When volunteers began rebuilding one of the world’s first fully \r\noperational general-purpose computers they had to painstakingly piece \r\ntogether the inner workings of the 65-year-old machine.
The original EDSAC – the Electronic Delay Storage Automatic Calculator – \r\nwas built immediately after World War II at the University of Cambridge,\r\n where it aided research into areas including genetics, meteorology and \r\nX-ray crystallography. The machine’s design was later used to create \r\nLEO, the world’s first business computer.
With the historic EDSAC scrapped decades ago, the 20 volunteers recreating the computer had to\r\n scrape together information about the machine. For guidance the team \r\nconsulted documents held by individuals and in libraries at the University of Cambridge, and examined the one surviving chassis used in the EDSAC.
Now\r\n the team working out of Bletchley Park in England, home to the famous \r\nWorld War II codebreakers that included father of computing Alan Turing,\r\n have had confirmation the rebuild is on the right track after stumbling\r\n across diagrams of the original machine.
The 19 detailed \r\ncircuit diagrams, which came to light more than 60 years after they were\r\n drawn up, were delivered to the team by chance.
For decades \r\nthe drawings sat in the home of John Loker, who worked as an engineer in\r\n the maths lab at the University of Cambridge and came across the \r\ndiagrams in 1959, just after EDSAC had been decommissioned.
“In a \r\ncorridor there was a lot of stuff piled up ready to be thrown away, but \r\namongst it I spotted a roll of circuit diagrams for EDSAC. I’m a \r\ncollector, so I couldn’t resist the urge to rescue them,” he said.
“It\r\n wasn’t until I visited TNMOC [The National Museum of Computing at \r\nBletchley Park] recently and learned about the EDSAC Project that I \r\nremembered I had the diagrams at home, so I retrieved them and gave them\r\n to the project.”
Many of the diagrams, which date from between \r\n1949 and 1953, were drawn after EDSAC had been constructed and are \r\nthought to have been an aid in refining the original machine and in \r\ndesigning its successor. They are believed to have been part of a much \r\nlarger set of at least 150 drawings and are in remarkably good \r\ncondition.
Andrew Herbert, leader of the EDSAC Project rebuild, \r\nsaid: “Thankfully, the documents confirm that the reconstruction we are \r\nbuilding is basically correct, but they are giving us some fascinating \r\ninsights about how EDSAC was built and show that we are very much in \r\ntune with the original engineers: both teams have been exercised by the \r\nsame concerns.
“Importantly, the drawings clearly show that the \r\naim of EDSAC’s designer, Sir Maurice Wilkes, was to produce a working \r\nmachine quickly rather than to create a more refined machine that would \r\ntake longer to build. The refinements could come later — and many did \r\nas the sequence of diagrams over the five-year period shows.”
Above, from left, is EDSAC technical leader Chris Burton, with John Loker, the engineer who saved the diagrams, and leader of the EDSAC Project rebuild Andrew Herbert.
Nick Heath is a computer science student and was formerly a journalist at TechRepublic and ZDNet.
