This is a CHIP-8 emulator is written in C++17 and uses SDL2 for sound, graphics and input. It's been written with compatibility in mind due to the various CHIP-8 interpreters available.

CHIP-8 is an interpreted programming language, developed by Joseph Weisbecker. It was initially used on the COSMAC VIP and Telmac 1800 8-bit microcomputers in the mid-1970s.

It has risen in popularity when the CHIP-48 interpreter was made for HP-48 graphic calculators, and hence many games are written for the CHIP-48. These rely on slightly different opcode behaviours compared to the CHIP-8 due to some of the original opcodes being undocumented, which is why this emulator includes different emulation modes to ensure compatibility.

Dependencies:

• C++17 compiler.

  • Linux: GCC 9. Can by installing the g++-9 from the ubuntu-toolchain-r/test PPA repo.
  • Windows: MinGW-w64 8.0 (GCC 9.2). Can be obtained through MSYS2 by installing the mingw-w64-x86_64-gcc pacman package after updating MSYS2 with pacman -Syu.

• SDL2

  • Linux: get SDL2 by running sudo apt install libsdl2-dev.
  • Windows: download the SDL2-2.0.10 development libraries and place them under a new "external" folder in the root directory of this project.

• CMake 3.10

  • Linux: can be obtained from the ubuntu-toolchain-r/test PPA repo or from the Kitware apt repo.
  • Windows: can be downloaded from here.

Compiling

Navigate to a directory to which you want the outputs to go, and run:

• Linux:

  cmake -DCMAKE_BUILD_TYPE=Debug -G "CodeBlocks - Unix Makefiles" <location of this project>

  cmake --build .

• Windows:

  cmake.exe -DCMAKE_BUILD_TYPE=Debug -G "CodeBlocks - MinGW Makefiles" <location of this project>

  cmake.exe --build .

Running

• Linux: Launch as any other program with the correct arguments.
• Windows: add download the SDL2 runtime binaries and put SDL2.dll into the folder with your compiled binary.

In terminal/command line run: chip_8.exe --rom <path> [options]

For more help, including displaying the available options, run: chip_8.exe --help

If audio is not working, set the SDL_AUDIODRIVER environment variable to an appropriate value mentioned here.

The CPU speed and operation modes may need to be changed between ROMs to ensure they work as intended. I've included 3 different operation modes due different ROMs relying on different opcode behaviours, depending on the time period and the interpreter they were written for. Explanations can be found in the links section. They are as follows:

• CHIP8: FX55 and FX65 opcodes increment the instruction counter. 8XY6 and 8XYE registers shift the value in VY and store the result in VX.

• CHIP-48: FX55 and FX65 opcodes increment the instruction counter.

• SCHIP: FX55 and FX65 opcodes don't increment the instruction counter (like on the SCHIP). This is what most ROMs expect, and is the default mode. The emulator doesn't actually support SCHIP opcodes (yet?).

• Revival Studios CHIP-8 Program Pack

• CHIP-8 games under CC0 license

• BestCoder's test ROM

• Cowgod's Chip-8 Technical Reference v1.0

• CHIP-8 on Wikipedia

• Explanation of differing opcode behaviours on CHIP8/CHIP-48/SCHIP

• Explanation on FX55 & FX65 opcodes

• Explanation of timer speeds