I was talking about the '85... sorry!
In that case, just snag the Pin Change library from the Tiny Core website and play a bit.
So in summary, external interrupts execute certain code when triggered
pin change interrupts are a register that stores the inputs on that port?
No. "Pin change interrupts" also execute certain code when triggered. The difference is that up to eight pins are tied to a single interrupt service routine and only CHANGE is supported.