I've been looking for a DiskFax machine for a long while, in fact I think it was my searches for that that ended up finding this one (on ebay).
That was a few years before the FISK, right? (FISK was ~1993). What was it internally? Something like a 6502/Z80 ?
Memory was 128K of Intel flash with 8K fixed boot partition and 64K of RAM.
Z8530 for the UART, Rockwell chipset for the fax portion. I seem to remember lots of messing around getting the parameters correct for the filters to detect dial tone for various european telco approvals. There was also a pass through port to allow plugging a fax machine in the back (can't remember how that worked though)
I can't remember what we used for the floppy disc controller (I seem to recall we supported single density floppies so we didn't use a multi-IO chip) and later models used a IDE drive with a 16->8 bit converter card.
Somewhere I probably still have the schematics.
I'd love to see those schematics if you can find them!