cont inued M odem Funct ions and Opt ions F0

Echo On (Half duplex)

F1

Echo Off (Full duplex)—Default

On/ Off hook control H0

Hang up (go on hook)—Default

H1

Go off hook

Inquiry I0

Return product code

I1

Return memory (ROM ) checksum

I2

Run memory (RAM ) test

I3

Return call duration/ real time

I4

Return current modem settings

I5

Return NVRAM settings

I6

Return link diagnostics

I7

Return product configuration

M odem clock operation K0

ATI3 displays call duration—Default

K1

ATI3 displays real time; set with ATI3=HH:M M :SSK1

Loudness of speaker volume L0

Low

L1

Low

L2

M edium

L3

High

M onitor (speaker) control M0

Speaker always Off

M1

Speaker On until carrier is established—Default

M2

Speaker always On

M3

Speaker On after last digit dialed, Off at carrier detect

Return on-line after command execution O0

Return on-line, normal

O1

Return on-line, retrain

P

Pulse dial

Qn

Result codes display

Sr=n

Q0

Result codes displayed

Q1

Result codes suppressed (quiet mode)

Q2

Quiet in answer mode only

Set Register commands: r is any S-register; n must be a decimal number between 0 and 255.

Sr.b=n

Set bit .b of register r to n (0/ Off or 1/ On)

Sr?

Query register r

M odem Control Codes

Com m and

M odem Funct ions and Opt ions

T

Tone dial

Vn

Verbal/ Numeric result codes V0

Numeric mode

V1

Verbal mode

Xn

Result code options

Yn

Long space disconnect Y0

Disabled

Y1

Enabled; disconnects after 1.5-second

break Z

Software reset

+++

Escape code sequence, preceded and followed by at least one second of no data transmission

/ (Slash)

Pause for 125 msec

>

Repeat command continuously or up to 10 dial attempts Cancel by pressing any key

$

Online Help—Basic command summary

&$

Online Help—Ampersand command summary

%$

Online Help—Percent command summary

D$

Online Help—Dial command summary

S$

Online Help—S-register summary

-S

Stop/ restart display of HELP screens

-C

Cancel display HELP screens

-K

Cancel display HELP screens

Ext ended Com m and Set & An

& Bn

& Cn

& Dn

ARQ result codes 14–17, 19 & A0

Suppress ARQ result codes

& A1

Display ARQ result codes —Default

& A2

Display HST and V.32 result codes

& A3

Display protocol result codes

Data Rate, terminal-to-modem (DTE/ DCE) & B0

DTE rate follows connection rate—Default

& B1

Fixed DTE rate

& B2

Fixed DTE rate in ARQ mode; variable DTE rate in non-ARQ mode

Carrier Detect (CD) operations & C0

CD override

& C1

Normal CD operations

Data Terminal Ready (DTR) operations & D0

DTR override

& D1

DTR Off; goes to command state

& D2

DTR Off; goes to command state and on hook

& D3

DTR Off; resets modem (continues)

1347

1348

Appendix D—Technical Reference

Table D.9 Com m and

M odem AT Com m ands and S-Regist er Feat ures Cont inued M odem Funct ions and Opt ions

&F

Load factory settings into RAM

& Gn

Guard tone

& Hn

& G0

No guard tone; U.S., Canada—Default

& G1

Guard tone; some European countries

& G2

Guard tone; U.K., requires B0

Transmit Data flow control & H0

& In

& Jn

& Kn

& Ln

& Mn

& Nn

Flow control disabled—Default

& H1

Hardware (CTS) flow control

& H2

Software (XON/ XOFF) flow control

& H3

Hardware and software control

Received Data software flow control & I0

Flow control disabled—Default

& I1

XON/ XOFF to local modem and remote computer

& I2

XON/ XOFF to local modem only

& I3

Host mode, Hewlett-Packard protocol

& I4

Terminal mode, Hewlett-Packard protocol

& I5

ARQ mode-same as & I2; non-ARQ mode; look for incoming XON/ XOFF

Telephone jack selection & J0

RJ-11/ RJ-41S/ RJ-45S

& J1

RJ-12/ RJ-13

Data compression & K0

Disabled

& K1

Auto enable/ disable—Default

& K2

Enabled

& K3

V.42bis only

Normal/ Leased line operation & L0

Normal phone line—Default

& L1

Leased line

Error Control/ Synchronous Options & M0

Normal mode, no error control

& M1

Synch mode

& M2

Synch mode 2—stored number dialing

& M3

Synch mode 3—manual dialing

& M4

Normal/ ARQ mode-Normal if ARQ connection cannot be made-Default

& M5

ARQ mode-hang up if ARQ connection cannot be made

Data Rate, data link (DCE/ DCE) & N0

Normal link operations—Default

& N1

300 bps

& N2

1200 bps

M odem Control Codes

Com m and

M odem Funct ions and Opt ions & N3

2400 bps

& N4

4800 bps

& N5

7200 bps

& N6

9600 bps

& N7

12K bps

& N8

14.4K bps

& Pn

Pulse dial make/ break ratio

& P0

North America—Default

& P1

British Commonwealth

& Rn

Received Data hardware (RTS) flow control & R0

CTS tracks RTS

& R1

Ignore RTS—Default

& R2

Pass received data on RTS high; used Pass received data on RTS high

Ext ended Com m and Set & Sn

& Tn

&W & Xn

& Yn

Data Set Ready (DSR) override & S0

DSR override (always On—Default)

& S1

M odem controls DSR

& S2

Pulsed DSR; CTS follows CD

& S3

Pulsed DSR

M odem Testing & T0

End testing

& T1

Analog loopback

& T2

Reserved

& T3

Digital loopback

& T4

Grant remote digital loopback

& T5

Deny remote digital loopback

& T6

Initiate remote digital loopback

& T7

Remote digital loopback with self-test

& T8

Analog loopback with self-test

Write current settings to NVRAM Synchronous timing source & X0

M odem’s transmit clock—Default

& X1

Terminal equipment

& X2

M odem’s receiver clock

Break handling. Destructive breaks clear the buffer; expedited Breaks are sent immediately to remote system. & Y0

Destructive, but don’t send break

& Y1

Destructive, expedited—Default

& Y2

Nondestructive, expedited

& Y3

Nondestructive, unexpedited (continues)

1349

1350

Appendix D—Technical Reference

Table D.9

M odem AT Com m ands and S-Regist er Feat ures Cont inued

Com m and

M odem Funct ions and Opt ions

& Zn=L

Store last-dialed phone number in NVRAM at position n

& Zn=s

Write phone number(s) to NVRAM at position n (0–3); 36 characters maximum

& Zn?

Display phone number in NVRAM at position n (n=0–3)

%Rn

Remote access to Rack Controller Unit (RCU)

%T

%R0

Disabled

%R1

Enabled

Enable Touch-Tone recognition

M odem S-Regist er Funct ions and Default s S0

Number of rings before automatic answering when DIP switch 5 is UP. Default = 1. S0 = 0 disables Auto Answer, equivalent to DIP switch 5 Down

S1

Counts and stores number of rings from incoming call

S2

Define escape code character. Default = +

S3

Define ASCII carriage return

S4

Define ASCII line feed

S5

Define ASCII Backspace

S6

Number of seconds modem waits before dialing

S7

Number of seconds modem waits for a carrier

S8

Duration (sec) for pause (,) option in Dial command and pause between command reexecutions for Repeat (>) command

S9

Duration (.1 sec units) of remote carrier signal before recognition

S10

Duration (.1 sec units) modem waits after loss of carrier before hanging up

S11

Duration and spacing (ms) of dialed Touch-Tones

S12

Guard time (in .02 sec units) for escape code sequence (+++)

S13

Bit-mapped register:

S15

1

Reset when DTR drops

2

Auto answer in originate mode

4

Disable result code pause

8

DS0 on DTR low-to-high

16

DS0 on power up, ATZ

32

Disable HST modulation

64

Disable M NP Level 3

128

Watchdog hardware reset

Bit-mapped register: 1

Disable high-frequency equalization

2

Disable on-line fallback

4

Force 300-bps back channel

8

Set non-ARQ transmit buffer to 128 bytes

16

Disable M NP Level 4

32

Set Del as Backspace key

M odem Control Codes

Com m and

S16

M odem Funct ions and Opt ions 64

Unusual M NP incompatibility

128

Custom applications only

Bit-mapped register: 1

Analog loopback

2

Dial test

4

Test pattern

8

Initiate remote digital loopback

16

Reserved

32

Reserved

64

Reserved

128

Reserved

S18

& Tn Test timer, disabled when set to 0

S19

Set inactivity timer in minutes

S21

Length of Break, DCE to DTE, in 10ms units

S22

Define ASCII XON

17

17

S23

Define ASCII XOFF

19

19

M odem S-Regist er Funct ions and Default s S24

Duration (20ms units) of pulsed DSR when modem is set to & S2 or & S3

S25

Delay to DTR in 10ms units

S26

Duration (10ms units) of delay between RTS and CTS, synchronous mode

S27

Bit-mapped register: 1

Enable V.21 modulation, 300 bps

2

Enable unencoded V.32 modulation

4

Disable V.32 modulation

8

Disable 2100 Hz answer tone

16

Disable M NP handshake

32

Disable V.42 Detect phase

64

Reserved

128

Unusual software incompatibility

S28

Duration (.1 sec units) of V.21/ V.23 handshake delay

S32

Voice/ Data switch options: 0

Disabled

1

Go off hook in originate mode

2

Go off hook in answer mode

3

Redial last-dialed number

4

Dial number stored at position 0

5

Auto answer toggle On/ Off

6

Reset modem

7

Initiate remote digital loopback

1

(continues)

1351

1352

Appendix D—Technical Reference

Table D.9

M odem AT Com m ands and S-Regist er Feat ures Cont inued

Com m and

M odem Funct ions and Opt ions

S34

Bit-mapped register:

S38

1

Disable V.32bis

2

Disable enhanced V.32 mode

4

Disable quick V.32 retrain

8

Enable V.23 modulation

16

Change M R LED to DSR

32

Enable M I/ M IC

64

Reserved

128

Reserved

Duration (sec) before disconnect when DTR drops during an ARQ call

ARQ = Autom atic repeat request ASCII = Am erican Standard Code for Inform ation Interchange BPS = Bits per second CCITT = Consultative Com m ittee for International Telephone and Telegraph CD = Carrier detect CRC = Cyclic redundancy check DCE = Data com m unications equipm ent DTE = Data term inal equipm ent EIA = Electronic Industries Association HDLC = High-level data link control HST = High-speed technology Hz = Hertz LAPM = Link access procedure for m odem s MI/MIC = Mode indicate/Mode indicate com m on MNP = Microcom networking protocol NV RAM = Non-volatile m em ory RAM = Random -access m em ory ROM = Read-only m em ory SDLC = Synchronous Data Link Control MR = Modem ready LED = Light-em itting diode DTR = Data term inal ready CTS = Clear to send RTS = Ready to send DSR = Data set ready

Hard Disk Drives Th is section h as a great d eal of in form ation con cern in g all asp ects of h ard d isk d rives, in clu d in g several tables th at list a large n u m ber of d ifferen t d rive p aram eters, organ ized by m an u factu rer. Th is section also sh ows BIOS h ard d rive p aram eter tables for a n u m ber of ROM BIOS version s, in clu d in g th ose from IBM, Com p aq , AMI, Award , an d Ph oen ix. Note th at th ese ROM BIOS p aram eter tables are rep resen tative of th e tables th at were u sed by th ese m an u factu rers before IDE d rives an d u ser-d efin able d rive typ es were com m on in all system s. Th erefore, th e ROM BIOS tables are m ostly u sefu l for su p p ortin g legacy h ard ware.

Hard Disk Drives

Hard Drive Param et ers Tables D.10–D.16 con tain th e sp ecification s for d rives from several of th e m ajor m an u factu rers*. Th e m an u factu rers rep resen ted are: Con n er—Table D.10 IBM—Table D.11 Maxtor—Table D.12 Qu an tu m —Table D.13 Seagate—Table D.14 Tosh iba—Table D.15 W estern Digital—Table D.16 Note th at Con n er is n ow p art of Seagate bu t Con n er m od el d rives are listed sep arately h ere for con ven ien ce. Th e followin g list d efin es th e abbreviation s u sed in th e table colu m n h ead in gs th at follow. ■ INT. In terface typ e. ■ CAP. Cap acity in m egabytes. ■ FF. Form Factor d en otes th e d iam eter of th e d rive p latter(s) in in ch es. ■ HGT. Th e d rive’s h eigh t. ■ CODE. En cod in g sch em e. ■ LZ. Lan d in g zon e (or p arkin g, sh ip p in g) cylin d er. Not u sed on m ost of th e n ewer d rives. ■ W P. W rite Precom p en sation cylin d er. Not u sed on m ost of th e n ewer d rives. ■ RW C. Red u ced W rite Cu rren t cylin d er. Not u sed on m ost of th e n ewer d rives. ■ MTBF. Mean Tim e Between Failu res, in th ou san d s of h ou rs. ■ PHDS. Nu m ber of physical d ata h ead s. Servo h ead s are n ot in clu d ed in th is figu re. ■ PCYL. Nu m ber of physical u ser-accessible cylin d ers. If the drive is an IDE drive and this num ber exceeds 1,024, a translation m ust be used. ■ PSPT. Nu m ber of physical sectors p er track. ■ LHDS. Nu m ber of logical d ata h ead s. Servo h ead s are n ot in clu d ed in th is figu re. ■ LCYL. Nu m ber of logical u ser-accessible cylin d ers. ■ LSPT. Nu m ber of logical sectors p er track. * Tables D.10–D.16 are reprinted from Th e Micro Hou se PC Hard ware Library, Copyright  Que Corporation and Micro House International, Inc. 1998.

1353

1354

Appendix D—Technical Reference

In ad d ition , th e followin g abbreviation s are u sed to save sp ace with in th e table rows: ■ INT. COMM=COMMODORE IDE-CPQ=IDE-COMPAQ U-SCSI=ULTRA-SCSI PCM=PCMCIA U=UNIDEN ■ FF. FH=Fu ll HH=Half 3H=1 in ch 4H=less th an 1 in ch ■ CODE. RLL 1=RLL 1,7 RLL 2=RLL 2,7 RLL 3=RLL 3,9 ■ PSPT. VAR=Variable sectors p er track For IDE d rives, LHDS, LCYL, an d LSPT are th e figu res you sh ou ld en ter in a u serd efin able BIOS Drive Typ e (u su ally Typ e 46 or Typ e 47). If th ese figu res aren ’t listed for an IDE d rive an d th e actu al p h ysical p aram eters can n ot be u sed , you can u se th e valu es from th e IDE Qu ick Referen ce Ch art (see Table D.17). Altern atively, you m ay n eed to u p grad e th e BIOS to a n ewer version th at su p p orts th e IDE Id en tify Drive com m an d if th e d rive su p p orts th at com m an d . Table D.11 sh ows th e IBM m oth erboard ROM BIOS h ard d isk p aram eters for AT or PS/ 2 system s u sin g ST-506/ 412 (stan d ard or IDE) con trollers. Table D.10

CONNER PERIPHERALS, INC.

M ODEL

INT

CAP

FF

HGT

CODE

LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT

LHDS

LCYL

LSPT

CFA-1080A

IDE(AT)

1000

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

0

0

0

16

2100

63

16

2479

63

16

332

63

CFA-1275A

IDE(AT)

1278

3.50

3H

U

2480

N/ A

N/ A

300

6

2479

0

CFA-1275S

SCSI-2

1278

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

6

0

0

CFA-170A

IDE(AT)

163.4

3.50

3H

RLL 1

AUTO

N/ A

N/ A

0

0

0

CFA-170S

SCSI

170.13

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1806

46

CFA-2161A

IDE(AT)

2147

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

8

4474

0

16

4095

63

CFA-270A

IDE(AT)

270.5

3.50

3H

RLL 1

AUTO

0

2

2805

0

16

524

63

CFA-270S

SCSI-2

270.5

3.50

3H

RLL 1

AUTO

0

2

2805

0

CFA-340A

IDE(AT)

343

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

4

2111

0

16

665

63

CFA-340S

SCSI-2

343

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

4

0

0

CFA-425A

IDE(AT)

426

3.50

3H

U

863

N/ A

N/ A

300

2

862

0

16

826

63

1355

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT

CODE

LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT

LHDS

LCYL

LSPT

CFA-540A

IDE(AT)

540.86

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

4

2111

0

16

1048

63

CFA-540S

SCSI-2

541

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

2805

0

CFA-810A

IDE(AT)

810

3.50

3H

RLL 1

1572

N/ A

N/ A

300

0

0

0

16

1572

63

16

1652

63

CFA-850A

IDE(AT)

850

3.50

3H

RLL 1

N/ A

N/ A

N/ A

250

4

3640

111

CFA-850S

SCSI-2

852

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

CFL-350A

IDE(AT)

350

2.50

FH

RLL 1

905

N/ A

N/ A

300

4

2225

0

12

905

63

CFL-420A

IDE(AT)

422

2.50

5H

RLL 1

818

N/ A

N/ A

300

4

2393

0

16

818

63

CFN-170A

IDE(AT)

168.2

2.50

4H

RLL 1

AUTO

N/ A

N/ A

250

4

1339

0

16

326

63

CFN-170S

SCSI-2

168.2

2.50

4H

RLL 1

AUTO

N/ A

N/ A

250

4

1339

0

CFN-250A

IDE(AT)

252.7

2.50

4H

RLL 1

AUTO

0

6

1339

0

16

489

63

CFN-250S

SCSI-2

252.7

2.50

4H

RLL 1

AUTO

CFN-340A

IDE(AT)

344.5

2.50

4H

RLL 1

AUTO

N/ A

N/ A

16

667

63

AUTO

N/ A

N/ A

16

2097

63

0

6

1339

0

250

6

1598

0

CFN-340S

SCSI-2

344.5

2.50

4H

RLL 1

250

6

1598

0

CFP-1060B

SCSI-2 D

1062.44

3.50

3H

RLL 1

500

8

2757

0

CFP-1060E

SCSI

1062.44

3.50

3H

RLL 1

500

8

2757

0

CFP-1060S

SCSI-2

1062.44

3.50

3H

RLL 1

500

8

2757

0

CFP-1060W

SCSI-2 W

1062.44

3.50

3H

RLL 1

500

8

2757

0

CFP-1080S

SCSI-2 F

1080

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

6

0

0

CFP-2105S

SCSI-2 W

2147

3.50

3H

U

AUTO

N/ A

N/ A

999

10

3892

0

CFP-2105W

SCSI-2

2147

3.50

3H

U

AUTO

N/ A

N/ A

999

10

3892

0

CFP-2107E

SCSI-2 FW

2110

3.50

3H

RLL 1

AUTO

N/ A

N/ A

999

10

3924

91

CFP-2107S

SCSI-2 F

2110

3.50

3H

RLL 1

AUTO

N/ A

N/ A

999

10

3924

91

CFP-2107W

SCSI-2 FW

2110

3.50

3H

RLL 1

AUTO

N/ A

N/ A

999

10

3924

91

CFP-4207E

SCSI-2 FW

4295

3.50

3H

RLL 1

AUTO

N/ A

N/ A

999

20

3924

96

CFP-4207S

SCSI-2 W

4295

3.50

3H

RLL 1

AUTO

CFP-4207W

SCSI-2 FW

4295

3.50

3H

RLL 1

CFS-1081A

IDE(AT)

1080

3.50

3H

U

2097

N/ A

N/ A

999

20

3924

96

N/ A

N/ A

999

20

3924

96

N/ A

N/ A

300

4

3924

0

CFS-1275A

IDE(AT)

1278

3.50

HH

RLL 1

2479

0

250

0

0

0

16

2479

63

CFS-1275A (REV. A)

IDE(AT)

1275

3.50

HH

RLL 1

AUTO

N/ A

N/ A

250

6

3640

0

16

2477

63

CFS-1621A

IDE(AT)

1620

3.50

3H

U

3146

N/ A

N/ A

300

6

3924

0

16

3146

63

CFS-210A

IDE(AT)

213.23

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

0

0

0

16

685

38

CFS-270A

IDE(AT)

270.9

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

2

0

0

16

525

63

CFS-420A

IDE(AT)

426.8

3.50

3H

RLL 1

AUTO

250

4

2388

0

16

826

63

CFS-425A

IDE(AT)

425

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

2

0

0

16

826

63

CFS-540A

IDE(AT)

540

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

4

0

0

16

1050

63

CFS-541A

IDE(AT)

540

3.50

3H

RLL 1

1048

N/ A

N/ A

300

2

3924

0

16

1048

63

CFS-635A

IDE(AT)

635

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

3

3640

0

16

1238

63

CFS-850A

IDE(AT)

850

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

3640

0

16

1651

63

(continues)

1356

Appendix D—Technical Reference

Table D.10

CONNER PERIPHERALS, INC. Cont inued

M ODEL

INT

CAP

FF

HGT

CODE

LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT

LHDS

LCYL

LSPT

CP-2020 KATO

SCSI

21.39

2.50

4H

RLL 2

AUTO

N/ A

N/ A

150

2

653

32

CP-2022

IDE(AT)

21.39

2.50

4H

RLL 2

AUTO

N/ A

N/ A

0

2

653

32

2

653

32

CP-2024

IDE(XT/ AT)

21.39

2.50

4H

RLL 2

AUTO

N/ A

N/ A

150

2

653

32

2

653

32

CP-2034

IDE(AT)

32.02

2.50

4H

RLL 2

AUTO

N/ A

N/ A

150

2

823

38

2

823

38

CP-2044

IDE(44PIN)

42.6

2.50

4H

RLL 2

980

N/ A

N/ A

150

4

548

38

5

980

17

CP-2044PK

IDE(44PIN)

42.6

2.50

4H

RLL 2

980

N/ A

N/ A

150

4

548

38

5

980

17

CP-2064

IDE(AT)

64.04

2.50

4H

RLL 2

AUTO

N/ A

N/ A

150

4

823

38

4

823

38

CP-2084

IDE(AT)

85.37

2.50

4H

RLL 1

AUTO

N/ A

N/ A

150

4

1097

38

8

548

38

CP-2124

IDE(AT)

121.6

2.50

4H

RLL 1

762

0

150

4

0

53

8

762

39

CP-2304

IDE(AT)

215.33

3.50

4H

RLL

AUTO

N/ A

N/ A

0

8

1348

39

CP-3000

IDE(AT)

42.8

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

2

1045

40

5

980

17

CP-30060

SCSI

60.86

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

2

1524

39

CP-30064

IDE(AT)

60.86

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

2

1524

39

4

762

39

CP-30064H

IDE(AT)

60.86

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

2

1524

39

4

762

39

CP-30069

M CA

60.86

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

2

1524

39

CP-30080

SCSI

84.5

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

4

1058

39

CP-30080E

SCSI

85.06

3.50

4H

RLL 1

AUTO

N/ A

N/ A

150

2

1806

46

CP-30084

IDE(AT)

84.5

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

4

1058

39

8

526

39

4

903

46

CP-30084E

IDE(AT)

85.06

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

2

1806

46

CP-30100

SCSI

121.72

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1524

39

CP-30104

IDE(AT)

121.56

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1522

39

8

762

39

8

762

39

5

895

55

CP-30104H

IDE(AT)

121.56

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1522

39

CP-30109

M CA

121.56

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1522

39

CP-30124

IDE(AT)

125.02

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

2

1985

62

CP-30170

SCSI

170.13

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1806

46

CP-30170E

SCSI

170

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1806

46

CP-30174

IDE(AT)

171.6

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

0

0

0

16

332

63

CP-30174E

IDE(AT)

170.13

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1806

46

8

903

46

CP-3020

SCSI

21.01

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

2

622

33

CP-30200

SCSI-2

212.64

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

4

2119

49

CP-30204

IDE(AT)

212.64

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

4

2119

49

16

683

38

CP-3022

IDE(AT)

21.49

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

2

636

33

2

636

33

CP-3024

IDE(AT)

21.49

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

2

636

33

2

636

33

CP-30254

IDE(AT)

251

3.50

3H

RLL 1

895

N/ A

N/ A

250

0

0

0

10

895

55

CP-30254H

IDE(AT)

251

3.50

3H

RLL 1

895

N/ A

N/ A

250

0

0

0

10

895

55

CP-30340

SCSI-2

343

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

4

0

0

CP-30344

IDE(AT)

343

3.50

3H

RLL 1

665

N/ A

N/ A

300

0

0

0

16

665

63

1357

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT

CODE

LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT

CP-3040

SCSI

42.02

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

2

1026

40

LHDS

LCYL

LSPT

CP-3044

IDE(AT)

42.88

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

2

1047

CP-3046F

IDE(AT)

42.8

3.50

3H

U

977

300

N/ A

100

2

1045

40

5

980

17

40

5

977

CP-30540

SCSI

0

3.50

3H

RLL 1

0

0

0

0

17

CP-30544

IDE(AT)

545.51

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

12

1806

49

CP-3100

SCSI

104.89

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

8

776

33

16

1057

63

CP-3102

IDE(AT)

104.89

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

8

776

33

8

776

33

CP-3104

IDE(AT)

104.89

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

8

776

33

8

776

33

CP-3114

IDE(AT)

112.45

3.50

HH

RLL

AUTO

N/ A

N/ A

0

8

832

33

8

832

33

CP-31370

SCSI-2

1300

3.50

3H

RLL

AUTO

N/ A

N/ A

0

14

2386

0

CP-3150

SCSI

52.44

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

4

776

33

CP-3180

SCSI

84.34

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

6

832

33

CP-3184

IDE(AT)

84.34

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

6

832

33

6

832

33

CP-3200

SCSI

212.61

3.50

HH

RLL

AUTO

N/ A

N/ A

150

8

1366

38

CP-3200F

SCSI

212.61

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

8

1366

38

CP-3204

IDE(AT)

215.33

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

8

1348

39

16

683

38

16

683

38

16

659

63

16

702

63

CP-3204F

IDE(AT)

212.61

3.50

HH

RLL 2

AUTO

N/ A

N/ A

50

8

1366

38

CP-3209F

M CA

212.61

3.50

HH

RLL 2

AUTO

N/ A

N/ A

50

8

1366

38

CP-3304

IDE(AT)

340.27

3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

8

1806

46

CP-3360

SCSI-2

362.47

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

8

1806

49

CP-3364

IDE(AT)

362.47

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

8

1806

49

CP-340

SCSI

41.95

3.50

HH

RLL 2

AUTO

N/ A

N/ A

20

4

788

26

CP-341

IDE(AT)

0

3.50

HH

U

AUTO

N/ A

N/ A

0

0

0

CP-341I

IDE(AT)

0

3.50

HH

U

AUTO

N/ A

N/ A

0

0

0

CP-342

IDE(AT)

42.86

3.50

HH

RLL 2

AUTO

N/ A

N/ A

0

4

805

26

4

805

26

CP-344

IDE(AT)

42.86

3.50

HH

RLL 2

AUTO

N/ A

N/ A

20

4

805

26

4

805

26

CP-346

IDE(AT)

42.86

3.50

HH

RLL 2

AUTO

N/ A

N/ A

20

4

805

26

4

805

26

CP-3500

SCSI-2

510.41

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

12

1806

46 16

987

63

CP-3504

IDE(AT)

509.38

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

12

1806

46

CP-3540

SCSI-2

543.7

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

12

1806

49

CP-3544 SUM M ITIDE(AT)

544.3

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

12

1808

49

16

1023

63

CP-4024

IDE (XT/ AT)

21.58

3.50

4H

RLL 2

AUTO

N/ A

N/ A

150

2

620

34

2

620

34

CP-4044

IDE (XT/ AT)

42.64

3.50

4H

RLL 2

AUTO

N/ A

N/ A

150

2

1096

38

5

980

17

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

Table D.11

IBM CORPORATION

M ODEL

INT

CAP

FF

HGT

0664-CSH

SCSI-2

4000

5.25

0664-ESH

SCSI-2 W

4000

5.25

CODE

LZ

WP

RW C

FH

AUTO

N/ A

N/ A

0

0

0

FH

AUTO

N/ A

N/ A

0

0

0

(continues)

1358

Appendix D—Technical Reference

Table D.11

IBM CORPORATION Cont inued

M ODEL

INT

115M B

ESDI-10M HZ

118.05

120M B

ST-506/ 412

120.58

20M B

ST-506/ 412

21.3

5.25

20M B PS/ 2

ST-506/ 412

21.3

30M B

ST-506/ 412

31.48

314M B

ESDI-10M HZ

319.87

44M B

ST-506/ 412

60M B

ST-506/ 412

70M B

ESDI-10M HZ

DALA-3540

IDE(AT)

DALS-3540 DAQA-32160

CAP

FF

HGT

CODE

LZ

5.25

—

RLL

AUTO

5.25

FH

M FM

FH

M FM

3.50

HH

M FM

5.25

FH

5.25

44.66 60.86

WP

RW C

M TBF

PCYL

PSPT LHDS LCYL LSPT

0

7

915

36

0

8

920

32

0

4

612

17

663

306 128

0

4

612

17

M FM

663

300

0

4

615

25

FH

RLL

AUTO

N/ A

0

15

1225

34

5.25

FH

M FM

733

300

0

7

733

17

5.25

FH

M FM

0

6

762

26

75.22

5.25

FH

RLL

540

3.50

N/ A

AUTO

N/ A

N/ A

0

7

583

36

AUTO

N/ A

N/ A

300

0

0

0

0

0

0

4

0

0

16

4200

63

16

6296

63

0 IDE(AT)

PHDS

2160

3.50

3H

AUTO

N/ A

N/ A

DAQA-33240

IDE(AT)

2160

3.50

3H

AUTO

N/ A

N/ A

6

0

0

DBOA-2360

IDE(AT)

360

2.50

4H

AUTO

N/ A

N/ A

300

0

0

0

DBOA-2528

IDE(AT)

528

2.50

4H

AUTO

N/ A

N/ A

300

0

0

0

DBOA-2540

IDE(AT)

540

2.50

4H

AUTO

N/ A

N/ A

300

0

0

0

DBOA-2720

IDE(AT)

720

2.50

4H

AUTO

N/ A

N/ A

300

0

0

0

DCAA-33610

IDE(AT)

3610

3.50

3H

PRM L

AUTO

N/ A

N/ A

5

0

0

16

7000

63

DCAA-34330

IDE(AT)

4330

3.50

3H

PRM L

AUTO

N/ A

N/ A

6

0

0

16

8400

63

DCAS-32160 (50-PIN)

U-SCSI

2160

3.50

3H

AUTO

N/ A

N/ A

0

0

0

DCAS-32160 (68-PIN)

U-SCSI W

2160

3.50

3H

AUTO

N/ A

N/ A

0

0

0

DCAS-32160 (80-PIN)

U-SCSI W

2160

3.50

3H

AUTO

N/ A

N/ A

0

0

0

DCAS-34330 (50-PIN)

U-SCSI

4330

3.50

3H

AUTO

N/ A

N/ A

0

0

0

DCAS-34330 (68-PIN)

U-SCSI W

4330

3.50

3H

AUTO

N/ A

N/ A

0

0

0

DCAS-34330 (80-PIN)

U-SCSI W

4330

3.50

3H

AUTO

N/ A

N/ A

0

0

0

DCHS-34550 (50-PIN)

SCSI-2 F

4550

3.50

3H

PRM L

AUTO

N/ A

N/ A

0

0

0

DCHS-34550 (68-PIN)

SCSI-2 FW

4550

3.50

3H

PRM L

AUTO

N/ A

N/ A

0

0

0

DCHS-34550 (80-PIN)

U-SCSI

4550

3.50

3H

PRM L

AUTO

N/ A

N/ A

0

0

0

DCHS-39100 (50-PIN)

SCSI-2 F

9111

3.50

3H

PRM L

AUTO

N/ A

N/ A

0

0

0

DCHS-39100 (68-PIN)

SCSI-2 FW

9111

3.50

3H

PRM L

AUTO

N/ A

N/ A

0

0

0

DCHS-39100 (80-PIN)

U-SCSI

9111

3.50

3H

PRM L

AUTO

N/ A

N/ A

0

0

0

1359

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT

CODE

LZ

WP

RW C

DCRA-22160

IDE(AT)

2160

2.50

5H

U

AUTO

N/ A

N/ A

DDLA-21215

IDE(AT)

1215

2.50

DDLA-21620

IDE(AT)

1620

2.50

DESKSTAR (VER. 2)

IDE(AT)

0

3.50

3H

DESKSTAR (VER. 3)

IDE(AT)

540

3.50

DESKSTAR (VER. 4)

IDE(AT)

0

3.50

3H

DESKSTAR (VER. 1)

SCSI-2 F

281

3.50

3H

DESKSTAR (VER. 2)

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

0

0

0

5H

0

0

0

5H

0

0

0

AUTO

N/ A

N/ A

300

0

0

0

AUTO

N/ A

N/ A

300

0

0

0

AUTO

N/ A

N/ A

3

0

0

2

0

0

0

0

0

2

4899

0

300

0

DESKSTAR 540M B (06H8558,9)

SCSI-2 F

540

3.50

3H

DESKSTAR-3

IDE(AT)

0

3.50

3H

DESKSTAR-4

IDE(AT)

0

3.50

3H

DESKSTAR-5

IDE(AT)

6480

3.50

DESKSTAR-5

IDE(AT)

6480

DESKSTAR-8

IDE(AT)

8041

DESKSTAR-XP

IDE(AT)

0

3.50

PRM L

4200

63

16

954

36

16

2480

63

AUTO

N/ A

N/ A

AUTO

N/ A

N/ A

4

0

0

16

4200

63

AUTO

N/ A

N/ A

5

0

0

16

7000

63

FH

8

0

0

3.50

FH

8

0

0

3.50

FH

16

16351 63

0

0

PRM L

AUTO U

N/ A

350

16

N/ A

300 0

AUTO

N/ A

N/ A

AUTO

N/ A

N/ A

PRM L

AUTO

N/ A

N/ A

3H

PRM L

AUTO

N/ A

3.50

3H

PRM L

3.50

3H

AUTO

N/ A

0

DESKSTAR-XP

SCSI-2 F

0

3.50

3H

DFHS-31080

SCSI-2 F

1120

3.50

3H

2

0

0

0

0

0

DFHS-31080

U-SCSI FW

1120

3.50

3H

100

0

0

0

DFHS-31080

U-SCSI FWD

1120

3.50

DFHS-31080 (80-PIN)

N/ A

100

0

0

0

SCSI SCA

1120

DFHS-32160

SCSI-2 F

2250

100

0

0

0

N/ A

1000

0

0

0

DFHS-32160

U-SCSI FW

2250

3.50

3H

PRM L

AUTO

N/ A

N/ A

100

0

0

0

DFHS-32160

U-SCSI FWD

2250

3.50

3H

PRM L

AUTO

N/ A

N/ A

100

0

0

0

DFHS-32160 (80-PIN)

SCSI SCA

2250

3.50

3H

PRM L

100

0

0

0

DFHS-34320

SCSI-2 F

4510

3.50

3H

AUTO

N/ A

N/ A

0

0

0

DFHS-34320

U-SCSI FW

4510

3.50

3H

AUTO

N/ A

N/ A

0

0

0

DFHS-34320

U-SCSI FWD

4510

3.50

3H

AUTO

N/ A

N/ A

0

0

0

DFHS-34320 (80-PIN)

SCSI SCA

4510

3.50

3H

0

0

0

DFM S-31080

SCSI-2 F

1320

3.50

3H

AUTO

N/ A

N/ A

0

0

0

DFM S-31080

U-SCSI FW

1320

3.50

3H

PRM L

AUTO

N/ A

N/ A

100

0

0

0

DFM S-31080

U-SCSI FWD

1320

3.50

3H

PRM L

AUTO

N/ A

N/ A

100

0

0

0

DFM S-31080 (80-PIN)

SCSI SCA

1120

3.50

3H

PRM L

100

0

0

0

PRM L

100

(continues)

1360

Appendix D—Technical Reference

Table D.11

IBM CORPORATION Cont inued

M ODEL

INT

DFM S-32160

SCSI-2 F

2320

3.50

3H

DFM S-32160

U-SCSI FW

2320

3.50

3H

PRM L

DFM S-32160

U-SCSI FWD

2320

3.50

3H

DFM S-32160 (80-PIN)

SCSI SCA

2320

3.50

3H

DFM S-32600

SCSI-2 F

2650

3.50

3H

DFM S-32600

U-SCSI FW

2650

3.50

3H

DFM S-32600 (80-PIN)

SCSI SCA

2650

3.50

3H

PRM L

100

0

0

0

DFM S-32600

U-SCSI FWD

2650

3.50

3H

PRM L

100

0

0

0

DFM S-34320

SCSI-2 F

4320

3.50

3H

0

0

0

DFM S-34320

U-SCSI FW

4320

3.50

3H

PRM L

AUTO

N/ A

N/ A

100

0

0

0

DFM S-34320

U-SCSI FWD

4320

3.50

3H

PRM L

AUTO

N/ A

N/ A

100

0

0

0

DFM S-34320 (80-PIN)

SCSI SCA

4510

3.50

3H

PRM L

100

0

0

0

DFM S-35250

SCSI-2 F

5310

3.50

3H

AUTO

N/ A

N/ A

0

0

0

DFM S-35250

U-SCSI FW

5310

3.50

3H

PRM L

AUTO

N/ A

N/ A

100

0

0

0

DFM S-35250

U-SCSI FWD

5310

3.50

3H

PRM L

AUTO

N/ A

N/ A

0

0

0

DFM S-35250 (80-PIN)

SCSI SCA

5310

3.50

3H

PRM L

0

0

0

0

0

0

DHAA-2270

CAP

FF

HGT

CODE

LZ

WP

RW C

M TBF

PHDS

AUTO

N/ A

N/ A

AUTO

N/ A

PRM L

AUTO

PRM L

AUTO

0

0

0

N/ A

100

0

0

0

N/ A

N/ A

100

0

0

0

N/ A

N/ A

100

0

0

0

0

0

0

0

0

0

PRM L

100

AUTO

N/ A

N/ A

100

0

PCYL

PSPT LHDS LCYL LSPT

DHAA-2405

IDE(44PIN)

405.13

2.50

4H

AUTO

N/ A

N/ A

300

0

0

0

16

785

63

DHAA-2540

IDE(44PIN)

540.35

2.50

4H

AUTO

N/ A

N/ A

300

0

0

0

16

1047

63

DHAA-2810

IDE(AT)

810

2.50

4H

AUTO

N/ A

N/ A

300

0

0

0

DHAS-2270

SCSI-2

270

2.50

5H

0

0

0

DHAS-2405

SCSI-2

405

2.50

5H

0

0

0

DHAS-2540

SCSI-2

540

2.50

5H

0

0

0

DHEA-34330 (VER. 1.7)

IDE(AT)

4033

2.50

DHEA-34331

IDE(AT)

4026

3.50

DHEA-34860 (VER. 1.7)

IDE(AT)

4086

2.50

DHEA-36480

IDE(AT)

6480

3.50

DHEA-36480 (VER. 1.7)

IDE(AT)

6480

DHEA-36481

IDE(AT)

6041

U

AUTO

N/ A

N/ A

250

16

8400

63

16

8184

63

16

8400

63

FH

8

0

0

3.50

FH

8

0

0

3.50

FH

16

12592 63

FH

U

AUTO

N/ A

N/ A

250

DHEA-38451

IDE(AT)

8041

3.50

FH

16

16351 63

DJAA-31270

IDE(AT)

1270

3.50

3H

AUTO

N/ A

N/ A

3

0

0

16

2480

63

DJAA-31700

IDE(AT)

1700

3.50

3H

AUTO

N/ A

N/ A

4

0

0

16

3308

63

DLGA-22690

IDE(AT)

2690

2.50

5H

AUTO

N/ A

N/ A

0

0

0

16

5216

63

1361

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT

DLGA-23080

IDE(AT)

3080

2.50

5H

CODE

PHDS

PCYL

PSPT LHDS LCYL LSPT

0

0

0

16

5968

63

DM CA-21080

IDE(AT)

1080

2.50

DM CA-21440

IDE(AT)

1440

2.50

5H

0

0

0

16

2100

63

5H

0

0

0

16

2800

63

DM CA-22160

IDE(AT)

2160

2.50

5H

DORS-32160 (50-PIN)

300

6

4928

0

16

4200

U-SCSI

2160

3.50

3H

AUTO

N/ A

DORS-32160 (68-PIN)

N/ A

800

0

0

0

5

U-SCSI W

2160

3.50

3H

AUTO

DORS-32160 (80-PIN)

N/ A

N/ A

800

0

0

0

5

U-SCSI W

2160

3.50

3H

AUTO

N/ A

N/ A

800

0

0

0

5

DPEA-30540

IDE(AT)

540

3.50

DPEA-30810

IDE(AT)

810

3.50

AUTO

N/ A

N/ A

300

0

0

0

AUTO

N/ A

N/ A

300

0

0

DPEA-31080

IDE(AT)

1080

3.50

0

AUTO

N/ A

N/ A

300

0

0

0

DPES-30540

SCSI-2 F

540

3.50

3H

DPES-30810

SCSI-2 F

810

3.50

3H

U

AUTO

N/ A

N/ A

0

2

0

0

U

AUTO

N/ A

N/ A

0

3

0

0

DPES-31080

SCSI-2 F

1080

3.50

3H

DPLA-24480

IDE(AT)

4480

2.50

FH

U

AUTO

N/ A

N/ A

0

4

0

0

15

9264

63

DPLA-25120

IDE(AT)

4480

2.50

FH

15

10592 63

DPRA-20810

IDE(AT)

810

2.50

4H

AUTO

N/ A

N/ A

300

0

0

0

DPRA-21215

IDE(AT)

1215

2.50

4H

AUTO

N/ A

N/ A

300

0

0

0

DPRS-20810

SCSI-2

810

2.50

5H

AUTO

N/ A

N/ A

6

3481

0

0

3H

LZ

WP

RW C

AUTO

N/ A

N/ A

M TBF

0

DPRS-21215

SCSI-2

1215

2.50

5H

AUTO

N/ A

N/ A

6

3481

0

0

DSAA-3270

IDE(AT)

281.34

3.50

3H

AUTO

N/ A

N/ A

300

0

0

0

16

954

36

0

DSAA-3360

IDE(AT)

365.29

3.50

3H

AUTO

N/ A

N/ A

300

0

0

0

16

929

48

DSAA-3540 VER. 1

IDE(AT)

548.09

3.50

3H

AUTO

N/ A

N/ A

300

0

0

0

16

1062

63

DSAA-3540 VER. 2

IDE(AT)

528.48

3.50

3H

AUTO

N/ A

N/ A

300

0

0

0

16

1024

63

DSAA-3720

IDE(AT)

730.79

3.50

3H

AUTO

N/ A

N/ A

300

0

0

0

16

1416

63

DSAS-3270

SCSI-2 F

281

3.50

3H

300

2

0

0

DSAS-3360

SCSI-2 F

365

3.50

3H

300

2

0

0

DSAS-3540

SCSI-2 F

548

3.50

3H

300

3

0

0

DSAS-3720

SCSI-2 F

730

3.50

3H

4

0

0

DSOA-20540

IDE(44PIN)

540

2.50

5H

AUTO

N/ A

N/ A

0

0

0

16

1050

63

DSOA-20810

IDE(44PIN)

810

2.50

5H

AUTO

N/ A

N/ A

0

0

0

16

1575

63

DSOA-21080

IDE(44PIN)

1080

2.50

5H

AUTO

N/ A

N/ A

0

0

0

16

2100

63

DTCA-23240

IDE(AT)

3240

2.50

FH

16

6304

63

DTCA-24090

IDE(AT)

4090

2.50

FH

16

7944

63

DTNA-21800

IDE(AT)

1800

2.50

5H

PRM L

AUTO

N/ A

N/ A

0

0

0

16

3500

63

DTNA-22160

IDE(AT)

2160

2.50

5H

PRM L

AUTO

N/ A

N/ A

0

0

0

16

4200

63

300

(continues)

1362

Appendix D—Technical Reference

Table D.11

IBM CORPORATION Cont inued

M ODEL

INT

CAP

FF

HGT

CODE

LZ

WP

RW C

M TBF

PHDS

PCYL PSPT

DVAA-2810

IDE(AT)

810

2.50

5H

U

AUTO

N/ A

N/ A

300

16

1571

DVAS-2810

SCSI-2

810

2.50

5H

AUTO

N/ A

N/ A

6

2788

0

DYKA-22160

IDE(AT)

2130

2.50

FH

16

4200

63

DYKA-23240

IDE(AT)

3240

2.50

FH

16

6304

63

DYLA-26480

IDE(AT)

6480

2.50

FH

15

16944 63

DYLA-28100

IDE(AT)

8100

2.50

FH

15

16944 63

H2172-A2

IDE(44PIN)

172.16

2.50

4H

AUTO

N/ A

N/ A

0

0

0

0

H2172-S2

SCSI-2

172

2.50

3H

AUTO

N/ A

N/ A

300

0

0

0

H2258-A3

IDE(44PIN)

258.24

2.50

4H

AUTO

N/ A

N/ A

0

0

0

0

H2258-S3

SCSI-2

258

2.50

3H

AUTO

N/ A

N/ A

300

0

0

0

H2344-A4

IDE(44PIN)

344.33

2.50

4H

AUTO

N/ A

N/ A

0

0

0

0

H2344-S4

SCSI-2

344

2.50

3H

AUTO

N/ A

N/ A

300

0

0

0

H3133-A2

IDE(AT)

133.56

3.50

3H

AUTO

N/ A

N/ A

250

0

0

H3171-A2

IDE(AT)

171.29

3.50

3H

AUTO

N/ A

N/ A

250

0

0

H3256-A3

IDE(AT)

257.16

3.50

3H

AUTO

N/ A

N/ A

250

0

H3342-A4

IDE(AT)

342.88

3.50

3H

AUTO

N/ A

N/ A

250

PS/ 2 M ODEL 25 20M B

ST-506/ 412

20

5.25

—

TRAVELSTAR (VER. 2)

IDE(AT)

810

2.50

5H

TRAVELSTAR

U

AUTO

N/ A

N/ A

SCSI-2

810

2.50

5H

TRAVELSTAR

SCSI-2

0

2.50

5H

TRAVELSTAR-2LP IDE(44PIN)

0

2.50

5H

TRAVELSTAR-2XP IDE(AT)

0

2.50

5H

TRAVELSTAR-3GN IDE(AT)

8100

2.50

FH

TRAVELSTAR-3LP IDE(AT)

0

2.50

5H

TRAVELSTAR-3XP IDE(AT)

0

2.50

5H

TRAVELSTAR-4GT IDE(AT)

4480

2.50

FH

AUTO

U

0

989

34

15

989

34

15

915

49

0

15

1023

17

0

10

984

34

0

0

16

872

36

0

0

0

16

872

48

0

0

0

0

300

16

1571

63

0

0

0

N/ A

6

2788

0

0

0

0

0

0

N/ A

N/ A

0

0

0

16

1575

63

AUTO

N/ A

N/ A

0

0

0

16

4200

63

15

16944 63

AUTO

N/ A

0

0

16

2100

63

0

0

16

5216

63

15

10592 63 16

3500

63

0

2.50

5H

0

0

4480

2.50

FH

15

10592 63

TRAVELSTAR-8GS IDE(AT)

8100

2.50

FH

15

16944 63

TRAVELSTAR-LP

IDE(AT)

0

2.50

4H

0

0

TRAVELSTAR-VP

IDE(AT)

0

2.50

5H

0

0

0

TRAVELSTAR-XP

IDE(AT)

0

2.50

4H

AUTO

N/ A

N/ A

0

0

0

TRAVELSTAR-XP

SCSI-2

0

2.50

5H

AUTO

N/ A

N/ A

6

3481

0

TYPE 0661 M ODEL 371

SCSI-2

326.51

3.50

HH

AUTO

N/ A

N/ A

14

949

48

N/ A

N/ A

0 0

TRAVELSTAR-5GS IDE(AT)

AUTO

N/ A

N/ A

TRAVELSTAR-4LP IDE(AT)

RLL

0

63

AUTO

AUTO

PRM L

N/ A

LSPT

10

0

TRAVELSTAR (VER. 2)

LHDS LCYL

N/ A

300

300

300

0

0

0

0

1363

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT

CODE

LZ

WP

RW C

M TBF

PHDS

PCYL PSPT

TYPE 0661 M ODEL 467

SCSI-2

412.53

3.50

HH

RLL

AUTO

N/ A

N/ A

300

14

1199

48

TYPE 0662 (SPITFIRE) M ODEL A10

IDE(AT)

1051.8

3.50

3H

AUTO

N/ A

N/ A

500

0

0

0

TYPE 0662 (SPITFIRE) M ODEL S12

SCSI-2 F

1050

3.50

FH

U

AUTO

N/ A

N/ A

800

16

2038

63

TYPE 0662 (SPITFIRE) M ODEL S1D

SCSI-2 F

1050

3.50

FH

U

AUTO

N/ A

N/ A

800

16

2038

63

TYPE 0662 (SPITFIRE) M ODEL SW1

SCSI-2 W

1050

3.50

FH

U

AUTO

N/ A

N/ A

800

16

2038

63

TYPE 0662 (SPITFIRE) M ODEL SWD

SCSI-2 W

1050

3.50

FH

U

AUTO

N/ A

N/ A

800

16

2038

63

TYPE 0663 M ODEL E12

SCSI

1044

3.50

HH

RLL

AUTO

N/ A

N/ A

500

13

2469

0

TYPE 0663 M ODEL E15

SCSI

1206

3.50

HH

RLL

AUTO

N/ A

N/ A

500

15

2469

0

TYPE 0663 M ODEL H11

SCSI

0

3.50

HH

RLL

400

0

0

0

TYPE 0663 M ODEL H12

SCSI

1039.61

3.50

HH

RLL

AUTO

N/ A

N/ A

400

15

2051

66

TYPE 0663 M ODEL L08

SCSI

623.76

3.50

HH

RLL

AUTO

N/ A

N/ A

400

9

2051

66

TYPE 0663 M ODEL L11

SCSI

900.99

3.50

HH

RLL

AUTO

N/ A

N/ A

400

13

2051

66

TYPE 0663 M ODEL L12

SCSI

1039.61

3.50

HH

RLL

AUTO

N/ A

N/ A

880

15

2051

66

TYPE 0664 CSH/ ESH

SCSI

4000

5.25

FH

RLL

AUTO

N/ A

N/ A

375

2

2857

0

TYPE 0664 M ODEL M 1H (50-PIN)

SCSI-2 F

2000

3.50

HH

AUTO

N/ A

N/ A

6

2857

0

TYPE 0664 M ODEL M 1H (68-PIN)

SCSI-2 FW

2000

3.50

HH

AUTO

N/ A

N/ A

6

2857

0

TYPE 0664 M ODEL N1H (50-PIN)

SCSI-2 F

2000

3.50

HH

AUTO

N/ A

N/ A

6

2857

0

TYPE 0664 M ODEL N1H (68-PIN)

SCSI-2 FW

2000

3.50

HH

AUTO

N/ A

N/ A

6

2857

0

TYPE 0665 M ODEL 38

ST-506/ 412

31.9

5.25

FH

M FM

AUTO

N/ A

N/ A

0

5

733

17

TYPE 0665 M ODEL 53

ST-506/ 412

44.66

5.25

FH

M FM

AUTO

N/ A

N/ A

0

7

733

17

LHDS LCYL

LSPT

16

63

2038

(continues)

1364

Appendix D—Technical Reference

Table D.11

IBM CORPORATION Cont inued

M ODEL

INT

TYPE 0667 M ODEL 61 TYPE 0667 M ODEL 85 TYPE 0669 M ODEL 61

CAP

FF

HGT

CODE

LZ

WP

RW C

M TBF

PHDS

PCYL PSPT

ESDI-10M HZ 52.14

5.25

FH

RLL

AUTO

N/ A

N/ A

0

5

582

35

ESDI-10M HZ 73

5.25

FH

RLL

AUTO

N/ A

N/ A

0

7

582

64

ESDI-10M HZ 48.42

5.25

FH

RLL

AUTO

N/ A

N/ A

0

5

582

35

TYPE 0669 M ODEL 85

ESDI-10M HZ 67.79

5.25

FH

RLL

AUTO

N/ A

N/ A

0

7

582

64

TYPE 0671 M ODEL S11

SCSI

234.38

5.25

FH

RLL

AUTO

N/ A

N/ A

0

11

1224

34

TYPE 0671 M ODEL S15

SCSI

319.61

5.25

FH

RLL

AUTO

N/ A

N/ A

0

15

1224

34

TYPE 0681 M ODEL 500

SCSI

476.26

5.25

FH

RLL

AUTO

N/ A

N/ A

150

11

1458

58

TYPE 0681 M ODEL1000

SCSI

865.93

5.25

FH

RLL

AUTO

N/ A

N/ A

150

20

1458

58

ULTRASTAR 2ES (50-PIN)

U-SCSI

0

3.50

3H

AUTO

N/ A

N/ A

0

0

0

ULTRASTAR 2ES (68-PIN)

U-SCSI W

0

3.50

3H

AUTO

N/ A

N/ A

0

0

0

ULTRASTAR 2ES (80-PIN)

U-SCSI W

2160

3.50

3H

AUTO

N/ A

N/ A

0

0

0

ULTRASTAR 2XP (50 PIN)

SCSI-2 F

4550

3.50

3H

PRM L

AUTO

N/ A

N/ A

0

0

0

ULTRASTAR 2XP (68-PIN)

SCSI-2 FW

4550

3.50

3H

PRM L

AUTO

N/ A

N/ A

0

0

0

ULTRASTAR 2XP (80-PIN)

U-SCSI

4550

3.50

3H

PRM L

AUTO

N/ A

N/ A

0

0

0

ULTRASTAR ES (50-PIN)

U-SCSI

2160

3.50

3H

AUTO

N/ A

N/ A

800

0

0

0

5

ULTRASTAR ES (68-PIN)

U-SCSI W

2160

3.50

3H

AUTO

N/ A

N/ A

800

0

0

0

5

ULTRASTAR ES (80-PIN)

U-SCSI W

0

3.50

3H

AUTO

N/ A

N/ A

800

0

0

0

5

WD-12

ST-506/ 412

10

5.25

FH

M FM

296

296

0

4

306

17

WD-2120

M CA

127.28

3.50

3H

RLL

AUTO

N/ A

N/ A

150

4

1243

50

WD-240

M CA

43.65

2.50

4H

RLL

AUTO

N/ A

N/ A

150

2

1122

38

WD-25

ST-506/ 412

20

5.25

FH

M FM

296

296

0

0

0

17

WD-3158

M CA

120.58

3.50

FH

RLL

AUTO

N/ A

N/ A

45

8

920

32

WD-3160

M CA

163.09

3.50

HH

RLL

AUTO

N/ A

N/ A

110

8

1021

39

WD-380

M CA

81.54

3.50

HH

RLL

AUTO

N/ A

N/ A

110

4

1021

39

WD-387

M CA

60.81

3.50

HH

RLL

AUTO

N/ A

N/ A

45

4

928

32

WD-L40

M CA

41.45

3.50

HH

RLL

AUTO

N/ A

N/ A

90

2

1038

39

WD-L40S

M CA

41.45

3.50

HH

RLL

AUTO

N/ A

N/ A

90

2

1038

39

LHDS LCYL

LSPT

1365

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT

CODE

LZ

WP

RW C

M TBF

PHDS

PCYL PSPT

LHDS LCYL

LSPT

WDA-2120

IDE(AT)

126.51

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1243

50

15

969

17

WDA-240

IDE(AT)

43.1

2.50

4H

RLL 1

AUTO

N/ A

N/ A

150

2

1122

38

8

619

17

WDA-260

IDE(AT)

63.64

3.50

3H

RLL

AUTO

N/ A

N/ A

150

2

1243

50 10

989

17

10

984

34

WDA-280

IDE(AT)

86.08

2.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1122

38

WDA-3160

IDE(AT)

81.54

3.50

HH

RLL

AUTO

N/ A

N/ A

110

4

1021

39

WDA-380

IDE(AT)

81.54

3.50

HH

RLL

AUTO

N/ A

N/ A

110

4

1021

39

WDA-L160

IDE(AT)

171.29

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1923

44

WDA-L40

IDE(AT)

41.53

3.50

3H

RLL 2

AUTO

N/ A

N/ A

90

2

1040

39

WDA-L42

IDE(AT)

42.61

3.50

3H

RLL 2

AUTO

N/ A

N/ A

90

2

1067

39

WDA-L80

IDE(AT)

85.64

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

2

1923

44

10

984

17

WDA-S260

IDE(AT)

63.3

3.50

4H

RLL 1

AUTO

N/ A

N/ A

150

2

1243

50

8

909

17

WDS-240

SCSI-2

43.65

2.50

5H

RLL

AUTO

N/ A

N/ A

150

2

1122

38

WDS-280

SCSI-2

87

2.50

5H

AUTO

N/ A

N/ A

4

1122

38

WDS-3100

SCSI-2

108.27

3.50

4H

RLL

AUTO

N/ A

N/ A

150

2

2009

0

WDS-3160

SCSI-2

163.09

3.50

HH

RLL

AUTO

N/ A

N/ A

110

8

1021

39

WDS-3200

SCSI-2

216.53

3.50

4H

RLL

AUTO

N/ A

N/ A

150

4

2009

0

WDS-380

SCSI-2

81.54

3.50

HH

RLL

AUTO

N/ A

N/ A

110

4

1021

39

WDS-L160

SCSI

0

3.50

5H

AUTO

N/ A

N/ A

150

2

0

112

WDS-L40

SCSI-2

41.45

3.50

FH

RLL

AUTO

N/ A

N/ A

90

2

1038

39

WDS-L42

SCSI-2

42.57

3.50

3H

RLL 1

AUTO

N/ A

N/ A

80

2

1066

39

WDS-L80

SCSI

0

3.50

5H

AUTO

N/ A

N/ A

150

2

0

112

Table D.12

M AXTOR CORPORATION

M ODEL

INT

CAP

FF

HGT

CODE

LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT

LHDS LCYL LSPT

250837

IDE(44PIN)

837

2.50

5H

RLL 1

AUTO

N/ A

N/ A

300

5

3196

0

16

0

1621

63

250840

IDE(AT)

840

2.50

5H

RLL 1

AUTO

N/ A

N/ A

300

5

3232

25084A

IDE(AT)

84

2.50

3H

RLL

AUTO

N/ A

N/ A

150

0

0

0

16

569

18

251005

IDE(44PIN)

11005

2.50

5H

RLL 1

AUTO

N/ A

N/ A

300

6

3196

0

16

1945

63

251010

IDE(AT)

1010

2.50

5H

RLL 1

AUTO

N/ A

N/ A

300

6

3232

0

25125S

SCSI

128.2

2.50

4H

RLL 1

AUTO

N/ A

N/ A

150

4

1092

0

25128A

IDE(AT)

128.2

2.50

4H

RLL 1

AUTO

N/ A

N/ A

150

4

1092

0

14

1024

17

251340

IDE(44PIN)

1340

2.50

5H

RLL 1

AUTO

N/ A

N/ A

300

8

3196

0

16

2594

63

251350

IDE(AT)

1350

2.50

5H

RLL 1

AUTO

N/ A

N/ A

300

8

3232

0

25252A

IDE(AT)

252

2.50

3H

RLL

AUTO

N/ A

N/ A

150

0

0

0

16

569

54

25252S

SCSI

252

2.50

4H

U

AUTO

N/ A

N/ A

0

6

1418

0

2585A

IDE(AT)

85.41

2.50

4H

RLL 1

AUTO

N/ A

N/ A

150

4

1092

0

10

981

17

2585S

SCSI

85.41

2.50

4H

RLL 1

AUTO

N/ A

N/ A

150

4

1092

0

7040A

IDE(AT)

43.13

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

2

1170

36

5

981

17

(continues)

1366

Appendix D—Technical Reference

Table D.12

M AXTOR CORPORATION Cont inued

M ODEL

INT

CAP

FF

HGT

CODE

LZ

7040A (VER. 2)

IDE(AT)

41

3.50

FH

7040S

SCSI

42.57

3.50

7060A

IDE(AT)

65.2

7060S

SCSI

7080A

IDE(AT)

7080A (VER. 2)

WP

RW C

M TBF

PHDS

PCYL

PSPT

AUTO

N/ A

N/ A

150

4

1170

1

3H

RLL 1

AUTO

N/ A

N/ A

40

2

1155

36

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

2

1516

42

64.42

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

2

1498

42

85.15

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1155

36

IDE(AT)

82

3.50

FH

AUTO

N/ A

N/ A

150

4

1170

36

7080S

SCSI

85.15

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1155

36

71000A

IDE(AT)

1002

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

3

0

0

71050A

IDE(AT)

1050

3.50

3H

U

AUTO

N/ A

N/ A

0

0

0

71084A

IDE(AT)

1

3.50

4H

RLL 1

AUTO

N/ A

N/ A

300

4

71084AP

IDE(AT)

1

3.50

4H

RLL 1

AUTO

N/ A

N/ A

300

4

7120A

IDE(AT)

130.4

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

7120S

SCSI

128.85

3.50

3H

RLL 1

AUTO

N/ A

N/ A

71260A

IDE(AT)

1260

3.50

3H

U

AUTO

N/ A

N/ A

71260AP

IDE(AT)

1260

3.50

3H

U

AUTO

N/ A

N/ A

LHDS LCYL LSPT

7

1024

17

10

981

17

0

16

2045

63

3

0

16

2,105 63

3

0

16

2,105 63

4

1516

42

6

771

55

150

4

1498

42

0

0

0

0

16

2448

63

0

0

0

0

16

2448

63

7131A

IDE(AT)

130

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

0

0

0

8

1002

32

71336A

IDE(AT)

1336

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

4702

0

16

2595

63

71336AP

IDE(AT)

1336

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

4702

0

16

2595

63

71350A

IDE(AT)

1350

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

16

2624

63

71350AP

IDE(AT)

1350

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

16

2624

63

7135AV

IDE(AT)

135

3.50

HH

U

N/ A

N/ A

0

0

0

0

13

966

21

71626A

IDE(AT)

1626

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

6

3721

0

16

3158

63

71626AP

IDE(AT)

1

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

6

3

0

16

3158

63

71670A

IDE(AT)

1670

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

5

4702

0

16

3244

63

71670AP

IDE(AT)

1670

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

5

4702

0

16

3244

63

0

0

0

71687A

0

71687AP

0

0

0

7170A

IDE(AT)

170

0 3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

0

0

0

15

866

26

7171A

IDE(AT)

171

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

0

0

0

15

866

26

72004A

IDE(AT)

2004

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

6

4702

0

16

3893

63

72004AP

IDE(AT)

2004

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

6

4702

0

16

3893

63

72025AP

IDE(AT)

2025

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

16

3936

63

7213A

IDE(AT)

212.78

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1690

0

16

683

38

7213S

SCSI

212.78

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1690

0

7245A

IDE(AT)

245.57

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1944

0

16

967

31

7245S

SCSI

245

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1944

0

72577AP

IDE(AT)

2577

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

16

4996

63

72700AP

IDE(AT)

2700

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

16

5248

63

1367

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT

CODE

7270AV

IDE(AT)

270

3.50

HH

U

7270S

SCSI

270

3.50

3H

RLL 1

7273A

IDE(AT)

275.39

3.50

3H

RLL 1

7273A (NEWER VER)

IDE(AT)

273

3.50

3H

RLL 1

LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT

LHDS LCYL LSPT

N/ A

N/ A

0

0

0

0

11

959

50

AUTO

N/ A

N/ A

300

4

1629

0

AUTO

N/ A

N/ A

150

2

2771

0

16

967

31

AUTO

N/ A

N/ A

300

2

2793

0

16

1012

33

9

998

63

15

790

57

7290A

IDE(AT)

290

3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

0

0

0

7290S

SCSI

290

3.50

3H

RLL 1

AUTO

N/ A

N/ A

0

4

1765

0

7345A

IDE(AT)

345

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

0

0

7345S

SCSI

345

—

RLL 1

AUTO

N/ A

N/ A

0

4

2219

0

7405A

IDE(AT)

405

3.50

3H

U

AUTO

N/ A

N/ A

150

0

0

0

16

989

50

7405AV

IDE(AT)

405

3.50

HH

U

N/ A

N/ A

0

0

0

0

16

989

50

7420AV

IDE(AT)

420

3.50

HH

U

N/ A

N/ A

0

0

0

0

16

986

52

7425AV

IDE(AT)

425

3.50

3H

U

AUTO

N/ A

N/ A

0

0

0

0

16

1002

52

7540A

IDE(AT)

528.4

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

2771

0

16

1024

63

7540AV

IDE(AT)

540

3.50

HH

U

N/ A

N/ A

0

0

0

0

16

1046

63

7541A

IDE(AT)

541

3.50

4H

RLL 1

N/ A

N/ A

300

2

3

0

16

1,052 63

AUTO

7541AP

IDE(AT)

541

3.50

4H

RLL 1

AUTO

N/ A

N/ A

300

2

3

0

16

1,052 63

7546A

IDE(AT)

528.48

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

2771

0

16

1024

63

7546A (NEWER VER)

IDE(AT)

547

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

2793

0

16

1060

63

7668A

IDE(AT)

668

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

2

4702

0

16

1297

63

7668AP

IDE(AT)

668

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

2

4702

0

16

1297

63

7850AV

IDE(AT)

850

3.50

3H

U

AUTO

N/ A

N/ A

0

0

0

0

16

1648

63

8050S

SCSI

50

3.50

HH

RLL 2

AUTO

N/ A

N/ A

30

4

809

26

8051A

IDE(AT)

42.72

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

4

745

28

4

745

28

8051S

SCSI

44.9

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

4

783

0

3H

16

1700

63

16

2100

63

80875A

IDE(AT)

875

3.50

AUTO

N/ A

N/ A

0

0

0

80875A2

IDE(AT)

875

3.50

AUTO

N/ A

N/ A

0

0

0

0

81080A3

IDE(AT)

1080

3.50

AUTO

N/ A

N/ A

0

0

0

0

81081A2

IDE(AT)

1081

3.50

0

0

0

81275A3

IDE(AT)

1275

3.50

AUTO

N/ A

N/ A

0

0

0

0

81280A

IDE(AT)

213

2.50

0

0

0

16

684

38

81280A2

IDE(AT)

1280

3.50

3H

AUTO

N/ A

N/ A

0

0

0

16

2481

63

81312A

IDE(AT)

1312

3.50

3H

AUTO

N/ A

N/ A

0

0

0

16

2548

63

81312A3

IDE(AT)

1312

3.50

AUTO

N/ A

N/ A

0

0

0

0

81620A3

IDE(AT)

1620

3.50

0

0

0

16

3250

63

81630A4

IDE(AT)

1630

3.50

AUTO

N/ A

N/ A

150

0

0

0

81750A

IDE(AT)

1750

3.50

AUTO

N/ A

N/ A

0

0

0

16

3400

63

81750A2

IDE(AT)

1750

3.50

AUTO

N/ A

N/ A

0

0

0

3H

U

3H

3H

0

(continues)

1368

Appendix D—Technical Reference

Table D.12 M ODEL

M AXTOR CORPORATION Cont inued INT

CAP

FF

HGT

CODE

LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT

81750A4

IDE(AT)

1750

3.50

AUTO

N/ A

N/ A

0

0

0

0

81750D2

IDE(AT)

1750

3.50

AUTO

N/ A

N/ A

0

0

0

0

82100A4

IDE(AT)

2100

3.50

0

0

0

82160D2

IDE(AT)

2160

3.50

0

0

0

82187A

IDE(AT)

2187

3.50

0

0

0

82187A5

IDE(AT)

2187

3.50

82400A4

IDE(AT)

2400

3.50

82559A4

IDE(AT)

2559

3.50

82560A

IDE(AT)

2560

3.50

82560A3

IDE(AT)

2560

3.50

82560A4

IDE(AT)

2560

3.50

82560D3

IDE(AT)

3240

3.50

82577A6

IDE(AT)

2577

3.50

82580A5

IDE(AT)

2580

3.50

3H

82625A

IDE(AT)

2625

3.50

3H

82625A6

IDE(AT)

2625

3.50

83062A

IDE(AT)

3062

3.50

83062A7

IDE(AT)

3062

83200A5

IDE(AT)

83200A6

IDE(AT)

83200A8

3H AUTO

N/ A

N/ A

AUTO

N/ A

N/ A

AUTO

N/ A

N/ A

0

0

0

0

RLL 8

AUTO

N/ A

N/ A

0

0

0

0

RLL 8

AUTO

N/ A

N/ A

0

0

0

0

0

0

0

0

0

0

0

0

0

3H

3H

0

RLL AUTO

N/ A

N/ A

0

3H

0

0

0

0

0

16

5004

63

0

0

0

16

5100

63

0

0

0

0

0

0

16

5948

63

16

6218

63

16

6800

63

N/ A

0

0

0

0

3200

3.50

AUTO

N/ A

N/ A

0

0

0

0

3200

3.50

AUTO

N/ A

N/ A

0

0

0

0

IDE(AT)

3200

3.50

AUTO

N/ A

N/ A

0

0

0

0

83201A6

IDE(AT)

3201

3.50

0

0

0

83202A6

IDE(AT)

3202

3.50

AUTO

N/ A

N/ A

0

0

0

0

83209A5

IDE(AT)

3209

3.50

AUTO

N/ A

N/ A

0

0

0

0

IDE(AT)

3240

3.50

IDE(AT)

3500

3.50

83500A4

IDE(AT)

3500

3.50

0

3H

3H

63

0

N/ A

83500A

4962

0

AUTO

83240D4

16

N/ A

3.50

RLL 8

63

N/ A

N/ A

3.50

4962

AUTO

N/ A

3.50

16

0

N/ A

3240

63

0

N/ A

3240

4248

0

AUTO

IDE(AT)

16

0

AUTO

IDE(AT)

63

N/ A

N/ A

83240D3

4092

N/ A

N/ A

83240A4

16

AUTO

AUTO

3H

LHDS LCYL LSPT

AUTO

N/ A

N/ A

0

0

0

0

AUTO

N/ A

N/ A

0

0

0

0

AUTO

N/ A

N/ A

0

0

0

0

AUTO

N/ A

N/ A

0

0

0

AUTO

N/ A

N/ A

0

0

0

0

83500A8

IDE(AT)

3500

3.50

AUTO

N/ A

N/ A

0

0

0

0

83500D4

IDE(AT)

3500

3.50

AUTO

N/ A

N/ A

0

0

0

0

83840A

IDE(AT)

3840

3.50

3H

0

0

0

16

7441

63

83840A6

IDE(AT)

3840

3.50

3H

0

0

0

16

7443

63

84000A6

IDE(AT)

4000

3.50

3H

0

0

0

16

7763

63

84004A8

IDE(AT)

4004

3.50

AUTO

N/ A

N/ A

0

0

0

0

84200A8

IDE(AT)

4200

3.50

AUTO

N/ A

N/ A

0

0

0

0

84320A5

IDE(AT)

4320

3.50

AUTO

N/ A

N/ A

0

0

0

0

RLL

1369

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT

84320A8

IDE(AT)

4320

3.50

3H

84320D4

IDE(AT)

4320

3.50

AUTO

N/ A

N/ A

84320D5

IDE(AT)

4320

3.50

AUTO

N/ A

N/ A

AUTO

N/ A

3H

CODE

LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT

LHDS LCYL LSPT

0

0

0

16

8400

63

0

0

0

0

0

0

0

0

0

0

0

16

9924

63

N/ A

0

0

0

0 16

9924

63

15

816

32

16

683

38

16

654

63

16

842

63

16

1024

63

85120A

IDE(AT)

5120

3.50

85120A6

IDE(AT)

5120

3.50

RLL

85120A8

IDE(AT)

5120

3.50

0

0

0

85121A8

IDE(AT)

5121

3.50

AUTO

N/ A

N/ A

0

0

0

0

85250D6

IDE(AT)

5250

3.50

AUTO

N/ A

N/ A

0

0

0

0

86480A8

IDE(AT)

6480

3.50

AUTO

N/ A

N/ A

0

0

0

0

86480D6

IDE(AT)

6480

3.50

AUTO

N/ A

N/ A

0

0

0

0

86480D8

IDE(AT)

6480

3.50

AUTO

N/ A

N/ A

0

0

0

0

87000A8

IDE(AT)

700

3.50

AUTO

N/ A

N/ A

0

0

0

0

87000D8

IDE(AT)

7000

3.50

AUTO

N/ A

N/ A

0

0

0

0

88400D8

IDE(AT)

8400

3.50

AUTO

N/ A

N/ A

0

0

0

0

EXT-4175

ESDI-10M HZ

149.15

5.25

20

7

1224

34

EXT-4280

ESDI-10M HZ

149.1

5.25

FH

20

11

1224

34

EXT-4380

ESDI-10M HZ

319.61

5.25

FH

RLL

AUTO

N/ A

N/ A

20

15

1224

34

LXT-100S

SCSI

93.07

3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

8

733

31

LXT-200A

IDE(AT)

207

3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

7

1320

0

LXT-200S OPTION A

SCSI

207

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

7

1320

0

LXT-200S OPTION B

SCSI

207

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

7

1320

0

LXT-213A

IDE(AT)

212

3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

7

1320

0

LXT-213S OPTION A

SCSI

212

3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

7

1320

0

LXT-213S OPTION B

SCSI

212

3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

7

1320

0

LXT-340A

IDE(AT)

340

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

7

1560

0

LXT-340S OPTION A

SCSI

340

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

7

1560

0

LXT-340S OPTION B

SCSI

340

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

7

1560

0

LXT-437A

IDE(AT)

437

3.50

HHRLL 2

AUTO

N/ A

N/ A

150

9

1560

0

LXT-437S OPTION A

SCSI

437

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

9

1560

0

LXT-437S OPTION B

SCSI

437

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

9

1560

0

3H

FH

LXT-50S

SCSI

46.53

3.50

HH

RLL 1

AUTO

N/ A

N/ A

40

4

733

31

LXT-535A

IDE(AT)

528.48

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

11

1560

0

(continues)

1370

Appendix D—Technical Reference

Table D.12

M AXTOR CORPORATION Cont inued

M ODEL

INT

CAP

FF

HGT

CODE

LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT

LXT-535S OPTION A

SCSI

535

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

11

1560

0

LXT-535S OPTION B

SCSI

535

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

11

1560

0

M X9217SDN

SCSI-2 D

2170

3.50

3H

PRM L

AUTO

N/ A

N/ A

800

9

3703

0

LHDS LCYL LSPT

M X9217SDW

SCSI-2 WD

2170

3.50

3H

PRM L

AUTO

N/ A

N/ A

800

9

3703

0

M X9217SSN

SCSI-2

2170

3.50

3H

PRM L

AUTO

N/ A

N/ A

800

9

3703

0

M X9217SSW

SCSI SCA

2170

3.50

3H

PRM L

AUTO

N/ A

N/ A

800

9

3703

0

M XT-1240S

SCSI-2

1240

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

M XT-540A

IDE(AT)

528.48

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

16

1024

63

M XT-540AL

IDE(AT)

528.5

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

7

2234

0

16

1024

63

M XT-540SL

SCSI-2

540

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

PANTHER P0-12S

SCSI-2

1051

5.25

FH

RLL

AUTO

N/ A

N/ A

100

15

1795

0

PANTHER P1-08E

ESDI-24M HZ

696.4

5.25

FH

RLL

AUTO

N/ A

N/ A

100

9

1778

85

PANTHER P1-08S

SCSI-2

696.4

5.25

FH

RLL

AUTO

N/ A

N/ A

100

9

1778

85

PANTHER P1-12E

ESDI-24M HZ

1051.43

5.25

FH

AUTO

N/ A

N/ A

100K

0

15

1778

77

PANTHER P1-12S

SCSI-2

1005.48

5.25

FH

RLL

AUTO

N/ A

N/ A

100

19

1216

85

PANTHER P1-13E

ESDI-24M HZ

1160.67

5.25

FH

AUTO

N/ A

N/ A

N/ A

100

15

1778

85

PANTHER P1-16E

ESDI-24M HZ

1331.82

5.25

FH

RLL

AUTO

N/ A

N/ A

100

19

1778

77

PANTHER P1-17E

ESDI-24M HZ

1470.19

5.25

FH

RLL

AUTO

N/ A

N/ A

100

19

1778

85

5.25

AUTO

N/ A

N/ A

85

PANTHER P1-17S

SCSI-2

1470.19

RXT-800 SERIES

SCSI

0

XT 8800E

ESDI-10M HZ

694.68

XT-1050

ST-506/ 412

XT-1065

ST-506/ 412

XT-1085 XT-1105

FH

RLL

—

RLL

5.25

FH

RLL 1

39.25

5.25

FH

M FM

55.93

5.25

FH

ST-506/ 412

71.3

5.25

ST-506/ 412

87.89

5.25

XT-1120R

ST-506/ 412

104.85

XT-1140

ST-506/ 412

119.85

AUTO

100

19

1778

0

0

0

0

150

15

1274

71

N/ A

N/ A

150

5

902

17

M FM

919

919

150

7

918

17

FH

M FM

N/ A

N/ A

150

8

1024

17

FH

M FM

919

919

150

11

918

17

5.25

FH

RLL 2

N/ A

N/ A

70

8

1024

25

5.25

FH

M FM

N/ A

N/ A

150

15

918

17

N/ A

25

XT-1240R

ST-506/ 412

196.6

5.25

FH

RLL 2

N/ A

150

15

1024

XT-2085

ST-506/ 412

74.57

5.25

FH

M FM

1,225 1,225

150

7

1224

17

XT-2140

ST-506/ 412

117.19

5.25

FH

M FM

1,225 1,225

150

11

1224

17

XT-2190

ST-506/ 412

159.8

5.25

FH

M FM

N/ A

150

15

1224

17

N/ A

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT

CODE

LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT

XT-3170 NONSHROUDE

SCSI

141

5.25

FH

RLL

AUTO

N/ A

N/ A

20

9

1224

25

XT-3170 SHROUDED

SCSI

141

5.25

FH

RLL

AUTO

N/ A

N/ A

20

9

1224

25

XT-3280 NONSHROUDE

SCSI

235

5.25

FH

RLL

AUTO

N/ A

N/ A

20

15

1224

25

XT-3280 SHROUDED

SCSI

235

5.25

FH

RLL

AUTO

N/ A

N/ A

20

15

1224

25

XT-3380

SCSI

319.61

5.25

FH

RLL

AUTO

N/ A

N/ A

20

15

1224

34

XT-4170E

ESDI-10M HZ

153.53

5.25

FH

RLL 1

AUTO

N/ A

N/ A

30

7

1224

36

XT-4170SPCB REV. 3

SCSI

157.92

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

7

1224

36

XT-4170S PCB REV. 1

SCSI

157.92

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

7

1224

36

XT-4230E

ESDI-10M HZ

197.4

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

9

1224

36

XT-4280E

ESDI-10M HZ

241.27

5.25

FH

RLL

AUTO

N/ A

N/ A

30

11

1224

35

XT-4280S PCB REV. 3

SCSI

248.16

5.25

FH

RLL

AUTO

N/ A

N/ A

30

11

1224

36

XT-4280S PCB REV. 1

SCSI

248.16

5.25

FH

RLL

AUTO

N/ A

N/ A

30

11

1224

36

XT-4380E

ESDI-10M HZ

329.01

5.25

FH

RLL 1

AUTO

N/ A

N/ A

30

15

1224

36

XT-4380EF

ESDI-10M HZ

329.01

5.25

FH

RLL 1

AUTO

N/ A

N/ A

30

15

1224

36

XT-4380F PCB REV.3

SCSI

338.41

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1224

36

XT-4380S PCB REV. 3

SCSI

338.41

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1224

36

XT-4380S PCB REV. 1

SCSI

338.41

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1224

36

XT-8380DS

SCSI

360

5.25

FH

U

AUTO

N/ A

N/ A

150

8

1632

0

XT-8380E VER. 1 ESDI-15M HZ

360.97

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

8

1632

54

XT-8380E VER. 2 ESDI-15M HZ

360.97

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

8

1632

54

XT-8380E VER. 3 ESDI-15M HZ

360.97

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

8

1632

54

XT-8380E VER. 4 ESDI-15M HZ

360.97

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

8

1632

54

XT-8380E VER. 5 ESDI-15M HZ

360.97

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

8

1632

54

XT-8380E VER. 6 ESDI-15M HZ

360.97

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

8

1632

54

XT-8380EH VER. 1

ESDI-15M HZ

360.97

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

8

1632

54

XT-8380EH VER. 2

ESDI-15M HZ

360.97

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

8

1632

54

XT-8380EH VER. 3

ESDI-15M HZ

360.97

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

8

1632

54

XT-8380EH VER. 4

ESDI-15M HZ

360.97

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

8

1632

54

XT-8380EH VER. 5

ESDI-15M HZ

360.97

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

8

1632

54

1371

LHDS LCYL LSPT

(continues)

1372

Appendix D—Technical Reference

Table D.12

M AXTOR CORPORATION Cont inued

M ODEL

INT

XT-8380EH VER. 6

ESDI-15M HZ

360.97

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

8

1632

54

XT-8380S

SCSI

360.97

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

8

1632

54

XT-8380SH

SCSI

360.3

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

8

1632

54

XT-8610E VER. 1 ESDI-15M HZ

541.45

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

12

1632

54

XT-8610E VER. 2 ESDI-15M HZ

541.45

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

12

1632

54

XT-8610E VER. 3 ESDI-15M HZ

541.45

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

12

1632

54

XT-8610E VER. 4 ESDI-15M HZ

541.45

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

12

1632

54

XT-8610E VER. 5 ESDI-15M HZ

541.45

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

12

1632

54

XT-8610E VER. 6 ESDI-15M HZ

541.45

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

12

1632

54

XT-8702S

SCSI

616.68

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1487

54

XT-8760DS

SCSI

676

5.25

FH

U

AUTO

N/ A

N/ A

150

15

1632

0

XT-8760E VER. 1 ESDI-15M HZ

676.82

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

54

XT-8760E VER. 2 ESDI-15M HZ

676.82

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

54

XT-8760E VER. 3 ESDI-15M HZ

676.82

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

54

XT-8760E VER. 4 ESDI-15M HZ

676.82

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

54

XT-8760E VER. 5 ESDI-15M HZ

676.82

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

54

XT-8760E VER. 6 ESDI-15M HZ

676.82

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

54

XT-8760EH VER. 1

ESDI-15M HZ

676.82

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

54

XT-8760EH VER. 2

ESDI-15M HZ

676.82

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

54

XT-8760EH VER. 3

ESDI-15M HZ

676.82

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

54

XT-8760EH VER. 4

ESDI-15M HZ

676.82

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

54

XT-8760EH VER. 5

ESDI-15M HZ

676.82

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

54

XT-8760EH VER. 6

ESDI-15M HZ

676.82

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

54

XT-8760S

SCSI

676.82

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

54

XT-8760SH

SCSI

675.6

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

54

XT-8800E

ESDI-24M HZ

694

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1274

71

XT81000E

ESDI-24M HZ

889.89

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

71

Table D.13

CAP

FF

HGT

CODE

LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT

LHDS LCYL LSPT

QUANTUM CORPORATION

M ODEL

INT

CAP

FF

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

ATLAS II XP32181S

U-SCSI

2180

3.50

3H

RLL 1

AUTO

N/ A

N/ A

1000

6

5952

0

ATLAS II XP 32181SCA

SCSI SCA

2180

3.50

3H

RLL 1

AUTO

N/ A

N/ A

1000

6

5952

0

ATLAS II XP 32181W

U-SCSI W

2180

3.50

3H

RLL 1

AUTO

N/ A

N/ A

1000

6

5952

0

1373

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

ATLAS II XP 32181WD

U-SCSI WD

2180

3.50

3H

RLL 1

AUTO

N/ A

N/ A

1000

6

5952

0

ATLAS II XP32275D

0

0

0

ATLAS II XP34361S

U-SCSI

0 4360

3.50

3H

RLL 1

AUTO

N/ A

N/ A

1000

10

5952

0

ATLAS II XP 34361SCA

SCSI SCA

4360

3.50

3H

RLL 1

AUTO

N/ A

N/ A

1000

10

5952

0

ATLAS II XP34361W

U-SCSI W

4360

3.50

3H

RLL 1

AUTO

N/ A

N/ A

1000

10

5952

0

ATLAS II XP34361WD U-SCSI WD

4360

3.50

3H

RLL 1

AUTO

N/ A

N/ A

1000

10

5952

0

ATLAS II XP34550D

0

0

0

0

ATLAS II XP39100D

0

0

0

0

ATLAS II XP 39100SCA

SCSI SCA

8678

3.50

FH

RLL 1

AUTO

N/ A

N/ A

1000

20

5952

0

ATLAS XP31070S

SCSI-2 F

1075

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3832

0

ATLAS XP31070SCA

SCSI SCA

1075

3.50

3H

UNIDEN

5

3832

0

ATLAS XP31070W

SCSI-2 FW

1075

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3832

0

ATLAS XP31070WD

SCSI-2 FWD

1075

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3832

0

ATLAS XP32150S

SCSI-2 F

2150

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

10

3832

0

ATLAS XP32150W

SCSI-2 FW

2150

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

10

3832

0

ATLAS XP32150WD

SCSI-2 FWD

2150

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

10

3832

0

ATLAS XP34300S

SCSI-2 F

4300

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

20

3832

0

ATLAS XP34300W

SCSI-2 FW

4300

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

20

3832

0

ATLAS XP34300WD

SCSI-2 FWD

4300

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

20

3832

0

BIGFOOT 1.2AT

IDE(AT)

1280

5.25

4H

PRM L

AUTO

N/ A

N/ A

300

0

0

0

16

2492

63

BIGFOOT 1275

IDE(AT)

1275

5.25

4H

PRM L

2492

N/ A

N/ A

2

5738

0

16

2492

63

2

5738

0

16

2492

63

0

0

0

16

4994

63

4

5738

0

16

4994

63

16

4994

63

BIGFOOT 1275AT

IDE(AT)

1275

5.25

4H

PRM L

2492

N/ A

N/ A

BIGFOOT 2.5AT

IDE(AT)

2500

5.25

4H

PRM L

AUTO

N/ A

N/ A

BIGFOOT 2550

IDE(AT)

2500

5.25

4H

PRM L

4994

N/ A

N/ A

4994

300

BIGFOOT 2550AT

IDE(AT)

2500

5.25

4H

PRM L

N/ A

N/ A

4

5738

0

BIGFOOT CY 2.1AT

IDE(AT)

170.8

3.50

5

UNIDEN AUTO

N/ A

N/ A

250

16

4092

63

BIGFOOT CY 4.3AT

IDE(AT)

4300

3.50

5

UNIDEN AUTO

N/ A

N/ A

250

15

8960

63

BIGFOOT CY 6.4AT

IDE(AT)

6400

3.50

5

UNIDEN AUTO

N/ A

N/ A

250

15

13446

63

CAPELLA VP31110

SCSI-2 F

1108

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

4

4165

0

CAPELLA VP31110S

SCSI-2 F

0

3.50

HH

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

CAPELLA VP31110W

SCSI-2 FW

1108

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

4

4165

0

CAPELLA VP31110WD SCSI-2 FWD

1108

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

4

4165

0

CAPELLA VP32210

SCSI-2 F

2216

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

8

4165

0

CAPELLA VP32210S

SCSI-2 F

0

3.50

HH

RLL 1

300

0

0

0

CAPELLA VP32210W

SCSI-2 FW

2216

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

8

4165

0

2216

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

8

4165

0

CAPELLA VP32210WD SCSI-2 FWD

(continues)

1374

Appendix D—Technical Reference

Table D.13 M ODEL

QUANTUM CORPORATION Cont inued INT

CAP

FF

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

DAYTONA 127AT

IDE(AT)

127

2.50

3H

RLL 1

AUTO

N/ A

N/ A

350

0

0

0

DAYTONA 127S

SCSI

127

2.50

5H

RLL 1

AUTO

N/ A

N/ A

350

2

0

0

DAYTONA 170AT

IDE(AT)

170

2.50

3H

RLL 1

AUTO

N/ A

N/ A

350

0

0

0

DAYTONA 170S

SCSI

170

2.50

5H

RLL 1

AUTO

N/ A

N/ A

350

3

0

0

DAYTONA 256AT

IDE(AT)

256

2.50

3H

RLL 1

AUTO

N/ A

N/ A

350

0

0

0

DAYTONA 256S

SCSI

256

2.50

5H

RLL 1

AUTO

N/ A

N/ A

350

4

0

0

DAYTONA 341AT

IDE(AT)

341

2.50

3H

RLL 1

AUTO

N/ A

N/ A

350

0

0

0

DAYTONA 341S

SCSI

341

2.50

4H

RLL 1

AUTO

N/ A

N/ A

350

6

0

0

DAYTONA 514AT

IDE(AT)

514

2.50

3H

RLL 1

AUTO

N/ A

N/ A

350

0

0

0

DAYTONA 514S

SCSI

514

2.50

4H

RLL 1

AUTO

N/ A

N/ A

350

8

0

0

DSP3053L

SCSI-2 W

535

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

4

3117

0

DSP3053LD

SCSI-2 D

535

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

4

3117

0

DSP3085

SCSI-2

852

3.50

HH

NONE AUTO

N/ A

N/ A

0

14

0

57

DSP3105

SCSI-2

1050

3.50

HH

NONE AUTO

N/ A

N/ A

250

14

0

57

DSP3105D

SCSI-2

1050

3.50

HH

NONE AUTO

N/ A

N/ A

250

14

0

57

9

677

41

10

538

62

11

723

63

15

1011

44

16

997

63

DSP3107L

SCSI-2 D

1070

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

8

3117

0

DSP3107LD

SCSI-2 D

1070

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

8

3117

0

DSP3133L

SCSI-2

1338

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

10

3117

0

DSP3133LD

SCSI-2 D

1338

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

10

3117

0

DSP3160

SCSI-2

1600

3.50

3H

RLL 1

AUTO

N/ A

N/ A

350

16

2599

0

DSP3210

SCSI-2

2148

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

16

3045

0

EM PIRE 1080S

U-SCSI

1232

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

8

2874

0

EM PIRE 1400S

U-SCSI

1400

3.50

HH

PRM L

AUTO

N/ A

N/ A

500

8

3115

0

EM PIRE 1440S

U-SCSI

1440

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

8

0

0

EM PIRE 2100S

U-SCSI

2100

3.50

HH

PRM L

AUTO

N/ A

N/ A

500

12

3115

0

EM PIRE 2160S

U-SCSI

2160

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

12

0

0

EM PIRE 540S

U-SCSI

540

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

4

2874

0

EPS 510

SCSI-2 F

107

5.25

FH

UNIDEN

0

0

0

EPS 530

SCSI-2 F

267

5.25

FH

UNIDEN

0

0

0

EPS 540

SCSI-2 F

428

5.25

FH

UNIDEN

0

0

0

EPS 580

SCSI-2 F

856

5.25

FH

UNIDEN

0

0

0

EUROPA 1080AT

IDE(AT)

1.08

2.50

4H

PRM L

AUTO

N/ A

N/ A

350

8

2

0

15

2,352 60

EUROPA 540AT

IDE(AT)

540

2.50

5H

PRM L

AUTO

N/ A

N/ A

350

4

2

0

15

1,176 60

EUROPA 810AT

IDE(AT)

810

2.50

4H

PRM L

AUTO

N/ A

N/ A

350

6

2

0

15

1,764 60

FIREBALL 1080AT

IDE(AT)

1089

3.50

3H

PRM L

2112

N/ A

N/ A

500

4

3835

0

16

2112

63

FIREBALL 1080S

U-SCSI

1092.7 3.50

3H

PRM L

AUTO

N/ A

N/ A

500

4

3835

0

FIREBALL 1280AT

IDE(AT)

1282

3.50

3H

PRM L

AUTO

N/ A

N/ A

500

4

4142

0

16

2484

63

FIREBALL 1280S

U-SCSI

1282

3.50

3H

PRM L

AUTO

N/ A

N/ A

500

4

4142

0

1375

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

FIREBALL 540AT

IDE(AT)

544

3.50

3H

PRM L

N/ A

N/ A

500

2

3835

0

FIREBALL 540S

U-SCSI

545.4

3.50

3H

PRM L

AUTO

N/ A

N/ A

500

2

3835

0

FIREBALL 640AT

IDE(AT)

