From:	MERC::"uunet!CRVAX.SRI.COM!RELAY-INFO-VAX"  7-JUL-1992 07:22:19.58
To:	info-vax@cdclu1.genrad.com
CC:	DONGRAY@cdclu1.genrad.com
Subj:	Re: serial <-> virtual port ??

> I installed a modem on a serial TXA port of one of our VAX 6000 last days.
> There was lots of trouble with the 'set term' command, which is not very well
> explained in the manuals.
>
> Anyway, after several tries I succeeded, but I was a little astonished about
> the device and terminal characteristics I saw. The serial device acts
> like a virtual device ?!?

[...device and terminal characteristics omitted...]

> Does anyone have an explanation ?
> Does it matter, that I've fooled around with the 'set term/dialup' command ??
>
> Thanx,
>
> Lars
>
>
> --
> /------------------------------------------------------------------------------\
> | Lars Sprute  -R-                            Net:                             |
> | DESY (Deutsches Elektronen Synchrotron)                                      |
> | Notkestr. 85                                sprute@vxdesy.desy.de            |
> | D - Hamburg 52                              SPRUTE@DESYVAX.BITNET            |
> | Germany                                     VXDESY::SPRUTE.DECNET            |
> | Tel. +49 40 8998 4364                                                        |
> \------------------------------------------------------------------------------/

This is the normal situation when virtual terminals have been enabled. This is
done by loadinbg the VT driver ...

  $ MCR SYSGEN CONNECT VTA0/NOADAPT/DRIVER=TTDRIVER

... and setting the terminal 'disconnect' bit, usually done in MODPARAMS by
adding %X20000 (131072) to the default value of TTY_DEFCHAR2, though you could
just do a "SET TERM/PERM/DISCONNECT" for all the modem terminals.

Virtual terminals implement the DISCONNECT command and allow session created
from modems to stay alive after an accidental hangup for a time determined by
TTY_TIMEOUT before they are logged off, thus allowing the user to reconnect. It
also works for LT termianls (DECservers) where the LT terminal may be
different; thus it avoids the problem  of the terminal suddenly changing during
a disconnect. Of course, for a modem it will usually connect back to the same
physical device.

It's probably the situation that you want; unless you want modem hangups to
kill the sessions?

As a final note, if you do have virtual terminals enabled via the SYSGEN
parameter (as we do, because we want it to work for LT terminals), then you
should do a "SET TERM/PERM/NODISCONNECT OPA0:" during startup or you won't be
able to make use of the "Login allowed from OPA0:" feature when you need to log
in and too many other users are already logged in!
------------------------------------------------------------------------------
Name : Derek Dongray, Systems Manager, GenRad Ltd.
Phone : 061 486 1511 ext 166
PSS : 234261600119::Dongray                 UKnet : Derek.Dongray@GenRad.co.uk
InterNet : Dongray@cdclu1.GenRad.com        CompuServe : 70374,2745
Address : Monmouth House, Monmouth Road, Cheadle Hulme, Cheshire, SK8 7AY, UK.