His Master's Slave

CSIR GOLDEN JUBILEE SERIES

HIS MASTER'S

SLAVE

TAPAN BHATTACHARYA

HIS MASTER'S SLAVE

TAPAN

BHATTACHARYA

Publications & Information Directorate Dr. K.S. Krishnan Marg New Delhi 110 012 India

His Master's Slave Tapan Bhattacharya © Publications & Information Directorate First Edition : November 1991 Second Edition : November 1992 Third Edition : August 1995 I S B N : 81-7236-018-5

CSIR Golden Jubilee Series Publication No. 3 Series Editor

Dr. Bal Phondke

Volume Editor

Parvinder Sindhoo

Cover Design

Pradip Banerjee

Illustrations

Pradip Banerjee, Neeru Sharma, Sushila Vohra, Neeru Vijan, P.R. Mehta and Mohan Singh

Production

V. Ramachandran, K.B. Nagpal, Sudhir Chandra, Mamgain, Vinod Sharma and Radhe Shiam

Designed, Printed and Published by Publications & Information Directorate (CSIR) Dr. K.S. Krishnan Marg, New Delhi 110 012 India

Foreword The Council of Scientific & Industrial Research (CSIR), established in 1942, is committed to the advancement of scientific knowledge, and economic and industrial development of the country. Over the years CSIR has created a base for scientific capability and excellence spanning a wide spectrum of areas enabling it to carry out research and development as well as provide national standards, testing and certification facilities. It has also been training researchers, popularizing science and helping in the inculcation of scientific temper in the country. The CSIR today is a well-knit and action-oriented network of 41 laboratories spread throughout the country with activities ranging from molecular biology to mining, medicinal plants to mechanical engineering, mathematical modelling to metrology, chemicals to coal and so on. While discharging its mandate, CSIR has not lost sight of the necessity to remain at the cutting edge of science in order to be in a position to acquire and generate expertise in frontier areas of technology. CSIR's contributions to high-tech and emerging areas of science and technology are recognized among others for precocious flowering of tissue cultured bamboo, DNA fingerprinting, development of non-noble metal zeolite catalysts, mining of polymetallic nodules from the Indian Ocean bed, building an all-composite light research aircraft, high temperature superconductivity, to mention only a few. Being acutely aware that the pace of scientific and technological development cannot be maintained without a steady influx of bright young scientists, CSIR has undertaken a vigorous programme of human resource development which includes, inter alia, collaborative efforts with the University Grants Commission aimed at nurturing the budding careers of fresh science and technology graduates. However, all these would not yield the desired results in the absence of an atmosphere appreciative of advances in science

and technology. If the people at large remain in awe of science and consider it as something which is far removed from their realms, scientific culture cannot take root. CSIR has been alive to this problem and has been active in taking science to the people, particularly through the print medium. It has an active programme aimed at popularization of science, its concepts, achievements and utility, by bringing it to the doorsteps of the masses through both print and electronic media. This is expected to serve a dual purpose. First, it would create awareness and interest among the intelligent layman and, secondly, it would help youngsters at the point of choosing an academic career in getting a broad-based knowledge about science in general and its frontier areas in particular. Such familiarity would not only kindle in them deep and abiding interest in matters scientific but would also be instrumental in helping them to choose the scientific or technological education that is best suited to them according to their own interests and aptitudes. There would be no groping in the dark for them. However, this is one field where enough is never enough. This was the driving consideration when it was decided to bring out in this 50th anniversary year of CSIR a series of p r o f u s e l y illustrated and specially written p o p u l a r monographs on a judicious mix of scientific and technological subjects varying from the outer space to the inner space. Some of the important subjects covered are astronomy, meteorology, oceanography, new materials, immunology and biotechnology. It is hoped that this series of monographs would be able to whet the varied appetites of a wide cross-section of the target readership and spur them on to gathering further knowledge on the subjects of their choice and liking. An exciting sojourn through the wonderland of science, we hope, awaits the reader. We can only wish him Bon voyage and say, happy hunting.

Preface Notwithstanding his pre-eminent position at the pinnacle of evolution, man is essentially a weak animal. He is not as strong as a wild bull or as supple as a deer. He cannot heave loads as heavy as an elephant can; nor can he run as fast as a cheetah does. He does have, however, one faculty in which he is superior to other members of the animal kingdom. That is his intellectual capacity. Quite naturally he has used this acumen to subjugate other animals and to enhance his own prowess or rather to camouflage his weakness. Having achieved that with a reasonable measure of success, man's appetite for ruling the world grew. He set about, therefore, to acquire even greater degrees of strengths. That led to the designing and constructing of various machines. These gave more power to his elbow but not to his brain. His next goal, obviously, was to do just that. At the same time, the relative ease with which man has been able to get these inanimate slaves has brought to the fore the inherent laziness of man. He is wont to get tired pretty soon of the tedium associated with repetitive operations. These considerations have weighed heavily in the acquisition of the latest of his inanimate slaves, the personal computer. This latter day version of the valet is as loyal to and as conscientious of the well being of its master as the legendary Jeeves of the Wodehousian fame. Unlike the latter, however, this valet lacks innate intelligence. To tap its potential fully and to harness its built-in abilities to the maximum the master has to understand the style of functioning of this dumb servant. Once the master has mastered the basic principles on which the servant obeys his master's commands no task is beyond the slave's comprehension or performing ability. So much so that there is an inherent danger that the master might be lulled into total dependence on the servant and is likely to get the roles reversed.

Acknowledgements The motivation to write a simple story on desktop personal computers came from a two-month assignment as a Visiting Professor in Calcutta University last year. I was asked to teach the basics of personal computers to graduate students and research scholars. I was overwhelmed by the response of my students, who wanted to learn more than what I could possibly know and teach. The excitement was infectious. I must thank all my students for this pleasant infection. I am also grateful to my good friend Prof. Sitesh Roy who was instrumental for my being there. The motivation was there. But, the stimulus came from another trusted friend, Dr. Bal Phondke. He is an acknowledged and much honoured popular science writer. Naturally, he inspired an amateur like me to write for the public. The encouragement was followed by painstaking observation and constructive assessment of the manuscript. My grateful thanks to you, Bal. After all, what are good friends for! In spite of her temporary ailment, the meticulous and methodical manner in which Ms. Gayatri Moorthy went through the manuscript and offered suggestions is amazing. I am immensely grateful to you, Gayatri. Quite often, I badly needed friendly shoulders to cry on. I am fortunate to have such understandingfriends. How can I ever forget the support and help I received from K. Santhanam, his wife, Ramanujam Ashokand Kameshwari Subramaniam! Thank you indeed, Santy, Jaya, Ashok and Kame. There are others who have helped me in various ways. In particular, I am grateful to Dr. B. Bhargava for his comments and suggestions on the manuscript. Finally, they say that it is a wife's prerogative to nag her husband. Tne nagging regularity with which my wife was after me to complete the work, and that too from a distance of some 1,400 km, is unbelievable. I am confident that I would not have completed the book without that nagging. Thank you,Shakuntala. Tapan Bhattacharya

To SHARMISTHA Perhaps some day, you too will use your oum inanimate slave to give relief to your suffering patients. —Baba

Contents Evolution

... 1

The Anatomy

...15

Bit by Bit

...29

Child's Play

... 39

Commanding the Slave

... 47

Muscle Power

... 59

Disease and Ailment

... 70

Master's Role

... 83

Glossary

... 87

The Conception uman species has always been authoritative. The urge for survival has made man dominate over others. Through the ages man has ruled the world, and he still does. In earlier times, he dominated over his own personal human slaves. But, man is also a conscientious being. His scruples did not finally allow him to continue treating another human being as a slave. That is why machines were invented; machines which would obey c o m m a n d s f a i t h f u l l y without any protest. And that is why computers also came into being.

H

Evolution

It actually started some 3,000 years before the birth of Jesus Christ. During those days, the Mesopotamians quite unknowingly laid the foundation of the computer era. They discovered the earliest form of a bead-andwire counting machine, which subsequently came to be known as abacus. Almost 3,000 years later, the Chinese improved upon the abacus, so that they could count and calculate fast. Even today, the Chinese use the abacus widely in their daily commercial and banking activities. In April

2

HIS M A S T E R ' S SLAVE

1991, an abacus knowledge contest held in China attracted more than 2.4 million participants. Many Chinese have claimed that an abacus is sometimes faster than a computer!

The abacus

The concept and development of a computer had to come some day. One cannot do without c o u n t i n g and m a n i p u l a t i n g numbers, which are required in every sphere of human activity.

In addition, precision is of utmost importance. Errors in calculations and mathematical tables could prove disastrous to engineers, scientists, astronomers, navigators, bankers and merchants. But, the manual preparation of precise mathematical tables is not only tedious, but is also subject to human errors. Therefore, there always has been a need for a machine which would count faithfully without mistakes, and a computer is basically a counting machine. However, the concept of a computer did not materialize overnight. Just as the growth and development of mature biological species normally take place in fits and starts over the ages, the computer concept also took thousands of years to mature. The idea evolved gradually with continuous advancement in the scientific, mathematical and engineering fields during the 19th and 20th centuries. Thousands of ideas, concepts and discoveries in physical sciences and mathematics, particularly in the fields of algebra, trigonometry, calculus, numbering and counting systems, contributed to the strengthening of the perception. For example, the idea of logarithm developed in 1614 by the Scottish nobleman, John NAPIER (1550-1617), who also devised a set of numbering rods known as Napier's Bones, notably reduced the tedium of repetitive calculations.

EVOLUTION

3

The Napier's Bones — a primitive calculating device

But the computer concept really took root in 1821. Charles BABBAGE (1791-1871), an Englishman who once taught mathematics at Cambridge, designed three Difference Engines, one after the other, which were expected to calculate logarithmic tables to a high degree of precision. The first engine was the earliest complete design for an automatic calculator. Babbage went on trying to build the engine for 12 years. Even before it was half complete, he designed his second engine, which was to be lighter and faster. This was also not complete, when he started on his third improved engine, which too was not completed. However, later in 1843, the first engine was built and demonstrated in Sweden. Babbage was undoubtedly a genius. Characteristically, therefore, he quickly lost interest in his Difference Engines. Instead, in 1833 he started designing an Analytical Engine which was to become the real ancestor of the modern day computer. Indeed, with the methodical design of his Analytical Engine, which also was never built, Babbage meticulously established the basic principles on which today's computers work. While his Difference Engines could only add numbers, the Analytical Engine was capable of all four arithmetical

4

HIS MASTER'S SLAVE

operations — addition, subtraction, multiplication and division. It had a number of features startlingly similar to those in today's electronic computers. The modern concept of a central processor Stor-

Charles Babbage — a man ahead of his time who designed two counting'machines: (A) the * Difference Engine and (B) the Analytical Engine a §

e

memory

i n p u t - o u t p u t d e v i c e s w e r e all i n c l u d e d i n h i s d e s i g n .

'

area,

and

EVOLUTION

5

It is interesting to note that Lady Ada AUGUSTA (1815-1853) Countess of Lovelace and daughter of the p o e t lord B Y R O N worked closely with Babb a g e in the d e s i g n of programs for the Analytical Engine. An ardent admirer of Babbage and a brilliant interpreter of his work Lady Lovelace used her influence to interest others in the Analytical engine. Even the concept of using punched cards was first introduced by BabAda Augusta Byron Lovelace bage. The Science Museum in London has recently completed building the second Difference Engine to mark the 200th birth anniversary of Charles Babbage in December 1991 — a fitting tribute to the acknowledged father of modern computers.

