On a flee market in Sete (France), I once had the chance to look at a Spectrum+3 computer, the one and only I have ever seen. The operating system looked somewhat similar to a C64. The owner of this computer sold it with hundreds of games for a few bugs later on. The first time I played a Sinclair game was on an emulator for Linux, though.
In 1962 (Sir) Cive Sinclair founded the Sinclair Radionics.
This company sold radios and amplifiers. Sinclair invented
many different electronical products like a pocket
calculator, one of the first digital watch, a pocket TV,
digital multimeters and at least home computers.
In 1980, he produced his first computer the ZX 80. After
this one he sold the successor of the ZX 80, it was the ZX81.
This computer really got famous and he sold over
2'000'000 computers. in 1986, Amstrad bought his company.
Sinclair changed the company name once more and called his
new company cambridge research. The latest gadget from
Sinclair is a Zike, a bycicle with an electro motor hided in
its frame.
This was the first low cost home computer made in 1980.
Sold over 2'000'000 times (1981). There exist many compatible rebuilds all over the world. It has 1kB RAM only!
Known as the the game computer No.1 in England and got really famous. That's why Sinclair became a 'Sir' in 1992
Same as the spectrum but with a better keyboard and an additional reset switch. (1984)
The new model with 128kB RAM and a new ROM (the old one is still included for compatibility reasons!)
This was Sinclairs first computer (1987) after the takeover of Amstrad sold with an internal tape drive.
The last Spectrum produced by Amstrad with an internal 3" floppy drive.
The operating system was developed by Clive Sinclair and was in fact a BASIC language. The commands where selectable by a single key press.