附件2-6：BM可引导光盘格式 Offset Type Description 0 Byte Packet Size.currently 13 Byte Boot media type.This specifies what media the boot image is intended to emulate in bits 0-3.Bits 6 and 7 are specific to the type of system. Bits 0-3 count as follows: 0-No Emulation 1-1.2 meg diskette 2-1.44 meg diskette 3-2.88 meg diskette 4-Hard Disk (drive C) 5-F-Reserved.invalid at this time bits 4-5-Reserved,must be 0 bit 6-Image contains an ATAPI driver,bytes 8&9 refer to IDE interface bit 7-Image contains SCSI drivers,bytes 8 9 refer to SCSI interface 22 Byte Drive Number.This is the drive number on which emulation is being initiated or terminated.This must be 0 for a floppy image,80 for a bootable hard disk,and 81-FF for a"non-bootable”ors“no emulation”drive. 3 Byte Controller Index.This specifies the controller number of the specified CD drive. 4-7 Dword Logical Block Address for the disk image to be emulated. 8-9 Word Device Specification.For SCSI controllers byte 8 is the LUN and PUN of the CD Drive,byte 9 is the Bus number.For IDE controllers the low order bit of byte 8 specifies master/slave device.0=master. A-B Word User Buffer Segment.If this field is non-zero it specifies the segment of a user supplied 3k buffer for caching CD reads.This buffer will begin at Segment:0. C-D Word Load Segment.This is the load address for the initial boot image.If this value is 0 the system will use the traditional segment of 7C0.If this value is non-zero the system will use the specified address.This field is only valid for fimction 4C E-F Word Sector Count.This is the number of virtual sectors the system will store at Load Segment during the initial boot procedure.This field is only valid for fimction 4C 10 Byte Bits 0-7 of the cylinder count.This should match the value returned in CH when INT 13 function 08 is invoked. 11 Byte This is the value returned in the CL register when INT 13 function 08 is invoked. Bits 0-5 are the sector count.Bits 6 and 7 are the high order 2 bits of the cylinder count. 2 Byte This is the head count,it should match the value in DH when INT 13 Function 08 is invoked Figure 9.-Specification Packet Version 1.0 Copyright1994 Phoenix Technologies and IBM All Rights Reserved. Page 16附件2-6：IBM可引导光盘格式 Version 1.0 Copyright  1994 Phoenix Technologies and IBM All Rights Reserved. Page 16 Figure 9. - Specification Packet Offset Offset Type Type Description Description Description Description 0 Byte Packet Size, currently 13 1 Byte Boot media type. This specifies what media the boot image is intended to emulate in bits 0-3. Bits 6 and 7 are specific to the type of system. Bits 0-3 count as follows: 0 - No Emulation 1 - 1.2 meg diskette 2 -1.44 meg diskette 3 -2.88 meg diskette 4 -Hard Disk (drive C) 5-F-Reserved, invalid at this time bits 4-5 - Reserved, must be 0 bit 6 - Image contains an ATAPI driver, bytes 8 & 9 refer to IDE interface bit 7 - Image contains SCSI drivers, bytes 8 & 9 refer to SCSI interface 2 Byte Drive Number. This is the drive number on which emulation is being initiated or terminated. This must be 0 for a floppy image, 80 for a bootable hard disk, and 81-FF for a “non-bootable” or “no emulation” drive. 3 Byte Controller Index. This specifies the controller number of the specified CD drive. 4-7 Dword Logical Block Address for the disk image to be emulated. 8-9 Word Device Specification. For SCSI controllers byte 8 is the LUN and PUN of the CD Drive, byte 9 is the Bus number. For IDE controllers the low order bit of byte 8 specifies master/slave device, 0 = master. A-B Word User Buffer Segment. If this field is non-zero it specifies the segment of a user supplied 3k buffer for caching CD reads. This buffer will begin at Segment:0. C-D Word Load Segment. This is the load address for the initial boot image. If this value is 0 the system will use the traditional segment of 7C0. If this value is non-zero the system will use the specified address. This field is only valid for function 4C E-F Word Sector Count. This is the number of virtual sectors the system will store at Load Segment during the initial boot procedure. This field is only valid for function 4C 10 Byte Bits 0-7 of the cylinder count. This should match the value returned in CH when INT 13 function 08 is invoked. 11 Byte This is the value returned in the CL register when INT 13 function 08 is invoked. Bits 0-5 are the sector count. Bits 6 and 7 are the high order 2 bits of the cylinder count. 12 Byte This is the head count, it should match the value in DH when INT 13 Function 08 is invoked