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    What hardware mechanisms are essential to the operation of the modern operating system? Briefly describe the purpose of each mechanism.
    2. Describe the main benefits of SPOOLing systems.
    3. Describe the boot process

    © BrainMass Inc. brainmass.com December 24, 2021, 7:53 pm ad1c9bdddf
    https://brainmass.com/computer-science/memory-management/operation-system-mechanisms-227010

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    1. What hardware mechanisms are essential to the operation of the modern operating system? Briefly describe the purpose of each mechanism.
    Let us discuss about the hardware mechanism which are essential to the modern operating system,

    INTERRUPTS:
    Interrupts provide an efficient way for the operating system to interact and react to its environment. When a hardware device triggers an interrupt the operating system's kernel decides how to deal with this event, generally by running some processing code. The processing of hardware interrupts is a task that is usually delegated to software called device drivers, which may be either part of the operating system's kernel, part of another program, or both.
    A program may also trigger an interrupt to the operating system. If a program wishes to access hardware for example, it may interrupt the operating system's kernel, which causes control to be passed back to the kernel. The kernel will then process the request. If a program wishes additional resources such as memory, it will trigger an interrupt to get the kernel's attention.
    MEMORY MANAGEMENT AND MEMORY MANAGEMENT:
    A multiprogramming operating system kernel must be responsible for managing all system memory which is currently in use by programs. This ensures that a program does not interfere with memory already used by another program. Since programs time share, each program must have independent access to memory.
    Memory protection enables the kernel to limit a process access to the computer's memory. All methods require some level of hardware support which doesn't exist in all computers. Various methods of memory protection include memory segmentation and paging.
    VIRTUAL MEMORY:
    If a program tries to access memory that is not in its current range of accessible memory, but nevertheless has been allocated to it, the kernel will be interrupted in the same way as it would if the program were to exceed its allocated memory. Under UNIX this kind of interrupt is referred to as a page fault. When the kernel detects a page fault it will generally adjust the virtual memory range of the program which triggered it, granting it access to the memory requested. This gives the kernel discretionary power over where a particular application's memory is stored
    In modern operating systems, application memory which is accessed less frequently can be temporarily stored on disk or other media to make that space available for use by other programs. This is called swapping, as an area of memory can be used by multiple programs
    2. Describe the main benefits of SPOOLing systems.
    SPOOLING:
    Spooling is a method of handling low-speed I/O devices commonly implemented in operating systems to increase throughput. It stands for simultaneous peripheral operations on line. Spooling is a higher level buffering to even out demand for unshareable resources: e.g. printers.
     During periods of high demand several processes are held up waiting for use of scarce resources and at the same time in other periods these same devices may be lying unused.
     Spool all I/O to these devices, i.e. instead of I/O directly to device, do it on intermediate medium, disc.
     Spooler then moves data between disc and device.

    Advantages of spooling
    1. Easier to produce several copies without rerunning jobs.
    2. Reduces possibility of deadlock caused by injudicious peripheral allocation.
    3. Evens out pressure on heavily used devices.

    3. Describe the boot process
    Booting (booting up) is a bootstrapping process that starts operating systems when the user turns on a computer system. The boot loader typically loads the main operating system for the computer. A boot sequence is the initial set of operations that the computer performs when it is switched on
    In simple terms we can say that, when we boot a football, we kick it really far away. Likewise when we boot a computer, we are simply turning it on. The term "boot" comes from the word "bootstraps," which people at one time used to get their boots on. Likewise, booting a computer gets it up and running.
    BOOT PROCESS:
    The typical computer system boots over again and again with no problems, starting the computer's operating system (OS) and identifying its hardware and software components that all work together to provide the user with the complete computing experience. In order for a computer to successfully boot, its BIOS, operating system and hardware components all must be work properly. If anyone in these three process pails it will result in failed boot sequence.
    When the computer is first turned on, the CPU initializes itself, which is triggered by a series of clock ticks generated by the system clock. Part of the CPU's initialization is to look to the system's ROM BIOS for its first instruction in the startup program. The ROM BIOS stores the first instruction, which is the instruction to run the power-on self test (POST), in a predetermined memory address. POST begins by checking the BIOS chip and then tests CMOS RAM. If the POST does not detect a battery failure, it then continues to initialize the CPU, checking the inventoried hardware devices (such as the video card), secondary storage devices, such as hard drives and floppy drives, ports and other hardware devices, such as the keyboard and mouse, to ensure they are functioning properly.
    Once the POST has determined that all components are functioning properly and the CPU has successfully initialized the BIOS looks for an OS to load. The BIOS typically looks to the CMOS chip to tell it where to find the OS, and in most PCs, the OS loads from the C drive on the hard drive even though the BIOS has the capability to load the OS from a floppy disk, CD or ZIP drive. The order of drives that the CMOS looks to in order to locate the OS is called the boot sequence, which can be changed by altering the CMOS setup. Looking to the appropriate boot drive, the BIOS will first encounter the boot record, which tells it where to find the beginning of the OS and the subsequent program file that will initialize the OS.
    Once the OS initializes, the BIOS copies its files into memory and the OS basically takes over control of the boot process. Now in control, the OS performs another inventory of the system's memory and memory availability and loads the device drivers that it needs to control the peripheral devices, such as a keyboard, printer, scanner, mouse and optical drive. This is the final stage in the boot process, after which the user can access the system's applications to perform tasks.

    This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

    © BrainMass Inc. brainmass.com December 24, 2021, 7:53 pm ad1c9bdddf>
    https://brainmass.com/computer-science/memory-management/operation-system-mechanisms-227010

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