User's Manual

Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

103

Bit Description

5 Pixel Panning Compatibility.

0 = Scroll both the upper and lower screen regions horizontally as specified in the Pixel Panning

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.