[Coco] make-do ROM Paks

[Joel Ewy]

Roger Taylor wrote:
> At 03:16 PM 9/16/2007, you wrote:
>
>> If you end up needing to get a 'mess of boards' made, why not just go
>> with a design that uses a 28-pin socket to accept
>> 2764/27128/27256/27512 EPROMS?  I have already created a prototype
>> layout for such a board using the ExpressPCB software. I can send you
>> the layout file if you like. You can view an image of the layout at:
>>
>> http://www.coco3.com/users/DarrenA/CoCoPak.gif
>
> That's what I was saying ... a mess of boards that use the 2764.  I
> looked at your design the other day for a few minutes.  Before I can
> submit something similar to a company to etch I will have to know that
> it will fit a CoCo port accurately.  Ofcourse, I'm not doubting your
> hard work.  It's probably ready to go as-is... ?  I know it can be
> very hard to insert and remove a case-less card in the CoCo if it is
> brand new or a certain thickness.  My J & M controller to this day is
> very tight fitting in an MPI or CoCo.  I tried it without the case
> earlier and I had to wiggle the board, etc.  Doing all of this with a
> tiny board worries me.  Then there's the issue of making cases
>
>
I've been watching this thread with interest for a while now.  I don't
want to promise anything yet, but I'm planning on building a homebrew
plastic vacuum forming box in the very near future, along the lines of
the one featured in the current issue of "Make" magazine.  There is
precedent for using a vacuum formed plastic case for CoCo cartridges in
the DS-69 Digisector video digitizer.  It is formed in two parts -- an
open-topped box that holds the PCB, and a separate lid that was glued
on, probably with plastic model cement.  I only damaged the lid of mine
slightly in removing it for an unfinished reverse-engineering effort. 
If I were to attempt to make vacuum formed project cases for the CoCo, I
think I would try to come up with a better method of securing the lid
than glue, but then, I think the DS-69 guys thought they had an interest
in obscuring the workings therein.  If I made the lip of the lid longer,
one could screw it on.  In the case of my DS-69B, I just use electrical
tape to hold it back together.

If I do end up making a usable project case for the CoCo, I'll make them
available to people on this list, but only as a raw form on a sheet of
styrene.  "Some assembly required."

Another relatively easy type of case to fabricate is one made of sheet
metal using the same general pattern as the Disto Super Controllers.

JCE

>
>> The layout has some jumper pads for configuring the A13 address line
>> and Auto-Start. The board dimensions have been minimized to reduce
>> cost, but it could easily be enlarged or reconfigured so that it
>> could be mounted in a case. The ExpressPCB price quote to have 10 of
>> these boards produced is $97.65 including shipping, 100 boards would
>> be $396.84. These would NOT have gold contacts on the connector.
>
> Auto-start is a must for my project so I wouldn't use that.  I think
> 10 boards for proof that they work and to detect minute errors would
> be the best idea, then on to bigger ideas if needed.
>
> I wonder if Mark Marlette would disclose how he had those nice
> SuperIDE cases made, or where.  Then I can compare to the cost of
> having a sheet metal case done.  The J & M controller has a durable
> metal case that looks rather simple to duplicate, although I would
> only go half the length.
>
>