Arcade-Darius_MiSTer

FPGA core for Darius (Taito Corporation, 1986) targeting the MiSTer FPGA platform (Terasic DE10-Nano).

Darius runs on a dual 68000 + Z80 ×2 board with two PC080SN tile layers, PC090OJ sprites, PC060HA master/slave communication, and YM2203 ×2 + MSM5205 audio, driving the game's signature triple-screen ultra-wide display. This core reimplements the hardware in SystemVerilog from MAME references and hardware observation on original PCBs.

About the game

Darius is Taito's landmark horizontal shoot-'em-up, famous for its three-monitor ultra-wide screen and its all-aquatic-themed mechanical bosses. You pilot the Silver Hawk starfighter through a branching tree of zones (pick your path at the end of each stage), fighting waves of enemies to a memorable Zuntata soundtrack, with the iconic "Warning!! A huge battleship is approaching" boss cadence. The board composes three horizontal panels into one continuous 864-pixel-wide playfield.

Status

Current version: 1.8 (July 2026)

The core runs the full game end-to-end on all supported ROM sets and has been tested on real MiSTer hardware. Since v1.1 the audio path, the sprite engine and the video/CRT tooling have been substantially reworked, and an experimental savestate system (16 slots) has been added.

What's new in v1.8

• Sprite engine fixes — the sprite object RAM is now double-buffered and latched at vblank (buffered sprite RAM, like the original hardware). This removes a rare but real defect where a mid-frame CPU update of the sprite list produced inconsistent scanlines (part of the screen using the old sprite data, part the new). Line preparation was also reworked with a shadow-scan FIFO and a small sprite-ROM cache to reduce SDRAM contention.
• Audio mixer rework — a new per-channel mixer (9 channels: FM ×2, PSG/SSG ×6, MSM5205 ADPCM) with per-channel volume and pan exposed in the OSD, a linear/transparent gain chain and a final soft-clip stage sized on the real worst case (no more square-wave saturation when many voices sum). The ADPCM ROM was moved into BRAM for deterministic latency, and various sound path fixes improve accuracy.
• Experimental savestate — 16 slots — full video / CPU state plus a deterministic audio restore. Select the slot from the OSD. Still experimental: see Known issues.
• CRT Adjust module — a core-side analog CRT alignment tool (validated and released, see the dedicated section below), bringing H-Size, H-Position and V-Shift together in one line-buffer module that never desyncs the CRT. Alongside it, an experimental set of single-screen views for the triple screen — Screen Jump, triple-screen wide and a follow-cam mode that tracks the Silver Hawk — opt-in from the OSD.
• DSP / BRAM optimizations across the audio mixer and video path.

Known issues (v1.8)

• Savestate is experimental. It works across the 16 slots but is not guaranteed solid in every situation; loading a state saved by an older build is not supported. Kept under observation.
• Experimental single-screen views — the triple-screen views (Screen Jump, wide zoom, follow-cam) are opt-in and still being refined. (CRT Adjust itself — H-Size / H-Position / V-Shift — is validated and released, not experimental.)
• 15 kHz CRT output — the native 864-pixel triple-panel resolution is hard on the MiSTer analog I/O board, but the new experimental CRT views (wide zoom, Triple CRT Wide, follow-cam) make 15 kHz usable — a lot more than before. The single-screen follow-cam / wide modes in particular give a proper CRT-friendly picture. This is via experimental features and not yet guaranteed in every mode.

Milestones reached

• Boots and plays the full game with accurate video and controls on all sets
• Dual 68000 main/sub with shared RAM (FX68K core), PC060HA master/slave communication reproduced from MAME
• Three horizontal panels composed into the continuous 864-pixel screen
• Sprite renderer with priority, flip, 16×16 4bpp tiles, buffered (vblank-latched) sprite RAM, shadow-scan FIFO and sprite-ROM cache
• FG text / HUD layer with local BRAM text ROM
• Palette with MAME-verified byte order
• Full audio chain: YM2203 ×2 (FM + SSG/PSG) + MSM5205 ADPCM, per-channel mixer with volume/pan
• Experimental 16-slot savestate (video + CPU + deterministic audio)
• CRT Adjust (validated / released) — core-side analog geometry (H-Size, H-Position, V-Shift) that never desyncs the CRT
• Experimental single-screen views for a triple-screen game — wide zoom modes (288/320/432), Screen Jump, Triple CRT Wide, and a follow-cam that tracks the Silver Hawk: play the ultra-wide triple game on one monitor / CRT

Roadmap / still to implement

• Make the savestate solid enough to drop the "experimental" tag
• Finish and stabilize the single-screen / follow-cam views
• Optional high-score saving (NVRAM) — under evaluation, deliberately non-invasive (no CPU pause), not in this release

