Learn: The Fetch-Decode-Execute Cycle

Welcome!Welcome to today's lesson on The Fetch-Decode-Execute Cycle. This is an important process that all CPUs follow to execute instructions. Let's explore how it works step by step!

What is the Fetch-Decode-Execute Cycle?The Fetch-Decode-Execute Cycle is how a CPU processes instructions. It involves fetching an instruction from memory, decoding its meaning, and executing it. This cycle is repeated constantly while the computer is running, enabling it to perform tasks.

Step 1: FetchingThe fetch phase involves retrieving an instruction from memory. The Program Counter (PC) holds the address of the next instruction, which is sent to the Memory Address Register (MAR). Then, the instruction is fetched from memory and stored in the Memory Data Register (MDR).

Step 2: DecodingThe decode phase involves interpreting the fetched instruction. The instruction is sent to the Current Instruction Register (CIR), where the Control Unit breaks it down to understand what needs to be done. This phase determines which operation the CPU should perform.

Step 3: ExecutingThe execute phase is where the CPU carries out the decoded instruction. This often involves the Arithmetic Logic Unit (ALU) for calculations or logical operations. The result is stored in a register, such as the Accumulator (ACC), and may affect other components like output devices.

CPU Performance FactorsThe speed of the Fetch-Decode-Execute Cycle depends on factors like clock speed, number of cores, and cache size. Higher clock speeds allow faster instruction processing, while multiple cores enable parallel processing.

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