Inventing the transistor meant the fulfillment of a dream.
–Ernest Braun and Stuart MacDonald, Revolution in Miniature
In the 1940s, the switching units in computers were mechanical relays that constantly opened and closed, clattering away like freight trains. In the 1950s, vacuum tubes replaced mechanical relays. But tubes were a technological dead end. They could be made only just so small, and because they generated heat, they had to be spaced a certain distance apart from one another. As a result, tubes afflicted the early computers with a sort of structural elephantiasis.
But by 1960, physicists working on solid-state elements introduced an entirely new component into the mix. The device that consigned the vacuum ...