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Encyclopedia > Address space

In computing, an address space defines a range of discrete addresses, each of which may correspond to a physical or virtual memory register, a network host, peripheral device, disk sector or other logical or physical entity. RAM (Random Access Memory) Look up computing in Wiktionary, the free dictionary. ... In computer architecture, a processor register is a small amount of very fast computer memory used to speed the execution of computer programs by providing quick access to commonly used values—typically, the values being calculated at a given point in time. ... Network node (NN): A grouping of one or more network elements (at one or more sites) which provides network related functions, and is administered as a single entity. ... In computer hardware, a peripheral device is any device attached to a computer in order to expand its functionality. ... In the context of computer hardware, a sector is a sub-division of a track on a magnetic disk or optical disc. ...

A memory address identifies a physical location in computer memory, somewhat similar to a street address in a town. The address points to the location where data is stored, just like your address points to where you live. In the analogy of a person's address, the address space would be an area of locations, such as a neighborhood, town, city, or country. Two addresses may be numerically the same but refer to different locations, if they belong to different address spaces. This is similar to your address being, say, "32, Main Street", while another person may reside in "32, Main Street" in a different town from yours. In computer science, a physical address is the address presented to a computers main memory in a virtual memory system, in contrast to the virtual address which is the address generated by the CPU. Virtual addresses are translated into physical addresses by a memory management unit (abbreviated MMU). ...

Example address spaces:

Specific examples for the Linux kernel: Primary storage is a category of computer storage, often called main memory. ... How virtual memory maps to physical memory Virtual memory is an addressing scheme implemented in hardware and software that allows non-contiguous memory to be addressed as if it were contiguous. ... Ports on the Apple iBook (Early 2003) In computer hardware, a port serves as an interface between the computer and other computers or devices. ... This article or section does not cite any references or sources. ... It has been suggested that Disk sector be merged into this article or section. ... The Linux kernel is a Unix-like operating system kernel. ...

The Kernel Virtual Address Space (KVA) is the virtual memory area in which all Linux kernel threads resides. ... User Virtual Address Space is a specific form of address space or memory allocation. ...

Address translation

In general, things in one address space are physically in a different location than things in another address space. For example, "house number 101 South" on one particular southward street is completely different from any house number (not just the 101st house) on a different southward street.

However, sometimes different address spaces overlap (some physical location exists in both address spaces). When overlapping address spaces are not aligned, translation is necessary. For example, virtual-to-physical address translation is necessary to translate addresses in the virtual memory address space to addresses in physical address space -- one physical address, and one or more numerically different virtual addresses, all refer to the same physical byte of RAM. YOU ARE FUN Random access memory (usually known by its acronym, RAM) is a type of data storage used in computers. ...

Memory models

Many programmers prefer to use a flat memory model, in which there is no distinction between code space, data space, and virtual memory -- in other words, numerically identical pointers refer to exactly the same byte of RAM in all three address spaces. Image File history File links Broom_icon. ... In computer programming, the flat memory model is an approach to organizing memory address space. ... In Computer Programming, Code Space is the memory segment in the main memory allocated to a process to store the code in execution. ... How virtual memory maps to physical memory Virtual memory is an addressing scheme implemented in hardware and software that allows non-contiguous memory to be addressed as if it were contiguous. ...

Unfortunately, many early computers did not support a flat memory model -- in particular, Harvard architecture machines force program storage to be completely separate from data storage. Many modern DSPs (such as the Motorola 56000) have 3 separate storage areas -- program storage, coefficient storage, and data storage. Some commonly-used instructions fetch from all three areas simultaneously -- fewer storage areas (even if there were the same or more total bytes of storage) would make those instructions run slower. The term Harvard architecture originally referred to computer architectures that used physically separate storage and signal pathways for their instructions and data (in contrast to the von Neumann architecture). ... A digital signal processor (DSP) is a specialized microprocessor designed specifically for digital signal processing, generally in real-time. ... The Motorola 56000 (56k) is a family of DSP chips produced by Motorola from the 1980s on, still continuing to be produced in more advanced models in the 2000s. ...

  Results from FactBites:
address space - a Whatis.com definition (290 words)
Address space is the amount of memory allocated for all possible addresses for a computational entity, such as a device, a file, a server, or a networked computer.
Address space may refer to a range of either physical or virtual addresses accessible to a processor or reserved for a process.
Address space may be differentiated as either flat, in which addresses are expressed as incrementally increasing integers starting at zero, or segmented, in which addresses are expressed as separate segments augmented by offsets (values added to produce secondary addresses).
  More results at FactBites »



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