Pan Docs

The community-maintained technical reference for the game-boy, published by the gbdev community at gbdev.io/pandocs from the GitHub repository gbdev/pandocs and released into the public domain (CC0 1.0). Its audio section — three pages, Audio Overview, Audio Registers and Audio Details — is this wiki's register-level source for the game-boy-apu, the counterpart of the datasheet material behind sid. The detailed APU diagram is credited to Lior "LIJI32" Halphon, and many claims cite SameSuite test ROMs as evidence (sources: s-pandocs-audio-overview, s-pandocs-audio-registers, s-pandocs-audio-details).

What the audio section covers#

• Overview (s-pandocs-audio-overview): the four specialised channels and VIN, the shared concepts — triggering, envelope (64 Hz), length timer (256 Hz), period values instead of frequencies — and the Super Game Boy 1's 2.4 % pitch error.
• Registers (s-pandocs-audio-registers): NR10–NR52 and wave RAM bit by bit, with the pitch formulas (pulse 131072 ÷ (2048 − v), wave 65536 ÷ (2048 − v), noise clock 262144 ÷ (divider × 2^shift)), the four duty cycles, the wave output levels and the LFSR modes.
• Details (s-pandocs-audio-details): DACs, mixer and high-pass filter (why things pop), the sweep unit, duty-step and sample-buffer internals, the LFSR and its lock-up, Game Boy Advance differences and a list of obscure behaviours ("zombie mode" volume control, DMG wave-RAM corruption).

Only the audio section is in raw/pandocs/ (fetched 2026-08-30 from the master branch; the three files were last changed in June, October and July 2025). Pan Docs also documents the CPU, memory map, PPU, cartridges, link port and Super Game Boy — not ingested.

Related#

game-boy-apu · game-boy · lsdj

Sources#

s-pandocs-audio-overview · s-pandocs-audio-registers · s-pandocs-audio-details