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Plessey was a British-based international radio, electronics and telecommunications company. Founded in 1917 in Marylebone, central London but moving to Cottenham Road in Ilford early in 1919 (and then to Vicarage Lane where it remained) it became one of the largest manufacturers in this field as the radio and television industries grew.
Plessey were partners in the development of the Atlas Computer in 1962 and in the development of Digital telephone systems - System X - during the late 1970s.
In 1988 Plessey and The General Electric Company (GEC) merged their telecom units to form GEC-Plessey Telecommunications (GPT), the UK's leading telecommunications manufacturer. This followed the barring of a full merger. In 1989 GEC and Siemens set up a jointly held company, GEC Siemens plc, to take over Plessey.
Plessey was divided as follows; Siemens acquired Plessey's radar systems, defence systems and traffic control businesses. (Siemens renamed the former defence businesses Siemens Plessey Systems). GEC took control of Plessey's avionics business and naval systems business. GEC was free to invest in Siemens Plessey businesses.
In 1991 Siemens purchased the remaining parts of the Plessey group in the UK. In 1997 British Aerospace acquired Siemens Plessey Systems. In 1999 Siemens acquired GEC's interests in Siemens Plessey. GEC acquired Siemens 40% interest in GPT the same year, renaming it Marconi Communications.
The company was taken over in 1998.
Plessey barcodes
Plessey is also a name for a barcode symbology developed by them, which is still used in some libraries and for shelf tags in retail stores, in part as a solution to their internal requirement for stock control. Its chief advantages are the relative ease of printing using the dot-matrix printers popular at the time of the code's introduction, and its somewhat higher density than the more common 2 of 5 and 3 of 9 codes.
Plessey barcodes use two bar widths. Whitespace between bars is not significant. The start element is a wide bar, and the stop element is two narrow bars. In between, the bars are in groups of four. High order bars appear leftmost. Narrow bars are zero and wide bars are 1.
This symbology is not self checking, though a modulo 10 or modulo 11 checksum (depending on application) is usually appended.
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