Date:	Wed, 4 Nov 1998 11:16:17 +0200 (IST)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender:	eliz AT is
To:	Jeramie Hicks <Jeramie DOT Hicks AT mail DOT utexas DOT edu>
cc:	djgpp AT delorie DOT com
Subject:	Re: DJGPP-written OS
In-Reply-To:	<363e3b5e.180409204@newshost.cc.utexas.edu>
Message-ID:	<Pine.SUN.3.91.981104111558.25255T-100000@is>
MIME-Version:	1.0
Reply-To:	djgpp AT delorie DOT com

On Mon, 2 Nov 1998, Jeramie Hicks wrote:

> I'm toying around with writing a barebones OS (initially being able to
> boot and walk around a hard drive only). I'd like to use DJGPP to
> write the command interpreter, but I'm not sure which DOS interrupt
> handlers I need to write. What interrupts does a DPMI provider or the
> DJGPP stub need initially provided to function properly?

The interrupt handlers are not usually part of the command
interpreter, they are part of the operating system itself.  The
command interpreter is just a user interface to basic operations like
moving around the directory structure, managing files, running
programs, etc.

So it is not entirely clear what are you asking about.

> I mean, I can figure out what DOS functions my own code needs, but
> what about the stub and DPMI program?

Clearly, the answer is in the sources.  I suggest to take a good look
at the files in djlsr201.zip that pertain to the startup code.  The
src/stub/stub.asm file and the src/libc/crt0 directory should be the
starting point, and then look up any library functions called by
crt0.S and crt1.c.

As for the DPMI provider, if you want to use CWSDPMI, look at its
sources (v2misc/csdpmi4s.zip on SimTel.NET).  Other providers will of
course use somewhat different set of DOS/BIOS calls.

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