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The RiscPC is a series of computers released by Acorn Computers Ltd starting in 1994. It is a successor to the Archimedes architecture.



The RiscPC does not have a CPU on the motherboard. Instead, two OpenBus connectors are provided for CPU cards. The main CPU was provided by a card containing an ARM610, ARM710 or StrongARM CPU. Cards containing ARM600, ARM700 and ARM810 are known to exist but either were not released or were released in very small numbers.

The second OpenBus connector is commonly used for a PC card. These cards contain a 486-class CPU, a Gemini family ASIC and a level 2 cache.

Multi-ARM configurations were prototyped, via the "Duet" ARM610 card[3] and the Simtec Electronics Hydra system, however did not made it to market.


The RiscPC has two 72-pin SIMM slots, supporting a maximum of 256 MB of fast-page mode DRAM. It also has a DIMM slot for 1 or 2 MB of VRAM.

The monitor is connected via a VGA connector.


VIDC20 officially provides resolutions up to 1280x1024 (110 MHz pixel clock), with up to 16.7 million colours. Video data can be fetched from either VRAM (if present) or DRAM.


Sound is provided by VIDC20. On Mk1 and Mk2 motherboards, 8-bit sound output is provided, similar to previous machines. 16-bit sound can be added via an add-on, which provides a 16-bit DAC. On Mk3 motherboards the 16-bit DAC is provided as standard and the 8-bit output is not connected. Mk3 motherboards also have a connector for mixing in CD audio.


A single IDE channel is provided on the motherboard, allowing two devices to be connected. Only PIO Mode 0 is supported.

A single floppy connector is provided. Mk1 motherboards only allow a single drive to be connected. Later motherboards allow two drives.


Two podule slots are provided as standard. This can be expanded to a maximum of eight slots, given the appropriate backplane. The podule slots support the newer DEBI standard, which allows for 32-bit transfers and a 16 MB address space per podule. Additionally, DMA is available to the first two podules in the system.

A dedicated network card slot is also provided.


RiscPC uses a PS/2 keyboard and a quadrature mouse. A serial port and a parallel port are provided.


The RiscPC case is modular, made of a base containing the motherboard, and one or more "slices". Each slice provides space for two podules, one 3.5" drive and one 5.25" drive. Officially up to four slices can be present, however larger machines have been unofficially assembled.


  • CPU: ARM610, ARM710 or StrongARM
  • RAM: Expandable to 256 MB
  • Hard drive: 3.5" IDE
  • CD-ROM: Optional, IDE
  • Removable storage: 1.6 MB floppy drive
  • Expansion: Two podule slots, expandable to eight
  • Network: RiscPC network socket provided
  • Printer port: Bidirectional
  • Serial port: Yes
  • Video output: VGA


First generation

The first generation was released in 1994. These machines all shipped with the 30 MHz ARM610 CPU and RISC OS 3.5. The first generation machines did not include 16-bit sound hardware.

  • ACB15 - RiscPC 600 2MB, HD210
  • ACB25 - RiscPC 600 5MB (4 MB RAM + 1 MB VRAM) HD210
  • ACB28 - RiscPC 600 5MB HD420 CD
  • ACB45 - RiscPC 600 9MB (8 MB RAM + 1 MB VRAM) HD420
  • ACB48 - RiscPC 600 9MB HD420 CD

Second generation

The second generation was released in 1995. These machines shipped with either the 33 MHz ARM610 or 40 MHz ARM710 CPU and RISC OS 3.6. These machines use the Mk3 motherboard which includes 16-bit sound hardware.

  • ACB60 - RiscPC 600 4MB HD425
  • ACB61 - RiscPC 600 4MB HD425 CD
  • ACB64 - RiscPC 600 4MB HD540
  • ACB65 - RiscPC 600 4MB HD540 CD
  • ACB67 - RiscPC 600 4MB HD425 Early Years
  • ACB68 - RiscPC 600 4MB HD425 Learning Curve
  • ACB69 - RiscPC 600 4MB HD425 Home Office
  • ACB70 - RiscPC 700 5MB HD425
  • ACB71 - RiscPC 700 5MB HD425 CD
  • ACB75 - RiscPC 700 10MB (8 MB RAM + 2 MB VRAM) HD850
  • ACB75A - RiscPC 700 10MB HD1GB
  • ACB75B - RiscPC 700 10MB HD1GB
  • ACB76 - RiscPC 700 10MB HD850 CD
  • ACB76A - RiscPC 700 10MB CD-ROM
  • ACB76B - RiscPC 700 10MB HD1GB 4xCD
  • ACB77 - RiscPC 700 5MB HD540
  • ACB77A - RiscPC 700 5MB HD540 CD
  • ACB77B - RiscPC 700 5MB HD540
  • ACB78B - RiscPC 700 5MB HD540 4xCD

StrongARM RiscPC

The StrongARM RiscPC was released in late 1996. All variants shipped with the 202 MHz StrongARM CPU and RISC OS 3.7.

  • SRP05 - 200MHz StrongARM RiscPC 10MB HD1GB
  • SRP06 - 200MHz StrongARM RiscPC 10MB HD1GB 8xCD
  • SRP10 - 200MHz StrongARM RiscPC 4MB HD1.2GB
  • SRP11 - 200MHz StrongARM RiscPC 4MB HD1.2GB 8xCD
  • SRP15 - 200MHz StrongARM RiscPC 10MB HD1.2GB
  • SRP16 - 200MHz StrongARM RiscPC 10MB HD1.2GB 8xCD

233 MHz StrongARM RiscPC

The 233 MHz StrongARM RiscPC was released in 1997. All variants shipped with the 233 MHz StrongARM CPU and RISC OS 3.7.

  • SRP20 - 233MHz StrongARM RiscPC 4MB HD1.2GB
  • SRP20a - 233MHz StrongARM RiscPC 4MB HD1.7GB
  • SRP21 - 233MHz StrongARM RiscPC 4MB HD1.2GB 8xCD
  • SRP41 - J233 JAVA RiscPC

Castle RiscPC

Following the closure of Acorn's workstation division, Castle Technology acquired the rights to continue distributing RiscPCs.[4] It would also go on to produce upgraded models based on the revision T StrongARM which were released in 1999.[5][6]

  • RISC PC233T - RISC OS 3.7, 8MB, HD2GB
  • RISCPC233T CD - RISC OS 4, 16MB, 2MB VRAM, HD4GB, 40xCD
  • WEB WIZARD - RISC OS 4, ANT, JAVA, 34MB, 2MB VRAM, HD8GB, dvdCD, 56k modem