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From: MANAGER@SKIDMORE.BITNET.UUCP
Newsgroups: comp.os.vms
Subject: SMG$ & MODEM INTERACTION...
Message-ID: <8709180322.AA00428@ucbvax.Berkeley.EDU>
Date: Wed, 16-Sep-87 21:49:00 EDT
Article-I.D.: ucbvax.8709180322.AA00428
Posted: Wed Sep 16 21:49:00 1987
Date-Received: Sat, 19-Sep-87 16:47:16 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: The ARPA Internet
Lines: 43

I've come upon a weird inconsistency in the Screen Management
routines (SMG$) that has me puzzled.  Our users connect to the VAX
via two paths...

     Most connect via a PBX at 9600 baud.  The PBX provides
     port selection.

     Others connect via modem to the pbx at 1200 baud using
     Hayes compatible modems.  Since the modem lines connect
     through the PBX, the VMS terminal characteristics are
     identical for all VAX ports.

When I write Pascal programs employing the SMG$ run time library I
get different behavior in the following setting.  If the screen contains
blank space, either because of a virtual display pasted at other than
column 1 or because of multiple spaces within a line, it is displayed
correctly on the pbx lines but incorrectly on the modem lines even though
the code is identical.

We have several programs that involve direct screen addressing (written
prior to SMG$).  These behave consistently across communication lines.
Therefore, I doubt if the modems lose characters  (besides which, the
inconsistencies always happen at the same screen locations).

My questions...

  Has anyone else seen this problem or is it unique to our location?

  Does SMG$ automatically change port characterstics?

  Can you offer any other clues as to why SMG$ routines refuse to work
  properly on modems?

PS.  Our end devices are Rainbows, VT100's, and PRO350's  -- all show
     the same screen problems.


===================================================================
Leo D. Geoffrion                  BITNET:  MANAGER@SKIDMORE.BITNET
Associate Director for             NYNEX:  (518) 584-5000 Ext. 2628
Academic Computing
Skidmore College
Saratoga Springs, NY  12866