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Sega - MS/GG (Gearsystem)

Background

Gearsystem is an open source, cross-platform Sega Master System, Game Gear, SG-1000, and Othello Multivision emulator written in C++.

  • Very accurate emulation with support for ROM-only cartridges and Sega, Codemasters, Korean, MSX, Janggun, SG-1000, EEPROM, and multicart mappers.
  • Automatic region detection: NTSC-JAP, NTSC-USA, PAL-EUR.
  • Accurate VDP emulation, including timing and VDP specifics for SMS, SMS2, GG and TMS9918 modes.
  • Support for YM2413 (OPLL) FM sound chip.
  • Light Phaser and Paddle Control support.
  • Internal database for ROM detection.
  • Battery-backed RAM save support.
  • Game Genie and Pro Action Replay cheat support.
  • Supported platforms (libretro): Windows, Linux, macOS, Raspberry Pi, Android, iOS, tvOS, PlayStation Vita, PlayStation 3, Nintendo 3DS, Nintendo GameCube, Nintendo Wii, Nintendo WiiU, Nintendo Switch, Emscripten, Classic Mini systems (NES, SNES, C64, ...), OpenDingux, RetroFW and QNX.

The Gearsystem core has been authored by

The Gearsystem core is licensed under

A summary of the licenses behind RetroArch and its cores can be found here.

BIOS

Gearsystem does not require BIOS (boot ROM) files, but they can be used optionally.

When enabled, the BIOS runs as it does on original hardware. Invalid ROMs or ROMs for a different region or system may fail to boot. Disable the BIOS if this occurs.

Required or optional firmware files go in the frontend's system directory.

Attention

If you’d like to use any BIOS, you can place the following files in RetroArch's system directory. Then, you need to enable Master System BIOS and/or Game Gear BIOS core options for these BIOS files to be used.

Filename Description md5sum
bios.sms Master System BIOS - Optional 840481177270d5642a14ca71ee72844c
bios.gg Game Gear BIOS - Optional 672e104c3be3a238301aceffc3b23fd6

Extensions

Content that can be loaded by the Gearsystem core have the following file extensions:

  • .sms
  • .gg
  • .sg
  • .mv
  • .bin
  • .rom

RetroArch database(s) that are associated with the Gearsystem core:

Features

Frontend-level settings or features that the Gearsystem core respects.

Feature Supported
Restart ✔
Screenshots ✔
Saves ✔
States ✔
Rewind ✔
Netplay ✔
Core Options ✔
Memory Monitoring (achievements) ✔
RetroArch Cheats - Game Genie ✔
RetroArch Cheats - Pro Action Replay ✔
Native Cheats ✕
Controls ✔
Remapping ✔
Multi-Mouse ✕
Rumble ✕
Sensors ✕
Camera ✕
Location ✕
Subsystem ✕
Softpatching ✔
Disk Control ✕
Username ✕
Language ✕
Crop Overscan ✔
LEDs ✕

Directories

The Gearsystem core's library name is 'Gearsystem'

The Gearsystem core saves/loads to/from these directories.

Frontend's Save directory

File Description
*.srm Cartridge battery save

Frontend's State directory

File Description
*.state# State

Geometry and timing

  • The Gearsystem core's provided FPS is 60 for NTSC games and 50 for PAL games
  • The Gearsystem core's provided sample rate is 44100 Hz
  • The Gearsystem core's base width is 256 for Master System / SG-1000 games and 160 for Game Gear games
  • The Gearsystem core's base height is 192 for Master System / SG-1000 games and 144 for Game Gear games
  • The Gearsystem core's max width is 320
  • The Gearsystem core's max height is 288
  • The Gearsystem core's provided aspect ratio is 4:3 for Master System / SG-1000 games and 10:9 for Game Gear games

Core options

The Gearsystem core has the following options that can be tweaked from the core options menu. The default setting is bolded.

Settings with (restart) means that core has to be closed for the new setting to be applied on next launch.

  • System (restart) [gearsystem_system] (Auto|Master System / Mark III|Game Gear (2 ASIC)|Game Gear (2 ASIC) SMS Mode|Game Gear (1 ASIC)|Game Gear (1 ASIC) SMS Mode|SG-1000 / Multivision|SG-1000 II)

    Select the console type to emulate. 'Auto' automatically detects the appropriate system based on the loaded content.

