Computer can classified in to five types according to generations i.e time period

. First generation computer

. Second generation computer

. Third generation computer

. Fourth generation computer

. Fifth generation computer

. First generation computer

Period : 1945 – 1956

Inviter : Lee de Forest

Main processing device : Vacuum tubes

Vacuum tube

Vacuum tube

Vacuum tube

Vacuum tube

Vacuum tubes

Observing Vacuum tube

Observing Vacuum tube

Vacuum tube tester

Punched curds

Punched card voting

Punched card decks

Punched cards models

Large punched cards

. First generation computerAdvantages :

. It was only electronic device

. First device to hold memory

Disadvantages :

. Too bulky i.e large in size

. Vacuum tubes burn frequently

. They were producing heat

. Maintenance problems

Too bulky i.e. large in size

Vacuum tubes burn frequently

Maintenance problems

. Second generation computer

Period : 1956 – 1963

Inviter : William Shockley

Main processing device : Transistor

Storage media : Magnetic disc

Transistor

1 2

Transistor board

. Second generation computer

Advantages :

. Size reduced considerably

. The very fast

. Very much reliable

Disadvantages :

. They over heated quickly

. Maintenance problems

. Third generation computer

Period : 1964 – 1971

Inviter : Jack Kilby

Robert Noyce

Main processing device : IC (integrated circuit)

Storage media : Floppies

IC (integrated circuit)

ICs (integrated circuits)

IC (integrated circuit)

. Third generation computer

Advantages :

. ICs are very small in size

. Improved performance

. Production cost cheap

Disadvantages :

. ICs are sophisticated

. Fourth generation computer

Period : 1971– present

Inviter : Ted Hoff

Main processing device : ICs with VLSI

(Very Large Scale Integration)

Storage media : Floppies, CDs.

ICs with VLSI(Very Large Scale

Integration)

. Fourth generation computer

Advantages :

. It is a compact

. Less power consumption

. Production cost is cheapDisadvantages :

. No artificial intelligent.

. Fifth generation computer

Period : present and beyond

Main processing device : ICs with parallel processing

Storage media : Video disks

Advantages : . Artificial intelligence . Expert system

. First generation computer. Second generation computer

. Third generation computer. Fourth generation computer

. Fifth generation computer

Vacuum tubes Transistors

ICsICs with VLSI

ICs with parallel processing

Computer is a group of electronic devices used to process the data.

The characteristics of a computer are:

4. Accuracy5. Automation 6. Functionality 7. Tirelessness

1. Speed 2. Reliability 3. Memory capacity

1. Speed: computer process the data at an unimaginable speed. The speed of the computer ranges up to Nano seconds.

2. Reliability: The next important characteristic of a computer is its reliability. we can always rely on the information given by a computer.

3. Memory capacity: The memory capacity of a computer is measured in in bits and bytes. Large amount of the data can be stored in computer and retrieved. Memory capacity of the computer ranges in Giga bytes.

4. Accuracy: Accuracy of the computer is very high it performs calculation with greater accuracy

in less time.

5. Automation: a computer allows automation for any process designed in the from of a program. A program can be executed any number of times to repeat the process.

6. functionality: computer can performs many kinds

of jobs. They not process the data but also can be

Used for plying music, movies, and printing jobs.

It finds its applications in all most all the fields.

7. Tirelessness: A computer never gate tired.