5DO

A modern, source-available C# / .NET 10 emulator for the 3DO Interactive Multiplayer.

Important

5DO is at v1.6.0, a documented-compatibility release. Windows x64 is the validated target; Linux x64 full suite passed (GPU presentation is preview/best-effort), and macOS/arm64 validation is post-1.0. No BIOS ROMs, game images, or extracted game assets are included. You must supply legally obtained files.

5DO is an accuracy-focused C# port of the FreeDO 3DO emulation core, with Opera/libopera as the primary behavioral reference for new compatibility work. It combines a deterministic managed emulation core with a cross-platform Avalonia desktop frontend, a headless CLI, and a test harness designed for reproducible compatibility evidence.

Why 5DO?

• Managed from top to bottom. The ARM60 CPU, CLIO, MADAM/CEL, DSP, SPORT, VDLP, XBUS, CD-ROM, storage, audio, and input paths are pure C#. No native emulator DLL, no C++/CLI, and no P/Invoke into FreeDOCore.
• Built for determinism. Fixed timesteps, explicit state serialization, seeded options, and per-frame PBUS recording make frames, audio, save states, and TAS movies reproducible.
• A real desktop emulator. Avalonia shell with a game library, cover art, BIOS and NVRAM managers, save slots with thumbnails, rewind/fast-forward, cheats, TAS recording, screenshots, GIF/WAV capture, a disc browser, controller mapping, and a diagnostics bundle.
• Modern presentation. Two-stage OpenGL/GLES presenter with accurate, nearest, sharp-bilinear, CRT, xBR-lv2, FSR 1.0, and GPU rule-table HQx 2x/3x/4x filters, plus 480i/240p field handling (auto detection, bob, weave, and blend). Optional Vulkan 1.0 and Direct3D 11 backends mirror the pipeline for desktop and headless probes.
• Powerful automation. Headless run, trace, bench, selftest, disc/BIOS/ NVRAM/cheat/movie/state commands, JSON output, watchpoints, dumps, and differential harnesses. Startup and 5do update check the public GitHub release feed.
• One bundle per system and architecture. Windows, Linux, and macOS bundles for x64 and arm64 contain both the framework-dependent single-file CLI and desktop app, plus the docs/notices. The .NET 10 runtime is a prerequisite and is not bundled. Optional NativeAOT CLI builds remain available for developers.

Status at a glance

Area	Current state
Version	1.6.0 release (GitHub Releases)
Validated platform	Windows x64
Build/publish targets	Windows, Linux, macOS — x64 and arm64
Automated tests	2,061 tests in the current test assembly
Differential oracle	50-title panel: 50/50 frame hashes at frames 60/120/300; only CD cadence remains
Library	414 unique titles across 1,371 images; 3 audio-only CHDs catalogued
Playability	375/378 game-test-set titles playable under the binary beyond-title rule; 0 Behind, 0 Regression
Loadability sweep	594 disc images tested; after triage 593 loadable/rendered, 1 known no-video case, 0 not loadable
First pass	576 rendered, 13 black/blank, 5 not loadable; triage resolved the failures and the blank/black set
Desktop presentation	OpenGL/GLES required; Vulkan and Direct3D 11 optional; CPU fallback available
Audio	Exact 44.1 kHz DSP clock; bundled OpenAL Soft 1.23.1

The full compatibility picture, per-title evidence, and remaining limitations live in the compatibility documentation, game compatibility list, 5DO vs 4DO vs Phoenix comparison, and known issues.

Download

One bundle per system and architecture, each containing both the desktop app and the CLI:

System	Bundle
Windows x64	5do-1.6.0-win-x64.zip
Windows arm64	5do-1.6.0-win-arm64.zip
Linux x64	5do-1.6.0-linux-x64.tar.gz
Linux arm64	5do-1.6.0-linux-arm64.tar.gz
macOS x64	5do-1.6.0-osx-x64.tar.gz
macOS arm64	5do-1.6.0-osx-arm64.tar.gz

The apps are single-file executables. Install the .NET 10 Runtime first from https://dotnet.microsoft.com/download/dotnet/10.0; the bundles do not contain a .NET runtime. See the release page for SHA256SUMS.txt and what's new.

Bundles are versioned and published for x64 and arm64, for example 5do-1.6.0-win-arm64.zip.

