🚀 go-pugleaf

> Indeed, you have to retrieve the SCC's control address from low memory and
> poke the chip into "clock channel A from TRxC" and "divide-by-(16,32,64)",
> but having done so, I've had no trouble running MIDI data capture, filtering,
> rechannelizing and echoing utilities written entirely in Lightspeed Pascal
> 	Lee Story @ Wang Labs

Lee is entirely correct.  You can use the existing driver with an external
clock provided you poke the appropriate SCC hardware control register.  My
objection is that there is no IM call that does this for you in a portable
way.  Once you resort to hardware fiddling (either by my approach or Lee's),
you have violated Apple's portability advice.  There just doesn't seem to be
any clean way to get high, non-standard baud rates "legally."

Aside: The DEC machines often have two baud rates called Ext A and Ext B
which are specifically for external clock support.  Maybe Apple will provide
that in a future release of the serial driver.  Please.

	Steve Falco