The OS kernel and this book were produced as part of an advanced individual course at the Royal Institute of Technology, Stockholm. The authors had previously taken courses in OS theory, but had only minor practical experience with OS kernel development. In order to get more insight and a deeper understanding of how the theory from the previous OS courses works out in practice, the authors decided to create a new course, which focused on the development of a small OS. Another goal of the course was writing a thorough tutorial on how to develop a small OS basically from scratch, and this short book is the result. …