Was it that only the 85 could connect to a com port, but then you could connect the 85 to the 82/83? I seem to remember pleading with the one kid with an 85 (who didn't even care about games).
IIRC there was a way to connect the TI-85 to your serial port and use some Windows or DOS software to copy files onto it. (Everyone's PC still had at least one serial port on it back then).