Personally, although written in 1968, I consider that this book continues to be of relevance as a first introduction to computer engineering, even today. Wilkinson describes the computer circuits, that he built with his secondary school class, in a way that brings home how straightforward the concepts really are; and this is applicable in any digital technology: such as pneumatic, hydraulic, optical or even DNA logic, not just the PNP transistor technology that he had as his vehicle).