File System Format
Version 1.02 12/12/00 317
16.3 Media Formats
This section describes how booting from different types of removable media is handled. In general
the rules are consistent regardless of a media’s physical type and whether it is removable or not.

16.3.1 Removable Media

Removable media may contain a standard FAT-12, FAT-16, or FAT-32 file system. Legacy
1.44 MB floppy devices typically support a FAT-12 file system.
Booting from a removable media device can be accomplished the same way as any other boot. The
boot file path provided to the boot manager can consist of an EFI application image to load, or can
merely be the path to a removable media device. In the first case, the path clearly indicates the
image that is to be loaded. In the later case, the boot manager implements the policy to load the
default application image from the device.
For removable media to be bootable under EFI, it must be built in accordance with the rules layed
out in Section 17.4.1.1.

16.3.2 Diskette

EFI bootable diskettes follow the standard formatting conventions used on Intel architecture
personal computers. The diskette contains only a single partition that complies to the EFI file
system type. For diskettes to be bootable under EFI, it must be built in accordance with the rules
layed out in Section 17.4.1.1.
Since the EFI file system definition does not use the code in the first block of the diskette, it is
possible to boot Intel architecture personal computers using a diskette that is also formatted as an
EFI bootable removable media device. The inclusion of boot code for Intel architecture personal
computers is optional and not required by EFI.
Diskettes include the legacy 3 ½ inch diskette drives as well as the newer larger capacity removable
media drives such as an Iomega† Zip†, Fujitsu MO, or MKE LS-120/SuperDisk†.

16.3.3 Hard Drive

Hard drives may contain multiple partitions as defined in Section 16.2 on partition discovery. Any
partition on the hard drive may contain a file system that the EFI firmware recognizes. Images that
are to be booted must be stored under the EFI sub-directory as defined in Sections 16.1 and 16.2.
EFI code does not assume a fixed block size.
Since EFI firmware does not execute the MBR code and does not depend on the bootable flag field
in the partition entry the hard disk can still boot and function normally on an Intel architecture-
based personal computer.