    • Auto selects the best hardware based on the ROM.
    • Master System / Mark III forces original Master System / Mark III hardware.
    • Game Gear (2 ASIC) forces Game Gear hardware with 2 ASIC configuration.
    • Game Gear (2 ASIC) SMS Mode forces Game Gear in SMS compatibility mode (2 ASIC).
    • Game Gear (1 ASIC) forces Game Gear hardware with 1 ASIC configuration.
    • Game Gear (1 ASIC) SMS Mode forces Game Gear in SMS compatibility mode (1 ASIC).
    • SG-1000 / Multivision forces SG-1000 / Multivision hardware.
    • SG-1000 II forces SG-1000 II hardware.

  • Region (restart) [gearsystem_region] (Auto|Master System Japan|Master System Export|Game Gear Japan|Game Gear Export|Game Gear International)

    Select which region is emulated.

    • Auto selects the best region based on the ROM.
    • Master System Japan forces Master System Japan region.
    • Master System Export forces Master System Export region.
    • Game Gear Japan forces Game Gear Japan region.
    • Game Gear Export forces Game Gear Export region.
    • Game Gear International forces Game Gear International region.

  • Mapper (restart) [gearsystem_mapper] (Auto|ROM|SEGA|Codemasters|Korean|SG-1000|MSX|Janggun|Korean 2000 XOR 1F|Korean MSX 32KB 2000|Korean MSX SMS 8000|Korean SMS 32KB 2000|Korean MSX 8KB 0300|Korean 0000 XOR FF|Korean FFFF HiCom|Korean FFFE|Korean BFFC|Korean FFF3 FFFC|Korean MD FFF5|Korean MD FFF0|Jumbo Dahjee|EEPROM 93C46|Multi 4PAK All Action|Iratahack)

    Select which mapper (memory bank controller) is emulated. 'Auto' automatically detects the appropriate mapper based on the loaded content. Only change this if a game does not work correctly with the default setting.

    • Auto selects the best mapper based on the ROM.
    • ROM forces no mapper.
    • SEGA forces SEGA mapper.
    • Codemasters forces Codemasters mapper.
    • Korean forces Korean mapper.
    • SG-1000 forces SG-1000 mapper.
    • MSX forces MSX mapper.
    • Janggun forces Janggun mapper.
    • Korean 2000 XOR 1F forces the Korean 2000 XOR 1F mapper.
    • Korean MSX 32KB 2000 forces the Korean MSX 32KB 2000 mapper.
    • Korean MSX SMS 8000 forces the Korean MSX SMS 8000 mapper.
    • Korean SMS 32KB 2000 forces the Korean SMS 32KB 2000 mapper.
    • Korean MSX 8KB 0300 forces the Korean MSX 8KB 0300 mapper.
    • Korean 0000 XOR FF forces the Korean 0000 XOR FF mapper.
    • Korean FFFF HiCom forces the Korean FFFF HiCom mapper.
    • Korean FFFE forces the Korean FFFE mapper.
    • Korean BFFC forces the Korean BFFC mapper.
    • Korean FFF3 FFFC forces the Korean FFF3 FFFC mapper.
    • Korean MD FFF5 forces the Korean MD FFF5 mapper.
    • Korean MD FFF0 forces the Korean MD FFF0 mapper.
    • Jumbo Dahjee forces the Jumbo Dahjee mapper.
    • EEPROM 93C46 forces the EEPROM 93C46 mapper.
    • Multi 4PAK All Action forces the Multi 4PAK All Action mapper.
    • Iratahack forces the Iratahack mapper.

  • Refresh Rate (restart) [gearsystem_timing] (Auto|NTSC (60 Hz)|PAL (50 Hz))

    Select which refresh rate will be used in emulation.

    • Auto selects the best refresh rate based on the ROM.
    • NTSC (60 Hz) forces 60 Hz.
    • PAL (50 Hz) forces 50 Hz.

  • Aspect Ratio [gearsystem_aspect_ratio] (1:1 PAR|4:3 DAR|16:9 DAR|16:10 DAR)

    Select which aspect ratio will be presented by the core.

    • 1:1 PAR selects an aspect ratio that produces square pixels.
    • 4:3 DAR forces 4:3 aspect ratio.
    • 16:9 DAR forces 16:9 aspect ratio.
    • 16:10 DAR forces 16:10 aspect ratio.

  • Overscan [gearsystem_overscan] (Disabled|Top+Bottom|Full (284 width)|Full (320 width))

    Select which overscan (borders) will be used in emulation.

    • Disabled disables overscan.
    • Top+Bottom enables overscan for top and bottom.
    • Full (284 width) enables overscan for top, bottom, left and right (284 width).
    • Full (320 width) enables overscan for top, bottom, left and right (320 width).

