EDSAC to be recreated

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.

EDSAC, which stands for Electronic Delay Storage Automatic Calculator, was a general purpose research tool built at Cambridge in the 1940s under the direction of the late Professor 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 Hartley, 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.”

“By recreating EDSAC where the public can watch the process, we aim to enthuse a new generation of computer science and engineering students with the genius of those post-war pioneers at Cambridge University.”

Professor 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 an unprecedented success. The computer 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 re-use of precious space. By then it had been superseded by the faster, more reliable and much larger EDSAC 2.

The original had over 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.

Professor Andrew Hopper, Head of the Computer Laboratory at Cambridge University, said: “EDSAC set computing standards for academia and commerce. It 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 & Co. Ltd. to perform payroll calculations in 1953.”

Kevin Murrell, a director and trustee of The National Museum of Computing, said: “Recreating a fully-functioning EDSAC computer is quite a challenge, but our experience in rebuilding the Colossus computer gives us confidence and insight.”

“The project is fortunate in having the advice and support of Chris Burton who managed the reconstruction of the Manchester Baby, another CCS project. Professor Martin Campbell-Kelly, computer historian at the University of Warwick, will provide an historical and academic perspective for the recreation of EDSAC.”