User's Manual

Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

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9.6.40. CR81



Reserved

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. CR82



Blink 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

Cycle

VSync Blink Rate

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).