EDSAC (Electronic Delay Storage Automatic Calculator) the room-sized stored-program computer built at Cambridge University and which first ran in 1949 is going to be rebuilt. And the public will be able to watch the 4-year project.

The UK's Computer Conservation Society has commissioned the replica which is to be built at Bletchley Park, Britain's wartime code-cracking centre and now home to the National Museum of Computing. 

Maurice Wilkes and the EDSAC1

Maurice Wilkes, regarded as the Father of British computing who died on 30 November 2010, was the architect of the EDSAC, which is sometimes regared as the first stored program computer. While that is not the case (that honor should go to the Manchester Mark I) it was the first machine to be used in a modern way in that it had users and this is the reason for its importance. 

The rebuild is a gigantic undertaking - EDSAC  was two metres high. Its 3,000 vacuum tubes took up four metres of floor space, and it could perform 650 instructions per second. All data input was via paper tape. 

 EDSAC - the original circa 1949

The original EDSAC used mercury-filled tubes for memory, but in the interests of safety, the replica will use an alternative non-toxic substance. Rebuilding will take four years, and visitors to Bletchley park will be able to watch the work as it progresses.

Further reading:

Maurice Wilkes and EDSAC

Maurice Wilkes, father of British computing, dies

Bletchey Park - site of national (UK) importance