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real time operating system

Discussion in 'Electronics Homework Help' started by vead, Apr 30, 2014.

  1. vead

    vead

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    Nov 27, 2011
    operating system that provide interface between hardware and application software
    operating system - windows Linux
    Example - we use operating system for computer
    - we use operating system for mobile
    1) does ATM machine use operating system ?
    please give other example where we used operating system ?
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Vead,
    this looks like you've been given this as an assignment to bring up examples for the use of operating systems. I'll move that post to the homework section.

    • Do you know, what an operating system does?
    • What have you researched so far to find more examples for the use of operating systems?
    By the way: neither windows nor Linux are real time operating systems.


    Regards,
    Harald
     
    KrisBlueNZ likes this.
  3. vead

    vead

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    I searched on google for operating system i found mostly two example computer ,mobile I just want to ask example
     
  4. davenn

    davenn Moderator

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    Sep 5, 2009
    what is your definition of a "real time" operating system ?


    D
     
  5. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    You know Google, don't you?
     
  6. davenn

    davenn Moderator

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    Sep 5, 2009

    dunno who you aimed that at Harald ?, hopefully not me as wasn't needed
    I wanted Vead to define what he was wanting

    Dave
     
  7. vead

    vead

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    Nov 27, 2011
    operating system
    operating system that provide interface between hardware program and application software
    hardware program- usb driver, LAN driver, video driver
    application software - VLC , MS word photoshope
    operating system - windows Linux
    Example - we use operating system for computer

    example - computer, mobile , ATM machine , Missile Satellites

    Q)every operating system should have display ?

    If answer is no then how can we use application software without display , so think the device that used operating system should have display
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Does a missile satellite have a display? Who is up there looking at it?

    Think more generally, what does some of the hardware (like USB ports, keyboards, mice, displays, printers, wifi cards, disk drives) have in common (what do they do with data?)
     
  9. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Heaven s no, Dave. By no means, please don't feel offended. This message was meant as a reply to vead's post #3
     
  10. vead

    vead

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    Nov 27, 2011
    ok I understood , without display we can use operating system
     
  11. vead

    vead

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    multitasking - the ability to execute more then one task at same time

    Q1) Is it correct definition for multitasking?

    task has three state
    running-executing on cpu
    ready-read to be execute
    waiting - waiting for execution

    If we have two task running at same time, both task can not be executed at same time so one of them will be delayed , one task will be wait another task will be execute

    Q2) one task will be wait another task will be execute but what decide that which one will be execute first and which one will be wait?

    I am confused about what is multitasking and scheduling
     
  12. pyromaniac4382

    pyromaniac4382

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    Scheduling solves the problem of multitasking. Think of this in real life. Say you have three tasks to complete. There are many ways to go about completing the tasks. You could do one after the other based off of some sort of priority you place on each task (maybe one is due sooner than the others), or you could alternate between the tasks doing a bit of each until all three tasks are complete. In operating systems there is a similar decision happening to multitask, and this decision making is decided by the scheduling method implemented. In an operating system however there are a lot more tasks, and the problem of scheduling the tasks to completion becomes much harder.
     
    Last edited: May 5, 2014
    vead likes this.
  13. vead

    vead

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    check out this definition
    kernel -kernel is part of operating system that provide basic service to application software running on processor

    multitasking - multitasking is process where one or more task run at same time on same single processor

    scheduling- scheduling is process by which operating system decide which one task will be perform first on processor

    please correct me If I am wrong
     
  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    No you don't understand at all.

    A display is just a means of getting data in or out (in the case of a display it's out) of the computer.
     
  15. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    That's not perfect but it may be close enough.
     
  16. vead

    vead

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    ok tell me where did I make mistake, what is perfect definition according yourself
     
  17. pyromaniac4382

    pyromaniac4382

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    I think what steve may be alluding to is that there can be a bit of a grey area when you start to include multiple processors with multiple cores, and so on. Depending on how the operating system handles tasks across these multiple processors or cores, and how the workload is split your definitions change.

