VESA BIOS Extensions
The VESA BIOS Extension (VBE ) is a standard of the Video Electronics Standards Association ( VESA) for graphics cards in IBM - compatible personal computers (PCs).
They are usually implemented in a graphics card BIOS programming interface ( API) that provides the programs interrupts available in order to perform actions such as setting or querying of video modes as well as to address other functions supported by the hardware. Today's counterparts such as DirectX and OpenGL, however, are implemented at the operating system level.
Primarily, the VESA BIOS Extension was designed for 16 -bit applications under DOS. The frame buffer can however also be used by 32 -bit DPMI programs. With the introduction of VBE 2.0, it was possible graphics modes in 16-bit color ( 65,536 colors) with resolutions up to 1600 × 1200 pixels to use without implementing a targeted program-internal distinctions used for graphics hardware. Under DOS, there was previously no standardized interface for artwork that went beyond the VGA standard.
The current version of the standard is 3.0, which is backward compatible with the previous specification 2.0. It is supported by most modern nVidia graphics card, though it is hardly still used by application software, since nowadays the hardware is not directly addressed by the application ( see below). Already at that time the changes introduced by the standard 3.0 new features compared to the standard 2.0 were not used because there are already with the standard 2.0 all essential functions. The main innovation was the protected mode entry point, but in modern systems from design to technical reasons ( it would have to change to 20-bit protected mode take place ) is not used. In addition, independent APIs are used in desktop systems such as Microsoft Windows and Linux from the graphics card, which then implement appropriate functionality via manufacturer-specific drivers with well-defined interfaces. Furthermore, some of the modes are overwritten with WXGA resolutions especially in laptops because of its particular display sizes.
Most MS -DOS-based games between about 1993 and 1997 used the high-speed 16 -bit modes with low resolution such as 320 × 200 or 320 × 240, 640 × 480 later However, since not all graphics cards corresponding functionality in the BIOS of the card implemented with the introduction of this standard, there was universal add-on programs (about UniVBE, later Scitech Display Doctor ) as well as hardware-specific add-on programs (about S3VBE Core 2.0 for S3 graphics cards or TLIVESA for Tseng Labs graphics cards) that offered appropriate support. Hereby only in such cases it was possible that the modes could be used.
The default play date, however, under Linux a role: Are open source graphics drivers not available for certain graphics cards, so you can only use a driver that uses the functionality described here, the release of more than 640 × 480 pixels at more than 256 colors are used.
However, Corresponding standard plays a role only for the 2D representation. Standards for 3D acceleration are thus not covered or defined.
List of modes
With bit, the different colors can be displayed. This can in this case from a range of possible, different colors can be selected (see: RGB color space ).