An Operating Systems Vade Mecum

PREFACETraditionally, a vade mecum (pronounced ‘‘VAHdee MAYkem’’) is a laboratory manualthat guides the student step by step through complex procedures. Operating systems arecomplex mixtures of policy and mechanism, of algorithm and heuristic, and of theoreticalgoals and practical experience. This vade mecum tries to unify these diverse points ofview and guide the novice step by step through the complexities of the subject. As a text,this book is intended for a first course in operating systems at the undergraduate level.The subject has so many individual parts that its practitioners and teachers often concentrateon subareas and ignore the larger concepts that govern the entire subject. I havetried to rectify that situation in this book by structuring the presentation about the dualideas of resource management and beautification.To unify disparate threads of discussion, I have taken the liberty introducing namesfor recurrent themes and glorifying them with the title ‘‘principles.’’ I hope that thisorganization and nomenclature will help the reader to understand the subject better and tointegrate new ideas into the same framework.Each technical term that is introduced in the text is printed in boldface the firsttime it appears. All boldface entries are collected and defined in the glossary. I havestriven to use a consistent nomenclature throughout the book. At times this nomenclatureis at odds with accepted American practice. For example, I prefer to call computermemory ‘‘store.’’ This name allows me to unify the various levels of the storage hierarchy,including registers, main store, swap space, files on disk, and files on magnetic tape.I also prefer the single word ‘‘transput’’ to the clumsier but more common term‘‘input/output.’’ Although I found this term jarring at first, I have grown to like it.Each chapter closes with a section on perspective, suggestions for further reading,and exercises. The perspective section steps back from the details of the subject andsummarizes the choices that actual operating systems have made and rules of thumb fordistinguishing alternatives. It also fits the subject of the chapter into the larger picture.The suggestions for further reading have two purposes. First, they show the reader wheremore information on the subject discussed in the chapter may be found. Second, theypoint to research articles related to the subject that describe actual implementations andxi