Plessey

Early history The Plessey company was founded in 1917 in Marylebone, central London. The original shareholders were Thomas Hurst Hodgson, C. H. Whitaker, Raymond Parker and his brother Plessey Parker. A talented German engineer, William Oscar Heyne, was employed by the company. Heyne later became the managing director and chairman of Plessey and was one of the key figures in the development of Plessey during the 1920s and 1930s. both of whom rose to prominent positions in the company. Electrical manufacturing During the 1920s Plessey began to diversify into electrical manufacturing. Important contracts included the manufacture of early radios In the 1960s the Group continued to expand, setting up facilities at places such as West Leigh (Havant, Hampshire) and Templecombe, Somerset. In 1961 Plessey merged with Ericsson Telephones and Automatic Telephone Manufacturing Company of Liverpool, to become Britain's largest manufacturer of telecommunications equipment, including the majority of the country's crossbar switches. By 1972, Plessey designed the first industrial capability-based security computer, a fault-tolerant multiprocessor system called Plessey System 250. Plessey was also the lead contractor for the Ptarmigan communications system supplied to the British Army, which adopted the System 250 architecture. In contrast to the existing implementation, announced with a 200 ns cycle time, Plessey introduced Miproc with a 350 ns cycle time as part of a development system costing $. During the 1970s and early 1980s, Plessey manufactured a series of computer systems and peripherals compatible with Digital Equipment Corporation's PDP-11, some based on the Miproc product which was itself revised to operate with a faster 250 ns cycle time. The company would eventually expand its Miproc range to include the Miproc RTS, running the RTX real-time operating system, alongside Plessey's other product lines featuring semiconductor and bubble memory, and microprocessor-based data terminals. Plessey Controls, from 1982 to the mid-1980s, also manufactured a type of Geiger counter known as the Portable Dose Rate Meter (PDRM). It gave highly accurate readings, using the Gray system of measurement and used standard torch batteries. They were built for civil defence, but also used by the British Army. Most ended up in the hands of the Royal Observer Corps and manufacture would discontinue by the late 1980s. UK air defence In 1959 AT&E, later Plessey, became the prime contractor for a new UK air defence system, known by the company under the name Plan Ahead and, from 1961, as Project Linesman. To enable the system to be designed and built without too much information becoming public knowledge, a new factory called "Exchange Works" was built in Cheapside in Liverpool city centre, where young employees were granted exemption from conscription. At the heart of the system, installed in a huge building in the middle of a council housing estate in West Drayton, was the computer room, occupying an area of around and filled with around 1,000 racks of electronics, including mainly the XL4 computer, based entirely on germanium transistors and using a computer language developed at Exchange Works in the 1950s and 1960s. The instrument was invented by Dr. Trevor Lloyd Wadley of the Telecommunications Research Laboratory of the South African Council for Scientific and Industrial Research (CSIR), also responsible for the Wadley loop receiver, which allowed precision tuning over wide bands, a task that had previously required switching out multiple crystals. South African insurance and investment company Sanlam bought 26% of Plessey South Africa in 1974, with first right of refusal to purchase more of the company. These shares were later transferred to Sankorp, Sanlam's industrial holdings company. In 1989, when GEC-Siemens took control of the Plessey Company, Sankorp indicated its intention to purchase the remaining 74% of shares in the South African subsidiary. Australia Plessey had a manufacturing plant at Meadowbank in Sydney, Australia that made defense equipment and TVs. In the 1970s and 80s it produced Ericsson Crossbar Telephone Exchanges under licence for Telecom Australia and the PNG Post and Telegraphs department. GEC takeover bid In December 1985, GEC launched a takeover bid for the Plessey Company, valuing the group at £1.2 billion. Both Plessey and the Ministry of Defence were against the merger, since GEC and Plessey were the two largest suppliers to the MoD and in many tenders the only competitors. In January 1986, the bid was referred to the Monopolies & Mergers Commission (MMC), whose report published in August advised against the merger. The government concurred and blocked GEC's bid. ==Break-up of the business==

