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

[RETRO Innovations]

On 3/7/2015 1:56 PM, Gene Heskett wrote:
> I saw that easily enough, but cannot visualize it for two main boards 
> in connectors 2 & 3 of each cable? 
Well, at this point, it's an idea of the type:

*Don't know if it will work, but should not do anything that would 
artificially preclude it, all things being equal*.

I agree the second attachment will be a bit wonky, but length is 
probably the most pressing thing, and there's nothing I can do about 
that :-(
> 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.
I really like the previous idea of moving the switch and LEDs to the 
main board.  I am in process of doing that now.  It allows me to better 
rationalize the need for 2 IDE cables.
> jumpers or switch?
> Flea clip jumpers per slot?  Accessible by suture clamps when that cart
> is removed?  I certainly would not ask for anything fancier than that,
> and certainly not when the one doing the work is doing it for free.
jumpers are easy, and electrically stable.  switches are not, and create 
RF (all that travel in the switch creates an antenna for non steady 
signals) so I greatly discourage them (you can use switches, if you put 
the switch on a TTL switch (like a set of buffers, or mux), which keeps 
the signal path pure, but that adds ICs.
>
> As it is, I feel I may actually be slowing the work, when what I am
> interested in is working hardware from the first run of boards.  The
> many eyeballs theory.  Sometimes the minutia can escape our
> consciousness, its happened to me on many occasions.  Fixing a problem
> is comparatively cheaper when fixed at the line on a screen stage. :)
>
> IOW, I can be told to shut up anytime.  Designing by committee tends to
> get un-manageable if a halt is not called to the feature creep.
As I noted before, this is not my first trek down the path, and I can 
sort the wheat from the chaff.  For instance, the ideas this morning are 
invaluable:

  * The idea to move the switch and LEDS to the buffer board sounds
    plausible, and cleans up the design.
  * Moving the switches allows me to put all of the power on one edge,
    which is a good idea.
  * While moving the power around, I realized it will absolutely not
    work where it is in a enclosure.  Since the enclosure much be wider
    than the PCB on the sides, the connectors would end up significantly
    recessed into the enclosure, which is a mess.
  * But, moving them to the front side of the PCB is OK, because that
    portion of the PCB can rest against the enclosure wall.
  * The suggestion to put LEDS on individual resistors is a good future
    proof design idea, since I have an idea that will allow multiple
    slots to be *on* at once.
  * The suggestion to move the SV connectors further from the slot conn
    is massively appreciated.

On the other hand

  * Symmetric mounting holes is probably not going to happen :-)
    Something has to give.

Still, a good design needs a bit of time to "season".

Jim

>
>> Jim
> Cheers, Gene Heskett


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