Hardware flow control for TTY ports under V.3

[Uwe Doering]

paul at frcs.UUCP (Paul Nash) writes:

>I think that I have a problem.  I need to talk from a TTY port on
>a 386 Unix box (Intel V.3.2) to a device that does hardware flow
>control.  The output port (currently) uses the FAS drivers, but
>this software needs to be portable to machines that don't have
>such luxuries.

There is no portable way to do hardware handshake under UNIX. The
termio(7) man page author didn't think of it (this is the only
explanation I have for that omission). And therefore, every vendor
chose his own way of doing hardware flow control. Many implementations
do hardware flow control transparently (as does FAS), so that a program
doesn't know (and doesn't _have_ to know) that it actually uses a port
with hardware handshake. On the other hand, SCO decided to do it non-
transparently, that is, the program has to know about certain termio(7)
flags and has to set them to enable hardware flow control.

      Uwe
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