Nice article, but it doesn’t mention the really gnarly stuff such as using the fact that a subroutine happens to return with some flags set, or with some fixed value in the X register to shave of some initialization instruction in the code calling it.

A main advantage of the 6502 is that it only has 64 kilobytes of memory ;-). That means sufficiently advanced and motivated programmers can keep the entire program in their head, and also nudges them to avoid bloat such as the use of 16-bit integers.

Zero page is great, but has limitations, for sure. Lots of moving stuff back and forth into the accumulator in order to do anything with it. And not relocatable like in the 6809 or 65816 "direct page".

Some nice simple extensions to the 02 architecture would be:

1) relocatable direct page and stack like in the 816. 2) some way of aliasing A to a direct page address to avoid doing it by hand.