Apple ][ boards -- what have I found? - test-drb@ccmp.vtda.org

28 Jul 2001

On Jul 27, 23:15, Tony Duell wrote:
...
  > On Jul 26, 18:38, Tony Duell wrote: 
...
  > > There seems to be a 6522 (on the BBC side)
with the ports connected to
...
  > > the ports of the 8255. That seems to be on
the Z80 bus.
 >
 > I've not looked at one for a while, but that makes more sense. 
Presumably
...
   the 6522 is
mapped into the Beeb's 1MHz bus space. 
 Don't you mean _Tube_ address space ? :-) 
Er, yes, that was a typo, induced by trying to type 15 minutes of email in
a 5-minute slot :-)

In fact, part of the reason the Torch board causes Beebs to misbehave if
Torch's own code doesn't grab it and hide it, is that the 6522 is seen by
Acorn's Tube code (in the DNFS ROM) and Acorn's code will try to initialise
it (and gets it wrong, of course).

-- 
Pete						Peter Turnbull
						Network Manager
						University of York