Program Counter changes

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.

score 5 · Accepted Answer · answered May 14 '12 at 15:17

5

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.

answered May 14 '12 at 15:17

Alexey Frunze

..and hardware interrupts change PC to execute interrupt service routines and then return to a different program than the one that was interrupted. – Martin James May 14 '12 at 20:49
@MartinJames yeah, to a program that had been interrupted. They are all interrupted. – Alexey Frunze May 14 '12 at 23:29

score 0 · Answer 2 · answered May 14 '12 at 15:09

0

I believe that that is all, assuming non-local jumps are included as part of 2 (e.g. setjmp, longjmp).

answered May 14 '12 at 15:09

TEOUltimus

2 Answers2