This book is a tutorial and reference manual for the UCSD Pascal language and operating system. It is written for programmers who have a working knowledge of UCSD Pascal or extensive experience with Standard Pascal. The intention of this book is to provide such advanced programmers with practical knowledge and perspectives that will enable them to write complex UCSD Pascal programs in the most effective ways possible. Hence, the material presented herein contains not only descriptions of the language, but also programming examples and architectural discussions not available in any other text.