The Birth What Charles Babbage could only dream about but not build, was fabricated in 1887 by an American named Herman HOLLERITH (1869-1926). He was working in the U.S. Census Department. He fabricated the first electromechanical punched-card tabulator. The machine had a battery of noisy mechanical switches and gears, which had to be adjusted manually. Postcard-sized paper cards were punched in a typewriter-like machine. These were used to feed instructions to the computer. The machine was used by the U.S.

6

HIS M A S T E R ' S S L A V E

Herman Hollerith with his tabulating machine

Department of Census to compile their 1880 census data. The total time taken to complete the compilation was three years, which otherwise would have taken about a decade. In comparison, modern computers can do the same job in a few hours. In 1924, the first computer company was launched in U.S.A. This company, named International Business Machine Corporation (IBM), made significant contributions to the research, development and growth of computers over the next seven decades. In fact, the desktop personal computer was first introduced by IBM more than half a century later. Prof. Howard AIKEN (1900-1973) in U.S.A. constructed in 1943 an electromechanical computer named MARK-1, which could multiply two 10-digit numbers in five seconds — a record at that time! In comparison, the same multiplication would take only a minute fraction of a second for our personal computer today.

7

EVOLUTION

Till the beginning of World War II, computers were electromechanical. They were also rather slow. Moreover,

Hollerith's punched card

before a specific computation could be performed, a huge array of switches and mechanical gears had to be manually adjusted to give the necessary commands to the computer for carrying out a task. It appeared that the operator had to toil more than the computer. Naturally, he was not happy. He wanted a computer which could obey his commands and do a job quickly without demanding human labour. Therefore, his attention was focussed on the development of an electronic computer, which was expected to be faster and more reliable, and could be operated without manual labour.

The Nursery The first acknowledged working model of a prototype electronic digital computer was designed in 1939 by John V. AT AN ASOFF of Iowa State College in U.S.A. Also during the early forties, the U.S. government initiated a project for developing an Electronic Numerical Integrator and Cal-

8

HIS M A S T E R ' S SLAVE

culator (ENIAC). At the Moore School of the University of Pennsylvania, a team of about 50 scientists and engineers completed the first large scale electronic computer in 1946. In the previous year, John von NEUMANN, the Hungarian born renowned space scientist who was also an adviser to the ENIAC project, first propounded the concept of a more versatile electronic computer named Electronic Discrete Variable Automatic Computer (EDVAC). This machine was finally built in 1950. It had the distinction of being the first computer with commands and programs stored in it. Till about I960, electronic computers were using vacuum tube devices or valves. Consequently, they were huge in size occupying large rooms and consuming a large amount of electrical energy. A lot of heat was also generated inside the room. Commands and instructions to the machine were fed using punched cards, which were originally thought of by Charles Babbage but introduced by Herman Hollerith. Computer users were always seen carrying a huge bunch of punched cards. The punching of cards and reading them were performed by mechanical machines which were noisy and took a lot of time and labour. All in all, the whole operation appeared to be rather messy. Further, it still did not satisfy the need to have a machine which would obey its master without demanding any manual labour. The beginning of the sixties witnessed the advent of the earliest form of solidstate computers. Valves and punched cards were gradually replaced with their second-generation cousins — transistors and magnetic tapes. Soon, the transistors were also replaced by their third-generation cousin — the microprocessor. Thousands of transistors and other electronic elements could be integrated in a single semiconductor device to form, the integrated circuit (IC) or the chip. The size of a chip was about the size of a small flower except that it was rectangular. This revolutionary development made one single chip capable of performing all the essential functions, which were being accomplished by hundreds of

EVOLUTION

9

A silicon chip; Size of the chip compared to that of a Petunia flower (inset)

mechanical switches and gears and several valves in the earlier computers. Such a small-sized chip was totally responsible for carrying out the processing and computing tasks. Hence, it was called the microprocessor. Using solid state microprocessors, the first supercomputer was built in 1975 and was named CRAY-I. This was at that time the fastest computer on earth, performing a million more calculations than the ENIAC in a space one thousand times smaller. A much more powerful version of the CRAY supercomputer has recently been procured by India for extensive meteorological studies and forecasts.

10

HIS M A S T E R ' S SLAVE

However, much more exciting was the phenomenal development of microprocessor chips that opened up the possibility of a microcomputer.

The Micro Till the mid seventies, computers were mostly what is currently known as mainframes. They had large capacity and high processing speeds, and were exceptionally reliable. However, only large organizations could afford to buy them, because they were enormously expensive. During the late seventies, less expensive mini computers came into the market. Although minis had considerably lower capacity and speed, these could be bought by smaller organizations who did not have access to mainframes. Both mainframes and minis are essential for analyzing and processing a large

The supercomputer

EVOLUTION

11

The desktop personal computer being operated in a modern office

volume of data in a short time. For example, the analyses of the 1991 Indian population census data, or the daily railway reservation of millions of people, could not possibly be carried out without a mainframe computer.

12

HIS M A S T E R ' S SLAVE

However, what man wanted was a personal slave. The mainframes and minis could never satisfy that requirement. There was an acute need for a small, inexpensive and manageable desktop microcomputer which could be used profitably by individuals, small organizatipns and business houses. But, the micro revolution remained a dream till the end of-the seventies. During the late seventies and early eighties, a number of commercial events helped the advent of a desktop microcomputer. In U.S.A., Seattle Computers launched the first electronic circuitry for a microcomputer using the then available microprocessor chip. In England, Sinclair introduced a home computer named ZENIX using another type of chip. This used a home television as the monitor. Although severely limited in processing speed and capacity as per current standards, this device immediately became popular. Finally in 1981, IBM first introduced a desktop computer for home use, which was trademarked as Personal Computer or PC. Soon, this was followed by hunreds of clones and compatibles made by other companies, whose performance was sometimes vastly superior to the original IBM PC. During the early eighties, Apple Computers in U.S.A. came out with a microcomputer using another chip. This was named Macintosh or simply MAC, and it immediately became a successful competitor to the IBM PC. More powerful microprocessor chips were gradually developed and introduced by many companies. Thus, the capacity, processing speed and reliability of desktop computers went on increasing. Thus, after two decades of dominance by the mainframes and minis, began the era of the microcomputer, or simply micro. It is not as if the utility and relevance of the mainframes and minis diminished. Not in the least. In fact, their utility went on increasing to handle highly complex, involved and intricate computations. Nevertheless, with the introduction of micros, man finally possessed a personal slave. An entirely new sphere of com-

EVOLUTION

13

14

HIS M A S T E R ' S SLAVE

puter activity flourished in small offices, shops, small business houses and commercial agencies; schools, colleges and educational institutions; and what is more exciting, in private homes where millions of individuals could neither afford nor have access to a mainframe or even a mini. Soon, the coupling of desktop micros with mainframes and minis using telephone lines opened up another new domain of information exchange. Over the past one decade, the basic microprocessor chip has undergone considerable advancement, close on the heels of the revolutionary achievements in the Very Large Scale Integration (VLSI) technology. In the IBM PC world, revolutionary changes have taken place in a short span of time. The original IBM PC had extremely limited capabilities in terms of speed of computation and available space for information and data storage. When, in the early eighties, the information storage capacity was substantially enhanced with the introduction of innovative electronic devices, the PC-XT was born. However, both PC and PC-XT used the same microprocessor chip, and hence, they had the same speed of computation. Within a couple of years, a more versatile and faster chip was used, thus giving birth to the PC-AT. During the latter half of the eighties, this chip too was replaced by a still faster and more versatile chip. The early nineties saw even this chip being replaced by its more powerful next generation. With technological advancement coming in leaps and bounds, the desktop personal computers in the early nineties have become as powerful and versatile as the mainframes and minis of yesteryear. Finally, the common man can afford a home computer which will obey his commands and instructions without demur or protest. Man's dream of ruling over a machine, which could act as a faithful slave and follow his commands sincerely, seemed to have been finally achieved.

The Slave here is no dearth of science fiction tales depicting computers ruling over mankind. The basic premise in such fiction is that a computer is more intelligent than a human being. It also presupposes that a computer has a brain. And, if it has a brain, it also must have a memory. On a different scale, the desktop microcomputers have sometimes been projected to be more powerful than most human beings, because apparently they do things which many human beings cannot do.

T The Anatomy

The truth, however, is different. With the birth of the desktop m i c r o c o m p u t e r , the common man has undoubtedly found a faithful slave, which will obey his c o m m a n d s w i t h o u t protest. A micro is a man-made inanimate slave, which is apparently capable of performing wonders. But, does it possess any intelligence at all? Does it have a brain? A memory? For, if it does not, how would it understand and obey its master's commands? In order to answer these questions, we have to look deeper into a c o m p u t e r ' s p h y s i q u e and anatomy.

16

HIS MASTER'S SLAVE

INP UT DE VICE BRAIN SENSE ORGANS OUTPUT DEVICE HEART

DIGESTIVE SYSTEM

CPU

ELECTRICAL POWER

POWER STATION

T h e factors essential for the functioning of a h u m a n b o d y c o m p a r e d to the basic faculties of a computer system

In a rather simplistic manner, we may visualize that a human body functions satisfactorily because of three factors. The human body has a heart, which acts as its life support. It has a brain which guides, directs and governs all its actions. It also has some assets by means of which it can feed itself for survival and growth, and which help it to communicate with the outside world. Undoubtedly, there are other essential functions in a human body. However, we are concerned here with only these three factors.

THE ANATOMY

17

In fact, for all satisfactorily functioning slaves, animate or inanimate, these three requirements are absolutely essential. The slave must be alive, it must have a faculty to guide and govern its actions and it must be able to communicate with its master. If our inanimate slave, the personal desktop computer, is to obey our commands faithfully, it must also possess these three basic faculties. Firstly, our slave must be alive. That is not difficult to visualize. As long as the computer is kept switched on, in principle, it can perform and is alive. The externally supplied electrical energy keeps it functional and acts as its life support. But, there is a catch in this. One must admit that the slave lives from day to day. It is alive and performing only as long as the electrical power input is maintained. As soon as the power is switched off, it is dead. This factor has a critical influence on the working characteristics of our slave. Secondly, our slave must have an acceptable control centre which would guide, direct and govern its performance. Lastly, it must also possess suitable resources (peripherals) by means of which it can communicate with its master.

