BIOS parameter block

BIOS parameter block (BPB) is a description of the physical medium (hard disk or floppy) that might be stored in a partition's Volume Boot Record. Filesystems with a BIOS parameter block include FAT16, FAT32, HPFS, and NTFS. ECMA-107 or ISO/IEC 9293 (which describes FAT as for flexible/floppy and optical disk cartridges) also describes this as an FDC Descriptor or an FDC Extended Descriptor.

FAT12/16 BPB:

Further reading

* cite web
url=http://homepages.tesco.net./~J.deBoynePollard/FGA/bios-parameter-block.html
author=Jonathan de Boyne Pollard
title=All about BIOS Parameter Blocks
work=Frequently Given Answers — a description of BPBs, from version 2.0 to version 7.0
* cite book
title=Developing applications using DOS
chapter=9: DOS Disk Usage
author=Ken W. Christopher, Barry A. Feigenbaum, & Shon O. Saliga
publisher=Wiley
year=1990
id=ISBN 0-471-52231-7 — In the "processing the BIOS parameter block" section the authors describe the evolution of the BIOS parameter block from the MS-DOS version 2.0 BPB to the PC-DOS version 4.0 BPB, and label each field with the DOS version that introduced it.
* cite book
title=Advanced MS-DOS Expert Techniques for programmers
author=Carl Townsend
chapter=4: Disk organization and management
publisher=Howard M. Sams
year=1989
id=ISBN 0-672-22667-7 — Figure 4.3 contains a diagram of the version 4.0 BPB and states that the layout of BPBs "is not defined by Microsoft and can vary with different vendors". At the time that the book was written, this was true. Microsoft first publicly documented the BPB structure in the OS/2 Developers' Toolkit.
* cite web
author=Alex Verstak
year=1998-03-10
url=http://averstak.tripod.com/fatdox/bootsec.htm
title=FAT Boot Sector — Verstak reverse engineers the BIOS parameter block. The paper contains several errors. One such is its statement that "the presence of the EBPB in FAT32 is not documented by Microsoft". See:
** cite web
url=http://www.microsoft.com/technet/archive/win98/reskit/part2/wrkc10.mspx
author=Microsoft
work=Microsoft Windows 98 Resource Kit
title=Chapter 10 - Disks and File Systems — Microsoft documents a version 4.0 BPB and a new "FAT32 BIOS Parameter Block (BPB)" (a version 7.0 BPB) for DOS-Windows 98 that is "larger than a standard BPB", has an "identical structure to a standard BPB", but that also "includes several extra fields".
** cite web
url=http://www.microsoft.com/technet/prodtechnol/Windows2000Pro/reskit/part7/proch32.mspx
author=Microsoft
work=Microsoft Windows 2000 Professional Resource Kit
title=Chapter 32 - Disk Concepts and Troubleshooting — Microsoft documents extended BPBs on both FAT16 and FAT32 volumes. It also documents BPBs on NTFS volumes.
* cite web
url=http://technet2.microsoft.com/WindowsServer/en/Library/8cc5891d-bf8e-4164-862d-dac5418c59481033.mspx#w2k3tr_ntfs_how_dhao
author=Microsoft
work=Microsoft Windows Server 2003 NTFS Technical Reference
title=How NTFS Works — The table "BPB and Extended BPB Fields on NTFS Volumes" describes BPBs on NTFS volumes. The descriptions of several fields contradict those given in the Windows 2000 Resource Kit.

ee also

*Master boot record