Date:	Mon, 27 Mar 1995 16:24:35 +0100
To:	djgpp AT sun DOT soe DOT clarkson DOT edu
From:	mmcmpope AT inet DOT uni-c DOT dk (MouseHouse)
Subject:	Re: How to debug after playing with timer-int ?

>(3) Does anybody have any general advise for how to debug a program involving
>    interrupt routines.  I sometimes try to use edebug (is that what its
>    called ?) and sometimes it behaves reasonably and sometimes the machine
>    hangs even before reaching points I know it reaches otherwise.
>
>    I guess that edebug isn't really intended to handle this sort of thing ?
>    (I did really expect it to.)  Is their some other way of doing it (given
>    that I can't really put prints everywhere 'cos they cause crashes ...)

Most everybody will tell you to use some special debugger with serial
support, to add some esoteric command-line switch, a million different
things. Problem is that serial support, printing etc.. all depends a lot on
the normal system resources being avaliable. Years of debugging with
graphics and interrupts has taught me not to rely on anything out of my
control. So I usually employ a simple color scheme: When the program
reaches this point, it changes the background color to red, if this or that
condition turns out false, it makes the screen blue... If you absolutely
need to see numbers, make your very own printing routine without relying on
any predefined routines or system calls.
A bit tiresome, but for time-critical stuff like interrupts, debuggers
and/or system routines just don't do the job...

-Jesper Juul

- Raw text -