how identify FAT16 or FAT32 from boot sector

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Is there a way to identify the type of a FAT partition (if it is 16 or 32) only by reading its boot sector?

thanks.

2

There are 2 best solutions below

3
tofro On

Not by reading the boot sector - You need to look into the file system itself.

Find the number of clusters. The file system subtype can be determined by this number:

less than 4086: FAT12

equal or more than 4086: FAT16

more than 65525: FAT32

0
ecm On

If the sectors per FAT word in the FAT12/FAT16 BPB is zero, it is FAT32. (Regardless of the actual FAT size, FAT32 uses the EBPB's sectors per FAT dword.) Likewise, if the number of root directory entries word is zero, it is FAT32.