Extended Graphics Array

In this article, we are going to explore the topic of Extended Graphics Array and analyze its impact on different aspects of society. Extended Graphics Array is a topic that has generated great interest in recent times, and its relevance transcends borders and cultures. Throughout history, Extended Graphics Array has played a fundamental role in the evolution of society, and its influence remains significant today. Through detailed analysis, we will examine the various facets of Extended Graphics Array and its importance in areas such as politics, economics, culture, and everyday life. Additionally, we will explore the possible future implications of Extended Graphics Array and how it may impact the way we live and interact in the modern world.

"XGA" redirects here. For the video mode, see XGA (resolution).
Not to be confused with Enhanced Graphics Adapter or Extended Video Graphics Array.

Extended Graphics Array (XGA)
The IBM internal XGA logo, designed by Rand Paul
Release date1990 (1990)
History
Predecessor8514/A
SuccessorXGA-2

The eXtended Graphics Array (usually called XGA) is a graphics card manufactured by IBM and introduced for the IBM PS/2 line of personal computers in 1990 as a successor to the 8514/A. It supports, among other modes, a display resolution of 1024 × 768 pixels with 256 colors at 43.5 Hz (interlaced), or 640 × 480 at 60 Hz (non-interlaced) with up to 65,356 colors. The XGA-2 added an 800 × 600 65,356 color mode and 1024 × 768 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 1024 × 768, as IBM's VGA gave its name to 640 × 480, despite the IBM 8514/A and 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 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 a 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/A

  • Register-compatible with VGA
  • Adds a 132 column text mode and high color in 640 × 480
  • 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-2

IBM micro channel architecture XGA-2 graphics card
Another variant of XGA-2 graphics card

XGA-2 added support for non-interlaced 1024 × 768 and made 1MB VRAM standard. It had a programmable PLL circuit and pixel clocks up to 90MHz, enabling a 75 Hz refresh rate at 1024 × 768. The 800 × 600 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 capabilities

The XGA offered:

  • 640 × 480:
    • 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 80×34 characters
  • 1024 × 768:
    • graphics with 256 colors out of 262,144;
    • text with 85×38 or 146×51 characters

XGA-2 introduced:

  • 640 × 480 graphics with 256 colors out of 16.7M (24-bit palette);
  • 800 × 600 graphics with 65,536 colors at once;
  • 1024 × 768 graphics with 256 colors out of 16.7M

Later clone boards offered additional resolutions:

  • 640 × 480 graphics with 16.7M accessible colors at once (if it were possible with 640 × 480 pixels) (24-bit "true color");
  • 800 × 600 graphics with 16.7M colors at once;
  • 1280 × 1024 graphics with 65,536 and 16.7M colors at once

Clones

Wikimedia Commons has media related to 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 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 also

References

  1. ^ "XGA Logo". Paul Rand Foundation. Retrieved 25 September 2021.
  2. ^ a b c d e Jon Peddie (8 April 2019). "Famous Graphics Chips: IBM's XGA. The End of an Era". IEEE.org.
  3. ^ a b c d e f g h i j k l m Julio Sanchez; Maria P. Canton (2003). The PC Graphics Handbook. Boca Raton: CRC Press. ISBN 9780203010532.
  4. ^ 1634–1699: 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. 1700–1799: 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. 1800–present: Federal Reserve Bank of Minneapolis. "Consumer Price Index (estimate) 1800–". Retrieved 29 February 2024.

Further reading

  • 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.
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