It is not generally known that the world’s first practical ‘stored program electronic digital computer” was designed and built in Cambridge by a team at the University’s Mathematical Laboratory between 1947 and 1949. Building on wartime expertise in radar electronics, the Cambridge team, led by M.V. Wilkes, designed a machine that embodied all the elements we expect to find in a modern computer. Of course EDDSAC was on a different scale: built using thermionic valves, it filled a large room; it’s memory was tiny, just 512 words; and its processor puny, running at a pedestrian 500KHz. But, in comparison to the hand calculators and other mechanical computers it replaced, EDSAC was a 1,500-fold speed up – perhaps the largest single leap in computing power ever seen. EDSAC ran for 10 years, helping 3 Cambridge scientists secure their Nobel prizes and starting many famous computer scientists on their careers. Scrapped after 10 years to make room for the next machine, very little of EDSAC survived beyond a few electronics racks, an album of photographs and a handful of technical reports.

The speaker is leading a project based The National Museum of Computing at Bletchley Park to construct an replica of EDSAC as a working exhibit to sit alongside the Museum’s recreation of Colossus, the wartime code-breaking “computer” and WITCH the world’s oldest surviving original computer, dating from 1952. After introducing EDSAC and explaining it’s importance in the history of computers, the speaker will describe how you go about reinventing 70-year old technology and progress on the project to date.