[Coco] Multipak redesign/replacement

[Gene Heskett]

On Monday, February 23, 2015 09:35:22 AM Benoit Bleau wrote:
> I would buy a kit and one assembled.
> 
> Benoit.

Unfortunately this project got above my pay grade when I found that we did 
not have all the logic on the board from the eagle files we have.  The 
schematic and .brd files are for the bi-directional bus buffering section 
only.  The programmed cpld or fpga is the heart of these.

And I am NOT in favor of duplicating whats in the later ones as a gal, it 
is so slow at the gate buffer direction turnaround time that a truly 
serious logic short exists in mine for about 100ns as it does that.  Both 
the ground and power rails are bounced, as much as a volt, destroying the 
logic circuits noise immunity, by having both buffer directions enabled 
for a short period of overlap. That no doubt also contributes to the power 
used, and the chip temps. I do not think the 26-3024 design suffered from 
this problem, so its straight ttl logic must have been faster than the gal 
used in the 26-3124.

So then I went looking for Paul Barton's 8 port kit from his cocozilla 
days, and the best I was able to come up with was a .jpg of the board, in 
B&W, which I'd have to blow up quite a bit to make it ledgible enough to 
try to duplicate it, possibly in kicad as its obviously way too big to 
do/fit in the free version of eagle.  But I just did that magnification in 
gimp, and the resolution simply was jpeg compressed about 10x too much to 
be useful, and as it is in b&W, no way to be certain which side of the 
board the trace is intended to be on.  eagle color codes that bit of data.

It is, from the image I have, apparently all one long board, rigged with a 
40 pin cable between two IDC headers to plug it into the coco. So the 
packs are rotated 90 degrees, all still standing up so we'd see them from 
the edges.  With _good_ high resolution drawings in hand, the ones I was 
able to download aren't, this could be laid down so the carts all 
projected to the rear, getting much of the I/O cabling down out of sight a 
lot better than now.

But without locating Paul Barton, aka BartSr on some forums, so that his 
original hi res work can be obtained, this project is equally dead in the 
water.  And I do apologize to all for getting the hopes up.

Now, as can be seen by this thread, there is definitely some interest in 
doing this, so if any one else wants to jump in, do so with whatever 
blessings and thanks I can offer, or help with if I can.

Cheers, Gene Heskett
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