Repository for a web based emulator for the Harwell WITCH. The Harwell computer, later known as the Wolverhampton Instrument for Teaching Computing from Harwell (WITCH), or the Harwell Dekatron Computer, was an early British relay-based computer. It has been restored and on display at The National Museum of Computing at Bletchley Park, where it is described as "the oldest original functioning electronic stored program computer in the world".