BIOS parameter block
The BIOS Parameter Block (BPB) describes the physical structure of a hard disk and some file system-relevant structures on the data carrier. It is part of the boating sector . The BPB is therefore a data structure that is stored in the beginning area of a data carrier.
File systems that use the BIOS parameter block are, for example, FAT12 , FAT16 , FAT32 , HPFS and NTFS .
Structure of a DOS 3.31 BIOS parameter block (FAT12 / FAT16)
| field | Bytes | Hex offset |
|---|---|---|
| BytesPerSector | 2 |
0x000B
|
| SectorsPerCluster | 1 |
0x000D
|
| ReservedSectors | 2 |
0x000E
|
| FatCopies | 1 |
0x0010
|
| RootDirEntries | 2 |
0x0011
|
| NumSectors | 2 |
0x0013
|
| MediaType | 1 |
0x0015
|
| SectorsPerFAT | 2 |
0x0016
|
| SectorsPerTrack | 2 |
0x0018
|
| NumberOfHeads | 2 |
0x001A
|
| HiddenSectors | 4th |
0x001C
|
| SectorsBig | 4th |
0x0020
|
For example, the ReservedSectors field describes the number of sectors required for the boot sector and other (file system or operating system-specific) information at the beginning of the data medium or partition.
literature
- Jonathan de Boyne Pollard: All about BIOS Parameter Blocks . In: Frequently Given Answers . Retrieved February 27, 2019. - Description of BPBs as used by DOS 2.0 to 7.0.
- Ken W. Christopher, Barry A. Feigenbaum, & Shon O. Saliga: 9: DOS Disk Usage . In: Developing applications using DOS . Wiley, 1990, ISBN 0-471-52231-7 . - Mapping of BPB fields to DOS versions that introduced them. The DOS versions 2.0 to 4.0 are discussed.
- Carl Townsend: 4: Disk organization and management . In: Advanced MS-DOS Expert Techniques for programmers . Howard M. Sams, 1989, ISBN 0-672-22667-7 .
- Microsoft: Chapter 10 - Disks and File Systems . In: Microsoft Windows 98 Resource Kit . Retrieved December 13, 2010. - Microsoft is documenting BPB 4.0 and BPB 7.0, which contains additional fields
- Microsoft: Chapter 32 - Disk Concepts and Troubleshooting . In: Microsoft Windows 2000 Professional Resource Kit . Retrieved December 13, 2010. - Microsoft documents extended BPSs for FAT16, FAT32, and NTFS file systems.
- Microsoft: How NTFS Works . In: Microsoft Windows Server 2003 NTFS Technical Reference . Retrieved December 13, 2010. - BPB extensions for NTFS file systems on Windows Server 2003.