FAT32 DOS Boot Record Format |
Offset |
Description |
Size |
00H |
Jump Code + NOP |
3 Bytes |
03H |
OEM Name and Version |
8 Bytes |
0BH |
Bytes Per Sector |
2 Bytes |
0DH |
Sectors Per Cluster |
1 Byte |
0EH |
Reserved Sectors |
2 Bytes |
10H |
Number of Copies of FAT |
1 Byte |
11H |
Maximum Root Directory Entries (but Not Available for FAT32) |
2 Bytes |
13H |
Number of Sectors in Partition Smaller than 32MB (Therefore Not Available for FAT32) |
2 Bytes |
15H |
Media Descriptor (F8H for Hard Disks) |
1 Byte |
16H |
Sectors Per FAT (In Older FAT Systems and Not Available for FAT32) |
2 Bytes |
18H |
Sectors Per Track |
2 Bytes |
1AH |
Number of Heads |
2 Bytes |
1CH |
Number of Hidden Sectors in Partition |
4 Bytes |
20H |
Number of Sectors in Partition |
4 Bytes |
24H |
Number of Sectors Per FAT |
4 Bytes |
28H |
Flags (Bits 0-4 Indicate Active FAT Copy) (Bit 7 Indicates whether FAT Mirroring is Enabled or Disabled <Clear is Enabled>) (If FAT Mirroring is Disabled, the FAT Information is only written to the copy indicated by bits 0-4) |
2 Bytes |
2AH |
Version of FAT32 Drive (High Byte = Major Version, Low Byte = Minor Version) |
2 Bytes |
2CH |
Cluster Number of the Start of the Root Directory |
4 Bytes |
30H |
Sector Number of the File System Information Sector (Referenced from the Start of the Partition) |
2 Bytes |
32H |
Sector Number of the Backup Boot Sector (Referenced from the Start of the Partition) |
2 Bytes |
34H |
Reserved |
12 Bytes |
40H |
Logical Drive Number of Partition |
1 Byte |
41H |
Unused (Could be High Byte of Previous Entry) |
1 Byte |
42H |
Extended Signature (29H) |
1 Byte |
43H |
Serial Number or 32 – Bit Binary ID of Partition
(Binary ID of 32 Bits provided by the OS itself) |
4 Bytes |
47H |
Volume Name of Partition |
11 Bytes |
52H |
FAT Name (FAT32 in this case) |
8 Bytes |
5AH |
Executable Code |
420 Bytes |
1FEH |
Executable Marker or Magic Number (AAH 55H) |
2 Bytes |
