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.
• 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)