VBE is made available through the video adapter's BIOS, which installs interrupt vectors pointing at itself during system startup. Unfortunately, the older versions of VBE (those bundled with the vast majority of existing video boards) supported only a real mode interface, which couldn't be used without a significant performance penalty from within protected mode operating systems, such as Windows 95 or Linux. This meant that the VBE standard was almost never used for writing video-drivers, and each video board vendor had to invent a proprietory protocol for communicating with their own board(s). Moreover, VBE does not include tools to control display refresh rate to prevent flicker, a severe problem at high resolutions.
See also: