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Multiprocessor Systems. Figure 1-2a. Figure 1-2b. CS433. 6. Multicomputer System. Figure 1-2c ... Conjuring framework administrations. Library call (nonprivileged) Kernel call ...
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1. Presentation 1.1 The Role of Operating Systems - Bridge the "Semantic Gap" amongst Hardware and Application - Three Views of Operating Systems 1.2 Organization of Operating Systems - Structural Organization - The Hardware Interface - The Programming Interface - The User Interface - Runtime Organization 1.3 Operating System Evolution & Concepts

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Single CPU System Figure 1-1

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Bridging the Semantic Gap Hardware abilities are low level Arithmetic and legitimate administrators Comparison of no good strings Branching, perusing, and composing bytes User needs to think as far as issue to be illuminated High-level information structures and relating operations Simple, uniform interfaces to subsystems, Treat projects and information records as single substances Use programming to extension this hole Language processors (e.g., constructing agents, compilers, translators). Editors and content processors, linkers and loaders. Application projects, utility and administration programs. Working Systems

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The part of OSs Bridge Hardware/Application Gap Machine guideline versus abnormal state operation compiler spans hole Linear memory versus information structures compiler spans hole Limited CPU & memory versus more required OS spans hole Secondary memory gadgets versus documents OS spans hole I/O gadgets versus abnormal state I/O summons OS spans hole

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Multiprocessor Systems Figure 1-2a Figure 1-2b

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Multicomputer System Figure 1-2c

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PC Hardware Organization Figure 1-7

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Three perspectives of OSs OS is a broadened machine Principle of deliberation shrouds many-sided quality OS gives abnormal state operations utilizing lower level operations OS is a virtual machine Principle of virtualization backings sharing OS gives virtual CPU, memory, gadgets OS is an asset administrator Balance general execution with individual needs (reaction time, due dates)

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Structural Organization of OSs Monolithic versus Layered Figure 1-8

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Organization of OSs Hardware Interface Applications and OS ordered into machine directions Interrupts and Traps permit OS to seize control process administration (time-sharing) gadget administration (I/O fulfillment)

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Principles of Interupts and Traps Figure 1-9

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Organization of OSs Hardware interface (proceeded with) Modes of CPU execution Privileged/Nonprivileged SVC (chief call) causes trap Control moved to OS in favored mode OS exits special mode when coming back to client

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Organization of OSs Programming Interface Invoking framework administrations Library call (nonprivileged) Kernel call (advantaged) Figure 1-8

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Invoking System Services Figure 1-10

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Organization of OSs User interface (cf. Fig. 1-8) Text-based shell (e.g. Unix) order mediator shell scripts Graphics-based GUI (e.g. Macintosh, MS Windows) W indows I cons M enus P ointer

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Organization of OSs Runtime association Service is a Subroutine Service is an Autonomous Process ("customer server") Figure 1-12

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OS Evolution and Concepts Early frameworks Bootstrapping Batch OSs I/O processors Interrupts Relocatable code Multiprogramming

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Multiprogramming Basic issue: Some projects are register bound, some I/O-bound Even "adjusted" projects are adjust just over the long run No one project can make full utilization of the framework Solution: Multiprogramming Have more than one dynamic (running) program in memory at any one time Multiprogramming requires Bridging the semantic crevice Sharing assets among various projects Hiding from every project the truth of this sharing

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OS Evolution and Concepts Multiprogramming Systems Overlap CPU and I/O Protection Synchronization and Communication Dynamic Memory Management (swapping and paging) Interactive OSs Guaranteed reaction Time-sharing (quantum)

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Batch Processing Uses multiprogramming Job (record of OS summons) arranged disconnected Batch of employments given to OS at one time OS forms occupations in a steady progression No human-PC connection OS upgrades asset use Batch handling (as a choice) still utilized today

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Shell Command Line Interpreter Interactive User Application & System Software Shell Program OS System Call Interface OS

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The Shell Strategy % grep first f3 fork a procedure read console Shell Process to execute order f3 read document

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Initializing a UNIX Machine Serial Port A login Serial Port B login Serial Port C login Serial Port Z login getty/and so on/passwd

