Learn: The Fetch–Decode–Execute Cycle

Welcome!Today we will learn about the fetch–decode–execute cycle, an essential process in the CPU. Let's explore how the CPU processes instructions step by step!

What is the Fetch–Decode–Execute Cycle?The fetch–decode–execute cycle is the process the CPU uses to run instructions stored in memory. It repeats continuously to carry out tasks required by computer programs.

Step 1: FetchDuring the fetch step, the CPU retrieves the next instruction from memory. The Program Counter (PC) holds the address of the next instruction, which is sent to the Memory Address Register (MAR). The instruction is then fetched into the Memory Data Register (MDR).

Step 2: DecodeIn the decode step, the CPU interprets the fetched instruction. The Control Unit (CU) decodes the instruction to determine what actions need to be performed. This ensures the CPU understands the task.

Step 3: ExecuteIn the execute step, the CPU carries out the decoded instruction. For example, the Arithmetic Logic Unit (ALU) may perform calculations, or data may be moved to a register or memory location.

Review Time!Great work! You’ve learned about the fetch–decode–execute cycle and the key roles of CPU components. Let’s test your understanding with a few final questions.