Basics of Computer Organization and Architecture: Problems and Solutions 9781842658482, 9781783320318

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Basics of Computer Organization and Architecture Problems and Solutions

Basics of Computer Organization and Architecture Problems and Solutions

S.S.S.P. Rao

α Alpha Science International Ltd. Oxford, U.K.

Basics of Computer Organization and Architecture Problems and Solutions 298 pgs. | 183 figs. | 14 tbls.

S.S.S.P. Rao (Retd.) Department of Computer Science and Engineering Indian Institute of Technology Bombay Mumbai Chief Advisor and Mentor CMC Limited, Hyderabad Copyright © 2014 ALPHA SCIENCE INTERNATIONAL LTD. 7200 The Quorum, Oxford Business Park North Garsington Road, Oxford OX4 2JZ, U.K.

www.alphasci.com All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without prior written permission of the publisher. ISBN 978-1-84265-848-2 E-ISBN 978-1-78332-031-8 Printed in India

To my Sister and Brother-in-law Indira Mahalakshmi and Sri krishna

Foreword

Computer Science is a dynamic subject in which change is the norm. Every eighteen months the power of processors double. The capacity of secondary storage doubles almost every 15 months. In addition the speed of communications systems and their bandwidth are rapidly increasing. Whereas the capacity and power of computers are increasing the cost has remained constant. The revolution in hardware has enabled very powerful software to be supported. Writing a textbook on computer organization and architecture is a challenge in this dynamic environment as it can become obsolete even while writing it! To guard against this, authors have to emphasize fundamental, invariant aspects of the subject by selecting appropriate topics to discuss and by choosing a method of presentation which enhances students' ability to understand, analyze and synthesize. A famous educational psychologist Benjamin Bloom created a taxonomy of learning domains in 1956 in order to promote higher forms of cognition. His taxonomy has six classes. At the lowest level of cognition is remembering or recalling what is learnt. Next one is understanding, namely, comprehending the meaning and interpreting the acquired knowledge. Analyzing is at a higher level which requires students to separate concepts into component parts to enable them to understand the organization and structure of the subject. Creating or synthesizing a new system from component parts is at next higher level of cognition. At the top is evaluation which requires students to judge the relative merits of alternative solutions or designs. The education and evaluation system in many institutions emphasize only recall. As pointed out by Prof. S.S.S.P. Rao in his Preface to this book, he found that his students had difficulty in examinations which test higher cognitive abilities. To alleviate this problem students face, Prof. Rao has taken a different approach in writing this book. He has given a short introduction to each chapter emphasizing fundamentals of the topic. It is followed by questions and answers which to some extent, follow Bloom's taxonomy, starting with recall and ending with design. The topics cover a normal undergraduate curriculum of this subject. It is a valuable addition to

viii

FOREWORD

the vast literature on this popular subject. I commend this effort by a very experienced teacher and I am sure that if students diligently work out by themselves the answers to the problems in the book and compare their answers with that provided by Prof. Rao, they will learn Digital Computer Organization and Architecture very effectively. V. Rajaraman Honorary Professor Super Computing Education and Research Centre IISc, Bangalore

Preface

Digital Computer Organization and Architecture is a very interesting topic and this book gives the reader a very good understanding of the functioning of the digital computer and its tremendous capabilities. This course was taught by me for the undergraduate students of Electrical and Computer Science and Engineering at IIT-Bombay for several years. There are very many good books on this topic by many authors. At one time I had also planned to write a book on this topic. But, then I noticed one thing. Even though this topic is simple and not very complicated, in my 40 years of teaching experience at IIT-Bombay, students could not do well in the examinations and very few students used to get good grades. Then I felt that even though there are very good books, they are not able to solve the problems. Then a thought crossed my mind that why not I take all the questions I asked in the examinations I conducted on this topic and write a book on Basics of Computer Organization and Architecture: Problems and Solutions. This book may help the student to understand the subject in a better way and make him confident enough to solve a variety of problems on this topic. Even though this book deals with problems and solutions, if one looks at the book in its totality it also serves as another text book on this topic. The problems are in graded form staring from simple to a reasonably complex level. This book starts from a brief history of electronic computers and covers all units of digital computer including number systems and codes, fixed point arithmetic, floating point arithmetic, decimal arithmetic, ALU Design, control unit, hardwired and micro-programmed control unit configurations and design, memories, memory interfacing, buses, examples of standard serial and parallel buses, input and output devices and I/O modes, introduction to microprocessors, microcontrollers, introduction to embedded systems with an example. I conclude with the hope that this book will help the student to understand the subject better and give him enough practice to solve problems confidently and efficiently. S.S.S.P. Rao