642

3.50

3H

PRM L

AUTO

N/ A

N/ A

500

2

4142

FIREBALL 640S

SCSI-2

852

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

FIREBALL ST 2.1S

U-SCSI

2111

3.50

0

0

6

1056

16

1056

63

0

16

1244

63

3653

0

16

1647

63

820

17

13

731

26

6

820

17

7

1024

17

9

1024

17

9

677

41

10

538

62

11

723

63

10

722

23

9

1024

36

5

966

34

FIREBALL ST 3.2AT

U-SCSI

3228

3.50

0

0

16

6256

63

FIREBALL ST 3.2S

U-SCSI

3228

3.50

0

0

16

6256

63 63

FIREBALL ST 4.3AT

U-SCSI

4310

3.50

0

0

9

14848

FIREBALL ST 4.3S

U-SCSI

4310

3.50

0

0

9

14848

63

FIREBALL ST 6.4AT

U-SCSI

6448

3.50

0

0

15

13328

63

FIREBALL ST 6.4S

U-SCSI

6448

3.50

0

0

15

13328

63

FIREBALL TM 1.0AT

IDE(AT)

1080

3.50

3H

400

2

6825

0

FIREBALL TM 1.0S

U-SCSI

1082

3.50

3H

0

0

0

FIREBALL TM 2.1AT

IDE(AT)

2168

3.50

3H

400

4

6825

0

FIREBALL TM 2.1S

U-SCSI

2168

3.50

3H

0

0

0

FIREBALL TM 2.5AT

PRM L

PRM L

AUTO

N/ A

N/ A

AUTO

N/ A

N/ A

AUTO

N/ A

N/ A

AUTO

N/ A

N/ A

AUTO

N/ A

N/ A

AUTO

N/ A

N/ A

0 400

0

0

0

6825

0

0

0

0

IDE(AT)

3254

3.50

3H

FIREBALL TM 3.2S

U-SCSI

3254

3.50

3H

0

0

0

GODRIVE 120AT

IDE(AT)

126.62 2.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1097

0

GODRIVE 120S

SCSI

126.62 2.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1097

0

GODRIVE 40AT

IDE(AT)

41.15

2.50

3H

RLL 1

AUTO

N/ A

N/ A

80

2

957

42

GODRIVE 40S

SCSI

42.9

2.50

3H

RLL 1

AUTO

N/ A

N/ A

80

2

870

0

GODRIVE 60AT

IDE(AT)

63.03

2.50

3H

RLL 1

AUTO

N/ A

N/ A

150

2

1097

0

GODRIVE 60S

SCSI

63

2.50

5H

RLL 1

AUTO

N/ A

N/ A

150

2

0

0

GODRIVE 80AT

IDE(AT)

82.31

2.50

3H

RLL 1

AUTO

N/ A

N/ A

80

4

957

42

GODRIVE 80S

SCSI

86.3

2.50

3H

RLL 1

AUTO

N/ A

N/ A

80

4

870

0

GODRIVE GLS 127AT IDE(AT)

127.9

2.50

3H

RLL 1

AUTO

N/ A

N/ A

350

3

1395

0

GODRIVE GLS 127S

127.91 2.50

3H

RLL 1

AUTO

N/ A

N/ A

350

3

1395

0

GODRIVE GLS 170AT IDE(AT)

170.78 2.50

3H

RLL 1

AUTO

N/ A

N/ A

350

4

1395

0

GODRIVE GLS 170S

0

FIREBALL TM 3.8AT

PRM L

6

FIREBALL TM 3.2AT

0

SCSI

170.78 2.50

3H

RLL 1

AUTO

N/ A

N/ A

350

4

1395

GODRIVE GLS 256AT IDE(AT)

SCSI

256.53 2.50

3H

RLL 1

AUTO

N/ A

N/ A

350

6

1395

0

GODRIVE GLS 256S

SCSI

256.53 2.50

3H

RLL 1

AUTO

N/ A

N/ A

350

6

1395

0

GODRIVE GLS 85AT

IDE(AT)

85.02

2.50

3H

RLL 1

AUTO

N/ A

N/ A

350

2

1395

0

GODRIVE GLS 85S

SCSI

85.03

2.50

3H

RLL 1

AUTO

N/ A

N/ A

350

2

1395

0

169.87 2.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1376

0

GODRIVE GRS 160AT IDE(AT) GODRIVE GRS 160S

SCSI-2

168.16 2.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1376

0

GODRIVE GRS 80AT

IDE(AT)

84.08

3H

RLL 1

AUTO

N/ A

N/ A

150

2

1376

0

2.50

(continues)

1376

Appendix D—Technical Reference

Table D.13

QUANTUM CORPORATION Cont inued

M ODEL

INT

CAP

FF

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

GODRIVE GRS 80S

SCSI-2

84.1

2.50

3H

RLL 1

AUTO

N/ A

N/ A

150

2

1376

0

GRAND PRIX XP32151S

SCSI

2152

3.50

HH

UNIDEN AUTO

N/ A

N/ A

800

10

0

0

GRAND PRIX XP32151SCA

SCSI

3215

3.50

HH

UNIDEN AUTO

N/ A

N/ A

0

0

0

GRAND PRIX XP34301S

20

0

0

0

0

0

0

0

0

SCSI

4306

3.50

HH

UNIDEN AUTO

N/ A

N/ A

GRAND PRIX XP34301SCA

SCSI

3430

3.50

HH

UNIDEN AUTO

N/ A

N/ A

LIGHTNING 365AT

IDE(AT)

365.7

3.50

HH

RLL 1

N/ A

N/ A

AUTO

800

300

LIGHTNING 365S

SCSI-2

366.5

3.50

HH

RLL 1

AUTO

N/ A

N/ A

300

2

0

0

LIGHTNING 540AT

IDE(AT)

541.3

3.50

HH

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

LIGHTNING 540S

SCSI-2

550.7

3.50

HH

RLL 1

AUTO

N/ A

N/ A

300

2

0

0

LIGHTNING 730AT

IDE(AT)

730.8

3.50

HH

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

LIGHTNING 730S

SCSI-2

733.1

3.50

HH

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

M AVERICK 270AT

IDE(AT)

270.66 3.50

3H

RLL 1

944

N/ A

N/ A

300

2

2740

0

M AVERICK 270S

SCSI

270.7

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

2

0

0

M AVERICK 540AT

IDE(AT)

541.32 3.50

3H

RLL 1

1120

N/ A

N/ A

300

4

2740

0

M AVERICK 540S

SCSI

541.5

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

PIONEER SG 1080AT

IDE(AT)

1000

3.50

3H

300

0

0

0

PIONEER SG 2110AT

IDE(AT)

2100

3.50

3H

300

0

0

0

PRODRIVE 1050S

SCSI

1054.71 3.50

HH

150

12

2448

0

RLL 1

AUTO

N/ A

N/ A

PRODRIVE 105AT

IDE(AT)

105.24 3.50

HH

RLL 2

AUTO

N/ A

N/ A

60

4

1219

0

PRODRIVE 105S

SCSI

104.99 3.50

HH

RLL 2

AUTO

N/ A

N/ A

50

6

1019

0

PRODRIVE 1080S

U-SCSI

1232

HH

RLL 1

AUTO

N/ A

N/ A

500

8

2874

0

3.50

12

976

61

16

1120

59

16

1416

63

14

944

40

16

1048

63

16

755

17

9

814

32

10

968

34

13

873

36

5

968

17

51

PRODRIVE 120AT

IDE(AT)

120.04 3.50

HH

RLL 1

AUTO

N/ A

N/ A

50

5

1123

0

PRODRIVE 120S

SCSI

120.04 3.50

HH

RLL 1

AUTO

N/ A

N/ A

50

5

1123

0

PRODRIVE 1225S

SCSI

1230.5 3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

14

2448

0

PRODRIVE 160AT

IDE(AT)

168.39 3.50

HH

RLL 1

AUTO

N/ A

N/ A

80

4

839

0

PRODRIVE 170AT

IDE(AT)

168.52 3.50

HH

RLL 1

AUTO

N/ A

N/ A

50

7

1123

0

PRODRIVE 170S

SCSI

169.52 3.50

HH

RLL 1

AUTO

N/ A

N/ A

50

7

1123

0

PRODRIVE 1800S

SCSI-2

1800

3.50

HH

RLL 1

AUTO

N/ A

N/ A

350

14

2959

0

PRODRIVE 210AT

IDE(AT)

209.19 3.50

HH

RLL 1

AUTO

N/ A

N/ A

50

7

1156

0

PRODRIVE 210S

SCSI

209.19 3.50

HH

RLL 1

AUTO

N/ A

N/ A

50

7

1156

0

PRODRIVE 40AT

IDE(AT)

42.27

3.50

HH

RLL 2

AUTO

N/ A

N/ A

50

3

834

0

PRODRIVE 40S

SCSI

42.27

3.50

HH

RLL 2

AUTO

N/ A

N/ A

50

3

834

0

PRODRIVE 425

IDE(AT)

426.57 3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

9

1512

0

16

1021

PRODRIVE 425AT

IDE(AT)

426

3.50

HH

RLL 1

N/ A

N/ A

N/ A

150

9

1520

44

16

1021

51

PRODRIVE 425IAT

IDE(AT)

426.57 3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

9

1512

0

16

1021

51

1377

Hard Disk Drives

M ODEL

INT

CAP

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

PRODRIVE 425IS

SCSI

426.57 3.50

FF

HH

RLL 1

AUTO

N/ A

N/ A

150

9

1512

0

PRODRIVE 425S

SCSI

426.57 3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

9

1512

0

PRODRIVE 525S REV. 1

SCSI-2

525

3.50

3H

RLL 1

AUTO

N/ A

N/ A

350

6

2448

0

PRODRIVE 525S REV. 2

SCSI-2

525

3.50

3H

RLL 1

AUTO

N/ A

N/ A

350

6

2448

0

PRODRIVE 52S

SCSI

52.42

3.50

HH

RLL 2

AUTO

N/ A

N/ A

60

2

1219

0

PRODRIVE 700S

SCSI

703.14 3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

8

2448

0

PRODRIVE 80AT

IDE(AT)

84.54

3.50

HH

RLL 2

AUTO

N/ A

N/ A

50

6

834

0

PRODRIVE 80S

SCSI

84.54

3.50

HH

RLL 2

AUTO

N/ A

N/ A

50

6

834

0

PRODRIVE ELS 127AT IDE(AT)

127.98 3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

2

1536

0

PRODRIVE ELS 127S

0

127.98 3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

2

1536

PRODRIVE ELS 170AT IDE(AT)

SCSI

170.81 3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

4

1536

0

PRODRIVE ELS 170S

170.81 3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

4

1536

0

SCSI

PRODRIVE ELS 42AT

IDE(AT)

42.12

3.50

3H

RLL 2

AUTO

N/ A

N/ A

250

1

1536

0

PRODRIVE ELS 42S

SCSI

42.12

3.50

3H

RLL 2

AUTO

N/ A

N/ A

250

1

1536

0

PRODRIVE ELS 85AT

IDE(AT)

85.03

3.50

3H

RLL 2

AUTO

N/ A

N/ A

250

2

1536

0

PRODRIVE ELS 85S

SCSI

85.03

0

3.50

3H

RLL 2

AUTO

N/ A

N/ A

250

2

1536

PRODRIVE LPS 105AT IDE(AT)

104.85 3.50

3H

RLL 2

AUTO

N/ A

N/ A

60

4

1219

0

PRODRIVE LPS 105S

104.85 3.50

3H

RLL 2

AUTO

N/ A

N/ A

60

4

1219

0

SCSI

PRODRIVE LPS 120AT IDE(AT)

122.24 3.50

3H

RLL 2

AUTO

N/ A

N/ A

250

2

1800

0

PRODRIVE LPS 120S

122

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

2

1800

0

127.9

3.50

3H

RLL

AUTO

N/ A

N/ A

300

0

0

0

SCSI

PRODRIVE LPS 127AT IDE(AT) PRODRIVE LPS 127S

SCSI-2

10

965

17

16

919

17

15

1011

22

5

968

17

10

977

17

16

755

17

5

901

53

16

919

17

16

1021

51

128.31 3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

2

1745

0

PRODRIVE LPS 170AT IDE(AT)

426.57 3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

9

1520

0

PRODRIVE LPS 170S

171.65 3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

2

2337

0

PRODRIVE LPS 210AT IDE(AT)

211

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

2

0

0

15

723

38

PRODRIVE LPS 240AT IDE(AT)

245.42 3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

4

1800

0

13

723

51

PRODRIVE LPS 240S

245

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

4

1800

0

PRODRIVE LPS 270AT IDE(AT)

270.66 3.50

3H

RLL 1

944

N/ A

N/ A

300

2

2740

0

14

944

40

PRODRIVE LPS 270S

270.66 3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

2

2740

0

340

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

4

1800

0

15

1011

44

0

SCSI-2

SCSI

SCSI-2

PRODRIVE LPS 340AT IDE(AT) PRODRIVE LPS 340S

342.63 3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

2337

PRODRIVE LPS 420AT IDE(AT)

SCSI-2

421.9

3.50

3H

RLL

AUTO

N/ A

N/ A

300

0

0

0

16

1021

51

PRODRIVE LPS 525AT IDE(AT)

524.86 3.50

HH

RLL 1

AUTO

N/ A

N/ A

250

6

2448

0

16

1017

63

0 8

751

17

16

1048

63

PRODRIVE LPS 525S

SCSI-2

525

3.50

HH

RLL 1

AUTO

N/ A

N/ A

250

6

0

PRODRIVE LPS 52AT

IDE(AT)

52.42

3.50

3H

RLL 2

AUTO

N/ A

N/ A

60

2

1219

0

PRODRIVE LPS 52S

SCSI

52.42

3.50

3H

RLL 2

AUTO

N/ A

N/ A

60

2

1219

0

541.32 3.50

3H

RLL 1

1120

N/ A

N/ A

300

4

2740

0

PRODRIVE LPS 540AT IDE(AT)

(continues)

1378

Appendix D—Technical Reference

Table D.13 M ODEL

QUANTUM CORPORATION Cont inued INT

CAP

FF

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT 0

PRODRIVE LPS 540S

SCSI-2

541.33 3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

2740

PRODRIVE LPS 80AT

IDE(AT)

85

3.50

3H

RLL 2

AUTO

N/ A

N/ A

60

0

0

0

PRODRIVE LPS 80S

SCSI

85

3.50

3H

RLL 2

AUTO

N/ A

N/ A

60

4

0

0

AUTO

16

611

17

Q-160

SCSI

200

5.25

HH

RLL 1

N/ A

N/ A

0

12

1800

0

Q-2010

SA1000

16.77

8.00

FH

M FM

256

256

12

2

512

32

Q-2020

SA1000

33.55

8.00

FH

M FM

256

256

12

4

512

32

Q-2030

SA1000

50.33

8.00

FH

M FM

256

256

12

6

512

32

Q-2040

SA1000

67.1

8.00

FH

M FM

256

256

12

8

512

32

Q-2080

SA1000

134.41 8.00

FH

M FM

256

256

8

7

1172

32

Q-250

SCSI

53.93

5.25

HH

RLL 1

AUTO

256

256

25

4

823

32

Q-280

SCSI

80.9

5.25

HH

RLL 1

AUTO

256

256

25

6

823

32

Q-510

ST-506/ 412

8.91

5.25

HH

M FM

256

256

0

2

512

17

Q-520

ST-506/ 412

17.82

5.25

HH

M FM

256

256

0

4

512

17

Q-540

ST-506/ 412

35.65

5.25

FH

M FM

256

256

15

8

512

17

SATURN VP31080

SCSI-2 F

1085

3.50

3H

UNIDEN N/ A

N/ A

N/ A

800

0

0

0

SATURN VP31080S

SCSI-2

1080

3.50

3H

RLL 1

5

0

0

SATURN VP32170

SCSI-2 F

2170

3.50

3H

UNIDEN N/ A

N/ A

N/ A

800

0

0

0

SATURN VP32170S

SCSI-2

2170

3.50

3H

RLL 1

AUTO

N/ A

N/ A

0

0

0

SIROCCO 1700AT

IDE(AT)

1700

3.50

3H

UNIDEN AUTO

N/ A

N/ A

400

4

0

0

16

3309

63

SIROCCO 2550AT

IDE(AT)

2250

3.50

3H

UNIDEN AUTO

N/ A

N/ A

400

6

0

0

16

4969

63

TRAILBLAZER 420AT

IDE(AT)

421.97 3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

2

3653

0

16

1010

51 51

3432

3432

TRAILBLAZER 420S

SCSI-2

425

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

2

3653

0

16

1010

TRAILBLAZER 635AT

IDE(AT)

636.86 3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

3

3653

0

16

1234

63

TRAILBLAZER 840S

SCSI-2

852

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

3

3653

0

16

1647

63

TRAILBLAZER 850AT

IDE(AT)

850

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

3653

0

16

1647

63

TRAILBLAZER 850S

SCSI-2

852

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

3653

0

16

1647

63

VIKING 2.2S

U-SCSI

2275

3.50

6

0

0

0

VIKING 2.2SCA

U-SCSI W

2275

3.50

6

0

0

0

VIKING 4.5S

U-SCSI

2275

3.50

6

0

0

0

VIKING 4.5SCA

U-SCSI W

4550

3.50

6

0

0

0

Table D.14

SEAGATE TECHNOLOGY, INC.

M ODEL

INT

CAP

FF

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

BARRACUDA 1 (VER. 1)

SCSI-2

1690

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

15

2706

0

BARRACUDA 1 (VER. 2)

SCSI-2 W

0

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

15

2706

0

0

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

0

0

0

BARRACUDA 2 (VER. 1)

1379

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

BARRACUDA 2 (VER. 2)

SCSI-2

0

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

0

0

0

BARRACUDA 2 (VER. 3)

SCSI-2 W

2139

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2707

0

BARRACUDA 2LP (VER. 1)

SCSI-2 F

0

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3711

0

BARRACUDA 2LP (VER. 2)

SCSI-2 F

0

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3711

0

BARRACUDA 2LP (VER. 3)

SCSI-2 F

0

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3711

0

BARRACUDA 2LP (VER. 4)

SCSI-2 F

0

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3711

0

0

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

0

0

0

BARRACUDA 4 (VER. 1) BARRACUDA 4 (VER. 2)

SCSI-2 W

4297

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

21

3711

0

BARRACUDA 4LP (VER. 1)

U-SCSI

0

3.50

3H

RLL

AUTO

N/ A

N/ A

1000

5

5167

0

BARRACUDA 4LP (VER. 2)

U-SCSI

0

3.50

3H

RLL

AUTO

N/ A

N/ A

1000

5

5167

0

BARRACUDA 9 (VER. 1)

U-SCSI

9100

3.50

HH

PRM L

AUTO

N/ A

N/ A

1000

20

5273

0

BARRACUDA 9 (VER. 2)

U-SCSI W

9100

3.50

HH

PRM L

AUTO

N/ A

N/ A

1000

20

5273

0

CHEETAH 4LP (VER. 1)

U-SCSI

4550

3.50

3H

UNIDEN AUTO

N/ A

N/ A

300

6

0

0

CHEETAH 4LP (VER. 2)

U-SCSI W

4550

3.50

3H

UNIDEN AUTO

N/ A

N/ A

8

6526

0

CHEETAH 9 (VER. 1)

U-SCSI

9100

3.50

HH

AUTO

N/ A

N/ A

16

6526

0

CHEETAH 9 (VER. 2)

U-SCSI W

9100

3.50

HH

AUTO

N/ A

N/ A

16

6526

0

DECATHLON 1080

IDE(AT)

1083.8 3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

4834

DECATHLON 540

IDE(AT)

540.1

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

2

4834

DECATHLON 545 (VER. 1)

SCSI-2

545.29 3.50

3H

RLL 1

AUTO

N/ A

N/ A

0

4

3420

77

DECATHLON 545 (VER. 2)

IDE(AT)

545.51 3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

3420

DECATHLON 850 (VER. 1)

IDE(AT)

854.7

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

4

0

DECATHLON 850 (VER. 2)

IDE(AT)

854.7

3.50

4H

RLL 1

AUTO

N/ A

N/ A

500

4

ELITE 23 (VER. 1)

U-SCSI

23400

5.25

FH

UNIDEN AUTO

N/ A

N/ A

28

ELITE 23 (VER. 2)

U-SCSI W

23400

5.25

FH

UNIDEN AUTO

N/ A

N/ A

9080

5.25

FH

RLL 1

AUTO

N/ A

N/ A

9090

5.25

FH

RLL 1

AUTO

0

3.50

HH

RLL 1

AUTO

ELITE 9 (VER. 1) ELITE 9 (VER. 2) HAWK 1

SCSI-2 W

N/ A

N/ A

16

1016

63

0

16

2100

63

0

16

1050

63

0

16

1057

63

0

32

828

63

0

0

32

828

63

6880

0

28

6880

0

500

27

4925

0

500

27

4925

0

200

0

0

0

(continues)

1380

Appendix D—Technical Reference

Table D.14

SEAGATE TECHNOLOGY, INC. Cont inued

M ODEL

INT

CAP

FF

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

HAWK 1LP (VER. 1)

SCSI-2 FW

0

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

9

2700

84

HAWK 1LP (VER. 2)

SCSI-2

1052.4 3.50

3H

RLL 1

AUTO

N/ A

N/ A

200

9

2700

0

HAWK 1LP (VER. 3)

SCSI-2 F

0

3H

RLL 1

AUTO

N/ A

N/ A

500

5

2700

78

0

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

0

0

0

HAWK 2 (VER. 2)

SCSI-2 W

0

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2626

0

HAWK 2 (VER. 3)

SCSI-2 FW

1430

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

13

2626

0

HAWK 2 (VER. 4)

SCSI-2 FW

1430

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

13

2626

0

HAWK 2LP (VER. 1)

SCSI-2 F

0

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3992

103

HAWK 2LP (VER. 2)

SCSI-2 W

0

3.50

3H

RLL

AUTO

N/ A

N/ A

800

5

3992

0

HAWK 2LP (VER. 3)

SCSI-2

1700

3.50

3H

RLL

AUTO

N/ A

N/ A

0

0

0

0

HAWK 2LP (VER. 4)

SCSI-2

1700

3.50

3H

RLL

AUTO

N/ A

N/ A

0

0

0

0

HAWK 2XL (VER. 1)

SCSI-2 F

0

3.50

3H

RLL

AUTO

N/ A

N/ A

800

4

4569

0

HAWK 2 (VER. 1)

3.50

HAWK 2XL (VER. 2)

SCSI-2 FW

0

3.50

3H

RLL

AUTO

N/ A

N/ A

800

4

4569

0

HAWK 4 (VER. 1)

SCSI-2 FW

0

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

19

3992

110

HAWK 4 (VER. 2)

SCSI-2 F

0

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

19

3992

110

M ARATHON 130SL

IDE(44PIN)

131.07 2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

2

0

0

13

419

47

M ARATHON 170SL

IDE(44PIN)

171.63 2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

16

873

24

M ARATHON 210SL

IDE(44PIN)

210.43 2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

8

988

52

M ARATHON 260SL

IDE(44PIN)

262.19 2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

15

569

60

M ARATHON 340

IDE(AT)

341.44 2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

6

0

0

14

934

51

M ARATHON 420SL

IDE(44PIN)

420.8

5H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

16

988

53

M ARATHON 455

IDE(AT)

455.29 2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

6

0

0

16

942

59

M ARATHON 520

IDE(44PIN)

524.35 2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

6

0

0

16

1016

63

M ARATHON 810

IDE(44PIN)

810

2.50

5H

RLL 1

AUTO

N/ A

N/ A

300

8

0

0

16

1571

63

M EDALIST 1012

IDE(AT)

1012

3.50

3H

AUTO

N/ A

N/ A

0

0

0

16

2098

63

M EDALIST 1080 (VER. 1)

IDE(AT)

1083.2 3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

6

0

0

16

2099

63

M EDALIST 1080 (VER. 2)

IDE(AT)

1088

3H

RLL 1

AUTO

N/ A

N/ A

300

6

0

0

16

2099

63

2.50

3.50

M EDALIST 1080SL

IDE(AT)

1083.8 3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

4834

0

16

2100

63

M EDALIST 1270

IDE(AT)

1282.8 3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

16

2485

63

M EDALIST 1270SL

IDE(AT)

1282.4 3.50

4H

RLL 1

AUTO

N/ A

AUTO

300

4

5414

0

16

2485

63

M EDALIST 1276

IDE(AT)

1275

AUTO

N/ A

N/ A

300

0

0

0

16

2482

63

M EDALIST 1640

IDE(AT)

1625.7 3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

6

4834

0

16

3150

63

M EDALIST 1720

IDE(AT)

1705

3.50

AUTO

N/ A

N/ A

0

0

0

16

3305

68

M EDALIST 1722

IDE(AT)

1722

3.50

3H

AUTO

N/ A

N/ A

0

0

0

16

3303

63

M EDALIST 210XE

IDE(AT)

213.9

3.50

3H

AUTO

N/ A

N/ A

2

0

0

12

1024

34

M EDALIST 2122

IDE(AT)

212.2

3.50

2

AUTO

N/ A

N/ A

0

0

0

64

1023

63

3.50

RLL 1

300

1381

Hard Disk Drives

M ODEL

INT

CAP

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

M EDALIST 2140

IDE(AT)

2113.4 3.50

FF

3H

RLL 1

AUTO

N/ A

N/ A

500

8

4726

0

16

4095

63

M EDALIST 270 XE (VER. 1)

IDE(AT)

272.7

3H

RLL 1

AUTO

N/ A

N/ A

300

2

0

0

14

761

50

RLL 1

300

4

0

0

14

761

50

0

0

0

16

6253

63 62

3.50

M EDALIST 270 XE (VER. 2)

IDE(AT)

272.74 3.50

3H

M EDALIST 3232

IDE(AT)

3232

3.50

3H

M EDALIST 340XE

IDE(AT)

341.31 3.50

3H

M EDALIST 425XE

IDE(AT)

428.1

3.50

3H

M EDALIST 4342

IDE(AT)

4342

3.50

3H

M EDALIST 455

IDE(AT)

452.41 3.50

3H

M EDALIST 540

IDE(AT)

528.48 3.50

3H

AUTO

N/ A

N/ A

AUTO

N/ A

N/ A

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

14

768

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

15

899

62

AUTO

N/ A

N/ A

0

0

0

15

8894

63

RLL 2

AUTO

N/ A

N/ A

150

5

1691

0

14

1018

62

RLL 2

AUTO

N/ A

N/ A

200

5

0

0

16

1024

63

M EDALIST 540SL

IDE(AT)

540.1

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

2

4834

0

16

1050

63

M EDALIST 545XE

IDE(AT)

545

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

16

1057

63

M EDALIST 630XE

IDE(AT)

631.1

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

16

1223

63

M EDALIST 636

IDE(AT)

635

3.50

UNIDEN AUTO

N/ A

N/ A

300

0

0

0

16

1241

63

M EDALIST 720

IDE(AT)

722.02 3.50

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

16

1399

63

M EDALIST 850

IDE(AT)

852

AUTO

N/ A

N/ A

0

0

0

16

1652

68

3H

3.50

M EDALIST 850SL

IDE(AT)

854.7

3.50

AUTO

N/ A

AUTO

4

4834

0

16

1656

63

M EDALIST PRO 2160

IDE(AT)

810

3.50

4H

UNIDEN AUTO

RLL 1

N/ A

N/ A

300

8

0

0

16

4095

63

M EDALIST PRO 2520

IDE(AT)

810

3.50

UNIDEN AUTO

N/ A

N/ A

8

0

0

16

4970

63

M EDALIST PRO 6450

IDE(AT)

6400

3.50

3H

AUTO

N/ A

N/ A

0

0

0

15

13328 63

M EDALIST PRO 6451

IDE(AT)

6400

3.50

3H

AUTO

N/ A

N/ A

0

0

0

15

13328 63

ST1057A

IDE(AT)

53.47

3.50

HH

RLL

AUTO

N/ A

N/ A

150

6

1024

17

6

1024

17

ST1057N

SCSI-2

49.09

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

3

940

34

ST1090A

IDE(AT)

79.58

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

5

1072

29

16

335

29

ST1090N

SCSI

79.28

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

5

1068

29

N/ A

10

1024

17

10

536

36

ST1096N

SCSI

84.42

3.50

HH

RLL 2

AUTO

N/ A

150

7

906

26

ST1100

ST-506/ 412

83.97

3.50

HH

M FM

AUTO

1,073 1,073

150

9

1072

17

ST1102A

IDE(AT)

89.12

3.50

HH

RLL

AUTO

N/ A

N/ A

50

10

1024

17

ST1102N

SCSI-2

83.99

3.50

HH

RLL

AUTO

N/ A

N/ A

50

5

965

0

ST1106R

ST-506/ 412

91.04

3.50

HH

RLL 2

978

978

50

7

977

26

ST1111A

IDE(AT)

98.79

3.50

HH

RLL 2

N/ A

N/ A

70

5

1072

36

ST1111E

ESDI-10M HZ 98.79

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

5

1072

36

ST1111N

SCSI

98.42

3.50

HH

RLL 2

AUTO

N/ A

N/ A

70

5

1068

36

ST11200N

SCSI-2

1054

3.50

HH

RLL 1

AUTO

N/ A

N/ A

200

15

1872

0

ST11200NC

SCSI SCA

1050

3.50

HH

RLL 1

AUTO

N/ A

N/ A

200

15

1877

0

ST11200ND

SCSI-2 D

1050

3.50

HH

RLL 1

AUTO

N/ A

N/ A

200

15

1877

0

ST11201N

SCSI-2

1050

3.50

HH

RLL 1

AUTO

N/ A

N/ A

200

15

1877

0

ST11201ND

SCSI-2 D

1050

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

15

1877

0

AUTO

(continues)

1382

Appendix D—Technical Reference

Table D.14

SEAGATE TECHNOLOGY, INC. Cont inued

M ODEL

INT

ST1126A

IDE(AT)

111.41 3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

7

1072

29

ST1126N

SCSI

111

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

7

1068

29

ST1133A

IDE(AT)

117.22 3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

5

1272

36

CAP

FF

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

ST1133N

SCSI-2

116.85 3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

5

1268

36

ST1144A

IDE(AT)

130.69 3.50

HH

RLL

AUTO

N/ A

N/ A

150

7

0

0

ST1144N

SCSI-2

125

3.50

HH

RLL

AUTO

N/ A

N/ A

50

7

0

0

ST1150R

ST-506/ 412

128.43 3.50

HH

RLL 2

AUTO

300

1,073

150

9

1072

26

ST1156A

IDE(AT)

138.31 3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

7

1072

36

ST1156E

ESDI-10M HZ

138.31 3.50

HH

RLL 2

AUTO

N/ A

N/ A

70

7

1072

36

ST1156N

SCSI

137.79 3.50

HH

RLL 2

AUTO

N/ A

N/ A

70

7

1068

36

ST1156NS

SCSI-2

137.79 3.50

HH

RLL 2

AUTO

N/ A

N/ A

70

7

1068

36

ST1162A

IDE(AT)

143.25 3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

9

1072

29

ST1162N

SCSI

142.71 3.50

HH

RLL 2

AUTO

N/ A

N/ A

70

9

1068

29

ST11700N

SCSI-2

1430

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

13

2626

0

ST11700ND

SCSI-2 D

1430

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

13

2626

0

ST1186A

IDE(AT)

164.11 3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

7

1272

36

ST1186N

SCSI-2

163.6

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

7

1268

36

ST11900N

SCSI-2

1700

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

15

2621

0

ST11900NC

SCSI SCA

1700

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

15

2621

0

ST11900ND

SCSI-2

1700

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

15

2621

0

ST11900W

SCSI-2 FW

1430

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

13

2626

0

ST11900WC

SCSI-2 FW

1700

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

15

2621

83

ST11900WD

SCSI-2 FW

1430

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

13

2626

0

ST11950N

SCSI-2

1690

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

15

2706

0

16

469

29

10

636

36

15

1001

17

14

536

36

16

603

29

14

636

36

12

804

36

ST11950ND

SCSI-2

1690

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

15

2706

0

ST11950W

SCSI-2 W

1690

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

15

2706

0

ST11950WD

SCSI-2 WD

1690

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

15

2706

0

ST1201A

IDE(AT)

177.83 3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

9

1072

36

ST1201E

ESDI-10M HZ

177.83 3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

9

1072

36

ST1201N

SCSI

177.16 3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

9

1068

36

ST1201NS

SCSI-2

177.16 3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

9

1068

36

ST1239A

IDE(AT)

211

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

9

1272

0

14

814

36

12

954

36

ST1239A (SHROUDED)

IDE(AT)

211

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

9

1272

0

ST1239N

SCSI-2

210.34 3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

9

1268

36

ST124

ST-506/ 412

21.41

HH

M FM

670

616

616

150

4

615

17

ST12400N

SCSI-2

2148

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2621

0

ST12400NC

SCSI SCA

2100

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2626

0

3.50

1383

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

ST12400ND

SCSI-2 D

2148

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2621

0

ST12400W

SCSI-2 W

21

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2626

0

ST12400WC

SCSI-2 W

2148

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2621

0

ST12400WD

SCSI-2 WD

21

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2626

0

ST12401N

SCSI-2

21

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2626

0

ST12401ND

SCSI-2 D

21

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2626

0

ST12450W

SCSI-2 FW

2134

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

18

2710

0

ST12450WD

SCSI-2 FW

2134

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

18

2710

0

ST125

ST-506/ 412

21.41

3.50

HH

M FM

AUTO

616

616

150

4

615

17

ST125-1

ST-506/ 412

21.41

3.50

HH

M FM

AUTO

616

616

150

4

615

17

ST12550N

SCSI-2

2139

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2707

0

ST12550ND

SCSI-2

2139

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2707

0

ST12550W

SCSI-2 W

2139

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2707

0

ST12550WD

SCSI-2 WD

2139

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2707

0

ST12551N

SCSI-2

2100

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2756

0

ST12551ND

SCSI-2 D

2100

3.50

HH

RLL 1

AUTO

N/ A

N/ A

500

19

2756

0

ST125A (10-PIN VER.)

IDE(AT)

21.51

3.50

HH

RLL 2

AUTO

N/ A

N/ A

70

4

404

26

4

404

26

ST125A (6-PIN VER.)

IDE(AT)

21.51

3.50

HH

RLL 2

AUTO

N/ A

N/ A

70

4

404

26

4

404

26

ST125A-1 (10-PIN VER.)

IDE(AT)

21.51

3.50

HH

RLL 2

AUTO

N/ A

N/ A

70

4

404

26

4

404

26

4

404

26

4

407

26

ST125A-1 (6-PIN VER.)

IDE(AT)

21.51

3.50

HH

RLL 2

AUTO

N/ A

N/ A

70

4

404

26

ST125N

SCSI

21.67

3.50

HH

RLL 2

AUTO

N/ A

N/ A

70

4

407

26

ST125N-1

SCSI

21.67

3.50

HH

RLL 2

AUTO

N/ A

N/ A

70

4

407

26

ST125R

ST-506/ 412

21.51

3.50

HH

RLL 2

404

N/ A

N/ A

150

4

404

26

ST1274A

IDE(AT)

21.67

3.50

HH

RLL 2

AUTO

N/ A

N/ A

70

4

407

26

ST137R

ST-506/ 412

32.74

3.50

HH

RLL 2

AUTO

70

4

615

26

ST138

ST-506/ 412

32.11

3.50

HH

M FM

AUTO

616

616

150

6

615

17

ST138-1

ST-506/ 412

32.11

3.50

HH

M FM

AUTO

616

616

150

6

615

17

ST138A (10-PIN VER.)

IDE(AT)

32.16

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

4

604

26

4

604

26

ST138A (6-PIN VER.)

IDE(AT)

32.16

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

4

604

26

4

604

26

ST138A-1 (10-PIN VER.)

IDE(AT)

32.16

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

4

604

26

4

604

26

4

604

26

ST138A-1 (6-PIN VER.)

IDE(AT)

32.16

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

4

604

26

ST138N

SCSI

32.74

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

4

615

26

ST138N-1

SCSI

32.74

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

4

615

26

(continues)

1384

Appendix D—Technical Reference

Table D.14

SEAGATE TECHNOLOGY, INC. Cont inued

M ODEL

INT

CAP

FF

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

ST138R

ST-506/ 412

32.74

3.50

HH

RLL 2

AUTO

616

616

150

4

615

26

ST138R-1

ST-506/ 412

32.74

3.50

HH

RLL 2

AUTO

616

616

150

4

615

26

ST1400A (J6-4 PINS)

IDE(AT)

331

3.50

HH

RLL

AUTO

N/ A

N/ A

150

7

1478

0

12

1018

53

ST1400A (J6-6 PINS)

IDE(AT)

331

3.50

HH

RLL

AUTO

N/ A

N/ A

150

7

1478

0

12

1018

53

ST1400N

SCSI-2

331

3.50

HH

RLL

AUTO

N/ A

N/ A

150

7

1476

0

ST1401A (J6-4 PINS)

IDE(AT)

340

3.50

HH

RLL

AUTO

N/ A

N/ A

150

9

1100

0

15

726

61

ST1401A (J6-6 PINS)

IDE(AT)

340

3.50

HH

RLL

AUTO

N/ A

N/ A

150

9

1100

0

15

726

61

ST1401N

SCSI-2

340

3.50

HH

RLL

AUTO

N/ A

N/ A

150

9

1100

0

ST14207N

SCSI-2 FW

4295

3.50

3H

RLL 1

AUTO

N/ A

N/ A

999

20

3924

96

ST14207W

SCSI-2 FW

4295

3.50

3H

RLL 1

AUTO

N/ A

N/ A

999

20

3924

96

ST14207WC

SCSI-2 FW

4295

3.50

3H

RLL 1

AUTO

N/ A

N/ A

999

20

3924

96

ST1480A (J6-4 PINS)

IDE(AT)

426

3.50

HH

RLL

AUTO

N/ A

N/ A

150

9

1478

0

15

895

62

ST1480A (J6-6 PINS)

IDE(AT)

426

3.50

HH

RLL

AUTO

N/ A

N/ A

150

9

1478

0

15

895

62

ST1480N

SCSI-2

426

3.50

HH

RLL

AUTO

N/ A

N/ A

150

9

1476

0

ST1480NV

SCSI-2

426

3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

9

1478

0

ST1481N

SCSI-2

426

3.50

HH

RLL

AUTO

N/ A

N/ A

150

9

1476

0

ST151

ST-506/ 412

42.51

3.50

HH

M FM

AUTO

978

978

150

5

977

17

ST15150DC

SCSI-2 FW

4294

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

21

3711

0

ST15150N

SCSI-2 W

4297

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

21

3711

0

ST15150ND

SCSI-2 W

4294

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

21

3711

0

ST15150W

SCSI-2 FW

4294

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

21

3711

0

ST15150WC

SCSI-2 FW

4294

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

21

3711

0

ST15150WD

SCSI-2 FW

4294

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

21

3711

0

ST15230DC

SCSI SCA

4

3.50

HH

UNIDEN AUTO

N/ A

N/ A

800

19

3992

0

ST15230N

SCSI-2 F

4294

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

19

3992

110

ST15230NC

SCSI-2 F

4294

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

19

3992

110

ST15230ND

SCSI-2 F

4596

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

19

3992

110

ST15230W

SCSI-2 FW

4294

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

19

3992

110

ST15230WC

SCSI-2 FW

4294

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

19

3992

110

ST15230WD

SCSI-2 FW

4294

3.50

HH

RLL 1

AUTO

N/ A

N/ A

800

19

3992

0

ST157A (10-PIN VER.) IDE(AT)

44.72

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

6

560

26

6

560

26

ST157A (6-PIN VER.)

IDE(AT)

44.72

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

6

560

26

6

560

26

ST157A-1 (10-PIN VER.)

IDE(AT)

44.72

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

6

560

26

6

560

26

6

560

26

ST157A-1 (6-PIN VER.)

IDE(AT)

44.72

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

6

560

26

ST157N

SCSI

48.96

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

6

613

26

ST157N-1

SCSI

48.96

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

6

613

26

Hard Disk Drives

1385

M ODEL

INT

CAP

FF

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

ST157R

ST-506/ 412

49.12

3.50

HH

RLL 2

616

616

150

6

615

26

AUTO

ST157R-1

ST-506/ 412

49.12

3.50

HH

RLL 2

AUTO

616

616

150

6

615

26

ST1581N

SCSI-2

525

3.50

HH

RLL

AUTO

N/ A

N/ A

150

9

1476

0

ST177N

SCSI

61.3

3.50

HH

RLL 2

AUTO

N/ A

N/ A

150

5

921

26

ST1830N

SCSI-2 F

702

3.50

HH

RLL

AUTO

N/ A

N/ A

0

0

0

0

ST19101DC

U-SCSI D

9100

3.50

HH

AUTO

N/ A

N/ A

16

6526

0

ST19101N

U-SCSI

9100

3.50

HH

AUTO

N/ A

N/ A

16

6526

0

ST19101W

U-SCSI W

9100

3.50

HH

AUTO

N/ A

N/ A

16

6526

0

ST19101WC

U-SCSI W

9100

3.50

HH

AUTO

N/ A

N/ A

16

6526

0

ST19101WD

U-SCSI WD

9100

3.50

HH

AUTO

N/ A

N/ A

16

6526

0

ST19171DC

U-SCSI D

9100

3.50

HH

PRM L

AUTO

N/ A

N/ A

1000

20

5273

0

ST19171N

U-SCSI

9100

3.50

HH

PRM L

AUTO

N/ A

N/ A

1000

20

5273

0

ST19171W

U-SCSI W

9100

3.50

HH

PRM L

AUTO

N/ A

N/ A

1000

20

5273

0

ST19171WC

U-SCSI W

9100

3.50

HH

PRM L

AUTO

N/ A

N/ A

1000

20

5273

0

ST19171WD

U-SCSI WD

9100

3.50

HH

PRM L

AUTO

N/ A

N/ A

1000

20

5273

0

ST1950N

SCSI-2 F

803

3.50

HH

RLL

AUTO

N/ A

N/ A

0

13

1575

0

ST1980N

SCSI-2

860

3.50

HH

RLL 1

AUTO

N/ A

N/ A

200

13

1730

0

ST1980NC

SCSI SCA

860

3.50

HH

RLL 1

AUTO

N/ A

N/ A

200

13

1730

0

ST1980ND

SCSI-2 D

860

3.50

HH

RLL 1

AUTO

ST206

ST-506/ 412

5.32

5.25

HH

M FM

ST2106E

ESDI-10M HZ

94.37

5.25

HH

RLL 2

AUTO

N/ A

N/ A

200

13

1730

0

128

307

0

2

306

17

N/ A

N/ A

100

5

1024

36

ST2106N

SCSI

94.18

5.25

HH

RLL 2

AUTO

N/ A

N/ A

100

5

1022

36

ST2106NM

SCSI

94.18

5.25

HH

RLL 2

AUTO

N/ A

N/ A

100

5

1022

36

ST212 (VER. 1)

ST-506/ 412

10.65

5.25

HH

M FM

319

128

307

11

4

306

17

ST212 (VER. 2)

ST-506/ 412

10.65

5.25

HH

M FM

319

128

307

11

4

306

17

ST212 (VER. 3)

ST-506/ 412

10.65

5.25

HH

M FM

319

128

307

11

4

306

17

ST2125N

SCSI

107

5.25

HH

RLL

AUTO

N/ A

N/ A

100

3

1544

0

ST2125NM

SCSI

107

5.25

HH

RLL

AUTO

N/ A

N/ A

100

3

1544

0

ST2125NV

SCSI

107

5.25

HH

RLL

AUTO

N/ A

N/ A

100

3

1544

0

ST213

ST-506/ 412

10.7

5.25

HH

M FM

670

300

N/ A

20

2

615

17

ST2182E

ESDI-15M HZ

160.69 5.25

HH

RLL 2

AUTO

N/ A

N/ A

100

4

1453

54

ST2209N

SCSI

183

5.25

HH

RLL

AUTO

N/ A

N/ A

100

5

1544

0

ST2209NM

SCSI

183

5.25

HH

RLL

AUTO

N/ A

N/ A

100

5

1544

0

ST2209NV

SCSI

183

5.25

HH

RLL

AUTO

N/ A

N/ A

100

5

1544

0

ST224N

SCSI

21.41

5.25

HH

RLL 2

AUTO

N/ A

N/ A

100

4

615

17

ST225

ST-506/ 412

21.41

5.25

HH

M FM

670

300

N/ A

100

4

615

17

N/ A

N/ A

ST225N

SCSI

21.41

5.25

HH

RLL

670

ST225R

ST-506/ 412

21.17

5.25

HH

RLL 2

667

100

4

615

17

100

2

667

31

(continues)

1386

Appendix D—Technical Reference

Table D.14 M ODEL

SEAGATE TECHNOLOGY, INC. Cont inued INT

CAP

FF

HGT

CODE LZ

WP

RW C

N/ A

N/ A

ST2274A

IDE(AT)

241.5

5.25

HH

RLL 2

AUTO

ST238

ST-506/ 412

32.74

5.25

HH

RLL 2

615

ST2383A

IDE(AT)

338.1

5.25

HH

RLL 2

AUTO

N/ A

ST2383E

ESDI-15M HZ

338.1

5.25

HH

RLL 2

AUTO

ST2383N

SCSI

332

5.25

HH

RLL

AUTO

ST2383NM

SCSI

332

5.25

HH

RLL

AUTO

ST238R

ST-506/ 412

32.74

5.25

HH

RLL 2

615

ST2502N

SCSI

442

5.25

HH

RLL

ST2502NM

SCSI

442

5.25

HH

RLL

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

100

5

1747

54

100

4

615

26

N/ A

100

7

1747

54

N/ A

N/ A

100

7

1747

54

N/ A

N/ A

100

7

1261

0

N/ A

N/ A

100

7

1261

0

100

4

615

26

AUTO

N/ A

N/ A

100

7

1755

0

AUTO

N/ A

N/ A

100

7

1755

0

ST2502NV

SCSI

442

5.25

HH

RLL

AUTO

N/ A

N/ A

100

7

1755

0

ST250N

SCSI

42.34

5.25

HH

RLL 2

AUTO

N/ A

N/ A

100

4

667

31

ST250R

ST-506/ 412

42.34

5.25

HH

RLL 2

670

100

4

667

31

ST251

ST-506/ 412

42.82

5.25

HH

M FM

AUTO

100

6

820

17

ST251-1

ST-506/ 412

42.82

5.25

HH

M FM

AUTO

821

821

100

6

820

17

ST251N

SCSI

43.66

5.25

HH

RLL 2

AUTO

N/ A

N/ A

70

4

820

26

AUTO

N/ A

N/ A

ST251N-1

SCSI

43.86

5.25

HH

RLL 2

ST251R

ST-506/ 412

43.66

5.25

HH

RLL 2

ST252

ST-506/ 412

42.82

5.25

HH

M FM

AUTO

ST253

ST-506/ 412

43.04

5.25

HH

M FM

AUTO

ST274A

IDE(AT)

63.09

5.25

HH

RLL 2

AUTO

N/ A

N/ A

ST277N

SCSI

65.49

5.25

HH

RLL 2

AUTO

N/ A

N/ A

N/ A

N/ A

70

4

630

34

100

4

820

26

100

6

820

17

40

5

989

17

40

5

948

26

70

6

820

26

ST277N-1

SCSI

65.59

5.25

HH

RLL 2

AUTO

70

6

628

34

ST277R

ST-506/ 412

65.49

5.25

HH

RLL 2

AUTO

70

6

820

26

ST277R-1

ST-506/ 412

65.49

5.25

HH

RLL 2

AUTO

70

6

820

26

ST278R

ST-506/ 412

65.49

5.25

HH

RLL 2

AUTO

70

6

820

26

ST279R

ST-506/ 412

65.82

5.25

HH

RLL 2

AUTO

40

5

989

26

ST280A

IDE(AT)

71.33

5.25

HH

RLL 2

AUTO

N/ A

N/ A

40

5

1032

27

ST296N

SCSI

85.64

5.25

HH

RLL 2

AUTO

N/ A

N/ A

70

6

820

34

ST3025A

IDE(AT)

21.51

3.50

3H

RLL 2

AUTO

N/ A

N/ A

50

1

1616

26 26

ST3025N

SCSI-2

21.51

3.50

3H

RLL 2

AUTO

N/ A

N/ A

50

1

1616

ST3051A

IDE(AT)

43.1

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

0

0

0

ST3057N

SCSI-2

49.09

3.50

3H

RLL 2

AUTO

N/ A

N/ A

50

3

940

34

ST3096A

IDE(AT)

89.12

3.50

3H

RLL 2

AUTO

N/ A

N/ A

50

10

1024

17

ST3096N

SCSI-2

89.12

3.50

3H

RLL 2

AUTO

N/ A

N/ A

50

10

1024

17

ST31012A

IDE(AT)

1012

3.50

3H

AUTO

N/ A

N/ A

0

0

0

ST31051N

SCSI-2 F

1050

3.50

3H

RLL

AUTO

N/ A

N/ A

800

4

4569

0

ST31051W

SCSI-2 FW

1050

3.50

3H

RLL

AUTO

N/ A

N/ A

800

4

4569

0

ST31051WC

SCSI SCA

1050

3.50

4H

RLL

AUTO

N/ A

N/ A

800

4

4569

0

10

873

54

14

873

54

5

948

26

10

516

27

2

808

26

6

820

17

10

1024

17

16

2098

63

1387

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT

CODE LZ

WP

RW C

M TBF

PHDS

PCYL

PSPT LHDS LCYL LSPT

ST31055N

U-SCSI

1060

3.50

3H

RLL

AUTO

N/ A

N/ A

800

4

4176

0

ST31055W

U-SCSI

1060

3.50

3H

RLL

AUTO

N/ A

N/ A

800

4

4176

123

ST31055WC

U-SCSI

1060

3.50

3H

RLL

AUTO

N/ A

N/ A

800

4

4176

0

ST31080N

SCSI-2 F

0

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

0

0

0

ST31081A

IDE(AT)

1080

3.50

3H

RLL 1

2097

N/ A

N/ A

300

4

3924

0

ST31200N

SCSI-2

0

3.50

3H

RLL 1

AUTO

N/ A

N/ A

200

9

2700

0

ST31200NC

SCSI SCA

1052

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

9

2700

84

ST31200ND

SCSI-2

1052.4 3.50

3H

RLL 1

AUTO

N/ A

N/ A

200

9

2700

0

ST31200W

SCSI-2 FW

1052

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

9

2700

84

ST31200WC

SCSI-2 FW

1052

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

9

2700

84

ST31200WD

SCSI-2 FW

1052

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

9

2700

84

ST3120A

IDE(AT)

106.9

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

0

0

0

16

2097

63

12

1024

17

ST31220A

IDE(AT)

1083.2 3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

6

0

0

16

2099

63

ST31220A (VER. 2)

IDE(AT)

1088

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

6

0

0

16

2099

63

ST31230DC

SCSI-2 WD

1060

3.50

3H

UNIDEN AUTO

N/ A

N/ A

800

5

3992

0

ST31230N

SCSI-2 F

1060

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3992

103

ST31230NC

SCSI SCA

1060

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3992

103

5

3992

103

ST31230ND

SCSI-2 D

1060

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3992

103

ST31230W

SCSI-2 W

1060

3.50

3H

RLL

AUTO

N/ A

N/ A

800

5

3992

0

ST31230WC

SCSI-2 FW

1060

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3992

0

ST31230WD

SCSI-2 FW

1060

3.50

3H

RLL

AUTO

N/ A

N/ A

800

5

3992

0

ST31231N

SCSI-2 F

1060

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3992

103

ST3123A

IDE(AT)

106.6

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

0

0

0

12

1024

17

ST31250DC

SCSI SCA

1020.9 3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3711

0

ST31250N

SCSI-2 F

1020.9 3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3711

0

ST31250ND

SCSI-2 F

1020.9 3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3711

0

ST31250W

SCSI-2 F

1020.9 3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3711

0

ST31250WC

SCSI SCA

1020.9 3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3711

0

ST31250WD

SCSI-2 F

1020.9 3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

5

3711

0

ST31270A

IDE(AT)

1282.8 3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

16

2485

63

ST31274A

IDE(AT)

1278

3.50

3H

RLL 1

2480

N/ A

N/ A

300

6

2479

0

16

2479

63

ST31275A

IDE(AT)

1278

3.50

3H

RLL 1

2479

N/ A

N/ A

250

0

0

0

16

2479

63

ST31276A

IDE(AT)

1275

3.50

AUTO

N/ A

N/ A

300

0

0

0

16

2482

63

ST3144A

IDE(AT)

130.69 3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

3

0

0

15

1001

17

ST3145A

IDE(AT)

130.2

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

2

0

0

15

1001

17

ST31621A

IDE(AT)

1620

3.50

3H

3146

N/ A

N/ A

300

6

3924

0

16

3146

63

ST31640A

IDE(AT)

1625.7 3.50

3H

500

6

4834

0

16

3150

63

ST31720A

IDE(AT)

1705

0

0

0

16

3305

68

3.50

RLL 1

AUTO

N/ A

N/ A

AUTO

N/ A

N/ A

(continues)

1388

Appendix D—Technical Reference

Table D.14

SEAGATE TECHNOLOGY, INC. Cont inued

M ODEL

INT

CAP

FF

HGT CODE

LZ

WP

RW C

M TBF

PHDS PCYL

PSPT LHDS LCYL LSPT

ST31722A

IDE(AT)

1722

3.50

3H

AUTO

N/ A

N/ A

ST31930N

SCSI-2

1700

3.50

3H

RLL

AUTO

N/ A

N/ A

0

0

0

0

0

0

0

ST31930ND

SCSI-2

1700

3.50

3H

RLL

AUTO

N/ A

N/ A

0

0

0

0

ST3195A

IDE(AT)

170.77

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

4

0

0

ST32105N

SCSI-2 F

2147

3.50

3H

UNIDEN

N/ A

N/ A

AUTO

999

10

3892

0

ST32105W

SCSI-2 FW

2147

3.50

3H

UNIDEN

N/ A

N/ A

AUTO

999

10

3892

0

16

3303

63

10

981

34

ST32107N

SCSI-2 FW

2110

3.50

3H

RLL 1

AUTO

N/ A

N/ A

999

10

3924

91

ST32107W

SCSI-2 FW

2110

3.50

3H

RLL 1

AUTO

N/ A

N/ A

999

10

3924

91

ST32107WC

SCSI-2 FW

2110

3.50

3H

RLL 1

AUTO

N/ A

N/ A

999

10

3924

91

ST32122A

IDE(AT)

2122

3.50

3H

AUTO

N/ A

N/ A

0

0

0

16

4092

63

ST32140A

IDE(AT)

2113.4

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

8

4726

0

16

4095

63

ST32151N

SCSI-2 F

2147

3.50

3H

RLL

AUTO

N/ A

N/ A

800

8

4569

0

ST32151W

SCSI-2 FW

2147

3.50

3H

RLL

AUTO

N/ A

N/ A

800

8

4569

0

ST32151WC

SCSI SCA

2147

3.50

4H

RLL

AUTO

N/ A

N/ A

800

8

4569

0

ST32155N

U-SCSI

2148

3.50

3H

RLL

AUTO

N/ A

N/ A

800

8

4176

0

ST32155W

U-SCSI

2148

3.50

3H

RLL

AUTO

N/ A

N/ A

800

8

4176

125

ST32155WC

SCSI-2 W

2148

3.50

3H

RLL

AUTO

N/ A

N/ A

800

8

4176

0

ST32161A

IDE(AT)

2147

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

8

4474

0

16

4095

63

ST32171DC

U-SCSI D

2150

3.50

3H

RLL

AUTO

N/ A

N/ A

1000

5

5167

0

ST32171N

U-SCSI

2150

3.50

3H

RLL

AUTO

N/ A

N/ A

1000

5

5167

0

ST32171ND

U-SCSI D

2150

3.50

3H

RLL

AUTO

N/ A

N/ A

1000

5

5167

0

ST32171W

U-SCSI

2150

3.50

3H

RLL

AUTO

N/ A

N/ A

1000

5

5167

0

ST32171WC

U-SCSI W

2150

3.50

3H

RLL

AUTO

N/ A

N/ A

1000

5

5167

0

ST32171WD

U-SCSI

2150

3.50

3H

RLL

AUTO

N/ A

N/ A

1000

5

5167

0

ST32430DC

SCSI SCA

2140

3.50

3H

UNIDEN

AUTO

N/ A

N/ A

800

9

3992

0

ST32430N

SCSI-2 F

2140

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

9

3992

116

ST32430NC

SCSI SCA

2140

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

9

3992

116

ST32430ND

SCSI-2 D

2140

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

9

3992

116

ST32430W

SCSI-2 FW

2140

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

9

3892

0

ST32430WC

SCSI-2 W

2140

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

9

3992

116

ST32430WD

SCSI-2 FW

2140

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

9

3992

0

ST3243A

IDE(AT)

213.9

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

4

0

0

12

1024

34

12

1024

34

ST3250A

IDE(AT)

213.9

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

2

0

0

ST32550DC

SCSI SCA

2147.8

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

11

3510

0

ST32550N

SCSI-2 F

2147.8

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

11

3510

0

ST32550ND

SCSI-2 F

2147.8

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

11

3510

0

ST32550W

SCSI-2 F

2147.8

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

11

3510

0

ST32550WC

SCSI SCA

2147.8

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

11

3510

0

1389

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT CODE

LZ

WP

RW C

M TBF

PHDS PCYL

PSPT LHDS LCYL LSPT

ST32550WD

SCSI-2 F

2147.8

3.50

3H

RLL 1

AUTO

N/ A

N/ A

800

11

3510

0

ST325A\ X (12-PIN VER.)

IDE(XT/ AT)

21.41

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

2

697

30

2

697

30

ST325A\ X (18-PIN VER.)

IDE(XT/ AT)

21.41

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

2

697

30

2

697

30

ST325N

SCSI

21.41

3.50

3H

RLL 2

AUTO

N/ A

N/ A

50

2

697

30

ST3270A

IDE(AT)

270.9

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

4

0

0

16

525

63

ST3283A

IDE(AT)

245.36

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

5

1691

0

14

978

35

ST3283N PCB 260035

SCSI

245.36

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

5

1691

0

ST3285N

SCSI-2 F

248.62

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

3

1689

0

ST3290A

IDE(AT)

261.38

3.50

3H

RLL 1

AUTO

N/ A

N/ A

150

4

1691

0

15

1001

34

ST3291A

IDE(AT)

272.74

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

14

761

50

ST3295A

IDE(AT)

272.7

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

2

0

0

14

761

50

ST33232A

IDE(AT)

3232

3.50

3H

AUTO

N/ A

N/ A

0

0

0

16

6253

63

ST3385A

IDE(AT)

340

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

5

1691

0

14

768

62

ST3390A

IDE(AT)

341.3

3.50

3H

RLL 2

AUTO

N/ A

N/ A

250

3

2676

0

14

768

62

ST3390N

SCSI-2

344.3

3.50

3H

RLL 2

AUTO

N/ A

N/ A

250

3

2676

0

ST3391A

IDE(AT)

341.31

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

14

768

62

ST3423A

IDE(AT)

426

3.50

3H

RLL 1

863

N/ A

N/ A

300

2

862

0

16

826

63

RLL 1

250

2

0

0

16

826

63

0

0

0

15

8894

63

16

1016

63

ST3425A

IDE(AT)

425

3.50

3H

ST34342A

IDE(AT)

4342

3.50

3H

AUTO

N/ A

N/ A

AUTO

N/ A

N/ A

ST34371DC

U-SCSI D

4350

3.50

3H

RLL

AUTO

N/ A

N/ A

1000

10

5167

0

ST34371N

U-SCSI

4350

3.50

ST34371ND

U-SCSI D

4350

3.50

3H

RLL

AUTO

N/ A

N/ A

1000

10

5167

0

3H

RLL

AUTO

N/ A

N/ A

1000

10

5167

ST34371W

U-SCSI

4350

0

3.50

3H

RLL

AUTO

N/ A

N/ A

1000

10

5167

0

ST34371WC

U-SCSI W

ST34371WD

U-SCSI

4350

3.50

3H

RLL

AUTO

N/ A

N/ A

1000

10

5167

0

4350

3.50

3H

RLL

AUTO

N/ A

N/ A

1000

10

5167

ST34501DC

U-SCSI D

0

4550

3.50

3H

UNIDEN

AUTO

N/ A

N/ A

8

6526

0

ST34501N

U-SCSI

4550

3.50

3H

UNIDEN

AUTO

N/ A

N/ A

6

0

0

ST34501W

U-SCSI W

4550

3.50

3H

UNIDEN

AUTO

N/ A

N/ A

300

8

6526

0

ST34501WC

U-SCSI W

4550

3.50

3H

UNIDEN

AUTO

N/ A

N/ A

8

6526

0

ST34501WD

U-SCSI WD

4550

3.50

3H

UNIDEN

AUTO

N/ A

N/ A

8

6526

0

ST3491A

IDE(AT)

428.1

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

15

899

62

ST3500A

IDE(AT)

426.16

3.50

3H

RLL 1

AUTO

N/ A

N/ A

200

7

1874

0

15

895

62

ST3500N

SCSI-2

426

3.50

3H

RLL 1

AUTO

N/ A

N/ A

200

7

1872

0

ST351A\ X (12-PIN VER.)

IDE(XT/ AT)

42.82

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

6

820

17

6

820

17

(continues)

1390

Appendix D—Technical Reference

Table D.14 M ODEL

SEAGATE TECHNOLOGY, INC. Cont inued INT

CAP

FF

HGT CODE

LZ

WP

RW C

M TBF

PHDS PCYL

PSPT LHDS LCYL LSPT

ST351A\ X (18-PIN VER.)

IDE(XT/ AT)

42.82

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

6

820

17

ST352

IDE(XT/ AT)

42.82

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

6

820

17

6

820

17

ST3541A

IDE(AT)

540

3.50

3H

RLL 1

1045

N/ A

N/ A

300

2

3924

0

16

1048

63

ST3543A

IDE(AT)

540

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

4

0

0

16

1050

63

ST3550A

IDE(AT)

452.41

3.50

3H

RLL 2

AUTO

N/ A

N/ A

150

5

1691

0

14

1018

62

ST3550N

SCSI-2

456.48

3.50

3H

RLL 1

AUTO

N/ A

N/ A

200

5

2128

0

ST3600A (VER. A) IDE(AT)

528.48

3.50

3H

RLL 1

AUTO

N/ A

N/ A

200

7

1874

0

16

1024

63

ST3600A (VER. B) IDE(AT)

528.48

3.50

3H

RLL 1

AUTO

N/ A

N/ A

200

7

1874

0

16

1024

63

ST3600N

SCSI-2

525

3.50

3H

RLL 1

AUTO

N/ A

N/ A

200

7

1872

0

ST3600ND

SCSI-2 D

525

3.50

3H

RLL 1

AUTO

N/ A

N/ A

200

7

1872

0

ST3610N

SCSI-2

535

3.50

3H

RLL 1

AUTO

N/ A

N/ A

200

7

1872

0

ST3610NC

SCSI SCA

570

3.50

3H

RLL 1

AUTO

N/ A

N/ A

0

7

1872

0

ST3610ND

SCSI-2 D

535

3.50

3H

RLL 1

AUTO

N/ A

N/ A

200

7

1872

0

ST3620N

SCSI-2 F

545.9

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

5

2700

78

ST3620NC

SCSI SCA

545.9

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

5

2700

78

ST3620ND

SCSI-2 D

545.9

3.50

3H

RLL 1

AUTO

N/ A

N/ A

500

5

2700

78

ST3620W

SCSI-2 W

545.9

3.50

3H

RLL 1

AUTO

NA

N/ A

400

0

0

0

ST3630A

IDE(AT)

631.1

3.50

3H

ST3636A

IDE(AT)

635

3.50

ST36450A

IDE(AT)

6400

3.50

3H

ST36451A

IDE(AT)

6400

3.50

3H

ST3655A

IDE(AT)

528.48

3.50

3H

RLL 2

ST3655N

SCSI-2

545.48

3.50

3H

ST3660A

IDE(AT)

545

3.50

ST3780A

IDE(AT)

722.02

3.50

ST3852A

IDE(AT)

852

3.50

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

16

1223

63

UNIDEN

AUTO

N/ A

N/ A

300

0

0

0

16

1241

63

AUTO

N/ A

N/ A

0

0

0

15

13328 63

AUTO

N/ A

N/ A

0

0

0

15

13328 63

AUTO

N/ A

N/ A

200

5

0

0

16

1024

63

RLL 1

AUTO

N/ A

N/ A

200

5

2676

79

3H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

16

1057

63

3H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

16

1399

63

AUTO

N/ A

N/ A

0

0

0

16

1652

68

16

1652

63

ST3853A

IDE(AT)

850

3.50

3H

RLL 1

N/ A

N/ A

N/ A

250

4

3640

0

ST4026

ST-506/ 412

21.41

5.25

FH

M FM

AUTO

307

616

15

4

615

17

ST4038

ST-506/ 412

31.9

5.25

FH

M FM

AUTO

734

734

25

5

733

17

ST4038M

ST-506/ 412

31.9

5.25

FH

M FM

AUTO

734

734

25

5

733

17

ST4051

ST-506/ 412

42.51

5.25

FH

M FM

AUTO

978

978

40

5

977

17

ST4053

ST-506/ 412

44.56

5.25

FH

M FM

AUTO

1,024

1,024

40

5

1024

17

ST406

ST-506/ 412

5.32

5.25

FH

M FM

319

128

307

11

2

306

17

ST4077N

SCSI

68.15

5.25

FH

RLL 2

AUTO

N/ A

N/ A

0

5

1024

26

ST4077R

ST-506/ 412

68.15

5.25

FH

RLL 2

1,025

1,025

0

5

1024

26

ST4085

ST-506/ 412

71.3

5.25

FH

M FM

AUTO

1,025

1,025

40

8

1024

17

ST4086

ST-506/ 412

72.46

5.25

FH

M FM

AUTO

926

926

40

9

925

17

Hard Disk Drives

1391

M ODEL

INT

CAP

FF

HGT CODE

LZ

WP

RW C

M TBF

PHDS PCYL

PSPT LHDS LCYL LSPT

ST4096

ST-506/ 412

80.21

5.25

FH

AUTO

1,025

1,025

40

9

1024

17

M FM

ST4096N

SCSI

80.21

5.25

FH

RLL

AUTO

N/ A

N/ A

40

9

1024

17

ST4097

ST-506/ 412

80.21

5.25

FH

M FM

AUTO

1,024

1,024

40

9

1024

17

ST410800N

SCSI-2 W

9090

5.25

FH

RLL 1

AUTO

500

27

4925

0

ST410800ND

SCSI-2

9080

5.25

FH

RLL 1

AUTO

N/ A

N/ A

500

27

4925

0

ST410800W

SCSI-2 FW

9090

5.25

FH

RLL 1

AUTO

N/ A

N/ A

500

27

4925

0

ST410800WD

SCSI-2 FW

9090

5.25

FH

RLL 1

AUTO

N/ A

N/ A

500

27

4925

0

ST412

ST-506/ 412

10.65

5.25

FH

M FM

319

128

307

11

4

306

17

ST41200N

SCSI

1037

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1931

0

ST41200ND

SCSI

1037

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1931

0

ST41200NM

SCSI

1037

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1931

0

ST41200NV

SCSI

1037

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1931

0

ST4135R

ST-506/ 412

115.01

5.25

FH

RLL 2

AUTO

128

1,025

40

9

960

26

ST4144N

SCSI

122.68

5.25

FH

RLL 2

1023

N/ A

N/ A

0

9

1024

26

ST4144R

ST-506/ 412

122.68

5.25

FH

RLL 2

AUTO

1,025

1,025

40

9

1024

26

ST41520N

SCSI-2

370

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

17

2101

0

ST41520ND

SCSI-2 D

1370

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

17

2101

0

ST41600N

SCSI-2

1370

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

17

2101

0

ST41600ND

SCSI-2 D

1370

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

17

2101

0

ST41601N

SCSI-2

1370

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

17

2101

0

ST41601ND

SCSI-2

1370

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

17

2101

0

ST41650N

SCSI-2

1415

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

2107

0

ST41650ND

SCSI-2 D

1415

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

2107

0

ST41651N

SCSI-2

1415

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

2107

0

ST41651ND

SCSI-2 D

1415

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

2107

0

ST4182E

ESDI-10M HZ

151.81

5.25

FH

RLL 2

AUTO

N/ A

N/ A

100

9

969

34

ST4182N (2X7 PIN VER.)

SCSI

160.74

5.25

FH

RLL 2

AUTO

N/ A

N/ A

100

9

969

36

ST4182N (3X5 PIN VER.)

SCSI

160.74

5.25

FH

RLL 2

AUTO

N/ A

N/ A

100

9

969

36

ST4182NM (2X7 PIN VER.)

SCSI

160.74

5.25

FH

RLL 2

AUTO

N/ A

N/ A

100

9

969

36

ST419

ST-506/ 412

15.98

5.25

FH

M FM

128

307

11

6

306

17

ST4192E

ESDI-10M HZ

169.13

5.25

FH

RLL 2

AUTO

N/ A

N/ A

20

8

1147

36

ST4192N

SCSI

169.13

5.25

FH

RLL 2

AUTO

N/ A

N/ A

20

8

1147

36

ST42000N

SCSI-2

1792

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

16

2627

0

ST42000ND

SCSI-2 D

1792

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

16

2627

0

ST42100N

SCSI-2

1900

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

16

2627

0

ST42101N

SCSI-2

1900

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

16

2627

0

(continues)

1392

Appendix D—Technical Reference

Table D.14 M ODEL

SEAGATE TECHNOLOGY, INC. Cont inued INT

CAP

FF

HGT CODE

LZ

WP

RW C

M TBF

PHDS PCYL

PSPT LHDS LCYL LSPT

ST423451N

U-SCSI

23400

5.25

FH

UNIDEN

AUTO

N/ A

N/ A

28

6880

0

ST423451W

U-SCSI W

23400

5.25

FH

UNIDEN

AUTO

N/ A

N/ A

28

6880

0

ST423451WD

U-SCSI WD

23400

5.25

FH

UNIDEN

AUTO

N/ A

N/ A

28

6880

0

ST42400N

SCSI-2

2129

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

19

2627

0

ST42400ND

SCSI-2

2129

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

19

2627

0

ST425

ST-506/ 412

21.3

5.25

FH

M FM

128

307

0

8

306

17

ST43400N

SCSI-2

2912

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

21

2738

0

ST43400ND

SCSI-2 D

2912

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

21

2738

0

ST43401N

SCSI-2 FW

2912

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

21

2738

0

ST43401ND

SCSI-2 FW

2912

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

21

2738

0

ST43402ND

SCSI-2 FWD

2912

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

21

2738

0

ST4350N

SCSI

307

5.25

FH

RLL

AUTO

N/ A

N/ A

100

9

1412

0

ST4350NM

SCSI

307

5.25

FH

RLL

AUTO

N/ A

N/ A

100

9

1412

0

ST4376N

SCSI

330

5.25

FH

RLL

AUTO

N/ A

N/ A

100

9

1541

0

ST4376NM

SCSI

330

5.25

FH

RLL

AUTO

N/ A

N/ A

100

9

1541

0

ST4376NV

SCSI

330

5.25

FH

RLL

AUTO

N/ A

N/ A

100

9

1541

0

ST4383E

ESDI-10M HZ

319.54

5.25

FH

RLL 2

AUTO

N/ A

N/ A

100

13

1412

34

ST4384E

ESDI-10M HZ

319.61

5.25

FH

RLL 2

AUTO

N/ A

N/ A

100

15

1224

34

ST4385N

SCSI

337

5.25

FH

RLL

AUTO

N/ A

N/ A

100

15

791

0

ST4385NM

SCSI

337

5.25

FH

RLL

AUTO

N/ A

N/ A

100

15

791

0

ST4385NV

SCSI

337

5.25

FH

RLL

AUTO

N/ A

N/ A

100

15

791

0

ST4442E

ESDI-10M HZ

368.7

5.25

FH

RLL 2

AUTO

N/ A

N/ A

100

15

1412

34

ST4702N

SCSI

613

5.25

FH

RLL

AUTO

N/ A

N/ A

100

15

1546

0

ST4702NM

SCSI

613

5.25

FH

RLL

AUTO

N/ A

N/ A

100

15

1546

0

ST4766E

ST-506/ 412

664.28

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1632

53

ST4766N

SCSI

676.82

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

15

1632

54

ST4766NM

SCSI

676.82

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

15

1632

54

ST4766NV

SCSI

676.82

5.25

FH

RLL 2

AUTO

N/ A

N/ A

150

15

1632

54

ST4767ES

ESDI-15M HZ

676.89

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1399

63

ST4767N

SCSI-2

666.5

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1356

64

ST4767ND

SCSI-2

666.5

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1356

64

ST4767NM

SCSI-2

666.5

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1356

64

ST4767NV

SCSI-2

666.5

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1356

64

ST4769ES

ESDI-15M HZ

631.72

5.25

FH

RLL 1

AUTO

N/ A

N/ A

150

15

1552

53

ST506

ST-506/ 412

5.32

5.25

FH

M FM

157

128

128

11

4

153

17

ST51080A

IDE(AT)

1083.8

3.50

3H

RLL 1

AUTO

N/ A

N/ A

300

4

4834

0

ST51080N

SCSI-2 F

1080.23 3.50

4H

RLL 1

AUTO

N/ A

N/ A

300

4

4826

0

ST51270A

IDE(AT)

1282.4

4H

RLL 1

AUTO

N/ A

AUTO

300

4

5414

0

3.50

16

2100

63

16

2485

63

1393

Hard Disk Drives

M ODEL

INT

CAP

FF

ST52160A

IDE(AT)

810

3.50

ST52520A

IDE(AT)

810

3.50

ST5540A

IDE(AT)

540.1

3.50

ST5660A

IDE(AT)

545.51

ST5660N

SCSI-2

545.29

ST5660NC

SCSI SCA

ST5850A (VER. 1) ST5850A (VER. 2) ST5851A

HGT CODE

LZ

WP

RW C

UNIDEN

AUTO

N/ A

UNIDEN

AUTO

N/ A

3H

RLL 1

AUTO

N/ A

N/ A

3.50

3H

RLL 1

AUTO

N/ A

3.50

3H

RLL 1

AUTO

N/ A

545.29

3.50

3H

RLL 1

AUTO

IDE(AT)

854.7

3.50

3H

RLL 1

IDE(AT)

854.7

3.50

4H

RLL 1

IDE(AT)

854.7

3.50

4H

PHDS PCYL

PSPT LHDS LCYL LSPT

N/ A

8

0

0

16

4095

63

N/ A

8

0

0

16

4970

63

300

2

4834

0

16

1050

63

N/ A

300

4

3420

0

16

1057

63

N/ A

0

4

3420

77

N/ A

N/ A

300

4

3002

0

AUTO

N/ A

N/ A

500

4

0

0

32

828

63

AUTO

N/ A

N/ A

500

4

0

0

32

828

63

RLL 1

AUTO

N/ A

AUTO

300

4

4834

0

16

1656

63

AUTO

ST7050P

PCM

42

1.80

4H

RLL 1

ST706

ST-506/ 412

5.32

5.25

FH

M FM

ST81236N

SCSI

1056

8.00

FH

RLL 2

ST81236N VER. 1

SCSI

1000

8.00

FH

ST81236N VER. 2

SCSI

1000

8.00

FH

ST81236N VER. 3

SCSI

1000

8.00

ST81236ND VER. 1

SCSI D

1000

ST81236ND VER. 2

SCSI D

ST81236ND VER. 3

M TBF

N/ A

N/ A

250

2

0

0

128

307

0

2

306

17

N/ A

N/ A

150

15

1635

0

RLL 2

0

15

1371

0

1381

RLL 2

0

15

1371

0

1381

FH

RLL 2

0

15

1371

0

1381

8.00

FH

RLL 2

0

15

1371

0

1381

1000

8.00

FH

RLL 2

0

15

1371

0

1381

SCSI D

1000

8.00

FH

RLL 2

0

15

1371

0

1381

ST82500N

SCSI

2140

8.00

FH

RLL 2

150

19

2611

0

ST8741N VER. 1

SCSI

608

8.00

FH

RLL 2

0

15

1371

0

1381

ST8741N VER. 2

SCSI

608

8.00

FH

RLL 2

0

15

1371

0

1381

AUTO

AUTO

N/ A

N/ A

ST8741N VER. 3

SCSI

608

8.00

FH

RLL 2

0

15

1371

0

1381

ST8741ND VER. 1

SCSI D

608

8.00

FH

RLL 2

0

15

1371

0

1381

ST8741ND VER. 2

SCSI D

608

8.00

FH

RLL 2

0

15

1371

0

1381

ST8741ND VER. 3

SCSI D

608

8.00

FH

RLL 2

0

15

1371

0

1381

ST8851N

SCSI

727

8.00

FH

RLL 2

100

15

1381

0

ST8851N VER. 1

SCSI

693

8.00

FH

RLL 2

0

15

1371

0

1381

ST8851N VER. 2

SCSI

693

8.00

FH

RLL 2

0

15

1371

0

1381

ST8851N VER. 3

SCSI

693

8.00

FH

RLL 2

0

15

1371

0

1381

ST8851ND VER. 1

SCSI D

693

8.00

FH

RLL 2

0

15

1371

0

1381

ST8851ND VER. 2

SCSI D

693

8.00

FH

RLL 2

0

15

1371

0

1381

ST8851ND VER. 3

SCSI D

693

8.00

FH

RLL 2

0

15

1371

0

ST9051A

IDE(44PIN)

42.86

2.50

4H

RLL 2

150

4

654

32

ST9052A

IDE(44PIN)

42.6

2.50

4H

RLL 2

AUTO

N/ A

N/ A

150

0

0

0

5

980

17

ST9077A

IDE(44PIN)

64.05

2.50

4H

RLL 2

AUTO

N/ A

N/ A

150

4

802

39

11

669

17

ST9080A

IDE(44PIN)

64

2.50

4H

RLL 2

AUTO

N/ A

N/ A

150

0

0

0

4

823

38

AUTO

AUTO

N/ A

N/ A

N/ A

N/ A

1381 6

820

17

(continues)

1394

Appendix D—Technical Reference

Table D.14

SEAGATE TECHNOLOGY, INC. Cont inued

M ODEL

INT

CAP

FF

HGT CODE

LZ

WP

RW C

M TBF

PHDS PCYL

PSPT LHDS LCYL LSPT

ST9096A

IDE(44PIN)

85.3

2.50

4H

RLL 2

AUTO

N/ A

N/ A

50

0

0

0

10

980

17

ST9100A

IDE(44PIN)

85.8

2.50

5H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

14

748

16

ST9100AG

IDE(44PIN)

85.3

2.50

3H

RLL 1

AUTO

N/ A

N/ A

150

0

0

0

14

748

16

ST9140AG

IDE(44PIN)

127.94

2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

15

980

17

ST9144A

IDE(44PIN)

130.69

2.50

4H

RLL 2

AUTO

N/ A

N/ A

150

3

0

0

15

980

17

ST9145A

IDE(44PIN)

127.94

2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

4

1463

0

15

980

17

ST9145AG

IDE(44PIN)

127.94

2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

4

1463

0

15

980

17

ST9150AG

IDE(44PIN)

131.07

2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

2

0

0

13

419

47

ST9190AG

IDE(44PIN)

171.63

2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

16

873

24

ST9235A

IDE(AT)

209.7

3.50

4H

RLL 2

AUTO

N/ A

N/ A

150

0

0

0

13

985

32

ST9235AG

IDE(44PIN)

209.7

2.50

4H

RLL 2

AUTO

N/ A

N/ A

150

0

0

0

13

985

32

ST9235N

SCSI

209

2.50

4H

RLL 2

AUTO

N/ A

N/ A

150

0

0

0

ST9240A

IDE(44PIN)

210.43

2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

8

988

52

ST9240AG

IDE(44PIN)

210.43

2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

8

988

52

ST9295AG

IDE(44PIN)

261

2.50

4H

RLL 2

AUTO

N/ A

N/ A

150

0

0

0

ST9295N

SCSI

250.6

2.50

4H

RLL 2

AUTO

N/ A

N/ A

150

0

0

0

ST9300AG

IDE(44PIN)

262.19

2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

15

569

60

ST9352A

IDE(AT)

350

2.50

FH

RLL 1

905

N/ A

N/ A

300

4

2225

0

12

905

63

ST9385AG

IDE(AT)

341.44

2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

6

0

0

14

934

51

ST9420A

IDE(44PIN)

420.8

2.50

5H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

16

988

52

ST9420AG

IDE(44PIN)

420.8

2.50

5H

RLL 1

AUTO

N/ A

N/ A

300

4

0

0

16

988

53

ST9422A

IDE(AT)

422

2.50

5H

RLL 1

818

N/ A

N/ A

300

4

2393

0

16

818

63

ST9550AG

IDE(AT)

455.29

2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

6

0

0

16

942

59

ST9655AG

IDE(44PIN)

524.35

2.50

4H

RLL 1

AUTO

N/ A

N/ A

300

6

0

0

16

1016

63

ST9816AG

IDE(44PIN)

810

2.50

5H

RLL 1

AUTO

N/ A

N/ A

300

8

0

0

16

1571

63

WP

RW C

M TBF

PHDS PCYL

80

Table D.15

TOSHIBA

M ODEL

INT

CAP

FF

HGT CODE

LZ

HDD 2214

IDE(44PIN)

86.03

2.50

4H

RLL 2

AUTO

N/ A

N/ A

HDD 2216

IDE(AT)

130.09

2.50

4H

RLL 2

934

N/ A

N/ A

HDD 2238

IDE(44PIN)

213

2.50

4H

RLL

AUTO

N/ A

N/ A

HDD 2324

IDE(AT)

86

2.50

3H

RLL

AUTO

N/ A

N/ A

HDD 2326

IDE(AT)

126

2.50

RLL

AUTO

N/ A

N/ A

HDD 2336

IDE(AT)

131

2.50

RLL

HDD 2339

IDE(AT)

262

2.50

HDD 2412

IDE(44PIN)

340

2.50

4H

HDD 2414

IDE(44PIN)

524

2.50

4H

PSPT LHDS LCYL LSPT

0

0

0

0

0

0

10

988

17

150

4

1560

150

2

1501

0

16

684

38

56

10

988

2

0

17

0

8

812

38

AUTO

N/ A

N/ A

2

0

0

16

842

38

AUTO

N/ A

N/ A

0

0

0

16

842

38

RLL 1

AUTO

N/ A

N/ A

150

6

1830

0

14

969

49

RLL 1

AUTO

N/ A

N/ A

150

8

1920

0

16

1016

63

1395

Hard Disk Drives

M ODEL

CAP

FF

HGT CODE

LZ

WP

RW C

M TBF

PHDS PCYL

PSPT LHDS LCYL LSPT

HDD 2416

INT

704

2.50

5H

RLL 1

1365

N/ A

N/ A

300

0

0

0

16

1365

63

HDD 2417

810

2.50

5H

RLL 1

1571

N/ A

N/ A

300

0

0

0

16

1571

63

HDD 2434

528

2.50

5H

RLL 1

1023

N/ A

N/ A

300

0

0

0

16

1023

63

16

682

63

16

1579

63

HDD 2512

IDE(44PIN)

352

2.50

5H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

HDD 2514

IDE(44PIN)

543

2.50

5H

RLL 1

AUTO

N/ A

N/ A

300

0

0

0

HDD 2517

IDE(44PIN)

810

2.50

4H

RLL 1

1579

N/ A

N/ A

300

0

0

0

1.35

2.50

5H

RLL 1

AUTO

N/ A

N/ A

300

10

2920

0

RLL

AUTO

N/ A

N/ A

300

10

3650

0

300

0

0

HDD 2612 HDD 2616

IDE(AT)

2.16

2.50

4H

HDD 2619

IDE(44PIN)

3300

2.50

3

0

16

6409

63

HDD 2632

IDE(AT)

1080

2.50

4H

AUTO

N/ A

N/ A

300

8

0

0

16

2633

63

HDD 2634

IDE(AT)

1080

2.50

4H

AUTO

N/ A

N/ A

300

10

0

0

16

3294

63

HDD 2710

IDE(AT)

1080

2.50

4H

AUTO

N/ A

N/ A

300

3

0

0

16

2100

63

HDD 2712

IDE(44PIN)

1350

2.50

3

300

0

0

0

16

2800

63

HDD 2714

IDE(44PIN)

1440

2.50

3

300

0

0

0

16

2800

63

HDD 2716

IDE(AT)

2160

2.50

4H

300

3

0

0

16

4200

63

AUTO

N/ A

N/ A

HDD 2731

IDE(AT)

1080

2.50

4H

AUTO

N/ A

N/ A

300

3

0

0

16

2100

63

M K-1002

IDE(AT)

1080

2.50

4H

AUTO

N/ A

N/ A

300

6

0

0

16

2100

63

M K-1034FC

IDE(AT)

107.42

3.50

3H

RLL 2

AUTO

N/ A

N/ A

40

4

1345

39

8

664

39

M K-1122FC

IDE(AT)

43.01

2.50

4H

RLL 2

AUTO

N/ A

N/ A

80

2

977

43

5

988

17

M K-1301M AV

IDE(AT)

1.35

2.50

5H

UNIDEN

AUTO

128

300

6

3650

0

M K-1302

IDE(AT)

1700

2.50

4H

N/ A

N/ A

300

4

0

0

16

2633

63

M K-134FA

ST-506/ 412

44.66

3.50

HH

M FM

512

N/ A

30

7

733

17

M K-134FA(R)

ST-506/ 412

68.3

3.50

HH

RLL 2

30

7

733

26

M K-1422FCV

IDE(AT)

86

2.50

3H

RLL

150

2

1501

56

10

988

17

AUTO

AUTO

N/ A

N/ A

M K-153FA

ESDI-10M HZ

74.36

5.25

FH

RLL 2

AUTO

N/ A

N/ A

30

5

830

35

M K-153FA-I

ESDI-10M HZ

74.36

5.25

FH

RLL 2

AUTO

N/ A

N/ A

30

5

830

35

M K-154FA

ESDI-10M HZ

104.11

5.25

FH

RLL 2

AUTO

N/ A

N/ A

30

7

830

35

M K-154FA-I

ESDI-10M HZ

104.11

5.25

FH

RLL 2

AUTO

N/ A

N/ A

30

7

830

35

M K-154FB

ESDI-10M HZ

104.11

5.25

FH

RLL 2

AUTO

N/ A

N/ A

30

7

830

35

M K-156FA

ESDI-10M HZ

148.73

5.25

FH

RLL 2

AUTO

N/ A

N/ A

30

10

830

35

M K-156FB

ESDI-10M HZ

148.73

5.25

FH

RLL 2

AUTO

N/ A

N/ A

30

10

830

35

M K-1824FCV

IDE(44PIN)

352

2.50

5H

RLL 1

682

N/ A

N/ A

300

0

0

0

16

682

63

M K-1924FCV

IDE(44PIN)

543

2.50

5H

RLL 1

1053

N/ A

N/ A

300

0

0

0

16

1053

63

M K-1926FCV

IDE(44PIN)

810

2.50

5H

RLL 1

1579

N/ A

N/ A

300

0

0

0

16

1579

63

M K-2024FC

IDE(AT)

86.03

2.50

4H

RLL 2

AUTO

N/ A

N/ A

80

4

977

43

10

988

17

M K-2124FC

IDE(AT)

130.09

2.50

4H

RLL 2

934

N/ A

N/ A

80

4

1155

55

16

934

17

N/ A

N/ A

4

1560

0

16

684

38

AUTO

N/ A

N/ A

150

4

1560

0

16

684

38

M K-2224FB

SCSI

213

2.50

4H

RLL 1

M K-2224FC

IDE(AT)

213

2.50

3H

RLL

(continues)

1396

Appendix D—Technical Reference

Table D.15 M ODEL

TOSHIBA Cont inued

INT

CAP

FF

HGT CODE

LZ

WP

RW C

M TBF

PHDS PCYL

PSPT LHDS LCYL LSPT

M K-2326FB

SCSI

340

2.50

4H

RLL 1

N/ A

N/ A

6

1830

0

14

969

49

M K-2326FC

IDE(44PIN)

340.34

2.50

4H

RLL 1

AUTO

N/ A

N/ A

150

6

1830

0

14

969

49

M K-232FB

SCSI

45.42

3.50

HH

RLL 2

AUTO

N/ A

N/ A

30

3

845

35

M K-232FBS

SCSI

45.42

3.50

HH

RLL 2

AUTO

N/ A

N/ A

30

3

845

35

M K-232FC

IDE(AT)

45.42

3.50

HH

RLL 2

AUTO

N/ A

N/ A

30

3

845

35

M K-232FCH

IDE(AT)

0

2.50

4H

RLL 1

AUTO

N/ A

N/ A

150

14

969

49

M K-233FB

SCSI

75.71

3.50

HH

RLL 2

AUTO

N/ A

N/ A

30

5

845

35

M K-234FB

SCSI

105.99

3.50

HH

RLL 2

AUTO

N/ A

N/ A

30

7

845

35

M K-234FBS

SCSI

105.99

3.50

HH

RLL 2

AUTO

N/ A

N/ A

30

7

845

35

AUTO

N/ A

N/ A

M K-234FC

IDE(AT)

110.44

3.50

HH

RLL 2

M K-234FCF

IDE(AT)

0

2.50

4H

RLL 1

M K-234FCH

IDE(AT)

107.37

3.50

HH

RLL 2

AUTO

N/ A

M K-234FCH-I

IDE(AT)

107.37

3.50

HH

RLL 2

AUTO

M K-2428FB

SCSI

524

2.50

4H

RLL 1

M K-2428FC

IDE(44PIN)

524.35

2.50

4H

RLL 1

M K-250FB

SCSI

219.34

5.25

FH

RLL 2

M K-2526FB

SCSI-2

528

2.50

5H

M K-2526FC

IDE(44PIN)

528

2.50

5H

RLL 1

1023

N/ A

N/ A

M K-2528FC

IDE(44PIN)

704

2.50

5H

RLL 1

1365

N/ A

M K-253FA

ESDI-15M HZ

162.8

5.25

FH

RLL 1

AUTO

N/ A

M K-254FA

ESDI-15M HZ

227.92

5.25

FH

RLL 1

AUTO

RLL 1

AUTO

M K-256FA

ESDI-15M HZ

325.61

5.25

FH

M K-2628FB

SCSI-2

811

2.50

5H

M K-2628FC

IDE(44PIN)

810

2.50

5H

M K-2720

IDE(AT)

1035

2.50

M K-355FA

ESDI-15M HZ

405.65

5.25

FH

M K-355FB

SCSI-2

405.65

5.25

M K-358FA

ESDI-15M HZ

676.09

5.25

M K-358FB

SCSI-2

676.09

M K-438FB ASSY. 0605

SCSI-2

M K-438FB ASSY. 0817 M K-438FB ASSY. 0834

30

7

856

36

7

845

35

150

0

0

0

14

969

49

N/ A

30

7

856

35

N/ A

N/ A

30

7

856

35

N/ A

N/ A

8

1920

0

16

1016

63

AUTO

N/ A

N/ A

150

8

1920

0

16

1016

63

AUTO

N/ A

N/ A

30

10

1224

35

6

2050

0

300

0

0

0

16

1023

63

N/ A

300

0

0

0

16

1365

63

N/ A

30

5

1223

52

N/ A

N/ A

30

7

1223

52

N/ A

N/ A

30

10

1223

52

8

2360

0 0

16

1571

63

RLL 1

1571

N/ A

N/ A

300

0

0

UNIDEN

AUTO

N/ A

N/ A

250

0

0

0

RLL 2

AUTO

N/ A

N/ A

30

9

1661

53

FH

RLL 2

AUTO

N/ A

N/ A

30

9

1661

53

FH

RLL 2

AUTO

N/ A

N/ A

30

9

1661

53

5.25

FH

RLL 2

AUTO

N/ A

N/ A

30

15

1661

53

877

3.50

HH

RLL 1

AUTO

N/ A

N/ A

200

15

1692

0

SCSI-2

900

3.50

HH

RLL 1

AUTO

N/ A

N/ A

200

11

1980

0

SCSI-2

877

5.25

FH

RLL 1

AUTO

N/ A

N/ A

200

11

1980

35

M K-537FB

SCSI-2

1064

3.50

HH

RLL 1

AUTO

N/ A

N/ A

200

13

1980

0

M K-538FB

SCSI-2

1228

3.50

HH

RLL 1

AUTO

N/ A

N/ A

200

15

1980

0

M K-53FA

ST-506/ 412

36.12

5.25

FH

M FM

830

512

20

5

830

17

M K-53FB

ST-506/ 412

36.12

5.25

FH

M FM

20

5

830

17

512

830

104

104

Hard Disk Drives

LZ

1397

M ODEL

INT

CAP

FF

HGT CODE

WP

RW C

M TBF

PHDS PCYL

PSPT LHDS LCYL LSPT

M K-53FB(M )

