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e\L-lovely-eng\comm4-1.pmd IInd 16-9-11 IIIrd 27-12-11 IVth 4-1-12

Information and Communication Technology Applications

Figure 4.1: Classification of Computers Based on Different Criteria
Notes
Classification of Computers
Based on

Purpose Technology Used Size & Capacity History

Analog Super
Computers Computers
General Purpose Mainframe
Computers Computers
Digital
Computers
Mini
Computers
Micro
Special Purpose Hybrid Computers
Computers Computers
(PCs)

First Second Third Fourth Fifth
Generation Generation Generation Generation Generation
Computers Computers Computers Computers Computers

4.1.1 Based on Purpose

According to the utilisation of computer for different uses, computers are of the following two
types :
(i) General Purpose Computers. Computers that follow instructions for general requirements such
as sales analysis, financial accounting, invoicing, inventory, management information etc. are called
General Purpose Computers. Almost all computers used in offices for commercial, educational and
other applications are general purpose computers.
(ii) Special Purpose Computers. Computers that are designed from scratch to perform special tasks
like scientific applications and research, weather forecasting, space applications, medical diagnostics,
etc. are called Special Purpose Computers.

4.1.2 Based on Technology Used

According to the technology used, computers are of the following three types:
(i) Analog Computers. Analog computers are special purpose computers that represent and store
data in continuously varying physical quantities such as current, voltage or frequency. These
computers are programmed for measuring physical quantities like pressure, temperature, speed
etc. and to perform computations on these measurements. Analog computers are mainly used for
scientific and engineering applications. Some of the examples of analog computers are given below:
(a) Thermometer. It is a simple analog computer used to measure temperature. In thermometer, the
mercury moves up or down as the temperature varies.

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