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

Revisions

ZX80 kit version1980, self-assembly kit, cheaper than assembled unit

ZX80 (8K ROM upgrade)8K ROM1980, later units upgraded to 8K ROM, same as ZX81

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