<operating system> A technique for increasing the memory space available by moving infrequently-used parts of a program's working memory from RAM to a secondary storage medium, usually hard {disk. The unit of transfer is called a page. A memory management unit (MMU) monitors accesses to memory and splits each address into a page number (the most significant bits) and an offset within that page (the lower bits). It then looks up the page number in its page table. The page may be marked as paged in or paged out. If it is paged in then the memory access can proceed after translating the virtual address to a physical address. If the requested page is paged out then space must be made for it by paging out some other page, i.e. copying it to disk. The requested page is then located on the area of the disk allocated for "swap space" and is read back into RAM. The page table is updated to indicate that the page is paged in and its physical address recorded. The MMU also records whether a page has been modified since it was last paged in. If it has not been modified then there is no need to copy it back to disk and the space can be reused immediately. Paging allows the total memory requirements of all running tasks (possibly just one) to exceed the amount of {physical memory}, whereas swapping simply allows multiple processes to run concurrently, so long as each process on its own fits within physical memory. (1996-11-22)

<storage, architecture> What a paging system does when it copies part of a task's working memory from RAM to {swap space} on disk. [Jargon File] (1995-01-23)

<storage, architecture> What a paging system does when it copies part of a task's working memory from swap space on disk to RAM. [Jargon File] (1995-01-23)

<operating system> A file used by a program or, more often, an operating system as swap space. A swap file is usually allocated as a long contiguous section of a hard disk to reduce access time. The disk space used for a swap file can not be used for other things. Under Microsoft Windows, swap files are recommended not to exceed three times the available RAM and are usually 150 percent of the RAM size. (1996-11-15)

<operating system> An area of disk (e.g. a swap file) used to store the state of a process that has been swapped out. Under a virtual memory system, it is the amount of swap space rather than the amount of physical memory which determines the maximum size of a single process and the maximum total size of all active processes. [Jargon File] (1994-11-03)

<operating system> (Or "WIN386.SWP") 386SPART.PAR is a hidden file created by Windows 3.1 for use as {virtual memory} swap file. It is generally found in the {root directory}, however it may appear elsewhere (typically in the WINDOWS directory). Its size depends on how much virtual memory you have set up under (Control Panel) Enhanced under Virtual Memory. If you move or delete this file Windows will complain the next time you start it with a Swap File error. Windows 95 uses a similar file, except it is named WIN386.SWP, and the controls for it are located under Control Panel - System - Performance tab - Virtual Memory. (1996-05-28)

Intel 5-level paging, referred to simply as 5-level paging in Intel documents, is a processor extension for the x86-64 line of processors. It extends the size of virtual addresses from 48 bits to 57 bits, increasing the addressable virtual memory from 256 TB to 128 PB.

1. <hardware, communications> (Or "beeper", "bleeper" (UK?)) A small wireless receiver that, when triggered (generally via phone), will beep or vibrate (un)pleasantly. The wearer will have been trained to respond to this signal by looking at a small screen on the device for an unimportant message. In recent years, pagers have grown more complex, allowing for long alphanumeric messages to be received and scrolled though (as opposed to earlier models, which supported only short numeric messages); at the same time as pager functions are integrated into some PDAs. If this trend continues, the distinction between PDAs and high-end pagers will disappear. Short Message Service allows a mobile phone to display a message, just like an alphanumeric pager. 2. <tool> A program for viewing a text file a screenful at a time via a text terminal, as opposed to scrolling through it in a GUI window, or catting it all at once to the terminal. The best known pagers are more, less, pg and list.com. (1997-09-11)