[Coco] question about MPI and Orch-90

[John Donaldson]

One of the biggest mods is strapping the Interrupt line across all 
slots. The only reason you want to do this is if your ONLY going to
run OS9 LII or NitrOS9. I don't remember which pins are strapped. Back 
in the COCO3 days we used wire-wrap wire to do the strapping. IIRC this 
mod allowed all slots to have this particular IRQ active all the time.

John Donaldson


On 5/7/2013 10:38 AM, Darren A wrote:
> On Tue, May 7, 2013 at 9:14 AM, Rogelio Perea wrote:
>> On Tue, May 7 2013 at 11:02 AM, Todd Wallace wrote:
>>
>> Ok I swapped out the chips.  Both say TANDY on them. And unfortunately I'm
>>> getting the same result with this alternate chip.  PEEK (&HFF90) still
>>> reports 255.  Perhaps the newer chip was just an newer version of the
>>> coco1/coco2 one.  Rogelio, I heard that the unmodded version on a coco3 has
>>> memory conflicts that can result in crashes, data corrupt, etc. I want to
>>> get this working properly for coco3 and i have no equipment for coco1/coco2
>>> anyways
>>>
>> I guess I've been living on the edge here... for years I have used both the
>> 26-3024 (big) and 26-3124 (smaller) MPIs on my CoC 3 with no upgrade, not a
>> single time I have ran across a problem. And yet, a little voice kept on
>> yelling at me that I anything happened to my data it was going to be my
>> fault :-)
>>
>> Been meaning to upgrade the 3124 MPI for a long while now, just to quiet
>> that little voice.
>>
> I've been using a 3124 MPI without the mod for several years and never
> had a problem.  When I recently tried running GoldRunner 2000 the
> system would freeze while loading.  It took me awhile but I finally
> figured out it was the MPI.  Substituting a 3024 MPI with the PAL mod
> fixed it.
>
> Darren
>
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