virtual memory

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الإنجليزية - الإنجليزية
Memory that appears to be RAM but is being simulated (by a process called paging) on a hard disk; allows a computer to operate as if it had more memory than it actually does, but with some loss of performance
  In computer systems, the memory as it appears to, i e , as it is available to, the operating programs running in the central processing unit (CPU)   Note: The virtual memory may be smaller, equal to, or larger than the real memory present in the system
Virtual memory is a computing technique in which you increase the size of a computer's memory by arranging or storing the data in it in a different way. Memory, often as simulated on a hard disk, that emulates RAM, allowing an application to operate as though the computer has more memory than it actually does
What do you do when you run out of real random access memory (RAM)? Easy Pass it off to virtual memory To do this you need a virtual memory manager (usually a function of the operating system) that maps chunks of data and code to storage areas that aren't RAM Virtual memory is really a part of your hard disk called a swap file, dedicated as a storage area for bits of data in RAM that aren't being used much By freeing up RAM, you're virtually increasing the amount of working memory available to you
Virtual memory Virtual memory will temporarily assemble extra RAM by use of permanent media
Use of hard drive space to serve as additional memory When a computer has limited RAM, this can be used, but it is much slower than real RAM, since access to a disk is much slower than access to memory chips See also: virtual memory (Webopedia)
VM Extra memory available on a system that is stored on a hard disk and is therefore essentially unlimited, although much slower than genuine RAM Usually it is called swap space
Memory allocation service supporting multiple, protected address spaces On systems with secondary storage, applications can use much more virtual memory than the memory physically available This module is specifically designed to implement distributed UNIX subsystems on top of the microkernel
(apparent) increase in the main memory of a computer by using part of the hard disk as additional memory
A method used to extend the size of RAM (random access memory) by using part of the hard disk One should be cautious about using virtual memory
A way of using disk storage space to make the computer work as if it had more memory When a file or program is too big for the computer to work with in its memory, part of the data is stored on disk This virtual storage is divided into segments called pages; each page is correlated with a location in physical memory, or RAM When an address is referenced, the page is swapped into memory; it is sent back to disk when other pages must be called The program runs as if all the data is in memory The computer uses a hardware device called a memory management unit (MMU) to manage virtual memory
The use of a disk partition or a file on disk to provide the same facilities usually provided by RAM The virtual-memory manger in Mac OS X provides 32-bit (minimum) protected address space for each task and facilitates efficient sharing of that address space
Real memory (RAM) plus swap memory (hard drive)
Apparently extended memory on a computer, consisting partly of real memory (RAM) and partly of disk space A technique to handle programs and applications that are too large to fit into real memory Can degrade performance if used too heavily
Memory which resides on the slow, hard disk and not in the fast electronics
Simulated memory When RAM is full, the computer swaps data to the hard disk and back as needed See Swapping
A way to provide large memory spaces to processes Virtual memory usually exceeds the actual memory capacity Virtual memory is broken into pages for ease of management Active pages are in memory, while the rest are on a disk
The use of hard disk storage to expand effective memory capability
- The process of using a portion of disk space as a temporary storage area for memory Synonymous with Swap
hard disk storage space used as RAM by the System software (built in to System 7 and above); set via the Memory Control Panel (note: many newer applications run much more stable with Virtual Memory turned off)
refers to the use of disk memory as if it were main memory
(computer science) memory created by using the hard disk to simulate additional random-access memory; the addressable storage space available to the user of a computer system in which virtual addresses are mapped into real addresses
This is system memory that is simulated by the hard drive When all the RAM is being used (for example if there are many programs open at the same time) the computer will swap data to the hard drive and back to give the impression that there is slightly more memory
For the computer virtual memory seems like normal memory, but in reality virtual memory is storage space on the hard disk If your computer uses virtual memory a lot, it will slow down your systems performance, because hard disks are slow compared with RAM For more information see Stop Windows 95 from wildly accessing your Hard Disk
Method of using hard disk space to provide extra memory Simulates additional RAM In Windows, the amount of virtual memory available equals the amount of free RAM plus the amount of disk space allocated to the swap file In Macintosh System 7, virtual memory is controlled in the Memory Control Panel The default setting is twice the amount of RAM in the machine However, the amount of RAM plus the amount of virtual memory TOGETHER is the amount of disk space you must allocate For example, if you have 4 MB of RAM and set virtual memory at 8 MB, 12 MB of disk space is allocated
A technique in which a large memory space is simulated with a small amount of RAM, a disk, and special paging hardware For example, a virtual 1 megabyte address space can be simulated with 64K of RAM, a 2 megabyte disk, and paging hardware The paging hardware translates all memory accesses through a page table If the page that contains the memory access is not loaded into memory a fault is generated which results in the least used page being written to disk and the desired page being read from disk and loaded into memory over the least used page
A sneaky trick by which Unix pretends to have more memory than it really does When you are not looking, Unix copies information from memory to the disk to free up space in memory When you need the information on disk, Unix copies it from the disk back into memory Virtual memory is generally invisible, except when a program uses it too enthusiastically; then the computer spends all its time copying stuff back and forth to the disk and no time doing useful work, a condition called thrashing
The address space available to a process running in a system with a memory management unit (MMU) The virtual address space is usually divided into pages of 2 bytes The bottom n address bits (the offset within a page) are left unchanged and the upper bits give a (virtual) page number which is mapped by the memory management unit to a physical page number Virtual memory is usually much larger than physical memory Paging allows the excess to be stored on disk and copied to RAM as needed, so that programs can be run whose memory requirements for code and data together exceed the amount of RAM available Performance depends strongly on how a program's memory access pattern interacts with the paging scheme
A computer term for a performance enhancing feature of some software Virtual memory is a process where hard disk storage space is borrowed and caused to act as if it were additional RAM The system will then be able to perform more complex functions just as if it had the additional RAM memory actually installed See also RAM
Virtual Memory System
method of increasing Random Access Memory (RAM) by using part of the hard disk, VMS
virtual memory

    الواصلة

    vir·tu·al me·mo·ry

    التركية النطق

    vırçuıl memıri

    النطق

    /ˈvərʧo͞oəl ˈmemərē/ /ˈvɜrʧuːəl ˈmɛmɜriː/
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