Master Boot Record
The Master Boot Record is located at the physical beginning of a hard disk, editable using the Disk Editor. It consists of a master bootstrap loader code (446 bytes) and four subsequent, identically structured partition records. Finally, the hexadecimal signature 55AA completes a valid Master Boot Record.
The format of a partition record is as follows:
Offset |
Size |
Description |
0 |
8 bit |
A value of 80 designates an active partition. |
1 |
8 bit |
Partition start head |
2 |
8 bit |
Partition start sector (bits 0-5) |
3 |
8 bit |
Partition start track (bits 8,9 in start sector as bits 6,7) |
4 |
8 bit |
Operating system indicator, see below |
5 |
8 bit |
Partition end head |
6 |
8 bit |
Partition end sector (bits 0-5) |
7 |
8 bit |
Partition end track (bits 8,9 in end sector as bits 6,7) |
8 |
32 bit |
Sectors preceding partition |
C |
32 bit |
Length of partition in sectors |
Operating system indicators:
(hexadecimal, incomplete list)
00 |
Empty partition-table entry |
01 |
DOS 12-bit FAT |
04 |
DOS 16-bit FAT (up to 32M) |
05 |
DOS 3.3+ extended partition |
06 |
DOS 3.31+ Large File System (16-bit FAT, over 32M) |
07 |
Windows NT NTFS, OS/2 HPFS, Advanced Unix |
08 |
OS/2 v1.0-1.3, AIX bootable partition, SplitDrive |
09 |
AIX data partition |
0A |
OS/2 Boot Manager |
0B |
Windows 95 with 32-bit FAT |
0C |
Windows 95 with 32-bit FAT (using LBA-mode INT 13 extensions) |
0E |
Logical-block-addressable VFAT (same as 06, but using LBA-mode INT 13) |
0F |
Logical-block-addressable VFAT (same as 05, but using LBA-mode INT 13) |
17 |
Hidden NTFS partition |
1B |
Hidden Windows 95 FAT32 partition |
1C |
Hidden Windows 95 FAT32 partition (using LBA-mode INT 13 extensions) |
1E |
Hidden LBA VFAT partition |
42 |
Dynamic disk volume |
50 |
OnTrack Disk Manager, read-only partition |
51 |
OnTrack Disk Manager, read/write partition |
81 |
Linux |
82 |
Linux Swap partition, Solaris (Unix) |
83 |
Linux native file system (ext2fs/xiafs) |
84 |
Hibernation partition |
85 |
Linux EXT |
86 |
FAT 16 volume/stripe set (Windows NT) |
87 |
HPFS fault-tolerant mirrored partition, NTFS volume/stripe set |
A0 |
Laptop hibernation partition |
BE |
Solaris boot partition |
C0 |
DR-DOS/Novell DOS secured partition |
C6 |
Corrupted FAT 16 volume/stripe set (Windows NT) |
C7 |
Corrupted NTFS volume/stripe set |
DE |
DELL OEM partition |
F2 |
DOS 3.3+ secondary partition |
FE |
IBM OEM partition |