Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!eng.ufl.edu!math.ufl.edu!uflorida!SORROW@MAPLE.CIRCA.UFL.EDU
From: sorrow@oak.circa.ufl.edu
Newsgroups: comp.os.msdos.programmer
Subject: How can a TSR detect if it has been installed?
Message-ID: <0094A83A.9AE8E1A0@MAPLE.CIRCA.UFL.EDU>
Date: 22 Jun 91 20:57:01 GMT
Sender: news@uflorida.cis.ufl.EDU
Reply-To: sorrow@oak.circa.ufl.edu
Organization: University of Florida CIRCA VAX Cluster
Lines: 20

I have written a  TSR that takes over the command line input for INT21H, in
other words an INT21H replacement.

How can it prevent itself from being re-installed?  I know programs such as
NORTON SI will show you who "owns" an interrupt, and my program comes up 
as the owner.  If there was a way to see if the owner was NOT DOS (i.e. another
program, such as a TSR, owned it) and to not install itself in that case, I
would like to know.

Thanks,

Brian
/*
Brian Hook -- MS-DOS Programmer for Contract
-----------------------------------------------------------------
"Seamus, that's my dog...I saw her today at the reception...sorry, sixTEEN
inches....better save the women and children first...but this one goes to 11!
..anymore of that plutonium nyborg?....there can be only ONE!....like a 
finger pointing to the moon....ease the seat back...one day closer to death
*/