Williams Sound Explorer & Designer (WSED)

This explorer emulates the original Williams arcade sound ROMs (Defender 1980, Stargate 1981, Robotron 2084 1982). Those ROM images are © Williams Electronics and are not distributed here — supply your own copy below.

🔒 Files are read in your browser only and stored locally (IndexedDB) — nothing is uploaded to any server. You need the sound ROM for each game (from a MAME romset you're licensed to use, or dumped from your own board). You can also build them from source with tools/build_roms.sh. Drop a file on a slot — the app checks it and shows its SHA-1.

Add at least one ROM to continue.

Williams Sound Explorer & Designer (WSED)

Engine view per-routine inner state
Engine state & toggles

The active sound's engine state. LFSR (LITE) also surfaces in the Code panel above; VARI shows duty-cycle bars; GWAVE shows the live 72-byte wavetable + sample cursor.

Toggles:
ORGAN — polyphonic tune (OSCIL voices + RDELAY)
OSCIL: checked = muted
SCREAM — 4 detuned voices (phase + FREQ/TIMER)
Voices: checked = muted
FNOISE — slope-limited noise (FREQ vs FMAX)
GWAVE — live wavetable ($24..$6B) + sample cursor
wavetable (72 bytes) · cursor — GPER=$00 GECHO=○ GECNT=0
GWFRM=$0000 GWFRQ=$0000 FOFSET=+$00 GDFINC=+$00 PRDECA=$00 GECDEC=$00
VARI — variable-duty square wave
LOPER $00
HIPER $00
Active engine highlighted in yellow. LFSR state (LITE) appears as a textual line in the Code panel.
Spectrogram

Scrolling FFT of the post-volume signal — low freq bottom, high top. LITE's LFSR noise is a broadband upward sweep.

RAM heatmap zero-page write activity

Each cell of the sound CPU's 128-byte zero-page RAM. Red intensity fades over ~1 second since last write. Watching which cells light up while a sound plays is the cheapest way to find an engine's working set.

Glossary

Click a term to read what it means. Engine names in the cmd-info panel above are also clickable.

Explainer card algorithm walkthrough for the fired sound
Listen-then-look quiz predict the engine from the sound
A/B diff & genealogy compare sounds across games

Pick two (game, cmd) pairs and click Compare. The diff band between the two byte tapes flashes red where the streams disagree. Or click a family below to auto-load a canonical pair.

Sound family tree