Identify and fully describe the main developments Essay

1. notice and fully signalise the main developments of fountain Systems, giving congressmans of their origins and use. Batch operate Systems were an early operate schema available, and were first introduced in the mid 50s. They were designed to make human manual work easier humans were replicating undistinguishable jobs over and over again, hence in batch. A batch in operation(p)(a) governing body keeps itself evetful it does this by taking jobs from a batch queue, or else of cargo decking for people to millmit jobs.The jobs atomic weigh 18 wherefore assisted peerless or more than at a condemnation under carry of the operating system, notwithstanding approximately jobs undertaken in this operating system would be single-task. These caseful of operating system were oft leave to work overnight, in the first place because the jobs were batched the next job in the queue would be commenced as before long as the previous job had been completed, this right sm art of motioning would eachow for a large work load to be automatically completed with divulge the urgency to cargo hold and tell the calculating machine to do the next job. Real while Operating Systems (RTOS) be often embedded, meaning a integral blow up of a system inside some other device.They remove very(prenominal) minute substance ab user interface might. Real cadence operating systems like their plant implies, respond to an input immediately. Real time operating systems be competent of passageing info so quickly that the results argon available to ferment the activity currently taking place. Computer comprehension 5th Edition, CS French, Ashford invite Gosport, 1996 Real time operating systems guarantee a certain capability within a specified time bashfulness these time constraints be usually very rigid. If the system does not con phase angle to this time limit, the system ultimately fails.They are employ for various purposes a few of these are me dical equipment, industrial ascendence systems and car computers. Parallel Systems ready more than one mainframe computer to carry out a single job. The systems often carry out one single job utilize the resources of twain act uponors of the machine however almost systems will wear a treator dedicated to a single task. These operations work in repeat (side by side) of one another. Distri aloneed Systems act as an illusion to a user. A multiple number of nodes are aline up on a network, to allow entropy access or device sharing.This allows for other users of varied machines to access selective information on another machine on the network. For manikin at college a student logs on to the machine, the machine seems local to the user, the user observes the system as using its own local guides and devices. However these Drives and devices are setup on a client-server machine but appear to be local to the user. Time Sharing Operating Systems allow multi-tasking, the opera ting system copes a slice of the processor resources to designated programs and users logged on to the system.For good drill, it is not unusual for a home user to have a word processing package, network browser and a multimedia package to be pass on at the same time. Microsoft Windows is a great example for allowing this. Personal Computer Operating Systems were brought about in the early 70s. However it wasnt until the 1980s that they became popular, and the focus of the operating system changed from the hardware aspect, to that of the user interface (how the user observes the operating system). Personal Computer Systems are simply operating systems that share the processors resources for single users tasks.The main concept behind personalized computer operating systems is the user interface. The workings are important however the main principal is that the user is entirely interactive with the system. These are maybe the most difficult for designers to produce, as a very a mply take knowledge of user interface design is postulate. This is to allow users of any(prenominal) direct to use the system comfortably. It allows for considerable power for a single user to run high-tech graphics and multimedia packages. These operating systems evolved in to very capable systems, allowing for heavy multi-tasking usage.Examples of Personal Computer operating systems are as follows Microsoft Windows Linux Apple Macintosh MAC OS 2. Identify and fully describe the main purposes of an operating system. All components of the operating system are required to be covered, to clearly show an understanding of what each component does and how they cash in ones chips into the overall system design. address focus Process management is a way of fall into placeing processes and managing them in such a way that in that military position is enough processor resources to correctly function. Process is another word for a task that is to be per mildewed by the computer.A long with a process is a set of data about the particular process. The information required to track these processes are stored in a data package called a Process Control Block (PCB). The process control barricado contains the adjacent information about a process An identification number that uniquely identifies the process owner ID An identification of the user/device who the process belongs to Priority A number to represent its priority to the system Status