The Brain All human actions are controlled and directed by the brain. Similarly, if your slave computer has to follow commands faithfully, it must also have some form of control centre. Because your slave is inanimate, it would require constant guidance to carry out tasks assigned to it. Otherwise, it cannot function. In the electromechanical computers of yesteryears, such guidance was supplied manually by adjusting mechanical switches and gears. The control centre in the desktop computer is known as the Central Processing Unit or CPU. This is the brain of the slave. Human brain has three components — cerebrum, cerebellum and brain stem. The cerebrum is responsible for

HIS MASTER'S SLAVE

18

COMPUTER PROCESSING

INPUT

MAIN MEMORY

OUTPUT

STORAGE

BRAIN

SENSORY NEURON

MOTOR NEURON

T h e CPU of a c o m p u t e r is comparable to the h u m a n brain. Just as an electrical impulse is carried in and out of the brain b y special neurons, so does the informational flow occurs through the input-output devices in a c o m p u t e r system

intelligence, judgement and memory in a human being. The cerebellum coordinates the muscular movements and other activities of a human body. The stem regulates desires like thirst, hunger, etc. In a somewhat similar manner, the CPU also has three components which are responsible for three different functions. The two components, which are basically responsible for counting operations, are its Control Unit (CU)

19

THE ANATOMY

and Arithmetic Logic Unit (ALU). The CU controls and guides the interpretation, flow and manipulation of all data and information. On the other hand, the ALU performs all the four arithmetical and some logical operations. In other words, the CPU is capable of guiding, directing and performing the two essential and critical operations, viz. counting and arithmetic logic. These two primary components of the computer b r a i n are contained in the s e m i c o n d u c t o r microprocessor chip, which ultimately determines its capability and versatility. However, it would be quite wrong to think that since the slave has a brain it has intelligence as well. The desktop computer is very hard working, sincere and conscientious. It will act as a perfect slave, as long as it is able to understand what its master wants. And you are the master! But, you have to always command your slave to carry out a specific task. It cannot anticipate or guess what you want. This is because, it can neither think on its own, nor does it have any imaginaMEMORY

PROCESSING

MEMORY

INPUT OUTPUT T h e a n a t o m y of a c o m p u t e r system

20

HIS M A S T E R ' S SLAVE

tion. In other words, it is like a dumb object, which can act as a docile slave who is not bright, imaginative or intelligent. Peter NORTON, an American professional, who has been a pioneer in the field of computer training, compares a desktop microcomputer with an "office worker, with lots of energy but absolutely no initiative, no commonsense, no independence".

Well, if the slave has a brain, it must also have the faculty which we call memory. Indeed, it does possess a memory, which is the third constituent of the CPU. However, the memory of a computer is most unlike human memory. A human being can remember stored information for a long time. Don't you still remember many adventures and antics of your childhood? But your slave has no such faculty. Its memory is temporary. You, as its master, can put information into its memory and take it out any time you want. It can recall as long as its memory has something that can be recalled. Remember, your slave lives from day to day. Therefore, it cannot remember anything after it is switched off. A computer's memory is more like a predefined working place, where it temporarily keeps information and data to facilitate its performance. Peter Norton compares the computer memory with the table of an office worker. As long as he is working there, the office worker uses his table for keeping papers, files, pens, pencils, paper weights and so on. At the end of the work period, he clears up his table and removes all materials. Next day, when he starts working again, he repeats the same procedure. Similarly, a computer's memory is used for temporarily storing information and instructions. The computer uses its memory to keep instructions for a command given by its master. After the task is performed, it clears its memory, and totally forgets all about it. The memory space is then available for the next task to be performed.

THE ANATOMY

21

Norton's analogy

22

HIS M A S T E R ' S S L A V E

The memory of a computer forms the primary storage unit, just like the table of the office worker. Technically, this unit is known as Random Access Memory (RAM). It consists of a series of semiconductor integrated circuit chips. These chips can store information as long as there is electrical power input, As soon as the power is switched off, the memory is totally erased. Therefore, RAM works as a volatile memory. However, one must be very careful in stretching the analogy of an office worker too far. In most cases, the office worker does not wait for his superior's instructions to start his work. He normally uses his brain and memory to start working on his own at the beginning of a work day. Your personal computer cannot do that. Further, the office worker generally uses his intelligence to overcome most difficulties, or a lack of suitable instructions, and carries on his work. A computer gets stuck if there is a lack of correct instructions. For example, if a word like command is spelt as comand, the office worker will immediately recognize it as a spelling mistake, and carry on his work regardless. But, a computer will refuse to accept the misspelt word. It will only caution the user that an error has occurred. Unless a fresh command' is issued with the correct spelling, it would refuse to continue its work. Thus, the basic difference between the two cases lies in the irrefutable fact that while an office worker can think and use his intelligence, your personal slave cannot.

The Limbs If we compare the slave with an office worker, then there must be allied facilities similar to those available in an office. An office worker has his table, which has some drawers. In addition, he has his file cabinet. He stores papers, files and other stationery in these drawers and cabinets. When he requires any article, he takes it out of the drawer or the cabinet and puts it on top of his table for carrying out his work. That

THE ANATOMY

23

is the accepted and convenient method of doing one's office work. The office worker has two different storage places. The first place is the top of his table, where things are kept temporarily when required. This is the primary storage space, because the worker carries out his job here. The other storage place consists of the drawers and cabinets where he can store things permanently. This is his secondary storage place. In a similar manner, your computer must also have analogous storage spaces, where it can stockpile all required items for use. Further, just like the facilities available in an office, it must also have two types of storage places — primary and secondary. RAM acts as the primary storage space in the desktop computer. But it must also have its secondary storage space, analogous to the drawers and cabinets of the office worker. In this secondary storage unit, things may be stored as long as they are not destroyed. The primary storage unit receives the master's commands and instructions from its secondary storage. This is similar to the office worker taking out things from his drawers and putting them on the table top. The difference between the two is that, while the office worker physically takes out the required items from his table drawers, instructions are only read by the CPU from its secondary storage unit. The information physically remains stored in the secondary storage unit, unless it is intentionally or accidentally destroyed. The two most important secondary storage media are the floppy diskette (or simply floppy) and the hard disk. A well known and proven method is used to record information on them. It is the same magnetic method which is used to record either music in your audio cassette tapes, or pictures in the video cassettes. Both the floppy and the hard disk are made by coating a thin layer of high-performance magnetic

HIS MASTER'S SLAVE

24

material on a flat and circular plastic base, similar to the preparation of the audio or video tapes. As is done for an audio or video tape, the information to be stored is converted into magnetic signals. To store the information, the mag(B) h a v e just o n e netic surfaces of the storage medium are magnetized in accordance with the generated signals. An audio cassette tape moves linearly in front of a readwrite head for the recorded music to be played. A floppy requires a disk drive with one or more heads, for the purpose of reading or writing. However, unlike an audio or video (A) A floppy o r a hard disk has two mag-

netic surfaces whereas a u d i o / v i d e o tapes

Tape Disk platter

Read-write head Head Movable arms

Head

Rotating shaft

Direction of cassette tape

The read-write mechanism in a hard disk c o m p a r e d to that in a n audio cassette

25

THE ANATOMY

A

typical disk pack

show-

ing read-write heads

tape, the floppy has two magnetic surfaces on the two opposite sides. Therefore, a floppy disk drive has two aligned read-write heads for the two surfaces. The circular floppy diskette inside its protective paper packet rotates, with its two surfaces facing the two heads. But, unlike the head in an audio tape recorder, the two readwrite heads in a floppy drive also move linearly along the disk radius. Thus, the circular motion of the flopp y a n d t h e l i n e a r m o v e m e n t of the

heads together cover the two opposite disk surfaces completely. A hard disk has a number of aligned platters, each similar to a floppy. Each platter has a pair of read-write heads on its two opposite sides. The larger the number of platters in a hard disk, the larger its storage capacity. Generally, a hard disk has a considerably higher storage capacity than a floppy. Unlike a floppy disk, the hard disk is hermetically sealed to avoid dust, moisture or other contaminants which may otherwise spoil the active magnetized surfaces of the platters.

Hearing and Talking If you are the boss, you may orally instruct your office worker to carry out what you want. Alternatively, you may write a note giving the required instructions. Your office worker can hear or read. Therefore, he would understand and follow your instructions. But, your slave computer is different. Generally speaking, it cannot hear and understand your voice. It also cannot read and interpret something scribbled on a piece of paper. At least not yet. Therefore, you need an input device to communicate with the computer.

26

HIS MASTER'S SLAVE

1 CM

Enter*-1

• Shift

Shift

Alt

The QWERTY layout

The most important input device is the keyboard. There are others like the Mouse or a Joy Stick which is used mostly for playing computer games. The computer keyboard is similar to the typewriter that the office worker uses, but with some important diffrences. Firstly, it is electronic and it cannot type on paper. The keyboard can be conceptually divided into two parts. The first part is exactly the same as the typewriter. This part has English alphabets, numerals, punctuation marks and some other characters like the + and - signs. In fact, the layout of this portion of the keyboard is exactly the same as any standard English typewriter. This is called the QWERTY layout, because the characters are laid

THE ANATOMY

27

out in that order from left to right on the second line from the top. The second portion has no counterpart in a standard typewriter. Pressing a key in this part has a special meaning to the computer. It is essentially equivalent to feeding the computer with a small command or a program. In particular, the key marked Enter (or Return in some keyboards) is an important and frequently used key. It acts as an entrance gate to allow any command or instruction to be fed to the computer. Pressing this key opens the gate. For example, you can type anything. But, uless you press the Enter key after typing, the computer will not read whatever you have typed. Similarly, there are many other special keys on the computer keyboard, each of which has an exclusive meaning to your slave. For instance, pressing the key marked Del deletes the currently typed character and so on. Just as your slave requires you to communicate with it through input devices like the keyboard, it too is in need of a mechanism to communicate with its master. In other words, it requires an output device. Such a device serves the purpose of depicting the results of computer processing in the realworld language. Your slave talks to you through its output device. The most common output device is the monitor or screen or video display unit (VDU). In computer jargon, it is called a console. On the screen you can not only see what you type, but also the results of computer processing. Other important output devices are printers, plotters, etc. As the names suggest, they would give you the processed results or a plotted output on paper.

Capability Notwithstanding all its brain and memory, its storage units and input and output devices, our faithful slave can only

28

HIS M A S T E R ' S S L A V E

count. In addition, it can also perform some logical operations on numbers, like comparing one number with the other. And it can perform both operations fast. That is all it can do. Indeed, our slave computer is nothing but a counting device. But then, so is an electronic calculator. A computer possesses its memory. But so does a calculator. What is then the difference between the two? The basic difference lies in the fact that, while a computer is also able to perform some logical operations, a calculator generally cannot. Due to this expertise, our slave can do many things, which apparently seem to us totally unconnected with counting. Thus, when a personal computer helps you write, edit and process texts, or draw lifelike pictures, or dial a telephone number on command, it appears that it can really do miracles. Such apparently miraculous tasks are performed by your slave computer only because it can count, it can carry out certain logical operations and because it possesses what is commonly known as its memory.

Learning to Cry new-born child does not know how to talk But it knows how to communicate with its surroundings. The child is born with vocal cords which it uses quite effectively. Through crying and apparently meaningless sounds, it expresses its hunger, joy, anguish and other emotions. As the child grows, it listens to the words spoken by others and starts imitating them. Bit by bit, it picks up spoken words and sounds, and starts c o m m u n i c a t i n g with others. Then the child grows up to read and write. It starts communicating in a more proficient manner. Gradually, the link of a spoken and written language makes the child an articulate member of its community.

