#gameboy #emulator

app mizu

An accurate gameboy(DMG) and gameboy color emulator. Front-end for mizu-core

3 releases

new 0.1.2 Feb 18, 2021
0.1.1 Feb 7, 2021
0.1.0 Feb 7, 2021

#8 in Emulators

21 downloads per month

MIT license

7.5K SLoC


Build status codecov crate.io

Mizu is an accurate Gameboy emulator built in Rust.


  • Emulating The original gameboy (DMG) and gameboy color hardware.
  • Passing most hardware tests (see TESTING.md).
  • Bettery save support.
  • Accurate RTC emulation for MBC3 mapper.
  • Accurate APU emulation with 48KHz audio.
  • SFML gui front-end.
  • Robust testing framework for continous testing.
  • Easily change emulation speed.
  • Functional mappers:
    • NoMapper
    • MBC1
    • MBC2
    • MBC3
    • MBC5
  • Printer emulation


The SFML front-end provide these keyboard bindings:


Key Gameboy
U Select
I Start
W Up
S Down
A Left
D Right


Key Function
Enter A+B+Select+Start*
+ Increase 5 to FPS**
- Recude 5 from FPS**
P Open Printer

* I made this because in Zelda: Link's awakening you need to press all of these buttons on the same frame to bring the save menu, which is annoying.

** FPS here is not the same with normal games FPS, where low FPS just makes the game laggy, here FPS control the emulation speed. Normally it will run on 60 FPS. If the user set FPS to 30 it will emulate in half the speed, this include audio, and CPU emulation.

Printer window keys

Key Function
C Clear current image buffer
S Save image buffer to file


Gameboy Printer is a serial device that can be connected to the gameboy and used by some cartridges to print images. Popular cartidges that uses it are:

  • Gameboy Camera.
  • Zelda: Link's Awakening DX (to print images from the album).
  • Pokemon (several versions) (to print pokemon info from the Pokedex).

The printer can be opened by pressing the P key.

The printer emulation allows to save the printed images into disk. The window will only show 160x144 pixels, but the image is scrollable.

Building and Installation

For installing or building mizu we would use cargo.


If you want to use the development version of mizu you can build the project yourself. After downloading/cloning the repository, it can be build with:

$ cargo build

With release option:

$ cargo build --release


If you want to use the latest stable version from crates.io:

$ cargo install mizu

Yet another gameboy emulator?

Why not?. it is fun and educational, but even though I'm planning to make it as accurate as I can. If you want to see cool emulators, check my previous work Plastic.


General Gameboy

CPU instructions

Debugging and testing


~113K SLoC