This book is on digital system design for programmable devices, such as FPGAs, CPLDs, and PALs. A designer wanting to design with programmable devices must understand digital system design at the RT (Register Transfer) level, circuitry and programming of programmable devices, digital design methodologies, use of hardware description languages in design, design tools and environments; and finally, such a designer must be familiar with one or several digital design tools and environments. Books on these topics are many, and they cover individual design topics with very general approaches. The number of books a designer needs to gather the necessary information for a practical knowledge of design with field programmable devices can easily reach five or six, much of which is on theoretical concepts that are not directly applicable to RT level design with programmable devices. The focus of this book is on a practical knowledge of digital system design for programmable devices. The book covers all necessary topics under one cover, and covers each topic just enough that is actually used by an advanced digital designer. In the three parts of the book, we cover digital system design concepts, use of tools, and systematic design of digital systems. In the first chapter, design methodologies, use of simulation and synthesis tools and programming programmable devices are discussed. Based on this automated design methodology, the next four chapters present the necessary background for logic design, the Verilog language, programmable devices, and computer architectures.