Original Game Gear core credit: GreyRogue authored Game Gear support for the MiSTer Sega Master System core, then contributed Game Gear button and stereo audio fixes. This project ports and adapts that MiSTer engine for Gamebub; it did not originate the Game Gear emulation core. Credit also belongs to the MiSTer-devel SMS/GG contributors and to Ben's earlier Papilio Master System implementation. See source notices.
AI-developed Gamebub port: OpenAI Codex writes the Gamebub adaptation, tests, and release packages with human direction and testing on Gamebub hardware.
Current unified prerelease: GG and SMS Bub alpha.6 uses one GG/SMS NTSC core entry and the tested alpha.5 FPGA bitstream under the simpler menu name. Its source is on the unified development branch. FM audio and PAL timing remain in development. This default branch retains the earlier GG-only source baseline.
Current alpha.6 Auto limitation: The v1.1-beta firmware does not pass .gg/.sms filename extensions to the core. Auto works only when a ROM has a consistent TMR SEGA header. For an .sms title that does not start under Auto, choose System: Master System and reload it; choose Game Gear for an unrecognized .gg title. The extension-hint firmware patch on the development branch is source only and has not been installed or verified on a Bub. The single ROM picker remembers its last folder, so switching between separate GG and SMS folders requires navigation.
The MiSTer core this port comes from already runs both systems in one engine. They share much of the CPU, video, cartridge, and PSG sound path; the Gamebub port changes the machine profile at runtime for the screen, palette, controls, and audio. One bitstream lets those parts be reused instead of packaging two emulator engines. Some games sold for Game Gear actually run in Master System compatibility mode, so both modes are needed for accurate Game Gear coverage. Upstream notes that those titles may need an .sms extension; with the current Gamebub firmware, select System: Master System manually instead. The current build has one ROM picker and one remembered folder, as described above.
Development port of the MiSTer Sega Master System/Game Gear engine to Gamebub rev4. The current core runs native Game Gear games: the diagnostic ROM and Sonic Triple Trouble have both run on hardware. It includes the Sega CPU, VDP and JT89 sound engine, a Gamebub host loader, SDRAM controller, 160×144 video, stereo audio, input mapping, and 32 KiB cartridge RAM. Battery save export has been verified on hardware; import verification is in progress. The source repository does not include a bitstream, firmware UF2, retail ROM, or BIOS.
The GG-only package from this default-branch baseline is the
v0.1.0-alpha.2 pre-release.
Download its ZIP, then copy its cores and roms folders to the BUB SD card.
It uses the GameGear.Dev core ID and requires the custom core-loading firmware.
A separate rev4 trial confirmed integer 3× and 2× screen sizes on hardware. The centered 4× zoom option also works on hardware; it crops 12 Game Gear lines from the top and bottom. The 3.5× bilinear option works on hardware and crops about 3–4 source lines at each vertical edge. All four sizes remain selectable.
The target is SMS_MiSTer feature parity where the Bub hardware and firmware permit it. See the feature roadmap, build and hardware test instructions, recorded results, and source notices.
python3 scripts/run_tests.py --four-state
python3 scripts/build_core.py --target gamebub_rev4The enabling firmware source was examined at v1.1-beta
(9966de77f037ae5d7610bd9d2b6f0b512ff7eb5c). This repository includes
the selected upstream Sega source files. The Gamebub framework and generated
FPGA snapshot are kept outside this repository; obtain the framework under
its own terms at the revision in manifests/repositories.json before building.