[Coco] Upgraded MPIs and Harware incompatability

[Mike Pepe]

I think the CoCo Max hi-res pack uses $FF90- that's one device that 
won't work properly with a modded MPI.

-Mike

Bruce W. Calkins wrote:
> The first suggestion of a PAL switcher to switch between CoCo 3 use and CoCo
> 1/2 use seems to be Marty Goodman in The Rainbow on January 1987 starting on
> page 98.  Here he does not say that the upgraded pack does not work on CoCo
> 1 &2s, but rather that some 3ed party hardware will not work with the
> upgraded MPI.  This is the earliest reference to a PAL switcher I have found
> so far.
> ----------------------------------------------------------------------
> In CoCo Consultations, The Rainbow, April 1987 a PAL switcher is addressed.
> This one is a bit vague as to the reason for the need to revert to the old
> PAL for use with the CoCo 1/2
> ----------------------------------------------------------------------------
> 
> I don't have time to research this much further now.  Suffice to say there
> was some confusion as to the needs for the upgrade in the first place, and
> it's affect on older equipment.
> 
> If Mark M. states the upgraded MPIs work fine with the CoCo 1 and 2, I can't
> argue it.
> 
> Bruce W.
> 
>