On Tuesday, the 61 year old Harwell Dekatron computer was rebooted at the The National Museum of Computing in the UK, making it the oldest original working digital computer. The 2.75 ton computer was originally used for atomic energy research by the British in the 1950s. It uses paper tape for input and to load programs, with 828 Dekatron tubes serving as volatile memory (similar to RAM). For more on the computer and its history, see this BBC article & video. The Harwell Dekatron computer is now on display at The National Museum of Computing.
video via The National Museum of Computing
photo via The National Museum of Computing