Features

Emulation core

• ARM60 interpreter with deterministic timing, banked registers, and a disassembler.
• Exact NTSC 60000/1001 (59.94 Hz) field clock and rational VDL accumulator, so audio and scanline timing do not drift against the reference core.
• Configurable 2-15 MB DRAM / 1-2 MB VRAM (stock 2 MB/1 MB), 2 MB ROM, NVRAM, high-resolution VRAM planes, and word-swapped storage.
• Opt-in unsigned-disc support patches the BIOS media RSA check in memory only; the BIOS file is never modified, and known No-RSA images are preferred when available.
• CLIO timers, interrupts, FIFOs, DMA, XBUS, and diagnostic port.
• MADAM CEL engine, matrix engine, pixel bus, CCB parsing, and pixel decoding.
• 3DO DSP with exact 44.1 kHz output, CD-DA mixing, and WAV analysis.
• SPORT VRAM fill/copy, VDLP display-list parsing, and CPU frame assembly.
• Mitsumi/MEI CD-ROM state machine with TOC, Sub-Q, CD-DA, multi-track CUE/CHD, M3U playlists, and ODE-style disc swapping.
• ISO, BIN, CUE+BIN, and CHD images, including parent/child CHDs and bounded read-ahead prefetch.

Desktop experience

• Avalonia game library with local and online covers, favorites, play time, metadata filters, and sorts. The online catalog uses precomputed 4DO game IDs plus annotation- stripped Jaro-Winkler fallback and an optional bulk pack for offline use.
• BIOS manager with region/Kanji/Anvil/patch detection, auto-selection, and per-game overrides.
• Shared and per-game NVRAM with backup, import, reset, and delete.
• Ten save slots with PNG thumbnails, state inspection, state diffing, and format v3.
• Compressed rewind history (30–300 seconds) and 2×–10× fast-forward.
• Latency controls: 0-2 frame run-ahead, 0-8 frame presentation delay, VRR/adaptive-sync presentation, a -250..250 ms audio sync offset, and software input-to-present telemetry.
• Per-game cheats with raw/typed/conditional/button codes and a desktop manager.
• Deterministic .5domovie TAS recording, replay, verification, branching, and a per-frame movie editor.
• Disc browser with file/directory extraction, disc info, track listing, and integrity verification.
• Screenshots, screenshot gallery, GIF recording, WAV recording, and a live FPS/input overlay.
• Eight-player keyboard and gamepad mapping; XInput on Windows and evdev on Linux; joypad, flightstick, mouse, lightgun, arcade lightgun, and Orbatak trackball devices.
• Portable mode, named configuration profiles, per-game profiles, and an instance lock.
• Privacy-scrubbed diagnostics bundles and an in-app log viewer.

Presentation

• OpenGL 3.3 desktop and OpenGL ES 3.0/3.1 paths, including ANGLE on Windows.
• Accurate pixel-for-pixel mode matching the CPU frame assembler.
• Nearest, sharp-bilinear, CRT (scanlines, aperture mask, curvature, vignette, bloom), xBR-lv2 4x, FSR 1.0 (EASU + RCAS), and HQx 2x/3x/4x.
• Integer scaling, custom aspect ratios, fullscreen, vsync, and 4K output.
• Optional Vulkan 1.0 backend with build-time SPIR-V shaders and a native Win32 swapchain path.

Platform support

Platform	Desktop	CLI	Status
Windows x64	✅	✅	Validated target
Windows arm64	✅	✅	Published; runtime validation pending
Linux x64	✅	✅	Published; local VM smoke validation
Linux arm64	✅	✅	Published; runtime validation pending
macOS x64 / arm64	✅	✅	Published; runtime validation pending
Raspberry Pi 4/5 (GLES 3.1)	—	—	Post-1.0 target

Quick start

Requirements

• .NET SDK 10.0.301 (pinned by global.json).
• A legally obtained 3DO BIOS ROM (1 MB; an optional second ROM for BIOS2/Kanji).
• Legally obtained 3DO disc images in ISO, BIN, CUE+BIN, or CHD format.
• For the desktop app: Windows 10+, a current Linux desktop, or macOS 12+.
• OpenGL 3.3 or OpenGL ES 3.0/3.1 for GPU presentation; the CPU fallback needs no GPU.
• No system OpenAL installation is required; the build bundles OpenAL Soft 1.23.1.

Note

v1.6.0 is published on GitHub Releases as one bundle per system and architecture (Windows, Linux, macOS; x64 and arm64), each with the CLI, desktop app, and SHA-256 checksums. The .NET 10 runtime is required on the host and is not bundled. Build from source below if you prefer. BIOS and game files are never distributed by this repository.

