What’s a good way to start learning 6502 assembly?

Pick a target machine first. The 6502 instruction set is only part of the picture: a Commodore 64, NES, Apple II, and a home-built board all have different memory maps and hardware. A book or tutorial for one platform will make more sense if you follow it on that same platform.

For general reading, 6502.org has material and books, and visual6502 can help make the CPU’s behavior less abstract. Start with tiny programs, like adding two values or copying a byte, and step through the registers and memory in an emulator before attempting a full project.

Assembly isn’t necessarily the easy route. Each instruction is close to what the processor executes, but you have to manage details that a higher-level language handles for you. That’s useful for learning how a CPU works, just expect progress to come in small steps.

I’d begin with the accumulator, X and Y registers, flags, addressing modes, and branches. Write a few short routines and inspect the results after each instruction. Once that feels comfortable, move on to the chosen machine’s input, output, and other hardware.

Keep the first goal small: assemble a program that adds two numbers, then one that loops over a few bytes in memory. A debugger or visualizer that lets you step instruction by instruction is more useful at this stage than trying to build a game right away.

Also check which 6502 variant your target uses. The core ideas carry over, but platform details and supported instructions can differ.

If your real aim is making a program for an existing retro computer or console, use resources for that exact platform rather than a generic CPU tutorial alone. You’ll need to learn how its screen, sound, and input hardware are mapped, and those details aren’t part of the 6502 instruction set itself.

If you mainly want to understand the processor, a simple emulator or a small physical circuit can be a more focused starting point. Either way, choose one environment and follow through with a tiny working program.