Changes
/* Oddities */
* The 6502 post-decrements on PHA and pre-increments on PLA, while the Z80 pre-decrements on PUSH and post-increments on POP, making them behave in opposite ways.
* The 6502 uses only one addressing mode per instruction, while the Z80 can combine two different addressing modes within a single instruction.
* The 6502 saves flags automatically during interrupts; while the Z80 requires PUSH AF and POP AF.
