Guide sector

master boot sector

0 hard disk cylinder, head 0, 1 sector is called the master boot record, the MBR also called the master boot record, the record occupies 512 bytes when it is used for the hard disk to the system control to the user-specified registered an operating system partition in the partition table. MBR content is written in the sector by the hard disk partition software partition, MBR not belong to any one operating system, with the operating system it does not vary, even if different, will not MBR entraining properties of the operating system, has a common guide It features. But there are some software installation or multi-boot function of LINUX LILO when possible rewrite it, it is first loaded into memory for all operating systems and play a role, then it will hand over control of the main activities of the operating system partition.

MBR members

1. Master boot program code bytes representing 446

2. 3. The disk signature the DPT hard disk partition table, accounting for 64 bytes 4 the main end flag 55AAH hard disk boot sector of the master boot program code starting from byte offset 446 to offset 0000H 01BDH end; master boot program code includes performing a short code. When starting the PC, the hardware system of the first test, after successfully entered bootloader INT 19H; The system then reads disk cylinder 0, head 0, the content of the master boot sector MBR sector 1 into the memory cell designated 0: 7C00 first start address of area, and block execution MBR.

MBR function

1. Scans the partition table to find the active partition; 2. Looking start sector of the active partition; 3. The boot sector of the active partition into memory; 4. Run boot sector code execution. If the master boot code does not perform these functions, the system displays the following error message

Invalid partition table Error loading operating system Missing operating system

partition boot sector

partition boot sector, also known as DBR, the content is written by the fORMAT sector advanced formatting commands, DBR is loaded by the MBR hard disk block. After DBR loaded into memory, i.e., the guide block is started, its main function is to complete the operating system bootstrap and control to the operating system. Each partition has a DBR boot sector, but only to be set active partition MBR will be loaded into memory to run.

DBR members

1. Jump instruction uses 3 bytes of the jump instruction will jump to the boot code.2. Vendor identification and DOS version number, the portion of a total of 8 bytes. 3. BPB (BIOS Parameter Block, BIOS parameter block). 4. Operating system boot process. 5. Word end flag, the end flag occupies 2 bytes, the contents of which is in addition to AA55 DBR portion 5 beyond the end flag fixed word, the remaining four portions are uncertain, the contents of the format used with the changes in the operating system version and logical disk parameters hard disk changes.

FAT32 partition boot sector

the first sector of the boot sector is FAT32 file system, also referred to as a DBR sectors.

BPB FAT volume expansion and BPB fields:

byte offset field length and the domain defined

0x03 8 bytes OEM number

< p> 0x0B 2 bytes bytes per sector

0x0D 1 byte number of sectors per cluster

0x0E 2-byte number of reserved sectors

FAT table number 0x10 1 byte

0x11 2 byte number of the directory entry

0x13 2 bytes total number of sectors

0x15 1 byte medium described Fu

0x16 2 bytes per FAT sector number

0x18 2 bytes the number of sectors per track

Guide sector

0x1A 2 bytes head

0x1C 4 bytes special hidden sector number

0x20 4 bytes total number of sectors

0x24 4-byte number of sectors per FAT table size

0x28 2-byte tag, FAT table to determine mode of operation, if only a bit7 is a FAT table is active, while the bit0 ~ bit3 be described, or mirror images of the two FAT

0x2A 2-byte version number

0x2C 4 bytes root directory starting cluster number, cluster typically 2

0x30 2 bytes FSINFO sector where, usually located sector 1

0x32 2 bytes backup boot sector position, a sector typically 6


0xFE 2-byte signature value "55AA "

NTFS partition boot sector

to NTFS partitions, a partition boot sector DBR occupies only one sector, and in the last sector of the partition is made a backup; NTFS boot sector of the boot is completed, and the parameter definitions partition, boot sector is not a sufficient condition for the partition NTFS partition, which requires the system to be recorded as the MFT normal $ MFT like normal access to the partition.

BPB NTFS volume expansion and BPB fields:

byte offset field length and the domain defined

0x03 2 bytes OEM name

< p> 0x0B 2 bytes sector byte

0x0D 1 byte number of sectors per cluster

0x0E 2-byte reserved sector

0x10 4 unused bytes

0x15 1 byte media descriptor

0x16 2 unused bytes

0x18 2 bytes the number of sectors per track

0x1A 2 bytes head

0x1C 4 bytes hidden sector

0x20 4 bytes not used NTFS

0x24 4 bytes NTFS is not used

0x28 8 bytes total number of sectors

0x30 8 bytes of the file start cluster number $ MFT

0x38 8-byte file $ MFT backup cluster number

0x40 4 bytes of each segment representing a cluster file record number

0x44 4 bytes of each index block representing the number of clusters

0x48 8 bytes volume serial number

0x50 4-byte checksum

0x54 426 bytes of the boot code

0x1F 2-byte signature value "55AA"

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