CSCE 3613 Lecture Notes - Lecture 3: Infinite Loop, Job Scheduler, Operating System
26 Aug 2016
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88tb long-term storage 35 tb of scratch storage. Multiprogramming :one job selected and run via job scheduling. Organizes jobs(code and data) so cpu always has one to execute. When it has to wait(for i/o for example), os switches to another job. Timesharing: logical extension in which cpu switches jobs so frequently that users can interact with each job while running, interactive computing. Response time should be less than 1 second. Each user has at least one program executing in memory -> process. If several jobs ready to run, -> cpu scheduling. If processes don t fit in memory, swapping moves them in and out to run. Virtual memory allows execution of processes not completely in memory. Software error or request creates exception or trap. Other process problems include infinite loop, processes modifying each other or the os. Dual-mode operation allows os to protect itself and other system components. Some instructions designated as privileged, only executable in kernel mode.
