Some older BIOS have early USB boot support, but it doesn't alway seem to work.
I have a EliteGroup K7S5A Pro motherboard that detects a 1GB USB flash drive as "USB-RFD" that will not boot from a normally formatted and partitioned USB drive. I found the following solutions to handle older BIOS with legacy USB boot methods.
BIOS settings to use:
- USB Function Support = Enabled
- USB Function for DOS = Disabled
- Thumb = Disabled
- Hit F8 to bring up the boot menu or configure it in your bios if you like
Making the USB drive bootable:
- Plug the USB drive into a Linux machine
- Wipe the drive with dd if=/dev/zero of=/dev/sdX bs=64k
- mkdiskimage -4 /dev/sdX 0 64 32
- This creates a single partition as the "4th" partition which allows the older BIOS to boot the usb drive like a ZIP drive which it expects since it uses an older boot method
- You can also use another partition program and mkfs just make sure to create it as the 4th partition with 64 heads, 32 sectors
- mkfs.msdos /dev/sdX4 (Important that it is made FAT16)
- syslinux /dev/sdX4 to make it bootable