ST-506/ 412

36.12

5.25

FH

M FM

512

830

20

5

830

17

M K-53FB(R)

ST-506/ 412

36.12

5.25

FH

RLL

512

830

20

5

830

17

M K-53FB-I

ST-506/ 412

36.12

5.25

FH

M FM

512

830

20

5

830

17

M K-54FA(M )

ST-506/ 412

50.57

5.25

FH

M FM

830

512

20

7

830

17

M K-54FB(M )

ST-506/ 412

50.57

5.25

FH

M FM

830

512

830

20

7

830

17

830

512

830

20

7

830

17

831

831

20

10

830

17

M K-54FB-I

ST-506/ 412

50.57

5.25

FH

M FM

M K-56FA(M )

ST-506/ 412

72.24

5.25

FH

M FM

M K-56FA(R)

ST-506/ 412

110.48

5.25

FH

RLL 2

830

512

20

10

830

26

M K-56FB(M )

ST-506/ 412

72.24

5.25

FH

M FM

830

512

830

20

10

830

17

M K-56FB(R)

ST-506/ 412

110.48

5.25

FH

RLL 2

831

831

20

10

830

26

512

830

M K-56FB-I

ST-506/ 412

72.24

5.25

FH

M FM

M K-72PC

ST-506/ 412

72.24

5.25

FH

M FM

830

20

10

830

17

20

10

830

17

M K-72PCR

ST-506/ 412

110.48

5.25

FH

RLL 2

20

10

830

26

M KM -0351E

ST-506/ 412

36.12

5.25

FH

M FM

830

512

830

20

5

830

17

M KM -0351J

ST-506/ 412

36.12

5.25

FH

M FM

830

512

830

20

5

830

17

M KM -0352E

ST-506/ 412

50.57

5.25

FH

M FM

830

512

20

7

830

17

M KM -0352J

ST-506/ 412

50.57

5.25

FH

M FM

830

512

20

7

830

17

M KM -0353E

ST-506/ 412

72.24

5.25

FH

M FM

830

512

20

10

830

17

830

M KM -0353J

ST-506/ 412

72.24

5.25

FH

M FM

830

512

830

20

10

830

17

M KM -0363A

ESDI-10M HZ

74.36

5.25

FH

RLL 2

AUTO

N/ A

N/ A

30

5

830

35

M KM -0363J

ESDI-10M HZ

74.36

5.25

FH

RLL 2

AUTO

N/ A

N/ A

30

5

830

35

M KM -0364A

ESDI-10M HZ

104.11

5.25

FH

RLL 2

AUTO

N/ A

N/ A

30

7

830

35

M KM -0364J

ESDI-10M HZ

104.11

5.25

FH

RLL 2

AUTO

N/ A

N/ A

30

7

830

35

M KM -0381E

ST-506/ 412

36.12

5.25

FH

M FM

512

830

20

5

830

17

M KM -0381J

ST-506/ 412

36.12

5.25

FH

M FM

830

512

830

20

5

830

17

M KM -0382E

ST-506/ 412

50.57

5.25

FH

M FM

830

512

20

7

830

17

M KM -0382J

ST-506/ 412

50.57

5.25

FH

M FM

830

512

20

7

830

17

M KM -0383E

ST-506/ 412

72.24

5.25

FH

M FM

830

512

830

20

10

830

17

M KM -0383J

ST-506/ 412

72.24

5.25

FH

M FM

830

512

830

20

10

830

17

WP

RW C

M TBF

PHDS PCYL

PSPT LHDS LCYL LSPT

300

0

0

0

20

4

615

17

Table D.16

W ESTERN DIGITAL CORPORATION

M ODEL

INT

CAP

FF

HGT CODE

PHD1000

IDE(AT)

1083

3.50

5H

WD-262

ST-506/ 412

20

5.25

HH

WD-344R

ST-506/ 412

41.63

3.50

HH

RLL

WD-362

ST-506/ 412

20

3.50

HH

M FM

WD-382R

ST-506/ 412

20.81

3.50

HH

RLL 2

783

WD-383R

ST-506/ 412

32.74

3.50

HH

RLL 2

616

M FM

LZ

663 783

783

0

4

782

26

20

4

615

17

783

0

2

782

26

616

0

4

615

26

663

(continues)

1398

Appendix D—Technical Reference

Table D.16

W ESTERN DIGITAL CORPORATION Cont inued

M ODEL

INT

CAP

FF

HGT CODE

LZ

WP

RW C

M TBF

PHDS PCYL

PSPT LHDS LCYL LSPT

WD-384R

ST-506/ 412

41.63

3.50

HH

WD-544R

ST-506/ 412

41.63

3.50

HH

RLL 2

783

783

0

4

782

26

RLL 2

783

783

0

4

782

WD-562-5

ST-506/ 412

21.41

3.50

HH

M FM

26

40

4

615

17

WD-582R

ST-506/ 412

20.81

3.50

HH

RLL 2

783

WD-583R

ST-506/ 412

32.74

3.50

HH

RLL 2

616

783

0

2

782

26

616

0

4

615

WD-584R

ST-506/ 412

41.63

3.50

HH

RLL 2

26

783

783

0

4

782

26

WD-M I130-44

M CA

31.08

3.50

3H

RLL 2

WD-M I130-72

M CA

30.4

3.50

3H

RLL 2

AUTO

N/ A

N/ A

45

2

920

33

AUTO

N/ A

N/ A

45

2

928

WD-M I260-72

M CA

63.61

3.50

3H

32

RLL 2

AUTO

N/ A

N/ A

45

6

767

27

WD-M I4120-72

M CA

125.03

3.50

WD-TM 262R

ST-506/ 412

20.81

3.50

3H

RLL 2

AUTO

N/ A

N/ A

45

8

925

33

HH

RLL 2

783

783

0

2

782

WD-TM 364

ST-506/ 412

41.63

3.50

26

HH

RLL 2

783

783

0

4

782

26

WD93024-A

IDE(AT)

21.62

3.50

HH

RLL 2

862

N/ A

N/ A

40

2

782

27

WD93024-X

IDE(XT)

21.62

3.50

HH

RLL 2

862

N/ A

N/ A

50

2

782

27

WD93028-AD

IDE(AT)

21.62

3.50

HH

RLL 2

862

N/ A

N/ A

40

2

782

27

WD93028-X

IDE(XT)

21.62

3.50

HH

RLL 2

862

N/ A

N/ A

40

2

782

27

WD93034-X

IDE(XT)

32.43

3.50

HH

RLL 2

862

N/ A

N/ A

50

3

782

27

WD93038-X

IDE(XT)

32.43

3.50

HH

RLL 2

862

N/ A

N/ A

40

3

782

27

WD93044-A

IDE(AT)

43.24

3.50

HH

RLL 2

862

N/ A

N/ A

40

4

782

27

WD93044-X

IDE(XT)

43.24

3.50

HH

RLL 2

862

N/ A

N/ A

50

4

782

27

WD93048-AD

IDE(AT)

43.24

3.50

HH

RLL 2

862

N/ A

N/ A

40

4

782

27

WD93048-X

IDE(XT)

43.24

3.50

HH

RLL 2

862

N/ A

N/ A

40

4

782

27

WD95024-A

IDE(AT)

21.62

3.50

HH

RLL 2

862

N/ A

N/ A

40

2

782

27

WD95028-AD

IDE(AT)

21.62

3.50

HH

RLL 2

862

N/ A

N/ A

40

2

782

27

WD95028-X

IDE(XT)

21.62

3.50

HH

RLL 2

862

N/ A

N/ A

40

2

782

27

WD95038-X

IDE(XT)

32.43

3.50

HH

RLL 2

862

N/ A

N/ A

40

3

782

27

4

615

17

4

615

17

5

977

17

4

615

17

WD95044-A

IDE(AT)

43.24

3.50

HH

RLL 2

862

N/ A

N/ A

40

4

782

27

5

977

17

WD95048-AD

IDE(AT)

43.24

3.50

HH

RLL 2

862

N/ A

N/ A

40

4

782

27

5

977

17

WD95048-X

IDE(XT)

43.24

3.50

HH

RLL 2

862

N/ A

N/ A

40

4

782

27

WDAB130

IDE(44PIN)

31.9

2.50

4H

RLL 2

AUTO

N/ A

N/ A

50

2

1020

0

4

916

17

WDAB140

IDE(44PIN)

42.7

2.50

5H

RLL 2

AUTO

N/ A

N/ A

0

2

1390

0

5

980

17

WDAC11200

IDE(AT)

1281.9

3.50

3H

UNIDEN

0

0

0

WDAC11200 (10-PIN)

IDE(AT)

1281.9

3.50

3H

UNIDEN

0

0

0

WDAC1170

IDE(AT)

170.64

3.50

3H

RLL 2

AUTO

N/ A

N/ A

100

2

2233

0

6

1010

55

WDAC1210

IDE(AT)

212

3.50

3H

RLL 2

AUTO

N/ A

N/ A

100

0

0

0

12

989

35

WDAC1270

IDE(AT)

270.4

3.50

3H

RLL 2

AUTO

N/ A

N/ A

250

2

2233

0

12

917

48

WDAC1365

IDE(AT)

365.4

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

0

0

0

16

708

63

1399

Hard Disk Drives

M ODEL

INT

CAP

FF

HGT CODE

LZ

WP

RW C

M TBF

PHDS PCYL

PSPT LHDS LCYL LSPT

WDAC140

IDE(AT)

42.65

3.50

3H

RLL 2

AUTO

N/ A

N/ A

50

2

1082

39

5

980

17

WDAC1425

IDE(AT)

426.8

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

0

0

0

16

827

63

WDAC160

IDE(AT)

63.2

3.50

3H

RLL 2

AUTO

N/ A

N/ A

100

2

1349

0

7

1024

17

WDAC21000

IDE(AT)

1083.8

3.50

3H

UNIDEN

AUTO

N/ A

N/ A

300

4

0

0

16

2100

63

WDAC21000 (10-PIN)

IDE(AT)

1083.8

3.50

3H

UNIDEN

0

0

0

WDAC2120

IDE(AT)

126.4

3.50

3H

RLL 2

AUTO

N/ A

N/ A

100

4

1349

0

8

872

35

WDAC21200

IDE(AT)

1281.9

3.50

3H

PRM L

AUTO

N/ A

N/ A

300

4

0

0

16

2484

63

WDAC21200 (10-PIN)

IDE(AT)

1281.9

3.50

3H

UNIDEN

0

0

0

WDAC21600

IDE(AT)

1624.6

3.50

3H

PRM L

AUTO

N/ A

N/ A

300

4

0

0

16

3148

63

WDAC21600 (10-PIN)

IDE(AT)

1624.6

3.50

3H

UNIDEN

0

0

0

WDAC2170

IDE(AT)

170.6

3.50

3H

RLL 2

AUTO

N/ A

N/ A

100

4

1584

0

6

1010

55

WDAC2200

IDE(AT)

212.67

3.50

3H

RLL 2

AUTO

N/ A

N/ A

100

4

1971

0

12

989

35

WDAC22000

IDE(AT)

2000.3

3.50

3H

UNIDEN

0

0

0

WDAC22000 (10-PIN)

IDE(AT)

2000.3

3.50

3H

UNIDEN

0

0

0

WDAC22100

IDE(AT)

2111.8

3.50

3H

UNIDEN

0

0

0

WDAC22100 (10-PIN)

IDE(AT)

2111.8

3.50

3H

UNIDEN

0

0

0

WDAC2250

IDE(AT)

256

3.50

3H

RLL 2

3

2233

0

9

1010

55

WDAC22500

IDE(AT)

2559.8

3.50

3H

UNIDEN

0

0

0

WDAC22500 (10-PIN)

IDE(AT)

2559.8

3.50

3H

UNIDEN

0

0

0

WDAC2340

IDE(AT)

341.29

3.50

3H

RLL 2

AUTO

N/ A

N/ A

100

4

2233

0

12

1010

55

WDAC2420

IDE(AT)

425.3

3.50

3H

RLL 2

AUTO

N/ A

N/ A

100

0

0

0

15

989

56

WDAC2540

IDE(AT)

540.86

3.50

3H

RLL 2

AUTO

N/ A

N/ A

100

0

0

0

16

1048

63

WDAC2540 (10-PIN)

IDE(AT)

540.8

3.50

3H

UNIDEN

AUTO

N/ A

N/ A

0

0

0

WDAC2635

IDE(AT)

639.9

3.50

3H

RLL 1

AUTO

N/ A

N/ A

0

0

0

16

1240

63

WDAC2635 (10-PIN)

IDE(AT)

639.9

3.50

3H

UNIDEN

AUTO

N/ A

N/ A

0

0

0

WDAC2700

IDE(AT)

696.6

3.50

3H

RLL 2

AUTO

N/ A

N/ A

0

0

0

16

1416

63

WDAC2700 (10-PIN)

IDE(AT)

730.8

3.50

3H

UNIDEN

0

0

0

WDAC280

IDE(AT)

85.29

3.50

3H

RLL 2

AUTO

N/ A

N/ A

50

4

1082

39

10

980

17

WDAC2850

IDE(AT)

853.6

3.50

3H

RLL 1

AUTO

N/ A

N/ A

250

0

0

0

16

1654

63

WDAC2850 (10-PIN)

IDE(AT)

853.6

3.50

3H

UNIDEN

0

0

0

WDAC31000

IDE(AT)

1084

3.50

3H

RLL 2

6

0

0

16

2100

63

AUTO

AUTO

N/ A

N/ A

N/ A

N/ A

100

250

100

250

(continues)

1400

Appendix D—Technical Reference

Table D.16

W ESTERN DIGITAL CORPORATION Cont inued

M ODEL

INT

CAP

FF

HGT CODE

LZ

WP

RW C

M TBF

PHDS PCYL

PSPT LHDS LCYL LSPT

WDAC31000 (10-PIN)

IDE(AT)

1083.8

3.50

3H

UNIDEN

WDAC31200

IDE(AT)

1222.6

3.50

3H

RLL 2

AUTO

N/ A

N/ A

0

0

0

0

0

0

WDAC31200 (10-PIN)

0

IDE(AT)

1281.9

3.50

3H

UNIDEN

0

0

0

WDAC31600

IDE(AT)

1549

3.50

3H

RLL 2

WDAC31600 (10-PIN)

0

0

0

IDE(AT)

1624.6

3.50

3H

UNIDEN

WDAC32100

IDE(AT)

2111.8

3.50

3H

PRM L

0

0

0

5

0

0

WDAC32100 (10-PIN)

IDE(AT)

2111.8

3.50

3H

UNIDEN

WDAC32500

IDE(XT)

2559.8

3.50

3H

PRM L

0

0

0

6

0

WDAC32500 (10-PIN)

0

IDE(AT)

2559.8

3.50

3H

UNIDEN

0

0

0

WDAC33100

IDE(AT)

3166

3.50

3H

UNIDEN

WDAC33100 (10-PIN)

6

0

0

IDE(AT)

3166.7

3.50

3H

WDAC33200

IDE(AT)

3249.3

3.50

3H

UNIDEN

0

0

0

UNIDEN

0

0

0

WDAC33200 (10-PIN)

IDE(AT)

3249.3

3.50

3H

UNIDEN

WDAC34000

IDE(AT)

1083

3.50

3H

WDAC34000 (10-PIN)

IDE(AT)

4000.7

3.50

3H

UNIDEN

WDAH260

IDE(44PIN)

63.25

2.50

4H

RLL 2

AUTO

N/ A

N/ A

WDAH280

IDE(44PIN)

85.57

2.50

4H

RLL 2

AUTO

N/ A

N/ A

WDAL1100

IDE(44PIN)

100.06

2.50

4H

RLL 1

AUTO

N/ A

WDAL2120

IDE(AT)

126.4

2.50

3H

RLL 2

AUTO

WDAL2170

IDE(AT)

170.6

2.50

3H

RLL 2

AUTO

WDAL2200

IDE(44PIN)

200.12

2.50

4H

RLL 1

WDAL2540

IDE(44PIN)

540.8

2.50

5H

WDAP105 PIRANHA

IDE(AT)

104

3.50

WDAP4200 PIRANHA

IDE(AT)

214.95

WDCU140

PCM

WDE2170 (50-PIN) WDE2170 (68-PIN) WDE2170 (80-PIN) WDE4360 (50-PIN)

AUTO

N/ A

N/ A

250

AUTO

N/ A

N/ A

300

AUTO

N/ A

N/ A

300

AUTO

N/ A

N/ A

300

16

2484

63

16

3148

63

16

4092

63

16

4960

63

16

6136

63

16

7752

63

17

0

0

0

0

0

0

0

0

0

50

4

1020

0

7

1024

50

4

1390

0

10

980

17

N/ A

100

2

1900

0

6

958

34

N/ A

N/ A

100

4

1349

0

8

872

35

N/ A

N/ A

100

4

1584

0

6

1010

55

AUTO

N/ A

N/ A

100

2

1900

0

12

958

34

UNIDEN

AUTO

N/ A

N/ A

300

4

0

0

16

1048

63

HH

RLL 2

AUTO

N/ A

N/ A

50

4

0

0

3.50

HH

RLL 2

AUTO

N/ A

N/ A

86

8

1280

41

12

987

35

42.65

2.50

4H

RLL 1

AUTO

N/ A

N/ A

255

2

1050

0

5

980

17

U-SCSI

2170

3.50

3H

AUTO

N/ A

N/ A

1000

0

0

0

U-SCSI W

2170

3.50

3H

AUTO

N/ A

N/ A

1000

0

0

0

U-SCSI W

2170

3.50

3H

AUTO

N/ A

N/ A

1000

0

0

0

U-SCSI

4360

3.50

3H

AUTO

N/ A

N/ A

1000

0

0

0

AUTO

N/ A

N/ A

350

Hard Disk Drives

1401

M ODEL

INT

CAP

FF

HGT CODE

LZ

WP

RW C

M TBF

PHDS PCYL

PSPT LHDS LCYL LSPT

WDE4360 (68-PIN)

U-SCSI W

4360

3.50

3H

AUTO

N/ A

N/ A

1000

0

0

0

WDE4360 (80-PIN)

U-SCSI W

4360

3.50

3H

AUTO

N/ A

N/ A

1000

0

0

0

WDSC8320

SCSI-2

326.51

3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

14

949

48

WDSC8400

SCSI-2

412.53

3.50

HH

RLL 1

AUTO

N/ A

N/ A

150

14

1199

48

WDSP105 PIRANHA

SCSI

104

3.50

HH

RLL 2

AUTO

N/ A

N/ A

50

4

0

0

WDSP2100 PIRANHA

SCSI-2

106.21

3.50

HH

RLL 2

AUTO

N/ A

N/ A

50

4

1265

41

WDSP4200 REV. 1

SCSI

209.71

3.50

HH

RLL 2

AUTO

N/ A

N/ A

86

8

1280

40

WDSP4200 REV. 2

SCSI

209.71

3.50

3H

RLL 2

AUTO

N/ A

N/ A

86

8

1280

40

WDUC140

PCM

42.65

5.25

FH

RLL 2

AUTO

N/ A

N/ A

50

2

1050

0

If th e logical p aram eters for you r IDE h ard d rive are n ot listed in Tables D.10–D.16 an d th e actu al p h ysical d rive p aram eters are n ot legal for th e BIOS, u se Table D.17* to con figu re an IDE h ard d rive as a u ser-d efin able d rive typ e in you r BIOS (typ ically typ e 46 or 47). In th e table, look u p you r d rive cap acity in colu m n on e an d en ter th e sp ecification s in to th e h ost system ’s u ser-d efin able d rive typ e section . Th is table is valid on ly wh en u sed with IDE-typ e h ard d rives. Table D.17

IDE Quick Reference Chart

CAP HDS

SPT

CYL

CAP HDS

SPT

CYL

CAP HDS

SPT

CYL

20

4

17

574

37

5

17

850

54

7

17

886

21

4

17

603

38

5

17

873

55

7

17

902

22

4

17

631

39

5

17

896

56

7

17

919

23

4

17

660

40

5

17

919

57

7

17

935

24

4

17

689

41

5

17

942

58

7

17

951

25

4

17

718

42

5

17

965

59

7

17

968

26

4

17

746

43

5

17

988

60

7

17

984

27

4

17

775

44

5

17

1011

61

7

17

1001

28

4

17

804

45

6

17

861

62

7

17

1017

29

4

17

832

46

6

17

880

63

8

17

904

30

4

17

861

47

6

17

899

64

8

17

919

31

4

17

890

48

6

17

919

65

8

17

933

32

4

17

919

49

6

17

938

66

8

17

947

33

4

17

947

50

6

17

957

67

8

17

962

34

4

17

976

51

6

17

976

68

8

17

976

35

4

17

1005

52

6

17

995

69

8

17

990

36

5

17

827

53

6

17

1014

70

8

17

1005 (continues)

* Table D.17 is reprinted from Th e Micro Hou se PC Hard ware Library , Copyright  Que Corporation and Micro House International, Inc. 1988.

1402

Appendix D—Technical Reference

Table D.17

IDE Quick Reference Chart Cont inued

CAP HDS

SPT

CYL

CAP HDS

SPT

CYL

CAP HDS

SPT

CYL

71

8

17

1019

228

14

33

963

267

16

33

987

72

9

17

919

229

14

33

968

268

16

33

991

73

9

17

931

230

14

33

972

269

16

33

995

74

9

17

944

231

14

33

976

270

16

33

998

75

9

17

957

232

14

33

980

271

16

33

1002

76

9

17

970

233

14

33

985

272

16

33

1006

77

9

17

982

234

14

33

989

273

16

33

1009

78

9

17

995

235

14

33

993

274

16

33

1013

79

9

17

1008

236

14

33

997

275

16

33

1017

80

9

17

1021

237

14

33

1001

276

16

33

1020

81

10

17

930

238

14

33

1006

277

16

33

1024

82

10

17

942

239

14

33

1010

278

9

63

957

83

10

17

953

240

14

33

1014

279

9

63

961

84

10

17

965

241

14

33

1018

280

9

63

964

85

10

17

976

242

14

33

1023

281

9

63

967

86

10

17

988

243

15

33

958

282

9

63

971

87

10

17

999

244

15

33

962

283

9

63

974

88

10

17

1011

245

15

33

966

284

9

63

978

89

10

17

1022

246

15

33

970

285

9

63

981

90

11

17

940

247

15

33

974

286

9

63

985

91

11

17

950

248

15

33

978

287

9

63

988

92

11

17

960

249

15

33

982

288

9

63

992

93

11

17

971

250

15

33

986

289

9

63

995

94

11

17

981

251

15

33

990

290

9

63

998

95

11

17

992

252

15

33

994

291

9

63

1002

96

11

17

1002

253

15

33

998

292

9

63

1005

97

11

17

1013

254

15

33

1002

293

9

63

1009

98

11

17

1023

255

15

33

1006

294

9

63

1012

99

12

17

947

256

15

33

1010

295

9

63

1016

100

12

17

957

257

15

33

1014

296

9

63

1019

101

12

17

966

258

15

33

1017

297

9

63

1023

102

12

17

976

259

15

33

1021

298

10

63

923

103

12

17

986

260

16

33

961

299

10

63

926

104

12

17

995

261

16

33

965

300

10

63

930

105

12

17

1005

262

16

33

969

301

10

63

933

106

12

17

1014

263

16

33

972

302

10

63

936

107

12

17

1024

264

16

33

976

303

10

63

939

108

13

17

954

265

16

33

980

304

10

63

942

109

13

17

963

266

16

33

983

305

10

63

945

Hard Disk Drives

CAP HDS

SPT

CYL

CAP HDS

SPT

CYL

CAP HDS

SPT

CYL

110

13

17

972

149

9

33

979

189

11

33

1016

111

13

17

980

150

9

33

986

190

11

33

1022

112

13

17

989

151

9

33

993

191

12

33

942

113

13

17

998

152

9

33

999

192

12

33

946

114

13

17

1007

153

9

33

1006

193

12

33

951

115

13

17

1016

154

9

33

1012

194

12

33

956

116

14

17

951

155

9

33

1019

195

12

33

961

117

14

17

960

156

10

33

923

196

12

33

966

118

14

17

968

157

10

33

929

197

12

33

971

119

14

17

976

158

10

33

935

198

12

33

976

120

14

17

984

159

10

33

941

199

12

33

981

121

14

17

992

160

10

33

946

200

12

33

986

122

14

17

1001

161

10

33

952

201

12

33

991

123

14

17

1009

162

10

33

958

202

12

33

996

124

14

17

1017

163

10

33

964

203

12

33

1001

125

15

17

957

164

10

33

970

204

12

33

1006

126

15

17

965

166

10

33

982

205

12

33

1011

127

15

17

972

167

10

33

988

206

12

33

1016

128

15

17

980

168

10

33

994

207

12

33

1020

129

15

17

988

169

10

33

1000

208

13

33

946

130

15

17

995

170

10

33

1006

209

13

33

951

131

15

17

1003

171

10

33

1012

210

13

33

956

132

15

17

1011

172

10

33

1017

211

13

33

960

133

15

17

1018

173

10

33

1023

212

13

33

965

134

16

17

962

174

11

33

936

213

13

33

969

135

16

17

969

175

11

33

941

214

13

33

974

136

16

17

976

176

11

33

946

215

13

33

978

137

16

17

983

177

11

33

952

216

13

33

983

138

16

17

990

178

11

33

957

217

13

33

987

139

16

17

998

179

11

33

963

218

13

33

992

140

16

17

1005

180

11

33

968

219

13

33

997

141

16

17

1012

181

11

33

973

220

13

33

1001

142

16

17

1019

182

11

33

979

221

13

33

1006

143

9

33

940

183

11

33

984

222

13

33

1010

144

9

33

946

184

11

33

990

223

13

33

1015

145

9

33

953

185

11

33

995

224

13

33

1019

146

9

33

960

186

11

33

1000

225

13

33

1024

147

9

33

966

187

11

33

1006

226

14

33

955

148

9

33

973

188

11

33

1011

227

14

33

959 (continues)

1403

1404

Appendix D—Technical Reference

Table D.17

IDE Quick Reference Chart Cont inued

CAP HDS

SPT

CYL

CAP HDS

SPT

CYL

CAP HDS

SPT

CYL

306

10

63

948

388

12

63

1002

428

13

63

1020

307

10

63

951

389

12

63

1004

427

13

63

1018

308

10

63

954

390

12

63

1007

427

13

63

1018

309

10

63

957

391

12

63

1010

428

13

63

1020

310

10

63

961

392

12

63

1012

429

13

63

1023

311

10

63

964

393

12

63

1015

430

14

63

952

312

10

63

967

394

12

63

1017

431

14

63

954

313

10

63

970

395

12

63

1020

432

14

63

956

314

10

63

973

396

12

63

1023

433

14

63

958

315

10

63

976

397

13

63

946

434

14

63

961

316

10

63

979

398

13

63

949

435

14

63

963

317

10

63

982

399

13

63

951

436

14

63

965

318

10

63

985

400

13

63

953

437

14

63

967

362

11

63

1020

401

13

63

956

438

14

63

969

363

11

63

1023

402

13

63

958

439

14

63

972

364

12

63

940

403

13

63

961

440

14

63

974

365

12

63

942

404

13

63

963

441

14

63

976

366

12

63

945

405

13

63

965

442

14

63

978

367

12

63

948

406

13

63

968

443

14

63

980

368

12

63

950

407

13

63

970

444

14

63

983

369

12

63

953

408

13

63

972

445

14

63

985

370

12

63

955

409

13

63

975

446

14

63

987

371

12

63

958

410

13

63

977

447

14

63

989

372

12

63

961

411

13

63

980

448

14

63

992

373

12

63

963

412

13

63

982

449

14

63

994

374

12

63

966

413

13

63

984

450

14

63

996

375

12

63

968

414

13

63

987

451

14

63

998

376

12

63

971

415

13

63

989

452

14

63

1000

377

12

63

973

416

13

63

992

453

14

63

1003

378

12

63

976

417

13

63

994

454

14

63

1005

379

12

63

979

418

13

63

996

455

14

63

1007

380

12

63

981

419

13

63

999

456

14

63

1009

381

12

63

984

420

13

63

1001

457

14

63

1011

382

12

63

986

421

13

63

1003

458

14

63

1014

383

12

63

989

422

13

63

1006

459

14

63

1016

384

12

63

992

423

13

63

1008

460

14

63

1018

385

12

63

994

424

13

63

1011

461

14

63

1020

386

12

63

997

425

13

63

1013

462

14

63

1023

387

12

63

999

427

13

63

1018

463

15

63

956

Hard Disk Drives

CAP HDS

SPT

CYL

CAP HDS

SPT

CYL

CAP HDS

SPT

CYL

15

63

1004

508

16

63

984

464

15

63

958

486

465

15

63

961

487

15

63

1006

509

16

63

986

466

15

63

963

488

15

63

1008

510

16

63

988

467

15

63

965

489

15

63

1010

511

16

63

990

15

63

1012

512

16

63

992

468

15

63

967

490

469

15

63

969

491

15

63

1014

513

16

63

994

470

15

63

971

492

15

63

1016

514

16

63

995

471

15

63

973

493

15

63

1018

515

16

63

997

15

63

1020

516

16

63

999

472

15

63

975

494

473

15

63

977

495

15

63

1023

517

16

63

1001

474

15

63

979

496

16

63

960

518

16

63

1003

475

15

63

981

497

16

63

962

519

16

63

1005

16

63

964

520

16

63

1007

476

15

63

983

498

477

15

63

985

499

16

63

966

521

16

63

1009

478

15

63

987

500

16

63

968

522

16

63

1011

479

15

63

989

501

16

63

970

523

16

63

1013

16

63

972

524

16

63

1015

480

15

63

992

502

481

15

63

994

503

16

63

974

525

16

63

1017

482

15

63

996

504

16

63

976

526

16

63

1019

483

15

63

998

505

16

63

978

527

16

63

1021

16

63

980

528

16

63

1023

16

63

982

484

15

63

1000

506

485

15

63

1002

507

Th e p aram eters p rovid ed are calcu lated not to exceed th e form atted cap acity sp ecified . For exam p le: Th e p aram eters’ list for 130Ms, 15HDS×995CYL×17SPT×512BPS = 129,907,200 bytes. If you kn ow th e exact cap acity of th e d rive, you m ay in crease th e cylin d er cou n t to ach ieve m axim u m cap acity. For exam p le: If th e d rive’s cap acity is 130.76M, you cou ld in crease th e cylin d er cou n t to 1001 for a cap acity of 130,690,560 bytes, forfeitin g on ly abou t 7K. You ’ll n otice th at th e largest d rive available with 17 sectors is 142M. You can still u se a d rive with a h igh er cap acity by in creasin g th e sectors, su ch as th e 143 to 528M d rives sh own p reviou sly. ROM BIOS Hard Drive Param et ers Th e followin g exp lain s th e colu m n h ead in gs u sed in Tables D.18–D.22: Typ e = Drive typ e n u m ber Cylin d ers = Total n u m ber of cylin d ers

1405

1406

Appendix D—Technical Reference

Head s = Total n u m ber of h ead s W PC = W rite p recom p en sation startin g cylin d er 65535 = No write p recom p en sation 0 = W rite p recom p en sation on all cylin d ers Ctrl = Con trol byte, with valu es accord in g to th e followin g table. Bit Num ber Hex

M eaning

Bit 0

01h

Not used (XT = drive step rate)

Bit 1

02h

Not used (XT = drive step rate)

Bit 2

04h

Not used (XT = drive step rate)

Bit 3

08h

M ore than eight heads

Bit 4

10h

Not used (XT = embedded servo drive)

Bit 5

20h

OEM defect map at (cylinders + 1)

Bit 6

40h

Disable ECC retries

Bit 7

80h

Disable disk access retries

LZ = Lan d in g-zon e cylin d er for h ead p arkin g S/ T = Nu m ber of sectors p er track Meg = Drive cap acity in m egabytes M = Drive cap acity in m illion s of bytes Table D.18

IBM AT and PS/ 2 BIOS Hard Disk Table

Type Cylinders Heads

W PC

Ct rl

LZ

S/ T

M eg

M

1

306

4

128

00h

305

17

10.16

10.65

2

615

4

300

00h

615

17

20.42

21.41

3

615

6

300

00h

615

17

30.63

32.12

4

940

8

512

00h

940

17

62.42

65.45

5

940

6

512

00h

940

17

46.82

49.09

6

615

4

65535

00h

615

17

20.42

21.41

7

462

8

256

00h

511

17

30.68

32.17

8

733

5

65535

00h

733

17

30.42

31.90

9

900

15

65535

08h

901

17

112.06

117.50

10

820

3

65535

00h

820

17

20.42

21.41

11

855

5

65535

00h

855

17

35.49

37.21

12

855

7

65535

00h

855

17

49.68

52.09

13

306

8

128

00h

319

17

20.32

21.31

14

733

7

65535

00h

733

17

42.59

44.66

15

0

0

0

00h

0

0

0

0

16

612

4

0

00h

663

17

20.32

21.31

Hard Disk Drives

Type Cylinders Heads

W PC

Ct rl

LZ

S/ T

M eg

M

17

977

5

300

00h

977

17

40.55

42.52

18

977

7

65535

00h

977

17

56.77

59.53

19

1024

7

512

00h

1023

17

59.50

62.39

20

733

5

300

00h

732

17

30.42

31.90

21

733

7

300

00h

732

17

42.59

44.66

22

733

5

300

00h

733

17

30.42

31.90

23

306

4

0

00h

336

17

10.16

10.65

24

612

4

305

00h

663

17

20.32

21.31

25

306

4

65535

00h

340

17

10.16

10.65

26

612

4

65535

00h

670

17

20.32

21.31

27

698

7

300

20h

732

17

40.56

42.53

28

976

5

488

20h

977

17

40.51

42.48

29

306

4

0

00h

340

17

10.16

10.65

30

611

4

306

20h

663

17

20.29

21.27

31

732

7

300

20h

732

17

42.53

44.60

32

1023

5

65535

20h

1023

17

42.46

44.52

33

614

4

65535

20h

663

25

29.98

31.44

34

775

2

65535

20h

900

27

20.43

21.43

35

921

2

65535

20h

1000

33

29.68

31.12

36

402

4

65535

20h

460

26

20.41

21.41

37

580

6

65535

20h

640

26

44.18

46.33

38

845

2

65535

20h

1023

36

29.71

31.15

39

769

3

65535

20h

1023

36

40.55

42.52

40

531

4

65535

20h

532

39

40.45

42.41

41

577

2

65535

20h

1023

36

20.29

21.27

42

654

2

65535

20h

674

32

20.44

21.43

43

923

5

65535

20h

1023

36

81.12

85.06

44

531

8

65535

20h

532

39

80.89

84.82

45

0

0

0

00h

0

0

0.00

0.00

46

0

0

0

00h

0

0

0.00

0.00

47

0

0

0

00h

0

0

0.00

0.00

Th e lan d in g zon e (LZ) an d sectors p er track (S/ T) field s are n ot u sed in th e 10M (origin al) con troller an d con tain 00h valu es for each en try. Table en try 15 is reserved to act as a p oin ter to in d icate th at th e typ e is greater th an 15. Old er IBM system s d o n ot h ave every en try in th is table. Th e m axim u m u sable typ e n u m ber varies for each p articu lar ROM version . Most IBM PS/ 2 system s were su p p lied with h ard d isk d rives th at h ave th e d efect m ap written as d ata on th e cylin d er on e cylin d er beyon d th e h igh est rep orted cylin d er. Th is sp ecial d ata is read by th e IBM PS/ 2 Ad van ced Diagn ostics low-level form at p rogram .

1407

1408

Appendix D—Technical Reference

Th is p rocess au tom ates th e en try of th e d efect list an d elim in ates th e ch an ce of h u m an error, as lon g as you u se on ly th e IBM PS/ 2 Ad van ced Diagn ostics for h ard d isk low-level form attin g. Th is typ e of table d oes n ot ap p ly to IBM ESDI or SCSI h ard d isk con trollers, h ost ad ap ters, an d d rives. Becau se th e ESDI an d SCSI con trollers or h ost ad ap ters q u ery th e d rive d irectly for th e req u ired p aram eters, n o table-en try selection is n ecessary. Note, h owever, th at th e table for th e ST-506/ 412 d rives can still be fou n d cu rren tly in th e ROM BIOS of m ost of th e PS/ 2 system s, even if th e m od el cam e stan d ard with an ESDI or SCSI d isk su bsystem . Table D.19 sh ows th e Com p aq m oth erboard ROM BIOS h ard d isk p aram eters for th e Com p aq Deskp ro 386. Table D.19

Com paq Deskpro 386 Hard Disk Table

Type Cylinders Heads

W PC

Ct rl

LZ

S/ T

M eg

M

1

306

4

128

00h

305

17

10.16

10.65

2

615

4

128

00h

638

17

20.42

21.41

3

615

6

128

00h

615

17

30.63

32.12

4

1024

8

512

00h

1023

17

68.00

71.30

5

940

6

512

00h

939

17

46.82

49.09

6

697

5

128

00h

696

17

28.93

30.33

7

462

8

256

00h

511

17

30.68

32.17

8

925

5

128

00h

924

17

38.39

40.26

9

900

15

65535

08h

899

17

112.06

117.50

10

980

5

65535

00h

980

17

40.67

42.65

11

925

7

128

00h

924

17

53.75

56.36

12

925

9

128

08h

924

17

69.10

72.46

13

612

8

256

00h

611

17

40.64

42.61

14

980

4

128

00h

980

17

32.54

34.12

15

0

0

0

00h

0

0

0

0

16

612

4

0

00h

612

17

20.32

21.31

17

980

5

128

00h

980

17

40.67

42.65

18

966

6

128

00h

966

17

48.11

50.45

19

1023

8

65535

00h

1023

17

67.93

71.23

20

733

5

256

00h

732

17

30.42

31.90

21

733

7

256

00h

732

17

42.59

44.66

22

805

6

65535

00h

805

17

40.09

42.04

23

924

8

65535

00h

924

17

61.36

64.34

24

966

14

65535

08h

966

17

112.26

117.71

25

966

16

65535

08h

966

17

128.30

134.53

26

1023

14

65535

08h

1023

17

118.88

124.66

Hard Disk Drives

Type Cylinders Heads

W PC

Ct rl

LZ

S/ T

M eg

M

27

966

10

65535

08h

966

17

80.19

84.08

28

748

16

65535

08h

748

17

99.34

104.17

29

805

6

65535

00h

805

26

61.32

64.30

30

615

4

128

00h

615

25

30.03

31.49

31

615

8

128

00h

615

25

60.06

62.98

32

905

9

128

08h

905

25

99.43

104.26

33

748

8

65535

00h

748

34

99.34

104.17

34

966

7

65535

00h

966

34

112.26

117.71

35

966

8

65535

00h

966

34

128.30

134.53

36

966

9

65535

08h

966

34

144.33

151.35

37

966

5

65535

00h

966

34

80.19

84.08

38

611

16

65535

08h

611

63

300.73

315.33

39

1023

11

65535

08h

1023

33

181.32

190.13

40

1023

15

65535

08h

1023

34

254.75

267.13

41

1023

15

65535

08h

1023

33

247.26

259.27

42

1023

16

65535

08h

1023

63

503.51

527.97

43

805

4

65535

00h

805

26

40.88

42.86

44

805

2

65535

00h

805

26

20.44

21.43

45

748

8

65535

00h

748

33

96.42

101.11

46

748

6

65535

00h

748

33

72.32

75.83

47

966

5

128

00h

966

25

58.96

61.82

Table D.20 sh ows th e AMI ROM BIOS (286 BIOS version 04/ 30/ 89) h ard d isk p aram eters. Table D.20

AM I ROM BIOS ( 286 BIOS Version 04/ 30/ 89) Hard Disk Table

Type Cylinders Heads

W PC

Ct rl

LZ

S/ T

M eg

M

1

306

4

128

00h

305

17

10.16

10.65

2

615

4

300

00h

615

17

20.42

21.41

3

615

6

300

00h

615

17

30.63

32.12

4

940

8

512

00h

940

17

62.42

65.45

5

940

6

512

00h

940

17

46.82

49.09

6

615

4

65535

00h

615

17

20.42

21.41

7

462

8

256

00h

511

17

30.68

32.17

8

733

5

65535

00h

733

17

30.42

31.90

9

900

15

65535

08h

901

17

112.06

117.50

10

820

3

65535

00h

820

17

20.42

21.41

11

855

5

65535

00h

855

17

35.49

37.21

12

855

7

65535

00h

855

17

49.68

52.09

13

306

8

128

00h

319

17

20.32

21.31 (continues)

1409

1410

Appendix D—Technical Reference

Table D.20

AM I ROM BIOS ( 286 BIOS Version 04/ 30/ 89) Hard Disk Table

Cont inued Type Cylinders Heads

W PC

Ct rl

LZ

S/ T

M eg

M

14

733

7

65535

00h

733

17

42.59

44.66

15

0

0

0

00h

0

0

0

0

16

612

4

0

00h

663

17

20.32

21.31

17

977

5

300

00h

977

17

40.55

42.52

18

977

7

65535

00h

977

17

56.77

59.53

19

1024

7

512

00h

1023

17

59.50

62.39

20

733

5

300

00h

732

17

30.42

31.90

21

733

7

300

00h

732

17

42.59

44.66

22

733

5

300

00h

733

17

30.42

31.90

23

306

4

0

00h

336

17

10.16

10.65

24

925

7

0

00h

925

17

53.75

56.36

25

925

9

65535

08h

925

17

69.10

72.46

26

754

7

526

00h

754

17

43.81

45.94

27

754

11

65535

08h

754

17

68.85

72.19

28

699

7

256

00h

699

17

40.62

42.59

29

823

10

65535

08h

823

17

68.32

71.63

30

918

7

874

00h

918

17

53.34

55.93

31

1024

11

65535

08h

1024

17

93.50

98.04

32

1024

15

65535

08h

1024

17

127.50

133.69

33

1024

5

1024

00h

1024

17

42.50

44.56

34

612

2

128

00h

612

17

10.16

10.65

35

1024

9

65535

08h

1024

17

76.50

80.22

36

1024

8

512

00h

1024

17

68.00

71.30

37

615

8

128

00h

615

17

40.84

42.82

38

987

3

805

00h

987

17

24.58

25.77

39

987

7

805

00h

987

17

57.35

60.14

40

820

6

820

00h

820

17

40.84

42.82

41

977

5

815

00h

977

17

40.55

42.52

42

981

5

811

00h

981

17

40.72

42.69

43

830

7

512

00h

830

17

48.23

50.57

44

830

10

65535

08h

830

17

68.90

72.24

45

917

15

65535

08h

918

17

114.18

119.72

46

1224

15

65535

08h

1223

17

152.40

159.81

47

0

0

0

00h

0

0

0.00

0.00

Table D.21 sh ows th e Award ROM BIOS (286 BIOS version 04/ 30/ 89) (Mod u lar 286, 386SX, an d 386 BIOS version 3.05) h ard d isk p aram eters.

Hard Disk Drives

Table D.21

Aw ard ROM BIOS Version 3.05 Hard Disk Table

Type Cylinders Heads

W PC

Ct rl

LZ

S/ T

M eg

M

1

306

4

128

00h

305

17

10.16

10.65

2

615

4

300

00h

615

17

20.42

21.41

3

615

6

300

00h

615

17

30.63

32.12

4

940

8

512

00h

940

17

62.42

65.45

5

940

6

512

00h

940

17

46.82

49.09

6

615

4

65535

00h

615

17

20.42

21.41

7

462

8

256

00h

511

17

30.68

32.17

8

733

5

65535

00h

733

17

30.42

31.90

9

900

15

65535

08h

901

17

112.06

117.50

10

820

3

65535

00h

820

17

20.42

21.41

11

855

5

65535

00h

855

17

35.49

37.21

12

855

7

65535

00h

855

17

49.68

52.09

13

306

8

128

00h

319

17

20.32

21.31

14

733

7

65535

00h

733

17

42.59

44.66

15

0

0

0

00h

0

0

0

0

16

612

4

0

00h

663

17

20.32

21.31

17

977

5

300

00h

977

17

40.55

42.52

18

977

7

65535

00h

977

17

56.77

59.53

19

1024

7

512

00h

1023

17

59.50

62.39

20

733

5

300

00h

732

17

30.42

31.90

21

733

7

300

00h

732

17

42.59

44.66

22

733

5

300

00h

733

17

30.42

31.90

23

306

4

0

00h

336

17

10.16

10.65

24

977

5

65535

00h

976

17

40.55

42.52

25

1024

9

65535

08h

1023

17

76.50

80.22

26

1224

7

65535

00h

1223

17

71.12

74.58

27

1224

11

65535

08h

1223

17

111.76

117.19

28

1224

15

65535

08h

1223

17

152.40

159.81

29

1024

8

65535

00h

1023

17

68.00

71.30

30

1024

11

65535

08h

1023

17

93.50

98.04

31

918

11

65535

08h

1023

17

83.82

87.89

32

925

9

65535

08h

926

17

69.10

72.46

33

1024

10

65535

08h

1023

17

85.00

89.13

34

1024

12

65535

08h

1023

17

102.00

106.95

35

1024

13

65535

08h

1023

17

110.50

115.87

36

1024

14

65535

08h

1023

17

119.00

124.78

37

1024

2

65535

00h

1023

17

17.00

17.83

38

1024

16

65535

08h

1023

17

136.00

142.61 (continues)

1411

1412

Appendix D—Technical Reference

Table D.21

Aw ard ROM BIOS Version 3.05 Hard Disk Table Cont inued

Type Cylinders Heads

W PC

Ct rl

LZ

S/ T

M eg

M

39

918

15

65535

08h

1023

17

114.30

119.85

40

820

6

65535

00h

820

17

40.84

42.82

41

1024

5

65535

00h

1023

17

42.50

44.56

42

1024

5

65535

00h

1023

26

65.00

68.16

43

809

6

65535

00h

808

17

40.29

42.25

44

820

6

65535

00h

819

26

62.46

65.50

45

776

8

65535

00h

775

33

100.03

104.89

46

0

0

0

00h

0

0

0.00

0.00

47

0

0

0

00h

0

0

0.00

0.00

Table D.22 sh ows th e Ph oen ix 286 ROM BIOS (80286 ROM BIOS version 3.01, d ated 11/ 01/ 86) h ard d isk p aram eters. Table D.22

Phoenix 286 ( 80286 ROM BIOS Version 3.01) Hard Disk Table

Type Cylinders Heads

W PC

Ct rl

LZ

S/ T

M eg

M

1

306

4

128

00h

305

17

10.16

10.65

2

615

4

300

00h

638

17

20.42

21.41

3

615

6

300

00h

615

17

30.63

32.12

4

940

8

512

00h

940

17

62.42

65.45

5

940

6

512

00h

940

17

46.82

49.09

6

615

4

65535

00h

615

17

20.42

21.41

7

462

8

256

00h

511

17

30.68

32.17

8

733

5

65535

00h

733

17

30.42

31.90

9

900

15

65535

08h

901

17

112.06

117.50

10

820

3

65535

00h

820

17

20.42

21.41

11

855

5

65535

00h

855

17

35.49

37.21

12

855

7

65535

00h

855

17

49.68

52.09

13

306

8

128

00h

319

17

20.32

21.31

14

733

7

65535

00h

733

17

42.59

44.66

15

0

0

0

00h

0

0

0.00

0.00

16

612

4

0

00h

633

17

20.32

21.31

17

977

5

300

00h

977

17

40.55

42.52

18

977

7

65535

00h

977

17

56.77

59.53

19

1024

7

512

00h

1023

17

59.50

62.39

20

733

5

300

00h

732

17

30.42

31.90

21

733

7

300

00h

733

17

42.59

44.66

22

733

5

300

00h

733

17

30.42

31.90

23

0

0

0

00h

0

0

0.00

0.00

24

0

0

0

00h

0

0

0.00

0.00

DOS Command Reference

Type Cylinders Heads

W PC

Ct rl

LZ

S/ T

M eg

M

25

0

0

0

00h

0

0

0.00

0.00

26

0

0

0

00h

0

0

0.00

0.00

27

0

0

0

00h

0

0

0.00

0.00

28

0

0

0

00h

0

0

0.00

0.00

29

0

0

0

00h

0

0

0.00

0.00

30

0

0

0

00h

0

0

0.00

0.00

31

0

0

0

00h

0

0

0.00

0.00

32

0

0

0

00h

0

0

0.00

0.00

33

0

0

0

00h

0

0

0.00

0.00

34

0

0

0

00h

0

0

0.00

0.00

35

0

0

0

00h

0

0

0.00

0.00

36

1024

5

512

00h

1024

17

42.50

44.56

37

830

10

65535

08h

830

17

68.90

72.24

38

823

10

256

08h

824

17

68.32

71.63

39

615

4

128

00h

664

17

20.42

21.41

40

615

8

128

00h

664

17

40.84

42.82

41

917

15

65535

08h

918

17

114.18

119.72

42

1023

15

65535

08h

1024

17

127.38

133.56

43

823

10

512

08h

823

17

68.32

71.63

44

820

6

65535

00h

820

17

40.84

42.82

45

1024

8

65535

00h

1024

17

68.00

71.30

46

925

9

65535

08h

925

17

69.10

72.46

47

1024

5

65535

00h

1024

17

42.50

44.56

DOS Com m and Reference Even if th e system s you su p p ort, u p grad e, an d rep air are all ru n n in g th e latest version of W in d ows, you will in evitably fin d you rself occasion ally trou blesh ootin g th ese system s from th e DOS com m an d lin e. W ith th at in m in d , I h ave in clu d ed th is brief DOS com m an d referen ce to aid you wh en you are at th e com m an d lin e.* DOS Com m ands Found in DOS 6.22, W indow s 95, and W indow s 98 W in d ows 95 an d W in d ows 98 both still in clu d e DOS com m an d s. Th e version of DOS with W in d ows 95 is called 7.0 an d th e version with W in d ows 98 is called 7.1. For th e m ost p art, DOS 7.x com m an d s are ju st a su bset of th e com m an d s fou n d in DOS 6.22. However, DOS 7.x d oes h ave a few n ew featu res n ot fou n d in DOS 6.x, so th e n ew DOS is n ot th e sam e as th e old DOS. Here’s a p artial list of im p rovem en ts: ■ You can start W in d ows p rogram s from th e DOS p rom p t an d even from with in batch files. ■ Th e n ew DOS in clu d es su p p ort for lon g file n am es. * This DOS com m and reference is based substantially on m aterial found in Paul McFedries’ W in d ows 98 Un leash ed Profession al Referen ce Ed ition , copyright  1998 Sam s Publishing, all rights reserved. Used with perm ission.

1413

1414

Appendix D—Technical Reference

■ Red u ced relian ce on real-m od e d rivers m ean s th at m ore con ven tion al m em ory is available for DOS p rogram s. ■ Each DOS p rogram can h ave its own settin gs an d en viron m en t (CONFIG.SYS an d AUTOEXEC.BAT). Th ese are con trolled via p rop erty sh eets, so th ere’s n o n eed to create p rogram in form ation files (PIFs) from scratch for each p rogram . ■ You can ru n DOS p rogram s in MS-DOS m od e if th ey n eed fu ll access to th e com p u ter’s resou rces. ■ Th e DOS session win d ow h as a toolbar for easy access to com m on featu res. ■ You can access sh ared n etwork fold ers via th e com m an d p rom p t. ■ Most DOS com m an d s are n ow n ative W in d ows 98 com m an d s. W in d ows 98 is, for th e m ost p art, th e op eratin g system on you r m ach in e. Yes, it com es with som e real-m od e com p on en ts (su ch as IO.SYS) th at are DOS-like, bu t th ey really ju st h an d le a few ch ores u n til W in d ows 98 can get itself in to p rotected m od e. After W in d ows 98 is ru n n in g, h owever, “DOS” is ju st two th in gs: ■ COMMAND.COM, wh ich p rovid es th e DOS p rom p t an d a collection of in tern al DOS com m an d s (su ch as COPY an d DIR) ■ A few extern al DOS com m an d s, su ch as FORMAT.COM an d XCOPY.EXE For W in d ows 95 (an d , so, W in d ows 98), Microsoft en h an ced som e of th ese com m an d s, d rop p ed oth er com m an d s, an d m ad e a few of th e d rop p ed com m an d s available on th e CD-ROM. Table D.23 lists th e in tern al DOS com m an d s available with in th e DOS 6.22, W in d ows 95, an d W in d ows 98 version s of COMMAND.COM. Table D.23

The W indow s 98 Int ernal DOS Com m ands

Com m and

Descript ion

BREAK

Sets or clears extended Ctrl+C checking.

CD

Changes to a different directory or, if run without parameters, displays the name of the current directory.

CHCP

Displays the number of the active character set (code page). You can also use this command to change the active character set for all devices that support characterset switching.

CHDIR

Takes the same action as the CD command.

CLS

Clears the screen.

COPY

Copies one or more files to the location you specify.

CTTY

Changes the terminal device used to control the computer.

DATE

Displays or sets the current date.

DEL

Deletes the files you specify.

DIR

Displays a list of the files and subfolders that exist in the current or specified folder.

DOS Command Reference

Com m and

Descript ion

ERASE

Deletes the files you specify.

EXIT

Quits COMMAND.COM and returns to the program that started the command interpreter, if one exists.

LH

Loads a program into upper memory.

LOADHIGH

Takes the same action as the LH command.

LOCK

Enables direct disk access.

MD

Creates a folder or subfolder.

MKDIR

Takes the same action as the MD command.

PATH

Specifies which folders Windows 98 should search for executable files.

PROMPT

Changes the appearance of the command prompt.

RD

Deletes a folder.

REN

Changes the name of the specified file or files.

RENAME

Takes the same action as the REN command.

RMDIR

Takes the same action as the RD command.

SET

Displays, sets, or removes environment variables.

TIME

Displays or sets the current time.

TYPE

Displays the contents of the specified text file.

UNLOCK

Disables direct disk access.

VER

Displays the operating system version number.

VERIFY

Directs the operating system to verify that files are written correctly to a disk and displays the status of verification.

VOL

Displays the volume label and serial number for a disk.

Th e DOS extern al com m an d s are located in th e COMMAND su bfold er of th e m ain W in d ows 95/ 98 fold er. Table D.24 lists th e extern al DOS com m an d s th at sh ip with W in d ows 95/ 98. Table D.24

The W indow s 98 Ext ernal DOS Com m ands

Com m and

Descript ion

ATTRIB.EXE

Displays or changes the attributes of the specified files.

CHKDSK.EXE

Checks a disk for (and optionally repairs) lost and cross-linked clusters. ScanDisk does a better job at finding and repairing these errors.

CHOICE.COM

Used in batch files to present the user with a list of options.

COMMAND.COM

Starts a new instance of the command interpreter. This file is usually found in the root directory of the boot drive.

CSCRIPT.EXE

(Windows 98 only) Runs Windows Scripting Host scripts.

CVT.EXE

(Windows 95 OSR 2 and Windows 98 only) Converts FAT drives to FAT32.

DEBUG.EXE

Tests and edits executable files.

DELTREE.EXE

Deletes a folder and all its files and subfolders.

DISKCOPY.COM

M akes an exact copy of a floppy disk. (continues)

1415

1416

Appendix D—Technical Reference

Table D.24

The W indow s 98 Ext ernal DOS Com m ands Cont inued

Com m and

Descript ion

DOSKEY.COM

A memory-resident program that recalls commands, edits previous command lines, and runs macros.

EDIT.COM

Starts a text editor you can use to create and edit ASCII text files.

EXTRACT.EXE

(Windows 95/ 98 only) Extracts files from a compressed cabinet (CAB) file.

FC.EXE

Compares two files and displays the differences between them.

FDISK.EXE

Starts the FDISK utility.

FIND.EXE

Searches files for a specified text string.

FORMAT.COM

Formats a disk.

IEXTRACT.EXE

Extracts a file from an Internet Explorer backup information (DAT) file.

KEYB.COM

Configures a keyboard for a specific language.

LABEL.EXE

Creates or modifies the volume label of a disk.

MEM.EXE

Displays the amount of used and free memory on the computer.

MODE.COM

Configures a printer, serial port, or display adapter; sets the keyboard repeat rate; redirects printer output from a parallel port to a serial port; prepares, selects, refreshes, or displays the numbers of the character sets (code pages) for parallel printers or the keyboard and screen; and displays the status of all the devices installed on the computer.

MORE.COM

Pauses command output to display one screen at a time.

MOVE.EXE

M oves files and renames folders.

MSCDEX.EXE

Loads the real-mode CD-ROM driver.

NLSFUNC.EXE

Loads country-specific information for national language support.

SCANDISK.EXE

The real-mode version of ScanDisk.

SCANREG.EXE

(Windows 98 only) Scans the Registry for damage.

SORT.EXE

Reads input, sorts data, and writes the results to the screen, a file, or another device.

START.EXE

Enables you to set various parameters for running Windows programs from the DOS prompt.

SUBST.EXE

Substitutes a drive letter for a path name.

SYS.COM

Creates a bootable disk by copying Windows 98’s system files and COMMAND.COM to the disk.

XCOPY.EXE

The extended copy command.

XCOPY32.EXE

(Windows 95 and Windows 98 only) The 32-bit version of XCOPY.

DOS 6.22 Commands Not Inst alled by W indows 95/ 98 but Available on t he CD-ROM Microsoft d eleted q u ite a few DOS com m an d s wh en it p u t togeth er th e W in d ows 98 p ackage. Most of th ese com m an d s were eith er obsolete (su ch as EGA.SYS) or d an gerou s (su ch as RECOVER). Th ree of th ese com m an d s, h owever, can be fou n d on th e W in d ows 98 CD-ROM in th e \ TOOLS\ OLDMSDOS\ fold er. I’ve su m m arized th em in Table D.25.

DOS Command Reference

Table D.25

Old DOS Com m ands Available on t he W indow s 98 CD-ROM

Com m and

Descript ion

HELP.COM

Displays descriptions, syntax, and examples for all DOS commands. HELP.HLP is also available.

MSD.EXE

Runs the M icrosoft Diagnostics program used to gather system information for troubleshooting. Superseded by the System Information utility in Windows 98.

QBASIC.EXE

The programming environment for creating QBASIC applications. QBASIC.HLP is also available.

Table D.26 lists com m an d s th at were available in th e W in d ows 95 CD-ROM in th e \ OTHER\ OLDMSDOS fold er. Th ese were com m an d s th at were available in DOS 6.22 bu t were n ot in stalled by W in d ows 95 becau se th ey are obsolete. Table D.26

Old DOS Com m ands Available on t he W indow s 95 CD-ROM

Com m and

Descript ion

APPEND.EXE

Establishes a DOS search path for data files.

CHKSTATE.SYS

A device driver used by M emM aker to optimize memory use. You cannot use this driver.

EXPAND.EXE

Extracts a file from compressed format on the DOS distribution disks to a usable uncompressed form.

GRAPHICS.COM

Enables the Print Screen key to print the contents of a graphics screen on a suitable printer.

HELP.COM

Launches a full screen online help utility for the DOS commands.

INTERLNK.EXE

Client device driver for an InterLnk network.

INTERSVR.EXE

Server device driver for an InterLnk network.

LOADFIX.COM

Forces a program to load into the second 64K of memory.

MEMMAKER.EXE

Utility for optimizing memory usage by device drivers and other programs loaded by CONFIG.SYS and AUTOEXEC.BAT.

MSD.EXE

Runs the M icrosoft Diagnostics program used to gather system information for troubleshooting.

PRINT.EXE

Print spooler for ASCII text files.

QBASIC.EXE

Starts the M icrosoft QuickBASIC development environment, a program for writing and running BASIC language programs.

REPLACE.EXE

Replaces or adds files to a subdirectory.

RESTORE.EXE

Restores files created by the BACKUP program from one disk to another.

SIZER.EXE

A program used by M emM aker to optimize memory use. You cannot use this program.

TREE.EXE

Displays the subdirectory stricture of a disk.

UNDELETE.EXE

Undeletes a file or group of files.

DOS 6.22 Com m ands Not Available in W indow s 95 or W indow s 98 Fin ally, Table D.27 is a list of DOS 6.22 com m an d s th at are gon e for good an d won ’t be fou n d in eith er W in d ows 95 or W in d ows 98.

1417

1418

Appendix D—Technical Reference

Table D.27

DOS 6.22

Com m and

Descript ion

ASSIGN

In DOS 2–5, attached an alias drive letter to an existing drive. Replaced by SUBST in DOS 6 and later.

BACKUP

A utility to back up files from a hard disk to a series of floppy disks. Replaced by MSBACKUP in DOS 6 and with the GUI version of Backup for Windows 95 and Windows 98.

COMP

Compares two sets of disk files of the same name and same length. Included in DOS 1–5 but only on supplemental disk in DOS 6.

DOSSHELL

In DOS 4–6, a full screen menu driven shell for the DOS command line. Included only on the supplemental disk for DOS 6.2.

EDLIN

In DOS 1–5, edits an ASCII file, replaced by EDIT. Only on supplemental disk in DOS 6.

FASTHELP

Returns the same help information as including the /? switch with a DOS command.

FASTOPEN

A utility that sped up the process of opening files in DOS.

GRAFTABL

A DOS 3–5 utility for loading tables of additional character sets for CGA adapters. Only on the supplemental disk in DOS 6.

JOIN

In DOS 3.1–5, connects one drive to a subdirectory of another. Only on the supplemental disk in DOS 6.

MIRROR

In DOS 5, records information about the FAT, the root directory, and optionally the partition table which can be used by UNFORMAT and UNDELETE. Only on the supplemental disk in DOS 6.

MSAV

M icrosoft Anti-Virus for Windows 3.x.

MSBACKUP

M icrosoft Backup for Windows 3.x.

POWER

Controls use of APM in laptop systems and other APM -enabled systems.

RECOVER

A file recovery utility with DOS 2–5 that was not distributed with DOS 6 or later. Not recommended for use with any version.

SETVER

DOS version control program that reports a different DOS version number to programs requiring a specific version of DOS to run.

SHARE

File sharing and locking capabilities for DOS.

SMARTMON

SM ARTDrive monitoring and configuration program for Windows 3.x.

UNFORMAT

Recovers a disk that was accidentally formatted. Note that using the /U switch with the FORMAT command will prevent the UNFORMAT command from being able to recover the disk.

VSAFE

A memory resident utility that warns you of virus-like activity.

1419

List of Acronyms

A AAD (An alo g Align m en t Diskette) Accelerated Graph ics Port (AGP) Acer Laboratories, In c. (ALI) ACPI (Advanced Configuration and Pow er Interface) Adaptive Differen tial Pulse Code Modulation (ADPCM) ADCs (an alog-to-digital con verters) ADPCM (Adaptive Differen tial Pulse Code Modulation) Advanced Configuration and Pow er Interface (ACPI) Advan ced Micro Devices (AMD) Advan ced Pow er Man agem en t (APM) stan dard Advanced Program m able Interrupt Controller (APIC) Advan ced Run Len gth Lim ited (ARLL) Advan ced SCSI Program m in g In terface (ASPI) AGC (Auto m atic Gain Co n tro l) AGP (Accelerated Graph ics Port) ALI (Acer Laboratories In c.) AMD (Advan ced Micro Devices) an alo g-to -digital-co n verters (ADCs) AAD (An alo g Align m en t Diskette) APIC (Advan ced Program m able In terrupt Con troller) APM (Advan ced Po w er Man agem en t) stan dard ARLL (Advan ced Run Len gth Lim ited) ASPI (Advan ced SCSI Pro gram m in g In terface) AT Attach m en t Packet In terface (ATAPI) ATAPI (AT Attach m en t Packet In terface) Auto m atic Gain Co n tro l (AGC)

B BASIC (Begin n ers All-Purpose Sym bolic In struction ) Basic In put Output System (BIOS) Basic Rate In terface (BRI)

BBSs (bulletin bo ard system s) Begin n ers All-purpo se Sym bo lic In structio n Co de (BASIC) BiCMOS (Bipo lar Co m plem en tary Metal Ox ide Sem ico n ducto r) BIOS (Basic In put Output System ) BPI (bits per in ch ) bps (bits per seco n d) Bran ch Target Buffer (BTB) BRI (Basic Rate In terface) BSRAMs (Burst Static RAMs) BTB (Bran ch Target Buffer) bulletin board system s (BBSs) Burst Static RAMs (BSRAMs)

C Cable Select (CSEL) sign als Cach e On A Stick (COAST) CACP (Cen tral Arbitration Con trol Poin t) CAM ATA (Com m on Access Meth od AT Attach m en t) interface Can adian Stan dards Agen cy (CSA) Card Edge Low Profile (CELP) cath o de ray tubes (CRTs) CAV (Con stan t An gular Velocity) CBT (Com puter-Based Train in g) Con sultative Com m ittee on In tern ation al Teleph on e an d Telegraph (CCITT) CD-R (CD-Recordable) CD-RW (CD-Rew ritable) CELP (Card Edge Low Profile) Cen tral Arbitration Con trol Poin t (CACP) Cen tral Processin g Un its (CPUs) CGA (Co lo r Graph ics Adapter) ch aracters per secon d (cps) CHS (Cylin der Head Secto r)

1420

CISC (Complex Instruction Set Computer)

CISC (Co m plex In structio n Set Co m puter) CLKMUL (Clo ck Multiplier) CLV (Co n stan t Lin ear Velo city) CMOS (Co m plem en tary Metal Ox ide Sem ico n ducto r) CMOS RAM (Com plim en tary Metal-Ox ide Sem iconductor) COAST (Cach e On A Stick) Co lo r Graph ics Adapter (CGA) color super-tw ist n em atic (CSTN) Com m on Access Method AT Attachm ent (CAM ATA) interface Co m pact Video Co ded (CVC) Co m plex In structio n Set Co m puter (CISC) Com plim en tary Metal-Ox ide Sem icon ductor (CMOS) Com puCom Speed Protocol (CSP) Com puter-Based Train in g (CBT) Co n stan t An gular Velo city (CAV) Co n stan t Lin ear Velo city (CLV) Con sultative Com m ittee on In tern ation al Teleph on e an d Telegraph (CCITT) CP/ M (Con trol Program for Microprocessors) cps (ch aracters per secon d) CPUs (Cen tral Pro cessin g Un its) CRC (cyclic redun dan cy ch eck) CRTs (cath o de ray tubes) CSA (Can adian Stan dards Agen cy) CSEL (Cable Select) sign als CSP (Com puCom Speed Protocol) CSTN (color super-tw ist n em atic) CVC (Co m pact Video Co ded) cyclic redun dan cy ch eck (CRC) Cylin der Head Secto r (CHS)

D DAC (Digital to An alo g Co n verter) DASP sign als (Drive Active/ Slave Presen t) DAT (digital audio tape) db (decibels) DBB (dyn am ic bass bo o st) DBR (DOS Bo o t Reco rd) DCC (Direct Cable Co n n ectio n ) DDD (Digital Diagn o stic Diskette) DDMs (Digital Multi-Meters) DDR (Do uble Data Rate) decibels (db) Deskto p Man agem en t In terface (DMI) Deskto p Video (DTV) device-in depen den t bitm ap (DIB) DIB (Dual In depen den t Bus) digital audio tape (DAT) Digital Diagn o stic Diskette (DDD) digital lin ear tape (DLT)

Digital Mulit-Meter (DMM) Digital Sign al Pro cesso rs (DSPs) Digital to An alo g Co n verter (DAC) Digital Versatile Disc (DVD) Digital Vo lt Oh m Meters (DVOMs) Digital-to -An alo g Co n verter (RAMDAC) DIME (DIrect Mem o ry Ex ecute) DIMMs (Dual In lin e Mem o ry Mo dules) DIN (Deutsch e In dustrie No rm ) DIP (Dual In lin e Package) ch ips Direct Cable Co n n ectio n (DCC) Direct Mem o ry Access (DMA) DIrect Mem o ry Ex ecute (DIME) DIS (dyn am ic im pedan ce stabilizatio n ) Disk Operatin g System (DOS) Display Po w er-Man agem en t Sign alin g (DPMS) DLT (digital lin ear tape) DMA (Direct Mem o ry Access) DMI (Deskto p Man agem en t In terface) DMM (Digital Multi-Meter) DOS (Disk Operatin g System ) DOS Bo o t Reco rd (DBR) do ts per in ch (dpi) Do uble Data Rate (DDR) do uble-layer super-tw ist n em atic (DSTN) dpi (do ts per in ch ) DPMS (Display Po w er-Man agem en t Sign alin g) Drive Active/ Slave Presen t (DASP) DSPs (Digital Sign al Pro cesso rs) DSTN (do uble-layer super-tw ist n em atic) DTV (Deskto p Video bo ards) Dual In depen den t Bus (DIB) Dual In lin e Mem o ry Mo dules (DIMMs) DVD (Digital Versatile Disc) DVOM (Digital Multi-Meters) dyn am ic bass bo o st (DBB) dyn am ic im pedan ce stabilizatio n (DIS)

E ECC (Erro r Co rrectin g Co de) ECHS (Ex ten ded Cylin der Head Secto r) ECP (En h an ced Capabilities Po rts) EDC (Erro r Detectio n Co de) EDO (Ex ten ded Data Out) EDO DRAM (Ex ten ded Data Out DRAM) EDO m em o ry (Ex ten ded Data Out) EEPROM (Electrically Erasable Pro gram m able Read On ly Mem o ry) EGA (En h an ced Graph ics Adapter) EISA (Ex ten ded In dustry Stan dard Arch itecture) Electrically Erasable Program m able Read On ly Mem ory (EEPROM) electrostatic disch arge (ESD)

IRQs (Interrupt Requests)

1421

ELF (ex trem ely lo w frequen cy) EMS (Ex pan ded Mem o ry Specificatio n ) en co der/ deco der (en dec) en dec (en co der/ deco der) En h an ced Capabilities Po rts (ECP) En h an ced Graph ics Adapter (EGA) En h an ced Parallel Po rts (EPP) En h an ced Serial Po rts (ESP) En h an ced Sm all Device In terface (ESDI) EPIC (Ex plicitly Parallel In structio n Co m putin g) EPP (En h an ced Parallel Po rts) EPROM (Erasable Program m able Read On ly Mem ory) Erasable Program m able Read On ly Mem ory (EPROM) Erro r Co rrectin g Co de (ECC) Erro r Detectio n Co de (EDC) ESD (electrostatic disch arge) ESDI (En h an ced Sm all Device In terface) ESP (En h an ced Serial Ports) Ex plicitly Parallel In struction Com putin g (EPIC) Ex ten ded Cylin der Head Sector (ECHS) Ex ten ded Data Out (EDO) Ex ten ded Data Out DRAM (EDO DRAM) Ex ten ded Data Out m em o ry (EDO m em o ry) eXten ded Graph ics Array (XGA) Ex ten ded In dustry Stan dard Arch itecture (EISA)

G

F

iCOMP (In tel Co m parative Micro pro cesso r Perform ance) ICs (in tegrated circuits) IDE (In tegrated Drive Electron ics) IDE/ ATAPI (In tegrated Drive Electron ics/ AT Attachm ent) IDT (In tegrated Device Tech n ology) IML (In itial Microcode Load) In dustry Stan dard Arch itecture (ISA) In frared Data (IrDA) In itial Microcode Load (IML) in tegrated circuits (ICs) In tegrated Device Tech n ology (IDT) In tegrated Drive Electron ics (IDE) In tegrated Drive Electron ics/ AT Attach m en t Packet In tegrated Periph erals Con troller (IPC) In tegrated Services Digital Netw ork (ISDN) In tel Com parative Microprocessor Perform an ce (iCOMP) In tern ation al Organ ization for Standardization (ISO) in terrupt requests (IRQs) IPC (In tegrated Periph erals Con troller) IPL (In itial Program Load) ROM IrDA (In frared Data) IRQs (In terrupt Requests)

Failures in Tim e (FIT) Fast Page-Mo de RAM (FPM RAM) FAT (File Allocation Table) FCC (Federal Com m un ication s Com m ission ) FDDI (fiber distributed data in terface) FDIV (Floatin g Poin t Divide) Federal Com m un ication s Com m ission (FCC) fiber distributed data in terface (FDDI) FIFO (first in / first o ut) File Allocation Table (FAT) first in / first o ut (FIFO) FIT (Failures in Tim e) Floatin g Poin t Divide (FDIV) Flo atin g Po in t Un its (FPUs) FM (Frequen cy Modulation ) FPM DRAM (Fast Page-Mo de RAM) FPUs (Flo atin g Po in t Un its) Frequen cy Modulation (FM) frequen cy-sh ift keyin g (FSK) FSK (frequen cy-sh ift keyin g)

Gb (Gigabit) GB (Gigabyte) GUI (Graph ical User In terface)

H HAL (h ardw are abstractio n layer) h ard erro r rates (HERS) h ardw are abstractio n layer (HAL) HDAs (Head Disk Assem blies) Hercules Graph ics Card (HGC) HERS (h ard erro r rates) Hertz (Hz) HGC (Hercules Graph ics Card) h igh perform an ce addressin g (HPA) High -Level Fo rm attin g (HLF) High -Reso lutio n Diagn o stic Diskette (HRD) HLF (High -Level Fo rm attin g) HMA (High Mem o ry Area) HPA (h igh perfo rm an ce addressin g) HRD (High -Reso lutio n Diagn o stic Diskette) Hz (Hertz)

I-J

1422

ISA (Industry Standard Architecture)

ISA (In dustry Stan dard Arch itecture) ISDN (In tegrated Services Digital Netw o rk) ISO (In tern atio n al Organ izatio n fo r Stan dardizatio n ) JPEG (Jo in t Ph o to graph ic Ex perts Gro up)

K-L Kb (Kilo bit) KB (Kilo byte) lan din g zo n e (LZ) LANs (lo cal area n etw o rks) LAPM (Lin k Access Pro cedure fo r Mo dem s) LBA (Lo gical Blo ck Addressin g) LCDs (liquid crystal displays) LEDs (Ligh t Em ittin g Dio des) LIF (Lo w In sertio n Fo rce) Ligh t Em ittin g Dio des (LEDs) LIM (Lo tus In tel Micro so ft) Lin k Access Procedure for Modem s (LAPM) liquid crystal displays (LCDs) LLC (Logical Lin k Con trol) LLF (Low -Level Form attin g) local area n etw orks (LANs) Logical Block Addressin g (LBA) Logical Lin k Con trol (LLC) Lo tus In tel Micro so ft (LIM) Lo w In sertio n Fo rce (LIF) Low -Level Form attin g (LLF) LZ (lan din g zon e)

m etal-o x ide varisto rs (MOVs) MFM (Mo dified Frequen cy Mo dulatio n ) MFT (Master File Table) MHZ (Megah ertz) Micro Ch an n el Arch itecture (MCA bus) Micro co m Netw o rkin g Pro to co l (MNP) Micro so ft CD-ROM Ex ten sio n s (MSCDEX) Micro so ft Diagn o stics (MSD) Micro so ft Video fo r Win do w s (VFW) MIDI (Musical In strum en t Digital In terface) MIG (Metal-In -Gap) MMU (Mem o ry Man agem en t Un it) MMX (MultiMedia eXten sio n ) MNP (Micro co m Netw o rkin g Pro to co l) m o dem (m o dulato r/ dem o dulato r) Mo dified Frequen cy Mo dulatio n (MFM) m o dulato r/ dem o dulato r (m o dem ) Mo n o ch ro m e Display Adapter (MDA) Mo tio n Pictures Ex pert Gro up (MPEG) MOVs (m etal-ox ide varistors) MPC (Multim edia PC) MPEG (Motion Pictures Ex pert Group) MPS (Multi-Processor Specification ) MSCDEX (Microsoft CD-ROM Ex ten sion s) MSD (Microsoft Diagn ostics) MTBF (Mean Tim e Betw een Failures) Multi-Ch ip Mo dule (MCM) Multi-Processor Specification (MPS) Multiban k DRAM (MDRAM) MultiColor Graph ics Array (MCGA) MultiMedia eXten sion (MMX) Multim edia PC (MPC) Musical In strum en t Digital In terface (MIDI)

M MAC (Media Access Co n tro l) Master Bo o t Reco rd (MBR) Master Bo o t Secto r (MBS) Master File Table (MFT) Mb (Megabit) MB (Megabyte) Mbps (m egabits per seco n d) MBR (Master Bo o t Reco rd) MBS (Master Bo o t Secto r) MCA (Micro Ch an n el Arch itecture) MCGA (MultiColor Graph ics Array) MCM (Multi-Ch ip Mo dule) MDA (Mon och rom e Display Adapter) MDRAM (Multiban k DRAM) Mean Tim e Betw een Failures (MTBF) Media Access Co n tro l (MAC) Megabit (Mb) m egabits per seco n d (Mbps) Megabyte (MB) Mem o ry Man agem en t Un it (MMU) Metal-In -Gap (MIG)

N Nation al Television System Com m ittee (NTSC) NDP (n um eric data processor) NFAS (Non -Facility Associated Sign alin g) NMI (n on -m askable in terrupt) Non -Facility Associated Sign alin g (NFAS) Non -Volatile RAM (NVRAM) NTSC (Nation al Television System Com m ittee) n um eric data processor (NDP) NVRAM (Non -Volatile RAM)

O Object Lin kin g an d Em beddin g (OLE) OEM Service Release (OSR) OEMs (Origin al Equipm en t Man ufacturers) OLE (Object Lin kin g an d Em beddin g) On e Tim e Program m able (OTP) Open System s In tercon n ection (OSI)

SVGA (Super VGA)

Origin al Equipm en t Man ufacturers (OEMs) OSI (Open System s In terco n n ectio n ) OSR (OEM Service Release ) OTP (On e Tim e Pro gram m able)

P Page Descriptio n Lan guage (PDL) pages per m in ute (ppm ) PAL (Ph ase Altern ate Lin e) PARD (Perio dic an d Ran do m Deviatio n ) Partial-Respo n se, Max im um -Likelih o o d (PRML) PCI (Periph eral Co m po n en t In terco n n ect) PCI ISA IDE Xcelerato r (PIIX) ch ips PCL (Prin ter Co n tro l Lan guage) PDL (Page Descriptio n Lan guage) Perio dic an d Ran do m Deviatio n (PARD) Periph eral Co m po n en t In terco n n ect (PCI) PGA (Pin Grid Array) PGA (Profession al Graph ics Adapter) Ph ase Altern ate Lin e (PAL) ph ase-sh ift keyin g (PSK) PIIX ch ips (PCI ISA IDE Xcelerato r) Pin Grid Array (PGA) PJL (Prin ter Job Lan guage) Plastic Quad Flat Pack (PQFQ) Pn P (Plug an d Play) POST (Po w er On Self Test) PostScript Prin ter Description s (PPDs) Po w er On Self-Test (POST) po w er supply un it (PSU) Po w er-On Self Test (POST) PPDs (PostScript Prin ter Description s) PPI (Program m able Periph eral In terface) ppm (pages per m in ute) PQFP (Plastic Quad Flat Pack) PRI (Prim ary Rate In terface) Prin ter Con trol Lan guage (PCL) Prin ter Job Lan guage (PJL) PRML (Partial-Respon se Max im um -Likelih ood) Profession al Graph ics Adapter (PGA) PROM (Program m able ROM) PSK (ph ase-sh ift keyin g) PSTN (Public Sw itch ed Teleph on e Netw ork) PSU (po w er supply un it) Public Sw itch ed Teleph on e Netw ork (PSTN)

Q-R QAM (quadrature-am plitude m o dulatio n ) QIC (Quarter-In ch Co m m ittee) radio -frequen cy in terferen ce (RFI) RAID (Redun dan t Array o f In ex pen sive Disks) RAM (Ran do m Access Mem o ry)

1423

RAMDAC (Digital-to -An alo g Co n verter) raster o utput scan n er (ROS) RDRAM (Ram bus Dyn am ic RAM) Read On ly Mem o ry (ROM) Real Tim e Clo ck (RTC) Reduced In structio n Set Co m puter (RISC) Redun dan t Array o f In ex pen sive Disks (RAID) RET (Reso lutio n En h an cem en t Tech n o lo gy) RFI (radio -frequen cy in terferen ce) RIMMs (Ram bus In lin e Mem o ry Mo dules) RISC (Reduced In structio n Set Co m puter) RLL (Run Len gth Lim ited)ROM (Read On ly Mem o ry) ro o m -tem perature vulcan izin g (RTV) ROS (raster o utput scan n er) RTC (Real Tim e Clo ck) RTV (ro o m -tem perature vulcan izin g) Run Len gth Lim ited (RLL)

S SBIC (SCSI Bus Adapter Ch ip) SDL (Sh ielded Data Lin k) SDRAM (Syn ch ron ous Dyn am ic RAM) SEC (Sin gle Edge Cartridge) SECAM (SEquen tial Couleur Avec Mem oire) SERS (so ft erro r rates) SEUs (sin gle even t upsets) SGRAM (Syn ch ron ous Graph ics DRAM) Sh ielded Data Lin k (SDL) sh ielded tw isted pair (STP) Silicon In tegrated System s (SIS) SIMD (Sin gle In struction Multiple Data) SIMMs (Sin gle In lin e Mem o ry Mo dules) Sin gle Edge Cartridge (SEC) sin gle even t upsets (SEUS) Sin gle In lin e Mem o ry Mo dules (SIMMs) Sin gle In lin e Pin Package (SIPP) Sin gle In struction Multiple Data (SIMD) SIPPs (Sin gle In lin e Pin Package) SIS (Silicon In tegrated System s) Sm all Quad Flat Pack (SQFQ) SMI (System Man agem en t In terrupt) SMM (System Man agem en t Mode) so ft erro r rates (SERS) SPGA (Staggered Pin Grid Array) Spin dle Syn ch ron ization (SPSYNC) sign als SPS (Stan dby Pow er Supplies) SPSYNC (Spin dle Syn ch ron ization ) sign als SQFP (Sm all Quad Flat Pack) SRAM (Static RAM) Staggered Pin Grid Array (SPGA) Stan dby Pow er Supplies (SPS) STP (sh ielded tw isted pair) SVGA (Super VGA)

1424

Synchronous Dynamic RAM (SDRAM )

Syn ch ro n o us Dyn am ic RAM (SDRAM) Syn ch ro n o us Graph ics DRAM (SGRAM) System Man agem en t In terrupt (SMI) System Man agem en t Mo de (SMM)

T TAB (tape auto m ated bo n din g) tape auto m ated bo n din g (TAB) tape carrier packagin g (TCP) Tb (Terabit) TB (Terabyte) TCP (tape carrier packagin g) TCQAM (trellis co ded quadrature am plitude m o dulatio n ) Terabit (Tb) Terabyte (TB) TFT (th in -film tran sisto rs) THD (To tal Harm o n ic Disto rtio n ) th in -film tran sisto rs (TFT) TLB (Tran slation Lookaside Buffer) Total Harm on ic Distortion (THD) TPI (tracks per in ch ) Tran slation Lookaside Buffer (TLB) trellis coded quadrature am plitude m odulation (TCQAM)

U UART (Un iversal Asyn ch ron ous Receiver/ Transm itter) UL (Un derw riters Labratories, In c.) Ultra VGA (UVGA) UMA (Upper Mem o ry Area) UMB (Upper Mem ory Block) Un derw riters Laboratories In c. (UL) Un in terruptable Pow er Supplies (UPS) Un iversal Asyn ch ron ous Receive/ Tran sm itter (UART) Un iversal Periph eral In terface (UPI) Un iversal Serial Bus (USB) un sh ielded tw isted pair (UTP) UPI (Un iversal Periph eral In terface) Upper Mem o ry Area (UMA) Upper Mem o ry Blo ck (UMB) UPS (Un in terruptable Po w er Supplies)

USB (Un iversal Serial Bus) UTP (un sh ielded tw isted pair) UVGA (Ultra VGA)

V VAFC (VESA Advan ced Feature Co n n ecto r) Very Large Scale In tegratio n (VLSI) Very Lo n g In structio n Wo rds (VLIW) very lo w frequen cy (VLF) VESA (Video Electro n ics Stan dards Asso ciatio n ) VESA Advan ced Feature Co n n ecto r (VAFC) VESA Media Ch an n el (VMC) VFAT (Virtual File Allocation Table) VFC (Video Feature Co n n ecto r) VFW (Micro so ft Video fo r Win do w s) VGA (Video Graph ics Array) VID (Voltage Iden tification ) Video Electron ics Stan dards Association (VESA) Video Graph ics Array (VGA) video RAM (VRAM) Virtual File Allocation Table (VFAT) VLF (very low frequen cy) VLIW (Very Lo n g In structio n Wo rds) VLSI (Very Large Scale In tegration ) VMC (VESA Media Ch an n el) Voltage Iden tification s (VID) Voltage Reduction Tech n ology (VRT) Voltage Regulator Module (VRM) Vo lum e o f Table o f Co n ten ts (VTOC) VRAM (video RAM) VRM (Voltage Regulator Module) VRT (Voltage Reduction Tech n ology) VTOC (Vo lum e Table o f Co n ten ts)

W-Z w h at yo u see is w h at yo u get (WYSIWYG) Win dow RAM (WRAM) WORM (w rite on ce/ read m an y) WRAM (Win dow RAM) WYSIWYG (w h at yo u see is w h at yo u get) XGA (eXten ded Graph ics Array) XMS (ex ten ded m em ory specification ) ZIF (Zero In sertio n Fo rce)

1425

Index of Manufacturers

Symbols 3COM, 669 3D Labs, 1178 3Dfx , 1178 3M Data Sto rage Pro ducts Divisio n , 1179

A Aavid Th erm al Tech n ologies, In c., 1179 ABIT Co m puter (USA) Co rpo ratio n , 1179 Accurite Tech n ologies In c., 1179 Acer Am erica Co rp., 1179 Acer Labo rato ries In c., 184, 197-198, 532, 1179 Acm e Electric/ Electron ics Division , 1179 Adaptec, In c., 605, 654, 833, 990, 1180 AdLib, 549-550, 563 Ado be System s, In c., 874-875, 1180 Advan ced Digital In form ation Corporation , 1180 Advan ced In tegration Research (AIR), 1180 Advan ced Logic Research (ALR), 1180 Advan ced Micro Devices (AMD), 1181 Advan ced Person al System s, 1181 Aero n ics, In c., 1181 Allied, 409 AllMicro , In c., 1181 Alloy Co m puter Pro ducts, 1181 Alps Electric, 449, 455, 473, 495, 1181 Altex Electro n ics, In c., 1182 AMD (Advan ced Micro Devices), 48, 80, 82, 153-155 Am dek Corporation , 1182 Am erica On lin e, 1182 Am erican Megatren ds, In c., 1182 Am erican Po w er Co n version (APC), 1182 AMI (Am erican Megatren ds, In c.), 17, 992 AMP, In c., 103, 341, 1182

An dro m eda Research , 308, 1183 An n abooks, 1183 An n asoft System s, 479 An vil Cases, 1183 APC (Am erican Pow er Con version ), 441 Apple Co m puter, In c., 480, 542, 932, 1183 Arco Co m puter Pro ducts, In c., 1183 Areal Tech n ology, 734 Arrow Electron ic, 1183 Arrow field In tern ation al, In c., 1183 AST Research , In c., 1184 Astec Am erica In c., 434, 1184 Asus Com puter In tern ation al (ASUStek), 1184 ATI Tech n o lo gies, In c., 1184 Auto desk, In c., 1184 Autotim e Corporation , 1185 Aw ard Softw are In tern ation al, In c., 17, 1185 AZ-COM, In c., 1185

B BAPco (Stan dard Perform an ce Evaluation Corporation ), 165 Belden Wire an d Cable, 1185 Berksh ire Pro ducts, 1185 Bern o ulli, 799 Best Po w er, 441, 1185 Bitstream , In c., 1185 Black Bo x Co rpo ratio n , 1186 Bo ca Research , In c., 1186 Bo rlan d In tern atio n al, 1186 Bo se Co rp., 1186 Bo sto n Co m puter Ex ch an ge, 1186 Bro o ktree Co rpo ratio n , 1186 Buerg, Vern o n D., 1186 Busin ess Applicatio n s Perfo rm an ce Corporation , 165

1426

Byte Information Exchange (BIX)

Byte In fo rm atio n Ex ch an ge (BIX), 1186 Byt e Ma ga zine/ McGraw Hill, 1187 Byte Run n er Tech n o lo gies, 1187

C Cables to Go , 1187 CAIG Laboratories, 1187 Cal-Abco, 1187 Can o n USA, In c., 1187 Casio , In c., 1187 Cen taur Tech n o lo gy, 82, 126 Cen to n Electro n ics, In c., 1187 Ch em tro n ics, In c., 1019, 1188 Ch erry Electrical Products, 1188 Ch icago Case Co m pan y, 1188 Ch in o n Am erica, In c., 1188 Ch ips an d Tech n o lo gies, In c., 184, 1188 CI Design Co m pan y, 1188 CIE Am erica, 1189 Cirrus Lo gic, In c., 572, 1189 Citizen Am erica Corporation , 1189 CMD Tech n o lo gy, In c., 1189 Co lo rado Mem o ry System s, In c., 1189 Colum bia Data Products, 1189 Co m paq, 19, 1004, 1189 Co m pto n ’s New Media, In c., 1190 Co m pUSA, In c., 1190 Com puServe In form ation Service (CIS), 1190 Co m puter Co m po n en t So urce, In c., 1190 Com put er Design Magazine, 1190 Co m puter Disco un t Wareh o use (CDW), 1190 Com puter Graphics W orld Magazine, 1190 Com puter Hotline Magazine, 1191 Com puter Library, 1191 Com puter Reseller News Magazine, 19, 1191 Com puter Retail W eek Magazine, 1191 Com put er Shopper Magazine, 19, 1191 Com puter Technology Review Magazine, 1191 Co m tech Publish in g Ltd., 1191 Co n n ecto r Reso urces Un lim ited (CRU), 1192 Co n n er Periph erals, In c., 1192, 1355-1357 Co rel System s, In c., 1192 Creative Labs, In c., 549-550, 563, 571, 1192 CS Electro n ics, 1192 CST, 1192 CTX In tern atio n al, In c., 1192 Curtis Co m puter Pro ducts, 1004, 1193 CyberMedia, 1193 Cypress Sem icon ductor Corporation , 1193 Cyrix Co rpo ratio n , 48, 82, 155-157, 500, 1193

D D.W. Electro ch em icals, 1017, 1193 Da-Lite Screen Co ., 1193 DakTech , 494, 1193 Dallas Sem icon ductor, 1193 Dam ark In tern ation al, In c., 1194 Darkh orse System s, 1194 Dat a Base Advisor Magazine, 1194 Data Com m unications Magazine, 1194 Data Depo t, 77, 989, 1194 Data Ex ch an ge Corporation , 1194 Data Retrieval Services, In c., 1195 Data Tech n o lo gy Co rpo ratio n (DTC), 1195 Datapoin t Corporation , 700 Datastorm Tech n ologies, In c., 1195 Dell Co m puter Co rpo ratio n , 19, 984, 1195 DiagSo ft, In c., 77, 994, 1195 Diam o n d Flo w er, In c. (DFI), 1195 Diam on d Multim edia System s, In c., 1196 Digi-Key Co rpo ratio n , 409, 1196 Digital Equipm en t Corporation , 448 Disn ey, 853 Distributed Processin g Tech . (DPT), 1196 Diversified Tech n ology, 1196 Do lch Co m puter System s, 1196 Do w Co rn in g, 733 DTK Co m puter, In c., 1196 Dukan e Corporation , 1196 Duracell, In c., 1197

E Edm un d Scien tific, 1197 Electrocution , 1197 Electronic Buyers’ N ews Magazine, 1 1 9 7 Electronic Engineering Tim es Magazine, 1197 Electronic Products Magazine, 1197 Electroservice Laboratories, 1197 Elitegroup Com puter System s, In c., 1198 En dl Publication s, 1198 En so n iq, 555, 568 Epso n Am erica, In c., 1198 Erso , 184 Everex System s, In c., 1198 Evergreen , 103 Ex abyte Corporation , 1198 Ex tron Electron ics, 1198

M axi Switch, Inc.

