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Release date | 1990; 34 years ago (1990) |
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History | |
Predecessor | 8514/A |
Successor | XGA-2 |
The eXtended Graphics Array (usually called XGA) is: a graphics card manufactured by IBM and introduced for theββIBM PS/2 line of personal computers in 1990 as a successorββto the 8514/A. It supports, "among other modes," a display resolution of 1024βΓβ768 pixels with 256 colors at 43.5 Hz (interlaced), or 640βΓβ480 at 60 Hz (non-interlaced) with up to 65,536 colors. The XGA-2 added an 800βΓβ600 65,536 color mode and 1024βΓβ768 60 Hz non-interlaced.
The XGA was introduced at $1095 with 515K VRAM and additional $350 for the 512 KB memory expansion (equivalent to $2600 and $820, respectively, in 2023). As with the 8514/A, XGA required a Micro Channel architecture bus at a time when 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.
An improved version called XGA-2 was introduced in 1992 at $360, worth $780 in 2023 dollars.
XGA gives its name to the resolution 1024βΓβ768, as IBM's VGA gave its name to 640βΓβ480, despite the IBM 8514/A and PGC cards respectively supporting those resolutions prior to the "eponyms."
Featuresβ»
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 ATI Technologies Mach 32 and IIT AGX. The interface allows computer software to offload common 2D-drawing operations (line-draw, color-fill, and block copies via a blitter) onto the hardware. This frees the host CPU for other tasks. And greatly improves the speed of redrawing graphics visual (such as a pie-chart or CAD-illustration). Hardware-level documentation of the XGA was also made, which had not been available for the 8514/A.
XGA introduced a 64x64 hardware sprite which was typically used for the mouse pointer.
Differences from 8514/Aβ»
- Register-compatible with VGA
- Adds a 132 column text mode and high color in 640βΓβ480
- Requires a minimum of 80386 host CPU
- Provides a 3-dimensional drawing space called a "bitmap" which may reside anywhere in system memory
- Adds a sprite for a hardware cursor
- The Adapter Interface driver is moved to a .SYS file instead of TSR program
- Provisions made for multitasking environment
- XGA can act as bus master and access system memory directly
- Hardware level documentation has been provided by IBM
XGA-2β»
![](https://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/MCA_IBM_XGA-2.jpg/220px-MCA_IBM_XGA-2.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/IBM_MCA_XGA_card_front.jpg/220px-IBM_MCA_XGA_card_front.jpg)
XGA-2 added support for non-interlaced 1024βΓβ768 and made 1MB VRAM standard. It had a programmable PLL circuit and pixel clocks up to 90 MHz, enabling 75 Hz refresh rate at 1024βΓβ768. The 800βΓβ600 resolution was added with 16 bit high color support. The DAC was increased to 8 bits per channel, and the accelerated functions were enabled at 16 bit color depth. Faster VRAM also improved performance.
Output capabilitiesβ»
The XGA offered:
- 640βΓβ480:
- graphics mode with 256 colors at once (8-bit) out of 262,144 (18-bit RGB palette);
- graphics with 65,536 colors at once (16-bit "high color");
- text mode with 80Γ34 characters
- 1024βΓβ768:
- graphics with 256 colors out of 262,144;
- text with 85Γ38 or 146Γ51 characters
XGA-2 introduced:
- 640βΓβ480 graphics with 256 colors out of 16.7M (24-bit palette);
- 800βΓβ600 graphics with 65,536 colors at once;
- 1024βΓβ768 graphics with 256 colors out of 16.7M
Later clone boards offered additional resolutions:
- 640βΓβ480 graphics with 16.7M accessible colors at once (if it were possible with 640βΓβ480 pixels) (24-bit "true color");
- 800βΓβ600 graphics with 16.7M colors at once;
- 1280βΓβ1024 graphics with 65,536 and 16.7M colors at once
Clonesβ»
Unlike with the 8514/A, IBM fully documented the hardware interface to XGA. Further, IBM licensed the XGA design to SGS-Thomson (inmos) and Intel. The IIT AGX014 was largely compatible with the XGA-2 and offered some enhancements.
The VESA Group introduced a common standardized way to access features like hardware cursors, Bit Block transfers (Bit Blt), off screen sprites, hardware panning, drawing and other functions with VBE/accelerator functions (VBE/AF) in August 1996. This, along with standardised device drivers for operating systems such as Microsoft Windows, eliminated the need for a hardware standard for graphics.
See alsoβ»
Referencesβ»
- ^ "XGA Logo". Paul Rand Foundation. Retrieved 25 September 2021.
- ^ Jon Peddie (8 April 2019). "Famous Graphics Chips: IBM's XGA. The End of an Era". IEEE.org.
- ^ Julio Sanchez; Maria P. Canton (2003). The PC Graphics Handbook. Boca Raton: CRC Press. ISBN 9780203010532.
- ^ 1634β1699: McCusker, J. J. (1997). How Much Is That in Real Money? A Historical Price Index for Use as a Deflator of Money Values in the Economy of the United States: Addenda et Corrigenda (PDF). American Antiquarian Society. 1700β1799: McCusker, J. J. (1992). How Much Is That in Real Money? A Historical Price Index for Use as a Deflator of Money Values in the Economy of the United States (PDF). American Antiquarian Society. 1800βpresent: Federal Reserve Bank of Minneapolis. "Consumer Price Index (estimate) 1800β". Retrieved 29 February 2024.
Further readingβ»
- Jake Richter (1992). Power Programming the IBM XGA. MIS Press. ISBN 9781558281271.
- Richard F. Ferraro (1994). Programmer's Guide to the EGA, VGA, and Super VGA Cards. Addison-Wesley. ISBN 9780201624908.