Learn: The Fetch-Decode-Execute Cycle

Welcome!Today we'll explore the Fetch-Decode-Execute Cycle, a key concept in understanding how a CPU processes instructions. This lesson is designed to help you understand each step of the cycle and apply what you've learned.

What is the Fetch-Decode-Execute Cycle?The Fetch-Decode-Execute Cycle is the process by which a CPU retrieves, interprets, and carries out instructions. It ensures that the computer performs tasks efficiently, one instruction at a time. Understanding this cycle is important because it explains how computers operate at their core.

The Fetch StepDuring 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 copied into the Memory Data Register (MDR).

The Decode StepIn the decode step, the instruction is interpreted by the Control Unit. The instruction from the Current Instruction Register (CIR) is decoded into signals that the CPU can use to execute the operation efficiently.

The Execute StepIn the execute step, the decoded instruction is carried out by the CPU. This could involve performing a calculation in the Arithmetic Logic Unit (ALU), accessing memory, or changing the Program Counter to fetch the next instruction.

Review Time!Great work! You've learned about the three steps in the Fetch-Decode-Execute Cycle and the roles of registers involved. Let's test your understanding with a few questions.

Well Done!You've completed this lesson on the Fetch-Decode-Execute Cycle. Understanding this cycle is essential for grasping how a CPU processes instructions. Keep practising to solidify your knowledge!