Richard (Dick) Barnes, co-designer of the Harwell Dekatron computer, died aged 98 on 8 April 2019.

Update: A memorial service for Dick Barnes will be held at St Helen's Church, Abingdon, Oxforshire on Tuesday 4 June 2019 at 11am.

In 1949, when working at AERE Harwell in Oxfordshire, Barnes co-designed the now world-famous Harwell Dekatron (WITCH) computer that is still operational at The National Museum of Computing. His co-designers were Ted Cooke-Yarborough and Gurney Thomas.

When TNMOC decided to restore the Harwell Dekatron computer in 2009, Barnes took a great interest in the project visiting to see progress. His daughter, Ros Mennie joined the project team analysing the original software.

On reboot day on 12 November 2012, Barnes was joined by Cooke-Yarborough to see the computer of their youth run again and by doing so it become the world’s oldest working digital computer – the story went around the world and the claim was soon recognised by Guinness World Records.

Speaking on video at the reboot, Barnes recalled why dekatrons were used in the computer. “All the early computer designers faced the problems of storing data, so we selected dekatrons, a ready-made storage device for one decimal digit.” Using telephone relays for control and sequencing, and the Dekatron tubes for storage and arithmetic, most program instructions are read from paper tape. The computer is slow, but very reliable and capable of operating continuously for long periods.

Paying tribute to Barnes, leader of the Harwell Dekatron restoration team Delwyn Holroyd said, "Dick took a keen interest in the restoration project and it was a privilege to be able to show him the machine working again 63 years after he first designed it. Dick was responsible for the complex relay logic, which he designed on paper without the benefit of the tools we take for granted nowadays and with very little prior art to draw upon. The compactness, elegance and reliability of the resulting design is a fitting tribute to his skill.

Even on its retirement from Harwell in 1957, the Harwell Dekatron found fame under a new name – the WITCH – the Wolverhampton Instrument for Teaching Computation from Harwell – being used to teach students about computing until 1972.

As an early computer pioneer, Barnes had other achievements to his credit, including a fixed-program binary calculator to analyse operational errors in air warfare at TRE, Malvern in 1945 and, in 1956, the Harwell Transistor Computer (CADET) co-designed with Cooke-Yarborough and JH Stephen. Barnes wrote that the CADET may have been the first all-transistor computer to provide a regular computing service. Barnes worked at AERE Harwell until retirement and was responsible for a whole series of electronic control logic elements for use in the nuclear industry.

Today, the Harwell Dekatron / WITCH computer, which has had so many lives, is on display and in daily use at The National Museum of Computing to teach students about the history and the internal workings of computers.

The reboot of the Harwell Dekatron / WITCH on Reboot Day 12 November 2012: