"OK, so you could tell it to display 8, but only segments e and g, and that would display r?"
Yes I believe so. Though I don't have anything with TMS0980 emulated yet to confirm it (I only have TI-30 hooked up, but it gets stuck in a loop very quickly).

BTW I forgot to ask before: could you also post your script (or description with pseudo code) to convert a raw dump to tms1000-order dump?