paging


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paging

[′pāj·iŋ]
(computer science)
The scheme used to locate pages, to move them between main storage and auxiliary storage, or to exchange them with pages of the same or other computer programs; used in computers with virtual memories.

paging

(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.

paging

(1) In a virtual memory computer, it is the transfer of program segments (pages) into and out of memory. Although paging is the primary mechanism for virtual memory, excessive paging is not desirable (see thrashing).

(2) A communications service that began in the U.S. in the 1980s. It evolved from a one-way beeper to one-way numeric text to one-way alphanumeric text to a two-way text service.
References in periodicals archive ?
SNET Paging will provide uninterrupted service to Page 2000 customers.
It has also put increased demands on the limited paging spectrum allotted by the FCC.
Our expertise in satellite broadcasting, combined with their expertise in paging infrastructure, creates a powerful combination for a variety of paging applications," said Joe Amor, vice president and general manager of Microspace.
population with paging service, and three extremely strong channels of distribution nationwide (direct, retail and reseller), the overall growth of TSR Wireless should rise tremendously in the years to come.
Since the launch of China Telecom's nationwide roaming paging network in 1997, Motorola has also won contracts in seventeen provincial cities and seven provinces in China, including Henan, Ningxia, Zheijiang, Liaoning, Guangxi, Yunnan and Sichuan province.
For paging operators, the main benefits are the reduction in trunk setup time, the ability to use the Caller Line Identification (CLI) feature to initiate numeric messaging, increasing the system capacity and flow of handling information, thus reducing the number of trunks which in turn lowers the carriers' operating costs and benefits end users.
In this contract, Motorola will provide five complete sets of its latest state-of-the-art paging infrastructure product, the Wireless Messaging System (WMS), including the Wireless Message Gateway(TM) paging terminal, featuring one of the highest processing capabilities in the industry; the RF-Conductor(TM), a high capacity paging network controller; and Nucleus(R) paging transmitters with RF-Baton
With 170 retail locations nationwide under the TSR Wireless name, TSR is considered America's largest paging retailer.
The PhenX IPG is TekNow's solution for secure and reliable paging via the Internet.
With this contract, Motorola is providing a high-speed paging network to both an islandwide and a regionwide private operator in Taiwan.
Motorola's paging system employs the Inter-switch Paging Networks Protocol (IPNP) defined by China Telecom to support Multi-Frequency Roaming.
We at Beeperland believe that advanced voice paging has an extremely bright future in both Chile and South America among not only business users, but also family members wishing to keep closer in touch," said Ben Helsten, President, Beeperland.