Fami - Famicom/NES Emulator

Fami is a NES emulator written in C#. The name is derived from the Japanese model of the NES, the Family Computer or Famicom.

The main goal was to build a fast NES emulator with sound in C#.

When running in Debug mode, the emulator manages around 40-50 fps, but runs full speed when running in Release mode on a Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz.

Screenshots

Prerequisites

• .NET 5 SDK
• Visual Studio 2019 v16+

Features

• Zapper/Light-gun support
• Support for using controllers
• Save/Load States (only slot 1 right now)
• Rewind (up to 8 seconds)

Todo

• Button mapping through a configuration file
• Menus and dialogs
• Implement more mappers
• Fullscreen

Usage

fami.exe "<path to rom>"

Key mapping

The mappings don't use Space or Enter or Escape since Steam maps the controller to these buttons.

Mappers

• NROM (000)
• MMC1 (001)
• UxROM (002)
• MMC3 (004)
• AxROM (007)

PPU

The PPU is a port of the C++ PPU used in One Lone Coders NES Emulation Tutorial and retains all the comments.

APU

The APU is taken from the BizHawk NES APU found here: https://github.com/TASVideos/BizHawk/blob/master/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/APU.cs

I decided to use it as it gave the best audio output.

It uses blargg's blip_buf library to effectively generate samples that are timed against an emulation clock (it coincides with every tick of a CPU cycle) which greatly simplifies synchronization of audio.

Known Issues

Zapper/Light gun

If you move the mouse immediately after firing, the sensor position will move, causing your aim to be off from where you clicked.

Right-clicking to trigger "outside" of the screen kind of works. It's good enough for game mode selection screens, but doesn't work well during actual gameplay. It still registers as a trigger "inside" the screen. This is probably caused by timing issues.