Bootable USB flash drives

While installing pfsense on an Intel mini-ITX board, the "memstick" version failed to boot from two of three different brands of USB flash drives.  Even with the latest BIOS, booting failed with messages like "bootable device has not been detected".

I examined the drives' boot sectors with Microsoft's secinspect.exe. "EB" was the first byte on the working drive and "33" was the first byte on both failing drives. If I understand correctly, when "EB" is the first byte, it's a "Boot Sector" for floppy disks, while if "33" is the first byte, it's a "Master Boot Record" for hard disks.

I used HPUSBDisk.exe to format the drives as DOS Startup Disks using files from Win98Boot.zip, then used the normal dd procedure to transfer the memstick image. All three drives can now boot the pfsense installation code.