Rusty Game Boy Emulator

Overview

A Game Boy (DMG-01) emulator written in Rust, focusing on accurate emulation and educational purposes. This project is both a learning experience in systems programming and a practical implementation of hardware emulation concepts. I hope to also blog the process of building this project, so check back for more.

Key Achievements

Core Implementation

• Implemented fundamental CPU components including registers, program counter, and stack pointer
• Successfully executed basic arithmetic and control flow instructions
• Developed memory bus with address space mapping capabilities

Instruction Set Progress

• Core arithmetic operations (ADD, SUB, INC, DEC)
• Control flow instructions (JP, CALL, RET, HALT, NOP)
• Stack operations (PUSH, POP)
• Memory operations (partial LD instruction support)

Technical Architecture

CPU Implementation

• 8-bit register implementation
• Program counter and stack pointer management
• Instruction decoding and execution pipeline
• Clock cycle accuracy focus

Memory Management

• Memory address space mapping (0x0000 - 0xFFFF)
• RAM and VRAM access implementation
• Memory bank controller groundwork

Development Practices

Testing Strategy

• Integration with Blargg’s test ROMs
• Unit tests for CPU operations
• Memory access validation
• Instruction timing verification

Current Development Status

Implemented Features

• Basic CPU architecture
• Core instruction set fundamentals
• Memory bus framework
• Basic address space mapping

In-Progress Features

• Expanding CPU instruction set
• Memory controller improvements
• ROM loading capabilities
• Interrupt handling system

Future Roadmap

Short-term Goals

• Complete basic instruction set implementation
• Pass Blargg’s CPU test ROMs
• Implement timer system
• Add interrupt handling

Long-term Goals

• Graphics processing unit (PPU) implementation
• Audio processing unit (APU) support
• Game Boy Color compatibility
• Save state functionality
• Debugger interface

Technical Resources

Documentation

• Pan Docs for comprehensive GB specs
• Game Boy: Complete Technical Reference
• Interactive Game Boy Opcode Table
• Gameboy Development Manual

Test Suites

• Blargg’s test ROMs
• Mooneye GB test suite

Development Tools

• Rust
• Cargo
• Test ROM suites (Blargg, Mooneye)
• Visual Studio Code
• Rust Rover

Learning Outcomes

• Deeper understanding of CPU architecture and the Game Boy instruction set
• Reading technical documentation including reference manuals
• Memory management concepts
• Systems programming with bit operations