Sinclair ZX 81 computer with Memopak 16 and UK700 power supply. Signs of wear, not tested. The combination of the Sinclair ZX81 computer and the Memotech Memopak 16K RAM expansion represents one of the most iconic retro computing pairings from the early 1980s. Launched in 1981, the Sinclair ZX81 was a revolutionary, low-cost home computer powered by a Z80 processor. It was famous for its tiny plastic wedge casing, an integrated film membrane keyboard, and having just 1KB of onboard RAM. While 1KB was enough for simple BASIC programming, it severely limited the complexity of software and games. Introduced in 1982 by third-party manufacturer Memotech, the Memopak 16K was designed to lift the ZX81 into the big leagues of home computing.