19200 baud on the Unix PC serial port

[Bill Mayhew]

Actually, the token for 19200 bps is "EXTA".  I believe that comes
from the DRV-11 (or something similar) on the PDP-11 that supported
two _external_ clock rates, which were supposed to have been
supplied from a clock generator in the modem.  The DRV-11 is a
single line serial RS-232C or current loop interface.

If you look in /usr/include/sys/termio.h, you'll see both EXTA and
EXTB defined.  EXTB is not suppoted by the kernel, according to a
comment in termio.h; if EXTB worked, it would be for 38400 bps.


Bill