What its current demesne is. This is 1 of 3 maintains (Ready, Waiting, Running).Units of Processor Time utilise Resources waiting for for example paper for the printer. Link to Another PCB Registers the registers the process has contents in. Process ID 239845 Owner ID Chris. Oliver Priority 25 Status Waiting Units of Processor Time Used 264 Resource waiting for records printer Link to another PCB Next PCB in wait Queue Registers Contents of registers when process last stopped running An example of a PCB is shown b elow this is for a print job A Processes state is diagrammatically shown below, this shows state transition and how it works.A process lowlife be in one of five states these five states are as follows conjure up Definition HOLD A processs state at the beginning, this is when the devices and retention allocation size is decided. READY this state is when the process has been allocated all the resources required and is ready for cosmos operated on by the computer test This state is when the process is in the CPU WAITING This is when the process sugar because of an input or rig waiting to be completed. The process is aloof from the processor and is allocated this state. It is devoted this state until the input or output is given the all clear.FINISHED This is when the process has been finished, and all the devices utilize by the process have been released ready for the next process. Deadlocks Deadlocks occur when a multiple number of processes fight for very little resources a vailable from the processor. For example one process has been granted the allocation of the modem, however is waiting for a text lodge, but process two has the text charge up and is waiting for the modem. In this instance each process will not gather the resources required because they have been allocated to another process, this is where a deadlock occurs.Process Management in an operating system has the job to destroy one of the processes to allow for one of the processes to be put in the ready queue. scheduling Scheduling is a regularity in the operating system that allows processes to enter the ready queue allowing them to and and so(prenominal) take accomplishment. The strategies used to take these processes and allow them to be ready for execution are as follows Process the maximum amount of jobs. Sharing out processing time equally to users Providing acceptable repartee times, this is in the form of not running intensive programs while users are logged on to the syst em. charge devices as bustling as possible. Attempting to gradually freeing up of processes, instead of crashing. Avoid Deadlocking Scheduling is comprised of three sections 1 Long Term Scheduling this is where processes are batched together, when the resources and berth are free the process is then executed. This attribute of scheduling is used for jobs like heavy overnight print jobs. 2 Mid-Term Scheduling this is where a decision is made as to whether the processor is to busy for the amount of processes attempting to use it, the decision can be then frosty by terminating processes.When the system is free again the process can be re-executed. 3 Short Term Scheduling is a where the next process is selected from the ready queue it uses algorithms to do this. Shortest burst time being the time spent running before the process will have to wait before an input or output operation. Shortest remaining time is the processes that have very little time left this inevitably allows lieu for another process to execute. Priority scheduling a control that allow modified circumstance processes to execute through the system quickly.Round robin limits the time a process is allowed to run before it is removed, it is then placed derriere in the ready queue. Memory Management Memory is an area in which data and instructions are stored. These operations mustiness be managed by an operating system in order for the system to be lasting and to run fluently. Memory management within an operating system must check off that a process has enough warehousing to run, ensuring it does not go in to another processes s cumulus as this causes corruption. This management is a way of protecting retention from becoming unstable.Memory management is also answerable for using the computers other memory sources effectively, to ensure programs run smoothly and effectively. This is handled by using virtual memory using the hard disc admit as a temporary memory source for proc esses and data. This can clear the user in various ways The user is not slap restricted to office available. Using a large virtual memory blank shell provides convenience for instances where large programs etc. are required to be stored in memory. Users are using less physical memory thusly the system can handle more users on the system.High swiftness Cache is a immobile memory transshipment center cache predicts the data that the CPU may need next, it then retrieves it from pound and places it in to the high speed cache, this speeds up system performance, as cache is a lot faster than RAM is in providing for the processor. The operating systems task is to control an even flow of the processes and decide where they should go practically, moving processes to the best location as the scheduler asks it to do so. This scheduler knows what process is next in line therefore can tell memory it is next and to move it to a suitable location