fast tty input driver

[utzoo!duke!decvax!ucbvax!Greg at NPRDC]

I have a DH driver that allows you to select a group of ports for "direct"
I/O -- i.e., charecters do not go through ttyinput, etc.  We use it to
permit Unix to act as a front-end on the ARPAnet for other machines.  It
has been run as fast as 9600 baud, but 4800 seems more reliable.  It also
(with a suitable-wired connector) controls the other host's Clear-To-Send
signal so that it won't get overrun.  Is this sufficient?