Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

R

9.4.6.AR13Horizontal Pixel Panning Register

I/O (and Memory Offset) Address:

Read at 3C1h and Write at 3C0h; (index=13h)

Default:

 

 

0Uh (U=Undefined)

Attributes:

 

Read/Write

 

 

7

 

 

4

3

0

 

 

 

 

 

Reserved (0000)

 

 

Horizontal Pixel Shift

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit

 

 

 

Description

 

 

 

 

 

 

 

 

7:4

Reserved.

 

 

 

 

 

 

 

 

3:0

Horizontal Pixel Shift 3-0.This field holds a 4-bit value that selects the number of pixels by which the

 

 

 

image is shifted horizontally to the left. This function is available in both text and graphics modes.

 

 

 

In text modes with a 9-pixel wide character box, the image can be shifted up to 9 pixels to the left. In text

 

 

 

modes with an 8-pixel wide character box, and in graphics modes other than those with 256 colors, the

 

 

 

image can be shifted u0p to 8 pixels to the left.

 

 

 

 

 

In standard VGA mode 13h (where bit 6 of the Mode Control Register, AR10, is set to 1 to support 256

 

 

 

colors), bit 0 of this register must remain set to 0, and the image may be shifted up to only 4 pixels to

 

 

 

the left. In this mode, the number of pixels by which the image is shifted can be further controlled using

 

 

 

bits 6 and 5 of the Preset Row Scan Register (CR08).

 

 

 

Number of Pixels Shifted

 

 

 

 

 

 

 

 

 

8-Pixel Text

 

256-Color

 

 

 

Bits [3:0]

9 Pixel Text

& Graphics

 

Graphics

 

 

 

0h

1

0

 

0

 

 

 

 

1h

2

1

 

Undefined

 

 

 

2h

3

2

 

1

 

 

 

 

3h

4

3

 

Undefined

 

 

 

4h

5

4

 

2

 

 

 

 

5h

6

5

 

Undefined

 

 

 

6h

7

6

 

3

 

 

 

 

7h

8

7

 

Undefined

 

 

 

8h

0

Undefined

 

Undefined

 

 

 

 

 

 

 

 

 

105

Page 105
Image 105
Intel 815 manual 6. AR13Horizontal Pixel Panning Register, Reserved, Pixel Text Color, Pixel Text Graphics