There is not much left here, and there is a good reason for it:
First of all, after Microsoft took over GitHub, I started moving all my OS code over to GitLab. So basically you can find the original code of this project here on GitLab.
Second, Vladimir Schneider has invested a lot of his time and developed a way more advanced debugger based on the same idea and generously made it OS here. I would recommend you try using that.