Abstract: An electromechanical locking device completely contained within a doorknob which can be a part of a usual lockset or retrofitted on an existing lockset which requires entry of an access code or entry of both an access code and use of a mechanical key for operating the lock. The code is entered on a keypad exposed on the knob and supplies a signal to a computer powered by batteries. A correct match of the input code to a code stored in the computer will actuate a motor operated cam to release a mechanical interlocking pin enabling the lock cylinder to be rotated to the unlocked position. Both visual and audible signals may be provided in the doorknob as to the power level of the batteries and ready condition of the lock. The mechanical interlock pin is disengaged automatically from the lock cylinder upon the power level of the batteries dropping to a predetermined level requiring only mechanical key operation of the lock.