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AH = 32h DL = drive number (00h = default, 01h = A:, etc)
Return:
AL = status 00h successful DS:BX -> Drive Parameter Block (DPB) (see #01395) for specified drive FFh invalid or network drive
Notes: The OS/2 compatibility box supports the DOS 3.3 version of this call except for the DWORD at offset 12h. This call updates the DPB by reading the disk; the DPB may be accessed via the DOS list of lists (see #01627 at AH=52h) if disk access is not desirable.. Undocumented prior to the release of DOS 5.0; only the DOS 4.0+ version of the DPB has been documented, however. Supported by DR DOS 3.41+; DR DOS 3.41-6.0 return the same data as MS-DOS 3.31. IBM ROM-DOS v4.0 also reports invalid/network (AL=FFh) on the ROM drive
See Also: AH=1Fh - AH=52h - AX=7302h
Format of DOS Drive Parameter Block: Offset Size Description (Table 01395) 00h BYTE drive number (00h = A:, 01h = B:, etc) 01h BYTE unit number within device driver 02h WORD bytes per sector 04h BYTE highest sector number within a cluster 05h BYTE shift count to convert clusters into sectors 06h WORD number of reserved sectors at beginning of drive 08h BYTE number of FATs 09h WORD number of root directory entries 0Bh WORD number of first sector containing user data 0Dh WORD highest cluster number (number of data clusters + 1) 16-bit FAT if greater than 0FF6h, else 12-bit FAT 0Fh BYTE number of sectors per FAT 10h WORD sector number of first directory sector 12h DWORD address of device driver header (see #01646) 16h BYTE media ID byte (see #01356) 17h BYTE 00h if disk accessed, FFh if not 18h DWORD pointer to next DPB ---DOS 2.x--- 1Ch WORD cluster containing start of current directory, 0000h=root, FFFFh = unknown 1Eh 64 BYTEs ASCIZ pathname of current directory for drive ---DOS 3.x--- 1Ch WORD cluster at which to start search for free space when writing 1Eh WORD number of free clusters on drive, FFFFh = unknown ---DOS 4.0-6.0--- 0Fh WORD number of sectors per FAT 11h WORD sector number of first directory sector 13h DWORD address of device driver header (see #01646) 17h BYTE media ID byte (see #01356) 18h BYTE 00h if disk accessed, FFh if not 19h DWORD pointer to next DPB 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
See Also: #01357 - #01663 - #01787 at AX=7302h - #04039 at INT E0/CL=71h
Category: DOS Kernel - Int 21h - D
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