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{{Short description|IBM graphics card and computer display standard}}
{{Redirect|XGA|the video mode|XGA (resolution)}}
{{Distinguish|Enhanced Graphics Adapter|Extended Video Graphics Array}}
{{use British English|date=February 2024}}
{{Infobox GPU
| name = Extended Graphics Array (XGA)
| image = [[File:XGA-1992.svg|100px|The IBM internal XGA logo, designed by Rand Paul<ref>{{cite web |title=XGA Logo |url=https://www.paulrand.design/work/XGA.html |publisher=Paul Rand Foundation |access-date=25 September 2021}}</ref>]]
| codename = 
| created = {{Start date and age|1990}}
| transistors = 
| entry = 
| midrange = 
| highend  = 
| enthusiast  = 
| openglversion = 
| d3dversion = 
| predecessor = [[IBM 8514|8514/A]]
| successor   = XGA-2
}}

The '''eXtended Graphics Array''' (usually called '''XGA''') is a [[Engineering:Graphics card|graphics card]] manufactured by [[Company:IBM|IBM]] and introduced for the IBM PS/2 line of personal computers in 1990 as a successor to the [[IBM 8514|8514/A]]. It supports, among other modes, a [[Engineering:Display resolution|display resolution]] of {{resx|1024x768}} [[Pixel|pixel]]s with 256 colors at 43.5&nbsp;[[Hertz|Hz]] ([[Interlaced video|interlaced]]), or {{resx|640x480}} at 60&nbsp;Hz ([[Engineering:Progressive scan|non-interlaced]]) with up to 65,536 colors.<ref name=peddie /><ref name=handbook /> The XGA-2 added an {{resx|800x600}} 65,536 color mode and {{resx|1024x768}} 60&nbsp;Hz non-interlaced.<ref name=peddie />

The XGA was introduced at $1095 with 512K [[VRAM]] and additional $350 for the 512{{nbsp}}KB memory expansion (equivalent to ${{Inflation|US|1095|1990|r=-2}} and ${{Inflation|US|350|1990|r=-1}}, respectively, in {{Inflation/year|US}}).{{Inflation/fn|US}}<ref name=peddie>{{cite web|title=Famous Graphics Chips: IBM's XGA. The End of an Era|url=https://www.computer.org/publications/tech-news/chasing-pixels/famous-graphics-chips-ibms-xga|publisher=IEEE.org|date=8 April 2019|author=Jon Peddie}}</ref> As with the 8514/A, XGA required a [[Engineering:Micro Channel architecture|Micro Channel architecture]] bus at a time when [[Engineering:Industry Standard Architecture|ISA]] systems were standard, however due to more extensive documentation and licensing ISA clones of XGA were made. XGA was integrated into the motherboard of the PS/2 Model 95 XP 486.<ref name=handbook>{{cite book|title=The PC Graphics Handbook|author1=Julio Sanchez|author2=Maria P. Canton|url=https://books.google.com/books?id=gZ5SDTpMR-MC|publisher=CRC Press|location=Boca Raton|year=2003|isbn=9780203010532}}</ref>

An improved version called XGA-2 was introduced in 1992 at $360, worth ${{Inflation|US|360|1992|r=-1}} in {{Inflation/year|US}} dollars.

XGA gives its name to the resolution {{resx|1024x768}}, as IBM's [[Video Graphics Array|VGA]] gave its name to {{resx|640x480}}, despite the IBM 8514/A and [[Engineering:Professional Graphics Controller|PGC]] cards respectively supporting those resolutions prior to the eponyms.

==Features==
The 8514 had used a standardised [[API]] called the "Adapter Interface" or AI. This interface is also used by XGA, IBM Image Adapter/A, and clones of the 8514/A and XGA such as the [[Company:ATI Technologies|ATI Technologies]] ''Mach 32'' and [[Company:8x8|IIT]] ''AGX''. The interface allows computer software to offload common [[2D computer graphics|2D-drawing]] operations (line-draw, color-fill, and block copies via a [[Engineering:Blitter|blitter]]) onto the hardware. This frees the host CPU for other tasks, and greatly improves the speed of redrawing a graphics visual (such as a pie-chart or CAD-illustration).<ref name=peddie /><ref name=handbook /> Hardware-level documentation of the XGA was also made, which had not been available for the 8514/A.<ref name=handbook />

XGA introduced a 64x64 hardware [[Sprite (computer graphics)|sprite]] which was typically used for the mouse pointer.

