Types Of Computers

 

A)Classified by its Purpose.

There are 3 main categories :-

1. Analog 

2.Digital 

3.Hybrid computers 

1.ANALOG COMPUTERS:

Analog computers are the computers that measures physical quantities like pressure , temperature etc. 

The best example for an analog computer is a thermometer.

2.DIGITAL COMPUTERS:

Digital computers are the computers that are used for counting digital devices.

Eg: digital calculator, digital watch ( Seven segment display )

3.HYBRID COMPUTERS

The features of analog and digital machines are combined to create a hybrid computing system.

Eg. Analog Cardiogram.

B) Classified by its Size and Performance:

These are classified into four categories:

1.Super Computer

2.Main Frame Computer

3.Mini Computer

4.Micro Computer

1.SUPER COMPUTER:

       Complex scientific applications like weather forecast require a large amount of data to be manipulated within a very short time. 

Eg. CRAY Computers.

2.MAIN FRAME COMPUTER:

       These are very large computers with a very high capacity of storage , because they can process large amount of data very quickly. These systems are used by big companies , government departments.

3.MINI COMPUTER:

       Mini Computers are powerful than micro computers and can support several users. They have larger RAM (Random Access Memory) and backing storage capacity and can process data more quickly.

Eg. PDP (Programmed Data Processor)

4)Micro computer:

Micro computer are at the lowest end of the computer. The special purpose of using micro computer is to control washing machines.

C) Generations of Computer:

These are totally five generations known till today. They are given below

1.First Generation (1942-1955)

2.Second Generation (1955-1964)

3.Third Generation (1964-1975)

4.Fourth Generation (1975 Onwards)

5.Fifth Generation ( present and Future Generation )

1.First Generation(1942-1955):

In first generation computer, vacuum tubes were used as the main component. Due to the large size of vacuum tubes, these computers were very large in size with limited memory.

ex:1.ENIAC(Electronic Numerical Integrator And Calculator)

2.EDVAC(Electronic Discreet Variable Automatic Computer)

3.EDSAC(Electronic Delay Storage Automatic Calculator)

Features of First Generation computer:

1.Electronic circuitry used is vacuum tubes.

2.Slow operating speed, high electricity consumption and large heat generation.

3.Air conditioning required.

4.Continous maintenance was required.

5.Very bulky in size so unreliable and non-portable.

6.Limited programming capabilities i.e machine and assembly language.

2.Second Generation:- (1955-1964)

Second generation computers used transistors in place of Vacuum tubes, which were made up of semi- conductor material. The size of this computer is comparatively very small as compared to first generation computer due to the small size of transistors.

Example: IBM 7000 series and honey well 200 series.

Features of Second Generation computers:

1. Electronic circuits are used in transistors.

2. Due to their small size, they are more reliable and portable.

3. Computational time is in micro seconds  (10-6sec).

4. Less heat generated.

5. Required power to operate.

6. Faster than first generation.

7. Higher level languages were used.

3.Third Generation:- (1964-1975)

Integrated circuits are used here. On this chip, a very large number of components are integrated on very small surface. Due to this, the size of this generation computers is much smaller than first two generation computers

Example: IBM-360 series and ICL-1900 series

Features of Third Generation Computers:

1. The electronic circuit used in integrated circuits (IC)

2. Smaller in size

3. Increased speed and reliability

4. A very low heat generated

5. Computational time is reduced to Nano seconds

6. Maintenance cost is low and portable

7. Less power requirement

8. More advanced, high level languages like PASCAL, FORTRAN,COBOL, were used

4.Fourth Generation (1975 ONWARDS):

In this generation very large scale integrated circuits (VLSI) of about 5000 components on a single chip is used. so, the size is very small for this generation computers.

Example: IBM-370 and HP-3000.

Features of Fourth Generation Computers:

1. VLSI (very large scale integrated circuits) is the circuitry Used.

2. Smallest in size

3. Heart generated is minimum

4. Very reliable and much faster as compared to previous generations

5. No ago-conditioning required

6. Minimal maintenance required because hardware failure is negligible

7. Easily portable due to small

8. cheapest among all generations

5.Fifth Generation ( present and Future Generation ):

In The Generation , the main emphasis is on parallel processing and artificial intelligence to make the computers intelligent like human being . Here the  VLCI technology became ULSI ( Ultra Large Scale Integration Technology ) resulting in the production of micro processing chip having 10 million electronic components.

Ex: super computer 

Features of Fifth Generation Computers:

1.ULSI technology ( Ultra large scale integration ).

2.Availaibility of very powerful and compact computer at a very cheap rate .

3.Development of true artificial intelligence.

4.Advancement in super conductor technologies.

5.More use of friendly with multimedia features.