Features

• Dual 68000 main/sub @ 8 MHz with shared RAM (FX68K core)
• Two Z80 sound CPUs (music + ADPCM/FX)
• Three horizontal panels composed into the 864-pixel virtual screen
• Sprite renderer with priority, flip, 16×16 4bpp tiles, buffered sprite RAM
• FG text/HUD layer with local BRAM text ROM
• Palette with MAME-verified byte order
• Audio: YM2203 ×2 (FM + PSG) + MSM5205 ADPCM with per-channel volume/pan mixer
• PC060HA main/sub communication
• SDRAM arbitration for tile/sprite ROM and main/sub CPU fetch
• Experimental savestate (16 slots) from the OSD
• CRT Adjust (H-Size / H-Position / V-Shift) — validated and released
• Experimental single-screen views (Screen Jump, triple wide, follow-cam)
• Inputs (coin, start, 8-way joystick) and full DIP switch support
• MiSTer OSD with video, audio-mix, pause and DIP options
• Pause overlay with project logo, scrolling supporters list and social links
• "Clean Pause" OSD option (pause without dim/logo overlay)

ROM sets supported

• Darius (World) — reference set
• Darius (US)
• Darius (Japan rev 1 — dariusj)
• Darius (Japan pure — dariuso)
• Darius Extra Version (dariuse)

CRT Adjust

CRT Adjust is a core-side analog CRT geometry / alignment tool exposed in the OSD — validated and released (not experimental). It is the evolution of the earlier "Analog H-Size" module: a single always-on line buffer that provides three live controls for lining the image up perfectly on a real CRT.

Control	What it does
H-Size	Horizontal stretch / squeeze — bidirectional, integer (every source pixel is emitted for a whole number of pixel clocks)
H-Position	Horizontal image shift — moves the picture content, not the sync
V-Shift	Vertical line shift

Why it never desyncs the CRT. The picture content is shifted and resized through the line buffer while the horizontal/vertical sync signals stay native. The CRT keeps its lock at all times, so you can slide and resize the image live without the screen rolling or losing hold — unlike moving the blanking / sync windows.

Because the resize is integer (no fractional ratio, no per-pixel nearest-neighbor) and the output is the byte-exact source pixel, there is no shimmering on moving content and no blending / blur — the image stays sharp while you stretch it.

The module is inserted core-side at the video-output boundary, with zero sys/ framework changes (MiSTer-devel compliant — the framework is never modified). The trade-off is that the adjustment reaches the analog DAC and HDMI follows it too: leave CRT Adjust Off (default) for an untouched HDMI image, and turn it on when aligning on an analog CRT. Cost is about 1 M10K, ~50 ALM, 0 DSP.

Triple-screen views, wide zoom & follow-cam (experimental)

Darius is a three-monitor game: its native picture is an 864-pixel-wide triple panel. On a single modern display that means a very wide, short image. This core adds a unique set of display modes — as far as we know nothing else on MiSTer does this — that reshape the triple screen for a single monitor without touching the game logic and while keeping the native 15.7 kHz line rate (so it stays CRT-friendly and never desyncs).

The picture is captured after the compositor, buffered per line (lossless), and re-emitted into a wider active window with integer pixel repeat — so the image genuinely grows on a CRT with no blur and no shimmer.

Mode	What you get
Triple	Native triple panel (864 px) — bypass, unchanged
Wide 288 ×4	Single-panel window, panel proportions, zoomed
Wide 320 ×4	"4:3-pushed" window (1280 active slots)
Wide 432 ×3	~1.5-screen window (1296 active slots)
Screen Jump	Single-panel view that jumps panel-to-panel with the action
Triple CRT Wide	Native triple re-emitted at a wider integer rate (864 active over ~1018 slots) so the whole triple screen fills a CRT line — integer 1:1 repeat, no scaling

• Follow-cam — instead of showing all three panels, the view becomes a single zoomed screen that follows the Silver Hawk: the camera tracks the ship (deadzone + smooth slew, updated at end of vblank) and eases back to the playfield center when the ship is absent (title / death). It turns the ultra-wide triple game into a normal-proportioned single-screen experience you can actually play comfortably on one monitor / CRT.

All of the above are experimental, opt-in from the OSD, and leave the default Triple view untouched.