In April 1990, GEC and Siemens agreed a new structure of ownership of the Plessey businesses: GEC acquisitions • In the UK • Plessey Aerospace • Plessey Avionics • Plessey Crypto • Plessey Materials • Plessey Naval Systems • Plessey Semiconductors • Plessey Research Caswell • Plessey Microsystems • Plessey Controls • In North America • Plessey Aero Precision Corp • Plessey Dynamics Corp • Plessey Electronic Systems Corp (including ES Marine Systems) • Sippican • Plessey Materials • Leigh Instruments Siemens acquisitions • Siemens Plessey Radar • Siemens Plessey Defence Systems • Siemens Plessey Controls • Siemens Plessey Australia • Siemens Plessey Assessment Services • Roke Manor Research Jointly owned • GEC Plessey Telecommunications: 60% GEC and 40% Siemens Disposals • Birkby Plastics (1989-1990) • Hoskyns Group • Plessey Valdarno S.p.A. (Italy), sold to Magnetek in 1991 • 51% share in Plessey Telenet acquired by minority partner in 1992 • 74% share in Plessey South Africa acquired by minority partner Sankorp ==Subsequent history==

UK In 1997, British Aerospace and DaimlerChrysler Aerospace acquired the UK operations and the German part of Siemens Plessey Systems, respectively. By 1997, the GPT name disappeared in the UK and the company was known as Siemens GEC Communication Systems (SGCS), which later became Siemens Communications. In August 1998, GEC acquired Siemens' 40% stake in GPT (by now only existing as a legal entity) and merged GPT with the telecoms units of its other subsidiaries, namely Marconi SpA, GEC Hong Kong and ATC South Africa, to form Marconi Communications. In December 1999, GEC's defence arm Marconi Electronic Systems was amalgamated with British Aerospace to form BAE Systems. The remainder of GEC was renamed to Marconi plc, and Marconi Communications became its principal subsidiary. This company was affected by the dot-com bubble and was restructured into Marconi Corporation in 2003, then collapsed in 2005. Most of it (including Marconi Communications) was bought by Ericsson and the remainder became Telent. The part of GPT which evolved into Siemens Communications would eventually become Siemens Enterprise Communications in 2008. GEC Plessey Semiconductors (GPS) was purchased by Mitel Semiconductors of Canada in 1998. After a number of downsizes, including the purchase of the power semiconductor and silicon on sapphire operation at Lincoln, Lincolnshire by Dynex Semiconductor in 2000, the company renamed itself Zarlink Semiconductor in 2001. The GPS fabrication plant in Plymouth was acquired by Xfab. Plessey Semiconductors Ltd After the sale of the Roborough site in Plymouth to Xfab, the original Plessey Semiconductors site at Cheney Manor, Swindon continued to operate under the Zarlink Semiconductor name until it was sold to MHS Industries in early 2008. In February 2009, the UK business was forced into receivership following the collapse of the parent MHS Electronics business in France. After a subsequent management buyout the company traded as Plus-Semi Ltd. The Roborough site ( 8" and 6" lines) was re-acquired from Xfab on 1 January 2010 and the company renamed as Plessey Semiconductors Ltd. The new company transferred its bipolar processes on silicon and SOI into the 8" Plymouth facility during 2010, exploiting the combined technology base in the development of new processes and products in a number of markets. The Swindon site on the Cheney Manor Industrial estate in the west of the town was demolished in July 2012. In 2011/2, Plessey acquired the rights to disruptive GaN-on-silicon technology by acquisition of CamGaN, a startup company, from Cambridge Enterprises. Using the GaN-on-silicon technology and semiconductor expertise, Plessey Semiconductors Ltd manufactured solid state lighting, horticultural lighting and medical sensing products. Their GaN-on-silicon i2LED high power LEDs and Stellar Orion Beam Forming modules, launched in autumn 2016, which enabled new form factors of lighting products and remove critical design constraints for lighting product designers. In horticulture, the Plessey Attis Growlight was at the forefront of an engineering approach to LED based plant grow lights which was then developed into a new brand, Hyperion Grow Lights. The company's medical products were based on the EPIC