Radar Establishment (RRE). It ran its first trial program in late 1952 or early 1953 and became operational in early 1955. MOSAIC contained 6,480 electronic valves and had an availability of about 75%. It occupied four rooms and was the largest of the early British computers. It was used to calculate aircraft trajectories from radar data. It continued operating until the early 1960s. Derivatives The principles of the ACE design were used in the Bendix Corporation's G-15 computer. The engineering design was done by Harry Huskey who had spent 1947 in the ACE section at the NPL. He later contributed to the hardware designs for the EDVAC. The first G-15 ran in 1954 and, as a relatively small single-user machine, some consider it to be the first personal computer. Other derivatives of the ACE include the EMI Electronic Business Machine and the Packard Bell Corporation PB 250. Footnotes Bibliography External links Oral history interview with Donald W. Davies, Charles Babbage Institute, University of Minnesota. Davies describes computer projects at the U.K. National Physical Laboratory, from the 1947 design work of Alan Turing to the development of the two ACE computers. Davies discusses a much larger, second ACE, and the decision to contract with English Electric Company to build the DEUCE—possibly the first commercially produced computer in Great Britain. Events in the history of NPL — ACE computer 1940s computers Alan Turing Early British computers One-of-a-kind computers English inventions 1940s in computing Computer-related introductions in 1950 Serial computers