Intel 815 Manuel D’Utilisation
Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0
R
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7. Initialization
Registers
To function, all registers described in this section must be programmed for the Intel
®
815 chipset family
of products. The default states of these registers, with the exception of registers that deal with extended
modes or performance enhancements, will prevent the Intel
modes or performance enhancements, will prevent the Intel
®
815 chipset family products from booting.
Note: The registers in this document are normally programmed by the video BIOS.
These registers also may be documented in other sections of this document.
7.1.
Standard VGA Registers
All VGA registers are in standard locations and initialized by means of standard procedures. This section
will document all nonstandard registers that are needed for initialization of the Intel
will document all nonstandard registers that are needed for initialization of the Intel
®
815 chipset.
7.2. SMRAM
Registers
The SMRAM register is in the chipset’s PCI configuration space (Device 0). Since this register is not
documented anywhere else, the entire register description is provided here.
documented anywhere else, the entire register description is provided here.
7.2.1.
SMRAM—System Management RAM Control Register
(Device 0)
Address Offset:
70h
Default Value:
00h
Access:
Read/Write, Read Only
Size: 8
bits
The SMRAM register controls how accesses to Compatible and Extended SMRAM spaces are treated,
and how much (if any) memory is “Stolen” from the System to support both SMRAM and Graphics
Local Memory needs.
and how much (if any) memory is “Stolen” from the System to support both SMRAM and Graphics
Local Memory needs.
7
6 5
4 3
2
1
0
Graphics Mode Select
Upper SMM Select
Lower SMM Select
SMM
Space
Locked
E_SMRA
M_ERR