A Nintendo Entertainment System (NES) emulator written in C using SDL2.

• 6502 CPU: Full instruction set implementation with all addressing modes
• PPU (2C02): Basic PPU structure with register handling
• Cartridge Loading: iNES format support with Mapper 0 (NROM)
• Controller Input: NES controller emulation with keyboard mapping
• SDL2 Graphics: Window and rendering system

• GCC compiler
• SDL2 development libraries
• Make

On macOS:

brew install sdl2

make

On Apple Silicon Macs, the build uses x86_64 architecture:

arch -x86_64 make

./bin/nes_emu <path_to_rom.nes>

Example:

./bin/nes_emu roms/game.nes

Analyze NES ROM files and display detailed information:

./bin/nes_info <rom.nes>

Features:

• iNES header parsing
• Mapper identification
• ROM size information
• Interrupt vectors
• CHR-ROM analysis
• Visual pattern display

Example output:

╔════════════════════════════════════════╗
║       NES ROM Analysis Tool            ║
╚════════════════════════════════════════╝

File: Tetris.nes

=== iNES Header Information ===
Magic: NES ✓ Valid

--- ROM Sizes ---
PRG-ROM: 8 x 16KB = 128KB
CHR-ROM: 16 x 8KB = 128KB

--- Mapper ---
Mapper Number: 65
Mapper Name: Irem H3001

Run unit tests:

make test

Tests verify:

• CPU operations
• Mapper 65 bank switching
• PPU palette/nametable
• Pattern extraction

.
├── Makefile
├── include/
│   ├── common.h      # Common type definitions
│   ├── bus.h         # Memory bus interface
│   ├── cpu.h         # 6502 CPU interface
│   ├── ppu.h         # PPU interface
│   └── cartridge.h   # ROM cartridge interface
└── src/
    ├── main.c        # Entry point and SDL loop
    ├── bus.c         # Memory mapping
    ├── cpu.c         # 6502 CPU implementation
    ├── ppu.c         # PPU implementation
    └── cartridge.c   # ROM loading

• All official opcodes implemented
• 12 addressing modes
• Interrupt handling (NMI, IRQ, RESET)
• Cycle-accurate timing

• Basic register implementation ($2000-$2007)
• Scanline and cycle tracking
• VBlank NMI generation
• Frame buffer output

• iNES format parsing
• Mapper 0 (NROM) support
• 16KB/32KB PRG-ROM
• 8KB CHR-ROM/RAM

The emulator maps keyboard keys to NES controller buttons:

• Only Mapper 0 (NROM) is supported
• No APU (Audio Processing Unit)
• PPU rendering is not fully implemented
• No sprite or background rendering

To make this a fully functional emulator:

1. PPU Rendering: Implement background and sprite rendering
2. More Mappers: Implement additional mappers (MMC1, MMC3, etc.)
3. APU: Add audio support
4. Save States: Implement save/load functionality

This is an educational project for learning NES emulation.