This volume presents assembly language as a vehicle for a concrete introduction to computer architecture and operating systems -- a comprehensive "look under the hood" of IBM microcomputers for readers with a basic knowledge of Pascal or C. Easy to follow and complete, the guide explores: IBM system components; APX assembly language; machine-level aspects of procedures in high-level languages; an overview of I/O ports and device structure; and issues in memory management. Suitable for any Software Engineer who works with personal computers.