ZX81

The Sinclair ZX81 was launched in March 1981 by Sinclair Research Ltd. as the successor to the ZX80. Designed to bring computing to the masses, it was sold in kit form for £49.95 or pre-assembled for £69.95. It featured a Z80-compatible CPU, 1KB RAM (expandable to 16KB and beyond), and connected to a TV for display. Its minimalist, membrane-keyboard design helped reduce costs, while its integrated BASIC interpreter made it accessible for beginners. Despite its limitations, the ZX81 sold over 1.5 million units worldwide, revolutionizing the UK home computing market and paving the way for the ZX Spectrum.

Specifications

Technical Information
Name	ZX81
Manufacturer	Sinclair Research Ltd
Launched	Sunday, March 1, 1981
Discontinued	3/1/1982
Country	United Kingdom
CPU	Zilog Z80 (or NEC D780C clone) @ 3.25 MHz
Power	9V DC (external PSU, typical draw ~700mA)
Storage	Cassette tape (300 baud)
Sound	None (external mods only)
Keyboard	40-key membrane keyboard
Graphics	Character-based with block graphics (no bitmap mode)
Display	Monochrome TV output (black & white, 24 lines text)
ROM	8 KB (includes BASIC interpreter)
RAM	1 KB onboard (expandable to 16 KB or more via RAM pack)