[Coco] Upgrade MPI?

K. Pruitt pruittk at roadrunner.com
Wed May 6 19:28:34 EDT 2015

----- Original Message ----- 
From: "K. Pruitt"
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Wednesday, May 06, 2015 3:44 PM
Subject: Re: [Coco] Upgrade MPI?

> ----- Original Message ----- 
> From: "Robert Gault"
> Sent: Wednesday, May 06, 2015 3:23 PM
> Subject: Re: [Coco] Upgrade MPI?
>> Joe Grubbs wrote:
>>> Through sheer blind luck I have acquired a Tandy branded 26-3124 MPI. It 
>>> looks barely used, and more importantly, the OE warranty sticker is 
>>> still in tact. Because it is "virgin" I'm reluctant to give it the CoCo3 
>>> PAL upgrade. Am I being ridiculous?
>> If you want to use it with a Coco3, upgrade it! It really is not an 
>> "upgrade to make it 'better'" but a required change to prevent ghosting 
>> of I/O bytes into the GIME region. If you intend to use it with a Coco1 
>> or 2, you do not need to make any changes.
>> -- 
> Does this ghosting cause more than software/hardware conflicts?  Can the 
> GIME actually be damaged?
> I used a non-upgraded 26-3124 for decades with  a Coco 2  and two 
> different Coco 3s without issue.
> Perhaps I'm just lucky.
> School me, Robert.

By the way, I'm not trying to be a smart aleck.  I'd really like to know.  I 
remember reading an article by, I believe, Marty Goodman, about the PAL.  He 
definitely stressed having the MPI upgraded, but I only recall him 
emphasizing program corruption and data loss, not hardware damage.  Of 
course it's been 25 years or so since I read it, so I could be remembering 

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