Path: utzoo!attcan!lsuc!maccs!cs4g6ag
From: cs4g6ag@maccs.dcss.mcmaster.ca (Stephen M. Dunn)
Newsgroups: alt.msdos.programmer
Subject: Re: Int 3
Message-ID: <25B616F3.4191@maccs.dcss.mcmaster.ca>
Date: 18 Jan 90 19:20:19 GMT
References: <10442.740.forumexp@mts.rpi.edu>
Reply-To: cs4g6ag@maccs.dcss.mcmaster.ca (Stephen M. Dunn)
Organization: McMaster University, Hamilton, Ontario
Lines: 16

In article <10442.740.forumexp@mts.rpi.edu> Greg_d._Moore@mts.rpi.edu (Commander Krugannal) writes:
$     Looking over some old code fragments today, I cam across a call
$   to int 3. Neither I nor any of the other programmers in the office
$   could recall what it did. Does anyone know?

   int 3 is the breakpoint interrupt.  It's a one-byte instruction so
that it's easier for a debugger to put it there in place of whatever
other instruction was there.  Of course, you _can_ use it for anything
you like - you could write a little routine to play "Yankee Doodle
Dandy" whenever int 3 was executed if you wanted.  But it was designed
for use as a breakpoint.
-- 
Stephen M. Dunn                               cs4g6ag@maccs.dcss.mcmaster.ca
          <std_disclaimer.h> = "\nI'm only an undergraduate!!!\n";
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       "I want to look at life - In the available light" - Neil Peart