Games on the Nintendo Entertainment System play audio using a handful of tools within the device’s Audio Processing Unit (APU). The Delta Modulation Channel (DMC) is the most expressive such tool as it can play arbitrary audio data. Any sound you’ve heard come out of a NES other than variations on square and triangle waves, and noise, was played using the DMC. As its name suggests, the DMC can play delta modulated audio data, where a signal is represented by a sequence of relative changes...
