The prototype computer (November 1953) had a simple seven-function order code and one track of 64 words for main storage. For the full-size computer (April 1955) the order code and storage were much extended and a hardware multiplier included. A third "regenerative" drum track formed an 8-word B store. Arithmetic was serial, with a pulse rate of 125,000 per second. The instruction times were directly related to the 30-millisecond drum revolution time (the basic unit being the time to read a word, i.e. 1/64th of a revolution). The expanded 1955 machine had a total of 200 point-contact transistors and 1300 point diodes, which resulted in a power consumption of 150 watts. There were considerable reliability problems with the early batches of transistors and the average error free run in 1955 was only 1.5 hours. Metrovick 950 Metropolitan-Vickers became interested in the design after the success the university had selling computing time on the Mark I to commercial customers. They adopted the design of the 1955 Manchester University transistor computer as the Metrovick 950. The only relevant experience in Metropolitan-Vickers was that in the early 1930s they had manufactured a mechanical calculating machine in the form of the differential analyser in conjunction with Douglas Hartree of Manchester University. They changed all the circuits to more reliable types of junction transistors, although it appears they may have built one example with the earlier designs. The production version was known as the Metrovick 950 and was built from 1956 to the extent of six or seven machines, which were "used commercially within the company" or "mainly for internal use". See also Manchester computers References External links Early computers at Manchester University Transistorized computers Metropolitan-Vickers Early British computers Computer-related introductions in 1956 History of science and technology in the United Kingdom