CHIP-8 Emulator

A fast, accurate CHIP-8 interpreter/emulator written in modern C++17.

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What is CHIP-8?

CHIP-8 is an interpreted programming language developed in the mid-1970s for use on 8-bit microcomputers. It was designed to allow video games to be more easily programmed for these computers. CHIP-8 programs are run on a virtual machine, making it an excellent target for emulation projects.

Specifications

Component	Details
Memory	4KB (4096 bytes)
Display	64×32 pixels, monochrome
Registers	16 general-purpose 8-bit registers (V0-VF)
Stack	16 levels
Timers	Delay timer, Sound timer (60Hz)
Input	16-key hexadecimal keypad
Instructions	35 opcodes, all 2 bytes long

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Features

• Complete implementation of all 35 CHIP-8 opcodes
• Configurable display scaling
• Adjustable emulation speed
• Clean, well-documented codebase
• Cross-platform support (macOS, Linux, Windows)

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Building

Prerequisites

• CMake 3.10 or higher
• C++17 compatible compiler (GCC 7+, Clang 5+, MSVC 2017+)
• SDL2 development libraries

Installing SDL2

macOS (Homebrew):

brew install sdl2

Ubuntu/Debian:

sudo apt-get install libsdl2-dev

Windows (vcpkg):

vcpkg install sdl2

Build Instructions

# Clone the repository
git clone https://github.com/mert-ergun/chip-8.git
cd chip-8

# Create build directory
mkdir build && cd build

# Configure and build
cmake ..
make

# The executable will be created as 'chip8'

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Usage

./chip8 <scale> <delay> <rom_path>

Arguments

Argument	Description	Recommended
scale	Display scale factor (window size = 64×scale by 32×scale)	10-20
delay	Cycle delay in milliseconds (controls emulation speed)	1-5
rom_path	Path to the CHIP-8 ROM file (.ch8)	-

Example

./chip8 15 2 ../roms/IBMLogo.ch8

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Keyboard Mapping

CHIP-8 uses a 16-key hexadecimal keypad. This emulator maps it to your keyboard as follows:

CHIP-8 Keypad           Keyboard
┌───┬───┬───┬───┐      ┌───┬───┬───┬───┐
│ 1 │ 2 │ 3 │ C │      │ 1 │ 2 │ 3 │ 4 │
├───┼───┼───┼───┤      ├───┼───┼───┼───┤
│ 4 │ 5 │ 6 │ D │  =>  │ Q │ W │ E │ R │
├───┼───┼───┼───┤      ├───┼───┼───┼───┤
│ 7 │ 8 │ 9 │ E │      │ A │ S │ D │ F │
├───┼───┼───┼───┤      ├───┼───┼───┼───┤
│ A │ 0 │ B │ F │      │ Z │ X │ C │ V │
└───┴───┴───┴───┘      └───┴───┴───┴───┘

Press ESC to exit the emulator.

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Project Structure

chip-8/
├── CMakeLists.txt      # Build configuration
├── LICENSE             # MIT License
├── README.md           # This file
├── roms/               # ROM files for testing
│   └── IBM Logo.ch8    # Classic test ROM
└── src/
    ├── chip8.cpp       # CHIP-8 CPU implementation
    ├── chip8.hpp       # CHIP-8 class definition
    ├── main.cpp        # Entry point
    ├── platform.cpp    # SDL2 platform layer
    └── platform.hpp    # Platform class definition

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Opcodes Reference

Click to expand full opcode table

Opcode	Mnemonic	Description
00E0	CLS	Clear the display
00EE	RET	Return from subroutine
1NNN	JP addr	Jump to address NNN
2NNN	CALL addr	Call subroutine at NNN
3XKK	SE Vx, byte	Skip next instruction if Vx == KK
4XKK	SNE Vx, byte	Skip next instruction if Vx != KK
5XY0	SE Vx, Vy	Skip next instruction if Vx == Vy
6XKK	LD Vx, byte	Set Vx = KK
7XKK	ADD Vx, byte	Set Vx = Vx + KK
8XY0	LD Vx, Vy	Set Vx = Vy
8XY1	OR Vx, Vy	Set Vx = Vx OR Vy
8XY2	AND Vx, Vy	Set Vx = Vx AND Vy
8XY3	XOR Vx, Vy	Set Vx = Vx XOR Vy
8XY4	ADD Vx, Vy	Set Vx = Vx + Vy, VF = carry
8XY5	SUB Vx, Vy	Set Vx = Vx - Vy, VF = NOT borrow
8XY6	SHR Vx	Set Vx = Vx >> 1, VF = LSB
8XY7	SUBN Vx, Vy	Set Vx = Vy - Vx, VF = NOT borrow
8XYE	SHL Vx	Set Vx = Vx << 1, VF = MSB
9XY0	SNE Vx, Vy	Skip next instruction if Vx != Vy
ANNN	LD I, addr	Set I = NNN
BNNN	JP V0, addr	Jump to NNN + V0
CXKK	RND Vx, byte	Set Vx = random byte AND KK
DXYN	DRW Vx, Vy, n	Draw sprite at (Vx, Vy), height N
EX9E	SKP Vx	Skip if key Vx is pressed
EXA1	SKNP Vx	Skip if key Vx is not pressed
FX07	LD Vx, DT	Set Vx = delay timer
FX0A	LD Vx, K	Wait for key press, store in Vx
FX15	LD DT, Vx	Set delay timer = Vx
FX18	LD ST, Vx	Set sound timer = Vx
FX1E	ADD I, Vx	Set I = I + Vx
FX29	LD F, Vx	Set I = location of sprite for digit Vx
FX33	LD B, Vx	Store BCD of Vx at I, I+1, I+2
FX55	LD [I], Vx	Store V0-Vx in memory starting at I
FX65	LD Vx, [I]	Read V0-Vx from memory starting at I

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Resources

• Cowgod's CHIP-8 Technical Reference
• CHIP-8 Wikipedia
• Awesome CHIP-8

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License

This project is licensed under the MIT License - see the LICENSE file for details.

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Made with coffee and C++