Sinclair Research "FM Wristwatch Radio", an LCD wristwatch with a radio attached. However, the watch had several problems and never went into full production. Sinclair had long had an interest in electric vehicles, and during the early 1980s he worked on the design of a single-seater "personal vehicle", eventually starting a company called Sinclair Vehicles Ltd in March 1983. He launched the Sinclair C5 electric vehicle on 10 January 1985, but it was a commercial disaster, selling only 17,000 units and losing Sinclair £7,000,000. Sinclair Vehicles went into liquidation later the same year. The failure of the C5, combined with those of
Sinclair Sovereign and information could only be taken from the memory onto the screen. Five keys were used for memory operations. The Sovereign used a Mostek MK50321N main integrated circuit, the same as the Sinclair Wrist Calculator and some variants of the Sinclair Cambridge. Clive Sinclair had assumed that people would prefer attractive illuminated LED displays to LCD displays, which incidentally also required more expensive CMOS chips. However, his calculators were designed with the assumption they would be turned off between calculations, which did not prove to be the case. Advertisements suggested that the batteries would last "about a year" under normal