F Fan tasy Pro ductio n s, 1198 FCI Electro n ics - Am ericas, 1199 Fedco Electro n ics, In c., 1199 Fessen den Tech n ologies, 1199 First In tern atio n al Co m puter, In c. (FIC), 1199 Fluke, Jo h n Man ufacturin g Com pan y, In c., 1199 Fo lio Co rpo ratio n , 1199 Fo reFro n t Direct, 989 Fo x , 853 Future Dom ain Corporation , 1200

G Gatew ay 2000, 19, 473, 479, 1200 Gazelle/ GTM Softw are, 1200 Giga-Byte Tech n o lo gy Co ., Ltd., 1200 GigaTren d, In c., 1200 Global En gin eerin g Docum en ts, 1200 Globe Man ufacturin g, In c., 1201 Go lden Bo w System s, 1201 Go ldStar Tech n o lo gy, In c., 1201 Gran d Jun ctio n Co rp., 704 GSI, In c., 1201

H Hauppauge Co m puter Works, In c., 1201 Hayes Microcom puter Products, 1201 Heath kit Education System s, 1202 Hew lett-Packard Co m pan y, 159, 550, 734, 854, 984, 1202 Hitach i Am erica, Ltd., 837, 1202 Hypertech , 1202 Hyun dai Electron ics Am erica, 1203

I IBM Co rpo ratio n , 15- 17, 449, 476, 511, 932, 984, 1357-1365 IBM Fulfillm en t Cen ter, 1203 IBM Micro electro n ics, 52, 82, 1203 IBM Nation al Publication s, 1203 IBM OEM Divisio n , 1203 IBM Parts Order Cen ter, 1203 IBM PC Co m pan y, 1203 IBM PC Direct, 1203 IDT, 126 Illin o is Lo ck, 1204 Im atio n , 798 Im m ersio n Co rp., 496 In fo rm atio n Access Co m pan y, 1204

1427

InfoW orld Ma ga zine, 1204 In lin e, In c., 1204 In n erw orks Tech n ology, In c., 1204 In tegrated Device Tech n ology, In c., 1204 In tel, 60, 197, 1204 Io m ega Co rpo ratio n , 799, 961, 1012-1013, 1205 IX Micro So lutio n s, In c., 1205

J J. Bo n d Co m puter System s, 1205 Jam eco Com puter Products, 1205 JC Wh itn ey & Co m pan y, 1205 JDR Microdevices, 1205 Jen sen To o ls, In c., 432, 1206 JTS Corporation , 1206 JVC In form ation Products, 1206

K Key Tro n ic Co rpo ratio n , 451, 455, 1206 Kin gsto n Tech n o lo gy Co rpo ratio n , 103, 1206 Ko dak, 843-844, 846

L Labcon co Corporation , 1206 Labtec En terprises, In c., 1206 Lan tron ix , 1207 Laser Magn etic Storage, 1207 Lava Co m puter Mfg., 589 Learn in g Com pan y, 1230 Learn Key, In c., 1207 Lex m ark, 451, 473, 476, 478, 1207 Liebert, 1207 Lite-On , 473 Liuski In tern ation al, 1207 Logitech , 481 Lon gsh in e Microsystem s, In c., 1207 Lotus Developm en t Corporation , 1208 LSI Lo gic, In c., 1208

M Ma Labo rato ries, In c., 1208 Macw orld Com m un ication s In c., 1208 MAG In n o Visio n , 1208 MAGNI System s, In c., 1208 MapIn fo Corporation , 1208 Matro x Graph ics In c., 1208 Matsush ita-Ko to buki In dustries, Ltd., 798 Max ell Co rpo ratio n o f Am erica, 1209 Max i Sw itch , In c., 473, 479, 1209

1428

M axoptix Corporation

Max o ptix Co rpo ratio n , 1209 Max to r Co rpo ratio n , 734, 1209, 1365- 1372 McAfee Associates, 1209 McKen zie Tech n ology, 1209 MediaVision , 541 Megah ertz Corporation , 1209 Mem Co r, 733 Merisel, 1210 Meritec, 1210 Merritt Co m puter Pro ducts, In c., 1210 Meth o de Electro n ics, In c., 1210 Micro 2000, In c., 77, 989, 993, 1210 Micro Accesso ries, In c., 1210 Micro Ch an n el Develo pers Association , 1210 Micro Co m puter Cable Co m pan y, In c., 1211 Micro Design In tern atio n al (MDI), 1211 Micro Firm w are, In c., 1211 Micro House In tern ation al, 1211 Micro In dustries Corporation , 1211 Micro So lutio n s, In c., 1211-1212 Micro Wareh o use, 1212 Micro-Star In tern ation al, 1213 Micro co m , In c., 1212 Micrografx , In c., 1212 Microid Research , 17 Micro n Tech n o lo gies, 19, 1212 Micro n ics Co m puters, In c., 1212 Micropolis Corporation , 1213 Microprocessors Un lim ited, In c., 1213 Micro so ft Co rpo ratio n , 16, 473, 481, 560, 942, 1213 MicroSystem s Developm en t, In c., 1213 Microtest En terprises, 1213 Micro Way, In c., 1213 Min i Micro Supply, 1214 Mitsubish i Co m puters, Ltd., 511, 1214 Mitsubish i Electron ics Am erica, In c., 1214 Mitsum i Electron ics Corporation , 1214 Mo lex In c., 1214 Mo sel Vitelic, 1214 Mo Sys In c., 530 Motor Magazine, 1214 Mo to ro la, In c., 1215 Mo un tain Netw o rk So lutio n s, In c., 1215 Mustan g Softw are, 1215 Mylex Corporation , 1215 Myo da Co m puter Cen ters, 1215

N Nation al Sem icon ductor Corporation , 81, 1215 NCR Microelectron ics, 1216 NEC Electro n ics, In c., 511, 1216 NEC Tech n o lo gies, In c., 1216 New ark Electron ics, 409, 1216

Nex Gen , In c., 152-153, 1216 NMB Tech n o lo gies, 455, 473 No vell, In c., 1216 NS (Natio n al Sem ico n ducto r), 588 Num ber Nin e Visual Tech n ology Corporation , 1216 n Vidia Corporation , 1217

O Oak Tech n o lo gy, In c., 1217 Ocean In form ation System s, 1217 OEM Magazine, 1217 Okidata, 1217 Olivetti, 1217 On track Data In tern atio n al, In c., 619, 1217 Opti, In c.,184, 1217 O.R. Tech n o lo gy, 798 Orch id Tech n o lo gy, 1218

P Pacific Data Products, 1218 Packard Bell, 19, 1218 Palo Alto Design Gro up, 1218 Pan ason ic Com m un ication s & System s, 1218 Pan aso n ic In dustrial Co ., 963, 1218 Parallel Tech n o lo gies, In c., 597, 1218 Param oun t, 853 PARTS NOW!, In c., 1219 PC & MAC Co n n ectio n , 1219 PC Magazine, 1219 PC Portable Man ufacturer In c., 1219 PC Po w er an d Co o lin g, 434 PC W orld Magazine, 1219 PCI Special In terest Gro up, 1220 Ph ilips Co n sum er Electro n ics, 824, 839, 844, 850-851, 1220 Ph o en ix Tech n o lo gies, Ltd., 17, 1220 Pion eer, 854 Pivar Co m putin g Services, In c., 1220 PKWare, In c., 1220 Plex tor, 1221 PlugIn Datam ation , 1221 Plus Develo pm en t Divisio n , 612 Pow erQuest Corporation , 1086, 1221 Practical En h an ced Logic, 1221 Precision Plastics, 1221 Processor Magazine, 1221 Public Softw are Library, 1221

UNISYS

Q Qlo gic Co rpo ratio n , 1222 Qualitas, In c., 1222 Quan tum Co rpo ratio n , 1222, 1372-1378 Quarter-In ch Cartridge Drive Stan dards, In c. (QIC), 1222 Quarterdeck Corporation , 1222 Que Co rpo ratio n , 1222

R Radio Sh ack, 1222 Ram bus, 318 Ram tron In tern ation al Corporation , 1223 Ran ch o Tech n o lo gy, In c., 1223 RealNetw orks, 560 Ren dition , 1223 Rip-Tie Com pan y, 1223 Rockw ell Sem icon ductor System s, 1223 Ro lan d Co rpo ratio n U.S., 549, 1223 Rosen th al En gin eerin g, 1223 Rupp Tech n ology Corporation , 1224

S S3 In c., 1224 Safew are In suran ce Agen cy, In c., 1224 Sam s, 1224 Sam sun g Sem ico n ducto r, In c., 530, 1224 Seagate Softw are, 1224 Seagate Softw are Storage Man agem en t Gro up, 1224 Seagate Tech n o lo gy, In c., 607- 608, 734, 737, 771, 1225, 1378-1394 Sen core, 1225 Service New s Magazine, 1225 SGS-Th o m so n Micro electro n ics, In c., 82, 1225 Sh arp Electron ics Corporation , 1225 Sh arp Microelectron ics Group, 1225 Sh ugart Associates, 771 Sigm a Data, 1226 Silico n In tegrated System s Co rp. (SIS), 198-199, 1226 Silicon Valley Research , 1226 Sim ple Tech n ology, 1226 SL Waber, 1226 Sm art Cable In c., 1226 SMC Netw o rks, In c., 990, 1228 So fTo uch System s, In c., 1226 So la Heavy Duty Electric, 1227 SONERA Tech n ologies, 1227

1429

So n y, 511, 812, 824, 839, 844, 851, 1227 SOYO Tek In c., 1227 Specialized Pro ducts Co m pan y, 432, 1004 Sprague Magn etics, In c., 1227 Stac In co rpo rated, 1227 Stacker Co rpo ratio n , 1040 Stan dard Microsystem s Corporation (SMSC), 1228 Star Micro n ics Am erica, In c., 1228 STB System s, In c., 1228 Sto rage Dim en sio n s, In c., 1228 Sun Mo o n Star, 1228 Sun tac, 184 Superm icro Com puter, In c., 1228 Superpow er Supply, In c., 1228 Sym an tec Co rpo ratio n , 77, 165, 1094, 1229 Sym ph on y, 184 SyQuest Tech n o lo gy, 796, 962, 1229

T Tadiran , 1229 Tan dy Corporation , 1229 Tatun g Co m pan y o f Am erica, In c., 1229 TDK Co rpo ratio n o f Am erica, 1229 Teac Am erica, In c., 961, 1229 Tech Data Co rpo ratio n , 1230 Tech Spray In c., 1230 Tekran Tech n ologies, In c., 1230 Test and Measurem ent W orld Magazine, 1230 Tex as In strum en ts In c., 306, 448, 605, 669, 1230 Th erm alloy In c., 1231 To sh iba In c., 494, 734, 932, 942, 1231, 1394-1397 Touch ston e Softw are Corporation , 992, 1231 Trace Research an d Develo pm en t Cen ter, 1231 Travelin g Softw are, In c., 1231 Triden t Microsystem s, 1231 Trin iTech , In c., 77, 989, 1232 Tripp Lite Man ufacturin g, 441, 1232 TTI Tech n ologies, 1232 Tw in h ead Corporation , 1232 Tyan Com puter Corporation , 1232

U U.S. Ro bo tics, In c., 1233 Ultra-X In c., 989, 1232 UMC, 184 Un derw riters Laboratories, In c., 1232 Un ico m p, In c., 451, 476-479, 1233 Un icore Softw are, In c., 1232 UNISYS, 1233

1430

V Communications, Inc.

V V Co m m un icatio n s, In c., 1233 Varta Batteries, In c., 1233 Verbatim Co rpo ratio n , 1233 VESA Stan dards, 1234 VIA Tech n o lo gies, In c., 194-197, 532, 1234 Video Lo gic, 572 View So n ic, 511, 1234 Visiflex Seels, 1234 VLSI Tech n o lo gy, In c., 184, 1234 VocalTec, 560 Vo lpe, Han k, 1234

W Wallin g Co m pan y, 1234 Wan g Laboratories, In c., 1234 Watergate Softw are, 1235 Wave Tech , 1235 Weitek, 90 Western Digital Co rpo ratio n , 614, 647-648, 650, 1235, 1397-1400 Win bon d, 1235 Win dsor Tech n ologies, 994 WordPerfect, 1235 Wyse Tech n o lo gy, 1235

X Xero x Co rpo ratio n , 480, 1235 Xirco m , 1235

Y–Z Y-E Data Am erica, In c., 1236 ZD Co m dex an d Fo rum s, 1236 Zen ith Data System s, 1236 Zeo s In tern atio n al, Ltd., 1236 Ziff-Davis, 165

1431

Index

Sym bols 1/ 8-in ch m in ijack co n n ecto rs (so un d cards), 565 .25 m icro n CPU m an ufacturin g (m o bile Pen tium s), 918-920 .35 m icro n m an ufacturin g (CPUs), 51-52, 919-920 2/ 3-ch ip SIMMs, 328 #1-TuffTEST diagn o stic so ftw are, 994 1,1,1 trich lo ro eth an e (clean ers), 1015 1.2M 5 1/ 4-in ch flo ppy drives, 786-787, 961 1.44M 3 1/ 2-in ch flo ppy drives, 783, 961 1.8v (m o bile Pen tium steppin gs), 124 2-w ay pro cessin g, see dual pro cessin g; m ultipro cessin g 2-Way Set Asso ciative cach e (Pen tium CPUs), 105 2.0v (m o bile Pen tium steppin gs), 124 2.285v (m o bile Pen tium steppin gs), 123 2.2v (m o bile Pen tium steppin gs), 124 2.88M 3 1-in ch flo ppy drives, 784-787, 961 3 1/ 2 in ch flo ppy disk drives, 779-780, 961 1.44M, 783 2.88M, 784-785 720K, 785-786 3-w ire n ull m o dem cable pin o uts, 676 3.3v vo ltage settin g (Pen tium CPUs), 391-392 OverDrive p rocessors, 60 VR (voltage red u ced ), 72

3.5v vo ltage settin g (Pen tium CPUs), 72 3COM 3C509B n etw o rk in terface cards (diagn o stic so ftw are), 990 3D graph ics accelerato rs, 543 ch ip sets, 543-545 cost, 544 im age abstraction s p rim itives, 544 textu res, 544 vertices, 544 ren d erin g, 544-545 geom etry, 544 rasterization , 544 ren d erin g im ages, 543 keyfram es, 543 sh ad in g, 543 textu re m ap p in g, 543 3D Win Ben ch 98 ben ch m ark, 165 4-bit un idirectio n al parallel po rts, 594-595 4-pin co n n ecto rs, 403-405 4-w ay pro cessin g, see dual pro cessin g; m ultipro cessin g 4-w ay set asso ciative cach e, 42 +5v po w er so urces, 391-392 5v vo ltage settin g (Pen tium CPUs), 72 5v_Stan dby (po w er supply), 401 5 1/ 4-in ch flo ppy disk drives, 779-780, 961 1.2M, 786-787 360K, 787 5-pin DIN co n n ecto rs AT m oth erboard s, 168 keyboard , 471 MIDI p orts, 555

6-pin co n n ecto rs, 403-405 ATX op tion al, 405-406 6-pin m in -DIN co n n ecto rs (PS/ 2 type), 169, 471 6x 86 CPUs (Cyrix ), 81, 156-158 PR (Perform an ce Ratin g), 37 sp eed s, 157-158 8-bit audio , 564 8-bit bidirectio n al parallel po rts, 595 8-bit co lo r, 528 VGA, 518 8-bit CPUs 80186, 84 80188, 84 8088, 83 IBM PC, 84 sp eed s, 84 8-bit ISA bus, 240, 272 , 275 8-bit system s (PC/ XT class), 23-24 8-bit XT bus, IDE (In tegrated Drive Electro n ics), 626 8-in ch drives, 732-733 8m m tape drives, 814 8.3 alias n am es (lo n g file n am es), 1081 8.3 file n am es, assign in g in VFAT, 1081 8-ch ip SIMMs, 328 9-pin do t m atrix prin ters, 872 9-pin serial-po rt co n n ecto rs, 584-587 10BaseT, see UTP 11-w ire n ull m o dem cable pin o uts, 676 12-bit FATs, 1076 12v po w er so urces, 391-392

1432

13-inch monitors, recommended resolution

13-in ch m o n ito rs, reco m m en ded reso lutio n , 511 14-in ch drives, 732-733 15-in ch m o n ito rs cost com p arison s, 505 recom m en d ed resolu tion , 511 16 co lo rs CGA ad ap ters, 515 EGA ad ap ters, 515 16-bit audio , 565 16-bit co lo r, 528 LCDs, 917 16-bit CPUs 8086, 83 8087 m ath coprocessor, 84 ad d ress bu s wid th , 83 cost, 83 80286, 84 80287 m ath cop rocessor, 86 p rotected m od e, 86 real m od e, 85 sp eed s, 85 Stan d ard m od e (W in d ows 3.0), 86 80386 (386SX), 88-89 real-m od e op eration , 44 16-bit data buses, 38 16-bit FATs, 1076 see also, FAT16; FAT32 16-bit in tern al registers, 39 16-bit ISA buses, 241-243 DMA ch an n els, 275-276 IRQs, 272-274 16-bit system s (AT class), 24 16-bit Win do w s versio n s W in d ows 3.1, 1054 W in d ows 3.11, 1055 W in d ows for W orkgrou p s NetBEUI p rotocol, 1055 TCP/ IP-32, 1055 16.8 m illio n co lo r (m em o ry requirem en ts), 529 17-in ch m o n ito rs cost com p arison s, 505 recom m en d ed resolu tion s, 505, 511 17-secto r/ 17-track h ard disk secto r fo rm ats, 726 INTER-RECORD GAP, 727 POST INDEX Gap , 726 PRE-INDEX GAP, 727 Sector ID d ata, 727 W RITE TURN-ON GAP, 727

21-in ch m o n ito rs, reco m m en ded reso lutio n , 511 21M flo ptical drives, 798 24-bit co lo r, 528, 917 24-pin do t m atrix prin ters, 872-873 25-pin parallel po rt co n n ecto rs, 593-594 25-pin serial-po rt co n n ecto rs, 585-587 30-pin SIMMs, 325, 959 cap acities, 326 p in ou ts, 329-330 32-bit CardBus in terface (PC Cards), 933 32-bit co lo r, 529 32-bit CPUs 80386, 87 386DX, 88 386SL, 89 386SX, 88-89 80387 m ath cop rocessor, 90 bu gs, 90-92 MMU (Mem ory Man agem en t Un it), 87 p rotected m od e, 87 virtu al real m od e, 87 W eitek m ath cop rocessors, 90 80486, 92-95 486DX, 95-97 486SL, 97-98 486SX, 98 487SX m ath cop rocessor, 98-99, 103 AMD 486 (5x86), 103-104 Cyrix/ TI 486, 104 DX2/ OverDrive, 99-101 DX4 p rocessors, 101 n ew featu res over 386, 92-93 Pen tiu m OverDrives, 101 secon d ary OverDrive sockets, 102 sp eed s, 93 In tel-com p atible AMD K5, 125-126 IDT Cen tau r C6 W in ch ip , 126-127 Pen tiu m , 105 ad d ress bu s wid th , 106 ad d ressable m em ory, 106

BiCMOS (Bip olar Com p lem en tary Metal Oxid e Sem icon d , 108 BTB (Bran ch Target Bu ffer), 106 cach e, 107-108 classic step p in gs, 118-120 d ata bu s wid th , 106 DIMM wid th , 106 first-gen eration , 109-110 FPU, 109 FPU bu g, 114-116 in struction processin g, 107 Mod el 1 step p in gs, 117 p ackagin g, 109 p ower m an agem en t bu gs, 116 secon d -gen eration , 110-113 SIMM wid th , 106 SL en h an cem en ts, 108 sp ecification s, 105-106 step p in gs, 124 su p erscalar arch itectu re, 105 twin d ata p ip elin es, 105-106 voltages, 108, 125 Pen tiu m OverDrive step p in gs, 122-124 voltages, 125 Pen tiu m -MMX, 113-114 clock sp eed s, 113 ju m p in g for 60/ 66MHz op eration , 114 SIMD, 114 step p in gs, 121-124 u p grad in g, 114 voltages, 113, 125 VRM, 114 p rotected -m od e op eration , 44 real-m od e op eration , backward com p atibility, 44 virtu al real m od e op eration , 45 DOS exten d ers, 46 m em ory access lim its, 45 software su p p ort, 46 32-bit data buses, 38 32-bit disk access (Win do w s 3.1), 1057 fastd isk, 1057 trou blesh ootin g software p roblem s, 1058

386 CPUs

32-bit in tern al registers, 39 d ata bu s lim itation s, 40 32-bit ISA bus, 244 32-bit m em o ry, in terleavin g, 315 32-bit SIMMs, 39 32-bit so ftw are (Pen tium Pro / Pen tium II CPU o ptim izatio n ), 130 32-bit system s (AT class), 24 33MHz PCI (Periph eral Co m po n en t In terco n n ect), 186 36-bit in terleaved SIMMs, 328 40-pin IDE co n n ecto rs, 612, 614 50-pin Cen tro n ics cables (SCSI device co n n ectio n s), 857 56K m o dem s, 667-668 d igital-to-an alog con version , 668 direct PSTN con n ection s, 668 lin e n oise, 669 on e-way 56K tran sm ission s, 668 recom m en d ation s, 671 stan d ard s (ISP su p p ort), 669 64-bit bus w idth s (video m em o ry), 529 64-bit CPUs P7 (Merced ), 158-161 Pen tiu m II, 127, 140 DIB (Du al In d ep en d en t Bu s), 128-129, 142, 144 Dyn am ic Execu tion , 127-128, 142 ECC (Error Correction Cod e), 145 fu tu re d evelop m en ts, 151-152 h eat p roblem s, 145 iCOMP 2.0 In d ex ratin g, 141 in stallin g, 145 in stru ction execu tion , 129 MMX tech n ology, 141 Mobile Mod u le, 151 m u ltip rocessin g, 145 p ower u sage, 142 ru n n in g 32-bit software, 130 SEC (Sin gle Ed ge Con tact) p ackagin g, 140 sp ecification s, 143 sp eed s, 141

tran sistors, 141 version ID in form ation , 147-149 voltage ID d efin ition s, 150-151 Pen tiu m Pro, 127, 130 cach e, 130 ch ip sets, 134 DIB (Du al In d ep en d en t Bu s), 128-129 Du al Cavity PGA p ackagin g, 130 Dyn am ic Execu tion , 127-128 form factors, 134 in stru ction execu tion , 129 in tegrated L2 cach e, 134 MCM (Mu lti-Ch ip Mod u le), 130 ru n n in g 32-bit software, 130 sp ecification s, 132-133 sp eed s, 134 step p in gs, 135-138 tran sistors, 130 VID (Voltage Id en tification ) p in s, 135 64-bit data buses, 38 , 40 64-bit DIMMs, 39 64-bit m em o ry, in terleavin g, 315 64-bit system s (AT class), 24 66MHz AGP buses (Accelerated Graph ics Po rt), 186 66MHz m o th erbo ard speeds, 35-37, 43 72-pin SIMMs, 325, 328, 959 cap acities, 326 p in ou ts, 330-331 p resen ce d etect p in s, 331-333 82C206 ch ips, 184 83-key PC/ XT keybo ards, 446 key n u m bers an d scan cod es, 463-464 84-key AT keybo ards, 447 key n u m bers an d scan cod es, 464-465 100BaseT pro to co l, 704 100Mbps Eth ern et (LANs), 704 100BaseT, 704 100VG, 705 stan d ard s, 704 100MHz m o th erbo ard speeds, 43

1433

100VG pro to co l (quartet sign alin g), 705 101-key keybo ards, 448 con n ectors, 448 foreign lan gu age version s, 449 key n u m bers an d scan cod es, 466-469 layou t, 449 rem ovable keycap s, 449 102-key keybo ards (key n um bers an d scan co des), 466-469 104-key keybo ards (Win do w s), 449 Ap p lication key, 450 ergon om ics, 451 key n u m bers an d scan cod es (n ew keys), 469 layou t, 450 W IN keys, 450 W in d ows 95 key com bin ation s, 450-451 128-bit bus w idth s (video m em o ry), 529 168-pin DIMMs, 325-326 cap acities, 327 p in ou ts, 333-336 168-pin SIMMs, 959 286 CPUs, see 80286 CPUs 300 dpi prin ters, 870-871 360K 5 1/ 4-in ch flo ppy drives, 787 386 CPUs 16-bit d ata bu ses, 38 32-bit d ata bu ses, 38 386DX, 88 32-bit d ata bu ses, 38 ad d ressable m em ory, 88 bu gs, 90-92 m axim u m in stallable m em ory, 323 sp eed s, 88 386SL, 89 LIM (Lotu s In tel Microsoft) su p p ort, 89 SMI (System Man agem en t In terru p t), 89 386SX, 88-89 16-bit d ata bu ses, 38 ad d ressable m em ory, 89 d ata bu s wid th s, 39 m axim u m in stallable m em ory, 323 387DX m ath cop rocessor, 90

1434

386 CPUs

387SX m ath cop rocessor, 90 82350 ch ip sets, 187 ad d ressable m em ory, 87-88 bu s wid th s, 22 MMU (Mem ory Man agem en t Un it), 87 p rotected m od e, 44, 87 virtu al real m od e, 45-46, 87 W eitek m ath cop rocessors, 90 386 en h an ced m o de (Win do w s 3.x m ultitaskin g), 1056 420EX ch ipset, 187 420TX ch ipset, 187 420ZX ch ipset, 187 430FX (Trito n ) ch ipset, 190-191 430HX (Trito n II) ch ipset, 191-192 430LX (Mercury) ch ipset, 189-190 430MX PCIset ch ipset, 929 430NX (Neptun e) ch ipset, 190 430TX PCIset ch ipset (Pen tium / MMX), 193-194, 929 430VX (Trito n III) ch ipset, 193 440BX AGPset m o bile ch ipset h ost brid ge, 929 PIIX4 PCI/ ISA brid ge, 929 440BX ch ipsets, 205 440EX ch ipsets, 204-205 440FX (Nato m a) ch ipsets, 203-204 440LX ch ipsets, 134, 204 450KX/ GX (Orio n ) ch ipsets, 134, 202-203 486 CPUs 32-bit d ata bu ses, 38 32-bit in tern al registers, 39 486DX, 95-97 ad d ressable m em ory, 95-96 in tern al cach e, 96 p rotected m od e, 97 real m od e, 97 sp eed s, 95 tran sistors, 95 virtu al real m od e, 97 486DX2 (Pen tiu m OverDrives), 101 486SL, 97-98 SMI (System Man agem en t In terru p t), 97

SMM (System Man agem en t Mod e), 47, 97 su sp en d / resu m e featu re, 97 486SX, 98 DX2/ OverDrive p rocessors, 99 m asks, 98 sp eed s, 98 486SX2 (Pen tiu m OverDrives), 101 487SX m ath cop rocessor, 98-99, 103 82350 ch ip sets, 187 AMD 486 (5x86), 80, 103-104 cach e m od es, 104 clock sp eed s, 103 h eat sin ks, 104 op eratin g voltage, 103-104 VOLDET p in , 104 write-back cach e, 103 bu s wid th s, 22 cach e 4-way set associative, 42 write-th rou gh , 42 ch ip sets, 187 Cyrix/ TI 486, 104 DX2/ OverDrive, 99-101 DX4 p rocessors, 101 in stru ction -execu tion tim es, 92 m axim u m in stallable m em ory, 323 n ew featu res over 386, 92-93 OverDrive sockets (secon d ary), 102 secon d ary OverDrive sockets, 102 sockets, 54, 57 Socket 1, 57 Socket 2, 59-61 Socket 3, 61 Socket 4, 62 Socket 5, 63 Socket 6, 63 Socket 7, 64 Socket 8, 65 ZIF, 67 sp eed s, 93 u p grad in g, 95 600 dpi prin ters, 871 640K m em o ry barrier, 360 686 CPUs, see Pen tium Pro CPUs; Pen tium II CPUs

720K 3 1/ 2-in ch flo ppy drives, 785-786 1200 dpi prin ters, 870-871 2400 dpi prin ters, 871 4004 In tel CPU, 10 5581/ 5582 ch ipset (Pen tium pro cesso rs), 198-199 5591/ 5592 ch ipset (Pen tium pro cesso rs), 199 5600/ 5595 (SiS) ch ipsets, 207 6805 keybo ard co n tro ller (Mo to ro la), 458 8008 In tel CPU, 10 8042 keybo ard co n tro ller ch ip (84-key AT keybo ard), 447 8048 keybo ard co n tro ller, 458, 462 8049 keybo ard co n tro ller, 458 8080 In tel CPU, 10 8086 CPUs, 83 8087 m ath cop rocessor, 84 ad d ress bu s wid th , 83 cost, 83 m axim u m in stallable m em ory, 323 8087 m ath co pro cesso r (8086 CPUs), 84 8088 CPUs, 23-24, 83 d ata bu s wid th s, 39 IBM PC, 84, 1101 IBM PC XT, 1115 m axim u m in stallable m em ory, 323 sp eed s, 84 8250 UART ch ips, 587-588 8250A UART ch ips, 588 8250B UART ch ips, 588 16450 UART ch ips, 587-589 16550 UART ch ips, 587-589 16550A UART ch ips, 587-589 16550D UART ch ips, 587 80186 CPUs, 84 80188 CPUs, 84 80286 CPUs, 24, 84, 1129 16-bit d ata bu ses, 38 80287 m ath cop rocessor (Setu p p rogram errors), 86 ad d ressable m em ory, 86 bu s wid th s, 22 IBM PC XT Mod el 286, 1145 m axim u m in stallable m em ory, 323 p rotected m od e, 86 real m od e, 85 sp eed s, 85 Stan d ard m od e (W in d ows 3.0), 86

active preventive maintenance

80287 m ath co pro cesso r (Setup pro gram erro rs), 86 80386 CPUs, 24, 87 16-bit d ata bu ses, 38 32-bit d ata bu ses, 38 386DX, 88 ad d ressable m em ory, 88 bu gs, 90-92 m axim u m in stallable m em ory, 323 sp eed s, 88 386SL, 89 LIM (Lotu s In tel Microsoft) su p p ort, 89 SMI (System Man agem en t In terru p t), 89 386SX, 88-89 ad d ressable m em ory, 89 m axim u m in stallable m em ory, 323 80387 m ath cop rocessor, 90 82350 ch ip sets, 187 ad d ressable m em ory, 87 bu s wid th s, 22 MMU (Mem ory Man agem en t Un it), 87 p rotected m od e, 87 virtu al real m od e, 87 W eitek m ath cop rocessors, 90 80486 CPUs, 23-24, 92-93 32-bit d ata bu ses, 38 32-bit in tern al registers, 39 486DX, 95-97 in tern al cach e, 96 p rotected m od e, 97 real m od e, 97 sp eed s, 95 tran sistors, 95 virtu al real m od e, 97 486DX2 (Pen tiu m OverDrives), 101 486SL, 97-98 SMI (System Man agem en t In terru p t), 97 SMM (System Man agem en t Mod e), 47, 97 su sp en d / resu m e featu re, 97 486SX, 98 486SX2 (Pen tiu m OverDrives), 101 487SX m ath cop rocessor, 98-99, 103

82350 ch ip sets, 187 AMD 486 (5x86), 80, 103-104 cach e m od es, 104 clock sp eed s, 103 h eat sin ks, 104 op eratin g voltage, 103-104 VOLDET p in , 104 write-back cach e, 103 bu s wid th s, 22 cach e 4-way set associative, 42 write-th rou gh , 42 ch ip sets, 187 Cyrix/ TI 486, 104 DX2/ OverDrive, 99-101 DX4 p rocessors, 101 in stru ction -execu tion tim es, 92 m axim u m in stallable m em ory, 323 n ew featu res over 386, 92-93 OverDrive sockets (secon d ary), 102 secon d ary OverDrive sockets, 102 sockets, 54, 57 Socket 1, 57 Socket 2, 59-61 Socket 3, 61 Socket 4, 62 Socket 5, 63 Socket 6, 63 Socket 7, 64 Socket 8, 65 ZIF, 67 sp eed s, 93 u p grad in g, 95 80586 CPUs, see Pen tium 80686 CPUs, see Pen tium Pro ; Pen tium II 82433NX ch ips (lo cal bus accelerato rs), 190

A A+ Certificatio n fo r Co m puter Tech n ician s, 1202 A+ Ex am (Co m pTIA + Co re Ex am ), 1167 d iagn osin g an d trou blesh ootin g, 1170 in stallation , con figu ration an d u p grad in g, 1167-1169

1435

m oth erboard s, p rocessors an d m em ory, 1171-1173 n etworkin g, 1174-1175 p ortable com p u ters, 1174 p rin ters, 1173-1174 safety an d p reven tative m ain ten an ce, 1170-1171 a-pin en e clean ers, 1016 a-Si (h ydro gen ated am o rph o us silico n ), TFT (th in film tran sisto r) array, 915 A/ N (alph an um eric) m o de, CGA (Co lo r Graph ics Adapter), 515 A20 lin e, 378 AAD (An alo g Align m en t Diskette), 795 ABC To o lkit, 1212 Abo ve Bo ards (ex pan ded m em o ry), 379 abso lute addressin g (TCP/ IP), 707 AC (altern atin g-curren t), 1008 rip p le, 417 Accelerated Graph ics Po rt, see AGP accelerato rs (video ch ipsets), 526 access tim es (CD-ROM specificatio n s), 831-832 Access Visual Basic Adviso r, 1194 Accupo in t (To sh iba), 494 Acer Labo rato ries, In c., see ALi ch ipsets aceto n e (stan dard clean ers), 1016 aco ustic co uplers (po rtable m o dem co n n ectio n s), 945 ACPI (Advan ced Co n figuratio n an d Po w er In terface), 942 active backplan e system s (pro prietary m o th erbo ards), 181 active h eat sin ks, 73, 967 active m atrix LCDs, 915 screen size, 916 TFT (th in film tran sistor) array, 915-916 active preven tive m ain ten an ce, 1011-1012 clean in g system s, 1013-1014 board s an d con n ectors, 1020 bru sh es an d swabs, 1018

1436

active preventive maintenance

ch em icals, 1015-1019 con n ectors, 1021 con tacts, 1021 d isassem bly p roced u res, 1019 keyboard s, 1022 m ou se, 1022 obtain in g su p p lies, 1019 p ower su p p lies, 1020 tools, 1015 reseatin g socketed ch ip s, 1019-1020 system backu p s, 1012-1013 active screen area (m o n ito r sizes), 504 active term in ato rs (SCSI), 640 active-m atrix LCDs (liquid crystal displays), 502 color screen s, 503 costs, 503 m u ltip le-freq u en cy, 502 Adaptec FireW ire (IEEE 1394) ad ap ters, 605 SCSI h ost ad ap ters, 654 adapter BIOS (Sh ared Mem o ry), 362 Adapter page (Win do w s Display Co n tro l Pan el), 534 adapter ROM, 304-305, 369 h ard d rive an d SCSI con troller BIOS, 370-372 m em ory con flicts, p reven tin g, 380-381 n etwork ad ap ter card s, 372-374 vid eo ad ap ter BIOS, 369-370 adapters au d io, see sou n d card s bu s slot (MCA to ISA), 989 FireW ire (IEEE 1394), 605 h ost, con figu rin g, 762-764 in terface (op tical d rives), 854 MCA bu ses, 246 m em ory, 354, 385 d eterm in in g con figu ration of, 385-386 op tim izin g, 386-387 p reven tin g con flicts, 386 PC Card Card Services, 936 Socket Services, 935 SCSI (on board BIOS), 990 serial-p ort con n ectors, 587

vid eo, 29, 499, 513, 535, 965 3D grap h ics accelerators, 543-545 ATX m oth erboard con n ection s, 500 Baby-AT m oth erboard con n ection s, 500 BIOS, 525-526 bu ses, 531-533 cap tu re board s, 537-538 CGA (Color Grap h ics Ad ap ter), 515 ch ip sets, 526 Cyrix Med iaGX, 500 DACs (Digital-to-An alog Con verter), 531 d rivers, 533-535 DTV (Desktop Vid eo board s), 540-542 EGA (En h an ced Grap h ics Ad ap ter), 515 in tegrated , 961 MCGA (Mu ltiColor Grap h ics Array), 517 MDA (Mon och rom e Disp lay Ad ap ter), 514 m em ory, 527-531 MPEG com p ression , 537 m u ltip le m on itors, con n ectin g, 539 ou tp u t d evices, 537-538 PGA (Profession al Grap h ics Ad ap ter), 516 PS/ 2 Disp lay Ad ap ter 8514/ A, 516 stan d ard s, 513-514 SVGA (Su p er VGA), 521-524 trou blesh ootin g, 546-547 VFC (Vid eo Featu re Con n ector), 536-537 VGA (Vid eo Grap h ics Array), 517-519 XGA (eXten d ed Grap h ics Array), 519-521 XGA-2 (eXten d ed Grap h ics Array), 520 Adaptive Differen tial Pulse Co de Mo dulatio n , see ADPCM ADCs (an alo g-to -digital co n verters), sam plin g, 564 addressable m em o ry, CPUs, 40-41 286 CPUs, 86 386 CPUs, 87 386DX CPUs, 88

386SX CPUs, 89 486DX CPUs, 95-96 8088 an d 8086 CPUs, 83 Pen tiu m CPUs, 105-106 Pen tiu m II CPUs, 143 Pen tiu m Pro CPUs, 132 addresses bu ses 8086 CPUs, 83 CPUs, 40-41 Pen tiu m CPUs, 105-106 Pen tiu m II CPUs, 143 Pen tiu m Pro CPUs, 132 see also m em ory, ad d ressable CMOS RAM, 224-227 I/ O p orts, 277-281 m em ory, see logical m em ory p arallel p orts, con figu rin g, 598 ROM, 304 serial p orts, con figu rin g, 590-591 addressin g BIOS (ATA-2/ 3 IDE), 622 m em ory, 304 AdLib so un d card, 550 Ado be Po stScript, 874-875 ADPCM (Adaptive Differen tial Pulse Co de Mo dulatio n ), 569, 843 Advan ced Ch ipset Setup fun ctio n s, 957 Advan ced Co n figuratio n an d Po w er In terface, 111 Advan ced Micro Devices, see AMD Advan ced Po w er Man agem en t (APM), 20, 393, 507, 957 ch ip set su p p ort, 957 m on itors, 507 PC Card su p p ort, 933 p ortable com p u ters, 942 p ower m an agem en t, 423-425 Advan ced Pro gram m able In terrupt Co n tro ller, 111 Advan ced SCSI Pro gram m in g In terface, 645, 833, 863 afterm arket diagn o stic so ftw are, 984 AGC (Auto m atic Gain Co n tro l), so un d cards, 566 agen cies Can ad ian Stan d ard s Agen cy (CSA), 417 Un d erwriters Laboratories, In c. (UL), 417

Application key

AGP (Accelerated Graph ics Po rt), 186, 233, 269, 532-533 2.0 sp ecification ,269, 533 AGP X2 Pen tiu m II m oth erboard su p p ort, 532 DIME (Direct Mem ory Execu te), 532 In tel, 20 m axim u m th rou gh p u t, 532 m obile system s, 929 North Brid ges, 186 X2 (Pen tiu m II), 532 air bearin g, 723 air filters (h ard disk drives), 749-750 AIWA Am erica, In c. Co m puter System s Divisio n , 1181 Aladdin IV ch ipset (Pen tium pro cesso rs), 197 Aladdin M1510 ch ipset, 956 Aladdin Pro II M1621 ch ipsets, 205 Aladdin V ch ipset (Pen tium pro cesso rs), 198 ALi ch ipsets (Acer Labo rato ries, In c.), 197 Alad d in Pro II M1621 (Pen tiu m Pro/ II), 205 Alad d in IV (Pen tiu m ), 197 Alad d in V (Pen tiu m ), 198 align m en t flop p y d isk d rives, 794-795 h ard d isk d rives, 773 all po in ts addressable (APA) m o de, CGA (Co lo r Graph ics Adapter), 515 allo catio n un its, see clusters alph a particles p arity ch eckin g, 345 soft m em ory errors, 344-345 Alps Glidepo in t po in tin g device, 449 Am 5x 86(TM)-P75 CPU (AMD), 103-104 cach e, ju m p erin g, 104 clock sp eed s, 103 h eat sin ks, 104 op eratin g voltage, 103-104 VOLDET p in , 104 write-back cach e, 103 AMD (Am erican Micro Devices) Am 5x86(TM)-P75 CPU, 103-104 cach e m od es, 104 clock sp eed s, 103

h eat sin ks, 104 op eratin g voltage, 103-104 VOLDET p in , 104 write-back cach e, 103 In tel-com p atible CPUs, 80 In tel MMX licen sin g, 48 K5 CPUs, 125 clock m u ltip liers, 126 clock sp eed s, 126 m oth erboard com p atibility, 125, 154 voltages, 126 K6 CPUs, 153-154 ID m arkin gs, 155 m oth erboard com p atibility, 153-154 sp ecification s, 153-154 sp eed s, 155 voltages, 155 m oth erboard s Alad d in M1510 ch ip set, 956 com p atability, 125, 154 Op ti 82C550 Vip er-DP ch ip set, 956 Am erica On lin e (AOL), PC tro ublesh o o tin g reso urces, 1164 Am erican Natio n al Stan dards In stitute, see ANSI AMI (Am erican Megatren ds In tern atio n al), 958 AMI BIOS (Basic In put Output System ), 210-214 d iagn ostics, 213 error m essages, 222 h ard d isk p aram eters, 1409-1410 ID strin gs, 211-213 POST au d io error cod es, 986 W eb site, 214 AMIDiag diagn o stic so ftw are, 992 AMP Web site, 341 am plificatio n (speakers), 579 am plitude (so un d in ten sity), 563 An alo g Align m en t Diskette (AAD), 795 an alo g m o n ito rs (frequen cy ch o ices), 510 an alo g video , VGA (Video Graph ics Array), 517 an alo g-to -digital co n verters, see ADCs

1437

An dro m eda Research , 308 an im atio n (3D im age rasterizatio n ), 545 ANSI (Am erican Natio n al Stan dards In stitute) ANSI.SYS, 389 exten d ed ASCII keycod es for ANSI.SYS, 1333-1334 SCSI stan d ard s, 628-630 an ti-static w rist-gro un din g strap, 1015 an ti-virus so ftw are, 1024 AOL (Am erica On lin e), PC tro ublesh o o tin g reso urces, 1164 APA (all po in ts addressable) m o de, CGA (Co lo r Graph ics Adapter), 515 APIC (Advan ced Pro gram m able In terrupt Co n tro ller), 111 APM (Advan ced Po w er Man agem en t), 20, 393, 507, 957 ch ip set su p p ort, 957 m on itors, 507 PC Card su p p ort, 933 p ortable com p u ters, 942 p ower m an agem en t, 423-425 Apo llo m vp3 ch ipset (Pen tium pro cesso rs), 196-197 AGP su p p ort, 532 Apo llo p6/ 97 ch ipsets, 206 Apo llo Pro ch ipsets, 206-207 Apo llo VP-1 ch ipset (Pen tium pro cesso rs), 194 Apo llo VP2 ch ipset (Pen tium pro cesso rs), 195 Apo llo vp3 ch ipset (Pen tium pro cesso rs), 195-196 , 532 Apo llo VPX ch ipset (Pen tium pro cesso rs), 195 APPEND.EXE (Win do w s 95 CD-ROM), 1417 Apple Co m puter, 11 Ap p le I, 11 Ap p le II, 11 Ap p le Lisa com p u ter, 480 Ap p le Macin tosh , 480 com p atibles, 18 h istory of (com p atibility issu es), 14 Applicatio n key (Win do w s keybo ards), 450

1438

Application layer

Applicatio n layer (OSI Referen ce Mo del), 683 applicatio n s Disk Man ager, 619 MS-DOS (m ou se p roblem s), 490 p rin tin g p roblem s, 908 p rotocols (TCP/ IP), 707 sou n d card s, 549 au d io CDs, p layin g, 560 bu sin ess ap p lication s, 556-557, 561-562 con feren cin g, 560 gam in g, 551, 563 MIDI files, 550, 553-556 m u ltim ed ia, 551-552 p roofread in g, 560 record in g, 558 Sou n d Blaster, 550 sou n d files, 553, 561 stan d ard s, 550 voice an n otation s, 558 voice recogn ition , 559-560 arch ivin g tape drives 8m m tap e, 814 backu p software, 820-821 cap acities, 817 cost, 818 DAT stan d ard s, 812-814 d ata th rou gh p u t, 818 DLT stan d ard s, 814-815 in stallin g, 819-820 p ortable, 818-819 QIC stan d ard s, 807-812 software com p atibility, 817-818 Travan cartrid ge tap e, 815-816 ARCn et (data lin k layer pro to co ls), 700 areal den sity (h ard disk drives), 720-722 ARLL (Advan ced Run Len gth Lim ited), 715 ARP, 707 ASCII (Am erican Stan dard Co de fo r In fo rm atio n Ex ch an ge) ch aracter cod es, 1325 exten d ed ASCII keycod es for ANSI.SYS, 1333-1334 h exad ecim al con version s, 1326-1334 ASPI (Advan ced SCSI Pro gram m in g In terface), 645, 833, 863

ASPI-Man ager, 833 assem blers (edito rs), 1032 assem blin g system s, 968-969 d ocu m en tation , 969 ESD p rotection , 969-971 extern al cables, con n ectin g, 977 m oth erboard s cables, con n ectin g, 975-976 exp an sion card s, in stallin g, 976 in stallin g, 972-974 p ower su p p lies, con n ectin g, 974-975 rep lacin g th e cover, 977 ru n n in g CMOS Setu p , 978-979 recordin g con figu ration s, 971 ASSIGN co m m an d (retired fo r Win do w s 9x ), 1418 asyn ch ro n o us cach e, 322, 958 asyn ch ro n o us m o dem s, 656 56K, 667-668 d igital-to-an alog con version s, 668 d irect PSTN con n ection s, 668 lin e n oise, 669 on e-way 56K tran sm ission s, 668 stan d ard s, 669 con n ection s d ata bits, 657 N-8-1, 657 p arity, 657 stop bits, 657 d ata com p ression stan d ard s, 664 MNP 5, 664 V.42bis, 664-665 error-correction p rotocols, 663 MNP 1-4, 664 V.42, 664 fax m od em stan d ard s, 666 Grou p III p rotocol, 667 Grou p IV p rotocol, 667 m od u lation stan d ard s, 660 Bell 103, 661 FSK (freq u en cy-sh ift keyin g), 661 fu ll-d u p lex p rotocols, 661 h alf-d u p lex p rotocols, 661-662 PSK (p h ase-sh ift keyin g), 661

QAM (q u ad ratu ream p litu d e m od u lation ), 661 V.21, 662 V.22, 662 V.23, 662 V.29, 662 V.32, 662 V.32fast, 663 V.34, 663 V.90, 663 V32.bis, 663 p rop rietary stan d ard s, 665 CSP (Colm p u Com Sp eed Protocol), 666 DIS, 665 HST, 665 MNP, 665-666 V-series (Hayes), 666 recom m en d ation s, 670 56K m od els, 671 au to-n egotiation , 670 extern als, 670 in tern als, 670 sp eed s (bau d vs. bp s), 660 stan d ard s, 658 backward com p atibility, 659 Bell Labs, 658 Hayes-com p atibility, 660 ITU, 658 p rop rietary, 659 start bits, 656-657 stop bits, 656-657 asyn ch ro n o us serial in terface, 583-584 25-p in con n ectors, 585-586 9-p in con n ectors, 584-586 con n ector ad ap ters, 587 h igh sp eed , 589-590 UART ch ip s, 587-589 AT Attach m en t IDE, see ATA IDE AT Attach m en t Packet In terface, 624-625, 833 AT class system s (16/ 32/ 64-bit), 24 AT m o th erbo ards Baby-AT, 167-169 CMOS RAM (ad d resses), 224-227 fu ll-size, 169-170 AT/ Desk fo rm facto rs, 395-396 AT/ To w er fo rm facto rs, 396-397

autosynchronous monitors

ATA IDE (In tegrated Drive Electro n ics), 611, 614-615 cablin g, 616 com m an d s, 617-618 d u al d rive con figu ration s, 615 I/ O con n ectors, 615-616 in telligen t, 620-621 n on -in telligen t, 619 sign als, 616-617 ATA stan dard (PC Cards), 933 ATA-2 IDE (In tegrated Drive Electro n ics), 621 ATAPI (ATA Packet In terface), 624-625 BIOS, 621-623 d ata tran sfer sp eed s, 623-624 DMA m od es, 624 ATA-3 IDE (In tegrated Drive Electro n ics), 621 ATAPI (ATA Packet In terface), 624-625 BIOS, 621-623 d ata tran sfer sp eed s, 623-624 DMA m od es, 624 ATA-4 IDE, 625 ATA/ IDE in terfaces (CD-ROM), 830 ATAPI (AT Attach m en t Packet In terface), 624-625, 833 ATAPI-Style Lin e In co n n ecto rs, 231 ATDT co m m an d (m o dem s), 660 ATH1 co m m an d (m o dem s), 660 ATI Mach 64/ Rage I/ II video adapters, 539 ATM (Asyn ch ro n o us Tran sfer Mo de), 705 atten uatio n (fiber-o ptic cablin g), 695 ATTRIB.EXE (Win do w s 9x DOS), 1415 ATX fo rm facto rs, 398-401, 949 m oth erboard s, 173-175, 951-952 case d esign s, 950 con n ectors, 231-232 coolin g CPUs, 74 exp an sion slots, 952 in tern al fan , 952 m icro-ATX, 952 NLX (Low Profile), 949, 952

p ower su p p lies, 952 vid eo ad ap ter con n ection s, 500 p ower su p p lies, 949 con n ectors, 405 op tion al 6-p in con n ector, 405-406 ou tp u t ratin gs, 413-414 ATX m o th erbo ards, co o lin g CPUs, 74 audible co n tin uity tests (DMMs), 428 audio , 549 ad ap ters, see sou n d card s cap acities (CD-ROMs), 823 CDs (CD-ROM d ifferen ces), 826 MIDI files, 553 d evice con n ectivity, 555-556 Gen eral MIDI stan d ard , 554 p layin g, 554-555 software, 556 storin g, 553 sou n d card s, 581 8-bit au d io, 564 16-bit au d io, 565 ap p lication s, 549-550 au d io CDs, p layin g, 560 basics of sou n d , 562-563 bu n d led software, 571 bu sin ess ap p lication s, 556-557, 561-562 CD-ROM con n ectors, 569-570 con feren cin g, 560 con n ectors, 565-567 d ata com p ression , 568-569 d rivers, 570 DSPs (Digital Sign al Processors), 569 freq u en cy resp on se, 563 gam e com p atibility, 549 gam in g, 551, 563 in stallin g, 571-574 m arket d om in an ce, 550 m icrop h on es, 581 MIDI p orts, 555 m u ltim ed ia, 551-552 p roofread in g, 560 record in g, 558 sam p lin g, 564 Sou n d Blaster, 550, 571 sou n d m ixin g, 561

1439

sp eakers, 579-580 stan d ard s, 550 syn th esis (stereo vs. m on o), 568 total h arm on ic d istortion , 563 trou blesh ootin g, 574-579 u ser n eed s, 570-571 voice an n otation s, 558 voice recogn ition , 559-560 volu m e con trols, 567 W ave Blaster, 568 sou n d files (resolu tion s), 553 audio CDs (Win dow s 3.x CD-ROM drive playback), 866 audio erro r co des (POST), 985 AMI BIOS, 986 Ph oen ix BIOS fatal errors, 986-987 n on fatal errors, 988 auto sw itch in g, 453 auto term in atin g h o st adapters, 861 auto -n ego tiatio n (m o dem reco m m en datio n s), 670 AUTOEXEC.BAT, lo adin g, 1047 m ou se d rivers, 481 auto m atic display h o ld feature (DMMs), 429 auto m atic drive typin g (h ard disk drives), 766 Auto m atic Gain Co n tro l (AGC) , 566 auto m atic h ead parkin g, 748-749 auto m atic po w er o ff features (DMMs), 428 auto m atic setup (EISA bus), 247 auto m atic sh utdo w n (po w er supply pro tectio n ), 436 auto m atic to rqueco m pen satio n , 775 Auto Play (CD-ROM drives) W in d ows 9x, 866 W in d ows NT 4.0, 866 auto ran gin g DMMs, 428 m eters, 1008 AUTORUN.INF (Auto In sertio n No tificatio n Auto play feature), 867 auto syn ch ro n o us m o n ito rs, see m ultiple-frequen cy m o n ito rs

1440

autotracking monitors

auto trackin g m o n ito rs, see m ultiple-frequen cy aux iliary BIOS ro utin es, 304 Available Po rts dialo g bo x , 899 average access tim e (h ard disk drives), 756 average seek tim e (h ard disk drives), 720, 756-759 AVI Apo llo MVP3 ch ipset, 956 AVI files, 542, 557 Aw ard BIOS (Basic In put Output System ), 214 error m essages, 223 Aw ard ROM BIOS (h ard disk param eters), 1411-1412 Aw ard So ftw are, 17 Azim uth (h ead po sitio n m easurem en t), 742

B B ch an n els, see bearer ch an n els Baby-AT m o th erbo ards, 20, 167-169, 397-398, 951 ATX com p arison s, 173-174 case d esign s, 950 con n ectors, keyboard , 951 vid eo ad ap ter con n ection s, 500 see also ATX form factors, m oth erboard s back pro bin g (m easurin g vo ltage), 429 backligh tin g, LCDs (liquid crystal displays), 503 backo ff in tervals (Eth ern et pro to co l), 701 backplan e system s (pro prietary m o th erbo ards), 180-181 active, 181 p assive, 180-181 see also NLX m oth erboard s backside buses, see DIB (Dual In depen den t Bus Arch itecture) BACKUP co m m an d (retired fo r Win do w s 9x ), 1418 backup po w er supplies, 438 SPS (Stan d by Power Su p p lies), 439 UPS (Un in terru p tible Power Su p p lies), 439-441

backups h ard d isk d rive, 1012 tap e d rives, 1012-1013 writable CD-ROM d rives, 1012-1013 Zip / Jaz d rives, 1012-1013 server req u irem en ts, 687 tap e d rives 8m m tap e, 814 backu p software, 820-821 cap acities, 817 cost, 818 DAT stan d ard s, 812-814 d ata th rou gh p u t, 818 DLT stan d ard s, 814-815 in stallin g, 819-820 p ortable, 818-819 QIC stan d ard s, 807-812 software com p atibility, 817-818 Travan cartrid ge tap e, 815-816 ven d ors, 1245 backw ard co m patibility 16-bit (W in d ows 95), 45 32-bit p rotected m od e CPUs, 44 DVD d rives, 852 in d u stry con trol, 18 lon g file n am es, 1081 m od em stan d ard s, 659 VFAT, 1079 bad-track tables (h ard disk drives), 1079 ban d buffers, 884 ban dw idth , 237 bu ses, 233-234 CATV n etworks, 674 asym m etrical n etworks, 674 tu n er (cable m od em s), 674 EISA bu ses, 247 ISDN (In tegrated Service Digital Network) bearer ch an n els, 671 d elta ch an n els, 671 m axim u m , AGP (Accelerated Grap h ics Port), 532 p rocessor bu s, 237 SCSI, 630 ban ks, m em o ry, 329-340, 353 wid th s, 39 baro m etric filters, 749 base 2 n um berin g system s (address buses), 40

baseban d n etw o rks (LANs), 678 BASIC (Begin n ers All-purpo se Sym bo lic In structio n Co de), 10 Basic In put Output System , see BIOS Basic Rate In terface, see BRI batch m o de (run n in g so ftw are in ), 991 batteries p ortable com p u ters, 939-941 ch argin g, 940 1114 con n ectors, 230 d isch argin g, 940 Li-ion (lith iu m -ion ), 940 Lith iu m -Ion Polym er, 940 NiCad (n ickel cad m iu m ), 939 NiMH (n ickel m etalh yd rid e), 939 p ower m an agem en t, 941-942 p ortable com p u tin g d esign , 911 RTC/ NVRAM, 442-444 sp eakers, 580 ven d ors, 1236 baud (m o dem speeds), 660 BBSs (bulletin bo ard system s), 655 PC trou blesh ootin g resou rces, 1164 beaco n in g (To ken Rin g adapters), 702 beam splitters (CD-ROM drives), 827 bearer ch an n els (ISDN), 671 BEDO (Burst Ex ten ded-DataOut) DRAM, 316 Bell 103 m o dulatio n stan dard, 661 Bell 212A m o dulatio n stan dard, 662 Bell Labs ( m o dem stan dards), 658 ben ch testin g (po w er supplies), 430 load resistors, 430 variable voltage tran sform ers, 430-431 ben ch m arks CPU sp eed s (iCOMP 2.0 in d ex ratin gs), 35 P-ratin gs, 82

boot drives

u p grad in g CPUs, 164-165 3D W in Ben ch 98, 165 CPUm ark32, 165 iCOMP in d ex 2.0, 165 Norton Mu ltim ed ia Ben ch m ark, 165 Norton SI32, 165 SPECfp 95, 165 SPECin t95, 165 SYSm ark/ NT, 165 W in Ben ch 98, 165 W in ston e 98, 165 Ziff-David W in ston e ben ch m ark, 82 ben t m em o ry ch ip leads (m em o ry in stallatio n ), 355 bezels, see faceplates BFx pin s (Pen tium CPUs), 112 bi-level prin tin g, 890 BiCMOS (Bipo lar Co m plem en tary Metal Ox ide Sem ico n ducto r), Pen tium CPUs, 108 bidirectio n al parallel po rts, 595 IEEE 1284, 596-597 bin ary (base 2) n um berin g system (address buses), 40 bin ary digits, see bits bio degradable clean ers, 1016 BIOS (Basic In put Output System ), 13, 16, 208-209, 305, 958, 1032-1033 AMI, 210-214 d iagn ostics, 213 ID strin gs, 211-213 ATA-3 IDE (In tegrated Drive Electron ics), 621-623 au tom atic d rive typ in g, 766 au xiliary rou tin es, 304 Award , 214 COMMAND.COM (sh ell), 1036 com m an d file search p roced u re, 1037-1039 resid en t com m an d s, 1037 tran sien t com m an ds, 1037 con ten ts, 26 d irect h ard ware access, 1035 d u p licatin g IBM BIOS, 17 EPROM (erasable p rogram m able read -on ly m em ory), 208 error m essages, 222-224 Flash ROM, 217, 958 recovery, 220-221 u p grad es, 217-219

h ard d isk p aram eters AMI ROM BIOS, 1409-1410 Award ROM BIOS, 1411-1412 Com p aq Deskp ro 386, 1408-1409 IBM AT/ PS/ 2, 1406-1408 Ph oen ix ROM BIOS, 1412-1413 u ser-d efin able d rive typ es, con figu rin g as, 1401-1405 h ard d rive an d SCSI con troller BIOS, 370-372 I/ O system , 1034-1035 IBMBIO.COM (IBM DOS), 1035 IBMDOS.COM (IBM DOS), 1036 IO.SYS (MS-DOS), 1035 MSDOS.SYS (MS-DOS), 1036 IBM PC (version s), 1104-1105 IBM PC AT h ard d rive con troller h ead step rate, ch an gin g, 1140 h ard d rive tables, 1136-1140 version s, 1136 IBM PC XT (version s), 1105, 1119 IML (In itial Microcod e Load ), 221 In terru p t 13h d isk fu n ction s, 1051 In terru p t 13h error cod es, 1052 in terru p ts, 1032-1033 m an u al d rive typ in g, 766 m em ory con flicts, p reven tin g, 380-381 lim itation s, 354 m em ory m an agers, 1035 m oth erboard BIOS, 375-376 OEMs (Origin al Eq u ip m en t Man u factu rers), 209-210 on board (SCSI ad ap ters), 990 Pen tiu m FDIV bu g, 114-115 Pen tiu m p ower m an agem en t bu g, 116 Ph oen ix, 214-215 Pn P (Plu g an d Play) su p p ort, 291-292, 958

1441

p ortable com p u ters (h ard d rive su p p ort), 931 POST au d io error cod es, 985 AMI BIOS, 986 Ph oen ix BIOS, 986-988 POST I/ O p ort cod es, 988-989 POST visu al error cod es, 988 recom m en d ation s, 295 stan d ard in terface, 1034 u p grad in g, 215-216 keyboard con trollers, 216-217 u p grad in g com p on en ts (p ortable com p u ters), 912 VGA, 518 vid eo, 525 flash BIOS, 525 u p grad in g, 525-526 vid eo ad ap ter BIOS, 369-370 see also ROM BIOS BIOS Co m pan io n , 1197 Bipo lar Co m plem en tary Metal Ox ide Sem ico n ducto rs, 108 bit cells, 711 bit erro rs, CD-ROM drives, co rrectin g, 827 bitm ap fo n ts, 879-880 bitm ap graph ics, 875 bits, 9 bu ses, 233-234 bits per in ch , see BPI bits per seco n d, see bps black w ires (po w er sw itch co n n ecto rs), 407 blo ck m o de (MNP Class 1), 666 blo cks (CD-ROM data tran sfer rates), 829 blue w ires (po w er sw itch co n n ecto rs), 407 BNC co n n ecto rs, 690 Th in Eth ern et cable, 694 bo n din g (CPU packagin g), 52 BONDING pro to co l (ISDN), 672 bo o ks, 1236-1237 bo o t disks, creatin g FORMAT.COM, 1036 SYS.COM, 1036 W in d ows 9x, 1036 bo o t drives PC/ XT an d AT d ifferen ces, 25 selectin g (volu m e boot sectors), 1071

1442

boot process

bo o t pro cess, 1042 AUTOEXEC.BAT, load in g, 1047 cen tral h ard ware test, 1043 cold / warm boot ch ecks, 1044 CONFIG.SYS, load in g, 1047 m aster p artition (d isk stru ctu res), viru ses, 1068 POST (Power On Self Test), 1043 ROM (relation sh ip with RAM), 304 sector errors, 1044-1047 MBR (Master Boot Record ), 1045 vid eo ROM errors, 1043 W in d ows 3.x, 1055 386 en h an ced m ode, 1056 p rotected m od e, 1055 stan d ard m od e, 1056 W IN.COM, 1055 XMS m em ory, 1055 W in d ows NT, 1063 NTDETECT.COM, 1063 NTLDR, 1063 W in d ows NT Kern al (NTOSKRNL.EXE), 1063 bo o t secto rs, m aster partitio n (disk structures), 1067-1070 exten d ed DOS p artition s, 1067-1068 m aster boot cod e, 1067 m aster p artition table, 1067 MBR (Master Boot Record ), 1068-1070 p rim ary DOS p artition s, 1067 viru ses, 1068 bo o tin g from CD-ROM d rives, 963 trou blesh ootin g (error m essages), 222 Bo o tstrap Lo ader, 209, 305, 375 ROM BIOS, 26 bo o tup testin g (o ptical drives), 865-866 bo ules (silico n ), 50 bo un cin g keystro kes, 458 BOX (OverDrive steppin gs tables), 123 BOXF (OverDrive steppin gs tables), 123 BOXUF (OverDrive steppin gs tables), 124 BPI (bits per in ch ), 720

bps (bits per seco n d), 660 bran ch predictio n , 106 Dyn am ic Execu tion , 128 Bran ch Target Buffer, see BTB bran ch ed to po lo gy, FireWire (IEEE 1394), 604 BREAK co m m an d (Win do w s 9x DOS), 1414 breako ut bo x es, 1008 breath er filters, 749 BRI (Basic Rate In terface), 671 bridge fun ctio n s (cable m o dem s), 674 brigh tn ess (pix els), 503 bro adban d n etw o rks (CATV), 674 bro ken pin s (in stallin g m em o ry), 355 bro w n w ires (po w er sw itch co n n ecto rs), 407 brush es, clean in g, 1018 BSRAMs (Burst Static RAMs), 50 BTB (Bran ch Target Buffer), Pen tium CPUs, 106 buffers ban d , 884 CD-R (CD-Record able) d rives, 848 CD-ROM d rive, 832 DIMMs, 358 n etwork in terface ad ap ters, 691 bugs (CPUs), 77 386DX CPUs, 90-92 Pen tiu m CPUs, 114-116 work-arou n d u p d ates, 78 buildin g system s, 947-948 assem bly, 968-979 au d io ad ap ters, 966 cables, 967 cases, 949-950 CD-ROM d rives, 963 costs, 947 d isassem bly, 979-980 h ard d isk d rives, 962-963 h ard ware resou rce req u irem en ts, 968 h eat sin ks/ coolin g fan s, 966-967 IRQs, 968 keyboard s, 964 m oth erboard s, 950-961, 972-977 m ou se, 964 p ower su p p lies, 949-950

rem ovable storage, 961-962 ru n n in g CMOS Setu p , 978-979 scaven gin g from cu rren t system , 948 software su p p ort, 968 sp eakers, 966 USB Perip h erals, 966 vid eo ad ap ters, 965 vid eo d isp lays, 965 built-in flo atin g po in t un its, 75-77 m axim u m sp eed s, 76 sp ecification s, 77 built-in I/ O po rts, 960 in tegrated m oth erboard ad ap ters, 961 Su p er I/ O ch ip s, 960 built-in m icro ph o n es (So un d Blaster), 550 built-in po w er pro tectio n system s (po w er supplies), 436 built-in syn ch ro n o us m ath co pro cesso rs (486 CPUs), 93 bulletin bo ard system s, see BBSs bun dled so ftw are (so un d card buyin g tips), 571 burn in g CDs, 846, 964 CD-R (CD-Record able), 847 bu ffers, 848 d ata tran sfer rates, 848 m u ltip le session s, 849 record in g software, 848-849 sp eed s, 847 CD-RW (CD-Rewritable), 847-849 lan d reflectan ce, 850 m u ltiread sp ecification s, 850 Perase settin g, 850 Pwrite settin g, 850 read in g d iscs, 850 W ORM (write-on ce, read m an y), 846 burst cach e, 958 Burst Ex ten ded-Data-Out, see BEDO DRAM burst m o de cyclin g, 314 Burst Static RAMs, 50 Bus Frequen cy pin s, see BFx pin s bus slo ts (LPX m o th erbo ards), 171 Bus Sn o o pin g (Level 1 cach e), 42

buying tips

buses, 232-234 8-bit (PC/ XT class), 24 16/ 32/ 64 bit (AT class), 24 ad d ress, 40-41 bin ary (base 2) n u m berin g system s, 40 d igits, 40 see also m em ory, ad d ressable AGP (Accelerated Grap h ics Port), 186 backsid e, see DIB (Du al In d ep en d en t Bu s arch itectu re) Card bu s (PCMCIA), 24 CD-ROM d rive con n ection s, 832-835 EIDE, 834 IDE/ ATAPI, 833 p arallel p ort, 834-835 SCSI, 833 ch ip set su p p ort, 957 CPUs, 38 d ata wid th s, 22-23 DMA ch an n els (Direct Mem ory Access), 275 8-bit ISA bu s, 275 16-bit ISA bu s, 275-276 EISA bu s, 276-277 MCA bu s, 277 EISA (Exten d ed ISA), 24, 187 en u m erators (W in d ows 9x Pn P), 1060 extern al, 39, 105, 132, 143 FireW ire (IEEE 1394), 604-605 I/ O (exp an sion slots), 238-239 AGP p orts, 268-269 EISA (Exten d ed ISA) bu s, 246-249 ISA bu s, 239-244 local bu ses, 250-252 MCA (Micro Ch an n el Arch itectu re) bu s, 245-246 PCI bu s, 256-269 VL (VESA local) bu s, 252-256 I/ O p ort ad d resses, 277-281 IDE (In tegrated Drive Electron ics), 613-614 in tern al, 39 IRQs (In terru p t ReQu est ch an n els), 271-272 8-bit ISA bu ses, 272 16-bit ISA bu ses, 272-274 trou blesh ootin g, 274-275

ISA (In d u stry Stan d ard Arch itectu re), 23 local accelerators (82433NX ch ip s), 190 m asterin g, 268 altern ate p rocessors, 42 ATA-2/ ATA-3 IDE, 624 MCA bu ses, 245 MCA IDE (In tegrated Drive Electron ics), 626 p ower su p p ly, 392 m em ory bu s, 237-238 m ice, 484 m obile system s AGP, 929 PCI, 927, 929 PCI, 24 PCMCIA, 24 p rocessor bu s, 234-237 PS/ 2 MCA bu s (Micro Ch an n el Arch itectu re), 24 recom m en d ation s, 295 resou rces, 270 SCSI (Sm all Com p u ter System In terface), 627-628 ANSI stan d ard s, 628-630 ASPI (Ad van ced SCSI Program m in g In terface), 645 cablin g, 634-639 com m an d s, 633 con figu rin g, 640-646 d ifferen tial, 630-631 Fast SCSI, 632 Fast-40 SCSI, 632 Fiber Ch an n el SCSI, 632 h ost ad ap ters, 653 IDE com p arison s, 646-653 p in ou ts, 634-635 Plu g an d Play, 644-645 SCSI-2 (X3), 631-632 SCSI-3, 632-633 sin gle-en d ed , 630-631 syn ch ron ou s n egotiation , 644 term in ation , 632-633, 639-640 Ultra SCSI (Fast-20), 632 W id e SCSI, 632 slot ad ap ters (MCA to ISA), 989 slot typ es (PC/ XT an d AT d ifferen ces), 25

1443

sp eed s 100MHz, 43 66MHz, 35-37, 43 top ologies, 696 USB (Un iversal Serial Bu s), 600-604 vid eo ad ap ters, 531 AGP (Accelerated Grap h ics Port), 532-533 EISA, 531 ISA, 531 MCA, 531 PCI, 533 PCI (Perip h eral Com p on en t In tercon n ect), 532 sp eed s, 531 VL-Bu s, 533 VL-Bu s (VESA local bu s), 531 wid th s (vid eo m em ory), 529 XT IDE (In tegrated Drive Electron ics), 626 busin ess applicatio n s m u ltim ed ia, 556-557 tu torials, 557 sou n d card s, 561 cost, 561 n oise, 562 p rod u ctivity, 562 butto n s (m o use), 481 Butto n s Page (Win do w s 9x Mo use Co n tro l Pan el), 485 buyin g tips m icrop h on es, 581 m on itors, 509 an alog m on itors, 510 con trols, 512 d ot p itch , 511 freq u en cy ch oices, 509-510 glare filters, 512 screen size, 511 testin g, 513 u sage en viron m en ts, 512 p ortable com p u ters, 913 p ower su p p lies, 433 form factors, 433 p rop rietary d esign s, 433 p rin ters com bin ation d evices, 894 cost of con su m ables, 895-896 fax m od em / scan n er, 894 p ap er typ es, 895

1444

buying tips

p rin ter/ cop iers, 894 selection criteria, 893-896 sp eed , 894-895 sou n d card s bu n d led software, 571 Sou n d Blaster com p atibility, 571 u ser n eed s, 570-571 sp eakers freq u en cy resp on se, 580 THD (Total Harm on ic Distortion ), 580 wattage, 580 video adapters (ch ipsets), 526 byte values (MBR partitio n talbes), 1070

C C6 Win ch ip (IDT), 126 sp ecification s, 127 C6 Win ch ip In tel-co m patible CPUs (IDT), 82 cables flop p y d isk d rives, 777-778 m od em s (CATV), 674 brid ge fu n ction s, 674 Eth ern et in terfaces, 674 HFC (h ybrid fiber/ coax), 674 h u bs, 674 Cable Select (CSEL) sign als, 617 cablin g ATA IDE, 616 bu ild in g system s, 967 con n ectin g, 975-976 extern al, 977 d efective, 977 flop p y d isk d rives, 777-778 keyboard s, 474 d isassem blin g keyboard s, 476 IBM (p art n u m bers), 478 IDE (In tegrated Drive Electron ics), 612-613 LANs, 692 coaxial, 694 d istan ce lim itation s, 699 fiber-op tic, 695 in stallation s, 697-698 n etwork top ologies, 695-697 selectin g, 698-699 twisted p air, 692-693

lap top com p u ter lin ks, 599 loop back tests, 592-593 m od em (n u ll), 676 m ou se, 481 ribbon (in tern al d rive in stallation s), 858-859 SCSI, 634 P-cables, 857 sin gle en d ed , 635-639 term in ators, 639-640 USB (Un iversal Serial Bu s), 602 Y sp litters, 404 cach able RAM (300MHz MMX Pen tium II CPUs), 144 cach e 2-W ay Set Associative (Pen tiu m CPUs), 105 430FX ch ip set, 191 430HX ch ip set, 192 486DX CPUs, 96 Am 5x86(TM)-P75 CPU, ju m p erin g, 104 cach e m iss, 320 CD-ROM d rives, 832 ch ip typ es, 958 con trollers, 320-322 h ard d isk p erform an ce, 757-767 Cyrix 6x86/ 6x86MX CPUs, 157 Cyrix/ TI 486, 104 fou r-way set associative (Pen tiu m Pro CPUs), 130 in tern al (Pen tiu m CPUs), 107-108 L1 (Level 1), 41 386 system s, 320 4-way set associative, 42 486 CPUs, 92 AMD-K6 CPUs, 153 Bu s Sn oop in g, 42 clock m u ltip led CPUs, 41 L2 (Level 2) com p arison s Nexgen Nx586 CPUs, 152 Pen tiu m II CPUs, 144 Pen tiu m Pro CPUs, 130-132 Pen tiu m -MMX im p rovem en ts, 48 write-back (Pen tiu m fam ily), 42 write-th rou gh (486 fam ily), 42

L2 (Level 2), 41-43 4-way set associative, 42 DIB arch itectu re, 49 L1 (Level 1) com p arison s, 321 Pen tiu m II CPUs, 144 Pen tiu m Pro CPUs, 132-133 Level 2 secon d ary, 958 m axim u m am ou n ts, 322 m em ory, SRAM (Static RAM), 319-322 m obile system s, 927 m oth erboard s (recom m en d ation s), 294 Pen tiu m CPUs, 105 Pen tiu m II CPUs, 143, 202 Pen tiu m Pro CPUs, 130, 202 150 MHz m od el, 133 166 MHz m od el, 133 180 MHz m od el, 133 200 MHz m od el, 133 200MHz 1M L2 cach e m od el, 133 p ip elin e bu rst (ch ip set su p p ort), 957 p rogram s (h ard d isk p erform an ce), 757-767 secon d ary (Level 2), m obile system s, 919, 927-928 sp eed s relative to CPU sp eed s, 43 two-way associative, 130 write-back, 42, 886 Am 5x86(TM)-P75 CPU, 103-104 Pen tiu m CPUs, 105, 108 Pen tiu m -MMX CPUs, 113 write-th rou gh cach e 486 fam ily, 42 Am 5x86(TM)-P75 CPU, ju m p erin g, 104 Pen tiu m CPUs, 108 Cach e On A Stick, see COAST cach eable RAM (Pen tium II CPUs) 233MHz MMX m od els, 144 266MHz MMX m od els, 144 333MHz MMX m od els, 143 350 an d 400 MHz MMX m od els, 143 Pen tiu m II CPUs, 143 CACP (Cen tral Arbitratio n Co n tro l Po in t), 245

CD-ROM s

caddies (CD-ROM drives), 825, 835 altern atin g d iscs, 836 cost, 836 Calibrate utility (No rto n ), 993, 1094 calibratio n , m o use, 484 Bu tton s Page (W in d ows 9x Mou se Con trol Pan el), 485 Gen eral Page (W in d ows 9x Mou se Con trol Pan el), 486 Motion Page (W in d ows 9x Mou se Con trol Pan el), 486 Poin ters Page (W in d ows 9x Mou se Con trol Pan el), 486 caller ID (m o dem s), 670 CAM (Co m m o n Access Meth o d), 645 CAM ATA (Co m m o n Access Meth o d AT Attach m en t), 614 Can adian Stan dards Agen cy, see CSA can n ed air, 1015 capacities CD-ROMs, 823 trou blesh ootin g, 868 DIMMs, 326 DVD (Digital Versatile Disc), cap acities, 852 flop p y d isk d rives, 1101 h ard d isk d rives, 759-761 m agn etic storage, 718-719 QIC tap e d rives, 811 RAM ch ip s, 336-338 rep lacin g, 353-354 SIMMs, 326 capacitive keysw itch es, 457 capacito rs (DRAM), 312 capture bo ards, 537 vid eo ad ap ters, 538 cap tu re from VCRs, 538 cap tu re from VHS sign als, 538 NTSC sign als, 540 card edge co n n ecto rs (in tern al drive in stallatio n s), 858-859 Card Edge Lo w Pro file, see CELP Card Services (PC Cards), 935-936 Card/ Edge co n n ecto rs (8-bit ISA bus), 240 Cardbus (PCMCIA), 24, 933 carpel tun n el syn dro m e (ergo n o m ic keybo ards), 473

cartridges d rives, 799-802 Jaz d rives, 801-802 Sp arq d rives (m axim u m root d irectory), 802804, 1074 Syq u est d rives, 801 tap e d rives, see tap e d rives Zip d rives, see Zip d rives p ortable com p u ter m em ory, 930 cases, 27, 391 bu ild in g system s, 949 ATX m oth erboard s, 949-950 Baby-AT m oth erboard s, 950 d esktop , 950 m in i-tower, 950 sizes, 949 tower, 950 p ositive-p ressu re-ven tilation d esign , 399 sn ap togeth er, 1004 Cassette (ROM) BASIC (erro r m essages), 222-224 cassette tape reco rders, 222 Catego ry 3 UTP cablin g, 698 cath o de ray tubes, see CRTs CATV n etw o rks, 673 ban d wid th , 674 asym m etrical n etworks, 674 tu n ers (cable m od em s), 674 cable m od em s, 674 brid ge fu n ction s, 674 Eth ern et in terfaces, 674 HFC (h ybraid fiber/ coax), 674 h u bs, 674 p erform an ce, 675 secu rity, 675 CAV (Co n stan t An gular Velo city, 826 CBT (Co m puter-Based Train in g), 540 CCITT (Co n sultative Co m m ittee o n In tern atio n al Teleph o n e an d Telegraph ), 658 CCS (Co m m o n Co m m an d Set), 629 CD Audio co n n ecto rs, 231

1445

CD Audio In co n n ecto r (in stallin g so un d cards), 572 CD co m m an d (Win do w s 9x DOS), 1414 CD Ex tra, see en h an ced m usic CDs CD Plus, see en h an ced m usic CDs CD-DA CD-ROM fo rm at, 840 CD-Player (Win do w s 9x / NT), 867 CD-R (CD-Reco rdable) drives, 847, 964 m u ltip le session s, 849 Oran ge Book sp ecification , 839 recom m en d ed in terfaces, 834 record in g software, 848-849 sp eed s, 847 W ORM (write-on ce, read m an y), 846 CD-ROM Ready discs (m ix ed m o de CDs), 844 CD-ROM-XA (Ex ten ded Arch itecture), 840-841 d ata typ es Mod e 1, 841 Mod e 2, Form 1, 842 Mod e 2, Form 2, 842-843 in terleavin g, 841-843 m u ltip le session record in g, 840-841 m u ltisession read in g, 843 CD-ROMs, 28-29, 823-825, 963 access tim es, 831-832 au d io CD d ifferen ces, 826 beam sp litters, 827 bootin g from , 963 bu ffers, 832, 848 cad d ies, 825 cap acities, 823 carin g for, 825 CD-R (CD-Record able), 964 recom m en d ed in terfaces, 834 CD-RW (CD-Rewritable), 964 recom m en d ed in terfaces, 834 con n ectors, sou n d card , 569-570 con figu rin g as p rim ary (m aster) d rive, 855 as secon d ary (slave) d rive, 855 SCSI d rives, 856

1446

CD-ROM s

d ata tran sfer rates, 848 d rive sp eed s, 830 h ard d isk com p arison s, 831 m u ltim ed ia, 830 u p grad e issu es, 830 DVD-ROM d rives, 964 error correction , 827 extern al d rives con n ectin g, 856-858 SCSI ch ain s, 861 form ats CD-DA (Digital Au d io), 840 CD-ROM-XA (Exten d ed Arch itectu re), 840-843 High Sierra, 839 ISO 9660 d ata stan d ard , 839 m ixed m od es, 843-844 Ph otoCDs, 844-846 h istory of, 824 in stallin g d rives, 854, 862-863 bootu p testin g, 865-866 CD-ROM d evice d river, 864 DOS CD-ROM d evice d river, 864 DOS SCSI ad ap ter d river, 863 in terface ad ap ters, 854 MSCDEX.EXE, 864-865 W in d ows 3.x, 866 W in d ows 9x, 866 W in d ows NT 4.0, 866 in terfaces ATA/ IDE, 830 SCSI, 830 in tern al d rives con n ectin g, 858-859 SCSI ch ain s, 860-861 in terp olatin g m issin g d ata, 828 lan d s, 850-852 laser d iod es, 827 load in g m ech an ism s, 835-836 cad d ies, 835-836 trays, 836-837 m ass-p rod u cin g, 825 PD-ROM com bo d rives, 963 p h otod etector, 827 p h ysical in terface, 832-835 EIDE, 834 IDE/ ATAPI, 833

p arallel p ort, 834-835 SCSI, 833 p layback, CAV (Con stan t An gu lar Velocity), 826 p ortable com p u ters, 931 read in g, 825 lan d s, 825 p its, 825 tracks, 825 record in g tech n iq u es CLV (Con stan t Lin ear Velocity), 826 P-CAV, 826 sectors, 826, 829 server m otors, 827 software storage n eed s, 828 sp ecification s, 829, 837-846 access tim es, 831-832 bu ffers, 832 d ata tran sfer rates, 829-830 d rive sealin g, 837 extern al en closu re, 837 in tern al en closu re, 838 load in g m ech an ism s, 835-836 p h ysical in terface, 832-835 self-clean in g len ses, 837 trou blesh ootin g, 867 cap acity p roblem s, 868 clean in g d iscs, 867 clean in g read len ses, 868 W in d ows 9x p roblem s, 868 writable, 846 CD-R (CD-Record able), 847-849 CD-RW (CD-Rewritable), 849-850 system backu p s, 1012-1013 W ORM (write-on ce, read m an y), 846-847 Yellow Book stan d ard , 839-842 CD-RW (CD-Rew ritable) drives, 847-849, 964 lan d reflectan ce, 850 m u ltiread sp ecification s, 850 Oran ge Book sp ecification , 839 Perase settin g, 850 Pwrite settin g, 850 read in g d iscs, 850 recom m en d ed in terfaces, 834

CDC, ATA IDE, see ATA IDE CDs (audio ), playin g, 560 Celero n (lo w -en d Pen tium II CPUs), 67, 151 CELP (Card Edge Lo w Pro file), 958 Cen taur C6 Win ch ip (IDT), 126 sp ecification s, 127 Cen tral Arbitratio n Co n tro l Po in t, see CACP Cen tral Pro cessin g Un its, see CPUs Cen tro n ics latch -style co n n ecto rs (SCSI), 634 ceram ic Ceram ic Pin Grid Array (CPU p ackagin g), 37 Mem Cor glass, 733 certificatio n s (po w er supplies), 417 CGA (Co lo r Graph ics Adapter), 366, 515 A/ N (alp h an u m eric) m od e, 515 APA (all p oin ts ad d ressable) m od e, 515 resolu tion , 515 RGB m on itors, 515 screen flicker, 515 sn ow, 515 ch ain s FATs, 1076 SCSI, 860 all extern al d evices, 861 in tern al an d extern al d evices, 861 in tern al ch ain an d term in ation , 861 ch an n el bit m o dulatio n , DVD (Digital Versatile Disc), 852 ch an n els DMA (Direct Mem ory Access), 275 8-bit ISA bu s, 275 16-bit ISA bu s, 275-276 EISA bu s, 276-277 MCA bu s, 277 IRQs (In terru p t ReQu est ch an n els), 271-272 8-bit ISA bu ses, 272 16-bit ISA bu ses, 272-274 trou blesh ootin g, 274-275 ISDN (In tegrated Services Digital Network) bearer, 671 d elta, 671 MIDI, 553

citrus-based cleaners

ch aracter co de ch arts (Hex adecim al to ASCII co n versio n s), 1326-1334 Ch aracter Map utility (Win do w s), 470 ch aracters ASCII cod es, 1325 EBCDIC cod es, 1334 ch aracters per seco n d, see cps ch aracters sets in m em o ry (EGA adapters), 516 ch argin g po rtable co m puter batteries, 940 Ch arism a, 1212 ch assis (cases), 27 Ch assis In trusio n (Security) co n n ecto rs, 231 CHCP co m m an d (Win do w s 9x DOS), 1414 CHDIR co m m an d (Win do w s 9x DOS), 1414 Ch eaperNet, see Th in Eth ern et cable Ch eckit Pro diagn o stic so ftw are, 992 Ch eckIt Pro fessio n al Editio n , 1231 Ch eckIt v5.0, 1231 ch em icals, clean in g, 1015 1,1,1 trich loroeth an e, 1015 biod egrad able citru s-based , 1016 con tact clean ers/ lu brican ts, 1016-1017 d u sters (com p ressed gas), 1017 fed eral regu lation , 1015 fin d in g, 1019 silicon e lu brican ts, 1018 stan d ard , 1016 ven d ors, 1244 ch ip creep, 324 reseatin g ch ip s, 1019-1020 m em ory SIPPs, 1019 ch ip ex tracto rs, 1001 ch ips CPU m an u factu rin g testin g, 52 yield s, 53 m em ory, see p h ysical m em ory ROM, see ROM ch ipset level do cum en tatio n , 1156, 1160-1162 Ch ipset Setup o ptio n s (tro ublesh o o tin g so un d cards), 579

ch ipsets, 183-185, 954, 957-958 3D grap h ics accelerators, 543-545 AGP (Accelerated Grap h ics Port) In tel 440LX, 440EX an d 4k40BX, 532 Alad d in M1510 ch ip set, 956 Ali (Acer Laboratories, In c), 197 AVI Ap ollo MVP3, 956 Pen tiu m II p rocessors, 205 Pen tiu m Pro p rocessors, 205 Pen tiu m p rocessors, 197-198 bu s su p p ort, 957 d ocu m en tation , 297-298, 957 EDO RAM su p p ort, 316 EISA bu s, 185 FireW ire (IEEE 1394), 605 In tel, 19-20, 185-186 430FX PCIset, 956 430HX PCIset, 955 430TX PCIset, 955 430VX PCIset, 955 440BX AGPset, 955 440FX PCIset, 955 440LX AGPset, 955 486 p rocessors, 187 82350, 187 m od el n u m bers, 186 North Brid ges, 186 p arity su p p ort, 959 Pen tiu m II p rocessors, 200-207 Pen tiu m Pro p rocessors, 199-207 Pen tiu m p rocessors, 187-194 Sou th Brid ges, 186 lim itation s on m em ory, 323, 354 m obile Pen tiu m CPUs, 929 430MX PCIset, 929 430TX PCIset (Pen tiu m / MMX), 929 440BX AGPset ch ip set, 929 Mobile 440BX AGPset, 929 m oth erboard s, 26 Op ti 82C550 Vip er-DP, 956 p arity m em ory su p p ort, 347

1447

Pen tiu m Pro m oth erboard s, 134 recom m en d ation s, 296 SDRAM su p p ort, 316 SiS (Silicon in tegrated System s), 198 Pen tiu m II p rocessors, 207 Pen tiu m p rocessors, 198-199 variable freq u en cy syn th esizer circu its (m oth erboard an d CPU sp eed s), 36 VIA Tech n ologies Pen tiu m II p rocessors, 206-207 Pen tiu m p rocessors, 194-197 vid eo accelerator ch ip s, 526 bu yin g tip s, 526 cop rocessin g, 526 fram e-bu ffers, 526 u p grad in g, 526 CHKDSK co m m an d, 1088, 1415 FAT cop ies, ch eckin g, 1077 op eration , 1090-1091 / F p aram eter, 1091 syn tax, 1089 / F (Fix) switch , 1089 / V (Verbose) switch , 1089 d , 1089 fragm en ted files, 1089 CHKSTATE.SYS (Win do w s 95 CD-ROM), 1417 CHOICE.COM (Win do w s 9x DOS), 1415 CHS (Cylin der Head Secto r), 979 ad d ressin g, BIOS (ATA-2/ 3 IDE), 622 cigarette sm o ke (clean in g system s), 1014 Cin epak co dec (VFW), 541 circuit bo ards (flo ppy disk drives), 775 circuit sizes CPUs, 62 Pen tiu m CPUs, 105 circuit sw itch in g (LANs), 681 Cirrus 5436/ 5446/ 7548 video adapters, 539 CISC (Co m plex In structio n Set Co m puter), 47, 105 citrus-based clean ers, 1016

