How BIOS boot from floppy and CD-ROM differently?

My test OS boots from floppy before, now I am trying to boot it from CD-ROM. But I am not quite sure how BIOS treat the floppy boot sector and CD boot sector differently. It seems the CD boot sector is much bigger than floppy boot sector. Is there any other things开发者_如何学C I need to notice?

Could anyone elabrate the details about it or point me to some links?

Thanks.

I would recommend booting with GRUB. Use the eltorito image to make the CD bootable. Then include your kernel in the CD image and make an entry in the GRUB configuration file use your kernel file like: kernel mykernel Include any initrd if you have and boot. To know about CD boot sectors i would tell you to have a look to the ISO Specifications

Wikipedia link

The ISO 9660 File System

ISO9660 Simplified for DOS/Windows

OSDev Link

I hope these links would help

To start, you should know that the bios does not use sector one of the CDrom to boot but sector 17 if I remember right.

You can learn alot by looking at the cdrom boot files which bootloaders such as grub or lilo use. Maby even minix has a cdboot option.