This is TheWebMachine's 6502 source code bits based on Ben Eater's 6502 breadboard project (eater.net/6502); but most of it will work with other 6502-based systems with little modification (most of which is done in the symbols at the top of the assembly code).
It's all MIT licensed. Do whatever you want with it. If you have a nifty improvement, feel free to submit a P request.