===Differences from 8514/A===
*[[Hardware register|Register]]-compatible with VGA<ref name=handbook />
*Adds a 132 column text mode and high color in {{resx|640x480}}<ref name=handbook />
*Requires a minimum of 80386 host CPU<ref name=handbook />
*Provides a 3-dimensional drawing space called a "bitmap" which may reside anywhere in system memory<ref name=handbook />
*Adds a sprite for a hardware cursor<ref name=handbook />
*The Adapter Interface driver is moved to a .SYS file instead of [[Terminate-and-stay-resident program|TSR]] program<ref name=handbook />
*Provisions made for [[Computer multitasking|multitasking]] environment<ref name=handbook />
*XGA can act as bus master and access system memory directly<ref name=handbook />
*Hardware level documentation has been provided by IBM<ref name=handbook />

===XGA-2===
[[File:MCA IBM XGA-2.jpg|thumb|IBM micro channel architecture XGA-2 graphics card]]
[[File:IBM MCA XGA card front.jpg|thumb|Another variant of XGA-2 graphics card]]
XGA-2 added support for non-interlaced {{resx|1024x768}} and made 1MB VRAM standard. It had a programmable PLL circuit and pixel clocks up to 90&nbsp;MHz, enabling a 75&nbsp;Hz refresh rate at {{resx|1024x768}}. The {{resx|800x600}} resolution was added with 16&nbsp;bit high color support. The [[Digital-to-analog converter|DAC]] was increased to 8 bits per channel, and the accelerated functions were enabled at 16&nbsp;bit color depth. Faster VRAM also improved performance.<ref name=peddie />

==Output capabilities==
The XGA offered:
*'''{{resx|640×480}}''':
**graphics mode with 256 colors at once (8-bit) out of 262,144 ([[List of monochrome and RGB color formats#18-bit RGB|18-bit RGB]] palette);
**graphics with 65,536 colors at once (16-bit "high color");
**text mode with 80×34 characters
*'''{{resx|1024×768}}''':
**graphics with 256 colors out of 262,144;
**text with 85×38 or 146×51 characters

XGA-2 introduced:
*'''{{resx|640×480}}''' graphics with 256 colors out of ''16.7M (24-bit palette)'';
*'''''{{resx|800×600}}''''' graphics with 65,536 colors at once;
*'''{{resx|1024×768}}''' graphics with 256 colors out of ''16.7M''

Later clone boards offered additional resolutions:
*'''{{resx|640×480}}''' graphics with ''16.7M'' accessible colors at once (if it were possible with {{resx|640×480}} pixels) ''([[Engineering:Color depth#True color (24-bit)|24-bit]] "true color")'';
*'''{{resx|800×600}}''' graphics with ''16.7M'' colors at once;
*'''''{{resx|1280×1024}}''''' graphics with 65,536 and 16.7M colors at once

==Clones==
{{Commons|XGA}}
Unlike with the 8514/A, IBM fully documented the hardware interface to XGA. Further, IBM licensed the XGA design to SGS-Thomson (inmos) and [[Company:Intel|Intel]]. The IIT AGX014 was largely compatible with the XGA-2 and offered some enhancements.

The [[Organization:Video Electronics Standards Association|VESA]] Group introduced a common standardized way to access features like hardware cursors, Bit Block transfers ([[Bit blit|Bit Blt]]), off screen [[Sprite (computer graphics)|sprites]], hardware panning, drawing and other functions with [[VESA BIOS Extensions#VBE/accelerator functions (VBE/AF) (August 1996)|VBE/accelerator functions (VBE/AF)]] in August 1996. This, along with standardised [[Device driver|device driver]]s for operating systems such as [[Software:Microsoft Windows|Microsoft Windows]], eliminated the need for a hardware standard for graphics.

==See also==
*[[Engineering:List of IBM products|List of IBM products]]
*List of defunct graphics chips and card companies

==References==
{{Reflist}}

==Further reading==
*{{cite book|title=Power Programming the IBM XGA|author=Jake Richter|year=1992|publisher=MIS Press|isbn=9781558281271}}
*{{cite book|title=Programmer's Guide to the EGA, VGA, and Super VGA Cards|author=Richard F. Ferraro|year=1994|isbn=9780201624908|publisher=Addison-Wesley}}

{{Computer display standard}}
{{IBM personal computers}}

[[Category:Computer display standards]]

{{Sourceattribution|Extended Graphics Array}}