XGA vs VGA
XGA, or the Extended Graphics Array, is IBM’s official replacement of the Video Graphics Array, or VGA. Although XGA is supposed to be a replacement of SVGA, it is considered to be under the SVGA umbrella, as it is only a subset of the SVGA capabilities. Comparing VGA to XGA, there is one very distinct difference, and it is in the resolution. VGA has a maximum resolution of 640 pixels by 480 pixels, while XGA is widely affiliated to the 1024×768 resolution that has become the standard today, especially in web pages. In reality though, XGA added 1024×768 and 800×600 to the existing resolutions of VGA. The latter resolution is not commonly affiliated to XGA, as it is already existent in SVGA.
Aside from the extended resolutions, XGA adds little else to the already established VGA standard. This is due, in part, to the need for backwards compatibility of the hardware that was already available on the market at the time of it’s introduction. The electrical characteristics of XGA follows those of VGA, and all XGA adapters are capable of working within VGA limits if the monitor that is attached to it is old, and is only capable of VGA resolutions. Backwards compatibility is the reason behind the consistent use of the DE-9 connector, established in VGA, to all other video specifications, and it is still present in most digital displays despite the introduction of DVI.
VGA has become the lowest common denominator for all display adapter manufacturers, due to its maturity. Most of the SVGA adapters, including XGA, need to load drivers in order to function properly. This is why adapters initially go into VGA mode to provide an interface where users can deal with problems before the computer has loaded the appropriate drivers.
In terms of hardware, XGA obviously requires better hardware than the older VGA. This is because the memory and processing power needed by each pixel in the display is more or less constant. Since XGA has more than twice the number of pixels compared to VGA, you can easily see why XGA requires better hardware. This is apart from the more complex drawing commands that is offloaded from the host processor and into the GPU.
Summary:
1. XGA offers much higher resolutions compared to VGA.
2. XGA still follows some of the standards established by IBM, in VGA.
3. VGA is supported by all adapters. XGA is supported by a few.
4. XGA requires better hardware compared to VGA.