RPCEmu and RISC OS 5 on Mac OS X (Rev #6, changes)

History, RISC OS 5 and software compatibility

Early ARM processors had a combined 26-bit program counter and status register, rather than separate 32-bit program counter and status registers.

For a time processors had both 26-bit and 32-bit modes, with the former being phased out by ARM. In October 2002 RISC OS 5 was released using only the 32-bit mode, required because 26-bit mode processors were no longer available – the last being the StrongARM used in the RiscPC.

Most software written in BBC BASIC has no compatibility issues, and in many cases software written in C merely requires a recompilation of the source code, where available. However, some software is reliant on features specific to 26-bit mode and needs updating before it will work.

Recent developments have made RISC OS 5 available for the RiscPC (StrongARM/ARM610/ARM710) and A7000/A7000+ (ARM7500/ARM7500FE).

A ROM upgrade is available to install on real hardware. The following installation notes will allow you to run RISC OS 5 on an emulated RiscPC on a Mac running OS X.

These notes are based on testing

• The author of this installation sequence has been using RPCemu on Mac OS X for a number of years, under Lion / Mountain Lion and now Maverick (10.9), without issue.
• Although RPCemu is now at version 0.8.11 for Windows, the latest binary version for OS X appears to be 0.8.9, with a beta produced by Francis Devereux available via a link on the RPCemu website.

Installation

1. Download the zip archive of RPCEmu 0.8.9.
2. Open the zip archive, and copy the application file RPCemu to the Applications folder (either drag it over the Applications entry in the Finder sidebar, or onto the Applications folder on the dock).
3. As the zip file doesn’t contain the folder contents of the Windows zip, create a data folder, e.g., RPCEmu within your Documents folder, Documents/RPCEmu. Create a subfolder called hostfs within this folder, and another called roms.
4. Download an IOMD ROM image from RISC OS Open. All files, stable and beta, are available from the “ROM Images images page” page. The recommended ROM for the RiscPC is IOMD stable, other variants exist to cater for other CPUs, each with a stable (even numbered) and a beta (odd numbered) version – this text assumes a stable IOMD ROM.
5. Copy the file “riscos” from IOMD-Soft.5.20.zip\soft\!Boot\Choices\Boot\PreDesk\!!SoftLoad\riscos into the Documents/RPCEmu/roms directory. The other files aren’t needed and can be discarded.
6. Download the ROOL self extracting hard disc. As with the ROM image there are both stable and beta versions available. The recommended file is HardDisc4 (self-extracting) – stable 2013-06-16. Copy this file to Documents/RPCEmu/hostfs as “HardDisc4-util,ffc” take care to keep the ,ffc (comma ffc) ending which will be translated by RPCEmu to produce the metadata filetype for RISC OS.

Configuration

1. Open the Applications folder and click on the RPCEmu icon to launch it. A dialogue box will appear, asking you to choose a data directory – choose the RPCEmu folder created earlier.
2. Ignore the TaskManager error and click on the RPCEmu item in the menu bar and then Preferences…
3. Select the RiscPC StrongARM hardware option, select 128MB or more RAM, and 2MB VRAM.
4. After the restart the emulator will stop at a * prompt. This is because the system is not currently configured correctly to boot into the desktop – type desktop to start the desktop GUI. Cancel the error ‘Machine startup has not completed’.
5. Click HostFS, on the iconbar, to open the root directory.
6. Double-click on the HardDisc4-util to extract the HardDisc4 contents. Wait a while. Double-click the HardDisc4 directory that has been created to open it. Cancel the error ‘No Boot application has been run’, and hold shift down while dragging the !Boot to HostFS:$ (this moves it rather than copying).
7. Press f12 and issue the following commands
   Configure FileSystem hostfs
   Configure Boot
8. Press enter twice to return to the desktop then press ctrl-shift-f12 to shutdown.
9. Click the OS X Close button.
10. Click on the RPCemu icon in the Applications folder to re-launch RPCEmu.
11. When RPCemu is launched, it should now boot to the desktop. All further configuration of RISC OS is personal preference. Access the configuration section of RISC OS by a single click of the Menu (middle) mouse button over the cog icon on the far right of the iconbar.