82845MP Datasheet, PDF (39/157 Pages) Intel Corporation – Intel 845 Family Chipset-Mobile 82845MP/82845MZ Chipset Memory Controller Hub Mobile (MCH-M)

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Intel^® 82845MP/82845MZ Chipset-Mobile (MCH-M)
“Reserved” register location is read, a random value is returned. (“Reserved” registers can be 8-bit, 16-
bit, or 32-bit in size.) Writes to “Intel Reserved” registers may cause system failure. Reads to “Intel
Reserved” registers may return a non-zero value.
Default Value Upon Reset:
Upon a full Reset, the MCH-M sets all of its internal configuration registers to predetermined default
states. Some register values at reset are determined by external strapping options. The default state
represents the minimum functionality feature set required to successfully bring up the system. Hence, it
does not represent the optimal system configuration. It is the responsibility of the system initialization
software (usually BIOS) to properly determine the DRAM configurations, operating parameters and
optional system features that are applicable, and to program the MCH-M registers accordingly.
3.5.
I/O Mapped Registers
The MCH-M contains two registers that reside in the CPU I/O address space: the Configuration Address
(CONFIG_ADDRESS) Register and the Configuration Data (CONFIG_DATA) Register. The
Configuration Address Register enables/disables the configuration space and determines what portion of
configuration space is visible through the Configuration Data window.
3.5.1. CONFIG_ADDRESS – Configuration Address Register
I/O Address:
Default Value:
Access:
Size:
0CF8h Accessed as a Dword
00000000h
Read/Write
32 bits
CONFIG_ADDRESS is a 32-bit register that can be accessed only as a Dword. A Byte or Word
reference will "pass through" the Configuration Address Register and the hub interface, onto the PCI bus
as an I/O cycle. The CONFIG_ADDRESS register contains the Bus Number, Device Number, Function
Number, and Register Number for which a subsequent configuration access is intended.
Figure 2. Configuration Address Register
31 30 24 23 16 15 11 10
87
2 1 0 Bit
0R
0
0
0
0
R ^Default
Reserved
Register Number
Function Number
Device Number
Bus Number
Reserved
Enable
250687-002
Datasheet
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