2597	 Monitors An Operating System Structuring Concept	 This paper develops Brinch-Hansen s concept of a monitor as a method of structuring an operating system. It introduces a form of synchronization describes a possible method of implementation in terms of semaphores and gives a suitable proof rule. Illustrative examples include a single resource scheduler a bounded buffer an alarm clock a buffer pool a disk head optimizer and a version of the problem of readers and writers. monitors operating systems scheduling mutual exclusion synchronization system implementation languages structured multiprogramming
