DOS code in CP/M? Revisited...

Liam Proven lproven at
Mon Jul 18 11:02:37 CDT 2016

On 17 July 2016 at 21:07, David Brownlee <abs at> wrote:
> On 17 July 2016 at 16:09, Liam Proven <lproven at> wrote:
>> In 1987 or so, the early Archimedes like the A305 and A310 came with
>> ST-506 controllers and 20-40MB Conner drives. The expensive
>> workstation-class models -- Dick mentions having an A500, but that was
>> a series, not a model.
> The A500 was the development prototype which pre-dated the A310
> (originally with pre-multiply ARM1 CPUs). Only a 100 or so made. I
> think they used pretty much the same Hitachi HD63463 as the (optional
> podule for the) A300 series which I think was DMA capable.
>> There was, later (1990), the A540:
>> This was the Unix R260, but shipping with RISC OS instead of RISC iX.
>> The A540 came with a snazzy SCSI HD:
> The A540/R260 was a completely different class of machine, with an
> ARM3 and the ability to take multiple memory (each with memory
> controller) cards.
>> ... but then it was the thick end of three thousand quid.
>> Back in '87, I suspect Dick had an A310 or something, with an ST-506
>> drive & Arthur (i.e. RISC OS 1 -- an ARM port of the BBC Micro's MOS
>> with a desktop written in BBC BASIC).
>> So I suspect no DMA... but I don't know.
> Think of it as an A310 with integrated disk controller, in a big metal
> box with a lot more soldered wires internally :-p
> Acorn kept them in internal service for white a while, including for
> development versions of RISC OS 3 with the multitasking filer.

Fascinating -- thanks for that!

OK, so the HD controller chipset was DMA capable, but did Arthur take
advantage of that fact?

I note that the first PDF datasheet I find for that chip is on Peter
Howkin's Martuan site. Pete is a friend of mine and maints RPCemu as
well as the open-source version of CDE, and is a major Acorn expert.

Said datasheet indicates that the HD63463 needs an accompanying
HD63450 DMA controller for DMA operation.

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