Harwell Machine restored at Bletchley Park

A computer called the Harwell Machine is to be restored at the National Museum of Computing, Bletchley Park. (Home of the World War II Enigma code crackers).

The Harwell Machine (full name: Wolverhampton Instrument for Teaching Computing from Harwell, or WITCH) will become the oldest British computer to be brought back to life when this happens. Well, technically speaking it will apparently be the oldest electronic stored program computer to be reinstated to a fully functioning form (as opposed to the oldest electronic calculating device).

The WITCH had 900 gas filled valves which were first used in 1951 to perform various mathematical calculations (it may also have had a pointy hat and a broomstick, but these were purely for decoration). Each valve could hold a single digit in memory, but predictably it wasn’t too quick at knocking out the resulting sums on paper tape.

It took the Harwell around 10 seconds to complete just one sum. However, on the plus side it was very reliable, as apparently it could run 10 days straight without crashing (Microsoft, are you listening)?

The restoration process is expected to take a year, after which time you can pop down to the National Museum of Computing and see a true piece of computing history. Perhaps after this project the boffins can rescue and restore some of the many ZX81s that have gone to wrack and ruin – after being employed as doorstops up and down the country.