UME-Core

A MAME core for OpenEmu, built from MAME 0.289. It replaces the MAME 0.250 core OpenEmu installs by default, so arcade sets dumped for a recent MAME load again, and it comes as a prebuilt plugin: download, double-click, done.

Features

• MAME 0.289 arcade drivers (the arcade subtarget), with ROM sets audited the way MAME does it. A set that fails the audit is reported with the missing or wrong files instead of a silent crash.
• Mouse as lightgun for gun games such as term2: left and right click are the trigger and the second button.
• Eight joysticks mapped to OpenEmu's arcade controls, plus a keyboard device.
• Save states, rewind and OpenEmu's display-mode changes.
• Updates itself through OpenEmu's core updater once installed.

Requirements

OpenEmu 2.4.1 on macOS 12.4 or later. OpenEmu.app is an Intel binary, so the core is x86_64 too; on Apple Silicon both run under Rosetta.

Install

1. Download MAME_<version>.zip from the latest release and unzip it.
2. Double-click MAME.oecoreplugin. OpenEmu imports it into ~/Library/Application Support/OpenEmu/Cores/, moves the previous MAME core to the Trash and asks to restart.
3. From then on OpenEmu checks this repository's appcast.xml at launch and installs newer versions by itself.

To install by hand instead, quit OpenEmu, copy MAME.oecoreplugin into ~/Library/Application Support/OpenEmu/Cores/, and clear the quarantine flag that Safari sets on downloads:

xattr -dr com.apple.quarantine ~/Library/Application\ Support/OpenEmu/Cores/MAME.oecoreplugin

The plugin is signed ad hoc, not notarized. OpenEmu removes the quarantine flag when it imports a plugin, which is why the double-click route needs no extra step.

ROMs

The core ships no ROMs. Add your sets to OpenEmu's Arcade library as MAME expects them: one <driver>.zip per game, named exactly after the MAME driver (sf2ceua.zip for driver sf2ceua), with the BIOS and device sets the game needs (neogeo.zip, qsound_hle.zip, …) in the same folder. Sets must match MAME 0.289; older sets often lack the PLD dumps added since. Mechanical machines, machines that need artwork and drivers MAME marks as not working are refused.

make romaudit (after a source build) audits a whole folder with the checks the core applies when it loads a game:

make romaudit                                   # OpenEmu's Arcade ROM folder
make romaudit ROMDIR=/path/to/roms

If a gun game follows the pointer but every shot lands in a corner, the game's own calibration in NVRAM (~/Library/Application Support/OpenEmu/MAME/nvram/<driver>/) predates pointer input. Recalibrate from the game's service menu, or delete that folder while no game is running.

Build from source

Requires Xcode 16 or later, about 5 GB of disk and, for MAME itself, around 20 minutes on an Apple Silicon Mac. The project expects an OpenEmu checkout next to this one (for one header, OEArcadeSystemResponderClient.h); set OPENEMU_DIR in Config/Local.mk to use another location.

git clone --recurse-submodules https://github.com/slioce/UME-Core.git
git clone --depth 1 --recurse-submodules https://github.com/OpenEmu/OpenEmu.git   # sibling checkout
cd UME-Core
make dylib     # MAME as deps/mame/mamearcade_headless.dylib (slow)
make sdk       # OpenEmuBase.framework into build/Release
make core      # build/Release/MAME.oecoreplugin
make install   # into ~/Library/Application Support/OpenEmu/Cores (quit OpenEmu first)

Or open MAME.xcodeproj in Xcode after make dylib sdk. Build settings live in Config/Shared.xcconfig; per-machine overrides such as OPENEMU_DIR or a signing team go in Config/Local.xcconfig, which is ignored by git. No developer account is needed.

On an Apple Silicon host the Makefile passes PLATFORM=x86 to MAME's build, which otherwise follows uname -m. MAME's objects go to deps/mame/build/osx_clang whatever the architecture, so delete that folder when switching.

Project layout

MAMEGameCore.m        The OpenEmu core: input mapping, options, ROM audit, frames, audio, save states.
Info.plist            Bundle metadata, OpenEmu keys and the appcast URL (SUFeedURL).
Config/               Build settings (Shared.xcconfig); Local.xcconfig and Local.mk are yours.
Makefile              dylib, sdk, core, install, dist, appcast, release, romaudit.
tools/                romaudit.m (ROM set audit) and make-appcast.sh.
appcast.xml           The feed OpenEmu polls for updates; rewritten by `make release`.
deps/mame             Fork of MAME (slioce/mame, branch mame0289-headless).

The fork adds a "headless" OSD layer (src/osd/headless/, originally written by Stuart Carnie for OpenEmu) that exposes MAME to Objective-C as OSD, InputDevice, AuditResult and friends, runs one frame per call instead of MAME's own loop, serializes save states to memory, and builds MAME as a dynamic library. CLAUDE.md has the details of the build and the debugging notes.

Releasing

Releases are built on a Mac, not in CI: compiling MAME takes hours on a GitHub runner.

1. Bump CURRENT_PROJECT_VERSION in Config/Shared.xcconfig (<MAME version>.0.<plugin revision>, for example 0.289.0.3), commit.
2. make release. It zips the plugin, pushes the commit, creates the GitHub Release v<version> with the zip attached, then regenerates appcast.xml, commits and pushes it. OpenEmu compares sparkle:version with the installed CFBundleVersion, so the appcast only goes live once the download exists.

Debugging

The core logs through os_log under the subsystem org.openemu.MAME (category audit for ROM audit details). It runs inside OpenEmuHelperApp:

/usr/bin/log show --last 1h --style compact --info --debug \
  --predicate 'subsystem == "org.openemu.MAME" OR subsystem BEGINSWITH "org.openemu"'

A "Load ROM at path …" line with no "Using GameAudio2 driver" after it means loading stopped before emulation started, almost always because the audit rejected the set.

Acknowledgements

The core and the headless OSD were written by the OpenEmu Team, Stuart Carnie in particular; this repository carries them to MAME 0.289 and adds the mouse lightgun, the audit errors and the release tooling. The work on this fork was done with the help of AI coding agents; design, review and testing are the author's.

MAME is developed by MAMEdev and contributors. MAME is a registered trademark of Gregory Ember. This project is not affiliated with MAMEdev or with OpenEmu.

License

Copyright © 2013-2026 OpenEmu Team and Alessandro Lioce. The code in this repository is released under the BSD 3-Clause License, as the original OpenEmu core.

The release zips embed a build of MAME, licensed under the GNU General Public License version 2 or later. Each plugin carries the license texts in Contents/Resources/legal/, and the corresponding source is the deps/mame submodule commit of the release tag.