Chris Collins

Tools · retro

YM2149 / AY sound designer

Design sounds for the Yamaha YM2149 and AY-3-8910 (Atari ST, ZX Spectrum 128, Amstrad CPC, MSX) — three tones, noise, all 16 envelope shapes, the mixer, live registers and code export — and play or inspect .YM music files (LHA-packed YM3/YM5/YM6) and SNDH headers.

Added

How to use it

Three tabs:

  • Sound designer — set each channel’s note or period, tone/noise mix, volume or envelope, the noise period, the envelope period, and pick one of the 16 envelope shapes (drawn from the chip’s own state machine). Sound on plays the registers live; the on-screen piano or your keyboard (A W S E D F T G…, Z/X for octave) plays the chosen channel. The register panel shows R0–R13, and Export writes them as Atari ST 68000 code, Spectrum 128 Z80 or BASIC OUT`s, MSX BASIC `SOUND statements, or plain values. Choose YM2149 or AY-3-8910 for the volume curve, and the clock of your machine.

  • YM / SNDH files — drop a .YM file. Most are LHA archives (-lh5-); the tool unpacks them itself and checks the CRC. It reads YM2, YM3, YM3b, YM5 and YM6, shows the title, author, frame rate, clock and loop point, draws each channel’s pitch over the whole song, and plays it (with per-channel mute, seeking, and WAV rendering). A demo tune is built in.

  • Note table — the tone period for every note at each machine’s clock, with the tuning error in cents, and as dc.w data.

Chip notes

  • Tone: frequency = clock ÷ (16 × period), a 12-bit period in R0/R1, R2/R3, R4/R5.

  • Noise: a 17-bit LFSR clocked at clock ÷ (16 × R6), R6 being 1–31.

  • Mixer (R7): bits 0–2 turn off tone A–C, bits 3–5 turn off noise A–C. A channel’s output is the AND of its (tone or disabled) and (noise or disabled).

  • Volume (R8–R10): 0–15, or bit 4 to follow the envelope.

  • Envelope: period R11/R12, each ramp takes 256 × period ÷ clock seconds. Shape R13 bits: CONTinue, ATTack, ALTernate, HOLD; writing R13 restarts the envelope. A fast sawtooth or triangle envelope on a channel with tone off is the "sync-buzzer" bass sound.

  • The YM2149’s envelope has 32 steps (the AY’s has 16), so YM envelopes are smoother.

Limits

  • YM5/YM6 special effects (SID-voice, digidrums, Sinus-SID, sync-buzzer timers) are flagged but not reproduced — the player plays the plain register stream.

  • SNDH files hold 68000 replay code, so only their header (title, composer, year, subtunes, timer) is shown. ICE-packed SNDH files are detected but not unpacked.

  • The level curves are approximations of measured chips.

Files never leave your browser.

Sharing

Share link copies a link that carries the sound-designer patch (tone, noise, mixer, envelope, clock) and the note table’s clock, packed in ?s=. YM and SNDH files are opened from your disk and never travel in links.

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