Date:	Tue, 7 Nov 2000 13:15:25 +0200 (IST)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender:	eliz AT is
To:	djgpp AT delorie DOT com
Subject:	Re: int 21h and assembler
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On Mon, 6 Nov 2000 danspam2000 AT my-deja DOT com wrote:

> I am quite new to assembler, but i need to service a hardware interrupt
> very quickly, so have had to code using inline assembler code.
> 
> The problem i have is that i can't seem to get a definitive answer
> about how to protect the service routine in memory. I think that i
> should use int 21H, but some books and lists say to use service 48 and
> some say 49, and one said 27! Also, i am not sure exactly what i need
> to pass, and using which registers (some say dx and some say bx), do i
> need to pass a segment or an offset, or both?

This is all explained in section 18.9 of the DJGPP FAQ list, which I
suggest to read.  Section 18.11 is also a recommended reading.

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