User's Manual

Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0
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82
9.1.3. FCR

Feature Control
I/O (and Memory Offset) Address: 3BAh/3DAh Write; 3CAh Read
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
Control
Reserved (000)
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.