The next significant effort devising an electromechanical
computer was made at the Harward University, jointly sponsored by IBM and the
Department of UN Navy. Howard Aiken of Harward University developed a system
called Mark-I in 1944, Mark-1 was a decimal machine.
Mark-I was about
15 meter long. The wire connecting various parts of the machine were about 800
kilometers in length.
Classification of Computer according to the technology used:
The term generation is used to generally characterize the
major developments in the field of computer industry. Hence, there is no
clear-cut separating line between the generations. Two generations may overlap
in their tenures and technologies.
FIRST GENERATION OF COMPUTERS (1942-1955)
Eckert and Mauchly developed the first electronic computer
ENIAC (Electronic Numerical Integrator and Calculator) in 1946 in the USA. It
used high-speed vacuum tubes as switching devices and had a very small memory.
In 1946, Prof. John V. Neumann proposed the concept of stored programming.
Using this principle, Prof. Marvrive Wilkes developed a computer in 1949 known
as EDSAC (Electronic Delay Storage
Automatic Calculator). The first commercial production of stored electronic
computers was UNIVAC (Universal Automatic Computer).
CHARACTERISTICS
*Vaccum time circuit.
*Continuous maintenance required.
*Punched-card and paper- tape secondary storage.
*Dump primary storage.
* Machine and symbolic language programming.
* Different Computers for Scientific and business
applications.
*Batch processing.
*Generated considerable heat.
*Poor reliability
*Limited internet storage
capacity.
* First commercial computer to be used.
* Slow Input/Output operations.
*Computer programmed with machine language.
Example:
ENIAC, EDVAC, EDSAC & UNIVACI.
SECOND GENERATION OF COMPUTERS (1955-1963)
The second generation of computers started with the advent
of transistors. Transistors was invented jointly by John Burdeen Walter
H.Brattain and William B. Shockley, in the Bell Telephones Laboratories. Vacuum
tubes were replaced by transistors which is a two state device made from
Silicon. It is cheaper as well as smaller.
CHARACTERISTICS
* Used transistors instead of Vacuum tubes.
* Smaller in size and used less power.
*Had less heat production rate.
*Comparatively faster and reliable.
*Cheaper than first generation of computers.
*Had all the components of modern computers, printers,
memory, operating systems and storing devices.
*Introduced the concept of programming language like COBOL,
FORTRAN etcc.
*Can be shifted to other place easily.
Example:
IBM-700 and 1401, ATLAS and ICL 1901.
THIRD GENERATION OF COMPUTERS(1964-1975)
Though transistors were an improvement over the vacuum
tubes, they still generated a great deal of heat which damages the computers sensitive
internal parts . To solve this problem, integrated circuits (I.C) was invented
by Jack Kilby who was an engineer with Taxes Instrument. IC was developed in
1960. A single IC replaced a number of transistors because all the functions
were performed by a single IC.
CHARACTERISTICS
*Used Integrated Circuits (IC's).
* Decreased in size and weight
*Very reliable.
*On-line, real time processing.
*Cheaper than earlier computers.
*Faster than earlier computers.
*Improved input and output devices.
*Can easily be replaced and maintained.
*Concept of multi-programming was used.
*Better storage device (tapes).
Example:
IBM/360/370.NCR 395 and Burroughs B6500.
FOURTH GENERATION OF COMPUTERS(1975 onwards)
The computers of this generations have been improved by
reducing the size of IC. The large number of IC'S can fill into a small area.
This led to the invention of microchip. With a technique known as Large Scale
Integration (LSI), hundreds of components were combined into a chips instead of
IC.
CHARACTERISTICS
*Used microchip with a technique known as very large scale
integration.
*Reduced considerably in size.
*Low in cost , affordable to common man.
*Efficiency increased due to operating systems and
programming languages.
*Increased memory capacity.
*Work with great speed.
*Developed network of computers.
FIFTH GENERATION OF COMPUTERS
Computers scientists and engineers are now talking about
developing fifth generation computers that can think. These computers are
supposed to be based on Artificial Intelligence (AI). With the use of
artificial intelligence, computer can hold conversations with its human
operations and can also learn from its own experience. The fifth generation
computers will be efficient to translate foreign languages.
These
computers will takes several more years to come into existence.
The regular inventions in the world of computers has made it
difficult to classify computers. Yet they are classified according to their
capacities. The terms micro, mini, mainframe and super computers are widely in
use.
TYPE OF COMPUTERS
Different type of computers can be classified as:
1. Micro Computers/PCs
2. Mini Computers
3. Mainframe Computers
4.Super Computers
The above classification of computers is based on the internal
memory and speed of processing.
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