1_os_intro

1_os_intro - OS and Architecture Overview Chapter 1 1 What is an operating system application(user operating system A software layer between

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1 OS and Architecture Overview C ha pte r 1
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2 What is an operating system? A software layer between hardware and application programs/users, provides a virtual machine interface easy to use (hides complexity) safe (prevents and handles errors) Acts as resource manager allows programs/users to share hardware resources in a protected way: fair and efficient hardware operating system application (user)
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3 What is an Operating System? A program that acts as an intermediary between a user of a computer and the computer hardware Operating system goals: Execute user programs and make solving user problems easier. Make the computer system convenient to use Use the computer hardware in an efficient manner Views Abstract or virtual machine Manager/policeman
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4 Dual nature of OS King:  Controls processes Allocates resources Slave:  Performs all menial tasks I/O, memory management, locking
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5 How does an OS work? Receives requests from the application: system calls Satisfies the requests: may issue commands to hardware Handles hardware interrupts: may upcall the application OS complexity: synchronous calls + asynchronous hardware OS application (user) system calls upcalls commands interrupts hardware independent hardware dependent
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6 Architecture Refresher
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7 Basic computer structure CPU Memory memory bus I/O bus disk Net interface
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8 What does OS do?
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9 Topics (Revisited) Processes and threads CPU scheduling Synchronization Memory management Virtual memory I/O and file system Distributed systems Real World Examples – look inside Google
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10 Storage Device Hierarchy register cache main memory word transfer block transfer disks page transfer decreasing cost per bit decreasing frequency of access increasing capacity increasing access time increasing size of transfer unit
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This note was uploaded on 10/13/2008 for the course CSC 246 taught by Professor Gu during the Spring '08 term at N.C. State.

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1_os_intro - OS and Architecture Overview Chapter 1 1 What is an operating system application(user operating system A software layer between

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