# Adapter (computing)

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{{Short description|Adapter used in computing}}
{{About|the general concept of an adapter|the programming design pattern|Adapter pattern}}
thumb|right|An assortment of adapters.
An '''adapter''' in regard to [computing](/source/computing) can be either a [hardware](/source/Computer_hardware) component (device) or [software](/source/software) that allows two or more incompatible devices to be linked together for the purpose of transmitting and receiving [data](/source/data).<ref name="hargraves">{{cite book |title=Hargrave's Communications Dictionary |last=Hargrave |first=Frank |year=2001}}</ref> Given an input, an adapter alters it in order to provide a compatible connection between the components of a system.<ref>{{cite web |last=Christensson |first=Per |date=13 July 2011 |title=Adapter |url=https://techterms.com/definition/adapter |url-status=live |archive-url=https://web.archive.org/web/20230926091137/https://techterms.com/definition/adapter |archive-date=26 September 2023 |access-date=2 July 2019 |website=TechTerms |language=English}}</ref> Both software and hardware adapters are used in many different devices such as [mobile phone](/source/mobile_phone)s, [personal computer](/source/personal_computer)s, [server](/source/server_(computing))s and [telecommunication](/source/telecommunication)s networks for a wide range of purposes.<ref name="eedict">{{cite book |title=Wiley Electrical and Electronics Engineering Dictionary |last=Kaplan |first=Steven M. |publisher=John Wiley and Sons, Inc. |year=2003 |isbn=0-471-40224-9 |location=USA}}</ref> Some adapters are built into devices, while the others can be installed on a computer's motherboard or connected as external devices.

[[File:QLA 2200F.jpg|thumb|right|A [Fibre Channel](/source/Fibre_Channel) host bus adapter]]

A [software component](/source/software_component) adapter is a type of software that is logically located between two software components and reconciles the differences between them.

== Function ==

=== Telecommunication ===
Like many industries, the [telecommunication](/source/telecommunication) industry needs electrical devices such as adapters to transfer data across long distances. For example, [analog telephone adapter](/source/analog_telephone_adapter)s (ATA) are used by telephone and cable companies. This device connects an analog [telephone](/source/telephone) to a computer or network by connecting them to digital communication lines, which enables users to make a call via the [Internet](/source/Internet).<ref>{{cite web |url=https://searchunifiedcommunications.techtarget.com/definition/analog-telephone-adapter |title=What is analog telephone adapter (ATA)? |website=SearchUnifiedCommunications |access-date=13 May 2019}}</ref><ref name="compdict">{{cite book |title=Dictionary of Computing |first=Peter |last=Collin |year=1998 |publisher=Peter Collin Publishing}}</ref>

=== Personal computers===
In modern [personal computer](/source/personal_computer)s, almost every [peripheral device](/source/peripheral_device) uses an adapter to communicate with a [system bus](/source/bus_(computing)), for example:
* [Display adapter](/source/Display_adapter)s used to transmit signals to a [display device](/source/display_device)
* [Universal Serial Bus](/source/Universal_Serial_Bus) (USB) adapters for [printer](/source/computer_printer)s, [keyboard](/source/Computer_keyboard)s and [mice](/source/computer_mouse), among others
* [Network adapter](/source/Network_adapter)s used to connect a computer to a [network](/source/computer_network)
* [Host bus adapter](/source/Host_bus_adapter)s used to connect [hard disk](/source/hard_disk)s or other storage

=== Analog and digital signals ===
Some hardware adapters convert between [analog](/source/analog_signal) and [digital](/source/digital_signal) signals with [A/D](/source/Analog-to-digital_converter) or [D/A](/source/Digital-to-analog_converter) converters. This allows adapters to interface with a broader range of devices. One common example of signal conversion is the [sound card](/source/sound_card), which converts [digital audio](/source/digital_audio) signals from a computer to analog signals for input to an [amplifier](/source/amplifier).

== Types ==
=== Host adapter ===
{{Main|Host adapter}}
A '''host adapter''', '''host controller''' or '''host bus adapter (HBA)''' is a circuit board or device which allows peripheral devices (usually internal) to interface with a computer.<ref>{{cite web |title=What is a Host Adapter? |url=https://www.computerhope.com/jargon/h/host_adapter.htm |url-status=live |archive-url=https://web.archive.org/web/20231202032151/https://www.computerhope.com/jargon/h/host_adapter.htm |archive-date=2 December 2023 |access-date=2019-05-13 |website=www.computerhope.com |language=en}}</ref><ref name="eedict" /> Host bus adapters are used to connect hard drives, networks, and USB peripherals. They are commonly integrated into [motherboard](/source/motherboard)s but can also take the form of an [expansion card](/source/expansion_card).<ref>{{cite web |url=https://www.techopedia.com/definition/17146/host-adapter |title=Host Adapter |website=Technopedia |access-date=2 July 2019}}</ref><ref name="taoe">{{cite book |url=https://books.google.com/books?id=LAiWPwAACAAJ |title=The Art of Electronics |edition=2nd |last1=Horowitz |first1=Paul |last2=Hill |first2=Winfield |publisher=Cambridge University Press |year=1989 |isbn=0-521-37095-7}}</ref>

