Terms of paging in OS

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Page Table-


  • Page table is a data structure.
  • It maps the page number referenced by the CPU to the frame number where that page is stored.

Characteristics-


  • Page table is stored in the main memory.
  • Number of entries in a page table = Number of pages in which the process is divided.
  • Page Table Base Register (PTBR) contains the base address of page table.
  • Each process has its own independent page table.

Working-



  • Page Table Base Register (PTBR) provides the base address of the page table.
  • The base address of the page table is added with the page number referenced by the CPU.
  • It gives the entry of the page table containing the frame number where the referenced page is stored.

Page Table Entry-


  • A page table entry contains several information about the page.
  • The information contained in the page table entry varies from operating system to operating system.
  • The most important information in a page table entry is frame number.

In general, each entry of a page table contains the following information-


Frame Number-


  • Frame number specifies the frame where the page is stored in the main memory.
  • The number of bits in frame number depends on the number of frames in the main memory.

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