First generation of computer:

The first generation of computer was developed around early 1950 i.e (1949-1956).
It had the following silent features:

1. It was very big in size like the size of room.
2. Very limited memory capacity.
3. Speed is low.
4. Consumed more electricity and generating more heat also.

Technology used:  vacume tube

Second generation  computers:

The second generation of computers was developed around 1956 i.e (1956-1965) with the replacement of vacume tube by transistor.
The feature’s are

1. The size was comparatively reduced.
2. It was faster and more reliable.
3. Speed was in term of micro second.
4. It was using better input/output devices.
5. It was needing less power and generating less heat
6. Memory was large.

Technology used : transistor which used in radios

Third generation computers:

It was developed around 1966-1975 with the concept of chips and had the following features:

1. very small in size.
2. Memory size was large.
3. Speed was quit fast in terms of nanoseconds .
4. Capability of multiprogramming concept

Technology used:  integrated circuit known as ic chips in place of transistors

Fourth generation computers:

The fourth generation of computers was developed in 1975(1975-present

1. it’s having the operating system with “virtual memory’ concept to write program in the memory more than the available memory.
2. Speed is very high
3. User interaction is vary fast.

Technology used : very large scale integrated circuit(VLSI)

The fifth generation computers are under development stage. This computers will use ULSI(ultra- large- scal integration) chip. ULSI chips contain million of components
into a single IC.