Historic computer rebuilt in museum as tribute

A working replica of the first fully-operational stored-program computer is to be rebuilt in recognition of the computer scientists at Cambridge University who developed it.

The project has been commissioned by the Computer Conservation Society (CCS) to inform the general public about Britain’s computer heritage and, hopefully, to inspire future students of computing and engineering as a result.

The EDSAC, which stands for Electronic Delay Storage Automatic Calculator, was a general-purpose research tool built at Cambridge in the 1940s under direction of the late Prof Sir Maurice Wilkes. It ran its first programmes on 6 May 1949, when it calculated a table of squares.

Plans have now been approved to recreate the computer, which was over two metres high and occupied a floor area of 20 square metres.

It will be built in full public view at The National Museum of Computing at the UK’s former code-breaking centre at Bletchley Park. The project is expected to take three to four years and is being funded by a consortium led by the computing entrepreneur, Hermann Hauser.

David Hartey, chairman of CCS and a former president of the British Computer Society, said: ‘The EDSAC was a brilliant achievement that laid the foundations for general purpose computing and introduced programming methods adopted worldwide and still in use.’

Prof Wilkes was director of the Mathematical Laboratory at Cambridge when EDSAC was built, and is now widely regarded as the ‘father’ of British computing. His objective was to produce a practical and reliable computer using proven hardware and imaginative software programming techniques.

EDSAC was capable of performing 650 instructions per second and was used for nine years of regular service, ending in July 1958 when it was dismantled to enable the reuse of precious space. By then it had been superseded by the faster, more reliable and much larger EDSAC 2.

The original had more than 3,000 electronic tubes or valves used for logic, mercury-filled tubes for memory, data input via paper tape and output on a teleprinter. Only the mercury-filled tubes are expected not to be recreated – in compliance with modern safety requirements – and will be substituted with a similar delay line storage technology.

Prof Andrew Hopper, head of the Computer Laboratory at Cambridge University, said: ‘EDSAC was so successful that in the nine years following 1949 it was used by Cambridge University researchers in studies such as genetics, meteorology and X-ray crystallography and even helped two researchers win Nobel prizes. EDSAC also led directly to the first commercially applied computer, the LEO, that broke new ground by enabling the catering company J Lyons & Company to perform payroll calculations in 1953.’