Os Basics

OS Basics What is an direct System? Basics of Operating Systems bound 4, 2001 Adapted from Operating Systems Lecture Notes, Copyright 1997 Martin C. Rinard. ! many an(prenominal) definitions - remedy to describe what OSs do ! Provide an bring upion everyplace computer ironware ! Standard interfaces to a variety of hardware ! Provide a user interface (not required, but approximately do) ! Provide an application program Programming Interface ! screw resource sharing ! central mainframe, dish antenna drives, network, sound, video, keyboard, mouse, ... ! pick out intentions depend on OS (e.g., Linux vs. Windows vs. PalmOS) 2 OS Basics, cont. OS Basics, cont. communication practical(prenominal)(prenominal) railroad cars ! When hardware was expensive, objective was to keep processor fully utilized (batch processing) ! As hardware became less expensive, entail shifted towards human usability ! E.g., cover large servers among many simultaneous users ! substantial off: At least 1 physical central processor per user ! Run many user programs on a CPU ! Complexity managed by creating an abstraction: communicating virtual machines Communicating virtual machines, cont. ! Simple Model: Write programs as if it was the still one and only(a) running on the machine ! realistic machine implemented over a lot of interfaces that abstract a computers hardware ! Many virtual machines run simultaneously on the same physical machine !

Virtual machines share every last(predicate) the resources of the physical machine ! Operating system substance runs and manages the virtual machines 3 4 1 OS Basics, cont. OS Basics, con t. Concurrency: CPU ! Process (a virtual! machine): a set of operating instructions + a state ! The virtual machine executes from from each one one instruction against its state ! A state includes all the entropy used by the execution stream ! States implemented by a variety of hardware registers, stack, RAM, hard drive ! objective lens: Fair sharing, protection - processes cannot directly change each others states (enforced by OS) ! Communication: done through shared computer storage or other resources 5 Processes ! Context...If you want to get a full essay, order of battle it on our website: OrderEssay.net

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