Namco WSG
 Namco
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| Manufacturer(s) | Namco |
| Designer(s) | Unknown (ICs) |
| Release Date(s) | 1980 |
| Type(s) | 4-bit Wavetable |
| Amount of channels | 1 (mono, 3-voice and 15xx), 2 (stereo, 30), 4 (quad, Pole Position) |
| Amount of voices | 3 (original PCB), 8 (Pole Position, ICs) |
| VGM support | None |
The Namco WSG is a custom wavetable synthesizer used in every Namco arcade system from Pac-Man to System 1. The original 3-voice version is in the form of circuitry on the top-right corner of the main board, while Pole Position expanded it to 8 voices. A later version of the synthesizer was made in the form of a chip that has a total of 8 voices and with a 4-digit part number starting with "15". Both the PCBs and 15xx get their waveforms from 128 bytes of dedicated ROM supplied to them. Each waveform is 4-bit and a length of 32, and each ROM comes with 8 waveforms which are a total of 256 steps, or 128 bytes as each step is a 4-bit value.
CUS30
The CUS30, N30, or just "30", is an improvement of the 15xx. The 30 is stereo, reads from 256 bytes of RAM instead of ROM (holds up to 16 waveforms and can be changed in-game), and has a noise mode for each voice. The noise mode is clocked based on the lower 8 bits of the 20-bit frequency register.
The internal workings
https://www.youtube.com/watch?v=csFwHrQEdbg
Links
https://github.com/mamedev/mame/blob/master/src/devices/sound/namco.cpp