Date: Sat, 03 Nov 2001 10:55:45 +0200
From: "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>
Sender: halo1 AT zahav DOT net DOT il
To: elj AT sky1 DOT elj DOT org (Edwin Johnson)
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CC: djgpp AT delorie DOT com
In-reply-to: <slrn9u5g6a.2sj.elj@sky1.elj.org>
Subject: Re: Interrupt handled RS232
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> Newsgroups: comp.os.msdos.djgpp
> From: elj AT sky1 DOT elj DOT org (Edwin Johnson)
> Date: 2 Nov 2001 21:47:11 GMT
> 
> I have the protected mode handler working, so the long post of code can be
> ignored for now. As of yet the real mode handler doesn't work, but I suspect
> it has to do with my transferring it to low memory, which I don't understand
> fully.

Hardware interrupts are by default always reflected to the PM
handler.  So the only way you could see your RM handler called is if
the interrupt happens while the CPU is in real mode (like while the
foreground program is writing to disk).

Also, please note that the FAQ advises a specific order of hooking the
interrupt if you install both a PM and an RM handlers.  If you don't
follow that order, you might not get real-mode handler called.