GM programs 0-15
Pulse, 50% duty
Envelope
Spectrum
- Attack
- 3 ms
- Decay
- 98.8 ms
- Release
- 1.9 ms
- Peak / RMS
- -14.1 / -37.1 dBFS
- Spectral centroid
- 1028 Hz
- Noise vs. tone
- tonal
MACHINE
Famicom Ricoh 2A03
Thin, bright square waves and a gritty noise channel - the sound of the earliest home consoles.
ITS VOICES
How it makes sound.
The Ricoh 2A03 has five voices: two pulse (square) wave channels, one triangle wave channel, one noise channel, and one channel that plays short sampled hits.
chipvoice uses the two pulse channels for melody and chords, the triangle for bass, and the noise and sample channels for drums.
HEAR EVERY PRESET
Its instruments.
Every preset a user can pick for this chip - played as one fixed probe, measured, never typed by hand.
Melody
GM programs 16-127
Pulse, 25% duty
Envelope
Spectrum
- Attack
- 4.5 ms
- Decay
- 97.3 ms
- Release
- 0.4 ms
- Peak / RMS
- -14.4 / -37.3 dBFS
- Spectral centroid
- 1109 Hz
- Noise vs. tone
- tonal
GM programs 32-39
Tone
Envelope
Spectrum
- Attack
- 3 ms
- Decay
- 3 ms
- Release
- 3.4 ms
- Peak / RMS
- -15.5 / -28.2 dBFS
- Spectral centroid
- 1036 Hz
- Noise vs. tone
- tonal
GM programs 40-87
Pulse, 25% duty
Envelope
Spectrum
- Attack
- 4.5 ms
- Decay
- 1.5 ms
- Release
- 0.4 ms
- Peak / RMS
- -15.7 / -28.4 dBFS
- Spectral centroid
- 1109 Hz
- Noise vs. tone
- tonal
GM programs 56-63
Pulse, 12.5% duty
Envelope
Spectrum
- Attack
- 3 ms
- Decay
- 3 ms
- Release
- 0.4 ms
- Peak / RMS
- -15.9 / -29.3 dBFS
- Spectral centroid
- 1392 Hz
- Noise vs. tone
- tonal
Chords
GM programs 0-15
Pulse, 50% duty
Envelope
Spectrum
- Attack
- 3 ms
- Decay
- 98.8 ms
- Release
- 1.9 ms
- Peak / RMS
- -14.1 / -37.1 dBFS
- Spectral centroid
- 1028 Hz
- Noise vs. tone
- tonal
GM programs 16-127
Pulse, 25% duty
Envelope
Spectrum
- Attack
- 4.5 ms
- Decay
- 97.3 ms
- Release
- 0.4 ms
- Peak / RMS
- -14.4 / -37.3 dBFS
- Spectral centroid
- 1109 Hz
- Noise vs. tone
- tonal
GM programs 32-39
Tone
Envelope
Spectrum
- Attack
- 3 ms
- Decay
- 3 ms
- Release
- 3.4 ms
- Peak / RMS
- -15.5 / -28.2 dBFS
- Spectral centroid
- 1036 Hz
- Noise vs. tone
- tonal
GM programs 40-87
Pulse, 25% duty
Envelope
Spectrum
- Attack
- 4.5 ms
- Decay
- 1.5 ms
- Release
- 0.4 ms
- Peak / RMS
- -15.7 / -28.4 dBFS
- Spectral centroid
- 1109 Hz
- Noise vs. tone
- tonal
GM programs 56-63
Pulse, 12.5% duty
Envelope
Spectrum
- Attack
- 3 ms
- Decay
- 3 ms
- Release
- 0.4 ms
- Peak / RMS
- -15.9 / -29.3 dBFS
- Spectral centroid
- 1392 Hz
- Noise vs. tone
- tonal
Bass
GM programs 0-127
Tone
Envelope
Spectrum
- Attack
- 6 ms
- Decay
- 0 ms
- Release
- 4.9 ms
- Peak / RMS
- -20.2 / -26.5 dBFS
- Spectral centroid
- 363 Hz
- Noise vs. tone
- tonal
Drums
Kick
Tone
Envelope
Spectrum
- Attack
- 7.5 ms
- Decay
- 142.2 ms
- Release
- 0.4 ms
- Peak / RMS
- -17.8 / -39.6 dBFS
- Spectral centroid
- 3914 Hz
- Noise vs. tone
- mixed
Snare
Tone
Envelope
Spectrum
- Attack
- 9 ms
- Decay
- 157.1 ms
- Release
- 0.4 ms
- Peak / RMS
- -18.4 / -40.9 dBFS
- Spectral centroid
- 2504 Hz
- Noise vs. tone
- mixed
Hi-hat
Noise
Envelope
Spectrum
- Attack
- 7.5 ms
- Decay
- 109.3 ms
- Release
- 0.4 ms
- Peak / RMS
- -23.4 / -52.8 dBFS
- Spectral centroid
- 1460 Hz
- Noise vs. tone
- mixed
Open hi-hat
Noise
Envelope
Spectrum
- Attack
- 18 ms
- Decay
- 181.1 ms
- Release
- 0.4 ms
- Peak / RMS
- -21.9 / -44.4 dBFS
- Spectral centroid
- 1541 Hz
- Noise vs. tone
- mixed
HOW WE CHECK
Its evidence.
How closely this chip's emulation matches the real hardware, from the conformance harness that runs before each release.
Digital parity
Compared with Nes_Snd_Emu 0.1.7 (blargg): 3.9 % identical (3,577,340 of 92,173,307 cycles), 13 of 13 logs with any divergence.
First divergence: script-dmc, cycle 0, tri - ours 15, the oracle's 0.
Compared with Mesen 2 (b9fa69d, 2026-06-04): 65.8 % identical (60,662,173 of 92,173,307 cycles), 13 of 13 logs with any divergence.
First divergence: script-dmc, cycle 0, tri - ours 15, the oracle's 0.
Test ROMs
29 of 29 test ROMs pass.
- apu_test/1-len_ctr: pass
- apu_test/2-len_table: pass
- apu_test/3-irq_flag: pass
- apu_test/4-jitter: pass
- apu_test/5-len_timing: pass
- apu_test/6-irq_flag_timing: pass
- apu_test/7-dmc_basics: pass
- apu_test/8-dmc_rates: pass
- apu_reset/4015_cleared: pass
- apu_reset/4017_timing: pass
- apu_reset/4017_written: pass
- apu_reset/irq_flag_cleared: pass
- apu_reset/len_ctrs_enabled: pass
- apu_reset/works_immediately: pass
- dmc_tests/buffer_retained: pass
- dmc_tests/latency: pass
- dmc_tests/status: pass
- dmc_tests/status_irq: pass
- apu_2005/01.len_ctr: pass
- apu_2005/02.len_table: pass
- apu_2005/03.irq_flag: pass
- apu_2005/04.clock_jitter: pass
- apu_2005/05.len_timing_mode0: pass
- apu_2005/06.len_timing_mode1: pass
- apu_2005/07.irq_flag_timing: pass
- apu_2005/08.irq_timing: pass
- apu_2005/09.reset_timing: pass
- apu_2005/10.len_halt_timing: pass
- apu_2005/11.len_reload_timing: pass
Analog stage
The mixer is measured against a real console's own recordings; the output filters are not measured yet.
- square: -32.7 dB (console -32.2 dB)
- triangle: -33.0 dB (console -30.9 dB)
- noise: -13.8 dB (console -16.2 dB)
- dmc: -31.0 dB (console -27.2 dB)
Driver coverage
The shipped driver reaches 4 of the chip's 5 voices.