Date   : Wed, 05 Mar 2008 15:32:16 +0000
From   : pete@... (Pete Turnbull)
Subject: TUBE chip, accessing 'Parasite' side - 16Mhz 65C02S

On 05/03/2008 14:39, Jules Richardson wrote:

> Some external 32016 256KB/1MB cheese-wedges for the BBC (the "small" 32016 
> board) are branded as "Cambridge Co-processor" whilst others are "32016 Second 
> Processor" (although, oddly, I think the PCB silkscreen only ever says "32016 
> second processor").

> I don't think the Master existed until late 1985 / early 1986, meaning that 
> the term "co-processor" existed in a BBC micro context at least a year before 
> the Master did.

Not quite.  AFAIR the original ones were sold as "32016 Second 
Processor" and the "Cambridge Co-processor" was later, and came about as 
part of the Master Scientific idea.

> In a Master context, wasn't there only ever an internal 65C102 co-processor, 
> and never an internal 6502 one? Similarly, weren't the boards designed for the 
> external TUBE interface only ever 6502 CPUs, not 65C102?

Correct.  At least for ones designed by Acorn, though if anyone were to 
nitpick, the external ones are 65C02 and have an extended instruction set.

>> There is a(n external) CoPro case - by CC I think, specificly designed to
>> do exactly that!
> 
> I had a Watford one (I think it went to Dave Moore), but I think that was more 
> about the ability to run the Master-series internal boards (primarily the 
> 80186) on a lowly model B.

There was an Acorn one as well, though never made or sold in any 
numbers.  It was indeed intended to allow Master-series internal boards 
to be sold for Beebs, at a time when Acorn (who had unbelievably long 
lead times) had run out of second processors and didn't want to commit 
to a large manufacturing run.  It came out at about the same time as 
Acorn were using two different replacements for the Tube ULA, and I 
remeber there was some problem over that because one of the replacements 
worked with second processors but not co-processors (or maybe t'other 
way round).

-- 

Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York