The Witch, as the machine is known, has been restored to clattering and flashing life in a three-year effort.
Design and construction work on the machine began in 1949 and it was built to aid scientists working at the UK's Atomic Energy Research Establishment at Harwell in Oxfordshire. The 2.5 tonne machine was created to ease the burden on scientists by doing electronically the calculations that previously were done using adding machines.
The machine first ran in 1951 and was known as the Harwell Dekatron - so named for the valves it used as a memory store. Although slow - the machine took up to 10 seconds to multiply two numbers - it proved very reliable and often cranked up 80 hours of running time in a week.
By 1957 the machine was being outstripped by faster, smaller computers and it was handed over to the Wolverhampton and Staffordshire Technical College (more recently Wolverhampton University) where it was used to teach programming and began to be called the Witch (Wolverhampton Instrument for Teaching Computation from Harwell).