TetaNES

📖 Summary - ✨ Features - 🌆 Screenshots - 🚀 Getting Started - 🛠️ Roadmap - ⚠️ Known Issues - 💬 Contact

Summary

photo credit for background: Zsolt Palatinus on unsplash

TetaNES is a cross-platform emulator for the Nintendo Entertainment System (NES) released in Japan in 1983 and North America in 1986, written in Rust using wgpu. It runs on Linux, macOS, Windows, and in a web browser with Web Assembly.

It started as a personal curiosity that turned into a passion project. It is still being actively developed with new features and improvements constantly being added. It is a fairly accurate emulator that can play most NES titles.

TetaNES is also meant to showcase using Rust's performance, memory safety, and fearless concurrency features in a large project. Features used in this project include complex enums, traits, generics, matching, iterators, channels, and threads.

TetaNES also compiles for the web! Try it out in your browser!

Features

• Runs on Linux, macOS, Windows, and Web.
• Standalone emulation core in tetanes-core.
• NTSC, PAL and Dendy emulation.
• Headless Mode when using tetanes-core.
• Pixellate and NTSC filters.
• Up to 4 players with gamepad support.
• Zapper (Light Gun) support using the mouse.
• iNES and NES 2.0 ROM header formats supported.
• 14 supported mappers covering ~85% of licensed games.
• Game Genie Codes.
• Configurable while running using egui.
  • Increase/Decrease speed & Fast Forward
  • Visual & Instant Rewind
  • Save & Load States
  • Battery-backed RAM saves
  • Screenshots
  • Gameplay recording and playback
  • Audio recording

Screenshots

Getting Started

TetaNES runs on all major operating systems (Linux, macOS, Windows, and the web). Installable binaries will be available when 1.0.0 is released, but for the time being you can install with cargo which comes installed with Rust.

Install

There are multiple options for installation, depending on your operating system, preference and existing tooling.

Linux

Ubuntu/Debian

A .deb package is provided under Assets on the latest Release. Once downloaded, you can install it and the required dependencies. e.g.

sudo apt install ./tetanes-0.10.0-1-amd64.deb

Other Distros

An AppImage is provided under Assets on the latest Release. Simply download it and put it wherever you want.

A .tar.gz package is also provided under Assets on the latest Release. You can place the tetanes binary anywhere in your PATH.

The following dependencies are required to be installed:

• ALSA Shared Library
• GTK3

e.g.

apt install libasound2 libgtk-3-0 dnf install alsa-lib gtk3 pacman -Sy alsa-lib gtk3

MacOS

App Bundle

The easiest is to download the correct app bundle for your processor. The .dmg downloads can be found under the Assets section of the latest Release.

Homebrew

TetaNES can also be installed through Homebrew.

brew install lukexor/formulae/tetanes

Windows

A windows installer is provided under Assets on the latest Release.

Cargo Install

You can also build and install with cargo which comes with rustup.

cargo install tetanes

This will install the latest released version of the TetaNES binary to your cargo bin directory located at either $HOME/.cargo/bin/ on a Unix-like platform or %USERPROFILE%\.cargo\bin on Windows.

Alternatively, if you have cargo binstall installed:

cargo binstall tetanes

This will try to find the target binary for your platform from the latest Release or install from source, similar to above.

Usage

Usage: tetanes [OPTIONS] [PATH]

Arguments:
  [PATH]  The NES ROM to load or a directory containing `.nes` ROM files.
  [default: current directory]

Options:
      --rewind                     Enable rewinding
  -s, --silent                     Silence audio
  -f, --fullscreen                 Start fullscreen
  -4, --four-player <FOUR_PLAYER>  Set four player adapter. [default: 'disabled']
                                   [possible values: disabled, four-score, satellite]
  -z, --zapper                     Enable zapper gun
      --no-threaded                Disable multi-threaded
  -m, --ram-state <RAM_STATE>      Choose power-up RAM state. [default: "all-zeros"]
                                   [possible values: all-zeros, all-ones, random]
  -r, --region <REGION>            Choose default NES region. [default: "ntsc"]
                                   [possible values: ntsc, pal, dendy]
  -i, --save-slot <SAVE_SLOT>      Save slot. [default: 1]
      --no-load                    Don't load save state on start
      --no-save                    Don't auto save state or save on exit
  -x, --speed <SPEED>              Emulation speed. [default: 1.0]
  -g, --genie-code <GENIE_CODE>    Add Game Genie Code(s). e.g. `AATOZE`
                                   (Start Super Mario Bros. with 9 lives)
      --config <CONFIG>            Custom Config path
  -c, --clean                      "Default Config" (skip user config and previous
                                   save states)
  -d, --debug                      Start with debugger open
  -h, --help                       Print help
  -V, --version                    Print version

iNES and NES 2.0 formatted ROMS are supported, though some advanced NES 2.0 features may not be implemented.

Supported Mappers

Support for the following mappers is currently implemented or in development:

1. Source Mirror

Controls

Keybindings can be customized in the keybindings menu. Below are the defaults.

NES joypad:

Controller Layout:

SDL-compatible mappings are used: https://github.com/mdqinc/SDL_GameControllerDB?tab=readme-ov-file but can be overriden by setting SDL_GAMECONTROLLERCONFIG.

