Yeah, I know, this is an NES music forum, just hear me out.
I recently got to hear some really cool old Atari homebrew music, specifcly "Mr. Roboto" by Styx and "Rock the Casbah" by The Clash. These songs were put into Atari games as simple background music, with no other sounds. Other games I've played feature little melodys, like Spider Fighter and Donkey Kong. All of these sounds are very simular to NES ones, so I was wondering do Atari 2600 and NES both run on a 2A05?

Though the Atari 2600 CPU does use the same instruction set as the NES, the Atari 2600 sound hardware is completely different.

Yeah, but the music I heard that was supposedly comming out of an Atari could be 100% mimicked with the NES and be dead on the same. You could emulate the Atari music, if you will. :P

It appears some of the waveforms that can be made with an Atari 2600 aren't possible on the NES. Atari 2600 sound is like 2A03 looped noise on steroids. Read More

Teppes, you gotta remember I have no idea what any of that means. But from your very basic description, "2A03 looped noise on steriods", I can infer a few things. So, could you do it the other way around then and recreate NES music on the 2600? Maybe someone could port Excitebike over. ^_^

I've examined Atari 2600 sound, I tried writing music on it (using Paul Slocum's sound engine) and it's not very easy to work with. It does have some very strange waveforms. Few systems actually have distortion settings for the square waves, some waveforms are kinda like a cross between a square wave and noise. It sounds cool as hell, but the problem is there isn't much frequency control. So there are many notes that it can't play, and some of the ones it can play are out of tune. (it get's even weirder, the frequencies played for each distortion setting is different, I think).

Atari 2600 couldn't play NES music, but the NES could play Atari music - minus the characteristic waveforms (it's not as fun anymore, then).

A similar soundchip that easier to work with is Atari's POKEY (used in their 8-bit computers and many arcade games). I had some fun playing around with this tracker:
http://www.infos.cz/raster/atari/rmt/rmt.htm