TTY Inquiry

[Doug Gwyn <gwyn>]

> > Currently under Bell UNIX, data communications for ttys are
> > uni-directional.  For example, once a port is conditioned to send out
> > data, it can not readily receive data.
> 
> What?  When I log into a UNIX system, I can type at it at the same time it's
> typing at me.  What do you mean by "conditioned to send out data"?  You
> can't have one process blocked on a "read" on that port and doing a "write"
> on the port at the same time on any current UNIX.  Programs like "cu"
> usually work by having two processes, one doing the reads and one doing the
> writes.

I couldn't figure this out either.  Finally I decided they must be
talking about setting different terminal modes (stty) for the
outgoing and incoming data channels.  If not, I wish they'd explain.