Learn: The Fetch-Decode-Execute Cycle

Welcome!You've already learned why the CPU is essential. Now, let's build on that by exploring how the CPU processes instructions using the Fetch-Decode-Execute Cycle. This forms the core of how a computer works!

What is the Fetch-Decode-Execute Cycle?The Fetch-Decode-Execute Cycle is the process by which the CPU retrieves, understands, and carries out instructions. This cycle happens millions or even billions of times per second, enabling the computer to perform tasks.

Step 1: FetchDuring the fetch phase, the CPU retrieves an instruction from memory. The Program Counter (PC) holds the address of the next instruction. This address is sent to the Memory Address Register (MAR), which communicates with main memory to retrieve the instruction. The instruction is then loaded into the Memory Data Register (MDR).

Step 2: DecodeIn the decode phase, the CPU analyses the instruction in the Current Instruction Register (CIR). The Control Unit (CU) identifies what the instruction is asking the CPU to do, such as performing a calculation or accessing data from memory.

Step 3: ExecuteDuring the execute phase, the CPU performs the action required by the instruction. This could involve calculations in the Arithmetic Logic Unit (ALU), data transfer between memory and registers, or sending instructions to output devices.

Why is the Fetch-Decode-Execute Cycle Important?This cycle is crucial because it allows the CPU to process instructions step by step. Without it, the computer would not be able to perform tasks or run programs efficiently.

Review Time!Great work! You've learned about the key steps of the Fetch-Decode-Execute Cycle, including the roles of the CPU components. Now, let's test your understanding with a few questions.

Well Done!You've mastered the Fetch-Decode-Execute Cycle and the roles of key CPU components. This knowledge forms the foundation of understanding how computers process instructions!