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Context : Computer 50 -- University of Manchester's 50th Anniversary Celebrations.

50th Anniversary of the "Transistor Computer"
at the University of Manchester

To mark this event, here is a short note by Dick Grimsdale, who built the machine.
It is hoped to add some more material in the near future.
Meanwhile already on these pages is a brief description of the project, the relevant passage in Tom Kilburn's biography and a photograph (plus close-up) of the machine.

The 16th of November 2003 marked the 50th anniversary of the execution of a program by the world’s first transistor computer at the University of Manchester. The computer was built by Dick Grimsdale, then a research student in the Department of Electrical Engineering and now a Professor of Electronic Engineering at Sussex University.

The machine used point-contact transistors, made in small quantities by STC and Mullard. These consisted of a single crystal of germanium with two fine wires, resembling the crystal and cat’s whisker of the 1920’s. These transistors had the useful property that a single transistor could possess two stable states. The Manchester Ferranti Mark I was in service at that time and, being a valve machine, required a large room to accommodate the 4000 valves and associated circuits and consumed 27kW of power. The transistor computer was much smaller and consumed 150 watts. The memory was a magnetic drum, a cylindrical version of today’s hard disk drives. The arithmetic and control registers were on the drum, in the form of delay lines with reading heads displaced a short distance from the writing heads around the circumference. The development of the machine was severely hampered by the unreliability of the transistors.

A commercial version of the transistor computer was built by Metropolitan-Vickers of Trafford Park, as the MV950. Some six machines gave reliable service in the engineering departments of the company for several years.

Copyright The University of Manchester 2003