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Virtual memory makes application programming easier by hiding fragmentation of physical memory; by delegating to the kernel the burden of managing the memory hierarchy (eliminating the need for the program to handle overlays explicitly); and, when each process is run in its own dedicated address space, by obviating the need to relocate program code or to access memory with relative addressing.
A modern computer operating system usually uses virtual memory to provide separate address spaces or separate regions of a single address space, called user space and kernel space. [1] [a] Primarily, this separation serves to provide memory protection and hardware protection from malicious or errant software behaviour.
Virtual disk: a computer program that emulates a disk drive such as a hard disk drive or optical disk drive (see comparison of disc image software) Data. Data virtualization: the presentation of data as an abstract layer, independent of underlying database systems, structures and storage
In computing, a virtual machine (VM) is the virtualization or emulation of a computer system. Virtual machines are based on computer architectures and provide the functionality of a physical computer. Their implementations may involve specialized hardware, software, or a combination of the two.
Virtual addresses seen by the program are added to the contents of the base register to generate the physical address. The address is checked against the contents of the bounds register to prevent a process from accessing memory beyond its assigned segment. The operating system is not constrained by the hardware and can access all of physical ...
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.
Memory virtualization technology follows from memory management architectures and virtual memory techniques. In both fields, the path of innovation has moved from tightly coupled relationships between logical and physical resources to more flexible, abstracted relationships where physical resources are allocated as needed.
The virtual memory subsystem is then made aware that pages with that region of memory need to be filled on demand if and when program execution actually hits those areas of unfilled memory. This may mean parts of a program's code are not actually copied into memory until they are actually used, and unused code may never be loaded into memory at ...