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 |
|
|
