Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

R

9.1.3.

FCRFeature Control

 

 

I/O (and Memory Offset) Address:

3BAh/3DAhWrite; 3CAhRead

 

Default:

00h

 

Attributes:

See Address above

The address selection for reads is dependent on CGA or MDA emulation mode as selected via the MSR register.

 

7

4

3

2

0

 

 

 

Reserved (0000)

VSYNC

 

Reserved (000)

 

 

 

 

Control

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit

Descriptions

 

 

 

 

 

 

 

 

 

 

 

7:4

Reserved. Read as 0.

 

 

 

 

 

 

 

 

 

 

 

 

3

VSYNC Control.

 

 

 

 

 

 

0 = Vsync output on the VSYNC pin (default).

 

 

 

 

 

 

1 = Logical 'OR' of VSync and Display Enable output on the VSYNC pin. This capability is provided for

 

 

 

IBM compatibility.

 

 

 

 

 

 

 

 

 

 

 

 

2:0

Reserved. Read as 0.

 

 

 

 

 

 

 

 

 

 

 

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Image 82
Intel 815 manual FCRFeature Control, Reserved. Read as Vsync Control