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Content and content of the FAT32 BPB FAT12/16 address 0x36 is exactly the same as before, starting at offset 0x36, differ in their content, specific content depends on the type of FAT12/16 FAT or FAT32, this ensures that contains a complete FAT12/16 or FAT32 BPB in the boot sector of the contents, do so in order to achieve the best compatibility, but also to ensure that all of the FAT file system driver and the driver can correctly identify different The FAT format and make them work well because they contain the entire contents of the existing offset 36 from the beginning of the beginning of the content FAT12/FAT16 different from FAT32, the following two tables listed in the following table for the content FAT12/FAT16 The following table shows the contents of the FAT32
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Name
|
offset
|
Length
|
Description
|
|
|
（byte）
|
（byte）
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|
|
BPB_FATSz32
|
0x24
|
4
|
A number of sectors occupied by the FAT table, this field is FAT32 unique, while
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BPB_FATSz16 must be 0
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BPB_Flags
|
0x28
|
2
|
This field FAT32 unique.
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|
|
|
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Bits0-3: not less than FAT (active FAT) number 0, only
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|
|
In the Mirror (mirrorig) ban is valid.
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|
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Bits 4-6: Reserved
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Bits 7: 0 indicates mirrored in real time to all FAT FAT table
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|
|
|
1 shows only one active FAT table. This table is
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|
|
|
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Specify that Bits0-3
|
|
|
|
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Bits8-15: Reserved
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BPB_FSVer
|
0x2A
|
2
|
This field is FAT32 unique,
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|
|
|
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FAT32 high as the major version number, the lower is the minor version number, this version
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|
|
|
|
Number is higher for future versions of FAT consideration, assuming the current operation
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|
|
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System only supports FAT32 version number is 0.0. Then the operating system
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Detects this field is not 0, it will ignore the FAT volume, because it's version
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|
|
|
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The number than the layout of the system can support higher
|
|
|
|
|
|
|
BPB_RootClus
|
0x2C
|
4
|
Root directory where the first cluster in generally the value of 2, but not necessarily
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|
|
|
Shall be 2
|
|
|
|
|
Disk Utility when changing the position of the root directory, you must find ways to make the disk first
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|
|
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Non-bad cluster as the root directory of the first cluster (for example, the second cluster, unless it
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|
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|
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Has been marked as bad clusters), in this case, if the field is exactly zero
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|
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|
|
Then the disk detection tools can easily find the location of the root directory where clusters
|
|
|
|
|
|
|
BPB_FSIfo
|
0x30
|
2
|
FAT32 volumes FSINFO number of sectors reserved area occupied structure, usually
|
|
|
|
|
1
|
|
|
|
|
There will be a backup in the Backup Boot FSINFO in, but the backup
|
|
|
|
|
Copies only update one pointer, that either the master boot record or
|
|
|
|
|
Backup boot records are pointing to the same structure FSINFO
|
|
BPB__BkBootSec
|
0x32
|
2
|
If not 0, which means that backup data in the reserved area boot record share of fans
|
|
|
|
|
Region number is usually 6. While not recommend the use of other values than 6
|
|
BPB_Reserved
|
0x34
|
12
|
FAT extensions for future use, FAT32. This field is filled with 0
|
|
BS_DrvNum
|
0x40
|
1
|
FAT12/16 and definition of the same, but the two are not located in the boot sector
|
|
|
|
|
Same position as it
|
|
|
|
|
|
|
BS_Reserved1
|
0x41
|
1
|
FAT12/16 and definition of the same, but the two are not located in the boot sector
|
|
|
|
|
Same position as it
|
|
|
|
|
|
|
BS_BootSig
|
0x42
|
1
|
FAT12/16 and definition of the same, but the two are not located in the boot sector
|
|
|
|
|
Same position as it
|
|
|
|
|
|
|
BS_VolID
|
0x43
|
4
|
FAT12/16 and definition of the same, but the two are not located in the boot sector
|
|
|
|
|
Same position as it
|
|
|
|
|
|
|
BS_FilSysType
|
0x47
|
11
|
FAT12/16 and definition of the same, but the two are not located in the boot sector
|
|
|
|
|
Same position as it
|
|
|
|
|
|
|
BS_FilSysType
|
0x52
|
8
|
Usually set to "FAT32", please refer to this part FAT12/16 Chen
|
|
|
|
|
Above.
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