This textbook Digital Principles and System Design has been written to meet the requirements of students of Engineering Colleges and Polytechnics. This Book is aimed to provide the Students a Comprehensive Knowledge of Boolean Algebra And Logic Gates, Combinational Logic, Synchronous Sequential Circuits, Asynchronous Sequential Logic Circuits, Memory And Programmable Logic. The materials of the reference books have noteworthy influence on this book. The author is thankful to her colleagues and students for their assistance in the preparation of this book. Finally, the author wishes to express her gratitude to M/s. Sara Publications for bringing out this book within a short span of time.