A security device to secure a computer may include a substantially vertical pedestal, a fixed platform mounted on the pedestal, a clamping table to cooperate with the fixed platform to secure the computer and a locking assembly to allow the clamping table to be moved to allow the computer to be attached and released from the fixed platform in an unlocked state and to prevent the clamping table from being moved to hold the computer in a locked state, The locking assembly may include a locking knob to operate the locking assembly between the locked state and the unlocked state, and the locking knob may rotate freely in the locked state and rotates to allow the clamping table to be moved in the unlocked state.