When a page is accessed, if the valid/invalid bit is set to valid, then the page is simply accessed in main memory via the logical address entry in the table. If the page is not contained in physical memory, then a page fault is generated. This causes the program to try and load the page into memory. The system first checks if the requested address is valid. If not, then the process is terminated. If the address is valid, then the system checks for free frames. If a free frame is found, then the system loads the requested data from the disk and places it in the free frame. The valid/invalid bit is set to valid in the paging table, the logical address is set to the previously free frame, and the program can continue executing. If no free frames are present, then the system must swap out a currently used frame and place the requested data in the frame. The system, an algorithm such as LRU, MRU, etc. to determine which page to swap out. The system swaps out the old page, loads in the new page and then returns control to the process.
Data and Information Data is an unprocessed raw fact which does not give complete meaning about any object,person, entity etc. But when various inter-related data arranged in a row, it gives a complete meaning which is referred to as information. For Example: ID Name Address Program 1101 Ram Shrestha Biratnagar BScIT is information of a specific person. Database Database is a repository(storage) for the organized collection of related information of data items. It Consist of meaningful arrangement of data, relationship, constraints, schema etc. In modern days we define database as a computerized record-keeping system used to store information and allows users to retrieve and update these information on their request. Some example of databases are telephone directory, data of SLC result, student and employee records etc. Database Management System(DBMS) Database is the softw...
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