Build and test

git clone https://github.com/purelogiccode/5DO.git
cd 5DO
dotnet build 5DO.sln
dotnet test 5DO.sln

Run the desktop app

dotnet run -c Release --project src/FiveDo.Frontend.Avalonia

# Open a disc directly (also used by file associations)
dotnet run -c Release --project src/FiveDo.Frontend.Avalonia -- "game.chd"

# Override the BIOS and start fullscreen
dotnet run -c Release --project src/FiveDo.Frontend.Avalonia -- `
  "game.chd" --bios "bios/panafz1.bin" --fullscreen

On first run, choose Open BIOS, select a BIOS such as panafz1.bin, choose Open Disc, and press Play. See the installation guide for platform notes and data locations.

Run headless

# Render 600 frames and write a PNG
dotnet run --project src/FiveDo.Cli -- run game.chd --bios panafz1.bin `
  --frames 600 --frame-out frame.png

# Capture 10 seconds of 44.1 kHz audio
dotnet run --project src/FiveDo.Cli -- run game.chd --bios panafz1.bin `
  --frames 600 --audio wav --wav-out capture.wav

# Inspect a disc and verify every sector
dotnet run --project src/FiveDo.Cli -- info game.chd --json
dotnet run --project src/FiveDo.Cli -- disc verify game.chd --json

# Run the deterministic benchmark and self-test
dotnet run --project src/FiveDo.Cli -- bench --frames 600
dotnet run --project src/FiveDo.Cli -- selftest

The complete command surface is documented in the CLI reference.

Default controls

3DO button	Player 1 keyboard
D-pad	Arrow keys
A	Z
B	X
C	C
L	A
R	S
P (play/pause)	Enter
X (stop)	Backspace

Useful desktop shortcuts: F5 save state, F8 load state, F6/F7 change slots, F9 advance one frame while paused, Shift+F9 rewind one frame, R rewind one second, hold Tab to fast-forward, F10 reset, F11 fullscreen, F12 screenshot, F3 swap disc, and F4 open the quick menu. Bindings are configurable for eight players in Input.

Documentation

Start here	What it covers
Documentation site	Complete user, reference, developer, and maintainer documentation
User guide	Install, controls, settings, saves, library, recording, cheats, and CLI overview
Installation	Platform setup, BIOS/disc placement, data folders, portable mode
FAQ	BIOS, discs, releases, performance, platforms, saves, and licensing
CLI reference	Every command, option, exit code, and JSON response
Configuration	settings.json, profiles, paths, input, NVRAM, environment variables
Cover art	Online catalog, WebP pack, matching, R2 hosting, and takedown
Compatibility	BIOS/disc compatibility, per-title status, and sweep evidence
5DO vs 4DO vs Phoenix	Unique-title compatibility matrix, verdicts, regressions, and evidence
Troubleshooting	Symptom-driven diagnosis and fixes
Developer guide	Source map, invariants, extension points, and conventions
Wiki	Concise community guides and links into the full documentation

The documentation source lives in docs/, and the site is built with MkDocs Material. See docs/Documentation.md if you want to build it locally or publish the wiki.

Compatibility snapshot

The compatibility-completion pass covers 1,371 images and 414 unique titles, with a 378-title game/homebrew test set:

• 375 of 378 titles are Playable under the documented binary beyond-title rule.
• 0 Behind and 0 Regression rows; the playable set is a strict superset of the 252-title 4DO/Phoenix peer union.
• The remaining rows are three non-retail/add-on images: two Title-only captures and one No-video homebrew emulator.

The earlier first full-collection loadability sweep covered 594 disc images:

• 576 loaded and rendered on the first pass.
• 13 loaded but produced a black/blank first frame.
• 5 were not loadable on the first pass.

After triage, 593 are loadable/rendered with one known no-video case (Crash 'n Burn Japan), and zero not-loadable rows remain. The four Arcade CD-ROM titles require panafz10-class BIOS behavior; the remaining blank/black titles render by 6,000–9,000 frames or with the correct BIOS/region.

The per-title evidence, Tier B grades, and honest limitations are in the compatibility documentation, game compatibility list, and results table. The unique-title comparison against 4DO and Phoenix is in the 5DO vs 4DO vs Phoenix matrix. Full compatibility with the entire 3DO library is not claimed.

