This introductory text on 'digital logic and computer organization' presents a logical treatment of all the fundamental concepts necessary to understand the organization and design of a computer. It is designed to cover the requirements of a first-course in computer organization for undergraduate computer science, electronics, or mca students. Beginning from first principles, the text guides students through to a stage where they are able to design and build a small computer with available ic chips. Starting with the foundation material on data representation, computer arithmetic and combinatorial and sequential circuit design, the text explains alu design and includes a discussion on an alu ic chip. It also discusses algorithmic state machine and its representation using a hardware description language before shifting to computer organization. The evolutionary development of a small hypothetical computer is described illustrating hardware-software trade-off in computer organization. I