Screenshots

Title screen	Attract — Silver Hawk briefing
Zone C	Zone I
Zone S	Zone G

Hardware emulated

Component	Spec
Main CPU	Motorola 68000 @ 8 MHz (FX68K)
Sub CPU	Motorola 68000 @ 8 MHz (FX68K)
Sound CPU	Z80 ×2 (music + ADPCM/FX)
Sound chip 1	Yamaha YM2203 OPN ×2 — FM + SSG/PSG (jt12)
Sound chip 2	OKI MSM5205 ADPCM (jt5205)
Tilemaps	Taito PC080SN ×2 (two scrolling tile layers)
Sprites	Taito PC090OJ (16×16 4bpp, buffered sprite RAM)
Comms	Taito PC060HA (master/slave)
Display	Triple horizontal panels → 864×224

Hardware requirements

• Terasic DE10-Nano
• MiSTer I/O board (recommended)
• SDRAM module (128 MB, 64 MB or 32 MB)
• HDMI display (recommended), or HDMI→VGA adapter for 31 kHz VGA monitors

Note on video output: The core works on standard HDMI displays. For 31 kHz VGA monitors, use an HDMI→VGA adapter — do not enable Direct Video. 15 kHz CRT output is not currently supported because the 864×224 triple-panel resolution is incompatible with the MiSTer analog I/O board.

Build from source

Requires Quartus Prime Lite 17.0.x for Cyclone V (5CSEBA6U23I7).

cd Arcade-Darius_MiSTer
quartus_sh --flow compile Darius -c Darius

Output: output_files/Darius.rbf (~3.9 MB).

Running on MiSTer

The releases/ folder contains the pre-built bitstream and the parent MRA for the reference ROM set:

• Darius_YYYYMMDD.rbf — pre-built core bitstream
• Darius (World).mra — parent MRA (reference set)

Alternative ROM sets are provided in releases/alternatives/:

• Darius (US).mra
• Darius (Japan).mra
• Darius (Japan, rev 1).mra
• Darius Extra Version (Japan).mra

Following the MiSTer-devel convention, the alternative sets are also mirrored to the official MRA-Alternatives_MiSTer repository, where they are picked up automatically by Update_All.

Steps:

1. Copy the .rbf to _Arcade/cores/ on the MiSTer SD card.
2. Copy the desired .mra file(s) to _Arcade/ on the MiSTer SD card.
3. Provide your legally-owned Darius ROM files where each MRA expects them (usually in games/mame/).
4. For HDMI displays, no special setup is required. For 31 kHz VGA monitors, use an HDMI→VGA adapter (do not enable Direct Video). 15 kHz CRT output is not currently supported (see Hardware requirements).
5. The core OSD defaults to Narrower HV-Integer scale, which gives a proper integer-scaled image on modern HDMI displays. Other Scale options (V-Integer, HV-Integer) are available for custom setups.

ROMs are NOT included in this repository. You must provide them yourself.

Repository layout

Arcade-Darius_MiSTer/
├── rtl/
│   ├── darius/       Darius-specific core RTL (Umberto Parisi)
│   ├── fx68k/        M68000 core (Jorge Cwik)
│   ├── jt12/         YM2203 FM synth (Jose Tejada)
│   ├── jt5205/       MSM5205 ADPCM (Jose Tejada)
│   ├── jtframe/      JTFRAME framework modules (Jose Tejada)
│   ├── t80/          Z80 core
│   ├── pll/          Clock PLL
│   └── sdram.sv      SDRAM controller (Sorgelig)
├── sys/              MiSTer framework (Sorgelig / MiSTer-devel)
├── releases/         Pre-built .rbf + parent MRA
│   └── alternatives/ MRA files for alternate ROM sets
├── docs/             Screenshots
├── Darius.qpf        Quartus project
├── Darius.qsf        Quartus assignments
├── Template.sv       Top-level wrapper
├── Template.sdc      Timing constraints
├── files.qip         HDL file list
├── build_id.v        Build version stamp
├── LICENSE           GNU GPL v3
├── AUTHORS.md        Credits and third-party licenses
└── README.md         This file

License

Distributed under GNU General Public License v3 or later. See LICENSE and AUTHORS.md for credits and third-party licensing.

GPL-3 is chosen to stay compatible with upstream GPL-3 dependencies (JTFRAME, FX68K, Sorgelig's sdram and sys framework).

Acknowledgements

• Jorge Cwik — FX68K (M68000 core)
• Jose Tejada (@jotego) — JTFRAME, JT12 (YM2203), JT5205 (MSM5205)
• Sorgelig and the MiSTer-devel team — framework, SDRAM controller and Template
• Andrea Bogazzi (@asturur) — help with the core-side CRT Adjust / Analog H-Size implementation
• The MAMEDev team — invaluable reference on the Taito PC080SN / PC090OJ / PC060HA hardware, memory maps and timing

Full list in AUTHORS.md.

Support this project

If you enjoy this core and want to support its development:

• Ko-fi — one-time support
• Patreon — monthly support
• PayPal — one-time donation

Follow

• GitHub
• Twitch — live streams
• YouTube — playlists and videos
• X / Twitter

Original Darius arcade hardware © Taito Corporation, 1986.