On 1/13/23 16:30, RETRO Innovations wrote:
IO that is not part of the original pinout
That is an issue.
Sticking with the edge contacts, you could get a few extra lines by just
sticking them on the top & bottom ends. REX for instance really only
needs two extra pins. All the other jtag and power pins are also normal
pins on the sides. If you had a usable socket, you could supply power
and attach all the jtag pins from there, and the only extra pins needed
would be one for the 3.3v generated by the board, and one for PORT_EN on
the cpld. So the short sides are more than enough for that. And it looks
like you could get as much as 12 total extra pins at full 2.54mm
spacing, and that flexy pin page says you can do 1.27mm spacing without
getting into expensive pcb manufacture.
I wasn't even thinking about that until you said it. But 24 possible
extra pins should cover a lot of possible uses.
I was also thinking of the use case of a user wanting to dump a
commercial rom by just reading it the same way the 100 does. I guess
since we can do that in software using the 100 itself, that is probably
the most practical. It just requires packaging up the routine into
something easier to use. Steve has posted code to do it and given
permission to set up a github re-share it to start making it into
something with simpler directions, and generally develop it further, but
I haven't done that yet.
But that's just one not very frequently needed case.
Another is for things like that 4ROM, I always want the end user to be
able to re-write the thing any time after the fact, not just myself and
not just during assembly. It still requires a programmer, but at least
even a programmer is still just an off the shelf generic device you just
buy and connect, not like needing to desolder a chip or unbend the legs
on a dip on a carrier and break them after two times.
In general, for a few different reasons and situations, it would just
generally be nice to have a way to connect to the exterior pins of an
assembled carrier or module the same way the socket does. What's really
wanted is, the normal socket.
There's always dip test clips. You can still get them, but they don't
work on an assembled carrier. Still maybe that is actually not that bad
of an idea, just break the plastic off from around the 4 corner pins so
it can get in between the corner shapes on a carrier. Not as convenient
as a one-piece adapter, where the adapter is not only a single piece, it
also does all the pin re-mapping. But at least it is something you can
buy off the shelf and you could always just draw up a simple easy to
follow wiring diagram to show the wires that need to be moved around.
Then again this doesn't address the extra pins problem.
To be clear I'm not selling these things or mass producing or anything
like that, I just want to develop a usable and practical design just so
that it exists. So anyone else who wants could either make them for
themselves or make them to sell or make something else using the same
starting point as a template.
--
bkw
