A small personal computer released in the United Kingdom in 1982. Based on a Zilog Z80 processor running at 3.5 MHz, the Spectrum came with either 16Kb or 48Kb of memory (an expansion pack was also available to upgrade the former). Output was to a TV, with a simple colour graphic display. A rubberised keyboard on top of a membrane (similar to a calculator) was marked with BASIC keywords, so that when in programming mode pressing 'G', for example, would insert the BASIC command GOTO. Programs were stored on a normal cassette recorder.
The Spectrum's video display, although rudimentary by today's standards, was perfect at the time for display on portable TV sets, and didn't hold games development up much. The text mode display was 32 columns x 24 rows, with a choice of 8 colours in either normal or bright mode, which gave 16 shades. The graphics resolution was 256x192 with the same colour limitations. The Spectrum had an interesting method of handling colour; the colour attributes were held in a 32x24 grid, separate from the text or graphical data, but was still limited to only two colours in any given character cell. This led to what was called colour clash or attribute clash with some bizarre effects in arcade style games.
Retailing for GBP125 for the 16 Kb and GBP175 for the 48 Kb model, the Spectrum was the first mainstream home computer in the UK, similar in significance to the Commodore 64 in the USA (this was also a rival to the Spectrum in the UK). A slightly modified version of the Spectrum, in a silver colored case with hard plastic keys, was sold in the USA by Timex as the TS2068. It had an extra 8K extension ROM, a cartridge port, two joystick ports and a AY-3-8912 sound chip with extra Sinclair BASIC commands to support these devices (STICK, SOUND).
Several peripherals for the Spectrum were marketed by Sinclair: the printer was already on the market, as the Spectrum had retained the control code for the ZX81's printer. The Interface 1 added a standard RS-232 port, a local area networking port and the ability to connect microdrives, tape-loop storage devices which were later used on the Sinclair QL. Sinclair also released the Interface 2 which added two joystick ports and a ROM cartridge port.
(something about third-party peripherals here.)
Later models of the machine included the ZX Spectrum+, with an improved keyboard, and the ZX Spectrum 128, with improved sound and 128 kB of RAM. After Amstrad's buyout of Sinclair Research in 1986, two more version were released: The ZX Spectrum +2 (with a built-in cassette recorder) and the ZX Spectrum +3 (with a built-in 3-inch floppy disk drive).
A number of current leading games developers began their careers on the ZX Spectrum, including Ultimate Play The game (now known as Rare, Inc), Peter Molyneux (ex-Bullfrog Games, and Shiny Entertainment.