Search results
Results from the WOW.Com Content Network
In a system using segmentation, computer memory addresses consist of a segment id and an offset within the segment. [3] A hardware memory management unit (MMU) is responsible for translating the segment and offset into a physical address, and for performing checks to make sure the translation can be done and that the reference to that segment and offset is permitted.
If paging is enabled, the base address in a segment descriptor is an address in a linear paged address space divided into 4 KB pages, so when that is added to the offset in the segment, the resulting address is a linear address in that address space; in IA-32, that address is then masked to be no larger than 32 bits. The result may be looked up ...
Without paging support the segment is the physical unit swapped in and out of memory if required. With paging support the pages are usually the unit of swapping and segmentation only adds an additional level of security. Addresses in a segmented system usually consist of the segment id and an offset relative to the segment base address, defined ...
When pure demand paging is used, pages are loaded only when they are referenced. A program from a memory mapped file begins execution with none of its pages in RAM. As the program commits page faults, the operating system copies the needed pages from a file, e.g., memory-mapped file, paging file, or a swap partition containing the page data ...
If the paging unit is enabled, addresses in a segment are now virtual addresses, rather than physical addresses as they were on the 80286. That is, the segment starting address, the offset, and the final 32-bit address the segmentation unit derived by adding the two are all virtual (or logical) addresses when the paging unit is enabled.
Flat memory model or linear memory model refers to a memory addressing paradigm in which "memory appears to the program as a single contiguous address space." [1] The CPU can directly (and linearly) address all of the available memory locations without having to resort to any sort of bank switching, memory segmentation or paging schemes.
Pages can be paged in and out of physical memory and the disk. The present bit can indicate what pages are currently present in physical memory or are on disk, and can indicate how to treat these different pages, i.e. whether to load a page from disk and page another page in physical memory out. The dirty bit allows for a performance optimization.
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.