What did Clive Sinclair invent

A. Plenty: the first electronic calculator, a hand-held personal computer and a pocket-sized television set, an electric three-wheeler and an electric-aided bike.< xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

Q. Hold up! One at a time please.

A. OK! Clive Marles Sinclair was born was born on 30 July, 1940. Both his father and grandfather were engineers. Leaving school at 18, he got a job with Practical Wireless magazine, rising to editor. Three years later he formed the Sinclair Radionics firm, soon launching a microamplifier, smaller than a matchbox.

Q. I'm beginning to see a theme here.

A. Indeed: miniaturisation. Sinclair marketed the first pocket calculator in 1972, the world's first digital wristwatch by 1976 and the first pocket television in 1977. (I've still got one of the first calculators - and it still works!) Then came computers.

Q. Miniature again

A. Got it in one. Before that, computers existed, but they were vast things that filled rooms and relied upon tape reels and index cards - the sort of thing you see in early James Bond films. In Britain, only Commodore had previously launched a personal computer: it cost 700, a small fortune in 1978. In January, 1980, Sinclair demonstrated the ZX80 at an exhibition in Wembley. You could buy it ready-assembled or in a kit and it cost less than 100.

Q. And the market expanded

A. Yes. In 1981 came the updated ZX81, then the ZX Spectrum 16K, costing 125, (or 175 for a 48k version) the next year. Sinclair sold 300,000 ZX81s and the firm was turning over 30 million. Business expanded and Sinclair was knighted in 1983.

Q. But I remember these computers - they were tiny things with rubber keys that you plugged into the spare TV. How did they develop into the PC that we now know and love

A. That came in 1984 with the Sinclair QL - short for Quantum Leap. Advanced features included multi-tasking and multi-window display. The launch was lavish, the computer got rave reviews - but the firm couldn't deliver them fast enough. By the end of May, the company had received more than 5 million for 13,000 machines, but had been able to deliver only a few hundred.

Q. And what about this three-wheeler

A. It was almost Sinclair's downfall. The Midas touch deserted him with this concept in personal transport: the Sinclair C5. It was, of course, a great idea: a small three-wheeler driven by a small motor powered by rechargeable batteries. But it got a bad press and the British public found it too extreme an invention:many were worried it was unsafe as well as impractical. Drivers were dwarfed by the other traffic and usually felt as if other motorists couldn't see them. This was a revolution, but the public was having none of it.

Q. But he carried on regardless

A. No. In 1986, Sinclair sold out to Amstrad.

Q. But he keeps on inventing

A. Absolutely. Most famous was the Zike: an ultra-light electric bicycle (weighing less than 11kg) with an electric motor hidden inside the frame. It has a top speed of 12mph and recharges itself when ridden down slopes. Launched in 1994, it cost 499.99. It didn't catch on. The world sometimes wasn't ready for Sir Clive Sinclair's inventions.

Q. What's he doing now

A. Sinclair now lives and works in his London penthouse flat. He enjoys classical music and is said to be 'passionate about poetry' as well as his life-long love of science and maths.

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By Steve Cunningham