Writing Chip-8 Emulator (interpreter) in Crystal

It was the middle of a week, around noon I think.

I thought to myself “I should write a yet-another NES emulator, that would be awesome!”.

A few minutes later I am reading blog posts, articles, browsing repositories.

And I am like “Damn it looks complicated”.

So I decided to start with something much, much simpler - Chip-8 that was developed in mid-1970s. Because it’s architecture was pretty straightforward it was a project I was able to finish within few days without a rush - and that included whole day+ of debugging why the hell drawing on screen doesn’t work as expected (reason: Crystal type interference gave me unsigned int8 on one calculation, but it somehow awkwardly handled overflow of int8 - I didn’t have chance to dig into it yet).

I am not going to write any step-by-step guide, because I have found two just fabulous blog posts related to the task - one is about writing Chip-8 emulator in Javascript, and the other one is complete guide with detailed explanations how to do it in C++ - big kudos for the authors. I stole a lot of code from the latter after my debugging frustration :P.

You can check out my result here. It is very messy, but it should give you a basic idea of how to do it in Crystal and how to use SDL2 bindings (that I have never had chance to use before in my life).

Note: Direct source of the comic above