Editing Commodore 64C (section)

== Sound – SID 8580 R5 ==
The 64C introduced the '''MOS 8580''' HMOS SID:

* Runs from '''+9 V''' (derived from the 9 VAC through a simple half-wave rectifier and 7809 regulator).  
* Significantly lower background noise than the NMOS 6581.  
* Filter curves were redesigned; many 1980s tunes written for the 6581 sound “tamer” on the 8580 unless software adjusts resonance values.  
* Paddle inputs now require 100 kΩ potentiometers (versus 470 kΩ on 6581).