Acorn Archimedes A4000
 | |
| A4000 with monitor and keyboard (photo: Chris Whytehead, Chris's Acorns, CC BY-SA 3.0) | |
| Specifications | |
|---|---|
| Manufacturer | Acorn Computers Ltd |
| Type | Personal computer (three-box desktop) |
| Released | Announced August 1992, shipped September 1992 |
| Discontinued | 1995 |
| Intro price | £949 ex VAT (2 MB, 80 MB hard disc, colour monitor) |
| CPU | ARM250 at 12 MHz |
| Memory | 2 MB, expandable to 4 MB |
| Storage | 3.5" floppy (1.6 MB formatted); 3.5" IDE hard disc (80, 105 or 210 MB) |
| Display | Multi-frequency analogue RGB, 15-pin connector |
| Sound | Stereo (VIDC1a section of the ARM250); internal mono speaker |
| OS / Firmware | RISC OS 3.11 |
| Predecessor | Acorn Archimedes A3000 |
| Successor | Acorn A7000 |
| Codename | Roadrunner |
| Model no. | AGC10–AGC82 |
The Acorn Archimedes A4000 is a three-box desktop computer that Acorn announced in August 1992 and shipped from September 1992. It was the "professional" member of a range of three ARM250 machines, sold alongside the A3010 for home use and the A3020 for education.[1] Its specification is almost the same as the A3020's. The A3010 and A3020 build the computer into the keyboard; the A4000 has a separate keyboard and a slimline system unit, which takes a 3.5-inch IDE hard disc where the A3020 takes a 2.5-inch one.[1][2]
Models and price
[edit | edit source]Chris Whytehead lists these product codes:[1]
| Code | Configuration |
|---|---|
| AGC10 | Home Office |
| AGC20 | 2 MB, 80 MB hard disc |
| AGC40 | 2 MB, 105 MB hard disc |
| AGC50 | 2 MB, 210 MB hard disc |
| AGC80 | 2 MB, 210 MB hard disc, 14" monitor, Home Office |
| AGC81 | 2 MB, 210 MB hard disc, 14" monitor, Learning Curve |
| AGC82 | 2 MB, 80 MB hard disc, 14" monitor, Early Years |
Arc Wiki gives the launch price as £949 ex VAT with 2 MB, an 80 MB hard disc and a colour monitor, and the codename as Roadrunner.[3]
Hardware
[edit | edit source]The ARM250 combines the functions of the ARM2, MEMC1a, VIDC1a and IOC on one chip, running at 12 MHz.[4][2] Acorn's comparison table for the three models gives the A4000 2 MB of DRAM expandable to 4 MB, RISC OS 3 in 2 MB of ROM, a 2 MB (1.6 MB formatted) floppy drive, an optional internal 3.5-inch IDE hard disc, multi-frequency analogue RGB video, a stereo 3.5 mm 32 ohm audio output and internal mono speaker, a separate 103-key keyboard, an 8-bit internal expansion slot, a network expansion slot, a serial port, a parallel port, a real-time clock with configuration memory, a rechargeable battery for the clock, and an electronic identity number. There is no TV modulator and no joystick interface; those are A3010 features.[2]
Acorn's parts list for the A4000 main PCB places the main devices as follows:[2]
| Designator | Device |
|---|---|
| IC13 | ARM250 (Acorn 0294,030), 160-pin PQFP |
| IC17, IC18 | RISC OS ROMs (socketed) |
| IC21, IC22, IC31, IC32 | 256K × 16 DRAM, 80 ns, SOJ |
| IC33–IC36 | Socket strips; no device fitted as standard |
| IC24 | 82C711 peripheral controller (floppy, IDE, serial, parallel) |
| IC5 | PCF8583 real-time clock and CMOS RAM |
| IC12 | DS2400 electronic identity |
| IC10 | LM386 audio amplifier |
| BT2 | 1.2 V 280 mAh nickel cell, Acorn 0817,014 |
Links LK31 and LK32 set the memory size: 1–2 and 2–3 for 2 MB, 2–3 and 1–2 for 4 MB.[2] Chris Whytehead's two A4000s carry main board 0194,600 issue 1 and measure 7.19 and 7.61 MIPS on ARMSi v4.0 and 5,407 and 5,557 Dhrystones per second; one has a Simtec 4 MB upgrade.[1]
Ports and expansion
[edit | edit source]From left to right the rear panel has the keyboard socket, parallel port, RS232 serial port, an Econet position (not normally fitted), the headphone socket and the video output; the power supply is at the left.[1] The serial port is a 9-way D plug with the IBM PC-AT pinout.[2] Internally there is one mini-podule slot, as on the A3010 and A3020, and a network slot for an Econet or Ethernet module.[1][2] Acorn's TRM limits the expansion connector to 100 mA internal plus 500 mA external, and the network slot to 300 mA internal plus 150 mA external.[2]
