CPU

• Implement auto_pc_advance instruction flag
• Real test ROMs with ca65
• Refactor + reduce code duplication in both source and tests
• Doubtful instruction implementations
  • SBC
  • BRK
  • RTI
  • RTS
• Check if status flags modified during instructions are only set if relevant, or always overridden (latter is currently the case)
• Check overflow and wrapping rules for each instruction

Bus

• Delegate read/writes to devices

PPU

• Pre-rendered frame buffer