The first electronic digital computer built in the US, ENIAC, was unveiled at the University of Pennsylvania in 1946. It weighed 300 tonnes, filled the space of a two-car garage, and contained 18000 vacuum tubes, which failed on average at the rate of one every seven minutes. It cost half a million dollars at 1946 prices. Today, the same amount of computing power is contained in a pea-sized silicon chip. Almost any home computer costing only about $100 can out-perform ENIAC.