He wrote a book called iWoz. It's definitely worth a read if you're interested in him. He was obsessed with building his own computer from a young age.
I read that book and while I can recommend it, I felt Woz didn't dwell particularly long on any single aspect - it was just a nice long polished story, like something he had told many times before but this time collected into a book. I don't think I was looking for secrets or drama, but the man has done some amazing things and he puts so little emphasis on them in the book. Does a Wozniak biography exist that is not an auto-biography?
Yup. Far better than the Jobs autobiography, though both were fascinating people I think Woz resonates with the average person much better, though his skills and intellect are far above average.