Report on Multi User Operating Systems Essay Example for Free

Report on Multi User Operating Systems EssayResources Sharing Concepts of Resource SharingA multi drug user operate trunk stop support to a greater extent that sensation user at a sentence, this means that multiple users can share the same dodging resources simultaneously. The users of a multi user operating agreement can share both hardware and software resources, the operating system carries out complicated routines to manage all the movees that the users are running. List of share resources * Hardware CPU Power, repulse, Hard drive, Peripherals (printer, Scanner, CD ROM) Other peripherals may be made available in a MUOS for users who require them (Floppy disk drive, Speakers, Head Phones, depiction Cameras etc. )* Software Scheduler Software ( trained to manage and prioritise tasks). Batch JobSome processes take a long time to complete and can ofttimes disturb other(a) computer tasks that are important. A Batch Job is a file that does not require any user intera ction, so it is chasten up to run a number of processes at a later time, often late at night. adept example is overnight maintenance at a bank when they update all the accounts so it will not disrupt the other processes during the day.Multi-Tasking Concepts of multi-taskingMulti tasking is when the operating system switches between tasks at a actually high speed, it can sometimes seem as though it is performing more than one task at a time. For example, a user could be printing and typing at the same 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 memory and the processes may run slower.The two types of multi-tasking are co-operative and pre-emptive* Pre-emptive This is when the applications are forced to give up the CPU after a current length of time so that the other processes get an equal share of CPU time. (time-sliced).* Co-operative multi-tasking is wh en it is the current 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 apiece 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 will not be stalled by other smaller tasks.A disadvantage of both types of multi-tasking is that it requires a large amount of memory to work properly.Background Processing Concepts of background / foreground processingWhen a task will require a long time to process and requires no user input e.g. downloading a large 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 process the customers accounts at the end of each day, the operating system can b e left to run the process overnight or when the CPU is not currently being used by a task that requires a great deal of processing. Unix command to run background processingControl-Z = Leave process running in backgroundbg = exsert 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 job, 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 have more that one processor. In some expensive operating systems it is possible to connect more CPUs to the system and have them work together to execute tasks.Multiprocessing can significantly reduce the time taken to execute each process. An operating system with multiple processors can perform dia metrical tasks separately or a task can be split up and processed by different 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 slicing 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 program 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 this could alike be a disadvantage if there are galore(postnominal) users executing smaller tasks as they w ill 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 instructions that control the computer. The control unit in a CPU controls everything which happens within, the ALU does calculations and is responsible for stopping point making and the accumulator stores the last data that was decoded for future processes. There are various registers within the CPU, they are the instruction register, which holds the instruction that is being decoded, the program proceeds stores what part of the program we have reached, the memory address register points to the location where data is being fetched or written and the memory data register is a storage area for data that is currently being transferred between the mem ory and the CPU. The Fetch-Decode-Execute Cycle has three important stages.* FETCH The CPU collects an instruction from the RAM* rewrite 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 Access 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 like RAM, this is a great deal slower than physical memory. Another type of memory is Read Only Memory (ROM) which can be written to but cannot be erased.Data reposition 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 writte n to and erased Zip Drive can be written to and erased, 100 250Mb remainders Dumb Terminal A dumb terminal 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 central 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 terminfo excitant / Output DevicesDumb Terminal Input keyboard and mouse. Output monitorIntelligent Terminal Input keyboard, mouse, scanner, touch screen. Output monitor, printer, speakersSoftware ComponentsKernelThe Kernel is the eye 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 an d 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 servicing requests of the device request queue.Spoolers (Simultaneous peripheral operations on-line)Spooling is used when data is waiting to go to an output device after it has been processed. The data is place 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 principally old devices e.g. old printers that can only handle one job at a timeUser InterfaceThis is how the user can pull in the data within the operating system. The main types of user interfaces are the graphical user interface e.g. Windows and Command driven interface e.g. MS DOS and pattern UNIX. The CDI was more complicated to use th an a GUI as you would have to know certain commands to do very basic 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/