    These ideas aren't really set in stone. The ideas are evolving with advances in software. Software lags behind hardware. Less than a decade ago I think I would be telling you a very straight forward definition of multitasking, but today it is a bit different. Universally however you can explain this "good enough" in a few sentences, but you could really write an entire manual out on this subject.

    I think to clear things up we can use a bit more analogies.

    A kernel is like a translator. If you went to another country lets say France, and did not know French, a translator will take all of the complexity out of trying to understand another language, and looking up word after word. A kernel does the same type of job, it knows how to talk to low-level devices based off of high level application instructions. The kernel provides this as a "basic service", but to me its job doesn't seem so basic. the kernel does other things as well, but this is a good general blanket statement.

    Your statement on multitasking can be extended outside of just a single processor.

    Scheduling isn't just about who is first. Take for example two processes needing to be completed. One could start first, switch to the second, finish the second, switch back to the first, then finish the first. Take a look at some scheduling methods such as "round-robin" to get a better idea of different scheduling strategies implemented in operating systems.

    If you have access to Wikipedia take a look at some of the pages on scheduling, multitasking, the kernel, and operating systems. This may give you a better general overview.
     
    vead and Allen Bong like this.
  18. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    It comes down to nuances and definitions. And what follows is not perfect.

    The kernel typically provides services to the operating system. Whilst applications can interact with the kernel at some level, they rarely do so directly. If they do, then they are often classified as part of the OS. For example, a device driver is not part of the kernel, interacts with it, and is part of the OS. Similarly an application level program that extracts process information from the kernel to display the state of running processes will typically be part of the OS. None of this means an application program can't access this stuff, but it's possibly going to go through an interface layer (in linux glibc is often that interface layer and it is part of the OS, but not part of the kernel). Some operating systems have multiple privilege levels (sometimes called "rings") that isolate parts of the OS from programs or processes that are not allowed to call them. The kernel may run in "ring 0" where it can do anything. A userspace program can't directly manipulate physical memory mapping (for example), and may not even be allowed to call the part of the kernel which does so. However the userspace program may be allowed to initiate a new process, and that OS code (perhaps in ring 1 will be allowed to call the kernel routine in ring 0 which does the physical memory mapping required to set up a process.

    Also, the device may have several processors and the kernel will typically manage resources on all of those processors. Via the OS, this management provides services to software (not necessarily application software) running on all available processors (assume processor = core for simplicity, but the same rule applies to multiple physical processors as well as single processors with multiple cores)

    multitasking is where multiple tasks are executed during the same period of time. However they may not be actively running (i.e. the processor is executing their instructions) simultaneously. To do that you require multiple cores. More succinctly, multitasking is where multiple processes are simultaneously loaded and scheduled to run, and where the operating system and/or application level programs provide some mechanism to switch between them so that it appears that they are running simultaneously.

    Not first, but next.

    It may (and frequently does) involve determining for how long a process will run, which processor it will run on, pre-empting the process (arguable), manipulating process priorities based on historical use of resources and other information, etc.[/quote]
     
  19. vead

    vead

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    Nov 27, 2011
    type of scheduling in real time operating system

    First come First serve - task are executed on first come first serve basis
    shortest Job first - task execute first which take minimum time to execute
    priority based - each task has priority , higher priority task will be executed first

    which type of scheduling, rtos support
     
    Last edited: May 8, 2014
  20. vead

    vead

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    Nov 27, 2011
    real time os designer design scheduling algorithms.
    Different OS kernels may use different scheduling algorithms

    First come First serve -
    shortest Job first -
    priority based -

    Q) does one kernel support only one scheduling algorithms ?

    I have exam question (RTOS)
    define following
    1. I/O subsystem
    2.memory management
    file system organizations

    I dont want to someone explain in detail for me just give me hint, what does it mean ?
     
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