Generations of Computer.

The development of electronic computers can be divided into generations depending
upon the technologies. The generations of computer are as follows:

1. First Generation Computer(1942-1955)

The beginning of commercial computer age is from UNIVAC (Universal Automatic
Computer).It was developed by two scientists MAUCHLY and ECHERT at the Census
Department of United Statesin 1947. The first generation computers were used during 1942
-1955. They were based on vacuum tubes.Examples of first generation computers are
ENIVAC and UNIVAC-I etc.

Advantages.
*Vacuum tubes were the only electronic component available during those days.
*Vacuum tubes technology made possible to make electronic digital computers.
*These computers could calculate data in milliseconds.

Disadvantages.
*These computers were very large in size.
*They consumed a large amount of energy.
*They heated very soon due to thousands of vacuum tubes.
*They were not very reliable.
*Ari conditioning was required.
*Constant maintenance was required.
*Non-portable.
*Costly commercial production.
*Limited commercial use.
*Very slow speed.
*Limited programming capabilities.
*Used magnetic drums which provide very less data storage.
*Used punch cards for input.
*No versatile and very faulty.

2. Second Generation Computers(1955-1964)

The second generation computers used transistors. The scientists BELL LABORATORIES
developed transistor in 1947. These scientists include JOHN BARDEEN,WILLIAM
BRATTAIN and WILLIAM SHOCKLEY. The size of computer was decreased by replacing
vacuum tubes by transistors. The examples of second-generation computers are IBM 7094
series, IBM 1400 series and CDC 164 etc.

Advantages.
*Smaller in size as compared to fist generation computers.
*More reliable.
*Used less energy and were not heated.
*Wider commercial.
*Better portability.
*Better speed and could calculate data in microseconds.
*Used faster peripherals like tape drives, magnetic disks, printer etc.
*Used Assembly language instead of machine language.
*Accuracy improved.
Disadvantages.
*Air conditioning was required.
*Constant maintenance was required.
*Commercial production was difficult.
*Only used for specific purposes.
*Costly and not versatile.
*Punch cards were used for input.

3.Third Generation Computers(1964-1975)

  The third generation computers used integrated circuits (IC) Jack Kilby developed the 
 concept of integrated circuit in 1958. It was an important invention in computer filed.The
first IC was invented and used in 1961. The size of an IC is about 1/4 square inch.faster,
more reliable and less expensive. The examples of third-generation computer are IBM 370,
IBM System/360, UNIVAC 9000 etc.

Advantages.
*Smaller in size as compared to previous generation.
*More reliable.
*Used less energy.
*Produced less heat as compared to previous generation computer.
*Better speed and could calculate data in nanoseconds.
*Used fan for heat discharge to prevent damage.
*Maintenance cost was low because hardware failure is rare.
*Totally general purpose.
*Could be used for high-level languages.
*Good storage.
*Versatile to an extent.
*Less expensive.
*Better accuracy.

 4.Fourth Generation Computers(1975-Present)                                                                               

The fourth generation computers started with the invention of microprocessor.The microprocessor contains

thousands OF ICs. Ted Hoff produced the first microprocessor in 1971 for Intel. It was known as Intel 4004. the technology of integrate circuits improved rapidly. The LSI (Large Scale Integration) circuit and VLSI (Very Scale Integration)circuit were deassign. It greatly reduced the size of computer. The size of modernmicroprocessors is usually one square inch. It can contain millions of electronic circuits. The examples of fourth generation computers are Apply Macintosh and IBM PC.

Advantages.
*More powerful and reliable than previous generation.
*Very small in size.
*Less power consumption and less heat generated.
*Fan for heat discharging and thus to keep cold.
*No air conditioning is required.
*Best speed to read instructions i.e. one billionth per second.
*Totally general purpose.
*Commercial production.
*Less need of repairing.
*Cheapest among all generations.
*All types of high-level languages can be used in this type of computers.
Disadvantages.
*The latest technology is required for manufacturing microprocessors.

5. Fifth Generation(Present and Beyond)

Scientists are now working on the 5th generation computers using recent engineering advances.
It is based on the technique of Artificial Intelligence(AI). Computers recent engineering under
stand spoken words instructions and imitate human reasoning. The ability to translate a foreign
language is also moderately possible with

Fifth generation computers.

Scientists are working to increase the speed of the computer.they are trying to create a
computer with real IQ with the help of advanced programming and technologies. The in
modern technologies will revolutionize the computer in future.