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Similarly, a page frame is the smallest fixed-length contiguous block of physical memory into which memory pages are mapped by the operating system. [ 1 ] [ 2 ] [ 3 ] A transfer of pages between main memory and an auxiliary store, such as a hard disk drive , is referred to as paging or swapping.
Some operating systems periodically look for pages that have not been recently referenced and then free the page frame and add it to the free page queue, a process known as "page stealing". Some operating systems [e] support page reclamation; if a program commits a page fault by referencing a page that was stolen, the operating system detects ...
The operating system provides an interface between an application program and the computer hardware, so that an application program can interact with the hardware only by obeying rules and procedures programmed into the operating system. The operating system is also a set of services which simplify development and execution of application programs.
The page table is a key component of virtual address translation that is necessary to access data in memory. The page table is set up by the computer's operating system, and may be read and written during the virtual address translation process by the memory management unit or by low-level system software or firmware.
The operating system (OS) then handles the situation, perhaps by trying to find a spare frame of RAM and set up the page map to map it to the requested virtual address. If no RAM is free, it may be necessary to choose an existing page (known as a victim ), using some replacement algorithm , and save it to disk (a process called paging ).
The operating system delays loading parts of the program from disk until the program attempts to use it and the page fault is generated. If the page is not loaded in memory at the time of the fault, then it is called a major or hard page fault. The page fault handler in the OS needs to find a free location: either a free page in memory, or a ...
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Besides powering iPhone, iOS is the basis for three other operating systems made by Apple: iPadOS, tvOS, and watchOS. [9] iOS formerly also powered iPads until iPadOS was introduced in 2019 and the iPod Touch line of devices until its discontinuation. [10] iOS is the world's second most widely installed mobile operating system, after Android.