Acorn Archimedes A4000
 | |
| Acorn Archimedes A4000 | |
| Specifications | |
|---|---|
| Manufacturer | Acorn Computers Ltd |
| Type | Personal computer (three-box desktop) |
| Released | September 1992 |
| Discontinued | 1995 |
| Intro price | £949 ex VAT (2 MB, 80 MB hard disc, with monitor) |
| CPU | ARM250 @ 12 MHz |
| Memory | 2 MB RAM (expandable to 4 MB) |
| Storage | 3.5" floppy (1.6 MB); 3.5" IDE hard disc (80/105/210 MB) |
| Display | Analogue RGB, 15-pin VGA-type connector |
| Sound | 8-channel, 8-bit logarithmic (VIDC1a) |
| Dimensions | approx. 430 mm × 340 mm × 95 mm |
| Weight | approx. 6 kg |
| 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 Computers announced in August 1992 and shipped from September 1992. It was the "professional" member of a three-machine range built around the ARM250 processor, sold alongside the home-market A3010 and the education A3020.[1][2]
Where the A3010 and A3020 built the computer into a keyboard case, the A4000 put the same design into a slimline desktop box with a separate keyboard. Its specification is almost identical to the A3020; the practical difference is a 3.5-inch IDE hard disc in place of the A3020's 2.5-inch drive.[1][2]
Positioning
Acorn sold the A4000 as a "professional 3-box solution" for home-office and business use, above the home A3010 and the education A3020 but below the ARM3-based A5000.[1] It shipped in a beige slimline case with a detachable 103-key keyboard and a three-button mouse.[3] Acorn sold it in several bundles — Home Office, Learning Curve and Early Years — with model codes from AGC10 to AGC82.[1][2]
The launch price, quoted with an 80 MB hard disc and a colour monitor and excluding VAT, was £949.[2]
Processor
The A4000 uses the ARM250 at 12 MHz, the single-chip device that integrates an ARM2-class core, the MEMC1a memory controller, the VIDC1a video and sound controller, and the IOC input/output controller.[4] (Some period Acorn material lists the integrated I/O part as "IOMD"; that is a later Risc PC chip, and the ARM250 integrates the IOC.)[4][1] Two A4000s measured for Chris's Acorns returned about 7.19 and 7.61 MIPS on the ARMSi benchmark, and roughly 5,400–5,600 Dhrystones per second, which is in line with the 12 MHz ARM250 in the A3020.[1]
A Chips & Technologies 82C711 peripheral controller provides the IDE, floppy, serial and parallel interfaces in a single support chip.[5]
Memory and firmware
The A4000 ships with 2 MB of RAM. It is expanded to a 4 MB maximum with a plug-in RAM upgrade board (for example the Simtec unit) that fits over the on-board memory — the motherboard carries the base memory with sockets for the expansion cards, not standard PC SIMMs.[1][2] RISC OS is held in 2 MB of ROM (two devices); production machines carry RISC OS 3.11, dated 29 September 1992.[1]
Storage
The floppy drive is a 3.5-inch high-density unit formatted to 1.6 MB, driven by the 82C711.[3] Unlike the A3020's 2.5-inch drive, the A4000 fits a 3.5-inch IDE hard disc through the same on-board IDE interface. Documented drives are 80 MB, 105 MB (Conner CFS105A) and 210 MB (Conner CFS210A), depending on model.[1][2]
Ports and expansion
The rear panel carries, from left to right, the keyboard socket, a parallel printer port, a serial (RS232) port, an Econet socket (usually not fitted), a headphone socket and the analogue RGB video output, with the separate power supply at the left of the panel.[1] The video connector is a 15-pin VGA-style socket carrying analogue RGB.[3]
Internally the A4000 has one mini-podule expansion slot, the same single-slot arrangement as the A3010 and A3020, plus a network-interface slot for an Econet or Ethernet module.[1][3] Common additions were an Ethernet mini-podule and a RAM upgrade board.[1]
Case and power
The A4000 is a slimline three-box desktop: system unit, separate keyboard and monitor. The case has two 3.5-inch drive bays, one of them accessible from the front for the floppy drive.[2] Unlike the A3010 and A3020, whose power supply is built onto the main board, the A4000 has a separate cased mains power-supply module that Acorn treats as a replaceable service part.[6] The machine is unusually simple to open: two screws release the cover, after which the board and drives lift out.[1]
Differences from the A3010 and A3020
All three 1992 machines share essentially the same "Roadrunner"-family main-board design.[4] The A4000 differs as follows:
| Feature | A4000 (professional) | A3020 (education) | A3010 (home) |
|---|---|---|---|
| Form factor | Three box, separate keyboard | Single box, integral keyboard | Single box, integral keyboard |
| Hard disc | On-board IDE, 3.5" drive standard | On-board IDE, optional 2.5" drive | None fitted |
| Network socket | Yes | Yes | No |
| TV modulator | No | No | Yes |
| Joystick ports | No | No | Two (9-pin) |
| Power supply | Separate cased module | On-board | On-board |
Sources: Chris's Acorns and Wikipedia.[1][4]
Circuit diagrams and PCB
The A4000 main board is part 0194,600, codenamed "Roadrunner". Acorn documented the machine at module level in the Service Manual; the component-level circuit diagrams are in the Technical Reference Manual, both hosted on this wiki.
| Main PCB | Circuit diagram (sheet 1 of 3) |
|---|---|
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| Circuit diagram (sheet 2 of 3) | Circuit diagram (sheet 3 of 3) |
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Discontinuation
Acorn ceased A4000 production in 1995, with remaining stock sold into 1996; along with the A3020 it did not conform to newly introduced European electrical regulations.[4][2] The Acorn Risc PC took over as Acorn's desktop from 1994, and the entry-level role passed to the Acorn A7000.
General maintenance
The main maintenance jobs are the soldered NiCd backup battery, which leaks and corrodes the board around it, the separate mains PSU module, and the ageing IDE hard disc. See the Acorn Archimedes A4000 Maintenance Guide.
Troubleshooting
Common faults are battery corrosion, PSU-module failure, hard-disc failure, and no-picture symptoms caused by a monitor-type mismatch. Because the ARM250 integrates the processor, memory, video and I/O controllers, a fault inside it is a whole-device replacement. See the Acorn Archimedes A4000 Troubleshooting Guide.
Capacitor guide
The A4000 board uses conventional leaded electrolytics with surface-mount ceramic decouplers and is not affected by the surface-mount electrolyte leakage of the A5000, A4 laptop and Risc PC; the recap priority is the separate PSU module. See the Acorn Archimedes A4000 Capacitor Guide.
See also
- Acorn Archimedes A3020 — education sibling (same board, 2.5" drive)
- Acorn Archimedes A3010 — home-market sibling
- Acorn Archimedes A3000 — predecessor
- Acorn Archimedes A5000 — ARM3 flagship of the same era
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 Whytehead, Chris. "Acorn A4000", Chris's Acorns / The Centre for Computing History.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 "A4000", Arc Wiki.
- ↑ 3.0 3.1 3.2 3.3 "A4000 Specifications", ClassicAcorn.
- ↑ 4.0 4.1 4.2 4.3 4.4 "Acorn Archimedes", Wikipedia.
- ↑ "82C711", Arc Wiki.
- ↑ Acorn A3010, A3020 and A4000 Service Manual, Acorn Computers Ltd — hosted on this wiki.