I'm not sure what the earlier Chiron units used for a CPU (I think I read somewhere that the Chiron II used the DataMate-70 minicomputer), but I'm pretty sure that Chyron's iNFiNiT! series used 68k CPUs (possibly a 68060 in the higher end units?).

I think I've said this on HN before, but professional character generators are woefully underdocumented. In a lot of ways, they were at the pinnacle of computing power (generating quality NTSC imagery is much more easier said than done). I'd love to see something like an emulated Datavision D-3000 one day. Modern computers can push around video well enough that such things could actually be shoehorned into a modern workflow (make the emulator into an NLE plugin that is scriptable and you'd be much of the way there).