Acknowledgements

This level one course on Computer Organization and Architecture was taught by me for several years for the undergraduate students of Indian Institute of Technology, Bombay and further, upon my retirement to the students of IIT-Hyderabad for two years as a visiting professor. Even though the course is not very difficult and a number of excellent text books are available on this subject, all through my professional career, I wondered why many students failed to get good grades in this course. I came to the conclusion that even though the students understand the subject, they are not able to solve the problems due to lack of better understanding of the basic concepts. During my tenure as a Professor of IIT-Bombay, I set many quizzes, mid-semester and end-semester examination papers. Then a thought came to my mind as to why not I take those question papers and write answers and publish a book on Basics of Computer Organization and Architecture: Problems and Solutions. Then immediately I conveyed this idea to many publishers. First response I got immediately from Sri N.K. Mehra of Narosa Publishing House informing that they are very much interested in publishing this book. Then we signed the agreement. First I would like to place on record my sincere thanks and appreciation to Sri N.K. Mehra for his interest, excellent support and encouragement. Then I started writing the solutions to the questions chapter wise. During this exercise, many of my colleagues helped me to a great extent. It is definitely not out of place to thank profusely my IIT-Bombay post graduate students N.B. Sonawalla, S.S. Marathe (1979), A.S. Mankar, A.C. Shelat (1980), and A.P. Tillu (1984) who were involved in the design of IBM 360 compatible computer using the AMD bit-slice processor 2901/2903 as their final year project. This project received financial funding from the Department of Electronics, Government of India. ORG Systems, Baroda provided support for fabricating the printed circuit boards, backplane wiring etc. I am extremely thankful to all the students, Government of India and ORG Systems. When the project was complete, IBM 360 Software test routines, and Micro-diagnostics ran successfully on this machine designed by my students. This exercise gave me a thorough insight into Computer Organisation and Architecture which made me to tune my lecture materials. I have put all that experience in writing this book. I would like to thank very sincerely Dr. Vamsi Srikantam who took great pains to go through my drafts and gave me very good suggestions for improvement of the content. I am highly grateful to him for his valuable help. Then my sincere thanks to my past secretary, Ms. Nasima Kazi, at IIT-Bombay. She had drawn many figures very meticulously with a fine touch. I am sure the reader will appreciate the diagrams when he/she looks at them. I am extremely grateful to my

xii

Acknowledgements

colleague Mr. Parthasaraty at CMC-Hyderabad for the help he rendered in suggesting some corrections, modifying some diagrams and text format for better readability. Further, Ms Usha Priyadharshini helped me in giving some valuable suggestions for the material on compact disk and also getting me some figures for the chapter on Input/Output Devices. Her contribution is commendable. My sincere thanks to her. Last but not the least, I want to express my sense of appreciation and gratitude to my wife, Rajeswari, who gave me immense encouragement and support while I was busy with my writing at home. S.S.S.P. Rao

Contents

Foreword vii Preface ix Acknowledgements xi Chapter 1 Electronic Computers: Brief Review................................................................... 1.1 Chapter 2 Digital Computer : Commonly used Terms and Definitions............................... 2.1 Chapter 3 Number Systems and Codes................................................................................ 3.1 Chapter 4 Fixed Point Arithmetic......................................................................................... 4.1 Chapter 5 Floating Point Arithmetic.................................................................................... 5.1 Chapter 6 Decimal Arithmetic.............................................................................................. 6.1 Chapter 7 Control Unit......................................................................................................... 7.1 Chapter 8 Memory Devices and Interfacing........................................................................ 8.1 Chapter 9 Buses.................................................................................................................... 9.1 Chapter 10 Input and Output Devices and I/O Modes......................................................... 10.1 Chapter 11 Introduction to 8 bit Microprocessors and Microcontrollers..............................11.1 Index......................................................................................................................................... I.1

