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Operating Systems

Operating Systems. Who’s in charge in there?. Types of Software. Application Software : Does things we want to do System Software : Does things we need done Low level details. Operating System. Operating System : Software that manages the operation of a computer

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Operating Systems

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  1. Operating Systems Who’s in charge in there?

  2. Types of Software • Application Software : Does things we want to do • System Software : Does things we need doneLow level details

  3. Operating System • Operating System : Software that manages the operation of a computer • Not all computational systems have an OS • Early computers • Embedded systems

  4. Varieties of OSes • Batch • Submit list of jobs

  5. Varieties of OSes • Interactive • Single user single task • Single user / multitask • Multiuser

  6. Operating Systems • PC Operating Systems • Windows • *nix • Linux • MacOS X

  7. Operating Systems • Phone OSes • iOS • Android • Windows • Palm

  8. Varieties of OSes • Real Time / Dedicated

  9. What do they do? • Manage hardwareresources • Provide an abstraction • Allocate scare resources

  10. Abstraction • API : Application Programming Interface • Set of functions software can do • OS API Features • Functions (blocks) to • Read files • Use a network • Draw windows • Get mouse position

  11. Resource Scarcity • Resources scarce in • Time • Processor • IO / Disk • Space • Memory • Disk

  12. Resources - Processes • OS manages what process(es) are running • Interrupts cause operating system to grab control • Timer • Hardware signalsthat data is ready http://faculty.chemeketa.edu/ascholer/cs160/VTCS0/OS/Lessons/Processes/index.html

  13. Resources - Processes • Processes Challenge: • Lots of incoming jobs, how do you determine how to handle them? • Shortest job first? • Round robin?

  14. Resources - Processes • Processes Challenge: • Lots of incoming jobs, how do you determine how to handle them?

  15. Resources - Memory • Memory : Where running programs & data are stored

  16. Virtual Address Space • Application memory scattered all over • Virtual address space makes it look clean to application

  17. Resources - Memory • Memory is a hierarchy

  18. Resources - Memory • Constant shuffle between levels • CPU registers have some information • Cache has a larger set • Main memory has a bigger set • The disk has everything else

  19. Resource Abstraction • Hard Drive workings: http://www.youtube.com/watch?v=kdmLvl1n82U&feature=related • What a programmer wants • Open the file called "essay.doc"

  20. Resources - IO • Keyboard, Monitor, Network, Printer… • Mange flow of information • Maintain buffers • Handle hardware interrupts • Provide application access

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