Acorn Risc PC 600
 | |
| Acorn Risc PC (slice case) | |
| Specifications | |
|---|---|
| Manufacturer | Acorn Computers Ltd |
| Type | Personal computer |
| Released | April 1994 |
| Intro price | £1,249–1,699 (ex VAT, 1994) |
| CPU | ARM610 @ 30 MHz (33 MHz from mid-1995) |
| Memory | DRAM via 72-pin SIMMs (up to 256 MB) + 1–2 MB VRAM |
| Storage | On-board IDE hard disc, 3.5" floppy, optional CD-ROM |
| Display | VIDC20, up to 16.7 million colours |
| Sound | 8-channel (8-bit; 16-bit from mid-1995) |
| OS / Firmware | RISC OS 3.50 (later 3.60) |
| Predecessor | Acorn Archimedes A5000 |
| Successor | Acorn Risc PC 700 |
| Model no. | ACB15, ACB25, ACB45 (and later variants) |
The Acorn Risc PC 600 was launched in April 1994 as Acorn's first major hardware change since the A5000 and the ARM3 in 1990. It introduced the slice-based stackable case, a plug-in CPU card with a second processor socket, and a new chipset built around IOMD and VIDC20.[1] It ran RISC OS 3.50.
Architecture
The processor sits on a small plug-in card; one of the two CPU sockets can take a second processor, and Acorn supplied x86 (486/586) "PC cards" so the machine could run RISC OS and PC software on the same hardware.[2] The launch CPU was the 30 MHz ARM610 (ARMv3), with the memory-management unit on the CPU rather than in a separate MEMC.
| Function | Device |
|---|---|
| CPU | ARM610 @ 30 MHz (on a plug-in CPU card) |
| Memory + I/O controller | IOMD |
| Video and sound | VIDC20 |
| Peripheral 'Combo' controller | SMC FDC37C665 (floppy, IDE, serial, parallel) |
Source for the chipset and peripheral controller: the Acorn Risc PC Technical Reference Manual.[3]
Memory and video
Main memory is fitted as 72-pin DRAM SIMMs (FPM or EDO), up to 256 MB, with the MMU inside the ARM. The Risc PC was Acorn's first machine to support dedicated video RAM: 1 or 2 MB of VRAM clocked faster than main memory, which allowed higher resolutions and colour depths. VIDC20 was the first Acorn video controller able to display more than 256 colours, up to 16.7 million (24-bit).[2]
Expansion and the slice case
The case is built from stackable "slices": the base holds the motherboard, PSU and a drive bay, and extra centre sections add drive and podule capacity. The TRM notes the PSU may need upgrading if more than two sections are used.[3] The machine has two podule slots on a backplane (a 2-way 0197,101 or 4-way 0197,001), a separate network slot for Econet or Ethernet, and the OPEN bus supports up to eight podules. It uses a standard PC-AT keyboard with Acorn's three-button quadrature mouse.[1]
Models
The launch models were the ACB15 (2 MB), ACB25 (4 MB, 1 MB VRAM) and ACB45 (8 MB, 1 MB VRAM, second case slice), all with IDE hard discs. The Risc PC 600 CD (ACB28/ACB48) added an internal CD-ROM in January 1995. From July 1995, alongside the launch of the Risc PC 700, the 600 was upgraded to a 33 MHz ARM610, 16-bit sound and RISC OS 3.60 (the ACB60–ACB69 models), with various bundled-software packages (ACB80–ACB88) and X-terminal variants (ACB98/ACB99).[1]
Board and battery
The main PCB is part 0197,000 (issues A, C, D). It carries on-board SMD fuses (FS1, 2 A; FS2, 800 mA) and a NiMH backup battery (BT1, 1.2 V) for the CMOS configuration.[3] Later StrongARM CPU cards (RISC OS 3.70) and the various x86 PC cards drop straight into the CPU sockets.
Maintenance and repair
Like the Acorn Archimedes A5000 and the Acorn A4 laptop, the Risc PC main board uses surface-mount aluminium electrolytic capacitors that leak with age and corrode the board. See the dedicated pages:
- Acorn Risc PC 600 Maintenance Guide
- Acorn Risc PC 600 Troubleshooting Guide
- Acorn Risc PC 600 Capacitor Guide
See also
References
- ↑ 1.0 1.1 1.2 Whytehead, Chris. "Acorn Risc PC 600", Chris's Acorns / The Centre for Computing History. Source for the launch date, the chipset (VIDC20, IOMD), the memory (up to 256 MB DRAM SIMMs + 1–2 MB VRAM), the PC-AT keyboard, the model list (ACB15–ACB99), the board part number (0197,000), and the mid-1995 upgrade to a 33 MHz ARM610, 16-bit sound and RISC OS 3.60.
- ↑ 2.0 2.1 "The Acorn Risc PC and A7000", 4corn Computers. Source for the dual-CPU capability and x86 PC cards (33 MHz 486 up to 133 MHz IBM 586), the move of the MMU on-board the CPU, VIDC20's 24-bit colour, and the 8-channel 16-bit sound.
- ↑ 3.0 3.1 3.2 Acorn Risc PC Technical Reference Manual (Issue 1, September 1994; part 0497,057), Acorn Computers — hosted on this wiki. Source for the IOMD/VIDC20/FDC37C665 architecture, the main-PCB parts list, the on-board fuses FS1 (2 A) and FS2 (800 mA), the NiMH backup battery (BT1), and the Power On Self Test.