A

Bit by Bit

Something even more basic must happen to your slave computer, before it can communicate with its master. It must first learn to cry. Further, it is alive only from day to day. Therefore, it m u s t l e a r n e v e r y time it is switched on. A desktop personal computer is an assembly of interconnected e l e c t r o n i c c o m p o n e n t s and

30

HIS M A S T E R ' S S L A V E

devices. The required energy for its becoming and staying alive comes from the input electrical energy. Also, the only possible means for the computer to communicate with the outside world is through electrical energy. Fortunately, this energy can be easily altered, either by changing its voltage, or current, or both. If we use direct current, its direction — positive or negative — can be used to designate contrasting characters. Therefore, in principle, it is possible for the slave computer to use varying levels of electrical energy to communicate with its master. Well, things are not so simple after all! We know that a communicable human language should have its written characters — alphabets, numbers and others. It must also have certain rules and regulations for spelling, grammar, sentence composition and so on. Finally, the language must also be unambiguous and consistent. Such constraints are equally applicable to the slave, even though it is inanimate. On the face of it, this does not seem to pose much problem, if one uses the vehicle of electrical energy to define different characters of the language. One can immediately see that electrical energy may be rather easily altered to represent various characters. One could use electrical pulses of varying magnitudes (heights) to represent different characters of the language. For example, an electrical pulse of, say, 1.0 Volt may represent the English character capital A, 1.1 Volt B, and so on and so forth. The computer brain should be able to detect the magnitudes of the incoming electrical pulses and interpret them correctly. In principle, such a scheme sounds good. However, there are some major complications. It turns out that such a scheme would be inefficient and unreliable, due to some inherent characteristics of electronics. Firstly, in order to represent 52 English alphabetic characters (26 upper case and 26 lower case) along with the 10 numbers and many other essential characters like punctuation marks or arithmetic signs, the electronics would have to generate electrical pulses of as

BIT BY BIT

31

many different magnitudes. That itself is a tall order. Secondly, the pulse magnitudes will have to be closely spaced, because one has to accommodate at least 128 characters within a reasonable and practical voltage range. Also, the electronic detection system would have to be sensitive enough to correctly distinguish between pulses having slightly different magnitudes. Furthermore, some unwanted noise or electrical disturbance in the system might alter a pulse height, thus causing problems of reliability.

Bits to Byte Now, suppose we represent each character in terms of a number. Say the number 65 represents capital A, 66 capital B, and so on. In such a case, we need to produce electrical signals to represent only 10 numbers from 0 to 9, and nothing more. The task becomes simpler. The number of distinct signals reduces from 128 to only 10. The scheme sounds great. But, wait! It can be simplified even more by having only two basic signals representing 0 and 1, and nothing more. The two electrical signals can also be easily discernible, if one is a null or no signal at all, and the other is a signal with a non-zero pulse height, something similar to an ON-OFF switch or a YESNO answer with nothing in between. Such a scheme would be e m i n e n t l y s u i t a b l e for the electronics, because it is easy to distinguish between nothing and something. But, how is it possible to use only two basic signals to communicate with the computer! The G e o r g e B o o l e _ a n £ n g l i s h answer lies in the use of the genius who developed the conB o o l e a n m e t h o d of n u m b e r cept of Binary system

HIS MASTER'S SLAVE

32

counting, a system named after the 19th century mathematician George BOOLE (1815-1864). In our day to day life, we use a decimal numbering system with a base of 10. This system uses 10 digits, starting from 0 and ending in 9. In the Boolean system, which is also called the binary system, the counting is done with a base of 2, with just-two digits 0 and 1. When we designate a number in our language as, say, 28, we actually multiply the first digit 2 by 10 and add it to the second digit 8 to get the result as 28. Similarly, the number 9083 actually stands for: 9083 = 9 0 0 0 + 0 + 80 + 3 = [(9x 103) +(0x 102) + (8x 10')+ (3x 10°)]

BINARY EQUIVALENT

DECIMAL NUMBER 0

=

(0x2 2 )

+

(0x2')

+

(0x2°)

=

000

1

=

(Ox2 2 )

+

(0x2')

+

(1x2°)

=

001

2

=

(0x2 2 )


(1x2')

+

(0x2°)

=

010

3

=

(Ox2 2 )

+

(1x2')

+

(1x2°)

=

Oil

4

=

(lx22)

+

(0x2')

+

(0x211)

=

100

5

=

(lx22)

+

(0x2")

+

(1x2°)

=

101

6

=

(1*22)

+

(1x2')

+

(0x2°)

r

110

7

=

(lx22)

+

(1x2')

+

(1x2°)

=

111

The binary n u m b e r i n g system operates much like an ordinary light switch. W h e n the switch is off, it corresponds to 0 and when it is on, it stands for 1

BIT BY BIT

33

The binary system is exactly similar, except with just two digits — 0 and 1. Our decimal number two will be represented in the binary system as 10, three as 11, four as 100, five as 101, and so on. Similarly, the decimal number 58 will be represented in the binary system by 111010. 58 = 32 + 16 + 8 + 0 + 2 + 0 = [(lx 2 5 ) + ( l x 2 4 )+(1X2 3 )+(0X 2 2 )+(1X 2')+(0x 2°) =111010 Similar to the arithmetic rules applicable to our decimal system, the binary system also has its own rules and regulations. We need not go into the details here. The important thing to appreciate is that communication with the computer becomes simpler through the use of a binary counting system. Each digit in a binary system is called a Bit (a short form for Binary digit). The first computers for home use marketed in U.S.A. and in England in the late seventies and early eighties were 8-bit machines. These machines could take a series of eight bits, or binary digits, at a time. Depending on the microprocessor chip in use, a desktop personal computer can be a 8-bit machine, or a 16-bit or even a 32-bit machine. The eight bits together constitute a byte. The byte is important because each byte represents a character. The maximum number of distinct characters the earlier 8-bit computers could handle was 128 (2 raised to the power of 7). Later, better microprocessor chips allowed even desktop computers to be capable of handling 16 or 32 bits at a time, thus enhancing their capabilities considerably. The basic measurement unit used by any computer to handle or store data and instructions is the byte. Thus, the memory capacity of a desktop microcomputer is normally 640 kilobytes or 640 KB. Similarly, the storage capacity of a floppy diskette or a hard disk is depicted either in KB or in MB (megabytes or million bytes). Floppy diskettes come in two sizes: 5V4 inch and 3V2 inch diameter. The inch measure-

HIS MASTER'S SLAVE

34

ment unit is used because the computer was originally an American product. The 514 inch diameter floppy can have a capacity of either 360 KB (low- density) or 1.2 MB (highdensity). Likewise the 3 ^ inch floppy can have a capacity of 720 KB or 1/44 MB or 2.88 MB. The capacities of hard disks are much higher and could be 20, 40, 80, 120 MB or more. There is a significant difference between the word kilo or mega used in the computer parlance and in our daily life. Generally speaking, a kilo represents 1,000 which is 10 3 . However, the computer uses the binary system of counting. Therefore, the word kilo here is equal to 1,024, which is the same as 2 10 . Similarly, whereas a mega in our daily life stands for 106 (1,000,000), in computer terminology it equals 2" or 1,048,576. In order to distinguish between the normally used kilo and the computer language kilo, the former is usually abbreviated as lower case k, and the latter as capital K.

Communication With the help of bits and bytes, vocal cords are provided to our slave computer. Thus, the basic problem of providing an understandable communication medium could be overcome by representing each character in terms of an unambiguous

VOCAL CORDS

Letter & W o r d s

BIT BY BIT

35

and explicit binary number having eight bits, or a byte. Using this approach, each English language character — alphabets, numbers, punctuation marks and arithmetic signs — has been codified by a specific number. The set of such a defined representation is known as ASCII, an acronym for American Standard Code for Information Interchange. In this codification, the decimal number 65 (1000001 in binary notation) represents capital A, 66 (1000010) capital B, 97 (1100001) represents lower case a, 122 (1111010) represents lower case z, and so on. But, codification of only the English language characters is not enough. Unlike a typewriter, the computer keyboard has many special keys each of which must also be suitably codified. For instance, pressing the Enter key acts like an entrance gate and it has been appropriately represented in ASCII. Code 13 (1101 in binary) represents the Enter key, 127 (1111111) the Del key, and so on. Similar to ASCII, an Indian standardization has also been attempted. This is known as ISCII, an acronym for Indian Standard Code for Information Interchange. Because there are many recognized Indian languages, ISCII codification has been done primarily for the devanagri script. Attempts are also being made to arrive at such representations separately for each Indian language. It should now be clear why a 16-bit machine is better than an 8-bit machine. The 8-bit computer can handle only 128 characters and no more. On the other hand, most personal computers are 16-bit machines, which can handle 256 characters (2 multiplied by 2 raised to the power of 7). For the present 16-bit machines, 128 more characters have been defined and codified. However, unlike the first 128 characters where there is universal ASCII standardization, the second set of 128 characters in a 16-bit computer vary from machine to machine. In fact, this set of 128 characters have often been utilized to represent characters of various other languages like Japanese, German, French, Spanish, Dutch and so on.

36

HIS M A S T E R ' S S L A V E

And that is how your slave, which was originally meant for only English speaking masters, can now be used by people from other countries as well. Undoubtedly, our inanimate slave is learning other languages fast! But, is English the communication language for our personal computer! Unfortunately it is not. We know that our slave is a counting machine, which understands only two things — the bit and the byte. Therefore, all commands and instructions must be given to it in terms of these bits and bytes. Commands in any other form would be totally incomprehensible to our slave, and it would refuse to follow those commands. That could be a problem to the master. Most of us do not know much about these bits and bytes. Neither do we want to learn them just for the sake of handling our slave. Hence, it will be next to impossible for many of us to convert our instructions into bits and bytes all the time. Further, we are the masters, after all! Why should we spend our time and labour to give our commands in the language of our slave? On the contrary, the slave should be able to follow our language. This is where the limitless ingenuity of mankind has come in to help. If a stubborn and dumb slave cannot understand our language, then we know how to overcome that difficulty. Let us take a similar real-life case. Suppose we understand only English and no other language. Also suppose that we have to talk to a person who speaks only Greek or Hebrew or some other language that we do not understand. We then hire a qualified interpreter who would translate from one language to the other. A similar method is used to communicate with our slave computer. Scientists have developed many such interpreters. These are the various program languages, which look almost like our good old English; but there are significant differen-

BIT BY BIT

37

ces. Only specially qualified people amongst us, known as programmers, learn and use such languages to write the

38

HIS MASTER'S S L A V E

required set of commands or programs, and then translate or compile them into a language our slave would understand. These compiled programs (or software) can be stored on floppy or hard disks for use by anyone. When we command our slave it can read and understand these programs. With the basic communication medium identified, our slave should now be ready to learn more about purposeful communication with its master. However, we must not forget that our slave lives from day to day. So, when it is switched on, the first thing it must learn is how to start the day.

Learning Process s the child grows up, he l e a r n s to do so m a n y things. That learning comes through its observation, training and teaching by others and its experience. For example, the child sees water, and learns that it is for drinking or for bathing. Observation of its environment makes it more and more aware of many things. Therefore, its initial learning depends very much on its environment and surroundings. Moreover, the initial learning process influences and controls the child's subsequent behaviour and performance.

A

Child's Play

The same is true with our desktop slave. However, an important difference is that, if our slave computer is taught something, it is quite temporary. This is so because it forgets everything as soon as the power is shut off. T h e r e f o r e , e v e r y time it is switched on, it has to go through the s a m e e s s e n t i a l l e a r n i n g process. Only then it can control its subsequent behaviour and performance. For example, it must first be taught that there are communicating devices like a keyboard, a screen or a printer. Unless it knows their existence, it

40

HIS MASTER'S S L A V E

would not be possible for our slave to interact with them. Just like a child, our slave's learning process depends very much on its environment. And, that is provided by what is known as its Operating System (OS). The OS finally determines what the computer can do or cannot do. The operating system commonly used today by most desktop personal computers is the Disk Operating System (DOS). The name arose because of the floppy or hard disk in use. Often DOS is known either as PC-DOS or as MS-DOS (short form of Microsoft DOS, after its producer).

