In today's world, the
use of computers has increased so rapidly that we can no longer
ignore them. Computers influence our lives one way or the other.
These days we see computers being used to perform several functions
that have made our life easy. The list of services for which
computers are used is a long one.
What is a Computer?
computer is an electric device that can accept store and process
information to produce the required results.
is essentially a problem solving machine. You can also use as
a typewriter for typing letters or a calculator for doing calculations.
computer has memory that can save a lot of information and can
take logical decisions like human beings.
Uses of Computers
Computers have a significant
impact on modern society. Nearly every profession uses computers
to a certain extent.
and Railway reservations
of blueprints for houses
Thus, you can see that computers have become very essential
part of life.
Benefits and Limitations
The various benefits of computers
Speed - Computers are very fast. The speed of the computer
is measured in terms of Million Instructions per Second (MIPS).
It represents the number of instructions that can be executed
by the computer per second.
- Computers are very accurate. If the input is correct,
they never make mistakes.
Diligence - Computers never get tired or bored of doing the same
task continuously. They work in the same manner all the time.
- A computer can store large amounts of information
in its memory.
- If a task has to be performed several times, the computer
needs to be instructed only once it automatically completes
A computer appears to
be far more intelligent and informed than human beings but the
fact is it cannot perform any task on its own. We need to give
the computer instructions on exactly what it has to do.
an unanticipated situation arises, computers will either produce
results or abandon the task altogether.
They do not have the potential to work alternate solutions.
History of Computers
is considered to be the first computer and was
invented 5,000 years ago by the Chinese.
basic purpose of the device is to make calculations.
consists of a rectangular frame with a number of strings attached.
string has a collection of beads. These beads are used to perform
is used even today to teach small children how to count.
Babbage’s Mechanical Computer
Charles Babbage invented
the first mechanical computer during the period 1830 to 1850.
This computer performed the basic arithmetic functions. It had
the following five components:
storage unit that holds the numbers.
arithmetic unit, called Mill, to perform the arithmetic calculations.
control unit that controls the activities of the computer.
input device that gives the numbers and instructions to the
output device that displays the result.
NOTE: Charles Babbage is referred to as
the ’Father of Computers’ due to his pioneering work.
The next device that
contributed to the evolution of computers was the punched cards.
These were cards made of special pulp paper. Machines were used
to make holes in the cards and thus store information. In addition,
storing machines were used to read these cards and collect data.
After the first mechanical
computer, the design of computers evolved over a period of time.
They were classified into generations:
The U.S. Census Bureau
developed the first business computer in the year 1951. This
computer was called Universal Automatic Computer (UNIVAC). It
used vacuum tube circuits for processing. The computers that
used vacuum tube circuits were called the First Generation Computers.
The vacuum tube circuits contained a filament that was heated
to emit electrons.
Bell Labs of U.S.A.
invented transistors that were used instead of vacuum tubes.
Transistors are electronic circuits that are small in size and
do not require any heating for emitting electrons. The computers
that used transistors were called the Second Generation Computers.
The Third Generation
Computers used large Scale Integrated (LSI) circuits for processing.
The LSI circuits were invented in the mid -1960s. LSI circuits
integrate several circuit components into a single chip.
Very Large Scale Integrated
(VLSI) chips were invented in the year 1969. The computers that
used VLSI chips were called the Fourth Generation Computers.
Recent research has
focused on developing “thinking computers”. These computers
are called the Fifth Generation Computers.
Computers can be classified
into microcomputers, minicomputers, mainframe computers and
supercomputers on the basis of the following:
·Speed of processing data
·Ability to handle input and output
- Microcomputers are also
called personal computers (PCs). These computers use microprocessors.
- They are small in size.
Also, they do not have large storage capacities.
- They can perform difficult
tasks. They are used mainly for desktop publishing, accounting,
statistical analysis, graphics designing and project management.
- Some examples are Apple
II, IBM PC, PS\2 and Macintosh.
are small general-purpose computers. These computers can perform
more complex tasks and cost more than microcomputers.
- They are larger in size
and they have small to medium storage capacity.
- They are used for processing
data and analyzing results of experiments. They are also used
for controlling and monitoring production processes.
- Some examples are PDP 11/42 and VAX 11.
are more powerful than minicomputers.
- They have high processing
speeds and can store large amounts of data. They are used
in wide area networks and support hundreds of users. However,
these computers consume more electricity.
- Some examples are IBM
3000 series and Univac 1180.
- Supercomputers are the
largest and fastest computers. They are also the costliest
- They are used in field
like science and defense. These computers are used for designing
and launching missiles, weather forecasting, biomedical research,
aircraft design and automobile design.
- They are only few supercomputers
throughout the world. India
owns a series of computers called PARAM
developed by C-DAC.
computers or PCs are the popular form of computers. Individuals
as well as organizations use these computers. The classification
of PCs is as follows:
The difference between portables and desktops is that
portables can be carried while traveling unlike desktops.
are small sized machines that have the same power of a desktop.
The weight of laptop is around 7 to 12 kg. The drawback of a
Laptop is that it is too bulky. Examples: Toshiba 5200C and
are similar than a laptop and are designed to overcome the drawbacks
of a laptop. They have the size of a notebook but are as powerful
as a desktop. They weigh 3 to 4 kg. Examples: Contura
3/20 and Acer Any Ware.
have the size of a pocket calculator. They are not as powerful
as a desktop; they support only a few applications. Example
A Personal Computer (PC) is a popular single-user system.
A single-user system can support only one user at a time.
A multi-user system is one that supports more than one
user at a time. It enables the users to run more than one program