Minecraft wiki entry for Advanced_redstone_circuits, associated text: The example on the right uses a 4-bit design, so you can handle a hexadecimal key. So you can use 15 various digits, [1,F] or [0,E]. You only can use 15, because the state (0)16 = (0000)2 won't activate the system. If you want to handle 16 states, you edit the logic, to interact for a 5-bit input, where the 5th bit represents the (0)16 state.