sensor, which were used in the advanced portable ECG monitoring device, Impulse, and was also the basis of an R&D program, named Warden, to develop driver alertness monitoring devices in automotive and aeronautical applications. In 2017, Plessey pivoted the focus of the business to the R&D and manufacturing of microLEDs (micro light-emitting diodes) as a market disrupting display technology for a wide range of applications, including: Augmented Reality, Mixed Reality, smartphones, televisions, smartwatches, head-up displays, head-mounted displays and more. , Plymouth in August 2017 Plessey continues to operate in the Roborough site with leading-edge 150mm and 200mm wafer processing facilities to undertake design, test and assembly of products, and a comprehensive suite of photonic characterisation and applications laboratories. Their original microLED product was an illuminator for display light engines (DMD and LCOS), which offered a 40% reduction in light engine size whilst delivering higher energy efficiency. They have now upgraded to full-field emissive microLED displays that combine very high-density RGB pixel arrays with high-performance CMOS backplanes to produce very high-brightness, low-power and high-frame-rate image sources. These are innovative products that are widely recognised within the industry with many accolades from prestigious electronics, engineering and display industry award programs, including: Elektra Awards 2017, British Engineering Excellence Awards 2017, National Technology Awards 2018, CES Innovation Awards 2019 and Electronics Industry Awards 2019. In March 2019, Plessey used their GaN-on-silicon technology, which natively emits blue, to innovatively engineer the early layers within the process to emit native green, opening more opportunities for markets such as military. Plessey also achieved the world's first GaN-on-silicon monolithic, wafer to wafer bonding, in May which was a massive breakthrough for not only the company but the industry. In 2025, Plessey Semiconductors was acquired by Haylo Labs, using funding from Chinese AI smartglasses manufacturer Goertek Inc. The acquisition was given national security clearance after a review under the National Security and Investment Act 2021. South Africa In South Africa, following the successful GEC/Siemens takeover, after protracted negotiations in 1991, Plessey South Africa became a wholly owned subsidiary of Sankorp under the new name of Plessey Tellumat South Africa Limited (PTSA). The addition of the name Tellumat had a double symbolism, firstly for the company's commitment to exports, as it is the name of its UK-based export subsidiary. Secondly, the name derives from the Tellurometer, South Africa's world first electronic surveying development—and by implication, a commitment to ongoing electronic research and development. PTSA continued to grow with a strong focus on telecommunications and defence products, particularly with a major expansion into large projects, rolling out the microwave backbone of MTN, one of South Africa's first GSM cellular networks and the installation of a fibre optic network and radio broadcasting system in Malaysia. A software division was formed through the acquisition of BSW data, largely staffed by engineers from the recently terminated South African space programme in which PTSA had also participated, both in the electronics of the launch vehicle and the satellite itself. 1995 was a landmark year in the history of the business in South Africa. The merger of PTSA and Tek Electronics, the consumer electronics audio and video products, manufacturer and distributor, (also wholly owned by Sankorp) took the business full circle back to its consumer electronics roots. Tellumat continues to develop and manufacture Plessey-branded products as before and operates in the defence, telecommunications and contract manufacturing markets. ==Plessey barcodes== The name is also used to refer to a barcode symbology developed by Plessey, 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. The system was first used in the early 1970s by J.Sainsbury to identify all of its products on supermarket shelves for its product restocking system. The chief advantages are the relative ease of printing using the dot-matrix printers, which were 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 0 and wide bars are 1. This symbology is not self checking, though a modulo 10 or modulo 11 checksum (or some combination of both checksums, depending on application) is usually appended. ==References==