Check out The Code Book by Simon Singh . It is about the history of cryptography, but along the way, it also has some history of computing, and it's an entertaining read.
What's the difference between this one and this one ?
This book is great. I read it a number of years ago and couldn't get enough.
"Alan Turing: The Enigma" http://www.amazon.com/Alan-Turing-Enigma-Andrew-Hodges/dp/08... , supposedly the best biography of Turing, I enjoyed it. There's quite a bit on his work on the Enigma but not technical.