I'm winding up with an old TM-231a as a backup rig.
Oh, the good 'ol days when solid monobanders were cool and not just for newbies :)
It looks like there are serial pins on the mic connector but I don't see much info about it. I don't have the radio yet.
Looks like there's some sort of functionality expected, based on the accessories available:
http://www.universal-radio.com/catalog/fm_txvrs/tm231a.html
I have (access to) a TM-251 and it's so (damn) simple I have a hard time imagining it being PC-programmable, and it's two generations newer. We don't even have things stored in it -- we just use the VFO.
I'm not exactly sure what the contemporary commercial equivalent was, but I know that the TK-705 is programmable by computer via some sane serial interface and it looks darn similar to the TM-231,241,251-era devices.