No$2k6

Emulation works with all games known to me. Precise timing emulation synchronizes CPU with the cathode ray beam. Auto-detects pal/ntsc frame rates & cartridge memory banking types. Emulates joysticks, paddles, keypads, and steering controller.
Debugger with breakpoints, symbolic debug info (labels), automatic I/O and Kernal disassembler comments, built-in assembler/disassembler supports native/nocash syntaxes, upload to real atari function, help text includes full atari programming specs.