First Generation : Use of Vacuum Tubes

It was in 1946 that Eckert and Mauchly produced the ENIAC or Electronic Numerical Integrator and Calculator at the University of Pennsylvania. This was made for Army Ordnance and was used to calculate the trajectories of air borne weapons. The ENIAC was made up of 18,000 vacuum tubes, 70,000 resistors. 10,000 capacitors and 6,000 switches. The ENIAC weighed 30 tons and took 15000 sq.ft. to house. It is said that when the ENIAC was turned on, all the lights in Philadelphia dimmed. The giant ENIAC was priced at US $ 4,87,000 and could perform 5000 calculations in one second. The ENIAC consumed so much power and generated so much heat that it had to be shut down quite frequently for cooling.

In fact, it is said that one out of the 18,000 vacuum tubes blew up every 7 minutes.

The problem of heat generation and size was a drawback on all the computers built during this time, because they used valves. Valves are those glowing tubes found inside old television or radio sets. The ENIAC takes the honor of being the first true electronic computer, as it was built with vacuum tubes, not relays, and incorporated the three-classical/output device. Computers such as the ENIAC, which were built with vacuum tubes, are known as First Generation Computers.

The Coming of Transistors : The Second Generation

During the second half of the fifties, 2nd Generation computers using transistors were introduced. A transistor is a small device, the size of a tablet, which can perform the same functions as that of a large valve. One can find the 3-legged transistors inside all transistor radios.

Second generation computers were significantly faster than the 1st Generation ones. Computers using transistors were smaller, faster, cheaper and more reliable than their predecessors. Their popularity saw the growth of the computer industry.

With the popularity of the 2nd generation computers, there was a new and increased interest in the research and development in the field of computer science. An improvement on the 2nd generation computers did not take place till the US space programme got under way.

LSI : The Third Generation Technology

The miniaturisation efforts in components to be used in Space technology paved way for next generation. It tried to compress about 1000 transistors into a single wafer of silicon known as a silicon chip - the size of a thumb. By compressing more and more circuitry into a single chip, greater logical capability could be built into a smaller unit than before. The packing of upto 1,000 circuits came to be known as Large Scale Integration - LSI.

VLSI : The fourth Generation.

The quest for improvement did not end here. Very soon, E.M. Huff at Intel Corporation succeeded in packing upto 10,000 circuits in a single chip. This represented Very Large Scale Integration or VLSI. Computers using such chips are known as the 4th generation Computers. Advance research at INTEL, has brought chips with a package of 2,75,000 transistors and circuit in a single chip.

Computers that have become more compact and less energy consuming mark the progress from one generation to the other. They have also gained in speed and reliability. This trend in hardware had a remarkable effect in the cost also. Prices of hardware crashed and day-by-day are shrinking.