nes-emu

A Nintendo Entertainment System (NES) emulator written in C++

As this is just a pet project, don't expect a full-featured emulator. There is no GUI, many typical features are missing, and only a few mappers have been implemented. However, the code is pretty clean and straightforward, and I think can be useful to learn from. Of course, if someone wanted to fork this code to write a full-featured emulator, that would be cool as well :)

Features

• Mappers 0,1,2,3,4,7 (~90% of games)
• Accurate audio emulation (no DMC)
• Automatic saving of SRAM
• Save state support
• Rewind any time up to 1 minute at normal speed
• Single and multi frame stepping when paused

Controls

Challenge

As with most pet projects, the purpose of writing this emulator was mainly to learn. My background is not in hardware, but I have always had a keen interest in computer architecture, so part of my goals was to learn more about how a console works at the hardware level. The NES is simple enough in that respect, although it has enough quirks to make it interesting to emulate.

To further my learning, I challenged myself to write this emulator without looking at any other emulator code. So the implementation is completely my own, and I suspect parts of my code may seem strange or inefficient as compared to other implementations.

Building

• Install CMake

• Download 32-bit SDL2 Development Libraries from https://www.libsdl.org/download-2.0.php

  • On Windows, set an environment variable named "SDL2" to the path of the extracted archive (e.g. set SDL2=C:\code\SDL2-2.0.4)
  • On Debian Linux, install SDL2: sudo apt-get install libsdl2-dev

• Run CMake and build. For example, on Windows:

cd nes-emu
md build
cd build
set SDL2=C:\code\SDL2-2.0.4
cmake ..

Thanks

Although I did not look at other emulator source code, I did get a lot of information and help from other sources:

• The awesome people on the #nesdev IRC channel (huge thanks!)
• Excellent documentation on the nesdev wiki
• Other excellent emulators I used to compare output, trace, and debug:
  • fceux
  • Nintendulator
  • NO$NES