2^nd  GENERATION:   In 2 generation there was transistors.

Advantages:

 Batter then first generation.

1. It occupy a half space.

2. Normal heat was generated.

3. Minimum 4 or 5 hardware engineers.

4. The system works for few months.

Disadvantages:

1.      A/c Requirement.

2.      Current waste.

3.      Money waste.

4.      Its derision era 1955 to 1965.

3 .GENERATION: ITS Integrated circuits.

1.      It occupy quarter space.

2.      Minimum 3 to 4 hardware engineers.

3.      The system works for few years.

DISADVANTAGES :-

1.      Normal heat was generated

2.      A/C requirement

3.      Current waste

4.      Money waste

5.      It’s derision era 1965 to 1975

4.GENERATION  V.L.S.I.C ( Very Large Scale Integrated Circuits )

Advantages :-

 Better than 1^st  and 2rd  are 3^rd generations