HISTORY & GENERATIONS
Ever since the man thought of counting, he developed the concept of communications. His initial approach to accounting and data computations and their recording was with help of sticks, pebbles or lines on walls of caves.Then he moved towards counting using ten fingers of his hands, which probably is the basis of present decimal system
The earliest computing device, which was used by Egyptians as early as 450 B.C., is ABACUS. The Chinese version of ABACUS was a bead on wires counting frame, which is still much is use in south east asia, China and Japan.
The first desktop calculator machine, which is capable to perform various arithmetic operations, was developed as early as 1642, which was pioneered by French scientist BLAISE PASCAL (1623-1662). This calculating machine mainly consisted of gears and wheels for calculations and this machine could perform only two basic operations i.e. addition and subtraction.
A German mathematician GOTTFRIED LEIBNITZ worked on improving this machine i.e. Pascal's calculator for performing four basic arithmetic operations (+,-,x,/).
Charles Babbage designed the early computer called difference engine in the year 1822. Which could produce reliable tables. He improved this machine and came out with a new idea of Analytical Engine in 1833, which could perform the basic arithmetic functions, which is intended to be completely automatic. This machine used punch cards as input output devices for basic input and output. He is called as "FATHER OF COMPUTERS".
In 1920, LEONARDO TORES demonstrated a digital calculating machine in Paris.
The concept of punched cards which was used by BABBAGE as I/O media, was developed further by HARMAN HOLLERITH in the year 1889. He is the founder of present IBM (International Business Machine) company.
As the demand for punched cards machine increased, there was inadequacy of these machine for scientific computations and this demand led to the development of electro mechanical calculators known as MARK-1, which was the first automatic general purpose digital computer which was able to do three additions per second, for multiplication it took about four seconds and about if took Aiken eleven seconds for division. This machine was designed by Prof. HOWARD AIKEN of Hardward University. This was in 1944.
The first electronic computer, ENIAC (Electronic Numerical Integrator And Calculator) was designed in 1946. It has capability to perform about 5,000 calculations per second. This was a huge computer which occupied about 1,500 sq.ft and weighed about 50 tons.
After ENIAC the next development was an electronic computer which was based on JOHN VON NEUMANN'S concept of stored program named as EDVAC (Electronic Discreate Variable Automatic Computer) and this was in 1949.
Almost simultaneously with EDVAC of U.S.A, the EDSAC (Electronic Delay Automatic Calculator) was developed by British scientists. This machine was capable to do mathematical operations which are executed in matter of a few micro seconds.
Then came in 1951 the commercial version of stored program computer UNIVAC (Universal Automatic Computer), which was first digital computer.
The development of computers has followed difference steps in the technology used and these steps of technological differences are called as generations.
FIRST GENERATION (1945-1960):
The first generation of computer were those computers which use Vacuum Tubes or Valves technology. Almost all the early computer like ENIAC, EDVAC, EDSAC etc. were made a reality only by the invention of vacuum tube, which is a fragile glass device that can control and amplify electronic signals. In this computer they are using 18,000
vacuum tubes, 70,000 resisters, 10,000 capacitors and 60,000 switches. It took 150 kilo watt electric power and it produce large amount of heat. They were bulky and required large space. They had small primitive memories and no auxiliary storage.
SECOND GENERATION (1960-1965):
With the development of transistors and their use in circuits, magnetic core for memory storage, the vacuum tubes of first generation are replaced by transistors to arrive at second generation of computers. The size of transistors is much smaller when compared to vacuum tubes. They consumed less power generated less heat and are faster and reliable. William B Shickley, John Burdeen and Walter H Brattain are the scientists develop the transistors. They are working bell telephone, U.S.A. They got noble prize. The major advantage use of transistors was that the size of computer has come down as well as the power consumption. Even the cost of transistors is less in comparison with the cost of vacuum tubes, the cost of computer reduced drastically, they were more reliable then first generation computers. Fortran, cobol, snowbal, algol etc. like high level languages are developed in this generation. In this generation they are using magnetic tapes for storing.
THIRD GENERATION (1965-1975):
With the development of silicon chips. The third generation of computers came into existence. These computers used compact integrated circuits (IC's) of silicon chips in place of transistors. Each of these IC's consisted of large number of chips in very small packages. With these IC's coming into picture the size of computers, cost, heat generation and power consumption decreased to a great extent, speed and reliability increased as compared to previous generations. These machines used IC's with LSI (Large Scale Integration).
FOURTH GENERATION (FROM 1975):
The computers belonging to these generation used Integrated Circuits with VLSI (Very Large Scale Integration). These computers have high processing powers, low maintenance, high reliability and very low power consumption. These computer reduces the cost as well as the size of the computer.
These computers use optic fiber technology to handle Artificial Intelligence, expert systems, robotics etc. These computers have very high processing speeds and are more reliable.http://bizcomputers.blogspot.com/2008/09/history-generations.html