genmddj v0.14

Native SEGA music tracker targeting YM2612 and SN76489 sound chips. Under active development. Tested under emulation via Genesis Plus as well as PAL and NTSC SEGA Mega Drive, Genesis and Nomad via flashcart.

Two headline features this release, both hardware-verified.

GROUP — one line, three voices
A TONE instrument played on T1 can now drive T2 and T3 for fat sounds from a single melody line:

• UNISON1/2 — detuned unison (±1/±2 on the tone register)
• FIFTH, POWER (fifth + octave), OCTAVE1/2
• CHORD — the C command sets the T2/T3 semitone offsets (high nibble T2, low nibble T3; latched)

T2/T3 follow T1's envelope/sweep/vibrato, with RD1/RD2 to pull their levels back. See MANUAL §5.

Region-aware playback (OPTIONS)
The region setting is split into VIDEO (refresh rate → tempo + display mode) and CLOCK (sound-chip crystal → pitch). AUTO detects the console, and the two are independent — so a PAL-60 mod (60 Hz video + PAL crystal) plays both in time and in tune. PAL, NTSC and modded consoles are all covered.

Also

• Instrument patcher shows the patch index in hex (matches the console).
• PSG squares standardised to T1–T3 across the docs and tools.

Full details in CHANGELOG.md. Flash genmddj-v0.14.bin to a Mega Drive flashcart or open it in an emulator.

genmddj v0.12

A maintenance release focused on the PSG voices, the command set, and editor ergonomics.

Highlights

• Noise pitched mode fixed — notes in the NO track now clock the noise from tone 2 (periodic + white).
• Macro tables keep running through a note's decay/tail instead of freezing when the volume hits zero; DCY=0 is now a quick multi-step decay (no click); K00 truly kills a note (and stops its table).
• X command now caps PSG (square + noise) level too, per-row; E is per-row; D on a tone no longer mis-pitches.
• Editor niceties — new table V / CMD cells inherit the last value entered; double-tap window widened to ~0.4 s and double-tap on an empty reference cell mints a fresh blank chain/phrase.
• OPTIONS value column aligned; AUDITION is now a toggle box.
• LIVE mode shows an X on a track queued to stop at chain end.

Full details in CHANGELOG.md.

Flash genmddj-v0.12.bin to a Mega Drive flashcart or open it in an emulator.

genmddj v0.11

genmddj v0.11

A fixes release on top of v0.1 — same tracker, several real fixes,
two of which affect playback directly.

Download: genmddj-v0.11.bin (2 MB) — drop it on a flashcart or open it in any Mega Drive
emulator. The build stamp (V0.11 902B494) is on the boot splash and OPTIONS → VER.

Highlights

• Hung / ringing notes fixed — stopping the transport (Start or C+B) now cuts every ringing
  voice: FM key-off, all PSG voices to zero, and the wave DAC stopped. Held notes (esp.
  HLD=$F) or PSG voices could previously ring on after Stop.
• PROJECT master transpose now works — it was a dead field (editable + saved, but never
  applied); it now transposes the whole song.
• FM editor: the operator AM switch moved to the end of the operator row and is drawn as
  an on/off toggle box, like the LFO screens (was a digit mid-envelope).
• Splash trimmed to ~2.0 s PAL / ~1.7 s NTSC (Start still skips it).
• PERC (YM2612 CH3 special-mode percussion) confirmed on real hardware.

Companion tools — now round-trip carts ⇄ emulators

The browser suite in user-tools/ is fully in step with the save format:

• The save tool and bank editor now read and write gzipped emulator saves (Genesis
  Plus / Bannister battery RAM) as well as raw flashcart .srm, so a song moves both ways.
  Layout detection uses the GMD1 signature; config offset + VID/SYNC labels corrected.
• Wave editor .gmdj offsets and the de-re-interleaver readout were fixed.

Full details in CHANGELOG.md.

Build 902B494 · V0.11

genmddj V0.1

genmddj V0.1 — first release

An LSDJ-inspired music tracker for the Sega Mega Drive / Genesis, driving the YM2612
FM synth (6 × 4-operator FM + an 8-bit PCM DAC) and the SN76489 PSG (3 squares + noise),
written in 68000 + Z80 assembly. It's a sibling to SMSGGDJ, the author's Master System /
Game Gear tracker.

This is the first public build. It's playable end-to-end on real hardware and in emulation —
write phrases, chain them, arrange a song, design FM voices, sequence samples, and save to the
cartridge. It's also still under active development, so there are rough edges and a couple
of known issues (below).

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Download & run

• genmddj-v0.1.bin (2 MB) — the ROM. Build 9f4a283.
• Flashcart: drop it on a Mega EverDrive (or similar) SD card and run it.
• Emulator: open it in genesis_plus_gx (Bannister / RetroArch), BlastEm, Mednafen, Kega
  Fusion, etc.
• Nothing loads or plays until you ask. The build version + git hash are on the boot splash
  and on the OPTIONS screen (VER), so you can always tell which build you're running.
• Tested on real Sega Genesis, Mega Drive, and Nomad, plus emulation. Save/load is
  hardware-verified on a real cartridge with a battery.

