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The most popular expansion chip to the Famicom’s sound system. The chip has 2 pulse wave channels and one sawtooth channel. 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 actually an 8-bit accumulator, its output may wrap around. For that reason, the sawtooth channel has its own instrument type. Setting volume macro and/or pattern editor volume setting too high (above 42/2A) may distort the waveform. 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. Furnace supports this routine for PCM playback, but it consumes a lot of CPU time in real hardware (even if conjunction with VRC6’s integrated IRQ timer).

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Channel Configuration

  • 2 pulse wave channels
    • 4-bit volume
    • 8-level duty cycle
    • DAC/PCM playback capable
  • 1 sawtooth channel
    • 6-bit volume
    • Dedicated instrument type
    • Volume distortion above 42/2A

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Effects

These effects are only effective in the pulse channels:
EffectDescription
12xxSet duty cycle
Range: 0-7

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Chip Configuration

The following options are available in the Chip Manager window:
  • Clock rate: Sets the rate at which the chip will run

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Instrument Editor

This chip uses the VRC6 and VRC6 (saw) instrument editors.

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