The museum also includes the world's oldest working digital computer (the Harwell Dekatron / WITCH), machines from the 1960s such as the Marconi Transistorised Automatic Computer (T.A.C.), Elliott 803 and 905, an ICL 2966 mainframe from the 1980s, an IBM 1130 from the 1960s, an analogue computer, a hands-on retrocomputing gallery, and several restoration projects such as the PDP-8 and the PDP-11-based air traffic control system from London Terminal Control Centre at West Drayton near London. Further exhibits include mechanical and electronic calculators, a history of slide rules, a pair of Cray supercomputers, and a personal computing gallery with ten hands-on machines. Visitors can also see a re-build of the Cambridge University EDSAC computer that is underway (still in progress as of May 2019.)