Path: utzoo!dptcdc!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!osu-cis!sppy00!jmv
From: jmv@sppy00.UUCP (Jim Vickroy)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Question 3 of 3 for assembly language programmers.
Keywords: How to uninstall TSR's?
Message-ID: <299@sppy00.UUCP>
Date: 18 Apr 89 15:24:36 GMT
References: <4498@tekigm2.MEN.TEK.COM>
Reply-To: jmv@sppy00.UUCP (Jim Vickroy)
Distribution: na
Organization: Online Computer Library Center, Dublin, Ohio.
Lines: 31

In article <4498@tekigm2.MEN.TEK.COM> alanr@tekigm2.MEN.TEK.COM (Alan Rovner) writes:
=>
=>Suppose I have a TSR already installed and working ok, and I want to disable
=>it and return its memory back to DOS.  Can this be done without rebooting?
=>I was thinking of passing a command line argument like -u to uninstall
=>the TSR.  But I don't know the assembly language details.  Thanks in advance
=>for any info.

Interrupt handlers get their information through the registers (see, for
example, INT 21H). What many interrupt handlers, therefore, do is define a 
"deinstall" function along with all of the other functions of the particular 
interrupt. Somthing like passing a FFH in AH (usually the register to pass
function numbers) would deinstall (actually disable unless your handler is
smart enough to physically deinstall itself and return it's memory back to
DOS). The problem with the -u is that there is no "reliable" (of course this
is debatable) way to check if your handler has already been installed.

jim
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