Basic Education Suppose you wish to undertake higher university studies, say, for a medical degree. It is clear that certain absolutely basic necessities have to be fulfilled first, without which it is not possible to do so. For instance, at the very least, you require the basic knowledge of how to talk in a language that others will follow. In return, you will have to have the basic education to understand others. All these require that you have to go through the essential schooling and undergraduate courses to educate and prepare yourself for higher studies. You cannot enroll for a medical degree directly without having such basic qualifications. In an analogous manner, when a computer is switched on, it will have to be provided first with some basic education. The operating system of a computer provides precisely this basic education. It exposes the computer to the essential preliminaries and prepares it for more complex tasks. It provides the necessary, qualifications to your slave for its expected performance while dealing with its master. In other words, DOS provides a predictable linkage between the electronic world of the computer and the real world of its master.

CHILD'S P L A Y

41

42

HIS MASTER'S SLAVE

An operating system is essentially a set of built-in programs, which teaches the slave computer the existence of associated hardware, such as the keyboard, monitor, printer and the floppy drive. It also tells the computer how to interpret external or internal signals (commands) and what to do under different circumstances. It provides the computer with an anticipated connection with the outside real world, so that the slave can be used in a predictable manner. Without an OS, the computer is just a bunch of electronic hardware capable of doing absolutely nothing.

The Syllabus Well, how does that basic teaching take place! All the required programs pertaining to DOS are generally stored either on a floppy diskette or on the hard disk, after specially preparing them for this purpose. Such a diskette is also known as a system or a boot diskette. The computer reads and interprets the DOS programs for its mandatory basic education, and puts the information in its primary storage space, RAM, for subsequent use. But the question is how does the computer know, in the first place, that it will have to look for the DOS programs. When it is switched on, a computer is not aware of the place where DOS programs are available. Indeed, DOS itself provides that knowledge. Hence, it becomes a chicken and egg problem. Unless there exists a chicken, no egg is produced and unless there is an egg, there cannot be a chicken. This riddle has been solved in a clever way through the use of a semiconductor memory chip called ROM or Reado n l y Memory. It is a pre-programmed microprocessor chip whose contents can only be read, but nothing can be written on it. This chip, an essential part of the computer electronics, contains a small and permanent program called BIOS or Basic

43

CHILD'S P L A Y

Input-Output System. Sometimes, this is also referred as the ROM BIOS, because it resides permanently on the ROM chip.

The R O M chip

ROM BIOS is programmed to carry out two important functions. Firstly, it checks the availability of the primary storage space or RAM, which is usually 640 KB in a PC or PC-XT. This is absolutely essential because RAM would finally contain all DOS instructions. After completing this task, BIOS tells the computer to look for and read the very first location (sector) of the floppy diskette in the first floppy diskette drive, which is the A drive (referred as A:). In the event that there is no floppy diskette in the A drive, BIOS instructs the computer to read the very first sector of the C drive (C:), which is the first hard disk. In addition, ROM BIOS also contains some error messages to caution the user when something goes wrong. Once the computer finds the required DOS programs, the functions of ROM BIOS are completed. It generally does not play any further part in the performance of the computer. The very first sector of a disk or diskette is called the boot sector. Apart from other important information, the boot sector contains a small program, which is often called the bootstrap loader. This program tells the computer to read three DOS programs (files) from the bootable disk. After

44

HIS M A S T E R ' S S L A V E

reading, the computer stores the instructions in the RAM. These programs together form the DOS. After completing these tasks, DOS tells you that your slave is educated enough to accept your commands. It does so by means of a DOS prompt which appears on the screen. This little prompt or cue tells you that your slave is now ready and waiting to serve you. Thus, initially guided by the pre-programmed ROM BIOS, the computer reads the DOS system files from a bootable disk. In the process, DOS takes complete control of the computer for all subsequent tasks. This startup process is often known as booting the computer, because DOS is pulled up by its own bootstrap. The basic and absolutely essential education of your slave gets completed.

The Growth The basic qualification that your slave acquires, when DOS takes control, is anything but permanent. As soon as it is switched off, it coolly forgets everything. Therefore, every time it is switched on, it has to go through the same routine. If there is some error in the DOS programs, your slave would refuse to be educated. Only an error message will be flashed on the screen to warn you that something has gone wrong. To begin with, DOS has been an excellent operating system with the PC family. Other operating systems had been tried with some versions of the desktop computers, without such great success. The universal success of DOS has been so outstanding that today an estimated seven or eight out of 10 desktop personal computers use DOS all over the world. This universality of DOS has helped programmers develop many useful softwares, because each program has to be made compatible with a specific operating system. For example, you write a program, save it in floppy diskettes and take it to

CHILD'S PLAY

45

a place far removed from your home in another country. Because DOS is so universal, your program will work there as well as it worked in your home. Thus, the availability of powerful programs has become global because of the worldwide use of DOS. Over the past 10 years DOS has undergone significant improvements. When it was first used in 1981, DOS started with a version number of 1.0. When major changes were introduced in DOS, the version number was upgraded. For instance, there was no hard disk in the original IBM PC, and DOS 1.0 could recognize only the floppy. DOS 2.0 was introduced to recognize hard disks as well. Since then the DOS versions have been upgraded regularly, and the latest version in the market as on October 1991 is DOS 5.0.

Inadequacy Notwithstanding the utility and universality, DOS is not without its limitations. The first of them is that it generally does not recognize a RAM memory capacity more than 640 KB. Out of this, about 50 to 70 KB is normally required by DOS itself, leaving only about 580 KB for other purposes. Hence, some large programs requiring a lot of free RAM space cannot be used, without the help of alternative means. Furthermore, higher the available memory, faster is the processing. However, such problems have been overcome in the latter versions of DOS by the use of some ingenious methods. But, there are two major disadvantages of DOS which defy satisfactory solutions. Firstly, it cannot serve effectively more than one user at a time. It also cannot efficiently perform more than one task at the same time. In other words, DOS is not a proficient multi-user and multi-tasking operating system.

HIS MASTER'S S L A V E

46

O n e at a time!

Undoubtedly, additional electronic hardware like the Local or Wide Area Networking (LAN or WAN) can be used to improve the usefulness of DOS in multi-user and multi-tasking operations. However, it is still not as efficient as other multi-user operating systems like UNIX.

Prescription hen you want someone to carry out a specific task, you first explain to the person what to do and then instruct him to do accordingly. For any human being, you necessarily assume a minimum level of intelligence. Therefore, you do not have to explain every tiny part of the task. For example, if you want the person to go and buy a pencil from a shop, you just instruct him to go to the shop and buy it. At best, you may tell him which shop to buy it from. But, you do not explain to him what a pencil is. Neither do you explicitly tell him that he will have to come back after buying the pencil and deliver it to you. These aspects, although essential, are hidden in your instructions. Any normal human being would understand that these hidden instructions are also to be executed.

W Commanding the Slave

To give a command to your slave computer, you need to follow a similar procedure, but with a major difference. Your slave is an inanimate object having absolutely no intelligence at all. Therefore, you will have to tell it precisely and explicitly what to do. It will carry out only what you

48

HIS M A S T E R ' S S L A V E

GO BUY A PENCIL

tell it to do and nothing more. You cannot assume that it will understand the hidden instructions which you did not specifically command. You may very well feel that instructing a computer is really tedious and laborious, if we have to tell it each time, precisely and explicitly, everything required to perform a task. In such a case, all of us will not be able to use the services of our slave effectively. Computers will then be useful only for experts. Well, fortunately things are not really that bad. There are qualified persons, known as software designers and programmers, who make things simpler for us to handle our slave efficiently. They write programs which would be understood by our slave in order to carry out one or more tasks. All required and necessary instructions are explicitly written

C O M M A N D I N G T H E SLAVE

49

in these programs. We just have to use them to command our computer to perform a task for us. Just as each one of us has a name for identification, each program or software has a name to go by. Each program is identified by a command name. To us, the users of desktop computers, the command name is important and not what it contains. When we want our personal computer to perform as per the precise instructions given in such a prewritten program, we merely give the required command by its designated name. And presto! Our slave carries out the required task faithfully. What happens inside your computer is the execution of a series of predictable steps guided and controlled by DOS. There are basically two types of commands. A set of essential programs (or commands) are already included in DOS. These are known as internal DOS commands. When DOS is loaded in the RAM during the startup, all the internal DOS commands also get loaded. These include commands like TIME, as a response to which your slave will show the current time on the screen. Same is the case with DATE. Similarly, when the command DIR is entered, it would list the contents of the disk on which you are working. There are about 25 internal DOS commands, which are rather handy in working with a computer. The second type of commands are not internal to DOS. They are separately written, each for a specific purpose. For example, you may have a program which is designed to carry out all kinds of text processing tasks. You may have another program to play a hide-and-seek game with the computer. A third one may yield a computer drawing board where you can draw whatever you want. There are hundreds of programs written by competent individuals or companies for various purposes. This makes life easier for us.

50

HIS M A S T E R ' S S L A V E

Go to the market

Stop at the stationery

shop

Ask for a pencil — a cylindrical, wooden object with a graphite core used for writing

Pay the shopkeeper

for the pencil

Bring the pencil

Give it to me

Buying a pencil - a possible program

Command Management The contents of a program are available in the form of what is known as a file. One specific program may have either one

C O M M A N D I N G T H E SLAVE

51

or more files, depending on the complexity of the program. The computer files are similar to the files used in offices. In the office, we have files which contain a set of papers, which, in turn, contain information and data. Similarly, we have the program instructions written in the computer files. Just as the office files are stored in the filing cabinets, the computer files are stored in the floppy or hard disks. Each file is identified by a specific filename. This has to follow certain specific regulations laid down by DOS. A filename has two distinct parts — the name and the extension, separated by a fullstop or a dot. Some arithmetic and punctuation characters are not allowed either in the name or its extension. The name of a file can be one to eight characters long, without any empty space in between, where as the extension maybe zero to three characters long. The extension in the filename generally designates the type of file it is. The computer files can be broadly divided into two categories: executable and non-executable. All executable files are specially prepared by competent programmers. The name of such a file constitutes the command name. There are only three types of file extensions which would allow the file to be executable. These three extensions are .COM, .EXE and BAT. Additional program instructions may be contained in files, having different extensions, which also fall in the category of executable files. Like the executable files, these are also specially prepared files. All other files fall in the category of non-executable files. They generally contain data, text matter etc., which may be required and used by the executable files during the program execution.

