Ask HN: What is the most practical guide for learning and implementing OS?

Last month i came across a hacker news question which was, What is the most practical guide for learning Network ? http://beej.us/blog/data/nodejs-httpserver/

This is the gem i found in that post you can go to this blog to get an idea what i am really looking for. The guide should focus on implementing the stuff rather than talking about it on conceptual and abstract level. Some more blogs i have gone through also on hackernews related to OS are : http://3zanders.co.uk/2017/10/13/writing-a-bootloader/

http://arjunsreedharan.org/post/82710718100/kernel-101-lets-write-a-kernel

I really enjoy these kind of articles. If you guys know something related to Operating System. Please bring it to me. Thanks in advance.