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Sinclair ZX80

ZX80 · 1980–1981 · desktop

Specifications

Cpu: NEC D780C (Z80 clone), 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, 32x24 characters/blocky graphics over RF to a TV; screen blanks during CPU-driven calculation on the earliest ROM
Storage: base: Cassette tape via a domestic tape recorder (no internal storage) · options:
Os Support: latest: Sinclair BASIC in ROM; a revised ROM later in production reduced screen flicker during computation · shipped: Sinclair BASIC in ROM (4 KB ROM)
Release Price: £99.95 assembled, £79.95 as a kit

Variants

Models

Kit versionCheaper self-assembly option at £79.95, undercutting the pre-built £99.95 unit; both used the same white plastic case and membrane keyboard.

Upgrade paths

RAM

16 KB via the official Sinclair RAM pack plugged into the rear edge connector · Same edge connector and 'RAM pack wobble' problem later inherited by the ZX81: a knock to the loosely seated pack could crash the machine and lose unsaved work.

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

EASY

CPU

No practical CPU upgrade; some hobbyists later fitted faster NMOS Z80 replacements for reliability, not speed · Not a real performance path, mainly a repair swap when the original NEC clone chip failed.

~£5 for a replacement Z80-family chip

HARD