CHAPTER

1

1.1

INTRODUCTION

Electronic Computers: Brief History

Computing is intimately connected to the representation of numbers. Advances in the numeral system and mathematical notations eventually led to the discovery of mathematical operations such as addition, subtraction, multiplication, division, squaring, square root etc. The earliest known tool for use in computation was the abacus, constructed as a bamboo frame with beads sliding on wires. This abacus is still in use till today in some parts of the world. WitKDGYDQFHVLQHOHFWURQLFVHQJLQHHUVFRXOGEXLOGDPSOL¿HUVZLWKDJDLQRIWKHRUGHURI 105RUPRUH7KLVDPSOL¿HULVFDOOHG2SHUDWLRQDODPSOL¿HU:LWKWKLVRSHUDWLRQDODPSOL¿HUXQLWV that can perform integration, differentiation, addition, subtraction etc., were built. Using these components, a computing system that works with continuous variables and solves differential equations was built which is called the Analog computer. Analog computer works in parallel and handles continuous variables, and hence it works faster. Differential equations play a prominent role in engineering, physics and other disciplines. Analog computer was heavily used then. The concept of programmable computers was developed by an English mechanical engineer Charles Babbage around 1820. Further developments of his work resulted in an electrical computer in 1942 that used vacuum tubes for digital computation including binary arithmetic and Boolean logic. This is the beginning of the digital computer era. Since earlier digital computer were not very fast and analog computer works in parallel, engineers thought of taking best of both worlds by combining analog computer and digital FRPSXWHUWKURXJKDVXLWDEOHLQWHUIDFHVRWKDWWKHRYHUDOOV\VWHPZRUNVIDVWHU7KLVFRQ¿JXUDWLRQ of both analog and digital computer system is called a Hybrid computer. Due to the tremendous advances in electronics and digital computer architecture, digital computers started operating at higher speeds with high reliability. Parallel and Super computers started appearing which not only do number crunching but could be used in various applications

BASICS OF COMPUTER ORGANIZATION AND ARCHITECTURE: PROBLEMS AND SOLUTIONS

1.2

that include Natural Language Processing, Machine Learning, Machine Translation and Web Knowledge Processing etc. Since analog computers have severe problems of drift and also used for limited operations, analog computers have become obsolete along with the hybrid computers. This chapter discusses analog, digital and hybrid computers and the reason for analog and hybrid computer becoming obsolete and presents a brief history of electronic computers of yesterday and today.

1.2

PROBLEMS AND SOLUTIONS

1.1. What are the Electronic computers that were avialable in 1960s? Solution: (a) Analog computer

(b) Digital computer

(c) Hybrid computer 1.2 What is an Analog computer? Solution: Analog computer works in parallel and handles continuous variables. And hence it works faster. There are mechanical and electronic analog computers. The oldest mechanical analog computer that existed in 100BC was a Greek machine Antikythera. Electronic analog computers use units such as Integrators, Summers, Function generators etc. 7KHPDLQHOHPHQWLQWKHVHXQLWVLVWKH2SHUDWLRQDODPSOL¿HUDQDPSOL¿HUZLWKYHU\KLJK gain of the order of 105 or more. Analog computer mainly solves differential equations using the above units. Since the voltages and frequency have limitations, one needs to do Amplitude and 7LPHVFDOLQJRIWKHGLIIHUHQWLDOHTXDWLRQVEHIRUHWKH\DUHVROYHGE\WKHDQDORJFRPSXWHU2QFH amplitude scaling and time scaling are done, based on the differential equations the Integrators, Summers and Functions generators need to be connected using cords (wires). There will be also DFRQWUROXQLWWRVWDUWWKHDQDORJFRPSXWHU7KHUHVXOWVFDQEHHLWKHUVHHQRQ&52VRUSULQWHG on printers. Some commercial Analog computers are Heathkit H1, EC-1, GTE EA 22, EPT-5 (Russian) 1.3 What are the essential units of an Analog computer? Solution: Essential components of Analog computer C

Integrator: Input

R

OA

Output OA = Very high gain amplifier (Operational amplifier)

ELECTRONIC COMPUTERS: BRIEF HISTORY

1.3 R2

Inverter: Input (Vi)

Summer: V1 V2 V3

R1

R2 Output = – R Vi 1 R2 is the gain. – R1

OA

R2

R R0

Output

OA

R1

V1

R2 R R + V2 2 + V3 2 R R1 R0

Fig. P1.1 (a) Essential units of an analog computer.

Symbolic representation of analog computer units initial condition at time t0 K1 Input

Output Integrator

Input

Inputs

K

Output

K2

Output

K3

Inverter with gain K Summer

Fig. P1.1 (b) Symbolic representation of essential units of an analog computer.

