Intel 815 manual DACSTATEDAC State Register, DACRXPalette Read Index Register

Models: 815

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Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

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9.5.2.DACSTATEDAC State Register

I/O (and Memory Offset) Address: 3C7h

 

 

 

Default:

 

00h

 

 

 

Attributes:

Read Only

 

 

 

7

 

2

1

0

 

 

 

 

 

Reserved (000000)

 

DAC State

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit

 

Description

 

 

 

 

 

 

 

 

 

 

7:2

Reserved. Read as 0s.

 

 

 

 

 

 

 

 

1:0

DAC State. This field indicates which of the two index registers was most recently written.

 

 

 

 

Bits [1:0]

Index Register Indicated

 

 

 

 

 

 

00

Palette Write Index Register at I/O Address 3C7h (default)

 

 

 

 

 

01

Reserved

 

 

 

 

 

 

10

Reserved

 

 

 

 

 

 

11

Palette Read Index Register at I/O Address 3C8h

 

 

 

 

 

 

 

 

 

 

 

9.5.3.DACRXPalette Read Index Register

I/O (and Memory Offset) Address:

3C7h

Default:

 

00h

Attributes:

Write Only

 

 

 

 

 

Bit

 

Description

 

 

 

 

7:0

Palette Read Index. The 8-bit index value programmed into this register chooses which of 256 standard

 

 

color data positions within the palette (or which of 8 alternate color data positions, depending on the

 

 

state of a bit in the Pixel Pipeline Control 0 Register) are to be made accessible for being read via the

 

 

Palette Data Register (DACDATA). The index value held in this register is automatically incremented

 

 

when all three bytes of the color data position selected by the current index have been read.

 

 

 

 

9.5.4.DACWXPalette Write Index Register

I/O (and Memory Offset) Address:

3C8h

Default:

 

00h

Attributes:

Write Only

 

 

 

 

 

Bit

 

Description

 

 

 

 

7:0

Palette Write Index. The 8-bit index value programmed into this register chooses which of 256 standard

 

 

color data positions within the palette (or which of 8 alternate color data positions, depending on the

 

 

state of a bit in the Pixel Pipeline Control 0 Register) are to be made accessible for being written via the

 

 

Palette Data Register (DACDATA). The index value held in this register is automatically incremented

 

 

when all three bytes of the color data position selected by the current index have been written.

 

 

 

 

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Page 108
Image 108
Intel 815 manual DACSTATEDAC State Register, DACRXPalette Read Index Register, DACWXPalette Write Index Register