Organization Well, it looks as if things are getting more and more complex, but definitely organized, for our slave computer. First we

52

HIS MASTER'S S L A V E

have the commands. There are the internal DOS commands and the external commands. Then we have the files which essentially contain instructions related to the external commands. It is all very fine that things can be arranged in such an organized manner for the benefit of our dumb slave to follow our commands faithfully. But, what about us, the masters? If there are hundreds of programs, each for a specific task, then there must be thousands of files. Computer programs are getting more and more complex and large each day. That is because the available facilities and the ease with which the programs can be executed and manipulated are gettingbetter everyday. If we wish to possess copies of some of these programs, we may have to store all relevant files in a hard disk. The relatively small-capacity floppy disks may not be sufficient for holding all files. In such a case, how can we remember what file is meant for which program? Or, how do we know which file is required for which program and which is not? More importantly, why should we remember such things? After all, we are the masters! Obviously, some kind of organization would also be required for us to store our files pertaining to different programs. Otherwise, things could be chaotic. With ever increasing data processing requirements and with more and more programs coming in the market, the hard disk storage capacity goes on increasing. The capacities of modern hard disks are huge — anywhere from 20 MB to 800 MB. Even the currently used floppy disks may have a capacity as high as 1.44 MB or 2.88 MB. You can accommodate hundreds of files on such a floppy and much more on a hard disk. However the more the number of files, the more untidy it becomes, unless these files are stored in an organized manner. Let us compare the situation with a warehouse or a godown. A godown starts with, say, one huge sized hall with one single entry. As things start coming in, these are stored in the same big hall. Soon, both the quantity and the nature

C O M M A N D I N G T H E SLAVE

53

of incoming things start increasing. If they are ail stored together in the same big hall, it would be difficult to find a particular item. Things may get out of control. So, we separately partition off small areas, each for a specific type of item to be stored. We also identify each separated area by a name, which may refer to the stored items. But, there is still one single entry point to the godown, through which all goods come in. As the number and nature of the input items increases still further, we make more such partitions. This process goes on till the complete hall is filled up totally. That would be an organized way to arrange materials in a godown. We can adopt a similar strategy with the large storage space available in the hard disk. We have, to start with, one single entry point to the hard disk. We call that the root directory. Simultaneously, we also make separate areas there, which are called subdirectories. Each such separated area, or subdirectory, may be named according to the type of program files contained in it. For example, a subdirectory named LOTUS may contain all files corresponding to the spreadsheet program LOTUS-123. Similarly, another one named DBASE may contain all files pertaining to a specific data base program. The naming of a subdirectory follows exactly the same rules as those laid down for naming a file. Within a subdirectory, one may further have one or more subd irectories, which are analogous to having compartments within a room. But, the important thing is that we will have to go to a subdirectory through the root directory, all the time, just like entering a partitioned godown through the main entry. It is also essential that whether we have any subdirectory or not, we must have a root directory on both the floppy and the hard disk. The root directory is similar to the drawing room or living room of your house. Anyone would enter this room first. Even if he wants to go to another room, he will have to go through this room. Similarly, in a hard or floppy disk, the

54

HIS MASTER'S SLAVE

ROOMS

COMPARTMENTS

•ENTRANCE

- -ROOT DIRECTORY

VEGETABLES SUBDIRECTORIES

APPLES

GRAPES

1

BANANAS

BRINJALS

LADY'S FINGERS

POTATOES

The data storage strategy in a hard disk (above) is akin to a wellorganized godown (top)

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55

first place you approach is the root directory. All subdirectories, if there is any, sprout out of this root directory. If you use a disk as your bootable system disk, then the DOS system files must reside in the root directory.

Obeying the Command Once the storage disk is organized with program files and the slave is ready and waiting to accept its master's command, you can command it to carry out a specific task. First, your computer reads the command name. Then it looks for the required instructions to process your command. The first place it scans is the RAM, where the DOS internal commands have been loaded while booting. If it finds the specific command name and associated instructions already loaded in RAM, it reads the instructions given there and carries out the required task accordingly. For example, if you give the command DIR (an internal command), your computer will extract the necessary instructions from the RAM and list the subdirectories and files on the screen. However, if the command you have entered is not an internal DOS command, then the computer searches for a file with a filename same as the entered command name, having an extension of either COM or .EXE or .BAT, in that sequence. If it finds the necessary file, DOS would direct it to read that file, interpret it and store the contents in its own language in the RAM. After that it carries out the instructions as stored in the RAM. The above two search processes are carried out sequentially one after the other like a clockwork, just as a dependable slave would do, without protest or demur. If the computer does not find the required instructions in any of these two locations, DOS would caution the master with an error message on the screen that the entered command is a bad command or the required file has not been found.

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HIS M A S T E R ' S S L A V E

Your slave can understand and execute two different types of commands. One is the normal one — internal or external — which would be executed as described above. The instructions are read and put in the RAM. These remain there till you finish your work. For example, suppose you load a command pertaining to a computer game, say, playing chess with the computer. After loading, the required instructions are stored in the RAM as long as you play the game. As soon as you quit, everything stored in the RAM is erased, and the previously occupied RAM space falls vacant to accept another program. However, DOS normally does not allow you to load another command simultaneously during the time one program is being so used. There is yet another type of program, which when loaded, remains resident in the memory, till the computer is switched off. This is known as memory resident program. This type of program is capable of working behind another program. For example, you may load a memory resident program which shows your appointments for different times of the day. Even while working with another entirely different program, you may invoke the appointment program and use it as long as you want. When you finish your work, you may get out of this memory resident program and go back to the earlier program where you started from. The advantage of such memory resident programs is that you have to load them only once, but you may use them any number of times. However, they occupy some part of the already limited RAM space, leaving less space in the memory for others.

When you give a command by typing some characters on the keyboard, the typed characters go one after another into what is known as the keyboard buffer and remain there till your computer is ready to read them. The buffer acts like a temporary memory. If the computer is busy performing other

57

COMMANDING THE SLAVE

jobs when you are typing, it would take time till that job is over. Remember, its operating system, DOS, does not allow it to carry out more than one task at a time. The keyboard buffer has a limited capacity and can hold only 11 characters at a time. The reading of a file from a floppy or a hard disk is also carried out via a buffer. Here again, the buffer acts like a temporary storage place, although its capacity is much larger than the keyboard buffer. The situation is similar to what happens in an office. When an office worker completes working on a file, he keeps the file on a separate outgoing tray for onward transmission.

INPUT DEVICE

COMPUTER BUFFER

BUFFER

OUTPUT DEVICE

Buffer - the outgoing tray in a computer

Later, the messenger would come to pick up the file from this outgoing tray. In an analogous manner, the buffer acts like an outgoing tray. The brain of your computer subsequently picks up the temporarily stored information from the buffer. The passage of information through the buffer may appear to delay the operation of the computer. Actually, it is just the reverse. Without a buffer, there would have been more delay. Your slave is fast in its execution of the given tasks. But, it is not fast enough. The delay in carrying out the given instructions occurs due to three factors. The first is hardware based,

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HIS MASTER'S S L A V E

because the processing speed depends on the microprocessor chip in use. In this regard, a PC-XT is slower than a PC-AT. Even amongst the PC-AT family, the processing speed varies widely depending on the chip in use. The second delay arises due to the time taken to read a file from a disk. The file reading is mechanical, and it is done by the read-write head on the rotating floppy disk or the platter of a hard disk. The rotating speed of the platters of a hard disk is 10 times higher than that of a floppy disk. Therefore, the reading time on a hard disk will be about 10 times faster. Thus, if you load a command from a hard disk, your slave would respond much faster. There is yet another delay, which is entirely based on the type of software in use. Some programs are faster working than others, although both may be meant for the same task. The speed of execution of a command depends on the software designers or programmers, our human friends who are the communicating links between a desktop micro computer and its non-expert user. Thus, your slave is not as fast as you may tend to imagine. How fast it can respond to your commands depends very much on its anatomy, what type of command you feed in and how you feed. It obviously has its limitations, much of which are man-made.

The Dumb Slave

Muscle Power

he proficiency, versatility and processing speed of desktop computers have advanced to such an extent that any type of information and data processing is like a child's play to the machines which are now available. Desktop computers today are capable of performing many more types of jobs than those performed by the m a i n f r a m e s and m i n i s of yesteryears. During the early eighties, when Sinclair introduced a small home computer in the U.K. or when IBM released its first PC in the U.S. market, none could have imagined that their future descendants would r e v o l u t i o n i z e the w o r l d of desktop micros. However, all personal computers are not capable of performing all tasks. There are three types of personal computers: the PC, PC-XT and PC-AT. Each has its own strengths and weaknesses. A job which can be accomplished only in a PC-AT, certainly cannot be done in a PC. Indeed, many of the computer applications discussed subsequently require at least a hard disk, and hence a PCXT.

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In general, the versatility of your desktop computer would depend on three factors: (i) the installed hardware, (ii) the available software, and (iii) your own ingenuity. It is difficult to provide a complete list of what your slave computer can do. It is easier to list what it cannot do. As has been stressed throughout, your computer neither has any independence nor any capability to think. Simply stated, it cannot make its own decision, not even of the level of a six month old child! Therefore, you as the master of your slave will have to provide precise and explicit instructions to your slave, in the form of programs and softwares, to let it perform as per your requirements. Many of us tend to believe that a computer cannot make a mistake. The fact is that if something fails, then it can certainly make an error. Therefore, this statement will have to be a qualified one. The hardware of a computer may fail occasionally, as can happen to any electronic equipment. The stored file(s) may get corrupted due to an undesirable environment, or due to virus infection. Such deficiencies would naturally result in mistakes. If such disorders are eliminated, it is surely true that your slave computer will not make an error. With such a high sense of reliability and loyalty, your slave is capable of performing what appears to us as miracles.

Sinew Human ingenuity has never shown any fatigue in trying to expand the horizons of our desktop computers. Over the years, professional programmers have come out with incredible software and programs to enable your slave to perform almost any type of task. Most of the currently possible tasks can be broadly divided into a dozen categories. Within a specific category, there are many types of jobs that your desktop is capable of performing.

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" T h e sun never sets on the computer world"

A wide spectrum of tasks performed by a Desktop Computer. Mail Merge Applications Books, Reports, Journals and Magazines Lecture and Demonstration Materials Electronic Spreadsheet Applications Financial Accounting and Analyses Stores and Inventory Management

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HIS M A S T E R ' S S L A V E

Management Information Service Library and Documentation Management Hospital Management Household Accounting and Inventory Management Statistical and Mathematical Analyses Line Diagrams, Charts, Graphs and Nomograms Video Display Mass Communication Computer Games and Simulation School and College Education Electronic or Electrical Circuit Layout Scientific, Engineering and Creative Design What-if Scenario Analyses Diagnostics Forecasting

Processing of textual matter and creation of organized and flawless documents happen to be the most common and widely used task of a personal computer. Everything you can achieve using some 'papers, a pen, a dictionary and a thesaurus, can be accomplished much more easily and quickly using your computer. In fact, you can achieve much more in terms of organization, readability, presentability and avoidance from spelling and other errors. There are program

MUSCLE POWER

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packages available which can even guide you in adjusting and modifying your writing style. Electronic cutting and pasting of words, lines, paragraphs and texts from other sources can be achieved in a flash. In other words, a qualified text processing package gives you everything, and much more than what you could achieve before the advent of the computer. What is still more exciting is Desk Top Publishing (DTP) using a PC-XT or PC-AT. As the name suggests, you get everything that you can achieve by the typesetting method, indeed much more, in a substantially shorter timeframe. Apart from composing the. text, its layout, line drawings, charts and graphs can be easily created and included in the main body of the text using standard programs. Scanners are available for black and white or colour pictures to be included in the final layout. The design and layout of a complete book or journal can be achieved without much trouble using a suitable DTP package. For example, this book has been written, corrected and edited using a standard text processing software, and then its layout composed by means of a standard DTP package. All these were done using a desktop computer with a hard disk. DTP packages in languages other than English are also available.

Data-based Management Our modern age has been witnessing a prolific explosion of information and data on myriad aspects. Imagine the volume of data and information gathered on approximately 844 million Indians during the recently completed 1991 census. There are about 90 data points on each individual Indian. Thus, more than 75 billion (75 thousand million) individual items of data are to be handled to bring about an authentic analysis of the Indian populace. Without a powerful and fast mainframe computer, it is virtually impossible to analyze this volume of data within a reasonable timeframe.

