NES Emulator

NOTE: This is still very much a work in progress.

TODO

• Implement 6502 CPU (minus APU)

  • Official opcodes
  • Unofficial opcodes
  • Ensure cycle accuracy

• Create 6502 CPU test runner for single-step tests

• Implement iNES 1.0 ROM parsing

• Implement Bus-centric architecture (NES wrapper handles orchestration)

• Implement interrupt handling

  • Non-maskable-interrupts
  • Software-defined interrupts

• Implement user-input via Joypad 1

• Implement cycle-accurate DMA transfer through Bus

• Implement PPU

  • Background nametable rendering
  • 8x8 sprite rendering (with horiz/vert flips)
  • 8x16 sprite rendering
  • Detect sprite-overflow
  • Sprite collision detection

• Encapsulate mapper logic behind Cartridge trait

• Implement APU

Resources

• 6502 opcode references:
  • https://www.nesdev.org/obelisk-6502-guide/reference.html
  • http://www.6502.org/tutorials/6502opcodes.html
• Illegal opcodes: https://www.masswerk.at/nowgobang/2021/6502-illegal-opcodes
• Single-step opcode tests: https://github.com/SingleStepTests/65x02/tree/main/nes6502/v1
• iNES file format spec: https://formats.kaitai.io/ines/index.html
• snake.nes: https://skilldrick.github.io/easy6502/#snake
• PPU timing chart: https://www.nesdev.org/w/images/default/4/4f/Ppu.svg
• PPU timing details: https://www.nesdev.org/wiki/PPU_rendering