HOME

TheInfoList




In
computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both computer hardware , hardware and software. It has sci ...

computing
, an address space defines a range of discrete addresses, each of which may correspond to a
network host Network and networking may refer to: Arts, entertainment, and media * ''Network'' (1976 film), a 1976 American film * ''Network'' (2019 film), an Indian film * ''Network'' (album), a 2004 album by Saga * Network (comics) N'astirh N'Garai ...

network host
,
peripheral device A peripheral or peripheral device is an auxiliary device used to put information into and get information out of the computer. The term peripheral device refers to all hardware components that are attached to a computer and are controlled by the co ...
,
disk sector In computer disk storage, a sector is a subdivision of a track Track or Tracks may refer to: Routes or imprints * Ancient trackway, any track or trail whose origin is lost in antiquity * Animal track, imprints left on surfaces that an animal w ...
, a
memory Memory is the faculty of the brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exis ...
cell or other logical or physical entity. For
software program A computer program is a collection of instructions Instruction or instructions may refer to: Computing * Instruction, one operation of a processor within a computer architecture instruction set * Computer program, a collection of instructions M ...
s to save and retrieve stored data, each unit of data must have an address where it can be located. The number of address spaces available depends on the underlying address structure, which is usually limited by the
computer architecture In computer engineering, computer architecture is a set of rules and methods that describe the functionality, organization, and implementation of computer systems. The architecture of a system refers to its structure in terms of separately specifi ...
being used. 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 in the address is different, addresses in said space will reference different entities. For example, there could be multiple buildings at the same address of "32 Main Street" but in different towns, demonstrating that different towns have different, although similarly arranged,
street address An address is a collection of information, presented in a mostly fixed format, used to give the location of a building, apartment, or other structure or a plot of land, generally using political boundaries Borders are geographic Geog ...
spaces. An address space usually provides (or allows) a partitioning to several regions according to the
mathematical structure In mathematics Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). It ...
it has. In the case of
total order In mathematics, a total or linear order is a partial order in which any two elements are comparable. That is, a total order is a binary relation \leq on some Set (mathematics), set X, which satisfies the following for all a, b and c in X: # a \ ...
, as for
memory address In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both computer hardware , hardware and softwa ...
es, these are simply chunks. Like the hierarchical design of postal addresses, some nested domain hierarchies appear as a directed ordered tree, such as with the
Domain Name System The Domain Name System (DNS) is the hierarchical and Decentralised system, decentralized naming system used to identify computers, Internet#Applications_and_services, services, and other resources reachable through the internet or other intern ...

Domain Name System
or a
directory structure In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both computer hardware , hardware and softwar ...
. In the
Internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a ''internetworking, network of networks'' that consist ...

Internet
, the
Internet Assigned Numbers Authority The Internet Assigned Numbers Authority (IANA) is a standards organization that oversees global IP address allocation, Autonomous system (Internet), autonomous system number allocation, DNS root zone, root zone management in the Domain Name Sys ...
(IANA) allocates ranges of
IP address An Internet Protocol address (IP address) is a numerical label such as that is connected to a computer network A computer network is a set of s sharing resources located on or provided by . The computers use common s over to communi ...
es to various registries so each can manage their parts of the global Internet address space.


Examples

Uses of addresses include, but are not limited to the following: *
Memory address In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both computer hardware , hardware and softwa ...
es for
main memory Computer data storage is a technology consisting of computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations automatically. Modern computers can perform ...
,
memory-mapped I/O Memory-mapped I/O (MMIO) and port-mapped I/O (PMIO) are two complementary methods of performing input/output In computing, input/output (I/O, or informally io or IO) is the communication between an information processing system, such as a compu ...
, as well as for
virtual memory In computing, virtual memory, or virtual storage is a Memory management (operating systems), memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "cre ...

virtual memory
; * Device addresses on an
expansion bus File:AT24C02 EEPROM 1480355 6 7 HDR Enhancer.jpg, Modern EEPROM chip suitable for storing expansion card configuration electronically In computing, an expansion card (also called expansion board, adapter card or accessory card) is a printed ...
; * Sector addressing for
disk drive Disk storage (also sometimes called drive storage) is a general category of storage mechanisms where data is recorded by various electronic, magnetic, optical, or mechanical changes to a surface layer of one or more rotating disks. A disk drive is ...
s; *
File name A filename or file name is a name used to uniquely identify a computer file A computer file is a computer resource for recording data Data are units of information Information can be thought of as the resolution of uncertainty; i ...
s on a particular
volume Volume is a scalar quantity expressing the amount Quantity or amount is a property that can exist as a multitude Multitude is a term for a group of people who cannot be classed under any other distinct category, except for their shared fact ...
; * Various kinds of network host addresses in
computer network A computer network is a set of computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operati ...
s; *
Uniform resource locator A Uniform Resource Locator (URL), colloquially termed a web address, is a reference to a web resource that specifies its location on a computer network and a mechanism for retrieving it. A URL is a specific type of Uniform Resource Identifier ( ...

Uniform resource locator
s in the Internet.


