Okay, you guys got my attention enough to start looking deeper into the disassembly. Now that my disassembler supports adding comments, I can concentrate more on the code.
From everything described so far, the 68000 side seems to have RAM at 000000-000FFF, and EPROM at 008000-00BFFF. It also has two 6850 ACIAs at 010041/3 and 010061/3, with the latter connected to the keyboard/display unit.
The keyboard/display unit is completely separate, with its own 40-pin MCU. The 68000 just pushes display data to it, and receives codes from the keypad. The keypad is simply 8N1 ASCII, and 7-segment patterns are sent to the display as 0x50, 0x20+index, and two hex ASCII digits of the LED pattern. The digits and rows of 8 LEDs are numbered starting at zero, going left to right in each row.
For some reason the "Serial Display Interface" MCU is in a ZIF socket accessible from the top of the "suitcase" model. I'm going to assume that the 68000 board is stacked below it on the suitcase version. I don't even see this board or chip in the "wide" version pictures. The random 7-segment display contents in one of the photographs imply that it might not clear the display on startup.
The ribbon cable on top next to the MCU is probably the serial communications, and the edge connector is probably where the MCU drives the display board. On the "wide" version, there is a ribbon cable directly connecting the 68000 board with the display board. For some reason there is an IDP connector on that cable, so maybe it isn't original and was pulled out of random parts for an ebay picture. I don't see any photos of the suitcase 68000 board, so there's not much more that can be determined. It is possible that the wide version doesn't use the serial display interface, but then it would need a different ROM.
If someone has the suitcase version, you should have the MCU dumped so that others can replace a missing one. It will probably be an 8742 or 8732, but none of the pictures show it up close.