Arcade-GundamSD_MiSTer

FPGA core for SD Gundam Psycho Salamander no Kyoui (Banpresto / Bandai, 1991) targeting the MiSTer FPGA platform (Terasic DE10-Nano).

SD Gundam Psycho Salamander no Kyoui (SD ガンダム サイコサラマンダーの脅威) is a side-scrolling shoot-em-up running on Seibu PB91008 hardware — the same Seibu D-Con family used by Blood Bros. and D-Con. The core reimplements the hardware in SystemVerilog from MAME (seibu/dcon.cpp, seibu/seibu_crtc.cpp), the Seibu CRTC documentation, the main 68000 ROM disassembly and observation of real PCB behavior.

Status

Current version: 1.0 (May 2026) — first public release.

The core runs the full game with audio and inputs.

Features

• M68000 main CPU @ 10 MHz (FX68K cycle-accurate)
• Z80 sound CPU @ 3.579545 MHz (T80s)
• YM2151 FM (jt51) + OKI M6295 ADPCM (jt6295) with MAME-accurate mixer
• 320×224 active video area (Seibu D-Con timings)
• BG / MG / FG tilemaps (16×16, 4bpp, 32×32 tilemap)
• Text layer (8×8, 4bpp, 64×32 tilemap)
• 16×16 sprites with priority callback (Seibu SEI0211)
• Seibu CRTC registers (scroll, layer enable, flip screen)
• MiSTer OSD with audio mixer (FM/OKI volume), per-layer debug toggles
• Pause overlay with logo + supporters scroll

ROM sets supported

• SD Gundam Psycho Salamander no Kyoui (sdgndmps)

Screenshots

Title screen	Attract — Insert Coin
Intro story	Gameplay — cave stage
Forest / mountain	Jungle stage

Hardware emulated

Component	Spec
Master clock	20 MHz crystal (main) + 14.31818 MHz (sound)
Main CPU	M68000 @ 10 MHz
Sound CPU	Z80 @ 3.579545 MHz
Sound chip 1	Yamaha YM2151 (jt51)
Sound chip 2	OKI M6295 (jt6295) ADPCM, pin7=LOW, 1.25 MHz
Video resolution	320×224 active
Refresh rate	~59.4 Hz
BG layer	16×16 4bpp, 32×32 tilemap, scroll X/Y
MG layer	16×16 4bpp, 32×32 tilemap, scroll X/Y, gfx-bank
FG layer	16×16 4bpp, 32×32 tilemap, scroll X/Y
Text layer	8×8 4bpp, 64×32 tilemap
Sprites	16×16 4bpp, 4-level priority (Seibu SEI0211)
Palette	xBGR_555, 2048 entries
Custom video CRTC	Seibu CRTC (legionna.cpp / seibu_crtc.cpp)
Sprite chip	Seibu SEI0211

Hardware requirements

• Terasic DE10-Nano
• MiSTer I/O board (recommended)
• Works on HDMI displays and on 15 kHz CRTs via the analog video output

Notes

• 15 kHz CRT output via the MiSTer analog I/O board works (Seibu D-Con 320×224 is a standard arcade resolution).
• HDMI output works directly on modern displays. For 31 kHz VGA monitors use an HDMI→VGA adapter, or enable Direct Video if your I/O board and monitor support it.

Build from source

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

cd Arcade-GundamSD_MiSTer
quartus_sh --flow compile SDGundamPS

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

Running on MiSTer

The releases/ folder contains the parent MRA and a prebuilt RBF:

• SD Gundam Psycho Salamander no Kyoui.mra — parent MRA
• SDGundamPS_YYYYMMDD.rbf — prebuilt bitstream

Steps:

1. Copy the .rbf to _Arcade/cores/ on the MiSTer SD card (rename to SDGundamPS.rbf or keep the dated name and update the MRA accordingly).
2. Copy the .mra file to _Arcade/ on the MiSTer SD card.
3. Provide your legally-owned sdgndmps.zip ROM where the MRA expects it (usually in games/mame/).

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

Repository layout

Arcade-GundamSD_MiSTer/
├── rtl/
│   ├── GundamSD/     SD Gundam-specific core RTL
│   ├── pll/          Clock PLL
│   ├── sound/        Sound chip cores (jt51, jt6295, t80)
│   ├── fx68k/        FX68K M68000 cycle-accurate core
│   ├── jtframe/      JTFRAME framework modules
│   └── sdram.sv      SDRAM controller (Sorgelig)
├── sys/              MiSTer framework (Sorgelig / MiSTer-devel)
├── logo/             Pause overlay assets (font, logo, supporter list)
├── docs/             Screenshots
├── releases/         Parent MRA + prebuilt RBF
├── SDGundamPS.qpf    Quartus project
├── SDGundamPS.qsf    Quartus assignments
├── GundamSD.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

Acknowledgements

• Jose Tejada (@jotego) for JT51 (YM2151), JT6295 (OKI M6295) and the JTFRAME framework.
• Daniel Wallner and MikeJ for the T80 (Z80) core.
• Frederic Requin and contributors for the FX68K cycle-accurate M68000 core.
• Sorgelig and the MiSTer-devel team for the framework, SDRAM controller and Template.
• The MAME project for invaluable hardware reference (seibu/dcon.cpp, seibu/seibu_crtc.cpp).

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

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).

Original SD Gundam Psycho Salamander no Kyoui arcade hardware © Banpresto / Bandai / Sunrise / SOTSU AGENCY, 1991. Original ROM data is not included; users must provide their own legally obtained copies.