Where do you people find such sexy information? MUST HAVE INFORMATION!!!
The FME7 is the same physical sound chip as the AY-3-8910, for which there is a tracker (VortexTracker). If you track in VT, then you're essentially writing for the FME7 using its full capabilities (which Gimmick!, the only game that uses the FME7's audio, did not exploit). That's how I got my info at least. That and ~J-@D!~'s infinite knowledge of the NSF format. :p
It looks like it's time for me to swallow my pride and admit that I was wrong! James (aka ~J-@D!~) managed to get some noise sound out of the FME7 using direct writes to registers $C000 and $E000 via ppMCK's y<num> command. The process is pretty complicated because ppMCK itself doesn't directly support the FME7's noise, but at least we have proof that it can be done somehow!
Here is the result of James's research, demonstrating both the envelope and noise features. As always, make sure you open the NSF in VirtuaNSF or you won't hear anything special!
The MML source can also be viewed here, although the built-in Flash player won't play the NSF properly.
I'm more comcerned about how you got the middle square to play something other than a 50%, because that's awesome...
Channel X produces noise, channel Y utilises the envelope generator, and channel Z is a regular 50% square.
EDIT: Note that all three channels have the exact same capabilities (i.e. you can switch them around and it'll still work just fine), but only one channel can use the envelope generator at any given time - if you try to use it on two channels at once, the one furthest down in the MML will receive priority.
I'm not on my computer right now, but I'll share the source code when I do, if you guys are interested. [edit: never mind that, it's available right here.]
