Interrupt 21h Function 440Dh Minor Code
6Bh
Unlocks the
physical volume or decrements the lock level.
mov ax, 440Dh
; generic IOCTL
mov bl, DriveNum
; see below
mov ch, 08h
; device category (must be 08h)
mov cl, 6Bh
; Unlock Physical Volume
int 21h
jc enter
Parameters
DriveNum
Drive to
unlock. This parameter must be one of these values (same device unit numbers as
for Interrupt 13h):
|
00 - 7Fh |
Floppy disk
drive (00 for the first floppy drive, 01 for the second, and so on). |
|
80 - FFh |
Hard disk
drive (80 for the first hard disk drive, 81 for the second, and so on). |
Return Value
Clears the
carry flag if successful. Otherwise, the function sets the carry flag and sets
the AX register to an error value.
Remarks
This function
is used to release the lock obtained by using Lock Physical Volume (Interrupt
21h Function 440Dh Minor Code 4Bh).
Only the lock owner can release the lock on a volume.
To release
the lock on the volume, an application must call Unlock Physical Volume the
same number of times that Lock Physical Volume was called.