While browsing I/O issues on archives.org, I stumble upon an article which seems to explain how to make a PSG (programmable sound generator) for the MZ80-B
https://archive.org/details/Io19829/page/n257
PSG for MZ80-B
Re: PSG for MZ80-B
I try starting build PCBs for the "B" ... prior I did this for the RC2014, but now I try to start with a simple card for the B