[BBC-Micro] TUBE chip, accessing 'Parasite' side - 16Mhz 65C02S

Johan Heuseveldt johan at waarland.demon.nl
Thu Mar 6 16:31:49 GMT 2008


On Thu 06 Mar, Andrew Benham wrote:
> David Warrington wrote:
> > I think ANYONE still using a beeb today should just "drop in a 65C02" or 
> > "65C02S" into their beeb to allow them to use BASIC4 and the "65Cxx" 
> > mnemonics in assembler, e.g. PHX, PHY, STZ, etc.  This is a no brainer
> > and a  5 minute exercise.
> Perhaps.  Except many years ago I wasted a lot of my time trying to
> debug code I'd written using the VIA to do some timer-driven stuff on
> the user port.  The VIA wasn't working like the manual said.
> Eventually I had somebody else test it on their Beeb, and it worked
> fine for them.  At this point I remembered I'd put a 65C02 in my Beeb -
> so I replaced it with the original NMOS processor and my code worked
> fine.
> I think the timing on the Beeb is "close the the edge", and the CMOS
> processor has slightly different timings.  I've never put a CMOS
> processor in a model B since then.
> [ Everything else on the Beeb worked just fine with the CMOS processor,

> it was just programming the VIA that didn't work.  Perhaps on another
> machine it would have been OK, or perhaps something else would have
> failed ...]

There's for certain an issue here. Sprow's web site has something on this
topic, including some alterations to perform!


Johan Heuseveldt <johan at waarland.demon.nl>
  aka  waarland

  The best place is a Riscy place
Genetics explains why you look like your father,
and if you don't, why you should.

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