What Is Arithmetic Logic Unit (ALU)?

Let's take a moment to consider the arithmetic logic unit. It's the heart of your computer, and without it, it wouldn't work. The Arithmetic Logic Unit (ALU) does all work related to arithmetic and logic operations on instruction words. Some microprocessors it's divided into two parts: an arithmetic unit (AU) and a logic unit (LU). So, what does that mean? Well… let's say you want to count two numbers together. Your computer would need to give the ALU those numbers, the operation (addition), and the destination address for where the result should go. The ALU would then add those numbers and send them off for storage at their destination address or what if you wanted to check whether one number is more significant than another? You'd give those numbers to the ALU along with an "if" operation—like "if A > B"—and tell it where to put its answer if A > B is true. Then you'd ask if A > B was false, and if so, where would be a good place for me to put my answer? The ALU will do all of this checking for you! The ALU is the workhorse of the CPU. It does all the math, and it does it well. But not just any math. It's not like you can give it many numbers and expect it to add them up. "What if one of those numbers is negative?" or "what if you want to multiply them?" or "divide them?" or do some crazy stuff like square roots or logarithms? Well, that's where the ALU comes in! It has these different processes for doing arithmetic operations, logic operations, bit-shifting operations, etc. So, next time you're trying to figure out how to do something with your computer—like calculating how much money you'd save if you went ahead and bought those super-expensive designer shoes that are on sale. You should remember that you have an ALU inside your CPU!