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June 23, 2010 T13/2132-D Revision 3
Working Draft Enhanced Disk Drive - 4 (EDD-4) 27
7.3.6 Section Entry
Section entries shall follow Section Headers. The Section Entry identifies a single boot image. This entry shall
be the same as the Initial/Default entry with one exception: the reserved bytes at the send of the entry contain
selection criteria. The Section Header ID string identifies the section type, and the section type determines how
the selection criteria bytes are interpreted. An example would be a section titled "Languages", the 19 bytes could
then be language identifiers. If the system language were set to a language, such as French or Japanese, the
system may then boot using an image designed for that language. Table 19 describes a Section Entry.
If the 19 bytes provided for selection criteria are insufficient, Section Entry Extensions may be used. There are a
possible 30 bytes of information available per extension, see 7.2.6 for more information on Section Entry
Extensions.
Table 19 — Section Entry
Offset Type Description
00h Byte 88h - Header ID indicates a bootable image is present. 00h indicates that a non-bootable
image is present
01h Byte Boot media type. The boot image shall fall into one of three categories: Floppy, Hard Drive,
or None.
ID Description
0 No Emulation
1 1.2MB diskette
2 1.44MB diskette
3 2.88MB diskette
4 Hard Drive
05h-FFh Reserved
02-03h Word Load Segment. This shall be the segment address where the first emulated sector of data
is loaded into system memory. If this field cleared to zero, the default value of 07C0h shall
be used. For flat memory model architectures (such as Motorola), this is the memory
address divided by 10h.
04h Byte System type. This shall be a copy of byte 5 (system type) from the partition table found in
the boot image.
05hByteReserved
06h-07h Word Sector Count. This shall be the number of emulated sectors the system shall transfer from
the CD to the Load Segment address in system memory during the boot process. This field
will normally be set to 01h for 80x86 systems that are booting a floppy or hard drive image.
For No Emulation Booting, this field could potentially ask for 32MB of data to be loaded from
the CD or DVD before jumping to the boot address.
08h-0Bh DWord Load Block. This shall be the absolute start sector on the CD or DVD of the image to be
used in the emulation.
0Ch Byte Selection Criteria. The selection criteria determines the format for the selection criteria.
The following formats are currently assigned:
Type Description
00h No selection criteria
01h Language and version information (IBM format)
02h-FFh Reserved
0Dh-1Fh Byte Selection Criteria