<P> At the University of Manchester, a team under the leadership of Tom Kilburn designed and built a machine using the newly developed transistors instead of valves . Their first transistorised computer and the first in the world, was operational by 1953, and a second version was completed there in April 1955 . However, the machine did make use of valves to generate its 125 kHz clock waveforms and in the circuitry to read and write on its magnetic drum memory, so it was not the first completely transistorized computer . That distinction goes to the Harwell CADET of 1955, built by the electronics division of the Atomic Energy Research Establishment at Harwell . </P> <P> The next great advance in computing power came with the advent of the integrated circuit . The idea of the integrated circuit was first conceived by a radar scientist working for the Royal Radar Establishment of the Ministry of Defence, Geoffrey W.A. Dummer . Dummer presented the first public description of an integrated circuit at the Symposium on Progress in Quality Electronic Components in Washington, D.C. on 7 May 1952 . </P> <P> The first practical ICs were invented by Jack Kilby at Texas Instruments and Robert Noyce at Fairchild Semiconductor . Kilby recorded his initial ideas concerning the integrated circuit in July 1958, successfully demonstrating the first working integrated example on 12 September 1958 . In his patent application of 6 February 1959, Kilby described his new device as "a body of semiconductor material...wherein all the components of the electronic circuit are completely integrated". Noyce also came up with his own idea of an integrated circuit half a year later than Kilby . His chip solved many practical problems that Kilby's had not . Produced at Fairchild Semiconductor, it was made of silicon, whereas Kilby's chip was made of germanium . </P> <P> This new development heralded an explosion in the commercial and personal use of computers and led to the invention of the microprocessor . While the subject of exactly which device was the first microprocessor is contentious, partly due to lack of agreement on the exact definition of the term "microprocessor", it is largely undisputed that the first single - chip microprocessor was the Intel 4004, designed and realized by Ted Hoff, Federico Faggin, and Stanley Mazor at Intel . </P>

Explain in brief all the generations of computer