1.4. Explain how the differential equation given below is solved on an Analog computer? ay + by + cy = F with intitial conditions y = A and y = B Solution: An Example: Differential equation to be solved on Analog computer is ay + by + cy = F with initial condition at time t0 yt0 = A

yt0 = B

Rewriting this equation  y =

c F b − y − y a a a

BASICS OF COMPUTER ORGANIZATION AND ARCHITECTURE: PROBLEMS AND SOLUTIONS

1.4

Analog computer set up to solve this differential equation is F a

A

B y . –y x

x

b/a –y x c/a

Could be a potentiometer or amplifier (non-inverter) depending on values of b/a or c/a

Fig. P1.2 Analog computer set up for solving a differential equation.

1.5. Why Analog computer became obsolete? Solution: Analog computer became obsolete due to very restricted computations and also due to WKHSUREOHPRI'5,)7LQWKHRSHUDWLRQDODPSOL¿HUZKLFKLVXVHGLQDOOXQLWVRIDQDORJFRPSXWHU Drift leads to some output even though there is no input or in other words when input is zero. Even though special steps are taken to reduce this drift problem, it could not be totally eliminated and needs to be corrected at regular intervals. This drift leads to erroneous results. Now analog computer is an history and is totally obsolete. Analog computer was taught to undergraduate students of Electrical Engineering in Indian Universities till about 1965. 1.6

%ULHÀ\GHVFULEHDDigital computer.

Solution: Digital computer handles discrete numbers. Internal operations are performed in binary number system. It has a central processing unit, primary and secondary memories and input and output equipment. This forms hardware component of digital computer. Digital computer internally works using binary number system. There will be machine instructions and data. The FRPSXWHUH[HFXWHVPDFKLQHLQVWUXFWLRQVDQGPRGL¿HVWKHGDWDDQGWKXVVROYHVWKHSUREOHP7KH machine instructions and data which are in binary form are kwon as machine language of the computer. The problem to be solved by the computer is written in a language that the user is IDPLOLDUZLWKDQGLVNQRZQDV+LJKHUOHYHOODQJXDJH2QFHWKHSUREOHPLVH[SUHVVHGLQ+LJKHU Level Language (HLL), it needs to be translated into machine language, so that computer can execute the machine language and solve the problem which is written in HLL. This forms the software part of the computer. There are generations of computers and the tremendous advances took place on all units of digital computer. Now there are multi-core processors chips. Advances took place in programming languages and operating systems. Apart from number crunching, digital computers are being used in Natural Language Processing, Machine Learning, Machine Translation, and Web Knowledge Processing.

ELECTRONIC COMPUTERS: BRIEF HISTORY

1.7

1.5

What is a Hybrid computer?

Solution: Analog computer works on continuous variables and digital computer handles discrete numbers. Analog computer mainly solves differential equations and is a very fast computer. Digital computer performs arithmetic and logical operations with higher precision. Digital computer is not only a number crunching machine and can be used for textual processing and language translation etc. So scientists thought that combining analog computer and digital computer with DVXLWDEOHLQWHUIDFHWRJHWEHVWRIERWKZRUOGVDQGWKLVFRQ¿JXUDWLRQLVFDOOHG+\EULGFRPSXWHU Hybrid computers were manufactured and lot of research and development work was done LQWKLV¿HOG'XHWRWKHWUHPHQGRXVGHYHORSPHQWVLQGLJLWDOFRPSXWHUDUFKLWHFWXUHPHPRULHV and peripherals and also because of limited capabilities of analog computer and also high cost, hybrid computers became obsolete and companies stopped manufacturing Hybrid computers. Some commercial Hybrid computers are EAI 180, EAI 185, EAI 680. 1.8

Give a brief history of Digital computers.

