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This is a collaboratively driven RISC OS FAQ, designed to replace the dated comp.sys.acorn.* FAQ. In this format it can be easily kept up to date by multiple contributors.

Please read the FAQ guidelines before editing this page.



What is RISC OS?

There are many summary and introduction pages to RISC OS around, but Wikipedia gives one of the best overviews.

What RISC OS versions are there?

Peter Howkins provides a database of RISC OS versions, components and modules which lists major versions. However, the main versions you will see in use with current machines are:

3.7x variants exist, especially for ARM7500-based machines, as do point versions of other versions - in particular, RISC OS 5.13 is the latest version for the IYONIX pc, and Adjust is also known as RISC OS 4.39.

All versions for the RiscPC apart from Select, come in a two chip ROM package. RISC OS Select is softload. For the IYONIX pc and some of the other machines, RISC OS exists on flash ROM.

I've got a RiscPC/A7000, what OS upgrades can I buy?

RISCOS Ltd sell versions of RISC OS for RiscPCs and A7000.

Currently they sell RISC OS 4.02, RISC OS 4.39 (Adjust), RISC OS Select (a subscription scheme) and RISC OS 6. Both Select and RISC OS 6 are softloaded, so require at least version 4.0x to be installed already on the machine. Softloads are also available to upgrade 3.x to 4.02 and 4.02 to 4.39. OS ROM chips also appear on eBay from time to time.

RISC OS Hardware

What RISC OS hardware is available for purchase?

New Hardware

  • The Raspberry Pi 1 & 2: a widely available RISC OS capable computer for $35 or less.
  • The Beagleboard
  • The Pandaboard
  • The ArmMini series from R-Comp
  • The PandaRO from CJE Micro's
  • The ARMX6 from R-Comp
  • The RapidO from CJE Micro's
  • The Titanium motherboard which is a bespoke design for RISC OS from Elesar

Second hand

The following machines are generally found on eBay, or the comp.sys.acorn.hardware newsgroup

  • IYONIX pc from Castle Technology
  • A9home from Advantage Six
  • RiscPC
    • 600/700 - manufactured 1994-96. Usually have not been upgraded beyond original purchase specification
    • StrongARM - manufactured 1997. Available in 202MHz or 233MHz, usually with RISC OS 3.7 or 4. Occasionally with Select/Adjust. Often come with IDE or Ethernet upgrades.
    • Kinetic - manufactured by Castle Technology. StrongARM overclocked up to 300MHz, and coupled with DDR RAM for faster memory access.
  • A7000 - Usually RISC OS 3.6 or 3.7. 32MHz or 40MHz processor, 4MB base RAM
  • A7000+ - Usually RISC OS 3.71, occasionally 4. 56MHz processor with floating point, 8MB base RAM. A much nicer machine.

Other more unusual machines worth considering

  • RiscStation - These are basically a more advanced A7000+. They use the same processor clocked at 56MHz but have faster bus and memory and ISA support. RISC OS 4.03 and above.
  • MicroDigital Mico - This is similar to the RiscStation but also has Microdigital's Microbus interface. RISC OS 4.03 and above.
  • MicroDigital Omega - This is based around the same StrongARM as many RiscPCs but has the processor clocked at 300MHz and much faster bus, memory and also PCI support. RISC OS 4.03 and above.

What emulation solutions exist?

What memory does my RISC OS/Acorn machine take?

  • RiscPC takes Fast Paged Mode (FPM) SIMMs - fitting of EDO SIMMs isn't supported but may work
  • A7000 takes FPM SIMMs
  • A7000+/NC/RiscStation/Mico/Bush STB take EDO SIMMs, though FPM SIMMs may work
  • Kinetic takes laptop-style SODIMMs
  • Omega takes SDRAM DIMMs
  • IYONIX pc takes DDR RAM
  • A9home uses a proprietary combined CPU and SDRAM module - no upgrades are currently available

References: [1]

What is the maximum size hard drive that may be fitted to my machine?

These are the maximum partition sizes you may create, which are a combination of limits imposed by hardware, FileCore, FileSwitch and filing systems (ADFS, SCSIFS, etc). Some filing systems (notably ADFS) don't permit more than one partition, while some allow 4 or 8.

These are the best case that apply to the motherboard interface unless stated:

  • IDE drives[2]:
    • RISC OS <=3.5: 512MB, formatting to 499MB recommended for efficiency.
    • RISC OS 3.60-3.70: 128GB, inefficient over a few GB. On motherboard interface *Configure ADFSBuffers 0 or install a patch to prevent machine hangs for drives >2GB
    • RISC OS 4/6 [3]: 256GB
    • IYONIX pc hardware (RISC OS 5): 256GB, only DMA on first 128GB
  • SCSI drives: OS limits are same as IDE above. Also see below.
  • USB drives:

DOS format limitations may be circumvented with FAT32FS or ROFS (both on Iyonix only, so far).

Third party interfaces may impose more stringent limits if they predate the OS you are running and don't have support for it. For running on RISC OS 4 or later it may be sufficient to format a drive on another interface and return it to your old machine, but this may not work or there may be data corruption on bigger drives (eg over 20GB).

