The Harwell Dekatron computer nicknamed WITCH has been recognized as the world's oldest original working digital computer.

The Harwell Dekatron / WITCH, recently restored and now on display in the UK's National Museum of Computing, dates from the early 1950's and has the distinction of using base ten (digital) rather than base two (binary).

Dekatron refers to the ten-state storage devices consisting of ten wires arranged in a circle in a neon tube used for its volatile memory. It was originally used by scientists at the UK Atomic Energy Research Establishment in Harwell, Oxfordshire and it acquired its nickname when in 1957 it was transferred to Wolverhampton and Staffordshire Technical College where, as the Wolverhampton Instrument for Teaching Computation from Harwell it was used for educational purposes for a further 16 years.

It is the second time that WITCH has gained a Guinness Record. The first was just before it was decommissioned at Wolverhampton and Staffordshire Technical College in 1973 when it was acclaimed as the "world's oldest operative computer".

The most recent episode in the history of the WITCH is outlined in more detail in World's Oldest Digital Computer Works Again. Briefly,  having been discovered to be in storage by computer conservationist Kevin Murrell, it  found a new home in The National Museum of Computing (TNMOC) where it was restored over a 3-year period by a team of volunteers and can now be seen working on most opening days.

(click for larger image)

The machine was formally rebooted at a ceremony at TNMOC  when it came back into life with dekatrons flashing and relays clattering. The event, which was recorded for the 21-minute video below, was attended by two of the original designers, Ted Cooke-Yarborough and Dick Barnes, along with Bart Fossey, an early user of the computer at Harwell in the 1950s, and Peter Barden, a user of the computer when it was in Wolverhampton in the 1960s.

The video also features the true story and a re-run of the famous Man versus Machine "Race" in which Bart Fossey takes on the computer with a hand calculator.

If you want to see and hear the Dekatron in action the reboot is between minutes 14 and 15.

Commenting on the Guinness World Record, Kevin Murrell commented:

"We are delighted with the recognition by Guinness World Records for the Dekatron.  Today the fully-functioning Harwell Dekatron / WITCH computer is proving a hugely popular attraction at TNMOC and invaluable in teaching our stream of educational groups about their computing heritage".

Dekatrons in action