I recommended The Elements of Computing Systems: Building a Modern Computer from First Principles http://www1.idc.ac.il/tecs/ http://www1.idc.ac.il/tecs/ It's

I recommended The Elements of Computing Systems: Building a Modern Computer from First Principles http://www1.idc.ac.il/tecs/ http://www1.idc.ac.il/tecs/ It's a great book/course which takes you through all the abstraction layers from chip architecture to OO-programming. After that, I recommend SICP. When you are self-taught you easily end up with big holes in your knowledge, because you typically focus on what you need to know in your current project. These two books are great because they cover a lot of ground (different abstraction levels, different paradigms) while still remaining practical.