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A page, memory page, or virtual page is a fixed-length contiguous block of virtual memory, described by a single entry in a page table.It is the smallest unit of data for memory management in an operating system that uses virtual memory.
In virtual memory systems, thrashing may be caused by programs or workloads that present insufficient locality of reference: if the working set of a program or a workload cannot be effectively held within physical memory, then constant data swapping, i.e., thrashing, may occur. The term was first used during the tape operating system days to ...
Physical memory can contain pages belonging to many processes. Pages can be held on disk if seldom used, or if physical memory is full. In the diagram above, some pages are not in physical memory. A page table is a data structure used by a virtual memory system in a computer to store mappings between virtual addresses and physical addresses.
A 68451 MMU, which could be used with the Motorola 68010. A memory management unit (MMU), sometimes called paged memory management unit (PMMU), [1] is a computer hardware unit that examines all memory references on the memory bus, translating these requests, known as virtual memory addresses, into physical addresses in main memory.
Virtual memory combines active RAM and inactive memory on DASD [a] to form a large range of contiguous addresses.. In computing, virtual memory, or virtual storage, [b] is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" [3] which "creates the illusion to users of a very large (main) memory".
When processes use virtual addresses and an instruction requests access to memory, the processor translates the virtual address to a physical address using a page table or translation lookaside buffer (TLB). When running a virtual system, it has allocated virtual memory of the host system that serves as a physical memory for the guest system ...
The general operation of the segmentation unit is otherwise unchanged. The paging unit may be enabled or disabled; if disabled, operation is the same as on the 80286. If the paging unit is enabled, addresses in a segment are now virtual addresses, rather than physical addresses as they were on the 80286.
Paging is a virtual memory system, and segmentation is another. "Virtual memory" refers to the translation between physical memory addresses and nonphysical (thus "virtual") addresses. Virtual memory allows swapping to secondary storage, but it certainly isn't synonymous with that, nor is it the only thing it's used for. So it's really a common ...