struc DPB                       ; Drive parameter block
 dpbDrive       db ?            ; Drive no. (0 = A, 1 = B, etc.)
 dpbUnit        db ?            ; Unit no. (for device driver)
 dpbSectorSize  dw ?            ; Sector size, in bytes
 dpbClusterMask db ?            ; Sectors per cluster - 1
 dpbClusterShift db ?           ; Sectors per cluster, as power of 2
 dpbFirstFAT    dw ?            ; First sector containing FAT
 dpbFATCount    db ?            ; No. of FATs
 dpbRootEntries dw ?            ; No. of root-directory entries
 dpbFirstSector dw ?            ; First sector of first cluster
 dpbMaxCluster  dw ?            ; No. of clusters on drive + 1
 dpbFATSize     dw ?            ; No. of sectors occupied by each FAT
 dpbDirSector   dw ?            ; First sector containing root directory
 dpbDriverAddr  dd ?            ; Addr of device driver's DeviceHeader
 dpbMedia       db ?            ; Media descriptor
 dpbFirstAccess db ?            ; 0FFh = medium in drive not accessed
 dpbNextDPB     dd ?            ; Address of next drive parameter block
 dpbNextFree    dw ?            ; Last allocated cluster
 dpbFreeCnt     dw ?            ; No. of free clusters (0FFFFh = unknown)
ends