introduction to it

INTRODUCTION TO COMPUTERS

Let us begin with the word ‘compute’. It means ‘to calculate’. We all are familiar with calculations in our
day to day life. We apply mathematical operations like addition, subtraction, multiplication, etc. and
many other formulas for calculations. Simpler calculations take less time. But complex calculations take
much longer time. Another factor is accuracy in calculations. So man explored with the idea to develop a
machine which can perform this type of arithmetic calculation faster and with full accuracy. This gave
birth to a device or machine called ‘computer’.

The computer we see today is quite different from the one made in the beginning. The number of
applications of a computer has increased, the speed and accuracy of calculation has increased. You must
appreciate the impact of computers in our day to day life. Reservation of tickets in Air Lines and Railways,
payment of telephone and electricity bills, deposits and withdrawals of money from banks, business data
processing, medical diagnosis, weather forecasting, etc. are some of the areas where computer has
become extremely useful. However, there is one limitation of the computer. Human beings do
calculations on their own. But computer is a dumb machine and it has to be given proper instructions to
carry out its calculation. This is why we should know how a computer works.

Computer is an electronic device. As mentioned in the introduction it can do arithmetic calculations
faster. But as you will see later it does much more than that. It can be compared to a magic box, which
serves different purpose to different people. For a common man computer is simply a calculator, which
works automatic and quite fast. For a person who knows much about it, computer is a machine capable of
solving problems and manipulating data. It accepts data, processes the data by doing some mathematical
and logical operations and gives us the desired output.
Therefore, we may define computer as a device that transforms data. Data can be anything like marks
obtained by you in various subjects. It can also be name, age, sex, weight, height, etc. of all the students
in your class or income, savings, investments, etc., of a country.

What is Computer?
In basic terms computer is an electronic device that processes data, converting it into information that
is useful to people:-

1. Electronic device ((Electronics is the branch of science and technology which makes use of the controlled
motion of electrons through different media and vacuum. The ability to control electron flow is usually
applied to information handling or device control).
2. Process data
3. Converting data into information

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Any computer regardless of its type is controlled by programmed instructions which give the machine a
purpose and tell it what to do.
Computer is an advanced electronic device that takes raw data as input from the user and
Processes these data under the control of set of instructions (called program) and gives
The result (output) and saves output for the future use. It can process both numerical and
Non-numerical (arithmetic and logical) calculations.
A computer is an electronic device, which is used to accept, store, retrieve and process the data. It is
called as data processor because it is mainly used for processing data for producing meaningful
information.
A. ACCEPTS DATA INPUT
B. PROCESSES DATA PROCESSING
C. PRODUCES OUTPUT OUTPUT
D. STORES RESULTS STORAGE

INPUT
Input is the raw information entered into a computer from the input devices. It is the
collection of letters, numbers, images etc.
Process:
Process is the operation of data as per given instruction. It is totally internal process of
the computer system.
Output:
Output is the processed data given by computer after data processing. Output is also
called as Result. We can save these results in the storage devices for the future use.

Computer System
All of the components of a computer system can be summarized with the simple
equations.

COMPUTER SYSTEM = HARDWARE + SOFTWARE+ USER
Hardware = Internal Devices + Peripheral Devices
All physical parts of the computer (or everything that we can touch) are known as
Hardware.

Software = Programs

Software gives "intelligence" to the computer.

USER = Person, who operates computer

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HISTORY OF COMPUTER
History of computer could be traced back to the effort of man to count large numbers. This process of
counting of large numbers generated various systems of numeration like Babylonian system of
numeration, Greek system of numeration, Roman system of numeration and Indian system of
numeration. Out of these the Indian system of numeration has been accepted universally. It is the basis of
modern decimal system of numeration (0, 1, 2, 3, 4, 5, 6, 7, 8, 9). Later you will know how the computer
solves all calculations based on decimal system. But you will be surprised to know that the computer does
not understand the decimal system and uses binary system of numeration for processing.
We will briefly discuss some of the path-breaking inventions in the field of computing devices
Calculating Machines

It took over generations for early man to build mechanical devices for counting large numbers. The first
calculating device called ABACUS was developed by the Egyptian and Chinese people.

The word ABACUS means calculating board. It consisted of sticks in horizontal positions on which were
inserted sets of pebbles. A modern form of ABACUS is given in Fig. 1.2. It has a number of horizontal bars
each having ten beads. Horizontal bars represent units, tens, hundreds, etc
Abacus Computer
Napier’s bones
English mathematician John Napier built a mechanical device for the purpose of multiplication in 1617 A
D. The device was known as Napier’s bones.
Slide Rule
English mathematician Edmund Gunter developed the slide rule. This machine could perform operations
like addition, subtraction, multiplication, and division. It was widely used in Europe in 16th century.
Pascal's Adding and Subtractory Machine
You might have heard the name of Blaise Pascal. He developed a machine at the age of 19 that could add
and subtract. The machine consisted of wheels, gears and cylinders.
Leibniz’s Multiplication and Dividing Machine
The German philosopher and mathematician Gottfried Leibniz built around 1673 a mechanical device that
could both multiply and divide.

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Babbage’s Analytical Engine

It was in the year 1823 that a famous English man Charles Babbage built a mechanical machine to do complex
mathematical calculations. It was called difference engine. Later he developed a general-purpose calculating machine
called analytical engine. You should know that Charles Babbage is called the father of computer.
Mechanical and Electrical Calculator
In the beginning of 19th century the mechanical calculator was developed to perform all sorts of mathematical
calculations. Up to the 1960s it was widely used. Later the rotating part of mechanical calculator was replaced by electric
motor. So it was called the electrical calculator.
Modern Electronic Calculator
The electronic calculator used in 1960 s was run with electron tubes, which was quite bulky. Later it was replaced with
transistors and as a result the size of calculators became too small.
The modern electronic calculator can compute all kinds of mathematical computations and mathematical functions. It can
also be used to store some data permanently. Some calculators have in-built programs to perform some complicated
calculations.

