Love some of the sounds coming out of this; would be great to get a circuit diagram to get a better idea of how this is hooked up. Is every output of the decad

Love some of the sounds coming out of this; would be great to get a circuit diagram to get a better idea of how this is hooked up. Is every output of the decade counter being used or just a single output making it a frequency divider (and other questions)? If I understand correctly, the Gameboy is running a sequencer, presumably outputting to the speaker, so how is that hooked into the leached information from the various parts of the Gameboy?