I'd like to recommend the book "Racing the Beam" to any technically-inclined 2600 or old game fans. It's a little dry but still interesting. Covers the history and some of the programming details of the 2600. Also has an awesome title and cover.
Probably the most interesting thing was that there wasn't enough memory for a frame buffer, so the position of each sprite had to be calculated just before the line they were on was drawn.