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A Shell Script Batch File gcc - g - c menu.c gcc - g - o driver driver.c menu.o driver < test_data > test_out lpr –Ppr0 test_out tar cvf driver_test.tar menu.c driver.c test_data test_out uuencode driver_test.tar >driver_test.encode

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UNIX Files UNIX and NT attempt to make each asset (with the exception of CPU and RAM) resemble a document Then can utilize a typical interface: open Specifies document name to be utilized close Release document descriptor read Input a piece of data compose Output a square of data lseek Position record for read/compose ioctl Device-particular operations

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UNIX File Example #include <stdio.h> #include <fcntl.h> int principle() { int inFile, outFile; singe *inFileName = "in_test"; scorch *outFileName = "out_test"; int len; roast c; inFile = open(inFileName, O_RDONLY); outFile = open(outFileName, O_WRONLY);/* Loop through the information record */while ((len = read(inFile, &c, 1)) > 0) write(outFile, &c, 1);/* Close documents and entirely */close(inFile); close(outFile); }

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OS Evolution and Concepts PC and workstation OSs GUI Real-time OSs Deadlines (booking) Distributed OSs Loosely coupled/firmly coupled Consistent course of events (coherent timekeepers, time stamps)

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Examples of Modern OS UNIX variations (e.g. Linux) - have advanced subsequent to 1970 Windows NT/2K - has developed following 1989 VxWorks for constant Research OSes – as yet advancing … Small PC OSes – as yet developing

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Requirements from a Modern OS 1. Small scale bit structure Scheduling Networking Device Drivers Memory Management Scheduling IP Communication Everything else is worked as utilities

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Requirements (cont.) 2. Multi-threading - A procedure comprises of strings -Threads run simultaneously -A string is schedulable and interruptable -User and bit strings 3. Symmetric Multiprocessing -More than one processors - > speed and blame tol. - Incremental development is conceivable

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Requirements (cont.) 4. Circulated Operating System - Running on numerous processors (bunches) -Vision of one OS -Fault Tolerance expanded -Performance, asset use -Still an examination issue – relatively few around -Distributed and Mobile and Real-time ??? that is by all accounts the eventual fate of OS !

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Processor Modes Mode bit: Supervisor or User mode Supervisor mode Can execute all machine guidelines Can reference all memory areas User mode Can just execute a subset of directions Can just reference a subset of memory areas

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Kernels The part of the OS basic to right operation (trusted programming) Executes in administrator mode The trap guideline is utilized to change from client to director mode, entering the OS

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Supervisor and User Memory User Space User Process Supervisor Process Supervisor Space

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send(… , A, … ); get(… , B, … ); send/get(… A, … ); … send(… , B, … ); Procedure Call and Message Passing Operating Systems call(… ); trap return;

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System Call Using the trap Instruction … fork(); … Trap Table Kernel fork() { … trap N_SYS_FORK() … } sys_fork() sys_fork() {/* framework capacity */… return; }

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A Thread Performing a System Call User Space Kernel Space Thread fork(); sys_fork() { }

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File Manager Memory Manager Device Manager Basic Operating System Organization Process, Thread & Resource Manager Processor(s) Main Memory Devices

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The UNIX Architecture Interactive User Libraries Commands Application Programs … OS System Call Interface Trap Table Device Driver Monolithic Kernel Module Process Management Memory Management File Management Device Mgmt Infrastructure Device Driver … Driver Interface Device Driver

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Microkernel Organization Process Libraries Process User Supervisor Server Device Drivers Microkernel Processor(s) Main Memory Devices

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Windows NT Organization Process T Process T Libraries T Process Management Memory Management File Management Device Mgmt Infrastructure Subsystem User Supervisor I/O Subsystem NT Executive NT Kernel Hardware Abstraction Layer Processor(s) Main Memory Devices

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Abstraction E.W.Dijkstra, "The Humble Programmer" (1972): "The motivation behind reflection is not to be obscure, but rather to make another semantic level in which one can be completely exact." "deliberation" is made by recognizing Essential attributes from Unimportant subtle elements Build levels (layers) of deliberations: What is insignificant point of interest at one level is a crucial trademark at a lower one.

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