The Sinclair ZX81 was released 1981 in the UK and later in 1982 in a slightly modified form as the Timex Sinclair 1000 in the United States. Designed as a low-cost introduction to home computing, the ZX81 was designed to be small, simple, and cheap.
In place of a dedicated monitor, the ZX81 was designed to output video to standard television set. Programs and data were loaded and saved from standard audio tape cassettes. The much-loathed pressure-sensitive membrane keyboard was a result of the cost-cutting in the desing of the ZX81, later resolve with it’s US successor the Timex Sinclair 1500.
Marketed to the mass public, the Sinclair ZX81 sought to bring computing to the general public and shed the sterotypes of computers being for only hardcore computer hobbyists. Sold in both kit form and assembled, only two official perhiperhals for the ZX81 were released – a 16kB RAM pack, and the ZX Printer. A plethora of third-party accessories such as proper keyboards, RAM packs with increased reliability, and hard disk interfaces helped the ZX81 compete against it’s technically superior, but more expensive competitors such as the Commodore VIC-20 and Texas Instruments TI 99-4/a.