Bootable CD-ROM Format Specification

6.3 INT 13 Function 4C - Initiate Disk Emulation & Boot

This function takes a pointer to the Specification Packet and uses it to reboot the system from scratch. This function

only returns if the supplied packet does not contain a pointer to a bootable disk image.

Registers at call:

AH = 4C

AL = 00

DS:SI - Specification Packet as defined in figure 9

Registers on return

AX - Return Codes

CF - Set if system failed to boot

CF Clear will not occur because when this function succeeds no return is generated.

6.4 INT 13 Function 4D - Return Boot Catalog

This function takes a drive number in DL, a command packet in DS:SI, and returns the requested number of sectors

from the boot catalog.

Registers at call:

AH = 4D

AL = 00

DS:SI - Pointer to command packet as defined in figure 8

Registers on return:

AX - Return Codes

CF - Clear if successful

CF - Set if device is not an emulated CD, or command packet is out of bounds

Offset Type Description

0 Byte Packet Size in bytes, currently 8

1 Byte Sector count. Number of sectors in the boot catalog to transfer

2-5 Dword Pointer to the buffer where the boot catalog will be moved

6-7 Word Beginning sector to transfer. This number is relative to the start of the boot

catalog. The initial call to INT 13 Function 4D should always set this value to 0.

Figure 8 - Command Packet