@mwichary I don’t know. This one came to me from someone who had it in their garage for a long time after getting it from someone else. Professionally made metal case and PCBs with a couple of wire patches. socketed PIC16C73A microcrontroller, 7 other 74 logic chips. Bears the serial number 1015 which suggests a couple of dozen were made.
Numeric keypad and 3×4 above are separate PCBs on ribbon cables but ALL the rest is a single PCB so perhaps there were (intended) options.
192 keys!