Date   : Fri, 24 Oct 2008 08:29:06 +0100
From   : pete@... (Pete Turnbull)
Subject: A500 development ROMs

On 24/10/2008 01:54, Jules Richardson wrote:
> Jonathan Graham Harston wrote:

>> I'm not sure. I though Brazil was what the PC Springboard used, and
>> so communicated via the PCI bus with the PC. 
> 
> ISA, not PCI - at least the pair I have. I think the Springboard was long dead 
> as a product before PCI really came along.

Yes.  IIRC the last Springboard was sold in early 1897, about 4-5 years 
before PCI (released 1992).  I expect Jonathan just meant "PC expansion 
bus" and wrote "PCI" because that's what came to mind, being most common 
now.

> It would fit date-wise for the A500 to be Brazil-based, I think, but it's by 
> no means a certainty. I'm also guessing Acorn used Brazil as a catch-all for 
> 'ARM supervisor', so the Brazil flavour varies between products.

I don't know but I believe that makes sense.

>> in <http://mdfs.net/Mirror/Archive/Acorn/Spring.zip> suggest. The
>> A500 communicated through a Tube link with a BBC/Master.
> 
> Although I don't think they *had* to have a TUBE link present - the ones I've 
> seen have a pretty enormous keyboard to them. (Unless you're talking about the 
> A500 copro, not the A500 machine?? Never have figured out why Acorn used the 
> same system designation for two completely different boards!)

I'm quite sure they *didn't* have two different boards.  And they didn't 
necessarily need the Tube.

At first, the A500s were used as second processors connected to a Beeb, 
not to give a Beeb a second processor to play with, but to give the A500 
(a complete but at that stage dumb computer) I/O capability while its 
own I/O routines were written and tested.  Once this was completed, the 
A500s could be disconnected, and use their own video hardware and 
keyboards.  Actually it was done in stages, video first, then keyboard, 
then the rest.  I don't believe there was ever an "A500 Second 
Processor" board as such.  Why would there be?  The A500 was always 
intended purely and simply as development platform to bootstrap the 
Archimedes range, to develop the O/S and support software (eventually 
including some 3rd-party software).  There was already an ARM 
Development System second processor, and the A500 was the next step - a 
self-contained ARM-based computer.  All the A500s I ever saw in Acorn in 
1986/87 were complete machines, though even in spring/summer 1987, I saw 
one still attached to a Beeb.  I'm sure the reason you think there was 
an A500 copro is simply that early on, the A500 needed the Tube and a 
Beeb to do I/O/.

-- 
Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York