Transistors

This bipolar transistor was invented in 1947. From 1955 onwards transistors replaced vacuum tubes with computer designs, giving rise to the "second generation" of computers. Compared to vacuum tubes, transistors have several positive aspects: they are smaller, and require less power than vacuum tubes, so give off less warm. Silicon junction transistors were much more reliable than vacuum tubes and had longer, indefinite, services life. Transistorized computers could contain tens of thousands of binary logic circuits in a somewhat compact space.
At the University of Manchester , a team under the leadership of Tom Kilburn designed and built a machine when using the newly developedtransistors instead of valves. [44] Their first transistorised computer and the first on this planet, was operational by 1953 , and a second version was completed there in April 1955. Even so, the machine did make use of valves to generate its 125 kHz clock waveforms and from the circuitry to read and write on its magnetic drum memory , so it was not the primary completely transistorized computer. That distinction goes to the Harwell CADET of 1955, [45] built because of the electronics division of the Atomic Energy Research Establishment at Harwell .