So, Atari ST started to talk with OPL2 Audio board :) https://www.youtube.com/watch?v=Rs20GDzk2n4&ab_channel=nokturnal not ideal, but at least sounds better than complete silence or noise. Device turned out to be not 100% SPI compliant and CS (\WR on screenshot) is used as a latch for indicating byte transfer is complete (\WR set to low and then high for brief period). Also address line A0 and \IC (Reset) is active low. SPI CLK and MOSI other way around. #atarist #opl2 #YM3812 #opl2audioboard