VBE Mode Numbers
Although mode number is a 16-bit value, the optional VBE mode numbers are 14 bits wide. Bit 7 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.
Read more about this topic: VESA BIOS Extensions
Famous quotes containing the words mode and/or numbers:
“That the mere matter of a poem, for instance—its subject, its given incidents or situation; that the mere matter of a picture—the actual circumstances of an event, the actual topography of a landscape—should be nothing without the form, the spirit of the handling, that this form, this mode of handling, should become an end in itself, should penetrate every part of the matter;Mthis is what all art constantly strives after, and achieves in different degrees.”
—Walter Pater (1839–1894)
“I had but three chairs in my house; one for solitude, two for friendship; three for society. When visitors came in larger and unexpected numbers there was but the third chair for them all, but they generally economized the room by standing up.”
—Henry David Thoreau (1817–1862)