Classification of computer

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7 Νοε 2013 (πριν από 4 χρόνια και 8 μήνες)

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Classification of computer

Computers can be classified as follows.

According to function

According to purpose

According to capabilities

According to function

According to function computers can be
classified into four types. These
classification of computer based on
principle of operation and hardware

Digital Computer

Analog Computer

Hybrid Computer

Digital Computer

A Digital computer works with data in term of
discrete number or digit. These number are
used to perform, arithmetic calculations and
also make logical decision to reach a
conclusion depending on the data they
receive from the user. All the expressions
are coded into binary digits (0 and 1) inside
the computer and it manipulates them at
very fast speed.

A digital computer manipulates data
according to the instructions or
programme given to it in a certain
computer language.

The instructions and data are fed to the
computer in the form of discrete electrical
signals. Digital Computers are easy to
program and are in general purpose use.
Almost all personal computers (PCs)
belong to this category.

Analog Computer

Analog computers actually is a measuring
device. An analog computer measures
continues type of data and use a physical
quantity, such as electric current, speed,
weight etc. Analog Computers are the first
Computers being developed & provide the
base for the development of modern
digital computers. These computers are
mainly made of electrical devices like
resisters, amplifiers & transistors.

This machine has a very limited memory & can
perform only certain type of calculations, which
make it specialized machine, suitable for
engineering & scientific calculations. An analog
computer is basically a device for solving
ordinary differential equations and can be used
in solution in solution of those problems which
can be converted to ordinary differential
equations. In general, Analog computer are
very fast in processing because all the

operations performed in this machine are
parallel but accuracy of these machines is
quite low. Speedometer and millimeter
(used in vehicles), Electric meter & Gas
meter (fixed on the supply line of the
house) pressure gauges & thermometers
are the general example of the analog

Hybrid Computer

A Hybrid computer is, which combines the
analog & digital capabilities in the same
computer system. Hybrid computers help
the user to exploit the machine's ability to
process both continuous and discrete
data. These machines are generally used
for scientific applications & it is also used
as a controlling device in an industrial

The results can be obtained either as
analog signal or discrete signal e.g.,
either as continuous output in the form of
graph discreet digits. This result can be
obtained by an electronic device
‘MODEM’. A modem is a device which can
transform analog signals to digital signals
and vice versa.

According to purpose.

Computer can be classified according to
purpose in two ways.

General Purpose

Special Purpose

General Purpose: These computer are
designed to solve wide variety of problems
from different fields. The hardware and the
software of such system are adaptable totally
different environments. These Computer are
used for different purpose like inventory
Control, Record keeping , Accounting, payroll

2. Special Purpose:

As the name suggests
these computers system are used only for
specific purposes or application. These
special purpose computer system may be
defined as a stored programme computer,
whose architecture is oriented towards one
or more specific applications. These
computers handle a very narrow categories
of data processing activities. Some example
of special purpose computer with their area
of application are as fallows.

Computer used for Process Control in an

medical X
ray instrument used only for

ECG machine which is used for ECG test

CCG machine which is used for CCG test

Electronic digital blood pressure instrument

Computer system used for desktop

Computer used for air
traffic control.

Computer system which is used in Robots.

According Capabilities

According to capabilities computers could
easily be classified into minis, micros
mainframes and super by considering their
size, performance and cost. However, today
these definitions are not so cut and dried,
due to the ever increasing pace of common
usage altogether. The manufactures are not
helping by bringing out many terms such as
mini super minis and micro mainframes etc.

These are obviously terms used to
describe the approximate position in the
hierarchy to which their products belong.
To understand this mass of jargon, it is still
necessary to understand the older
definitions of the terms minis , micros,
mainframes and super, now we will discus
these computers in detail the following.


This is quite simply, a computer which uses a
microprocessor is the name given to the very
complex chip which contains most of the basic
systems need to set up a computer system
using this single chip as the central processing
unit. In the late 1970s the first
Microcomputers were 8
bit machines.
(although some less
useful 4
microprocessors were available earlier. This
meant that their fundamental unit of data was
eight binary digits.


Thin is a medium
sized computer and can
vary in power from a very large and powerful
micro to a small mainframes. Indeed,
because of the increasing power of minis,
mainframes market has shrunk considerably
over the last few years. A minicomputer is
often a floor
standing model, although some
modem ones now fit onto the top of your

but there is not much space left for the
coffee pot !

A small minicomputer might be able to
support b/w ten & twenty users. It is ,
therefore, ideal for use
within a single
department within a college or university,
or far use in a medium size business.
They are really mini versions of the
mainframe computer, and this is where the
term mini was originally coined. The mini
has been designed with multi
user access
in mind & is therefore usually easy to
expand up to maximum possible
numbers of a users.

Mainframe computers

These are the largest of computer systems
(not necessarily the fastest or most

they certainly will not fit on the
top of your desk ! It is common to have
hundreds of simultaneous users on such a
system. There is usually a vast amount of
RAM, and any extra peripherals such as
tape & disk machines.

Super computers

There are the fastest & most expensive
modern computer systems. They are usually
not used for normal data processing, but for
intense mathematical calculations such as
forecasting the weather, or super high
resolution graphics such as ray
images. Nevertheless, for very large systems
such as the customs
clearance system in the
port of a development country, all the
government departments are linked to a
computer which is then able to

produce all the necessary documentation
for clearance in just a few minutes,
compared to several days under the older
manual systems.

There are also many complex scientific &
engineering applications which require
enormous processing speed & power.