• What is computer?
• Block diagram of
• Generation of computers
What is computer ?
Computer is an electronic machine that
takes input (data) analyze it process it
and give the desired output (information
). Also provide the capability of storing
data for future use.
Central Processing Unit
Responsible of all kind of processing.
Process the data according to the set of
instruction given by the user.
Three major parts of CPU
- Control Unit
- ALU ( Arithmetic and Logical Unit ).
Read instruction from the memory ,
decode it and send signal to various parts
of computer to perform the work
Control the sequence of instruction to be
Store intermediate results during program
Made up of flip- flop.
Categorize in two types
- General Purpose Register
- Dedicated Register
Generation of Computer
Basically 4 generation of computer
I Generation ( 1940 - 1956 ) :-
- Very big and bulky.
- Heating effect.
- Large electricity consumption.
- Work on 0’s and 1’s.
- Machine Dependent.
- Magnetic drum for storage.
- Input through punch card and output through
Example :- UNIVAC, ENIAC
2nd Generation of Computer
II Generation (1957-1963)
- Very small in size as compare to vacuum tube.
- Smaller in size, cheap, much more energy
- Magnetic core technology is used instead of
- Assembly Language instead of binary.
- Translators required.
- Input still taken by punch card and output by
- Programming is machine dependent.
Examples:- PDP-8, IBM 1401 and CDC 1604.
3rd Generation of Computer
III Generation (1964-1971)
Integrated Circuits ( ICs )
- Size of computer more compact, more
- Speed of computation become very high.
- SSI and MSI is used.
- Use of High Level Languages(COBOL, PASCAL
- Programming Languages are machine independent.
- Keyboards and mouse - input and monitors - output.
- Multiple task .
Examples:- IBM 370, PDP 11,IBM-360 series,Honeywell-6000
4th Generation of Computer
IV Generation (after 1971)
- Compact and light in weight, consume
- Very fast processing speed.
- Multitasking is possible.
- High level language is used such as
- Time-sharing , real time, and distributed
Example :- IBM system 3090, HP 9000