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Format of Get_ExtDPB data buffer

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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

Note:

Except for offset 18h, all of the first 33 bytes are identical to the standard DOS 4-6 DPB.

See Also:

#01786,#01395 at AH=32h,#01664