Expansion card: Difference between revisions

{{shortShort description|Circuit board ablefor to be connectedconnecting to a computer system to add functionality}}

[[File:IBM 1401 card cage.agr.jpg|thumb|Rack of [[IBM Standard Modular System]] expansion cards in an [[IBM 1401]] computer using a 16-pin gold plated edge connector first introduced in 1959]]

[[File:Thunderbolt 3 Cable connected to OWC Thunderbolt 3 Dock.jpg|thumb|[[Thunderbolt 3]] connector introduced by [[Intel]] in December 2015 multiplexes up to 4-lanes of [[PCIe 3.0]] and 8-lanes of [[DisplayPort]] 1.2 and can support an external [[docking station]] housing one or more expansion cards with enough bandwidth to drive a mid-range [[GPU]].]]

Expansion cards allow the capacitiescapabilities and interfaces of a computer system to be adjustedextended or supplemented in a way appropriate to the tasks it will perform. For example, a high-speed multi-channel data acquisition system would be of no use toin a personal computer used for bookkeeping, but might be a key part of a system used for industrial process control. Expansion cards can often be installed or removed in the field, allowing a degree of user customization for particular purposes. Some expansion cards take the form of "daughterboards" that plug into connectors on a supporting system board.

{{Main article|Bus (computing)#History}}

Even vacuumVacuum-tube based computers had modular construction, but individual functions for peripheral devices filled a cabinet, not just a printed circuit board. Processor, memory and I/O cards became feasible with the development of [[integrated circuit]]s.<ref>{{Cite Expansionweb cards|title=Eurotherm allowedParker aSSD processorLink systemHardware toL5341 {{!}} Automation Industrial |url=https://l5341.com/blog |access-date=2024-01-02 |website=l5341.com |language=en}}</ref> Expansion cards make processor besystems adaptedadaptable to the needs of the user, allowingby variationsmaking init thepossible typeto connect various types of devices connected, additionsincluding toI/O, additional memory, orand optional features to the central processor (such as a [[floating point unit]]) to the central processor. Minicomputers, starting with the [[PDP-8]], were made of multiple cards, allcommunicating powered bythrough, and communicatingpowered throughby, a passive [[backplane]].

IBM's [[Micro Channel architecture|MCA]] bus, developed for the PS/2 in 1987, was a competitor to ISA, also their design, but fell out of favor due to the ISA's industry-wide acceptance and IBM's licensing of MCA. EISA, the 32-bit extended version of ISA championed by [[Compaq]], was used on some PC motherboards until 1997, when Microsoft declared it a "legacy" subsystem in the [[PC 97]] industry white-paper. Proprietary local buses (q.v. Compaq) and then the [[VESA Local Bus]] Standard, were late 1980s expansion buses that were tied but not exclusive to the 80386 and 80486 [[Central processing unit|CPU]] bus.<ref>{{cite web|url=http://www.artofhacking.com/th99/m/U-Z/32626.htm |title=MB-54VP |archive-url = https://web.archive.org/web/20130516025559/http://www.artofhacking.com/th99/m/U-Z/32626.htm|website= ArtOfHacking.com |access-date=2012|archive-11-17date = 16 May 2013}}</ref><ref>{{cite web|url=http://www.artofhacking.com/th99/m/A-B/34897.htm |title=NX586 |website=ArtOfHacking.com |access-date=2012|archive-11date = 16 May 2013|archive-17url = https://web.archive.org/web/20130516063438/https://artofhacking.com/th99/m/A-B/34897.htm}}</ref><ref>{{cite web |url=http://www.artofhacking.com/th99/m/A-B/32775.htm |title=LEOPARD 486SLC2 REV. B |website=ArtOfHacking.com |access-date=2012-11-17 |archive-date=2014-10-17 |archive-url=https://web.archive.org/web/20141017222554/http://artofhacking.com/th99/m/A-B/32775.htm |url-status=dead }}</ref> The [[PC/104]] bus is an [[wikt:embedded|embedded]] bus that copies the ISA bus.

