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)
Bubble System 2 channel Wavetable sound generator logic is configuration with K005289, 4 bit PROM and DAC.
K005289 controls pitch and 5 bit address generator per channel, Waveform select and Volume control is tied to AY-3-8910 ports. (each port for per channels)
these configuration is better known as K005289, the part of logic.
furnace emulates this configurations as single system, waveform format is 15 level and 32 width.
its 16 channel wavetable/PCM chip, with (optional) stereo support.
Its also has envelope, this feature has similar as AY PSG's one but its shape is also stored at RAM, and each nibble in envelope data is for each output: so i decided to added some feature for more stereo-ish envelope.
Split: Envelope shape will be splitted to Left and Right half for each output.
HInv, Vinv: Envelope shape will be Horizontally/Vertically mirrored the left one.
Max sample length is sample bank size of Seta 2 arcade hardware (currently not emulated yet, nor it doesn't support on VGM).
Chip id is temporary, it can be changed with to suggestions.
Allow 8 bit volume for YM2610 ADPCM-B
Remove sample mode macro in YM2610, it's always enabled and seperated channels.
TODO: ADPCM-B is still not implemented, FM Channel 2 is silenced in extended channel 3 configuration
as of now compound systems (Genesis and Arcade) are translated to
separate chips.
this improves audio quality and makes things easier.
it also allows you to change the volume of each chip on a Genesis.
also adds SegaPCM system with 16 channels!
