These are reference charts to trouble shoot your Commodore C-64 and 1541.
I have version Reference #4 and Reference #6
GEOS – Leroy’s Cheat sheet
This is a nice one with a ton of info for you.
The PDF is here: Geos-card
The Jpeg is below:
BASIC Overlay by Leroy’s Cheatsheet
The PDF is here: BASIC-card.pdf
Airborne Ranger Overlay
THE PDF is HERE: Airborne_Ranger_Overlay.pdf