Minecraft wiki entry for Memory, associated text: That linear design can also be bent into a 3×3 square, as N. (The "any" blocks can be air, and that torch can just as well be on the ground.) Tiling design N is a little tricker, but it can be done in either horizontal direction, by mirroring adjacent copies. Note that the output can be taken from whichever side of that corner is free, but the player will need repeaters to keep adjacent outputs from cross-connecting.