Rust-NES

Just a hobby NES emulator.

Purpose

I am attempting to make this emulator as hardware-accurate as possible, for two reasons:

• To see how good I actually am at modeling a real-world system in software
• I have no idea how accurate an NES emulator needs to be for it to play games well. I guess I will figure that out along the way, but I like to play things safe.

In addition, I want to learn more about real-time systems that require shared resources.

Usage

• Compiling my example ROM (A really stupid test program):
  • Ensure you have freem's asm6f installed (available in the AUR as asm6f package)
  • asm6f sample.asm
• Running the Emulator:
  • Have the Rust build system set up
  • cargo run --release -- [ROM.nes]

Roadmap

• Basic hardware layout
• Header decoding
• Memory Bus
  • Correct hardware rerouting
  • Mappers:
    • none yet! :P
• 6502 core (56 instructions, 151 opcodes, all cycle-accurate)
  • ADC
  • AND
  • ASL
  • BCC
  • BCS
  • BEQ
  • BIT
  • BMI
  • BNE
  • BPL
  • BRK (1 opcode)
  • BVC
  • BVS
  • CLC
  • CLD
  • CLI
  • CLV
  • CMP
  • CPX
  • CPY
  • DEC
  • DEX
  • DEY
  • EOR
  • INC
  • INX
  • INY
  • JMP
  • JSR
  • LDA (8 opcodes)
  • LDX (5 opcodes)
  • LDY (5 opcodes)
  • LSR
  • NOP (1 opcode)
  • ORA
  • PHA
  • PHP
  • PLA
  • PLP
  • ROL
  • ROR
  • RTI
  • RTS
  • SBC
  • SEC
  • SED
  • SEI
  • STA (7 opcodes)
  • STX (3 opcodes)
  • STY (3 opcodes)
  • TAX (1 opcode)
  • TAY (1 opcode)
  • TSX
  • TXA (1 opcode)
  • TXS
  • TYA (1 opcode)
• PPU
• APU

Helpful Resources

• Thanks to NESDEV for their simply amazing work on documenting the NES hardware
• mass:werk's excellent Instruction Set reference
• doppelganger's Super Mario Bros. Disassembly for giving me some good assembly code examples to reference.