This computer organization textbook is for readers who are interested in computer architecture. The content is related to history and evolution of the computer, date representation in a computer, digital logic, central processing unit, memory unit, input/output unit, storage unit, simple computer simulation, and alternative architectures, Readers will be able to explain concepts of computer or organization and architectures, explain features, capable of computer organization and architectures and apply the course knowledge to solve given problems. The author hopes this book will be useful to students and reader who know about the concept of computer architecture.