# NesCore A NES Emulator made in JavaScript for educational purposes. [Try it!](https://afska.github.io/nescore/) Its main objective is to reflect the NES internals as simply as possible by using clean, object-oriented code. It doesn't have any complex bitwise operations, huge switch-case statements or files with lots of magic numbers. > rlabs Created by [[r]labs](https://r-labs.io). > ⚠️ This is not a cycle-accurate emulator and performance is not the main concern. ## Features - 👾 It emulates the **NES** - 👨‍🔧 It plays [Super Mario Bros. 3](https://en.wikipedia.org/wiki/Super_Mario_Bros._3)! - 💻 **CPU** - All **official instructions** are implemented - [nestest](https://raw.githubusercontent.com/afska/nescore/master/public/testroms/nestest.txt) passes ✔️ - Fully functional 🖥️ **PPU** and 🔊 **APU** - 🔌 Supported **mappers** - Mapper **0**: [NROM](https://www.nesdev.org/wiki/NROM) - Mapper **1**: [MMC1](https://www.nesdev.org/wiki/MMC1) - Mapper **2**: [UxROM](https://www.nesdev.org/wiki/UxROM) - Mapper **3**: [CNROM](https://www.nesdev.org/wiki/INES_Mapper_003) - Mapper **4**: [MMC3](https://www.nesdev.org/wiki/MMC3) - 🐏 **SRAM** support - 💾 **Save states** support - 🌎 **Web frontend** using [Web Workers](https://www.w3.org/TR/2021/NOTE-workers-20210128/) and [Gamepad API](https://www.w3.org/TR/gamepad/) ## Usage **`npm install --save nes-emu`** ```js // configure video and audio: const onFrame = (frameBuffer) => { // write `frameBuffer` (a Uint32Array) to screen... }; const onSample = (sample) => { // write `sample` (a number) to audio buffer... }; // create an instance: const nes = new NES(onFrame, onSample); // load a game: nes.load(rom); // rom = Uint8Array // run at 60 fps, or as fast as you can: { nes.setButton(1, "BUTTON_A", true); // player = 1, button = A, pressed = true nes.setButton(2, "BUTTON_DOWN", false); // player = 2, button = DOWN, pressed = false // ...set the rest of the buttons nes.frame(); } // save / restore states: const saveState = nes.getSaveState(); nes.setSaveState(saveState); ``` 👀 Have a look at the [demo implementation](https://github.com/afska/nescore/tree/master/src/gui) for more details. When running the demo (`npm start`) you can add `?debug` to the URL to enable a global `window.debug` object. ## Full API | Method | Parameters | Description | | --------------- | ------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | **constructor** | `onFrame`, `onSample`, _`logger`_ | Creates an emulator's instance. All properties can be set at any time. | | `load` | `rom`, _`saveFileBytes`_ | Loads a ROM. If a `saveFileBytes` array is provided, it sets the SRAM content. | | `frame` | | Runs the emulation for a whole video frame. | | `samples` | `requestedSamples` | Runs the emulation until the audio system generates `requestedSamples`. | | `scanline` | | Runs the emulation until the next scanline. | | `setButton` | `player`, `button`, `isPressed` | Sets the `button` state of `player` to `isPressed`. The `button` can be one of: `["BUTTON_A", "BUTTON_B", "BUTTON_SELECT", "BUTTON_START", "BUTTON_UP", "BUTTON_DOWN", "BUTTON_LEFT", "BUTTON_RIGHT"]` | | `clearButtons` | `player` | Sets all buttons of `player` to a non-pressed state. | | `getSaveFile` | | Returns an array with the SRAM bytes, or null. | | `getSaveState` | | Returns an object with a snapshot of the current state. | | `setSaveState` | `saveState` | Restores a `saveState`. | ## Screenshots ![nestest screenshot](https://raw.githubusercontent.com/afska/nescore/master/img/capture-sm.png) ## Useful links - [NesDev](https://www.nesdev.org/) | [Mirror](https://afska.github.io/nes-docs-backup/nesdev-wiki.zip) - [NES Emulation Overview](https://ltriant.github.io/2019/11/22/nes-emulator.html) | [Mirror](https://afska.github.io/nes-docs-backup/nes-emulation-good-bad-tedious/) - [NES Ebook](https://bugzmanov.github.io/nes_ebook/chapter_1.html) | [Mirror](https://afska.github.io/nes-docs-backup/nes-emulator-rust/) - [Easy 6502](https://skilldrick.github.io/easy6502/) | [Mirror](https://afska.github.io/nes-docs-backup/easy6502) - [6502 Reference](https://web.archive.org/web/20210724004546/http://www.obelisk.me.uk/6502/reference.html) | [Mirror](https://afska.github.io/nes-docs-backup/6502-reference.zip) - [NES Rendering](https://austinmorlan.com/posts/nes_rendering_overview) | [Mirror](https://afska.github.io/nes-docs-backup/nes-rendering-overview/) - [NES Graphics Part 1](http://www.dustmop.io/blog/2015/04/28/nes-graphics-part-1/) | [Mirror](https://afska.github.io/nes-docs-backup/nes-graphics-part-1/) - [NES Graphics Part 2](http://www.dustmop.io/blog/2015/06/08/nes-graphics-part-2/) | [Mirror](https://afska.github.io/nes-docs-backup/nes-graphics-part-2/) - [NES Graphics Part 3](http://www.dustmop.io/blog/2015/12/18/nes-graphics-part-3/) | [Mirror](https://afska.github.io/nes-docs-backup/nes-graphics-part-3/)