> out of band, e.g. via ioctls You seem to be assuming terminals designed to support Unix, when in fact it's the other way around. None of this stuff is Unix-

> out of band, e.g. via ioctls You seem to be assuming terminals designed to support Unix, when in fact it's the other way around. None of this stuff is Unix-specific; it's just ISO 6429 / ISO 2022 / ASCII (or ECMA-48, ECMA-35, ECMA-6 if you want free copies). Out of band? Do you suddenly double everyone's wiring costs? That won't fly. How about multiplexing control and data streams onto the same channel? Yeah, that's exactly what ISO 6429 / ISO 2022 / ASCII does. If you want to express terminal control using function calls rather than inserting raw multiplexed control sequences into text — Yeah, that's a good idea… which Unix has had since 1978.