Sinclair ZX81 microcomputer with power pack and isntruction manual, manufactured by Sinclair Research Limited, British, 1981-1985

ZX81 microcomputer with power pack, manufactured by Sinclair Research Ltd, 1981. The ZX81 was the successor to the ZX80 of a year earlier, the first computer made to appeal to the mass market and designed to connect to a television set or tape recorder. The ZX81 contained the same microprocessor but had a better BASIC (Beginner's All Symbolic Instruction Code) programming language. It was also £30 cheaper than the ZX80 at under £100, with fewer chips and a simpler design. By December 1981, over 250,000 had been sold, giving Sinclair the largest microcomputer user base in the world at that time. In 1982 The ZX81 was marketed in the United States by the Timex Corporation under the new title of the Timex Sinclair 1000.