Disclosed is a docking unit which includes a mechanical lock having an unlock position and a lock position. A security key is provided for manipulating the mechanical lock to move between the unlock position and the lock position. The security key is (1) detachable from the mechanical lock at the lock position and (2) undetachable from the mechanical lock at the unlock position. The docking unit further includes a latch for securing a portable computer to the unit in response to positioning of the mechanical lock in the lock position and releasing the computer from the unit in response to positioning of the mechanical lock in the unlock position. The unit also includes an inhibitor for selectively inhibiting the mechanical lock from movement to the lock position.