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Identify and fully describe the main developments of Operating Systems, giving examples of their origins and use.

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Introduction

Chris Oliver Unit 27 - Operating Systems OLI02032345 1. Identify and fully describe the main developments of Operating Systems, giving examples of their origins and use. Batch Operating Systems were an early operating system available, and were first introduced in the mid 50's. They were designed to make human manual work easier; humans were replicating identical jobs over and over again, hence in batch. A batch operating system keeps itself eventful; it does this by taking jobs from a batch queue, instead of waiting for people to submit jobs. The jobs are then processed one or more at a time under control of the operating system, however most jobs undertaken in this operating system would be single-task. These type of operating system were often left to work overnight, mainly because the jobs were 'batched' the next job in the queue would be commenced as soon as the previous job had been completed, this way of processing would allow for a large work load to be automatically completed without the requirement to wait and tell the computer to do the next job. Real Time Operating Systems (RTOS) are often embedded, meaning a integral part of a system inside another device. They have very little user interface capability. Real time operating systems like their name implies, respond to an input immediately. "Real time operating systems are capable of processing data so quickly that the results are available to influence the activity currently taking place." [Computer Science 5th Edition, CS French, Ashford Press Gosport, 1996] Real time operating systems guarantee a certain capability within a specified time constraint; these time constraints are usually very rigid. If the system does not conform to this time limit, the system ultimately fails. They are used for various purposes; a few of these are medical equipment, industrial control systems and car computers. Parallel Systems have more than one processor to carry out a single job. ...read more.

Middle

This is handled by using virtual memory; using the hard disc drive as a temporary memory source for processes and data. This can benefit the user in various ways: - The user is not rigidly restricted to space available. Using a large virtual memory space provides convenience for instances where large programs etc. are required to be stored in memory. - Users are using less physical memory; therefore the system can handle more users on the system. High Speed Cache is a fast memory storage; cache predicts the data that the CPU may need next, it then retrieves it from RAM 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. Paging Paging is a method used in operating systems to make a program's 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 bigger 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. Defragmentation 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 found, it will be relocated and stored as a whole. ...read more.

Conclusion

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 today's computing is very little in comparison to what users require. OS Services - 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 function. 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 Input 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 names]: a) Local council office department 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 transactions for the business are conducted. c) An electro-plating circuit board manufactures. d) A travelling company 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. ...read more.

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