Acorn A3010 & Acorn A3020
The Acorn A3010 and Acorn A3020 (launched in 1992) are closely related ARM250-based RISC OS desktops from Acorn’s “A30x0” family. They’re popular restoration targets, but (like many Acorn machines of this era) you should treat the CMOS/RTC battery as a high-priority inspection item.
This page is a repair-and-reference jumping point: a quick comparison, the most common issues, and links to the most useful manuals/technical PDFs.
Quick comparison
| Feature | A3010 | A3020 |
|---|---|---|
| CPU | ARM250 @ 12MHz | ARM250 @ 12MHz |
| Typical OS | RISC OS 3 (commonly seen as 3.11) | RISC OS 3 (commonly seen as 3.11) |
| Base RAM | Typically 1MB (also exists as a 2MB variant) | 2MB |
| Max RAM (typical) | 2MB or 4MB (upgrade-dependent) | 4MB |
| Floppy | 3.5" 2MB (1.6MB formatted) | 3.5" 2MB (1.6MB formatted) |
| IDE / internal HDD | No internal IDE hard disc interface | Optional internal 2.5" IDE hard drive (many were fitted) |
| TV modulator | Yes (home-oriented; RF/TV output) | No |
| Joystick ports | Yes (two Atari-style joystick ports) | No |
| Network interface slot | No (no built-in network slot) | Yes (network connector/slot; Econet/Ethernet via internal card) |
| Internal expansion | Single internal 8-bit expansion upgrade connector/slot | Single internal 8-bit expansion upgrade connector/slot |
| Common ports | Analogue RGB monitor output, audio out, serial, parallel, 3-button mouse | Analogue RGB monitor output, audio out, serial, parallel, 3-button mouse |
How to identify which model you have
- A3010: look for two joystick ports and a TV modulator/RF output on the rear panel.
- A3020: no joystick ports and no TV modulator; commonly has (or is prepared for) networking and may have an internal 2.5" IDE hard drive.
- Both use a “single-box” style case with an integral keyboard and similar rear-panel layout for RGB/serial/parallel/audio/mouse.
Common issues (repair-focused)
1) CMOS/RTC battery leakage (high priority)
- These machines use a rechargeable battery for the real-time clock and configuration memory. If it leaks, it can corrode traces, vias, and nearby connectors.
- Symptoms vary widely: loss of CMOS settings/time, intermittent keyboard/mouse problems, odd boot behaviour, and unstable operation.
- Many restorers remove the original rechargeable to stop ongoing damage and fit an alternative solution (research carefully so you don’t charge a non-rechargeable cell).
2) Power/PSU faults and instability
- The A3010/A3020 power circuitry involves hazardous mains voltages on the main PCB (see safety notes below). Age, heat, and capacitor degradation can cause intermittent start-up, sudden resets, or “dead” machines.
- If you’re not experienced with mains-powered electronics, treat PSU faults as “service/replace” rather than DIY repair.
3) Floppy drive faults
- Dirty heads, aged mechanisms, and alignment issues can cause read/write problems.
- Always test with known-good media before assuming the drive is faulty.
4) A3020-specific: hard drive / IDE issues
- Many A3020s were fitted with an internal 2.5" IDE HDD; original drives are now failure-prone (stiction, bad sectors, spin-up failure).
- For diagnosis, disconnect the HDD to see whether the machine boots reliably from floppy/ROM without it.
5) Keyboard flex/ribbon and connector issues
- Both machines have an integral keyboard with internal flex connections; oxidised contacts or damaged flex can cause intermittent keys or total keyboard failure.
First checks before extended power-on
- Open and inspect for battery leakage/corrosion before repeated power-ups.
- Photograph the board (battery area, ROMs, RAM area, connectors) for reference before cleaning/repair.
- Test minimal configuration: disconnect optional internal devices (especially the A3020 HDD) to separate “computer boots” from “storage boots”.
- Don’t assume RAM is good: if you have odd crashes, consider removing/trying different RAM upgrades if present.
- Use the manuals: the service manual includes functional tests (floppy, IDE, joystick, video, etc.) and PSU fault flowcharts.
Power & safety notes
- Hazardous voltages: the A3010 and A3020 have mains-related circuitry on the main PCB, and access to dangerous areas is restricted by internal metalwork/screening.
- Do not run without correct shielding/covers fitted. Besides safety, it can affect stability/EMI compliance.
- PSU repairs: if you are not qualified to work on mains power supplies, do not attempt board-level PSU repair. Use a known-safe service route.
Board revisions / “Adelaide” daughterboard notes
Early production A3010/A3020/A4000 units can be found with a daughterboard carrying a discrete implementation of the ARM250 (“Adelaide”/mezzanine-style), rather than the single ARM250 IC used in later boards. Documentation notes functional equivalence, but also highlights clock-generation and battery location differences between the two PCB versions.
For restorers, this matters mainly because: (1) the battery may be in a different location between issues, and (2) board issue/part numbers can help when comparing against schematics, parts lists, and known fixes.
Manuals & technical documentation
Core manuals (high value)
- Acorn A3010/A3020/A4000 Technical Reference Manual (TRM) (PDF)
- A3010/A3020/A4000 Module Level Service Manual (PDF)
- Acorn A3010 Welcome Guide (PDF)
- Acorn A3020 Welcome Guide (PDF)
Networking (A3020)
- Acorn A3020 & A4000 Network Interface Specification (PDF)
- A3020/A4000 Econet module installation instructions (ManualsLib)
Video/monitor details
Contemporary review / context
Reference/spec pages
- Classic Acorn: A3010 specs & production changes
- Classic Acorn: A3020 specs
- Chris’s Acorns: A3010
- Chris’s Acorns: A3020
- 4corn archive hub (docs/software)