I don't remember much but I see there are many articles from people who've hooked a Minitel up to a Raspberry Pi or similar in recent times. I think it had a non-standard DIN connector, and you could make up a special cable to get RS232, possibly with a voltage change, not sure about that, and then I think you just had to talk to it very slowly; maybe 1200/75 baud, something like that. There were terminfo definitions for minitel (various models) and I see they are still there in Debian, which means you can write programs using libcurses to do primitive, slow 80s style user interfaces!