commercial sector of computing, but left the industrial field free. Some of the technology of the FP 6000 was later used in its Ferranti Argus range of industrial computers which were developed in its Wythenshawe factory. The first of these, simply Argus, was initially developed for military use. Meanwhile, in Bracknell the Digital Systems Division was developing a range of mainframe computers for naval applications. Early computers using discrete transistors were the Hermes and Poseidon and these were followed by the F1600 in the mid 1960s. Some of these machines remained in active service on naval vessels for many years. The FM1600B was the first of the range to use integrated circuits and was used in many naval and commercial applications. The FM1600D was a single-rack version of the computer for smaller systems. An airborne version of this was also made and used aboard the RAF Nimrod. The FM1600E was a redesigned and updated version of the FM1600B, and the last in the series was the F2420, an upgraded FM1600E with 60% more memory and 3.5 times the processing speed, still in service at sea in 2010. Semiconductors Ferranti had been involved in the production of electronic devices, including radio valves, cathode-ray tubes and germanium semiconductors for some time before it became the first European company to produce a silicon diode, in 1955. In 1972 they launched the ZN414, a single-chip AM radio integrated circuit in a 3-pin package. Ferranti Semiconductor Ltd. went on to produce a range of silicon bipolar devices, including, in 1977, the Ferranti F100-L, an early 16-bit microprocessor with 16-bit addressing. An F100-L was carried into space on the amateur radio satellite UoSAT-1 (OSCAR 9). Ferranti's ZTX series bipolar transistors gave their name to the inheritor of Ferranti Semiconductor's discrete semiconductor business, Zetex Semiconductors plc. In the early 1980s, Ferranti produced some of the first large uncommitted logic arrays (ULAs), used in home computers such as the Sinclair ZX81, Sinclair ZX Spectrum, Acorn Electron and BBC Micro. The microelectronics business was sold to Plessey in 1988. Acquisition of International Signal and Control In 1987 Ferranti purchased International Signal and Control (ISC), a United States defence contractor based in Pennsylvania. The company subsequently changed its name to Ferranti International plc. and restructured the combined business into the following divisions: Ferranti Computer Systems, Ferranti Defence Systems, Ferranti Dynamics, Ferranti Satcomms, Ferranti Telecoms, Ferranti Technologies and International Signal and