Interrupt 21h Function 440Dh Minor Code
48h
Locks or
unlocks the volume in the given drive (preventing or permitting its removal) or
returns the locked status of the given drive.
mov ax, 440Dh ; generic IOCTL
mov bx, DriveNum ; see below
mov ch, 8 ; device category
mov cl, 48h ; Lock or Unlock Removable Media
mov dx, seg ParamBlock ; see below
mov ds, dx
mov dx, offset ParamBlock
int 21h
jc error
Parameters
DriveNum
Drive to lock
or unlock. This parameter can be 0 for default drive, 1 for A, 2 for B, and so
on.
ParamBlock
Address of a PARAMBLOCK structure that specifies
the operation to carry out and receives a count of the number of locks on the
drive.
Return Value
Clears the
carry flag and copies the number of pending locks on the given drive to the NumLocks
member of the PARAMBLOCK
structure if successful. Otherwise, the function sets the carry flag and sets
the AX register to one of the following error values:
|
01h |
The
function is not supported. |
|
B0h |
The volume
is not locked in the drive. |
|
B2h |
The volume
is not removable. |
|
B4h |
The lock
count has been exceeded. |