Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

R

9.6.40. CR81Reserved

I/O (and Memory Offset) Address:

3B5h/3D5h(index 81h)

Default:

00h

Attributes

Read/Write

This register is not present in 2D.

7

0

 

 

 

Reserved (00000000)

 

 

 

 

 

 

 

 

 

 

Bit

Description

 

 

 

 

7:0

Reserved. (This register did something useful in ‘554, and was not completely removed from Portola

 

 

 

database, even though it does nothing useful).

 

 

 

 

 

9.6.41.CR82Blink Rate Control

I/O (and Memory Offset) Address:

3B5h/3D5h(index 82h)

Default:

00h

Default:

83h is the VGA default, but 88h is used instead because

that’s a more visually

appealing value

Attributes

Read/Write

The h/w default for this register does not match the VGA compatibility requirements. BIOS must make sure to set this register to correct value.

 

 

7

 

6

5

0

 

 

Character Blink Duty

 

VSync Blink Rate

 

 

 

 

Cycle

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit

 

 

 

 

Description

 

 

 

 

 

 

 

7:6

 

Character Blink Duty Cycle. (Character Blink is also known as Attribute Blink).

 

 

 

 

00

= 50% duty cycle.

 

 

 

 

 

01

= 25% duty cycle.

 

 

 

 

 

10

= 50% duty cycle (power on default).

 

 

 

 

 

 

 

 

5:0

 

VSync Blink Rate. Controls the cursor blink rate in terms of the number of VSyncs on the following

 

 

 

 

basis: the programmed value must be the (actual value/2)-1. (The default is 3).

 

 

 

 

 

 

 

 

 

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Image 140
Intel 815 manual 40. CR81Reserved, 41. CR82Blink Rate Control