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Address spaces are created by combining enough uniquely identified qualifiers to make an address unambiguous within the address space. For a person's physical address, the address space would be a combination of locations, such as a neighborhood, town, city, or country. Some elements of a data address space may be the same, but if any element ...
A few computers have a main memory larger than the virtual address space of a process, such as the Magic-1, [34] some PDP-11 machines, and some systems using 32-bit x86 processors with Physical Address Extension. This nullifies a significant advantage of paging, since a single process cannot use more main memory than the amount of its virtual ...
Diagram of relationship between the virtual and physical address spaces. In computing, a physical address (also real address, or binary address), is a memory address that is represented in the form of a binary number on the address bus circuitry in order to enable the data bus to access a particular storage cell of main memory, or a register of memory-mapped I/O device.
The physical address of computer memory banks may be mapped to different logical addresses for various purposes. In a system supporting virtual memory, there may actually not be any physical memory mapped to a logical address until an access is attempted. The access triggers special functions of the operating system which reprogram the MMU to ...
Relationship between pages addressed by virtual addresses and the pages in physical memory, within a simple address space scheme. Physical memory can contain pages belonging to many processes. Pages can be held on disk if seldom used, or if physical memory is full. In the diagram above, some pages are not in physical memory.
On the 360/65, on S/370 models without DAT and when running with translation turned off, there are only a flat real address space and a flat absolute address space. On the 360/67, S/370 and successors through S/390, when running with translation on, addresses contain a segment number, a page number and an offset. Although early models supported ...
Diagram of relationship between the virtual and physical address spaces. Date: 5 April 2007: Source: en:Image:Virtual address space and physical address space relationship.png: Author: Traced by User:Stannered, original by en:User:Dysprosia: Permission (Reusing this file) BSD original: Other versions
The offset part of the logical address contains an offset inside the segment, i.e. the physical address can be calculated as physical_address = segment_part × 16 + offset, if the address line A20 is enabled, or (segment_part × 16 + offset) mod 2 20, if A20 is off. [clarification needed] Every segment has a size of 2 16 bytes.