Matt Heffernan kicks off a new series with a hands-on 65C02 assembly tutorial built for the Commander X16. This isn’t just a rerun—he’s reworked an earlier video to focus on actual hardware and the most current development tools. Whether you’re looking to go beyond BASIC or just want to see what makes the X16 tick, this episode breaks down your first working program in assembly—byte by byte.
The 65C02 assembly tutorial starts with an explanation of what assembly actually is: human-readable instructions that translate directly into the 1s and 0s a processor understands. Matt walks viewers through writing a program using the ca65 assembler, a tool in the cc65 toolchain, that turns a short script into machine code for the X16. He shows how to write the code, assemble it into a .PRG file, and run it both in the emulator and on real hardware.
This episode covers just three main instructions—load, increment, and store—but packs in everything you need to understand how the X16 handles memory, registers, and opcodes. There’s plenty of practical info too, like setting up your .org address, building with cl65, and loading from the BASIC prompt. If you’ve ever been intimidated by assembly language, this episode chips away at that with simple, logical steps.
Best of all, the example code and more helpful resources are available on Matt’s GitHub repo:
https://github.com/SlithyMatt/x16-assembly-tutorial
The 65C02 assembly tutorial series is perfect for anyone looking to start programming close to the metal on the Commander X16. Even if you’ve only used high-level languages before, you’ll come away with a solid grasp of how the processor actually works—and maybe even get hooked.
