Intel 815 manual 12. CR0AText Cursor Start Register, 13. CR0BText Cursor End Register

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Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

R

9.6.12.CR0AText Cursor Start Register

I/O (and Memory Offset) Address:

3B5h/3D5h (index=0Ah)

Default:

00UU UUUUb (U=Undefined)

Attributes:

Read/Write

This cursor is the text cursor that is part of the VGA standard, and should not be confused with the hardware cursor and popup (a.k.a., cursor and cursor 2), which are intended to be used in graphics modes. This text cursor exists only in text modes, and thus, this register is entirely ignored in graphics modes.

 

7

6

5

4

0

 

 

 

Reserved (00)

Text

 

Text Cursor Start

 

 

 

 

 

Cursor Off

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit

 

 

 

 

Description

 

 

 

 

 

 

 

 

7:6

 

Reserved. Read as 0s.

 

 

 

 

 

 

 

 

 

 

 

 

5

 

Text Cursor Off.

 

 

 

 

 

 

 

0 = Enables the text cursor.

 

 

 

 

 

 

1 = Disables the text cursor.

 

 

 

 

 

 

 

 

4:0

 

Text Cursor Start. This field specifies which horizontal line of pixels in a character box is to be used to

 

 

 

display the first horizontal line of the cursor in text mode. The horizontal lines of pixels in a character box

 

 

 

are numbered from top to bottom, with the top-most line being number 0. The value specified by these 5

 

 

 

bits should be the number of the first horizontal line of pixels on which the cursor is to be shown.

 

 

 

 

 

 

 

 

9.6.13.CR0BText Cursor End Register

I/O (and Memory Offset) Address:

3B5h/3D5h (index=0Bh)

Default:

0UUU UUUUb (U=Undefined)

Attributes:

Read/Write

This cursor is the text cursor that is part of the VGA standard, and should not be confused with the hardware cursor and popup (a.k.a., cursor and cursor 2), which are intended to be used in graphics modes. This text cursor exists only in text modes, and so this register is entirely ignored in graphics modes.

 

 

7

 

6

5

4

0

 

 

Reserved

 

Text Cursor Skew

 

 

Text Cursor End

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit

 

 

 

 

 

Description

 

 

 

 

 

 

 

 

 

 

 

7

 

Reserved. Read as 0s.

 

 

 

 

 

 

 

 

 

6:5

 

Text Cursor Skew. This field specifies the degree to which the start and end of each horizontal line of

 

 

 

pixels making up the cursor is delayed to compensate for internal pipeline delays. These 2 bits describe

 

 

 

the delay in terms of a number character clocks.

 

 

 

 

 

00

= No delay

 

 

 

 

 

 

 

01

= Delayed by 1 character clock

 

 

 

 

 

10

= Delayed by 2 character clocks

 

 

 

 

 

11

= Delayed by 3 character clocks

 

 

 

 

 

 

 

4:0

 

Text Cursor End. This field specifies which horizontal line of pixels in a character box is to be used to

 

 

 

display the last horizontal line of the cursor in text mode. The horizontal lines of pixels in a character box

 

 

 

are numbered from top to bottom, with the top-most line being number 0. The value specified by these 5

 

 

 

bits should be the number of the last horizontal line of pixels on which the cursor is to be shown.

 

 

 

 

 

 

 

 

 

 

119

Page 119
Image 119
Intel 815 manual 12. CR0AText Cursor Start Register, 13. CR0BText Cursor End Register