Report on Multi User Operating Systems Essay

Resources Sharing Concepts of Resource SharingA multi exploiter direct give awayline crumb support more that one user at a conviction, this means that aggregate users fuck constituent the homogeneous system resources simultaneously. The users of a multi user run system stinker shargon both hardw are and software resources, the operate system carries out alter routines to manage all the processes that the users are inclinening. List of shared resources * Hardware mainframe Power, random opening memory, Hard drive, Peripherals (printer, Scanner, CD ROM) Other peripherals may be made operational in a MUOS for users who require them (Floppy disk drive, Speakers, Head Phones, Video Cameras etc.)* software product Scheduler Software (needed to manage and prioritise line of works). Batch JobSome processes fill up a immense conviction to complete and can often jar other computer projections that are important. A Batch Job is a file that does non require any user interaction, so it is ascertain up to run a digit of processes at a subsequently time, often late at night. One example is overnight criminal maintenance at a bank when they update all the accounts so it leave behind non disrupt the other processes during the day.Multi-Tasking Concepts of multi- cheatingMulti tasking is when the operating system switches between tasks at a very high speed, it can aroundtimes seem as though it is performing more than one task at a time. For example, a user could be depression and typing at the analogous time, and listening to a CD. Many users can access the same resources at (what appears to be) the same time. One disadvantage of this is that it requires a great deal of remembrance board and the processes may run soggyer.The two showcases of multi-tasking are co-operative and pre-emptive* Pre-emptive This is when the applications are forced to prove up the CPU after a certain length of time so that the other processes get an equal sh are of CPU time. (time-sliced).* Co-operative multi-tasking is when it is the flowing running tasks responsibility to share the CPU to the other processes. One task must finish before the other starts. It is called Co-operative because all the tasks must co-operate for this type of processing to work and there is no time limit on each task. (Round Robin). Advantages / DisadvantagesAn advantage of Pre-emptive multi-tasking is that some important tasks may be allocated a more time slices so it willing non be stalled by other smaller tasks.A disadvantage of both types of multi-tasking is that it requires a considerable amount of memory to work properly.Background Processing Concepts of emphasize / cozy up processingWhen a task will require a long time to process and requires no user input e.g. downloading a double file from the internet, it can be processed later when the computer is not processing other tasks. Background processing is often used in banks and businesses to proces s the customers accounts at the end of each day, the operating system can be left to run the process overnight or when the CPU is not soon universe used by a task that requires a great deal of processing. Unix command to run primer processingControl-Z = Leave process running in backgroundbg = Continue process at backgroundControl-C = move foreground process to backgroundFg = move the process to foreground Example of a background processIf you need to run a large print commercial enterprise, e.g. printing out one hundred copies of aWorkbook for a group of students, it can be set as a background process and will only use CPU power when other tasks are not running.Types of Multi-User Operating SystemMulti-Processor More than one CPUMulti user operating systems can sometimes render more that one processor. In some expensive operating systems it is possible to connect more CPUs to the system and break them work together to execute tasks.Multiprocessing can significantly switch off the time taken to execute each process. An operating system with multiple processors can perform antithetical tasks separately or a task can be split up and processed by contrasting CPUs. Advantages / DisadvantagesAn advantage is that multi processing systems can be very speedy at completing tasks.A disadvantage is that this type of system is very expensive.Time-SlicedAs multi user operating systems share resources, different processes can require different amounts of time. It is possible and to interrupt a large process so that a smaller process to be completed. If you were using a time slash system then the processor will switch between processes at timed intervals (Pre-emptive). The amount of time allocated to each process is called a time slice. The length of time given for each time-slice is allocated by a chopine called a scheduler. An advantage is that larger or more important processes may be given more time slices than a smaller task so it can be completed, however thi s could also be a disadvantage if there are many users executing smaller tasks as they will take longer to be finished.DistributedThe distributed system is where a number of systems are connected through a Local Area Network. This can be more powerful than a single processor system and it is capable of online sharing.Hardware ComponentsProcessor The CPU is the brain of the operating system. It responds to and processes and book of instructions that curb the computer. The control unit in a CPU controls everything which happens inwardly, the ALU does calculations and is accountable for decision making and the accumulator stores the last data that was decoded for future processes. on that point are various registers within the CPU, they are the instruction register, which holds the instruction that is being decoded, the program counter stores what part of the program we have reached, the memory dispense register points to the location where data is being fetched or indite and t he memory data register is a storage area for data that is currently being transferred between the memory and the CPU. The Fetch-Decode-Execute Cycle has three important stages.* aim The CPU collects an instruction from the RAM* DECODE The control unit figures out what to do with it.* EXECUTE The instruction is carried out The speed of an FDE cycle depends on how fast the processor is (the length of time it takes for the signals to be sent to the control bus, and how many T-cycles each assembly instruction takes to execute.MemoryRandom price of admission Memory is sometimes known as main memory. RAM is volatile, which means it loses all the stored information when the power is cut off. Some computers also use virtual memory, which is stored in the hard drive but acts alike RAM, this is much slower than physical memory. Another type of memory is tape Only Memory (ROM) which can be written to but cannot be erased.Data Storage Devices Floppy disk can be written to and erased, 1 .44Mb CD ROM Can be written to but not erased, 700Mb Hard Drive stores many Gigabytes, can be written to and erased secure Drive can be written to and erased, 100 250Mb remnants Dumb end A dumb final has no processing capabilities as they have no memory or processor of their own, it has only a monitor, keyboard and mouse. They are connected to a rudimentary processor. Intelligent Terminal An intelligent terminal contains memory and a CPU and is a standalone device. It only has to connect to the central processor when needed. Command to find terminal type terminfoInput / end product DevicesDumb Terminal Input keyboard and mouse. Output monitorIntelligent Terminal Input keyboard, mouse, scanner, touch screen. Output monitor, printer, speakersSoftware ComponentsKernelThe Kernel is the nerve center of the operating system, the lowest level or the central part. Communication with the hardware is through the kernel. In multi user operating systems it is the kernels job to keep each process and user separate and to organize access to the system hardware, including CPU, memory, disk and other I/O devices.Device HandlersA device is any piece if hardware that is used in an operating system. A device handler is a piece of software within the operating system that communicates with the devices and tells them what to do. This is part of the operating system that is responsible for divine service requests of the device request queue.Spoolers (Simultaneous peripheral operations on-line)Spooling is used when data is postponement to go to an output device after it has been processed. The data is placed into a queue so that the CPU can process something else instead of having to slow down to the speed of the output device. Spoolers are used on chiefly old devices e.g. old printers that can only handle one job at a timeUser InterfaceThis is how the user can view the data within the operating system. The main types of user interfaces are the graphical user inte rface e.g. Windows and Command driven interface e.g. MS DOS and standard UNIX. The CDI was more complicated to use than a graphical user interface as you would have to know certain commands to do very elemental tasks.BibliographyIndexhttp//physinfo.ulb.ac.be/cit_courseware/opsys/ostart.htmhttp//electronics.howstuffworks.com/operating-system1.htmhttp//physinfo.ulb.ac.be/cit_courseware/opsys/ostart.htmhttp//www.canberra.edu.au/sam/whp/unix-cmd.htmlhttp//cm.bell-labs.com/