> I think their cash registers ran SCO Xenix.

Tandy had a Xenix license from Microsoft and shipped a version on their TRS-80 Model 16 and Tandy 6000 machines (both of which were Motorola 68000-based). It would be interesting to know how much of their own stuff they used internally. I have a recollection of a (potentially apocryphal) story the TRS-80 Model 1 had a "fallback" use as an in-store management computer if they failed to sell.