BIOS Parameter Block (BPB)

##.d bpb bootbp
   BytesPerSector: 0200
SectorsPerCluster: 08
  ReservedSectors: 0001
     NumberOfFATs: 00
      RootEntries: 0200
     TotalSectors: 0000
  MediaDescriptor: f8
    SectorsPerFAT: 00fa
  SectorsPerTrack: 0020
            Heads: 0040
    HiddenSectors: 00000820
  BigTotalSectors: 0007cfe0

##.d bpb minimumbpb
   BytesPerSector: 0200
SectorsPerCluster: 01
  ReservedSectors: 0001
     NumberOfFATs: 00
      RootEntries: 0010
     TotalSectors: 0000
  MediaDescriptor: f0
    SectorsPerFAT: 0001
  SectorsPerTrack: 0009
            Heads: 0001
    HiddenSectors: 00000000
  BigTotalSectors: 003fffff

Notes:

Two system BPBs are locatable at symbols BootBPB and minimumBPB.

Others are pointed to from the Device Driver Request Packet for DosDevIOCtl command code 2 (build BPB).

See .D REQ Command for information on formatting Device Driver Request Packets.

For a description of the BPB fields, see the BIOS Parameter Block in the System Reference.