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COMPUTER GENERATIONS

You know that the evolution of computer started from 16th century and resulted in the form that we see today. The
present day computer, however, has also undergone rapid change during the last fifty years. This period, during
which the evolution of computer took place, can be divided into five distinct phases known as Generations of
Computers.Each phase is distinguished from others on the basis of the type of switching circuits used.

1.6.1 First Generation Computers(1940-1956: Vacuum Tubes)
The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous,
taking up entire rooms. These computers were large in size and writing programs on themwas difficult. First
generation computers relied on machine language to perform operations, and they could only solve one problem at
a time. Machine languages are the only languages understood by computers. While easily understood by computers,
machine languages are almost impossible for humans to use because they consist entirely of numbers. Computer
Programmers, therefore, use either high level programming languages or an assembly language programming. An
assembly language contains the same instructions as a machine language, but the instructions and variables have
names instead of being just numbers

ENIAC: It was the first electronic computer built in 1946 at University of Pennsylvania, USA by John Eckert and
JohnMauchy. It was named Electronic Numerical Integrator and Calculator (ENIAC). The ENIAC was 30 50 feet long,
weighed 30 tons, contained 18,000 vacuum tubes, 70,000 registers, 10,000 capacitors and required 150,000 watts of
electricity. Today your favorite computer is many times as powerful as ENIAC, still size is very small.

EDVAC: It stands for Electronic Discrete Variable Automatic Computer and was developed in 1950. The concept of
storing data and instructions inside the computer was introduced here. This allowed much faster operation since the
computer had rapid access to both data and instructions. The other advantages of storing instruction was that
computer could do logical decision internally.

Other Important Computers of First Generation

EDSAC: It stands for Electronic Delay Storage Automatic Computer and was developed by M.V. Wilkes at Cambridge
University in 1949.

UNIVAC-1: Ecker and Mauchly produced it in 1951 by Universal Accounting Computer setup.

Limitations of First Generation Computer

Followings are the major drawbacks of First generation computers.

1. The operating speed was quite slow.

2. Power consumption was very high.

3. It required large space for installation.

4. The programming capability was quite low
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Second Generation Computers 1956-1963: Transistors
Around 1955 a device called Transistor replaced the bulky electric tubes in the first generation
computer. Transistorsare smaller than electric tubes and have higher operating speed. They have no
filament (conductor which easily gets heat up ) and require no heating. Manufacturing cost was
also very low. Thus the size of the computer got reduced considerably. The transistor was far
superior to the vacuum tube,allowing computers to become smaller, faster, cheaper,more energy-
efficient and more reliable than their first-generation predecessors. Though the transistor still
generated a great deal of heat that subjected the computer to damage, it was a vast improvement
over the vacuum tube Today's latest microprocessor contains tens of millions of microscopic
transistors.
It is in the second generation that the concept of Central Processing Unit (CPU), memory,
programming language and input and output units were developed. The programming languages
such as COBOL, FORTRAN were developedduring this period. Some of the computers of the Second
Generation were
IBM 1620: Its size was smaller as compared to First Generation computers and mostly used for
scientificpurpose.
IBM 1401: Its size was small to medium and used for business applications.
CDC 3600: Its size was large and is used for scientific purposes.

Third Generation Computers

The third generation computers were introduced in 1964. They used Integrated Circuits (ICs). These
ICs are popularly known as Chips. The development of the integrated circuit was the hallmark of the
third generation of computers. Transistors were miniaturized and placed on silicon chips, called
semiconductors, which drastically increased the speed and efficiency of computers.

A single IC has many transistors, registers and capacitors built on a single thin slice of silicon. So it is
quite obvious that the size of the computer got further reduced. A chip is a small piece of semi
conducting material(usually silicon) on which an integrated circuit is embedded. A typical chip is less
than ¼-square inches and can contain millions of electronic components(transistors). Computers
consist of many chips placed on electronic boards called printed circuit boards. There are different
types of chips. For example, CPU chips (also called microprocessors) contain an entire processing
unit, whereas memory chips contain blank memory.

users interacted with third generation computers through keyboards and monitors and interfaced
with an operating system, which allowed the device to run many different applications at one time
with a central program that monitored the memory. Computers for the first time became accessible
to a mass audience because they were smaller and cheaper than their predecessors

Some of the computers developed during this period were IBM-360, ICL-1900, IBM-370, and VAX-
750. Higher level language such as BASIC (Beginners All purpose Symbolic Instruction Code) was
developed during this period.
Computers of this generations were small in size, low cost, large memory and processing speed is
very high.

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Fourth Generation Computers 1971-Present

The present day computers that you see today are the fourth generation computers that started
around 1975. It uses large scale Integrated Circuits (LSIC) built on a single silicon chip called
microprocessors. A silicon chip that contains a CPU. In the world of personal computers,the terms
microprocessor and CPU are used interchangeably. At the heart of all personal computers and most
workstations sits a microprocessor. Microprocessors also control the logic of almost all digital
devices .

Three basic characteristics differentiate microprocessors:
Instruction Set: The set of instructions that the microprocessor can execute.

Bandwidth: The number of bits processed in a single instruction.

Clock Speed: Given in megahertz (MHz), the clock speed determines how many instructions per
second the processor can execute.

Abbreviation of central processing unit, and pronounced as separate letters. The CPU is the brains of
the computer. Sometimes referred to simply as the processor or central processor, the CPU is where
most calculations take place. In terms of computing power,the CPU is the most important element
of a computer system.

Two typical components of a CPU are:
The arithmetic logic unit (ALU), which performs arithmetic and logical operations.
The control unit, which extracts instructions from memory and decodes and executes them, calling
on the ALU when necessary.

