This page offers some documentation related to XeNTaX projects. 

 

 
FM-YAM Quick Manual v1.0 One page manual that is also added to FM-YAM batches 1 and 2 packaging
YM3812 Datasheet Technical details of the YM3812 (OPL2) chip, on registers and capabilities
YM3526 Datasheet Technical details of the YM3526 (OPL1) chip, on registers and capabilities
Secret Weapons of Commodore information on SFX series A must-read about some of the details of the SFX Series, including the Sound Expander. A great site by Cameron Kaiser.
Programming the Adlib/Soundblaster Jeffey S. Lee's documentation on how to program the YM3812 on the Adlib/Soundblaster. This is basically the same as doing it for FM-YAM, so a great document.