A port of David Firth's multi-platform Atari 800 emulator, which
emulates any 6502-based Atari computer (Atari 400/800/XL/XE), plus the
Atari 5200 game console.

Requirements
PPC Macintosh
200-300 MHz for full speed
Mac OS 8.1 or later (For Classic version). Carbon version requires 8.6
or later.
Mac OS X or CarbonLib 1.3 for the Carbon version.
InputSprockets to use controllers.

Features
Sound (though digitized sounds are not played.)
Menu-driven interface.
Settings are stored in a preferences file.
Keyboard, joystick and paddle input.
Saving screen shots into picture files. You can also copy the screen
to the clipboard or drag it to another application.

Missing Features
Upper fire buttons on 5200 controllers.
Light pens.
Digitized sounds.
Converting between ROM dump files and cartridge files.
Saving and loading of the machine state.
Integration with the Finder (i.e. responding to open commands.)
Does not yet support controllers under MacOS X.

(Paraphrased from author's site via Wayback Machine)

Grab ROMs [here (.SIT archive)][1] and [ here (.SITX archive)][2].

See also: [WACKE][3]

Compatibility
Architecture: PPC PPC (Carbonized)

  [1]: http://macintoshgarden.org/sites/macintoshgarden.org/files/apps/Atari8bitROMs.sit_.bin
  [2]: http://macintoshgarden.org/sites/macintoshgarden.org/files/apps/Atari8bitROMs.sitx_.bin
  [3]: http://macintoshgarden.org/apps/wacke-160