Power supply
[edit | edit source]The A4000 has a separate cased power supply, a primary switched-mode design rated at about 24 W. The A3010 and A3020 instead have a transformer-based supply on the main board.[2] The supply connects to the main board through a four-way plug (PL26) carrying +5 V, 0 V, −12 V and +12 V.[2][5] Acorn's manual says +5 V feeds the main PCB, floppy drive and hard disc, and +12 V feeds pin 12 of the video connector SK1 (for a SCART television) and the A4000's hard disc. It treats the A4000 supply as a service-replacement-only item.[5]
The main board has its own fuses: FS1, a 2 A leaded fuse, and FS4, a 250 mA surface-mount fuse.[2]
Backup battery
[edit | edit source]The real-time clock and CMOS RAM are backed by BT2, a 1.2 V 280 mAh rechargeable nickel cell (Acorn part 0817,014) mounted upright on the main board.[2] On Chris Whytehead's board it is at the top right.[1] Old cells of this type leak and corrode the tracks around them; see Battery Explosion, Capacitor or Corrosion Damage and Battery Refurbishment.
Documentation and circuit diagrams
[edit | edit source]Acorn documented the A4000 at module level in the Acorn A3010, A3020 and A4000 Service Manual. The Acorn A3010, A3020 and A4000 Technical Reference Manual has the system description, links and plugs, and full parts lists for the A4000 main PCB; the circuit diagrams are hosted as separate images.
-
A4000 main board, part 0194,600 -
Circuit diagram, sheet 1 of 3 -
Circuit diagram, sheet 2 of 3 -
Circuit diagram, sheet 3 of 3
.png)
.png)
.png)
Discontinuation
[edit | edit source]Production of the A3020 and A4000 ended in 1995, with remaining stock sold during 1996, because they did not conform to new European Union electrical regulations. The A7000 then became Acorn's entry-level desktop.[4]
General maintenance
[edit | edit source]The main jobs are the backup cell, the separate power supply and the hard disc.
Troubleshooting
[edit | edit source]The troubleshooting guide covers Acorn's power-on self-test codes, the power supply checks and the functional tests.
Capacitor guide
[edit | edit source]Acorn's parts list gives every capacitor on the main board, including six surface-mount aluminium electrolytics.[2]
See also
[edit | edit source]- Acorn Archimedes A3020, the education model with the same chip set
- Acorn Archimedes A3010, the home model
- Acorn Archimedes A3000, the earlier ARM2 machine
- Acorn Archimedes A5000, the ARM3 machine sold above it
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Whytehead, Chris. "Acorn A4000", Chris's Acorns, archived by The Centre for Computing History. Launch, model list, port layout, disassembly, board part number 0194,600, and two documented machines with measured figures.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 Acorn Computers Limited, Acorn A3010/A3020/A4000 Technical Reference Manual, issue 1, January 1993: model comparison table p. 1-1; system timing p. 1-3; power supply p. 1-18; links and plugs p. 1-20; A4000 main PCB assembly parts list (issue 2) pp. 2-1 to 2-4. Hosted on this wiki as Acorn A3010, A3020 and A4000 Technical Reference Manual; the pages of the hosted scan are out of order.
- ↑ "A4000", Arc Wiki (retrieved 2026-10-01).
- ↑ 4.0 4.1 "Acorn Archimedes", Wikipedia (retrieved 2026-10-01): ARM250, A4000 compared with the A3020, end of production.
- ↑ 5.0 5.1 Acorn Computers Limited, Acorn A3010, A3020 and A4000 Module Level Service Manual, part number 0494,059, issue 1, September 1993: Part 1, fault diagnosis (PSU failure p. 1-3, power-on self-test and fault codes pp. 1-3 to 1-4); Part 2, disassembly (A4000 pp. 2-3 to 2-4); Appendices C and D, earth continuity and DC insulation tests; Appendix E, functional tests. Hosted on this wiki: Acorn A3010, A3020 and A4000 Service Manual.