usb
^ This boot floppy allows a computer to boot off usb even if this is not supported. I think it may only work with knoppix. However it may be possible to adapt the floppy. If this mirror goes down search for "featherlinux"; this is a knoppix remaster that fits into a 64mb usb stick.
cdrom
^ This boot floppy allows you to boot from cdrom even if the motherboard doesn't support it.
I have used these 2 boot floppies to get my p90 to boot off usb and cdrom.
This is extremely rare knowledge.
gentoo forum link