Grab Tannenbaum's "Operating Systems, Design and Implementation" - aka "The Minix book" - you will LOVE the book, and walk away having an genuine understanding of what's going on under the hood in a kernel, and be able to write your own

Amazon link https://www.amazon.com/Operating-Systems-Design-Implementati...

Get the Minix book:

http://www.amazon.com/Operating-Systems-Design-Implementatio...

Tanenbaum's ineffable "Operating Systems Design and Implementation" and MINIX (a learning OS) existed then, and was what Linus Torvalds studied before creating Linux:

http://www.amazon.com/dp/0131429388