For a good high-level introduction aimed at technical readers who aren't CompEs, I suggest Jon Stokes "Inside the Machine: An Illustrated Introduction to Microp

For a good high-level introduction aimed at technical readers who aren't CompEs, I suggest Jon Stokes "Inside the Machine: An Illustrated Introduction to Microprocessors and Computer Architecture". It's a readable and reasonably in-depth explanation of how a modern processor works without going into the level of detail that a full-blown computer architecture textbook would. Charles Petzold's "Code: The Hidden Language of Computer Hardware and Software" is also well regarded, but is aimed more at non-technical people.