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From: garry@TCGOULD.TN.CORNELL.EDU (Garry Wiegand)
Newsgroups: mod.computers.vax
Subject: Re: virtual terminal names and LATs
Message-ID: <8610312023.AA20630@tcgould.tn.cornell.edu>
Date: Fri, 31-Oct-86 15:23:46 EST
Article-I.D.: tcgould.8610312023.AA20630
Posted: Fri Oct 31 15:23:46 1986
Date-Received: Mon, 3-Nov-86 20:57:45 EST
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Organization: Cornell Engineering && Flying Moose Graphics
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In a recent article Ruth Milner said:
>Regarding terminal names, it was recently noted that VTAxxx names can be
>too long for some programs. In fact there is the same problem with LAT
>terminal names (LTAxxx). Each time someone logs into the system on a LAT,
>the terminal number is incremented. After about 5 days of uptime on our
>system, the number gets up to 1000. After that, a lot of things stop
>working. For one thing, getjpi's returned answer loses a character
>...

This is buggy in the operating system, not just in a number of programs.
Specifically, the process-control-block field "PCB$T_TERMINAL" is a
counted-Ascii string of total size 8 (and net size 7). So "VTA999:" fits,
"VTA1000:" does not.

I've been eagerly awaiting the day when we fall over 1000 (we're at
883 right this minute -- go go go!) and everything breaks. I've
especially been wondering whether the logical "TT" will come out 
wrong - I use it a lot.

Seriously, the posted patch to CLONE_UCB should fix the entire problem.
It should also make your next system upgrade fail with a "checksum
error" :-)  You should restore a virginal Sys.Exe before upgrading,
and re-apply the patch afterwards (if Dec hasn't already.)

garry wiegand   (garry%cadif-oak@cu-arpa.cs.cornell.edu)