Guida ai display, parte 2

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.