Reading DBR of Floppy and Small Volumes Extended DOS Boot Record Format for FAT12 and FAT16 Information

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Reading DBR of Floppy and Small Volumes

The table given next represents the format of DBR of Floppy. The Partitions having FAT12 File System or FAT16 File system with less than or equal to 32MB size also have the similar DBR format.

DOS Boot Record  Format for FAT12 and FAT16

Offset

Size

Field

Default

00H

3

Jump

E9 XX XX or EB XX 90 (Hex)

03H

8

OEM ID

MSWIN4.0

 

BIOS Parameter Block

0BH

2

Bytes Per Sector

512

0DH

1

Sectors Per Cluster

(See Table of Cluster Sizes )

0EH

2

Reserved Sectors

1

10H

1

Number of FATs

2

11H

2

Number of Root Directory Entries

512/544

13H

2

Total Sectors in Logical Volume (Small, For Logical Volume Size Less than or Equal to 32 MB)

0

15H

1

Media Descriptor Byte

(See the Table of Media Descriptors)

16H

2

Number of Sectors Per FAT

Must Be Calculated

 

(End of BIOS Parameter Block)

18H

2

Sectors Per Track

Depends on Hard Disk, Usually 63

1AH

2

Number of Heads

Depends on Hard Disk

1CH

4

Number of Hidden Sectors

 

20H

4

Total Sectors in Volume (Large, Logical volume size greater than 32MB)

Size of the partition in terms of Sectors

 

Extended Boot Record Information (DOS 4.0 and Later)

24H

1

Physical Drive Number

80H

25H

1

Current Head                                    

0

26H

1

Extended Boot Signature Record

for WinNT, 28H else 29H

27H

4

Volume Serial Number
(32 – bit Binary Volume ID)

Random

2BH

11

Volume Label                                  

 1

36H

8

File System ID

FAT12, FAT16

 Total

62

 

 

 

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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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