In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the
Macintosh. Microprocessors also moved out of the realm of desktop computers and into many
areas of life as more and more everyday products began to use microprocessors.
As these small computers became more powerful, they could be linked together to form networks,
which eventually led to the development of the Internet. Fourth generation computers also saw the
development of GUI's, the mouse and handheld devices

Due to the development of microprocessor it is possible to place computer’s central processing unit
(CPU) on single chip. These computers are called microcomputers. Later very large scale Integrated
Circuits (VLSIC) replaced LSICs.

Thus the computer which was occupying a very large room in earlier days can now be placed on a
table. The personal computer (PC) that you see in your school is a Fourth Generation Computer.

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Fifth Generation - Present and Beyond: Artificial Intelligence
Fifth generation computing devices, based on artificial intelligence, are still in development,though
there are some applications, such as voice recognition, that are being used today.
Artificial Intelligence is the branch of computer science concerned with making computers behave
like humans. The term was coined in 1956 by John McCarthy at the Massachusetts Institute of
Technology. Artificial intelligence includes:
Games Playing: programming computers to play games such as chess and checkers

Expert Systems: programming computers to make decisions in real-life situations (for example,
some expert systems help doctors diagnose diseases based on symptoms)

Natural Language: programming computers to understand natural human languages

Neural Networks: Systems that simulate intelligence by attempting to reproduce the types of
physical connections that occur in animal brains

Robotics: programming computers to see and hear and react to other sensory stimuli
Currently, no computers exhibit full artificial intelligence (that is, are able to simulate human
behavior). The greatest advances have occurred in the field of games playing. The best computer
chess programs are now capable of beating humans. In May,1997, an IBM super-computer called
Deep Blue defeated world chess champion Gary Kasparov in a chess match.
In the area of robotics, computers are now widely used in assembly plants, but they are capable
only of very limited tasks. Robots have great difficulty identifying objects based on appearance or
feel, and they still move and handle objects clumsily.
Natural-language processing offers the greatest potential rewards because it would allow people to
interact with computers without needing any specialized knowledge. You could simply walk up to a
computer and talk to it. Unfortunately, programming computers to understand natural languages
has proved to be more difficult than originally thought. Some rudimentary translation systems that
translate from one human language to another are in existence, but they are not nearly as good as
human translators.
There are also voice recognition systems that can convert spoken sounds into written words, but
they do not understand what they are writing; they simply take dictation. Even these systems are
quite limited -- you must speak slowly and distinctly.
In the early 1980s, expert systems were believed to represent the future of artificial intelligence and
of computers in general. To date, however, they have not lived up to expectations. Many expert
systems help human experts in such fields as medicine and engineering, but they are very expensive
to produce and are helpful only in special situations.
Today, the hottest area of artificial intelligence is neural networks, which are proving successful in
an umber of disciplines such as voice recognition and natural-language processing.
There are several programming languages that are known as AI languages because they are used
almost exclusively for AI applications. The two most common are LISP and Prolog

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D

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A World of Computers

Computers are everywhere: at work, at school, and at home (Figure 1-1). Mobile devices, such asmany
cell phones, often are classified as computers. Computers are a primary means of local and global
communication for billions of people. Employees correspond with clients, students with classmates
and teachers, and family with friends and other family members.

Through computers, society has instant access to information from around the globe. Local
And national news, weather reports, sports scores, airline schedules, telephone directories, mapsand
directions, job listings, credit reports, and countless forms of educational material always
areaccessible. From the computer, you can make a telephone call, meet new friends, share photos
andvideos, share opinions, shop, book flights, file taxes, take a course, receive alerts, and automate
yourhome.

In the workplace, employees use computers to create correspondence such as e-mail
messages,memos, and letters; manage calendars; calculate payroll; track inventory; and generate
invoices.At school, teachers use computers to assist with classroom instruction. Students use
computers tocomplete assignments and research. Instead of attending class on campus, some
students take entireclasses directly from their computer.

People also spend hours of leisure time using a computer. They play games, listen to music or
radio broadcasts, watch or compose videos and movies, read books and magazines, share
stories,research genealogy, retouch photos, and plan vacations.

Many people believe that computer literacy is vital to success. Computer literacy, also known
asdigital literacy, involves having a current knowledge and understanding of computers and their
uses.Because the requirements that determine computer literacy change as technology changes, you
mustkeep up with these changes to remain computer literate.

Data and Information

Computers process data into information. Data is a collection of unprocessed items, which caninclude
text, numbers, images, audio, and video. Information conveys meaning and is useful to people.As shown
in Figure 1-2, for example, computers process several data items to print information inthe form of a cash
register receipt.

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Figure 1-2 A computer processes data into information. In this simplified example, the item ordered, item
price,quantity ordered, and amount received all represent data. The computer processes the data to
produce the cash register receipt (information).
Information Processing Cycle
Computers process data (input) into information (output). Computers carry out processes using
instructions, which are the steps that tell the computer how to perform a particular task. A collection
of related instructions organized for a common purpose is referred to as software. A computer
often holds data, information, and instructions in storage for future use. Some people refer
to the series of input, process, output, and storage activities as the information processing cycle.
Recently, communications also has become an essential element of the information processing cycle.
The Components of a Computer
A computer contains many electric, electronic, and mechanical components known as hardware.
These components include input devices, output devices, a system unit, storage devices, and
communications devices. Figure 1-3 shows some common computer hardware components.
Input Devices
An input device is any hardware component that allows you to enter data and instructions into
a computer. Five widely used input devices are the keyboard, mouse, microphone, scanner, and Web
cam (Figure 1-3).
A computer keyboard contains keys you press to enter data into the computer. A mouse is a small
handheld device. With the mouse, you control movement of a small symbol on the screen, called
the pointer, and you make selections from the screen.
A microphone allows a user to speak into the computer. A scanner converts printed material (such
as text and pictures) into a form the computer can use.
A Web cam is a digital video camera that allows users to create movies or take pictures and store
them on the computer instead of on tape or film.

