Timex Sinclair was a joint venture between the British company Sinclair Research and Timex Corporation in an effort to gain an entry into the rapidly-growing early-1980s home computer market in the United States. British inventor Sir Clive Marles Sinclair build and introduced the ZX80 in 1980, an inexpensive computer designed to bring computing to the masses. The tiny machine output black & white video and had a built-in RF modulator to display on one of two TV channels. The 1K ZX80 was updated to the ZX81 in March 1981 with 2K of memory. In July 1982 watch maker Timex began selling the Timex Sinclair 1000 clone of the ZX81 at their dealership network in the United States. At a retail price of $99.95, this was the first fully assembled computer for less than $100. Unfortunately, the little computer became known as the “doorstop” because so many were returned (50%) or just discarded. Thus the only thing they were useful for was as a doorstop! Timex withdrew from the personal computer business in 1984.