Sinclair ZX81

ZX81 · 1981–1984 · desktop

Specifications

Cpu: Zilog Z80A, 3.25 MHz
Ram: max: 16 KB with a plug-in RAM pack · base: 1 KB
Ports: Rear edge-connector expansion bus (RAM pack, later add-ons) · Cassette in/out (ear/mic jacks) · RF TV output
Display: Monochrome only, 32×24 characters/blocky graphics over RF to a TV
Storage: base: Cassette tape via a domestic tape recorder (no internal storage) · options:
Os Support: latest: Sinclair BASIC in ROM · shipped: Sinclair BASIC in ROM
Release Price: £69.95 assembled, £49.95 as a kit

Variants

Revisions

ZX81 kit version1981, cheaper self-assembly kit option

Timex Sinclair 1000TS10001982 US rebadge under Timex license, 2KB RAM

Timex Sinclair 1500TS15001983 US redesign in Spectrum-style case

Storage

1KBstandard onboard RAM

16KB RAM packofficial Sinclair ZX RAM pack expansion, sold as bundle

Upgrade paths

RAM

16 KB via the official Sinclair RAM pack plugged into the rear edge connector · Famous for 'RAM pack wobble': the pack was only held on by the edge connector's friction, and the slightest knock could crash the machine and lose unsaved work.

~£49.95 for the 16 KB RAM pack at the time

EASY