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Output Devices
An output device is any hardware compo nent that conveys information to one or more people.
Three commonly used output devices are a printer, a monitor, and speakers (Figure 1-3).
A printer produces text and graphics on a physical medium such as paper. A monitor displays text,
graphics, and videos on a screen. Speakers allow you to hear music, voice, and other audio (sounds).

Figure 1-3 Common computer hardware components include the keyboard, mouse, microphone, scanner,
Web cam, printer,

monitor, speakers, system unit, hard disk drive, external hard disk, optical disc drive(s), USB flash drive,
card reader/writer, memory

cards, and modem.Figure 1-3 Common computer hardware components include the keyboard, mouse,
microphone, scanner, Web cam, printer,

card reader/writer, memory

cards, and modem.

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Figure 1-3 Common computer hardware components include the keyboard, mouse, microphone, scanner,
Web cam, printer,

card reader/writer, memorycards, and modem.

System Unit

The system unit is a case that contains electronic components of the computer that are used to

process data (Figure 1-3 on the previous page). The circuitry of the system unit usually is part of or

is connected to a circuit board called the motherboard.

Two main components on the motherboard are the processor and memory. The processor, also

called the CPU (central processing unit), is the electronic component that interprets and carries

out the basic instructions that operate the computer. Memory consists of electronic components that
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store instructions waiting to be executed and data needed by those instructions. Most memory keeps

data and instructions temporarily, which means its contents are erased when the computer is shut off.

Storage Devices

Storage holds data, instructions, and information for future use. For example, computers can store

hundredsor millions of customer names and addresses. Storage holds these items permanently.

A computer keeps data, instructions, and information on storage media. Examples of storage

media are USB flash drives, hard disks, optical discs, and memory cards. A storage device records

(writes) and/or retrieves (reads) items to and from storage media. Storage devices often function as a

source of input because they transfer items from storage to memory.

A USB flash drive is a portable storage device that is small and lightweight enough to be transported

on a keychain or in a pocket (Figure 1-3). The average USB flash drive can hold about 4

billion characters.

A hard disk provides much greater storage capacity than a USB flash drive. The average hard disk

can hold more than 320 billion characters. Hard disks are enclosed in an airtight, sealed case. Although

some are portable, most are housed inside the system unit (Figure 1-4). Portable hard disks are either

external or removable. An external hard disk is a separate, freestanding unit, whereas you insert and

remove a removable hard disk from the computer or a device connected to the computer.

An optical disc is a flat, round, portable metal disc with a plastic coating. CDs, DVDs, and Blu-ray

Discs are three types of optical discs. A CD can hold from 650 million to 1 billion characters. Some

DVDs can store two full-length movies or 17 billion characters (Figure 1-5). Blu-ray Discs can store

about 46 hours of standard video, or 100 billion characters.

Some mobile devices, such as digital cameras, use memory cards as the storage media. You can

use a card reader/writer (Figure 1-3) to transfer stored items, such as digital photos, from the

memory card to a computer or printer.

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Communications Devices

A communications device is a hardware component that enables a computer to send (transmit) and
receive data, instructions, and information to and from one or more com putersor mobile devices. A
widely used communications device is a modem (Figure 1-3).

Communications occur over cables, telephone lines, cellular radio networks, satellites, and
other transmission media. Some transmission media, such as satellites and cellular radio networks,
are wireless, which means they have no physical lines or wires.

CHARACTERISTICS OF COMPUTER
Let us identify the major characteristics of computer. These can be discussed under the headings of
speed, accuracy, diligence, versatility and memory.
Now-a-days computer is playing a main role in everyday life it has become the need of people just like
television, telephone or other electronic devices at home. It solves the human problems very quickly as
well as accuratly. The important characteristics of a computer are described below:

1. Speed
The computer is a very high speed electronic device. The operations on the data inside the computer are
performed through electronic circuits according to the given instructions. The data and instructions flow
along these circuits with high speed that is close to the speed of light. Computer can perform million of
billion of operations on the data in one second. The computer generates signals during the operation
process therefore the speed of computer is usually measure in mega hertz (MHz) or gega hertz (GHz). It
means million cycles units of frequency is hertz per second. Different computers have different speed.The
computer was invented as a high-speed calculator. This has led to many scientific projects which were
previously impossible. The control of the moon landing would not have been feasible without computers,
and neither would today's more scientific approach to weather prediction. If we want tomorrow's
forecast today (and not in six months time) meteorologists can use the computer to perform quickly the
necessary calculations and analyses. When making flight reservations we want to know well in advance of
take-off that a seat will be available - if it is not, then we have time to make other arrangements. The
ability to get answers fast enough so that one has time to take action on them (or to make alternative
plans, as in the case of airline reservations) makes real-time computing possible.Electrical pulses travel at

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incredible speeds and, because the computer is electronic, its internal speed is virtually instantaneous.
We do not talk in terms of seconds or even milliseconds. Our units of speed are the microsecond
(millionths), the nanosecond (thousand0millionths) and latterly even the picosecond (million-millionths).
A powerful computer is capable of adding together two 18-digit number in 300 to 400 nanoseconds.
Consider two examples from non-numerical environments. The manual indexing of the complete works of
Thomas Aquinas (approximately 13 million words) would have taken 50 scholars about 40 years to
accomplish. With the aid of a computer a few scholars did it in less than one year. Fingerprint
identification, in time to catch a criminal before he flees the country, would be impossible without
computers. The first example enables us to enjoy knowledge that would otherwise be unobtainable
within our own lifetime. In the second example, the police gain time in which to act.

2. Arithmetical and Logical Operations
A computer can perform arithmetical and logical operations. In arithmetic operations, it performs the
addition, subtraction, multiplication and division on the numeric data. In logical operation it compares the
numerical data as well as alphabetical data.

