Finally … this is the ORIGINAL!!!!
Probably sometime around 1986 / 1987.
(This video from a Linux machine using Wine to run a Windows emulator which runs the BeebEm emulator for the BBC Micro. BeebEm is running MUPROC. And simulating the sound hardware)
Quora question : Who wrote the MUPROC?
Download the MUPROC disc-image (for the BeebEm)