When a `call` instruction is executed, the CPU must remember where to return after the function finishes. To manage this, the processor pushes the current value of the program counter—the address of the instruction immediately following the call—onto the stack.
Program Counter CPU Directional Awareness and Fetch-Decode-Execute Cycle
Instead of simply moving to the next address, the counter is loaded with a new target address specified by the jump instruction. In this scenario, the program counter functions as a simple incrementer.
After fetching an instruction located at memory address `0x100`, for example, the counter automatically advances to `0x104` (assuming a 32-bit instruction) to point to the next line. Think of it as a digital bookmark within the vast library of system memory.
Program Counter CPU Directional Awareness and Fetch-Decode-Execute Cycle
Upon completion, the original address is popped off the stack and loaded back into the program counter, allowing the program to seamlessly resume its previous path. The Fetch-Decode-Execute Cycle To understand the role of the program counter, it is essential to examine the cycle that defines CPU operation.
More About What does the program counter do
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