Monday, March 22, 2010

microprocessor


Microprocessors
(The Fourth Generation)
After the integrated circuit, the only place to go was down - in size, that is. Large scale integration (LSI) could fit hundreds of components onto one chip. By the 1980's, very large scale integration (VLSI) squeezed hundreds of thousands of components onto a chip. The ability to fit so much onto an area about half the size of a U.S. dime helped diminish the size and price of computers. It also increased their power, efficiency and reliability. Marcian Hoff invented a device which could replace several of the components of earlier computers, the microprocessor. The microprocessor is the characteristic of fourth generation computers, capable of performing all of the functions of a computer's central processing unit. The reduced size, reduced cost, and increased speed of the microprocessor led to the creation of the first personal computers. Until now computers had been the almost exclusively the domain of universities, business and government. In 1976, Steve Jobs and Steve Wozniak built the Apple II, the first personal computer in a garage in California. Then, in 1981, IBM introduced its first personal computer. The personal computer was such a revolutionary concept and was expected to have such an impact on society that in 1982, "Time" magazine dedicated its annual "Man of the Year Issue" to the computer. The other feature of the microprocessor is its versatility. Whereas previously the integrated circuit had had to be manufactured to fit a special purpose, now one microprocessor could be manufactured and then programmed to meet any number of demands. Soon everyday household items such as microwave ovens, television sets and automobiles with electronic fuel injection incorporated microprocessors. The 1980's saw an expansion in computer use in all three arenas as clones of the IBM PC made the personal computer even more affordable. The number of personal computers in use more than doubled from 2 million in 1981 to 5.5 million in 1982. Ten years later, 65 million PCs were being used. Computers continued their trend toward a smaller size, working their way down from desktop to laptop computers (which could fit inside a briefcase) to palmtop (able to fit inside a breast pocket).

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