[Coco] 26-3124 M.P.I. Upgrade #2

[Mark Marlette]

John,

I don't recall which IC I piggyback on but there are only 3 wires added as I recall. The rest are direct connects, no legs bent up.

Is she drinking again? :)

Regards,

Mark

----- Original Message -----
From: sales at gimechip.com
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Sent: Tue, 29 Jun 2010 19:39:09 -0000 (UTC)
Subject: Re: [Coco] 26-3124 M.P.I. Upgrade #2

Mark, I did just think of another caveat to this method:
If an MPI gets "wiggled" it can fry the '245 or CPU in the CoCo and it can 
fry the '245 in the MPI. With the GAL mod - a fried 245 likely=a fried GAL 
(no, not my girlfriend drinking), whereas the 74LS10 would likely be 
unaffected. So replacing the '245 with a piggybacked GAL would be more 
difficult than replacing the '245 with the 74LS10 mod. Still, I have fun 
coming up with all of this stuff. When my dad gets the magnifiers installed 
so I'll be able to see to solder again, I'll be back at building 
things -John
----- Original Message ----- 
From: "Mark Marlette" <mmarlette at frontiernet.net>
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Tuesday, June 29, 2010 1:28 PM
Subject: Re: [Coco] 26-3124 M.P.I. Upgrade #2


> John,
>
> I have done a few of these mods.... :)
>
> A few observations on your procedure.
>
> 1. 16v8 is ~1.00, 74LS10 is ~$0.50.
> 2. Difference between cut trace & cut pin? I have never reversed the mod 
> after it was installed.
> 3. 100% compatible with the Tandy Satellite Board Upgrade, install both?
>
> A good training exercise.
>
> Regards,
>
> Mark
>
>
>
> ----- Original Message -----
> From: sales at gimechip.com
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Sent: Tue, 29 Jun 2010 11:49:57 -0000 (UTC)
> Subject: [Coco] 26-3124 M.P.I. Upgrade #2
>
> I've just posted my method of using a 16v8 GAL chip to upgrade the 26-3124 
> M.P.I. to CoCo 3 compatibility here:
> http://www.coco3.com/community/2010/06/26-3124-mpi-coco-3-upgrade-2
> Normally, this is done with a 74LS10, a trace cut, and some jumper wires. 
> My method DOES NOT require a trace cut and is 100% compatible with the 
> Tandy Satellite Board Upgrade. The caveat? You have to program a 16v8.
> -John
>
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