The ZX81 was a home computer released in the United States in a slightly modified form from the Timex Sinclair 1000. The ZX81 was produced by Sinclair Research and manufactured by the Timex Corporation. It was launched in the United Kingdom in 1981 as the successor to Sinclair's ZX80. Like the ZX80, it was a low-cost INTRODUCTION to home computing for the general public. It was a huge success, and over 1.5 million units were sold.
To make the machine affordable, the ZX81 was DESIGNED to use as few components as possible. For video, it CONNECTED to a home television set. Programs were loaded and saved onto AUDIO cassette tape. It had one kilobyte of onboard RAM. The machine had no moving parts, not even a POWER switch, and used a pressure-sensitive membrane keyboard for input.