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Study material for professional knowledge: Operating System Concepts(Basics)

<div dir="ltr" style="text-align: left;" trbidi="on"><h1 style="text-align: center;">Study material for professional knowledge:  Operating System Concepts(Basics)</h1><div style="text-align: center;"> <div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwaa5gmkmIcwpKztTPVptrL9pmZMskjKfu6kzcX8sI3nqv_c2h941YzXt7nXQg59DN6CRft39MFNcUTFqYZQoBjhyphenhyphen6zueduy45bEeB8cpU2pxrqxMwUoF_yoIXhnMY2d-uBGYayZrGL58/s1600/operating+system+study+material.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwaa5gmkmIcwpKztTPVptrL9pmZMskjKfu6kzcX8sI3nqv_c2h941YzXt7nXQg59DN6CRft39MFNcUTFqYZQoBjhyphenhyphen6zueduy45bEeB8cpU2pxrqxMwUoF_yoIXhnMY2d-uBGYayZrGL58/s1600/operating+system+study+material.png" /></a></div> <div class="separator" style="clear: both; text-align: center;"></div> </div><div style="text-align: center;"> </div><div style="text-align: left;">What is an Operating System? <div style="text-align: left;"></div><ul style="text-align: left;"><li>A program that acts as an intermediary between a user of a computer and the computer hardware.</li><li>Operating system goals:</li><li>Execute user programs and make solving user problems easier.</li><li>Make the computer system convenient to use.</li><li>Use the computer hardware in an efficient manner.</li><li>Computer systems typically contain: Hardware and Software Hardware - electronic, mechanical, optical devices Software – programs</li><li>Without support software, the computer is of little use.</li><li>An interface between Hardware and User Programs</li><li>An abstraction of the hardware for all the (user) processes</li><li>Hide the complexity of the underlying hardware and give the user a better view of the computer</li></ul> <div style="text-align: justify;">Computer System Components</div> <ul style="text-align: left;"><li>Hardware – provides basic computing resources (CPU, memory, I/O devices).</li><li>Operating system – controls and coordinates the use of the hardware among the various application                           programs for the various users.</li><li>Applications programs – define the ways in which the system resources are used to solve the computing problems of the users (compilers, database systems, video games, business programs).</li><li>Users (people, machines, other computers). </li></ul> Abstract View of System Components           <div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvn-7OkgUdFwsb3OFUVr3vDtcwCOrsvj4TgoRz1zxrT6M3yBUYATNAjrO5AQVb3ry-k3akTc1mi_euv9NpPy43uobv34X_DWDX1wZhkV2F67b3WZToXbal_WQns3ZDOUBHG5ipmw5BLKM/s1600/OS+system+components.jpg.png" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="526" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvn-7OkgUdFwsb3OFUVr3vDtcwCOrsvj4TgoRz1zxrT6M3yBUYATNAjrO5AQVb3ry-k3akTc1mi_euv9NpPy43uobv34X_DWDX1wZhkV2F67b3WZToXbal_WQns3ZDOUBHG5ipmw5BLKM/s1600/OS+system+components.jpg.png" width="640" /></a></div> Operating System Definitions <ul style="text-align: left;"><li>Resource allocator – manages and allocates resources.</li><li>Control program – controls the execution of user programs and operations of I/O devices .</li><li>Kernel – the one program running at all times (all else being application programs).</li></ul> The Goals of an OS <div style="text-align: left;"></div><ul style="text-align: left;"><li>     Let users run programs:</li><li>     Correctness- Memory boundaries, priorities, steady state</li><li>     Convenience-User should not handle the tiny details (encapsulate/abstract), provide synchronization primitives, system calls, file system, tools</li><li>     Efficiency-Resource Utilization, resource Sharing, Multitasking</li><li>     Fairness (in resource allocation)</li><li>     Among: users, tasks, resources</li><li>     The tradeoff between efficiency and fairness</li></ul> An OS is a Resource Allocator <ul style="text-align: left;"><li>Multiple users  get all computing resources “simultaneously”:</li><li>Cpu time</li><li> Memory (ram, swap, working set, virtual,..)</li><li> File system (storage space)</li><li> I/O devices (display, printers, mouse,..)</li><li> The OS should give every user the illusion that she is getting all resources to herself (not sharing!) </li></ul> Virtual  Continuity <ul style="text-align: left;"><li>A process can get “switched in” or “switched out”.</li><li>OS should give the illusion for the process as if it exists in the CPU continuously => Context Switching</li></ul> Context switching <ul style="text-align: left;"><li>      When an event occurs, the operating system saves the state of  the active process and restores the state of the new process. </li><li>     This mechanism is called a Context Switch.</li><li>     What must get saved? Everything that the next process could or will damage. For example:</li></ul>               Program counter (PC)             Program status word (PSW)               CPU registers (general purpose, floating-point)             File access pointer(s)             Memory Scheduling and Context switch         Give up the CPU == switch out the current process + switch in another process Preemptive Scheduling <ul style="text-align: left;"><li>There are OS’s where a process is forced to give up the cpu (e.g. when stayed for too long).</li><li>Such systems are implementing a “preemptive scheduling” policy.</li><li>Examples include Windows NT, Unix, - BUT NOT - Windows prior to Win95 ! or Macintosh!</li></ul> Using Priorities <ul style="text-align: left;"><li>Most OS’s provide the priority mechanism</li><li>Priorities are associated with processes</li><li>Priority are used to help the OS to reach fairness</li></ul> Process     A process is a program in execution.     The components of a process are:             the program to be executed,             the data on which the program will execute,             the resources required by the program—such as memory and file(s)—and  the status of the execution. OS Features Needed for Multiprogramming <ul style="text-align: left;"><li>     I/O routine supplied by the system.</li><li>     Memory management – the system must allocate the memory to several jobs.</li><li>    CPU scheduling – the system must choose among several jobs ready to run.</li><li>    Allocation of devices.</li></ul> Time-Sharing Systems–Interactive Computing     <ul style="text-align: left;"><li>The CPU is multiplexed among several jobs that are kept in memory and on disk (the CPU is allocated to a job only if the job is in memory).</li><li>A job swapped in and out of memory to the disk.</li><li>On-line communication between the user and the system is provided; when the operating system finishes the execution of one command, it seeks the next “control statement” from the user’s keyboard.</li><li>On-line system must be available for users to access data and code.</li></ul> </div></div>

