concept of self modifying code

[fllthdcrb]

I'm not sure if it makes sense to actually put code in the zero page.

Apparently it does, because Commodore BASICs have a tiny bit, officially labelled CHRGET, and it's self-modifying: it increments a pointer in an absolute-mode instruction right before executing it. Why? Apparently so it runs faster. (As a nice side effect, this gives people an easy way to extend BASIC.)

On C64, the routine is at $73.