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

[Brian Blake]

Mark,

I don't know for sure if this is a fact, but, the guys I bought my first MPI
from (an eBay purchase in 2006) said you (Cloud9 before I knew what Cloud9
was...) did the upgrade on it. According to a pic I took it looks like you
piggybacked on IC5...

http://coco.randomrodder.com/images/c9mpi_upgd.jpg

The IC on it doesn't appear to be a 74LS10, and from what I can tell, it
doesn't quite match the diagram of using a 74LS10, either...





On Tue, Jun 29, 2010 at 4:48 PM, Mark Marlette <mmarlette at frontiernet.net>wrote:

> 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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