Elliott 803

The Elliott 803 is a small, medium-speed transistor digital computer which was manufactured by the British company Elliott Brothers in the 1960s. About 211 were built. The 800 series began with the 801, a one-off test machine built in 1957. The 802 was a production model but only seven were sold between 1958 and 1961. The short-lived 803A was built in 1959 and first delivered in 1960; the 803B was built in 1960 and first delivered in 1961. Over 200 Elliott 803 computers were delivered to customers, at a unit price of about £29,000 in 1960 (roughly ). Most sales were of the 803B version with more parallel paths internally, larger memory and hardware floating-point operations. The Elliott 803 was the computer used in the ISI-609, the world's first process or industrial control system, wherein the 803 was a data logger. It was used for this purpose at the US's first dual-purpose nuclear reactor, the N-Reactor. A significant number of British universities had an Elliott 803. Elliott subsequently developed (1963) the much faster, software compatible, Elliott 503. Two complete Elliott 803 computers survive. One is owned by the Science Museum in London but it is not on display to the public. The second is owned by The National Museum of Computing (TNMoC) at Bletchley Park, is fully functional, and can regularly be seen in operation by visitors to that museum. The 803 is a transistorised, bit-serial machine; the 803B has more parallel paths internally. It uses ferrite magnetic-core memory in 4096 or 8192 words of 40 bits, comprising 39 bits of data with parity. The central processing unit (CPU) is housed in one cabinet with a height, width, and depth, of . Circuitry is based on printed circuit boards with the circuits being rather simple and most of the signalling carried on wires. There is a second cabinet about half the size used for the power supply, which is unusually based on a large nickel–cadmium battery with charger, an early form of uninterruptible power supply.