Bletchley Park To Host Pioneering EDSAC Computer

A working replica of the first fully operational stored-program computer will be recreated at the National Museum of Computing (TNMOC), fittingly located at the WW2 code breaking centre at Bletchley Park in Buckinghamshire.

The project, to rebuild the Electronic Delay Storage Automatic Calculator (EDSAC) computer has been commissioned by the Computer Conservation Society, and is expected to take at least three to four years to complete. The rebuild costs are estimated at £250,000 and will be funded by a consortium led by Hermann Hauser, the founder of Acorn Computers.

The EDSAC computer used mercury delay lines for memory and vacuum tubes (valves) for logic processing. Data was apparently inputted via paper tape and output was displayed on a teleprinter.

It was built at Cambridge university in the late 1940s, and space wise took up an entire room (roughly 20 square metres).

Father Of British Computing

The computer was built by a team led by the late Professor Sir Maurice Wilkes, then director of the Mathematical Laboratory at Cambridge University. Sir Maurice was a leading light in the early days of computing, and was often overlooked compared to his contemporary Alan Turing.

Sir Maurice died in November last year aged 97, but he was the man that many regard as the father of British computing. His objective was to produce a practical and reliable computer using proven hardware and imaginative software programming techniques.

In the end he was responsible for building what in modern terms, was a 17-bit computer that boasted a whopping 2KB of memory. The EDSAC computer was able to process approximately 650 instructions per second.

One of the challenges of the rebuild however is the fact the original computer used 3,000 mercury-based valves, which cannot now be used because of modern Health and Safety concerns.

Research Tool

The EDSAC computer itself was designed as a general purpose research tool, and it ran its first program on 6 May 1949. It was used for nine years thereafter and its regular service ended in July 1958 when it was dismantled to enable the re-use of precious space.

“EDSAC set computing standards for academia and commerce,” said Professor Andrew Hopper, Head of the Computer Laboratory at Cambridge University. “It was so successful that in the nine years following 1949 it was used by Cambridge University researchers in studies such as genetics, meteorology and X-ray crystallography and even helped two researchers win Nobel prizes. EDSAC also led directly to the first commercially applied computer, the LEO, that broke new ground by enabling the catering company J Lyons & Co Ltd to perform payroll calculations in 1953.”

“The EDSAC was a brilliant achievement that laid the foundations for general purpose computing and introduced programming methods adopted worldwide and still in use,” said Dr David Hartley, chairman of the CCS. “By recreating EDSAC where the public can watch the process, we aim to enthuse a new generation of computer science and engineering students with the genius of those post-war pioneers at Cambridge University.”

Bletchley Park is also home to what is commonly referred to as the oldest “original functioning electronic stored program” machine of its kind, with the restoration of the Harwell computer, which was later known as the WITCH computer.

That machine is housed alongside Colossus Mk II which is said to be the world’s first electronic computer.