Music during loading. Is it possible?

Fun question.

With opl4 or musicmodule you could play looping samples, because the unit is standalone

With a basic msx, maybe cassette if you write your own cassette loaders. The psg can produce sound while loading, the interrupts are disabled. Disk loading the interrupts are sometimes disabled, so the timing would be bad.
In theory it would be possible.
I think msx can do a lot if you really want. Coding your custom loaders it could be done.

I can confirm that with the philips music module with samples you can, we used that a lot in our 4 mega demo’s. Playing a song is a different matter.

That is probably Fony DemoDisk #2

Music is not a real problem when you would be willing to sacrifice loading speed, music timing and load from SD/HD.

Whenever you load data, interrupts might be disabled which screws up timing. You need to load less bytes at the same time to allow for more interrupts (slower loading).

Disk loading using the BIOS disables a lot of interrupts and therefore it will have the most impact. Traxplayer or the screen 3 animations we did actually did the loading of data from disk directly from the hardware and we could interleave sample playing with loading data.

The project we are working on now does a lot of sample loading and cannot play music because of that. Everything is sample based and the OPL4 does not support playering and uploading data to sram at the same time.

It is definitively possible, since if I don't remember wrong, the "Mutant Zone" game for MSX1 id it! (I'm speaking from memory, so, I might be wrong), but I think it has a minigame while loading, with music.