Pcsim, /etc/tty/ttyconf, line disciplines?

[Ed Ravin]

I had the pleasure of installing PC-Stimulator on my RS-6000 under AIX 3.1.5.
Apart from a broken install process (the README file and the message catalog
had the wrong checksums, indicating a few last minute changes somewhere),
things worked well, until I set up serial ports for the PC environment.

My Info Expurger hypertext CD (also 3.1.5) has an article titled "How to
install Serial Port Support for PC-Simulator" (this is not verbatim, since
I'm at home and don't have an eidetic memory).  It instructs you to run
the command "/etc/tty/ttyconf -l pcsim", which I'm guessing loads a line
discipline into the kernel.

So far, so good.  I run pcsim and get my little PC window, even a VGA
screen (hey IBM!  neat software!  congratulations!).  I run MS-Kermit
and even the Prodigy service in the little window, and they work with
a modem attached to one of my RS-6000's tty's.  Both these programs
write directly to UART hardware registers, so there's clearly some
interesting emulation going on here.

But then, I exit pcsim, and ummmm, geee, the modem's DTR light is still
on.  I try to run Kermit, and Kermit can't set the baud rate or read
from the tty anymore.  I try "stty 0 </dev/tty9" and I get the message
"missing /etc/tty/stty-pcsim".  If I want the port back for normal Unix
applications, I need to reboot the machine.

Can anyone out there shed light on this strangeness?  And who is this
beast /etc/tty/ttyconf, and why, apart from the brief mention in the
pcsim install instructions, goes entirely undocumented in the Info
Intruder disk?
-- 
Ed Ravin            | I'm sorry, sir, but POSTAL REGULATIONS don't allow
cmcl2!panix!eravin  | PLASTIC tape over PAPER tape and NYLON cord on an
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