Learn: The Fetch-Decode-Execute Cycle

Welcome!Today we'll learn about the Fetch-Decode-Execute Cycle. This is how a processor executes instructions step by step. Let's explore it in detail!

What is the Fetch-Decode-Execute Cycle?The Fetch-Decode-Execute Cycle is the process the CPU uses to execute instructions. It involves fetching an instruction from memory, decoding it to understand what needs to be done, and then executing it. This cycle repeats continuously while the computer is running.

Step 1: FetchDuring the fetch stage, the CPU retrieves the instruction from memory. The Program Counter (PC) holds the address of the next instruction, and the Memory Address Register (MAR) sends this address to memory to fetch the instruction.

Step 2: DecodeIn the decode stage, the instruction is interpreted by the CPU. The instruction is copied into the Current Instruction Register (CIR) and decoded by the Control Unit, which determines what needs to be done.

Step 3: ExecuteDuring the execute stage, the CPU carries out the decoded instruction. This might involve performing calculations in the Arithmetic Logic Unit (ALU), transferring data, or updating registers. The result is stored in the Accumulator (ACC) or memory.

Factors Affecting the CycleThe speed of the Fetch-Decode-Execute Cycle depends on factors like clock speed, the number of cores, and the size of the cache. Faster clock speeds and larger caches allow the CPU to process instructions more quickly.

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