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

[RETRO Innovations]

As a stepping stone to the 8 port unit, I thought I'd finish the 4 port 
one that I had started, since the same design is usable for both, just 
the CPLD size has to change.  As of right now, the design:

  * All data lines routed
  * All CPLD lines routed except switch select lines
  * 1.15" spacing btween ports (25mm = 1.00", and I could just not make
    that work with the CPLD size.  I hope 1.15" will work
  * Initial decoupling caps in place, not all routed though.
  * All power buues are routed

To do:

  * Add 3V3 regulator (have to create a footprint
  * Check dimensions of portion that goes into Coco (Anyone have a high
    res scan of a PCB that has the grounding ears?  I am trying to
    follow Gene's measurements, but it's difficult without a pic
  * Determine cabling option and reroute lines to headers
  * Add PSU connector(s)
  * Tie ground planes together at edges.
  * Add Large electrolytics on each port for power stability
  * Add standoff mounting holes

Lots of minor stuff, but routing was the more complicated, so I focused 
on it first.  I'll probably still move some of the lines around (and the 
LEDs will have to move, as they are right under the carts now), but the 
CPLD lines should be close to final.

Without ground pour:  http://s6.postimg.org/a3xvuex6p/PCB2.png

With:  http://s6.postimg.org/wz0rx2npd/PCB.png

Jim

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