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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 ...
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.
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 ...
An example is a 32-bit x86 processor with 4 GB and without Physical Address Extension (PAE). In this case, the processor is able to address all the RAM installed and no more. However, even in this case, paging can be used to support more virtual memory than physical memory. For instance, many programs may be running concurrently.
In a computer using virtual memory, accessing the location corresponding to a memory address may involve many levels. In computing, a memory address is a reference to a specific memory location in memory used by both software and hardware. [1] These addresses are fixed-length sequences of digits, typically displayed and handled as unsigned ...
Each page table entry (PTE) holds the mapping between a virtual address of a page and the address of a physical frame. There is also auxiliary information about the page such as a present bit, a dirty or modified bit, address space or process ID information, amongst others.
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.
The physical gateway address is called the media access control(MAC) address or burned in address (BIA). The physical address is assigned when the device is manufactured, and cannot be changed. When a frame is sent to a device not on the local network, the gateway's MAC address is used in the frame header. The gateway address must be configured ...