  • Hide Left Bar (SMS only) [gearsystem_hide_left_bar] (No|Auto|Always)

    Select when to hide the left bar in Master System games.

    • No never hides the left bar.
    • Auto hides the left bar when the bar is detected.
    • Always always hides the left bar even if no left bar is detected.

  • No Sprite Limit [gearsystem_no_sprite_limit] (Disabled|Enabled)

    Remove the per-line sprite limit. This reduces flickering but may cause glitches in some games.

  • Master System BIOS (restart) [gearsystem_bios_sms] (Disabled|Enabled)

    Enable or disable the Master System BIOS. The bios.sms file must exist in the frontend's system directory. When enabled, it runs as it does on original hardware, so invalid ROMs may fail to boot.

  • Game Gear BIOS (restart) [gearsystem_bios_gg] (Disabled|Enabled)

    Enable or disable the Game Gear BIOS. The bios.gg file must exist in the frontend's system directory. When enabled, it runs as it does on original hardware, so invalid ROMs may fail to boot.

  • YM2413 (restart) [gearsystem_ym2413] (Auto|Disabled)

    Enable or disable the YM2413 (OPLL) FM sound chip. 'Auto' enables the chip based on the loaded content. Some Master System games use this chip for enhanced music.

    • Auto selects the best option based on the ROM.
    • Disabled disables YM2413.

  • PSG Volume [gearsystem_psg_volume] (100|0-200 in increments of 10)

    Set the volume of the PSG (SN76489). The value is a percentage from 0 to 200, where 100 is the default volume.

  • FM Volume [gearsystem_fm_volume] (100|0-200 in increments of 10)

    Set the volume of the YM2413 (OPLL) FM sound chip. The value is a percentage from 0 to 200, where 100 is the default volume.

  • 3D Glasses [gearsystem_glasses] (Both Eyes / OFF|Left Eye|Right Eye)

    For games with 3D glasses support this option will let you choose to display only left or right eye.

    • Both Eyes / OFF is required for games with NO 3D support or if you want to display both eyes in 3D games.
    • Left Eye displays the left eye only.
    • Right Eye displays the right eye only.

  • Allow Up+Down / Left+Right [gearsystem_up_down_allowed] (Disabled|Enabled)

    Enable this option to press, quickly alternate, or hold both left and right, or up and down, at the same time.

    This may cause movement-based glitches in some games.

    It is best to keep this option disabled.

  • Light Gun Input [gearsystem_lightgun_input] (Light Gun|Touchscreen)

    Select which input will be used for Light Phaser games.

    • Light Gun - Selects mouse-controlled Light Gun input (devices will use RetroLightgun inputs).
    • Touchscreen - Selects a touchscreen input (devices will use RetroPointer inputs instead).

  • Light Gun Crosshair [gearsystem_lightgun_crosshair] (Disabled|Enabled)

    Enable or disable the crosshair for Light Phaser games.

  • Light Gun Crosshair Shape [gearsystem_lightgun_shape] (Cross|Square)

    Select the shape of the crosshair for Light Phaser games.

  • Light Gun Crosshair Color [gearsystem_lightgun_color] (White|Black|Red|Green|Blue|Yellow|Magenta|Cyan)

    Select the color of the crosshair for Light Phaser games.

  • Light Gun Crosshair Offset X [gearsystem_lightgun_crosshair_offset_x] (0|-10 - 10)

    Set the horizontal pixel offset of the crosshair for calibration.

  • Light Gun Crosshair Offset Y [gearsystem_lightgun_crosshair_offset_y] (0|-10 - 10)

    Set the vertical pixel offset of the crosshair for calibration.

  • Paddle Sensitivity [gearsystem_paddle_sensitivity] (1|1-15)

    Set the sensitivity of the Paddle Control.

    • 1 is the lowest sensitivity.
    • 15 is the highest sensitivity.

Joypad

RetroPad Inputs SMS / GG Pad
Up
Down
Left
Right
1
2
Pause / Start

Light Gun

RetroLightgun Inputs Light Phaser
Gun Crosshair Light Phaser Crosshair
Gun Trigger Light Phaser Trigger

Pointer

RetroPointer Inputs Light Phaser
or Pointer Position Light Phaser Crosshair
Mouse 1 Light Phaser Trigger

Mouse

RetroMouse Inputs Paddle Control
Mouse Cursor Paddle wheel
Mouse 1 Paddle button

Compatibility

See also

Sega - Game Gear

Sega - Master System - Mark III

Sega - SG-1000