Jupiter Ace

The 1982 oddity designed by ex-Sinclair engineers (Vickers & Altwasser): instead of BASIC it runs FORTH — faster and more compact. Z80A, B&W, 1 KB of RAM, cassette. Rare and much sought-after. Standard 8-bit repair: recap, SRAM, membrane.

Jupiter Ace — photo by Dutra de Lacerda, domaine public (Wikimedia Commons).

Identification

• CPU: Zilog Z80A @ 3.25 MHz; 1 KB RAM (expandable 16/48 KB); FORTH ROM.
• Video: B&W text/graphics → RF output (composite mod common).
• TTL logic (no custom ULA like the Spectrum); ZX-style membrane keyboard.

Repair (technician)

• Recap + check the external PSU → Recap.
• 2114 SRAM (the 1 KB RAM): a frequent failure → substitution / test.
• Membrane keyboard: broken flex → membrane replacement (a remade part).
• TTL logic: diagnose by substitution (no ULA makes repair easier).

Modernisation & mods — what to buy, how

• RAM expansion (16/48 KB) remade 🟢: near-mandatory to make the machine actually usable (1 KB stock).
• Storage: cassette via audio 🟢 (PC/phone); community SD interfaces 🟡.
• Video: RF output → composite mod 🟡 for a crisp modern display.
• Reproductions: remade boards / clones (e.g. the Ace-inspired "Minstrel") to preserve the platform without wearing out the original.
• Reliability: light recap; clean keyboard/membrane.

⚠️ Do not host ROMs/software — method only.

See also

• ZX Spectrum · ZX80/81/QL (same Sinclair school) · Recap.

Sources & attribution

• Photo Jupiter Ace — Dutra de Lacerda, domaine public, Wikimedia Commons — https://commons.wikimedia.org/wiki/File:Jupiter-ACE_small_system.JPG
• Wikipedia — Jupiter Ace (Z80A, FORTH, 1 KB RAM) — CC-BY-SA — https://en.wikipedia.org/wiki/Jupiter_Ace
• Established Ace community knowledge (2114 SRAM, membrane, clones) — synthesis.

Review & corrections

How this space is used

Spotted a wrong value, an outdated procedure, a chip reference that does not match your board? Say so here, with what you observed (model, board revision, serial number, measurement). Every report is cross-checked against a source before anything changes — an unverifiable correction is published as “reported by …, not cross-checked” rather than silently applied.

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