Curt Vendel posted some source code over in the Atari 8-bit forum some time ago for some classic video games from the Atari 8-bit series. Since the CPU is the same, porting would be a matter of replacing the sound and graphics routines only...
Among them: Donkey Kong, Dig Dug and Defender. The Atari 8-bit version of Donkey Kong was very good compared to many of the consoles/computers of the day.
http://atariage.com/forums/topic/210244-source-code-palooza/
Among them: Donkey Kong, Dig Dug and Defender. The Atari 8-bit version of Donkey Kong was very good compared to many of the consoles/computers of the day.
http://atariage.com/forums/topic/210244-source-code-palooza/