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[ WROCC Home » Meetings » Past Meetings » September 2014 ]

RiscPC to Raspberry Pi

September 2014 meeting – report by Peter Richmond

September’s meeting was to be a combined presentation by Peter Richmond and Terry Marsh, looking at the history of the RiscPC and some ‘easter eggs’ which can be found on the Raspberry Pi. In the event, Peter’s trip down memory lane filled the evening, leaving Terry to investigate the Pi at a later date (probably the October meeting).

Peter brought along two of his RiscPCs: one running RISC OS 6, and one running RISC OS 3.7 with the ART orange and black ‘splash’ screen.

An Acorn history

He suggested that we start by looking at what went before the RiscPC to see how the decision was made to implement the features it was given, then look at competing machines and developments that have kept the RiscPC viable as a usable desktop computer.

Originally the Acorn range of computers were 8-bit, but after a few years some 16-bit processors were becoming available. However, when these were researched fully by Acorn, they found that in many instances the 16-bit computers were slower that the finely tuned 6502 running in the BBC Micro. Acorn did develop 16-bit co-processors running in conjunction with their existing 8-bit computers, but eventually the decision was made to design their own processor – which we all know was the ARM chip.

The first ARM processors were made in 1984 but needed supporting chips before a new computer system could be built. This happened when the ARM2-based Archimedes 300-series desktop computers were built running the Arthur OS, which was quite different to what we are used to today. It did, however, start out with the three button mouse which has always been an integral part of RISC OS.

Construction of these computers was by thick steel in a two box system which also had very advanced graphics for the time giving 256 colours. 1988 saw the introduction of a 25MHz ARM3 processor. 1990 saw the introduction of the 400-series computer with RISC OS 2, which is the OS on which pretty much all RISC OS machines are based upon.

It’s a testament to the designers of the OS that the basics have remained pretty unchanged: Draw, Paint and ChangeFSI have only had minor updates, mainly to do with the number of colours that they can display. [It could also be seen as an indication of how little RISC OS has progressed in the past 25 years – Ed] Peter remembered that he started doing DTP with a 9-pin dot-matrix printer, using Acorn DTP. Although the program was quite poor, it had a massive speed advantage over PCs and Macs of this period.

1993 saw the introduction of the A5000, which had an integral ARM3 processor. Other things that were standard included an IDE disc interface and memory expansion via a plug-in board. The maximum hard drive size, memory expansion and number of displayed colours had, however, got ‘stuck’ due to limitations in the hardware and RISC OS.

The birth of the RiscPC

Competing systems had CD-ROM drives, and higher screen resolutions with more display colours – plus there was always the question of PC compatibility. The guys at Acorn took all these problems on board, looked at what they needed to change, and considered at how they could achieve it.

Peter divided the ideals into two lists: ‘standard’ changes and more ‘esoteric’ ones. The standard ones included:

  • An IDE interface plus CD-ROM drives (in the case),
  • Space to hold a second hard disc in the case,
  • An easy-fit network card (not Econet),
  • Greater RAM capacity (SIMMs),
  • A faster processor, and
  • Greater graphics capability (16-bit graphics).

The more esoteric ideals included:

  • Video RAM and 24-bit graphics,
  • A ‘plug-in’ main processor,
  • DMA on two podule slots,
  • A ‘plug-in’ x86 processor card, and
  • A plastic ‘cake-slice’ case design.

As a result, in 1994 the RiscPC 600 came out with a 30MHz ARM610 processor running RISC OS 3.5. It still had 8-bit sound, and its hard disc size was limited to 500MB.

By 1995, the RiscPC 700 had 16-bit sound, and ARM710 processor running at 40MHz and RISC OS 3.6 including support for hard discs of 4GB or 16GB. In 1995 486 cards were released for the second processor slot to be able to run Windows 3.1 and later Windows ’95.

This processor was keeping up with the PCs of the time, but 1996 was the big year for the RiscPC. This was when the 200MHz StrongARM processor came out, along with RISC OS 3.7 which allowed even larger hard disc sizes. The SA RiscPC had now truly become a PC-basher. Acorn themselves started to promote SA RiscPCs as desktop publishing systems, especially since ArtWorks and many 24-bit graphics programs were available.

Some people expanded their RiscPCs to many ‘slices’. Two was a popular option, with power users having three ‘slices’ to store various devices ‘in the box’.