3. Accuracy
In addition to being very fast, computer is also very accurate device. it gives accurate output result
provided that the correct input data and set of instructions are given to the computer. It means that
output is totally depended on the given instructions and input data. If input data is in-correct then the
resulting output will be in-correct. In computer terminology it is known as garbage-in garbage-out.

4. Reliability
The electronic components in modern computer have very low failure rate. The modern computer can
perform very complicated calculations without creating any problem and produces consistent (reliable)
results. In general, computers are very reliable. Many personal computers have never needed a service
call. Communications are also very reliable and generally available whenever needed.

5. Storage
A computer has internal storage (memory) as well as external or secondary storage. In secondary storage,
a large amount of data and programs (set of instructions) can be stored for future use. The stored data
and programs are available any time for processing. Similarly information downloaded from the internet
can be saved on the storage media.

6. Retrieving data and programs
The data and program stored on the storage media can be retrieved very quickly for further processing. It
is also very important feature of a computer.

7. Automation
A computer can automatically perform operations without interfering the user during the operations. It
controls automatically different devices attached with the computer. It executes automatically the
program instructions one by one.
A computer is much more than an adding machine, calculator or check-out till, all of which require human
operators to press the necessary keys for the operations to be performed. Once a program is in the
computer's memory, the individual instructions are then transferred, one after the other, to the control

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unit for execution. The CPU follows these instructions until it meets a last instruction which says 'stop
program execution'. When Babbage claimed that his Analytical Engine would be automatic, he meant that
once the process had begun, it would continue without the need for human intervention until
completion.

8. Versatility
Versatile means flexible. Modern computer can perform different kind of tasks one by one of
simultaneously. It is the most important feature of computer. At one moment your are playing game on
computer, the next moment you are composing and sending emails etc. In colleges and universities
computers are use to deliver lectures to the students. The talent of computer is dependent on the
software. Computers seem capable of performing almost any task, provided that the task can be reduced
to series of logical steps. For example, a task such as preparing a payroll or controlling the flow of traffic
can be broken down into a logical sequence of operations, whereas comparing the tones of a turner with
a Vermeer cannot. Yet the computer itself has only limited ability and, in the final analysis, actually
performs only four basic operations: It exchanges information with the outside world via I/O devices, It
transfers data internally within the CUP, It performs the basic arithmetical operations, It performs
operations of comparison. IN one sense, then, the computer is not versatile because it is limited to four
basic functions. Yet, because so many daily activities can be reduced to interplay between these
functions, it appears that computers are highly ingenious. Programming is the craft or reducing a given
problem into interplay between these few operations.
9. Communications
Today computer is mostly used to exchange messages or data through computer networks all over the
world. For example the information can be received or send through the internet with the help of
computer. It is most important feature of the modern information technology.

10. Diligence
A computer can continually work for hours without creating any error. It does not get tired while working
after hours of work it performs the operations with the same accuracy as well as speed as the first one.
Being a machine, a computer does not suffer from the human traits of tiredness and lack of
concentration. If 3 million calculations have to be performed, it will perform the 3 millionth with exactly
the same accuracy and speed as the first. This factory may cause those whose jobs are highly repetitive to
regard the computer as a threat. But to those who rely on a continuous standard of output, e.g., quality
control in the refining of oil and other chemical processes, the computer will be seen as a considerable
help.

The Basic Anatomy of the Computer

It receives information (input); it processes this information in some way according to set of precise
instructions (in the CPU); and it then presents the results in a useful form (output).On closer inspection
we find that the CPU (the computer itself, remember) has to store the information in a memory before it
can carry out processing operations. Two kinds of information have to be input, the program and the
data. The program is the set of instructions which the computer is to carry out, and the data is the
information on which these instructions are to operate. For example, if the task is to sort a list of
telephone subscribers into alphabetical orders, the sequence of instructions or procedure which guides
the computer through this operation is the program, whilst the list of names to be sorted is the data. IN

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the Analytical Engine calculations were to be handled by an arithmetic unit which Babbage called the Mill.
The computer also has an arithmetic unit. Arithmetic, because all computer operations involve the
manipulation of numbers. All information, program and data, are represented in numeric form. The
manipulations also include making comparisons and logic type operations as well as arithmetic operations
( + - * / ), and for this reason the unit is referred to in full as the arithmetic and Logic Unit (ALU).The
Electronic Discrete Variable Automatic Computer (EDVAC) in 1952, was to be one such computer. The
memory unit stored both the instructions and data to be used for the calculations. IN 1946, Ekert and
Mauchly formed their own company, which in 1949 was incorporated as the UNIVAC division of the
Remington Rand Company Ltd., In 1951 the UNIVAC I, i.e. the computer developed by Ekert and Mauchly
became operational at the Census Bureau. This computer was self-checking and used magnetic tape for
data input and output. The UNIVAC I was run 24 hours a day until 1963. Yet, another UNIVAC I was put to
business by the General Electric Corporation in 1954.The first generation of computers was marked by the
use of vacuum tubes as the electronic components and by the use of either electrostatic tubes or mercury
delay lines for storage. Power tapes and punched cards were also used. Electronic time per operation
ranged from 0.1 millisecond, while memory access time was 1 millisecond.11. No

11. Feelings
Computer is an electronic machine. It has no feelings. It detects objects on the basis of instructions given
to it. Based on our feelings, taste, knowledge and experience: we can make certain decisions and
judgments in our daily life. On the other hand, computer cannot make such judgments on their own. Their
judgments are totally based on instructions given to them.

12. Consistency
People often have difficulty to repeat their instructions again and again. For example, a lecturer feels
difficulty to repeat a same lecture in a class room again and again. Computer can repeat actions
consistently (again and again) without losing its concentration:

To run a spell checker (built into a word processor) for checking spellings in a document.
To play multimedia animations for training purposes.
To deliver a lecture through computer in a class room etc.
A computer will carry out the activity with the same way every time. You can listen a lecture or perform
any action again and again.

