About

This chip was created by Namco and contains up to eight wave channels. This chip was earlier erroneously known as Namco 106 (which is the same chip but without the audio capabilities). It was used in multiple Namco games, such as Final Lap, King of Kings, Mappy Kids and Rolling Thunder.

The chip has 128 bytes of RAM for waveform storage and channel registers. Each channel can use a wave size from 4 to 256 steps, with adjustable wave RAM position either through the instrument settings or the Zxx command.

This chip has up to 8 channels available, configurable from the module properties dialog. All channels are clocked sequentally by the chip, so the pitch range will depend on the channel count: a lower number of channels means less time taken by channels to update, which means each channel has an extended top pitch range. More channels will also increase the effects of aliasing since this chip uses phase accumulation for tone generation.

The DAC is also shared by all channels in the same sequential manner. The rate for this channel switching is around 120 kHz, which means that when all 8 channels are enabled, there will be audible channel switching noise at 15 kHz (or 17 kHz when 7 channels are enabled). Some Namco carts do have a LP filter to deal with this, but it did little to alleviate the high pitched noise, so it's still very audible. To avoid this, either disable multiplexing in the emulation configuration settings, or use a sufficient lowpass filter in the emulation configuration settings.

Instruments

Envelopes

Namco instruments has an envelope editor that behaves like 2A03, with the exception for an extra wave setting.

See 2A03 instruments for more information.

Wave

This tab is used to define waves for the instrument, the wave editor is the same as used for FDS except that only 16 levels are available and the wave size is customizable. Like for FDS, a few presets are available.

Up to 64 different waves can be stored in the same instrument, and the wave to actually use is controlled by the wave envelope setting or the Vxx effect. Only one wave is uploaded the the wave memory at a time.

The location in the wave memory is customizable, and the user is responsible for being sure that no instruments tries to use the same memory position simultaneously! For example, two instruments that uses wave position 0 cannot be used at the same time, but can be used at different times. Two instruments that uses wave position 0 and 32 can be used simultaneously.

The instrument editor will suggest wave positions depending on the wave size.

Also be aware that the pitch table is calculated with 32 steps waves in mind, so waves that are not a power of two in size will be out of tune.