History of science: 60 years old computer springs back into action in the Great Britain

After a three-year restoration project at The National Museum of Computing, the Harwell Dekatron (aka WITCH) computer will rebooted on 20 November 2012 to become the world's oldest original working digital computer.

The 2.5 tonne, 1951 computer from Harwell with its 828 flashing Dekatron valves, 480 relays and a bank of paper tape readers will clatter back into action in the presence of two of the original designers, one of its first users and many others who have admired it at different times during its remarkable history.

Harwell Dekatron development began in 1949. The computer was ready two years later. Computer was used for calculations by the the staff of nuclear energy research center, located in the English county of Oxfordshire.

By 1957, the computer had become redundant at Harwell, but an imaginative scientist at the atomic establishment arranged a competition to offer it to the educational establishment putting up the best case for its continued use. Wolverhampton and Staffordshire Technical College won, renamed it the WITCH (Wolverhampton Instrument for Teaching Computation from Harwell) and used it in computer education until 1973.

After a period on display in the former Birmingham Museum of Science and Industry, it was dismantled and put into storage, but "rediscovered" by a team of volunteers from The National Museum of Computing in 2008. With the blessing of the Birmingham museum and in conjunction with the Computer Conservation Society, the team developed a plan to restore the machine and to put it once again to educational use at TNMOC.

Restorers have set a goal to minimize the use of modern parts in the machine. Because of this the restoration process lasted for three years. To the ceremony of launching the computer which will now be an exhibit of Bletchley Park, were invited engineers and programmers from the founders and the first users of Harwell Dekatron.

Bletchley Park Museum, in addition to Harwell Dekatron, features some other unique systems, including the Bombe - deciphering machine created during the Second World War, with the contribution of the British mathematician Alan Turing.