Boot Region0FAT RegionSector #24Data RegionFAT Offset + FAT Length × Number of FATS
SectionContentsOffset (sector number)Size (in sectors)
Main Boot RegionBoot sector01
Extended Boot Sectors18
OEM Parameters91
Reserved Sectors101
Boot checksum111
Backup Boot RegionBoot sector121
Extended Boot Sectors138
OEM Parameters211
Reserved sectors221
Boot checksum231
FAT RegionFAT Alignment24FATOffset - 24
First FATFATOffsetFATLength
Second FATFATOffset + FATLengthFATLength * (NumberOfFATs - 1)
Data RegionCluster Heap AlignmentFATOffset + FATLength * NumberOfFATsClusterHeapOffset - (FATOffset + FATLength * NumberOfFATs)
Cluster HeapClusterheapOffsetClusterCount * 2SectorsPerClusterShift
Excess Space (to end of partition or disk)ClusterheapOffset + ClusterCount * 2SectorsPerClusterShiftVolumeLength - (ClusterHeapOffset + ClusterCount * 2SectorsPerClusterShift)

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