cc65 is a complete cross development package for 65(C)02 systems,
including a powerful macro assembler, a C compiler, linker, librarian
and several other tools.

Supported targets include the Atari 400/800/XL/XE computers, the Atari Lynx
console, the Commodore PET/VIC/64/16/Plus4, the Nintendo NES, the Apple II,
and others.