What are the best resources for learning 6502 assembly?

A Commodore 64 is a great way to learn because it gives you a real 6502-based system to experiment with. The book Mapping the C64 is especially useful, and there are still plenty of modern demonstrations and projects that show what people are doing with low-level assembly.

The 6502 Cookbook is a worthwhile resource. It’s an older book, but it covers the processor and practical assembly techniques clearly, so the age shouldn’t be a problem for learning the fundamentals.

A detailed 6502 programming tutorial can help you get started with the instruction set, addressing modes, and memory layout. After learning the basics, writing small programs for an emulator or a Commodore 64-style environment is a good way to make the concepts stick.