[Coco] eBay MPI Heads Up

[Barry Nelson]

The test for the CoCo 3 upgrade on a MultiPak is:
PRINT PEEK(&HFF90)
The correct (upgraded) value that should be returned is 126.
The non upgraded value is 255.
This test must be performed using a CoCo 3 to be valid.
Using the MultiPak for the short time needed to perform this test even a few times should be safe. Running the MultiPak continuously day to day on CoCo 3 with out the upgrade is NOT safe.

On May 30, 2015, at 1:18 AM, coco-request at maltedmedia.com wrote:

> Date: Fri, 29 May 2015 22:02:54 -0700
> From: "K. Pruitt" <pruittk at roadrunner.com>
> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> Subject: Re: [Coco] eBay MPI Heads Up
> Message-ID: <025901d09a95$ef9db880$0200a8c0 at Desktop1>
> Content-Type: text/plain; format=flowed; charset="utf-8";
> 	reply-type=response
> 
> Okay, here's the low down on my initial testing...
> 
> The MPI itself works just fine.
> 
> With the switch in the Coco 1/2 mode position, the Coco 3 will not see the 
> disk controller and will boot in to extended color basic.
> This is expected behavior according to the Marty Goodman article that 
> Stephen provided. I assume it will see the disk controller when running a 
> Coco 1/2 but I haven't tested that yet (have to find the TV adapter thingie 
> to hook it to a TV).
> 
> With the switch in the Coco 3 mode position, the disk controller is 
> recognized and I get the Disk Extended Basic screen as normal.
> 
> I can boot in to SDC-DOS and everything seems to work fine, but attempting 
> to boot in to NitrOS9 or OS9 via the SDC results in the computer hanging at 
> the shell prompt. My 26-3124 had this same issue with the SDC when trying to 
> boot either flavor of OS9.
> 
> I intended to examine it with a loop before testing it, but what the heck 
> just plug it in and hope the magic smoke doesn't escape. So now, with magic 
> smoke still contained, I am going to examine Marty's board with a loop. 
> Whoever repaired the traces on this board is very good with a soldering gun. 
> So kudos to whomever it was.
> 
> If the board can safely be removed (more examination is required to make 
> that determination) I will photograph the component side of the board and 
> post them.
> 
> By the way, this is serial number 005684. It's a grand-pappy even among the 
> grey MPIs.