Sorry for too long preface/introduction ;) but it was my very _first_ contact with ZXpand module for ZX81 computer (32Kb or RAM, SD-card instant loading plus additional AY-interface in standard of classic ZX81′s ZonX AY-interface from 80s).
It is really ZX81 playing music via AY chip (well, actually its Japanese version: YM). You can get both modules from RWAP Software: http://www.rwapsoftware.co.uk/zx812.html
via ZX81 computer with AY-interface & ZXpand Module. – YouTube.
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