Versatile Commodore Emulator
VICE is an emulator collection which emulates the C64, the C64-DTV, the C128, the VIC20, practically all PET models, the PLUS4 and the CBM-II (aka C610). It runs on Unix, MS-DOS, Win32, OS/2, Acorn RISC OS, BeOS, QNX 6.x, Amiga, GP2X or Mac OS X machines.
multi-platform cross assembler for 6502/6510/65816 cpu
ACME is a free cross assembler released under the GNU GPL. It can produce code for the following processors: 6502, 6510 (including illegal opcodes), 65c02 and 65816. ACME supports the standard assembler stuff like global/local/anonymous labels, offset assembly, conditional assembly and looping assembly. It can include other source files as well as binaries while assembling. Calculations can be done in integer or float mode. Oh, and it is fast.