All societies of computing should acquire some understanding and appreciation of a computer system's functional components, characteristics, performances, and interactions. Sci-Tech communities need to understand the computer organization and architecture in order to structure a program so that it runs more efficiently on a real machine. The emphasis of this book is to deal with Computer Structure and Function, Digital Logic and System, Data Representation, Assembly Level Machine Organization, Memory System Organization and Architecture, Fundamentals of Input/Output, Simple Data Paths and Control Unit - Hardwired vs. Micro-programmed Realizations, and Instruction Pipelining and Instruction-Level Parallelism (ILP). Moreover, the book prepared with detail explanation, different self-exercises and simple figures. Thus, any sort of reader can comprehend the book and get a countless knowledge of computer organization and architecture easily.