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VESA BIOS Extensions
VESA BIOS Extensions (VBE) is a VESA standard, currently at version 3, that defines the interface that can be used by software to access compliant video boards at high resolutions and bit depths. This is opposed to the "traditional" INT 10h BIOS calls, which are limited to resolutions of 640×480 pixels with 16 colour (4-bit) depth or less. VBE is made available through the video card's BIOS, which installs some interrupt vectors that point to itself during boot up.
Most newer cards implement the more capable VBE 3.0 standard. Older versions of VBE provide only a real mode interface, which cannot be used without a significant performance penalty from within protected mode operating systems. Consequently, the VBE standard has almost never been used for writing a video card's drivers; each vendor has thus had to invent a proprietary protocol for communicating with its own video card. Despite this, it is common that a driver thunk out to the real mode interrupt in order to initialize screen modes and gain direct access to a card's linear frame buffer, because these tasks would otherwise require handling many hundreds of proprietary variations that exist from card to card.
In EFI 1.x systems, the INT 10H and the VESA BIOS Extensions (VBE) are replaced by the EFI UGA protocol. In widely used UEFI 2.x systems, the INT 10H and the VBE are replaced by the UEFI GOP.
Initially, the need for standardization came from problems with accessing higher than standard VGA resolutions and color-depth modes on Super VGA graphic cards. Using those modes with cards produced by different manufacturers required drivers, which were available only for a few programs (mainly AutoCAD and Windows), while majority of the software was still made for DOS. The VBE allowed developers of DOS real-mode applications to use the new graphic modes in a common, standardized way.
VBE 1.0 (VS891001) was defined in 1989. VBE 1.1 (VS900602) was defined in 1990. VBE 1.2 (VS911022) was defined in 1991. These versions of VBE require real mode to work.
VBE defines several new functions called through INT 10H. The function numbering start with AX=4F00, or (AH=4F, AL=00), for Function 00h. 00h to 05h were defined in VBE 1.0, 06h and 07h in 1.1, and 08h in 1.2.
This standard provides the primary functionality of the VESA BIOS Extensions. It allows applications to determine the capabilities of the graphics card and provides the ability to set the display modes that are found. VBE 2.0 adds some new features above the prior VBE 1.2 standard including linear framebuffer access and protected mode banking. Some of the VBE Core 2.0 features include:
A superset of the VBE 2.0 standard. This standard adds refresh rate control, facilities for stereo glasses, improved multi-buffering and other functions to the VBE 2.0 standard.
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VESA BIOS Extensions AI simulator
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VESA BIOS Extensions
VESA BIOS Extensions (VBE) is a VESA standard, currently at version 3, that defines the interface that can be used by software to access compliant video boards at high resolutions and bit depths. This is opposed to the "traditional" INT 10h BIOS calls, which are limited to resolutions of 640×480 pixels with 16 colour (4-bit) depth or less. VBE is made available through the video card's BIOS, which installs some interrupt vectors that point to itself during boot up.
Most newer cards implement the more capable VBE 3.0 standard. Older versions of VBE provide only a real mode interface, which cannot be used without a significant performance penalty from within protected mode operating systems. Consequently, the VBE standard has almost never been used for writing a video card's drivers; each vendor has thus had to invent a proprietary protocol for communicating with its own video card. Despite this, it is common that a driver thunk out to the real mode interrupt in order to initialize screen modes and gain direct access to a card's linear frame buffer, because these tasks would otherwise require handling many hundreds of proprietary variations that exist from card to card.
In EFI 1.x systems, the INT 10H and the VESA BIOS Extensions (VBE) are replaced by the EFI UGA protocol. In widely used UEFI 2.x systems, the INT 10H and the VBE are replaced by the UEFI GOP.
Initially, the need for standardization came from problems with accessing higher than standard VGA resolutions and color-depth modes on Super VGA graphic cards. Using those modes with cards produced by different manufacturers required drivers, which were available only for a few programs (mainly AutoCAD and Windows), while majority of the software was still made for DOS. The VBE allowed developers of DOS real-mode applications to use the new graphic modes in a common, standardized way.
VBE 1.0 (VS891001) was defined in 1989. VBE 1.1 (VS900602) was defined in 1990. VBE 1.2 (VS911022) was defined in 1991. These versions of VBE require real mode to work.
VBE defines several new functions called through INT 10H. The function numbering start with AX=4F00, or (AH=4F, AL=00), for Function 00h. 00h to 05h were defined in VBE 1.0, 06h and 07h in 1.1, and 08h in 1.2.
This standard provides the primary functionality of the VESA BIOS Extensions. It allows applications to determine the capabilities of the graphics card and provides the ability to set the display modes that are found. VBE 2.0 adds some new features above the prior VBE 1.2 standard including linear framebuffer access and protected mode banking. Some of the VBE Core 2.0 features include:
A superset of the VBE 2.0 standard. This standard adds refresh rate control, facilities for stereo glasses, improved multi-buffering and other functions to the VBE 2.0 standard.