Some more recent drives won't work on the Risc PC or A7000(+) IDE motherboard interface, but will work happily on a third-party interface. A symptom of this problem is the drive being recognised but the model name or capacity appearing corrupted in HForm. This is because the motherboard interface requires the drive to provide the /IOCS16 signal which has long been deprecated from the ATA standards. See this newsgroup thread for more information and other possible workarounds.

Configure won't detect my network card!

Create an obey file called "AutoSense" with something similar to the following in it:

Set InetSetup$Driver$NIC I-cubed EtherLAN600:eh0:EtherH:4.33:EtherH16

Save it into !Boot.Resources.Configure.!InetSetup and reboot. The fields are:

  • NIC: the podule slot the card is fitted in. Use Slot0, Slot3, etc if it's a podule slot rather than a network slot card
  • I-cubed EtherLAN600: The name of the podule as reported by *Podules
  • eh0: the network device. *ROMModules will show the card having a module on it called something like EtherM, EtherY, EtherX, etc. You should replace 'h' with the letter 'm', 'y', or 'x' in these cases. You're mostly likely to want to use device zero: EtherH and EtherM cards also provide devices eh1 and em1, mostly for PC cards, which can be configured separately.
  • EtherH: the name of the driver module in memory (usually the same name as that shown by *ROMModules)
  • 4.33: the lowest version of that driver module that's required. Try 0.00 if you don't know.
  • EtherH16: the filename of that module to load from System:Modules.Network. Sometimes the module will have a different filename on disc as it has in memory, but usually this will be the same as the name in memory.

You should now see your card in !Boot's network configuration.

RISC OS Software

Is there a list of "must have" RISC OS software?

riscos.info maintains a list of recommended software.

Is there a version of RealPlayer for RISC OS?

Not really. There is a player for very early RealAudio files (pre-1996) by Kira L Brown and Justin Fletcher, but these are seldom found today and it is unable to cope with streamed audio.

In 1995/6 Acorn and Warm Silence Software cooperated to port the then-current RealPlayer as part of the Network Computer project. Acorn are said to have loaned a RiscPC to Progressive Networks (now Real Inc) to allow them to compile the core routines without releasing them outside the company. However it is said that Progressive Networks asked for a five or six figure sum to allow release of this version, and so the project was canned.

Circa 2002 Real Inc performed a partial release of the RealPlayer source code through its HelixCommunity website. The source to Helix Player, a player frontend, is available for relatively unrestricted download. This does not contain source to the RealPlayer decoders. They, including ARM-optimised variants, are available at zero-cost but under a more restrictive licence arrangement. Essentially a prospective porter has to submit a proposal to Real that they intend to port the codecs. By agreeing to the Research and Development licence they gain access to the source. After examining the source they must then submit a plan stating the timescales by which they intend to port the code and what work needs to be done. Once the port is complete, Real's commercial distribution licence requires a royalty of US$0.25 per copy.

The misapprehension that performing a port requires many thousands in licence fees still circulates. However at present the barrier to porting is financially lower but requires a degree of commitment from the porter. To date no-one has publically stated such a commitment.

Does Unicode printing work in RISC OS 5?

Not currently, though this situation is being rectified. See the full situation.

Are there any Viruses?

Viruses are extremely uncommon on RISC OS due to the small user base. However, viruses have been written in the past.

RISC OS Forums and mailing lists

What mailing lists exist for RISC OS?

A9home. Advantage Six maintains a private mailing list to which users were subscribed, the joining details may, or may not, still be available at the time of purchase. There is an open "unofficial" list, unsupported by Advantage Six, at http://riscository.co.uk/mailman/listinfo/a9home-list_riscository.co.uk.

Virtual Acorn. A forum at http://www.virtualacorn.co.uk/forum/index.php is the official channel. For those that dislike forums there is an "unofficial" mailing list, which may not be supported by Virtual Acorn, at http://riscository.co.uk/mailman/listinfo/virtualacorn-list_riscository.co.uk

Misc. Iconbar maintains a list of RISC OS mailing lists.mailing list

Are there any usenet groups related to RISC OS?

Yes. For historical reasons they come under the 'Acorn' name. They are:

  • comp.sys.acorn.advocacy
  • comp.sys.acorn.announce (Moderated)
  • comp.sys.acorn.apps
  • comp.sys.acorn.extra-cpu (Quiet)
  • comp.sys.acorn.games (Quiet)
  • comp.sys.acorn.hardware
  • comp.sys.acorn.misc
  • comp.sys.acorn.networking (Quiet)
  • comp.sys.acorn.programmer
  • comp.sys.acorn.tech (Archive only)
  • maus.computer.archimedes (German language, quiet)

These groups can be accessed using your own usenet software, or via the Google Groups web interface.

I prefer online forums - are there any of those?

Online forums are not so popular amongst the RISC OS community. However, the least quiet ones can be found on the Iconbar.

IRC Channels

A List of the known ones can be found on this site at

RISC OS Publications

Which online and offline publications exist for RISC OS?



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