Question

Of all possibilities in which the PC (program counter) register changes I found these:

1) PC increases its value with loading new instruction
2) with jumps and branches
3) with calling subroutine
4) with return from subroutine

Are those all or am I missing something?

I come from this article.

Answer 1

There are a few more:

• Hardware interrupts change PC to execute interrupt service routines and then return to the interrupted program.
• Exceptional situations (exceptions like division by 0 or page fault) change PC in a similar fashion.
• Debug interrupts do that too.
• System calls (their invocation and return) change PC as well.