Minecraft wiki entry for Redstone_computers, associated text: Arithmetic logic unit (ALU) will execute instructions sent to it from the CU and will compare binary numbers and communicate with the Control Unit. It can do simple addition and subtraction which can be repeated to do multiplication and whole-number division, outputting a whole number (then division). There are also logic gates for booleans, the fundamental logic gates are required, such as the NOT gate and the NAND gate.