This is one of Namco's NES mappers, with up to 8 wavetable channels. It has also 128 byte of internal RAM, and both channel register and wavetables are stored here. Wavetables are variable size and freely allocable anywhere in RAM, it means it can use part of or continuously pre-loaded waveform and its sequences in RAM. But waveform RAM area becomes smaller as more channels are activated; as channel registers consumes 8 bytes for each channel. You must avoid conflict with channel register area and waveform for avoid broken channel playback.
Furnace supports loading waveforms into RAM and waveform playback simultaneously, and channel limit is dynamically changeable with effect commands.
You must load waveform to RAM first for playback, as its load behavior auto-updates when every waveform changes.
Both waveform playback and load command works independently per each channel columns, (Global) commands don't care about the channel columns for work commands and its load behavior is independent with per-channel column load commands.