Completely revised and updated, Computer Systems, Fourth Edition offers a clear, detailed, step-by-step introduction to the central concepts in computer organization, assembly language, and computer architecture. It invites students to explore the many dimensions of computer systems through a top-down approach to levels of abstraction. By examining how the different levels of abstraction relate to one another, the text helps students look at computer systems and their components as a unified concept.The new Fourth Edition is based on the Pep/8 assembler and simulator, which was designed to teach the basics of the classic von Neumann machine. Pep/8 now includes a new symbolic trace feature that displays global variables and the run-time stack in real time as the student single steps through the program. Throughout the text Warford emphasizes the importance of mastering fundamental computer concepts, which provides a basis for understanding both current and future technology, while also stressing the importance of keen problem solving skills. Computer Systems, Fourth Edition covers all of the core topics in the Architecture and Organization category of the ACM-IEEE Curriculum 2001 Guidelines for Computer Science.