Learn: The Fetch-Decode-Execute Cycle

Welcome!This lesson is designed to help you understand the Fetch-Decode-Execute Cycle, an essential process that occurs within a computer's CPU. Let's explore how this crucial operation works and why it's important!

What is the Fetch-Decode-Execute Cycle?The Fetch-Decode-Execute Cycle describes the process the CPU uses to carry out instructions. It consists of three main stages: fetching an instruction, decoding it, and executing it. This cycle is repeated continuously while the computer is running.

Fetch StageDuring the fetch stage, the CPU retrieves an instruction from memory. The location of the next instruction is stored in the Program Counter (PC), which points to the memory address of the instruction. The address is sent to the Memory Address Register (MAR), and the instruction is fetched from memory.

Decode StageIn the decode stage, the CPU interprets the fetched instruction. The instruction is sent to the Current Instruction Register (CIR), which holds the instruction temporarily. The Control Unit (CU) then decodes the instruction to understand what needs to be done.

Execute StageDuring the execute stage, the instruction is carried out. This is done by the Arithmetic Logic Unit (ALU) if calculations are required, or by other parts of the CPU such as the registers. The result of the operation may be stored in the Accumulator (ACC) for future use.

CPU Performance FactorsThree factors affect the speed of the Fetch-Decode-Execute Cycle: clock speed, number of cores, and cache size. A higher clock speed means instructions are processed faster, more cores allow multiple instructions to be processed simultaneously, and a larger cache reduces the time to access frequently used data.

Review Time!Great work! You've learned about the Fetch-Decode-Execute Cycle, its components, and factors affecting CPU performance. Let's test your understanding with a few questions.

Congratulations!You've completed the lesson on The Fetch-Decode-Execute Cycle. Understanding this process is key to knowing how computers operate. Keep practising to master this concept!