The ZX Spectrum is a line of 8-bit personal computers from British company Sinclair Research. It was hugely successful in its homeland, as well as in the Eastern Bloc and in Brazil in the form of unlicensed clones. In the US, authorized clones were sold by Timex, without the same success.
Being so popular, the Spectrum has a quite huge gaming library. However, overambitious plans and some poorly received products led to financial difficulties to Sinclair; the company was bought by long-time rival Amstrad, who continued to produce the Spectrum line until the early 90s.
Earlier models had no joystick adapters, which would only be added in the later models.