Bootable CD-ROM Format Specification

Version 1.0 Copyright  1994 Phoenix Technologies and IBM All Rights Reserved. Page 6
c. Boots from either the image specified in the Initial/Default Entry or from one of the other images listed
in Section Headers and Section Entries (See below) that follow the Initial/Default entry. The
selection of which image to boot from depends on Selection Criteria determined by the OEM (See
below).
System
(Unused)
Normal CD-ROM
Configuration
CD-ROM
Image
CD-ROM
Image
Descriptors
Volume
Multiple Boot-Image
Configuration
Booting Catalog
Initial/Default Entry
Boot Entry
Boot Entry
Boot Entry
Bootable
Disk Image
Bootable
Disk Image
System
(Unused)
Bootable
Disk Image
Set Terminator Volume Descriptor
Primary Volume Descriptor
Boot Record Volume Descriptor
Sector 0
Sector 16
Single Boot-Image
Configuration
Booting Catalog
CD-ROM
Image
CD-ROM
Image
Initial/Default Entry
Bootable
Disk Image
System
(Unused)
Set Terminator Volume
Primary Volume
Boot Record Volume
Sector 17
Figure 1. Three types of CD-ROM configuration:
1. The Normal CD-ROM configuration is not bootable, uses Root Directory and CD-ROM drivers to access CD-
ROM images.
2. A BIOS with Single Boot-Image capability accesses the Initial/Default Entry to access a single bootable disk
image. After loading the operating system, the system can revert to standard CD-ROM drivers and the Root
Directory to access CD-ROM images.
3. A BIOS with Multiple Boot-Image capability can access any one of a number of Bootable Disk Images listed
in the Booting Catalog. After loading the operating system, the system can access other items in the disk
image with standard INT 13 calls or return to normal access of CD-ROM images using CD-ROM drivers and
the Root Directory.
1.5 Definition of Terms
For the remainder of this document the following definitions apply:
Sector - Is a sector of data on a CD. This is in all cases 800 bytes.
Virtual Sector - Is a sector of data on an emulated device. This document only addresses 200 byte device (for
emulation)