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 10hBIOS 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.[1][2]
Standards
Early VBE
VBE 1.0 (VS891001) was defined in 1989.[3] VBE 1.1 (VS900602) was defined in 1990. VBE 1.2 (VS911022) was defined in 1991.[4] 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.
VESA BIOS Extensions (VBE core) 2.0 (November 1994)
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[5] features include:
Linear framebuffer access
Enables direct framebuffer access in protected mode as one large area of memory instead of less efficient smaller chunks.
Protected mode banking
Allows access to the framebuffer from protected mode without "thunking" down to real mode. This is implemented using a new Function 0Ah.
Allows higher performance animation to provide for smooth animation for computer games and other high performance graphics programs.
Super VGA virtual screens
Allows software to set up virtual display resolutions, larger than the actual displayed resolution, and smoothly scroll or pan around the larger image.
Industry standard 16-bit and 24-bit graphics modes for resolutions from 320×200 up to 1600×1200.
VESA BIOS Extensions (VBE core) 3.0 (September 1998)
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.
Allows high speed applications to perform multi-buffering with less screen flickering and without having to wait for the graphics controller.
Refresh rate control using GTF timings
This allows applications and operating system utilities to change the refresh rate in a standard way on all VBE 3.0 graphics controllers. Important for stereo applications, since when stereo is enabled, the user's effective refresh rate is cut in half.
Stereo page flipping
When viewing an application using stereo glasses, software needs to page flip twice as often as normal, because it needs to generate separate images for each eye. This new feature allows stereo compatible software to display properly.
Hardware stereo sync
Allows stereo software to determine if there is a connector for stereo glasses on the user's graphics card.
A new "Protected Mode Entry Point" was added as an alternative to Function 0Ah.
VBE/accelerator functions (VBE/AF) (August 1996)
VBE/AF provides a low-level, standard interface to common acceleration functions available on most hardware. Some of the functions defined in the standard are access to hardware cursors, Bit Block Transfers (Bit Blt), off screen sprites, hardware panning, drawing and other functions. It is defined to work under 32-bit protected mode. Despite the widespread adoption of VBE Core, very few devices support VBE/AF. The FreeBE/AF project implements free third-party VBE/AF drivers for certain graphics cards.
Supplemental specifications
Supplemental specifications provides device independent interface between application software and Super VGA hardware. Function numbers are assigned by VESA Software Standards Committee (SSC).
DPMS is a hardware standard that allows graphics cards to communicate with DPMS-compliant monitors via a special signalling system that can be used with existing graphics controllers and monitor cables. This signalling system allows the graphics card to tell the monitor to go into a number of different power management or power saving states, which effectively allow the monitor to turn itself off when it is not in use.
Flat panel interface extensions (FP)
Allows access to special features in flat panel controllers.
Audio interface extensions (AI)
Provides standard to audio services.
Currently (version 1.00), the VBE/AI specification defines three device classes: WAVE, MIDI, and VOLUME. Device types not covered:
The Display Data Channel or DDC is a digital connection between a computer display and a graphics adapter that allows the display to communicate its specifications to the adapter. The standard was created by VESA.
Serial Control Interface (SCI)
Provides hardware independent means for operating system and application to read and write data over I²C serial control interface.
VBE mode numbers
Although mode number is a 16-bit value, the optional VBE mode numbers are 14 bits wide. Bit 15 is used by VGA BIOS as a flag to clear or preserve display memory.
VBE defined mode numbers as follows:
Bit
Meaning
0–8
Mode numbers. If bit 8 is 1, it is a VESA defined VBE mode.
9-10
Reserved for expansion. Must be set to 0.
11
Refresh rate control Select. If set to 1, use user specified CRTC values for refresh rate, otherwise use BIOS default refresh rate.
12–13
Reserved for VBE/AF. Must be set to 0.
14
Linear/Flat Frame Buffer Select. If set to 1, use linear frame buffer, otherwise use banked frame buffer.
15
Preserve Display Memory Select. If set to 1, preserve display memory, otherwise clear display memory.
Starting in VBE/Core 2.0, VESA no longer defines new VESA mode numbers and no longer requires a device to implement the old numbers. To properly detect information of a screen mode, use Function 01h - Return VBE Mode Information.
Mode 81FFh is a special video mode designed to preserve current memory contents and give access to the entire video memory.
Modes defined by VESA
Beginning with the VBE 2.0 standard, no new modes will be defined by VESA, and old modes are no longer mandatory. The use of defined modes should be considered deprecated: modern video cards may or may not use these mode numbers (even though most do for backward compatibility), and modern software should not use them. The correct way for software to discover available display modes is to obtain a list of modes (using "Function 00h - Return VBE Controller Information") and then to check each mode (using "Function 01h: Return VBE Mode Information") until it finds the mode/s it requires.[citation needed]
Graphics modes
320×200
640×400
640×480
800×600
1024×768
1280×1024
16-color palette
258 (0102h), 106 (6Ah)
260 (0104h)
262 (0106h)
256-color palette
256 (0100h)
257 (0101h)
259 (0103h)
261 (0105h)
263 (0107h)
15-bit (5:5:5)
269 (010Dh)
272 (0110h)
275 (0113h)
278 (0116h)
281 (0119h)
16-bit (5:6:5)
270 (010Eh)
273 (0111h)
276 (0114h)
279 (0117h)
282 (011Ah)
24-bit (8:8:8)
271 (010Fh)
274 (0112h)
277 (0115h)
280 (0118h)
283 (011Bh)
Modes 264–268 are text modes. 264 (0108h) is 80 columns × 60 rows (80×60), 265 (0109h) is 132×25, 266 (010Ah) is 132×43, 267 (010Bh) is 132×50 and 268 (010Ch) is 132×60.
