Learn: Program Counter - Tracking the Next Instruction

Welcome!You've already learned about the CPU, the fetch-decode-execute cycle, and how registers work. Today, we'll focus on the Program Counter (PC), which ensures the CPU knows which instruction to execute next.

What is the Program Counter?The Program Counter (PC) is a register in the CPU that stores the address of the next instruction to execute. It plays a key role in the fetch-decode-execute cycle, ensuring the CPU processes instructions correctly in sequence.

How Does the Program Counter Work?During the fetch phase, the CPU retrieves the next instruction from the memory location stored in the Program Counter. After fetching, the PC is updated to point to the address of the next instruction.This ensures instructions are executed in order. If a program includes jumps or loops, the PC adjusts to point to the correct instruction instead of simply incrementing.

Why Is the Program Counter Important?The Program Counter ensures the CPU processes instructions efficiently and in sequence. Without it, the CPU wouldn't know where to look for the next instruction, leading to errors or incomplete program execution.

Updating the Program CounterAfter each instruction is fetched, the Program Counter updates to point to the next instruction. In sequential programs, this is usually done by incrementing the address. For jumps or loops, the address updates to a specific location.

Review Time!Great work! You've learned how the Program Counter tracks the next instruction and its role in the CPU. Let's test your understanding with a few questions.