The main disadvantage of dividing memory into variable partitions is external fragmentation, which requires the searching of memory for holes large enough to satisfy each request.
As we’ve mentioned previously, swapping or compaction is necessary when no hole large enough is available.
A page is a fixed-size contiguous block of a logical address space identified by the page number.
A page frame is a fixed-size contiguous block of physical memory identified by the page frame number. This is the smallest unit of data for memory management and may contain a copy of any page.
A page table is an array that keeps track of which pages of a given logical address space reside in which page frames. Each entry corresponds to one page and contains the starting address of the frame containing the page.
There will be multiple tables. One for each logical space of memory.
With paging, a logical address is broken into two components: a page number p and an offset w within the page. A physical address is broken into two components: a frame number f and an offset w within the frame.
The OS must translate the logical address into the physical address.
Paging avoids external fragmentation by having all pages and page frames the same size so that any page fits into any frame without creating holes between frames. However, there can be internal fragmentation where a program doesn’t take up all the allotted space. This creates a hole at the
Memory Paging was originally found on Access 2 Learn
