[Coco] SAMx4 - CPLD-based SAM replacement

[Ciaran Anscomb]

Ciaran Anscomb via Coco wrote:
> And there is a reason to do that - the banker board function intercepts
> $FF3x, which is usually shadowed PIA1, so it slightly reduces
> compatibility (possibly some CoCo CB ROMs would be affected?).

So to answer that: maybe not!  Bodging XRoar to report shadowed writes,
it seem like the CB ROM only accesses shadows of PIA0 at $FF1x - so
might be in the clear with that one.

..ciaran