http://syslinux.zytor.com/wiki/index.php/MEMDISK

The image file should contain a disk image, either a floppy disk or hard disk image. The disk image can be compressed with gzip if you have MEMDISK 2.03 or later.

For any other size, the image is assumed to be a hard disk image, and should typically have an MBR and a partition table. It may optionally have a DOSEMU geometry header; in which case the header is used to determine the C/H/S geometry of the disk. Otherwise, the geometry is determined by examining the partition table, so the entire image should be partitioned for proper operation (it may be divided between multiple partitions, however.)

documented on: 2007-10-21