[Coco] eBay MPI Heads Up

[K. Pruitt]

Okay, that was quick.  The board just unplugged without issue.

Here a pic of the component side of Marty Goodman's PAL selector

https://www.dropbox.com/s/b0s3nwj4viis50y/DSC01414.JPG?oref=e

To the left (left side of your monitor) is the empty socket in to which the 
board is plugged. The blue thingie is the part that plugs in to the empty 
socket. It is simply a electrical pass-through (I'm sure that's not the real 
name). It is not an IC.

It is essentially just the two versions of the PAL chip and a switch to 
choose between them.

Simple and elegant.

----- Original Message ----- 
From: "K. Pruitt"
Sent: Friday, May 29, 2015 10:02 PM
Subject: Re: [Coco] eBay MPI Heads Up


> 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.
>