[Coco] 4 Port MPI PCB artwork (so far)

[RETRO Innovations]

On 3/7/2015 6:40 PM, Gene Heskett wrote:
>
> Don't forget Jim that we CAN make our own cables, and that length limit
> is purely an artifact of the much faster (relatively) speeds of an ide
> interface.
Well, they'd need to be 80 pin cables, now :-)  But, yes, I know you can 
make them.
> On the outer edge of the board, so a slider cap could be put on the
> switches stickup which is projecting past the edge of the board?
> With a small stem on the slider/knob, basically a miniature of the
> tandy switch with the same exterior in miniature.  But I'm 200% open
> to whatever idea makes it accessible from the outside if we make
> cases for it while of coarse keeping costs as low as is practical.
OK, switch has been moved to Buffer Board, and placed near the edge.

> The idea of a mux is done in SW for linuxcnc. :)  I have at least one
> such instance in the .hal files that configure the code to drive my 2
> machines.  But in practice you are right.  The flea clips are relatively
> small so I wouldn't normally point too sharp a finger at its noise
> radiation. Certainly nothing that a Holaday meter can specifically find.
I've actually never heard the term "flea clip".  TIL I what they are.  I 
think a more finished solution is a shorting jumper, like those on an 
IDE drive to set master/slave and such.

OK, attached is a link to v4 of the design: 
http://s6.postimg.org/hnbwm58g1/PCB1_4.png

  * switch is moved
  * LED footprints for 8 slots.
  * Rearranged power jacks to front of board
  * moved mounting holes
  * Added "bank" selector
  * Cleaned up bug on IDE cable pinout

Still to do:

  * Add more mounting holes (per slot, easy add)
  * Add footprints for better selector switch option
  * Determine if large PCBs with the angled "ears" will need slots cut
    in the PCB to ensure full edge connector mating
  * Lots of wasted space on bufferboard.  Hmmm
  * Add reset inhibit (and add reset button on buffer board (the
    Commodore folks demand one be on every cart, not sure why)
  * Add cart autostart inhibit

Questions:

  * Does cart inhibit need to be per slot, or just a master "inhibit"? 
    Latter is easier, of course.
  * The dotted line on the buffer board is where the Coco case ends, so
    that should show how much will be stuffed inside the Coco.  If the
    remaining amount enough, or should I lengthen the buffer board PCB?
  * Is there a howto to pry one of these Tandy game carts apart so I can
    micrometer it?
  * Seriously thinking about remove the angled ears.  Anyone care?

Jim