           Left Triggers                        Right Triggers
              _=====_                               _=====_
             / _____ \                             / _____ \
           +.-'_____'-.---------------------------.-'     '-.+
          /   |     |  '.                       .'            \
         / ___| /|\ |___ \                     /      (N)      \
        / |      |      | ;    _         _    ;                 ;  Action Pad
 D-Pad  | | <---   ---> | |  <:_|       |_:>  |  (W)       (E)  |  (South, East,
        | |___   |   ___| ;  Select    Start  ;                 ;   North, West)
        |\    | \|/ |    /  _              _   \      (S)      /|
        | \   |_____|  .','" "',        ,'" "', '.           .' |
        |  '-.______.-' / Left  \------/ Right \  '-._____.-'   |
        |              /\ Stick /      \ Stick /\               |
        |             /  '.___.'        '.___.'  \              |
        |            /                            \             |
         \          /                              \           /
          \________/                                \_________/

Emulator shortcuts:

While the CPU Debugger is open:

While the PPU Debugger is open:

Other mappings can be found and modified in the Config -> Keybinds menu.

Directories

TetaNES stores to files to support a number of features, and depending on the file type and varies based on operating system.

Configuration Preferences

• Linux: $HOME/.config
• macOS: $HOME/Library/Application Support
• Windows: %LOCALAPPDATA%\tetanes
• Web: Does not currently support persisting configuration preferences.

Screenshots

• Linux, macOS, & Windows: $HOME/Pictures
• Web: Does not currently support saving screenshots.

Replay Recordings

• Linux, macOS, & Windows: $HOME/Documents
• Web: Does not currently support saving recordings.

Audio Recordings

• Linux, macOS, & Windows: $HOME/Music
• Web: Does not currently support saving recordings.

Battery-backed RAM, save states, and logs

• Linux: $HOME/.local/share/tetanes
• macOS: $HOME/Library/Application Support/tetanes
• Windows: %LOCALAPPDATA%\tetanes
• Web: Does not currently support save states.

Powerup State

The original NES hardware had semi-random contents located in RAM upon power-up and several games made use of this to seed their Random Number Generators (RNGs). By default, TetaNES honors the original hardware and emulates randomized powerup RAM state. This shows up in several games such as Final Fantasy, River City Ransom, and Impossible Mission II, amongst others. Not emulating this would make these games seem deterministic when they weren't intended to be.

If you would like TetaNES to provide fully deterministic emulated power-up state, you'll need to change the ram_state setting in the configuration menu and trigger a power-cycle or use the -m/--ram_state flag from the command line.

Building/Running

To build/run TetaNES, you'll need a nightly version of the compiler and run cargo build or cargo build --release (if you want better framerates).

To run the web version, you'll also need the wasm32-unknown-unknown target and trunk installed:

rustup target add wasm32-unknown-unknown
trunk serve --release

Unit and integration tests can be run with cargo test. There are also several test roms that can be run to test various capabilities of the emulator. They are all located in the tetanes-core/tests_roms/ directory.

Run them in a similar way you would run a game. e.g.

cargo run --release tetanes-core/test_roms/cpu/nestest.nes

Feature Flags

• cycle-accurate - Enables cycle-accurate emulation. More CPU intensive, but supports a wider range of games requiring precise timing. Disabling may improve performance on lower-end machines. Enabled by default.
• profiling - Enables puffin profiling.

Troubleshooting

If you get an error running a ROM that's using the supported Mapper list above, it could be a corrupted or incompatible ROM format. If you're unsure which games use which mappers, see http://bootgod.dyndns.org:7777/. Trying other versions of the same game from different sources sometimes resolves the issue.

If you get some other error when trying to start a game that previously worked, try removing any saved states from the directories listed above to ensure it's not an incompatible savestate file causing the issue.

If you encounter any shortcuts not working, ensure your operating system does not have a binding for it that is overriding it. macOS specifically has many things bound to Ctrl-*.

If an an issue is not already created, please use the github issue tracker to create it. A good guideline for what to include is:

• The game experiencing the issue (e.g. Super Mario Bros 3). Please don't include any download links or ROM attachments.
• Operating system and version (e.g. Windows 7, macOS Mojave 10.14.6, etc)
• What you were doing when the error happened
• A description of the error and what happeneed
• Any screenshots or console output
• Any related errors or logs

When using the web version in the browser, also include:

• Web browser and version (e.g. Chrome 77.0.3865)

Roadmap

See ROADMAP.md.

Known Issues

See the github issue tracker.

Documentation

In addition to the wealth of information in the docs/ directory, I also referenced these websites extensively during development:

• NES Documentation (PDF)
• NES Dev Wiki
• 6502 Datasheet

License

TetaNES is licensed under a MIT or Apache-2.0 license. See the LICENSE-MIT or LICENSE-APACHE file in the root for a copy.

Contribution

While this is primarily a personal project, I welcome any contributions or suggestions. Feel free to submit a pull request if you want to help out!

Contact

For issue reporting, please use the github issue tracker. You can also contact me directly at https://lukeworks.tech/contact/.

Credits

Implementation was inspiried by several amazing NES projects, without which I would not have been able to understand or digest all the information on the NES wiki.

• fogleman NES
• sprocketnes
• nes-emulator
• LaiNES
• ANESE
• FCEUX

I also couldn't have gotten this far without the amazing people over on the NES Dev Forums:

• blargg for all his amazing test roms
• bisqwit for his test roms & integer NTSC video implementation
• Disch
• Quietust
• rainwarrior
• And many others who helped me understand the stickier bits of emulation

Also, a huge shout out to OneLoneCoder for his NES and olcPixelGameEngine series as those helped a ton in some recent refactorings.