Try Plop Boot Manager: https://www.plop.at/en/bootmanagers.html https://www.plop.at/en/bootmanagers.html It can boot from a floppy or from a CD drive, and it l

Try Plop Boot Manager: https://www.plop.at/en/bootmanagers.html https://www.plop.at/en/bootmanagers.html It can boot from a floppy or from a CD drive, and it lets you chainload into a live usb even on old computers. I used it to boot from CD from a floppy in an old Pentium MMX and it worked great (although slow, of course)