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

Fri Jul 2 23:08:37 EDT 2010

Brian, I just noticed that you said the chip used in this particular upgrade 
is 16 pins - and so can't be a 74ls10. The picture is kind of blurred and I 
can't make out the part number. Could you tell me how the chip is numbered? 
Obviously, the 74LS10 isn't the only way to upgrade the MPI - basically, you 
just change the addresseing based on A7, as well as CTS* and SLENB* so there 
are numerous different ways to obtain the same result. The reason that I 
used the 16V8 gal is that it was just easier for me and my lame eyesight to 
work with :-)
-John
----- Original Message ----- 
From: "Brian Blake" <random.rodder at gmail.com>
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Friday, July 02, 2010 2:29 PM
Subject: Re: [Coco] 26-3124 M.P.I. Upgrade #2


> 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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