Namco WSG
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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, discrete and 15xx), 2 (stereo, CUS30) |
Amount of voices | 3 (discrete), 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 discrete circuitry, while later arcade systems condensed it into 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 CUS30 is stereo, reads from 256-byte 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