Namco WSG
 Namco
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| Manufacturer(s) | Namco |
| Designer(s) | Unknown (ASICs) |
| Release Date(s) | 1980 |
| Type(s) | 4-bit Wavetable |
| Amount of channels | 1 (mono, PCB and 15xx), 2 (stereo, 30) |
| Amount of voices | 3 (PCB), 8 (ASICs) |
| VGM support | None |
The Namco WSG is a custom wavetable synthesis hardware used in every Namco arcade system from Pac-Man to System 1. The original 3-voice version is a printed circuit board, while later arcade systems condensed it to a chip that has a total of 8 voices and with a 4-digit part number starting with "15". Both the 3-voice 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 128 bytes.
CUS30
The CUS30, 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