I second this recommendation. Not being a CS major I didn't take an OS course so I worked through the first part of the OSTEP book and found it to be very well-

I second this recommendation. Not being a CS major I didn't take an OS course so I worked through the first part of the OSTEP book and found it to be very well-written and much less intimidating. I haven't finished reading it entirely yet and didn't do any of the labs but I liked the big picture approach it took to OS design.