Address mapping and translation

Another common feature of address spaces are mappings and translations, often forming numerous layers. This usually means that some higher-level address must be translated to lower-level ones in some way. For example,
file system In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both computer hardware , hardware and soft ...
on a
logical disk A logical disk, logical volume or virtual disk (VD or vdisk for short) is a virtual device that provides an area of usable storage capacity on one or more physical disk drive(s) in a computer system. The disk is described as ''logical'' or ''virtua ...
operates
linear Linearity is the property of a mathematical relationship (''function Function or functionality may refer to: Computing * Function key A function key is a key on a computer A computer is a machine that can be programmed to carry out se ...
sector numbers, which have to be translated to ''absolute'' LBA sector addresses, in simple cases, via
addition Addition (usually signified by the plus symbol The plus and minus signs, and , are mathematical symbol A mathematical symbol is a figure or a combination of figures that is used to represent a mathematical object A mathematical object is an ...

addition
of the partition's first sector address. Then, for a disk drive connected via
Parallel ATA Parallel ATA (PATA), originally , also known as ATA or IDE IDE, iDE, or Ide may refer to: Organisations * ''Institut für Dokumentologie und Editorik'', a German think tank for the application of digital methods on historical documents * Instit ...
, each of them must be converted to ''logical''
cylinder-head-sector Cylinder, head, and sector of a hard drive. Cylinder-head-sector (CHS) is an early method for giving addresses to each physical block of data on a hard disk drive. It is a 3D-coordinate system made out of a vertical coordinate ''head'', a horizo ...
address due to the interface historical shortcomings. It is converted back to LBA by the
disk controller The disk controller is the controller Controller may refer to: Occupations * Controller or financial controller, or in government accounting comptroller A comptroller is a management Management (or managing) is the administration of an o ...
then, finally, to ''physical''
cylinder A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear In geometry Geometry (from the grc, γεωμετρία; ''wikt:γῆ, geo-'' "earth", ''wikt:μέτρον, -metron'' "measur ...
,
head Head Sport GmbH is an American-Austrian manufacturing company Manufacturing is the creation or production Production may be: Economics and business * Production (economics) * Production, the act of manufacturing goods * Production, in th ...
and sector numbers. The
Domain Name System The Domain Name System (DNS) is the hierarchical and Decentralised system, decentralized naming system used to identify computers, Internet#Applications_and_services, services, and other resources reachable through the internet or other intern ...

Domain Name System
maps its names to (and from) network-specific addresses (usually IP addresses), which in turn may be mapped to
link layer In computer networking, the link layer is the lowest Abstraction layer, layer in the Internet protocol suite, the networking architecture of the Internet. The link layer is the group of methods and communications protocols confined to the link th ...
network addresses via
Address Resolution Protocol The Address Resolution Protocol (ARP) is a communication protocol A communication protocol is a system of rules that allows two or more entities of a communications system 400px, Communication system A communications system or communic ...
. Also,
network address translation#REDIRECT Network address translation Network address translation (NAT) is a method of mapping an IP address space In computing, an address space defines a range of discrete addresses, each of which may correspond to a network host, peripheral dev ...
may occur on the edge of ''different'' IP spaces, such as a
local area network A local area network (LAN) is a computer network A computer network is a set of s sharing resources located on or provided by . The computers use common s over to communicate with each other. These interconnections are made up of te ...
and the Internet. An iconic example of virtual-to-physical address translation is
virtual memory In computing, virtual memory, or virtual storage is a Memory management (operating systems), memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "cre ...

virtual memory
, where different
pages Page most commonly refers to: * Page (paper) A page is one side of a leaf A leaf (plural leaves) is the principal lateral appendage of the vascular plant plant stem, stem, usually borne above ground and specialized for photosynthesis. T ...
of
virtual address space In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithm of an algorithm (Euclid's algorithm) for calculating the greatest commo ...

virtual address space
map either to
page file In computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operations known as Computer program, programs. These prog ...

page file
or to main memory
physical address In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both computer hardware , hardware and softw ...
space. It is possible that several numerically different virtual addresses all refer to one physical address and hence to the same physical byte of
RAM Random-access memory (RAM; ) is a form of computer memory In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic proces ...

RAM
. It is also possible that a single virtual address maps to zero, one, or more than one physical address.


See also

*
AddressabilityAddressability is the ability of a digital device to individually respond to a message sent to many similar devices. Examples include pagers, mobile phone A mobile phone, cellular phone, cell phone, cellphone, handphone, or hand phone, som ...
*
Linear address space Flat memory model or linear memory model refers to a memory addressing paradigm in which "computer memory, memory appears to the program as a single contiguous address space." The CPU can directly (and addressing mode#Sequential addressing modes, l ...
*
Name space In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both computer hardware , hardware and softw ...
*
Virtualization In computing, virtualization or virtualisation (sometimes abbreviated v12n, a numeronym) is the act of creating a virtual (rather than actual) version of something, including virtual computer hardware platforms, Data storage device, storage device ...


References

{{Reflist Computing terminology Data management Computer architecture