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:
“The only mode of obtaining an answer to these questions of the senses is to forego all low curiosity, and, accepting the tide of being which floats us into the secret of nature, work and live, work and live, and all unawares the advancing soul has built and forged for itself a new condition, and the question and the answer are one.”
—Ralph Waldo Emerson (1803–1882)
“Out of the darkness where Philomela sat,
Her fairy numbers issued. What then ailed me?
My ears are called capacious but they failed me,
Her classics registered a little flat!
I rose, and venomously spat.”
—John Crowe Ransom (1888–1974)