Network, Computer and Programming Resources
Boot Sector and BPB Structure[Fat32]-> BPB_RootClus [Offset=44, Size=4]Boot Sector and BPB Structure[Fat32]-> BS_BootSig [Offset=66, Size=1]Boot Sector and BPB Structure[Fat32]-> BS_DrvNum [Offset=64, Size=1]Boot Sector and BPB Structure[Fat32]-> BS_FilSysType [Offset=82, Size=8]Boot Sector and BPB Structure[Fat32]-> BS_Reserved1 [Offset=65, Size=1]Boot Sector and BPB Structure[Fat32]-> BS_VolID [Offset=67, Size=4]Boot Sector and BPB Structure[Fat32]-> BS_VolLab [Offset=71, Size=11]Boot Sector and BPB Structure-> BPB_BytsPerSec [Offset=11, Size=2]Boot Sector and BPB Structure-> BPB_FATSz16 [Offset=22, Size=2]Boot Sector and BPB Structure-> BPB_HiddSec [Offset=28, Size=4]Boot Sector and BPB Structure-> BPB_Media [Offset=21, Size=1]Boot Sector and BPB Structure-> BPB_NumFATs [Offset=16, Size=1]
Fat32 - Boot Sector and BPB Structure-> BPB_NumFATs [Offset=16, Size=1]
The count of FAT data structures on the volume. This field should always contain the value 2 for any FAT volume of any type. Although any value greater than or equal to 1 is perfectly valid, many software programs and a few operating systems’ FAT file system drivers may not function properly if the value is something other than 2. All Microsoft file system drivers will support a value other than 2, but it is still highly recommended that no value other than 2 be used in this field. The reason the standard value for this field is 2 is to provide redundancy for the FAT data structure so that if a sector goes bad in one of the FATs, that data is not lost because it is duplicated in the other FAT. On non-disk-based media, such as FLASH memory cards, where such redundancy is a useless feature, a value of 1 may be used to save the space that a second copy of the FAT uses, but some FAT file system drivers might not recognize such a volume properly.