Extended Graphics Array

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Graphics card of the type IBM XGA-2

Extended Graphics Array (abbreviation XGA ) denotes both a type of graphics card that was introduced by IBM in October 1990 for the IBM PS / 2 series of computers ( XGA Display Adapter / A ), as well as the associated graphics standard.

In addition to the original XGA Display Adapter / A , IBM also manufactured the similar XGA-2 Display Adapter / A , which enabled a higher achievable color depth .

technology

The XGA hardware was backwards compatible with the VGA graphics standard , the 8514 / A driver interface and also offered a 132-column text mode (40 and 80 were common). The maximum image resolution was 1024 × 768 pixels, the maximum color depth 16 bit (65,536 colors). Although these maximum values ​​could not be reached at the same time for reasons of memory, with an expansion of the graphics memory 256 colors at 1024 × 768 pixels and 65,536 colors at 800 × 600 pixels were possible. The frame buffer is accessed directly at XGA graphics cards so that their hardware theoretically any combination of resolution and color depth can provide, the graphics memory as long as sufficient to do so. Unlike the normal VGA and analogous to the 8514 / A, they have hardware-accelerated drawing commands and cursor display.

Whereabouts

The XGA standard was unable to establish itself in the area of IBM PC-compatible computers . The SVGA -compatible graphics cards from third-party manufacturers, which appeared a little later, were comparably flexible thanks to VESA compatibility, achieved similar performance and were available for all bus architectures. The model for these forefathers of modern PC graphics hardware, however, were the characteristics of the XGA standard.

Other meanings

The name "XGA", based on this graphics standard, was also used in a wider sense for an image mode within the VESA 2.0 standard, which corresponds to the maximum image resolution (1024 × 768 pixels) of the XGA standard. In addition, VESA 2.0 contains the SXGA ( Super XGA) image mode with 1280 × 1024 pixels, which apart from the name has nothing to do with the original standard. Similar marketing names for certain image modes that emerged in the 2000s and also contain the abbreviation XGA are not related to the XGA standard.

literature

  • IBM: Video Subsystem. In: IBM PS / 2 Hardware Interface Technical Reference, May 1992 edition ( PDF; 1.7 MB )

Web links

Individual evidence

  1. ↑ IBM: IBM Announcement Letter Number 190-182: IBM XGA Display Adapter / A. October 30, 1990.
  2. ↑ a b IBM: Video Subsystem. In: IBM PS / 2 Hardware Interface Technical Reference, May 1992 edition.
  3. ↑ Louis Ohland: Technical information on the XGA display adapter (English)
  4. ↑ Louis Ohland: Technical information on the XGA-2 display adapter (English)