Int 21h Function 440Dh Minor Code 6Fh (FAT32)

Retrieves information about the specified drive. This call only works under Windows 95. It will fail if called from exclusive MS-DOS mode.

mov ax, 440Dh             ; Generic IOCTL
mov bx, DriveNum          ; See below
mov ch, DeviceCat         ; See below
mov cl, 6Fh               ; Get drive map info
mov dx, seg DriveMapInfo  ; See below
mov ds, dx
mov dx, offset DriveMapInfo
int 21h

jc  error_handler         ; Carry set means error

Parameters

DriveNum

Drive to obtain information about (0 = default drive, 1 = A, 2 = B, and so on).

DeviceCat

Specifies a FAT16, FAT12 or FAT32 drive.

Value	Description
08h	FAT32, FAT16, or FAT12 drive.
48h	FAT32, FAT16, or FAT12 drive. This value is supported on Windows 95 OEM Service Release 2 and later.

Note: Because this call may be implemented in the device driver, the 48h form of this call may fail on FAT16 or FAT12 media. Therefore, applications making the 48h form of this call must fall back on the 08h form if the 48h call fails.

DriveMapInfo

Pointer to the DRIVE_MAP_INFO structure that receives information about the specified drive. The DRIVE_MAP_INFO structure has the following form:

DRIVE_MAP_INFO    struc
    dmiAllocationLength   db ?
    dmiInfoLength         db ?
    dmiFlags              db ?
    dmiInt13Unit          db ?
    dmiAssociatedDriveMap dd ?
    dmiPartitionStartRBA  dq ?
DRIVE_MAP_INFO    ends