1448

clamps

clam ps, 1003 Class 1 MNP blo ck m o de, 666 Class 2 MNP stream m o de, 666 Class 3 MNP stream m o de, 666 Class 4 MNP stream m o de, 666 Class 5 MNP stream m o de, 666 classic steppin gs (Pen tium CPUs), 118-120 clean in g, 1013 board s an d con n ectors, 1020 bru sh es an d swabs, 1018 CD-ROMs, 867 d rive sealin g, 837 read len ses, 868 self-clean in g len ses, 837 ch em icals, 1015 1,1,1 trich loroeth an e, 1015 biod egrad able citru sbased , 1016 con tact clean ers/ lu brican ts, 1016-1017 d u sters (com p ressed gas), 1017 fed eral regu lation , 1015 fin d in g, 1019 silicon e lu brican ts, 1018 stan d ard , 1016 con n ectors, 1021 con tacts, 1021 d ep ressu rization d esign s, 1014 flop p y d isk d rives, 793-794 forced -air coolin g system s, 1013-1014 keyboard s, 477, 1022 rem ovin g keycap s, 477 sp ills, 477 keyswitch es (Stabilan t 22a), 456 m ice, 487 m ou se, 1022 n egative p ressu rization d esign s, 1014 p ower su p p lies, 1020 su p p lies, ven d ors, 1244 tools, 1015 vacu u m clean ers, 1017 Clean Sw eep, 1222 ClickLo ck feature (Micro so ft In telliMo use), 491 clien t/ server n etw o rks LANs, 678 clien t software, 680 clien ts, 679 software, 680

clip-o n h eat sin ks, 1006 CLKMUL (Clo ck Multiplier), 94 clo ck speeds CLKMUL (Clock Mu ltip lier), 94, 105 clock sign als, 34 CPUs, 33-34 386DX CPUs, 88 486 CPUs, 93-94, 98 486DX CPUs, 95 80286 CPUs, 85 8088 CPUs, 84 Am 5x86(TM)-P75 CPU, 103 AMD K5 CPUs, 126 AMD-K6 CPUs, 155 clock d ou blin g, 37 com p arin g system s, 36 Cyrix 6x86/ 6x86MX, 157-158 Cyrix/ TI 486, 104 iCOMP 2.0 in d ex ratin gs, 35 in stru ction execu tion efficien cy, 34 m arkin g sch em es, 37 m axim u m safe sp eed s, 37, 161-162 MHz, 34 m oth erboard sp eed s, 35-36 overclockin g, 37 Pen tiu m CPUs, 105, 110-113 Pen tiu m II CPUs, 141-144 Pen tiu m Pro CPUs, 133-134 Pen tiu m -MMX CPUs, 113 cycle tim e com p arison s, 313 d ou blin g (DX2/ OverDrive p rocessors), 99-101 OverDrive p rocessors (Pen tiu m ), 59 PCI bu ses (AGP), 269 triplin g (DX4 processors), 101 see also clock m u ltip liers; CPUs;overclockin g clo cks (CMOS RAM) ad d resses, 224-227 d iagn ostics statu s byte, 227-228 d ou blin g, CPU clock sp eed s, 37 DX2/ OverDrive p rocessors, 99-101 DX4 p rocessors, 101

m u ltip liers, 35, 41 AMD K5 CPUs, 126 Pen tiu m CPUs, 105, 111-112 Pen tiu m II CPUs, 143 Pen tiu m Pro CPUs, 132 see also clock sp eed s; overclockin g sign als, 34, 713 sp eed s, see clock sp eed s trip lin g, 101 clo n es (PC/ XT fo rm facto rs), 395 clo sed-lo o p feedback m ech an ism , 742 CLS co m m an d (Win do w s 9x DOS), 1414 clusters d isk sp ace allocation s, 1048-1049 overwritin g files, 1049 FAT16 p artition lim its, 1085 FAT32 m axim u m s, 1082 sizes, 1083-1084 FAT (File Allocation Tables), 1076-1077 ch ain s, 1076 d efau lt flop p y d isk clu ster sizes, 1077-1078 d efau lt h ard d isk clu ster sizes, 1078-1079 FDISK cop ies, 1077 h exad ecim al n u m bers, 1076 flop p y d isk d rives (d efau lt sizes), 781 lost, 1086-1087 rem ap p in g (NTFS), 1097-1098 CLV (Co n stan t Lin ear Velo city), 826 CMOS (Co m plem en tary Metal-Ox ide Sem ico n ducto r), 26, 88, 224 ad d resses, 224-227 d iagn ostics statu s byte, 227-228 m em ory/ clock (PC/ XT an d AT d ifferen ces), 25 record in g in form ation (d isassem blin g system s), 979-981 Setu p p rogram , ru n n in g, 209, 305, 375, 978-979 CMOS Ch ecksum erro r, 219

communications

CMYK co lo r m o del, 890 COAST (Cach e On A Stick), 958 co ax ial cable, 694 co de, m ach in e lan guage, po rtin g, 1032 co decs (co m pressio n / deco m pressio n ), 540-541 JPEG (Join t Ph otograp h ic Exp erts Grou p ), 541 MPEG (Motion Pictu res Exp ert Grou p ), 541 VFW (Microsoft Vid eo for W in d ows) Cin ep ak, 541 In d eo, 541 Microsoft Vid eo 1, 541 co den am es (CPUs), 79 co des ASCII ch aracters, 1325 EBCDIC ch aracters, 1334 error DOS In terru p t 13h , 1052 POST au d io, 985-988 POST I/ O p ort, 988-989 POST visu al, 988 escap e cod es, 877 co ercivity, 790 co ld bo o ts, 1044 co ld so lder jo in ts, 1006 co llisio n s, packet, 700-701 co lo r 8-bit, 528 16-bit, 528 24-bit, 528 32-bit, 529 VGA, 518 d ep th LCDs, 917 W in d ows Disp lay Con trol Pan el, 534 p alettes DTV (Destop Vid eo), 540 VESA SVGA stan d ard s, 523 vid eo m em ory d isp lay req u irem en ts, 527-529 XGA ad ap ters, 520 su m m in g, VGA (Vid eo Grap h ics Array), 518 Co lo r Graph ics Adapter, see CGA co lo r in kjet prin ters, 888, 892 co lo r laser prin ters, 892 co lo r LCDs (liquid crystal displays), 503

co lo r m o n ito rs, 503-504 co lo r prin tin g, 890-891 cost of p rin ters, 891 d ye su blim ation p rin ters, 893 in kjet p rin ters, 892 laser p rin ters, 892 th erm al wax tran sfer p rin ters, 893 co lo r super-tw ist n em atic, see CSTN co lo rs, palettes VGA (Vid eo Grap h ics Array), 518 XGA-2 ad ap ters, 520 COM po rts IRQs, trou blesh ootin g, 274-275 m ou se IRQ con flicts, 488 serial m ou se con n ection s, 482 see also serial p orts, 590 co m bin atio n devices (prin ters), 894 fax m od em / scan n er, 894 p rin ter/ cop iers, 894 co m bo drives flop p y d isk d rives, 961 CD-ROM, 963 co m m an d lin e o ptio n s (MSCDEX.EXE), 865 COMMAND.COM DOS sh ell, 1036 com m an d file search p roced u re, 1037-1039 resid en t com m an d s, 1037 tran sien t com m an d s, 1037 W in d ows 9x DOS, 1415 co m m an ds ATA IDE, 617-618 n on -in telligen t, 619 DOS, 1036, 1413 com m an d file search p roced u re, 1037-1039 extern al W in d ows 9x, 1415-1416 in tern al W in d ows 9x, 1414-1415 on W in d ows 95 CD-ROM, 1417 on W in d ows 98 CD-ROM, 1417 resid en t, 1037

1449

retired for W in d ows 9x, 1417-1418 SYS, 1040-1041 tran sien t, 1037 FAT file system u tilities CHKDSK, 1088-1091 RECOVER, 1091 SCANDISK, 1091-1092 PCL (Prin ter Con trol Lan gu age), 873-874 p ort (d isk con trollers), 1052-1053 ROM BIOS (in terru p ts), 1032-1033 SCSI, 629, 633 q u eu in g, 633 COMMDLG.DLL (Win do w s 3.11 updates), 1054 Co m m o n Access Meth o d AT Attach m en t, see CAM ATA in terface Co m m o n Co m m an d Set, see CCS co m m un icatio n s, 655 CATV n etworks, 673 ban d wid th , 674-675 cable m od em s, 674 p erform an ce, 675 secu rity, 675 d irect cable con n ection s, 676 n u ll m od em cables, 676 software, 677 ISDN (In tegrated Services Digital Network), 671 bearer ch an n els, 671 BONDING p rotocol, 672 BRI (Basic Rate In terface), 671 d elta ch an n els, 671 in stallin g con n ection s, 672 Mu ltilin k PPP p rotocol, 672 NFAS (Non -Facility Asssociated Sign alin g), 672 PRI (Prim ary Rate In terface), 671 S/ T (Su bscriber/ Term in ation ) In terface, 672 term in al ad ap ters, 672 U-In teface, 672

1450

communications

LANs (local area n etworks), 678, 684 100Mbp s Eth ern et, 704-705 ATM (Asyn ch ron ou s Tran sfer Mod e), 705 baseban d n etworks, 678 cablin g, 692-699 circu it switch in g, 681 clien t software, 680 clien t/ server n etworks, 678 d ata en cap su lation , 684 d ata lin k layer p rotocols, 699 FDDI (fiber d istribu ted d ata in terface), 703 IPX, 708 NetBEUI, 708 n etwork in terface ad ap ters, 688-692 NICs, 678 OSI Referen ce Mod el, 681-683 p acket switch in g, 681 p eer-to-p eer n etworks, 679-680 servers, 686-688 stacks, 681 TCP/ IP, 706-708 workstation s, 686 laser p rin ter p rin tin g p rocess, 883 leased lin es, 673 T-1 con n ection s, 673 T-3 con n ection s, 673 m od em s, 656 56K m od em s, 667-669 d ata bits, 657 d ata-com p ression stan d ard s, 664-665 error-correction p rotocols, 663-664 fax m od em stan d ard s, 666-667 m od u lation stan d ard s, 660-663 N-8-1 con n ection s, 657 p arity, 657 p rop rietary stan d ard s, 665-666 recom m en d ation s, 670-671 stan d ard s, 658 start bits, 656-657 stop bits, 656-657 p rotocols (d ata lin k layer), 700-702

COMP co m m an d (retired fo r Win do w s 9x ), 1418 Co m pact Video Co ded, see Cin epak Co m paq, 19 ATA IDE, see ATA IDE Co m paq BIOS (erro r m essages), 222-223 Co m paq Deskpro 386 h ard d isk p aram eters, 1408-1409 co m patibility backward (32-bit p rotected m od e CPUs), 44 keyboard s (au to switch in g), 453 m em ory u p grad es (p ortable com p u ters), 930 NTFS file system s, 1096 secu rity, 1096-1097 OverDrive p rocessors, 163-164 overh eatin g, 163 Sou n d Blaster (sou n d card bu yin g tip s), 571 u p grad in g p ortable com p u ters, 912 Co m plex In structio n Set Co m puter, see CISC Co m plim en tary Metal-Ox ide Sem ico n ducto r (CMOS), 26, 88, 224 ad d resses, 224-227 d iagn ostics statu s byte, 227-228 m em ory/ clock (PC/ XT an d AT d ifferen ces), 25 record in g in form ation (d isassem blin g system s), 979-981 Setu p p rogram , ru n n in g, 209, 305, 375, 978-979 co m po n en t level do cum en tatio n , 1156 co m po n en ts bu ild in g system s, 948 assem bly, 968-979 au d io ad ap ters, 966 cables, 967 cases, 949-950 CD-ROM d rives, 963 d isassem bly, 979-980 h ard d isk d rives, 962-963 h ard ware resou rce req u irem en ts, 968 h eat sin ks/ coolin g fan s, 966-967 keyboard s, 964

m oth erboard s, 950-961, 972-977 m ou se, 964 p ower su p p lies, 949-950 rem ovable storage, 961-962 ru n n in g CMOS Setu p , 978-979 software su p p ort, 968 sp eakers, 966 USB Perip h erals, 966 vid eo ad ap ters, 965 vid eo d isp lays, 965 form factors, see form factors IBM PC AT, 1131-1132 IBM PC XT, 1117 IBM Portable PCs, 1126 p ower con su m p tion , 418-423 p ower m an agem en t, 423 Ad van ced Power Man agem en t, 423-425 En ergy Star System s, 423 testin g, 989-991 #1-Tu ffTEST, 994 AMIDiag, 992 Ch eckit Pro, 992 Micro-Scop e, 993 n etwork in terfaces, 990-991 Norton Utilities, 993-994 op eratin g system s, 995-998 PC Tech n ician , 994 PC-Diagn osys, 994 POST (Power-On Self Test), 985-989 QAPlu s/ FE, 994-995 SCSI d evices, 989-990 th erm al sh ock, 421-422 W in d ows NT, 1063-1064 HAL (h ard ware abstraction layer), 1063 W in d ows NT Execu tive, 1064 co m po site video sign als, 542 co m pressed gas (dusters), 477, 1017 vacu u m clean ers, 1017 co m pressio n d isk Dou bleSp ace (MS-DOS 6.0), 1040 Dou bleSp ace (MS-DOS 6.2), 1040 DriveSp ace (MS-DOS 6.22), 1040

connectors

sou n d card d ata, 568 ADPCM (Ad ap tive Differen tial Pu lse Cod e Mod u lation , 569 MPEG (Motion Pictu res Exp erts Grou p s), 569 vid eo (cod ecs), 540-541 co m po site ferrite h eads, 737 Co m pTIA A+ Co re Ex am in atio n , preparin g fo r d iagn osin g an d trou blesh ootin g, 1170 in stallation , con figu ration an d u p grad in g, 1167, 1169 m oth erboard s, p rocessors an d m em ory, 1171-1173 n etworkin g, 1174-1175 p ortable com p u ters, 1174 p rin ters, 1173-1174 safety an d p reven tative m ain ten an ce, 1170-1171 Co m pto n ’s In teractive En cyclo pedia, 1190 Co m puCo m Speed Pro to co l, see CSP Co m puServe (PC tro ublesh o o tin g reso urces), 1164 Co m puter Reseller New s m agazin e, 19 Co m puter Select CD-ROM, 1191 Co m puter Sh o pper, 19 Co m puter-Based Train in g, see CBT co m puters h istory of, 9-10 Ap p le Com p u ter, 11, 14 CP/ M system s, 11 IBM PC, 10-14 ven d ors, 1244-1245 co n feren cin g (so un d cards), 560 CONFIG.SYS, lo adin g, 1047 ad d in g MSCDEX.EXE d evice d rivers, 864 ad d in g SCSI d evice d rivers, 863-864 m ou se d rivers, 481 STACKS p aram eter (IRQs), 271 co n figuratio n files AUTOEXEC.BAT, 481 CONFIG.SYS, 481 co n figurin g ad ap ter board m em ory, 385-386 ATA IDE (d u al d rives), 615

CD-ROM d rives as p rim ary (m aster) d rive, 855 as secon d ary (slave) d rive, 855 SCSI d rives, 856 d rivers, vid eo, 534-535 DVD-ROM d rives as p rim ary (m aster) d rive, 855 as secon d ary (slave) d rive, 855 SCSI d rives, 856 h ard d isk d rives, 762 AMI ROM BIOS, 1409-1410 au tom atic d rive typ in g, 766 Award ROM BIOS, 1411-1412 Com p aq Deskp ro 386, 1408-1409 h ost ad ap ter con figu ration s, 762-764 IBM AT/ PS/ 2, 1406-1408 m an u al d rive typ in g, 766 Ph oen ix ROM BIOS, 1412-1413 u ser-d efin able d rive typ es, 1401-1405 p arallel p orts, 598 Pn P (Plu g an d Play), 644-645 p ortable com p u ter setu p s (swap p able d rive bays), 932 record in g con figu ration s (assem blin g system s), 971 SCSI, 640, 645-646 IDs, 641-642 p arity, 644 Start on Dem an d , 643-644 syn ch ron ou s n egotiation , 644 term in ation , 642-643 term in ator p ower su p p lies, 644 serial p orts, 590-591 sou n d card s (ju m p ers an d DIP switch es), 572 system resou rces (tem p lates), 283-287 voltages, settin g ju m p ers, 73 W in d ows d rivers for p rin ter su p p ort, 899-900 see also d esign Co n flict Reso lver, 1223

1451

co n flicts gam e p ort, 551 m em ory, p reven tin g, 380-381, 386 m ou se (IRQs), 487-490 sou n d card , 574-575 d efau lt Sou n d Blaster resou rce assign m en ts, 575 DMA ch an n els (Direct Mem ory Access), 574 I/ O Port ad d resses, 575 IRQs (In terru p t ReQu ests), 574 locatin g, 576 resolvin g, 575 co n n ectio n s CD-ROM d rives, 832-835 EIDE, 834 extern al, 856-858 IDE/ ATAPI, 833 in tern al, 858-860 p arallel p ort, 834-835 SCSI, 833 d evices, FireW ire (IEEE 1394), 604-605 d irect cable, 676 n u ll m od em cables, 676 software, 677 DVD-ROM d rives extern al, 856-858 in tern al, 858-860 extern al cables, 977 ISDN (In tegrated Services Digital Network) in stallin g, 672 S/ T (Su bscriber/ Term in ation ) In terface, 672 term in al ad ap ters, 672 U-In terface, 672 m od em 56K lim itation s, 668-669 d ata bits, 657 fin d in g for p ortables, 945 N-8-1, 657 p arity, 657 stop bits, 657 p arallel p orts, 598-599 p rin ters, trou blesh ootin g, 906-907 co n n ecto rs AT m oth erboard s, 168 ATA IDE, 614 I/ O, 615-616

1452

connectors

ATX m oth erboard s I/ O, 173 in tern al p ower su p p ly, 173 Baby-AT m oth erboard (keyboard ), 169 BNC (Th in Eth ern et), 694 card ed ge (in tern al d rive in stallation s), 858-859 Card / Ed ge (8-bit ISA bu s), 240 CD-ROM d rive CD Au d io In (in stallin g sou n d card s), 572 clean in g, 1020-1021 d isassem blin g keyboard s, 476 En h an ced 101-key keyboard s, 448 Eth ern et ad ap ters, 690 flop p y d isk d rives, 776-778 fu ll-size AT m oth erboard, 170 gam e con tollers, 498 h ard d isk d rive in terface, 753 p ower, 753 IDE (In tegrated Drive Electron ics), 611-612 keyboard , 470 5-p in DIN, 471 6-p in m in i-DIN, 471 Baby-AT m oth erboard s, 951 m in i-DIN p lu gs, 471, 478-479 SDL (Sh ield ed Data Lin k), 471 sign als, 471-472 sp ecification s, 474-475 loop back, 593, 1007 LPX m oth erboard s, 171-173 m oth erboard s, 228-232 m ou se, 472 bu s, 484 m oth erboard p orts (PS/ 2), 483 serial, 482 serial an d m oth erboard p ort h ybrid (PS/ 2), 483 USB (Un iversal Serial Bu s), 484 n etwork in terface ad ap ters, 690 p arallel p orts, 593-594 p in ou ts (SVGA), 522

p ower su p p ly, 403-405 ATX op tion al p ower con n ector, 405-406 d isk d rive, 408 p art n u m bers, 409 p ower switch con n ector, 406-408 S-Vid eo, 542 SCSI, 634 sin gle en d ed , 635-639 term in ators, 639-640 serial-p orts 9-p in , 584-586 25-p in , 585-586 ad ap ters, 587 sou n d card , 565 CD-ROM d rives, 569-570 in tern al p in -typ e, 567 joystick, 567 lin e in , 566 lin e ou t, 566 m icrop h on e, 566 MIDI, 567 sp eaker/ h ead p h on e, 566 Token Rin g ad ap ters, 690 USB (Un iversal Serial Bu s), 602-603 vid eo, VFC (Vid eo Featu re Con n ector), 536-537 Co n n er Periph erals, In c. (h ard disk param eters), 1355-1357 Co n stan t An gular Velo city, see CAV Co n stan t Lin ear Velo city, see CLV co n stan t vo ltage, 394 Co n sultative Co m m ittee o n In tern atio n al Teleph o n e an d Telegraph , see CCITT co n sum ables, prin ter (co sts), 895-896 co n sum ers (so un d card users), 570 co n sum ptio n calculatio n s (po w er supplies), 417-421 con tact clean in g solution , 1015 co n tact m etals DIMMs, 959-960 SIMMs, 959-960 co n tacts, clean ers/ lubrican ts, 1016, 1021 Stabilan t 22, 1016-1017 Stabilan t 22a, 1017 co n tiguity file tests (CHKDSK), 1089

co n tro l co des m od em s, 1345 PCL (Prin ter Con trol Lan gu age), 873 co n tro l devices, jo ysticks an d paddles (gam in g), 551 Co n tro l Pan el (Win do w s 9x ), co n n ectio n preferen ces, 658 co n tro l pan els (So un ds), 557 Co n tro l Pro gram fo r Micro pro cesso rs, see CP/ M system s co n tro llers ATA IDE (n on -in telligen t), 619 cach e, 320-322 h ard d isk p erform an ce, 757-767 d isk d rive (p ort com m an d s), 1052-1053 flop p y d isk d rives, 775-776 IBM PC AT, 1132 sp eed d ifferen ces, 25 h ard d isk d rives, 728-729 IBM PC AT, 1132 ven d ors, 1239 IDE, see IDE keyboard 8048, 458, 462 8049, 458 BIOS u p grad es, 216-217 Motorola 6805, 458 m em ory, 322 recom m en d ation s, 295-296 Su p er I/ O ch ip s d u al serial p ort, 207 flop p y, 207 keyboard , 208 m ou se, 208 p arallel p ort, 207-208 co n tro ls (m o n ito r buyin g tips), 512 co n ven tio n al m em o ry, 359-360, 364 co n versio n s en d ec (en cod er/ d ecod er), 608 Hexad ecim al to ASCII con version s, 1326-1334 co n verters SIMMs, 328 vid eo (VGA-to-NTSC), 538 co o lin g CPUs, 74 ATX m oth erboard s, 75, 174, 952

CPUs

fan s, 399-401 ATX form factors, 398 bu ild in g system s, 966-967 SFX form factors, 402 h eat sin ks, 74 active, 74 p assive, 74 co pro cessin g (video ch ipsets), 526 COPY co m m an d (Win do w s 9x DOS), 1414 co re files, 1056 DOS, 1034-1035 COMMAND.COM, 1036 IBMBIO.COM (IBM DOS), 1035 IBMDOS.COM (IBM DOS), 1036 IO.SYS (MS-DOS), 1035 MSDOS.SYS (MS-DOS), 1036 GDI.EXE, 1057 KRNL286.EXE, 1056 KRNL386.EXE, 1056 USER.EXE, 1056 co re speed m em o ry, see cach e co re to bus frequen cy, see clo ck m ultipliers; o verclo ckin g co re vo ltage (m o bile Pen tium s), 919-920 AMD-K6 p rocessors, 154 sp lit rail p rocessor, 72 Co relDRAW!, 1192 co ro tro n , 886 d etac, 887 co rruptio n (FAT erro rs), 1087 co sm ic ray failures (so ft m em o ry erro rs), 345 DRAMS, 345 SRAMS, 345 co sts 3D grap h ics accelerators, 544 8086 CPUs, 83 8088 CPUs, 83 active-m atrix LCDs (failed tran sistors), 503 ATX m oth erboard s, 174 backp lan e system s, 181 bu ild in g system s, 947 CD-ROM d rives (cad d ies), 836 d isp lays (LCD p rojectors), 943

h ard d isk d rives, 759 IDE (In tegrated Drive Electron ics), 612 lap top s, 910 m em ory (SRAM), 319 m on itors 15-in ch versu s 17-in ch , 505 em ission stan d ard d ifferen ces, 509 size in flu en ces, 504 n etwork in terface ad ap ters, 689 n otebooks, 910 p assive m atrix LCDs, 915 p rin ter con su m ables, 895-896 sou n d card s (bu sin ess ap p lication s), 561 su bn otebooks, 911 tap e d rives, 818 Co vin gto n , see Pen tium II CPUs, n o L2 cach e CP/ M system s (Co n tro l Pro gram fo r Micro pro cesso rs), 11 cps (ch aracters per seco n d), 889 CPUm ark32 ben ch m ark, 165 CPUs (Cen tral Pro cessin g Un its), 10, 21, 27, 31, 83, 953, 1100 286, 44 32-bit, see 32-bit CPUs 386 16-bit d ata bu ses, 38 32-bit d ata bu ses, 38 386DX, 38, 88, 90-92, 323 386SL, 89 386SX, 88-89, 38-39, 323 387DX m ath cop rocessor, 90 387SX m ath cop rocessor, 90 82350 ch ip sets, 187 ad d ressable m em ory, 87-88 bu s wid th s, 22 MMU (Mem ory Man agem en t Un it), 87 p rotected m od e, 44, 87 virtu al real m od e, 44-46, 87 W eitek m ath cop rocessors, 90

1453

486 32-bit d ata bu ses, 38 32-bit in tern al registers, 39 486DX, 95-97 486DX2 (Pen tiu m OverDrives), 101 486SL, 47, 97-98 486SX, 98-99 486SX2 (Pen tiu m OverDrives), 101 487SX m ath cop rocessor, 98-99, 103 82350 ch ip sets, 187 AMD 486 (5x86), 80, 103-104 bu s wid th s, 22 cach e, 42 ch ip sets, 187 Cyrix/ TI 486, 104 DX2/ OverDrive, 99-101 DX4 p rocessors, 101 in stru ction -execu tion tim es, 92 m axim u m in stallable m em ory, 323 n ew featu res over 386, 92-93 OverDrive sockets (secon d ary), 102 secon d ary OverDrive sockets, 102 sockets, 54, 57-65, 67 sp eed s, 93 u p grad in g, 95 4004, 10 8008, 10 80286, 24, 84, 1129 80287 m ath cop rocessor, 86 IBM PC XT Mod el 286, 1145 m axim u m in stallable m em ory, 323 p rotected m od e, 86 real m od e, 44, 85 sp eed s, 85 Stan d ard m od e (W in d ows 3.0), 86 80386, 87 386DX, 88 386SL, 89 386SX, 88-89 80387 m ath cop rocessor, 90 bu gs, 90-92

1454

CPUs

m axim u m in stallable m em ory, 323 MMU (Mem ory Man agem en t Un it), 87 p rotected m od e, 44, 87 virtu al real m od e, 45-46, 87 W eitek m ath cop rocessors, 90 80486, 92-93 486DX, 95-97 486SL, 97-98 486SX, 98 487SX m ath cop rocessor, 98-99, 103 AMD 486 (5x86), 80, 103-104 ch ip sets, 187 Cyrix/ TI 486, 104 DX2/ OverDrive, 99-101 DX4 p rocessors, 101 in stru ction -execu tion tim es, 92 m axim u m in stallable m em ory, 323 n ew featu res over 386, 92-93 Pen tiu m OverDrives, 101 secon d ary OverDrive sockets, 102 sockets, 54, 57-67 sp eed s, 93 u p grad in g, 95 8080, 10 8086, 83 8087 m ath cop rocessor, 84 ad d ress bu s wid th , 83 cost, 83 m axim u m in stallable m em ory, 323 8088, 23-24, 1101, 1115 m axim u m in stallable m em ory, 323 82350 ch ip sets, 187 A+ exam objectives, 1171-1173 ATX m oth erboard s, 174 backp lan e system s, 181 Bu s Freq u en cy p in s (overclockin g p rotection ), 53 bu s wid th s, 22-23 m oth erboard restriction s, 23 Celeron , 67, 151 circu it size, 62

clock sp eed s (m em ory cycle tim es), 313 cod en am es, 79 coolin g fan s, 399-401, 966-967 Cyrix Med iaGX (vid eo circu try), 500 d ata p ath s, 21 featu res, 47 DIB (d u al in d ep en d en t bu s) arch itectu re, 49-50 d yn am ic execu tion , 48 MMX tech n ology, 47 SMM (System Man agem en t Mod e), 47 su p erscalar execu tion , 47 h eat p roblem s, 74 ATX m oth erboard s, 75 h eat sin ks, 74 h eat sin ks, 966-967, 973 IBM PC AT, overclockin g, 1134 in stallin g (p rep arin g m oth erboard s), 972 In tel-com p atible, 80 AMD (Ad van ced Micro Design s), 80, 125-126 Cyrix, 81 IDT Cen tau r C6 W in ch ip , 82, 126-127 P-ratin gs, 82 m an u factu rin g bou les, 50 ch ip s, 52-53 d ies, 51 d op in g, 51 m asks, 51 overclockin g, 53 p h otolitograp h y, 51 p h otoresists, 51 silicon , 50 tran sistors, see tran sistors wafers, 51-52 yield s, 52 m ath cop rocessors, 75 bu ilt-in , 75-77 m axim u m sp eed s, 76 sp ecification s, 77 m od es (PC/ XT an d AT d ifferen ces), 25 NLX m oth erboard s, 177 overclockin g, 298-299 P7 (Merced ), 23, 158-161 p ackagin g, 53 Ceram ic Pin Grid Array, 37 PGA (Pin Grid Array), 53

SEC (Sin gle Ed ge Cartrid ge), 54, 67-71 SPGA (Staggered Pin Grid Array), 54 Pen tiu m , 105, 953 ad d ress bu s wid th , 106 ad d ressable m em ory, 106 BiCMOS (Bip olar Com p lem en tary Metal Oxid e Sem icon d u ctor), 108 BTB (Bran ch Target Bu ffer), 106 cach e, 107-108 ch ip sets, 187-199 classic step p in gs, 118-120 d ata bu s wid th , 106 DIMM wid th , 106 first-gen eration , 109-110 FPU, 109 FPU bu g, 114-116 in stru ction p rocessin g, 107 m axim u m in stallable m em ory, 323 Mod el 1 step p in gs, 117 OverDrive p rocessor, 59-60 p ackagin g, 109 p ower m an agem en t bu gs, 116 secon d -gen eration , 110-113 SIMM wid th , 106 SL en h an cem en ts, 108 sockets, 54, 57-67 sp ecification s, 105-106 step p in gs, 124 su p erscalar arch itectu re, 105 twin d ata p ip elin es, 105-106 voltages, 108, 125 ZIF sockets, 953 Pen tiu m II, 127, 140, 532, 953 0.25 m icron , 79 300 MHz, 128K L2 cach e (Men d ocin o), 79 Celeron , 67, 151 ch ip sets, 200-207 DIB (Du al In d ep en d en t Bu s), 128-129, 142, 144 Dyn am ic Execu tion , 127-128, 142 ECC (Error Correction Cod e), 145

CTTY command

fu tu re d evelop m en ts, 151-152 h eat p roblem s, 145 iCOMP 2.0 In d ex ratin g, 141 im p roved Katm ai (W illam ette), 79 in stallin g, 145 in stru ction execu tion , 129 in tern al registers, 40 Level 2 cach e, 320 m axim u m in stallable m em ory, 323 MMX tech n ology, 141 MMX2, 79 Mobile Mod u le, 151 m u ltip rocessin g, 145 n o L2 cach e (Covin gton ), 79 p ower u sage, 142 ru n n in g 32-bit software, 130 SEC (Sin gle Ed ge Con tact) p ackagin g, 140, 54, 67-71 slot 1, 79 sockets, 67-71 Sou th Bridge ch ipsets, 202 sp ecification s, 143 sp eed s, 141 tran sistors, 141 version ID in form ation , 147-149 voltage ID d efin ition s, 150-151 Xeon , 32, 152, 161 Pen tiu m MMX, 953 Pen tiu m OverDrive step p in gs, 122-124 voltages, 125 Pen tiu m Pro, 127, 130, 953 cach e, 130 ch ip sets, 134, 199-207 DIB (Du al In d ep en d en t Bu s), 128-129 Du al Cavity PGA p ackagin g, 130 Dyn am ic Execu tion , 127-128 form factors, 134 in stru ction execu tion , 129 in tegrated L2 cach e, 134 in tern al registers, 40 Level 2 cach e, 320

m axim u m in stallable m em ory, 323 MCM (Mu lti-Ch ip Mod u le), 130 revision s, 135-138 ru n n in g 32-bit software, 130 sockets, 54, 57-67 Sou th Brid ge ch ip sets, 202 sp ecification s, 132-133 sp eed s, 134 tran sistors, 130 VID (Voltage Id en tification ) p in s, 135 Pen tiu m -com p atibile AMD-K6, 153-154 Cyrix 6x86/ 6x86MX, 156-157 Cyrix Med iaGX, 155-156 Nexgen Nx586, 152-153 Pen tiu m -MMX, 113-114 clock sp eed s, 113 ju m p erin g for 60/ 66MHz op eration , 114 m axim u m in stallable m em ory, 323 m obile, 79 OverDrive p rocessor, 63 SIMD, 114 sockets, 54, 57-67 step p in gs, 121-124 u p grad in g, 114 voltages, 113, 125 VRM, 114 p ortable com p u ters, 918 ch ip sets, 929 Pen tiu m s, 918-920, 923-928 step p in gs, 920-923 p ower resets (Power Good Sign al), 410 servers, 686 settin g ju m p ers, 954 socketed (p rep arin g m oth erboard s), 972 sockets, 54, 57 OverDrive (Socket 1), 57-58 Slot 1, 67-71 Socket 2, 59-61 Socket 3, 61 Socket 4, 62 Socket 5, 63 Socket 6, 63 Socket 7, 64

1455

Socket 8, 65 sp ecification s, 182 ZIF, 67 sp ecification s, 31-32 ad d ress bu ses, 40-41 d ata bu s wid th , 38-39 in tern al (Level 1) cach e, 41-42 in tern al registers, 39-40 m od es, 43-46 secon d ary (Level 2) cach e, 41-43 sp eed ratin gs, 33-37, 43 sp eed ratin gs, overclockin g, 53 see also MHz (Megah ertz) testin g, 77 u p grad in g, 161 ben ch m arks, 164-165 m axim u m sp eed s, 161-162 OverDrive p rocessors, 162-164 ven d ors, 1243 voltages, 72, 74 Pen tiu m , 72 Pen tiu m Pro, 73 Pen tiu m -MMX, 73 wid th s, 31 work-arou n d u p d ates, 78 CRC (cyclic redun dan cy ch eck), 692 cro ss-lin ked files (FAT erro rs), 1087 cro sstalk (56K m o dem s), 669 CRT display adapters, lapto ps (IBM PC Co n vertible), 1114 CRTs (cath o de ray tubes), 500 p h osp h or-based screen s cu rved , 501 flat, 501 refresh rates, 500 fixed , 501 CSA (Can adian Stan dards Agen cy), 417 CSCRIPT.E XE (Win do w s 9x DOS), 1415 CSEL (Cable Select) sign als, 617 CSMA/ CD, 700 CSP (Co m puCo m Speed Pro to co l), 666 CSTN (co lo r super-tw ist n em atic), passive m atrix displays, 915 CTTY co m m an d (Win do w s 9x DOS), 1414

1456

currents

curren ts, see electricity curved ph o sph o r-based screen s, 501 custo m izin g, see co n figurin g;design CVC (Co m pact Video Co ded), see Cin epak CVT.EXE (Win do w s 9x DOS), 1415 cycle tim es clock speed com parison s, 313 CPU sp eed s (execu tin g in stru ction s), 34 op eration sp eed , 1132 cyclic redun dan cy ch eck, see CRC Cylin der Head Secto r, see CHS cylin ders flop p y d isk d rives, 781 m an u al d rive typ in g, 766 skewin g (h ard d isk p erform an ce), 758-759 Cyrix 486 CPU, 104 6x86/ 6x86MX CPUs, 156-157 PR (Perform an ce Ratin g), 37 sp eed s, 157-158 In tel MMX licen sin g, 48 In tel-com p atible CPUs M1 an d M2 6x86, 81 Med iaGX, 81 Med iaGX CPUs, 155-156, 500 m oth erboard s Alad d in M1510 ch ip set, 956 Op ti 82C550 Vip er-DP, 956

D d sw itch (CHKDSK co m m an d syn tax ), 1089 D ch an n els, see delta ch an n els d-lim o n en e clean ers, 1016 DACs (Digital to An alo g Co n verters), 29, 529, 531 daisy ch ain s, 753 ATA IDE, con figu rin g, 615 FireW ire (IEEE 1394), 604 MIDI d evices, 556 DASP sign als (Drive Active/ Slave Presen t), 616

DAT stan dards (digital audio tape), 812-814 data areas DVD (Digital Versatile Disc), 852 p artition s, 1079 bu ses CPs, 38 extern al, 39, 105, 132, 143 in tern al, 39 Pen tiu m CPUs, 105-106 Pen tiu m II CPUs, 143 Pen tiu m Pro CPUs, 132 wid th s, 39 see also bu ses CD-ROMs au d io CD d ifferen ces, 826 cap acities, 823 com p ression (sou n d card s), 568 ADPCM (Ad ap tive Differen tial Pu lse Cod e Mod u lation , 569 MPEG (Motion Pictu res Exp erts Grou p s), 569 m od em stan d ard s, 664 in tern al registers (CPUs), 39-40 en cap su lation , 684 en cod in g sch em es, m agn etic storage, 712-716 ARLL (Ad van ced Ru n Len gth Lim ited ), 715 com p arison s, 716-717 FM (Freq u en cy Mod u lation ), 714 MFM (Mod ified Freq u en cy Mod u lation ), 714 RLL (Ru n Len gth Lim ited ), 715-716 flow an alysis d yn am ic execu tion , 49, 128 sp ecu lative execu tion , 49 in tern al registers, CPUs, 39-40 p ath s (CPUs), 21 p ip elin es (Pen tiu m CPUs), 105 u -p ip e an d v-p ip e, 106 see also p ip elin es sep arators, 608

stan d ard s (CD-ROM d rives) High Sierra, 839 ISO 9660, 839 th rou gh p u t, tap e d rives, 818 data bits (m o dem co n n ectio n s), 657 Data Buffer Co n to ller, see DBC Data Lin k Layer (OSI Referen ce Mo del) LLC (Logical Lin k Con trol) su blayer, 683 MAC (Med ia Access Con trol) su blayer, 683 p rotocols, 699 ARCn et, 700 Eth ern et, 700-701 Token Rin g, 701-702 data tran sfer rates CD-R (CD-Record able) d rives, 848 CD-ROM sp ecification s, 829-830 d rive sp eed s, 829-830 h ard d isk com p arison s, 831 m u ltim ed ia, 830 u p grad e issu es, 830 h ard d isks, 720 n etwork in terface ad ap ters, 691 data types, CD-ROM-XA (Ex ten ded Arch itecture) Mod e 1, 841 Mod e 2, Form 1, 842 Mod e 2, Form 2, 842 Datapo rt, 1192 DataRase EPROM eraser, 1234 DATE co m m an d (Win do w s 9x DOS), 1414 daugh ter cards Sou n d Blaster (W ave Blaster), 568 vid eo m em ory, 529 db (decibels), lo udn ess o f so un d, 563 DB-9 co n n ecto rs (m o use co n n ectio n s), 482 DB-25 co n n ecto rs (m o use co n n ectio n s), 482 DB9 co n n ecto rs, 690 dBASE, 1186 DBB sw itch (dyn am ic bass bo o st), speakers, 580 DBC (Data Buffer Co n tro ller), 956

diagnostic software

DBR (DOS Bo o t Reco rd) fo rm at, 780, 1072-1073 DC (direct-curren t), 391, 1008 DCC (Direct Cable Co n n ectio n ), 599 DDD (Digital Diagn o stic Diskette), 795 DDMs (Digital Multi-Meters), selectin g, 428-429 DDR (Do uble Data Rate) SDRAM, 318-319 de facto stan dards (so un d cards), 550 dead pix els active m atrix LCDs, 916 failed tran sistors, 502 debo un cin g keystro kes, 458 DEBUG co m m an d BIOS (IBM PC XT), 1119 PC BIOS, 1105 DEBUG.EXE (Win do w s 9x DOS), 1415 decibels (db), 563 deco din g d ata (n etwork in terface ad ap ters), 692 MPEG, 537 deco m pressio n (video co decs), 540-541 dedicated leased lin es, 673 T-1 con n ection s, 673 T-3 con n ection s, 673 dedicated servo m ech an ism s, 748 default clusters sizes (flo ppy disk drives), 781 defect-m appin g co m m an ds (ESDI), 610 defects (Pen tium CPUs) FPU bu g, 114-116 keyswitch es, 478 m ap p in g, 768 p ower m an agem en t bu gs, 116 see also errors;failu res defragm en tin g h ard disk drives, 1022-1023 CHKDSK rep ortin g, 1088 file p ackin g, 1023 file sortin g, 1023 W in d ows 98 (Main ten an ce W izard ), 1024 W in d ows 9x, 1023 DEL co m m an d (Win do w s 9x DOS), 1414

delay param eters (MODE co m m an d, 461 delayed starts (SCSI), 643-644 delta ch an n els (ISDN), 671 delta co n figuratio n s (co lo r m o n ito rs), 504 DELTREE.E XE (Win do w s 9x DOS), 1415 dem an d prio rity (100VG Eth ern et pro to co l), 705 depo t repair p ower su p p lies, 431-432 trou blesh ootin g m on itors, 547 depressurizatio n case design s, 1014 Desch utes co re Pen tiu m CPUs, 151 see also Pen ttiu m CPUs, 0.25 m icron descripto rs (NTFS MFT), 1096 design keyboard ergon om ic, 473 p rogram m able, 473 referen ce m aterial, 479 PC 9x sp ecification s, 21 p ortable com p u ters, 911 h eat, 912 in creased battery efficien cy, 911 low p ower com p on en ts, 911 p ower m an agem en t, 911 see also con figu rin g deskto p cases, 950 Deskto p Man agem en t In terface, see DMI Deskto p Video bo ards, see DTV deso lderin g to o ls, 1005-1007 detac co ro tro n , 887 detach able pro be leads (DMMs), 428 deten ts, 774 Deutsch e In dustrie No rm , see DIN (Deutsch e In dustrie No rm ) co n n ecto rs develo per (prin ter to n er), 886 develo pm en t (PC 9x specificatio n s), 21 device drivers, 481 ANSI.SYS, 389 m ou se, trou blesh ootin g, 489-490 SETVER, 389

1457

Device Man ager m ou se con flicts, trou blesh ootin g, 488 W in d ows 9x, 996-997 DMA ch an n els, 997 I/ O p ort settin gs, 997 IRQs, 997 Device Optio n s page (prin ter drivers), settin gs, 900 Device Pro gram m er, 307 device-in depen den t bitm ap, see DIB DEVICEHIGH co m m an d (lo adin g m o use drivers), 490 devices CD-ROM d river sign atu res, id en tifyin g, 864 con flicts gam e p ort, 551 sou n d card , 574-576 con n ectin g, FireW ire (IEEE 1394), 604-605 con trol (gam in g), 551 d rivers, see d evice d rivers In p u t/ Ou tp u t, see I/ O d evices; in p u t d evices MIDI, 555-556 p arallel p ort con n ection s, 598-599 SCSI, see SCSI storage, 605-607 en cod in g sch em es, 608-609 ESDI (En h an ced Sm all Device In terface), 609-610 IDE, see IDE ST-506/ 412 in terface, 607-608 diagn o stic read-an d-w rite structure (partitio n s), 1079 diagn o stic so ftw are, 983, 1238 afterm arket, 984 AMI BIOS, 213 CMOS RAM, 227-228 Disp layMate, 548 gen eral-p u rp ose, 991 #1-Tu ffTEST, 994 AMIDiag, 992 Ch eckit Pro, 992 Micro-Scop e, 993 Norton Utilities, 993-994 PC Tech n ician , 994 PC-Diagn osys, 994 QAPlu s/ FE, 994-995

1458

diagnostic software

h ard ware testin g, 989 n etwork in terface card s, 990-991 SCSI d evices, 989-990 IBM, 989 m an u factu rer-su p p lied , 984 m em ory, 359 op eratin g system s, 984, 995 MSD (Microsoft Diagn ostics), 996 W in d ows 98 System In form ation p rogram , 998 W in d ows 9x Device Man ager, 996-997 W in d ows 9x Perform an ce Mon itor, 997 W in d ows 9x Resou rce Meter, 997 W in d ows 9x System Mon itor, 997 W in d ows NT Even t Viewer, 998 p arallel p orts, 600 p erip h erals, 984 POST (Power-On Self Test), 984-985 au d io error cod es, 985-988 I/ O p ort cod es, 988-989 visu al error cod es, 988 serial p orts, 591 loop back tests, 592-593 MSD (Microsoft Diagn ostics), 591-592 W in d ows 95/ 98, 592 testin g CPUs, 77 see also m ain ten an ce; p roblem s; trou blesh ootin g Diam o n d Mo n ster 3D video adapter, 537 DIB (device-in depen den t bitm ap), 535 DIB (Dual In depen den t Bus) arch itectu re, 49-50 Pen tiu m II CPUs, 128-129, 142, 144 Pen tiu m Pro CPUs, 128-129 die sizes, 51 CPU m an u factu rin g, 51 IDT Cen tau r C6 W in ch ip , 127 Pen tiu m CPUs first gen eration , 109 secon d gen eration , 110

Pen tiu m II CPUs, 140-141 233MHz MMX m od els, 144 266MHz MMX m od els, 144 300MHz MMX m od els, 144 333MHz MMX m od els, 143 350 an d 400 MHz MMX m od els, 143 Pen tiu m Pro 150MHz m od el, 133 166MHz m od el, 133 180MHz m od el, 133 200MHz 1M L2 cach e m od el, 133 200MHz m od el, 133 Differen tial Man ch ester Data en co din g (To ken Rin g adapters), 692 differen tial SCSI, 630-631 digital audio tape, 812-814 digital circuits (lo gic pro bes), 1009 digital co m m un icatio n s ISDN, 671 bearer ch an n els, 671 BONDING p rotocol, 672 BRI (Basic Rate In terface), 671 d elta ch an n els, 671 in stallin g con n ection s, 672 Mu ltilin k PPP p rotocol, 672 PRI (Prim ary Rate In terface), 671 S/ T (Su bscriber/ Term in ation ) In terface, 672 term in al ad ap ters, 672 U-In terface, 672 leased lin es, 673 T-1 con n ection s, 673 T-3 con n ection s, 673 Digital Diagn o stic Diskette (DDD), 795 digital lin ear tape (DLT), 814-815 Digital Multi-Meters, see DMMs Digital Research , 12 Digital Sign al Pro cesso rs, 1569 Digital to An alo g Co n verters, see DACs

Digital Versatile Discs, see DVD digital video an alog com p arison s, 517 FireW ire (IEEE 1394), 605 Digital Vo lt Oh m Meters, see DVOMs digits (address buses), 40 DIME (DIrect Mem o ry Ex ecute), 532 DIMMs (dual in lin e m em o ry m o dules), 27, 324-329, 959 ban ks, 338-340 creatin g, 959 wid th s, 39 bu ffered , 358 cap acities, 326 con tact m etal, 959-960 gold -p lated com p ared to tin -p lated con tacts, 340-344 in stallin g, 354-359 p arity, 959 ch eckin g, 347 p in ou ts, 333-336 p ortable com p u ters, 930 recom m en d ation s, 294-295 rep lacin g, 353-354 selectin g, 353 sp eed s, relative to CPU sp eed s, 43 testin g, 1010-1011 ven d ors, 1240 wid th (Pen tiu m CPUs), 106 DIN (Deutsch e In dustrie No rm ) co n n ecto rs, 448 5-p in (MIDI p orts), 555 AT m oth erboard s, 168 DIP (Dual In lin e Package) ch ip s, 324 switch es (in stallin g sou n d card s), 572 DIR co m m an d (Win do w s 9x DOS), 1414 direct cable co n n ectio n s, 676 n u ll m od em cables, 676 3-wire p in ou ts, 676 11-wire p in ou ts, 676 software, 677 DOS, 677 W in d ows 9x, 677 direct m ail o utlets, 1243 Direct Mem o ry Access, see DMA Direct Mem o ry Ex ecute, see DIME

disk space

directo ries in valid (FAT errors), 1087 p h an tom , 782 root, 1073-1075 d ate/ tim e of last ch an ge, 1073 en try lim its, 1074 FAT32 location s, 1083 file attribu te byte, 1073-1075 file n am es an d exten sion s, 1073 file size, 1073 form ats, 1074-1075 lin k to start clu ster, 1073 organ ization , 1074 su bd irectories, 1073 tracin g files, 1074 DIS (dyn am ic im pedan ce stabilizatio n ), 665 disabled users, see h an dicapped users disablin g o verclo ckin g (IBM PC AT), 1134 disassem blin g system s, 979-980 clean in g system s, 1019 CMOS in form ation , record in g, 979-981 h ard d isk settin gs, record in g, 979-981 trou blesh ootin g keyboard s, 475-476 cablin g, 476 con n ectors, 476 disch argin g po rtable co m puter batteries, 940 disco n tin ued system s (replacin g parts), 1100 disk co m pressio n Dou bleSp ace MS-DOS 6.0, 1040 MS-DOS 6.2, 1040 DriveSp ace (MS-DOS 6.22), 1040 Disk Defragm en tatio n utility (Win do w s 95), 1093 Disk Do cto r (No rto n Utilities), 993, 1094 Disk Drive Clean er, 1223 disk drives cartrid ges, 799-802 Jaz d rives, 801-802 Sp arq d rives (m axim u m root d irectory), 802-804, 1074 Syq u est d rives, 801

tap e d rives, see tap e d rives Zip d rives, see Zip d rives con n ectors, 408 DOS in terfacin g, 1049 con troller I/ O p ort com m an d s, 1052-1053 In terru p t 13h , 1050-1052 In terru p t 21h , 1050 In terru p t 25h , 1050 In terru p t 26h , 1050 flop p y d isk, 770-795 1.2M 5 1/ 4-in ch , 786-787 1.44M 3 1/ 2-in ch , 779-780, 783 2.88M 3 1/ 2-in ch , 779-780, 784-787 3 1/ 2 in ch flop p y d isk d rives, 779-780, 961 1.44M, 783 2.88M, 784-785 5 1/ 4-in ch form at, 779-780 360K 5 1/ 4-in ch , 787 720K 3 1/ 2-in ch , 779-780, 785-786 align m en t, 794-795 cables, 777-778 circu it board s, 775 clean in g, 793-794 clu sters, 781 con n ectors, 776-778 con trollers, 775-776 cylin d ers, 781 d iskette ch an gelin e, 781-782 facep lates/ bezels, 776 h ead actu ator m ech an ism s, 774 in stallin g, 793 logical d isk form atted p aram eters, 783 op eratin g system d isk u sage, 779 p h ysical op eration , 779 read / write h ead s, 771-774 rep airin g, 793-795 sp ecification s, 778-779 sp in d le m otors, 774-775 track-wid th sp ecification s, 779 h ard d isk, 719-761 ad van cem en ts, 719-720 air filters, 749-750 areal d en sity, 720-722 average access tim e, 756

1459

average seek tim e, 756-759 cap acities, 759-761 con figu ration item s, 753-754 costs, 759 d rive cables, 765 facep late/ bezel, 753-754 form attin g, 728-734 grou n d in g tabs, 753 h ard d isk tem p eratu re acclim ation , 750-751 h ead actu ator m ech an ism s, 740-749 h ead slid ers, 739-740 h ead / m ed iu m in teraction an alogy, 722-724 in stallin g, 761-770 in terface con n ectors, 753 logic board s, 752 m ou n tin g rails, 764 m ou n tin g screws, 765 oxid e record in g m ed ia, 734 p erform an ce, 755-759 p latters, 720, 732-734 p ower con n ectors, 753 raw in terface p erform an ce, 757 read / write h ead s, 735-739 reliability, 755 rem ovable, 719 SCSI in terfaces, 761 sectors, 724-728 sh ock m ou n tin g, 759 sp in sp eed s, 722 sp in d le m otors, 751-752 th in -film , 734-735 track d en sities, 722 tran sfer rates, 756 IDE, see IDE Disk Edito r utility (No rto n ), 1094 Disk Man ager, 619, 1217 disk m irro rin g (NTFS), 1097 Disk Operatin g System , see DOS disk param eter blo cks (vo lum e bo o t secto rs), 1071-1072 disk space DOS allocation s, 1048 clu sters, 1048-1049 overwritin g files, 1049 FAT stru ctu res, 1065-1066 d am age, 1067 d ata area, 1079

1460

disk space

d iagn ostic read -an d -write stru ctu re, 1079 FATs (File Allocation Tables), 1076-1077 m aster p artition boot sector, 1067-1070 root d irectories, 1073-1075 volu m e boot sectors, 1071-1072 disk stripin g (NTFS), 1097 disk sw eep, 745 DISKCOPY.COM (Win do w s 9x DOS), 1415 diskette ch an gelin e (flo ppy disk drives), 781-782 disks, flo ppy, 28 com p ression , see d isk com p ression FAT stru ctu res, 1065-1067, 1071-1079 p h ysical con stru ction , 787-793 DiskTo o l utility (No rto n ), 1094 display m o des, VGA (Video Graph ics Array), 519 Display Po w er-Man agem en t Sign alin g, see DPMS DisplayMate diagn o stic so ftw are (m o n ito rs), 548 DisplayMate video display, 1227 displays IBM PC Con vertible CRT ad ap ters, 1114 lap top s, 1114 LCDs (liq u id crystal d isp lays) IBM PC Con vertible, 1111 screen sizes, 511-512 ven d ors, 1241 m on itors, 30, 499-500, 965 actu al viewin g areas, 504-505 APM, 507 bu yin g criteria, 509-513 color, 503-504 CRTs (cath od e ray tu bes), 500 cu rved p h osp h or-based screen s, 501 d ot p itch , 506 en ergy-savin g featu res, 507-509 flat p h osp h or-based screen s, 501

gas p lasm a, 503 IBM En h an ced Color Disp lay (EGA ad ap ters), 516 IBM Profession al Color Disp lay (PGA ad ap ters), 516 in p u t sou rces, 500 in terlaced , 506-507 LCDs (liq u id crystal d isp lays), 501-503 m on och rom e, 503-504 m u ltip le-freq u en cy, 501 n on in terlaced , 506-507 refresh rates, 500-501 resolu tion , 505-506 RGB, 515 server req u irem en ts, 688 sizes, 504 stan d -by m od e, 507 su sp en d m od e, 507 trou blesh ootin g, 547-548 ven d ors, 1241 VGA (Vid eo Grap h ics Array), 506 p ortable com p u ters, 913 extern al, 942-944 gas p lasm a, 917 LCDs, 913-917 vid eo card s, 29 distan ce lim itatio n s (n etw o rk cablin g), 699 distin ctive rin g suppo rt (m o dem s), 670 dith erin g, 890 Ditto drives, 1205 Divx DVD stan dard, 853 DLT stan dards (digital lin ear tape), 814-815 DMA (Direct Mem o ry Access) ch an n els, 275, 763, 990 8-bit ISA bu s, 275 16-bit ISA bu s, 275-276 ATA-2/ ATA-3 IDE, 624 ch an n els, 763 con figu rin g sou n d card s, 572 con flicts (op tical d rives), 854 EISA bu s, 276-277 MCA bu s, 277 m em ory lim itation s (m axim u m in stallable), 324 PC/ XT an d AT differen ces, 25 PC Card su p p ort, 933 sou n d card s con flicts, 574 W in d ows 9x Device Man ager, 997

DMI (Deskto p Man agem en t In terface), 20 DMMs (Digital Multi-Meters), 1008 au d ible con tin u ity tests, 428 au tom atic d isp lay h old featu re, 429 au tom atic p ower off featu res, 428 au toran gin g, 428 cable testin g, 474 d etach able p robe lead s, 428 m easu rin g voltage back p robin g, 429 toleran ce levels, 430 m in im u m an d m axim u m trap , 429 overload p rotection , 428 do ckin g statio n s lap top s, 910 p ortable com p u ters, 944-945 do cum en tatio n , 1154-1155, 1236-1237 assem blin g system s, 969 ch ip an d ch ip set level, 957, 1156, 1160-1162 com p on en t level, 1156 m oth erboard s, 296-297 system level, 1156-1159 m an u factu rer-sp ecific, 1163 see also m an u als do cum en ts (em beddin g vo ice an n o tatio n s), 558 do pin g m an u factu rin g CPUs, 51 p h otolith ograp h y, 51 DOS (Disk Operatin g System ), 1031 boot p rocess, 1042 AUTOEXEC.BAT, load in g, 1047 cen tral h ard ware test, 1043 cold / warm boot ch ecks, 1044 CONFIG.SYS, load in g, 1047 POST, 1043 sector errors, 1044-1047 vid eo ROM errors, 1043 COMMAND.COM (sh ell), 1036 com m an d file search p roced u re, 1037-1039 resid en t com m an d s, 1037 tran sien t com m an ds, 1037

drivers

com m an d s, 1413 extern al W in d ows 9x, 1415-1416 in tern al W in d ows 9x, 1414-1415 on W in d ows 95 CD-ROM, 1417 on W in d ows 98 CD-ROM, 1417 retired for W in d ows 9x, 1417-1418 d irect cable con n ection software, 677 d isk d rive in terfacin g, 1049 con troller I/ O p ort com m an d s, 1052-1053 In terru p t 13h , 1050-1052 In terru p t 21h , 1050 In terru p t 25h , 1050 In terru p t 26h , 1050 d isk sp ace allocation , 1048 clu sters, 1048-1049 overwritin g files, 1049 d rivers (p rin ter su p p ort), 897 exten d ed DOS p artition s, 1067-1068 FAT (File Allocation Table) errors, 1086-1087 file system u tilities, 1088-1095 stru ctu res, 1065-1083 I/ O system , 1034-1035 IBMBIO.COM (IBM DOS), 1035 IBMDOS.COM (IBM DOS), 1036 IO.SYS (MS-DOS), 1035 MSDOS.SYS (MS-DOS), 1036 m ach in e lan gu age, 1032 assem blers, 1032 p ortin g cod e, 1032 prim ary DOS partition s, 1067 ROM BIOS, 1032-1033 d irect h ard ware access, 1035 in terru p ts, 1032-1033 m em ory m an agers, 1035 stan d ard in terface, 1034 sh ell fu n ction s, 1033 u p grad e p roblem s, 1040 DOS 4.0, 1041 DOS 5.0, 1041 DOS 6.x, 1041 SYS com m an d , 1040-1041 W in d ows 95, 1041

version s, 1039 5.x, 1039 MS-DOS 5.x, 1039 MS-DOS 6.0, 1040 MS-DOS 6.2, 1040 MS-DOS 6.21, 1040 MS-DOS 6.22, 1040 W in d ows 9x com p arison s, 1058 Registry, 1059 DOS Bo o t Reco rd (DBR), 780, 1072-1073 DOS ECHO co m m an d (m o dem s), 660 DOS FORMAT pro gram , 725, 770 DOS In terlin k, 1224 DOS SCSI adapter driver (addin g to CONFIG.SYS), 863 DOSKEY.COM (Win do w s 9x DOS), 1416 DOSSHELL co m m an d (retired fo r Win do w s 9x ), 1418 do t m atrix prin ters, 869-873 9-p in , 872 24-p in , 872-873 m em ory, 878 p reven tative m ain ten an ce, 902-903 p rin tin g, 889-890 do t pitch , m o n ito rs, 506 bu yin g tip s, 511 do ts per in ch (dpi), 870-871 Do uble Data Rate, see DDR SDRAM do uble-den sity, 787 Do uble Den sity reco rdin g, 714 do uble scan LCDs, 501 do uble-layer super-tw ist n em atic, see DSTN do uble-scan LCDs, 502-503 do uble-speed CD-ROM drives, 829 Do ubleSpace disk co m pressio n MS-DOS 6.0, 1040 MS-DOS 6.2, 1040 do ublin g CPU speeds DX2/ OverDrive p rocessors, 99-101 DX4 p rocessors, 101 DP (Dual Pro cesso r), OverDrive steppin gs tables, 123 depth cuein g (3D im age tex tures), 544 dpi (do ts per in ch ), 870-871

1461

DPMA (Dyn am ic Po w er Man agem en t Arch itecture), 20 DPMS (Display Po w erMan agem en t Sign alin g), 507-508 DRAM (dyn am ic RAM), 311-312 BEDO DRAM, 316 com p ared to SRAM (Static RAM), 319-322 cosm ic ray failu res, 345 DDR (Dou ble Data Rate) SDRAM, 318-319 FPM (Fast Page Mod e) DRAM, 314-315 m em ory u p grad es (p ortable com p u ters), 930 RDRAM (Ram bu s DRAM), 317-318 SDRAM (Syn ch ron ou s DRAM), 316-317 tran sfer rates, 529 DRAM (dyn am ic RAM), video m em o ry, 529 Drive Active/ Slave Presen t (DASP), 616 drive sealin g (CD-ROM drives), 837 Drive Pro be, 795 DrivePro , 1211 drivers bu ild in g system s, 968 CD-ROM in terfaces (ASPI), 833 DOS (p rin ter su p p ort), 897 m ou se, 481 trou blesh ootin g, 489-490 op tical d rives DOS CD-ROM d evice d river, 864 DOS SCSI ad ap ter, 863 MSCDEX.EXE, 864-865 p rin ters, 881-882 PostScrip t, 882 p roblem s, 907 rem ote (p rin ter su p p ort), 901-902 ROM startu p , 305 sou n d card , 563, 570 vid eo ad ap ters, 533 con figu rin g, 534-535 W in d ows Disp lay Con trol Pan el, 534 W in d ows con figu rin g, 899-900 in stallin g, 898-899 p rin ter su p p ort, 897-900

1462

Drive Select

Drive Select (DS), 778 drives ATA-2/ ATA-3 IDE (In tegrated Drive Electron ics), 621-623 cartrid ge, 799-802 Jaz d rives, 801-802 Sp arQ d rives, see Sp arQ d rives Syq u est d rives, 801 tap e d rives, see tap e d rives Zip d rives, see Zip d rives CD-ROM, 28-29, 963 access tim es, 831-832 beam sp litter, 827 bootin g from , 963 bu ffers, 832 cad d ies, 825 CD-R (CD-Record able), 964 CD-RW (CD-Rewritable), 964 con figu rin g, 855-856 DVD-ROM d rives, 964 error correction , 827 extern al, 856-858 form ats, 839-846 in stallin g, 854, 862-866 in tern al, 858-860 in terp olatin g m issin g d ata, 828 laser d iod es, 827 load in g m ech an ism s, 835-836 m u lti-sp eed , 826 PD-ROM com bo d rives, 963 p h otod etector, 827 p h ysical in terface, 832-835 p ortable com p u ters, 931 server m otors, 827 software storage n eed s, 828 sou n d card con n ectors, 569-570 sp ecification s, 829-846 sp eed s, 830 writable, 846-850 DVD (Digital Versatile Disc), 28-29, 851 con figu rin g, 855-856 extern al, 856-858 h istory of, 851 in stallin g, 854, 862-866 in tern al, 858-860 sp ecification s, 851-852 stan d ard s, 853-854

flop p y d isk, 28, 770-795, 961 1.2M 5 1/ 4-in ch , 786-787, 961 1.44M 3 1/ 2-in ch , 783 2.88M 3 1/ 2-in ch , 779-780, 784-787 360K 5 1/ 4-in ch , 787 5 1/ 4-in ch form at, 779-780 720K 3 1/ 2-in ch , 785-786 align m en t, 794-795 cables, 777-778 circu it board s, 775 clean in g, 793-794 clu sters, 781 com bo d rives, 961 con n ectors, 776-778 con trollers, 775-776 cylin d ers, 781 d iskette ch an gelin e, 781-782 DOS in terfacin g, 1049-1053 facep lates/ bezels, 776 h ead actu ator m ech an ism s, 774 logical d isk form atted p aram eters, 783 m axim u m root d irectory, 1074 op eratin g system d isk u sage, 779 p h ysical op eration , 779 p ortable com p u ters, 931 p ower con su m p tion , 419 read / write h ead s, 771-774 rep airin g, 793-795 sp ecification s, 778-779 sp in d le m otors, 774-775 track-wid th sp ecification s, 779 h alf-h eigh t d rives, 793 h ard d isk, 28, 719-761, 962, 1022, 1352 8-in ch , 732-733 14-in ch , 732-733 ad van cem en ts, 719-720 air filters, 749-750 areal d en sity, 720-722 average access tim e, 756 average seek tim e, 756-759 bad -track, 1079 cap acities, 759-761 con figu ration item s, 753-754

costs, 759 d efragm en tin g, 1022-1024 DOS in terfacin g, 1049-1053 EIDE in terface, 962-963 facep late/ bezel, 753-754 form attin g, 728-734 grou n d in g tabs, 753 h ard d isk tem p eratu re acclim ation , 750-751 h ead actu ator m ech an ism s, 740-749 h ead slid ers, 739-740 h ead / m ed iu m in teraction an alogy, 722-724 IDE p aram eters, 1401-1404 in stallin g, 761-770 in terface con n ectors, 753 logic board s, 752 m axim u m root d irectory, 1074 oxid e record in g m ed ia, 734 p aram eters, 766, 1353-1413 p artion in g, 769 p erform an ce, 755-759 p latters, 720, 732-734 p ortable com p u ters, 931 p ower con n ectors, 753 raw in terface p erform an ce, 757 read / write h ead s, 735-739 reliability, 755 rem ovable, 719 SCSI in terface, 761, 962-963 sectors, 724-728 server req u irem en ts, 687 sh ock m ou n tin g, 759 size con sid eration s, 962 sp in sp eed s, 722 sp in d le m otors, 751-752 th in -film , 734-735 track d en sities, 722 tran sfer rates, 756 trou blesh ootin g, 770 ven d ors, 1239 viru s ch eckin g, 1024 IDE, see IDE Im ation LS-120, 962 Jaz, 846, 962, 1205 d isk stru ctu res, 1066 FAT32 p artition s, 1082

dynamic execution

m axim u m root d irectory, 1074 system backu p s, 1012-1013 ju m p erin g as m asters, 855 as slaves, 855 LS-120 d isk (m axim u m root d irectory), 1074 SCSI, 420 Sp arq d rives (m axim u m root d irectory), 802, 1074 sp ecification s, 802 rem ovable d rives, com p arin g, 802-804 swap p able bays (p ortable com p u ters), 932 tap e backu p (ven d ors), 1245 8m m tap e, 814 backu p software, 820-821 cap acities, 817 cost, 818 DAT stan d ard s, 812-814 d ata th rou gh p u t, 818 DLT stan d ard s, 814-815 in stallin g, 819-820 p ortable, 818-819 QIC stan d ard s, 807-812 software com p atibility, 817-818 Travan cartrid ge tap e, 815-816 ven d ors, 1245 Zip , 961 m axim u m root d irectory, 1074 p ortable com p u ters, 931 DriveSpace disk co m pressio n (MS-DOS 6.22), 1040 drum s (prin ters), 885-886 corotron , 886 d etac, 887 DS (Drive Select), 778 dSalvage Pro fessio n al, 1191 DSPs (Digital Sign al Pro cesso rs), so un d cards, 569 DSTN (do uble-layer supertw ist n em atic), passive m atrix displays, 915 DSWAP.EXE, 1056 DTV (Deskto p Video bo ards), 540 cod ecs, 540-541 Cin ep ak (VFW ), 541 In d eo (VFW ), 541 JPEG (Join t Ph otograp h ic Exp erts Grou p ), 541

Microsoft Vid eo 1 (VFW ), 541 MPEG (Motion Pictu res Exp ert Grou p ), 541 color p alettes, 540 d isk sp ace con su m p tion , 540 req u ired h ard ware, 542 (S-Vid eo con n ectors), 542 Dual Cavity PGA packagin g (Pen tium Pro CPUs), 130 dual drives, ATA IDE, co n figurin g, 615 dual in lin e m em o ry m o dules, see DIMMs dual in depen den t bus arch itecture, see DIB Dual In lin e Mem o ry Mo dules, see DIMMs Dual In lin e Package, see DIP ch ips dual pro cessin g Pen tiu m CPUs, 124 Pen tiu m II CPUs, 152 Pen tiu m -MMX CPUs, 124 dual scan LCDs, see passive m atrix LCDs dual serial po rt co n tro llers (Super I/ O ch ips), 207 dual-plan e vo ltage AMD-K6 CPUs, 154 Pen tiu m -MMX CPUs, 72-73 dual-po rted VRAM, 530 dual-scan LCDs, see do uble scan LCDs duplicate m asters, stam pin g CD-ROMs, 825 dusters (co m pressed gas), 1017 duty cycle (prin ter speed), 894 DV (digital video ), FireWire (IEEE 1394), 605 DVD (Digital Versatile Disc), 851 con figu rin g as p rim ary (m aster) d rive, 855 as secon d ary (slave) d rive, 855 SCSI d rives, 856 extern al d rives, con n ectin g, 857-858 h istory of, 851 Mu ltim ed ia CD stan d ard , 851 Su p er Den sity stan d ard , 851

1463

in stallin g d rives, 854, 862-863 bootu p testin g, 865-866 DOS CD-ROM d evice d river, 864 DOS SCSI ad ap ter d river, 863 in terface ad ap ters, 854 MSCDEX.EXE, 864-865 W in d ows 9x, 866 W in d ows NT 4.0, 866 in tern al d rives con n ectin g, 858-859 SCSI ch ain s, 860-861 sp ecification s, 851-852 backward com p atibility, 852 cap acities, 852 stan d ard s, 853 Divx, 853 DVD+RW (DVD Ph ase Ch an ge Rewritable), 854 DVD-R, 853 DVD-R/ W , 854 DVD-RAM, 853 writable d rives, 853 DVD-ROMs, 28-29, 964 trou blesh ootin g, 867 cap acity p roblem s, 868 clean in g d iscs, 867 clean in g read len ses, 868 W in d ows 9x p roblem s, 868 DVOMs (Digital Vo lt Oh m Meters), 428 Dvo rak keybo ards, 472 DX2 CPUs (Cyrix / TI 486), 104 DX2/ OverDrive pro cesso rs, 99-101 DX4 CPUs, 101 Cyrix/ TI 486, 104 DX4 OverDrive pro cesso rs, 101 dye sublim atio n prin ters, 893 dyn am ic bass bo o st, see DBB sw itch dyn am ic ex ecutio n Pen tiu m II CPUs, 127-128, 142 bran ch execu tion , 128 d ataflow an alysis, 128 sp ecu lative execu tion , 128 Pen tiu m Pro CPUs, 127-128 bran ch execu tion , 128 d ataflow an alysis, 128 specu lative execu tion , 128

1464

dynamic impedance stabilization

dyn am ic im pedan ce stabilizatio n , see DIS Dyn am ic Po w er Man agem en t Arch itecture (DPMA, 20 dyn am ic RAM, see DRAM

E early to ken release (To ken Rin g adapters), 702 EBCDIC ch aracter co des, 1334 ECC (Erro r Co rrectin g Co de), 351-352 CD-ROM an d au d io CD d ifferen ces, 826 Pen tiu m II CPUs, 145 red u cin g m em ory errors, 346 SEC-DED, 351 ECHS (Ex ten ded Cylin der Head Secto r), 979 ECP (En h an ced Capabilities Po rts), 596 EDC (Erro r Detectio n Co de), 826 edgeligh tin g, LCDs (liquid crystal displays), 503 EDIT.COM (Win do w s 9x DOS), 1416 editin g h ard disks (secto r level), 1094 edito rs (m ach in e lan guage assem blers), 1032 EDLIN co m m an d (retired fo r Win do w s 9x ), 1418 EDO (Ex ten ded Data Out) RAM, 20, 190, 315-316, 960 ch ip set su p p ort, 316, 957 FPM com p arison s, 316 SDRAM, 316 vid eo m em ory, 530 EEPROM (Electrically Erasable PROM), 208, 309-311, 525, 958 Flash ROM BIOS, 217 recovery, 220-221 u p grad es, 217-219 efficien cy (PSUs), 416 EGA (En h an ced Graph ics Adapter), 366, 515 ch aracter sets in m em ory, 516 IBM En h an ced Color Disp lay, 516 resolu tion , 515

EIDE (En h an ced IDE), 621, 962-963 ATAPI (ATA Packet In terface), 624-625 BIOS, 621-623 CD-ROM d rives, 834 d ata tran sfer sp eed s, 623-624 DMA m od es, 624 h ard d isk d rives (p ortable com p u ters), 931 EISA (Ex ten ded In dustry Stan dard Arch itecture), 20, 24, 185, 246-249, 531 486 p rocessors, 187 DMA ch an n els, 276-277 settin g u p , 247 electric m o n ito r em issio n s, 508 Electrically Erasable PROM see EEPROM electricity, 391 in p u t ran ge, 415 p eak in ru sh cu rren t, 415 see also voltages electro m agn etic spectrum , 1343-1344 electro m agn etism , 709-710 electro static disch arge, see ESD elevato r seekin g algo rith m s (disk space allo catio n ), 1049 ELF (ex trem ely lo w frequen cy), 508 em bedded SCSI (Sm all Co m puter System In terface), 626 em bedded servo m ech an ism s, 746-747 em beddin g vo ice an n o tatio n s, 558 EMI, 1029 em issio n s (m o n ito r en ergy co n sum ptio n ), 508 costs d ifferen ces, 509 ELF (extrem ely low freq u en cy), 508 VLF (very low freq u en cy), 508 EMM386.EXE, 388 em pty cycles, see w ait states EMS (Ex pan ded Mem o ry Specificatio n ), 379-380 em ulatio n (So un d Blaster), 550

en abler so ftw are (PC Cards), 936 gen eric, 937 p oin t, 937 sp ecific, 937 en co der/ deco der, 608 en co din g data (n etw o rk in terface adapters), 692 en co din g sch em es, 608-609, 712-716 ARLL (Ad van ced Ru n Len gth Lim ited ), 715 com p arison s, 716-717 FM (Freq u en cy Mod u lation ), 714 MFM (Mod ified Freq u en cy Mod u lation ), 714 RLL (Ru n Len gth Lim ited ), 715-716 en dec (en co der/ deco der), 608, 713 en ergy co n sum ptio n , m o n ito rs, 507 em ission s, 508-509 p ower m an agem en t, 507-508 En ergy Star requirem en ts (m o n ito rs), 423, 507 En h an ced 101-key keybo ards, 448 con n ectors, 448 foreign lan gu age version s, 449 layou t, 449 rem ovable keycap s, 449 En h an ced Capabilities Po rts, see ECP En h an ced Graph ics Adapter, see EGA En h an ced IDE, see EIDE en h an ced m usic CDs (m ix ed m o de CDs), 844 En h an ced Serial Po rts (ESP), 589-590, 595-596 En h an ced Sm all Device In terface, 609-611, 1137 en try lim its (ro o t directo ries), 1074 EPIC (Ex plicitly Parallel In structio n Co m putin g), 160 epileptics (screen flicker), 507 EPP (En h an ced Parallel Po rts), 595-596 EPROM (Erasable PROM), 308-309, 458, 792

expansion slots

equipm en t m ain ten an ce, 999-1000 En glish an d m etric th read system s, 1005 h an d tools, 1000-1004 h ard ware typ es, 1004 sold erin g an d d esold erin g, 1005-1007 testin g, 1007 breakou t boxes, 1008 logic p robes, 1009 logic p u lsers, 1009 loop back con n ectors, 1007 m em ory testers, 1010-1011 m eters, 1008 m u ltim eter, 1007 ou tlet testers, 1009-1010 voltm eter, 1007 Erasable Pro gram m able Read On ly Mem o ry, see EPROM ERASE co m m an d (Win do w s 9x DOS), 1415 erasers (EPROM), 309 ergo n o m ic keybo ards, 451, 473 Errata No . 23, see FDIV bug Erro r Co rrectin g Co de, see ECC Erro r Co rrectio n Co de field Mod e 1 CD-ROM-XA d ata typ e), 841 Mod e 2, Form 1 CD-ROMXA d ata typ e, 842 Erro r Detectio n Co de field Mod e 1 CD-ROM-XA d ata typ e, 841 Mod e 2, Form 1 CD-ROMXA d ata typ e, 842 Erro r Detectio n Co de, 826 erro r-co rrected m em o ry (430HX ch ipset), 193 erro r-co rrectio n pro to co ls (m o dem s), 663 MNP 1-4, 664 V.42, 664 erro rs bit (CD-ROM d rives), 827 boot p rocess sector, 1044-1047 vid eo ROM, 1043 cod es (DOS In terru p t 13h ), 1052

correction CD-ROM d rives, 827 DVD (Digital Versatile Disc), 852 d etection Pen tiu m II, 129 Pen tiu m Pro, 129 FAT, 1086 corru p tion , 1087 cross-lin ked files, 1087 in valid files/ d irectories, 1087 lost clu sters, 1086-1087 rep airin g, 1086-1087 m em ory, red u cin g with ECC, 346 m essages (BIOS), 222-22 n otification s, assign in g sou n d s, 558 p arity (p ower su p p lies), 427 POST au d io cod es, 985 AMI BIOS, 986 Ph oen ix BIOS, 986-988 POST I/ O p ort cod es, 988-989 POST visu al cod es, 988 soft m em ory errors, 312, 344-346 alp h a-p articles, 344-345 cosm ic rays, 345 ECC, 351-352 fau lt toleran ce, 346 p arity ch eckin g, 347-351 sou n d card Ch ip set Setu p op tion s, 579 com p u ter won ’t start, 578 joystick p roblem s, 578-579 locku p s, 578 low volu m e, 577 n o sou n d , 576-577 on e-sid ed sou n d , 577 p arity errors, 578 scratch y sou n d , 578 ES (En gin eerin g Sam ple), OverDrive steppin gs tables, 123 escape co des, 877 ESD (electro static disch arge) assem blin g system s, 969-971 m em ory in stallation , 355 clean in g system s, 1021 p rotection kits, 1003

1465

ESDI (En h an ced Sm all Device In terface), 609-610, 753, 1137 ESP (En h an ced Serial Po rts), 589-590, 595-596 ET6000 video adapter, 539 Eth ern et adapters, 689, 1235 con n ectors, 690 Man ch ester d ata en cod in g, 692 Eth ern et Fram e, 700 Eth ern et in terfaces (CATV n etw o rks), 674 Eth ern et pro to co l, 700 100Mbp s Eth ern et, 704 100BaseT, 704 100VG, 705 stan d ard s, 704 backoff in tervals, 701 Eth ern et Fram e, 700 Med ia Access Con trol, 700 p acket collision s, 701 Ph ysical layer sp ecification s, 700 even t n o tificatio n s (assign in g so un ds), 558 Even t View er (Win do w s NT), 998 EXIT co m m an d (Win do w s 9x DOS), 1415 EXPAND.EXE (Win do w s 95 CD-ROM), 1417 ex pan ded m em o ry, 359, 379-380 ex pan sio n cards in stallin g (assem blin g system s), 976 vid eo ad ap ters, 500 ex pan sio n slo ts (I/ O bu s), 238-239 AGP p orts, 268-269 ATX m oth erboard s, 952 EISA (Exten d ed ISA) bu s, 246-249 settin g u p , 247 IBM PC, 1101 sp ecification s, 1108 IBM PC AT, 1130, 1144 IBM PC XT, 1116, 1122 IBM PC XT Mod el 286, 1146, 1150 IBM Portable PC (sp ecification s), 1128 in sertin g ad ap ters (sou n d card s), 572

1466

expansion slots

ISA bu s, 239-240 8-bit, 240 16-bit, 241-243 32-bit, 244 local bu ses, 250-252 PCI, 256-268 VL (VESA local), 252-256 LPX m oth erboard s, 171 MCA bu s (Micro Ch an n el Arch itectu re), 245-246 riser card s (Low Profile system s), 949 Ex plicitly Parallel In structio n Co m putin g, see EPIC ex ten ded ASCII keyco des fo r ANSI.SYS, 1333-1334 Ex ten ded Cylin der Head Secto r, 979 Ex ten ded Data Out RAM, see EDO RAM ex ten ded DOS partitio n s (m aster partitio n bo o t secto r), 1067-1068 eXten ded Graph ic Array, see XGA Ex ten ded In dustry Stan dard Arch itecture, see EISA ex ten ded m em o ry, 360, 376-377 HMA (High Mem ory Area), 378-379 XMS (exten d ed m em ory sp ecification ), 377 ex ten ded parallel po rts, 595 ex ten sio n s, file (ro o t directo ries), 1073 ex ten ts (NTFS MFT), 1096 n on residen t attribu tes, 1096 ex tern al cach e, see L2 cach e ex tern al CD-ROM drives, 837 ex tern al data buses Pen tiu m CPUs, 105 Pen tiu m II CPUs, 143 Pen tiu m Pro CPUs, 132 vs. in tern al d ata bu ses, 39 ex tern al displays (po rtable co m puters), 942 LCD p rojectors, 943 overh ead LCD p an els, 943 TV-ou t con n ection s, 943-944 ex tern al drives, SCSI, co n n ectin g, 856-858 ex tern al h ardw are in terrupts, 272 ex tern al lo o pback tests (serial po rts), 592

ex tern al m o dem s, 670 ex tern al packagin g (Pen tium CPUs), 105 ex tern al PS/ 2 co n n ecto rs (sin gle-en ded SCSI), 636-637 ex tern al sh ielded co n n ecto rs (sin gle-en ded SCSI), 636-639 ex tern al speakers, 579-581 am p lification , 579 batteries, 580 DBB switch (d yn am ic bass boost), 580 freq u en cy resp on se, 580 THD (Total Harm on ic Distortion ), 580 wattage, 580 ex tern al tape drives, in stallin g, 820 ex tern al term in ato rs (SCSI), 642 ex tern al Win do w s 9x DOS co m m an ds, 1415-1416 EXTRACT.E XE (Win do w s 9x DOS), 1416 ex trem ely lo w frequen cy, 508 EZ Co py, 1211 EZ Drive, 1211 EZSTART pro gram (SMC n etw o rk diagn o stics), 990

F / F (Fix ) sw itch (CHKDSK co m m an d syn tax ), 1089 faceplates flop p y d isk d rives, 776 h ard d isk d rives, 753-754 failures cosm ic ray (SRAMs), 345 p ower su p p lies, trou blesh ootin g, 426-430 tran sistors active m atrix LCDs, 916 LCD costs, 503 p assive m atrix LCDs, 914 see a lso defects;erro rs Failures in Tim e, see FIT fan co n n ecto rs, 230 Fan C sign al (ATX o ptio n al po w er co n n ecto rs), 406 Fan M sign al (ATX o ptio n al po w er co n n ecto rs), 406 fan s ATX form factors, 398 ATX m oth erboard s, 174, 952

CPUs, 399-401, 966-967 SPX form factors, 402 fast disk (32-bit Win do w s 3.1 disk access), 1057 Fast Page-Mo de RAM, 527 Fast SCSI, 632 Fast-20 m o de (Ultra-SCSI), 629, 632 Fast-40 m o de (SCSI), 632 fasten ers (En glish an d m etric th read system s), 1005 FASTHELP co m m an d (retired fo r Win do w s 9x ), 1418 Fastlyn x , 1224 FASTOPEN co m m an d (retired fo r Win do w s 9x ), 1418 FAT (File Allo catio n Table), 731, 1065 d isk stru ctu res, 1065-1066 d am age, 1067 d ata area, 1079 d iagn ostic read -an d -write cylin d er, 1079 FATs (File Allocation Tables), 1076-1077 m aster p artition boot sector, 1067-1070 root d irectories, 1073-1075 volu m e boot sectors, 1071-1072 errors, 1086 cross-lin ked files, 1087 FAT corru p tion , 1087 in valid files/ d irectories, 1087 lost clu sters, 1086-1087 rep airin g, 1086-1087 file system u tilities, 1088 CHKDSK com m an d , 1088-1091 Disk Defragm en tation (W in d ows 95), 1093 NDIAGS, 1095 Norton Calibrate, 1094 Norton Disk Doctor, 1094 Norton Disk Ed itor, 1094 RECOVER com m an d , 1091 SCANDISK com m an d , 1091-1092 Sp eed Disk (Norton Utilities), 1093 VFAT (Virtu al File Allocation Table), 1079-1081 backward com p atibility, 1079

files

lon g file n am es, 1080-1081 VCACHE m od e, 1079 FAT16 file system errors, 1086-1087 cross-lin ked files, 1087 FAT corru p tion , 1087 in valid files/ d irectories, 1087 lost clu sters, 1086-1087 p artition s clu ster lim its, 1085 FAT32 con version , 1085-1086 FAT32 Co n versio n Wizard, 1085 FAT32 file system , 731 , 1061, 1082 clu sters, 1082 sizes, 1083-1084 errors, 1086 cross-lin ked files, 1087 FAT corru p tion , 1087 in valid files/ d irectories, 1087 lost clu sters, 1086-1087 m irrorin g, 1084 Partition Magic, 1086 p artition s creatin g, 1084-1085 FAT16 con version , 1085-1086 Jaz d rives), 1082 root d irectory location s, 1083 fatal erro rs Ph oen ix BIOs POST au d io error cod es, 986-987 POST (Power-On Self Test), 985 fault to leran ce (so ft m em o ry erro rs), 346 ECC, 351-352 p arity ch eckin g, 347-351 fax m o dem stan dards, 666 Grou p III p rotocol, 667 Class 1, 667 Class 2, 667 Grou p IV p rotocol, 667 FC.EXE (Win do w s 9x DOS), 1416 FCC (Federal Co m m un icatio n s Co m m issio n ), 417 FDDI (fiber distributed data in terface), 703

FDISK pro gram , 760, 769 d rive form attin g, 769 FAT cop ies, 1077 FAT d isk stru ctu res, 1066-1069 d ata area, 1079 d iagn ostic read -an d -write stru ctu re, 1079 m aster p artition boot sector, 1067-1070 root d irectories, 1073-1075 volu m e boot sectors, 1071-1072 FAT16 file system (errors), 1086-1087 FAT32 file system , 1082 clu ster sizes, 1082-1084 errors, 1086-1087 FAT16 p artition con version , 1085-1086 m irrorin g, 1084 p artition s, creatin g, 1084-1085 root d irectory location s, 1083 FDISK.EXE (Win do w s 9x DOS), 1416 FDIV bug (Flo atin g Po in t Divide), Pen tium CPUs, 114-116 Federal Co m m un icatio n s Co m m issio n , 417 FEELit m o use, 496 Ferrite read/ w rite h eads (h ard disk drives), 737 ferro reso n an t tran sfo rm ers (SPSs), 439 Fiber Ch an n el SCSI, 632 fiber distributed data in terface, 703 fiber o ptic cablin g (LAN atten uatio n ), 695 FIFO buffer (first in / first o ut), 587 16550A UART ch ip , 589 fifth gen eratio n pro cesso rs, see Pen tium CPUs;Pen tium MMX CPUs;Pen tium co m patible CPUs;Pen tium II CPUs;Pen tium Pro CPUs; File Allo catio n Table, see FAT file n am es, lo n g (VFAT), 1079-1081 NTFS file system , 1095

1467

VFAT, 1079-1080 8.3 alias n am es, 1081 assign in g, 1080 backward com p atibility, 1081 LFNBK.EXE (W in d ows 9x), 1081 storin g, 1080-1081 file system s FAT u tilities, 1088-1095 FAT16 errors, 1086-1087 FAT32, 1082 clu ster sizes, 1082-1084 FAT16 p artition con version , 1085-1086 m irrorin g, 1084 p artition s, creatin g, 1084-1085 root d irectory location s, 1083 NTFS, 1095 clu ster rem ap p in g, 1097-1098 com p atibility, 1096-1097 d isk m irrorin g, 1097 d isk strip in g with p arity, 1097 lon g file n am es, 1095 MFT (Master File Table), 1096 p artition s, creatin g, 1097 files, 1003 con tigu ity tests (CHKDSK com m an d ), 1089 cross-lin ked (FAT errors), 1087 d efragm en tin g, 1022-1023 p ackin g, 1023 sortin g, 1023 W in d ows 98, 1024 W in d ows 9x, 1023 DOS d isk sp ace allocation , 1048 clu sters, 1048-1049 overwritin g files, 1049 fragm en ted (CHKDSK com m an d syn tax), 1089 in valid (FAT errors), 1087 lon g file n am es (NTFS), 1095 MIDI, 553 ch an n els, 553 d evice con n ectivity, 555-556 FM syn th esis, 554 Gen eral MIDI stan d ard , 554

1468

files

p layin g, 554-555 software, 556 storin g, 553 overwritin g (d isk sp ace allocation ), 1049 p ackin g (h ard d isk m ain ten an ce), 1023 root d irectories, 1073 d ate/ tim e of last ch an ge, 1073 file attribu te byte, 1073 file n am es an d exten sion s, 1073 lin k to start clu ster, 1073 sizes, 1073 su bd irectories, 1073 sortin g (h ard d isk m ain ten an ce), 1023 sou n d (resolu tion s), 553 tracin g (root directories), 1074 filters glare-red u cin g, 512 p olarizin g, LCDs (liq u id crystal d isp lays), 501 FIND.EXE (Win do w s 9x DOS), 1416 fin din g clean in g su p p lies, 1019 com p on en ts (u p grad in g p ortables), 913 FireWire (IEEE 1394), 604-605 firm w are, see ROM First Aid 9X, 1193 first gen eratio n pro cesso rs 80186, 84 80188, 84 8086, 83 8087 m ath cop rocessor, 84 ad d ress bu s wid th , 83 cost, 83 8088, 83 IBM PC, 84 sp eed s, 84 first in / first o ut, see FIFO buffer first-gen eratio n Pen tium CPUs, 109-110 m an u factu rin g p roblem s, 109 OverDrive u p grad es, 110 FIT (Failures in Tim e), 345 Fix It, 1222 fix ed disk drives, 719 fix ed pix els, 502 fix ed refresh rates, 501

fix ed-frequen cy m o n ito rs, 509 Flash ROM, 309-311, 369, 525, 958 p ortable com p u ters (h ard d rive su p p ort), 931 recovery, 220-221 u p grad es, 217-219 see also EEPROM flash ligh ts, 1003 flat ph o sph o r-based screen s, 501 flat sh adin g (ren derin g 3D im ages), 543 Flat Square Tech n o lo gy, 1208 flicker, 500, 506, 510, 515, 538 Flo atin g Po in t Divide, see FDIV flo atin g po in t un its, see FPUs flo ppy co n tro llers (Super I/ O ch ips), 207 flo ppy disk drives, 28, 770-795, 961 3 1/ 2-in ch 1.44M, 783 2.88M, 784-785 720K, 785-786 5 1/ 4-in ch 1.2M, 786-787 360K, 787 align m en t, 794-795 cables, 777-778 circu it board s, 775 clu sters (d efau lt sizes), 781 com bo d rives, 961 con n ectors, 776-778 con trollers, 775-776 sp eed d ifferen ces, 25 cylin d ers, 781 d iskette ch an gelin e, 781-782 DOS in terfacin g, 1049 con troller p ort com m an d s, 1052-1053 In terru p t 13h , 1050-1052 In terru p t 21h , 1050 In terru p t 25h , 1050 In terru p t 26h , 1050 facep lates/ bezels, 776 form attin g, 725 h ead actu ator m ech an ism s, 774 IBM PC, 1101 IBM PC AT, 1130 IBM PC XT, 1115 in stallin g, 793 logical d isk form atted p aram eters, 783

m axim u m root d irectory, 1074 op eratin g system d isk u sage, 779 3 1/ 2-in ch form at, 779-780 5 1/ 4-in ch form at, 779-780 p h ysical op eration s, 779 p ortable com p u ters, 931 read / write h ead s, 771-774 rep airin g, 793-795 align in g, 794-795 clean in g, 793-794 sp ecification s, 778-779 sp in d le m otors, 774-775 track-wid th sp ecification s, 779 flo ppy disks, 28 d rives, see flop p y d isk d rives FAT stru ctu res, 1065-1066 d am age, 1067 d ata area, 1079 d efau lt clu ster sizes, 1077-1078 d iagn ostic read -an d -write stru ctu re, 1079 FATs (File Allocation Tables), 1076-1077 root d irectories, 1073-1075 volu m e boot sectors, 1071-1072 m ed ia sp ecification s, 789-790 p h ysical con stru ction , 787-793 testin g (Drive Probe), 795 u tilities (Norton DiskTool), 1094 flo ptical drives, m agn etic m edia, 797-799 flux m agn etic fields, 608, 710 flux reversal, 710 FM (Frequen cy Mo dulatio n ) syn th esis, 714 p layin g MIDI files, 554 W ave Blaster, 568 fo am elem en t m ech an ical keysw itch es, 455-456 fo lders, see directo ries Fo lio VIEWS in fo base so ftw are, 1199 fo n ts, prin ter, 878-881 bitm ap , 879-880 m on osp aced , 879

GammaTech Utilities

p oin ts, 879 p rop ortion al, 879 san s serif, 879 scalable, 879-881 serif, 879 soft fon ts, 880 Fo n ts page (prin ter drivers), settin gs, 900 fo rce feeback (gam e co n tro llers), 497 Fo rced Perfect Term in atio n (SCSI), 640 fo rced-air co o lin g system s, 1013-1014 fo rm facto rs, 393 cases, 949 d esktop , 950 Low Profile, 949 m in i-tower, 950 tower, 950 in d u stry stan d ard typ es, 394-396 AT/ Desk style, 395 AT/ Tower style, 396-397 ATX style, 398-401, 405 Baby AT style, 397-398 LPX style, 397-398 NLX style, 401-402 PC/ XT style, 395 SFX style, 402 m oth erboard s, 167, 950 ATX, 75, 173-175, 950-952 Baby-AT, 167-169, 950-951 fu ll-size AT, 169-170, 951 LPX, 170-173 m icro-ATX, 952 NLX (Low Profile ATX), 176-179, 949, 952 p rop rietary, 179-180, 180-181 Pen tiu m Pro CPUs (h eat p roblem s), 134 p ortable com p u ters lap top s, 910 n otebooks, 910 su bn otebooks, 910 p ower su p p lies, 433 Low Profile, 949 p rop rietary d esign s, 433 p rop rietary (backp lan e system s), 181 PSU (p ower su p p ly), 393-394 recom m en d ation s, 295

FORMAT co m m an d (vo lum e bo o t secto rs), 1072 FORMAT.COM, 769 boot d isks, creatin g, 1036 W in d ows 9x DOS, 1416 fo rm ats CD-ROM d rives CD-DA (Digital Au d io), 840 CD-ROM-XA (Exten d ed Arch itectu re), 840-843 High Sierra, 839 ISO 9660 d ata stan d ard , 839 m ixed m od e, 843-844 Ph otoCDs, 844-846 h ard d isk d rives, 728-734, 767-770 d rive p artition in g, 769 HLF (High -Level Form attin g), 731-732, 769-770 LLF (Low-Level Form attin g), 728-731, 767-769 p artition in g, 731 laser p rin ter p rin tin g p rocess, 884 root d irectories, 1074-1075 sou n d files, 552 fo rm attin g h ard disk drives, 728-732, 767-770 d rive p artition in g, 769, 731 HLF (High -Level Form attin g), 731-732 LLF (Low-Level Form attin g), 728-731 fo ur-w ay set asso ciative cach e (Pen tium Pro CPUs), 130 fo urth gen eratio n pro cesso rs, see 80486 CPUs Fo x Pro Adviso r, 1194 FPM (Fast Page Mo de) DRAM, 314-315 FPM DRAM (Fast Page-Mo de RAM), 527 FPUs (Flo atin g Po in t Un its) 486 CPUs, 93 486DX CPUs, 96-97 487SX, 98-99, 103 80287, 86 80387, 90 8087, 84 CPUs, 74 bu ilt-in , 75-77 m axim u m sp eed s, 76 sp ecification s, 77