Intel launched their [[PCI bus]] chipsets along with the [[P5Pentium (microarchitectureoriginal)|P5]]-based [[Pentium (brand)|Pentium]] CPUs in 1993. The [[ConventionalPeripheral PCIComponent Interconnect|PCI]] bus was introduced in 1991 as a replacement for ISA. The standard (now at version 3.0) is found on PC motherboards to this day. The PCI standard supports bus bridging: as many as ten daisy -chained PCI buses have been tested. [[CardbusCardBus]], using the [[PC Card|PCMCIA]] connector, is a PCI format that attaches peripherals to the Host PCI Bus via PCI to PCI Bridge. Cardbus is being supplanted by [[ExpressCard]] format.

[[Intel]] introduced the [[Accelerated Graphics Port|AGP]] bus in 1997 as a dedicated video acceleration solution. AGP devices are logically attached to the PCI bus over a PCI-to-PCI bridge. Though termed a bus, AGP usually supports only a single card at a time ([[Legacy system|Legacy]] [[BIOS]] support issues). From 2005 [[PCI- Express]] has been replacing both PCI and AGP. This standard, approved{{whom2Like whom?|date=May 2013}} in 2004, implements the logical PCI protocol over a serial communication interface. PC/104(-Plus) or [[Mini PCI]] are often added for expansion on small form factor boards such as [[Mini-ITX]].

For their [[Tandy 1000|1000 EX]] and [[Tandy 1000|1000 HX]] models, Tandy Computer designed the PLUS expansion interface, an adaptation of the XT-bus supporting cards of a smaller form factor. Because it is electrically compatible with the XT bus (a.k.a. 8-bit ISA or XT-ISA), a passive adapter can be made to connect XT cards to a PLUS expansion connector. Another feature of PLUS cards is that they are stackable. Another bus that offered stackable expansion modules was the "sidecar" bus used by the IBM [[IBM PCjr|PCjr]]. This may have been electrically comparable to the XT bus; it most certainly had some similarities since both essentially exposed the 8088 CPU's address and data buses, with some buffering and latching, the addition of [[interrupt]]s and [[Direct memory access|DMA]] provided by Intel add-on chips, and a few system [[fault (technology)|fault]] detection lines (Power Good, Memory Check, I/O Channel Check). Again, PCjr sidecars are not technically expansion cards, but expansion modules, with the only difference being that the sidecar is an expansion card enclosed in a plastic box (with holes exposing the connectors).

Most other computer lines, including those from [[Apple Inc.]] ([[Apple II]], [[Macintosh]]), [[Tandy Corporation|Tandy]], [[Commodore International|Commodore]], [[Amiga]], and [[Atari, Inc.]], offered their own expansion buses. The [[Amiga]] used [[Amiga Zorro II|Zorro II]]. Apple used a proprietary system with seven 50-pin-slots for [[Apple II peripheral cards]], then later used theboth variations on [[Processor Direct Slot]] and [[NuBus]] for its Macintosh series until 1995, when they switched to a PCI Bus. Generally, PCI expansion cards will function on any [[Central processing unit|CPU]] platform if there is a software driver for that type. PCI video cards and other cards that contain a [[BIOS]] are problematic, although video cards conforming to VESA Standards may be used for secondary monitors. DEC Alpha, IBM PowerPC, and NEC MIPS workstations used PCI bus connectors.<ref>{{cite web|url=http://www.artofhacking.com/th99/index.htm#1|title=Motherboards|publisher=Artofhacking.com|access-date=2012-11-17}}</ref> Both Zorro II and NuBus were [[plug and play]], requiring no hardware configuration by the user.

Other computer buses were used for industrial control, instruments, and scientific systems. One specific example is HP-IB (or Hewlett Packard Interface Bus) which was ultimately standardized as [[IEEE-488]] (aka GPIB). Some ofwell-known thesehistorical standards wereinclude [[VMEbus]], [[STD Bus]], [[SBus]] (specific to Sun's SPARCStations), and numerous others.

===ExternalVideo expansiongame busesconsoles===

The primary purpose of an expansion card is to provide or expand on features not offered by the motherboard. For example, the original [[IBM Personal Computer|IBM PC]] did not have on-board graphics or hard drive capability. In that case, a graphics card and an [[ST-506]] hard disk controller card provided graphics capability and hard drive interface respectively. Some [[single-board computer]]s made no provision for expansion cards, and may only have provided IC sockets on the board for limited changes or customization. Since reliable multi-pin connectors are relatively costly, some mass-market systems such as [[home computer]]s had no expansion slots and instead used a card-edge connector at the edge of the main board, putting the costly matching socket into the cost of the peripheral device.

