Complete description and explanation of a small workstation operating system which is moderately object oriented. About more than 95 percent of the program texts are available for free. Important parts of the program texts are included in the book. About more than 95 percent of the program texts are written in a high level, type safe, moderately object oriented language. There is almost no need for using or understanding assembler except for the compiler which emits native CPU instructions. Even the compiler and garbage collector are presented in great detail. In understanding The Oberon System one will understand many concepts like MVC in their essence.