As someone who's been writing their own Unix Kernel, this tutorial is good for the beginnings. It's important to read the osdev page on the known bugs though, a

As someone who's been writing their own Unix Kernel, this tutorial is good for the beginnings. It's important to read the osdev page on the known bugs though, and personally I don't think this tutorial focuses enough on actual kernel design. I would recommend reading and looking at other material while working through this tutorial.