Date   : Fri, 24 Oct 2008 11:01:46 +0100
From   : michael.firth@... (michael.firth@...)
Subject: A500 development ROMs

> -----Original Message-----
> From: 
> bbc-micro-bounces+michael.firth=bt.com@... 
> [mailto:bbc-micro-bounces+michael.firth=bt.com@...
.uk] On Behalf Of Adam Sampson
> Sent: 24 October 2008 10:47
> To: bbc-micro@...
> Subject: Re: [BBC-Micro] A500 development ROMs
> 
> Pete Turnbull <pete@...> writes:
> 
> > 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/.
> 
> There are some pictures of an "A500 second processor" board here that
> looks distinctly different from a regular A500 motherboard:
> 
>   http://acorn.chriswhy.co.uk/8bit_Upgrades/Acorn_A5002ndProc.html
> 
Its also significantly different from the ARM Evaluation system, as pictured
here:

http://www.stumpie.com/armeval/index.php?ps=large&pname=dscf1272

> It appears to have video, audio and keyboard interfaces, but no disk
> controller...
> 

Given that Acorn presumably made their PCBs in house, it may be that the
Acorn A500 second processor was a half-way house system between the ARM Evaluation
System and the A500 standalone machine.

As Pete Turnbull has already said that the video circuitry was brought up 
first and then the keyboard, and it looks as though the A500 second processor 
has the video and keyboard circuitry, then a few of these boards were probably
produced to allow the firmware designers to get on with things while the
rest of the A500 PCB was laid out.

Michael