Int 13/AH=4Ah

Bootable CD-ROM - INITIATE DISK EMULATION

AH = 4Ah
AL = 00h
DS:SI -> specification packet (see #00281)

Return:
CF clear if successful
CF set on error (drive will not be in emulation mode)
AX = return codes

See Also: AH=48h - AX=4B00h - AH=4Ch - AH=4Dh


Format of Bootable CD-ROM Specification Packet:

Offset  Size    Description     (Table 00281)
00h    BYTE    size of packet in bytes (13h)
01h    BYTE    boot media type (see #00282)
02h    BYTE    drive number
00h floppy image
80h bootable hard disk
81h-FFh nonbootable or no emulation
03h    BYTE    CD-ROM controller number
04h    DWORD   Logical Block Address of disk image to emulate
08h    WORD    device specification (see also #00282)
(IDE) bit 0:
Drive is slave instead of master
(SCSI)  bits 7-0:
LUN and PUN
bits 15-8:
Bus number
0Ah    WORD    segment of 3K buffer for caching CD-ROM reads
0Ch    WORD    load segment for initial boot image
if 0000h, load at segment 07C0h
0Eh    WORD    number of 512-byte virtual sectors to load
(only valid for AH=4Ch)
10h    BYTE    low byte of cylinder count (for INT 13/AH=08h)
11h    BYTE    sector count, high bits of cylinder count (for INT 13/AH=08h)
12h    BYTE    head count (for INT 13/AH=08h)

See Also: #00283 - AH=08h


Bitfields for Bootable CD-ROM boot media type:

Bit(s)  Description     (Table 00282)
3-0    media type.
0000 no emulation.
0001 1.2M diskette.
0010 1.44M diskette.
0011 2.88M diskette.
0100 hard disk (drive C:).
Other reserved
5-4    reserved (0)
6      image contains ATAPI driver
7      image contains SCSI driver(s)

See Also: #00281

Category: Disk I/O Enhancements - Int 13h - B

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