Learn: The Fetch-Decode-Execute Cycle

Welcome!You've already learned why the CPU is essential for running a computer. Now, let's explore how it processes instructions using the fetch-decode-execute cycle.

What is the Fetch-Decode-Execute Cycle?The fetch-decode-execute cycle is the process the CPU uses to run instructions. It fetches instructions from memory, decodes them to understand what to do, and executes the actions.This cycle allows a computer to perform tasks step by step, like loading a game or saving a file.

Step 1: FetchThe CPU retrieves the next instruction from memory. The Program Counter (PC) stores the address of the next instruction, and the Memory Address Register (MAR) sends that address to the memory.The instruction is then copied into the Memory Data Register (MDR).

Step 2: DecodeOnce fetched, the instruction is sent to the Control Unit (CU). The CU decodes the instruction to understand what actions to perform, such as calculations or data movement.Decoding helps the CPU understand the purpose of the instruction.

Step 3: ExecuteAfter decoding, the CPU performs the instruction using components like the Arithmetic Logic Unit (ALU) or registers. This could include calculations, storing data, or interacting with hardware.The Accumulator is often used to store intermediate results during execution.

Review Time!Great work! You've learned about the fetch-decode-execute cycle. Let's test your understanding with a few questions.