Working as an engineer with advanced weapon systems for more than 25 years, it was crucial to understand the fundamentals of digital systems design development methods and combinational logic circuits. Whether as a technician or engineer, these fundamentals are the basics of engineering and are essential in interpreting logic gate functionality. The intent of this book is to provide much more information than most commercial engineering references currently offer. In Chapter 1, Karnaugh Maps (K-Maps) with two, three, four, five, and six variables are discussed along with using essential prime implicants, switching functions, and other uses and forms of K-Maps. Chapter 2 discusses an introduction to the Quine-McCluskey Method, Prime Implicant Determination, the Prime Implicant Chart, and the Incomplete Specific Function Simplification. Chapter 3 provides a broad array of Combinational Logic Circuitry, discussing topics such as Exclusive-OR, Exclusive-NOR, Parity, Data Selection/Distribution, Carry Out, and ROM Address Decoder circuits. The chapter review and chapter answer sections provide an extensive number of questions with comprehensive insight to showing how to attain the answers. This book will be an extremely valuable asset for technical and engineering students studying digital system design.