Can you tell me about different generations of computers?

Answer 1

In the beginning ...

A generation refers to the state of improvement in the development of a product. This term is also used in the different advancements of computer technology. With each new generation, the circuitry has gotten smaller and more advanced than the previous generation before it. As a result of the miniaturization, speed, power, and memory of computers has proportionally increased. New discoveries are constantly being developed that affect the way we live, work and play.

The First Generation: 1944-1958 (The Vacuum Tube Years)

The first generation computers were huge, slow, expensive, and often undependable. In 1944 Tommy Flowers of the British Post Office built the first Colossus codebreaking computer for Bletchley Park, it used roughly 2000 vacuum tubes (before the end of WW2 9 more Colossus computers were built). In 1946 two Americans, Presper Eckert, and John Mauchly built the ENIAC electronic computer which used vacuum tubes instead of the mechanical switches of the Mark I. The ENIAC used 18,000 vacuum tubes, which took up a lot of space and gave off a great deal of heat just like light bulbs do. The ENIAC led to other vacuum tube type computers like the EDVAC (Electronic Discrete Variable Automatic Computer) and the UNIVAC I (UNIVersal Automatic Computer).

The vacuum tube was an extremely important step in the advancement of computers. Vacuum tubes were invented the same time the light bulb was invented by Thomas Edison and worked very similar to light bulbs. It's purpose was to act like an amplifier and a switch. Without any moving parts, vacuum tubes could take very weak signals and make the signal stronger (amplify it). Vacuum tubes could also stop and start the flow of electricity instantly (switch). These two properties made the ENIAC computer possible.

The Second Generation: 1959-1964 (The Era of the Transistor)

The transistor computer did not last as long as the vacuum tube computer lasted, but it was no less important in the advancement of computer technology. In 1947 three scientists, John Bardeen, William Shockley, and Walter Brattain working at AT&T's Bell Labs invented what would replace the vacuum tube forever. This invention was the transistor which functions like a vacuum tube in that it can be used to relay and switch electronic signals. There were obvious differences between the transistor and the vacuum tube. The transistor was faster, more reliable, smaller, and much cheaper to build than a vacuum tube. These transistors were made of solid semiconductor material, some of which are germanium, silicon, gallium arsenide, etc. Therefore they were very cheap to produce. They were much smaller and gave off virtually no heatcompared to vacuum tubes. Their use marked a new beginning for the computer. Some computers of this generation were UNIVAC 1107, IBM 7090, IBM 1620, IBM 1401, UNIVAC III, UNIVAC Solid State, DEC PDP-1, and CDC 6600.

The Third Generation: 1965-1970 (Integrated Circuits - Miniaturizing the Computer)

Transistors were a tremendous breakthrough in advancing the computer. However no one could predict that thousands even now millions of transistors could be compacted in such a small space. The integrated circuit, or as it is sometimes referred to as semiconductor chip, packs a huge number of transistors onto a single wafer of silicon. Robert Noyce of Fairchild Corporation and Jack Kilby of Texas Instruments independently invented different types of integrated circuits. Placing such large numbers of transistors on a single chip vastly increased the power of a single computer and lowered its cost considerably.

Since the invention of integrated circuits, the number of transistors that can be placed on a single chip has doubledevery two years, shrinking both the size and cost of computers even further and further enhancing its power. Most electronic devices today use some form of integrated circuits placed on printed circuit boards-- thin pieces of paper or fiberglass bonded with phenolic or epoxy resins that have copper electrical connections etched onto them.

These third generation computers could carry out instructions in billionths of a second. The size of these machines dropped to the size of small file cabinets. Yet, the single biggest advancement in the computer era was yet to be discovered. Some computers of this generation were IBM System 360, Apollo Guidance Computer, Minuteman Missile Guidance Computer, UNIVAC 1108, DEC PDP-8, IBM System 370, DEC PDP-11, Data General Nova, DEC VAX-11/780, Cray-1.

The Fourth Generation: 1971-Today (TheMicroprocessor)

This generation can be characterized by both the jump to monolithic integrated circuits(millions of transistors put onto one integrated circuit chip) and the invention of the microprocessor (a single chip that could do all the processing of a full-scale computer). By putting millions of transistors onto one single chip more calculation and faster speeds could be reached by computers. Because electricity travels about a foot in a billionth of a second, the smaller the distance the greater the speed of computers.

However what really triggered the tremendous growth of computers and its significant impact on our lives is the invention of the microprocessor. Ted Hoff, employed by Intel(Robert Noyce's new company) invented a chip the size of a pencil eraser that could do all the computing and logic work of a computer. The microprocessor was made to be used in calculators, not computers. It led, however, to the invention of personal computers, or microcomputers.

It wasn't until the 1970's that people began buying computer for personal use. One of the earliest personal computers was the Altair 8800 computer kit. In 1975 you could purchase this kit and put it together to make your own personal computer. In 1977 the Apple II was sold to the public and in 1981 IBM entered the PC (personal computer) market.