| Function | Description |
|---|---|
| Interrupt 21h Function 440Dh Minor Code 4Ah | Lock Logical Volume |
| Interrupt 21h Function 440Dh Minor Code 4Bh | Lock Physical Volume |
| Interrupt 21h Function 440Dh Minor Code 6Ah | Unlock Logical Volume |
| Interrupt 21h Function 440Dh Minor Code 6Bh | Unlock Physical Volume |
| Interrupt 21h Function 440Dh Minor Code 6Ch | Get Lock Flag State |
| Interrupt 21h Function 440Dh Minor Code 6Dh | Enumerate Open Files |
| Interrupt 21h Function 440Dh Minor Code 6Eh | Find Swap File |
| Interrupt 21h Function 440Dh Minor Code 70h | Get Current Lock State |
| Interrupt 21h Function 710Dh | Reset Drive |
The exclusive-volume locking IOCTL functions are similar to other MS-DOS functions. An application must copy function parameters to registers and issue an Interrupt 21h instruction to carry out the call.