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Computer History page 4 In the 1940's, virtually all local and long distance telephone service in the United States was provided by AT&T. Calls placed by AT&T's customers were routed from one location to another by electromechanical relays--switches that physically shuttled themselves from one position to another in response to a quick burst of electrical energy.
Demand for telephone service in the 1940s was growing exponentially. It wasn't long before AT&T's engineers realized that their electromechanical call-switching system lacked the speed and efficiency required to endure the anticipated calling volumes. In order for AT&T to meet the future needs of its customers, the engineers knew that they would have to develop a faster, fully electronic switching system. Interestingly, the engineers rejected the idea of a system based on vacuum tubes outright. Basing their opinion on the army's experience with ENIAC, AT&T's engineers concluded that vacuum tubes took too much time to warm up, required too much space, consumed too much energy, and required too much manual upkeep to ever be cost-effective. Instead, AT&T turned to Bell Labs, the company's research division, for assistance. The Bell Labs physicists were asked if it might be possible to develop a smaller, faster, more reliable, and less costly successor to the vacuum tube. Mervin Kelly, Bell Labs' director of research, believed that a solution might be possible.
Kelly felt that metalloids, such as silicon or germanium, might hold the answer. Metalloids are naturally occuring elements that form the dividing line between metals (such as iron) and non-metals (such as carbon). Metalloids share some of their properties with metals and share other properties with non-metals. Like most non-metals, metalloids do not ordinarily conduct electricity. However, under certain conditions, some metalloids can be coerced into becoming carriers of electrical current. Metalloids that can be switched between electrically conductive and non-conductive states are known as semiconductors. Kelly asked a talented but cantankerous physicist named William Shockley to develop a semiconductor that--like the vacuum tube before it--could act as a fast, movement-free electrical switch.
Perhaps most importantly, the transistor made it possible for IBM and other computer manufacturers to develop smaller and more affordable computers. The first transistorized computers found their way onto U.S. military bases and Navy vessels in the early 1950s. But it wasn't long before these powerful new machines began to grace the halls of other U.S. government agencies and large American corporations like General Motors and Sara Lee.
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Shockley made some progress, but eventually moved on to other tasks. Shockley's project was turned over to John Bardeen and Walter H. Brattain for completion. On December 23, 1947, Bardeen and Brattain first demonstrated their invention--a device that became known as the transistor--to the management at Bell Labs.
Like the vacuum tube that preceded it, the transistor could be used to either transmit or interrupt an electrical current. This current could then be used to both represent and move data. The transistor held several advantages over its predecessor. Unlike vacuum tubes, transistors did not generate much heat, didn't take up a lot of space, could be manufactured for pennies per thousand, didn't need to be warmed up, required little in the way of power, and, under the right conditions, could last almost forever.
Because they were small, inexpensive, and required little electrical power, transistors made possible an incredibly wide variety of new and innovative electronic devices. In 1954, the first pocket-sized transistor radios appeared, followed by battery-powered hearing aids, hand-held calculators, "instant-on" television sets, two-way radios, pacemakers, portable audio cassette recorders, VCRs, CD players, infrared remote controls, digital cameras, cellular phones, self-tuning car engines, and the entire space program, among other things. The transistor has brought significant change to our everyday lives, and it brought Shockley, Bardeen, and Brattain a well-deserved joint Nobel prize in physics.