CHIP-8 Emulator

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Overview

This project is a complete CHIP-8 emulator written from scratch in Rust. The emulator recreates the original CHIP-8 virtual machine by implementing its memory model, registers, timers, instruction set, display system, keyboard input, and sound output.

The project was built as a systems programming exercise focused on understanding how CPUs execute instructions through the fetch-decode-execute cycle. It emulates the original 1970s architecture while providing a modern desktop interface using Rust.

Features

• Complete CHIP-8 instruction set implementation
• 4KB emulated memory system
• 16 general-purpose registers (V0-VF)
• Program counter, stack, and index register support
• 64x32 monochrome display renderer
• Pixel scaling for modern displays
• Keyboard input mapped to CHIP-8 hexadecimal keypad
• Delay timer implementation
• Sound timer with audio output
• ROM loading and execution
• Real-time FPS counter in the window title
• Font sprite loading and rendering

Concepts Demonstrated

• Emulator and virtual machine development
• CPU fetch-decode-execute architecture
• Opcode decoding using bitwise operations
• Memory management and address manipulation
• Stack operations and subroutine execution
• Register-based CPU design
• Real-time rendering and frame updates
• Keyboard input handling
• Audio generation and playback
• Timing systems and synchronization
• State management in Rust
• Modular software architecture

Architecture

The emulator executes CHIP-8 programs by repeatedly performing the CPU cycle:

1. Fetch the next opcode from memory
2. Decode instruction fields using bit masking
3. Execute the corresponding operation
4. Update timers and display state
5. Render the display buffer

The display is stored as a 64x32 boolean framebuffer and scaled to a larger window for visibility. Keyboard input is continuously mapped to the CHIP-8 keypad layout, allowing ROMs to receive user input exactly as they would on the original system.

Technical Details

• CPU execution rate of approximately 600Hz
• Display refresh rate of 60Hz
• 35 CHIP-8 opcodes implemented
• 16-key hexadecimal keypad support
• 64x32 monochrome framebuffer
• Audio generated through a sine wave beeper
• Window rendering via minifb

Requirements

• Language: Rust
• Cargo package manager
• Desktop platform supporting minifb

Libraries Used

• Rust
• minifb — window creation and display rendering
• rodio — audio playback

Learning Outcomes

This project provided hands-on experience with low-level systems programming concepts including CPU architecture, instruction decoding, memory management, bitwise operations, and real-time application development. Building the emulator from scratch reinforced an understanding of how software interacts with virtual hardware and how classic computing systems execute programs.