Format of Get_ExtDPB data buffer: Offset Size Description ) 00h WORD (call) length of following data (003Dh) 02h 61 BYTEs (ret) drive parameter block (DPB) (see #01787) Format of Extended Drive Parameter Block: Offset Size Description ) 00h 24 BYTEs standard DOS 4+ DPB 18h BYTE "dpb_flags" (undocumented) FFh force media check 19h DWORD pointer to next DPB (see note) 1Dh WORD cluster at which to start search for free space when writing, usually the last cluster allocated 1Fh WORD number of free clusters on drive, FFFFh = unknown 21h WORD high word of free cluster count 23h WORD active FAT/mirroring bit 7: do not mirror active FAT to inactive FATs bits 6-4: reserved (0) bits 3-0: the 0-based FAT number of the active FAT (only meaningful if mirroring disabled) 25h WORD sector number of file system information sector, or FFFFh for none (see also #01788) 27h WORD sector number of backup boot sector, or FFFFh for none 29h DWORD first sector number of the first cluster 2Dh DWORD maximum cluster number 31h DWORD number of sectors occupied by FAT 35h DWORD cluster number of start of root directory 39h DWORD cluster number at which to start searching for free space Notes: except for offset 18h, all of the first 33 bytes are identical to the standard DOS 4-6 DPB unless the proper value is given in SI on entry to "Get_ExtDBP", the next-DPB pointer and device driver address are set to 0000h:0000h SeeAlso: #01786,#01395 at AH=32h,#01664