https://little-scale.blogspot.com/2009/09/simultaneous-sn76489-and-ym2413-midi.html?showComment=1252653843401
little-scale: Simultaneous SN76489 and YM2413 MIDI Support
I've added simultaneous support for the SN76489 and the YM2413 sound chips for the Sega Master System MIDI Interface.
littlescalesimultaneousmidisupport
https://drive.google.com/file/d/1zvE9XgX8Ss2tV-MxTlEBvqOqCR-uMBBi/view?usp=sharing
YM2413-MDB.pdf - Google Drive
mdbpdfgoogledrive