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Operating System Functions (Part 3)Operating System Functions (Part 3)5. Memory Management The memory unit has very important role for data processing. The processor takes data and program instructions from RAM during processing. The data and programs are loaded from disk into RAM. The operating system loads the data and programs into RAM and allocates the memory areas and manages these properly. When the program is closed, the operating system clears the memory area allocated to that program and its data. During data processing some operating systems use the hard disk as memory. It is called the virtual memory. During processing, operating system transfers some of data from RAM to hard disk and reloads again when required. The operating system exchanges the data and programs between RAM and hard disk. The data or programs are stored in hard disk in temporary file called the swap file. The word “swap” means exchange. This technique of swapping data between memory and hard disk is called Paging. Operating system spends a lot of time in paging process, instead of executing the application software; it is referred to as Thrashing. 6. Scheduling Jobs A job is an activity or operation that a processor performs. It may be receiving data from input device, sending output to output device or loading data from disk into RAM etc. The operating system determines the order in which the jobs are to be processed. Sometimes, the operating system processes jobs on a fir-come first- served basis. But in some situations, one user may have higher priority than the other users. In this case, the operating system has to adjust the schedule ofjobs. Sometimes, a device is busy in processing a job and another job is sent to that device. For example, three documents are sent to printer but the printer can print only one document at a time. In this case, the operating system places the other documents in buffers. A buffer is a temporary storage area in memory, which is used to place data. In this case, operating system uses buffers with print jobs. This process is called Spooling. Multiple print jobs are arranged in a queue iii the buffer. See Also or Related Articles:
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