Start here: see MANUAL.md
for the full guide. Quick version: write a PHRASE (B-tap to drop notes), list phrases in a
CHAIN, place chains across the ten SONG columns, press Start.

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The ten voices

• F1–F6 — six YM2612 FM voices. F6 doubles as the host for PCM samples and wavetables.
• S1–S3 — three SN76489 PSG square voices.
• NO — the PSG noise voice.

What's in this build

Engine & UI

• The 68000 runs the song, the editor, and the per-tick sequencer; it diffs the chip-register
  state and pushes only the changes to the Z80, which is the sole sound-chip servant and feeds
  the PCM DAC off the YM2612's Timer A.
• The full screen set: SONG · CHAIN · PHRASE · INSTR · FM-LFO · TABLE · WAVE · GROOVE · ECHO ·
  PROJECT · OPTIONS · FILES, navigated with a context-following screen map.
• The 3-button modifier control scheme (A / B / C / Start) — no simultaneous-press timing.
• Copy / paste / clone (OPTIONS CLONE SLIM/DEEP depth), block select, and note AUDITION
  (prelisten as you enter notes; default on).

Instruments — six types

• FM — a full YM2612 four-operator voice, edited on a dedicated on-console editor (ALGO/FB,
  the chip LFO + per-channel AMS/FMS, PAN, and a 4-operator grid) with a live algorithm diagram,
  audition, and live patch editing (tweak a voice while the song plays).
• KIT — sample drum kits on the DAC; the note picks the pad. Ships with 808, 909, C78, 606
  and two SP0256-AL2 speech kits, baked with per-sample normalise → gain → tanh conditioning.
• WAVE — 16 drawable wavetables on the DAC.
• TONE / NOISE — the PSG voices (square + white/periodic noise, incl. pitched periodic-noise bass).
• PERC — YM2612 CH3 special-mode percussion (F3's four operators tuned independently for metallic / inharmonic perc; hardware-verified).
• A factory bank (32 instruments) seeds every new song; LOAD copies, SAVE-TO-BANK stashes to a
  cross-song SRAM library.

Sequencing

• The complete A–Z command set (arp, slide, bend, finetune, retrigger with decay, pan, FM
  brightness/algo/LFO, tables, hop, iteration/probability variation, tempo/groove/wait, …).
• Grooves are the clock (swing/timing); tables are a per-instrument macro sequencer
  (volume / transpose-arp / command columns); ECHO is a tempo-synced delay.
• LIVE mode — the SONG grid becomes a quantized clip launcher.
• SONG playback — Start plays the whole song from the top; C+B plays the cursor's
  contiguous block (from its top) and loops it, so gaps in a column act as separately-loopable sections.

Save / sync

• Save / load to cartridge SRAM — an RLE-compressed directory of up to 32 named songs, with a
  FILES browser, in-list rename, and PURGE (drop unused phrases/chains before saving).
• DE-9 sync over controller port 2: OUT / PULSE / IN / IN24. OUT↔IN is one clock per row
  (two-Mega-Drive tested); cross-syncs with SMSGGDJ; IN24 follows a 24-PPQN source incl.
  the Ableton Link bridge.
• DAC declick (hardware-verified) so drum hits don't pop.

Companion tools (user-tools/, browser-based)

No install — open the HTML files. Highlights:

• Instrument patcher — edit the 32 FM patches with a register-level OPN2 audition; import/
  export .gmi / .tfi / .vgi / Ableton Operator .adv; rip patches from a VGM game log.
• als2genmddj — Ableton .als & Standard MIDI .mid → .gmdj (and back), plus MML ⇄ .gmdj.
• palette + font patchers, kit/sample patcher, wave editor, save tool, SRAM
  bank editor, EverDrive de/re-interleaver.

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Known issues & caveats (first release — read me)

• Still in progress: the DAC sample feed-rate ceiling (~6–7 kHz today; higher rates pitch
  down), a couple of sync refinements (PULSE master-drive, genmddj↔SMSGGDJ cross-sync, a
  residual ≤1-frame lag), and general polish are ongoing.
• Held-FM note vs DAC (under investigation): an FM instrument set to HLD = $F (infinite
  hold) can be re-articulated on each drum hit in the emulator. It's traced to the per-beat
  68k→Z80 bus grab disturbing the YM render; whether it happens on real silicon is an open
  check (the chip is clocked independently of the bus grab, so it should be clean). Workaround:
  give that instrument any HLD other than $F.
• MIDI note-input sync is built on the console side but hidden (the ESP32-S3 wire is pending).
• Emulator vs hardware: YM2612 / Z80 / DAC behaviour can diverge from silicon — when in doubt,
  trust real hardware.

Credits

genmddj is by little-scale (Sebastian Tomczak), creator of GenMDM and SMSGGDJ — a Mega Drive
port of SMSGGDJ. Built with vasm (68k) + a Z80 driver blob and a Python build toolchain.

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Build 9f4a283 · V0.1