Learn: The ALU - Arithmetic vs Logic

Welcome!Welcome to today's lesson! You've already learned about the importance of the CPU, the fetch-decode-execute cycle, and how registers help the CPU process instructions. Today, we'll focus on the Arithmetic Logic Unit (ALU) and how it performs arithmetic and logic operations inside the CPU.

What is the ALU?The Arithmetic Logic Unit (ALU) is a key component of the CPU. It is responsible for carrying out arithmetic calculations (like addition and subtraction) and logic operations (like AND, OR, and NOT). The ALU works closely with other parts of the CPU, such as the control unit and registers, to execute instructions during the fetch-decode-execute cycle.

What does the ALU do?The ALU performs two main types of operations: arithmetic operations, such as addition, subtraction, multiplication, and division, and logic operations, such as comparing values and performing operations using logic gates (AND, OR, NOT). These operations are essential for running programs and solving problems.

Arithmetic Operations in the ALUArithmetic operations involve calculations with numbers. The ALU can perform tasks such as addition, subtraction, multiplication, and division. For example, if you're adding two numbers in a program, the ALU handles the calculation.

Logic Operations in the ALULogic operations involve making decisions based on comparisons and conditions. The ALU uses logic gates such as AND, OR, and NOT to process these operations. For example, the ALU can compare two numbers to determine which is larger or check if two values are equal.

How does the ALU fit into the CPU?The ALU works with other CPU components to process data. For example, it takes inputs from the registers, performs calculations or logical comparisons, and sends the results back to the registers or memory. The control unit directs the process by telling the ALU what operations to perform.

Review Time!Great work! You've learned what the ALU does, the difference between arithmetic and logic operations, and how the ALU fits into the CPU. Let's test your understanding with a few questions.