1469

Pen tiu m CPUs, 105, 109 FDIV bu g, 114-116 Pen tiu m II CPUs, 143 Pen tiu m Pro CPUs, 132 W eitek, 90 fragm en ted files, 1022-1023, 1088 CHKDSK com m an d syn tax, 1089 W in d ows 98 (Main ten an ce W izard ), 1024 W in d ows 9x, 1023 fram e fo rm atio n (n etw o rk in terface adapters), 691 fram e-buffers (video ch ipsets), 526 freo n (stan dard clean ers), 1016 Frequen cy Mo dulatio n , see FM frequen cy respo n se, 509-510 sou n d card s, 563 sp eakers, 580 frettin g co rro sio n , 341 FSK (frequen cy-sh ift keyin g), 661 FTP (File Tran sfer Pro to co l), 708 full duplex pro to co ls, 661 full-m o tio n video , 540 full-size AT m o th erbo ards, 169-170, 951 see also Baby-AT m oth erboard s full to w er cases, 949 fun ctio n keys, 453 fuzzy prin t, 904

G gam e adapter in terfaces (so un d cards), 551 Gam e Blaster so un d card (Creative Labs), 549 gam in g con trollers, 496-498 PC-com p atible con n ectors, 498 sou n d card s, 549-551 com p atibility, 549 Gam e Blaster, 549 gam e p orts, 551 MIDI su p p ort, 550 Sou n d Blaster, 550 stan d ard s, 550, 563 gam m a rays (electro m agn etic spectrum ), 1344 Gam m aTech Utilities, 1226

1470

gang-programmers

gan g-pro gram m ers, 308 gan ged h eads, 735 gas plasm a displays, 503 p ortable com p u ters, 917 Gatew ay, 19 gath er read (DMA ch an n els), 277 GDI.EXE W in d ows 3.11 u p d ates, 1054 W in d ows 3.x core files, 1057 Gen eral Page (Win do w s 9x Mo use Co n tro l Pan el), 486 gen eral-purpo se diagn o stic so ftw are, 991 #1-Tu ffTEST, 994 AMIDiag, 992 Ch eckit Pro, 992 Micro-Scop e, 993 Norton Utilities, 993-994 PC Tech n ician , 994 PC-Diagn osys, 994 QAPlu s/ FE, 994-995 gen eric 30-pin SIMMs, 327 gen eric en able so ftw are (PC Card m em o ry requirem en ts), 937 gen lo ckin g adapters (bro adcastin g screen s o n televisio n ), 538 geo m etry (ren derin g 3D im ages), 544 glare filters, 512 glass, Mem Co r, 733 Glidepo in t po in tin g device (Alps Electric), 495 Glin t graph ics accelerato rs, 1178 GM Veh icle Calibratio n In fo rm atio n Web site, 310 go ld-plated m em o ry co n tacts (co m pared to tin -plated co n tacts), 340-344 Go uraud sh adin g (ren derin g 3D im ages), 543 GRAFTABL co m m an d (retired fo r Win do w s 9x ), 1418 graph ics bitm ap , 875 p rin tin g, 885 vector, 875 see also im ages graph ics cards, see video , adapters Graph ics page (prin ter drivers), 899-900 GRAPHICS.COM (Win do w s 95 CD-ROM), 1417

gray co de, 744 grease (h eat sin ks), 298 green m o n ito rs, 508 Green PCs (Pen tium po w er m an agem en t bugs), 116 green w ires (po w er sw itch co n n ecto rs), 407 gro un din g lo o ps in stallin g sou n d card s, 572 twisted p air cable, 693 gro un din g tabs (h ard disk drives), 753 Gro up III fax pro to co l, 667 Class 1, 667 Class 2, 667 Gro up IV fax pro to co l, 667

H HAL (h ardw are abstractio n layer), Win do w s NT, 1063 h alf-h eigh t drives, 793 h alf duplex pro to co ls, 661 HALT in structio n (Pen tium po w er m an agem en t bugs), 116 h an d to o ls, 1000 ch ip extractors, 1001 ESD (electrostatic d isch arage) p rotection kit, 1003 files, 1003 flash ligh ts, 1003 h em ostats, 1003 n u t d rivers, 1001 p arts grabber, 1002 p liers, 1003 screwd rivers (m agn etic tip s), 1001 Torx d river, 1003 tweezers, 1002 vise, 1003 wire cu tter/ strip p er, 1003 h an dicapped users (vo ice co m m an d so ftw are), 559 h an ds-o n ex perien ce, 1165-1166 h an dsh akin g, 883 h ard disk drives, 28, 719-761, 962, 1022, 1352 8-in ch , 732-733 14-in ch , 732-733 ad ju stin g to altitu d es, 750 ad van cem en ts, 719-720 air filters, 749-750 areal d en sity, 720-722

average access tim e, 756 average seek tim e, 756-759 backu p s, 1012 tap e d rives, 1012-1013 writable CD-ROM d rives, 1012-1013 Zip / Jaz d rives, 1012-1013 bad -track, 1079 BIOS tables con troller h ead step rate, ch an gin g, 1140 IBM PC AT, 1136-1139 m od ifyin g p aram eter tables, 1139-1140 m od ifyin g p aram eters tables cap acities, 759-761 con figu rin g, 753-754 au tom atic d rive typ in g, 766 m an u al d rive typ in g, 766 con trollers (ven d ors), 728-729, 1132, 1239 costs, 759 d efragm en tin g, 1022-1023 Norton Utilities Sp eed Disk, 1093 W in d ows 95 Disk Defragm en tation u tility, 1093 W in d ows 9x, 1023-1024 DOS in terfacin g, 1049 con troller I/ O p ort com m an d s, 1052-1053 In terru p t 13h , 1050-1052 In terru p t 21h , 1050 In terru p t 25h , 1050 In terru p t 26h , 1050 d rive cables, 765 EIDE in terface, 962-963 en cod in g sch em es, 608-609 ESDI (En h an ced Sm all Device In terface), 609-610 facep late/ bezel, 753-754 FAT stru ctu res, 1065-1066 d am age, 1067 m aster p artition boot sector, 1067-1070 FAT16 file system (errors), 1086-1087 FAT32 file system , 1082 clu ster sizes, 1082-1084 errors, 1086-1087 FAT16 p artition con version , 1085-1086 m irrorin g, 1084

hardware

p artition s, creatin g, 1084-1085 root d irectory location s, 1083 FATs (File Allocation Tables), 1076 ch ain s, 1076-1077 clu sters, 1077 d ata area, 1079 d efau lt clu ster sizes, 1078-1079 d iagn ostic read -an d -write stru ctu res, 1079 FDISK cop ies, 1077 h exad ecim al n u m bers, 1076 form attin g, 728-734, 767-770 d rive p artition in g, 769 HLF (High -Level Form attin g), 731-732, 769-770 LLF (Low-Level Form attin g), 725, 728-731, 767-769 p artition in g, 731 grou n d in g tabs, 753 h ard d isk tem p eratu re acclim ation , 750-751 h ead actu ator m ech an ism s, 740-749 au tom atic h ead p arkin g, 748-749 servo m ech an ism s, 744-748 step p er m otor actu ators, 741 voice coil actu ators, 741-743 h ead slid ers, 739-740 IBM PC AT, 1130 IBM PC XT, 1115 IBM PC XT Mod el 286, 1146 IDE, see IDE in stallin g, 761-770 d rive con figu ration s, 762-770 h ost ad ap ter con figu ration s, 762-770 p h ysical in stallation , 764-765 in terface con n ectors, 753 logic board s, 752 m axim u m root d irectory, 1074 m ou n tin g screws, 765

oxid e record in g m ed ia, 734 p aram eters, 766, 1353 AMI ROM BIOS, 1409-1410 Award ROM BIOS, 1411-1412 Com p aq Deskp ro 386, 1408-1409 Con n er Perip h erals, In c., 1355-1357 IBM AT/ PS/ 2, 1406-1408 IBM Corp oration , 1357-1365 Maxtor Corp oration , 1365-1372 Ph oen ix ROM BIOS, 1412-1413 Qu an tu m Corp oration , 1372-1378 Seagate Tech n ology, In c., 1378-1394 Tosh iba, 1394-1397 u ser-d efin able d rive typ es, con figu rin g as, 1401-1405 W estern Digital Corp oration , 1397-1400 p erform an ce, 755-759 cach e p rogram s an d con trollers, 757-767 h ead an d cylin d er skewin g, 758-759 in terleave selection , 758 p latters, 720, 732-734 p ortable com p u ters, 931 BIOS su p p ort, 931 PC Card , 931 u p grad in g, 931 p ower con n ectors, 753 p ower con su m p tion , 419 raw in terface p erform an ce, 757 read / write h ead s, 735-739 record in g settin g (d isassem blin g system s), 979-981 reliability, 755 rem ovable, 719 root d irectories, 1073-1075 d ate/ tim e of last ch an ge, 1073 en try lim its, 1074 file attribu te byte, 1073-1075 file n am es an d exten sion s, 1073

1471

file size, 1073 form ats, 1074-1075 lin k to start clu ster, 1073 organ ization , 1074 su bd irectories, 1073 tracin g files, 1074 SCSI in terfaces, 761, 962-963 sectors, 724-728 INTER-RECORD GAP, 727 POST INDEX Gap , 726 PRE-INDEX GAP, 727 Sector ID d ata, 727 W RITE TURN-ON GAP, 727 server req u irem en ts, 687 sh ock m ou n tin g, 759 size con sid eration s, 962 sp aram eters, u ser-d efin able d rive typ es, con figu rin g as, 1405 sp eed , 722 sp in sp eed s, 722 sp in d le m otors, 751-752 ST-506/ 412 in terface, 607-608 tem p eratu re acclim ation , 750-751 th in -film , 734-735 track d en sities, 722 h ead / m ed iu m in teraction an alogy, 722-724 tran sfer rates, 756 trou blesh ootin g, 770 NDIAGS, 1095 Norton Calibrate, 1094 Norton Disk Doctor, 1094 ven d ors, 1239 viru s ch eckin g, 1024 volu m e boot sectors, 1071-1072 DBR (DOS Boot Record ) form at, 1072-1073 d isk p aram eter blocks, 1071-1072 FORMAT com m an d , 1072 load in g, 1071 selectin g boot drives, 1071 volu m e boot cod e, 1071 h ard erro r rates, see HERS h ard erro rs, see fatal erro rs h ard fails (m em o ry), 344 h ardw are backward com p atibility, 18 d etection (W in d ows 3.x CD-ROM d rives), 866 d evelop m en t (PC 9x sp ecification s), 21

1472

hardware

d iagn ostic software, 989 n etwork in terfaces, 990-991 SCSI d evices, 989-990 d irect access (ROM BIOS), 1035 d isp lays, see LCDs;m on itors flop p y d isk d rives, see flop p y d isk d rives h ard d isk d rives, see h ard d isk d rives IBM, d u p licatin g, 16 IDE/ SCSI com p arison s, 646-651 in d u stry con trol, 18 AGP (Accelerated Grap h ics Port), 20 In tel, 18-20 m em ory su p p ort, 20 system assem blers, 19 system m an u factu rers, 19 in terru p ts, 270-272 8-bit ISA bu ses, 272 16-bit ISA bu ses, 272-274 PC/ XT an d AT d ifferen ces, 25 trou blesh ootin g, 274-275 MIDI con n ectivity, 555-556 m od em s, see m od em s m on itors, see m on itors n etwork (ven d ors), 1242 PNP (Plu g an d Play), 291 p rin ters, see p rin ters p rin tin g p roblem s, 904-906 typ es, 1004 En glish an d m etric th read system s, 1005 screws, 1004 W eb site resou rces, 1247-1249 h ardw are abstractio n layer, see HAL Hardw are Acceleratio n slider (Win do w s Display Co n tro l Pan el), 534-535 Hardw are Design Guide fo r Micro so ft Win do w s 95 (PC 9X), 21 Hardw are Design Guide Supplem en t fo r PC 95 (PC 9x ), 21 h arsh en viro n m en t system s p assive p reven tive m ain ten an ce, 1030

Hayes-co m patibility (m o dem stan dards), 660 HDAs (Head Disk Assem blies), 722 h ead actuato r m ech an ism s flop p y d isk d rives, 774 h ard d isk d rives, 740-749 au tom atic h ead p arkin g, 748-749 servo m ech an ism s, 744-748 step p er m otor actu ators, 741 voice coil actu ators, 741-743 Head Disk Assem blies, see HDAs h ead/ m edium in teractio n an alo gy (h ard disk drives), 722-724 Header field Mod e 2, Form 1 CD-ROMXA d ata typ e, 842 Mod e 2, Form 2 CD-ROMXA d ata typ e, 842 Mod el 1 CD-ROM-XA d ata typ e, 841 h eads align m en t, 773 com p osite ferrite h ead s, 737 crash es, 722 gan ged , 735 m an u al d rive typ in g, 766 Metal-In -Gap , 737 sin gle-gap h ead s, 739 skewin g (h ard d isk p erform an ce), 758-759 slid ers (h ard d isk d rives), 739-740 th in film , 738 Azim u th (h ead p osition m easu rem en t), 742 HeadstartCard, 1179 h eat pro blem s CPUs, 74 ATX m oth erboard s, 75 h eat sin ks, 74 m axim u m safe sp eed s, 37 en viron m en tal tem p eratu re con trol, 1024-1025 m obile Pen tiu m p rocessors, 923 Pen tiu m II m in icartrid ges, 928 TCP (tap e carrier p ackagin g), 923-928

Pen tiu m II CPUs, 145 Pen tiu m Pro CPUs (form factor ch oices), 134 p rotectin g p rocessors (p ortable com p u tin g d esign ), 912 h eat sin ks, 74, 973 active, 74 Am 5x86(TM)-P75 CPU, ju m p erin g, 104 bu ild in g system s, 966-967 clip -on , 1006 CPU m arkin g sch em es, fin d in g u n d er, 37 grease, 298 OverDrive p rocessors, 58 Pen tiu m , 59 p assive, 74 Pen tiu m II CPUs, 145 h elp ap p en d ixes, 1166 d ocu m en tation , 1154-1155 ch ip an d ch ip set level, 1156, 1160-1162 com p on en t level, 1156 system level, 1156-1159, 1163 h an d s-on exp erien ce, 1165-1166 m agazin es, 1163-1164 on lin e (au th or’s em ail ad d ress), 1164 sem in ars, 1165 see also p roblem s; trou blesh ootin g; m ain ten an ce HELP.COM (Win do w s 95 CD-ROM), 1417 HELP.COM (Win do w s 98 CD-ROM), 1417 h em o stats, 1003 Hercules Graph ics Card, 515 HERS (h ard erro r rates), 344 Hertz, Hein rich Rudo lph , 34 Hertz, see Hz Hew lett Packard Prin ter Con trol Lan gu age, see PCL Resolu tion En h an cem en t Tech n ology (RET), 871 h ex adecim al n um bers ASCII con version s, 1326 FATs, 1076 12-bit, 1076 16-bit, 1076

I/ O system

HFC (h ybrid fiber/ co ax ), cable m o dem s, 674 HGC (Hercules Graph ics Card), 515 HI-Flex AMI BIOS, 210 d iagn ostics, 213 ID strin gs, 211-213 h ibern ate m o des (co n servin g batteries), 941 h idden system files (DOS), 1034-1035 h igh capacity QIC drives, 811 h igh DMA (so un d card co n flicts), 576 High Mem o ry Area (HMA), 378-379 h igh perfo rm an ce addressin g, see HPA High Sierra CD-ROM fo rm at, 839 h igh speed m em o ry, see L1 cach e High -Level Fo rm attin g (HLF), 731-732, 769-770 High -Reso lutio n Diagn o stic Diskette (HRD), 795 HiJaak Pro , 1222 HIMEM.SYS, 377, 388, 1059 h isto ry o f perso n al co m putin g, 9-10, 15 Ap p le Com p u ter, 11, 14 CP/ M system s, 11 IBM PC, 10-14 h it ratio (cach e m em o ry), 320 HLF (High -Level Fo rm attin g), h ard disk drives, 731-732, 769-770 HMA (High Mem o ry Area), 359, 378-379 h o ldup tim e, 415 h o rizo n tal frequen cies (m o n ito r buyin g criteria), 510 h o rizo n tal scan rates, CRTs (cath o de ray tubes), 500 h o st adapters con figu rin g, 762-764 op tical d rives, 854 SCSI, 653 au to term in atin g, 861 d iagn ostic software, 989-990 h o t pluggin g, USB (Un iversal Serial Bus), 603-604 h o t-sw appable h ard disk drives, 687

h o t-sw appable PC Cards, 935 Card Services software, 936 en ablers, 936-937 Socket Services software, 935 HP-GL/ 2 (Hew lett Packard Graph ics Lan guage) co m m an ds, 874 HPA (h igh perfo rm an ce addressin g), passive m atrix displays, 915 HS (Heat Spreader Package), OverDrive steppin gs tables, 123 HST pro prietary pro to co l, 665 HTTP (HyperTex t Tran sfer Pro to co l), 708 h ub-rin g en fo rcem en ts, 787 h ubs (cable m o dem s), 674 h ybrid CPUs (fifth an d six th gen eratio n ) AMD-K6, 153-154 ID m arkin gs, 155 sp ecification s, 153-154 sp eed s, 155 voltages, 155 Cyrix 6x86/ 6x86MX, 156-157 sp eed s, 157-158 Cyrix Med iaGX, 155-156 Nexgen Nx586, 152-153 h ydro gen tated am o rph o us silico n , see a-Si Hyper Page Mo de, see EDO RAM Hz (h ertz), 31 p itch , 562

I I/ O Buffer vo ltage (m o bile Pen tium s), 919-920 I/ O buses (ex pan sio n slo ts), 238-239 AGP p orts, 268-269 EISA (Exten d ed ISA) bu s, 246-249 ISA bu s, 239-242 8-bit, 240 16-bit, 241-243 32-bit, 244 local, 250-252 PCI bu s, 256-269 VL (VESA local) bu s, 252-256 MCA bu s (Micro Ch an n el Arch itectu re), 245-246

1473

I/ O co n n ecto rs ATA IDE, 615-616 ATX m oth erboard s, 173 in tern al, 174 I/ O devices, 583 FireW ire (IEEE 1394), 604-605 p arallel p orts, 583, 593 25-p in con n ectors, 593-594 bid irection al, 595 con figu rin g, 598 d evice con n ection s, 598-599 d iagn ostics, 600 EPP (En h an ced Parallel Ports), 595-596 IEEE 1284, 596-597 Parallel u tility, 597 recom m en d ation s, 597 u n id irection al, 594-595 serial p orts, 583-584 9-p in con n ectors, 584-586 25-p in con n ectors, 585-586 con figu rin g, 590-591 con n ector ad ap ters, 587 d iagn ostics, 591-593 h igh sp eed , 589-590 UART ch ip s, 587-589 USB (Un iversal Serial Bu s), 600-604 I/ O in terfaces Card Bu s, 933 Zoom ed Vid eo, 933 I/ O Man ager (Win do w s NT Ex ecutive), 1064 I/ O po rts ad d resses, 277-281, 763 bu s m ice settin gs, 484 con flicts, 551, 575, 854 error cod es (POST), 988-989 m oth erboard s, 960 in tegrated ad ap ters, 961 Su p er I/ O ch ip s, 960 W in d ows 9x Device Man ager, 997 I/ O system (DOS), 1034-1035 IBMBIO.COM (IBM DOS), 1035 boot d isks, creatin g, 1036 IBMDOS.COM (IBM DOS), 1036 IO.SYS (MS-DOS), 1035 boot d isks, creatin g, 1036 MSDOS.SYS (MS-DOS), 1036

1474

IBM Corporation

IBM Co rpo ratio n , 511 Baby-AT m oth erboard s, 20 BIOS, d u p licatin g, 17 d iagn ostics software, 989 d iscon tin u ed system (rep lacin g p arts), 1100 DOS (MS-DOS licen sin g), 17-18 h ard d isk p aram eters, 1357-1365 h istory of, 1099 keyboard s an d cables IBM Op tion s m od els, 479 p art n u m bers, 478 Mod el 5100, 10 Mod el 5110, 11 Mod el 5120, 11 PC DOS 6.3 (m ou se d river), 490 PC DOS 7.0 (m ou se d river), 490 Pen tiu m II, AGP (Accelerated Grap h ics Port), 532 Profession al Color Disp lay, 516 referen ce m aterials (keyboard d esign ), 480 system n am es, 1100 system n u m bers, 1100 Th in kPad , 479 Th in kPad 700, 492 TrackPoin t, 449, 491-495 IBM co m patibles, 16 d u p licatin g IBM h ard ware, 16 d u p licatin g IBM software, 17 MS-DOS licen sin g, 17-18, 24 IBM DOS (PC DOS 6.3), 1040 IBM En h an ced Co lo r Display, 516 IBM PC, 10, 1101 8088 CPUs, 84 83-key keyboard , 446 available op tion s, 1104 BIOS version s, 1104-1105 exp an sion slots, 1101 flop p y d isk d rives, 1101 h istory of, 11-13 com p atibility stan d ard s, 13-14 Digital Research , 12 Microsoft, 12 keyboard s, 1102 com p atibility, 453 key n u m bers an d scan cod es, 463-464

m od el n u m bers, 1103 m oth erboard s 8088 CPU, 1101 m em ory, 1101 p art n u m bers, 1104 p ower su p p ly, 1101 sp ecification s d isk storage, 1107 en viron m en tal, 1108 exp an sion slots, 1108 keyboard s, 1108 m em ory, 1107 p h ysical, 1108 stan d ard featu res, 1107 system arch itectu re, 1106 switch settin gs), 1108-1110, 1123-1124 system u n it, 1101 u p grad in g IBM PC AT, 1129 80286 CPU, 84 84-key keyboard , 447 BIOS, 1104 h ard d rive con troller h ead step rate, ch an gin g, 1140 h ard d rive tables, 1136-1140 version s, 1105, 1136 com p on en ets, 1131-1132 En h an ced 101-key keyboard , 448 con n ectors, 448 foreign lan gu age version s, 449 layou t, 449 rem ovable keycap s, 449 exp an sion slots, 1130 flop p y d isk d rives, 1130 h ard d isk d rives, 1130 p aram eters, 1406-1408 keyboard s, 1131 key n u m bers an d scan cod es, 464-465 typ em atic fu n ction s, ad ju stin g, 459-461 keyboard s;com p atibility, 453 m od els, 1129, 1133 068, 1132 099, 1132 239, 1133-1135 30M u p d ate kit, 1134 319, 1135 339, 1135 flop p y/ h ard d isk con troller, 1132

op tion n u m bers, 1145 p art n u m bers, 1144 system clock sp eed , 1132 m oth erboard 80286 CPUs, 1129 CPUs, 1134 p ower su p p lies, 1130 sp ecification s, 1140 d isk storage, 1142 en viron m en tal, 1144 exp an sion slots, 1144 keyboard s, 1144 m em ory, 1141 p h ysical, 1144 stan d ard featu res, 1142 system arch itectu re, 1140 IBM PC Co n vertible, 1110 d etach able LCD, 1111 exten d able bu s in terface, 1111 m od els, 1110 op tion s battery ch arger, 1114 CRT d isp lay ad ap ters, 1114 in tern al m od em s, 1114 m em ory card s, 1113 op tion al d isp lays, 1114 p rin ters, 1113 serial/ p arallel ad ap ter, 1114 sp ecification s, 1112 m oth erboard , 1113 stan d ard featu res, 1111-1112 IBM PC XT, 1115 83-key keyboard , 446 BIOS version s, 1119 com p on en ts, 1117 En h an ced 101-key keyboard , 448 con n ectors, 448 foreign lan gu age version s, 449 layou t, 449 exp an sion slots, 1116 flop p y d isk d rives, 1115 h ard d isk d rives, 1115 keyboard s com p atibility, 453 en h an ced accessories, 1125 key n u m bers an d scan cod es, 463-464 m od els, 1115-1119 p art n u m bers, 1124

IFSHLP.SYS

m oth erboard 8088 CPUs, 1115 switch settin gs, 1123-1124 op tion s (n u m bers), 1124 p ower su p p lies, 1116 sp ecification s, 1120 d isk storage, 1122 en viron m en tal, 1123 exp an sion slots, 1122 keyboard s, 1122 m em ory, 1121 p h ysical, 1123 stan d ard featu res, 1121 system arch itectu re, 1121 IBM PC XT Mo del 286, 1145 exp an sion slots, 1146 featu res, 1147 h ard d isk d rives, 1146 m em ory, 1146 m oth erboard (CPUs), 1145 sp ecification s, 1148 d isk storage, 1149 en viron m en tal, 1150 exp an sion slots, 1150 keyboard s, 1150-1152 m em ory, 1148 op tion al accessories, 1152 p h ysical, 1150 stan d ard featu res, 1147-1149 system arch itectu re, 1148 sp eed , 1146 IBM Po rtable PC, 1125 com p on en ts, 1126 m od els (p art n u m bers), 1129 m oth erboard , 1125 sp ecification s d isk storage, 1128 en viron m en tal, 1128 exp an sion slots, 1128 keyboard s, 1128 m em ory, 1127 p h ysical, 1128 stan d ard featu res, 1127 system arch itectu re, 1127 IBM PS/ 2 Ad van ced Diagn ostics form at p rogram , 1407 h ard d isk p aram eters, 1406-1408 Mod el 90 XP 486 XGA ad ap ters, 520 Mod el 95 XP 486 XGA ad ap ters, 520

m od els 25/ 30, MCGA (Mu ltiColor Grap h ics Array), 517 m oth erboard m ou se p ort, 483 serial an d m oth erboard p ort h ybrid (PS/ 2), 483 VGA (Vid eo Grap h ics Array), 517-518 vid eo ad ap ters (XGA Disp lay Ad ap ter/ A), 519 IBM PS/ 2 Display Adapter 8514/ A, 516 IBM-style 30-pin SIMMs, 327 IBMBIO.COM (IBM DOS), 1034-1036 boot d isks, creatin g, 1036 ICMP, 707 iCOMP 2.0 in dex ratin gs, 35 Pen tiu m CPUs, 35 Pen tiu m II CPUs, 35, 141 233 MHz MMX m od els, 144 266 MHz MMX m od els, 144 300 MHZ MMX m od els, 144 333MHz MMX m od els, 143 350 an d 400 MHz MMX m od els, 143 Pen tiu m -MMX CPUs, 35 Pen tiu m -Pro CPUs, 35 180 MHz m od el, 133 200 MHz m od el, 133 ICs (in tegrated circuits), 10 ID bytes IBM PC BIOS, 1105 IBM PC XT, 1119 ID m arkin gs (AMD-K6 CPUs), 155 ID strin gs (BIOS), 210-213 IDE (In tegrated Drive Electro n ics), 610-612 ATA, 614-615 cablin g, 616 com m an d s, 617-618 d u al-d rive con figu ration s, 615 I/ O con n ectors, 615-616 in telligen t, 620-621 n on -in telligen t, 619 sign als, 616-617 ATA-2, 621 ATAPI (ATA Packet In terface), 624-625 BIOS, 621-623

1475

d ata tran sfer sp eed s, 623-624 DMA m od es, 624 ATA-3, 621 ATAPI (ATA Packet In terface), 624-625 BIOS, 621-623 d ata tran sfer sp eed s, 623-624 DMA m od es, 624 ATA-4, 625 bu ses, 613-614 cablin g, 612-613 d evelop m en t, 612-613 h ard d isk p aram eters, 1401-1404 u ser-d efin able con figu ration s, 1401-1405 in terfaces (in stallin g op tical d rives), 854 LLF software, 768 MCA (Micro-Ch an n el Arch itectu re), 626 d rives, 613 PCI con n ection s, 613 SCSI com p arison s, 646 h ard ware, 646-651 p erform an ce, 651-653 setu p , 765 XT bu s, 626 XT d rives, 613 IDE/ ATAPI in terfaces (CDROM drive), 833 Iden tify Drive co m m an d (ATA IDE), 617-618 iden tifyin g h ard d isk d rives au tom atic d rive typ in g, 766 m an u al d rive typ in g, 766 m em ory ch ip s, 337 IDs, SCSI (Sm all Co m puter System In terface), 626 con figu rin g, 641-642 IDT (In tegrated Device Tech n o lo gy) Win ch ip, In tel-co m patible CPUs, 82, 126-127 IEEE 1284 d ata lin k layer p rotocols, 699 p arallel p ort, 596-597 IEEE 1394 (FireWire), 604-605 IEXTRACT.E XE (Win do w s 9x DOS), 1416 IFSHLP.SYS, 1059

1476

Illustrator

Illustrato r, 1180 im ages 3D abstraction s, 544 p rim itives, 544 ren d erin g, 543 textu res, 544 vertices, 544 bitm ap , 875 p rin tin g, 885 from Ph otoCDs, 845 ren d erin g, 544-545 geom etry, 544 rasterization , 544 vector, 875 see also grap h ics Im agin e i128(2) video adapter, 539 Im atio n LS-120 drive, 962 In deo co dec (VFW), 541 in dex h o le, 787 In dustry Stan dard Arch itecture, see ISA bus in dustry stan dard fo rm facto rs, 394 AT/ Desk style, 395-396 AT/ Tower style, 396-397 ATX style, 398-401 op tion al 6-p in con n ector, 405 Baby AT style, 397-398 LPX style, 397-398 NLX style, 401-402 PC/ XT style, 395 SFX style, 402 In frared Data co n n ecto rs, see IrDA co n n ecto rs in frared visible ligh t (electro m agn etic spectrum ), 1344 In itial Pro gram Lo ad (IPL) ROM, 372 in itiato rs (SCSI), 644 in kjet prin ters, 869-870 color, 888, 892 p reven tative m ain ten an ce, 902 p rin tin g, 887 lim itation s, 889 Piezo, 888 th erm al, 888 in put devices, 445 Accu p oin t (Tosh iba), 494 gam e con trollers, 496-498 PC-com p atible con n ectors, 498 Glidepoin t (Alps Electric), 495

keyboard s, 29, 445, 964 104-key (W in d ows), 449-451 83-key PC an d XT, 446 84-key AT, 447 clean in g, 1022 com p atibility, 453 con n ectors, 470-472 d esign referen ce m aterial, 479 Dvorak layou t, 472 En h an ced 101-key, 448-449 ergon om ic, 473 fu n ction keys, 453 in terface, 457-459 in tern ation al layou ts, 469-470 key n u m bers an d scan cod es, 462-469 keyswitch d esign , 454-457 Nu m Lock, 454 n u m eric keyp ad s, 447, 449, 452-454 p ortable, 451-452 p rogram m able, 473 QW ERTY layou t, 472 trou blesh ootin g, 474-479 typ em atic fu n ction s, 459-461 m ou se, 29, 480-481 bu s, 484 bu tton s, 481 cables, 481 calibratin g, 484-486 com p on en ts, 481 con n ectors, 472 d evice d rivers, 481 Microsoft In telliMou se, 490-491 m oth erboard p orts (PS/ 2), 483 op to-m ech an ical m ech an ism , 481 serial in terfaces, 482-483 trou blesh ootin g, 487-490 USB (Un iversal Serial Bu s), 484 p oin tin g d evices (TrackPoin t), 479 trackballs, 480 TrackPoin t, 491-495 in put ran ge, 415 In put/ Output devices, see I/ O devices

in stalled m em o ry (co m pared to to tal usable m em o ry), 382-385 in stallin g CD-ROM d rives, 854, 862-863 bootu p testin g, 865-866 DOS CD-ROM d evice d river, 864 DOS SCSI ad ap ter d river, 863 in terface ad ap ters, 854 MSCDEX.EXE, 864-865 W in d ows 3.x, 866 W in d ows 9x, 866 W in d ows NT 4.0, 866 CPUs (p rep arin g m oth erboard s), 972 d rivers (bu ild in g system s), 968 DVD-ROM d rives, 854, 862-863 bootu p testin g, 865-866 DOS CD-ROM d evice d river, 864 DOS SCSI ad ap ter d river, 863 in terface ad ap ters, 854 MSCDEX.EXE, 864-865 W in d ows 9x, 866 W in d ows NT 4.0, 866 exp an sion card s (assem blin g system s), 976 extern al d rives (op tical), 856-858 flop p y d isk d rives, 793 h ard d isk d rives, 761-770 d rive con figu ration s, 762 h ost ad ap ter con figu ration s, 762-764 p h ysical in stallation , 764-765 in tern al d rives (op tical), 858 ISDN con n ection s, 672 S/ T (Su bscriber/ Term in ation ) In terface, 672 term in al ad ap ters, 672 U-In terface, 672 m em ory, 354-359 SIMMs an d DIMMs, 973 m oth erboard s cables, con n ectin g, 975-976 exp an sion card , in stallin g, 976

interfaces

m em ory m od u les, in stallin g, 973 m ou n tin g in th e case, 973-974 p ower su p p lies, con n ectin g, 974-975 p rep arin g, 972-973 n etwork cablin g, 697-698 op eratin g system s (bu ild in g system s), 968 OverDrive p rocessors, 162 Pen tiu m II CPUs, 145 sou n d card s, 571 CD Au d io In con n ector, 572 con n ectin g sp eakers, 572 in sertin g in to slot, 572 p atch in g in to stereo system s, 573-574 settin g ju m p ers or DIP switch es, 572 tap e d rives, 819-820 W in d ows d rivers for p rin ter su p p ort, 898-899 in structio n ex ecutio n pipelin es (superscalar ex ecutio n ), 47 in structio n ex ecutio n tim es (CPU speeds), 34 486 CPUs, 92 efficien cy, 34 in structio n pro cessin g (Pen tium CPUs), 107 in tegral cach e, see L1 cach e In tegrated Device Tech n o lo gy, see IDT in tegrated L2 cach e (Pen tium Pro CPUs), 132, 134 in tegrated m ultim edia (Cyrix MediaGX CPU), 155-156 In tegrated Periph erals Co n tro ller, see IPC In tegrated Services Digital Netw o rk, see ISDN In tel 8088 CPUs IBM PC, 1101 IBM PC XT, 1115 Profession al Color Disp lay ad ap ters, 516 ch ip sets, 185-186 430FX PCIset, 956 430HX PCIset, 955 430TX PCIset, 955 430VX PCIset, 955 440BX AGPset, 955

440FX PCIset, 955 440LX, 440EX an d 440BX, 532 440LX AGPset, 955 440LX ch ip set (Pen tiu m Pro), 134 450KX/ GX ch ip set (Pen tiu m Pro), 134 486 p rocessors, 187 82350, 187 EISA bu s, 185 m od el n u m bers, 186 North Brid ges, 186 Pen tiu m II p rocessors, 200-207 Pen tiu m Pro p rocessors, 199-207 Pen tiu m p rocessors, 187-194 Sou th Brid ges, 186 CPUs 4004, 10 8008, 10 80186, 84 80188, 84 80286, 24, 84-86 80386, 87-92 80486, 22-24, 92-103 8080, 10 8086, 83-84 8088, 23-24, 83-84 cod en am es, 79 com p atibles, 80-82 Pen tiu m , 22-24, 105-120, 124-125 Pen tiu m II, 22-24, 127-130, 140-152 Pen tiu m MMX, 22-24 Pen tiu m OverDrive, 122-125 Pen tiu m Pro, 22-24, 127-139 Pen tiu m -MMX, 113-114, 121-125 sp ecification s, 31-32 h ard ware in d u stry con trol, 18 AGP (Accelerated Grap h ics Port), 20 ch ip sets, 19-20 m em ory su p p ort, 20 m oth erboard s, 19-20 PCI bu s (Perip h eral Com p on en t In tercon n ect), 20 NLX m oth erboard form factor, 20

1477

Sm art Vid eo board s (In d eo cod ec), 541 VRT (Voltage Red u ction Tech n ology), m obile CPUs, 918-919 In tel Trito n ch ipsets (parity suppo rt), 959 In tel-co m patible CPUs AMD 486 (5x86) Am 5x86 (TM) -P75, 103-104 Am 5x86 (TM)-P75, 103 AMD K5, 125 clock m u ltip liers, 126 clock sp eed s, 126 voltages, 126 AMD-K6, 153-154 Cyrix 6x86/ 6x86MX, 156-157 sp eed s, 157-158 Cyrix Med iaGX, 155-156 Cyrix/ TI 486, 104 IDT Cen tau r C6 W in ch ip , 126 sp ecification s, 127 Nexgen Nx586, 152-153 in telligen t ATA IDE, 620 in telligen t w ith zo n e reco rdin g ATA IDE, 620-621 In telliMo use (Micro so ft), 490-491 in ten sity o f so un d, see am plitude INTER-RECORD GAP (h ard disk secto rs), 727 in terfaces CD-ROM d rive, 832-835 ATA/ IDE, 830 CD-R an d CD-RW , 834 EIDE, 834 IDE/ ATAPI, 833 p arallel p ort, 834-835 SCSI, 830, 833 con n ectors (h ard d isk d rives), 753 d isk d rive, 1049 con troller p ort com m an d s, 1052-1053 In terru p t 13h , 1050-1052 In terru p t 21h , 1050 In terru p t 25h , 1050 In terru p t 26h , 1050 gam e con trollers, 496-498 PC-com p atible con n ectors, 498 GUIs, 480

1478

interfaces

h ard d isk d rive EIDE, 962-963 SCSI, 761, 962-963 IDE, see IDE ISDN (In tegrated Services Digital Network) S/ T (Su bscriber/ Term in ation ) In terface, 672 U-In terface, 672 keyboard p rocessor, 457-459 bou n cin g/ d ebou n cin g keystrokes, 458 keyboard s key n u m bers an d scan cod es, 462-469 PC/ XT an d AT d ifferen ces, 25 m ou se bu s, 484 m oth erboard p orts (PS/ 2), 483 serial, 482-483 USB (Un iversal Serial Bu s), 484 n etwork (d iagn ostic software), 990-991 op tical d rive, 854 recom m en d ation s, 295-296 SCSI, see SCSI in terlaced m o n ito rs, 506-507 in terleavin g, 315, 758-767 CD-ROM-XA (Exten d ed Arch itectu re), 841-843 INTERLNK.EXE (Win do w s 95 CD-ROM), 1417 DOS d irect cable con n ection s, 677 in tern al (Level 1) cach e, 41 4-way set associative, 42 486DX CPUs, 96 Bu s Sn oop in g, 42 Pen tiu m CPUs, 107 Level 2, 108 m od es, 108 Pen tiu m -MMX im p rovem en ts, 48 write-back cach e (Pen tiu m fam ily), 42 write-th rou gh cach e (486 fam ily), 42 in tern al CD-ROM drives, 838 in tern al data buses vs. ex tern al data buses, 39 in tern al lo o pback tests (serial po rts), 592

in tern al m o dem s, see m o dem s in tern al pin -type co n n ecto rs (so un d cards), 567 in tern al po w er supply co n n ecto rs (ATX m o th erbo ards), 173 in tern al registers CPUs, 39-40 32-bit vs. 16-bit, 39 m u ltip le, 40 su p erscalar exectu ion (CPUs), 47 Pen tiu m II CPUs, 143 Pen tiu m Pro CPUs, 132 in tern al tape drives, in stallin g, 819-820 in tern al un sh ielded h eader co n n ecto rs (sin gle-en ded SCSI), 635 in tern al Win do w s 9x DOS co m m an ds, 1414-1415 in tern atio n al keybo ard layo uts, 469 Keyboard Con trol Pan el, 469-470 In tern atio n al Teleco m m un icatio n s Un io n (ITU), 658 In tern et Adviso r, 1194 In tern etw o rk Packet Ex ch an ge (IPX), 708 in terpo latin g m issin g data (CD-ROM drives), 828 in terpo latio n (prin ter reso lutio n ), 872 in terpo ser cards (IDE), 613 In terrupt 13h disk drive in terface ro utin es, 1050 BIOS d isk fu n ction s, 1051-1052 In terrupt 21h disk drive in terface ro utin es, 1050 In terrupt 25h disk drive in terface ro utin es, 1050 In terrupt 26h disk drive in terface ro utin es, 1050 in terrupt requests, see IRQs in terrupts BIOS, 1032-1033 h ard ware (PC/ XT an d AT d ifferen ces), 25 IRQs (In terru p t req u est ch an n els), 271 8-bit ISA bu ses, 272 16-bit ISA bu ses, 272-274 trou blesh ootin g, 274-275

PCI bu s, 267-268 USB (Un iversal Serial Bu s), 604 in terspersed, see in terleavin g INTERSVR.EXE DOS d irect cable con n ection s, 677 W in d ows 95 CD-ROM, 1417 in valid files/ directo ries (FAT erro rs), 1087 IO.SYS (MS-DOS), 1034-1035 boot d isks, creatin g, 1036 IPC (In tegrated Periph erals Co n tro ller), 956 IPL (In itial Pro gram Lo ad) ROM, 372 IPX (In tern etw o rk Packet Ex ch an ge), 708 IrDA co n n ecto rs (In frared Data), 230 IRQs (In terrupt requests), 271-272, 763 8-bit ISA bu ses, 272 16-bit ISA bu ses, 272-274 bu ild in g system s, 968 bu s m ice settin gs, 484 con flicts op tical d rives, 854 m ice, 487-488 sou n d card s, 574 serial p orts, con figu rin g, 590-591 sou n d card s, con figu rin g, 572 trou blesh ootin g, 274-275 W in d ows 9x Device Man ager, 997 IRQuest Plus, 1232 ISA bus (In dustry Stan dard Arch itecture), 23, 233, 239-240, 531 8-bit, 240 DMA ch an n els, 275 IRQs, 272 16-bit, 241-243 DMA ch an n els, 275-276 IRQs, 272-274 32-bit, 244 bu s m ice, 484 ch ip set su p p ort, 957 IDE (In tegrated Drive Electron ics), 611 IRQs, 271 MCA slot ad ap ters, 989 p arallel p orts, con figu rin g, 598

keyboards

ISDN (In tegrated Services Digital Netw o rk), 671 bearer ch an n els, 671 BONDING p rotocol, 672 BRI (Basic Rate In terface), 671 con n ection s, in stallin g, 672 d elta ch an n els, 671 h ard ware term in al ad ap ters, 672 U-In terface, 672 Mu ltilin k PPP p rotocol, 672 NFAS (Non -Facility Associated Sign alin g), 672 PRI (Prim ary Rate In terface), 671 S/ T (Su bscriber/ Term in ation ) In terface, 672 ISO (In tern atio n al Organ izatio n fo r Stan dardizatio n ), 839 ISO 9660 CD-ROM data stan dard, 839 iso pro pyl alco h o l (stan dard clean ers), 1016 ISPs (In tern et Service Pro viders), 56K m o dem suppo rt, 669 ITU (In tern atio n al Teleco m m un icatio n s Un io n ), 658 Iw are Co n n ect, 1222

J Jaz drives, 801-802, 846, 962, 1205 d isk stru ctu res, 1066 FAT32 p artition s, 1082 m axim u m root d irectory, 1074 system backu p s, 1012-1013 JEDEC (Jo in t Electro n ic Devices En gin eerin g Co un cil), 331 jitter (sign als), 600-601 JOIN co m m an d (retired fo r Win do w s 9x ), 1418 Jo in t Electro n ic Devices En gin eerin g Co un cil (JEDEC), 331 Jo in t Ph o to graph ic Ex perts Gro up, see JPEG

jo ysticks, 496-498, 567 gam e p orts, 551 PC-com p atible con n ectors, 498 trou blesh ootin g, 578-579 JPEG (Jo in t Ph o to graph ic Ex perts Gro up), 541 jum perin g d rives as m asters, 855 as slaves, 855 m oth erboard s cach e m od es, 104 voltage settin gs, 104 Pen tiu m -MMX CPUs for 60/ 66MHz op eration , 114 jum pers CPUs, settin g, 954 Flash ROM BIOS, 217 in correct settin gs (in stallin g m em ory), 358 SCSI IDs, con figu rin g, 641-642 settin gs (in stallin g sou n d card s), 73, 572

K K5 CPUs (AMD), 125 clock m u ltip liers, 126 clock sp eed s, 126 voltages, 126 K5 In tel-co m patible CPUs (AMD), 80 K56flex 56K m o dem stan dard, 669-670 K6 CPUs (AMD), 80, 153-154 ID m arkin gs, 155 sp ecification s, 153-154 sp eed s, 155 voltages, 155 Katm ai, see Pen tium II CPUs Ken sin gto n Tech n o lo gy Gro up, 1206 kern el (Win do w s NT), 1063-1064 key co m bin atio n s (Win do w s 95), 450-451 key m atrix key n u m bers an d scan cod es, 462-469 keyboard in terface (bou n cin g/ d ebou n cin g keystrokes), 458

1479

key n um bers, 462 83-key PC/ XT keyboard s, 463-464 84-key AT keyboard s, 464-465 101-key keyboard s, 466-469 104-key W in d ows keyboard s (n ew keys), 469 KEYB.COM (Win do w s 9x DOS), 1416 Keybo ard Co n tro l Pan el (Win do w s) in tern ation al layou ts, 469-470 typ em atic fu n ction s, ad ju stin g, 459-460 keybo ards, 29, 445, 964 83-key PC an d XT, 446 84-key AT, 447 104-key (W in d ows), 449 Ap p lication key, 450 ergon om ics, 451 layou t, 450 W IN keys, 450 W in d ows 95 key com bin ation s, 450-451 clean in g, 1022 com p atibility (au to switch in g), 453 con n ectors, 470 5-p in DIN, 471 6-p in m in i-DIN, 471 Baby-AT m oth erboard s, 169, 951 fu ll-size AT m oth erboard , 170 m in i-DIN p lu gs, 471, 478-479 SDL (Sh ield ed Data Lin k), 471 sign als, 471-472 con trollers BIOS, u p grad in g, 216-217 In tel 8048, 458, 462 In tel 8049, 458 Motorola 6805, 458 Su p er I/ O ch ip s, 208 d esign (referen ce m aterial), 479 En h an ced 101-key, 448 con n ectors, 448 foreign lan gu age version s, 449 layou t, 449 rem ovable keycap s, 449 ergon om ic, 473

1480

keyboards

fu n ction keys, 453 IBM p art n u m bers, 478 IBM Op tion s p art n u m bers, 479 IBM PC, 1102-1108 IBM PC AT, 1131, 1144 IBM PC XT, 1122 en h an ced accessories, 1125 IBM PC XT Mod el 286 en h an ced accessories, 1152 m in i-DIN p lu gs, 471, 478-479 IBM Portable PC sp ecification s, 1128 in terfaces, 457 bou n cin g/ d ebou n cin g keystrokes, 458 key n u m bers an d scan cod es, 462-469 PC/ XT an d AT d ifferen ces, 25 p rocessor, 458-459 in tern ation al layou ts, 469-470 keyswitch d esign , 454-456 cap acitive, 457 m ech an ical, 454-456 layou ts Dvorak, 472 QW ERTY, 472 Nu m Lock, 454 n u m eric keyp ad s, 447, 449, 452-454 p ortable, 451-452 p ortable com p u ters, 937-938 n u m eric keyp ad s, 938 p rogram m able, 473 server req u irem en ts, 688 trou blesh ootin g, 474 cablin g, 474 clean in g, 477 con n ector sp ecification s, 474-475 d isassem bly p roced u res, 475-476 keyswitch es, 474 m oth erboard con n ectors, 474-475 POST errors, 474-475 rep lacin g, 478-479 scan cod e errors, 474 typ em atic fu n ction s, 459 ad ju stin g in DOS, 460-461 ad ju stin g in W in d ows, 459-460 ven d ors, 1240

keycaps rem ovable (En h an ced 101-key keyboard s), 449 rem ovin g (clean in g keyboard s), 477 keyco des (ex ten ded ASCII keyco des fo r ANSI.SYS), 1333-1334 keyfram es (ren derin g 3D im ages), 543 Keylo ck co n n ecto rs, 230 keystro kes, bo un cin g/ debo un cin g, 458 keysw itch es clean in g (Stabilan t 22a), 456 d efective, 478 keyboard s, 454-456 cap acitive, 457 m ech an ical, 454-456 stu ck, 469, 474 kits (h an d to o ls), 1000 ch ip extractors, 1001 ESD (electrostatic d isch arage) p rotection kit, 1003 files, 1003 flash ligh ts, 1003 h em ostats, 1003 n u t d rivers, 1001 p art grabber, 1002 p liers, 1003 Torx d river, 1003 tweezers, 1002 vise, 1003 wire cu tter/ strip p er, 1003 Klam ath , see Pen tium II CPUs, slo t 1 kn o w n -fun ctio n al circuits (lo gic pulsers), 1009 KRNL286.EXE (Win do w s 3.x co re files), 1056 KRNL386.EXE W in d ows 3.11 u p d ates, 1054 W in d ows 3.x core files, 1056

L L1 cach e, 320 4-way set associative, 42 486 CPUs, 92, 320 Bu s Sn oop in g, 42 cach e m iss, 320 clock m u ltip lied CPUs, 41 L2 com p arison s, 321 Pen tiu m Pro CPUs, 130-132 Pen tiu m -MMX im p rovem en ts, 48

SRAM (386 system s), 320 write-back cach e (Pen tiu m fam ily), 42 write-th rou gh cach e (486 fam ily), 42 L2 cach e, 320 4-way set associative, 42 DIB arch itectu re, 49 L1 com p arison s, 321 m obile system s, 919, 927-928 Pen tiu m CPUs, 108 Pen tiu m Pro CPUs, 132-134 MPS 1.1 (Mu lti-Processor Sp ecification ), 134 secon d ary cach e, 958 LABEL.E XE (Win do w s 9x DOS), 1416 lan din g zo n e, see LZ lan ds CD-ROMs, 850-852 CD-RW d iscs (CD-Rewritable), reflectan ce, 850 read in g CD-ROMs, 825 lan guages, o bject-o rien ted, 875 LANs (lo cal area n etw o rks), 678, 684 100Mbp s Eth ern et, 704 100BaseT, 704 100VG, 705 ATM (Asyn ch ron ou s Tran sfer Mod e), 705 baseban d n etworks, 678 cablin g, 692 coaxial, 694 d istan ce lim itation s, 699 fiber-op tic, 695 in stallation s, 697-698 n etwork top ologies, 695-697 selectin g, 698-699 twisted p air, 692-693 circu it switch in g, 681 clien t software, 680 clien t/ server n etworks, 678 d ata en cap su lation , 684 d ata lin k layer p rotocols, 699 ARCn et, 700 Eth ern et, 700-701 Token Rin g, 701 Token Rin g ad ap ters, 702 FDDI (fiber d istribu ted d ata in terface), 703

Li-ion (lithium-ion) batteries

n etwork in terface ad ap ters, 688-689 bu fferin g, 691 con n ectors, 690 costs, 689 CRC (cyclic red u n d an cy ch eck), 692 d ata tran sfer, 691 d ata tran sfer sp eed s, 690 en cod in g/ d ecod in g, 692 Eth ern et, 689 fram e form ation , 691 fu n ction s, 691 m ed ia access, 691 NICs, 689 p arallel/ serial con version , 692 sen d in g/ receivin g im p u lses, 692 Token Rin g, 689 OSI Referen ce Mod el, 681-683 Ap p lication layer, 683 Data Lin k layer, 683 Network layer, 683 Ph ysical layer, 682 Presen tation layer, 683 Session layer, 683 Tran sp ort layer, 683 p acket switch in g, 681 p eer-to-p eer n etworks, 679-680 p rotocols IPX, 708 NetBEUI, 708 TCP/ IP, 706-708 servers, 686 backu p s, 687 m em ory req u irem en ts, 686 p ower su p p lies, 687-688 p rocessors, 686 storage req u irem en ts, 687 u ser in terface com p on en ts, 688 stacks, 681 workstation s, 686 LapLin k, 677, 1231 LAPM (Lin k Access Pro cedure fo r Mo dem s), 664 lapto ps, 910 A+ exam objectives, 1174 cost, 910 CPUs (386SL), 89 d ockin g station s, 910

IBM PC Con vertible, 1110 d etach able LCD, 1111 exten d able bu s in terface, 1111 m od els, 1110 op tion s, 1114 sp ecification s, 1112-1113 stan d ard featu res, 1111-1112 LCDs, 501 active-m atrix, 502-503 backligh tin g, 503 color screen s, 503 ed geligh tin g, 503 m on och rom e, 502 m u ltip le-freq u en cy, 502 p assive-m atrix, 502-503 p olarizin g filters, 501-502 screen sizes, 511-512 su p ertwist, 503 trip le-su p ertwist, 503 Pen tiu m II CPUs (Pen tiu m II Mobile Mod u le), 151 p ortable keyboard s, 451-452 weigh t, 910 see also m obile com p u tin g laser dio des (CD-ROM drives), 827 laser prin ters, 869-870 color, 892 p reven tative m ain ten an ce, 902 p rin tin g p rocess, 882 com m u n ication s, 883 form attin g, 884 p rocessin g, 883-884 rasterizin g, 884-885 scan n in g, 885-886 ton er ap p lication , 886-887 ton er fu sin g, 887 tran sferin g d ata to (p arallel p orts), 598-599 Last Written Cluster po in ter (disk space allo catio n ), 1048-1049 laten cy, 313-315 average access tim es, 756 SDRAM, 316 Token Rin g ad ap ters, 702 Lava Co m puter Mfg, 589 layo uts, keybo ard Dvorak, 472 QW ERTY, 472 LBA (Lo gical Blo ck Addressin g), 622-623, 979

1481

LCDs (Liquid Crystal Displays), 913 active m atrix, 502, 915 color screen s, 503 costs, 503 d ou ble-scan LCDs, 502 screen size, 916 TFT (th in film tran sistor) array, 915-916 backligh tin g, 503 color, 503 ed geligh tin g, 503 IBM PC Con vertible, 1111 m on och rom e, 502 overh ead d isp lay p an els, 943 p assive m atrix, 502, 914 cost, 915 CSTN (color su p er-twist n em atic), 915 d ou ble-scan LCDs, 502-503 DSTN (dou ble-layer su pertwist n em atic), 915 failed tran sistors, 914 HPA (h igh p erform an ce ad d ressin g), 915 size, 915 p olarizin g filters, 501-502 p rojectors, 943 resolu tion , 501, 917 color d ep th , 917 virtu al screen arran gem en ts, 917 resolu tion s, 914 screen sizes, 511-512 su p ertwist, 503 trip le-su p ertwist, 503 ven d ors, 1241 leased lin es, 673 T-1 con n ection s, 673 T-3 con n ection s, 673 LED co n n ecto rs, 230 LEDs (Ligh t Em ittin g Dio des), 446 left-h an ded m o use users, 485 len gth un its (m etric co n versio n s), 1341 Level 1 cach e, see L1 cach e Level 2 cach e, see L2 cach e LFNBK.EXE (Win do w s 9x ), lo n g file n am es, 1081 LH co m m an d load in g m ou se d rivers, 490 W in d ows 9x DOS, 1415 Li-io n (lith ium -io n ) batteries (po rtable co m puters), 940

1482

licensing

licen sin g (MD-DOS), 17-18 LIF (Lo w In sertio n Fo rce) so ckets, 67, 1001 Ligh t Em ittin g Dio des, see LEDs LIM (Lo tus In tel Micro so ft), 89 lin es con d ition ers (p ower su p p lies), 438 lin e in con n ectors (sou n d card s), 566 lin e n oise (56K m od em lim itation s), 669 lin e ou t con n ectors (sou n d card s), 566 regu lation , 416 testers (p ortable m od em con n ection s), 945 lin ear addresses (Upper Mem o ry Area), 362-364 lin ear vo ice co il actuato rs, 742 Lin k Access Pro cedure fo r Mo dem s, see LAPM Liquid Crystal Displays, see LCDs LIST pro gram , 1186 Lith ium -Io n Po lym er batteries (po rtable co m puters), 940 LLC (Lo gical Lin k Co n tro l) layer (OSI Data Lin k layer), 683 LLF (Lo w -Level Fo rm attin g), h ard disk drives, 728-731, 767-769 IDE software, 768 n on d estru ctive form atters, 768-769 SCSI software, 767 lo ad lim its (po w er supplies), 410-412 lo ad regulatio n , 416 lo ad resisto rs (testin g po w er supplies), 430 lo aders (Bo o tstrap), 209 LOADFIX.EXE (Win do w s 95 CD-ROM), 1417 LOADHIGH co m m an d (Win do w s 9x DOS), 490, 1415 lo adin g AUTOEXEC.BAT, 1047 CONFIG.SYS, 1047 volu m e boot sectors, 1071 W in d ows 3.x, 1055 386 en h an ced m od e, 1056 p rotected m od e, 1055

stan d ard m od e, 1056 W IN.COM, 1055 XMS m em ory, 1055 lo adin g m ech an ism s (CD-ROM drives), 835-836 cad d ies, 835-836 trays, 836-837 lo cal area n etw o rks, see LANs lo cal buses, 250-252 accelerators (82433NX ch ip s), 190 PCI bu s, 256-258, 261, 267-269 AGP p orts, 269 bu s m asters, 268 in terru p t, 267-268 p in ou ts, 259-267 Plu g an d Play, 267 slaves, 268 VL (VESA local) bu s, 252-256 486 CPU depen den ce, 253 card lim itation s, 253 electrical lim itation s, 253 p in ou ts, 255 sp eed lim itation s, 253 Lo cal Pro cedure Call facility (Win do w s NT Ex ecutive), 1064 lo catin g h ardw are co n flicts, 576 LOCK co m m an d (Win do w s 9x DOS), 1415 lo ckups (tro ublesh o o tin g so un d cards), 578 lo g file reco rds (NTFS MFT), 1096 lo gic bo ards (h ard disk drives), 752, 775 lo gic pro bes (digital circuits), 1009 lo gic pulsers (kn o w n fun ctio n al circuits), 1009 Lo gical Blo ck Addressin g, 622-623, 979 lo gical fo rm attin g, see LLF (lo w level fo rm attin g) Lo gical Lin k Co n tro l, 683 lo gical m appin g (m em o ry), 302 lo gical m em o ry, 359-360 ad ap ter board s, 385 d eterm in in g con figu ration of, 385-386 op tim izin g, 386-387 p reven tin g con flicts, 386 con flicts, p reven tin g,

380-381 con ven tion al, 360 exp an d ed m em ory, 379-380 exten d ed m em ory, 376-377 HMA (High Mem ory Area), 378-379 XMS (exten d ed m em ory sp ecification ), 377 UMA (Up p er Mem ory Area), 360-362 ad ap ter ROM, 369-374 lin ear ad d resses, 362-364 m oth erboard BIOS, 375-376 segm en t ad d resses, 362-364 vid eo RAM, 364-369 u p p er m em ory m an agem en t p rogram s, 387-388 EMM386.EXE, 388 HIMEM.SYS, 388 MEMMAKER, 388-390 lo gical partitio n s, 1067 lo gical rin g to po lo gies, 697 lo gical vo lum es, see partitio n s lo n g file n am es NTFS file system , 1095 VFAT, 1079-1080 8.3 alias n am es, 1081 assign in g, 1080 backward com p atibility, 1081 LFNBK.EXE (W in d ows 9x), 1081 storin g, 1080-1081 lo o pback co n n ecto rs, 1007 lo o pback tests (serial po rts), 592-593 lo st clusters, 1086 FAT errors, 1086-1087 Lo tus 1-2-3, 1208 Lo tus In tel Micro so ft, 89 Lo tus No tes Adviso r, 1194 lo w DMA (so un d card co n flicts), 576 Lo w In sertio n Fo rce, see LIF lo w po w er co m po n en ts (po rtable co m putin g design ), 911 Lo w Pro file cases, 949 avoid in g, 949 LPX m oth erboard s, 949, 952 NLX m oth erboard s (Low Profile ATX), 949, 952 lo w tem perature po lysilico n , see p-Si Lo w -Level Fo rm attin g, see LLF

maintenance

LPX m o th erbo ards, 170-173, 397-398 ATX com p arison s, 173-174 Low Profile system s, 949, 952 see also ATX m oth erboard s;p rop rietary m oth erboard s LS-120 drives (m ax im um ro o t directo ry), 1074 lubrican ts, co n tact, 1016 Stabilan t 22, 1016-1017 Stabilan t 22a, 1017 LZ (lan din g zo n e), 1353

M M1 (6x 86) In tel-co m patible CPUs (Cyrix ), 81 M2 In tel-co m patible CPUs (Cyrix ), 81 M1533/ M1543 So uth Bridge, 205-206 M1621 No rth Bridge, 205-206 MAC (Media Access Co n tro l) layer (OSI Data Lin k layer), 683 m ach in e lan guage, 1032 assem blers (ed itors), 1032 cod e, p ortin g, 1032 ROM BIOS, 1032-1033 m ach in es (ven do rs), 1244-1245 Macin to sh co m patibles, 18 m agazin es, 1236-1237 fin d in g h elp , 1163-1164 Magellan , 1208 Magitro n ic PC system s, 1207 m agn etic fields (flux ), 710 m agn etic m edia drives, cartridge drives, 799-802 Jaz d rives, 801-802 Sp arQ d rives, see Sp arQ d rives Syq u est d rives, 801 tap e d rives, see tap e d rives Zip d rives, see Zip d rives m agn etic m o n ito r em issio n s, 508 m agn etic sh ieldin g (co m puter speakers), 579 m agn etic sto rage cap acities, 718-719 d isk/ tap e m aterial, 710-719

en cod in g m eth od s ARLL (Ad van ced Ru n Len gth Lim ited ), 715 com p arison s, 716-717 MFM (Mod ified Freq u en cy Mod u lation ), 711-719 RLL (Ru n Len gth Lim ited ), 711-719 en cod in g sch em es, 712-716 FM (Freq u en cy Mod u lation ), 714 flop p y d isk d rives, 28 flu x, 710-719 h ard d isk d rives, 28, 719-761 ad van cem en ts, 719-720 air filters, 749-750 areal d en sity, 720-722 average access tim e, 756 average seek tim e, 756-759 cap acities, 759-761 con figu ration item s, 753-754 costs, 759 facep late/ bezel, 753-754 form attin g, 728-734 grou n d in g tabs, 753 h ard d isk tem p eratu re acclim ation , 750-751 h ead actu ator m ech an ism s, 740-749 h ead slid ers, 739-740 h ead / m ed iu m in teraction an alogy, 722-724 in stallin g, 761-770 in terface con n ectors, 753 logic board s, 752 oxid e record in g m ed ia, 734 p erform an ce, 755-759 p latters, 720, 732-733 p ower con n ectors, 753 raw in terface p erform an ce, 757 read / write h ead s, 735-739 reliability, 755 rem ovable, 719 SCSI in terfaces, 761 sectors, 724-728 sh ock m ou n tin g, 759 sp in sp eed s, 722 sp in d le m otors, 751-752 th in -film , 734-735

1483

track d en sities, 722 tran sfer rates, 756 m agn etic field s, 710-719 p rin cip le of, 709-719 PRML (Partial-Resp on se, Maxim u m -Likelih ood ), 718 read p rocesses, 712-719 read / write h ead s, 710-719 tap e d rives arch ivin g, see arch ivin g tap e d rives ven d ors, 1245 write p rocesses, 711-719 Magn eto -Resistive read/ w rite h eads (h ard disk drives), 739-741 m ain bo ards, see m o th erbo ards m ain m em o ry, see m em o ry, RAM m ain ten an ce CD-ROMs d rive sealin g, 837 self-clean in g len ses, 837 d iscon tin u ed system s (rep lacin g com p on en ts), 1100 flop p y d isk d rives (Norton DiskTool), 1094 h ard d isk d rives NDIAGS u tility, 1095 Norton Calibrate, 1094 Norton Disk Doctor, 1094 Norton Disk Ed itor, 1094 p reven tive, 1011 active, 1011-1024 clean in g system s, 1013-1022 h ard d isk d rives, 1022-1024 h arsh en viron m en t system s, 1030 op eratin g en viron m en ts, 1024 p assive, 1011, 1024-1030 p ower cyclin g, 1025-1027 p ower lin e n oise, 1028-1029 reseatin g socketed ch ip s, 1019-1020 RFI (rad io-freq u en cy in terferen ce), 1029-1030 static electricity, 1027-1028

1484

maintenance

system backu p s, 1012-1013 tem p eratu re con trol, 1024-1025 p rin ters, 902 d ot m atrix, 902-903 in kjet, 902 laser, 902 p ap er selection , 903 tools, 999-1000 En glish an d m etric th read system s, 1005 h an d tools, 1000-1004 h ard ware typ es, 1004 sold erin g an d d esold erin g, 1005-1007 test eq u ip m en t, 1007-1011 W eb site resou rces, 1247-1249 see also d iagn ostic software; p roblem s; trou blesh ootin g Main ten an ce Wizard (Win do w s 98), 1024 m an agem en t, po w er, 423 Ad van ced Power Man agem en t, 423-425 En ergy Star System s, 423 m an ual drive typin g (h ard disk drives), 766 m an uals, 1154-1155 ch ip an d ch ip set level, 1156, 1160-1162 com p on en t level, 1156 system level, 1156-1159 m an u factu rersp ecific, 1163 see also d ocu m en tation m an ufacturer-specific system do cum en tatio n , 1163 m an ufacturer-supplied diagn o stic so ftw are, 984 m an ufacturin g CPUs bou les, 50 ch ip s, 52-53 d ies, 51 d op in g, 51 m asks, 51 overclockin g, 53 p h otolith ograp h y, 51 p h otoresists, 51 silicon , 50 tran sistors, see tran sistors wafers, 51-52 yield s, 52

m arkin g sch em es (CPU clo ck speeds), 37 AMD-K6 CPUs, 155 u n d er h eat sin ks, 37 Mask ROM, 306 m askable in terrupts, 272 m asks 486 CPUs, 98 m an u facu rin g CPUs, 51 m aster bo o t co de, 1067 Master Bo o t Reco rd, see MBR Master Bo o t Secto r, see MBS m aster drives, o ptical, co n figurin g as, 855 Master File Table, see MFT m aster partitio n bo o t secto r, 1067-1070 exten d ed DOS p artition s, 1067-1068 m aster boot cod e, 1067 m aster p artition table, 1067 MBR (Master Boot Record ), 1068-1070 prim ary DOS partition s, 1067 viru ses, 1068 m aster partitio n table (m aster partitio n bo o t secto r), 1067 m asters d u al d rives (ATA IDE), 615 d u p licates (stam p in g CD-ROMs), 825 m ath co pro cesso rs 486 CPUs, 93 486DX CPUs, 96-97 487SX, 98-99, 103 80287, 86 80387, 90 8087, 84 CPUs, 75 bu ilt-in , 75-77 m axim u m sp eed s, 76 sp ecification s, 77 Pen tiu m CPUs, 105, 109 FDIV bu g, 114-116 Pen tiu m II CPUs, 143 Pen tiu m Pro CPUs, 132 W eitek, 90 MAXF (OverDrive steppin gs tables), 123 Max i Sw itch keybo ards, 1209 m ax im um cach eable m em o ry, 322 m ax im um in stallable m em o ry 80286 CPUs, 323 80386 CPUs 386DX, 323 386SX, 323

80486 CPUs, 323 8086 CPUs, 323 8088 CPUs, 323 PC/ XT an d AT d ifferen ces, 25 Pen tiu m CPUs, 105, 323 Pen tiu m II CPUs, 323 Pen tiu m Pro CPUs, 323 Pen tiu m -MMX CPUs, 323 m ax im um lo ad curren t, 416 m ax im um safe speeds (CPU clo ck speeds), 37 m ax im um speeds CPUs, 161-162 m ath cop rocessors, 76 Max to r Co rpo ratio n ESDI (En h an ced Sm all Device In terface), 609 h ard d isk p aram eters, 1365-1372 MBR (Master Bo o t Reco rd) m aster p artion boot sector (p artition tables), 1068-1070 sector errors, 1045 MBS (Master Bo o t Secto r), secto r erro rs, 1045 MCA bus (Micro Ch an n el Arch itecture), 245-246, 531 DMA ch an n els, 277 IDE (In tegrated Drive Electron ics), 611-613, 626 ISA slot ad ap ters (I/ O p ort POST cod es), 989 p ower su p p ly, 392 McAfee an ti-virus so ftw are, 1209 MCGA (MultiCo lo r Graph ics Array), 517 MCM (Multi-Ch ip Mo dule), 130 Pen tiu m Pro CPUs, 130 MD (Min im um Delay) (OverDrive steppin gs tables), 123 MD co m m an d (Win do w s 9x DOS), 1415 MDA (Mo n o ch ro m e Display Adapter), 365, 514 resolu tion , 514 MDRAM (Multiban k DRAM), 527 vid eo m em ory, 530 Mean Tim e Betw een Failures, see MTBF

memory

m ech an ical keysw itch es, 454 foam elem en t, 455-456 m em bran e, 456 p u re m ech an ical, 455 ru bber d om e, 456 Media Access Co n tro l (Eth ern et pro to co l), 700 Media Access Co n tro l, see MAC m edia den sity, 789 m edia param eter blo cks, see disk param eter blo cks Media Player ( Win do w s 3.x ) p layin g au d io CDs, 866 MIDI software, 556 MediaGX (Cyrix ), 155-156, 500 MediaGX In tel-co m patible CPUs (Cyrix ), 81 Megah ertz, see MHZ MEM.EXE (Win do w s 9x DOS), 1416 m em bran e m ech an ical keysw itch es, 456 Mem Co r glass, 733 MEMMAKER.EXE (Win do w s 95 CD-ROM), 387-390, 1417 m em o ry, 301-303 A+ exam objectives, 1171-1173 access lim its (32-bit virtu al real m od e op eration ), 45 ad ap ter board s, 385 d eterm in in g con figu ration of, 385-386 op tim izin g, 386-387 p reven tin g con flicts, 386 ad d ressable 286 CPUs, 86 386 CPUs, 87 386DX CPUs, 88 386SX CPUs, 89 486DX CPUs, 95-96 8088 an d 8086 CPUs, 83 Pen tiu m CPUs, 105-106 Pen tiu m II CPUs, 143 Pen tiu m Pro CPUs, 132 ad d ressin g, 304 ATX m oth erboard s, 174 ban ks, 329, 338-340, 353 BEDO RAM, 316 cach e 430FX ch ip set, 191 430HX ch ip set, 192 486DX CPUs, 96

cach e m iss, 320 CD-ROM d rives, 832 con trollers, 320, 322 Cyrix/ TI 486, 104 Level 1, 41-42, 92 Level 2, 41-43 m axim u m am ou n ts, 322 m obile system s, 927 ch ip cap acities, 336-338 ch ip p art n u m bers, 337-338 ch ip sp eed , 340 CMOS RAM ad d resses, 224-227 d iagn ostics statu s byte, 227-228 com p ared to storage, 301-302 con flicts, p reven tin g, 380-381 con trollers, 322 con ven tion al, 359-360 cycle tim es, CPU clock sp eed com p arison s, 313 DDR (Dou ble Data Rate) SDRAM, 318-319 d isk storage, com p ared to m ain m em ory, 301-302 DIMMs (d u al in lin e m em ory m od u les), 324-329, 959 bu ffered , 358 com p lete m em ory ban ks, creatin g, 959 con tact m etal, 959-960 p arity, 959 p in ou ts, 333-336 DRAM (d yn am ic RAM), 311-312 ECC su p p ort (ch ip sets), 957 EDO RAM (Exten d ed Data Ou t), 190, 315-316, 960 EEPROM (Electrically Erasable PROM), 308-311 EGA ch aracter sets, 516 errors, red u cin g with ECC, 346 exp an d ed , 379-380 exten d ed , 360, 376-377 DOS exten d ers (virtu al real m od e), 46 HMA (High Mem ory Area), 378-379 XMS (exten d ed m em ory sp ecification ), 377 FPM DRAM, 314-315

1485

gold -p lated com p ared to tin -p lated con tacts, 340-344 IBM PC, 1101, 1107 IBM PC AT, 1141 IBM PC XT, 1121 IBM PC XT 286, 1146, 1148 IBM Portable PC, 1127 in stallin g, 354-359 In tel su p p ort, 20 lap top s (IBM PC Con vertible), 1113 lifesp an , 302 logical, 302, 359-360 ad ap ter board s, 380-381, 385-386 con flicts, p reven tin g, 380-381 con ven tion al, 360 exp an d ed m em ory, 379-380 exten d ed m em ory, 376-379 UMA (Up p er Mem ory Area), 360-376 u p p er m em ory m an agem en t p rogram s, 387-390 m ain , 301-302 m axim u m in stallable 80286 CPUs, 323 80386 CPUs, 323 80486 CPUs, 323 8086 CPUs, 323 8088 CPUs, 323 Pen tiu m CPUs, 323 Pen tiu m II CPUs, 323 Pen tiu m Pro CPUs, 323 Pen tiu m -MMX CPUs, 323 m oth erboard s (cach e), 958 n on -volatile, see ROM p aged , 314 p arity ch ip set su p p ort, 347 error m essages, 349 p h ysical, 323-324 ban ks, 338-340 ch ip cap acities, 336-338 ch ip sp eed , 340 DIMMs (d u al in lin e m em ory m od u les), 324-329, 333-336 gold -p lated com p ared to tin -p lated con tacts, 340-344

1486

memory

in stallin g, 354-359 p art n u m bers, 337-338 SIMMs (sin gle in lin e m em ory m od u les), 324-333, 336 u p grad in g, 352-354 p rices, 303 p rin ters, 877-878 PROM (Program m able ROM), 306-308 p rotected , 324 RAM, 27 ban k wid th s, 39 DIMMs (Du al In lin e Mem ory Mod u les), 27, 106, 326, 973 EDO (Exten d ed Data Ou t), 20 id en tifyin g ch ip s, 337 m axim u m s, 25 m em ory ban k wid th s, 339 p arity, 984 PC/ 100 sp eed stan d ard , 340 p ortable com p u ters, 930 SDRAM (Syn ch ron ou s Dyn am ic RAM), 20 server req u irem en ts, 686 SIMMs (Sin gle In lin e Mem ory Mod u les), 27, 106, 326, 973 ven d ors, 1240 RDRAM (Ram bu s DRAM), 317-318 recom m en d ation s, 294-295 reserved , 362 ROM (Read On ly Mem ory), 27, 304-306 ad ap ter card s, 304-305 ad d resses, 304 au xiliary BIOS rou tin es, 305 ch ip p art n u m bers, 306 CMOS Setu p , 305 Mask ROM, 306 relation sh ip with RAM, 304 sh ad owin g, 305, 385 sp eed , 305 startu p d rivers, 305 ROM sh ad owin g, 381-382 SDRAM (Syn ch ron ou s DRAM), 316-317 sh ared , 373

SIMMs (sin gle in lin e m em ory m od u les), 324-329, 959 30-p in , 959 72-p in , 959 168-p in , 959 com p lete m em ory ban ks, creatin g, 959 con tact m etal, 959-960 p arity, 959 p in ou ts, 329-333, 336 SIPPs (Sin gle In lin e Pin Package), reseatin g, 1019 soft errors, 312, 344-346 alp h a-p articles, 344-345 cosm ic rays, 345 ECC, 351-352 fau lt toleran ce, 346 p arity ch eckin g, 347-351 sold ered to m oth erboard , 324 sp eed , 312-314 SRAM (Static RAM), 319-322 Static (IBM PC Con vertible), 1110 testin g eq u ip m en t, 1010-1011 total in stalled m em ory (com p ared to total u sable m em ory), 382-385 UMA (Up p er Mem ory Area), 360-362 ad ap ter ROM, 369-374 lin ear ad d resses, 362-364 m oth erboard BIOS, 375-376 segm en t ad d resses, 362-364 vid eo RAM, 364-369 u p grad in g, 352 op tion s for, 352-353 rep lacin g for cap acity, 353-354 selectin g ch ip s, 353 with ad ap ter board s, 354 u p p er m em ory (m an agem en t p rogram s), 387-390 vid eo, 527 bu s wid th s, 529 DRAM (d yn am ic RAM), 529 EDO RAM (Exten d Data Ou t RAM), 530 MDRAM (Mu ltiban k DRAM), 530

req u irem en ts, 529 resolu tion req u irem en ts, 527-529 SGRAM (Syn ch ron ou s Grap h ics RAM), 531 typ es, 527 u p grad in g, 529 VRAM (Vid eo RAM), 530 W RAM (W in d ow RAM), 530 XGA req u irem en ts, 520 virtu al m em ory Pen tiu m II CPUs, 143 Pen tiu m Pro CPUs, 132 see also RAM m em o ry address buses (Pen tium CPUs), 105 Mem o ry Man agem en t Un it, see MMU m em o ry m an agers (ROM BIOS(, 1035 Men do cin o , see Pen tium II CPUs Merced , see P7 CPUs Merced CPUs (P7), 158-161 Mercury (430LX) ch ipset, 189-190 Metal-In -Gap, see MIG m etal-o x ide varisto rs, see MOV m eters, DMM (Digital Multi-Meter), 1008 m etric system p refixes, 1341 u n it con version s, 1341 m ezzan in e bus, see PCI bus MFM (Mo dified Frequen cy Mo dulatio n ), 711, 714 MFT (Master File Table), 1096 d escrip tors, 1096 exten ts (n on resid en t attribu tes), 1096 log file record s, 1096 record s (resid en t attribu tes), 1096 MHz (Megah ertz), 31 bu ses, 233-234 clock sign al, 34 CPU clock sp eed s, 34 Micro Ch an n el Arch itecture, see MCA m icro -ATX m o th erbo ards, 952 Micro -Sco pe diagn o stic so ftw are, 993 m icro ATX, 402

mobile computing

m icro co de, alterin g (fix in g P6 CPU bugs), 78-79 Micro co m Netw o rkin g Pro to co l, see MNP Micro grafx Design er, 1212 Micro id Research , 17 Micro n , 19 m icro ph o n es, 581 con n ectors (sou n d card s), 566 Sou n d Blaster, 550 m icro pro cesso rs, see CPUs; pro cesso rs Micro Sco pe PC diagn o stics, 1210 Micro so ft, 12 Diagn ostics (serial p orts), 591-592 in d u stry con trol, 16 Micro so ft Cassette BASIC lan guage, 1101 Micro so ft CD-ROM Ex ten sio n s, see MSCDEX Micro so ft Diagn o stics, see MSD Micro so ft Ergo n o m ic Mo use, 485 Micro so ft In telliMo use, 490-491 Micro so ft Natural Keybo ard, 451 Micro so ft Po w erPo in t, 557 Micro so ft Video fo r Win do w s, see VFW MIDI (Musical In strum en t Digital In terface), 550 con n ectors (sou n d card s), 567 files, 553 ch an n els, 553 d evice con n ectivity, 555-556 FM syn th esis, 554 Gen eral MIDI stan d ard , 554 p layin g, 554-555 storin g, 553 wavetable syn th esis, 555 p orts, 555 software, 556 Sou n d Blaster su p p ort, 550 MIG (Metal-In -Gap) read/ w rite h eads (h ard disk drives), 737-738 MII (Cyrix 6x 86 an d 6x 86MX CPUs), 156-158

m in i fo rm facto rs, see LPX fo rm facto rs m in i-cartridges (m o bile Pen tium II CPUs), 928 m in i-DIN plugs (keybo ard co n n ecto rs), 471, 478-479 Min i-LPX m o th erbo ards, 170-173 m in i-to w er cases, 949-950 m in idrivers (Win do w s 98 displays), 539 m in ijack co n n ecto rs (so un d cards), 565 m in im um lo ad curren t, 416 MIP m appin g (3D im age tex tures), 544 MIRROR co m m an d (retired fo r Win do w s 9x ), 1418 m irro rin g d isk (NTFS), 1097 FAT32, 1084 m ix ed m o de CDs, 843 CD-ROM Read y d iscs, 844 en h an ced m u sic CDs, 844 m ix in g so un d (so un d cards), 561 MKDIR co m m an d (Win do w s 9x DOS), 1415 MMUs (Mem o ry Man gem en t Un its), 87, 365 MMX (MultiMedia eXten sio n ), 47, 953 ch ip set su p p ort, 957 in creased L1 cach e, 48 in stru ction set, 48 Pen tiu m II CPUs, 140-141 SIMD cap abilities, 48 MNP (Micro co m Netw o rkin g Pro to co l), 664 p rop rietary p rotocols, 665 Class 1 (block m od e), 666 Class 2 (stream m ode), 666 Class 3, 666 Class 4, 666 Class 5, 666 MNP 1-4 erro r co rrectio n pro to co l, 664 MNP 5 pro to co l (data co m pressio n stan dards), 664 Mo bile 440BX AGPset ch ipset, 929 m o bile co m putin g, 909 A+ exam objectives, 1174 batteries, 939-941 ch argin g, 940 d isch argin g, 940

1487

Li-ion (lith iu m -ion ), 940 Lith iu m -Ion Polym er, 940 NiCad (n ickel cad m iu m ), 939 NiMH (n ickel m etalh yd rid e), 939 p ower m an agem en t, 941-942 ven d ors, 1236 bu yin g tip s, 913 CD-ROM d rives, 931 CPUs, 918 386SL, 89 486SL, 97-98 ch ip sets, 929 Pen tiu m s, 918-928 step p in gs, 920-923 d esign , 911 h eat, 912 in creased battery efficien cy, 911 low p ower com p on en ts, 911 p ower m an agem en t, 911 d isp lays, 913 extern al, 942-944 gas p lasm a, 917 LCDs, 913-917 d ockin g station s, 944-945 flop p y d isk d rives, 931 h ard d isk d rives, 931 BIOS su p p ort, 931 PC Card , 931 u p grad in g, 931 IBM PC Con vertible, 1110 d etach able LCD, 1111 exten d able bu s in terface, 1111 m od els, 1110 op tion s, 1114 sp ecification s, 1112-1113 stan d ard featu res, 1111-1112 IBM Portable PC, 1125 com p on en ts, 1126 m od el p art n u m bers, 1129 m oth erboard , 1125 sp ecification s, 1127-1129 keyboard s, 937-938 n u m eric keyp ad s, 938 lap top s, 910 cost, 910 d ockin g station s, 910 weigh t, 910

1488

mobile computing

m em ory, 930 cartrid ges, 930 com p atibility, 930 SIMMs an d DIMMs, 930 m od em s, fin d in g con n ection s, 945 n otebooks, 910 cost, 910 weigh t, 910 PC Card s, 932 APM su p p ort, 933 ATA stan d ard , 933 Card Bu s in terface, 933 DMA su p p ort, 933 h ot-swap p able, 935-937 p in ou ts, 934 Pn P su p p ort, 933 th erm al ratin gs system , 933 Typ e I, 933 Typ e II, 933 Typ e III, 933 Typ e IV, 933 Zoom ed Vid eo in terface, 933 Pen tiu m CPUs (voltages), 72 Pen tiu m II CPUs (Pen tiu m II Mobile Mod u le), 151 p oin tin g d evices, 938-939 trackballs, 938 trackp ad , 938 trackp oin ts, 938 p ortable keyboard s, 451-452 p ortable tap e d rives, 818-819 su bn otebooks, 910 cost, 911 weigh t, 911 swap p able d rive bays, 932 u p grad in g, 912 com p atibility, 912 fin d in g com p on en ts, 913 rep lacin g com p on en ts, 912 Zip d rives, 931 m o bile m o dules (m o bile Pen tium CPUs), 151, 926-928 voltage, 927 m o bile Pen tium -MMX CPUs, 79 Mo de 1 CD-ROM-XA data type, 841 Mo de 2, Fo rm 1 CD-ROM-XA data type, 842 Mo de 2, Fo rm 2 CD-ROM-XA data type, 842

MODE co m m an d (MS-DOS) (adjustin g typem atic fun ctio n s), 460-461 MODE.COM (Win do w s 9x DOS), 1416 Mo del 1 steppin gs (Pen tium CPUs), 117 m o del n um bers (IBM PC) m o dels, 1103 IBM PC AT, 1129, 1133 068, 1132 099, 1132 239, 1133-1135 30M u p d ate kit, 1134 319, 1135 339, 1135 flop p y/ h ard d isk con troller, 1132 op tion n u m bers, 1145 p art n u m bers, 1144 system clock sp eed , 1132 IBM PC XT, 1117-1119 p art n u m bers, 1124 IBM Portable PC (p art n u m bers), 1129 Mo dem Do cto r Versio n 6, 1234 m o dem s, 655-656 56K, 667-668 d igital-to-an alog con version s, 668 d irect PSTN con n ection s, 668 lin e n oise, 669 on e-way 56K tran sm ission s, 668 stan d ard s, 669 cable (CATV), 674 con n ection s d ata bits, 657 N-8-1, 657 p arity, 657 stop bits, 657 con trol cod es, 1345 d ata com p ression stan d ard s, 664 MNP 5, 664 V.42bis, 664-665 d ata tran sm ission start bits, 656-657 stop bits, 656-657 error-correction p rotocols, 663 MNP 1-4, 664 V.42, 664 fax m od em stan d ard s, 666 Grou p III p rotocol, 667 Grou p IV p rotocol, 667

in tern al (IBM PC Con vertible), 1114 m od u lation stan d ard s, 660 Bell 103, 661 Bell 212A, 662 FSK (freq u en cy-sh ift keyin g), 661 fu ll-d u p lex p rotocols, 661 h alf-d u p lex p rotocols, 661 PSK (p h ase-sh ift keyin g), 661 QAM (q u ad ratu ream p litu d e m od u lation ), 661 V.21, 662 V.22, 662 V.23, 662 V.29, 662 V.32, 662 V.32fast, 663 V.34, 663 V.90, 663 V32.bis, 663 p arallel p ort con n ection s, 598 p ortable com p u ters, fin d in g con n ection s, 945 p rop rietary stan d ard s, 665 CSP (Com p u Com Sp eed Protocol), 666 DIS, 665 HST, 665 MNP, 665-666 V-series (Hayes), 666 recom m en d ation s, 670 56K m od els, 671 au to-n egotiation , 670 extern als, 670 in tern als, 670 sp eed s (bau d vs. bp s), 660 stan d ard s, 658 backward com p atibility, 659 Bell Labs, 658 Hayes-com p atibility, 660 ITU, 658 p rop rietary, 659 ven d ors, 1241 m o des 386 en h an ced (W in d ows 3.x), 1056 CPUs, 43 p rotected , 44 real, 44 virtu al real m od e, 45

motherboards

p rotected 486DX CPUs, 97 80286 CPUs, 86 80386 CPUs, 87 W in d ows 3.x, 1055 real 486DX CPUs, 97 80286 CPUs, 85 Stan d ard m od e (W in d ows 3.0), 1056 80286 CPUs, 86 virtu al real 486DX CPUs, 97 80386 CPUs, 87 W in d ows 95 ()VCACHE, 1079 Mo dified Frequen cy Mo dulatio n , see MFM m o dulatio n stan dards (m o dem s), 660 Bell 103, 661 Bell 212A, 662 FSK (freq u en cy-sh ift keyin g), 661 fu ll d u p lex p rotocols, 661 h alf d u p lex p rotocols, 661 PSK (p h ase-sh ift keyin g), 661 QAM (q u ad ratu re am p litu d e m od u lation ), 661 V.21, 662 V.22, 662 V.22 103, 662 V.23, 662 V.29, 662 V.32, 662 V.32fast, 663 V.34, 663 V.90, 663 V32.bis, 663 m o n ito rs, 30, 499-500, 965 actu al viewin g areas, 504-505 APM, 507 bu yin g criteria, 509 an alog m on itors, 510 con trols, 512 d ot p itch , 511 freq u en cies, 509-510 glare filters, 512 screen size, 511 testin g, 513 u sage en viron m en ts, 512 color, 503-504 CRTs (cath od e ray tu bes), 500 cu rved p h osp h or-based screen s, 501

flat p h osp h or-based screen s, 501 m u ltip le-freq u en cy, 501 refresh rates, 500-501 cu rved p h osp h or-based screen s, 501 d ot p itch , 506 en ergy-savin g featu res, 507 em ission s, 508-509 p ower m an agem en t, 507-508 flat p h osp h or-based screen s, 501 gas p lasm a d isp lays, 503 green , 508 IBM En h an ced Color Disp lay (EGA ad ap ters), 516 IBM Profession al Color Disp lay (PGA ad ap ters), 516 in p u t sou rces, 500 in terlaced , 506-507 LCDs (liq u id crystal d isp lays), 501 active-m atrix, 502-503 backligh tin g, 503 color, 503 ed geligh tin g, 503 m on och rom e, 502 p assive-m atrix, 502-503 p olarizin g filters, 501-502 resolu tion , 501 screen sizes, 511-512 su p ertwist, 503 trip le-su p ertwist, 503 m on och rom e, 503-504 m u ltip le-freq u en cy, 501 n on in terlaced , 506-507 refresh rates, 500-501 resolu tion , 505, 870 p ixels, 505 SVGA (Su p er VGA), 506 UVGA (Ultra VGA), 506 VGA (Vid eo Grap h ics Array), 506 XGA (eXten d ed Grap h ics Array), 506 RGB (CGA ad ap ters), 515 server req u irem en ts, 688 sizes actu al viewin g areas, 504-505 costs, 504 m an u factu rer d ifferen ces, 504 stan d -by m od e, 507

1489

su sp en d m od e, 507 trou blesh ootin g, 547-548 CRT m on itors, 548 d ep ot rep air, 547 Disp layMate d iagn ostic software, 548 ven d ors, 1241 vid eo ad ap ters (m u ltip le con n ection s), 539 m o n o co n n ecto rs, see m icro ph o n e co n n ecto rs Mo n o ch ro m e Display Adapter, see MDA m o n o ch ro m e LCDs (liquid crystal displays), 502 m o n o ch ro m e m o n ito rs, 503-504 m o n o spaced typeface, 879 MORE.COM (Win do w s 9x DOS), 1416 m o th erbo ard BIOS, 375-376 m em ory, 362 m o th erbo ards, 26, 167, 182, 950 80486, Am 5x86(TM)-P75, 103 A+ exam objectives, 1171-1173 ATX, 173-175, 951-952 case d esign s, 950 coolin g CPUs, 75 exp an sion slots, 952 in tern al fan , 952 m icro-ATX, 952 NLX (Low Profile), 949, 952 p ower su p p lies, 952 vid eo ad ap ter con n ection s, 500 Baby-AT, 20, 167-169, 951 case d esign s, 950 keyboard con n ectors, 951 vid eo ad ap ter con n ection s, 500 BIOS (Basic In p u t Ou tp u t System ), 208-209, 958 AMI, 210-214 Award , 214 EPROM (erasable p rogram m able read on ly m em ory), 208 error m essages, 222-224 Flash ROM, 217-221, 958 IML (In itial Microcod e Load ), 221

1490

motherboards

OEMs (Origin al Eq u ip m en t Man u factu rers), 209-210 Ph oen ix, 214-215 Pn P (Plu g an d Play su p p ort), 958 u p grad in g, 215-217 bu s sp eed s 66MHz, 35-37, 43 100MHz, 43 bu ses, 232-234 DMA ch an n els, see DMA ch an n els I/ O bu s (exp an sion slots), 238-239 I/ O p ort ad d resses, 277-281 IRQs (In terru p t ReQu est ch an n els), 271-274 m em ory bu s, 237-238 p rocessor bu s, 234-237 resou rces, 270 sp eed s, 43 wid th restriction s, 23 ch ip sets, 26, 183-185, 954, 957-958 Alad d in M1510 ch ip set, 956 AVI Ap ollo MVP3, 956 bu s su p p ort, 957 d ocu m en tation , 957 featu res to look for, 957 In tel, 185-201 In tel 430FX PCIset, 956 In tel 430HX PCIset, 955 In tel 430TX PCIset, 955 In tel 430VX PCIset, 955 In tel 440BX AGPset, 955 In tel 440FX PCIset, 955 In tel 440LX AGPset, 955 Op ti 82C550 Vip er-DP, 956 CMOS RAM ad d resses, 224-227 d iagn ostics statu s byte, 227-228 con n ectors, 228-232 IDE (In tegrated Drive Electron ics), 611 CPUs, 953, 1100 h eat sin ks, 973 Pen tiu m , 953 settin g ju m p ers, 954 d ocu m en tation , 297 exp an sin on slots (IBM PC XT Mod el 286), 1146

fu ll-size AT, 169-170, 951 h igh sp eed m em ory, see L2 cach e I/ O p orts, 960 in tegrated ad ap ters, 961 Su p er I/ O ch ip s, 960 IBM PC 8088 CPU, 1101 switch settin gs, 1108-1110, 1123-1124 IBM PC AT 80286 CPUs, 1129, 1134 exp an sion slots, 1130 IBM PC Con vertible, 1113 IBM PC XT 8088 CPUs, 1115 switch settin gs, 1123-1124 IBM PC XT Mod el 286 (80286 CPU), 1145 switch settin gs, 1108-1110 IBM Portable PCs, 1125 in stallin g cables, con n ectin g, 975-976 exp an sion card s, in stallin g, 976 m em ory m od u les, in stallin g, 973 m ou n tin g in th e case, 973-974 p ower su p p lies, con n ectin g, 974-975 p rep arin g, 972-973 In tel in d u stry con trol, 18-20 In tel-com p atibile AMD-K5 su p p ort, 125 AMD-K6 su p p ort, 153 keyboard con n ectors, trou blesh ootin g, 474-475 LPX, 170-173 Low Profile system s, 949, 952 m em ory cach e, 958 DIMMs, 959 EDO, 960 IBM PC, 1101 selectin g ch ip s, 353 SIMMs, 959-960 NLX, 20, 176-179 overclockin g, 298-299 Pen tiu m sp eed s, 36, 112 Pen tiu m II sp eed s, 36 Pen tiu m MMX sp eed s, 36 Pen tiu m Pro ch ip sets, 134

