fixNES vs JSNES

fixNES is a free, open-source NES emulator for Windows and Linux. It runs NTSC and PAL .nes ROMs and creates .sav files for games that support saving. FDS and QD titles can run when a FDS BIOS named disksys.rom is placed in the same folder, and NSF music files are supported with track changes on the left and right keys. Files can be opened by drag and drop, command-line argument or from ZIP archives. The project lists support for NES mappers and VRC6, VRC7, FDS, MMC5, N163 and Sunsoft 5B audio expansions. Controls are keyboard-only; Windows users can use joy2key for controller input. The standalone build uses supplied scripts and requires freeglut and openal-soft, while a Makefile supports RetroArch core use. The README says the project is not in its most complete or cleanest state. It is licensed under MIT.

JSNES is a free JavaScript library for emulating NES games in browsers and Node.js. Its Browser helper handles canvas rendering, audio, keyboard and gamepad input, and frame timing; the lower-level NES class allows custom rendering and audio handling in Node.js. ROM data can be loaded from a URL or from a string, Uint8Array, or ArrayBuffer. The API runs frames, accepts controller input for either player, resets, adjusts frame rate, and includes methods for moving and triggering the Zapper. Applications can serialize and restore emulator state with `toJSON()` and `fromJSON()`. The `onBatteryRamWrite` callback lets an application capture battery-backed SRAM writes for persistent game saves. Sound emulation is enabled by default, with a default sample rate of 48000 Hz, and an audio callback is available. The README provides npm installation for Node.js or Webpack and an unpkg script for browser use, as well as a React embedding example. JSNES is licensed under Apache-2.0; its GitHub Issues tracker accepts bug reports and feature requests.