This book has been designed to meet the needs of students of electronic engineering, computer science and physics. It will also be useful to engineers and scientists who did not have the opportunity to study digital techniques and microprocessors in their college days. The book can be used for self study, practice and as a guide to what can be expected in the examination. The book consists of 12 chapters and 8 appendices. Each chapter contains: Solved problems (300 in the book) Unsolved problems with answers (320 in the book) Questions with Answers (450 in the book) There is separate section containing 465 multiple choice questions (with answers) covering all the topics. Readers will find the exhaustive glossary of over 500 terms very useful. The book consists of set of problems, review questions, multiple-choice questions, and a glossary. Out of 530 problems, more than 300 have been solved in detail highlighting the important concepts involved. Answers for the others have been given in Appendix H. The fundamental concepts of digital techniques have been introduced in Chapter 1. Chapter 2 deals with semiconductor devices bearing in mind their application in digital circuits. Based on these devices, various digital circuits, reffed to as logic families, have been discussed in detail in Chapter 3. A number of appendices has been introduced have been provided to include the useful information,such as the summary of the operation of logic gates, Boolean algebraic theorems, digital ICs, summary of 8085s instruction set, etc.