Invention of the transistor
One major event was crucial for this whole development. It was the invention of the transistor that revolutionized the world of electronics.
By the 1940s, the switching units in computers were mechanical relays which were then replaced by vacuum tubes. But these vacuum tubes soon turned out to have some critical disadvantages which impeded the further progress in computing technology. In contra st, transistors were much better. They could perform everything the vacuum tubes did, but "required much less current, did not generate as much heat, and were much smaller") than vacuum tubes.
The use of vacuum tubes, which could not be made as small as transistors, had meant that the computers were very large and drew a lot of power. For example the famous American ENIAC, built in 1946 and consisting of more than 18,000 vacuum tubes, had a tota l weight of 30 tons, filled a whole room and consumed 150 KW per hour. The breathtaking development in computers can be seen, when comparing the ENIAC with today's laptops which are portable with about 5 kg, are battery driven and run some 100,000 times fa ster.)
This development was launched by the transistor (short for "transfer resistance") invented in 1947 by William Shockley and his colleagues John Bardeen and Walter Brattain. This "major invention of the century") was made at the Bell Labs in Murray Hill, Ne w Jersey, which are the "R&D arm of the American Telephone and Telegraph Company (AT&T).") And in 1956, the three scientists received the Nobel Prize in Physics for their invention that had "more significance than the mere obsolescence of another bit of t echnology.")
The transistor is a "switch - or, more precisely, an electronic "gate," opening and closing to allow the passage of current.") Transistors are solid-state and are based on semiconductors such as silicon. The crystals of these elements show properties whic h are between those of conductors and insulators, so they are called semiconductors. The peculiarity of semiconductor crystals is that they can be made "to act as a conductor for electrical current passing through it in one direction") only, by adding imp urities or "doping" them - for instance, "adding small amounts of boron of phosphorus.")