Block diagram
MBR (Master Boot Record) partition table is a traditional way of MS-DOS to partition larger hard disc drives into distinct partitions.
This table is stored in the end of the boot sector (first sector) of the drive, after the bootstrap code. Original DOS 2.0 specification allowed only 4 partitions per disc, but DOS 3.2 introduced concept of "extended partitions", which work as nested extra "boot records" which are pointed to by original ("primary") partitions in MBR.
This page hosts a formal specification of MBR (Master Boot Record) partition table using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
meta:
id: mbr_partition_table
title: MBR (Master Boot Record) partition table
xref:
forensicswiki: master_boot_record
justsolve: Master_Boot_Record
wikidata: Q624752
tags:
- dos
license: CC0-1.0
endian: le
doc: |
MBR (Master Boot Record) partition table is a traditional way of
MS-DOS to partition larger hard disc drives into distinct
partitions.
This table is stored in the end of the boot sector (first sector) of
the drive, after the bootstrap code. Original DOS 2.0 specification
allowed only 4 partitions per disc, but DOS 3.2 introduced concept
of "extended partitions", which work as nested extra "boot records"
which are pointed to by original ("primary") partitions in MBR.
seq:
- id: bootstrap_code
size: 0x1be
- id: partitions
type: partition_entry
repeat: expr
repeat-expr: 4
- id: boot_signature
contents: [0x55, 0xaa]
types:
partition_entry:
seq:
- id: status
type: u1
- id: chs_start
type: chs
- id: partition_type
type: u1
- id: chs_end
type: chs
- id: lba_start
type: u4
- id: num_sectors
type: u4
chs:
seq:
- id: head
type: u1
- id: b2
type: u1
- id: b3
type: u1
instances:
sector:
value: 'b2 & 0b111111'
cylinder:
value: 'b3 + ((b2 & 0b11000000) << 2)'