 Two notable examples of systems employing this technology comprise the Nintendo Game Boy portable game console, and the Commodore 64 personal computer.The Game Boy uses two pulse channels (switchable between 12.5%, 25%, 50% and 75% wave duty cycle), a channel for 4-bit pulse-code modulation (PCM) playback, and a pseudo-random-noise generator.The Commodore 64, however, used the MOS Technology SID chip which offered 3 channels, each switchable between pulse, saw-tooth, triangle, and noise.