GEEKDEX #0220
Sinclair ZX81
Computers · Sinclair Research
The £49.95 kit computer that brought Sinclair to the masses — a touch-membrane keyboard and just 1 KB of RAM.
The ZX81 (1981) was Sinclair’s follow-up to the ZX80, redesigned around a single ULA chip to cut the component count and the price — sold as a build-it-yourself kit for £49.95 or assembled for £69.95. Its 1 KB of RAM was punishingly small even by the standards of the day, expandable only via the notoriously wobble-prone rear-mounted 16K RAM pack, and the touch-sensitive membrane keyboard traded feel for cost. It sold in huge numbers regardless, and directly set up the ZX Spectrum a year later.
Reference photo: Wikimedia Commons (“Sinclair-ZX81.png” by Evan-Amos), CC BY-SA 3.0.
- Identity
Category Computers Manufacturer Sinclair Research Architecture 8-bit Released 1981 Region United Kingdom Launch price £49.95 (kit) / £69.95 (assembled) - Hardware
CPU Zilog Z80A @ 3.25 MHz RAM 1 KB (expandable to 16 KB via RAM pack) Storage 8 KB ROM Display 32×24 text, monochrome (chunky block graphics, no true bitmap mode) Video out UHF/PAL (composite on later boards) OS Sinclair BASIC Expansion Rear edge connector (RAM packs, printer, etc.) Keyboard 40-key touch-sensitive membrane
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