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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

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