9x11x18 SS Programmable Combination Lock

It is a compact, 12 button, 4 digit programmable combination lock. Since it requires a signal strength input, the button panel can be wired with a single redstone line. It uses 8 vertical SS memory cells, 4 for code memory (Dark Grey wool) and 4 for input memory (White wool). The yellow line controls which cells are cleared and written to, and is composed of a SS to unary decoder and two modified SS memory cells. The light grey line contains an RS nor latch for switching between writing into Input memory or Code memory, and it contains a SS to unary decoder for the New Input and New Code buttons. The light blue line compares the code memory to the input memory and performs an and operation on the comparison. The other redstone lines are less important and are explained on signs. The lock also has several nice features. If it is unlocked, pressing any button automatically resets the lock, the SS input allows for a compact button pad, the code can only be reset after it has been unlocked, and the lock can only switch to the new input mode if all 4 digits of the code have been programmed into the lock.