OPL4 - Should I use it in the next game?

1) No idea how many are out there. I suppose most of the active MSX users has one.

2) As far as I have tested, only OpenMSX supports it fully. It is also the only emulator in active development. WebMSX can emulate the OPL4 reasonable, but it has a lot of timing issues. It also does not emulate LFO's for example. BlueMSX does not support the timers correctly if I remember correctly, so I've stop using that emulator years ago (it is basically abandonware).

3) Wave is "only" 24 channels of PCM (both from RAM and ROM). FM is 6 channels of PCM, and the (18?) channels of FM. PCM in the FM version is mostly used for percussion and custom samples.

4) Not sure why this matters. The GR8NET is the only OPL4 implementation in FPGA, which is done perfectly. It can only do 512KB RAM with the current cartridges. The GR8NET is also "in active development" so any issues can still be resolved. As far as I know this is the only still available OPL4 compatible cartridge, not taking the current Russia situation in consideration.

5) I have defined the LCD as 512K, also because of the GR8NET limit. The moonsound v1 cannnot be easily exanded, since the chip is soldered. The v2 is pretty easy to expand to max 1MB. Not sure of any of the more recent cartridges. I currently own the Moonsound v1, v2, MSX Blaster and GR8NET.

6) There is no bios in the cartridge. You should directly use the i/o ports.

7) You have two timers which generate interrupts. You mostly use them the same way you use the vblank for timing on the FM-Pac. Biggest advantage is that the music timing will be indifferent to the VDP settings (50/60Hz). You do not need to use these timers at all, if you don't use them, there are no interrupts. Disadvantage of the timers is that they can occur anytime, not only in the border. There is no interrupt to indicate "end of sample" and other fancy stuff. Just two timers.

8) You probably already have all of them. Except a mod player. In SD we just use MODs up to 16 channels. So the tool is actually any program that can create MOD files.

Well, as long as you also support other sounds chips like for example MSX-Music it can only be considered as a nice plus to do so, so... just go ahead

Totally see that!!! But there are quite some combo-carts out there, so why not a new v9990+OPL4? It would be a great one.

Double post... Sorry!

From a composer perspective that might be completely different though. IMO OPL4 is more interesting to make music for, simply because you have a lot more possibilities (more channels, custom samples, stereo). Sadly there’s not a lot of trackers/programs that allow you to use it to its full potential (at least Moonblaster FM/Wave, they’re very limited even though they at least have drivers to use it in games).

Also, from a musician perspective I don’t really care that some people say it’s not part of the MSX standard
As a musical tool, it gives me more options to make suitable music, rather than hearing the same psg or fm sounds all over again.

Downside of supporting multiple soundchips is that the music has to be made twice, for every soundchip. Apart from the extra work, it also means stuff gets lost and compromised because you can’t really lean in into a single soundchip and get the most out of it. For Bombaman, the FM music was essentially lazy stripped down conversions of the Moonsound music and I hated wasting my time on that.

YMMV, just wanted to share a perspective from the musical side of things.