CHIP-8 Emulator

A simple CHIP-8 emulator written in C using SDL2.

Spec

• All instructions are 2 bytes long and are stored most-significant-byte first.
• 4K RAM (0x0 ~ 0xfff)
  • 0x0 ~ 0x1ff: reserverd for system
  • 0x200 ~ 0xe9f: freely used RAM
  • 0xea0 ~ 0xeff: reserved for stack, internal use and other variables
  • 0xf00 ~ 0xfff: for display
• 64x32 resolution display (1 bit per pixel)
• Font sprite starts at 0x000, see details below
• 8-bit delay and sound timer
• 16 8-bit registers V0 ~ VF
• A 16-bit program counter (PC)
• A 8-bit stack pointer (SP)
• One 16-bit address register I
• Instruction set
  • 8XYE: VF should be the most significant bit of VX not VY prior to the shift
  • 8XY6: Same as above
  • FX55: Don't increset I
  • FX65: Same as above

Keymapping

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

Build

Mac OS:

• Install SDL2: brew install sdl2
• Git clone the repo
• make buildmac && make test

Windows:

• Download MSYS2 64bit from here: https://www.msys2.org/
• Update MSYS2: pacman -Syu
• Install build tools and SDL2: pacman -S make git mingw-w64-x86_64-toolchain mingw64/mingw-w64-x86_64-SDL2
• Start MSYS2 MinGW 64-bit Shell
• Git clone the repo
• make buildwin && make test

Test

There are a few roms in the rom directory of repo.

BC_Test.ch8 and test_opcode.ch8 are used for testing the fundamental functions of our emulator.

test.ch8 is used for testing arbitrary instructions written by ourself.

All others are games for fully testing our emulator 🎮.

Reference

• http://devernay.free.fr/hacks/chip8/C8TECH10.HTM#2.4
• https://code.austinmorlan.com/austin/chip8-emulator
• https://github.com/massung/CHIP-8