An NES Homebrew ROM that plays a bunch of waveforms that you can use to make virtual instruments. Rom tested on OpenEmu emulator, but it should run on others too.
โข Chromatic scale of each waveform played in order: 12.5% Pulse, 25% Pulse, Square, 75% Pulse, Triangle, Noise
(Click the image to watch How to Recreate Retro Game Instruments for FREE | NES, SEGA Genesis & SNES)