| Offset | Description | Size in bytes |
| 0×0000 | Code Area | up to 446 |
| 0x018A | Four 9 byte primary partition table entries (IBM extensions) | 36 |
| 0x01B8 | Optional Disk signature | 4 |
| 0x01BC | Usually Nulls; 0×0000 | 2 |
| 0x01BE | Table of primary partitions (Four 16-byte entries, MBR Partition Table scheme only) | 64 |
| 0x01FE | 55h, MBR signature; 0xAA55 | 2 |
| 0x01FF | AAh | |
| MBR, total size: 446 + 64 + 2 = 512 |
| Offsets | Description | Size in bytes |
| 0×0000 - 0x01BD | Unused; normally filled with zero-bytes | 446 |
| 0x01BE - 0x01CD | Partition Table's First entry | 16 |
| 0x01CE - 0x01DD | Partition Table's Second entry | 16 |
| 0x01DE - 0x01FD | Unused, but should be filled with zero-bytes | 32 |
| 0x01FE | 55h Boot Record signature: 0xAA55 (AA55h) | 2 |
| 0x01FF | AAh | |
| Offset | Description | Size in bytes |
| 0×00 | Status (0×80 = bootable, 0×00 = non-bootable, other = malformed) | 1 |
| 0×01 | Cylinder-head-sector address of the first sector in the partition | 3 |
| 0×04 | Partition type | 1 |
| 0×05 | Cylinder-head-sector address of the last sector in the partition | 3 |
| 0×08 | Logical block address of the first sector in the partition | 4 |
| 0x0C | Length of the partition, in sectors | 4 |
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