A cycle accurate emulation of the classic Nintendo Entertainment System. Plays over 1000 games!
 Super Mario Bros. |
 Tetris |
 The Legend of Zelda |
|---|---|---|
 DuckTales |
 Choujin Sentai Jetman |
 Castlevania |
For now, to run znes you'll need cargo and SDL2. Installation instructions for the Rust toolchain can be found here, and consult your distro's repositories for SDL2.
Use cargo to build the project:
cargo build --release
The binary can then be found in ./target/release/znes. Znes uses clap to handle command line arguments. It expects the directory of an NES rom (absolute or relative), followed by optional arguments. Running with the -h flag will display the options.
USAGE:
znes [FLAGS] [OPTIONS] <file>
ARGS:
<file> The .nes file to be ran by the emulator
FLAGS:
-d Turn debugging information on
-h, --help Prints help information
-V, --version Prints version information
OPTIONS:
-s <scale> Resolution scaling factor, defaults to 3
The debugging flag will turn on CPU profiling and save the profile to ./znes.profile. You can use Google's pprof for analysis.
The control scheme uses the following keys:
Z - (A)
X - (B)
Backspace - (Select)
Enter - (Start)
Up - (Up)
Down - (Down)
Left - (Left)
Right - (Right)
Space - Toggle pause
After making my Chip8 emulator at the end of last year, I wanted to work on something more complicated and challenging. And this project was undoubtedly the hardest I've ever worked on. Even though the NES is a relatively simple machine, the components are still incredibly complex and nuanced, especially when compared to the aforementioned Chip8. In order for a working emulator, you need to accurately emulate most of the internal hardware of the NES - even small bugs can render an emulator completely broken.
Like with my Chip8 emulator, I wrote znes in Rust. It's quickly become my favorite language, and even though it causes the occasional headache, I'm sure I avoided many bugs that I would have encountered if I wrote it in C or C++. I'll continue using Rust for future projects.
What made this project possible was the unmatched efforts of the incredible NES community. The Nesdev Wiki details everything that you could possibly need for this project, so you won't need to rummage through hardware manuals from the 1980s to understand the inner workings of the machine. One Lone Coder's NES series was also paramount to being able to fully understand the hardware. Additionally, thanks to Folgeman's emulator, nestur, and LaiNES for being great references throughout development. And last but not least, special thanks to my friends Thomas George and Daniel Prilik, for convincing me to go through with this project. Their emulators, NESS and ANESE were also great resources and served as inspiration for the project.
The code could be optimized further for better performance. I'd like to do some more cleanup and implement more mappers. Currently, Mappers 0-3 are implemented which covers around 70% of games according to this list. Additionally, I haven't implemented the APU, which is probably the highest priority at this point.
I'll also look into deploying this project to the web using WebAssembly.