Acorn AKA16 MIDI card and StrongARM

The problem

A number of people have experienced problems with their AKA16 MIDI card upon upgrading to StrongARM. Specifically that the machine fails to boot up (at all, ie not getting as far as the desktop) when the AKA16 is present.

The best 'probable explanation' I've heard is that the AKA16's ROM is an old device (the MIDI 3.14 image is dated 9 Aug 1989) and in most cases is too slow to respond when the SA is booting up.

On this premise the solution is to unplug the AKA16's MIDI module ROM (using the *Unplug command, not physically), and to use a disc image of the MIDI module.

Unplugging the MIDI module

This is a little tricky, as you need to boot up the machine with the AKA16 installed so that you can *Unplug the MIDI module which is preventing you from booting up your machine :-)

There are a couple of approaches to get around this, though first a brief note on the workings of the *Unplug command :

The unplug status of all modules is held in CMOS (battery backed-up) RAM, with 8 bytes being allocated to podule-based modules (1 byte for each of 8 podule slots). This holds the unplugged state of the first 8 modules provided by ROMs on the card in each podule slot. The AKA16's ROM contains just 2 modules - MIDILog and MIDI.

It is important to note therefore that if you physically move an expansion card (which has unplugged modules) to another podule slot, the unplug status does not move with it. So you should ensure that the expansion card in question is in the slot you intend it to remain in, when you use the *UnPlug command.

Eg. if you have (say) a SCSI card in slot 0, and the AKA16 in slot 1, and the MIDI module (on the AKA16) has been unplugged. Then if you physically swap over the 2 cards, you will find that the MIDI module is no longer unplugged and that instead the second module on your SCSI card is now unplugged.

It's also worth noting that some of the <Key> - Power On combinations can clear the contents of the CMOS RAM, and hence clear all Unplugged status.

NB

In the following text I'll suggest that you remove / replace items of hardware.
ALWAYS ensure that the computer is turned OFF and disconnected from the mains supply beforehand.

Also, some devices (in particular the StrongARM card) are sensitive to and can easily be damaged by static charges present on your body. To protect against this - WEAR AN EARTHING STRAP !

Okay, so bearing that in mind, here's a few things you can try, to get the machine booted with the AKA16 in place :

  1. If you have a heavily populated machine, then you may find that it will start up okay with the AKA16 installed if you first temporarily remove other items of hardware.

    The first candidate for removal is a PC card (if you have one). This was sufficient in my case. However, you may find that you need to temporarily remove other things, like second hard discs, CD drives, expansion cards, etc. Though you may want to try (2) first, before going to such lengths.

    This sort of thing can be a little tedious, though with luck you'll find a configuration where the machine does boot okay. If so, then :

    • Press the F-12 key (to go to the command line),
    • Type the command *Unplug MIDI and press the <RETURN> key,
    • Shutdown the machine and switch it off.
    • Replace / reconnect all the bits you'd removed / disconnected,
    • Power up the machine - and pray.

  2. If you upgraded to SA from a RiscPC600/700 and you still have your old processor card, then you can try the following :

    • Ensure the machine is switched off,
    • Remove the SA card and replace it with the old 610/710 processor card,
    • Ensure the AKA16 is installed (in the podule slot you intend it to stay in),
    • Power up the machine. It should boot up normally.
    • Press the F-12 key (to go to the command line),
    • Type the command *Unplug MIDI and press <RETURN>,
    • Shutdown the machine and switch it off.
    • Remove the old processor card, replacing it with the SA card,
    • Power up the machine - and pray.

  3. If (1) was unsuccessful and (2) is not an option because you bought a RiscPC with a SA already installed, then either try and borrow a 610/710 card or make a phonecall to your nearest RISC OS friendly dealer to see if they can help.

    Failing that, there may still be hope ...

  4. I haven't tried this, but the theory seems okay. With the knowledge that the *Unplug command just sets bits in CMOS RAM, it should be possible to do this directly. Ie with the AKA16 removed, power up, and alter the appropriate CMOS bit. Then, power off, re-install the AKA16, power on, and hey presto the machine should boot with the MIDI module unplugged (providing you hit the right CMOS bit).

    This could turn out to be the simplest solution.

If one of the above was successful, the machine should now boot up successfully with the AKA16 present, though you will have no MIDI facilities - that comes with the next bit.

Using a disc image of the MIDI module

The easiest way to get this is to buy ESP's MIDI Support software (about £20).

An overview of ESP's MIDI Support explains the advantages of the system over the standard Acorn implementation of MIDI.