Editing Delta modulation (section)

=== Video game sound effects ===
The [[Nintendo Entertainment System]]'s audio processing unit (the [[Ricoh 2A03]] chip) includes a Delta Modulation Channel (DMC) to demodulate percussion and sound effects. The DMC reads delta-encoded audio data via [[direct memory access]] into a [[shift register]], which gets shifted out [[Serial communication|serially]] into an [[up/down counter]] acting as the demodulator's integrator. Because the shift register is clocked by a configurable timer, the audio's frequency can be shifted by adjusting the playback speed. The counter's value is outputted though a 7-bit [[digital-to-analog converter]] (DAC). Note: writing PCM samples directly to the counter bypasses the DM demodulation to instead provide low-bit PCM output.<ref>{{Cite journal |last=Collins |first=Karen |date=2007 |title=In the Loop: Creativity and Constraint in 8-bit Video Game Audio |url=https://www.cambridge.org/core/journals/twentieth-century-music/article/abs/in-the-loop-creativity-and-constraint-in-8bit-video-game-audio/13249E23669D3D386D2B505A96239453 |journal=Twentieth-Century Music |language=en |volume=4 |issue=2 |pages=214 |doi=10.1017/S1478572208000510 |issn=1478-5730}}</ref><ref>{{Cite web |title=NES APU Sound Hardware Reference |url=https://www.nesdev.org/apu_ref.txt}}</ref><ref>{{Cite web |last=Taylor |first=Brad |date=2004-04-23 |title=2A03 technical reference |url=https://www.nesdev.org/2A03%20technical%20reference.txt}}</ref>