Psion was established in 1980 as a software house with a close relationship with Sinclair Research. The company developed games and other software for the ZX81 and ZX Spectrum home computers, released under the Sinclair/Psion brand. Its name means "Potter Scientific Instruments." after the company's founder David Potter. The acronym PSI was already in use elsewhere in the world so ON was added to make the name PSION unique. David Potter remained and managing director until 1999 and currently is still chairman of the company. Psion's games for the ZX Spectrum included Chess, Chequered Flag, Flight Simulator and the Horace series.