Virtual Acorn – Fun with Virtualized RISC OS

(this is a guest post from Antoni Sawicki aka Tenox)

VirtualRPC-SA let’s you run virtual RISC OS on a Windows or Mac OS X host similarly to VMware, VirtualBox or Qemu. The company page features this picture:

acorn1… in reality you you probably don’t want to do that!

As of time of writing of this article there is a sale going on! You can buy VirtualRPC-SA for only about $100. My primary reason for getting it was porting aclock to RISC OS. In addition to the VM I also purchased the original compiler and developer tools (DDE). It allows to target the funky 26 bit CPU. Otherwise GCC is available for free.acorn-cVirtualRPC comes “pre-installed” with the RISC OS in a virtual ROM image. The OS at first glance is quite nice looking and seems fun in to explore and play around. You can browse the web and use a bunch of weird applications from alien world. You can find a lot of software apps here and here and here. However I personally could not use this for anything more serious.

riscos-webPorting of aclock to RISC OS was by far one of most difficult ones if not the most difficult. To display text on the screen you need to use system calls directly, for which you use a special function called _swi() or _swix(). There is no concept of sleep() so I had to improvise an empty loop. Fortunately there are screen codes that allow to position the cursor, clear screen etc.

void cls(void) {
     (void) _swix(OS_WriteI + 12, 0);

The result is far from pretty but it will do for v1:

aclock-riscosSome funnies, which actually weren’t that funny at the time:

A directory separator in RISC OS is “.” (yes a dot) for example: root.folder.subfolder.file. The C compiler expects .c as a file extension as it would on any normal OS. The problem is that naming file aclock.c would make a directory aclock with c file in it. Fortunately, or maybe not, extensions in RISC OS are prefixing, not postfixing a file. So you have c.aclock or o.aclock. Except, as previously explained c and o are directories. You can see c and o folders in the screenshot above. Are you confused yet?

Interestingly RISC OS does have concept of a command line interface and a terminal window. However try to figure out the commands!

  • dir – change directory aka “cd” on the planet Earth
  • cat – list directory aka “ls” or “dir” in your normal OS

riscos-cmdThere is more, so I encourage you to try yourself just for the fun!

19 thoughts on “Virtual Acorn – Fun with Virtualized RISC OS

    • This and Spectrums and Atari’s. It really is a strange place. Hard to imagine their home grown RISC CPU is so prevalent these days.

        • I know this is an old blog, but to anyone reading it… the sheer ignorance and stupidity rolled in to one sentence by this guy is amazing. The ARM processors were 32 bit from the very start. Try actually looking what the ’26 bit’ refers to.

      • Aaaggghhh! Some people are just clueless. This is so wrong, it’s painful to read. For anyone reading this: The UK had pretty much every computer under the sun, Atari were an also ran, CBM were popular, as were Amstrad, Tandy, Dragon, Oric, BBC/Acorn, TI99/4A, Sinclair ZX range to name few. Risc OS was released in 1987. Its roots go back to the early 80s and the Acorn BBC Micro. Back then many of the ‘standards’ in use today we’re not actually standard. MS Windows was a flimsy, single tasking veneer over single tasking MS DOS, itself a third party clone of CP/M licenced by MS. CP/M and GEM were still around and Apple’s OS used a one button mouse and had no command line at all. The team that started Acorn were as innovative as Gates or Jobs ever were. They went on to design an ultra low energy, super fast, full 32 bit risc processor from scratch, a new line of computers and a bespoke OS for it. The Acorn Archimedes, using the “Acorn Risc Machine” chip. Acorn split off ARM and changed the name accordingly.

        • Xenix 386 and Windows/386 show that Microsoft easily could have done a full 32bit product but IBM got involved and screwed it all up, see the FOOTBALL beta of OS/2 1.0 and the v86 hypervisor was already there.

          As for the ARM they didn’t sell those outside of the UK so they died in obscurity until the processor was freed by the death of the parent. I too had a Newton.

          As far as standards went, Taiwan set the standard. There was no Amiga or ST clone, Intel sold to anyone as did Microsoft. The rise of the IBM compatible was inevitable.

          It’s my blog, if you think I’m so clueless and ignorant fine, but there was no BBC users or machines in North America. With the rise of DooM it shattered the conception that even games had to be assembly, let alone couldn’t succeed using dos extenders or needing a 32bit OS. By the 1993 it was clear that Chicago and NT were going to dominate, BSD was the only thing that could have stood up, but then that lawsuit and Linus being the right guy in the right place with the right software set it all in motion. And even he needed persuasion to put Linux under the GPLv2.

          TripOS is still lost to us, land by the time riscos was opened the market had long since left it behind.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.