The textbook for CPSC 457 is Operating Systems Concepts (Eighth Edition), by Silberschatz, Galvin, and Gagne. Published by Wiley, 2009. It is affectionately known as the "dinosaur book", because of the colourful cover design.
Copies of this book are available in the University of Calgary Bookstore for approximately $140. If you are looking for used copies from previous students, you might have to settle for the Seventh Edition. You can survive with the older Seventh Edition, but the lecture materials and readings in this course will be based on the Eighth Edition.
Book Web Site
Supplementary materials for the CPSC 457 textbook are available on the Wiley Web site. The supplementary material for students includes several demos and coding examples. The supplementary material for instructors includes slides, quizzes, assignments, programming projects, and sample solutions.
Here is a link to the student portion of the Web site for the 8th edition.
Here is a link to the instructor portion of the Web site for the 8th edition.