[Coco] grey MPI 26-3024 - how to tell if upgraded

[RETRO Innovations]

On 2/1/2015 3:27 PM, Ivan Browning wrote:
> PRINT PEEK(&HFF90)
>
> If it returns 126 it is upgraded if 255 not upgraded
>
> On Sun, Feb 1, 2015 at 1:58 PM, Randall Kindig <randall.kindig at gmail.com>
> wrote:
>
>> I have a grey MPI (model # 26-3024) that I was told has been upgraded for
>> a CoCo 3.  As a CoCo newbie, I’m wondering how I can tell for sure that
>> it’s been upgraded?  Is there a PEEK or anything I can do software-wise to
>> verify?
>>
>> Thanks all!
>>
>> Randy
>>
>>
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>>
So, is there a link to a note that explains why the PAL changes were not 
backward compatible? As I understand it, the Coco3 MPI PAL allows 
addressing only ff7f, but the earlier MPIs would allow ghost locations.  
Why would disallowing the ghost make the unit not usable with Coco 1 and 
2 machines?

JIm


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