Offset |
Size |
Description |
Comments |
0 (0x00) |
3 |
JumpBoot |
0xEB7690 |
3 (0x03) |
8 |
FileSystemName |
"EXFAT" |
11 (0x0B) |
53 |
MustBeZero |
|
64 (0x40) |
8 |
PartitionOffset |
In sectors; if 0, shall be ignored |
72 (0x48) |
8 |
VolumeLength |
Size of exFAT volume in sectors |
80 (0x50) |
4 |
FatOffset |
In sectors |
84 (0x54) |
4 |
FatLength |
In sectors. May exceed the required space in order to align the second FAT |
88 (0x58) |
4 |
ClusterHeapOffset |
In sectors |
92 (0x5C) |
4 |
ClusterCount |
2^32-11 is the maximum number of clusters could be described |
96 (0x60) |
4 |
RootDirectoryCluster |
|
100 (0x64) |
4 |
VolumeSerialNumber |
|
104 (0x68) |
2 |
FileSystemRevision |
as MAJOR.minor, major revision is high byte, minor is low byte; currently 01.00 |
106 (0x6A) |
2 |
VolumeFlags *
Offset |
Size |
Field |
0 |
1 |
ActiveFat
0 - First FAT and Allocation Bitmap are active, 1- Second.
|
1 |
1 |
VolumeDirty
(0-clean, 1-dirty)
|
2 |
1 |
MediaFailure
(0 – no failures reported or they already marked as BAD clusters)
1- some read/write operations failed)
|
3 |
1 |
ClearToZero
(no meaning) |
4 |
12 |
Reserved
(no meaning) |
|
|
108 (0x6C) |
1 |
BytesPerSectorShift |
Power of 2. Minimum 9 (512 bytes per sector), maximum 12 (4096 bytes per sector) |
109 (0x6D) |
1 |
SectorsPerCluster Shift |
Power of 2. Minimum 0 (1 sector per cluster), maximum 25 – BytesPerSectorShift, so max cluster size is 32 MB |
110 (0x6E) |
1 |
NumberOfFats |
2 is for TexFAT only |
111 (0x6F) |
1 |
DriveSelect |
Extended INT 13h drive number; typically 0x80 |
112 (0x70) |
1 |
PercentInUse |
0..100 – percentage of allocated clusters rounded down to the integer
0xFF – percentage is not available
|
113 (0x71) |
7 |
Reserved |
|
120 (0x78) |
390 |
BootCode |
|
510 (0x1FE) |
2 |
BootSignature |
0xAA55
|
512 (0x200) |
2^BytesPerSectorShift - 512 |
ExcessSpace |
Not used
|
