The size and speed of computers have changed dramatically since the development of the first general-purpose electronic digital computer. The ENIAC, built in 1946, the massive computer could perform about 5000 editions and 1000 multiplications per second. Early computers like UNIVAC used bulky, unreliable vacuum tubes. The invention of the transistor in 1947 led to the production of faster, smaller, and more reliable electronic computers. The development of the integrated circuit in the early 1960s continued the miniaturisation process. Many of today's integrated circuits contain millions of transistors and other tiny parts on a small chip. Smaller and less expensive components made the development of smaller computers, called personal computers, possible. Today, personal computers are more powerful than the room-sized computers of the past. They are able to carry out millions of instructions per second. Small portable notebook computers usually weigh less than 5 pounds. Even smaller computers can fit in the palm of (their hand).