Program Counter

Program Counter:

The Program Counter (PC) is a crucial register within the CPU that holds the address of the next instruction to be fetched and executed during the program's operation. It plays a central role in the fetch-decode-execute cycle.

Functions of the Program Counter:

1. Instruction Address Tracking:

   • Stores the memory address of the instruction to be executed next.

2. Automatic Increment:

   • After an instruction is fetched, the PC is incremented to point to the address of the subsequent instruction in sequence.

3. Branching and Jumping:

   • If the current instruction involves a jump, branch, or subroutine call, the PC updates to the new target address instead of incrementing sequentially.

4. Program Flow Control:

   • Ensures the CPU processes instructions in the correct sequence unless explicitly modified by a control instruction.

Role in the Fetch-Decode-Execute Cycle:

1. Fetch Phase:

   • The CPU reads the address stored in the PC to fetch the next instruction from memory.

2. Increment Phase:

   • After fetching, the PC updates to the next instruction address 

3. Execution Phase:

   • Executes the instruction while maintaining or updating the PC as required.

Importance of the Program Counter:

• Sequential Execution: Maintains the flow of the program by fetching instructions in order.

• Non-Sequential Execution: Handles jumps, calls, and interrupts to alter the normal sequence when needed.