Intel 815 manual Pixel Panning Compatibility, Enable Blinking/Select Background Intensity

Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

R

Bit	Description
5	Pixel Panning Compatibility.
	0 = Scroll both the upper and lower screen regions horizontally as specified in the Pixel Panning
	Register (AR13).
	1 = Scroll only the upper screen region horizontally as specified in the Pixel Panning Register (AR13).
	Note:
	This bit has application only when split-screen mode is being used, where the display area is divided
	into distinct upper and lower regions which function somewhat like separate displays.
4	Reserved. Read as 0s.
3	Enable Blinking/Select Background Intensity.
	0 = Disables blinking in graphics modes, and for text modes, sets bit 7 of the character attribute bytes
	to control background intensity, instead of blinking.
	1 = Enables blinking in graphics modes and for text modes, sets bit 7 of the character attribute bytes to
	control blinking, instead of background intensity.
	Note:
	The blinking rate is derived by dividing the VSYNC signal. The Blink Rate Control Register (FR19)
	defines the blinking rate.
2	Enable Line Graphics Character Code.
	0 = Every 9th pixel of a horizontal line (i.e., the last pixel of each horizontal line of each 9-pixel wide
	character box) is assigned the same attributes as the background of the character of which the
	given pixel is a part.
	1 = Every 9th pixel of a horizontal line (i.e., the last pixel of each horizontal line of each 9-pixel wide
	character box) is assigned the same attributes as the 8th pixel if the character of which the given
	pixel is a part. This setting is intended to accommodate the line-drawing characters of the PC’s
	extended ASCII character set -- characters with an extended ASCII code in the range of B0h to
	DFh.
	Note:
	In IBM* literature describing the VGA standard, the range of extended ASCII codes that are said to
	include the line-drawing characters is mistakenly specified as C0h to DFh, rather than the correct range
	of B0h to DFh.
1	Select Display Type.
	0 = Attribute bytes in text modes are interpreted as they would be for a color display.
	1 = Attribute bytes in text modes are interpreted as they would be for a monochrome display.
0	Graphics/Alphanumeric Mode.
	0 = Alphanumeric (text) mode.
	1 = Graphics mode.

103