The Imitation Game props in a Cambridge home workshop


A home workshop in Cambridge is today playing a vital role in the reconstruction of a Cambridge University machine that 65 years ago led the world’s computing revolution. It’s one of several home workshops across England that are being transported back in time as they play their part in the reconstruction of EDSAC, one of the world’s earliest computers, that is currently being assembled at The National Museum of Computing on Bletchley Park.

In Nigel Bennée’s home workshop in Cambridge, key components of the EDSAC reconstruction are being built. The racks that he is using to assemble the Arithmetic Logic Unit, called the Computer in original EDSAC terminology, have already had an extraordinarily high profile because they were originally built, to the EDSAC's team specifications, for use as part of the “Christopher computer” in Alan Turing’s home in the Oscar-winning film, The Imitation Game. Their latest role is to hold some of the 3000 valves of the reconstructed EDSAC computer.

EDSAC was built in Cambridge in the years following the Second World War and was the first computer ever to go into service at a University. It enabled new approaches to scientific research and was used in at least two Nobel-Prize winning research breakthroughs. The complete reconstruction is being assembled piece by piece at The National Museum of Computing where the process can be followed by Museum visitors.

Former nuclear physicist and owner of the home workshop, Nigel Bennée, is the EDSAC Project’s expert on Arithmetic circuits.. He is one of the 20 project volunteers, many of whom are reconstructing parts of EDSAC in their home workshops across England from the Welsh borders to Norfolk and from Kent to Manchester. Every few months they converge on The National Museum of Computing to report progress and to contribute completed modules that are then installed and commissioned in the huge reconstruction of EDSAC.

Andrew Herbert, leader of the EDSAC reconstruction project, said: “The very idea of reconstructing a computer using technologies that are 65 years old might seem impossible, but we have located key experts among that last generation of engineers who know about immediate post-war technologies like thermionic valves. Because they kept up-to-date with technological developments throughout their careers, they can deploy a battery of skills, techniques and modern computer-based instruments to test the modules they are building even before they are installed in the reconstructed machine. That has given us a huge advantage over the original pioneers who had only the most basic equipment -- they had to connect complete assemblies of circuits and then puzzle out exactly which ones weren’t working!”

A skilled electronics enthusiast at the age of ten, Nigel Bennée did not encounter computers until 1966, 17 years after EDSAC’s debut. Then he became hooked, designing equipment and programming a variety of machines. He is now thoroughly enjoying his latest, retro challenge: “The EDSAC project gives a fascinating insight into the origins of computing and it’s very stimulating to help develop or redevelop the skills that were once required to work with the technologies of the 1940s. It is also sobering to note that I was learning arithmetic at about the same time as the circuits I am reconstructing were being designed to enable EDSAC to do the same thing. The parts now temporarily residing in my workshop, will be seen by millions across the world! In a few months’ time. The buzz will be to see the reconstructed EDSAC running its first program at The National Museum of Computing at Bletchley Park and helping to shine some light on the origins of computing for new generations of computer scientists and engineers.”

Notes To Editors


EDSAC, the Electronic Delay Storage Automatic Calculator, was built immediately after World War II by a team led by Sir Maurice Wilkes in the Mathematical Laboratory of the University of Cambridge. It was one of the first practical general purpose computers and was used by scientific researchers across the University. The EDSAC design was later developed to create LEO, the world's first business computer.

  • EDSAC was based on the ideas of John von Neumann and others who in 1945 suggested that the future of computing lay in computers which could store sets of instructions (programs) as well as data in a memory.

  • EDSAC was over two metres high and occupied a ground area of four metres by five metres.

  • Pre-dating the transistor, its 3000+ thermionic valves / vacuum tubes used as logic were arranged on 12 racks containing just over 140 chassis in total.

  • Mercury-filled tubes were used for the main memory, comprising 512 words initially, later 1024 word (equivalent to 2KB/4KB of PC storage).

  • It performed 650 instructions per second, effectively computing more than 1500 times faster than the mechanical calculators it replaced.

  • EDSAC read in programs from paper tape and printed its results on a teleprinter.

  • EDSAC ran its first program on 6 May 1949 and soon after that began nine years of regular service for scientific users across the University of Cambridge and other institutions, 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 and much larger EDSAC 2.

2 The EDSAC Reconstruction Project

The EDSAC Reconstruction Project which began in 2011 is expected to be completed in 2015/6. The reconstructed EDSAC, which will occupy 20 square metres, is being built at The National Museum of Computing, where visitors can see the work in progress. The EDSAC Replica Project has been funded by a consortium led by Hermann Hauser.

The ongoing reconstruction story featuring videos of progress can be seen at

3 About The National Museum of Computing

The National Museum of Computing, located on Bletchley Park, is an independent charity housing the world's largest collection of functional historic computers, including the rebuilt Colossus, the world’s first electronic computer, and the WITCH, the world's oldest working digital computer. The Museum enables visitors to follow the development of computing from the ultra-secret pioneering efforts of the 1940s through the large systems and mainframes of the 1950s, 60s and 70s, and the rise of personal computing in the 1980s and beyond.

The Museum runs a highly successful Learning Programme for schools and colleges and promotes introductions to computer coding amongst young people, especially females, to inspire the next generation of computer scientists and engineers.

A pledge by an individual benefactor of £1 million if matched funding is found means that every pound or dollar donated to the Museum will count double. Funders of the Museum have included Bletchley Park Capital Partners, Bloomberg, CreateOnline, Ceravision,, Ocado Technology, FUZE, 4Links, Google UK, IBM, NPL, HP Labs, and BCS.

The whole Museum is currently open to the public from 12 noon on Thursdays, Saturdays and Sundays, spring and summer Bank Holidays and during school holidays. The Colossus and Tunny galleries are open daily. Public and private Guided Tours are available and bookable online – see the website or the iPhone app for details. Educational and corporate group visits are available by prior arrangement.

For more information, see and follow @tnmoc on Twitter and The National Museum of Computing on Facebook and Google+. A TNMOC iPhone App is also now available from the iPhone App Store.

Media Contacts

Stephen Fleming, Palam Communications, for the EDSAC Project 01635 299116