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http://hulkholden.github.io/n64js/

An n64 emulator in JavaScript
http://hulkholden.github.io/n64js/

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An n64 emulator in JavaScript

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# n64js



n64js is an n64 emulator written in (mostly) pure ES6 JavaScript. It runs many roms at full framerate.



## Why?



Mostly for the challenge. I've spent ~25 years (on and off) working on N64 emulators and writing one in JavaScript gives me the opportunity to expand my comfort zone and learn something new. It's a good showcase for how powerful modern browsers have become.



## How To Run



A hosted version is available on GitHub pages at https://hulkholden.github.io/n64js/.



## Development



Install `bun`: https://bun.sh/.



Compile sources (pass --watch to automatically recompile on any change):



```

bun run build --watch

```



Run a local webserver in the root directory:



```

python3 -m http.server

```



Navigate to http://localhost:8000/.



If you want to run without installing bun, you can change the importmap in index.html to point at src/n64.js instead of build/n64.min.js.



## Compatibility



Compatibility has improved a lot over the past few months.



As of 2023-09-23 95% of [n64-systemtest](https://github.com/lemmy-64/n64-systemtest) tests now pass. 



The areas where tests are failing are:



* 64-bit memory access (rarely/never used by roms)

* RDP (shouldn't be a problem, as n64js uses HLE)

* Floating point accuracy



The floating point issues are largely edge cases with rounding values close to the numerical limits for 32 bit floats.



Beyond the things n64-systemtest covers, the main compatibility issues I'm aware of are:



* imprecise cycle counting

* graphics



Imprecise cycle counting affects some roms more than others. GoldenEye in particular seems to hang when LLE audio emulation is enabled on the RSP.

I suspect this is due to the CPU running faster than it should be and causing the game to overflow audio buffers.



Graphics are rendered using high-level emulation and there are still a lot of TODOs. Many roms are playable but most have graphical issues of some kind.



## Browser Compatibility



* Chrome 116.0.5845.140 - I've been doing most of my development in Chrome so this is the preferred option

* Firefox 117.0 - runs, but is slower than Chrome.

* Safari 16.6 - runs, but is slower than Chrome.

* Edge - untested. Please let me know how you get on.



## Performance



I've been testing on an Apple M2 Max and most roms run at full framerate *most* of the time.

LLE audio emulation seems to be the biggest performance hit. To date I've mostly been focussed compatibility so there are likely a lot of improvements to be made here. 



## Implementation Status



* [ ] CPU

  * [x] cop0 instructions

  * [x] cop1 instructions

  * [x] TLB

  * [ ] Cycle accuracy

* [x] RSP

* [ ] Controller

  * [x] Static key bindings

  * [ ] Configurable bindings

  * [ ] Gamepad API

* [ ] Graphics

  * [ ] HLE

    * [ ] GBI0 - mostly implemented

    * [ ] GBI1 - partially implemented

    * [ ] GIB2 - partially immplemented

  * [ ] LLE - not implemented

* [ ] Audio

  * [ ] HLE - not implemented

  * [x] LLE - implemented

* [ ] Save

  * [x] Persistance (via localStorage)

  * [ ] Import/Export

  * [x] Mempack

  * [x] Eeprom 4k

  * [x] Eeprom 16k

  * [x] SRAM

  * [x] FlashRAM



## TODOs



Here's some things I'd like to get around to:



* Fix graphics issues

* Save game import/export

* Savestates

* [Gamepad](https://developer.mozilla.org/en-US/docs/Web/API/Gamepad_API/Using_the_Gamepad_API) support.



## History



n6js is derived from [Daedalus](https://github.com/hulkholden/daedalus), an emulator I started working on around 1999 and continued working on periodically for many years.

Around 2012 I made a bet with [@mmalex](https://github.com/mmalex) that I could write a port in JavaScript, and n64js was born!