This site provides all kinds of information about theYamaha CX5M(II) music computers.
I also added a blog page on which you can find more MSX related things.
This site should be a valuable source for programming or repairing the computer or module. It also provides information about connecting the module to another MSX(2) system.
BUT! I’m not a software expert. I can provide the info, but am not able to help you with programming of Z80 ML-applications. I do hope you people can keep me posted on new developments though and that this info can stir up some extra interest again for this unique machine.