16 lines
812 B
Markdown
16 lines
812 B
Markdown
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# Konami VRC6
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Its one of NES mapper with sound expansion, and one of two VRCs with this feature by Konami.
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The chip has 2 pulse wave channel and single sawtooth channel.
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volume register is 4 bit for pulse wave and 6 bit for sawtooth, but sawtooth output is corrupted when volume register value is too high. because this register is 8 bit accumulator in technically, its output is wraparoundable.
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pulse wave duty cycle is 8 level, it can be ignored and it has potential for DAC at this case: volume register in this mode is DAC output and it can be PCM playback through this mode.
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Furnace supports this routine for PCM playback, but it's consume a lot of CPU resource in real hardware.
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# effects
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- `12xx`: set duty cycle. (0 to 7)
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- `17xx`: toggle PCM mode.
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* All effects are affects at pulse channels only.
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