OSDev.org

whenever i try to boot my boot loader off of a floppy, i get teh error "NTLDR is missing press any key to try again"

This mean that your Floppy disk is formated with NT or newer version of windows, and your boot loader is not installed on the first sector.

Use the windows format utility to format the floppy disk again. Use partcopy or rawrite to copy your bootsector to sector 1 on the floppy disk.

OK, a few things:

- NTLDR is the boot loader for Windows systems that use the NT kernel, which include Windows 2000 and Windows XP. Did you format the disk under WinNT, Win2K, or WinXP before using it to test your boot loader? Was it "preformatted especially for Windows XP" when you bought it?

- How did you copy the boot loader to the disk?

- Did you test the boot image on a simulator or virtual machine (Bochs, VMware) before trying it on a real disk?

i formatted it under windows 2000, or windows XP, i forget which one exactly but its definatley oen of those cuz i did on my schools network. i loaded the bootloader into debug, and used the command:

w 0000:7C00 0 1 0

the bootloader goes into memory at 7C00, thats wat i put for address, 0 for floppy drive, 1 for sector 1, and i thought the last argument might mean cylinder, so i put zero for that. did i do somethign wrong? btw, my file is named boot, not boot.com or anything like that, and its not stored at 100h liek com files are.

to put a file on the first sector of a floppy you should have:

-w 100 0 0 1

how do i put my test kernel on the second sector of the floppy? better yet, could you jsut explain to me wat arguments write takes in debug? and also, that disk i was trying to use which was formatted under XP, do i have to remformat it? or by putting the boot loader in the first sector, i alreayd take care of that?

by writing new code into the bootsector, you overwrite the code which Windows placed there which attempts to load NTLDR.

make sure you dont overwrite the FAT12 header which is also in the bootsector, its @ something like bytes 3 to 61.. this is the reason for using partcopy.. you can also use a program i wrote for windows that does the same thing but with a gui.. u can find it @ http://mrd.knows.it