The second chapter of the book, The Design and Implementation of the 4.4BSD Operating System is excerpted here with the permission of the publisher. No part of it may be further reproduced or distributed without the publisher's express written permission. The rest of the book explores the concepts introduced in this chapter in incredible detail and is an excellent reference for anyone with an interest in BSD UNIX. More information about this book is available from the publisher, with whom you can also sign up to receive news of related titles. Information about BSD courses is available from Kirk McKusick.