Date   : Sat, 06 Aug 2005 19:53:30 +0000
From   : Jules Richardson <julesrichardsonuk@...>
Subject: Re: 80186 co-pro

On Sat, 2005-08-06 at 20:20 +0100, Phil Blundell wrote:
> Thanks.  I'll look around for it.
> 
> I also found a couple of partially-depopulated 80286 external
> coprocessor boards.  

Bloody hell, those are rarer than hen's teeth. No ROMs whatsoever on
them? The Master 512 copro ROMs *should* work though; that's what my
board has. I've got ROM dumps of what's in my machine somewhere if
needed.

These boards were only used in the ABC3xx machines far as I know -
someone correct me if I'm wrong. 

> Does anybody have a circuit diagram of these, or a
> photo of an assembled board that I could use to figure out what goes in
> the empty sockets? 

Photo of assembled board I can do (not today, but probably tomorrow;
means digging my ABC310 out of the cupboard). Circuit diagram I got
halfway through drawing a while ago but haven't finished it yet...

> 1 off 40-pin DIP, on the north side between the Tube ULA and the EPROMs.
> I have no idea what this one is.

I think that's probably for a x87 copro - there's nothing in that socket
on my machine's board. 

Having said that, my board doesn't work yet (hence the reason I was
drawing out schematics!) so maybe that socket's for something vital ;)

At some point I'll be able to get hold of the service manual for these
boards (well reminded - need to chase that one up! :)

FWIW, much of the development work for the Master 512 was done using
those boards within Acorn as they were faster and had more memory.

Don't chuck them in case I need any bits to get mine going ;)

cheers

Jules