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Seminal UK computer Edsac to be recreated

The UK's first fully working general-purpose computer is to be recreated at Bletchley Park, to sit alongside Colossus, Witch and other groundbreaking designs
Written by Rupert Goodwins, Contributor

Edsac, the UK's first fully operational general-purpose computer, is to be recreated at The National Museum of Computing at Bletchley Park.

The £250,000 project will be conducted in public, so visitors to the historic code-breaking site will be able to see it at all stages in the process, the Computer Conservation Society said in its announcement on Thursday.

Edsac computer recreation

The Edsac computer, pictured here in 1947, is to be recreated at the National Museum of Computing at Bletchley Park. Photo credit: Computer Laboratory, University of Cambridge

The original Edsac — Electronic Delay Storage Automatic Computer — was completed in 1949 at the University of Cambridge, and was used in active mathematical and computational research. It ran at around 650 instructions per second, used 12KW of power, and had the equivalent of 2KB of memory in mercury delay lines — the only part unlikely to be recreated, due to modern health and safety rules.

David Hartley, chairman of the Computer Conservation Society (CCS), told ZDNet UK that while the project is still at an early stage, much of the groundwork has already been done.

It's very exciting that we can do the restoration in public. Education is the whole reason for the project.
– David Hartley, Computer Conservation Society

"We have enough of a design to work from," he said, "and we have located a lot of the parts. We'll need 3,000 valves, for example. We've got to the stage where we've trawled the archives and looked at the few artefacts that survive. We have some circuit diagrams, some photographs, and we're talking to people who were there, although there aren't many of them left."

Hartley said that the idea for the recreation "cropped up in discussions" last April with Acorn Computers founder Hermann Hauser, serial Cambridge IT entrepreneur and venture capitalist, who expressed interest and later created a consortium to fund the recreation. Born in 1948, Hauser is one year older than Edsac.

The choice of The National Museum Of Computing to conduct the project was an easy one, Hartley said.

"It has more space, more volunteers [than Cambridge] and all the resources of the museum. It's an extremely good place for the restoration of computers, and it's very exciting that we can do it in public. Education is the whole reason for the project," he said.

Stored-program computer
Although such titles are contested, the CCS claims that Edsac was the world's first fully operational stored-program computer. Its design was largely responsible for Leo 1, the Lyons Electronic Office computer that is accepted as the first electronic computer to be used in business.

Edsac itself saw the first subroutine, the first software library, and was used on the course for the first formal university qualification in computing in the world. Its practical work included X-ray molecular biology, radioastronomy, theoretical chemistry and atmospheric studies.

Hartley told ZDNet UK that while the project was still getting underway and was still to appoint a manager, he expected that visitors to Bletchley Park will see things happening "within a very few months". Completion is expected within three to four years.

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