Video Graphics Array (VGA)
IBM introduced VGA about the same time as the 8514/A and MCGA made their appearances. VGA was slightly less capable than the 8514/a, but it was cheaper and operated on the standard ISA bus. Due to the resistance towards licensing that IBM was facing over the MCA bus debacle, more and more third party vendors began to produce and market several different implementations of VGA type display adapters, resulting in greatly reduced prices. VGA was an analog output display, which gave it a much higher color palette than the earlier EGA and CGA. However, all was not well, since IBM dropped its VGA support in favor of the new "XGA" adaptor they had developed. Third party companies were not interested in building cards based on the XGA adapter spec, and instead continued to build and develop their VGA technology. The problem was that since IBM was no longer interested in developing VGA technology, there were no standardized guidelines.
VGA and XGA both used this connector
With the release of XGA, third party manufacturers all turned away from IBM and began to develop their own enhanced version of the VGA standard, which became loosely known as "Super VGA", even though no actual standard existed. SVGA used the same 15-pin header, and virtually all "SVGA" adapters were fully VGA compatible, but it was with the advancements beyond the predefined VGA standard that software compatibility problems began to rear up.
VESA (Video Electronics Standards Association), an organization made up of a membership of several companies, recognized the problems that were popping up due to splintering VGA technology. Programming software to support each and every VGA display adapter was virtually impossible since the software developer was forced to write code to support each adapter directly into their software. This process was not only extremely time consuming, but also expensive. As such, software developers would pick and choose what video cards to support, and which to not support. If you did not have a video card that was supported by the software you wanted to run, you were forced to buy one that was supported in order to use that software.
VESA released a specification for the "VESA BIOS Extension", which was a standardized set of guidelines created to assure that all software could be made to run properly on ALL SVGA video cards that included the VESA extensions. Initially, the VESA extensions were loaded into the system in the form of a device driver, which was loaded from the system startup files.
The VESA BIOS extension was a good start in getting compatibility back into line, but many end users still experienced problems because they were not aware that a VESA driver had to be loaded before they could run some graphics programs. The incorporation of the VESA extension directly into the video BIOS solved this issue, since the end user needed to take no action besides starting the program.
The VESA SVGA standard covers virtually every resolution and color depth up to 1280X1024, and has been since extended to cover even higher resolutions and color depths. Other standards for legacy fallbacks (to assure compatibility with older hardware), and for the new Digital Flat panel displays have been introduced. All VESA standards serve to ensure cross compatibility between software and hardware.