Date   : Thu, 11 Aug 2005 10:43:57 +0000
From   : Jules Richardson <julesrichardsonuk@...>
Subject: Re: 80186 co-pro

On Thu, 2005-08-11 at 02:19 +0100, Rob wrote:
> At 22:18 10/08/2005, Sprow wrote:
> 
> 
> > > >[snip- co pro based on WDC 14MHz 6502]
> >
> >Without wanting to paint myself into a corner or do Phil out of any work, I
> >was planning the following extensions to the ARM copro board proposed earlier
> >
> >  a) emulate the 6502 tube/65C102 turbo as required in software on the
> >     ARM. At 75MHz you should be able to at least achieve 10MHz, allowing
> 
> >  b) use a soft 6502 blatted into the spare space in the programmable logic
> >     emulating the Tube IC, I've already done some work on a VHDL core which
> >
> >That way you get two coprocessors for the price of one,
> >Sprow.
> 
> Hmm... any room in there for a Z80 as well? ;-)
> 
> Actually, both are sensible options; I guess it would be fast enough so 
> it's possible to write an emulator for any period processor - and after all 
> the emulator wouldn't have to worry about any i/o devices apart from the 
> tube interface, and that can just be a 'pass through' to the actual 
> interface, so the emulator is talking direct to the real beeb host...

Actually, you're probably onto something there. Presumably with a fast
enough CPU it should be possible to emulate any of the period beeb
coprocessors and for all intents and purposes it's indistinguishable
from the real thing...

Just have a rotary switch on the back (say) which selects which copro
you want prior to power-up (or fancy pushbuttons / LCD display, but I
quite fancy something that just lives in a cheese-wedge box)