os2-1_str.ppt - Operating Systems Functional View of Operating System A Frank P Weisberg Contents \u2022 \u2022 \u2022 \u2022 \u2022 \u2022 2 Computer System Organization

os2-1_str.ppt - Operating Systems Functional View of...

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A. Frank - P. Weisberg Operating Systems Functional View of Operating System
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2 A. Frank - P. Weisberg Contents Computer System Organization Main Memory Management Memory Protection I/O Protection CPU Protection Types of Interrupts: 1. Traps 2. External interrupts 3. System calls
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3 A. Frank - P. Weisberg Computer System Organization One or more CPUs, device controllers connect through .common bus providing access to shared memory Concurrent execution of CPUs and devices competing for .memory cycles
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4 A. Frank - P. Weisberg Storage Structure Main memory – only large storage media that the CPU can access directly. Secondary storage – extension of main memory that provides large nonvolatile storage capacity. Hard disks – rigid metal or glass platters covered with magnetic recording material: Disk surface is logically divided into tracks, which are subdivided into sectors. The disk controller determines the logical interaction between the device and the computer.
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5 A. Frank - P. Weisberg Storage Hierarchy
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6 A. Frank - P. Weisberg Performance of Various Levels of Storage
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7 A. Frank - P. Weisberg Caching Important principle, performed at many levels in a computer (in hardware, operating system, software). Information in use is copied from slower to faster storage temporarily. Faster storage (cache) checked first to determine if information is there: If it is, information used directly from the cache (fast). If not, data copied to cache and used there. Cache smaller than storage being cached: Cache management is an important design problem. Cache size and replacement policy matter.
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8 A. Frank - P. Weisberg Main Memory Management Initial memory management techniques: 1. Minimal management – one program that manages memory for itself. No memory protection problems here. 2. Memory split – Resident Monitor and User Job/Program split the memory between them. 3. Memory Division – The operating system and a few user jobs divide the available memory between them.
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9 A. Frank - P. Weisberg MS-DOS Memory Split
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10 A. Frank - P. Weisberg Memory Management Dynamics Sharing system resources requires the operating system to ensure that an incorrect program cannot cause other programs to execute incorrectly. Resident Monitor is a “Trusted Program” but how to protect it from damage by the user program? Solution: Fence Register (a dedicated register) and addressing access logic.
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11 A. Frank - P. Weisberg Memory Split Resident Monitor User Program Fence Register 0K 64K 16K
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12 A. Frank - P. Weisberg Fence Register The Fence Register is loaded with the base of the user program (which is also the limit of the Resident Monitor).
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  • Summer '18
  • Aileen
  • Virtual memory, Central processing unit, Interrupt, Interrupt handler

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