[Coco] Multipak redesign/replacement

[Gene Heskett]

On Saturday, February 21, 2015 09:16:47 PM Andrew wrote:
> While I can't help with the design or such, I would be willing to help
> test any resulting system, if needed.
> 
> That said, what I would like to see for a new MPI would be something
> more akin to the few "backplane" systems that were available back in
> the day in the pages of the Rainbow and elsewhere (alas, I was a kid,
> and such a backplane was out of the question to my parents). I would,
> though, change things up slightly.
> 
> Instead of orienting the paks vertically, as in a standard MPI, I would
> rather that they were oriented on their sides; think of the current
> MPI, with the paks vertical, then rotate the packs 90 degrees
> clockwise, edge connector toward the cartridge slot.
> 
> There would have to be some kind of vertical interface plane for the
> slot connectors; probably all the needed electronics could be fit on a
> 2-sided board (heck, maybe on one side using SMT components). There
> would have to be some kind of extra mechanical support or such for the
> vertical board, but I think it would be doable. An alternative
> arrangement might be to have the same orientation, but the edge
> connectors facing toward the rear of the CoCo (label sides of the paks
> to the front).
> 
> The nice thing about such an arrangement would be that you wouldn't
> have tall packs sticking up so far (like the original RS-232 pak - or
> the older floppy drive controllers); in fact, since all paks are the
> same width, that's the maximum height they would be above the level of
> the CoCo. If a cable connection is doable with such an arrangement,
> all the better.
> 
> Finally - a potential thing to do might be to put a microcontroller (or
> something) on each end to buffer the I/O lines and translate the
> signals to high-speed serial (maybe USB?) - so that a thinner (and
> longer) cable between the CoCo and new MPI could be used (though I
> realize that such a solution likely has major pitfalls of its own).

Something along those lines has been on my mind since forever I think, but 
with a 80 in scsi-III sort of an interconnect, between the board design we 
have now in the part 1 of 2 file from little John.  That, IIRC uses the 
same cabling as the 80 wire IDE, but would give us 40 signal wires and a  
rock solid ground.

I think that is just a 2 layer board that we have the eagle files for, but 
I am not sure how he intended to do the interconnection between the slot 
carrier board and the logic board we already have, which has an 8 slot 
capability.  I should load that up into eagle and run it thru pcb2gcode to 
get an idea of the logic board size when laying in the mill table as my y 
motion is all used up at about 5".  It may be small enough I could make 
the first copy on my mill.  But that will wait till the local deep freeze 
is over.  Way too cold now even with the keep it dry heat thats on out 
there.

Its been so long since I designed the encoder board for my lathes spindle 
that I may as well go get the latest free version of eagle and install it.  
And probably have to learn how to do it all over again.

I'll report, when I have something to report.

Cheers, Gene Heskett
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