Not only did he know and love product engineering, it's all he really wanted to do. He told me once that part of the reason he wanted to be CEO was so that nobody could tell him that he wasn't allowed to participate in the nitty-gritty of product design. He was right there in the middle of it. All of it. As a team member, not as CEO. He quietly left his CEO hat by the door, and collaborated with us. He was basically the Product Manager for all of the products I worked on, even though there eventually were other people with that title, who usually weren't allowed in the room :)

"What it's Really Like Working with Steve Jobs"