which plays PSG and MSX-MUSIC when latter one is inserted. 
I think 99,99% of MSX composers would first require a tracker which can handle both chips using always the same file format.
AFAIK no-one would feel like re-arranging all that stuff manually.
Unless he/she'd get paid a LOT.
Sorry, I meant that when player don´t have MSX-MUSIC cartridge, game plays PSG only, and when MSX-MUSIC is inserted, it plays MSX-MUSIC *ONLY*, no both chips same time! Sorry for misunderstooding!
And for Outrun, maybe one can use original PSG arrangements? Thought there are just two tunes of arcade´s three...
but maybe that could be nice little extra, when you get all three tunes when you insert MSX-MUSIC cartridge.
I understand, that it would be big job to make BOTH msx-1 and msx-2 versions of Outrun (or whatever larger game) for same cartridge, but I just like to see such games! Then nobody cannot quarrel about "It´s just MSX-1 only game, so it´s crap!!" or "It´s just MSX-2 only game, so it´s crap!". 
Sorry, I forgot.
If you make cartridge which has BOTH msx-1 and msx-2 versions of whatever game, then 2+ and R owners start to quarrel, "It´s MSX-1 and MSX-2 only game, so it´s crap!"
Sorry, I meant that when player don´t have MSX-MUSIC cartridge, game plays PSG only, and when MSX-MUSIC is inserted, it plays MSX-MUSIC *ONLY*, no both chips same time! Sorry for misunderstooding!
Fair enough, but this is what I mean:
I don't know about a tracker which produces such music files.
Imagine someone finds a way to extract and convert raw PSG tone data (from a PT3 for instance) to be played with FM-PAC
(let's put the incompatibilities from PSG to FM-PAC aside for the sake of the argument).
Then you always got 3 channels played with the default instrument zero (piano).
So you'd might want different instruments, use more than those 3 channels and maybe FM-PAC drums.
You could add extra data to the PSG file which says, I want this PSG instrument replaced by that FM-PAC costum instrument, etc.
But I don't think composers would be satisfied with this.
So, you need to be able to freely edit the events for all 6/9 channels, user generated voices, drums etc. in case FM-PAC is present.
This means you either need:
* (1) A universal music file which can be handled by a replayer checking which chips are inserted and plays either PSG or FM-PAC version
* (2) Always two music files; 1 version for PSG and 1 version for FM-PAC
Option (1) implies having a tracker capable of producing such content. I don't know if such exists on MSX.
Option (2) means, to have 2 versions.
When you have a tracker with with you can make "projects" (= the same song) and from there edit and render the PSG and FM-PAC versions, it's not a big problem besides some extra disk or ROM space.
And hey, if that's possible with one tracker, you might even use both chips at the same time if you want that anyway.
OR you can have a tracker able to read PT3 and THEN make the FM-PAC version (think of MoonBlaster 1.4 to MBWave).
This implies your PSG version has to be 100% finished else you can later go convert and adapt it again.
Again, I don't think such tracker(s) exists.
With the current offering of trackers this means you'd first have to make one version of your music for one chip in one dedicated tracker, and then you can make another version for the second chip in an entirely different tracker. With no exchangable files!
I can tell you this is very boring, tedious work; imagine if you have to do that with an entire game soundtrack.
So until the day a kind of tracker which I mentioned exists, I don't think it's gonna happen soon.
I like your point about MSX/MSX2 by the way, though this implies a lot of extra work too. 
@RyJuZo: Just joking, dude.
Imagine someone finds a way to extract and convert raw PSG tone data (from a PT3 for instance) to be played with FM-PAC
Then you always got 3 channels played with the default instrument zero (piano).
So you'd might want different instruments, use more than those 3 channels and maybe FM-PAC drums.
You could add extra data to the PSG file which says, I want this PSG instrument replaced by that FM-PAC costum instrument, etc.
That would be really nice! No need for composing two tracks of same tune. But of course result is probably better (?) if composer makes that FM-PAC stuff from the scratch instead of using such PSG to FM-PAC converter program. But idea is very good!! Me wanta hear such conversion!! 
I like your point about MSX/MSX2 by the way, though this implies a lot of extra work too.
This probably works best when making some single screen/flip screen platform/maze game, which don´t have very much different tiles/sprites. INK comes to my mind.
But I like to see at least one "bigger" MSX-1/MSX-2 double game in my life time.
I guess INK is still only one MSX-1/MSX-2 double game around?
I guess INK is still only one MSX-1/MSX-2 double game around?
MJTT!
somewhat..
..which is also a double game regarding music!
I guess INK is still only one MSX-1/MSX-2 double game around?
MJTT!
somewhat..
..which is also a double game regarding music!
Yeah, and concerning pallette, don't forget Mr. Mole and Nemesis III.
And to plug our own stuff again:
MOAM will also (slightly) adjust the pallette when run on MSX2. [/plug stuff]
@ D-Tail & @ wolf_: Well, exactly that would be excellent! I totally agree crossdevelopment is the key.
If you'd separate the "mode field" and reserve chip-dedicated channels, you could exchange tone data between them.
IMHO that would be better than classifying each time which channels communicate with which chip.
Speaking only for myself, and when it's only PSG + FM-PAC (simultaneously) we're talking about, in that case I'd be quite content already with 16 channels:
11 for FM-PAC; either 9 chromatic or 6 chromatic + 5 drums
3 for PSG
2 for reserve crap, extra events, envelope/tempo/noise commands etc. split/chip
In case, for instance PSG shares some melody line with FM-PAC, just copy paste and adapt if needed.
