Acorn Risc PC 700
 | |
| Risc PC 700 front panel (photo: Chris Whytehead) | |
| Specifications | |
|---|---|
| Manufacturer | Acorn Computers Ltd |
| Type | Desktop computer |
| Released | July 1995 |
| CPU | ARM710 at 40 MHz on a plug-in card |
| Memory | Two 72-pin DRAM SIMM sockets, up to 256 MB; 1 or 2 MB VRAM fitted |
| Storage | 3.5-inch floppy; IDE hard disc (425 MB to 1 GB); CD-ROM on some models |
| Display | VIDC20 |
| Sound | 8-channel, 16-bit |
| OS / Firmware | RISC OS 3.60 |
| Model no. | ACB70 to ACB78, ACB96 |
The Acorn Risc PC 700 is a desktop computer that Acorn Computers launched in July 1995 as an update of the Acorn Risc PC 600. It has a 40 MHz ARM710 processor card, RISC OS 3.60, VRAM and 16-bit sound as standard, and larger hard discs. Chris Whytehead gives the ARM710 as about 40 % faster than the original Risc PC 600.[1] 4corn notes that it cost the same as the 600 it replaced.[2]
Differences from the Risc PC 600
[edit | edit source]The 700 uses the same case, chip set (IOMD, VIDC20, SMC FDC37C665), processor-card slots, SIMM and VRAM sockets, backplanes and power supplies as the 600.[3] The differences are:
- An ARM710 processor card at 40 MHz (Chris's cards carry the VLSI VY86C710A).[1]
- A revised main board, 1208,000, with 16-bit sound on the board and a CD audio input.[1][4]
- RISC OS 3.60 in ROM, and VRAM fitted in every model.[1]
Acorn's 1994 Technical Reference Manual and its drawings describe the 600's 0197,000 board, not the 1208,000. The stardot user philpem calls the 1208,000 the "Series III" or "Rimmer" board, and owners repairing it on stardot have worked from the 0197,000 drawings, noting where the later board differs.[5]
Power supply
[edit | edit source]The power supply is the same unit as on the 600: +5.1 V (+2 %, −4 %), +12 V (±7 %) and −12 V (±7 %), in 70 W and 103 W versions. The 103 W supply is needed with the 4-slot backplane.[3] The full table is on Acorn Risc PC 600.
Main board
[edit | edit source]The 1208,000 board keeps the 600's arrangement of a rechargeable backup cell for the PCF8583 clock and CMOS RAM, and surface-mount aluminium electrolytic capacitors.[5] On one 1208,000 board the 10 µF, 4.7 µF and 1 µF surface-mount electrolytics had all leaked.[5] Battery leakage is the other common damage; one owner found it had run down the board as far as the reset switch.[6] See Acorn Risc PC 700 Maintenance Guide and Acorn Risc PC 700 Capacitor Guide.
Models
[edit | edit source]| Model | RAM | VRAM | Hard disc | CD-ROM |
|---|---|---|---|---|
| ACB70 | 4 MB | 1 MB | 425 MB | – |
| ACB71 | 4 MB | 1 MB | 425 MB | Yes |
| ACB75, ACB75A, ACB75B | 8 MB | 2 MB | 850 MB (75), 1 GB (75A, 75B) | – |
| ACB76, ACB76A, ACB76B | 8 MB | 2 MB | 850 MB (76), 1 GB (76A, 76B) | Yes (quad speed on 76A) |
| ACB77, ACB77B | 4 MB | 1 MB | 540 MB | – |
| ACB77A | 4 MB | 1 MB | 540 MB | Yes |
| ACB78, ACB78B | 4 MB | 1 MB | 540 MB | Quad speed |
| ACB96 | 8 MB | 2 MB | 850 MB | X Window system |
Source: Chris's Acorns.[1] On the late ACB75B the front flap reads simply "RiscPC".[1]
Documentation
[edit | edit source]- Acorn Risc PC Technical Reference Manual: covers the shared architecture, interfaces and power supply; its parts lists are for the 600's 0197,000 board.[3]
- File:Acorn Risc PC Technical Reference Manual drawings.pdf: Acorn's drawings for the 0197,000 board, processor card, VRAM cards and backplanes.
Related pages
[edit | edit source]- Acorn Risc PC 700 Maintenance Guide
- Acorn Risc PC 700 Troubleshooting Guide
- Acorn Risc PC 700 Capacitor Guide
- Acorn Risc PC 600
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Whytehead, Chris. "Acorn Risc PC 700", Chris's Acorns, archived by The Centre for Computing History (retrieved 2026-10-01). July 1995 launch; 40 MHz ARM710 (VY86C710A); RISC OS 3.60; VRAM standard, 16-bit sound, bigger hard discs; about 40 % faster than the original Risc PC 600; model list; his machines all have main board 1208,000.
- ↑ "The Acorn Risc PC and A7000", 4corn Computers (retrieved 2026-10-01). Risc PC 700: 40 MHz ARM710, larger RAM, at least 1 MB VRAM, larger discs and 16-bit sound as standard at the same price; shipped with RISC OS 3.60.
- ↑ 3.0 3.1 3.2 Acorn Computers, Risc PC Technical Reference Manual, part no. 0497,057, issue 1, September 1994, hosted on this wiki. System description Part 1; battery p. 1-10; backplanes and power requirements p. 1-21; parts lists Part 3 (for the 0197,000 board); Power On Self Test p. A-1; power supply data p. E-1.
- ↑ "RISC PC motherboard refurbish", stardot.org.uk forum thread, July 2020 to March 2022. The refurbished board is a "Series 3" 1208,000 board with CD audio input and 16-bit sound; electrolyte leaking from the surface-mount electrolytics; none passed an in-circuit ESR test.
- ↑ 5.0 5.1 5.2 "(Repair) RISC PC Series 3 (1208,000) motherboard", stardot.org.uk forum thread, July 2020 to November 2022. philpem's repair of a 1208,000 ("Series III" / "Rimmer") board: the 10 µF, 4.7 µF and 1 µF surface-mount electrolytics had leaked and the 47 µF parts had not; "CMOS unreadable" traced to the battery circuit (D2, R212, C70 and a failed via); a later poster notes that the drawings on Chris's Acorns are for the earlier board.
- ↑ "Where to start resurrecting a RiscPC 700", stardot.org.uk forum thread, April–May 2018. A corroded battery whose leakage had spread down the board to the reset switch; cleaning with white vinegar, rinsing and drying before power-up.