As promised, a video of VGM playback on a MBHP_Genesis module!
There is still one issue with the frequency correction, which occasionally leads to wrong notes in certain VGM files, but I understand what the issue is and will fix it when I get a chance. Also, there's an inherent incompatibilty between the noise channel in the SN76489 and the one in the SN76489-clone used in the actual Mega Drive / Genesis (shift register length and therefore pitch, and also what happens with zero frequency). I may be able to have the software correct for it in certain cases, but it's not a huge deal overall.