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Oeiuwq Faith Blog OpenSource Porfolio

gmarty/jsSMS

JavaScript Sega Master System & Game Gear dynamic recompiling emulator.
Source code at GitHub https://gmarty.github.io/jsSMS/
gmarty/jsSMS.json
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  "homepage": "https://gmarty.github.io/jsSMS/",
  "language": "JavaScript",
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  "pushedAt": "2023-07-11T13:22:27Z",
  "stargazersCount": 150,
  "topics": [
    "dynamic-compiler",
    "emulator",
    "interpreter",
    "recompiler",
    "sega-master"
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  "updatedAt": "2025-10-03T05:35:30Z",
  "url": "https://github.com/gmarty/jsSMS"
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jsSMS

Section titled “jsSMS”

jsSMS is a dynamic recompiling emulator for Sega Master System & Game Gear ROMs written in JavaScript and designed to be fast on mobile browsers.

Code

Section titled “Code”

Originally, this is a JavaScript port of JavaGear by Chris White.

Original copyright: Copyright (C) 2002-2008 Chris White

The code then evolved from a basic interpreter to a complex recompiler able to run on mobile at full speed.

The recompilation code is located in src/compiler folder as well as technical insights.

Section titled “Related talk”

Video of the talk about JSSMS I gave at Reject.js 2013. There are also the slides in HTML.

Current state

Section titled “Current state”
  • Though state save and load functions are ported, there are not used and should be more JavaScript friendly (using JSON for example, see JSNES for an example of implementation).
  • Lightgun is not yet supported.
  • The recompiler is not compatible with Closure Compiler in advanced optimizations mode and will likely never be.

Many parts of the script are borrowed from JSNES, a NES emulator in JavaScript by Ben Firsh.

If you are looking for another SMS emulator in JavaScript, go to Miracle.

ToDos

Section titled “ToDos”
  • Support latest IE.
  • Experiment with web workers for recompiled code generation.
  • Experiment with generator for calling interrupts.
  • Experiment with asm.js.

License

Section titled “License”

jsSMS - A dynamic recompiling emulator for Sega Master System & Game Gear written in JavaScript

Copyright (C) 2018 Guillaume Cedric Marty (https://github.com/gmarty)

Based on JavaGear Copyright (c) 2002-2008 Chris White

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.