Putting it to use

Peter then switched over from his RISC OS 6 RiscPC to his RISC OS 3.7 machine with a 486 second-processor running Windows ’95, and took us back in time to the delights of Windows and the joys of the Start button. We then had a look at Windows 3.1 ‘style’ of word processor, which looked like the ‘dark ages’ as far as design is concerned – particularly bearing in mind that Impression came out in 1992!

Peter then mentioned that DMA on the first two podule slots was useful for moving lots of data around. One of the programs that made good use of this was VideoDesk, which could record in SVHS quality to the hard drive whilst also allowing titling and various transitions. The software used a ‘busy’ single width card with hardware encoding and decoding, which could all be handled by a SA RiscPC.

Unfortunately Peter had problems displaying this, but mentioned that without DMA such a system would have been a non-starter. Peter did mention that one of the things that he liked about this VideoDesk is that initially the program to do most of the basic video options came on one floppy disc. PCs always had a fairly full CD-ROM!

In 1998, Phoebe was going to be introduced to replace the RiscPC and was to have many new features including

  • A PCI bus to accept standard PC expansion cards,
  • A 15-way D MIDI and ‘games’ port, and
  • Standard network cards, and so on.

After the RiscPC

As we all know, it was never to be and in 1999 Castle acquired the rights to make the RiscPC and A7000. A consortium of dealers bought the OS and released RISC OS 4, which contains a number of improvements. In 2000 the Microdigital Omega was announced as a potential upgrade from a RiscPC but, as we now know, it never came to fruition.

Also in 2000, Castle introduced the Kinetic RiscPC which linked very fast memory directly to the processor to give a noticeable performance boost. 2001 saw the release of the Viewfinder graphics card which allowed higher resolution screens and faster refresh rates in many colours, which kept many of the DTP and graphics users happy for quite a while.

2002 saw Castle announce the Iyonix with RISC OS 5: although this was a faster computer, it only had podule compatibility. Of course not every program worked with RISC OS 5, which still left quite a few people using their RiscPCs. The year also saw Simtec and Castle bring out USB 1.1 cards, which allowed the use of thumb drives for storage of data up to 2GB when fitted to a RiscPC – greatly helping the transfer of data.

2003 was the last year when RiscPCs were produced by Castle, and the year that the RISC OS ‘Select’ scheme came out for users of RISC OS 4, incrementally helping the usability of the RiscPC. Incidentally, 2003 would make the ‘newest’ RiscPCs at least eleven years old today!

Universal expansion

Possibly the card that extended the life of the RiscPC the most was introduced in 2004, and was the Unipod. This gave several functions in one card: 100Mbit networking, USB 1.1, enhanced EIDE and a User Port.

2007 saw the general release of RISC OS 6, which could be soft-loaded over RISC OS 4.39 and gave many improvements to the OS – including numerous keyboard shortcuts and enhancements to Draw, ChangeFSI and Paint. This update was later released so as to be available as an upgrade for people who had never got past RISC OS 4. A lot of work was done to ‘tidy up’ the OS coding, which could also give speed improvements.

In 2009, the VPod was introduced to enhance the graphics capability of the RiscPC for those without Viewfinders, but only in conjunction with RISC OS 6. This card had 64,000 colour capability by dint of having 32MB of Video RAM, which speeded up multi-colour high resolution screens by quite a bit and again kept the DTP and graphics fraternity happy with their RiscPCs.

Peter then brought up the last slide in his presentation, which read: “RiscPC – 20 years of innovative British Computing”. As an end-note, Peter observed that the computer which may have signalled the end of the useful life of the RiscPC is the Raspberry Pi – which, as someone noted, is a really good graphics chip with a 700MHz processor attached.

In reality a Pi, in conjunction with Aemulor, can now perform tasks where a RiscPC is showing its age. The Pi comes with 512MB RAM, which is just not achievable with a RiscPC, and the processor is 700MHz whereas the fastest reliable processor on a RiscPC is about 300MHz. Of course there are still hardware podules that are not replicated on a Pi, Beagleboard or Pandaboard, and for that reason RPCs will still be used, but its still a remarkable feat that a twenty-year-old computer can have a number of uses and still communicate sensibly with modern devices.

I think that we can be proud of the British heritage of the Acorn team and of the RiscPC.

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