HIS MASTER'S SLAVE

64

TRAINING CELL 26.09.91 Reverse Text

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Text

Registration and

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Rotate'1 The words "Rotated Text" below should apht pear at r'B »"B'cs to the w e d s " N o r m a l T c x t " i f y ° u r P , i n I e ' c «« print roti , c d , c x l - Otherwise, the words "jloUted Text" will not appear at a1'x

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6,8,10,12,

14.24,36.48.

"Dead zone.** This ruling line a round the page goes e xacti y to edge of the physical page. When printed, the white space outside xhc ruling line represents the "dead" space to which your printer can't print

7

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MUSCLE POWER

65

Undoubtedly, a desktop computer would be hopelessly inadequate to handle such volume of data, however powerful it may be. On the other hand, consider the list of addresses and telephone numbers you have to use frequently, which contains, say, 500 entries. It is extremely easy for your personal computer to handle, analyze and report whatever portion of the data you wish to be manoeuvered v These two extreme examples are intended to stress the act that, in principle, data handling and analyses can be performed by your slave in the same way as in a mainframe. The two major differences are the volume of data that can be handled and the processing speed. A basic philosophy behind the efficient use of a desktop computer is to avoid, or at least reduce, the drudgery and monotony of carrying out a task which is either absolutely routine or highly repetitive in nature. Handling and analyses of a large volume of repetitive data fall in this category. Therefore, a desktop computer is ideally suited for such purposes, subject to the limitations imposed by its performance versatility and speed. The skill in handling data has resulted in a number of practical and highly efficient software packages, ranging from financial analyses to hospital, library and institution management. In particular, for shops, small business establishments, schools, colleges, universities, research institutions, small m a n u f a c t u r i n g units, professionals and individuals, the capability for data analyses and data-based management has turned out to be a bonanza. Indeed, virtually any type of data-based management service can be provided by a desktop computer. In addition to the routine analyses of different types of data and information, your slave is also capable of performing a number of complicated numerical and mathematical analyses. These include almost all types of statistical and regression analyses, equation solving through numerical

66

HIS MASTER'S S L A V E

means and curve fitting to a set of data. There are a number of software packages available in the market, each catering to a specific set of tasks.

Graphics and Animation Perhaps the most spectacular tasks performed by our desktop slave involve graphics and animation packages. Apart from the capability of drawing various types of charts,

Computer graphics

MUSCLE POWER

67

graphs and line diagrams, and text, headlines and banners in a number of attractive fonts, these packages are capable of producing life-like drawings with or without animation. Much of the computer graphics and animation that you see on your television can be produced by your slave. This skill has immensely improved the quality and efficacy of educational, commercial and other audio-visual presentations, lecture-demonstration programs and mass communication, in general. Ultimately, it is the limit of human ingenuity which may restrict the application of the seemingly limitless graphic and animation capabilities of your computer.

CAD/CAM Two major areas where your desktop computer can effectively contribute are drafting of many engineering designs and controlling of some manufacturing processes. These

CAD/CAM

68

HIS MASTER'S S L A V E

capabilities have led to the development of two highly successful application areas called Computer Aided Design (CAD) and Computer Aided Manufacture (CAM). The practice of manual drafting of designs for buildings, machine tools, automobiles, furniture and many other products is slowly giving way to computer drafting. Draftsmen, who were toiling with a large drawing sheet and a set of pencils, erasers, scales and set-squares, are now drafting the same things on a computer screen, with a single drawing showing both isometric and planar views at the flip of a key. The drudgery and monotony of hours of manual labour have reduced considerably. Qualified software packages and hardware interfaces are available for your slave to supervise and control routine manufacturing jobs on a production shop floor. Both CAD and CAM are extensively used to facilitate design, drafting and production control.

Artificial Intelligence Perhaps the most exciting development in the personal computer field is the advent of AI or Artificial Intelligence. This name was first coined in 1956 by Dartmouth College Asstt. Prof. John McCarthy. As the name indicates, attempts are being made to teach a computer to make its own decisions under a set of given conditions. The field is wide open for development, and once fully developed it should contribute substantially in various decision making processes, such as in the battlefield. AI primarily belongs to main-frames and minis, because it requires a huge memory capacity and large processing speed. Nonetheless, a small amount of AI has already made inroads in the desktop field as well. In particular, there are great possibilities for its use in the field of education and training of the handicapped.

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A robot at work

And More There are many other useful applications of your desktop computer. Innovative and new ideas to utilize our docile slave more effectively are constantly coming up. Improvements and advancements in both hardware and software have been contributing to the growth of new application areas. Some important application areas, which have not been discussed in our brief resume above, include education and training, music composition, literal translation of documents from one language to another and hardware-based interface with telephone, telex and fax facilities.

m

Virus nce people got used to the faithful slave computer, they could never imagine that it could strike work someday, and refuse to obey its master. It did precisely that during the latter part of 1987, first in U.S.A. and then the world over. Not only did it just refuse to work, but it started behaving in a puzzling manner. What was more alarming was that the stored files on the hard disks started getting damaged or corrupted. It was reported that many important stored files in a U.S. Defence Department office were lost beyond possible retrieval. This became a crisis situation and all experts started spending sleepless nights to determine the reason for such unusual behaviour by a docile slave. Finally, it was discovered that the culprit was a man-made virus.

O Disease and Ailment

The menace posed by computer viruses m e r c i l e s s l y destroying important stored data and information was first widely publicized in 1988 by a Time magazine article in U.S.A. It was found that two computer viruses named Brain and Ashar, written by two P a k i s t a n i

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Welcome to the dungeon...

brothers, Basit and Amjad of Lahore, were already creating havoc with stored files in many desktop computers. A computer infected with Ashar virus used to flash a message Welcome to the dungeon... on the screen, ironically an apt message to warn about its alarmingly damaging character. The Ashar virus actually replaces a whole program by something totally useless. The presence of the Brain virus was detected by the disk name or volume label getting modified to C Brain. It also destroys files and slows down the processing speed considerably. These highly damaging viruses infect the boot sector of the hard or floppy disk and start destroying everything written on it. The two brothers later

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HIS M A S T E R ' S S L A V E

claimed that their intention was honourable. However, computer experts never believed that. That was the beginning of the virus menace. One would expect that, similar to a living being, your desktop slave would also have some disorders once a while. Most wellunderstood problems arise due to hardware failure. That is nothing abnormal. Hardware failure happens to any electronic system and a desktop computer is no exception. Particularly in dusty and humidity prone areas, a piece of hardware may fail to function properly. A floppy, or occasionally the hard disk, may fail permanently due to the environment or improper handling. However, unless physical damage results due to mishandling or vandalism, permanent hardware failures are rare. The important thing is that the problems due to hardware failure can be understood and rectified with relative ease. However, the most damaging kind of computer disease is due to the impertinent and flippant behaviour of a group of human beings, who want to extract fun out of the discomfort of serious computer users. This alarming disease is caused by infection with one or more man-made computer viruses. The disease is often difficult to diagnose and considerably more challenging to cure. Since its first introduction during 1987, it has been creating devastation in the desktop computer world.

The name virus has been derived from its biological equivalent. Though non-living and artificially created, a computer virus has marked similarities with its biological counterpart. A biological virus is actually a molecular species containing information coded in a nucleic acid core with a covering protein coat. It has the potential to replicate itself. A computer virus, on the other hand, is a small program having

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Attachment

j Introduction of ' iHral genetic matter into host cell,

Clean floppi,

Computer virus

I

Host cell genetic matter lost | Copies of viral genetic matter made

Infectea floppy

Virus spreads to otl

'oppy and hard disks

Host cell swarming until vims

Lysis of host cell ii'all and release of virus

T h e c o m p u t e r virus (right) replicates much like a biological virus (left)

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HIS M A S T E R ' S S L A V E

a set of coded instructions to carry out the desired disorder and destruction, as also to replicate itself. Thus, both forms of viruses contain coded instructions to carry out a set of activities, when certain specified conditions are met. While a biological virus is characterized by its strain, each computer virus has its distinct signature. Similar to the biological counterpart, a computer virus has to replicate and multiply to survive. In both cases, a host is required to sustain the replication process. The replication process of a computer virus is very similar to that of a biological virus, where an animal or a human body acts as the host. A computer virus is first introduced by its creator on to a host — usually a floppy disk containing some useful programs. When that infected floppy is used in a desktop computer, the virus quietly moves either to an uninfected and clean floppy or to the hard disk. When the infected floppy or hard disk is used along with an uninfected floppy in a computer, the virus spreads itself again to infect the clean floppy. That is how it multiplies and replicates. However, unlike the biological viruses, all computer viruses are artificially created, with malicious intentions. The creators are knowledgeable human beings, sadly displaying a sadistic desire to extract some sort of fun at the cost of serious computer users. With the advancement in biotechnology and genetic engineering, it is possible to alter the strains of biological viruses to make them more or less potent. Likewise, it is not difficult to alter a computer virus. Therefore, several versions of the same computer virus have invaded the world computer scene. The only difference is that the altered versions of computer viruses are almost always more potent and harmful. As of August 1991, more than 600 computer viruses have been identified and named. Many of them happen to be aliases of some other more well known viruses. Even if these

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aliases are discounted, there are still more than 500 computer viruses which have already been identified. And, the list is growing every day!

Symptoms Fortunately, the virus infected host computer exhibits a set of symptoms characteristic of each virus. This makes it possible to diagnose the infection. Once infected, appropriate vaccines can be used as a cure. Similarly, preventive

The Trojan horse virus infection

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HIS M A S T E R ' S S L A V E

measures against possible future infection may be carried out by means of suitable immunization processes. Viruses may be broadly divided into three types: Trojan horse, boot sector and file viruses. The most dangerous of them all is the Trojan horse virus. It is capable of destroying files or damaging disks much more severely than any other type of virus. Like the historical Trojan horse, this virus disguises itself as a genuine program, and hence is very hard to detect. The boot sector virus replaces a disk's original boot record with its own code. Remember, when your slave computer is first switched on, the ROM BIOS directs it to read the boot sector of the DOS system disk, which is the first location of the disk. In fact, whenever a floppy or hard disk is used, the computer first reads the boot sector. If that sector is infected, the virus signature would be read and stored into the RAM before anything else. If the signature is in the RAM, any subsequent operation would spread it to all floppy and hard disks. Almost all Trojan horse and boot sector viruses reduce the speed of your computer by substantially increasing the operation times. Viruses which affect the boot sector of a disk eventually result in totally damaging the disk with the consequent loss of all files. The file viruses mostly infect executable files. Infected executable files start behaving in a puzzling manner. Quite often, the lengths of infected files are increased by a preset amount, typical of the virus infecting them. In fact, an unaccountable increased length of an executable file is almost a sure sign of virus infection. There may be many possible infection symptoms. The symptoms may not always be apparent to the user. They depend on what the virus has been created for. Apparent symptoms vary from the regular flashing of funny messages

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ori screen to the complete destruction of all files stored in a disk. However, most viruses manifest themselves in some apparent abnormality or suspicious activity. For example, if your computer suddenly starts flashing a message on the screen which says Stoned, Legalize Marijuana or Happy Birthday, you can be sure that the Stoned or Joshi virus has struck If you find that your computer continuously refuses to boot from the hard disk, chances are that the disk may have been infected. If you suspect that your PC is taking much longer time to execute certain programs, there is a likelihood that a virus must have infected your system. If during routine operation, your slave computer suddenly refuses to function (hangs up), a virus must have invaded. Such suspicious symptoms are more or less definitive indications of some virus having infected the system. There could be other questionable and unnatural symptoms as well. However, all viruses do not produce such obvious symptoms. Indeed, there is a virus called Do nothing virus which remains resident in the RAM and which slowly corrupts the programs and files. You may not be aware of its presence, till it is too late. Some viruses continuously go on increasing the infected file lengths. No other apparent or external symptoms are shown. Unless the infected files are regularly compared with the corresponding uninfected ones, you may not be aware of the virus attack till it is beyond your control. Some viruses alter commonly used internal DOS commands producing totally unexpected and damaging results. For instance, the internal COPY command is meant to copy a file from one disk to another disk or subdirectory. Some viruses are capable of altering this internal DOS command in such a way that, instead of copying, the command will actually erase the file. Such dangerous symptoms are not always easy to detect immediately, unless a qualified virus scanning program is used to check the disk.