13. Precision
Computers are not only fast and consistent but they also perform operations very accurately and
precisely. For example, in manual calculations and rounding fractional values (That is value with decimal
point can change the actual result). In computer however, you can keep the accuracy and precision up to
the level, you desire. The length calculations remain always accurate.

14. Cheaper (Reduction of cost) Computers are short term investment in order to achieve a long term
gain. Though the investment is high they reduce the cost of each and every transaction. They reduce man
power and leads to an elegant and efficient way for computing various tasks. Storehouse (Memory)

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Secondary storage devices are the key for the data storage. They store the data for which the user wants
to retrieve these data for future use. The examples for various secondary devices are Floppy disk, Optical
disks (CS and DVD), Zip drives, Thumb drives etc. The data of smaller size can be easily fetched and they
can be copied to the primary memory (RAM).Example: Data Warehousing made by IBM.

15. Stage
The speed with which computers can process large quantities of information has led to the generation of
new information on a vast scale, in other words, the computer has compounded the information
'explosion'. How can people cope with it? We can't, but computers can. But where do they keep it all? AS
a human acquires new knowledge, the brain subconsciously selects what it feels to be important and
worth retaining in its memory, and relegates unimportant details to the back of the mind or just forgets
them. In computers, the internal memory of the CPU is only large enough to retain a certain amount of
information. It is therefore, impossible to store inside the computer the records, for example, of every
Premium Bond and the names and address of their owners. All of this data is stored outside of the
memory of the CPU, on auxiliary or secondary storage devices. Small sections of the total data can be
accessed very quickly by the CPU and brought into the main, internal memory, as and when required for
processing.

Advantages and Disadvantages of Using Computers
CHARACTERISTICS OF COMPUTER

Let us identify the major characteristics of computer. These can be discussed under the headings of
speed, accuracy,
diligence, versatility and memory.

Now-a-days computer is playing a main role in everyday life it has become the need of people just like
television, telephone or other electronic devices at home. It solves the human problems very quickly as
well as accuratly. The important characteristics of a computer are described below:
1. Speed
The computer is a very high speed electronic device. The operations on the data inside the computer are
performed through electronic circuits according to the given instructions. The data and instructions flow
along these circuits with high speed that is close to the speed of light. Computer can perform million of
billion of operations on the data in one second. The computer generates signals during the operation
process therefore the speed of computer is usually measure in mega hertz (MHz) or gega hertz (GHz). It
means million cycles units of frequency is hertz per second. Different computers have different speed.
2. Arithmetical and Logical Operations
A computer can perform arithmetical and logical operations. In arithmetic operations, it performs the
addition, subtraction, multiplication and division on the numeric data. In logical operation it compares the
numerical data as well as alphabetical data.
3. Accuracy
In addition to being very fast, computer is also very accurate device. it gives accurate output result

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provided that the correct input data and set of instructions are given to the computer. It means that
output is totally depended on the given instructions and input data. If input data is in-correct then the
resulting output will be in-correct. In computer terminology it is known as garbage-in garbage-out.
4. Reliability
The electronic components in modern computer have very low failure rate. The modern computer can
perform very complicated calculations without creating any problem and produces consistent (reliable)
results. In general, computers are very reliable. Many personal computers have never needed a service
call. Communications are also very reliable and generally available whenever needed.
5. Storage
A computer has internal storage (memory) as well as external or secondary storage. In secondary storage,
a large amount of data and programs (set of instructions) can be stored for future use. The stored data
and programs are available any time for processing. Similarly information downloaded from the internet
can be saved on the storage media.

6. Retrieving data and programs
The data and program stored on the storage media can be retrieved very quickly for further processing. It
is also very important feature of a computer.
7. Automation
A computer can automatically perform operations without interfering the user during the operations. It
controls automatically different devices attached with the computer. It executes automatically the
program instructions one by one.
8. Versatility
Versatile means flexible. Modern computer can perform different kind of tasks one by one of
simultaneously. It is the most important feature of computer. At one moment your are playing game on
computer, the next moment you are composing and sending emails etc. In colleges and universities
computers are use to deliver lectures to the students. The talent of computer is dependent on the
software.
9. Communications
Today computer is mostly used to exchange messages or data through computer networks all over the
world. For example the information can be received or send throug the internet with the help of
computer. It is most important feature of the modern information technology.
10. Diligence
A computer can continually work for hours without creating any error. It does not get tired while working
after hours of work it performs the operations with the same accuracy as well as speed as the first one.
11. No Feelings
Computer is an electronic machine. It has no feelings. It detects objects on the basis of instructions given
to it. Based on our feelings, taste, knowledge and experience: we can make certain decisions and
judgments in our daily life. On the other hand, computer can not make such judgments on their own.
Their judgments are totally based on instructions given to them.
12. Consistency
People often have difficulty to repeat their instructions again and again. For example, a lecturer feels
difficulty to repeat a same lecture in a class room again and again. Computer can repeat actions
consistently (again and again) without loosing its concentration:
To run a spell checker (built into a word processor) for checking spellings in a document.
To play multimedia animations for training purposes.
To deliver a lecture through computer in a class room etc.

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A computer will carry out the activity with the same way every time. You can listen a lecture or perform
any action again and again.
13. Precision
Computers are not only fast and consistent but they also perform operations very accurately and
precisely. For example, in manual calculations and rounding fractional values (That is value with decimal
point can change the actual result). In computer however, you can keep the accuracy and precision upto
the level, you desire. The length calculations remain always accurate.

