[Tor3]

For that you'll need Apple II documentation - though that's device-specific information. It's easy to find online, e.g. https://nicole.express/2024/phasing-in-and-out-of-existence...., but there's lots more with various levels of info. This one, for example: https://www.kreativekorp.com/miscpages/a2info/memorymap.shtm...

For actual 6502 programming you'll need a dedicated 6502 assembly programming book, for example the aforementioned Rodney Zaks books.

[abkt]

Is the Apple II Reference Manual good for that ? Or anything specific to the Apple II, like "What's Where in the Apple" or "Understanding the Apple II" ?

[Tor3]

All of those are quite useful.