Now in its fifth edition, this textbook is intended for an introductory course in digital computer design for B.Sc. students of computer science, B.Tech. students of computer science and engineering, and BCA/MCA students of computer applications.The first part of the book presents the basic tools and develops procedures suitable for the design of digital circuits and small digital systems. It equips students with a firm understanding of logic principles before they move on to study the intricacies of logic organisation and the architecture of computers, covered in the the second part of the book.Besides discussing data representation, arithmetic operations, Boolean algebra and its application in designing combinatorial and sequential switching circuits, the book introduces the Algorithmic State Machines which are used to develop a hardware description language for the design of digital systems.The organisation of a small hypothetical computer is described to illustrate how instruction sets are evolved. Real computers are described and compared with the hypothetical computer. After discussing the features of a CPU, I/O devices and I/O organisation, cache and virtual memory, the book concludes with a new chapter on the use of parallelism to enhance computer speed.In addition, this fifth edition includes new material on CMOS gates, MSI/ALU and Pentium5 architecture; and the chapter on cache and virtual memory has been rewritten.