David J. Eck 
The Most Complex Machine [PDF ebook] 
A Survey of Computers and Computing

This introduction to computers presents the fundamental ideas and principles on which modern computers are built. While used as a text for courses in computer appreciation as well as introductions to computer science, the book has found a wide audience among computer users who wish to understand the basis of the machines that form and transform our society.
What Computers Do • Teaching Silicon to Compute • Building a Computer •†Theoretical Computers • Real Computers • Programming • Subroutines and Recursion • Real Programming Languages • Applications • Cooperating Computers • Graphics • Artificial Intelligence • Answers • The text is supplemented by a web site that gives access to other problems and projects.