Learning Operating Systems

When you are starting out with learning about operating systems, it's easy to be overwhelmed. So you should learn about options and choose wisely.

My advice would be studying two books:

- general text (theory);

- implementation text (practice with OS of choice).

Theory

My best bet is Operating System Concepts by Silberschatz, Galvin and Gagne. It is a commonly used book on operating system courses. It is also called "dinosaur book" due to it's fancy cover. This is a great modern introduction into OS, and, in my opinion, is the best book to start from scratch.

Another good option is Operating Systems by Deitel, Deitel and Choffnes. It is a great alternative to "dinosaur book".

Others might recommend one of Tanenbaum's books, for example Modern Operating Systems. Yeah, there is a lot of talk about minix (and how bad Windows architecture is) but that's Tanenbaum.

If you prefer video lections, then there is a UC Berkeley Computer Science 162 on YouTube.

Practice

Linux:
- Linux Kernel Development by Robert Love, 

- Linux Kernel Architecture by Wolfgang Mauerer,
- Understanding The Linux Virtual Memory Manager by Mel Gorman

Windows: 

- Windows Internals by Russinovich and Solomon,

- Programming Windows by Charles Petzold.

- Channel 9 videos (Windows kernel)

If you just want to have fun, you can try The Little Book About OS Development; it is a free practical guide to writing your own x86 operating system.

Now you are ready for my last advice: the source to Linux and lots of other systems is out there, so read it!