JSNES vs NET-NES

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.

NET-NES is a free Nintendo Entertainment System emulator written in C# that can run some NES games. Downloadable builds are listed for Windows, macOS, and Linux, including win-x64, win-x86, osx-x64, osx-arm64, and linux-x64. Launching the executable opens a basic graphical interface with options to open a ROM and view the manual. Command-line options include ROM loading, a CPU JSON test, window scaling, an FPS counter, and debug mode. Mapper 0 is supported, while Mappers 1, 2, and 4 are implemented experimentally. The project says it passes nestest CPU instruction tests and lists tested games as working, but some games may glitch or freeze. Its PPU uses scanline timing rather than dot-by-dot timing, so it is not cycle accurate and some games may be affected. A debugger, Mapper 3, player 2 controller support, and audio are listed as upcoming features. The project distributes the software under the MIT License.