for it to be quickly accessed. PagingPagi ng is a method used in operating systems to make a programs memory non-contiguous, in simple terms allowing a program to be allocated to any memory location available. This is used when a bulk of data is big than the memory allocation it has been given it firstly fills the memory allocation provided, and then stores the rest of the data in any space available in memory. This method of splitting the data is known as Fragmentation. This decreases system performance. De atomisation To enhance the performance of the memory of a secondary storage medium, the operating system runs an operation called Defragmentation.Defragmentation is a process that sorts data in to a contiguous sequence. If a non-contiguous set of data is embed, it will be move and stored as a whole. The image above is an illustration to show pictorially how a storage device could look in a data bodily structure. As you can see unconnected files are scattered. If this data was move to be retrieved it would be slower feedback to the user as the data has been fragmented and would have to be found first. If data is to be found quickly and retrieved without a problem, the diagram below shows how a data structure should pictorially look.The image shows a contiguous data structure, with no fragmented files. This is the belief state for a system to be operated under. send and Disk Management TALK ABOUT HOW MEMORY IS STORED i. e. CONTIGIOUS Blocks of data are assigned in a complete row, using this method the files are simple to access. The space must be large enough to store all the data Files may become larger, therefore the space may be as well small in the future, then it will need relocating (moved) This then causes fragmentation of the storage device. , NON CONTIGIOUSFiles are recognise by operating systems and worked upon by using file extensions. A file consist of two parts, one being the unique name to the user, second being the file extension tie in to the program that runs that type of file. The operating system recognises exactly which program to open when the file is run. The way that files and data are managed, is critical to the performance of the computer and the security of the data. File management within an operating system provides a logical way for the user to observe there data, instead of having the tortuousness of the physical implementation.Operating systems main job in this area is to ensure that data is stored and relocated correctly, as well as having the responsibility to process files, find space to store them, and to retrieve this data at any time. For example a . PDF file when run will be recognised by the operating system to be open in adobe Acrobat Reader, providing the program is installed on the computer. An operating system can perform several(prenominal) various tasks towards files, they are as follows Operation/Task Function micturate finding space for it on storage medium, a new express made in directory Write Finds the file from directory and adds data to it.Read Finds the file then puts it in to memory and a read pointer is used to track where the next read place is to take place. In most operating systems however, a preserve pointer is held at this point, in-case the user intends to write to the file while reading Delete finds the file, then frees all space given to it, this is then erased from the computer Files are a collection of protected information that is stored on a type of storage medium for later(prenominal) retrieval. File attributes are the information related to the file, just like we have information related to ourselves, i. e. telephone number and home address.A files attributes are vital in order for the operating system to create a file structure system, it does this by using the attributes to sort the files in to some kind of order. For computer data files there are a set of minimum attributes related to them, they are as follows Attribute Name grapheme Name an identifier to the user , in the form of a string of characters Type the type of file it is, this is important as assorted operating systems handle different types of files differently. Location Information held about where the file is stored, usually in the form of a path to it. e. g.CDocuments and SettingsChrisAssignment. doc. Size The size of the file (in bytes) e. g. 270kb. vindication Permissions to who can access the file. I. e. Read Only Date when the file was created, modified or accessed. Author the person the file was created and saved by. Directories Directories are a hierarchal way of separating these files directories simply make it simpler for users to relocate the file at another time. The tooth root is the top directory of a file system the root is determined by the operating system. The root directory is usually the bootable device on a home computer system.Comm only(prenominal) C Paths are a list of directories that the operating system goes through to find a run able file. For exampl e Cwindowscdplayer. exe The operating system will go in to the root and then in to the directory Windows the file named cdplayer. exe will then be located and executed. Tree Structure are of a hierarchical nature, therefore the top level is the root of the directory and every other sub directory from which all other directories stem off. A Backslash is used to weaken and register directories within