[comp.os.vms] Pseudo-terminals on VMS

KVC@ENGVAX.SCG.HAC.COM (Kevin Carosso) (06/19/87)

> Several times I have seen reference to "pseudo-terminals" or PTYs.  Does
> anyone know if this is a DEC supported product?  I've definitely seen
> them referenced in VMS GNU Emacs, but I've never seen them work.  I
> suspect that PTYs are what I want but I don't know how to get my hands
> on them.

Yes, pseudo-terminals are what you need.  A pseudo-terminal (at least the
one fairly good implementation I know of for VMS) is really two devices.
The master device (which the program controlling the PTY uses) acts sort
of like a full-duplex mailbox.  You just read and write it.

The other device looks and acts like a standard VMS terminal, responding
to all the TTDRIVER QIO functions, etc...  That's what addresses the problems
you see trying to use mailboxes for this sort of thing.

Unfortunately, there is no PTY supplied or supported by DEC with VMS.  Too
bad, especially since they keep needing them for their own damn products
(eg. DEC test manager, DECwindows) and have at least one internal
implementation.

The best one I know of, and the one most people seem to be using, is generally
referred to as the CMU PTY drivers.  It was originally written by Dale Moore
at Carnegie-Mellon many years ago. I did quite a bit of work updating the
drivers and fixed some severe bugs. I made my version available to Marty
Sasaki for inclusion in the VMS GNU EMACS distribution and I sent it back to
Dale at CMU.  It should also be available for anonymous FTP from
OBERON.USC.EDU in ./pub/pty.com (a DCL archive file, just get it and "@" it to
restore the sources). It may also be available from others.

Make sure that the drivers, PYDRIVER and TPDRIVER, are both at least version
V04-006 and include my edits (check the edit history) up through 5-DEC-1986.
Anything before that, unless fixed by someone else, will not run reliably
under VMS V4.

If anyone has any edits subsequent to mine, I'd very much appreciate a copy
of them.  I have heard that someone within DEC has done some more work on
it.

I'd prefer not to mail the sources out to everyone and his grandmother,
so if you can get it via FTP that'd be easiest.  If someone who's got the
latest could make it available via FTP (I can't) that'd be appreciated.

        /Kevin Carosso                     kvc@engvax.scg.hac.com
         Hughes Aircraft Co.               kvc%engvax@oberon.usc.edu