Learn: The Fetch-Decode-Execute Cycle

Welcome!Welcome back! You’ve already explored why the CPU is essential to a computer. Now, let’s build on that knowledge by learning about the Fetch-Decode-Execute Cycle, which is how the CPU processes instructions.

What is the Fetch-Decode-Execute Cycle?The Fetch-Decode-Execute Cycle is the process the CPU uses to execute instructions. It retrieves instructions from memory, decodes them to understand what needs to happen, and then performs the actions.This cycle is repeated millions of times per second to ensure the computer runs smoothly and efficiently.

Step 1: FetchThe CPU begins by fetching the next instruction. The Program Counter (PC) holds the address of the next instruction in memory. The Memory Address Register (MAR) is used to locate this instruction in the main memory.The data at the address is then copied into the Memory Data Register (MDR).

Step 2: DecodeOnce the instruction is fetched, the Control Unit (CU) decodes it. This means the CPU translates the instruction into a format it understands and determines what action to take.

Step 3: ExecuteFinally, the CPU executes the instruction. This involves performing the operation specified, such as a calculation or moving data. The Arithmetic Logic Unit (ALU) often plays a key role in this step, as it carries out calculations and logical operations.

Review Time!Great work! You’ve learned how the CPU processes instructions in the Fetch-Decode-Execute Cycle. Let’s test your understanding with a few final questions.

Congratulations!You’ve mastered the Fetch-Decode-Execute Cycle. This cycle is the foundation of how CPUs process instructions and keep computers running. Keep reviewing this topic to strengthen your understanding further!