Sinclair ZX81

Summary

In 1980, the British company Sinclair Research launched the ZX80 for under $200. A year later, the new and improved version ZX81 will be released for half the price. It’s the first computer to cost under $100. With a simple design and low chip equipment, Sinclair can keep production costs low.

The ZX81 has a Z80 CPU (3.25 MHz clock), BASIC in the ROM, a TV connection (black-white, 64 x 48 pixels) and only 1 KiB memory, which is still expandable. The input takes place via a membrane keyboard and is therefore easy to clean. The buttons are so close together that fast typing is impossible. Third-party manufacturers produce external keyboards.

As a kit, the ZX81 is available for USD 99.95 and as a ready-to-use device for USD 149.95. In the first 12 months, Sinclair sells half a million devices, an estimated 1.5 million devices — in 1984 production ends.

Due to its low memory, the ZX81 expansion port was very important for its users. Most popular was a module that increased the memory by 16 KiB.