Acorn BBC Archimedes A310 with RISC OS 3

The Acorn Archimedes 300 series of computers was launched in June 1987 as the Archimedes A305 and A310 and at the time it was nothing short of revolutionary as they were the first RISC CPU powered desktop computers in the world.

The Acorn Archimedes A310

At the time, the processor was called the Acorn RISC Machine. In fact the processor was the ARM2, superseding the original ARM1 processor which could be found at the heart of a TUBE based second processor, the ARM Evaluation System for the BBC Micro series of computers.

The A310 was the higher specification version of the Archimedes 300 series of computers and was launched by Acorn in 1987. Originally, these machines shipped with the operating system 'Arthur' and later models featured an updated and renamed OS called RISC OS 2. The A310 came with a full 1MB of RAM whereas the A305 shipped with 512Kb of RAM and was upgradeable to 1MB.

The Archimedes range of machines was introduced as the next step in the BBC's Computer Literacy Project and was branded as being a BBC Microcomputer as is evidenced by the label on the keyboard.

The Archimedes A310 keyboard detailing the BBC Microcomputer System label

The potential for upgrade of the A300 series of machines was limited as it did not ship with a backplane (one could be added later) and any add on podule expansions that were manufactured could not be fitted until a backplane was added.

Over the years, third party hardware developers created hardware add ons that allowed owners of the A300 series of computers to keep up with advancements and features that were developed by Acorn as standard features in their new models such as the A400/1 series, A3000 and A5000 machines.

Expansions in this A310

This particular A310 did not have a backplane fitted but despite that was highly expanded when compared to a standard A310 featuring several products from IFEL who developed many expansion options for the Archimedes range of computers.

The A310 with no backplane fitted

Since I acquired the machine, I've been able to source a backplane allowing the Archimedes to be expanded to its full potential.

In order to provide support for the ARM3 processor and the 4MB RAM upgrade, the MEMC controller chip had to be replaced with the MEMC1a chip which provided a 10% increase in performance of memory access for the Archimedes.

RISC OS 3.10 in MODE 31 courtesy of a Retro-Kit Ultra VIDC Enhancer

Repair/Change History

  • When I received this A310 in October 2012, it was in its original packaging and in reasonable condition although it has discoloured over time. I stripped the machine down to effect several minor repairs and changes.
  • The original ARM3 processor upgrade had become dislodged during transit and was re-seated. After successful testing, the ARM3 board was replaced with a taller IFEL ARM3 board freeing up the A310's ARM3 processor to be fitted into an A3000.
  • The Duracell AA batteries had leaked causing corrosion on one of the battery terminals which required cleaning up and the connecting wire required de-soldering, trimming and re-soldering before a set of new batteries were fitted.
    A leaky AA battery caused a large amount of corrosion and build up on the negative terminal
  • An Ultra VIDC Enhancer has been fitted to the A310 providing maximum compatibility with the VGA and SVGA monitor types.
    An Ultra VIDC Enhancer fitted to my Archimedes A310 
  • Some excess solder was shorting out the left and right channels on the Auxiliary Audio connector which was removed.
  • The mouse and keyboard were stripped and cleaned thoroughly.
  • In December 2012, the Field Change Order E011 was carried out to reduce the signal noise on the video output.
  • Also in December 2012, a Computerware 4-way backplane was fitted to the internal expansion socket.
  • Fitting the backplane allowed the addition of a Morley User/MIDI/Analogue interface card and an ICS/Baildon Electronics IDE/I2C interface
  • I downgraded RISC OS to RISC OS 2 in order to test the AutoVIDC software controlling an Ultra VIDC Enhancer on RISC OS 2 and have subsequently re-fitted RISC OS 3.11.

Battery replacement schedule

2 Duracell AA alkaline batteries were fitted in October 2013.

The next battery change is due in October 2014.

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A310 maintenance

Other maintenance resources

JASSP Forums

The JASSP project run by Jon Abbott is an attempt to acquire the rights to all of the Acorn Archimedes games back catalogue and archive them for the future.

Archiving the games is just half of the battle. Jon has written ADFFS which allows those archived images to be loaded and played on any ARM based machine running RISC OS which involves patching these games to run on later hardware using a JIT/VM style environment within ADFFS to allow the games to be patched to run safely on the latest hardware.

RISC OS links

RISC OS is the operating system that runs on all Archimedes and RISC PC's from Arthur in the beginning, to RISC OS 2 and onwards to RISC OS 4, 5 and 6 today.