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

[Brian Blake]

If I had to guess, based on what was told to me, I'd say the upgrade time
was late '04 or early '05. If I'm not mistaken, he bought a 512k CoCo3 from
you about the same time - have to dig out the papers to be sure and not clue
where those are at, lol.

The coded IC would make sense as the one used in the upgrade is 16 pins and
a 74LS10 is 14 pins.

I used one of John's GAL upgrades; it works fine so far. I want to try the
74LS10 just for the helluvit...



On Fri, Jul 2, 2010 at 2:55 PM, Mark Marlette <mmarlette at frontiernet.net>wrote:

> Brian,
>
> Depending on when the mod was put in, I have enhanced the installation.
>
> I don't have the info in front of me right now.
>
> The IC could very well be an inhouse chip, ie: coded. It is a 74ls10.
>
> Regards,
>
> Mark
>
>
>
> ----- Original Message -----
> From: Brian Blake <random.rodder at gmail.com>
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Sent: Fri, 02 Jul 2010 17:08:28 -0000 (UTC)
> Subject: Re: [Coco] 26-3124 M.P.I. Upgrade #2
>
> 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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> >
> >
> >
> >
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