I could drive my RC2014 from my TRS-80 4P (using the Remote Shell
coming in the next commit)! A challenge I faced was that the RC2014
spits characters too fast and the CTS line of its ACIA modules
(both the 6850 and SIO/2 ones) are hard-wired to ground, making
flow control difficult. I solved this, for now, by lowering comm
speed.

This driver improvement makes CL<? faster and makes baud rate
configurable in CL$.