Mesen
NES accuracy perfected
The highly accurate NES and SNES emulator known for comprehensive debugging tools and near-perfect hardware emulation.
Overview
Mesen is a cycle-accurate NES emulator (and later SNES with Mesen-S) created by Sour, known for exceptional accuracy and comprehensive debugging features. It passes virtually all known accuracy tests while remaining fast enough for general use. For NES development and preservation, Mesen has become the reference standard.
Fast Facts
- Developer: Sour
- First release: 2016
- Systems: NES, Famicom, SNES (Mesen-S)
- Accuracy: 99%+ on test ROMs
- Platforms: Windows, Linux, macOS
Accuracy
Mesen’s test results:
| Test Suite | Result |
|---|---|
| blargg tests | All pass |
| Mesen test ROMs | All pass |
| Obscure games | Nearly all work |
| Homebrew | Excellent compatibility |
Debugging Features
Exceptional development tools:
| Feature | Use |
|---|---|
| Debugger | Breakpoints, stepping |
| Memory viewer | RAM, VRAM, OAM |
| PPU viewer | Nametables, sprites, palettes |
| Trace logger | Execution history |
| Script support | Lua automation |
| Event viewer | IRQ, NMI timing |
Mapper Support
Comprehensive cartridge support:
- All common mappers (MMC1, MMC3, etc.)
- Obscure mappers
- Unlicensed cartridges
- Famicom Disk System
- Expansion audio chips
Why Developers Use Mesen
For NES development:
- Accurate behaviour - Code works on hardware
- Fast iteration - Quick testing
- Debugging - Find bugs efficiently
- Documentation - Learn from the emulator
- Free - Open source
Mesen-S
SNES variant:
- Same accuracy philosophy
- Comprehensive debugging
- Cycle-accurate
- Coprocessor support (SuperFX, SA-1, etc.)
Comparison
| Emulator | Accuracy | Debugging | Speed |
|---|---|---|---|
| Mesen | Excellent | Excellent | Good |
| FCEUX | Good | Good | Fast |
| Nestopia | Good | Limited | Fast |