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Colourful Names Computer viruses have one interesting aspect. Unlike the biological viruses, most of these have been tagged with colourful names. Sometimes, when a new virus is detected by vigilant observers, it is named after its creator if that name is known. Human ego being what it is, some virus creators do advertise their names. Thus, viruses like Ashar and Joshi were so tagged. However, such cases are rare. In general, viruses tend to get named after the nature of damages they are capable of inflicting. For example, the Friday the 13th virus has been so named because of the irrecoverable damage it does on a friday which falls on the 13th

HISM

R'SS i

E V

The Raindrop virus attack

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of any month. Infection by this virus makes the .COM and .EXE files gradually increase in length, every time such a file is loaded in the memory. Program delays are slowly introduced, resulting in considerably slower processing speeds. If an infected file is loaded in the memory on any friday which falls on the 13th of a month, the file is totally erased. Similarly, there are the April 1st, April 15, Tuesday 1st and Black Monday viruses. The Raindrop or Falling Letters virus is so named because its attack is manifested in the sudden showering of characters on the screen, resulting in a spectacular visual effect. Similarly, we have names like AIDS, Happy New Year, Christmas, Armageddon, Beast, Blood, Disk Killer, Datacrime, Doctor and Joker. Often, viruses have been named after certain countries, places or political leaders, apparently due to some similarities. Thus, we have viruses like Alabama, Big Italian, Icelandic, Iraqi, Tel-Aviv, PLO, Jerusalem, Pakistani (same as Brain), India, Saddam, Kennedy, Hong Kong, Taiwan, Korea, City of Sofia, Lisbon, Vienna, Pentagon, New Zealand and Hawaii. Looking at the colourful and entertaining virus names one must admit that vigilant virus watchers certainly do not lack humour! •

Prevention and Cure But, there is nothing funny or humorous about this dangerous and lethal man-made virus menace. Days, months and years of labour can be destroyed and annihilated at the blink of an eye by this plague, unless precautionary and preventive measures are consciously taken to fight the menace. Fortunately, for serious computer users, as the number of psychotic virus creators increases all over the world, the number of alert virus watchers and immunizers is also growing.

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Just as vaccines protect humans against diseases so do anti-virus programs counter computer viruses

Serious users must always be alert to counter this deadly disease. There are four'essential steps to achieve and sustain that alertness: *

All storage media must be occasionally scanned for possible virus infection. This should include all the

DISEASE AND AILMENT

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suspicious activities which are not normally expected from our faithful slave computer. *

Mercilessly kill the virus if it is detected anywhere.

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All preventive measures must be taken to safeguard the storage media. These would include the use of memory-resident virus detection and elimination programs, immunization of important files against subsequent attack and being suspicious and wary of other's floppy disks, even if these come from your closest friends or relatives.

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All original uninfected programs must be stored in uninfected floppy disks. It should also be ensured that these floppies are so protected that nothing can ever be written on them.

There are some excellent virus scanning programs available in the market. These scanning programs work on the basis of a known characteristic of any virus. Each virus is identified by its specific signature, which consists of a series of bytes. If the signature is known, it becomes easy to detect the presence of the corresponding virus. A virus scanning program searches the storage disk for several such known signatures which have earlier been identified. In fact, some more qualified programs search for any suspicious or questionable activity on the disk. If the disk is infected or any suspicious activity detected, the scanning program cautions the user accordingly. It kills the virus and only then loads the disinfected file into RAM for further processing. If requested by the user, some highly complex anti-virus programs may also immunize selected disk files against all possible subsequent attacks. Thus, the most important requirement to fight the menace is to identify as many virus signatures as possible. Absence of some viruses does not necessarily mean the absence of others as well. Therefore, the primary task is to find out and collect the signatures of all viruses. To fight the virus menace

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collectively, serious computer users must, therefore, exchange information on viruses as widely and freely as possible. The menace has undoubtedly come to stay, and there is a great need to prevent its spread. The only way one can do that is to join hands with others fighting the menace. Only through such a collective effort, we would be able to use our slave to' its fullest capacity.

Going Places

Master's Role

ay by day, the slave is getting more compact. No longer is it necessary for the slave to stay on the desktop. It is going places by faithfully following the master. Thanks to the revolutionary advancement in electronics, battery-powered laptop c o m p u t e r s , with a size smaller than a brief case, are being widely used. Travelling salesmen, businessmen and other professionals have found the laptop computer a boon in their daily chores. From the l a p t o p to the notebook (or palmtop) computer was a natural outcome. The slave is now being carried not as a brief case, but inside its master's pocket as a notebook, just like an electronic calculator. However, the latest entrant is the pen computer. It looks like a notebook computer. But, instead of a keyboard, a pen-like stylus is used to point to a task on the computer screen for the slave to act. It can also recognize its master's handwriting. Because it is easier for us to use a pen or a pencil, rather than a keyboard or mouse,

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this i n n o v a t i o n has really been a blessing. But the l i m i t l e s s human brain is never satisfied in its pursuit for e x c e l l e n c e . T h e Japanese industry has already demonstrated s o m e p r o t o t y p e s of wearable personal computers. Such a computer is designed also to act as a personal adornment. The output and input devices may be worn like a wrist watch or as an atThelaptop tractive waist band. The wearer will have a thin tube running down the back-under the clothes, which would contain all other hardware. At present, such a c o m p u t e r has b e e n designed to do only a limited set of tasks. But, it is only a matter of time for it to learn more. By the beginning of the next century, the slave will perhaps be a constant c o m p a n i o n of the master as an attractive personal adornment. The master will be in a position to get every

*';.--

The pen computer

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service while on the move — everything that is achieved today using a standard desktop personal computer.

Master's Initiative Indeed, by imparting the slave with skillful education and know-how, the human ingenuity has made it small in size and extremely powerful. But, there is always a limitation. The slave can learn up to a certain point and no more. Undoubtedly, its learning capability goes on increasing every day, as new and more powerful chips are developed. Yet, somewhere along the line, the slave will have to admit its failure and refuse to learn more. That is where the master has to make use of the limitless human intelligence and skill to overcome the refusal of the slave to learn more. Human ingenuity has so far overcome almost all problems arising out of its stubborn behaviour. Therefore, life has become easier for the computer users. However, in spite of the availability of several excellent facilities, it is necessary for us - the masters - to marshal many functional disciplines and work ethics, if we wish to handle this powerful slave gainfully. For example, we may need to know the precise spellings and formats of commands we wish to use. It is mandatory for us to be aware of how to feed in data and'information, when required. We need to understand and follow instructions, if any, which may appear on the screen during the processing of a given task. Even with the latest pen computer, we need to know how to use it correctly to get maximum out of our slave. While the masters' learning is undoubtedly essential, it is not the end in itself. In fact, it is just the beginning to continuously expand the capabilities of a powerful machine. A little additional learning makes the master adept in considerably reducing the drudgery, tedium and manual labour of many essential and useful activities.

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Ingenuity of the human brain is yet unrivalled

The relief from drudgery may be so great that within a short time the master may subconsciously start depending completely on the slave. For instance, when the master becomes so indifferent as to command the slave to add two single digit numbers, which should best be done mentally, the dependence becomes total. Eventually, the master may start losing the faculty of independent thinking reaching an inevitable point of no return. Perhaps then, the master becomes the slave, and the slave the master!

Abacus: An ancient device used for counting. It utilizes the base five numbering system. Chip: Integration of thousands of electronic devices and components on a single, rectangular slice of silicon. It is the key to the microelectronic revolution in computers. Compatible: A computer which is operation and performance-wise similar to a computer of a well known make. Compile: To convert a source program to a program which a computer can recognize and understand. Disk drive: An electromechanical device similar to a cassette tape drive used to read/write on a storage device.Hard disk: A flat magnetic plate like a gramophone record used for storing data. Hardware: The physical parts of a computer that includes the mechanical, electrical and the electronic devices. Immunization: A process which induces resistance in the body against a disease. Input device: A device used by a computer user to enter data into the central processing unit of a computer. Magnetic tape: A plastic tape having a coated surface to store data in the from of magnetized regions. Microprocessor An integrated circuit that performs a variety of operations in accordance with a set of instructions. It is widely used as a control device for microcomputers, automobiles, household appliances and so on. Mouse: A device that fits in the palm of a hand and can be moved across a flat surface to control the movement of the cursor - a marker on the display screen which indicates the position where a specific operation is performed for formatting a page on DTP. A mouse generally has three buttons used

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for different operations. It is an aid for those who have little or no typing skill. Output device: A device used in a computer to output the data to the computer user. Peripherals: All hardware other than the CPU in a computer. Program: A set of coded instructions that direct a computer to follow a given logical sequence to perform a particular task. Software: The combination of a set of programs and documentation that enables the computer to perform a set of defined tasks. Vaccines: Biological or chemical agents employed to evoke immunological memory against a disease. Similarly, in a computer, anti-virus programs counter computer viruses.

BRILLIANT

in scope, design, applica- . tion and performance, the Personal Computer(PC) is earning laurels for faultless service. Adept at perfectly and swiftly executing logical commands, in enhancing imaginative conceptualization and information retrieval, in blending precision with promptness while eliminating the tedium of routine, PCs are flawless slaves, skillful, compliant and willing provided the master instructs it in an appropriate yet authoritative manner. In the fast paced brave new world o f today, PCs are intrinsic to efficiency, versatility and success. This attractive and lavishly illustrated book, written especially for the nonspecialist, demystifies the core concepts of computers while highlighting the bond between the human master and his impeccably proficient inanimate slave. Against the backdrop of a canvas rich in detail unfolds the riveting story of a modern day genie of the bottle, the PC, truly his master's slave.

About the Author Dr Tapan Bhattacharya (b.1936) did his M.Sc.(Tech) in Radio Physics & Electronics from Calcutta University and M.S. and Ph.D. from Illinois Institute of Technology(IIT), Chicago, a s a fellow of the International Atomic Energy Agency and later a s a Research Assistant at IIT. Dr Bhattacharya was a trainee at the Trombay Training School of the Atomic Energy Establishment {now BARC). After that he served BARC a s a senior scientist for about 17 years and Central Electronics Ltd (CEL) as Project Manager, Group Manager and finally General Manager. Based in Delhi, Dr Bhattacharya is at present a consultant in ' photovoltaics, semiconductors and PC uses. . During his illustrious career Dr Bhattacharya. has worked on a very wide range of basic, applied and even technoeconomitf aspects of photovoltaics, semiconductors and semiconductor devices. He is the author of about 85 technical papers, reports, studies, etc. His Master's Slave is his first popular science monograph.

ISBN : 81-7236-018-5