I would propose, as an immutable standard medium for
cctalk-relevant
micros and some minis, neither SD, nor CF, nor USB.
I would propose 110 Baud ASCII via 20mA current loop.
Well, the covneresion for those people who prefer a votlage-level
itnerface is pretty simple (a couple of opto-isolators and some
discretes), so yes, seems reasoable...
-tony