Changes
PSG
,/* Block Diagram */
Also, note that period = 0 is the same as period = 1. This is mentioned in the YM2203 datasheet. However, this does NOT apply to the Envelope period. In that case, period = 0 is half as period = 1. [https://github.com/mamedev/mame/blob/master/src/devices/sound/ay8910.cpp Source] (Does this last sentence apply only to the SSG or to the PSG as well?)
And much like the CRTC chip, the counters never stop counting. The tones, the noise, and envelope are never halted. All of them are continually active whether or not they're connected to an audible output.
Things that have been verified not to halt things: [https://forums.nesdev.org/viewtopic.php?p=236745#p236745 Source]
