Dubbed The Witch, the computer was the workhorse of Britain's atomic energy research program in the 1950s, but has spent the last 15 years gathering dust in a storeroom, the BBC reported Monday.
Restored to noisy, light-flashing life in a three-year restoration effort, The Witch will reside at the National Museum of Computing in Buckinghamshire.
The 2.5-ton machine was built in 1949 to help researchers in Britain's atomic energy program by speeding up calculations once performed by a bevy of humans with adding machines.
Though achingly slow by modern standards -- it could take up to 10 seconds to multiply two numbers -- it proved very reliable and was in use until 1957 when it was outstripped by faster, smaller computers.
"It's important for us to have a machine like this back in working order as it gives us an understanding of the state of technology in the late 1940s in Britain," said Kevin Murrell, a trustee of The National Museum of Computing in Bletchley Park.