Acorn BBC Micro & Electron¶
The British educational reference (1981): a 6502, robust, expandable, ubiquitous in UK schools (Elite was born on it). The Electron (1983) is its budget version. Standard 8-bit repair: recap, PSU RIFA, keyboard.
BBC Micro Model B — photo by Stuart Brady, domaine public (Wikimedia Commons).
Identification¶
| Model | Year | CPU | Note |
|---|---|---|---|
| BBC Model A / B | 1981 | 6502 @ 2 MHz | the school standard (B = 32 KB) |
| BBC Master | 1986 | 65C102 | evolution, more RAM/ROM |
| Acorn Electron | 1983 | 6502 | budget version (ULA, slower) |
SN76489 sound; RGB/composite output; a rich expansion bus ("Tube", 1 MHz bus).
Repair (technician)¶
- Recap + RIFA (PSU mains filter) → Recap; the RIFA smokes/explodes with age.
- Won't boot / unstable: regulator / RAM / socketed ROM → substitution.
- Keyboard: contacts / keys → clean.
- Floppy drive (5.25″ via interface): mechanism → clean / emulator.
- Electron: the ULA is the weak point (like the Spectrum) → cool/replace.
Common faults¶
| Symptom | Likely cause | Lead |
|---|---|---|
| Smoke at power-on | PSU RIFA | Replace the RIFA |
| Won't boot / unstable | regulator / RAM / ROM | Recap, substitute |
| Dead keys | keyboard | Clean |
| No picture (Electron) | ULA | Cool / replace |
Modernisation & mods — what to buy, how¶
PSU RIFA + recap
The BBC's PSU has RIFA caps that blow into smoke with age → replace them systematically on acquisition. Recap + check the regulator.
Modern storage
- BBC: Gotek + FlashFloppy or HxC 🟡 (5.25″/3.5″ floppy emulation); native SD solutions
(MMFS, Datacentre / SmartSPI boards) 🟡 that expose an SD card as a drive → load .ssd/.dsd.
- Electron: ElkSD 🟢 (SD via the cartridge port), Plus 1 + modern interfaces.
Video (the emblematic case) - The BBC's TTL RGB output is the original target of RGB2HDMI 🟡 (hoglet's Raspberry Pi project, born on the BBC) → crisp, zero-lag HDMI; otherwise SCART RGB 🟢 + OSSC/RetroTINK.
Expansion - PiTubeDirect 🟢: a Raspberry Pi on the Tube port emulates a second processor (fast 6502, Z80, ARM…) → a huge speed boost. - ROM/RAM boards (sideways ROM sockets) 🟢, Econet networking.
⚠️ Do not host ROMs/games — method only.
See also¶
- Archimedes (the ARM successor) · ZX Spectrum · Recap.
Sources & attribution¶
- Photo BBC Micro Model B — Stuart Brady, domaine public, Wikimedia Commons — https://commons.wikimedia.org/wiki/File:BBC_Micro_Front_Restored.jpg
- Wikipedia — BBC Micro / Acorn Electron (6502, SN76489, models) — CC-BY-SA — https://en.wikipedia.org/wiki/BBC_Micro
- Established Acorn community knowledge (RIFA, Electron ULA) — synthesis.
Review & corrections
How this space is used
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