I spend about an hour fiddling with this stuff yesterday, so I think it might be worth sharing my findings.

Using the below instructions, you can easily boot floopy and ISO images, such as the ones used for hardware diagnostics, right from GRUB or GRUB2 bootloader. That eliminates the need to write a CD or run around searching for a strange thing called a floppy drive (I hear nowadays the best person to ask is a musician).

1 Take 'memdisk' binary from syslinux (in Fedora: yum install syslinux) and put it to /boot (in Fedora: cp /usr/share/syslinux/memdisk /boot).

2 Put your floppy image or iso image to /boot. I am using Drive Fitness Test, and succeeded with both floppy (.IMG) and CD (.ISO) image.

3 This step depends of whether you have GRUB or GRUB2.

3.1 For GRUB, add the following to /boot/grub/grub.cfg:

# for ISO
title DFT iso image
      kernel /memdisk iso
      initrd /your-image.iso

# for floppy
title DFT floppy image
      kernel /memdisk
      initrd /your-image.img

3.2 For GRUB2, add this to /etc/grub.d/40_dft:

#!/bin/sh

cat << EOF
# for ISO
menuentry "DFT ISO image" {
      kernel16 /memdisk iso
      initrd16 /your-image.iso
}

# for floppy
menuentry "DFT floppy image" {
      kernel16 /memdisk
      initrd16 /your-image.img
}
EOF

4 For more info, see memdisk docs