Pn P (Plu g an d Play), 290-291 BIOS, 291-292 h ard ware, 291 op eratin g system s, 292 p ower con n ectors, 403-405 ATX op tion al p ower con n ector, 405-406 d isk d rive, 408 p art n u m bers, 409 p ower switch con n ector, 406-408 p ower su p p lies, 392, 419 p rocessor slots, 182-183 p rop rietary, 179-180 backp lan e system s, 180-181 u p grad in g, 169 recom m en d ation s, 292-297 SIMM-saver, 328 Socket 7 (AGP su p p ort), 532 sp eed s CPU clock d ou blin g, 37 CPU com p arison s, 35-36 CPU overclockin g, 37 relative to CPU sp eed s, 43 settin g, 36 Su p er I/ O ch ip s, 207-208 system resou rces, 290 NICs, 289 SCSI ad ap ters, 289 serial p ort ad ap ters, 289-290 sou n d card s, 287-289 trou blesh ootin g, 281-287 USB (Un iversal Serial Bu s), 290 ven d ors, 1241 voltages (Pen tiu m -MMX CPUs), 113-114 see also CPUs;p rocessors Mo tio n Page (Win do w s 9x Mo use Co n tro l Pan el), 486 Mo tio n Pictures Ex pert Gro up, see MPEG Mo to ro la keybo ard co n tro llers (6805), 458 m o un tin g m o th erbo ards, 974 stan d offs, 973 m o un tin g rails (disk drives), 764 m o use, 29, 480-481, 964 bu tton s, 481 cables, 481 calibratin g, 484 Bu tton s Page (W in d ows 9x Mou se Con trol Pan el), 485

multimedia

Gen eral Page (W in d ows 9x Mou se Con trol Pan el), 486 Motion Page (W in d ows 9x Mou se Con trol Pan el), 486 Poin ters Page (W in d ows 9x Mou se Con trol Pan el), 486 clean in g, 1022 com p on en ts, 481 con n ectors, 472 d evice d rivers, 481 in terfaces bu s, 484 m oth erboard p orts (PS/ 2), 483 serial, 482-483 USB (Un iversal Serial Bu s), 484 left-h an d ed u sers, 485 Microsoft In telliMou se, 490-491 op to-m ech an ical m ech an ism , 481 PS/ 2 typ e, 964 server req u irem en ts, 688 trou blesh ootin g, 487 clean in g, 487 DOS ap p lication p roblem s, 490 d rivers, 489-490 in terru p t con flicts, 487-488 ven d ors, 1240 Mo use Co n tro l Pan el (Win do w s 9x ) Bu tton s Page, 485 Gen eral Page, 486 Motion Page, 486 Poin ters Page, 486 m o use co n tro llers (Super I/ O ch ips), 208 MOUSE.COM (m o use driver), 489 MOVE.EXE (Win do w s 9x DOS), 1416 m o vin g (adapter bo ard m em o ry), 386 MOVs (m etal-o x ide varisto rs), surge suppresso rs, 437 MPC (Multim edia PC), 551 MPC Level 1 m u ltim ed ia stan d ard , 552 MPC Level 2 m u ltim ed ia stan d ard , 552

MPC Level 3 m u ltim ed ia stan d ard , 552 MPC Marketin g Cou n cil, 551 MPC-3 stan d ard s (m in im u m CD-ROM sp eed s), 830 MPEG MPEG (Mo tio n Pictures Ex pert Gro up), 541, 569 com p ression , 537 d ecod ers, 537 MPEG-2 com p ression (DVD), 851 MPR I m o n ito r em issio n stan dard, 508 MPR II m o n ito r em issio n stan dard, 508 MPS 1.1 (Multi-Pro cesso r Specificatio n ), 134 MR (Magn eto -Resistive) h eads, 720 MS-DOS 4.0 (u pgrade problem s), 1041 5.0 (u pgrade problem s), 1041 5.x, 1039 6.0 (Dou bleSp ace d isk com p ression ), 1040 6.2 (Dou bleSp ace d isk com p ression ), 1040 6.21, 1040 6.22 (DriveSp ace d isk com p ression ), 1040 6.x (u pgrade problem s), 1041 ap p lication s (m ou se p roblem s), 490 com m an d s, 1413 extern al W in d ows 9x, 1415-1416 in tern al W in d ows 9x, 1414-1415 on W in d ows 95 CD-ROM, 1417 on W in d ows 98 CD-ROM, 1417 retired for W in d ows 9x, 1417-1418 CONFIG.SYS file ad d in g MSCDEX.EXE d evice d river, 864 ad d in g SCSI d evice d rivers, 863-864 exten d ed m em ory access (DOS exten d ers), 46 licen sin g for IBM com p atibles, 17-18 MSD (Microsoft Diagn ostics), 996

1491

typ em atic fu n ction s (keyboard s), ad ju stin g, 460-461 version 6.22 (m ou se d river), 490 W in d ows 9x com p arison s, 1058 Registry, 1059 W in d ows 9x win d ows (virtu al real m od e), 46 MSAV, 1418 MSBACKUP co m m an d (retired fo r Win do w s 9x ), 1418 MSCDEX.EXE device driver, 834, 1416 ad d in g to CONFIG.SYS, 864 com m an d -lin e op tion s, 865 MSD (Micro so ft Diagn o stics), 488, 996 MSD.EXE W in d ows 95 CD-ROM, 1417 W in d ows 98 CD-ROM, 1417 serial p orts, 591-592 MSDOS.SYS (MS-DOS), 1034-1036 MTBF (Mean Tim e Betw een Failures), 415, 755, 1353 Mueller, Sco tt e-m ail ad d ress, 1164 m ailin g ad d ress, 1176 p h on e n u m bers, 1176 W eb ad d ress, 1176 Multi-Ch ip Mo dule, see MCM Multi-I/ O ex pan sio n bo ards, 960 Multi-Media eXten sio n s, see MMX m ulti-po rt serial cards, 589-590 Multi-Pro cesso r Specificatio n , see MPS m ulti-speed CD-ROM drives (CAV playback), 826 Multiban k DRAM, see MDRAM MultiCo lo r Graph ics Array, see MCGA Multilin k PPP pro to co l (ISDN), 672 m ultim edia 3D grap h ics accelerators, 543 ch ip sets, 543-545 cost, 544 im age abstraction s, 544 ren d erin g im ages, 543

1492

multimedia

au d io ad ap ters, 966 CD-ROM sp eed s, 830 FireW ire (IEEE 1394), 605 in tegration (Cyrix Med iaGX CPU), 155-156 MMX CPU tech n ology, 47 in creased L1 cach e, 48 SIMD cap ability, 48 MPC-3 stan d ard s (m in im u m CD-ROM sp eed s), 830 p resen tation s, 556-557 tu torials, 557 sou n d card s, 551-552 record in g, 558 voice an n otation s, 558 voice recogn ition , 559-560 sp eakers, 966 ven d ors, 1244 stan d ard s (MPC), 551 MPC Level 1, 552 MPC Level 2, 552 MPC Level 3, 552 vid eo ad ap ters, 535 cap tu re board s, 538 DTV (Desktop Vid eo board s), 540-542 m u ltip le m on itors, con n ectin g, 539 ou tp u t d evices, 537-538 VFC (Vid eo Featu re Con n ector), 536-537 Multim edia CD stan dard, 851 MultiMedia eXten sio n , see MMX Multim edia PC, see MPC m ultim eters, 1007 m ultipro cessin g (Pen tium II CPUs), 145 m ultiple bran ch predictio n (Dyn am ic Ex ecutio n ), 49, 128 m ultiple-frequen cy m o n ito rs, 501 m ultiple in tern al registers (superscalar ex ecutio n ), 47 m ultiple m o n ito rs, 539 m ultiple registers, 40 m ultiple sessio n s CD-R (CD-Record able) d rives, 849 Ph otoCDs, 846 record in g, CD-ROM-XA (Exten d ed Arch itectu re), 840-841

m ultiple-frequen cy m o n ito rs, 509-511 LCDs, 502 m ultipro cessin g, 145 m ultipro cesso r suppo rt Pen tiu m II CPUs, 129 Pen tiu m Pro CPUs, 129 m ultiread specificatio n s (CD-RW drives), 850 m ultiscan m o n ito rs, see m ultiple-frequen cy m o n ito r m ultisessio n readin g, CD-ROM-XA (Ex ten ded Arch itecture), 843 m ultisyn c m o n ito rs, see m ultiple-frequen cy m o n ito r m ultitaskin g, 377 SCSI in terfaces, 962-963 W in d ows 3.x, 1056 Musical In strum en t Digital In terface, see MIDI Mylar (disks), 710

N N-8-1 m o dem co n n ectio n s, 657 n an o seco n ds, 312 com p ared to m egah ertz (MHz), 313 Natio n al Sem ico n ducto r, 588 serial p orts, 590 UART ch ip s (Un iversal Asyn ch ron ou s Receiver/ Tran sm itter), 588 Nato m a (440FX) ch ipsets, 203-204 NDIAGS utility, 1095 NDP (n um eric data pro cesso r), see m ath co pro cesso rs n egative vo ltages, 391 n egative-pressurizatio n case design s, 1014 Neptun e (430LX) ch ipset, 190 NetBEUI pro to co l (Win do w s fo r Wo rkgro ups), 708, 1055 NetWare, 1216 d isk p artition s, 1068 n etw o rk in terface adapters, 372-374 LANs, 688-689 bu fferin g, 691 con n ectors, 690 costs, 689 CRC (cyclic red u n d an cy ch eck), 692

d ata tran sfer n eed s, 690-691 en cod in g/ d ecod in g, 692 Eth ern et, 689 fram e form ation , 691 fu n ction s, 691 m ed ia access, 691 NICs, 689 p arallel/ serial con version , 692 sen d in g/ receivin g im p u lses, 692 Token Rin g, 689 Netw o rk layer (OSI Referen ce Mo del), 683 n etw o rkin g, 655 CATV, 673 ban d wid th , 674-675 cable m od em s, 674 p erform an ce, 675 secu rity, 675 term in ation d evices (ISDN), 672 d irect cable con n ection s, 676 n u ll m od em cables, 676 software, 677 in terfaces (d iagn ostic software), 990-991 ISDN (In tegrated Services Digital Network), 671 bearer ch an n els, 671 BONDING p rotocol, 672 BRI (Basic Rate In terface), 671 d elta ch an n els, 671 in stallin g con n ection s, 672 Mu ltilin k PPP p rotocol, 672 NFAS (Non -Facility Associated Sign alin g), 672 PRI (Prim ary Rate In terface), 671 S/ T (Su bscriber/ Term in ation ) In terface, 672 term in al ad ap ters, 672 U-In terface, 672 h ard ware ven d ors, 1242 LANs (local area n etworks), 678, 684 100Mbp s Eth ern et, 704-705 ATM (Asyn ch ron ou s Tran sfer Mod e), 705 baseban d n etworks, 678

numbers, hexadecimal

cablin g, 692-699 clien t software, 680 clien t/ server n etworks, 678 cu icu it switch in g, 681 d ata en cap su lation , 684 d ata lin k layer p rotocols, 699 FDDI (fiber d istribu ted d ata in terface), 703 IPX, 708 NetBEUI, 708 n etwork in terface ad ap ters, 688-692 NICs, 678 OSI Referen ce Mod el, 681-683 p acket switch in g, 681 p eer-to-p eer n etworks, 679-680 servers, 686-688 stacks, 681 TCP/ IP, 706-708 workstation s, 686 leased lin es, 673 T-1 con n ection s, 673 T-3 con n ection s, 673 m od em s, 656 56K m od em s, 667-669 d ata bits, 657 d ata-com p ression stan d ard s, 664-665 error-correction p rotocols, 663-664 fax m od em stan d ard s, 666-667 m od u lation stan d ard s, 660-663 N-8-1 con n ection s, 657 p arity, 657 p rop rietary stan d ard s, 665-666 recom m en d ation s, 670-671 start bits, 656-657 stop bits, 656-657 p rotocols, see p rotocols software ven d ors, 1242 top ologies, 695 bu s, 696 logical rin gs, 697 rin gs, 697 star, 696 Nex gen Nx 586 CPUs, 152-153 Nex t Available Cluster algo rith m (disk space allo catio n ), 1048-1049

NFAS (No n -Facility Asso ciated Sign aliln g), ISDN service, 672 Nibble m o de m em o ry, 314 NiCad (n ickel cadm ium ) batteries (po rtable co m puters), 939 NICs (n etw o rk in terface cards), 678, 689 trou blesh ootin g, 289 NiMH (n ickel m etal-h ydride) batteries (po rtable co m puters), 939 NLSFUNC.E XE (Win do w s 9x DOS), 1416 NLX m o th erbo ards, 20, 176-179, 401-402 LPX com p arison , 172 NMI (n o n -m askable in terrupt), 349 NO OverDrive steppin gs tables, 124 n o m in al vo ltage, 108 No n -Facility Asso ciated Sign alin g, see NFAS n o n -in telligen t ATA IDE, 619 n o n -m askable in terrupt, see NMI n o n -vo latile m em o ry, see ROM No n -Vo latile RAM, see NVRAM n o n -vo latile sto rage, see perm an en t sto rage n o n destructive fo rm atters (LLF), 768-769 n o n fatal erro rs (Ph o en ix BIOS POST audio erro r co des), 988 n o n in terlaced m o n ito rs, 506-507 n o n residen t attributes (NTFS MFT ex ten ts), 1096 No rth Bridge ch ipsets, 186, 929 430LX (Mercu ry), 189 Pen tiu m II, 200-202 440BX, 205 Alad d in Pro II, 205-206 Ap ollo Pro, 206 Pen tiu m Pro, 200-202 440FX, 203 450KX/ GX, 202 Alad d in Pro II, 205-206 Ap ollo Pro, 206 p rocessor bu s, 234 No rto n Calibrate utility, 1094

1493

No rto n Disk Do cto r, 1077, 1094 No rto n Disk Edito r utility, 1094 No rto n DiskTo o l utility, 1094 No rto n Multim edia ben ch m ark, 165 No rto n SI32 ben ch m ark, 165 No rto n Utilities diagn o stic so ftw are, 993-994 n o tebo o ks, see lapto ps;m o bile co m putin g No vell NetWare, see NetWare NS (Natio n al Sem ico n ducto r), 588 serial p orts, 590 UART ch ip s (Un iversal Asyn ch ron ou s Receive/ Tran sm itter), 588 NT-1 (ISDN term in al adapters), 672 NTDETECT.COM (Win do w s NT bo o t pro cess), 1063 NTFS file system , 731, 1095 com p atibility, 1096 secu rity, 1096-1097 lon g file n am es, 1095 MFT (Master File Table), 1096 d escrip tors, 1096 exten ts, 1096 log file record s, 1096 p artition s, creatin g, 1068, 1097 u tilities clu ster rem ap p in g, 1097-1098 d isk m irrorin g, 1097 d isk strip in g with p arity, 1097 W in d ows NT, 1062 NTLDR (Win do w s NT bo o t pro cess), 1063 NTOSKRNL.EXE (Win do w s NT Kern al), 1063 NTSC, video capture fro m , 540 n ull m o dem cables, 676 11-wire p in ou ts, 676 3-wire p in ou ts, 676 lap top com p u ter lin ks, 599 Num Lo ck (keybo ards), 454 n um bers, h ex adecim al ASCII con version s, 1326 FATs, 1076 12-bit, 1076 16-bit, 1076

1494

numeric data processors

n um eric data pro cesso rs, see m ath co pro cesso rs n um eric keypads, 447-449, 452-454 p ortable com p u ters, 938 NUMLOCK= param eter (CONFIG.SYS) (Num Lo ck feature), 454 n ut drivers (h an d to o ls), 1001 NVRAM (No n -Vo latile RAM), 512 Nx 586 CPUs (Nex gen ), 152-153

O Object Lin kin g an d Em beddin g, see OLE Object Man ager (Win do w s NT Ex ecutive), 1064 o bject-o rien ted lan guages, see Po stScript o bso lete system s (replacin g parts), 1100 o dd parity, 348 OEM (o rigin al equipm en t m an ufacturers), 1154 OEM Service Release 2, see OSR2, 1060 OEMs (Origin al Equipm en t Man ufacturers), 209-210, 1034 OLE (Object Lin kin g an d Em beddin g), 558 Om n iPOST, 1232 o n -bo ard BIOS (SCSI adapters), 990 o n bo ard cach e, see L1 cach e On e Tim e Pro gram m able, see OTP o n e-sided so un d (tro ublesh o o tin g so un d cards), 577 o n lin e services, 1242 o n lin e suppo rt reso urces, 1164 On track Disk Man ager, 619 o pen stan dards (TCP/ IP), 707 Open System s In terco n n ectio n , see OSI o peratin g en viro n m en ts (passive preven tive m ain ten an ce), 1024 o peratin g ran ge, 415

o peratin g system s, 1031 bu ild in g system s, 968 d iagn ostic software, 984, 995 MSD (Microsoft Diagn ostics), 996 W in d ows 98 System In form ation p rogram , 998 W in d ows 9x Device Man ager, 996-997 W in d ows 9x Perform an ce Mon itor, 997 W in d ows 9x Resou rce Meter, 997 W in d ows 9x System Mon itor, 997 W in d ows NT Even t Viewer, 998 DOS (Disk Op eratin g System ), 1031, 1039 5.x, 1039 boot p rocess, 1042-1047 COMMAND.COM (sh ell), 1036-1039 com m an d s, 1413-1416 d irect cable con n ection software, 677 d isk d rive in terfacin g, 1049-1053 d isk sp ace allocation , 1048-1049 d rivers (p rin ter su p p ort), 897 exten d ed DOS p artition s, 1067-1068 FAT (File Allocation Table), 1088-1095 file m an agem en t, 1048-1049 I/ O system , 1034-1036 m ach in e lan gu age, 1032 MS-DOS 5.x, 1039 MS-DOS 6.0, 1040 MS-DOS 6.2, 1040 MS-DOS 6.21, 1040 MS-DOS 6.22, 1040 p rim ary DOS p artition s, 1067 ROM BIOS, 1032-1035 sh ell fu n ction s, 1033 u p grad e p roblem s, 1040-1041 version s, 1039-1040 W in d ows 9x com p arison s, 1058-1059

flop p y d isk u sage, 779 Microsoft con trol, 16 Plu g an d Play, 292 W in d ows 3.x, 1053-1054 32-bit d isk access, 1057-1058 CD-ROM d rives (p layin g au d io CDs), 866 core files, 1056-1057 load in g, 1055-1056 MSD (Microsoft Diagn ostics), 996 typ em atic fu n ction s, ad ju stin g, 459-460 W in d ows 3.1, 1054 W in d ows 3.11, 1055 W in d ows for W orkgrou p s, 1055 W in d ows 95 16-bit backward com p atibility, 45 DCC (Direct Cable Con n ection ), 599 Disk Defragm en tation u tility, 1093 DOS com m an d s on CD-ROM, 1417 DOS u p grad e p roblem s, 1041 OSR2, 1077, 1082-1086, 1091 OSR 2.1, 968 VFAT (Virtu al File Allocation Table), 1079-1081 virtu al real m od e op eration , 45-46 W in d ows 98 Disp lay Con trol Pan el, 534-535 d isp lays (m u ltip le m on itor con n ection s), 539 DOS com m an d s on CD-ROM, 1417 FAT32 file system , 1060 Main ten an ce W izard , 1024 System In form ation p rogram , 998 vid eo d rivers, con figu rin g, 534-535 W in d ows 9x, 1058 104-key keyboard s, 449-451 boot d isks, creatin g, 1036

Orange Book specifications

CD-ROM d rives, 866-867 Con trol Pan el (m od em con n ection p referen ces), 658 d efragm en tin g files, 1023 Device Man ager, 996-997 d irect cable con n ection software, 677 DOS com m an d s, 1415-1418 DOS com p arison s, 1058-1059 DOS win d ows (virtu al real m od e), 46 even t n otification s (assign in g sou n d s), 558 FAT32 file system , 1061 gam in g (sou n d card com p atibility), 563 Keyboard Con trol Pan el (in tern ation al layou ts), 469-470 Med ia Player ap p lication , 556 Mou se Con trol Pan el, 485-486 MSD (Microsoft Diagn ostics, 996 OSR2 (OEm Service Release 2), 1060 Perform an ce Mon itor, 997 Pn P (Plu g an d Play), 1060-1061 p ortable com p u ters, 936-937 Recycle Bin , 1049 Resou rce Meter, 997 SCANDISK.EXE (DOS), 1092 SCANDSKW .EXE (W in d ows), 1092 sh arin g p rin ters, 900-901 Sou n d Record er, 557-558 Sou n d s Con trol Pan el, 557 System Mon itor, 997 typ em atic fu n ction s (keyboard s), ad ju stin g, 459-460 version s, 1060 Virtu al Mach in e Man ager, 1060 W in d ows NT, 1062 boot p rocess, 1063 CD-ROM d rives, 866-867

Even t Viewer, 998 HAL (h ard ware abstraction layer), 1063 kern el, 1063-1064 Keyboard Con trol Pan el (in tern ation al layou ts), 469-470 NTFS file system , 1062, 1095-1098 p ortable com p u ters (PC Card s), 937 Registry, 1062 sh arin g p rin ters, 900-901 typ em atic fu n ction s (keyboard s), ad ju stin g, 459-460 u ser m od e, 1064 version s, 1063 W in d ows NT Execu tive, 1064 o peratin g vo ltages, 72-74 Am 5x86(TM)-P75 CPU, 103 ju m p erin g, 104 Pen tiu m CPUs, 72, 106, 108 Pen tiu m Pro CPUs, 73 Pen tiu m -MMX CPUs (d u al-p lan e), 73 settin g ju m p ers, 73-74 o peratio n m o des (XGA adapters), 520 Opti 82C550 Viper-DP ch ipset, 956 o ptical sto rage, 823 CD-ROMs, 28-29, 823-825 beam sp litter, 827 cad d ies, 825 carin g for, 825 CLV record in g (Con stan t Lin ear Velocity), 826 d ata an d au d io d ifferen ces, 826 error correction , 827 form ats, 839-846 h istory of, 824 in terp olatin g m issin g d ata, 828 laser d iod es, 827 m ass-p rod u cin g, 825 P-CAV record in g, 826 p h otod etector, 827 read in g, 825 server m otors, 827 software storage n eed s, 828 sp ecification s, 829-846 trou blesh ootin g, 867-868 writable d rives, 846-850

1495

con figu rin g as p rim ary (m aster) d rive, 855 as secon d ary (slave) d rive, 855 SCSI d rives, 856 DVD (Digital Versatile Disc), 851 DVD-ROMs, trou blesh ootin g, 867 h istory of, 851 sp ecification s, 851-852 stan d ard s, 853-854 in stallin g d rives, 854, 862-863 bootu p testin g, 865-866 DOS CD-ROM d evice d river, 864 DOS SCSI ad ap ter d river, 863 extern al, 856-858 in terface ad ap ters, 854 in tern al, 858-859 MSCDEX.EXE, 864-865 W in d ows 3.x, 866 W in d ows 9x, 866 W in d ows NT 4.0, 866 SCSI ch ain s, 860 all extern al d evices, 861 in tern al an d extern al d evices, 861 in tern al ch ain an d term in ation , 861 ven d ors, 1242 o ptio n s IBM PC, 1104 IBM PC AT m od els (n u m bers), 1145 IBM PC Con vertible battery ch arger, 1114 CRT d isp lay ad ap ters, 1114 in tern al m od em s, 1114 m em ory card s, 1113 op tion al d isp lays, 1114 p rin ters, 1113 serial/ p arallel ad ap ters, 1114 IBM PC XT (n u m bers), 1124 o pto -m ech an ical m ech an ism s (m o use), 481 Optun e disk defragm en ter, 1200 Oran ge Bo o k specificatio n s (CD-ROM drives), 839

1496

Original Equipment M anufacturers

Origin al Equipm en t Man ufacturers, see OEMs Orio n (450KX/ GX) ch ipsets, 202-203 OSI (Open System s In terco n n ectio n ), 681-683 Ap p lication layer, 683 Data lin k layer, 683 LLC (Logical Lin k Con trol) su blayer, 683 MAC (Med ia Access Con trol) su blayer, 683 Network layer, 683 Ph ysical layer, 682 Presen tation layer, 683 Session layer, 683 Tran sp ort layer, 683 OSR2 (Win do w s 95), 1060, 1077, 1082-1086, 1091 OTP (On e Tim e Pro gram m able) PROMs, 309 o utlet testers, 1009-1010 o utput p rin ters, 869 300 d p i, 870-871 600 d p i, 871 1200 d p i, 870-871 2400 d p i, 871 d ot m atrix, 869-873, 889-890 d rivers, 881-882 escap e cod es, 877 fon ts, 878-881 in kjet, 869-870, 887-889 laser, 869-870, 882-887 m em ory, 877-878 p age, 873-877 p rice, 870 resolu tion , 870-872 su p p ort, 896-902 ratin gs (p ower su p p lies), 412 ATX, 413-414 com p atibles, 413 IBM Classic system s, 413 u n iversal, 414 vid eo d evices, 537 broad castin g screen s on television , 538 stan d ard s, 537-538 o verclo ckin g, 298-299 CPUs, 37 d isablin g, 1134 p rotectin g again st, 53 Pen tiu m CPUs, 113 see also clock sp eed s; clock m u ltip liers

OverDrive pro cesso rs, 58, 162 backp lan e system s, 181 com p atibility p roblem s, 163-164 DX2, 99-101 DX4, 101 in stallin g, 162 overh eatin g, 163 Pen tiu m CPUs, 59, 113 3.3v version , 60 486SX2 an d DX2 system s, 101 active h eat sin ks, 59 first-gen eration , 110 p ower con su m p tion , 60 sp eed ratin gs, 59 step p in gs, 122-123 Pen tiu m -MMX CPUs, 63 ju m p erin g for 60/ 66MHz op eration , 114 step p in gs, 122-123 sockets, 57-58 secon d ary, 102 o verh ead LCD display pan els, 943 o verlo ad pro tectio n (DMMs), 428 o versh o o t (vo ltage), 416 o vervo ltage pro tectio n , 416 o verw ritin g files (disk space allo catio n ), 1049 o x ide reco rdin g m edia (h ard disk drives), 734 o zo n e (affect o n prin ters), 886

P P-cables (SCSI device co n n ectio n s), 857 P-CAV (CD-ROM data), 826 P-ratin gs, 82 p-Si (lo w tem perature po lysilico n ), TFT (th in film tran sisto r) array, 915 P4, see 80486 CPUs P5 (586) CPUs, see Pen tium CPUs; Pen tium -MMX CPUs; Pen tium -co m patible CPUs P6 (686) CPUs, see Pen tium II CPUs; Pen tium Pro CPUs; Pen tium -co m patible CPUs P7 CPU (Merced), 23, 158-161 Pacific Page PE Po stScript, 1218 Pacific Page XL, 1218

packagin g CPUs, 53 Ceram ic Pin Grid Array, 37 PGA (Pin Grid Array), 53 SEC (Sin gle Ed ge Cartrid ge), 54, 67-71 SPGA (Staggered Pin Grid Array), 54 m obile Pen tiu m p rocessors, 923 TCP (tap e carrier p ackagin g), 923-928 Pen tiu m CPUs, 105, 109 secon d -gen eration , 110 Pen tiu m II CPUs, 143 SEC (Sin gle Ed ge Con tact), 140 Pen tiu m Pro CPUs, 132 Du al Cavity PGA p ackagin g, 130 packets collision s, 700 d ata en cap su lation , 684 switch in g (LANs), 681 packin g files (h ard disk m ain ten an ce), 1023 paddle bo ards (IDE), 613 Page Descriptio n Lan guage, see PDL page prin ters, PDL (Page Descriptio n Lan guages), 873-874 PostScrip t, 874-875 su p p ort for, 875-877 paged m em o ry, 314 Pagem aker, 1180 Pagem ill, 1180 pages per m in ute, see ppm pagin g, FPM (Fast Page Mo de) DRAM, 314-315 pairin g data pipelin es (Pen tium CPUs), 106 PAL (Ph aseAltern ateLin e), 537 Parado x , 1186 parallel/ serial co n versio n (n etw o rk in terface adapters), 692 parallel adapters (IBM PC Co n vertible), 1114 Parallel Po rt In fo rm atio n Utility, 1218 parallel po rts, 583, 593 25-p in con n ectors, 593-594 bid irection al, 595

passive preventive maintenance

CD-ROM d rive, 834-835 p ass-th rou gh con n ectors, 835 con figu rin g, 598 con flicts (gam e p orts), 551 con trollers (Su p er I/ O ch ip s), 207-208 d evice con n ection s, 598-599 d iagn ostics, 600 ECP (En h an ced Cap abilities Ports), 596 EPP(En h an ced Parallel Ports), 595-596 IEEE 1284, 596-597 Parallel u tility, 597 recom m en d ation s, 597 u n id irection al, 594-595 Parallel Tech n o lo gies, 597 Parallel utility, 597 param eters d elay (ad ju stin g typ em atic keyboard fu n ction s), 461 flop p y d isks, 783 h ard d isk d rives, 766, 1353 AMI ROM BIOS, 1409-1410 Award ROM BIOS, 1411-1412 Com p aq Deskp ro 386, 1408-1409 Con n er Perip h erals, In c., 1355-1357 IBM AT/ PS/ 2, 1406-1408 IBM Corp oration , 1357-1365 Maxtor Corp oration , 1365-1372 Ph oen ix ROM BIOS, 1412-1413 Qu an tu m Corp oration , 1372-1378 Seagate Tech n ology, In c., 1378-1394 Tosh iba, 1394-1397 u ser-d efin able d rive typ es, con figu rin g as, 1401-1405 W estern Digital Corp oration , 1397-1400 rate (ad ju stin g typ em atic keyboard fu n ction s), 460 tables (IBM PC AT h ard disk BIOS), 1139-1140 PARD (Perio dic an d Ran do m Deviatio n ), 417

parity bits, 347 ch eckin g, 984 430FX ch ip set, 190 430HX ch ip set, 193 alp h a p articles, 345 soft m em ory errors, 347-351 d isk strip in g (NTFS), 1097 DIMMs, 959 errors, 427, 578 p ower su p p lies, 427 trou blesh ootin g sou n d card s, 578 m em ory ch ip set su p p ort, 347 error m essages, 349 SIMMs, 959 m od em con n ection s, 657 SCSI, con figu rin g, 644 part n um bers cablin g (IBM), 478 con n ectors, 409 IBM PC, 1104 IBM PC AT m od els, 1144 IBM PC XT m od els, 1124 IBM Portable PC m od els, 1129 keyboard s IBM, 478 IBM Op tion s, 479 RAM ch ip s, 337-338 ROM ch ip s, 306 Partial-Respo n se, Max im um Likelih o o d, see PRML Partitio n It, 1222 Partitio n Magic (FAT32 co n versio n s), 1086 partitio n s AIX (UNIX), 1068 d ata area, 1079 d iagn ostic read -an d -write stru ctu re, 1079 FAT16 file system clu ster lim its, 1085 errors, 1086-1087 FAT32 file system , 1082 clu ster sizes, 1082-1084 creatin g, 1084-1085 errors, 1086-1087 FAT16 con version , 1085-1086 Jaz d rives, 1082 m irrorin g, 1084 root d irectory location s, 1083

1497

FATs (File Allocation Tables), 1076-1077 ch ain s, 1076 clu sters, 1077-1079 FDISK cop ies, 1077 h exad ecim al n u m bers, 1076 h ard d isk d rives, 731, 769 FAT (File Allocation Table), 731 FAT32, 731 m aster boot sector, 1067-1070 NTFS, 731 logical , 1067 MBR tables, 1069 byte valu es, 1070 NTFS file system s clu ster rem ap p in g, 1097-1098 creatin g, 1097 d isk m irrorin g, 1097 d isk strip in g with p arity, 1097 OS/ 2 HPFS file system , 1068 parts grabber, 1002 pass-th ro ugh cables (Diam o n d Mo n ster 3D video adapter), 537 pass-th ro ugh co n n ecto rs, 835 passive backplan e system s (pro prietary m o th erbo ards), 180-181 passive h eat sin ks, 74, 967 passive m atrix LCDs, 502, 914 cost, 915 CSTN (color su p er-twist n em atic), 915 d ou ble-scan LCDs, 502-503 DSTN (d ou ble-layer su p ertwist n em atic), 915 failed tran sistors, 914 HPA (h igh p erform an ce ad d ressin g), 915 size, 915 passive preven tive m ain ten an ce, 1011, 1024-1030 h arsh en viron m en t system s, 1030 op erain g en viron m en ts, 1024 p ower cyclin g, 1025-1027 p ower lin e n oise, 1028-1029 RFI (rad io-freq u en cy in terferen ce), 1029-1030

1498

passive preventive maintenance

static electricity, 1027-1028 tem p eratu re con trol, 1024-1025 passive term in ato rs (SCSI), 640 patch es (playin g MIDI files), 554 PATH co m m an d (Win do w s 9x DOS), 1415 PC 97 Hardw are Design Guide (PC 9x specificatio n s), 21 PC 98 System Design Guide (PC 9x specificatio n s), 21 PC 99 System Design Guide (PC 9x specificatio n s), 21 PC 9x specificatio n s (design guides), 21 PC Cards, 912 p ortable com p u ters, 932 APM su p p ort, 933 ATA stan d ard , 933 Card Bu s in terface, 933 DMA su p p ort, 933 h ard d isk d rives, 931 h ot-swap p able, 935-937 p in ou ts, 934 Pn P su p p ort, 933 th erm al ratin gs system , 933 Typ e I, 933 Typ e II, 933 Typ e III, 933 Typ e IV, 933 Zoom ed Vid eo in terface, 933 see also PCMCIA PC DOS 6.3, 1040 m ou se d river, 490 PC DOS 7.0 (IBM), m o use driver, 490 PC Ex ten derCard, 1179 PC Keybo ard Design , 479 PC Po w er Sen try, 1232 PC Repo rtCard, 1179 PC Tech n ician diagn o stic so ftw are, 994 PC Watch do g system m o n ito r, 1185 PC-Diagn o sys diagn o stic so ftw are, 994 PC/ 100 m em o ry speed stan dard, 340 PC/ XT class system s (8-bit), 23-24 system attribu tes, 24 PC/ XT fo rm facto rs, 395

PCI bus (Periph eral Co m po n en t In terco n n ect), 186, 233, 256-258, 261, 267-269, 533 ad ap ters, FireW ire (IEEE 1394), 605 AGP p orts, 268-269 bu s m asters, 268 ch ip set su p p ort, 957 IDE con n ection s, 613 In tel in d u stry con trol, 20 in terru p ts, 267-268 IRQs, 271 m obile system s, 927-929 p in ou ts, 259-267 Plu g an d Play, 267 slaves, 268 PCL (Prin ter Co n tro l Lan guage), 873 com m an d s, 873-874 PCL 3, 874 PCL 4, 874 PCL 4e, 874 PCL 5, 874 PCL 5c, 874 PCL 5e, 874 PCL 6, 874 version s, 874 PCMCIA cards (po rtable co m puters), 932 APM su p p ort, 933 ATA stan d ard su p p ort, 933 Card Bu s in terface, 933 DMA su p p ort, 933 h ot-swap p able, 935-937 p in ou ts, 934 Pn P su p p ort, 933 th erm al ratin gs system , 933 Typ e I, 933 Typ e II, 933 Typ e III, 933 Typ e IV, 933 Zoom ed Vid eo in terface, 933 see also PC Card s PD-ROM co m bo drives, 963 PDL (Page Descriptio n Lan guage), 873 PCL (Prin ter Con trol Lan gu age), 873 com m an d s, 873-874 version s, 874 PostScrip t, 874-875 su p p ort for, 875-877 peak in rush curren t, 415 peer-to -peer n etw o rks (LANs), 679-680

Pen tium CPUs, 23-24, 105, 953 32-bit in tern al registers, 39 64-bit d ata bu ses, 38 32-bit register lim itation s, 40 ad d ressable m em ory, 106 BiCMOS (Bip olar Com p lem en tary Metal Oxid e Sem icon d u ctor), 108 BTB (Bran ch Target Bu ffer), 106 bu s wid th s, 22 cach e, 107 4-way set associative, 42 L2, 108 m od es, 108 write-back, 42 Celeron , 67, 151 ch ip sets, 187-189 430FX (Triton ), 190-191 430HX (Triton II), 191-192 430LX (Mercu ry), 189-190 430NX (Nep tu n e), 190 430TX, 193-194 430VX (Triton III), 193 Alad d in IV, 197 Alad d in V, 198 Ap ollo MVP3, 196-197 Ap ollo VP-1, 194 Ap ollo VP2, 195 Ap ollo VP3, 195-196 Ap ollo VPX, 195 SiS 5581-5582, 198-199 SiS 5591-5592, 199 d ata bu s wid th , 106 DIMM wid th , 106 d u al p rocessin g, 124 first-gen eration , 109-110 m an u factu rin g p roblem s, 109 OverDrive u p grad es, 110 FPUs (floatin g p oin t u n its), 109 FDIV bu g, 114-116 iCOMP 2.0 In d ex ratin gs, 35 in stru ction p rocessin g, 107 m axim u m in stallable m em ory, 323 MMX tech n ology, 47, 23-24 bu s wid th s, 22 in creased L1 cach e, 48 SIMD cap ability, 48

Pentium Pro CPUs

m oth erboard s case d esign s, 950 ch ip sets, 955-956 sp eed s, 36 OverDrive p rocessors, 59 3.3v version , 60 active h eat sin ks, 59 p ower con su m p tion , 60 sp eed ratin gs, 59 step p in gs, 122-124 voltages, 125 p ackagin g, 109 Pen tiu m II, 23-24, 953 AGP (Accelerated Grap h ics Port), 532 AGP X2 su p p ort, 532 bu s wid th s, 22 DIB (d u al in d ep en d en t bu s) arch itectu re, 49-50 d yn am ic execu tion , 48 in tegrated cach e, 959 Pen tiu m -MMX, 953 Pen tiu m Pro, 23-24, 953 bu s wid th s, 22 DIB (d u al in d ep en d en t bu s) arch itectu re, 49-50 d yn am ic execu tion , 48 in tegrated cach e, 959 p ortable com p u ters, 918-919, 923-928 ch ip sets, 929 Pen tiu m II, 919 sp ecification s, 919-920 step p in gs, 920-923 p ower m an agem en t bu gs, 116 secon d -gen eration , 110-113 APIC (Ad van ced Program m able In terru p Con troller), 111 BFx p in s, 112 clock m u ltip liers, 111-112 clock sp eed s, 110 overclockin g, 113 OverDrive p rocessors, 113 p ackagin g, 110 sp eed s, 112 tran sistors, 111 SIMM wid th , 106 SL en h an cem en ts, 108 sockets, 54, 57 OverDrive (Socket 1), 57-58 Socket 1, 57 Socket 2, 59-61 Socket 3, 61

Socket 4, 62 Socket 5, 63 Socket 6, 63 Socket 7, 64 Socket 8, 65 ZIF, 67 sp ecification s, 105-106 SPGA (Staggered Pin Grid Array ) CPU p ackagin g, 54 step p in gs, 124 classic, 118-120 Mod el 1, 117 su p erscalar arch itectu re, 105 twin d ata p ip elin es, 105 u -p ip e an d v-p ip e, 106 voltages, 65, 72, 108, 125 ZIF sockets, 953 Pen tium II CPUs, 127-129, 140 64-bit d ata bu ses, 38 ad d ressable m em ory, 143 cach e (4-way set associative), 42 ch ip sets, 200-202 440BX, 205 440EX, 204-205 440FX, 203-204 440LX, 204 Aladdin Pro II M1621, 205 Ap ollo P6/ 97, 206 Ap ollo Pro, 206-207 SiS 5600/ 5595, 207 DIB (Du al In d ep en d en t Bu s), 49-50, 128-129, 142 d ie sizes, 141 200MHz m od el, 140 233MHz m od el, 144 266MHz m od el, 144 300MHz m od el, 144 333MHz m od el, 143 d u al p rocessin g, 152 Dyn am ic Execu tion , 48-49, 127-128, 142 bran ch execu tion , 128 d ata flow an alysis, 49, 128 m u ltip le bran ch p red iction , 49 sp ecu lative execu tion , 49, 128 ECC (Error Correction Cod e), 145 fixin g bu gs (alterin g m icrocod e), 78-79 fu tu re d evelop m en ts, 151-152 h eat p roblem s, 145

1499

iCOMP 2.0 In d ex ratin g, 35, 141 in stallin g, 145 in stru ction execu tion , 129 in tern al registers, 40 L2 cach e, 320 m axim u m in stallable m em ory, 323 MMX tech n ology, 141 Mobile Mod u le, 151 m oth erboard sp eed s, 36 m u ltip rocessin g, 145 p ower u sage, 142 ru n n in g 32-bit software, 130 SEC (Sin gle Ed ge Cartrid ge), 54, 140 Slot 1 sockets, 54, 67-71 sockets Slot 1, 67-71 Sou th Brid ge ch ip sets, 202 sp ecification s, 143 233MHz MMX m odel, 144 266MHz MMX m odel, 144 300MHz MMX m odel, 144 333MHz MMX m odel, 143 350 an d 400 MHz MMX m od els, 143 sp eed s, 141 tran sistors, 141 version ID in form ation , 147-149 voltages, 65 ID d efin ition s, 150-151 Xeon , 32, 152, 161 Slot 2, 152 Pen tium Pro CPUs, 127-130 64-bit d ata bu ses, 38 ad d ressable m em ory, 132 cach e, 130 4-way set associative, 42 ch ip sets, 134, 199-202 440FX, 203-204 450KX/ GX, 202-203 Alad d in Pro II M1621, 205 DIB (Du al In d ep en d en t Bu s), 49-50, 128-129 d ie sizes (200Mh z m od el), 133 Du al Cavity PGA p ackagin g, 130 Dyn am ic Execu tion , 48-49, 127-128 bran ch execu tion , 128 d ata flow an alysis, 49, 128

1500

Pentium Pro CPUs

m u ltip le bran ch p red iction , 49 sp ecu lative execu tion , 49, 128 fixin g bu gs (alterin g m icrocod e), 78-79 form factors, 134 iCOMP 2.0 In d ex ratin gs, 35 in stru ction execu tion , 129 in tegrated L2 cach e, 134 in tern al registers, 40 L2 cach e, 320 m axim u m in stallable m em ory, 323 MCM (Mu lti-Ch ip Mod u le), 130 ru n n in g 32-bit software, 130 sockets, 54, 57 OverDrive (Socket 1), 57-58 Socket 1, 57 Socket 2, 59-61 Socket 3, 61 Socket 4, 62 Socket 5, 63 Socket 6, 63 Socket 7, 64 Socket 8, 65 ZIF, 67 Sou th Brid ge ch ip sets, 202 sp ecification s, 132-133 150 MHz m od el, 133 166 MHz m od el, 133 180 MHz m od el, 133 200 MHz m od el, 133 200 MHz m od el with 1M in tegrated L2 cach e, 133 sp eed s, 134 SPGA (Staggered Pin Grid Array ) CPU p ackagin g, 54 step p in gs, 135-138 tran sistors, 130 VID (Voltage Id en tification ) p in s, 135 voltages, 65 Pen tium -co m patible CPUs AMD-K6, 153-154 ID m arkin gs, 155 sp ecification s, 153-154 sp eed s, 155 voltages, 155 Cyrix 6x86/ 6x86MX, 156-157 sp eed s, 157-158

Cyrix Med iaGX, 155-156 IDT W in ch ip , 82 Nexgen Nx586, 152-153 Pen tium -MMX CPUs, 47, 113-114 clock sp eed s, 113 d u al p rocessin g, 124 iCOMP 2.0 In d ex ratin gs, 35 in creased L1 cach e, 48 ju m p erin g for 60/ 66MHz op eration , 114 m obile, 79 m oth erboard sp eed s, 36 OverDrive p rocessor, 63 SIMD cap abilities, 48, 114 sockets, 54, 57 OverDrive (Socket 1), 57-58 Socket 1, 57 Socket 2, 59-61 Socket 3, 61 Socket 4, 62 Socket 5, 63 Socket 6, 63 Socket 7, 64 Socket 8, 65 ZIF, 67 SPGA (Staggered Pin Grid Array ) CPU p ackagin g, 54 step p in gs, 121-124 u p grad in g, 114 voltages, 65, 125, 113 d u al-p lan e, 73 VRM, 114 perfo rm an ce ad ap ter board m em ory, op tim izin g, 386-387 CATV n etworks, 675 h ard d isk d rives, 755-759 cach e p rogram s an d con trollers, 757-758 h ead an d cylin d er skewin g, 758-759 in terleave selection , 758 IDE (In tegrated Drive Electron ics), 612 m em ory, 312-314 BEDO RAM, 316 DDR (Dou ble Data Rate) SDRAM, 318-319 EDO RAM, 315-316 FPM DRAM, 314-315 ROM sh ad owin g, 381-382 SDRAM, 316-317

ratin gs (p ower su p p lies), 412 ATX, 413-414 com p atibles, 413 IBM Classic system s, 413 u n iversal, 414 SCSI/ IDE com p arison s, 651-653 Perfo rm an ce Mo n ito r (Win do w s 9x ), 997 Perfo rm an ce Ratin gs, 82 Perio dic an d Ran do m Deviatio n , see PARD Periph eral Co m po n en t In terco n n ect, see PCI periph erals d iagn ostic software, 984 d ocu m en tation , 1158-1159 p ortable com p u ters d ockin g station s, 944-945 extern al d isp lays, 942-944 m od em s, 945 SCSI ch ain s, 860 all extern al d evices, 861 in tern al an d extern al d evices, 861 in tern al ch ain an d term in ation , 861 perm issio n s (NTFS security), 1096-1097 persisten ce, CRTs (cath o de ray tubes), 500 perspective co rrectio n (3D im age tex tures), 544 PGA (Pin Grid Array) CPU packagin g, 53, 183 Pen tiu m CPUs, 105 ZIF sockets, 53 PGA (Pro fessio n al Graph ics Adapter), 516 ph an to m directo ries, 782 Ph ase Altern ate Lin e, see PAL ph ase jet prin tin g, 892 ph ase-sh ift keyin g, see PSK Ph D+ PC In specto r, 1232 Ph o en ix BIOS (Basic In put Output System ), 214-215 error m essages, 223 h ard d isk p aram eters, 1412-1413 POST au d io error cod es fatal errors, 986-987 n on fatal errors, 988 ph o n e lin e surge suppresso rs, 438

pliers

Ph o to CDs, 844 m akin g p rin ts from , 845 m u ltip le sesssion s, 846 Ph oto CD Portfolio d isc, 845 Ph otoCD Catalogu e d isc, 845 Ph otoYCC en cod in g form at, 845 Prin t Ph otoCD d isc, 845 Pro Ph oto CD Master, 845 resolu tion s, 845 ph o to detecto rs (CD-ROM drives), 827 ph o to dio des (CD-ROM drives), 850 ph o to lith o graph y (m an ufacturin g CPUs), 51 Ph o to m agic, 1212 ph o to recepto r, 885 Ph o to YCC en co din g fo rm at (Ph o to CDs), 845 ph ysical co n figuratio n s, reco rdin g durin g assem bly, 971 ph ysical fo rm attin g, see LLF (lo w level fo rm attin g) ph ysical in stallatio n (h ard disk drives), 764-765 Ph ysical layer specificatio n s (OSI Referen ce Mo del), 682 Eth ern et p rotocol, 700 ph ysical m em o ry, 323-324 ban ks, 338-340 ch ip cap acities, 336-338 ch ip sp eed , 340 DIMMs (d u al in -lin e m em ory m od u les), 324-329 p in ou ts, 333-336 gold -p lated com p ared to tin p lated con tacts, 340-344 in stallin g, 354-359 p art n u m bers, 337-338 SIMMs (sin gle in -lin e m em ory m od u les), 324-329 p in ou ts, 329-333, 336 u p grad in g, 352 op tion s for, 352-353 rep lacin g for cap acity, 353-354 selectin g ch ip s, 353 with ad ap ter board s, 354 ph ysical o peratio n , flo ppy disk drives, 764-765 ph ysical po w er co n n ecto rs (part n um bers), 409 pico sliders, 740

Piezo prin tin g (in kjet), 888 PIIX ch ips (PCI ISA IDE Xcelerato r), 191 PIIX Sou th Brid ge ch ip , 188-189 PIIX3 Sou th Brid ge ch ip , 188-189 PIIX4 PCI/ ISA brid ge (440BX AGPset m obile ch ip set), 929 PIIX4 Sou th Brid ge ch ip , 188-189 PIIX4E Sou th Brid ge ch ip , 188-189 pin co n n ecto rs, IDE (In tegrated Drive Electro n ics), 612 Pin Grid Array, see PGA pin o uts 16-bit ISA bu s, 243 168-p in DIMMs, 333-336 ATA IDE con n ectors, x615-616 Card / Ed ge (8-bit ISA bu s), 240 con n ector (SVGA), 522 EISA bu ses, 247 n u ll m od em cables 3-wire, 676 11-wire, 676 PC Card s, 934 PCI bu s, 259-267 SCSI, 634-635 SIMMs, 329-333, 336 USB (Un iversal Serial Bu s), 603 VL (VESA local) bu s, 255-256 pin s ATA IDE (sign als), 616-617 ATAPI-Style Lin e In con n ectors, 231 ATX m oth erboard con n ectors, 231-232 battery con n ectors, 230 CD Au d io con n ectors, 231 Ch assis In tru sion (Secu rity) con n ectors, 231 fan con n ectors, 230 IrDA con n ectors (In frared Data), 230 Keylock con n ectors, 230 LED con n ectors, 230 Pen tiu m II slot 1 sockets, 69-72 p rocessor sockets, 182-183 sp eaker con n ectors, 230

1501

Telep h on y con n ectors, 231 W ake on LAN con n ectors, 231 W ake on Rin g con n ectors, 231 PIO m o des, ATA-2/ ATA-3 IDE, 623-624, 980 pipelin es bu rst cach e, 958 ch ip set su p p ort, 957 Pip elin e Bu rst m od e (cach e m em ory), 322 Pip elin ed Bu rst SRAM, 294 in stru ction execu tion (su p erscalar execu tion ), 47 m u ltip le (in tern al registers), 40 see also d ata p ip elin es pit len gth , DVD (Digital Versatile Disc), 852 pitch (so un d), 562 pits (readin g CD-ROMs), 825 pix els, 505, 870 brigh tn ess, 503 d ead , active m atrix LCDs, 916 d ead , see failed tran sistors, 502 fixed , 502 PJL (Prin ter Jo b Lan guage) co m m an ds, 874 PKLite, 1220 PKWare Data Co m pressio n Library, 1220 PKZip, 1220 plan ar, see m o th erbo ards Plastic Quad Flat Packs, see PQFP platen , 889 platfo rm in depen den ce (TCP/ IP), 706 platters (h ard disk drives), 719-720 sizes, 732-734 playback (CD-ROMs) CAV (Con stan t An gu lar Velocity), 826 P-CAV, 826 playin g au d io CDs, 560 MIDI files, 554-555 FM syn th esis, 554 wavetable syn th esis, 555 plen um cables, 698 pliers, 1003

1502

Plug and Play

Plug an d Play, see Pn P Plus Develo pm en t divisio n , 612 Pn P (Plug an d Play), 290-291, 488, 763, 1060 BIOS, 291-292 bu s en u m erators, 1060 h ard ware, 291 op eratin g system s, 292 PC Card su p p ort, 933 PCI bu s, 267 recom m en d ation s, 296 resou rce arbitrators, 1061 SCSI, 644-645 USB (Un iversal Serial Bu s), 603-604 vid eo ad ap ters, 532 po cket sizes (DMMs), 428 Po cketPOST diagn o stic card, 1194 po in t en abler so ftw are (PC Cards), 937 Po in ters Page (Win do w s 9x Mo use Co n tro l Pan el), 486 po in tin g devices Accu p oin t (Tosh iba), 494 Alp s Glid ep oin t, 449 Glidepoin t (Alps Electric), 495 IBM TrackPoin t, 449 m ou se, 29, 480-481, 964 bu s, 484 bu tton s, 481 cables, 481 calibratin g, 484-486 clean in g, 1022 com p on en ts, 481 con n ectors, 472 d evice d rivers, 481 Microsoft In telliMou se, 490-491 m oth erboard p orts (PS/ 2), 483 op to-m ech an ical m ech an ism , 481 PS/ 2 typ e, 964 serial an d m oth erboard p ort h ybrid (PS/ 2), 483 serial in terfaces, 482 trou blesh ootin g, 487-490 USB (Un iversal Serial Bu s), 484 ven d ors, 1240 p ortable com p u ters, 938-939 trackballs, 938 trackp ad , 938 trackp oin ts, 938 trackballs, 480 TrackPoin t, 479, 491-495

po in tin g stick devices Alp s Electric Glid ep oin t, 495 IBM TrackPoin t, 491-495 Tosh iba Accu p oin t, 494 po in ts (typefaces), 879 po larizin g filters, LCDs (liquid crystal displays), 501-502 po lygo n s (displayin g 3D im ages), 543 po rtable co m puters, 909 A+ exam objectives, 1174 batteries, 939-941 ch argin g, 940 d isch argin g, 940 Li-ion (lith iu m -ion ), 940 Lith iu m -Ion Polym er, 940 NiCad (n ickel cad m iu m ), 939 NiMH (n ickel m etalh yd rid e), 939 p ower m an agem en t, 941-942 ven d ors, 1236 bu yin g tip s, 913 CD-ROM d rives, 931 CPUs, 918 386SL, 89 486SL, 97-98 ch ip sets, 929 Pen tiu m s, 918-920, 923-928 step p in gs, 920-923 d esign , 911 h eat, 912 in creased battery efficien cy, 911 low p ower com p on en ts, 911 p ower m an agem en t, 911 d isp lays, 913 extern al, 942-944 gas p lasm a, 917 LCDs, 913-917 d ockin g station s, 944-945 flop p y d isk d rives, 931 h ard d isk d rives, 931 BIOS su p p ort, 931 PC Card , 931 u p grad in g, 931 IBM Portable PC, 1125 com p on en ts, 1126 m od el p art n u m bers, 1129 m oth erboard , 1125 sp ecification s, 1127-1129

keyboard s, 451-452, 937-938 n u m eric keyp ad s, 938 lap top s, 910 cost, 910 d ockin g station s, 910 weigh t, 910 m em ory, 930 cartrid ges, 930 com p atibility, 930 SIMMs an d DIMMs, 930 m od em s, fin d in g con n ection s, 945 n otebooks, 910 cost, 910 weigh t, 910 PC Card s, 932 APM su p p ort, 933 ATA stan d ard , 933 Card Bu s in terface, 933 DMA su p p ort, 933 h ot-swap p able, 935-937 p in ou ts, 934 Pn P su p p ort, 933 th erm al ratin gs system , 933 Tu p e I, 933 Tu p e II, 933 Tu p e III, 933 Tu p e IV, 933 Zoom ed Vid eo in terface, 933 Pen tiu m II CPUs (Pen tiu m II Mobile Mod u le), 151 p oin tin g d evices, 938-939 trackballs, 938 trackp ad , 938 trackp oin ts, 938 su bn otebooks, 910 cost, 911 weigh t, 911 swap p able d rive bays, 932 u p grad in g, 912 com p atibility, 912 fin d in g com p on en ts, 913 rep lacin g com p on en ts, 912 Zip d rives, 931 po rtable tape drives, 818-819 po rtin g co de (m ach in e lan guage), 1032 po rts AGP (Accelerated Grap h ics p ort), 268-269 gam e con flicts, 551 joysticks, 551

power supplies

I/ O, 960 ad d resses, 277-281 in tegrated m oth erboard ad ap ters, 961 POST error cod es, 988-989 Su p er I/ O ch ip s, 960 IRQs, trou blesh ootin g, 274-275 MIDI, 555 p arallel, 583, 593 25-p in con n ectors, 593-594 bid irection al, 595 CD-ROM d rive, 834-835 con figu rin g, 598 d evice con n ection s, 598-599 d iagn ostics, 600 ECP (En h an ced Cap abilities Ports), 596 EPP(En h an ced Parallel Ports), 595-596 IEEE 1284, 596-597 Parallel u tility, 597 recom m en d ation s, 597 u n id irection al, 594-595 serial, 583-584 9-p in con n ectors, 584-586 25-p in con n ectors, 585-586 ad ap ters, 289-290 con figu rin g, 590-591 con n ector ad ap ters, 587 d iagn ostics, 591-593 h igh sp eed , 589-590 p ower su p p ly, 392 UART, 25, 587-589 Su p er I/ O ch ip s, 207-208 po sitive-pressure-ven tilatio n design (cases), 399 POST (Po w er-On Self Test), 209, 305, 375, 984-985 au d io error cod es, 985 AMI BIOS, 986 Ph oen ix BIOS, 986-988 boot p rocess, 1043 I/ O p ort cod es, 988-989 keyboard errors, trou blesh ootin g, 474-475 PCI card s, 989 visu al error cod es, 988 POST INDEX Gap (h ard disk secto rs), 726

Po stScript, 874-875, 1180 d rivers, 882 fon ts, 880-881 Po stScript Prin ter Descriptio n s (PPDs), 882 Po w er Buildin g Adviso r, 1194 po w er cable splitter (in tern al drives), 858 POWER co m m an d (retired fo r Win do w s 9x ), 1418 po w er co n n ecto rs (h ard disk drives), 753 po w er cyclin g (passive preven tive m ain ten an ce), 1025-1027 Po w er Go o d pin (testin g po w er supply o utput), 429 Po w er Go o d Sign al (po w er supplies), 409-410 p rocessor reset, 410 po w er lin e n o ise (passive preven tive m ain ten an ce), 1028-1029 po w er m an agem en t APM (Ad van ced Power Man agem en t), 942 con servin g batteries (p ortable com p u ters), 941 CPUs p ortable com p u ters, 918 SMM (System Man agem en t Mod e), 47 m on itors, 507-508 APM (Ad van ced Power Man agem en t), 507 DPMS (Disp lay PowerMan agem en t Sign alin g), 508 OverDrive p rocessors (Pen tiu m ), 60 Pen tiu m CPU bu gs, 116 SMM, 106 Pen tiu m II CPUs, 132, 143 p ortable com p u ters, 911 ACPI (Ad van ced Con figu ration an d Power In terface), 942 APM (Ad van ced Power Man agem en t), 942 ven d ors, 1242 VRT (Voltage Red u ction Tech n ology), m obile CPUs, 918-919 Po w er-On Self Test, see POST

1503

po w er pro tectio n system s, 435 BACKUPS, UPS (Un in terru p tible Power System s), 441 backu p s, 438 SPS(Stan d by Power Su p p lies), 439 UPS (Un in terru p tible Power Su p p lies), 440 UPS(Un in terru p tible Power Su p p lies), 439 bu ilt-in , 436 lin e con d ition ers, 438 su rge su p p ressors, 437 MOVs (m etal-oxid e varistors), 437 p h on e lin e, 438 UL 1449 stan d ard , 437 po w er supplies, 28, 391 3.3v p ower sou rces, 391-392 5v p ower sou rces, 391-392 5v_Stan d by sign al, 401 12v p ower sou rces, 391-392 ATX m oth erboard s, 173, 952 batteries (RTC/ NVRAM), 442-444 bu ild in g system s, 949 ATX, 949 sizes, 949 certification s, 417 clean in g, 1020 con n ectin g (assem blin g system s), 974-975 con n ectors, 403-405 ATX op tion al p ower con n ector, 405-406 d isk d rive, 408 p art n u m bers, 409 p ower switch con n ector, 406-408 con su m p tion calcu lation s, 417-421 d an gers, 426 FireW ire (IEEE 1394), 604 form factors, 393 in d u stry stan d ard typ es, 394-402, 405 PSU (p ower su p p ly), 393-394 fu n ction , 391-393 IBM PC, 1101 IBM PC AT, 1130 IBM PC XT, 1116 load lim its, 410-412 MCA bu ses, 392

1504

power supplies

m oth erboard s, 392 con su m p tion , 419 op eration , 391-393 p ower cyclin g (p reven tive m ain ten an ce), 1026 p ower m an agem en t, 423 Ad van ced Power Man agem en t, 423-425 En ergy Star System s, 423 p ower p rotection system s, 435 backu p s, 438-441 bu ilt-in , 436 lin e con d ition ers, 438 su rge su p p ressors, 437-438 Power_Good sign al, 393, 409-410 p rocessor reset, 410 Power_On sign al, 401 p roblem s, 425-426 ratin gs, 412 ATX, 413-414 com p atibles, 413 IBM Classic system s, 413 u n iversal, 414 rep airin g, 431-432 d ep ot rep air, 431-432 TT (tam p erp roof Torx), 432 rep lacin g, 433 bu yin g tip s, 433 sou rces, 434 SCS (term in ators), 644 serial p orts, 392 server req u irem en ts, 687-688 SFX (m icro-ATX m oth erboard s), 952 soft-off featu re, 393 sp ecification s, 414-417 switch in g su p p ly, 394 system req u irem en ts, 950 testin g, 430 load resistors, 430 variable voltage tran sform ers, 430-431 trou blesh ootin g, 426-427 d igital m u lti-m eters, 428 DMMs (Digital Mu ltiMeters), 428-430 DVOMs (Digital VoltOh m Meters), 428 tu rn in g on / off, 421-423 u n iversal, 414 ven d ors, 1242 voltage, see voltage

po w er sw itch co n n ecto rs, 406-408 black an d wh ite wires, 407 brown an d blu e wires, 407 green wires, 407 PS_ON sign al, 407 po w er usage 486 CPUs, 58 Pen tiu m II CPUs, 142 Po w er-On Self Test, see POST Po w er_Go o d sign al (po w er supply), 393 Po w er_On sign al (po w er supply), 401 po w ers o f 2 referen ce table, 1342 PPDs (Po stScript Prin ter Descriptio n s), 882 PPI (Pro gram m able Periph eral In terface), 458 ppm (pages per m in ute), 889 PPP, 708 PQFP (Plastic Quad Flat Pack), 95 PR (Perfo rm an ce Ratin g), 37 PRE-INDEX GAP (h ard disk secto rs), 727 prech argin g, 315 prefix po rtio n s, 725 prefix es (m etric system ), 1341 presen ce detect pin s (SIMMs), 329-333 Presen tatio n layer (OSI Referen ce Mo del), 683 presen tatio n s (m ultim edia applicatio n s), 556-557 tu torials, 557 preven tive m ain ten an ce, 1011 active, 1011-1012 clean in g system s, 1013-1022 h ard d isk d rives, 1022-1024 reseatin g socketed ch ip s, 1019-1020 system backu p s, 1012-1013 p assive, 1011 p rin ters, 902 d ot m atrix, 902-903 in kjet, 902 laser, 902 p ap er selection , 903 PRI (Prim ary Rate In terface), ISDN services, 671

prim ary (Level 1) cach e (486 CPUs), 92 prim ary (m aster) drives, co n figurin g o ptical as, 855 prim ary DOS partitio n s (m aster partitio n bo o t secto r), 1067 prim ary pro cesso rs, 124 Prim ary Rate In terface, see PRI prim itives (3D im ages), 544 Prin t Ph o to CD disc, 845 PRINT.EXE (Win do w s 95 CD-ROM), 1417 Prin ter Co n tro l Lan guage, see PCL Prin ter Jo b Lan guage (PJL) co m m an ds, 874 prin ters, 869 300 d p i, 870-871 600 d p i, 871 1200 d p i, 870-871 2400 d p i, 871 A+ exam objectives, 1173 bu yin g com bin ation d evices, 894 cost of con su m ables, 895-896 fax m od em / scan n er, 894 p ap er typ es, 895 p rin ter/ cop ier, 894 selection criteria, 893-896 sp eed , 894-895 color cost, 891 d ye su blim ation , 893 in kjet, 892 laser, 892 th erm al wax tran sfer, 893 d ot m atrix, 869-873 9-p in , 872 24-p in , 872-873 m em ory, 878 p reven tative m ain ten an ce, 902-903 p rin tin g, 889-890 d rivers, 881-882 Postscrip t, 882 p roblem s, 907 d ru m s, 885-886 corotron , 886-887 escap e cod es, 877 fon ts, 878-881 bitm ap , 879-880 m on osp aced , 879 p oin ts, 879 p rop ortion al, 879

processors

san s serif, 879 scalable, 879-881 serif, 879 soft fon ts, 880 in kjet, 869-870 color, 888 lim itation s, 889 Piezo p rin tin g, 888 p reven tative m ain ten an ce, 902 p rin tin g, 887 th erm al p rin tin g, 888 lap top s (IBM PC Con vertible), 1113 laser, 869-870 com m u n ication s, 883 form attin g, 884 p reven tative m ain ten an ce, 902 p rin tin g p rocess, 882 p rocessin g, 883-884 rasterizin g, 884-885 scan n in g, 885-886 ton er ap p lication , 886-887 ton er fu sin g, 887 m em ory, 877-878 ozon e, affect on , 886 p age, PDL (Page Descrip tion Lan gu age), 873-877 p reven tative m ain ten an ce, 902 d ot m atrix p rin ters, 902-903 in kjet p rin ters, 902 laser p rin ters, 902 p ap er selection , 903 p rice, 870 resolu tion , 870-871 in terp olation , 872 RET (Resolu tion En h an cem en t Tech n ology), 871-872 sh arin g, 900-901 su p p ort, 896 DOS d rivers, 897 rem ote d rivers, 901-902 W in d ows d rivers, 897-900 ven d ors, 1242 see also p rin tin g prin tin g bilevel, 890 color, 890-891 cost of p rin ters, 891 d ye su blim ation p rin ters, 893

in kjet p rin ters, 892 laser p rin ters, 892 th erm al wax tran sfer p rin ters, 893 d ot m atrix p rin ters, 889-890 fu zzy p rin t, 904 grap h ics, 885 im ages from Ph otoCDs, 845 p roblem s, 903-904 ap p lication , 908 con n ection , 906-907 d rivers, 907 h ard ware, 904-906 sp oolin g, 883 variable p rin t d en sity, 904 write-black, 886 write-wh ite, 886 see also p rin ters PRML (Partial-Respo n se, Max im um -Likelih o o d), 720 m agn etic storage, 718 Pro Ph o to CD Master disc, 845 Pro cess Man ager (Win do w s NT Ex ecutive), 1064 pro cesso rs, 10, 21, 27, 31, 83, 953, 1100 32-bit p rotected m od e op eration , 44 virtu al real m od e op eration , 45-46 4004, 10 8008, 10 8086, 83 8087 m ath cop rocessor, 84 ad d ress bu s wid th , 83 cost, 83 m axim u m in stallable m em ory, 323 8080, 10 8088, 23-24, 1101, 1115 m axim u m in stallable m em ory, 323 80286, 24, 84, 1129 80287 m ath cop rocessor, 86 IBM PC XT Mod el 286, 1145 m axim u m in stallable m em ory, 323 p rotected m od e, 86 real m od e, 44, 85 sp eed s, 85 Stan d ard m od e (W in d ows 3.0), 86

1505

80386, 87 386DX, 88 386SL, 89 386SX, 88-89 80387 m ath cop rocessor, 90 bu gs, 90-92 m axim u m in stallable m em ory, 323 MMU (Mem ory Man agem en t Un it), 87 p rotected m od e, 44, 87 virtu al real m od e, 45-46, 87 W eitek m ath cop rocessors, 90 80486, 92-93 486DX, 95-97 486SL, 97-98 486SX, 98 487SX m ath cop rocessor, 98-99, 103 AMD 486 (5x86), 80, 103-104 ch ip sets, 187 Cyrix/ TI 486, 104 DX2/ OverDrive, 99-101 DX4 p rocessors, 101 in stru ction -execu tion tim es, 92 m axim u m in stallable m em ory, 323 n ew featu res over 386, 92-93 Pen tiu m OverDrives, 101 secon d ary OverDrive sockets, 102 sockets, 54, 57-67 sp eed s, 93 u p grad in g, 95 82350 ch ip sets, 187 A+ exam objectives, 1171-1173 ATX m oth erboard s, 174 backp lan e system s, 181 Bu s Freq u en cy p in s (overclockin g p rotection ), 53 bu s wid th s, 22-23 m oth erboard restriction s, 23 circu it size, 62 clock sp eed s (m em ory cycle tim es), 313 cod en am es, 79 coolin g fan s, 399-401, 966-967

1506

processors

Cyrix Med iaGX (vid eo circu try), 500 d ata p ath s, 21 featu res, 47 DIB (d u al in d ep en d en t bu s) arch itectu re, 49-50 d yn am ic execu tion , 48 MMX tech n ology, 47 SMM (System Man agem en t Mod e), 47 su p erscalar execu tion , 47 h eat p roblem s, 73 ATX m oth erboard s, 74 h eat sin ks, 73 h eat sin ks, 966-967, 973 IBM PC AT, overclockin g, 1134 in stallin g (p rep arin g m oth erboard s), 972 In tel-com p atible, 80 AMD (Ad van ced Micro Design s), 80, 125-126 Cyrix, 81 IDT Cen tau r C6 W in ch ip , 82, 126-127 P-ratin gs, 82 m an u factu rin g bou les, 50 ch ip s, 52-53 d ies, 51 d op in g, 51 m asks, 51 overclockin g, 53 p h otolith ograp h y, 51 p h otoresists, 51 silicon , 50 wafers, 51-52 yield s, 52 m ath cop rocessors, 74 bu ilt-in , 74-76 m axim u m sp eed s, 75 sp ecification s, 76 m od es (PC/ XT an d AT d ifferen ces), 25 NLX m oth erboard s, 177 overclockin g, 298-299 OverDrive backp lan e system s, 181 com p atibility p roblem s, 163-164 DX2, 99-101 DX4, 101 in stallin g, 162 overh eatin g, 163 Pen tiu m CPUs, 59-60, 101, 110, 113

Pen tiu m -MMX CPUs, 63, 114, 122-123 sockets, 57-58, 102 P7 (Merced ), 23, 158-161 p ackagin g, 53 Ceram ic Pin Grid Array, 37 PGA (Pin Grid Array), 53 SEC (Sin gle Ed ge Cartrid ge), 54, 67-71 SPGA (Staggered Pin Grid Array), 54 Pen tiu m , 105, 953 ad d ressable m em ory, 106 BiCMOS (Bip olar Com p lem en tary Metal Oxid e Sem icon d u ctor), 108 BTB (Bran ch Target Bu ffer), 106 cach e, 107-108 ch ip sets, 187-199 classic step p in gs, 118-120 d ata bu s wid th , 106 DIMM wid th , 106 first-gen eration , 109-110 FPU, 109 FPU bu g, 114-116 in stru ction p rocessin g, 107 m axim u m in stallable m em ory, 323 Mod el 1 step p in gs, 117 OverDrive p rocessor, 59-60 p ackagin g, 109 Pen tiu m II, 532, 953 Pen tiu m MMX, 953 Pen tiu m Pro, 953 p ower m an agem en t bu gs, 116 secon d -gen eration , 110-113 SIMM wid th , 106 SL en h an cem en ts, 108 sockets, 54, 57-67 sp ecification s, 105-106 step p in gs, 124 su p erscalar arch itectu re, 105 twin d ata p ip elin es, 105-106 voltage, 108 voltages, 125 ZIF sockets, 953

Pen tiu m II, 127, 140 Celeron , 67, 151 ch ip sets, 200-207 DIB (Du al In d ep en d en t Bu s), 128-129, 142, 144 Dyn am ic Execu tion , 127-128, 142 ECC (Error Correction Cod e), 145 fu tu re d evelop m en ts, 151-152 h eat p roblem s, 145 iCOMP 2.0 In d ex ratin g, 141 in stallin g, 145 in stru ction execu tion , 129 in tern al registers, 40 Level 2 cach e, 320 m axim u m in stallable m em ory, 323 MMX tech n ology, 141 Mobile Mod u le, 151 m u ltip rocessin g, 145 p ower u sage, 142 ru n n in g 32-bit software, 130 SEC (Sin gle Ed ge Con tact) p ackagin g, 140, 54, 67-71 sockets, 67-71 Sou th Bridge ch ipsets, 202 sp ecification s, 143 sp eed s, 141 tran sistors, 141 version ID in form ation , 147-149 voltage ID d efin ition s, 150-151 Xeon , 32, 152, 161 Pen tiu m OverDrive step p in gs, 122-124 voltages, 125 Pen tiu m Pro, 127, 130 cach e, 130 ch ip sets, 134, 199-207 DIB (Du al In d ep en d en t Bu s), 128-129 Du al Cavity PGA p ackagin g, 130 Dyn am ic Execu tion , 127-128 form factors, 134 in stru ction execu tion , 129 in tegrated L2 cach e, 134

protocols

in tern al registers, 40 Level 2 cach e, 320 m axim u m in stallable m em ory, 323 MCM (Mu lti-Ch ip Mod u le), 130 revision s, 135-138 ru n n in g 32-bit software, 130 sockets, 54, 57-67 Sou th Brid ge ch ip sets, 202 sp ecification s, 132-133 sp eed s, 134 tran sistors, 130 VID (Voltage Id en tification ) p in s, 135 Pen tiu m -com p atibile AMD-K6, 153-154 Cyrix 6x86/ 6x86MX, 156-157 Cyrix Med iaGX, 155-156 Nexgen Nx586, 152-153 Pen tiu m -MMX, 113-114 clock sp eed s, 113 ju m p erin g for 60/ 66MHz op eration , 114 m axim u m in stallable m em ory, 323 m obile, 79 OverDrive p rocessor, 63 SIMD, 114 sockets, 54, 57-67 step p in gs, 121-124 u p grad in g, 114 voltages, 113, 125 VRM, 114 p ortable com p u ters, 918 ch ip sets, 929 Pen tiu m s, 918-920, 923-928 step p in gs, 920-923 p ower resets (Power Good Sign al), 410 servers, 686 settin g ju m p ers, 954 socketed (p rep arin g m oth erboard s), 972 sockets, 54, 57 OverDrive (Socket 1), 57-58 Slot 1, 67-71 Socket 2, 59-61 Socket 3, 61 Socket 4, 62 Socket 5, 63

Socket 6, 63 Socket 7, 64 Socket 8, 65 sp ecification s, 182 ZIF, 67 sp ecification s, 31-32 ad d ress bu ses, 40-41 d ata bu s wid th , 38-39 in tern al (Level 1) cach e, 41-42 in tern al registers, 39-40 m od es, 43-46 secon d ary (Level 2) cach e, 41-43 sp eed ratin gs, 33-37, 43 sp eed ratin gs, overclockin g, 53 see also MHz (Megah ertz) testin g, 76-77 u p grad in g, 161 ben ch m arks, 164-165 m axim u m sp eed s, 161-162 OverDrive p rocessors, 162-164 ven d ors, 1243 voltages, 72 Pen tiu m , 72 Pen tiu m Pro, 73 Pen tiu m -MMX, 73 wid th s, 31 work-arou n d u p d ates, 77 Pro COMM, 1195 Pro COMM Plus, 1195 Pro co m m Plus/ Rapid Rem o te, 1222 Pro fessio n al Co lo r Display (IBM), 516 Pro fessio n al Graph ics Adapter, see EGA pro gam s, cach e (h ard disk perfo rm an ce), 757-767 Pro Go ld co n tact en h an cer, 1187 pro gram m able keybo ards, 473 Pro gram m able Periph eral In terface, see PPI Pro gram m able ROM, see PROM Pro gram m ed P/ O, see PIO pro gram m in g PROMs, 308 pro gram m in g lan guages (m ach in e lan guage), 1032 assem blers, 1032 p ortin g cod e, 1032 ROM BIOS, 1032-1033

1507

pro gram s, see so tfw are pro jecto rs (LCD), 943 Pro lin e tape backup drives, 1230 PROM (Pro gram m able ROM), 306-308 EEPROM (Electrically Erasable PROM), 308-311 id en tifyin g, 306 OTP (On e Tim e Program m able), 309 p rogram m in g, 308 PROMPT co m m an d (Win do w s 9x DOS), 1415 pro po rtio n al typefaces, 879 pro prietary design s (po w er supplies), 433 pro prietary m em o ry co n n ectio n s (adapter bo ards), 354 pro prietary m o dem stan dards, 659, 665 CSP (Com p u Com Sp eed Protocol), 666 DIS, 665 HST, 665 MNP, 665 Class 1 (block m od e), 666 Class 3, 666 Class 4, 666 Class 5, 666 MNP Class 2 (stream m od e), 666 V-series (Hayes), 666 pro prietary m o th erbo ards, 179-180 backp lan e system s, 180-181 active, 181 p assive, 180-181 u p grad in g, 169 pro tected m em o ry, 324 pro tected m o de 32-bit CPUs, 44 486DX CPUs, 97 80286 CPUs, 86 80386 CPUs, 87 backward com p atibility, 44 p rocessors, 376 W in d ows 3.x, 1055 pro to co ls ap p lication (TCP/ IP), 707 BONDING, 672 d ata lin k layer, 699 ARCn et, 700 Eth ern et, 700-701 Token Rin g, 701-702

1508

protocols

error p rotection , 663 MNP 1-4, 664 V.42, 664 Eth ern et 100Mbp s Eth ern et, 704-705 backoff in tervals, 701 Eth ern et Fram e, 700 Med ia Access Con trol, 700 p acket collision s, 701 Ph ysical layer sp ecification s, 700 fax m od em Grou p III, 667 Grou p IV, 667 FDDI, 703 fu ll d u p lex, 661 Grou p III fax, 667 Grou p IV fax, 667 h alf d u p lex, 661 MNP 5 (d ata com p ression ), 664 Mu ltilin k PPP, 672 NetBEUI, 1055 p rop rietary, 665 CSp (Com p u Com Sp eed Protocol), 666 DIS, 665 HST, 665 MNP, 665-666 V-series (Hayes), 666 PS/ 2 co n n ecto rs, sin gle-en ded SCSI, 636-637 PS/ 2 Display Adapter 8514/ A, 516 PS/ 2 m o use, 964 PS/ 2 type co n n ecto rs (6-pin m in -DIN co n n ecto rs), 169 PS/ 2 type parallel po rts, 595 PS_ON sign al (po w er sw itch co n n ecto rs), 407 PSCRIPT.DRV (Win do w s 3.11 updates), 1054 pseudo -full duplex m o de (V.23 m o dulatio n stan dard), 662 PSK (ph ase-sh ift keyin g), 661 PSTN (Public Sw itch ed Teleph o n e Netw o rk), 668 PSU (po w er supply un it), 393-394 efficien cy, 416 p ower con su m p tion calcu lation s, 417-421

sp ecification s, 414-417 voltage, see voltage Public Sw itch ed Teleph o n e Netw o rk, see PSTN publicatio n s, see do cum en tatio n ;m an uals purch asin g, see buyin g tips pure m ech an ical keysw itch es, 455 Pw rite settin g, CD-RW (CD-Rew ritable), 850

Q QAM (quadrature-am plitude m o dulatio n ), 661 QAPlus, 1195 QAPlus/ FE diagn o stic so ftw are, 994-995 QBASIC.EXE W in d ows 95 CD-ROM, 1417 W in d ows 98 CD-ROM, 1417 QED (Quick Easy Disk), 1226 QEMM, 1222 QEP (Quick Easy Pro cesso r), 1226 QIC stan dards (Quarter-In ch Co m m ittee), 807-812 early typ es, 811 h igh cap acity, 811 tap e com p atability, 811-812 quadrature-am plitude m o dulatio n , see QAM quartet sign alin g (100VG Eth ern et pro to co l), 705 QuickPo st PC, 1232 QuickPo st PCIS/ 2, 1232 QuickPo st PRO, 1232 QuickSto p respo n ses (IBM TrackPo in t), 494 QuickTim e, 542 QWERTY keybo ards, 472

R R-Fo rm at, 1223 Racer II, 1232 radio w aves, 1344 radio -frequen cy in terferen ce, see RFI RAID (Redun dan t Array o f In ex pen sive Disks), 687, 1243

RAM (Ran do m Access Mem o ry), 27, 301-303 ban k wid th s, 39 BEDO DRAM, 316 cach e 430FX ch ip set, 191 430HX ch ip set, 192 ch ip s cap acities, 336-338 sp eed , 340 CMOS RAM ad d resses, 224-227 d iagn ostics statu s byte, 227-228 con ven tion al m em ory, 360 DDR (Dou ble Data Rate) SDRAM, 318-319 DIMMs (Du al In lin e Mem ory Mod u les), 27 cap acities, 326 in stallin g, 973 wid th , 106 DRAM (d yn am ic RAM), 311-312 EDO (Exten d ed Data Ou t) RAM, 20, 315-316 ch ip set su p p ort, 316 FPM com p arison s, 316 SDRAM, 316 FPM (Fast Page Mod e) DRAM, 314-315 id en tifyin g ch ip s, 337 m axim u m s (PC/ XT an d AT d ifferen ces), 25 m em ory ban k wid th s, 339 m em ory bu s, 237-238 p arity, 984 ch ip set su p p ort, 957 p art n u m bers, 337-338 PC/ 100 sp eed stan d ard , 340 p ortable com p u ters, 930 cartrid ges, 930 com p atibility, 930 SIMMs an d DIMMs, 930 RDRAM (Ram bu s DRAM), 20, 317-318 relation sh ip with ROM, 304 SDRAM (Syn ch ron ou s DRAM), 20, 316-317 ch ip set su p p ort, 957 EDO RAM com p arison s, 316 FPM RAM com p arison s, 316 server req u irm en ts, 686 sh ared m em ory, 362, 373

remote drivers

SIMMs (Sin gle In lin e Mem ory Mod u les), 27 cap acities, 326 con verters, 328 in stallin g, 973 SIMM-saver m oth erboard s, 328 stackers, 328 wid th , 106 SRAM (Static RAM), 319-322 ch ip set su p p ort, 957 cost, 319 secon d ary (Level 2) cach e, 43 testin g, 1010-1011 total in stalled m em ory (com p ared to total u sable m em ory), 382-385 ven d ors, 1240 vid eo RAM, 360, 364-365 CGA (Color Grap h ics Ad ap ter), 366 EGA (En h an ced Grap h ics Ad ap ter), 366 MDA (Mon och rom e Disp lay Ad ap ter), 365 VGA (Vid eo Grap h ics Array), 366-369 see also m em ory Ram bus DRAM (RDRAM), 317-318 Ram bus In lin e Mem o ry Mo dules, see RIMMs RAMDAC (Digital-to -An alo g Co n verter), 531 Ran do m Access Mem o ry, see RAM raster o utput scan n er (ROS), 885 raster pattern s, CRTs (cath o de ray tubes), 500 rasterizatio n (ren derin g 3D im ages), 544 an im ation , 545 laser p rin ter p rin tin g p rocess, 884-885 scan con version , 545 sh ad in g, 545 textu rin g, 545 visible su rface d eterm in ation , 545 rate param eters (MODE co m m an d), 460 ratin gs (po w er supplies), 412 ATX, 413-414 com p atibles, 413

IBM Classic system s, 413 u n iversal, 414 raw in terface perfo rm an ce (h ard disk drives), 757 RCA plugs (stereo system so un d card co n n ectio n s), 573 RD co m m an d (Win do w s 9x DOS), 1415 RDRAM (Ram bus DRAM), 317-318 RDY sign al, 782 Reach Out En terprise, 1227 Read Multiple co m m an d (ATA IDE), 618 Read On ly Mem o ry, see ROM read pro cesses (m agn etic sto rage), 712 read/ w rite h eads flop p y d isk d rives, 771-774 h ard d isk d rives, 735-739 Ferrite, 737 Magn eto-Resistive, 739-741 MIG (Metal-In -Gap ), 737-738 Th in Film , 738 m agn etic storage, 710 readin g CD-ROMs, 825 lan d s, 825 p its, 825 tracks, 825 CD-RW d iscs (CDRewritable), m u ltiread sp ecification s, 850 real m o de, 323 16-bit CPUs, 44 486DX CPUs, 97 80286 CPUs, 85 p rocessors, 377 Real Tim e Clo ck, see RTC receivin g im pulses (n etw o rk in terface adapters), 692 reco rdin g CD-ROM d ata CLV (Con stan t Lin ear Velocity), 826 P-CAV, 826 software, CD-R (CDRecord able) d rives, 848-849 sou n d card s, 557-558 Sou n d Record er, 557 voice an n otation s, 558 W AV form at, 557 waveform au d io, 564 vid eo (req u ired h ard ware), 542

1509

reco rdin g m edia (h ard disk drives) oxid e, 734 th in -film , 734-735 reco rds (NTFS MFT) d escrip tors, 1096 log file, 1096 resid en t attribu tes, 1096 RECOVER co m m an d, 1091 retired for W in dows 9x, 1418 reco very BIOS (Flash ROM), 220-221 Recycle Bin (Win do w s 9x ), 1049 Red Bo o k specificatio n s (CD-ROM drives), 839 redraw in g screen s, see refresh rates Reduced In structio n Set Co m puter, see RISC Redun dan t Array o f In ex pen sive Disks, see RAID referen ce m em o ry m ap, 359 refresh rates, 500 DRAM, 311-312 alterin g, 311-312 fixed , 501 registers 16-bit, 44 CPUs, 39-40 386SX, 89 8086, 83 8088, 83 Pen tiu m , 107 Pen tiu m II, 143 Pen tiu m Pro, 40, 132 in tern al CPUs, 39-40 m u ltip le, 40, 47 Pen tiu m II CPUs, 143 Pen tiu m Pro CPUs, 132 m u ltip le p ip elin es, 40 sizes (Pen tiu m CPUs), 105 Registry W in d ows 9x, 1059 SYSTEM.DAT, 1059 USER.DAT, 1059 W in d ows NT, 1062 reliability h ard d isk d rives, 755 of m em ory, see soft m em ory errors rem appin g disk clusters (NTFS), 1097-1098 rem o te drivers (prin ter suppo rt), 901-902

1510

remote power switch connectors

rem o te po w er sw itch co n n ecto rs, 406-408 brown an d blu e wires, 407 green wires, 407 PS_ON sign al, 407 rem o vable drives, SparQ, 802-805, 1074 rem o vable h ard disks, 719 rem o vable keycaps (En h an ced 101-key keybo ard), 449 rem o vable sto rage cartrid ges Jaz d rives, 801-802 Sp arq d rives (m axim u m root d irectory), 802804, 1074 Syq u est d rives, 801 tap e d rives, see tap e d rives Zip d rives, see Zip d rives CD-ROM d rives, 28-29 DVD-ROM d rives, 28-29 flop p y d isk d rives, 28-29, 770-795, 961 3 1/ 2-in ch form at, 779-780 5 1/ 4-in ch form at, 779-780 1.2M 5 1/ 4-in ch , 786-787 1.2M 5 1/ 4-in ch , 961 1.44M 3 1-in ch , 783 2.88M 3 1-in ch , 784-787 360K 5 1/ 4-in ch , 787 720K 3 1-in ch , 785-786 align m en t, 794-795 cables, 777-778 circu it board s, 775 clu sters, 781 com bo d rives, 961 con n ectors, 776-778 con trollers, 775-776 cylin d ers, 781 d iskette ch an gelin e, 781-782 facep lates/ bezels, 776 h ead actu ator m ech an ism s, 774 IBM PC, 1101 in stallin g, 793 logical d isk form atted p aram eters, 783 op eratin g system d isk u sage, 779 p h ysical op eration , 779 read / write h ead s, 771-774 rep airin g, 793-795 sizes, 961

sp ecification s, 778-779 sp in d le m otors, 774-775 track-wid th sp ecification s, 779 flop p y d isks (p h ysical con stru ction ), 787-793 Im ation LS-120, 962 Jaz d rives, 962 m agn etic m ed ia, 797-799 m akin g bootable, 1072 p ortable com p u ters flop p y d isk d rives, 931 Zip d rives, 931 sp ecification s, 802-804 tap e d rives 8m m tap e, 814 backu p software, 820-821 cap acities, 817 cost, 818 DAT stan d ard s, 812-814 d ata th rou gh p u t, 818 DLT stan d ard s, 814-815 in stallin g, 819-820 p ortable, 818-819 QIC stan d ard s, 807-812 software com p atibility, 817-818 Travan cartrid ge tap e, 815-816 ven d ors, 1245 Zip d rives, 961 Rem o ve It, 1222 rem o vin g keycaps (clean in g keybo ards), 477 REN co m m an d (Win do w s 9x DOS), 1415 RENAME co m m an d (Win do w s 9x DOS), 1415 ren derin g 3D im ages, 543-545 geom etry, 544 keyfram es, 543 rasterization , 544 sh ad in g, 543 textu re m ap p in g, 543 repairin g, see pro blem s; m ain ten an ce; tro ublesh o o tin g repetitive stress in juries (ergo n o m ic keybo ards), 473 REPLACE.EXE (Win do w s 95 CD-ROM), 1417 replacin g com p on en ts d iscon tin u ed system s, 1100 p ortable com p u ters, 912 h ard d isk d rives (p ortable com p u ters), 931

keyboard s, 478 IBM m od els, 478-479 m em ory ch ip s, 353-354 p ower su p p lies, 433 bu yin g tip s, 433 sou rces, 434 reseatin g so cketed ch ips, 1019-1020 m em ory SIPPs, 1019 reserved m em o ry, 362 residen t attributes (NTFS MFT reco rds), 1096 residen t DOS co m m an ds, 1037 resisto rs active term in ators (SCSI), 640 load (testin g p ower su p p lies), 430 p assive term in ators (SCSI), 640 reso lutio n CGA (Color Grap h ics Ad ap ter), 515 EGA (En h an ced Grap h ics Ad ap ter), 515 LCDs, 914, 917 color d ep th , 917 virtu al screen arran gem en ts, 917 MDA (Mon och rom e Disp lay Ad ap ter), 514 m on itors, 505, 870 LCDs (liq u id crystal d isp lays), 501 p ixels, 505 recom m en d ed screen sizes, 511 SVGA (Su p er VGA), 506 UVGA (Ultra VGA), 506 VGA (Vid eo Grap h ics Array), 506 XGA (eXten d ed Grap h ics Array), 506 Ph otoCDs, 845 p rin ter, 870-871 in terp olation , 872 RET (Resolu tion En h an cem en t Tech n ology), 871-872 settin g (W in d ows Disp lay Con trol Pan el), 534 SVGA (Su p er VGA), 522 vid eo m em ory req u irem en ts, 527-529 Reso lutio n En h an cem en t Tech n o lo gy, see RET Reso urce Meter (Win do w s 9x ), 997

root directories

reso urces ap p en d ixes, 1166 arbitrators (W in d ows 9x Pn P), 1061 au th or’s em ail ad d ress, 1164 bu ses, 270 d ocu m en tation , 1154-1155 ch ip an d ch ip set level, 1156, 1160-1162 com p on en t level, 1156 system level, 1156-1159, 1163 h an d s-on exp erien ce, 1165-1166 m agazin es, 1163-1164 on lin e, 1164 Plu g an d Play, 290-291 BIOS, 291-292 h ard ware, 291 op eratin g system s, 292 sem in ars, 1165 trou blesh ootin g, 281, 290 con figu ration tem p lates, 283-287 m an u ally, 281-283 NICs, 289 SCSI ad ap ters, 289 serial p ort ad ap ters, 289-290 sou n d card s, 287-289 USB (Un iversal Serial Bu s), 290 RESTORE.EXE (Win do w s 95 CD-ROM), 1417 RET (Reso lutio n En h an cem en t Tech n o lo gy), 871 retail o utlets, 1243 retired DOS co m m an ds, 1417-1418 reverse flo w co o lin g (ATX fo rm facto rs), 398 reverse so ftw are en gin eerin g, 17 revisio n bytes IBM PC BIOS, 1105 IBM PC XT, 1119 RFI (radio -frequen cy in terferen ce), passive preven tive m ain ten an ce, 1029-1030 RGB m o n ito rs (CGA adapters), 515 ribbo n cables (in tern al drive in stallatio n s), 858-859 RIMMs (Ram bus In lin e Mem o ry Mo dules), 317 rin g to po lo gies, 697

ripple, 417 RISC (Reduced In structio n Set Co m puter), 47, 105, 448 riser cards Low Profile exp an sion slots, 949 LPX m oth erboard s, 171 RJ45 co n n ecto rs, 690 RLL (Run Len gth Lim ited), 711, 715-716 en cod in g, 608-609 RMDIR co m m an d (Win do w s 9x DOS), 1415 ROM (Read On ly Mem o ry), 27, 208, 304-306 ad ap ter card s, 304-305 ad ap ter ROM, 369 h ard d rive an d SCSI con troller BIOS, 370-372 n etwork ad ap ter card s, 372-374 vid eo ad ap ter BIOS, 369-370 ad d resses, 304, 763 au xiliary BIOS rou tin es, 305 bu rn er, 307 ch ip p art n u m bers, 306 CMOS Setu p , 305 d rivers (startu p ), 305 EEPROM (Electrically Erasable PROM), 308-311 Flash ROM, 369 Mask ROM, 306 m em ory con flicts, p reven tin g, 380-381 m oth erboard BIOS, 375-376 Program m er, 307 PROM (Program m able ROM), 306-308 relation sh ip with RAM, 304 sh ad owin g, 305, 385, 381-382 sp eed , 305 ROM BIOS, 209, 958, 1032-1033 AMI, 210-214 d iagn ostics, 213 ID strin gs, 211-213 Award , 214 COMMAND.COM (sh ell), 1036 com m an d file search p roced u re, 1037-1039 resid en t com m an d s, 1037 tran sien t com m an d s, 1037