Solution: History of Digital Computers: History of computing starts from 1820 till today. The concept of programmable computers was developed by an English mechanical engineer Charles Babbage in around 1820. Programmable computer implies a machine which can do mathematical operations. Charles Babbage machine was called Difference engine. These innovations are also the result of tremendous advances WKDW DUH WDNLQJ SODFH LQ WKH ¿HOG RI HOHFWURQLFV$IWHU &KDUOHV %DEEDJH PDQ\ VFLHQWLVWV DQG engineers like Lady Lavelace, Percy Ludgate, LoenardonToren Y Quevedo carried on his work. 7RPP\)ORZHUVGHYHORSHGWKH¿UVWHOHFWURQLFSURJUDPPDEOHFRPSXWHUWKHColossus, and was demonstrated in 1943. In 1942 Professor John Vincent Atanasoff and graduate student Cliff Berry developed the ABC, which was an electrical computer that used vacuum tubes for digital FRPSXWDWLRQLQFOXGLQJELQDU\DULWKPHWLFDQGERROHDQORJLF7KH¿UVWIXOO\IXQFWLRQDOGLJLWDO computer that was built by J. Presper Eckert was ENIAC ( Electronic Numerical Integrator and Computer) which had 18,000 Vacuum tubes and occupied 1800 square feet. In 1949, There FDPHWKH¿UVWVWRUHGSURJUDPGLJLWDOFRPSXWHU('6$&Electronic Delay Storage Automatic Calculator). In 1950, the UNIVAC (Universal Automatic Computer) 1101 was developed which LVFRQVLGHUHGWREHWKH¿UVWFRPSXWHUWKDWFRXOGVWRUHDQGUXQDSURJUDPIURPPHPRU\,Q ,%0,QWHUQDWLRQDO%XVLQHVV0DFKLQHV DQQRXQFHGWKH¿UVWHOHFWULFFRPSXWHUWKHZKLFK ZDVPDVVSURGXFHG(DFK\HDUVDZVLJQL¿FDQWLQQRYDWLRQVLQKDUGZDUHDQGVRIWZDUHDVZHOO DV PLOHVWRQHV LQ DUHDV VXFK DV VFLHQWL¿F FRPPHUFLDO %XVLQHVV  HWF 7KHVH LQQRYDWLRQV DUH DOVRWKHUHVXOWRIWUHPHQGRXVDGYDQFHVWKDWDUHWDNLQJSODFHLQWKH¿HOGRIHOHFWURQLFV$IWHU 9DFXXPWHFKQRORJ\6HPLFRQGXFWRUGHYLFHVVWDUWHGDSSHDULQJLQWKHPDUNHW7KH¿UVWFRPSXWHU XVLQJWUDQVLVWRUVWKH7;2ZDVGHPRQVWUDWHGDWWKH0DVVDFKXVHWWV,QVWLWXWHRI7HFKQRORJ\ LQ%HFDXVHRIWKHDGYDQFHVLQVHPLFRQGXFWRU¿HOGYDULRXVW\SHVRIFRPSXWHUVVXFKDV Supercomputers, large Computers, Minicomputers, Personal Computers, laptops appeared in WKHPDUNHW,%0&'&DUHH[DPSOHVRIODUJHFRPSXWHUV,%0LQWURGXFHGLW¶V

BASICS OF COMPUTER ORGANIZATION AND ARCHITECTURE: PROBLEMS AND SOLUTIONS

1.6

¿UVWSHUVRQDOFRPSXWHUWKHIBM PC in 1981. The Intel microprocessor 8088 was used in this IBC PC with 16 KB ( Kilobytes) of main memory which could be expanded up to 26 KB with 06'260LFURVRIW'LVN2SHUDWLQJ6\VWHP 7KH¿UVWGLJLWDOFRPSXWHUWKDWXVHGPDJQHWLFFRUH Random Access Memory as its main memory was Whirlwind that was introduced by MIT in in 1955. Digital Equipment Corporation manufactured their minicomputer, PDP (Programmed Data Processor) family, starting from 1960. Hewlett Packard introduced their minicomputer HP2100A. Electronic Corporation of India (ECIL), Hyderabad, released their minicomputers 7'&7'&7'&LQ6RPHFRPPHUFLDO6XSHUFRPSXWHUVDUH,%03RZHU EDVHGRQ3RZHUSURFHVVRU(.$EDVHGRQ+3EODGHVDQG,QWHOFORYHUWRZQSURFHVVRU Cray-XC-30 - by Cray corporation, Fujitsu - FX10, Param1000 – CDAC, Pune, India. Then workstations arrived. These workstations included a fully operational computer, display and PRXVHDQGXVHGZLQGRZVPHQXVDQGLFRQVDVDQLQWHUIDFHWRWKH2SHUDWLQJV\VWHP3RUWDEOH FRPSXWHUVODSWRSVVWDUWHGDSSHDULQJLQWKHPDUNHWVLQFH,%0LVWKH¿UVWSRUWDEOH FRPSXWHUZHLJKLQJSRXQGVDQGKDGD¿YHLQFK&57GLVSOD\WDSHGULYH0+]3$/0 SURFHVVRUDQG.%RI5$02VERUQH,LVDQRWKHUODSWRSUHOHDVHGLQZHLJKHGRQO\ pounds and had Z-80 microprocessor, 64 KB of memory, dual 5.25 inches single sided 40 track ÀRSS\GULYHVNH\GHWDFKDEOHNH\ERDUGLQFKFKDUDFWHUîOLQHPRQRFKURPH&57 GLVSOD\PDSSHGDVDZLQGRZRQîFKDUDFWHUGLVSOD\PHPRU\,(((SRUWFRQ¿JXUDEOH as a Parallel printer port, RS-232 compatible 1200 or 300 baud Serial port for use with external modems or serial printers and ran the then-popular CP/M 2.2 operating system. Now several laptops are available from IBM, HP and DELL etc. 1.9