Performance

The core is designed for 60 fps at 4K output with presentation-only scaling:

• Native 320×240 emulation; 4K is output upscaling, not internal CEL resolution.
• Road Rash's 3D race measures 4.20 ms/frame total (p99 7.40 ms) on the reference machine after the 2026-10-31 performance pass, with an unchanged frame hash.
• 4K sharp-bilinear measures GPU p99 0.089 ms and present p99 0.208 ms on an RTX 4070 through the OpenGL path, with zero renderer/mailbox allocations per frame after warm-up.
• The synthetic benchmark gate enforces zero managed bytes/frame, core p99 ≤ 8 ms, total mean ≤ 8 ms, and total p99 ≤ 16.667 ms in CI.
• Presentation-only frame skipping (Off, Auto, OneInTwo–OneInFive) is available; Auto is the default.

See Performance and Vulkan for the full measurements.

Architecture

5DO keeps one console subsystem per assembly and a strict downward dependency rule:

Frontends        FiveDo.Frontend.Avalonia        FiveDo.Cli
                        │                            │
Host             FiveDo.Host (settings, library, save slots, profiles, diagnostics)
                        │
Machine          FiveDo.Machine (composition, Quartz scheduler, frame loop)
                        │
Chips            CPU · Memory · MADAM · CLIO · DSP · SPORT · VDLP · XBUS · CD-ROM
                        │
Contracts        FiveDo.Core (interfaces, value types, state contracts, constants)

The core is platform-neutral and deterministic. The host owns files, devices, windows, and settings. The Avalonia frontend and CLI are replaceable consumers of the same host layer. See Architecture and Developer Guide.

Build, test, and publish

# Full solution
dotnet build 5DO.sln -c Release
dotnet test 5DO.sln -c Release

# Formatting
dotnet format 5DO.sln --verify-no-changes

# Trimmed, self-contained CLI for a target runtime
dotnet publish src/FiveDo.Cli/FiveDo.Cli.csproj -c Release -r win-x64 `
  --self-contained true -p:PublishSingleFile=true -p:PublishTrimmed=true

# Trimmed desktop frontend
dotnet publish src/FiveDo.Frontend.Avalonia/FiveDo.Frontend.Avalonia.csproj `
  -c Release -r win-x64 --self-contained true `
  -p:PublishSingleFile=true -p:PublishTrimmed=true

# Optional NativeAOT CLI
dotnet publish src/FiveDo.Cli/FiveDo.Cli.csproj -c Release -r win-x64 `
  --self-contained true -p:FiveDoNativeAot=true -p:PublishSingleFile=true

CI runs build/test on Windows, Linux, and macOS, format checks, benchmark budget gates, NativeAOT smoke tests, unified bundle builds, and the release/wiki/docs deployment. See Build and Test and packaging/README.md.

Contributing

Contributions are welcome. Start with CONTRIBUTING.md, then read the Developer Guide, Test Strategy, and Build and Test.

• Use GitHub Discussions for questions and ideas, and SUPPORT.md for the support map.
• Use the issue forms for reproducible bugs, feature requests, and compatibility reports.
• Follow the Code of Conduct.
• Report security vulnerabilities privately through the security policy; do not open a public issue.
• Do not include BIOS ROMs, game images, or extracted copyrighted assets in issues, pull requests, or test fixtures.

Legal and attribution

5DO is donationware: non-commercial, source-available software funded by voluntary donations rather than sales. It is distributed under the FreeDO modified GNU LGPL; the FreeDO additional terms take precedence where they conflict with the LGPL. See LICENSE, THIRD-PARTY-NOTICES.md, and docs/Licensing.md.

FreeDO, 4DO, and Opera/libopera are upstream projects with their own copyright notices and terms. This repository does not include BIOS ROMs, game images, or extracted game assets. Donations do not grant commercial rights.

"3DO" and "Panasonic" are trademarks of their respective owners. 5DO is not affiliated with or endorsed by Panasonic, The 3DO Company, or any rights holder.

Acknowledgements

• FreeDO and 4DO for the original emulation core and game database.
• Opera/libopera for the behavioral reference used by modern compatibility work.
• Avalonia, Silk.NET, CHDSharp, Serilog, and OpenAL Soft for the platform, presentation, storage, diagnostics, and audio foundations.
• Every contributor who has recorded a frame hash, a save-state roundtrip, or a compatibility result.

---

_{Made with C# and .NET 10. Bring your own BIOS and discs.}