I'll let the question speak for itself...is there a routine to play sound in ASM programs?

If you just want beeps and bloops to play a melody during a game, the Pyoro source code had a note reader and player that you can use and also kind of has some macros to simplify editing music.

On the other hand, if you want high quality sound or music that doesn't need to be rendered at the same time as the game, try Real Sound.

And on the third hand, if you want some medium quality music to play while the game is going, you'll have to ask calc83 becasue he's the only one I've seen actually pull it off well, or at least I trust he has, I haven't actually used it.  I think it requires 15MHz mode for this option.

calc83

Poor Calc84god...er...maniac, you downgraded him and now he can no longer test Project M sound on real hardware

I wouldn't be surprised if he could pull off 1 channel sound on 6 MHz tho, even during gameplay, considering ATM he uses 3 or 4 channels

Wouldnt there be a way to make sound not play consistently, though? Like not a long beep, but several millisecond beeps to leave some CPU time for other stuff? IIRC, CalcMOD allowed doing some actions in the middle of a two chan song and it was on a regular 83+. It was just stopping/exiting, but still actions.