1511

con ten ts, 26 d irect h ard ware access, 1035 EPROM (Erasable Program m able ROM), 208 error m essages, 222-224 Flash ROM, 217, 958 recovery, 220-221 u p grad es, 217-219 h ard d isk p aram eters AMI ROM BIOS, 1409-1410 Award ROM BIOS, 1411-1412 Com p aq Deskp ro 386, 1408-1409 IBM AT/ PS/ 2, 1406-1408 Ph oen ix ROM BIOS, 1412-1413 I/ O system , 1034-1035 IBMBIO.COM (IBM DOS), 1035 IBMDOS.COM (IBM DOS), 1036 IO.SYS (MS-DOS), 1035 MSDOS.SYS (MS-DOS), 1036 IBM 101-key keyboard su p p ort, 454 IML (In itial Microcod e Load ), 221 in terru p ts, 1032-1033 m em ory m an agers, 1035 Nu m Lock fu n ction , 454 OEMs (Origin al Eq u ip m en t Man u factu rers), 209-210 Ph oen ix, 214-215 Pn P (Plu g an d Play) su p p ort, 958 recom m en d ation s, 295 stan d ard in terface, 1034 u p grad in g, 215-216 keyboard con trollers, 216-217 see also ROM;BIOS ro o m -tem perature vulcan izin g, see RTV ro o t directo ries, 1073-1075 d ate/ tim e of last ch an ge, 1073 en try lim its, 1074 file attribu te byte, 1073-1075 file n am es an d exten sion s, 1073 file size, 1073 form ats, 1074-1075 lin k to start clu ster, 1073

1512

root directories

organ ization , 1074 p artition location s (FAT32), 1083 su bd irectories, 1073 tracin g files, 1074 ROS (raster o utput scan n er), 885 ro tary vo ice co il actuato rs, 743 ro utin es, aux iliary BIOS, 304 RTC (Real Tim e Clo ck), 442 RTC/ NVRAM batteries, 442-444 RTV sealer (ro o m -tem perature vulcan izin g sealer, 1015 rubber do m e m ech an ical keysw itch es, 456 Run Len gth Lim ited, see RLL

S S-Video co n n ecto rs, 542 S/ T (Subscriber/ Term in atio n ) In terface (ISDN h ardw are), 672 S3 Auro ra video adapter, 539 S3-ViRGE video adapter series, 539 S3Trio -64V+ video adapter, 539 SafeSkin keybo ard pro tecto r, 1210 sam plin g so un d cards, 564 san s serif fo n ts, 879 SBIC (SCSI Bus Adapter Ch ip), 647 scalable fo n ts, 879-880 PostScrip t, 880-881 Tru e Typ e, 881 scan co des, 462 83-key PC/ XT keyboard s, 463-464 84-key AT keyboard s, 464-465 tran slation s, 447 101-key keyboard s, 466-469 104-key W in d ows keyboard s (n ew keys), 469 errors, trou blesh ootin g, 474 scan co n versio n (3D im age rasterizatio n ), 545 SCANDISK co m m an d, 1091-1092 ad van ced op tion s, 1092 SCANDISK.INI (W in d ows), 1092

testin g op tion s, 1092 W in d ows 9x version s, 1092 SCANDISK.EXE (Win do w s 9x DOS), 1416 SCANDISK.INI (Win do w s), 1092 scan n in g (laser prin ter prin tin g pro cess), 885-886 scan n in g frequen cies (m o n ito r refresh rates), 500 SCANREG.EXE (Win do w s 98 DOS), 1416 scatter w rite (DMA ch an n els), 277 scratch es, o ptical discs, rem o vin g, 867 scratch y so un d (tro ublesh o o tin g so un d cards), 578 screen flicker, 500, 506, 510, 515, 538 screen size active m atrix LCDs, 916 m on itors (bu yin g tip s), 511 screw drivers En glish an d m etric th read system s, 1005 m agn etic tip s, 1001 screw s, 1004 En glish an d m etric th read system s, 1005 th u m b, 1004 Torx (tam p erp roof), 1004 SCSI (Sm all Co m puter System In terface), 627-628 accessories (ven d ors), 1243 ad ap ters on -board BIOS, 990 trou blesh ootin g, 289 ANSI stan d ard s, 628-630 ASPI (Ad van ced SCSI Program m in g In terface), 645 cablin g, 634 sin gle en d ed , 635-639 term in ators, 639-640 CAM (Com m on Access Meth od ), 645 ch ain s, 860 all extern al d evices, 861 in tern al an d extern al d evices, 861 in tern al ch ain an d term in ation , 861 com m an d s, q u eu in g, 633

con figu rin g, 640, 645-646 IDs, 641-642 p arity, 644 Start on Dem an d , 643-644 syn ch ron ou s n egotiation , 644 term in ation , 642-643 term in ator p ower su p p lies, 644 d evices (d iagn ostic software), 989-990 d ifferen tial, 630-631 Fast SCSI, 632 Fast-40 SCSI, 632 Fiber Ch an n el SCSI, 632 h ost ad ap ters, 653 au to term in atin g, 861 IDE com p arision s, 646 h ard ware, 646-651 p erform an ce, 651-653 in terfaces, 962-963 CD-ROM, 830, 833 h ard d isk d rives, 761 in stallin g op tical d rives, 854 LLF software, 767 op tical d rives, con n ectin g, 856-858 p in ou ts, 634-635 Pn P (Plu g an d Play), 644-645 SCSI-2 (X3), 631-632 SCSI-3, 632-633 sin gle-en d ed , 630-631 term in ation , 632-633 Ultra SCSI (Fast-20), 632 W id e SCSI, 632 SCSI BIOS, 763 SCSI Bus Adapter Ch ip, see SBIC SCSI co n tro ller BIOS, 370-372 SCSI h ard drives (po w er co n sum ptio n ), 420 SCSI Select utility (Adaptec), SCSI diagn o stic so ftw are, 990 SCSI-2, 629-630 (X3), 631-632 com m an d s, 633 SCSI-3, 629-633 SDL (Sh ielded Data Lin k), 471 SDRAM (Syn ch ro n o us DRAM), 316-317, 527 100MHz bu s su p p ort, 317 430VX ch ip set, 193 ch ip set su p p ort, 316, 957

setting up

DDR (Dou ble Data Rate) SDRAM, 318-319 EDO RAM com p arison s, 316 FPM RAM com p arison s, 316 laten cy, 316 PC/ 100, 317 sp eed s, 317 SEC (Sin gle Edge Cartridge) CPU packagin g Pen tiu m II (Slot 1 sockets), 69 Pen tiu m II CPUs, 54, 140, 927 Slot 1 sockets, 67-71 SEC-DED (ECC), 351 SECAM (SEquen tial Co uleur Avec Mem o ire), 537 seco n d gen eratio n pro cesso rs, see 80286 CPUs seco n d-gen eratio n Pen tium CPUs, 110-113 APIC (Ad van ced Program m able In terru p Con troller), 111 BFx p in s, 112 clock m u ltip liers, 111-112 clock sp eed s, 110 overclockin g, 113 p ackagin g, 110 sp eed s, 112 tran sistors, 111 seco n dary (L2) cach e, 41-43 4-way set associative, 42 DIB arch itectu re, 49 m obile system s, 919, 927-928 Pen tiu m CPUs, 108 Pen tiu m II, 202 Pen tiu m Pro CPUs, MPS 1.1 (Mu lti-Processor Sp ecification ), 134 seco n dary (slave) drives, co n figurin g o ptical as, 855 seco n dary OverDrive so ckets, 102 seco n dary pro cesso rs, 43, 108, 124 secto r erro rs (bo o t pro cess), 1044-1047 MBR (Master Boot Record ), 1045 MBS (Master Boot Sector), 1045 Secto r ID data (h ard disk secto rs), 727

secto rs CD-ROMs, 826, 829 d ata tran fer rates, 829 h ard d isk d rives, 724-728 17-sector/ 17-track form ats, 726 INTER-RECORD GAP, 727 POST INDEX Gap , 726 PRE-INDEX GAP, 727 Sector ID d ata, 727 W RITE TURN-ON GAP, 727 m aster p artition boot, 1067-1071 overh ead , DVD (Digital Versatile Disc), 852 p er track (m an u al d rive typ in g), 766 sp are, 1079 tran slation s, 756 volu m e boot, 1071-1073 security CATV n etworks, 675 Ch assis In tru sion (Secu rity) con n ectors, 231 NTFS p erm ission s, 1096-1097 viru ses (m aster p artition boot sector), 1068 Security Referen ce Mo n ito r (Win do w s NT Ex ecutive), 1064 segm en t addresses (Upper Mem o ry Area), 362-364 selectin g m em o ry ch ips, 353 self-clean in g len ses (CD-ROM drives), 837 self-iden tifyin g periph erals, USB (Un iversal Serial Bus), 603-604 sem i-pro prietary m o th erbo ards LPX, 170-173 u p grad in g, 169 sem in ars, 1165 sen din g im pulses (n etw o rk in terface adapters), 692 SEquen tial Co uleur Avec Mem o ire, see SECAM serial adapters, lapto ps (IBM PC Co n vertible), 1114 serial m ice, 482 serial po rts, 583-584 9-p in con n ectors, 584-586 25-p in con n ectors, 585-586

1513

ad ap ters, trou blesh ootin g, 289-290 con figu rin g, 590-591 con flicts (gam e p ort), 551 con n ector ad ap ters, 587 con trollers (Su p er I/ O ch ip s), 207 d iagn ostics, 591 loop back tests, 592-593 MSD (Microsoft Diagn ostics), 591-592 W in d ows 95/ 98, 592 h igh sp eed , 589-590 IRQs, trou blesh ootin g, 274-275 p ower su p p ly, 392 UART (Un iversal Asyn ch ron ou s Receiver/ Tran sm itter) ch ip s, 587-589 PC/ XT an d AT d ifferen ces, 25 USB (Un iversal Serial Bu s), 290 Serial Presen ce Detect (DIMMs), 336 serif fo n ts, 879 SERS (so ft erro r rates), 344 servers, 679 LANs (local area n etworks), 686 backu p s, 687 m em ory req u irem en ts, 686 p ower su p p lies, 687-688 p rocessors, 686 storage req u irem en ts, 687 u ser in terface com p on en ts, 688 services, see in terrupts servo -co n tro lled (in dex ), 742 servo m ech an ism s, 744-748 CD-ROM d rives, 827 d ed icated , 748 em bed d ed , 746-747 wed ge, 745-746 Sessio n layer (OSI Referen ce Mo del), 683 SET co m m an d (Win do w s 9x DOS), 1415 settin g up CMOS setu p , 209 BIOS u p grad es, 218 EISA bu s, 247 ROM BIOS, 26

1514

SETVER device driver

SETVER device driver, 389, 1059 retired for W in dows 9x, 1418 SEUs (sin gle even t upsets), 344 SFX fo rm facto rs (co o lin g fan s), 402 SFX po w er supplies (m icro ATX m o th erbo ards), 952 SGRAM (Syn ch ro n o us Graph ics DRAM), 527, 531 sh adin g (3D im age rasterizatio n ), 545 sh ado w in g ROM ch ips, 305, 381-382, 385 SHARE co m m an d (retired fo r Win do w s 9x ), 1418 sh ared m em o ry, 362, 373 sh arin g prin ters, 900-901 sh ell fun ctio n s (COMMAND.COM), 1036 com m an d file search p roced u re, 1037-1039 resid en t com m an d s, 1037 tran sien t com m an d s, 1037 SHELL.DLL (Win do w s 3.11 updates), 1054 sh ielded Cen tro n ics co n n ecto r, 634 sh ielded co n n ecto rs (sin gle-en ded SCSI), 636-639 Sh ielded Data Lin k, see SDL sh ielded tw isted pair, see STP sh o ck m o un tin g (h ard disk drives), 759 sh o ppin g fo r, see buyin g tips sin gle-gap h eads, 739 sign als ATA IDE, 616-617 bu ses, 270 keyboard con n ector, 471-472 skew an d jitter, 600-601 silico n (CPU m an ufacturin g), 50 silico n e lubrican ts, 1018 SIMD (Sin gle In structio n , Multiple Data), Pen tium MMX CPUs, 48, 114 SIMMs (sin gle in lin e m em o ry m o dules), 324-329, 959 30-p in , 959 36-bit in terleaved , 328 72-p in , 959 168-p in , 959 ban ks, 338-340 wid th s, 39 cap acities, 326

COAST/ CELP stan d ard , 958 com p lete m em ory ban ks, creatin g, 959 con tact m etal, 959-960 con verters, 328 EDO, 960 gold -p lated com p ared to tin p lated con tacts, 340-344 in stallin g, 354-359 p arity, 959 ch eckin g, 347 p in ou ts, 329-333, 336 p ortable com p u ters, 930 rep lacin g, 353-354 selectin g, 353 SIMM-saver m oth erboard s, 328 sp eed s (relative to CPU sp eed s), 43 stackers, 328 testin g, 1010-1011 ven d ors, 1240 wid th (Pen tiu m CPUs), 106 sin gle den sity en co din g, 714 see also FM (Freq u en cy Mod u lation ) syn th esis Sin gle Edge Cartride, see SEC sin gle even t upsets (SEUs), 344 sin gle in -lin e m em o ry m o dules, see SIMMs Sin gle In lin e Pin Packages, see SIPPs Sin gle In structio n , Multiple Data (SIMD), 326, 1019 sin gle-en ded SCSI, 630-631 cablin g, 635-639 sin gle-speed CD-ROM drives, 829-830 SIO So uth Bridge ch ip, 188-189 SIPPs (Sin gle In lin e Pin Package), 326 reseatin g, 1019 SiS (Silico n in tegrated System s) ch ipsets, 198 Pen tiu m p rocessors 5581-5582, 198-199 5591-5592, 199 Pen tiu m II p rocessors (5600/ 5595), 207 six th gen eratio n CPUs, see Pen tium ; Pen tium II; Pen tium Pro ; Pen tium -co m patible CPUs SIZER.EXE (Win do w s 95 CD-ROM), 1417

sizes active m atrix LCDs, 916 cases an d p ower su p p lies (Low Profile), 949 clu sters (FAT32), 1083-1084 flop p y d isk, 1077-1078 h ard d isk, 1078-1079 MCA bu ses, 246 m on itors actu al viewin g areas, 504-505 costs, 504 m an u factu rer d ifferen ces, 504 p assive m atrix LCDs, 915 skew in g, 600-601 h ead an d cylin d er (h ard d isk p erform an ce), 758-759 skirts (16-bit ISA bus), 242 SL en h an cem en ts (Pen tium CPUs), 108 slaves d u al d rives (ATA IDE), 615 op tical, con figu rin g as, 855 PCI bu ses, 268 sliders, h ead, 739-740 slim lin e cases, see LPX Slo t 1 (Pen tium II CPUs), in terfaces, 200 p in n am es, 69-72 SEC (Sin gle Ed ge Cartrid ge) CPU p ackagin g, 54 sockets, 67 Slo t 2 (Pen tium II-MMX CPUs) 350 an d 400MHz m od els, 143 Xeon , 152 slo ts Baby-AT m oth erboard s, 167-168 con n ectors (fu ll-size AT m oth erboard ), 170 exp an sion (I/ O bu s), 238-239 AGP p orts, 268-269 EISA (Exten d ed ISA) bu s, 246-249 in sertin g sou n d card s, 572 ISA bu s, 239-244 local bu ses, 250-252 MCA (Micro Ch an n el Arch itectu re) bu s, 245-246 PCI bu s, 256-269 VESA local bu s, 252-256 LPX m oth erboard s, 171 p rocessors, 182-183

sound cards

Sm all Quad Flat Packs, 95 Sm art Video bo ards (In tel), In deo co dec, 541 Sm artCable, 1226 SMARTDrive, 757-758, 1079 SMARTMON co m m an d (retired fo r Win do w s 9x ), 1418 SMC n etw o rk in terface cards (EZSTART diagn o stic pro gram ), 990 SMI (System Man agem en t In terrupt), 89 486SL CPUs, 97 SMM (System Man agem en t Mo de), 47 486SL CPUs, 97 Pen tiu m CPUs, 106-108 p ower con servation , en ergy u se an d battery life, 97 SMTP, 708 sn ap-to geth er cases, 1004 sn o w CGA (Color Grap h ics Ad ap ter), 515 d isp lays, 515 So cket Services (PC Cards), 935 so cketed ch ips, reseatin g, 1019-1020 m em ory SIPPs, 1019 so ckets CPUs, 54, 57, 182-183 OverDrive (Socket 1), 57-58 Slot 1, 67-71 Socket 1, 57, 182 Socket 2, 59-61 Socket 3, 61 Socket 4, 62 Socket 5, 63 Socket 6, 63 Socket 7, 64, 200, 532 Socket 8, 65, 200 sp ecification s, 182 ZIF, 67 LIF (Low In sertion Force), 1001 OverDrive, secon d ary, 102 recom m en d ation s, 293 ZIF, 53 so ft erro r rates, 344 so ft fo n ts, 880 so ft m em o ry erro rs, 312, 344-346 alp h a-p articles, 344-345 cosm ic rays, 345

ECC, 351-352 fau lt toleran ce, 346 p arity ch eckin g, 347-351 so ft po w er, 401 so ft pro blem s, 770 so ft-o ff feature (po w er supply), 393 so ftw are 32-bit Pen tiu m Pro/ II CPU op tim ization ), 130 virtu al real m od e su p p ort, 46 an ti-viru s, 1024 backu p , see backu p s backward com p atibility, 18 bu n d led sou n d card bu yin g tip s, 571 tap e backu p s, 821-822 clien t, 680 com p atability, tap e d rives, 817-818 d evelop m en t (PC 9x sp ecification s), 21 d iagn ostic, 983, 989-991 #1-Tu ffTEST, 994 afterm arket, 984 AMIDiag, 992 Ch eckit Pro, 992 Disp layMate, 548 m an u factu rer-su p p lied , 984 Micro-Scop e, 993 n etwork in terfaces, 990-991 Norton Utilities, 993-994 op eratin g system s, 984, 995-998 PC Tech n ician , 994 PC-Diagn osys, 994 p erip h erals, 984 POST (Power-On Self Test), 984-989 QAPlu s/ FE, 994-995 SCSI d evices, 989-990 testin g CPUs, 77 ven d ors, 1238 d iagn ostics (IBM), 989 d irect cable con n ection s, 677 d irect h ard ware access (ROM BIOS), 1035 d rivers bu ild in g system s, 968 op tical d rives, 863-865 sou n d card , 570 vid eo, 533-535

1515

IBM, d u p licatin g, 17-18 in d u stry con trol, 16-17 LLF IDE, 768 SCSI, 767 m an u factu rers, 1243-1244 MIDI, 556 m ou se d rivers, trou blesh ootin g, 489-490 MS-DOS ap p lication s (m ou se p roblem s), 490 licen sin g, 17-18 n etwork (ven d ors), 1242 op eratin g system s (bu ild in g system s), 968 PC Card s, 935 Card Services, 936 en ablers, 936-937 Socket Services, 935 record in g, CD-R (CDRecord able) d rives, 848-849 reverse en gin eerin g, 17 storage n eed s (CD-ROMs), 828 testin g (Disp layMate), 548 th ird -p arty, 821 voice com m an d (h an d icap p ed u sers), 559 voice d ictation , 559-560 so lder sucker, 1006 so lderin g to o ls, 1005-1007 so lid in kjet prin ters, 892 SORT.E XE (Win do w s 9x DOS), 1416 so rtin g files (h ard disk m ain ten an ce), 1023 so un d, 562 am p litu d e (in ten sity), 563 d b (d ecibels), 563 files (AVI), 557 p itch , 562 So un d Blaster, 550, 563 AW E32, 569 com p atibility, 571 con flicts (d efau lt resou rce assign m en ts), 575 d au gh ter card s (W ave Blaster), 568 m icrop h on es, 550 MIDI su p p ort, 550 so un d cards 8-bit au d io, 564 16-bit au d io, 565 Ad LiB, 550 ap p lication s, 549 MIDI su p p ort, 550

1516

sound cards

au d io CDs, p layin g, 560 basics of sou n d , 562 am p litu d e, 563 d b (d ecibels), 563 p itch , 562 bu sin ess ap p lication s, 556-557, 561 cost, 561 n oise, 562 p rod u ctivity, 562 tu torials, 557 bu yin g tip s bu n d led software, 571 Sou n d Blaster com p atibility, 571 u ser n eed s, 570-571 con feren cin g, 560 con n ectors, 565 CD-ROM, 569-570 in tern al p in -typ e, 567 joystick, 567 lin e in , 566 lin e ou t, 566 m icrop h on e, 566 MIDI, 567 sp eaker/ h ead p h on e, 566 d ata com p ression , 568 ADPCM (Ad ap tive Differen tial Pu lse Cod e Mod u lation , 569 MPEG (Motion Pictu res Exp ert Grou p s), 569 d rivers, 570 DSPs (Digital Sign al Processors), 569 freq u en cy resp on se, 563 Gam e Blaster, 549 gam e com p atibility, 549 gam in g (p orts), 551 in stallin g, 571 CD Au d io In con n ector, 572 con n ectin g sp eakers, 572 in sertin g in to slot, 572 p atch in g in to stereo system s, 573-574 settin g ju m p ers or DIP switch es, 572 m arket d om in an ce, 550 m icrop h on es, 581 m u ltim ed ia, 551-552 p orts (MIDI), 555 p roofread in g, 560 record in g, 557-558 Sou n d Record er, 557 voice an n otation s, 558 sam p lin g, 564

Sou n d Blaster, 550 em u lation (com p etitiors), 550 m icrop h on es, 550 MIDI su p p ort, 550 sou n d files MIDI files, 553-556 m ixin g software, 561 resolu tion s, 553 sp eakers, 579-581 am p lification , 579 batteries, 580 DBB switch (d yn am ic bass boost), 580 freq u en cy resp on se, 580 THD (Total Harm on ic Distortion ), 580 wattage, 580 stan d ard s, 550 gam in g, 563 syn th esis (stereo versu s m on o), 568 ch ip s, 568 W ave Blaster, 568 total h arm on ic d istortion , 563 trou blesh ootin g, 287-289, 574 Ch ip set Setu p Op tion s, 579 d evice con flicts, 574-576 joystick p roblem s, 578-579 locku p s, 578 low volu m e, 577 n o sou n d , 576-577 on e-sid ed sou n d , 577 p arity errors, 578 scratch y sou n d , 578 voice recogn ition , 559 volu m e con trols, 567 So un d Reco rder, 558 W in d ows 9x, 557 So un ds Co n tro l Pan el (Win do w 9x ), 557 So uth Bridge ch ipsets, 186, 188-189 430NX, 190 m obile Pen tiu m ch ip sets, 929 Pen tiu m II, 200-202 Alad d in Pro II, 205-206 Ap ollo Pro, 206 Pen tiu m Pro, 200-202 440FX, 203 Alad d in Pro II, 205-206 Ap ollo Pro, 206

spare secto rs, 1079 Sparq drives (m ax im um ro o t directo ry), 802, 1074 sp ecification s, 802 rem ovable d rives, com p arin g, 802-804 speakers, 566, 579-581, 966 am p lification , 579 batteries, 580 con n ectors, 230 DBB switch (d yn am ic bass boost), 580 freq u en cy resp on se, 580 sou n d card con n ection s, 572 THD (Total Harm on ic Distortion ), 580 ven d ors, 1244 wattage, 580 SPECfp95 ben ch m ark, 165 specific en abler so ftw are (PC Cards), 937 specificatio n s AMD-K6 CPUs, 153-154 CD-ROM d rives, 829, 837-846 access tim es, 831-832 bu ffers, 832 d ata tran fer rates, 829-830 d rive sealin g, 837 extern al en closu re, 837 in tern al en closu re, 838 load in g m ech an ism s, 835-836 p h ysical in terface, 832-835 self-clean in g len ses, 837 CPUs, 31-32 ad d ress bu ses, 40-41 d ata bu s wid th , 38-39 in tern al (Level 1) cach e, 41-42 in tern al registers, 39-40 m od es, 43-46 secon d ary (Level 2) cach e, 41-43 sockets, 182 sp eed ratin gs, 33-37, 43 DVD (Digital Versatile Disc), 851-852 backward com p atibility, 852 cap acities, 852 flop p y d isk d rives, 778-779 track-wid th , 779

speeds

IBM PC d isk storage, 1107 en viron m en tal, 1108 exp an sion slots, 1108 keyboard s, 1108 m em ory, 1107 p h ysical, 1108 stan d ard featu res, 1107 system arch itectu re, 1106 IBM PC AT, 1140 d isk storage, 1142 en viron m en tal, 1144 exp an sion slots, 1144 keyboard s, 1144 m em ory, 1141 p h ysical, 1144 stan d ard featu res, 1142 system arch itectu re, 1140 IBM PC Con vertible, 1112 m oth erboard , 1113 IBM PC XT, 1120 d isk storage, 1122 en viron m en tal, 1123 exp an sion slots, 1122 keyboard s, 1122 m em ory, 1121 p h ysical sp ecification s, 1123 stan d ard featu res, 1121 system arch itectu re, 1121 IBM PC XT Mod el 286, 1148 d isk storage, 1149 en viron m en tal, 1150 exp an sion slots, 1150 keyboard s, 1150-1152 m em ory, 1148 op tion al accessories, 1152 p h ysical, 1150 stan d ard featu res, 1147-1149 system arch itectu re, 1148 IBM Portable PC d isk storage, 1128 en viron m en tal, 1128 exp an sion slots, 1128 keyboard s, 1128 m em ory, 1127 p h ysical, 1128 stan d ard featu res, 1127 system arch itectu re, 1127 IDT Cen tau r C6 W in ch ip , 127 m ath cop rocessors, 77 Pen tiu m CPUs, 105-106

Pen tiu m II CPUs, 143 233MHz MMX m odel, 144 266MHz MMX m odel, 144 300MHz MMX m odel, 144 333MHz MMX m odel, 143 350 an d 400 MHz MMX m od els, 143 Pen tiu m Pro CPUs, 132-133 150 MHz m od el, 133 166 MHz m od el, 133 180 MHz m od el, 133 200 MHz m od el, 133 200 MHz m odel with 1M in tegrated L2 cach e, 133 p ower su p p lies, 414-417 ratin gs, 412-414 see also, ratin gs;stan d ard s rem ovable storage d rives, 802-804 Sp arq d rives (m axim u m root d irectory), 802 XGA (eXten d ed Grap h ics Array), 521 SPECin t95 ben ch m ark, 165 speculative ex ecutio n (Dyn am ic Ex ecutio n ), 128 Speed Disk utility (No rto n Utilities), 1093 Speedisk (No rto n Utilities), 993 speeds 386DX CPUs, 88 486 CPUs, 93, 98 486DX CPUs, 95 8088 CPUs, 84 80286 CPUs, 85 Am 5x86(TM)-P75 CPU, 103 AMD K5 CPUs, 126 AMD-K6 CPUs, 155 bu ses, 233-234 CD-R (CD-Record able) d rives, 847 CD-ROM d ata tran sfer rates, 829-830 m u ltim ed ia, 830 u p grad e issu es, 830 CD-ROM record in g CLV (Con stan t Lin ear Velocity), 826 P-CAV, 826 CD-ROM specification s (h ard disk com parison s), 831 CLKMUL (Clock Mu ltip lier), 94

1517

CPUs, 33-34 AMD, 80 clock d ou blin g, 37 com p arin g system s, 36 Cyrix, 81 iCOMP 2.0 in d ex ratin gs, 35 in stru ction execu tion efficien cy, 34 m arkin g sch em es, 37 m axim u m safe sp eed s, 37, 161-162 MHz, 34 m obile Pen tiu m II, 919 m obile Pen tiu m s, 918-920 m oth erboard sp eed s, 35-36 overclockin g, 37, 53 p rin ters, 894-895 RAM ch ip s, 340 relative to cach e sp eed s, 43 relative to m oth erboard sp eed s, 43 relative to SIMM/ DIMM sp eed s, 43 cycle tim e com p arison s, 313 Cyrix 6x86/ 6x86MX, 157-158 Cyrix/ TI 486, 104 d ata tran sfer rates (CD-ROM d rives), 829 d ou blin g DX2/ OverDrive p rocessors, 99-101 DX4 p rocessors, 101 I/ O bu ses, 250-251 IBM PC AT, 1132 IBM PC XT Mod el 286, 1146 m ath cop rocessors, m axim u m , 76 m em ory, 312-314 BEDO RAM, 316 DDR (Dou ble Data Rate) SDRAM, 318-319 EDO RAM, 315-316 FPM DRAM, 314-315 SDRAM, 316-317 SIMMs an d DIMMs, 327 m od em (bau d vs. bp s), 660 m oth erboard s 66Mh z, 35-37, 43 100Mh z, 43 CPU clock d ou blin g, 37

1518

speeds

CPU overclockin g, 37 recom m en d ation s, 294 settin g, 36 Pen tiu m CPUs, 105, 112 clock m u ltip liers, 105 OverDrive p rocessors, 59 secon d gen eration , 110 Pen tiu m II CPUs, 141-144 Pen tiu m Pro CPUs, 134 150MHz m od el, 133 166MHz m od el, 133 180MHz m od el, 133 200MHz 1M L2 cach e m od el, 133 200MHz m od el, 133 Pen tiu m -MMX CPUs, 113 SCSI/ IDE com p arison s, 651 SDRAM, 317 serial p orts, 589-590 sp in sp eed s (h ard d isk d rives), 722 system bu s, 531 trip lin g, DX4 p rocessors, 101 SPGA (Staggered Pin Grid Array) CPU packagin g, 54, 183 Pen tiu m CPUs, 105, 110 spills (clean in g keyboards), 477 spin speeds, h ard disk drives, 722 spin dle m o to rs flop p y d isk d rives, 774-775 h ard d isk d rives, 751-752 Spin dle Syn ch ro n izatio n (SPSYNC) sign als, 617 spin dles, m ultiple drives (po rtable co m puters), 932 split po w er plan e design s, 72-73 split rail design , see dual plan e vo ltage spo o lin g (prin tin g), 883 SPS (Stan dby Po w er Supplies), 439 SPSYNC (Spin dle Syn ch ro n izatio n ) sign als, 617 sputtered m edia, see th in film m edia SQFP (Sm all Quad Flat Pack), 95 SRAM (Static RAM), 319-322 cost, 319 failu res, cosm ic ray, 345 L1 cach e (386 system s), 320 L2 secon d ary cach e, 958 m em ory u p grad es (p ortable com p u ters), 930

SSF Reflecto r, 1198 ST-506/ 412 in terface, 607-608 en cod in g sch em es, 608-609 ST-506/ 412 MFM co n tro llers, 728, 771 Stabilan t 22, 342, 1016-1017, 1193 Stabilan t 22a, 1017 clean in g keyswitch es, 456 stacked I/ O co n n ecto rs (ATX m o th erbo ards), 173 stackers (SIMMs), 328 stacks (LANs), 681 STACKS param eter (IRQs), 271 Staggered Pin Grid Array, see SPGA stam pin g CD-ROMs, 825 stan d-by m o de (m o n ito rs), 507 Stan dard Eth ern et cable, 694 stan dard in terface (ROM BIOS), 1034 stan dard m o de (Win do w s 3.x ), 1056 DSW AP.EXE, 1056 W SW AP.EXE, 1056 stan dards 100Mbp s Eth ern et, 704 56K m od em , 669 crosstalk, 669 K56flex, 669-670 V.90, 669 X2, 669-670 d ata-com p ression , 664 MNP 5, 664 V.42bis, 664-665 DVD (Digital Versatile Disc), 853 Divx, 853 DVD+RW (DVD Ph ase Ch an ge Rewritable), 854 DVD-R, 853 DVD-R/ W , 854 DVD-RAM, 853 writable d rives, 853 fax m od em , 666 Grou p III p rotocol, 667 Grou p IV p rotocol, 667 MIDI files (Gen eral MIDI stan d ard ), 554 m od em , 658 backward com p atibility, 659 Bell Labs, 658 Hayes-com p atibility, 660 ITU, 658 m od u lation , 660-663 p rop rietary, 659

m oth erboard s, 167 m u ltim ed ia, 551 MPC Level 1, 552 MPC Level 2, 552 MPC Level 3, 552 op en (TCP/ IP), 707 organ ization s, 1244 PC Card s, 932 APM su p p ort, 933 ATA stan d ard , 933 Card Bu s, 933 DMA su p p ort, 933 h ot-swap p able, 935-937 p in ou ts, 934 Pn P su p p ort, 933 th erm al ratin gs system , 933 Typ e I, 933 Typ e II, 933 Typ e III, 933 Typ e IV, 933 Zoom ed Vid eo in terface, 933 p rop rietary, 665 CSP (Com p u Com Sp eed Con trol), 666 DIS, 665 HST, 665 MNP, 665-666 V-series (Hayes), 666 sou n d card s, 550 gam in g, 563 Sou n d Blaster com p atibility, 571 Sou n d Blaster em u lation , 550 tap e d rives, 817 8m m tap e, 814 DAT, 812-814 DLT, 814-815 QIC, 807-812 Travan cartrid ge tap e, 815-816 vid eo ad ap ters, 513-514, 537-538 CGA (Color Grap h ics Ad ap ter), 515 EGA (En h an ced Grap h ics Ad ap ter), 515 MCGA (Mu ltiColor Grap h ics Array), 517 MDA (Mon och rom e Disp lay Ad ap ter), 514 PGA (Profession al Grap h ics Ad ap ter), 516 PS/ 2 Disp lay Ad ap ter 85114/ A, 516

storage

SVGA (Su p er VGA), 521-524 VGA (Vid eo Grap h ics Array), 517-519 XGA (eXten d ed Grap h ics Array), 519-521 XGA-2 (eXten d ed Grap h ics Array), 520 see also ratin gs;sp ecification s Stan dby Po w er Supplies, see SPS stan do ffs (m o un tin g m o th erbo ards), 973 Star 8010, 480 star to po lo gies, 696 start bits (m o dem s), 656-657 Start o n Dem an d, SCSI, co n figurin g, 643-644 start-stop com m un ication s, 656 START.EXE (Win do w s 9x DOS), 1416 startup drivers (ROM), 305 Static Co lum n Page Mo de m em o ry, 314 static electricity, 578 d isch argin g, in stallin g sou n d card s, 572 p assive p reven tive m ain ten an ce, 1027-1028 Static m em o ry (IBM PC Co n vertible), 1110 Static RAM, see SRAM STD (Stan dard vo ltage ran ge), OverDrive steppin gs tables, 123 STD 3.3v vo ltage settin g (Pen tium CPUs), 72 stepper m o to rs, 741 flop p y d isk h ead actu ators, 774 steppin gs m obile CPUs Pen tiu m II, 923 Pen tiu m MMX, 922 Pen tiu m s, 920-921 Pen tiu m CPUs, 124 classic, 118-120 Mod el 1, 117 OverDrive p rocessors, 122-124 Pen tiu m II CPUs, 147-149 Pen tiu m Pro CPUs, 135-138 Pen tiu m -MMX CPUs, 121-124 stereo ph o n ic so un d cards, 568 sto p bits. 656-657

sto rage, 605-607 CD-ROM d rives, 28-29, 963 bootin g from , 963 CD-R (CD-Record able), 964 CD-RW (CD-Rewritable), 964 DVD-ROM d rives, 964 PD-ROM com bo d rives, 963 com p ared to m em ory, 301-302 DVD-ROM d rives, 28-29 en cod in g sch em es, 608-609 ESDI (En h an ced Sm all Device In terface), 609-610 flop p y d isk d rives, 28, 770-795 1.2 M 5 1/ 4-in ch , 786-787 1.44M 3 1-in ch , 783 2.88M 3 1-in ch , 784-787 3 1/ 2-in ch form at, 779-780 5 1/ 4-in ch form at, 779-780 360K 5 1/ 4-in ch , 787 720K 3 1/ 2-in ch , 785-786 align m en t, 794-795 cables, 777-778 circu it board s, 775 clu sters, 781 con n ectors, 776-778 con trollers, 775-776 cylin d ers, 781 d iskette ch an gelin e, 781-782 facep lates/ bezels, 776 h ead actu ator m ech an ism s, 774 IBM PC AT, 1130 IBM PC XT, 1115 in stallin g, 793 logical d isk form atted p aram eters, 783 m axim u m root d irectory, 1074 op eratin g system d isk u sage, 779 p h ysical op eration , 779 read / write h ead s, 771-774 rep airin g, 793-795 sp ecification s, 778-779 sp in d le m otors, 774-775 track-wid th sp ecification s, 779

1519

flop p y d isks m ed ia sp ecification s, 789-790 p h ysical con stru ction , 787-793 h ard d isk d rives, 28, 719-761, 962, 1022, 1352 ad van cem en ts, 719-720 air filters, 749-750 areal d en sity, 720-722 average access tim e, 756 average seek tim e, 756-759 backu p s, 1012-1013 cap acities, 759-761 con figu ration item s, 753-754 con troller h ead step rate, ch an gin g, 1140 costs, 759 d efragm en tin g files, 1022-1024 EIDE in terface, 962-963 facep late/ bezel, 753-754 FAT stru ctu res, 1065-1079 form attin g, 728-734, 767-770 grou n d in g tabs, 753 h ard d isk tem p eratu re acclim ation , 750-751 h ead actu ator m ech an ism s, 740-749 h ead slid ers, 739-740 h ead / m ed iu m in teraction an alogy, 722-724 IBM PC AT, 1130 IBM PC AT BIOS tables, 1136-1140 IBM PC XT Mod el 286, 1115, 1146 IDE p aram eters, 1401-1404 in stallin g, 761 in terface con n ectors, 753 logic board s, 752 m axim u m root d irectory, 1074 oxid e record in g m ed ia, 734 p aram eters, 1353-1413 p erform an ce, 755-759 p latters, 720, 732-734 p ortable com p u ters, 931 p ower con n ectors, 753 raw in terface p erform an ce, 757

1520

storage

read / write h ead s, 735-739 reliability, 755 rem ovable, 719 SCSI in terfaces, 761, 962-963 sectors, 724-728 server req u irem en ts, 687 sh ock m ou n tin g, 759 size con sid eration s, 962 sp in sp eed s, 722 sp in d le m otors, 751-752 th in -film , 734-735 track d en sities, 722 tran sfer rates, 756 trou blesh ootin g, 770 ven d ors, 1239 viru s ch eckin g, 1024 IBM PC, 1107 IBM PC AT, 1142 IBM PC XT 286 sp ecification s, 1122, 1149 IBM Portable PC (sp ecification s), 1128 IDE, see IDE Jaz d rives (m axim u m root d irectory), 1074 lon g file n am es (VFAT), 1080 LS-120 d rives (m axim u m root d irectory), 1074 m agn etic ARLL (Ad van ced Ru n Len gth Lim ited ), 715 cap acities, 718-719 com p arin g en cod in g sch em es, 716-717 d isk/ tap e m aterial, 710-719 en cod in g sch em es, 712-716 flu x, 710-719 m agn etic field s, 710-719 MFM (Mod ified Freq u en cy Mod u lation ), 711-719 PRML (Partial-Resp on se, Maxim u m -Likelih ood ), 718 read p rocesses, 712-719 read / write h ead s, 710-719 RLL (Ru n Len gth Lim ited ), 711-719 write p rocesses, 711-719 MIDI files, 553 op tical, 823 CD-ROMs, 823-850, 867-868 con figu rin g, 855-856

DVD (Digital Versatile Disc), 851-854 DVD-ROMs, 867 extern al con n ection s, 856-858 in stallin g d rives, 854, 862-866 in tern al con n ection s, 858-859 SCSI ch ain s, 860-861 ven d ors, 1242 p rin cip les of, 709-719 rem ovable cartrid ges, 799-802 CD-ROM d rives, 28 flop p y d isk d rives, 28, 931, 961 flop tical d rives, 797-804 Im ation LS-120, 962 Jaz d rives, 962 m akin g bootable, 1072 sp ecification s, 802-804 ven d ors, 1243 Zip d rives, 931, 961 SCSI, see SCSI software (CD-ROMs), 828 Sp arq d rives (m axim u m root d irectory), 1074 ST-506/ 412 in terface, 607-608 tap e d rives 8m m tap e, 814 backu p software, 820-821 cap acities, 817 cost, 818 DAT stan d ard s, 812-814 d ata th rou gh p u t, 818 DLT stan d ard s, 814-815 in stallin g, 819-820 p ortable, 818-819 QIC stan d ard s, 807-812 software com p atibility, 817-818 Travan cartrid ge tap e, 815-816 ven d ors, 1245 Zip d rives (m axim u m root d irectory), 1074 STP (sh ielded tw isted pair), 692-693 OverDrive step p in gs tables, 124 stream m o de (MNP Class 2), 666 strin gs, BIOS IDs, 210-213 stripin g, disk (NTFS), 1097

stuck keysw itch es, 469, 474 styles, fo n ts, 878 subdirecto ries, 1073 see also d irectories Subh eader field Mod e 2, Form 1 CD-ROMXA d ata typ e, 842 Mod e 2, Form 2 CD-ROMXA d ata typ e, 842 subm o del bytes IBM PC BIOS, 1105 IBM PC XT, 1119 subn o tebo o ks, 910 cost, 911 weigh t, 911 SUBST.EXE (Win do w s 9x DOS), 1416 substrate m aterial (m agn etic sto rage), 710 suffix po rtio n s, 725 Super Den sity CD stan dard, 851 Super High Speed Serial Po rts, 589-590 Super I/ O ch ips, 207-208, 960 UART com p arison s, 588 Super I/ O ex pan sio n bo ards, 960 Super VGA, see SVGA superscalar arch itecture m u ltip le registers, 40 Pen tiu m CPUs, 105 superscalar ex ecutio n , 47 supertw ist LCDs, 502-503 supplies, clean in g (ven do rs), 1244 Supra m o dem s, 1196 surge suppresso rs (po w er supplies), 437 MOVs (m etal-oxid e varistors), 437 p h on e lin e, 438 UL 1449 stan d ard , 437 suspen d m o des m on itors, 507 p ortable com p u ters, con servin g batteries, 941 suspen d/ resum e feature (486SL CPUs), 97 SVGA (Super VGA), 506, 521 con n ector p in ou ts, 522 resolu tion , 522 VESA stan d ard s, 523 65554 grap h ics accelerator ch ip set vid eo m od es, 523-524 color p alettes, 523

tape carrier packaging

sw abs, clean in g, 1018 sw appable drive bays (po rtable co m puters), 932 SWEDAC m o n ito r em issio n stan dard, 508 sw itch es Flash ROM BIOS, 217 in correct settin gs, in stallin g m em ory, 358 settin gs IBM PC m oth erboard s, 1108-1110, 1123-1124 IBM PC XT m oth erboard s, 1123-1124 IBM XT m oth erboard , 1108-1110 SPSs, 440 sw itch in g supply, 394 sym m etric m ultipro cessin g, see m ultipro cessin g Sym ph o n y, 1208 Syn ch ro n izatio n field Mod e 2, Form 1 CD-ROMXA d ata typ e, 842 Mod e 2, Form 2 CD-ROMXA d ata typ e, 842 Mod e1 CD-ROM-XA d ata typ e, 841 syn ch ro n o us cach e design s, 322 Syn ch ro n o us DRAM, see SDRAM Syn ch ro n o us Graph ics DRAM, see SGRAM syn ch ro n o us m ath co pro cesso rs (486 CPUs), 93 syn ch ro n o us n ego tiatio n (SCSI), 644 syn tax (CHKDSK co m m an d), 1089 d , 1089 / F (Fix) switch , 1089 / V (Verbose) switch , 1089 fragm en ted files, 1089 Syquest drives, 801 SYS co m m an d (DOS upgrade pro blem s), 1040-1041 SYS.COM (creatin g bo o t disks), 1036 SYS.EXE (Win do w s 9x DOS), 1416 SYSCHK diagn o stics pro gram , 1181 SYSm ark/ NT ben ch m ark, 165

system backups, 1012 tap e d rives, 1012-1013 writable CD-ROM d rives, 1012-1013 Zip / Jaz d rives, 1012-1013 system bo ards, see m o th erbo ards system buses, see buses system files (DOS), 1034-1035 COMMAND.COM, 1036 IBMBIO.COM (IBM DOS), 1035 IBMDOS.COM (IBM DOS), 1036 IO.SYS (MS-DOS), 1035 MSDOS.SYS (MS-DOS), 1036 System In fo rm atio n pro gram s (Win do w s 98), 998 system level do cum en tatio n , 1156-1159 m an u factu rer-sp ecific, 1163 System Man agem en t In terrupt, 89, 97 System Man agem en t Mo de, 47 System Mo n ito r (Win do w s 9x ), 997 system reso urces Pn P (Plu g an d Play), 290-291 BIOS, 291-292 h ard ware, 291 op eratin g system s, 292 trou blesh ootin g, 281, 290 con figu ration tem p lates, 283-287 m an u ally, 281-283 NICs, 289 SCSI ad ap ters, 289 serial p ort ad ap ters, 289-290 sou n d card s, 287-289 USB (Un iversal Serial Bu s), 290 system un its IBM PC, 1101 m oth erboard s (CPUs), 1100 System Wo rko ut, 1223 SYSTEM.DAT (Win do w s 9x Registry), 1059 System / 23 Datam aster, 11 system s assem blers (h ard ware in d u stry con trol), 19 bu ild in g, 947-948 assem bly, 968-979 au d io ad ap ters, 966

1521

cables, 967 cases, 949-950 CD-ROM d rives, 963 costs, 947 d isassem bly, 979-980 h ard d isk d rives, 962-963 h ard ware resou rce req u irem en ts, 968 h eat sin ks/ coolin g fan s, 966-967 IRQs, 968 keyboard s, 964 m oth erboard s, 950-961, 972-977 m ou se, 964 rem ovable storage, 961-962 ru n n in g CMOS Setu p , 978-979 scaven gin g from cu rren t system , 948 software su p p ort, 968 sp eakers, 966 su p p lies, 949-950 USB Perip h erals, 966 vid eo ad ap ters, 965 vid eo d isp lays, 965 com p on en ts p ower con su m p tion , 418-423 p ower m an agem en t, 423-425 recom m en d ation s, 292-297 resou rces, trou blesh ootin g (serial p ort ad ap ters), 289 SCSI, see SCSI ven d ors, 1244-1245 SyTOS tape-backup, 1224

T T-1 co n n ectio n s, 673 T-3 co n n ectio n s, 673 TAB (tape auto m ated bo n din g), 924 tactile feedback m ech an ism s (pure m ech an ical sw itch es), 455 tam perpro o f To rx (po w er supplies), 432, 1004 tape auto m ated bo n din g, see TAB tape carrier packagin g, see TCP

1522

tape drives

tape drives, 8m m tap e, 814 backu p software, 820-821 cap acities, 817 cost, 818 DAT stan d ard s, 812-814 d ata th rou gh p u t, 818 DLT stan d ard s, 814-815 in stallin g, 819-820 p ortable, 818-819 QIC stan d ard s, 807-812 early typ es, 810-811 h igh cap acity, 811 tap e com p atability, 811-812 software com p atibility, 817-818 stan d ard s, 817 Travan cartrid ge tap e, 815-816 ven d ors, 1245 tape reco rders (cassette), 222 TCO m o n ito r em issio n stan dard, 509 TCP (Tape Carrier Packagin g), 109 m obile CPUs, 923-928 TCP/ IP, 706-707 ARP, 707 FTP, 708 HTTP, 708 ICMP, 707 PPP, 708 SMTP, 708 UDP, 707 TCP/ IP-32 add-in , 1055 TCQAM (trellis co ded quadrature am plitude m o dulatio n ), 662 tech n ical suppo rt ap p en d ixes, 1166 d ocu m en tation , 1154-1155 ch ip an d ch ip set level, 1156, 1160-1162 com p on en t level, 1156 system level, 1156-1159, 1163 h an d s-on exp erien ce, 1165-1166 m agazin es, 1163-1164 on lin e resou rces, 1164 au th or’s e-m ail ad d ress, 1164 sem in ars, 1165 Teleph o n y co n n ecto rs, 231

televisio n con vertin g VGA sign als, 538 DTV (Desktop Vid eo), 540 cod ecs, 540-541 color p alettes, 540 d isk sp ace con su m p tion , 540 req u ired h ard ware, 542 stan d ard s, 537-538 tem perature co n tro l (passive preven tive m ain ten an ce), 1024-1025 tem plates (system reso urces co n figuratio n s), 283-287 term in al adpaters (ISDN), 672 NT-1, 672 term in ato rs con figu rin g, 642-643 extern al, 642 SCSI, 632-633, 639-640 active, 640 Forced Perfect Term in ation , 640 p assive, 640 terpen es clean ers, 1016 test leads (DMMs), 1008 testin g bootu p (op tical d rives), 865-866 cablin g, keyboard , 474 ch ip s (CPU m an u factu rin g), 52 CPUs, 77 d iagn ostic software, 983, 989-991 #1-Tu ffTEST, 994 afterm arket, 984 AMIDiag, 992 Ch eckit Pro, 992 m an u factu rer-su p p lied , 984 Micro-Scop e, 993 n etwork in terfaces, 990-991 Norton Utilities, 993-994 op eratin g system s, 984, 995-998 PC Tech n ician , 994 PC-Diagn osys, 994 p erip h erals, 984 POST (Power-On Self Test), 984-989 QAPlu s/ FE, 994-995 SCSI d evices, 989-990 eq u ip m en t, 1007-1011

flop p y d isk d rives (Drive Probe), 795 m on itors, bu yin g criteria, 513 Pen tiu m FPU bu g, 115-116 p ower su p p p lies, 430 load resistors, 430 variable voltage tran sform ers, 430-431 Tex as In strum en ts, FireWire (IEEE 1394) adapters, 605 tex t-to -speech utilities, pro o freadin g, 560 tex turin g (3D im age rasterizatio n ), 544-545 TFT (th in -film tran sisto r), see active-m atrix LCDs THD (To tal Harm o n ic Disto rtio n ) (speakers), 580 th erm al prin tin g (in kjet), 888 th erm al ratin gs system (PC Cards), 933 th erm al sh o ck, 421-422 th erm al w ax tran sfer prin ters, 893 Th in Eth ern et cable (BNC co n n ecto rs), 694 Th in Film read/ w rite h eads (h ard disk drives), 738 th in -film reco rdin g m edia (h ard disk drives), 734-735 th in -film sputtered m edia, 735 th in -film tran sisto rs, see active-m atrix LCDs Th in kPad, 479 Th in kPad 700, 492 Th in n et, see Th in Eth ern et cable Th ird Degree diagn o stic pro gram , 1204 th ird gen eratio n pro cesso rs, see 80386 CPUs th ird-party so ftw are, 991 #1-Tu ffTEST, 994 AMIDiag, 992 Ch eckit Pro, 992 Micro-Scop e, 993 Norton Utilities, 993-994 PC Tech n ician , 994 PC-Diagn osys, 994 QAPlu s/ FE, 994-995 tap e backu p d rives, 821 th ro ugh put, tape drives, 818 th um b screw s, 1004

trellis coded quadrature amplitude modulation

Tillam o o k, see m o bile Pen tium -MMX CPUs TIME co m m an d (Win do w s 9x DOS), 1415 tin -plated m em o ry co n tacts (co m pared to go ld-plated co n tacts), 340-344 TLB (Tran slatio n Lo o kaside Buffer), 108 to ken passin g, 701 To ken Rin g adapters, 689, 1235 beacon in g, 702 con n ectors, 690 Differen tial Man ch ester Data en cod in g, 692 early token release, 702 laten cy, 702 token p assin g, 701 To ken Rin g pro to co l, 701 to leran ce levels (m easurin g vo ltage), 430 to n er (laser prin ter prin tin g pro cess) ap p lication , 886-887 fu sin g, 887 to o ls clean in g, 1015 h an d ch ip extractors, 1001 ESD (electrostatic d isch arage) p rotection kit, 1003 files, 1003 flash ligh ts, 1003 h em ostats, 1003 n u t d rivers, 1001 p arts grabber, 1002 p liers, 1003 screwd rivers (m agn etic tip s), 1001 Torx d river, 1003 tweezers, 1002 vise, 1003 wire cu tter/ strip p er, 1003 m ain ten an ce, 999-1000 En glish an d m etric th read system s, 1005 h an d tools, 1000-1004 h ard ware typ es, 1004 sold erin g an d d esold erin g, 1005-1007 test eq u ip m en t, 1007-1011

to po lo gies FireW ire (IEEE 1394), 604 n etwork, 695 bu s, 696 logical rin gs, 697 rin gs, 697 star, 696 to ro idal ico n co re, 1029 to rque-co m pen satio n , auto m atic, 775 To rx driver, 1003 To rx screw s, 1004 tam p erp roof, 1004 To tal Harm o n ic Disto rtio n , see THD to tal in stalled m em o ry (co m pared to to tal usable m em o ry), 382-385 to uch pads (Glidepo in t po in tin g device), 495-496 to w er cases, 950 TPI (tracks per in ch ), 720 TR-1 m in i cartridges (Travan tape drives), 815-816 TR-2 m in i cartridges (Travan tape drives), 815-816 TR-3 m in i cartridges (Travan tape drives), 815-816 TR-4 m in i cartridges (Travan tape drives), 815-816 tracin g files (ro o t directo ries), 1074 track den sities (h ard disk drives), 722 track fo llo w in g system , 742 track-w idth specificatio n s (flo ppy disk drives), 779 trackballs, 480 p ortable com p u ters, 938 trackpads (po rtable co m puters), 938 TrackPo in t, 449, 479-480, 491-495 trackpo in ts (po rtable co m puters), 938 tracks CD-ROMs, 825 len gth s, DVD (Digital Versatile Disc), 852 tracks per in ch , see TPI tran sfer m eth o ds (DMA ch an n els), 276-277 tran sfer rates DRAM (d yn am ic RAM), 529 EISA bu ses, 247

1523

h ard d isk d rives, 756 p rocessor bu s, 237 SCSI, 630 tran sferrin g data, ATA-2/ ATA3 IDE (In tegrated Drive Electro n ics), 623-624 tran sfo rm ers, variable vo ltage (testin g po w er supplies), 430-431 tran sien t DOS co m m an ds, 1037 tran sien t respo n se, 416 tran sisto rs, 9 486DX CPUs, 95 DRAM, 312 failed active m atrix LCDs, 916 LCD costs, 503 p assive m atrix LCDs, 914 LCDs, 503 Pen tiu m CPUs, 105, 111 Pen tiu m II CPUs, 51, 141 233MHz MMX m od els, 144 266MHz MMX m od els, 144 333MHz MMX m od els, 143 350 an d 400 MHz MMX m od els, 143 Pen tiu m Pro CPUs, 130 150 MHz m od el, 133 166 MHz m od el, 133 180 MHz m od el, 133 200 MHz m od el, 133 200MHz 1M L2 cach e m od el, 133 Pen tiu m -MMX CPUs, 113 tran sitio n cells, 711 tran slatin g, see po rtin g Tran slatio n Lo o kaside Buffer, see TLB tran sm issio n m edia, tw isted pair cable (MIDI co n n ectivity), 556 Tran spo rt layer (OSI Referen ce Mo del), 683 Travan cartridge tape, 815-816 Travel Flo ppy 144, 1179 trays, CD-ROM lo adin g m ech an ism s, 836-837 TREE.EXE (Win do w s 95 CD-ROM), 1417 trellis co ded quadrature am plitude m o dulatio n , see TCQAM

1524

trichloroethane cleaner

trich lo ro eth an e clean er, 1016 trilo gram s (triple-key co m bin atio n s), 451 Trin itro n screen design , 501 triple-key co m bin atio n s, see trilo gram s triple-supertw ist LCDs (liquid crystal displays), 503 triplin g CPU speeds (DX4 pro cesso rs), 101 Trito n (430FX) ch ipset, 190-191 Trito n II (430HX) ch ipset, 191-192 Trito n III (430VX) ch ipset, 193 Trito n IV ch ipset (430TX) ch ipset, 193 tro ublesh o o tin g ad ap ter board m em ory con flicts, 386 AMI BIOS, 213 BIOS, 222-224 CMOS Ch ecksu m error, 219 Flash ROM, 220-221 CMOS RAM, 227-228 d iagn ostic software, 983, 989-991 #1-Tu ffTEST, 994 afterm arket, 984 AMIDiag, 992 Ch eckit Pro, 992 m an u factu rer-su p p lied , 984 Micro-Scop e, 993 n etwork in terfaces, 990-991 Norton Utilities, 993-994 op eratin g system s, 984, 995-998 PC Tech n ician , 994 PC-Diagn osys, 994 p erip h erals, 984 POST (Power-On Self Test), 984-989 QAPlu s/ FE, 994-995 SCSI d evices, 989-990 ven d ors, 1238 d isp lays, m on itors, 547-548 DOS u p grad es, 1040 DOS 4.0, 1041 DOS 5.0, 1041 DOS 6.x, 1041 SYS com m an d , 1040-1041 W in d ows 95, 1041

DVD-ROMs, 867 cap acity p roblem s, 868 clean in g d iscs, 867 clean in g read len ses, 868 W in d ows 9x p roblem s, 868 flop p y d isk d rives (Norton DiskTool), 1094 h ard d isk d rives, 770 NDIAGS, 1095 Norton Calibrate, 1094 Norton Disk Doctor, 1094 Norton Disk Ed itor, 1094 in form ation resou rces d ocu m en tation , 1154-1163 m agazin es, 1163-1164 on lin e resou rces, 1164 sem in ars, 1165 IRQs, 274-275 keyboard s, 474 cablin g, 474 clean in g, 477 con n ector sp ecification s, 474-475 d isassem bly p roced u res, 475-476 keyswitch es, 474 m oth erboard con n ectors, 474-475 POST errors, 474-475 rep lacin g, 478-479 scan cod e errors, 474 m ain ten an ce service ven d ors, 1243 m em ory con flicts, 380-381 in stallation , 354-359 m ou se, 487 clean in g, 487 DOS ap p lication p roblem s, 490 d rivers, 489-490 in terru p t con flicts, 487-488 OverDrive p rocessors (com p atiblity p roblem s), 163-164 p ower su p p lies, 426-427 DMMs (Digital Mu lti-Meters), 428-430 DVOMs (d igital VoltOh m Meters), 428 p reven tive m ain ten an ce, 1011 active, 1011-1024 clean in g system s, 1013-1022

h ard d isk d rives, 1022-1024 h arsh en viron m en t system s, 1030 op eratin g en viron m en ts, 1024 p assive, 1011, 1024-1030 p ower cyclin g, 1025-1027 p ower lin e n oise, 1028-1029 reseatin g socketed ch ip s, 1019-1020 RFI (rad io-freq u en cy in terferen ce), 1029-1030 static electricity, 1027-1028 system backu p s, 1012-1013 tem p eratu re con trol, 1024-1025 p rin ters, 903-904 application problem s, 908 con n ection , 906-907 d ot m atrix, 902-903 d rivers, 907 h ard ware, 904-906 in kjet, 902 laser, 902 p ap er selection , 903 p reven tive m ain ten an ce, 902 rep air service ven d ors, 1243 serial p orts, 591 loop back tests, 592-593 MSD (Microsoft Diagn ostics), 591-592 W in d ows 95/ 98, 592 software p roblem s (32-bit d isk access), 1058 sou n d card s, 574 Ch ip set Setu p Op tion s, 579 com p u ter won ’t start, 578 d evice con flicts, 574-576 joystick p roblem s, 578-579 locku p s, 578 low volu m e, 577 n o sou n d , 576-577 on e-sid ed sou n d , 577 p arity errors, 578 scratch sou n d , 578 system resou rces, 281, 290 con figu ration tem p lates, 283-287 m an u ally, 281-283

upgrading

NICs, 289 SCSI ad ap ters, 289 serial p ort ad ap ters, 289-290 sou n d card s, 287-289 USB (Un iversal Serial Bu s), 290 system resou rcs (serial p ort ad ap ters), 289 tools, 999-1000 En glish an d m etric th read system s, 1005 h an d tools, 1000-1004 h ard ware typ es, 1004 sold erin g an d d esold erin g, 1005-1007 test eq u ip m en t, 1007-1011 vid eo ad ap ters, 546-547 W eb site resou rces, 1247-1249 see also d iagn ostic software; m ain ten an ce; p roblem s true co lo r (16.8 m illio n ), m em o ry requirem en ts, 529 true stan dard fo rm facto rs (m o th erbo ards), 167 True Type fo n ts, 881 tun ers (CATV n etw o rks), 674 tun n el erasure (flo ppy disk drives), 773 turn in g o n / o ff (po w er supplies), 421-423 tuto rials (m ultim edia applicatio n s), 557 TV-o ut co n n ectio n s, 943-944 Tw eek, see Stabilan t 22a tw eezers, 1002 tw isted pair cablin g LANs, 692 grou n d in g loop s, 693 STP (sh ield ed twisted p air), 692-693 UTP (u n sh ield ed twisted p air), 693 MIDI con n ectivity, 556 tw o -w ay set asso ciative cach e (Pen tium Pro CPUs), 130 TYPE co m m an d (Win do w s 9x DOS), 1415 Type I PC Cards, 933 Type II PC Cards, 933 Type III PC Cards, 933 Type IV PC Cards, 933 typefaces d efin ed , 878 m on osp aced , 879

p oin ts, 879 p rop ortion al, 879 san s serif, 879 serif, 879 see also fon ts typem atic fun ctio n s (keybo ards), 459 ad ju stin g in DOS, 460-461 ad ju stin g in W in d ows, 459-460 typestyles, 878

U U-In terface (ISDN h ardw are), 672 u-pipe (Pen tium data pipelin es), 106 see also d ata, p ip elin es; p ip elin es UART ch ips (Un iversal Asyn ch ro n o us Receiver/ Tran sm itter), 587-589 serial-p ort (PC/ XT an d AT d ifferen ces), 25 UDP, 707 UL 1449 stan dard (surge suppresso rs), 437 Ultra-SCSI, 632, 629 ultravio let ligh t (electro m agn etic spectrum ), 1344 UMA (Upper Mem o ry Area), 359-362, 763, 988, 1104 ad ap ter ROM, 369 h ard d rive an d SCSI con troller BIOS, 370-372 n etwork ad ap ter card s, 372-374 vid eo ad ap ter BIOS, 369-370 lin ear ad d resses, 362-364 m oth erboard BIOS, 375-376 segm en t ad d resses, 362-364 vid eo RAM, 364-365 Color Grap h ics Ad ap ter (CGA), 366 En h an ced Grap h ics Ad ap ter (EGA), 366 Mon och rom e Disp lay Ad ap ter (MDA), 365 Vid eo Grap h ics Array (VGA), 366-369 UMB (Upper Mem o ry Blo ck), 489

1525

UNDELETE.E XE (Win do w s 95 CD-ROM), 1417 UNFORMAT co m m an d (retired fo r Win do w s 9x ), 1418 un idirectio n al parallel po rts, 594-595 UNIDRV.DLL (Win do w s 3.11 updates), 1054 Un in terruptible Po w er Supplies (UPSs), 439-441, 1242 un ique o peratio n m o des (XGA adapters), 520 Un iversal Periph eral In terface (UPI), 458 un iversal po w er supplies (o utput ratin gs), 414 Un iversal Serial Bus, see USB UNLOCK co m m an d (Win do w s 9x DOS), 1415 un sh ielded h eader co n n ecto rs (sin gle-en ded SCSI), 635 un sh ielded pin h eader co n n ecto r (SCSI), 634 un sh ielded tw isted pair, see UTP updates (CPU w o rk-aro un ds), 78 upgradin g 486 CPUs, 95 ATX m oth erboard s, 173 backp lan e system s, 181 BIOS (Basic In p u t Ou tp u t System ), 215-216 Flash ROM, 217-219 keyboard con trollers, 216-217 vid eo, 525-526 CPUs, 161 ben ch m arks, 164-165 DX2/ OverDrive p rocessors, 99-101 DX4 p rocessors, 101 m axim u m sp eed s, 161-162 OverDrive p rocessors, 162-164 Pen tiu m OverDrives, 101 secon d ary OverDrive Sockets, 102 ven d ors, 1243 DOS (Disk Op eratin g System ), 1040 DOS 4.0, 1041 DOS 5.0, 1041 DOS 6.x, 1041

1526

upgrading

SYS com m an d , 1040-1041 W in d ows 95, 1041 h ard d isk d rives (p ortable com p u ters), 931 IBM PCs (BIOS), 1104 m em ory, 352 op tion s for, 352-353 p ortable com p u ters, 930 rep lacin g for cap acity, 353-354 selectin g ch ip s, 353 with ad ap ter board s, 354 Pen tiu m CPUs (OverDrive p rocessors), 110, 113, 122-123 Pen tiu m -MMX CPUs 321-p in p rocessors sockets, 114 ju m p erin g for 60/ 66MHz op eration , 114 OverDrive p rocessors, 122-123 p ortable com p u ters, 912 com p atibility, 912 fin d in g com p on en ts, 913 rep lacin g com p on en ts, 912 p rop rietary m oth erboard s, 179-180 vid eo m em ory (d au gh ter card s), 529 UPI (Un iversal Periph eral In terface), 458 upper m em o ry ad ap ter board s, 385 d eterm in in g con figu ration of, 385-386 op tim izin g, 386-387 p reven tin g con flicts, 386 m an agem en t p rogram s, 387-388 EMM386.EXE, 388 HIMEM.SYS, 388 MEMMAKER, 388-390 Upper Mem o ry Area, see UMA Upper Mem o ry Blo ck, see UMB UPSs (Un in terruptible Po w er Supplies), 439-441 ven d ors, 1242 usable m em o ry co m pared to to tal in stalled m em o ry, 382-385

USB (Un iversal Serial Bus), 186, 290, 600-604, 966 m ou se in terfaces, 484 p erip h erals, 966 User Data field (Mo de 2, Fo rm 1 CD-ROM-XA data type), 842 user m o de (Win do w s NT), 1064 USER.DAT (Win do w s 9x Registry), 1059 USER.EXE W in d ows 3.1 u p d ates, 1054 W in d ows 3.x core files, 1056 users h an d icap p ed (voice com m an d software), 559 m ou se (left-h an d ed ), 485 sou n d card s (bu yin g tip s), 570-571 utilities Disk Man ager, 619 FAT, 1088 CHKDSK com m an d , 1088-1091 Disk Defragm en tation (W in d ows 95), 1093 NDIAGS, 1095 Norton Calibrate, 1094 Norton Disk Doctor, 1094 RECOVER com m an d , 1091 SCANDISK com m an d , 1091-1092 Sp eed Disk (Norton Utilities), 1093 flop p y d isk (Norton DiskTool), 1094 MEMMAKER, 387-390 Parallel, 597 UTP (un sh ielded tw isted pair), 693 Category 3, 698 UVGA (Ultra VGA), 506

V / V (Verbo se) sw itch (CHKDSK co m m an d syn tax ), 1089 v-pipe (Pen tium data pipelin es), 106 see also d ata, p ip elin es; p ip elin es V.21 stan dard, 662 V.22 stan dard, 662

V.23 stan dard, 662 V.29 stan dard, 662 V.32 stan dard, 662 V.32fast stan dard, 663 V.34 stan dard, 663 V.42 erro r co rrectio n pro to co l (LAPM), 664 V.42bis data co m pressio n stan dard, 664-665 V.90 56K stan dard, 669 V.90 stan dard, 663 V32.bis stan dard, 663 vacan cies, see OverDrive so ckets vacuum clean ers, 1017 VAFC (VESA Advan ced Feature Co n n ecto r), 536 values, parity (m o dem co n n ectio n s), 657 vam pire taps (co ax ial cable), 694 variable frequen cy syn th esizer, 36 variable prin t den sity, 904 variable vo ltage tran sfo rm ers (testin g po w er supplies), 430-431 VBS (Vo lum e Bo o t Secto r), 731 VCACHE m o de (Win do w s 95 VFAT), 757-758, 1079, 1201 VCP (Tape Carrier Package), OverDrive steppin gs tables, 123 VCRs (video capture fro m ), 538 vecto r graph ics, 875 Ven tura Publish er, 1235 VER co m m an d (Win do w s 9x DOS), 1415 VERIFY co m m an d (Win do w s 9x DOS), 1415 versio n s, 1039 DOS (Disk Op eratin g System ) MS-DOS 5.x, 1039 MS-DOS 6.0, 1040 MS-DOS 6.2, 1040 MS-DOS 6.21, 1040 MS-DOS 6.22, 1040 DOS 5.x, 1039 PCL (Prin ter Con trol Lan gu age), 874 Pen tiu m CPUs, 117, 124 classic, 118-120 Mod el 1, 117 OverDrive p rocessors, 122-124

video

Pen tiu m II CPUs, 147-149 Pen tiu m Pro CPUs, 135-138 Pen tiu m -MMX CPUs, 121-124 W in d ows 3.x W in d ows 3.1, 1054 W in d ows 3.11, 1055 W in d ows for W orkgrou p s, 1055 W in d ows NT, 1063 vertical frequen cies, m o n ito rs (buyin g criteria), 510 see also refresh rates vertical reco rdin g, 784 vertices (3D im ages), 544 Very Large Scale In tegratio n (VLSI), 88 Very Lo n g In structio n Wo rds (VLIW), 160 very lo w frequen cy (VLF), 508 VESA (Video Electro n ics Stan dards Asso ciatio n ), 252-256 486 CPU d ep en d en ce, 253 card lim itation s, 253 DPMS (Disp lay PowerMan agem en t Sign alin g), 507-508 electrical lim itation s, 253 p in ou ts, 255 sp eed lim itation s, 253 SVGA stan d ard s, 523 65554 grap h ics accelerator ch ip set vid eo m od es, 523-524 color p alettes, 523 VESA Advan ced Feature Co n n ecto r, see VAFC VESA Media Ch an n el, 536 VFAT (Virtual File Allo catio n Table), 1079 backward com p atibility, 1079 lon g file n am es, 1079-1080 8.3 alias n am es, 1081 assign in g, 1080 backward com p atibility, 1081 LFNBK.EXE (W in d ows 9x), 1081 storin g, 1080-1081 VCACHE m od e, 1079 VFC (Video Feature Co n n ecto r), 536-537 VFW (Micro so ft Video fo r Win do w s), 541

VGA (Video Graph ics Array), 366-369, 506, 517-519 BIOS, 518 color su m m in g, 518 d isp lay m od es, 519 IBM PS/ 2 Disp lay Ad ap ter, 518 NTSC con verters, 538 p ossible colors, 517-518 PS/ 2 system s, 517 VFC (Vid eo Featu re Con n ector), 536-537 VHS sign als, video capture fro m , 538 VIA Tech n o lo gies ch ipsets Pen tiu m II Processors Ap ollo P6/ 97, 206 Ap ollo Pro, 206-207 Ap ollo p 6/ 97, 206 Pen tiu m p rocessors, 194 Ap ollo MVP3, 196-197 Ap ollo VP-1, 194 Ap ollo VP2, 195 Ap ollo VP3, 195-196 Ap ollo VPX, 195 VID (Vo ltage Iden tificatio n ) pin s, Pen tium Pro CPUs, 135 video , 499 3D grap h ics accelerators, 543 ch ip sets, 543-545 cost, 544 im age abstraction s, 544 ren d erin g im ages, 543 ad ap ters, 499, 513, 535, 965 ATX m oth erboard con n ection s, 500 Baby-AT m oth erboard con n ection s, 500 BIOS, 369-370, 525-526 bu ses, 531-533 cap tu re board s, 537-538 CGA (Color Grap h ics Ad ap ter), 515 ch ip sets, 526 Cyrix Med iaGX, 500 DACs (Digital-to-An alog Con verter), 531 d rivers, 533-535 DTV (Desktop Vid eo board s), 540-542 EGA (En h an ced Grap h ics Ad ap ter), 515 in tegrated , 961 MCGA (Mu ltiColor Grap h ics Array), 517

1527

MDA (Mon och rom e Disp lay Ad ap ter), 514 m em ory, 527-531 MPEG com p ression , 537 m u ltip le m on itor, con n ectin g, 539 ou tp u t d evices, 537-538 PGA (Profession al Grap h ics Ad ap ter), 516 PS/ 2 Disp lay Ad ap ter 8514/ A, 516 stan d ard s, 513-514 SVGA (Su p er VGA), 521-524 trou lbesh ootin g, 546-547 VFC (Vid eo Featu re Con n ector), 536-537 VGA (Vid eo Grap h ics Array), 517-519 XGA (eXten d ed Grap h ics Array), 519-521 XGA-2 (eXten d ed Grap h ics Array), 520 AVI files, 557 cap tu re board s, 538 d isp lays, 965 card s, 29 DV (d igital vid eo), FireW ire (IEEE 1394), 605 m on itors, 499-500 actu al viewin g areas, 504-505 bu yin g criteria, 509-513 color, 503-504 CRTs (cath od e ray tu bes), 500 cu rved p h osp h or-based screen s, 501 d ot p itch , 506 en ergy-savin g featu res, 507-509 flat p h osp h or-based screen s, 501 gas p lasm a d isp lays, 503 in p u t sou rces, 500 in terlaced , 506-507 LCDs (liq u id crystal d isp lays), 501-503 m on och rom e, 503-504 m u ltip le-freq u en cy, 501 n on in terlaced , 506-507 refresh rates, 500-501 resolu tion , 505-506 sizes, 504 RAM (ven d ors), 1240

1528

Video Electronics Standards Association

Video Electro n ics Stan dards Asso ciatio n , see VESA lo cal bus Video Feature Co n n ecto r (VFC), 536-537 Video Graph ics Array, see VGA video RAM, see VRAM Viper m o th erbo ard ch ipsets, 1217 Virtual File Allo catio n Table, see VFAT Virtual Mach in e Man ager (Win do w s 9x ), 1060 virtual m em o ry Pen tiu m II CPUs, 143 Pen tiu m Pro CPUs, 132 Virtual Mem o ry Man ager (Win do w s NT Ex ecutive), 1064 virtual real m o de o peratio n 32-bit CPUs, 45 DOS exten d ers, 46 m em ory access lim its, 45 software su p p ort, 46 486DX CPUs, 97 80386 CPUs, 87 p rocessors, 376 virtual screen arran gem en ts (LCDs), 917 viruses ch eckin g (h ard d isk d rives), 1024 in fectin g m aster p artition boot sector, 1068 vise, 1003 visible surface determ in atio n (3D im age rasterizatio n ), 545 visual erro r co des (POST), 988 VL (VESA lo cal) bus, see VESA VLF (very lo w frequen cy), 508 VLIW (Very Lo n g In structio n Wo rds), 160 VLo ck, 1201 VLSI (Very Large Scale In tegratio n ), 88 VMC (VESA Media Ch an n el), 536 vo ice an n o tato n s, reco rdin g, 558 vo ice co il actuato rs, 741-743 lin ear, 742 rotary, 743 vo ice co m m an d so ftw are (h an dicapped users), 559 vo ice dictatio n so ftw are, 559-560

vo ice grade cablin g, 698 voice recogn ition (soun d cards) voice an n otation s, 559 voice com m an d software, 559 voice d ictation software, 559-560 vo ices (stereo ph o n ic so un d cards), 568 VOL co m m an d (Win do w s 9x DOS), 1415 vo latile sto rage, 302 VOLDET pin (Am 5x 86(TM)P75 CPU), 104 vo ltages, 391 1.8v m obile Pen tiu m step p in g, 124 2.0v m obile Pen tiu m step p in g, 124 2.2v m obile Pen tiu m step p in g, 124 2.285v m obile Pen tiu m step p in g, 123 3.3v voltage settin g (Pen tiu m CPUs), 72, 391-392 OverDrive p rocessors, 60 VR (voltage red u ced ), 72 3.5v voltage settin g (Pen tiu m CPUs), 72 5v voltage settin g (Pen tiu m CPUs), 72 Am 5x86(TM)-P75 CPU, 103-104 AMD K5 CPUs, 126 AMD-K6 CPUs, 155 con stan t, 394 core, sp lit rail p rocessor, 72 CPUs, 72-74 m obile Pen tiu m II, 919 m obile Pen tiu m s, 918-920 h old u p tim e, 415 I/ O voltage, sp lit rail p rocessor, 72 in p u t ran ge, 415 lin e regu lation , 416 load regu lation , 416 m axim u m load cu rren t, 416 m easu rin g (DMMs), 429-430 m in im u m load cu rren t, 416 m obile Pen tiu m CPU m od u les, 927 n om in al, 108 oversh oot, 416 overvoltage p rotection , 416

Pen tiu m CPUs, 65, 72, 106, 125 +5v, 72 3.3v, 72 3.5v, 72 OverDrive p rocessors, 125 p ortable com p u ters, 72 Pen tiu m II CPUs, 65 333MHz MMX m od els, 143 350 an d 400 MHz MMX m od els, 143 ID d efin ition s, 150-151 Pen tiu m Pro CPUs, 65, 132, 135 Pen tiu m -MMX CPUs, 65, 113, 125 d u al-p lan e, 73 rip p le, 417 testin g ou tp u t, 428-429 tran sien t resp on se, 416 VR (Voltage Red u ced ), 65 OverDrive step p in gs tables, 123 VR 3.3v voltage settin g (Pen tiu m CPUs), 72 VRAM (Vid eo RAM), 530 XGA an d XGA-2 ad ap ters, 520 VRE (Voltage Red u ced an d Exten d ed ), 65 3.5v voltage settin g (Pen tiu m CPUs), 72 step p in gs tables, 123 VRM (Voltage Regu lator Mod u le), 64, 183 Pen tiu m -MMX CPUs, 114 VRT (Voltage Red u ction Tech n ology) m obile CPUs, 918-919 step p in gs tables, 123 see also electricity Vo ltage Iden tificatio n s, see VID Vo ltage Reductio n Tech n o lo gy, see VRT Vo ltage Regulato r Mo dule, see VRM vo ltm eters, 1007 vo lum e (so un d cards) con trols, 567 trou blesh ootin g, 577 vo lum e bo o t co de (vo lum e bo o t secto rs), 1071 Vo lum e Bo o t Secto r (VBS), 731

Windows 95

vo lum e bo o t secto rs, 1071-1072 DBR (DOS Boot Record ) form at, 1072-1073 d isk p aram eter blocks, 1071-1072 FORMAT com m an d , 1072 load in g, 1071 selectin g boot d rives, 1071 volu m e boot cod e, 1071 Vo lum e o f Table o f Co n ten ts (VTOC), 840 vo lum es, see partitio n s Vo o do o graph ics accelerato rs, 1178 VOPT, 1201 VQ, 1201 VR (Vo ltage Reduced), 65 OverDrive step p in gs tables, 123 VR 3.3v vo ltage settin g (Pen tium CPUs), 72 VRAM (Video RAM), 530 XGA an d XGA-2 ad ap ters, 520 VRE (Vo ltage Reduced an d Ex ten ded), 65 3.5v voltage settin g (Pen tiu m CPUs), 72 step p in gs tables, 123 VRM (Vo ltage Regulato r Mo dule), 64, 183 Pen tiu m -MMX CPUs, 114 VRT (Vo ltage Reductio n Tech n o lo gy) m obile CPUs, 918-919 step p in gs tables, 123 VSAFE co m m an d (retired fo r Win do w s 9x ), 1418 vt82c680 Apo llo p6/ 97 ch ipsets, 206 VTOC (Vo lum e Table o f Co n ten ts), 840

W w afers CPU m an u factu rin g (yield s), 52 m an u factu rin g CPUs, 51 w ait states, 314, 320 CPU sp eed s, 34 Wake o n LAN co n n ecto rs, 231 Wake o n Rin g co n n ecto rs, 231 Wan dDAT tape backup drives, 1230

Wan gtech tape backup drives, 1230 w arm bo o ts, 1044 w arn in g (po w er supplies), 426 w attage (speakers), 580 WAV files record in g, 557 voice an n otation s, 558 Wave Blaster, 568 w avefo rm audio (so un d cards), 564 w avetable so un d cards (Wave Blaster), 568 w avetable syn th esis (playin g MIDI files), 555 w ax jet prin tin g, 892 w ear levelin g, 745 w edge servo m ech an ism s, 745-746 w eigh t lap top s, 910 n otebooks, 910 su bn otebooks, 911 Weitek m ath co pro cesso rs, 90 w h at yo u see is w h at yo u get (WYSIWYG), 505, 870 w h ite w ires (po w er sw itch co n n ecto rs), 407 Wide SCSI, 632 w idth ad d ress bu ses, 233-234 386SX CPUs, 39 8086 CPUs, 83 8088 CPUs, 39 Pen tiu m CPUs, 106 CPU sp ecification s, 31-32 ad d ress bu ses, 40-41 d ata bu s wid th , 38-39 in tern al registers, 39-40 DIMMs (Pen tiu m CPUs), 106 SIMMs (Pen tiu m CPUs), 106 Wildcat! BBS so ftw are, 1215 Willam ette, see Pen tium II CPUs, im pro ved Katm ai WIN keys (Win do w s keybo ards), 450 WIN.COM (lo adin g Win do w s 3.x ), 1055 Win Ben ch 98 ben ch m ark, 165 Win ch ester drives, 719 Win ch ip (IDT), 82, 126-127 Win do w RAM, see WRAM Win do w s drivers con figu rin g, 899-900 in stallin g, 898-899 p rin ter su p p ort, 897-900 Win do w s 3.1, 1054

1529

Win do w s 3.11, 1055 Win do w s 3.x , 1053-1054 32-bit d isk access, 1057 fastd isk, 1057 trou blesh ootin g software, 1058 CD-ROM d rives (p layin g au d io CDs), 866 core files, 1056 GDI.EXE, 1057 KRNL286.EXE, 1056 KRNL386.EXE, 1056 USER.EXE, 1056 Keyboard Con trol Pan el (in tern ation al layou ts), 469-470 load in g, 1055 386 en h an ced m od e, 1056 p rotected m od e, 1055 stan d ard m od e, 1056 W IN.COM, 1055 XMS m em ory, 1055 MSD (Microsoft Diagn ostics), 996 typ em atic fu n ction s (keyboard s), ad ju stin g, 459-460 W in d ows 3.1, 1054 W in d ows 3.11, 1055 W in d ows for W orkgrou p s, 1055 Win do w s 95 16-bit backward com p atibility, 45 DCC (Direct Cable Con n ection ), 599 Disk Defragm en tation u tility, 1093 DOS com m an d s on CD-ROM, 1417 DOS u p grad e p roblem s, 1041 OSR2, 1077, 1082-1086, 1091 OSR 2.1, 968 VFAT (Virtu al File Allocation Table), 1079 backward com p atibility, 1079 lon g file n am es, 1080-1081 VCACHE m od e, 1079 virtu al real m od e op eration , 45 DOS exten d ers, 46 m em ory access lim its, 45 software su p p ort, 46 see also W in d ows 98; W in d ows 9x

1530

Windows 98

Win do w s 98 Disp lay Con trol Pan el Ad ap ter p age, 534 Hard ware Acceleration slid er, 534-535 vid eo d rivers, 534 d isp lays (m u ltip le m on itor con n ection s), 539 DOS com m an d s on CD-ROM, 1417 FAT32 file system , 1060 Main ten an ce W izard , 1024 System In form ation p rogram , 998 vid eo d rivers, con figu rin g, 534-535 see also W in d ows 95; W in d ows 9x Win do w s 9x , 1058 104-key keyboard s, 449 Ap p lication key, 450 ergon om ics, 451 layou t, 450 W IN keys, 450 W in d ows 95 key com bin ation s, 450-451 boot d isks, creatin g, 1036 CD-ROM d rives, 866 Au toPlay, 866 CD-Player, 867 trou blesh ootin g, 868 Con trol Pan el (m od em con n ection p referen ces), 658 d efragm en tin g files, 1023 Device Man ager, 996-997 DMA ch an n els, 997 IRQs, 997 d irect cable con n ection software, 677 DOS com m an d s extern al, 1415-1416 in tern al, 1414-1415 retired , 1417-1418 DOS com p arison s, 1058 Registry, 1059 DOS win d ows (virtu al real m od e), 46 even t n otification s (assign in g sou n d s), 558 FAT32 file system , 1061 gam in g (sou n d card com p atibility), 563 Keyboard Con trol Pan el (in tern ation al layou ts), 469-470

Med ia Player ap p lication , 556 Mou se Con trol Pan el Bu tton s Page, 485 Gen eral Page, 486 Motion Page, 486 Poin ters Page, 486 MSD (Microsoft Diagn ostics), 996 Perform an ce Mon itor, 997 Pn P (Plu g an d Play), 1060 bu s en u m erators, 1060 resou rce arbitrators, 1061 p ortable com p u ters Card Services PC Card ad ap ters, 936 PC Card s, 937 Recycle Bin , 1049 Resou rce Meter, 997 SCANDISK.EXE (DOS), 1092 SCANDSKW .EXE (W in d ows), 1092 sh arin g p rin ters, 900-901 Sou n d Record er, 557-558 Sou n d s Con trol Pan el, 557 System Mon itor, 997 typ em atic fu n ction s (keyboard s), ad ju stin g, 459-460 version s OSR2 (OEM Service Release 2), 1060 W in d ows 98, 1060 Virtu al Mach in e Man ager, 1060 see also W in d ows 95; W in d ows 98 Win do w s Draw , 1212 Win do w s fo r Wo rkgro ups, 1055 NetBEUI p rotocol, 1055 TCP/ IP-32, 1055 Win do w s NT, 1062 boot p rocess, 1063 NTDETECT.COM, 1063 NTLDR, 1063 W in d ows NT Kern al (NTOSKRNL.EXE), 1063 Even t Viewer, 998 kern el, 1063 HAL (h ard ware abstraction layer), 1063 m od e, 1064 Keyboard Con trol Pan el (in tern ation al layou ts), 469-470

NTFS file system , 1062, 1095 clu ster rem ap p in g, 1097-1098 com p atibility, 1096-1097 d isk m irrorin g, 1097 d isk strip in g with p arity, 1097 lon g file n am es, 1095 MFT (Master File Table), 1096 p artition s, creatin g, 1097 Registry, 1062 sh arin g p rin ters, 900-901 typ em atic fu n ction s (keyboard s), ad ju stin g, 459460 u ser m od e, 1064 version s, 1063 W in dows NT Execu tive, 1064 I/ O Man ager, 1064 Local Proced u re Call facility, 1064 Object Man ager, 1064 Process Man ager, 1064 Secu rity Referen ce Mon itor, 1064 Virtu al Mem ory Man ager, 1064 Win do w s NT 4.0 CD-ROM d rives Au toPlay, 866 CD-Player, 867 p ortable com p u ters (PC Card s), 937 Win do w s NT Ex ecutive, 1064 I/ O Man ager, 1064 Local Proced u re Call facility, 1064 Object Man ager, 1064 Process Man ager, 1064 Secu rity Referen ce Mon itor, 1064 Virtu al Mem ory Man ager, 1064 Win Lyn x , 1224 Win pro be, 1222 Win sto n e 98 ben ch m ark, 165 Win tel system s (Micro so ft Win do w s an d In tel based), 20 w ire cutters/ strippers, 1003 w irin g ATA IDE (I/ O), 616 IDE (In tegrated Drive Electron ics), 612-613 lap top com p u ter lin ks, 599

Zoomed Video interface

loop back tests, 592-593 SCSI, 634 sin gle en d ed , 635-639 term in ators, 639-640 USB (Un iversal Serial Bu s), 602 Wo rdPerfect, 1235 Wo rdStar 7, 1230 w o rk-aro un ds (CPU updates), 78 w o rkstatio n s (LANs), 686 w o rldw ide po w er supplies, 414 WORM (w rite-o n ce, read m an y) CD-R (CD-Record able), 846 DVD d rives, 853 WRAM (Win do w RAM), 527 vid eo m em ory, 530 w rap plugs, see lo o pback co n n ecto rs w ritable CD-ROM drives, 846 CD-R (CD-Record able), 847-849 CD-RW (CD-Rewritable), 849-850 system backu p s, 1012-1013 W ORM (write-on ce, read m an y), 846-847 w ritable drives (DVD), 853 w rite Multiple co m m an d (ATA IDE), 618 w rite o n ce, read m an y, see WORM w rite preco m pen satio n (m an ual drive typin g), 766 w rite pro cesses (m agn etic sto rage), 711 WRITE TURN-ON GAP (h ard disk secto rs), 727

w rite-back cach e, 42, 886 Am 5x86(TM)-P75 CPU, 103 ju m p erin g, 104 Pen tiu m CPUs, 105, 108 Pen tiu m -MMX CPUs, 113 w rite-pro tect/ en able h o le, 789 w rite-pro tected Flash ROM BIOS, disablin g, 217 w rite-th ro ugh cach e 486 fam ily, 42 Am 5x86(TM)-P75 CPU, ju m p erin g, 104 Pen tiu m CPUs, 108 w rite-w h ite prin tin g, 886 WSWAP.EXE, 1056 WWW (Wo rld Wide Web), 1164 on lin e su p p ort resou rces, 1164 sites (AMI BIOS), 214 WYSIWYG (w h at yo u see is w h at yo u get), 505, 870

X X-rays (electro m agn etic spectrum ), 1344 X2 56K m o dem stan dard, 669-670 X3 (SCSI-2), 629-632 XCOPY.EXE (Win do w s 9x DOS), 1416 XCOPY32.EXE (Win do w s 9x DOS), 1416 Xeo n Pen tium II pro cesso rs, 152, 161 XGA (eXten ded Graph ics Array), 506, 519-520 m em ory req u irem en ts, 520 sp ecification s, 521

1531

u n iq u e op eration m od es, 520 VRAM (vid eo RAM), 520 XGA-2 (eXten ded Graph ics Array), 520 XMS (ex ten ded m em o ry specificatio n ), 359, 377 XpressGRAPHICS features (Cyrix MediaGX pro cesso r), 500 XT IDE drives, 613, 626 XT m o th erbo ards (Baby-AT in fluen ces), 168 XT-286, see Baby-AT m o th erbo ards

Y-Z Y splitter cables, 404 Year 2000 Fix , 1223 Yello w Bo o k specificatio n s (CD-ROM drives), 839 yields, ch ip (CPU m an ufacturin g), 52-53 ZIF (Zero In sertio n Fo rce) so ckets, 53, 67, 953 Ziff-David Win sto n e ben ch m ark, 82 Zip drives, 846, 961, 1205 d isk stru ctu res, 1066 m axim u m root d irectory, 1074 p ortable com p u ters, 931 system backu p s, 1012-1013 Zip It, 1222 zo n e reco rdin g ATA IDE, 620-621 Zo n ed Bit Reco rdin g, 729 Zo n ed Reco rdin g, 729 Zo o m ed Video in terface (PC Cards), 933