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1 x digital article [PDF] available by request. The Sperry 1412 computer’s design was first postulated at Sperry Gyroscope’s Bracknell R & D department in 1967. The first prototypes appeared in 1969. It was initially developed as a ‘skunk-works’ project, an undercover experiment in digital technology new to the company. (Sperry Gyroscope at Bracknell hosted the world’s largest analogue computer at that time, used for simulation of the flight control systems for Sea Slug and Sea Dart missiles both manufactured at Bracknell.) Its applications were initially thought to be in the aerospace industry where a fast, general-purpose digital computer of shoebox dimensions and low weight would appeal to system designers. In fact, most applications were for the British and French Navies. Those applications were the Exocet missile pre-launch fire control system for the French and British Navies, the Sea Archer GSA.7 gunfire control system for the Royal Navy and project Chevaline - a secret British upgrade to American Polaris Nuclear missiles, giving them a decoy capability. It is now more than 50 years since the Sperry 1412 computer first entered service with the French Navy. In 2023, MBDA confirmed that there were several French Navy Exocet MM40 systems still using the 1412A computer – an in-service life then of 48 years and counting. The Sperry 1412 computer was a remarkable machine that went on to have an equally remarkable in-service life. Yet few have been aware of its existence. For project Chevaline, civil servants described it as ‘the electronics unit’ in an attempt to disguise the fact that it was a commercially available digital computer. The team at Bracknell developed a whole raft of ingenious solutions to practical problems – some examples: The smallest lightest general -purpose digital computer of its time. After Apollo, the first use of Fairchild integrated circuits in a production computer. First use of RISC techniques in a production computer. First demonstration of a vector graphics display from a UK company. First use of Analogue Devices A-D and D-A solid state converters. First digital gunfire control system for the Royal Navy (GSA.7) and the prototype for GSA.8 -still in service today on UK Type 23 Frigates. First operational digital interface for the Royal Navy 4.5-inch Mk8 Naval gun. Chevaline, the first manoeuvrable exo-atmospheric vehicle after Apollo. Development of Triple Modular Redundancy (TMR) for protection against Electro-Magnetic Pulse (EMP). And according to Roy Dommett’s oral history for the British Library (Ref21) an inspiration for European and American projects that followed. Peter has written this article to create a public record of the team’s work. And to document how computer technology, specifically software development, looked in the 1970’s and early 1980’s. Fortan, Cobol and Algol programming languages existed for early business computers but not for military machines. For the latter, programs were written in machine-code or assembler language. In those days there were no bulk storage devices – no hard drives, no internet, no broadband, no web servers. Just 720 Kbyte and 1440 Kbyte floppy discs and huge reels of paper tape. Computer memory was measured in bytes and Kilobytes – no Megabytes, no Gigabytes and no Terabytes. This is the story of an extraordinary computer, the projects it was applied to and the people that made it happen.