What is von Neumann Architecture of Digital computer?

Solution: von Neumann architecture has only one main memory and both Instructions and data are stored together. This mechanism is known as stored programme concept. This concept was ¿UVWLQWURGXFHGE\YRQ1HXPDQQ  and the IAS computer (at the Princeton Institute for Advanced Studies) was completed in 1952. All general-purpose computers are now based on the concept of the von Neumann architecture (Fig. P1.3). This architecture suffers from one problem. All information (instructions and data) need to move between the

Memory instruction 1 instruction 2 ins.3 (branch)

instruction 4 CPU

Address data item

data and instructions Fig. P1.3 The von Neumann architecture.

ELECTRONIC COMPUTERS: BRIEF HISTORY

1.7

SURFHVVRU DQG PHPRU\ YLD D VLQJOH FKDQQHO ZKLFK ZLOO KDYH ¿QLWH EDQGZLGWK  'XH WR WKLV reason the processor cannot go faster. This performance limiting factor is the bottleneck of von Neumann Architecture. 1.10

What is Harvard Architecture?

Solution: Harvard Architecture The Harvard Architecture is shown in Fig. P1.4 (a). This architecture has two memories one for data and the second is for instructions. The obvious advantage of this architecture is that bandwidth gets increased since there are separate buses for instructions and data. Since memory LVDOORFDWHGWRLQVWUXFWLRQVDQGGDWDLQD¿[HGUDWLRWKLVEHFRPHVVRPHGLVDGYDQWDJH

instruction memory

data memory

instruction 1 data item

instruction 2 ins.3 (branch) ins. address

CPU

data address

instruction 4

instructions

data

Fig. P1.4 (a) The Harvard architecture.

In present day digital computers, outside the CPU von Neumann architecture is used but within CPU there are two memories known as Instruction Cache and Data Cache as in Harvard architecture. Stored programme concept is used in the outside main memory in the sense that LWZLOOKDYHZLOOKDYHERWK,QVWUXFWLRQVDQGGDWDWRJHWKHU7KLVPRGL¿HG+DUYDUGDUFKLWHFWXUH is shown in Fig. P1.4 (b).

BASICS OF COMPUTER ORGANIZATION AND ARCHITECTURE: PROBLEMS AND SOLUTIONS

1.8

Main memory instructions and data

System bus (instructions and data)

instruction memory

data cache

instruction 1 instruction 2 ins.3 (branch)

data item ins. address

CPU

data address

instruction 4

instructions

data

Fig. P1.4 E 0RGL¿HG+DUYDUGDUFKLWHFWXUHZKLFKLVLPSOHPHQWHGLQFXUUHQWGD\FRPSXWHUV

REFERENCES 1. Rajaraman V. Analog Computation and Simulation, PHI, 1963. 2. $UWKXU+DXVQHU$QDORJDQG$QDORJ+\EULG&RPSXWHU3URJUDPPLQJ3UHQWLFH+DOO 3. Goel Anita, Computer Fundamentals, Pearson, 2010.

