2 Pulse channels:
- 8 level pulse duty cycle, DAC mode(just ignores duty cycle)/pulse wave mode, 4 bit volume.
- Furnace support PCM playback in pulse channels with duty cycle ignore mode.
Sawtooth:
- nothing but 6 bit volume (8 bit accumulator in technically) and 12 bit frequency (periodic).
VRC6 instrument:
- 6 bit Volume macro for finer sawtooth volume handling, also 3 bit Duty cycle macro for pulse channels.
Duty, PCM mode command and Duty macro affects for pulse channel only.
It means Custom wavetable sound generator logic on Bubble System.
It's wavetable select and volume is controlled by single AY-3-8910 IO for both channels, Another AY-3-8910 IO is used for reading sound status.
Schematics: http://pdf.textfiles.com/manuals/ARCADE/K-R/Nemesis%20[Schematics]%20[English].pdf (Nemesis, derivative of Bubble system)
