chip8-emu's Introduction

CHIP-8 Emulator

This is a CHIP-8 emulator written in JavaScript. Try it here: http://mir3z.github.io/chip8-emu/

Features

The emulator has a decent implementation of all 35 CHIP-8 op-codes, all of which are well-tested.

Two known "quirks" have also been implemented (see: chip8.CPU#quirks):

Load/store quirks - Instructions LD [I], Vx and LD Vx, [I] increments value of I register but some CHIP-8 programs assumes that they don't.
Shift quirks - Shift instructions originally shift register VY and store results in register VX. Some CHIP-8 programs incorrectly assumes that the VX register is shifted by this instruction, and VY remains unmodified.

Project repository contains 90 CHIP-8 roms and their descriptions which can be found at http://chip8.com (CHIP-8 Program Pack). All of them were checked and should work fine on the emulator. It is a common issue among emulators I have tested, that some of ROMS were not working correctly - this is mostly because of quirks I have mentioned above and errors in op-codes implementation.

Original CHIP-8 keyboard layout is mapped to PC keyboard as follows by default:

|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|

Usage

The simplest way to set up the emulator is the following code:

// Initialize chip8 with default options
chip8.initialize({
    ctx: document.querySelector('canvas').getContext('2d')
});

// Load ROM file asynchronously...
chip8.loadROM('roms/Puzzle.ch8', function () {
    // ... and run emulator when ROM loading is done
    chip8.run();
});

Take a look at API documentation the learn more advanced usage.