master boot record format description initial program loader (IPL) partition entry

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Master Boot Record Format

Master Boot Record Format

We may partition the Hard Disk Drive into several logical drives which are generally assigned their own drive letter by DOS. Only one partition at a time can be marked as the active (or bootable) Partition.

Master Boot Record Format

The Master Boot Record has the limit of four entries in the Master Partition Table. However the location of Extended Master Boot Record can be obtained with the help of Master Boot Record that contains Extended Partition Tables, whose format is exactly the same as of the main Partition Table except there is no boot code.

In extended Master Boot Record, this space of 446 Bytes is normally reserved for the boot code and remains empty. All the 512Bytes of The Master Boot Record are Broken as follows, given in the Table:

Offset

Description

Size

000H

Initial Program Loader (IPL) , Executable Code (Provides very first booting to the Computer)

446 Bytes

1BEH

First Partition Entry (See Next Table)

16 Bytes

1CEH

Second Partition Entry

16 Bytes

1DEH

Third Partition Entry

16 Bytes

1EEH

Fourth Partition Entry

16 Bytes

1FEH

Executable Marker or Bootable Sector Signature or Magic Number (AAH 55H)

2 Bytes

Total = 512 Bytes

All the extended partitions should exist within the space reserved by the extended partition entry. Only two of the extended partitions are meant to be used, the first as a normal partition and the second as another extended partition if exists. Thus with the help of one Master Partition Table We can get the location of another Extended Master Partition Table next to it, if present.

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Data Recovery Book
 
Chapter 1 An Overview of Data Recovery
Chapter 2 Introduction of Hard Disks
Chapter 3 Logical Approach to Disks and OS
Chapter 4 Number Systems
Chapter 5 Introduction of C Programming
Chapter 6 Introduction to Computer Basics
Chapter 7 Necessary DOS Commands
Chapter 8 Disk-BIOS Functions and Interrupts Handling With C
Chapter 9 Handling Large Hard Disks
Chapter 10 Data Recovery From Corrupted Floppy
Chapter 11 Making Backups
Chapter 12 Reading and Modifying MBR with Programming
Chapter 13 Reading and Modifying DBR with Programming
Chapter 14 Programming for “Raw File” Recovery
Chapter 15 Programming for Data Wipers
Chapter 16 Developing more Utilities for Disks
Appendix Glossary of Data Recovery Terms
 
 

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