CHAPTER

2.1

2

Digital Computer: Commonly Used Terms and Definitions

INTRODUCTION

After an electronic computer that used vacuum tubes for digital computation including binary arithmetic and Boolean logic was demonstrated, many generations of digital computers have EHHQGHVLJQHG&RPSXWHUVDUHFODVVL¿HGDV¿UVWVHFRQGWKLUGDQGWKHIRXUWKJHQHUDWLRQEDVHG on the hardware and the software used in that machine. )LUVWJHQHUDWLRQRIFRPSXWHUV XVHG9DFXXPWXEHVZLWK¿[HGSRLQWDULWKPHWLFDV hardware and machine and assembly language as software. They used only programmed and ,QWHUUXSW,2PRGHV Second generation computers (1955-64) were built using transistors, magnetic core memory DVPDLQPHPRU\DQGKDGERWK¿[HGSRLQWDQGÀRDWLQJSRLQWDULWKPHWLFDQG'0$PRGHRI,2 7KH\KDGKLJKOHYHOODQJXDJHVOLNH)2575$1DQGFRPSOLHUVDQGXVHGEDWFKSURFHVVLQJ 7KLUGJHQHUDWLRQ FRPSXWHUVXVHGLQWHJUDWHGFLUFXLWVPLFURSURJUDPPLQJFRQWURO FDFKHDQGSLSHOLQLQJDQG,2FKDQQHOV7KH\KDGPXOWLXVHUDQGWLPHVKDULQJRSHUDWLQJV\VWHPV and multiuser applications. Virtual memory concept was introduced. )RXUWKJHQHUDWLRQSUHVHQW FRPSXWHUVDUHKLJKOHYHOPDFKLQHVXVLQJPLFURSURFHVVRUV VHPLFRQGXFWRU PHPRULHV DQG ,2 SURFHVVRUV7KH\ KDYH PXOWLSURFHVVRU RSHUDWLQJ V\VWHPV HLLs and modern compliers. Multitasking and multithreading concepts are introduced. Super computer and Vector processors are built. Now Multi-core processors are available and efforts DUHRQWRGHYHORSHI¿FLHQWRSHUDWLQJV\VWHPVIRUWKHVHPXOWLFRUHSURFHVVRUEDVHGFRPSXWHUV When a reader reads about a computer, he comes across various computer terms that he needs to understand very clearly. This chapter is devoted to clearly explain the terms starting from bit to task, thread and multithreading etc., in a graded form that are used in Computer 2UJDQL]DWLRQDQG$UFKLWHFWXUH

BASICS OF COMPUTER ORGANIZATION AND ARCHITECTURE: PROBLEMS AND SOLUTIONS

2.2 2.2 2.1

PROBLEMS AND SOLUTIONS What do you understand by the term Computer architecture?

Solution: If a question is asked what features are provided in a computer, the answer you get is the Architecture of the Computer. Ex: Instruction set, Pipelining, Branch prediction etc. 1.2

What do you understand by the term Computer organization?

Solution: If a question is asked how those facilities are provided in the computer, the answer you get is Computer organization. Ex: How the Computer architecture is realized using the components VXFKDVORJLFJDWHVÀLSÀRSVUHJLVWHUVPHPRULHVHWFDQGWKHZD\WKH\DUHFRQQHFWHG,QRWKHU words, it represents how the Instruction Set architecture is implemented. 2.3

What is Computer hardware?

Solution:&RPSXWHUKDUGZDUHXVHVORJLFJDWHVÀLSÀRSVUHJLVWHUVDGGHUVPHPRULHVHWFDQG connects them to manipulate data (alphanumeric information). 2.4

What is Computer software?

Solution: Computer software is a set of instructions ( Commands) to manipulate data as desired using computer hardware. 2.5

What do you understand by the term Firmware?

Solution: Firmware is the microprogramme written for the microprogrammed control unit. This term also is used for the software stored in a Read-only-memory in a computer. 2.6

What is Bit?

Solution: Bit is binary digit. (1 or 0) 2.7

What is Nibble?

Solution: Nibble contains four bits. 2.8

What is a Byte?

Solution: Byte contains eight bits. 2.9

What is Machine instruction?

Solution: 0DFKLQHLQVWUXFWLRQZULWWHQLQELQDU\FRGHWKDWWHOOVWKHFRPSXWHUZKDW2SHUDWLRQ $ULWKPHWLF/RJLF&RQWURO,QSXW2XWSXW LVWREHSHUIRUPHGE\WKHFRPSXWHUDQGDOVRVSHFL¿HV WKHGDWDRUORFDWLRQRIGDWDRQZKLFKWKHVSHFL¿HGRSHUDWLRQLVWREHSHUIRUPHG6RPDFKLQH LQVWUXFWLRQFRQWDLQV23(5$7,21&2'($''5(662)'$7$25'$7$,76(/)2521/