Computer is playing very important role in every field of life. Computers are everywhere such as at
home, at school. In daily life a large number of activities are dependent on computers. The main fields
where computer is playing very important role are:
1. Education
Education is the process of developing knowledge through instructions. The instructions are received
from people such as parents, teachers etc. and from printed material such as books, journals etc. Today,
the modern technique to get knowledge is by using computers.
All schools use computers in classrooms and labs to teach students. Many educators prefer to deliver
their lectures by computer-based presentations. In schools, colleges and universities, students use
software packages to complete their assignments.
The computer-based training (CBT) or presentation is also called computer aided instruction (CAI). In this
method, computer is used as an aid to teach the students in the classroom. The instructions of particular
subject are received from the instructions that uses a program presented by a computer as learning
medium. The web-based training (WBT) is another type of CBT that uses internet technology. It means
that many websites provides online education. A lot of material of different topics is available on these
websites. They also provide online lectures and tutorials for the students. The CBT and WBT are used in
business education centers to educate people. People can get knowledge at very low cost as well as in
very short period of time. Most of the WBT is free of cost.
Eductainment is another type of CBT. It is a type of educational software that combines the education
with entertainment. These software are available on CD-ROMs and DVD-ROMs and teach children in a fun
and in exciting way. Similarly typein is learnt through these types of software.
2. Entertainment

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Computer has also played a very important role for the entertainment of humans. Computer has become
need of humans for entertainment at their home. Formexample, to play video games at home, different
game software are available to play games. Similarly, software are available to see movie films and to
listen music. Today the movie files and famous songs are mostly available on CDs or on the web at very
low cost. You can listen music while you work on the computer.
On the web, you can view fine art images in online museums and galleries. Some artists sell their works
online and others display them for your viewing pleasure.
E-Commerce
E-commerce (electronic commerce) of e-trade or e-business is a financial business transaction conducted
electronically between business partners over computer network (such as on Internet). With e-
commerce, transactions can occur instantaneously and globally. This saves time for participants on both
ends. The users can buy, sell and exchange of products or services via computer network. Today, many
mobile computers can also access the internet on wireless.
There are many applications of e-commerce such as home banking, buying stocks, collaborating
electronically with business partners around the globe, marketing and advertising products, providing
services to the customers etc.
There are several types of e-commerce like collaborative commerce business-to-commerce, consumer-to-
consumer, mobile commerce etc.
The following services are mostly used in e-commerce or e-business.
(i) E-Mail
It is the most popular service through which we can electronically send and receive messages anywhere in
the world. The spoken messages are sent and received through voice mail.
(ii) Video Conferencing
A video conference is a meeting between two or more people residing at various places. They can watch
and talk with each other. They use a network (i.e. Internet). To participate in a video conference, you
need a video camera, a microphone, speaker and software (sepcial video conferencing software). Video
conferencing also need a computer with a large memory and fast processor.
Video conferencing provides a complete simulation of a normal meeting environment, enabling both
parties to see, hear and present material, just as if they are in the same room.
(iii) Electronic Shopping (E-Shopping)
Many businesses now have websites that allow internet users to buy goods or services. Shopping can take
place using a computer at home, or at a cybercafe. The e-shop can be anywhere in the world and it
remains open 24 hours a day. You can purchase any goods such as books, software, movies, computers,
cars, airline tickets etc. on the web.
(iv) Electronic Banking
One of the most popular uses of e-commerce is electronic banking. An electronic banking is also known as
cyber-banking. It includes various banking activities conducted from home, a business, or on the road
instead of a physical bank location. In all over the world, about 95 percent banks are online.
4. Health Care
Nearly every area of the medical field uses computers, such as laboratories, researches, scanning,
monitoring, pharmacy etc., which are helping the doctors to diagnose diseases and many other purposes.
The main uses of computer in medical field are described below:
(i) Maintaining Patient History and Other Records
The complete bio-data as well as medical history of patient is recorded into the computer before check up
of patient. The complete medical history (current and previous) is delivered to the related doctor for the
check up of patient. In this way, much of the doctor’s time is saved.

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In addition to patient history, other information about doctors, medicines, chemicals and equipments is
also maintained. It is very easy and efficient way to organize records than paper-based records. Any
information about patients, doctors, equipments etc. can be retrieved verybeasity and quickly. In
hospitals, mostly all the medical wards are interconnected through network. For example, if a patient is
allocated a specific ward but being examined by a consultant and receiving treatment in other areas
(wards) of the hospital, his detail can be viewed and updated at any terminal on the hospital’s LAN
network.
(ii) Patient Monitoring
The electronic scanning units (medical equipments) used in hospital can also be attached to computers.
These are very expensive and are used to monitor the patient continuously. Thus computers are normally
used in the following medical units of hospitals.
ICU (Intensive Care Unit)
Operation Theater
Recovery Room
Medical Ward
EGG (Electrocardiograph)
The medical equipment with sensors attached to the patient that detects changes of heart rate, pulse
rate, blood pressure, breathing and brain activity. If any unbalancing situation occurs, computer activates
the alarming device, which creates sound and alerts the medical staff. The data is also logged and used to
analyze the change in a patient’s condition over a period of time.
(iii) Diagnosis of Diseases
Computer is also used in hospital for diagnosis. For example, laboratory tests on blood and tissue
chemistry have become dependent on computer analysis.
One common use of computer is hospital is to scan the body of patient. A special scanner is used for this
purpose. A scanner sends electromagnetic rays through a patient body and sensors detect that how much
patient’s body have affected to any type of cancer (or disease). For example, the CAT (Computerized Axial
Topography) scanner passes rays over the patient. A CAT scanner takes many X-rays around the body. It
displays an image that enables physicians to look beneath the patient’s skin. As the scanner passes over
the patient, it displays and image of bone and tissue structure of patient on a computer screen.
(iv) Telemedicine
Another improvement in the medical field is the telemedicne. In telemedicine, you can access medical
care centers using computers videoconferencing.
(v) Computer-Aided Surgery (CAS)
Many surgeons also use computer aided surgery while they are in training. It is used to learn surgical
techniques. The physicians and dentists also use the computer aided learning (CAL) program.
Many websites also provide up-to-date medical, fitness, etc. information. These websites also maintain
databases about various problems and their solutions. There are also medical chat rooms on the internet
5. Science
Computer is used in all branches of science to collect and analyze data. The scientists also use internet to
collect the latest information around the world. Today, it is impossible to carry out scientific researches
without use of computers. In all branches of science, it is mainly used to get accurate experimental
results, for example to tget accurate
6. Publishing
In the field of publishing, computer is playing very important role such as to publish the books, magazines
and newspapers etc. The publishers use computer and word processors and graphics software to design
pages of the books or magazines. Many writes and publishers use Internet to collect information that is

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used for compliling a new book of magazine. Some websites allow you to download and entire book,
called an electronic book (e-book). The journalists also use the notebook computers and digital cameras
to capture and record news.

