| Offset (bytes) | Size (bytes) | Name |
|---|---|---|
| 0 | 3 | BS_jmpBoot |
| 3 | 8 | BS_OEMName |
| 11 | 2 | BPB_BytsPerSec |
| 13 | 1 | BPB_SecPerClus |
| 14 | 2 | BPB_RsvdSecCnt |
| 16 | 1 | BPB_NumFATs |
| 17 | 2 | BPB_RootEntCnt |
| 19 | 2 | BPB_TotSec16 |
| 21 | 1 | BPB_Media |
| 22 | 2 | BPB_FATSz16 |
| 24 | 2 | BPB_SecPerTrk |
| 26 | 2 | BPB_NumHeads |
| 28 | 4 | BPB_HiddSec |
| 32 | 4 | BPB_TotSec32 |
| 36 | 1 | BS_DrvNum |
| 37 | 1 | BS_Reserved1 |
| 38 | 1 | BS_BootSig |
| 39 | 4 | BS_VolID |
| 43 | 11 | BS_VolLab |
| 54 | 8 | BS_FilSysType |
Information:
BPB (BIOS Parameter Block), sometimes called
boot sector,reserved sector or0th sector is the first important data structure on a FAT VolumeBPB Size
BPB_RsvdSecCnt * BPB_BytsPerSecBS_jmpBoot
Offset: 0 bytes
Size: 3 bytes
Jump instruction to boot code. This field has two allowed forms:
jmpBoot[0] = 0xEB, jmpBoot[1] = 0x??, jmpBoot[2] = 0x90and
jmpBoot[0] = 0xE9, jmpBoot[1] = 0x??, jmpBoot[2] = 0x??0x?? indicates that any 8-bit value is allowed in that byte. What this forms is a three-byte Intel x86 unconditional branch (jump) instruction that jumps to the start of the operating system bootstrap code. This code typically occupies the rest of sector 0 of the volume following the BPB and possibly other sectors. Either of these forms is acceptable. JmpBoot[0] = 0xEB is the more frequently used format.