I haven't seen it documented, but it works on both a P3B-F and CUSL2. If you hold down the <esc> key during boot up, a little boot loader screen pops up. You can pick on the fly, any device to boot from. This would be floppy, any HD, CDrom, SCSI device. Real handy if you have a dual boot on two drives, or for that once in awhile occasion that you need to boot from a floppy or CD. Nice feature.