Text modes
Columns
Rows
80
132
25
265 (0109h)
43
266 (010Ah)
50
267 (010Bh)
60
264 (0108h)
268 (010Ch)
Other commonly available graphics modes
The table below combines the modes defined by VESA (the values denoted in black) along with modes commonly used, but which may not work on all graphics cards as they are not defined by any standard (denoted in red).
A few tools have been written to detect VBE modes available on a system. They generally work by invoking Function 01h, which is more reliable than assuming a table of extended modes as it's part of the device's self-documentation.
hwinfo is the hardware detection tool used in SuSE Linux and in some other Linux distributions.[10] Running hwinfo --framebuffer reports graphics information, including VESA modes on a "Mode" line.
mdt is a Linux or DOS tool that uses VESA BIOS functions to read monitor data.[11]
The Linux Real Mode Interface (LRMI) has a vbetest program that prints out VESA info.
SciTech Software had a unrelated vbetest for DOS that dates back to 1994.
The x86 "PC" version GNU GRUB 2 has a vbeinfo command for printing out available video modes and vbetest for trying a specific mode. They use a built-in table instead of Function 01h. For other platforms, including x86 EFI, they are replaced by the more generic videoinfo and videotest.
Linux video mode numbers
The Linux kernel allows the user to select the VESA mode at boot time by passing a code in memory to the kernel. The LILO boot loader passes this code based on a "vga" parameter in its configuration file. It takes the form 'vga=XXX', where XXX is the decimal value, or 'vga=0xHHH', where HHH is the hexadecimal value. However, the 'vga=' boot loader parameter does not directly accept VESA video mode numbers; rather, the Linux video mode number is the VESA number plus 512 (in the case of the decimal representation) or plus 0x200 (in the case of the hexadecimal representation). For example, the defined VESA value of 257 (0x101), representing 640x480 and 256 colours, has an equivalent Linux video mode value of 769 (0x301).[12]
As indicated earlier, the VESA standard defines a limited set of modes; in particular, none above 1280×1024 are covered and, instead, their implementation is completely optional for graphics adapter manufacturers. As vendors are free to utilize whatever additional values they please, this means that, in the table below, the modes denoted in red (and expressed in decimal form) may not apply to every graphics adapter!
320×200
640×400
640×480
800×500
800×600
896×672
1024×640
1024×768
1152×720
1280×1,024
1400×1,050
1440×900
1600×1,200
1920×1080
1920×1200
16 colors
770 0302h
772 0304h
774 0306h
256 colors
768 0300h
769 0301h
879 036Fh
771 0303h
815 032Fh
874 036Ah
773 0305h
869
775 0307h
835
864
796
893
15-bit (5:5:5)
781 030Dh
801 0321h
784 0310h
880 0370h
787 0313h
816 0330h
875 036Bh
790 0316h
870
793 0319h
865
797
16-bit (5:6:5)
782 030Eh
802 0322h
785 0311h
881 0371h
788 0314h
817 0331h
876 036Ch
791 0317h
871
794 031Ah
837
866
798
24-bit (8:8:8)
783 030Fh
803 0323h
786 0312h
882 0372h
789 0315h
818 0332h
877 036Dh
792 0318h
872
795 031Bh
838
867
799
32-bit (8:8:8)1
804
809
883
814
819
878
824
873
829
868
834
980 03D4h
1: 32-bit is really (8:8:8:8), but the final 8-bit number is an "empty" alpha channel. It is otherwise equal to 24-bit colour. Many GPUs use 32-bit colour mode instead of 24-bit mode merely for faster video memory access through 32-bit memory alignment.
VGA=864 [ 352 (0160h)] also appears to select 1280×800 (8-bit) for various laptops' displays.
VGA=834 [ 322 (0142h)] is 1400×1050
Modes available in Parallels
The VESA BIOS emulation in the Parallels virtual machine has a different set of non-standard VESA modes. As of build 3214, LRMI vbetest reveals these modes:
640×400
640×480
720×480
800×500
800×600
896×672
1024×640
1024×768
1152×720
1280×1,024
1440×900
1600×1,200
256 color palette
256 (0100h)
257 (0101h)
367 (016Fh)
364 (016Ch)
259 (0103h)
297 (0129h)
358 (0166h)
261 (0105h)
355 (0163h)
263 (0107h)
352 (0160h)
284 (011Ch)
15-bit (5:5:5)
272 (0110h)
275 (0113h)
278 (0116h)
281 (0119h)
285 (011Dh)
16-bit (5:6:5)
289 (0121h)
273 (0111h)
368 (0170h)
365 (016Dh)
276 (0114h)
298 (012Ah)
359 (0167h)
279 (0117h)
356 (0164h)
282 (011Ah)
353 (0161h)
286 (011Eh)
24-bit (8:8:8)
290 (0122h)
274 (0112h)
369 (0171h)
366 (016Eh)
277 (0115h)
299 (012Bh)
360 (0168h)
280 (0118h)
357 (0165h)
283 (011Bh)
354 (0162h)
287 (011Fh)
Modes available in VirtualBox
The VESA BIOS emulation in the VirtualBox virtual machine has a different set of non-standard VESA modes. As of 6.1.38_Ubuntu build r153438, the VESA BIOS function AX=0x4F01 reveals these modes (See also VBETables-gen.c):
^ abcModes available via the traditional 10h BIOS call
^352 (0160h) also appears to select 1280×800 (8-bit) for various laptops' displays
^32-bit is really (8:8:8:8), but the final 8-bit number is an "empty" alpha channel. It is otherwise equal to 24-bit color. Many GPUs use 32-bit color mode instead of 24-bit mode merely for faster video memory access through 32-bit memory alignment.
