Interesting that you picked out the use of different API calls for writing to terminal, printer, and the tape. There was at least an attempt at unifying that with the "IOByte" configuration.

The idea was that depending on the state of the IOByte the actual destination of "stuff" could vary.

Of course in the CP/M emulator I wrote/maintain I ignore that byte, because it turns out everybody else did too. (Kinda like user-numbers/areas, most people ignored them.)