Early radios and other electronic devices relied on vacuum tube technology. Because the tubes took up a great deal of space, the devices that utilized them tended to be very bulky and cumbersome. In the late 1940's, the development of the transistor provided a compact alternative to vacuum tubes. Transistors were capable of achieving the same level of power amplification achieved by tubes while taking up much less space, and using only a fraction of the power. Starting in the 1960's, the integrated circuit provided still another level of miniaturization. An integrated circuit the size of a transistor could perform the function of 20 transistors. Today, the microprocessor, a modern refinement of the original integrated circuits, can incorporate the functions of several complete printed circuit boards into a single, low-power consumption chip less than two inches square, allowing for the construction of hand-held computers with more computing power than the huge mainframes used in the 70's and 80's.