=== Adapter card ===
{{Main|Expansion card}}
An '''adapter card''' or '''expansion card''' is a circuit board which is plugged into the expansion bus in a computer to add function or resources, in much the same way as a host bus adapter {{see above}}.<ref name="eedict" /><ref name="hargraves" /> Common adapter cards include [video card](/source/video_card)s, [network card](/source/network_card)s, [sound card](/source/sound_card)s, and other I/O cards.<ref>{{cite web |url=https://www.pluralsight.com/blog/it-ops/comptia-a-exam-prep-adapter-cards-and-their-functions |title=CompTIA A+ Exam Prep: Adapter Cards & Functions |website=Pluralsight |language=en |access-date=2019-05-13}}</ref>

=== Video adapter ===
{{Main|Video card}}
A '''video adapter''' (also known as ''graphics adapter'', ''display adapter'', ''graphics card'', or ''video card'') is a type of [expansion card](/source/expansion_card) for computers which converts data and generates the electrical signal to display text and graphics on a [display device](/source/display_device).<ref>{{cite book |title=BCS Glossary of Computing and ICT |last1=Burdett |first1=Arnold |last2=Bowen |first2=Dan |edition=14th}}</ref>

=== Bus master adapter ===
{{See also|Bus mastering}}
'''Bus master adapters''' fit in EISA or MCA expansion slots in computers, and use [bus mastering](/source/bus_mastering) to quickly transfer data by bypassing the [CPU](/source/CPU) and interfacing directly with other devices.<ref name="eedict" /><ref name="compdict" />

=== General purpose interface adapter ===
A '''general purpose interface adapter''' or '''GPIA''' is usually used as an interface between a processing unit and a GPIB ([IEEE 488](/source/IEEE_488)) bus.<ref name="compdict" />

=== Fax adapter ===
{{Main|Fax modem}}
A '''fax adapter''', also called a ''fax card'' or ''fax board'', is an internal [fax modem](/source/fax_modem) which allows a computer to transmit and receive fax data.<ref name="compdict" />

=== Network adapter ===
{{Main|Network interface controller}}
'''Network adapters''' connect a device to a network and enable it to exchange data with other devices on the network. These devices may be computers, servers, or any other networking device.<ref>{{cite web|url=https://www.lifewire.com/introduction-to-computer-network-adapters-817580|title=Understanding Computer Network Adapters (Both Wired and Wireless)|first=Bradley |last=Mitchell|website=Lifewire|language=en|access-date=2019-05-13}}</ref>

''Network adapter'' usually refers to a piece of computer hardware typically in the form of an [Ethernet](/source/Ethernet) card, wireless network card, USB network adapter, or wireless game adapter. Hardware network adapters which are either wired or wireless can be installed on a motherboard, connecting the computer to a network.<ref>{{cite web|url=https://www.lifewire.com/definition-of-adapter-817585|title=What Are Network Adapters and How Do They Work?|last=Mitchel|first=Bradley|website=Lifewire|language=en|access-date=2019-05-13}}</ref>

The term can also refer to a ''virtual'' network adapter which exists only in software, either for the purposes of [virtualization](/source/virtualization), or to interface with some other physical adapter.<ref name="hargraves" />

=== Terminal adapter ===
{{Main|Terminal adapter}}
In [telecommunication](/source/telecommunication)s, a '''terminal adapter''' or '''TA''' acts as an interface between a terminal device, such as a computer or telephone, and a communications network (typically an [integrated services digital network](/source/ISDN)).<ref>{{cite web |url=https://www.techopedia.com/definition/3015/terminal-adapter-ta |website=Techopedia |title=Terminal Adapter (TA) |access-date=2 July 2019}}</ref>

=== Channel-to-channel adapter ===
{{Main|Channel-to-channel adapter}}
A '''channel-to-channel adapter''' (CTCA) connects two input/output [channels](/source/Channel_I%2FO) in [IBM mainframe](/source/IBM_mainframe)s.<ref>{{cite manual|publisher=IBM|title=IBM System/360 Model 65 Functional Characteristics|id=A22-6884-3|year=1968|page=10|url=http://www.bitsavers.org/pdf/ibm/360/functional_characteristics/A22-6884-3_360-65_funcChar.pdf}}</ref>

=== Resource adapters ===
Resource adapters are used to retrieve and route data.<ref>{{Cite web |title=What Is a Resource Adapter? |url=https://javaee.github.io/tutorial/resources001.html |access-date=2022-10-18 |website=javaee.github.io}}</ref> They provide access to databases, files, messaging systems, enterprise applications and other data
sources and targets. Each adapter includes a set of adapter commands that can be used to customize its operation. Adapter commands specify different queues and queue managers, specific messages by message ID, specific sets of messages with the same message ID, message descriptors in the data, and more.

The resource adapters provided with many integration products enable data transformation and adapter-specific behavior recognition on different systems and data structures.

==See also==
*[Computer port (hardware)](/source/Computer_port_(hardware))
*[Controller (computing)](/source/Network_interface_controller)
*[Electrical connector](/source/Electrical_connector)

== References ==
{{reflist}}

{{DEFAULTSORT:Adapter (Computing)}}
Category:Computer peripherals

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Adapted from the Wikipedia article [Adapter (computing)](https://en.wikipedia.org/wiki/Adapter_(computing)) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Adapter_(computing)?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.