Please don't! Build something original . It really is possible! Once you've built a UNIX clone, you have polluted your mind as an OS designer. I did so (as a standard college homework assignment) and it took me years to shake the crud out of my head. As for the tutorial, it is very well written, but x86-32-centric and therefore worthless. There are nontrivial differences between x86-32 and x86-64 from the standpoint…
As for the x86/x64 differences, they're by no means insurmountable once you have the concepts down, which is exactly what this tutorial provides.