Study material for professional knowledge: Operating System Concepts(Basics)

Study material for professional knowledge: Operating System Concepts(Basics)What is an Operating System?A program that acts as an intermediary between a user of a computer and the computer hardware.Op…

01 Mar 2014

Study material: Most Important Questions for Computer Awareness for all exams

<div dir="ltr" style="text-align: left;" trbidi="on"><div class="MsoNormal"><div class="MsoNormal" style="margin-left: 0.25in;"></div><div>Study material: Important  Questions  for Computer Awareness for all exams</div><div> </div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-3OjyMnW3WobAOPvCppmVMsrVG6xCvwoKXQWZYeio2_m46SAw_J2U5ek21gHBkE09kQ6sAc-oL-jKvMlw5V32wGbRJZGbtnuB3Kq7AKbclNiOVIsXjb8rawNCaBX_jxLMbTaacVE_Smo/s1600/computer+awareness+important+questions.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-3OjyMnW3WobAOPvCppmVMsrVG6xCvwoKXQWZYeio2_m46SAw_J2U5ek21gHBkE09kQ6sAc-oL-jKvMlw5V32wGbRJZGbtnuB3Kq7AKbclNiOVIsXjb8rawNCaBX_jxLMbTaacVE_Smo/s1600/computer+awareness+important+questions.jpg" /></a></div> <div class="MsoNormal" style="margin-left: 0.25in;"></div><ul style="text-align: left;"><li>Job control language is used for Mainframe computer.</li><li>A stub link is a network that is connected to only one router.</li><li>You will require video card to see graphics on your computer.</li><li>A computer peripheral that prints one line of output at a time is known as line printer.</li><li>In time sharing mode each user uses a local input/output device.</li><li>NOT gate is used to invert the input signal.</li><li>ALGOL is an algorithmic language.</li><li>IEEE 802.16 standard represents WiMAX.</li><li>Tutorial is written for those who do not very much about computer.</li><li>Point-of-sale software is an example of vertical market software.</li><li>Computer port does not exist in a computer.</li><li>Terminal symbol in a flowchart indicates the beginning and end in a program’s logic flow.</li><li>Part of a computer instruction word that designates the function performed by a specific instruction is – OPCODE.</li><li>The most common method for gaining access to the Internet is through a – provider or host computer.</li><li>Blue-ray disk is an example of optical disk.</li><li>Bridge can check the physical address of source and destination contained in the frame.</li><li>Downlink is a term related to receiving data from a satellite.</li><li>Operation code is also known as order code.</li><li>PDF is an acronym for PORTABLE DOCUMENT FORMAT.</li><li>Windows.exe file starts MS WORD.</li><li>SUM(B2:B9) is an example of a formula in MS-Excel.</li><li>MS-DOS is an operating system that dos nor implement multitasking truly.</li><li>Tangible parts of a computer are called Hardware.</li><li>AMPS is the first generation cellular technology.</li><li> A container used to display a set of tabbed pages of elements is known as tab box.</li><li>High level language is a machine independent language.</li><li>Shimmer Sparkle Text, Blinking Background, etc are known as text effects.</li><li>10 Base F type of Ethernet uses star topology.</li><li>An error that causes a program to abort and many there of return the user to the OS is called a fatal error.</li><li>Personal Area Network is another name of Bluetooth.</li><li>11 is the default font size of a cell content in MS-EXCEL.</li><li>Cut and paste is the best method to move some text from one page to different page.</li><li>One definition of AI i.e. Artificial Intelligence focuses on problems solving methods that processes symbols.</li><li>The “big picture” diagram of a system is a system flowchart.</li><li>Control unit is the part of CPU containing clock, program counter, instruction register.</li><li>In a compiler, the syntax analysis is done by parser.</li><li>Presentation layer is responsible for the protocol conversion.</li><li>Testing is process of finding error code.</li><li>ULSI hardware technology was used by fifth generation computers.</li><li>For each instruction in a program memory the CPU goes through a ‘fetch code – execute’ sequence. </li></ul> <div class="MsoListParagraphCxSpFirst" style="mso-list: l0 level1 lfo1; text-indent: -0.25in;"></div></div></div>

Study material: Most Important Questions for Computer Awareness for all exams

Study material: Important Questions for Computer Awareness for all examsJob control language is used for Mainframe computer.A stub link is a network that is connected to only one router.You will req…

01 Mar 2014

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Study material for professional knowledge: Operating System Concepts(Basics)

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