The book is devoted to basic principles of applied theory of digital automata (finite state machines). The number systems, axioms and laws of Boolean algebra, methods for specification and minimization of Boolean functions are considered. The design methods are discussed targeted on implementation of combinational circuits using logic elements starting from simple gates to programmable logic devices. There are examples of specification and minimization of abstract automata. The basic principles of structural synthesis are discussed with the impact on canonical method of structural synthesis. The final part of the book deals with design methods of control automata. The book is written for students and postgraduates in computer engineering and digital automatics, as well as for professionals in digital design.