Minecraft wiki entry for Advanced_redstone_circuits, associated text: Therefore, we combine (((b1=b1 & b2=b2) & b3=b3) & b4=b4) =: (b*=b*). In minecraft we have to use four ANDs like the left handside. Now we save the status to the RS-latch /A\. The comparison works the same way for Key[2], and Key[3].