RISC OS Software


Here are several applications I have written for RISC OS, the operating system used by Acorn's 32 bit ARM-based computers.

If you wish to run them on a PC running Windows, I suggest you try the emulator RPCemu or Red Squirrel.


TypeInfo is an unofficial database of RISC OS filetypes. It has been compiled over many years to present informal information about the applications that use various file types. The most prominent feature is to operate in the background, only appearing when an unrecognised file is double-clicked and presenting any information known about that type to allow the user to track down the relevant application.

Download 562 Kb ArcFS2 Archive

TypeInfo displaying information about a filetype.


TypeFind analyses the structure of files and makes an educated guess at the appropriate filetype from over 200 known types. With batch processing and automatic file-typing, this is ideal for identifying the file type when it has been lost. For example when files are transferred from a PC to an Acorn without DOS extensions to the file name.

Download 173 Kb Zip Archive

TypeFind accurately identifying the type of its !RunImage file.


MapIt is a little program to correctly RISC OS file types that have DOS extensions as might commonly be brought to a RISC OS computer on a DOS disk. For example, a file with the extension '.gif' would have it's RISC OS file type appropriately set to &695 and the '.gif' characters removed from the end of the file name. MapIt can operate very quickly on batches of files and knows over 200 DOS extensions.

Download 36 Kb Zip Archive

MapIt removing a .gif DOS extension.


An emulator of the Manchester Small Scale Experimental Machine, the first working stored program computer. Originally written to allow RISC OS users to enter a competition to commemorate the 50th anniversary of this historic event, the emulator simply emulates the running of programs and not the interface to the actual computer. Comes with an assembler to convert modern-style assembly language into the binary patterns of the original machine. Anyone interested in this should really take a look at the more extensive emulator of the Baby that I wrote in Java.

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Babe having emulated the first stored program ever executed.

6502 emulator (unfinished)

This is an unfinished emulator for the 6502 microprocessor written in ARM assembly. It was developed in Spring/Summer 1998 during discussions with Alain Brobecker and Richard Talbot-Watkins and was intended to form the basis of a Nintendo Entertainment System emulator for RISC OS. It is written in 26-bit PC mode ARM assembly so would need some work to be used on any modern (32-bit PC) ARM processor.

There are still some bugs in there (particularly in relation to the condition flag emulation) and there are more accurate source codes to similar projects available but it is still useful in that it is well-structured and commented and with the accompanying document should provide a lot of information about the techniques used in writing an interpreting CPU emulator in assembly language.

Download 23 Kb Zip Archive
Download Thoughts on an assembly-coded emulator

ArmSI 4 (unfinished)

Sometime back in 1998 Mohsen Alshayef (author of StrongBS) and I were looking at writing a new version of the RISC OS machine identifier and benchmarker, ArmSI. Version 3 had been stagnant for sometime and Mohsen wanted to start from scratch and had plenty of ideas for ways to probe and test Acorn machines.

Regrettably the project never got off the ground, he was the driving force behind the project and didn't have the time to work on it and I went off to university and stopped developing software for RISC OS. However, a fair amount of code was written by Mohsen to perform various benchmarking tests and for that reason I'm releasing the work done in case it's of use to anyone interested in a similar project in the future.

Download 206 Kb Zip Archive