It looks like what I’m looking for from CSPI (aka CSP, Inc.) is the “SuperKit”
board support, function, and RPC library for the SuperCard SC-3XL and SC-4XL,
along with their documentation.
There are mentions of it in the Wayback Machine for http://www.cspi.com/ and
the vendor is still around, but there’s obviously no mention anywhere on the
current web site of this stuff, and I doubt contacting their support would do
any good…
Does anyone have more detail? Or do I have to reverse-engineer any ROMs that
happen to be on these boards?
— Chris