A 26 bit build of RISC OS


This is a Rom Image and hard disc image of RISC OS, built from the open ROOL sources, but compiled up in 26bit compatible mode.

It mostly uses code from approx 2000-2002, compiled up with a set of contempory tools.

It should be compatible with Acorn RiscPCs, A7000s, A7000+, and the emulator RPCEmu.

Latest download

Version 4.00 release B1 - 8/1/2024

Installing on RPCEmu

Download and install/compile RPCEmu as usual.

Download the 'ROM Image', unzip and place in the the roms/ directory.

Download the 'Hard Disc in Emulator HostFS format', unzip and place contents of 'HardDisc4' in the root of the hostfs/ directory.

Run rpcemu-interpreter (recompiler will not function yet), and RISC OS should run, but without booting off the Harddisc.

For best compatibility, edit your RPCEmu config, Settings->Configure, and change the 'Hardware' to 'RiscPC - StrongARM' and click OK, this will reboot RPCEmu.

Enter the command line (F12), and type the following.

*configure filesystem hostfs
*configure boot

Reboot RPCEmu, File->Reset, and it should execute the Boot sequence.

Installing on real machine

Unknown if this softload will load over the top of RISC OS 4.00 ROMs or higher

Download 'ROM Image' and 'Hard Disc in zip Format' and copy them to your hardware. Move asside your existing !Boot, Apps, and other folders, from the root of your machine.

Unzip the contents of 'Hard Disc in zip format' HardDisc4 folder and place in the root of your harddisc.

Unzip the contents of 'ROM Image' and place the file in !Boot.Softload. Rename the rom image file to 'Ursula'

Reboot the machine, it should softload the new OS.

Known Issues:

  • Untested on real hardware
  • Not sure it will softload on machines with version 4.00 or higher already installed...
  • On RPCEmu, does not work in recompiler (bug in RPCEmu being investigated)
  • On RPCEmu, works better in StrongARM mode (likely another RPCEmu bug)
  • May be missing modules and harddisc apps people would expect to be there
    • ShareFS missing from ROM
    • Host and GetHost network commands missing from disc
  • Only very lightly tested