1. Computer Generations First Generation (1942-1955)
Second Generation( )
Third Generation( )
Forth Generation( )
Fifth Generation(1989-present)

2. First Generation ( )
The vacuum tubes were used in the circuits of these computers.
As vacuum tubes used filaments, they had limited life.
Consumed about half a watt of power. Power consumption of these computers was very high as they used more than 10,000 vacuum tubes.

3. First Generation ( )
The input and output operations were done using punched card technology.
For external storage, magnetic tapes were used.
Too bulky in size, requiring large rooms for installation.
The machine was capable to do one job at a time, therefore batch processing was adopted.
The language used by these computers was machine language and assembly language.
Example of Computers: ENIAC,EDVAC,EDSAC, IBM 650 etc.

4. Second Generation (1955-1964) Transistors were used in the circuits.
More powerful and reliable than vacuum tubes.
Consumed less power and dissipated less heat than the first generation computers but
still room required to be air
conditioned.
Less prone to hardware failures
than first generation computers.

5. Second Generation ( )
The input operations were performed using punched cards and magnetic tapes and for output operations, punched cards and papers were used.
For external storage magnetic tapes were used.
The orientation was towards multiple users i.e. the machine was capable to process multiple tasks concurrently.
The high level languages like FORTRAN, COBOL, BASIC etc. were used as the languages by the computer.
Example of Computers: UNIVAC LARC, IBM 1400 and series, General Electric 635 etc.

6. Third Generation( )
Integrated circuits replaced transistors. Inspite of their smaller size they were capable to perform better than transistors.
Consumed less power and dissipated less heat than second generation computers.

7. Third Generation( )
For data input and output operations monitors and keyboards replaced the punched cards.
For external storage magnetic disks were used.
Timesharing operating systems were capable of handling several jobs concurrently were used.
Suitable for both scientific and commercial applications.
More advanced high level languages like PASCAL were used.
Example of computers: IBM System

8. Fourth Generation( )
The circuits used VLSI and microprocessors of virtually microscopic size, which led to drastic cut on the size of computer.
Micro computers have evolved.
Did not require manual assembly of individual components into electronic
circuits.
The input output devices were
the same monitors, keyboard,
printer etc.
Use of standard high level
languages.

9. Fourth Generation( )
Magnetic disks were the primary devices used for external storage.
Graphical user interface(GUI) enabled new users to quickly learn how to use computers.
PC based applications made PCs popular for both office and home usage.
Network of computers enabled sharing of resources like disks, printers among multiple computers.
Affordable for personal use at home.
Example of computers: IBM Systems

10. Fifth Generation(1989-Present)
The computers of this generation use optic fibre technology to handle Artificial Intelligence.
These computers have capacity to think and reason which can be used to solve problems where human intelligence is required.
Expert Systems are examples of systems implementing Artificial Intelligence (AI).
Less prone to hardware failures than their predecessors were so negligible maintenance cost.
User friendly interfaces with multimedia features.