I realized the other day that I've written hundreds of thousands of JavaScript, etc. and don't know how virtual memory, for example, works.
Anything is appreciated! Thank you!
https://www.cs.washington.edu/students/ugrad/degree_requirem...
Wikipedia is pretty decent in most topics.
Also, I've found that GeeksForGeeks is pretty neat too: http://www.geeksforgeeks.org/
But if what you are after is insight into how a computer works I found that I had my 'ah-ha' moment while learning C, Assembly (intel), and writing a compiler. I did have to have a slight basis in computer architecture, but that compiler project I worked on made everything click.
(side note on writing a compiler. Read, Decode, Execute. There are no short cuts around those series of steps).
If you are looking for a book I would recommend the 'Dragon Book'
http://www.amazon.com/Compilers-Principles-Techniques-Tools-...
I found a paper copy of the international version for cheap (like $10 US if I remember) that was amazing.
Suitable for lifelong learning.