Memory space ... device needed own room
BOFFINS will rebuild the "great-grandad" of computers - a 6ft 6in British whopper 50,000 times slower than today's PCs.
The original 1949 machine could handle a revolutionary 650 commands a second.
Modern personal computers process around 30 million in the same time. But the Electronic Delay Storage Automatic Calculator solved maths problems 1,500 times faster than a desk-top calculator of the time and saved weeks of data entry. National Museum of Computing Director Kevin Murrell said: "This was Adam as far as modern computers are concerned - it was their great-grandfather.
"Most things in modern computers come from designs like EDSAC."
It occupied 215sq ft of floor space and used 3,000 valves - equivalent to one transistor. Modern laptops contain hundreds of millions of transistors.
But Stephen Fleming, of the Computer Conservation Society, said: "By performing 650 commands a second, EDSAC revolutionised computing."
It was created by a team led by Cambridge University Prof Sir Maurice Wilkes and first used on May 6, 1949, It was dismantled after nine years to make space for the much faster EDSAC 2. The £250,000 replica will take up to four years to build at the museum in Bletchley Park, Buckinghamshire.