Abstract: A key reading apparatus having a slot for receiving a key and at least one reading pin sensing depressions or raised projections on a key. The pin has a magnetic portion movable to two different positions, each of which positions place a Hall transistor at a different energy level. The key may have at least two rows of reading points. A clock line device distinguishes successive reading positions.

Abstract: A key reading system including a key having a plurality of rows of reading positions, each reading position cooperating with a reading position in each other row to form a set of reading positions. The reading system includes a clock line which senses all but one of the total number of code combinations of each set as a clock pulse, thus eliminating the need for a separate clock pulse row.

Abstract: A door control unit for electronically locking and unlocking one or more doors. The door control unit includes door locking means having a rotatable lock cylinder for locking and unlocking a door, means engaging the lock cylinder for normally locking the door, and means responsive to a control signal for unlocking the door. A key is included having a first and second series of light-refractive discrete encoded clocking and data bars formed thereon. The lock cylinder includes photodiode means for reflectively decoding the encoded data on the key upon insertion of the key into the lock cylinder, thereby generating a first identification code. The first code is compared with at least one other predetermined identification code by processor means and if the two signals correspond, the control signal is generated thereby unlocking the door.