Classification of Computers

A) Analog Computers

·         Analog computers are used to process continuous data

·         An analog computer measures continuously instead of counting.

·         Output is in the form of graph.

·         Limited memory.

·         Speed is low

·         Accuracy is poor

·          All the analog computers are special purpose computers.

B) Digital Computers

•      Digital computer represents physical quantities with the help of digits or numbers

•      These numbers are used to perform Arithmetic calculations and also make logical decision to reach a conclusion, depending on, the data they receive from the user.

•      Better Accuracy

•      Larger Memory Space

•      Processing Speed is Faster

•      Used for business, Industries, etc

C) Hybrid Computers

Various specifically designed computers are with both digital and analog characteristics combining the advantages of analog and digital computers when working as a system. Hybrid computers are being used extensively in process control system where it is necessary to have a close representation with the physical world.

The hybrid system provides the good precision that can be attained with analog computers and the greater control that is possible with digital computers, plus the ability to accept the input data in either form.

1. Super Computers

2. Main Frame Computers

3. Mini Computers

4. Micro Computers

1. Super Computers E.g.:- CRAY Research :- CRAY-1 & CRAY-2, Fujitsu (VP2000), Hitachi (S820), NEC (SX20), PARAM 10000 by C-DAC, Anupam by BARC, PACE Series by DRDO

􀂃 Most powerful Computer system - needs a large room

􀂃 Minimum world length is 64 bits

􀂃 CPU speed: 100 MIPS

􀂃 Equivalent to 4000 computers

􀂃 High cost: 4 – 5 millions

􀂃 Able to handle large amount of data

􀂃 High power consumption

􀂃 High precision

􀂃 Large and fast memory (Primary and Secondary)

􀂃 Uses multiprocessing and parallel processing

􀂃 Supports multi-programming

2. Main Frame Computers E.g.:- IBM 3000 series, Burroughs B7900, Univac 1180, DEC

􀂃 Able to process large amount of data at very high speed

􀂃 Supports multi-user facility

􀂃 Number of processors varies from one to six.

􀂃 Cost: 3500 to many million dollars

􀂃 Kept in air conditioned room to keep them cool

􀂃 Supports many I/O and auxiliary storage devices

􀂃 Supports network of terminals 

3. Mini Computers E.g.:- Digital Equipment PDP 11/45 and VAX 11)

􀂃 Perform better than micros

􀂃 Large in size and costlier than micros

􀂃 Designed to support more than one user at a time

􀂃 Posses large storage capacities and operates at higher speed

􀂃 Support faster peripheral devices like high speed printers

􀂃 Can also communicate with main frames

4. Micro Computers E.g.:- IBM PC, PS/2 and Apple Macintosh

􀂃 A microcomputer uses a microprocessor as its central Processing Unit. Microcomputers are tiny computers that can vary in size from a single chip to the size of a desktop model

􀂃 They are designed to be used by only one person at a time

􀂃 Small to medium data storage capacities 500MB – 2GB

􀂃 The common examples of microcomputers are chips used in washing machines, TVs, Cars and Note book/Personal computers.