Heh! Clever little rat 3@$^@&%$! Like I guessed, there are a whole bunch of the alternate ground lines that are NOT connected to ground.

Looks like the middle ground line on both connectors would be the power source, but there are still a lot of "ground lines" unaccounted for . . .

. . . nuts! :-/

Found another hit: MICROSYSTEMS SwapBox* Classic Dual slot supports Type Cards

. . . using image search helps a LOT sometimes. :approve: