Date   : Mon, 03 Mar 2008 18:16:54 +0000
From   : pete@... (Pete Turnbull)
Subject: TUBE chip, accessing 'Parasite' side

On 03/03/2008 17:14, Johan Heuseveldt wrote:

> I refound the schematics for the internal CoPro 80186, but couldn't find
> anything else.

Try http://www.bbcdocs.com/ and follow the link for Hardware.  The 
diagrams for three coprocessors including the external 6502 are near the 
bottom of the page.

  With my own 6502 external 2ndProcessor, I've investigated a
> few things. It appears that the power connections to the TUBE chip are more
> advanced than I first assumed, which makes sense as this chip - besides the
> logical model for the TUBE software protocols - must also handle two
> independant power connections, and some safety precautions are apperently
> necessary!

I expect you're looking at the circuitry around LK1 and LK3.  It also 
has provision for power to be taken from the cheese wedge PSU or 
alternatively from the Tube.

> The '004' document for the TUBE doesn't say anything how fast the parasite
> side can/may be accessed. Even an pin description is without pin numbers.

No, sadly it only says how quickly the parasite needs to respond to keep 
up, ie the lower limit -- not what the upper limit is.  The Arm Eval or 
32016 circuits might give a clue; I've not looked.  You won't have a 
problem with a 68B09, though (I know because (a) it's been done and (b) 
that's about the same bus speed as the corresponding 2MHz 6502A or a 
4MHz Z80A).

-- 
Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York