Learn: The Fetch-Decode-Execute Cycle

Welcome!Building on your knowledge of why the CPU is essential, today we’ll explore how it processes instructions using the Fetch-Decode-Execute Cycle. Let’s get started!

What is the Fetch-Decode-Execute Cycle?The Fetch-Decode-Execute Cycle is the process used by the CPU to execute instructions. It involves fetching an instruction from memory, decoding it to understand what to do, and executing it to carry out the task.

Step 1: FetchThe CPU retrieves the next instruction from memory. It uses the Program Counter (PC) to know the address of the instruction. The instruction is stored in the Memory Data Register (MDR).

Step 2: DecodeOnce the instruction is fetched, the CPU decodes it to understand what needs to be done. This is managed by the Control Unit (CU), which interprets the instruction and prepares for execution.

Step 3: ExecuteDuring the execute phase, the CPU carries out the instruction. This may involve arithmetic operations handled by the Arithmetic Logic Unit (ALU), accessing memory, or interacting with input/output devices.

Review Time!Great work! You've learned about the key steps of the Fetch-Decode-Execute Cycle and the roles of important components like registers and the Control Unit. Let’s test your understanding with a few questions.

Congratulations!You’ve completed this lesson on the Fetch-Decode-Execute Cycle! You now understand how the CPU processes instructions step-by-step. Keep practising to reinforce your knowledge!