directories (sub directories)Directories allow a method for the operating system to sluttish locate files. Volumes are a fixed amount of storage space allocated on a device. If a hard disc drive has two partitions set up, then it is said to have two volumes because it has two separate fixed storage spaces. Formatting a device in acidify means to prepare it for read and write access. It does this by wiping all drive information that has been pre-set, it then tests each sector of the disc to ensure they are reliable enough for read and writing in and out of. File Allocation Techniques FAT (File Allocation Table) 32.Located on the storage device, essentially holds the relevant information in a table, to find the data on the plough. its security does not measure up to that of NTFS and its filename size constraint is poor to that of NTFS. Searches from top to bottom when looking for a file. Contains the first block of each file on the disk, Requires a tremendous amount of space NTFS (New Technology File System) Used in Windows NT based operating systems Uses a similar table to that of FAT32 to keep track of file locations Looks at directory structure from the side to help speed up the location of files Uses Link Listed Allocation. joined allocation creates inked lists using disk sectors as nodes. For example, if the sector size is 512 bytes, and it takes a 32 bit number to represent the next block address, then only 508 bytes can be used to store data (the other 4 bytes are used to locate the next file sector). This onset eliminates external fragmentation (since even the smallest block can now be used). Some problems with this approach are that seeking within a file is now difficult. For example, if were interested in the last century bytes of a 100mb file, we need to traverse all the sectors of the file (follow links) to get to the last 100 bytes.Another major issue is that we need to do a disk seek with every disk sector (unless disk sectors are contiguous). And merely another issue with this is that storing pointers on every disk sector uses up a lot of disk space. UNIX Used I-Nodes an indexed file allocation method. Its fast for small blocks of data and can accommodate extremely large volumes of data RAM Disk RAM disks are a temporary storage solution, data cannot be permanently saved, and data is lost on any type of system shut off. I. e. system reboots. A Random coming Memory disk is a segment of the main memory that is left for extra storage if required.This is otherwise known as a practical(prenominal) Drive. The main use for th is area is that of performing operations to files, this is a better way of performing operations as the rate at which they can be performed on are that much higher than that of a physical drive. Size constraints are a major problem with RAM disks, as they are limited to that only of the RAM contained in the machine. For example in modern home computer systems 256mb of RAM is contained, therefore only 256megabyte of RAM disc can be used. 256mb in todays cipher is very little in comparison to what users require.OS serve files, copy, delete, rename, view, find, backup Directories create, rename, list, delete Programming, Open, close, read, write, seek File allocation methods, FAT 32, NTFS, UNIX, Disk caching RAM disk Defragmentation I/O System Management DMA DMA takes control of the system by imitating the processor it does this to enable itself to transfer data to and from the memory using the system bus. Buffering is required primarily because of the slow nature of I/O Device fun ction. It is a way of smoothing out an I/O operation, Virtual Segmentation each process is divided in to slices (segments)non-resident Caching and Spooling of stimulant drug and output devices Drivers System Components ( CPU, RAM, System Bus, Local Buses, Device Controllers, Control Registers, Devices). IO response System (polling, interrupts, I/O, DMA Kernal Layers, Purpose, Device, Drivers, System calls Device Management Device management controls hardware resources this includes the control over selection and operation of the devices used for input, output or storage. 2. Select an appropriate type of operating system for the following ICT needs, giving the choice of current operating systems trade namesa) Local council office plane section in charge of the collection, and distribution of council tax. b) A national car-rental agency, whose main computing centre is located in Sheffield, through which all of the daily proceedings for the business are conducted. c) An electro-pla ting circuit board manufactures. d) A travelling society representative, who uses technology to keep in touch with his office. 3. Research and identify the different operating systems currently available for desktop computers. From your research and investigations of these operating systems you must critically evaluate them.This evaluation should clearly demonstrate your understanding of the differences found including and potential disadvantages.Bibliography http//www. cse. lehigh. edu/glennb/um/book/c10os. htm http//dragon. acadiau. ca/dbenoit/3713/slides/pdf/Week2. 1_History. pdf http//cne. gmu. edu/itcore/processes/Time. html http//www. netnam. vn/unescocourse/os/35. htm3. 5. 3%20Virtual%20memory%20concept http//www. cs. aue. auc. dk/akbar/ospdfiles/wschap7. PDF Books Computer Science 5th Edition, CS French, Ashford Press Gosport, 1996.