This book is intended to be used for a first course in computer organization, or computer architecture. It assumes that all digital components can be constructed from fundamental logic gates. The book begins with number representation schemes and assembly language for the MIPS architecture, including assembler directives, pseudo-operations, and floating point instructions. It then describes the machine language instruction formats, and shows the student how to translate an assembly language program to machine language. This is followed by a chapter which describes how to construct an assembler for MIPS. This chapter may be omitted without loss of continuity. This is followed by an introduction to boolean algebra and digital logic, then a possible design of the MIPS datapath. The book concludes with a description of the memory hierarchy, including cache memory, RAM, and virtual memory. Each section concludes with a list of exercises (solutions are available to instructors who have adopted this text in a course).