I know that many of the FPmini builds are still in process
and other than the errors outlined in the wiki I haven't
received much feedback on operation with various CPU
cards.
That being said and feeling confident it was going to be
production ready and not a prototype I went ahead with
what I call the full size version. This is actually intended as
a drop in replacement for a popular unnamed S-100 front panel.
This reproduction includes a few enhancements:
- Slow Step Operation
- Drivers for many of the buss signals
- Slde DIP switch on top of the board for board configuration
- Option for 8080 and Z80 CPU's
- Switches do not cover any IC's (like original design. had to
unsolder switch to replace IC)
for the prototype board price. This board is 17 inches long and
85 cubic inches. I tried a new Chinese PCB company for this
first prototype because they offered the best price.
Well I was pretty excited when the five prototype boards
arrived. My excitement soon turned to dreed. The boards
looked very nice however they did them with thickness of .6mm
instead of .062 inches! They are so thin I can almost bend then
in half. It's no so bad having an extra thin board
and considered using them, however as you can image the card edge
does not make contact with the female S100 connector. It does
fit the connector of my S100 prototype board so may be usable.
One thing that was difficult was getting the 10 mounting holes
laid out perfectly. The board would have to be an exact match in order
for it to mount correctly in the old chassis. I struggled with all sorts of
measuring approaches. Not being able to print actual size it was a best
guess with hope and prayers it would line up correctly. Then one day I
had a great idea. Why not mount up the original board in my mill and use
the DRO's to measure hole position. Man that worked perfect. I was able
to get hole positions within .001 thousandths of an inch.
With the prototype I did confirm that the mounting holes are perfect.
I assembled the PCB with the photomask and two plexiglass pieces. Screws
dropped in perfect and mounts to chassis. Using the DRO to measure
the holes worked like a charm! I was worried it would take several versions
of a prototype to get them right.
On a lighter note regarding revisions. Some manufactures like to use code
names for projects. I'm starting to sense a theme on my boards. Not intentional,
purely coincidental. If you notice the date on the FPMini is was 9/11. This
full size board was completed on 12/7. I refer to them as the 911 board and the
Perl Harbor board. Both were historical events were major disasters so maybe I
should find happier anniversaries (Don't pay attention to the coffee cup in the photo) :)
-- Don Caprio ilv...@gmail.com
