Real mode BIOS routine and Protected Mode

Question

I am doing some OS experiment. Until now, all my code utilized the real mode BIOS interrupt to manipulate hard disk and floppy. But once my code enabled the Protect Mode of the

Answer 1

If you'd like code to read the harddrive (or USB key) from 32-bit mode, you can find some from my OS project PwnOS. It doesn't support DMA or anything, but the basics work. Specifically, trunk/Core/IO/ATA Driver.asm contains the code for reading an ATA device, e.g. harddrive (without magic numbers! :D)

I decided not to write the code for writing a device, since I didn't want to risk it, but it's very similar. The specs can be found at the first google hit for "cottontail os dev" (you'll want the ATA/ATAPI-6 document), but they're a bit hard to follow.

If you have any more questions about it, feel free to ask. I've got code to get set up into 64-bit mode as well, as well as an assembly language editor that I specifically designed for OS development (search for Inventor IDE), in that it has built-in assembling and linking of 16-bit, 32-bit, and 64-bit code at defined addresses and file offsets. That way, you can focus on the part you're interested in, instead of the fluff.