Depending on the [[Computer formForm factor (design)|form factor]] of the motherboard and [[computer case|case]], around one to seven expansion cards can be added to a computer system. 19 or more expansion cards can be installed in backplane systems. When many expansion cards are added to a system, total power consumption and heat dissipation become limiting factors. Some expansion cards take up more than one slot space. For example, many [[video card|graphics card]]s on the market as of 2010 are dual slot graphics cards, using the second slot as a place to put an active [[heat sink]] with a fan.

Some cards are "low-profile" cards, meaning that they are shorter than standard cards and will fit in a lower height computer chassis such as [[HTPC]] and [[Small form factor (desktop and motherboard)|SFF]]. (There is a "low profile PCI card" standard<ref name=":0">{{cite web|url=http://www.pcisig.com/specifications/conventional/conventional_pci/lowp_ecn.pdf |title=PCI Mechanical Working Group ECN: Low Profile PCI Card |publisher=Pcisig.com |access-date=2012-11-17}}</ref> that specifies a much smaller bracket and board area). The group of expansion cards that are used for external connectivity, such as [[network card|network]], [[Storage area network|SAN]] or [[modem]] cards, are commonly referred to as [[input/output]] cards (or I/O cards).

[[Image:Roland SCB-55 on Diamond MX300.jpg|thumb|A sound card with a MIDI daughterboard attached]]<!-- This section name is used as for the redirects [[Daughterboard]] and [[Daughter board]] -->[[Image:Inventec daughterboard LSI 1078.jpg|thumb|A daughterboard for [[Inventec]] server platform that acts as a RAID controller based on [[LSI Corporation|LSI]] 1078 chipset]]

A '''daughterboard''', '''daughtercard''', '''mezzanine board''' or '''piggyback board''' is an expansion card that attaches to a system directly.<ref> '' IEEE Std. 100 Authoritative Dictionary of IEEE Standards Terms, Seventh Edition'', IEEE, 2000,{{ISBN|0-7381-2601-2}}, page 284 </ref> Daughterboards often have plugs, sockets, pins or other attachments for other boards. Daughterboards often have only internal connections within a computer or other electronic devices, and usually access the motherboard directly rather than through a [[computer bus]]. Such boards are used to either improve various memory capacities of a computer, enable the computer to connect to certain kinds of networks that it previously could not connect to, or to allow for users to customize their computers for various purposes such as gaming. <ref>M.J. Memon, What Is A Daughterboard. Easy Tech Junkie. Sep. 24, 2011. https://www.easytechjunkie.com/what-is-a-daughterboard.htm. Accessed Oct. 15, 2021</ref>

Daughterboards are sometimes used in computers in order to allow for expansion cards to fit parallel to the motherboard, usually to maintain a small [[Computer form factor|form factor]]. This form are also called [[riser card]]s, or risers. Daughterboards are also sometimes used to expand the basic functionality of an electronic device, such as when a certain model has features added to it and is released as a new or separate model. Rather than redesigning the first model completely, a daughterboard may be added to a special connector on the main board. These usually fit on top of and parallel to the board, separated by [[Spacers and standoffs|spacers or standoffs]], and are sometimes called '''mezzanine cards''' due to being stacked like the [[mezzanine (architecture)|mezzanine]] of a [[theatre]]. [[Table-lookup synthesis|Wavetable]] cards ([[sample-based synthesis]] cards) are often [[wikt:mount|mounted]] on [[sound card]]s in this manner.

[[Image:Raspberry Pi 4B DVB TV μHat (angle).jpg|thumb|right|[[Raspberry PIPi]] 4B single-board computer with "TV Hat" card (for DVB-T/T2 television reception) attached.]]

the 172 pin High -Speed Mezzanine Card (HSMC);<ref>

IndustryPacks (VITA 4), the [[GreenSpring Computers#Mezzanine modules | GreenSpring Computers Mezzanine modules]];

*[[Server Management daughterboard]] (SMDC)

*Network Daughterboard (NDB). Commonly integrates: bus interfaces logic, [[Logical_link_controlLogical link control|LLC]], [[PHY]] and Magnetics onto a single board.

{{Main article|List of computer bus interfaces|List of device bit rates#Computer buses}}

* [[ConventionalPeripheral PCIComponent Interconnect]] (PCI)

* [[NuBus]] (Apple [[Mac (computer)|Macintosh]])