The world's oldest original working digital computer

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The world's oldest original working digital computer springs back into action at TNMOC

The 61 year old computer that refuses to retire

After a three-year restoration project at The National Museum of Computing, the Harwell Dekatron (aka WITCH) computer will rebooted on 20 November 2012 to become the world's oldest original working digital computer.

Now in its seventh decade and in its fifth home, the computer with its flashing lights and clattering printers and readers provides an awe-inspiring display for visiting school groups and the general public keen to learn about our rich computer heritage.

The 2.5 tonne, 1951 computer from Harwell with its 828 flashing Dekatron valves, 480 relays and a bank of paper tape readers will clatter back into action in the presence of two of the original designers, one of its first users and many others who have admired it at different times during its remarkable history.

See BBC video of the machine

A clip from the Reboot:

Kevin Murrell, trustee of TNMOC who initiated the restoration project, said: "In 1951 the Harwell Dekatron was one of perhaps a dozen computers in the world, and since then it has led a charmed life surviving intact while its contemporaries were recycled or destroyed. As the world's oldest original working digital computer, it provides a wonderful contrast to our Rebuild of the wartime Colossus, the world's first semi-programmable electronic computer."

The Harwell Dekatron computer first ran at Harwell Atomic Energy Research Establishment in 1951 where it automated the tedious calculations performed by talented young people using mechanical hand calculators. Designed for reliability rather than speed, it could carry on relentlessly for days at a time delivering its error-free results. It wasn't even binary, but worked in decimal -- a feature that is beautifully displayed by its flashing Dekatron valves.

By 1957, the computer had become redundant at Harwell, but an imaginative scientist at the atomic establishment arranged a competition to offer it to the educational establishment putting up the best case for its continued use. Wolverhampton and Staffordshire Technical College won, renamed it the WITCH (Wolverhampton Instrument for Teaching Computation from Harwell) and used it in computer education until 1973.

After a period on display in the former Birmingham Museum of Science and Industry, it was dismantled and put into storage, but "rediscovered" by a team of volunteers from The National Museum of Computing in 2008. With the blessing of the Birmingham museum and in conjunction with the Computer Conservation Society, the team developed a plan to restore the machine and to put it once again to educational use at TNMOC.

Kevin Murrell recalls its rediscovery: "I first encountered the Harwell Dekatron as a teenager in the 1970s when it was on display in the Birmingham Museum of Science and Industry -- and I was captivated by it. When that Museum closed, it disappeared from public view, but four years ago quite by chance I caught a glimpse of its control panel in a photograph of stored equipment. That sparked our ideas to rescue it and we hunted it down.

"The TNMOC restoration team has done a superb job to get it working again and it is already proving to be a fascination to young and old alike. To see it in action is to watch the inner workings of a computer -- something that is impossible on the machines of today. The restoration has been in full public view and even before it was working again the interest from the public was enormous."

Delwyn Holroyd, a TNMOC volunteer who led the restoration team, said: "The restoration was quite a challenge requiring work with components like valves, relays and paper tape readers that are rarely seen these days and are certainly not found in modern computers. Older members of the team had to brush up on old skills while younger members had to learn from scratch!"

The Harwell Dekatron / WITCH computer can be seen by the general public whenever The National Museum of Computing is open. See www.tnmoc.org/visit for opening times.

Notes To Editors

WITCH Fact file

1949 Design begun
1951 First operated
1957 Moved to Wolverhampton
1973 Declared world's most durable computer
1973 Moved to Birmingham Museum of Science and Industry
1997 Moved into storage at Birmingham Collections Centre
2009 Moved to TNMOC
2012 Rebooted to become the world's oldest original working digital computer

Power Consumption: 1.5kW
Size 2m high x 6m wide x 1m deep
Weight: 2.5 tonnes
Number of Dekatron counter tubes: 828
Number of other valves: 131
Number of relays: 480
Number of contacts or relay switches: 7073
Number of high speed relays: 26
Number of lamps: 199
Number of switches: 18

About The National Museum of Computing

The National Museum of Computing, located at Bletchley Park, is an independent charity housing the largest collection of functional historic computers in Europe, including a rebuilt Colossus, the world’s first electronic semi-programmable computer. The Museum enables visitors to follow the development of computing from the ultra-secret pioneering efforts of the 1940s through the mainframes of the 1960s and 1970s, the rise of personal computing in the 1980s and beyond.

New working exhibits are regularly unveiled and the public can already view a rebuilt and fully operational Colossus, the restoration of the Harwell Dekatron / WITCH computer, an ICL 2966, one of the workhorse mainframes computers of the 1980s, many of the earliest desktops of the 1980s and 1990s, plus the NPL Technology of the Internet Gallery. In June 2010 TNMOC hosted Britain’s first-ever Vintage Computer Festival.

Funders of the Museum include Bletchley Park Capital Partners, CreateOnline, Ceravision, InsightSoftware.com, Google UK, PGP Corporation, IBM, NPL, HP Labs, BCS, the Drapers' Foundation, Black Marble, and the School of Computer Science at the University of Hertfordshire. The Museum is currently open to the public on Thursdays and Saturdays from 1pm, and on Bank Holidays in spring and summer. Guided tours are also available at 2.30pm on Tuesdays, 2pm Sundays and some other days. Groups may visit at other times by arrangement and special organisation Away-Days can be booked.

For more information, see www.tnmoc.org and follow @tnmoc on Twitter and The National Museum of Computing on Facebook and Google+.

Media Contacts
Stephen Fleming
Palam Communications for TNMOC
t +44 (0) 1635 299116
e sfleming@palam.co.uk

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