Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site brl-tgr.ARPA
Path: utzoo!watmath!clyde!bonnie!akgua!gatech!seismo!brl-tgr!tgr!ron@BRL.ARPA
From: ron@BRL.ARPA (Ron Natalie)
Newsgroups: net.unix
Subject: Re:  Info needed on pseudo TTYs in SysV
Message-ID: <3073@brl-tgr.ARPA>
Date: Sat, 9-Nov-85 11:42:06 EST
Article-I.D.: brl-tgr.3073
Posted: Sat Nov  9 11:42:06 1985
Date-Received: Tue, 12-Nov-85 04:16:46 EST
Sender: news@brl-tgr.ARPA
Lines: 17

Actually, the way the System V terminal driver is set up, it is
designed to help you do this.  Unfortunately, it means driver
hacking, and you really do need a UNIX source license.  If you
can find one, look at the xt.c driver for running the BLITs and
tty5620 terminals, it is switching a packetized input stream
consisting of six virtual terminals into separate xt000 devices.

System V doesn't really have pty's at all.  The SXT (which are VR2
anyhow) devices are a kludged up version of the code for the xt
driver.  What they do is switch a single real tty line back and
forth between a set of virtual terminals.  Doing this, they achieve
something roughly equivelent to the 4.2 Job control.  The difference
is that you actually have a shell on each of the sxt virtual devices.
What you are really doing is switching your real tty to several virtual
tty "contexts."

-Ron