. Traveling
Computer is also playing very important role in traveling by car or airplane to arrive easily and safely at
your destination. Today many vehicles manufactured use special electronic equipments in the car that
controls various activities of the car. These cars have GPS (Global Positioning System) receiver that
reports your vehicle’s location. These cars also have “Onboard Navigation Systems” that have the
following featuers.
Track the vehicle if it is stolen
Provide emergency services
Provide directions
Provide roadside assistance
Perform remote diagnostics if a warning light appears on the dashboard
To make hotel and restaurant reservations

Today many vehicles also include options such as screens with e-mail and internet access, printers, fax
capability etc. Airlines also provide online access. The passengers can connect their notebook or hand
held computer to the web during their flights. Some airlines also provide web surfing devices to their
passenger during their flights.
Computer are also used in cars to monitor fluid levels, temperatures, electrical systems etc. It is also used
to monitor the air traffic etc.
8. Government
A government runs the country by making policies and provides citizens with up-to-date information.
Most of the government departments have their own websites. The computers are used in all
government departments have their own websites. The computers are used in all government offices to
perform various activities. The government agencies use computers as part of their daily routine.
9. Home
Like other electronic devices used in home such as T.V. set, washing machine etc. computer has also
become the need of every person at home. It is used at home as an educational tool for children. But it is
also used at home to keep records, write letters, prepare budgets, connect with others to send and get
information on the internet, to watch films and to listen music or other entertainment etc.
10 Agriculture
In agriculture field also, computer is playing very important role. The agricultural scientists are computer
for analyzing the agricultural data. The students of agriculture also uses computer to get latest
information about agriculture on the internet. The farmers also use computer to get information about
crops and to calculate bills and cost per acre as well as to get information about crops market prices.
11. Energy
Energy companies use computers to locate or search oil, coal, natural gas and uranium. Similarly electric
power companies use computers to monitor the power networks. In addition, meter readers use hand
held computers to record the units consumed in homes and business.

12. Industry

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In industry, computers are used to control the manufacturing system and continuous running of the
machinery. These also help in monitoring temperature [pressure, check the quality and accuracy and
measurement needed in the manufacturing process.
In industry, robots are used to perform most of the activities as mentioned above. A robot is an automatic
programmable machine that moves and preforms mechanical tasks. It means that a robot acts like human
beings. Robot can work in environment that is dangerous for human being such as opening chemical
packages and packages believed to contain bombs. It can perform repetitive tasks continuously without
any break, at very high accuracy than human. Robots can also be used in hundreds of applications such
as:
Assembling & spray-painting cars
Lifting of heavy equipments, power cables etc.
Testing blood samples
Performing experiments in artificial satellites and radioactive environment etc.

Society has reaped many benefits from using computers. A user is anyone who communicates with
a computer or utilizes the information it generates. Both business and home users can make
wellinformed
decisions because they have instant access to information from anywhere in the world.
Students, another type of user, have more tools to assist them in the learning process.
Advantages of Using Computers
The benefits from using computers are possible because computers have the advantages of speed,
reliability, consistency, storage, and communications.
• Speed: When data, instructions, and information flow along electronic circuits in a computer,
they travel at incredibly fast speeds. Many computers process billions or trillions of operations in
a single second.
• Reliability: The electronic components in modern computers are dependable and reliable
because they rarely break or fail.
• Consistency: Given the same input and processes, a computer will produce the same results —
consistently. Computers generate error-free results, provided the input is correct and the
instructions work.
• Storage: Computers store enormous amounts of data and make this data available for processing
anytime it is needed.
• Communications: Most computers today can communicate with other computers, often
wirelessly. Computers allow users to communicate with one another.
Disadvantages of Using Computers
Some disadvantages of computers relate to the violation of privacy, public safety, the impact on
the labor force, health risks, and the impact on the environment.
• Violation of Privacy: In many instances, where personal and confidential records stored on
computers were not protected properly, individuals have found their privacy violated and
identities stolen.
• Public Safety: Adults, teens, and children around the world are using computers to share publicly
their photos, videos, journals, music, and other personal information. Some of these unsuspecting,
innocent computer users have fallen victim to crimes committed by dangerous strangers.
• Impact on Labor Force: Although computers have improved productivity and created an entire
industry with hundreds of thousands of new jobs, the skills of millions of employees have been

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replaced by computers. Thus, it is crucial that workers keep their education up-to-date. A separate
impact on the labor force is that some companies are outsourcing jobs to foreign countries
instead of keeping their homeland labor force employed.
• Health Risks: Prolonged or improper computer use can lead to health injuries or disorders.
Computer users can protect themselves from health risks through proper workplace design, good
posture while at the computer, and appropriately spaced work breaks. Two behavioral health risks
are computer addiction and technology overload. Computer addiction occurs when someone
becomes obsessed with using a computer. Individuals suffering from technology overload feel
distressed when deprived of computers and mobile devices.
• Impact on Environment: Computer manufacturing processes and computer waste are depleting
natural resources and polluting the environ ment. Green computing involves reducing the
electricity consumed and environmental waste generated when using a computer. Strategies that
support green computing in clude recycling, regulating manufacturing processes, extending the
life of com puters, and immediately donating or properly disposing of replaced computers.

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