Bootstrap Hard disk access

I'm trying to write a bootstrap loader for the fun of it, I've been using guides such as:

http://www.omninerd.com/articles/PC_Bootstrap_Loader_Programming_Tutorial_in_ASM

http://hem.passagen.se/danma/nboot.htm

http://en.skelix.org/skelixos/tutorial01.php

I'm able to successfully copy over sectors from a floppy disk but when I try to access a harddisk I'm returned an error code from all int 13 functions other than reset. reset disk doesn't return开发者_JS百科 an error.

Is there something special I have to do before int 13 works for hard disks?

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Not that I'm aware of. Have you seen http://gaztek.sourceforge.net/osdev/boot/index.html ? That has a list of examples, at least one of which claims to be reading a file from "C:\" (presumably a DOS-formatted harddisk)