Define paging and explain its working principle with a suitable example
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Ans. Paging is a memory-management scheme that removes the requirement of contiguous allocation of physical memory. Address mapping is used to maintain the illusion of contiguity of the virtual address space of a process despite its discontiguous placement in physical memory.
Physical memory is broken into fixed-size blocks called frames. Logical memory is also broken into blocks of the same size called pages. When process is to be executed, its pages are loaded into any available memory frames from the backing store. The backing store is divided into fixed-sized blocks that are of the same size as the memory frames.
The hardware support for paging is shown in fig. 2.11. every address generated by the CPU is divided into two parts – a page number (p), a page offset (d). The page number is used as an index into a page table. The page table contains the base address of address of each page in physical memory. The base address is combined with the page offset to define the physical memory address that is sent to the memory unit.
Physical memory is broken into fixed-size blocks called frames. Logical memory is also broken into blocks of the same size called pages. When process is to be executed, its pages are loaded into any available memory frames from the backing store. The backing store is divided into fixed-sized blocks that are of the same size as the memory frames.
The hardware support for paging is shown in fig. 2.11. every address generated by the CPU is divided into two parts – a page number (p), a page offset (d). The page number is used as an index into a page table. The page table contains the base address of address of each page in physical memory. The base address is combined with the page offset to define the physical memory address that is sent to the memory unit.
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