![](http://datasheet.mmic.net.cn/340000/82845G_datasheet_16452459/82845G_3.png)
Intel
82845G/82845GL/82845GV GMCH
Datasheet
3
Contents
1
Introduction
...........................................................................................................13
1.1
Terminology...................................................................................................13
1.2
Related Documents .......................................................................................14
1.3
Intel
845G Chipset System Overview..........................................................15
1.4
Intel 82845G GMCH Overview....................................................................17
1.4.1
Host Interface....................................................................................17
1.4.2
System Memory Interface.................................................................17
1.4.3
Hub Interface ....................................................................................17
1.4.4
Multiplexed AGP and Intel
DVO Port Interface...............................18
1.4.5
Graphics Overview............................................................................18
1.4.6
Display Interfaces .............................................................................19
Signal Description
..............................................................................................21
2.1
Host Interface Signals....................................................................................23
2.2
Memory Interface...........................................................................................25
2.2.1
DDR SDRAM Interface .....................................................................25
2.2.2
SDR SDRAM Interface .....................................................................26
2.3
Hub Interface .................................................................................................28
2.4
AGP Interface Signals....................................................................................29
2.4.1
AGP Addressing Signals...................................................................29
2.4.2
AGP Flow Control Signals ................................................................29
2.4.3
AGP Status Signals ..........................................................................30
2.4.4
AGP Strobes.....................................................................................30
2.4.5
PCI Signals–AGP Semantics............................................................31
2.4.6
PCI Pins during PCI Transactions on AGP Interface........................32
2.5
Multiplexed Intel
DVO Device Signal Interfaces ..........................................32
2.5.1
Intel
DVO Signal Name to AGP Signal Name Pin Mapping............34
2.6
Analog Display...............................................................................................35
2.7
Clocks, Reset, and Miscellaneous Signals....................................................36
2.8
RCOMP, VREF, VSWING Signals.................................................................36
2.9
Power and Ground Signals............................................................................37
2.10
Functional Straps...........................................................................................38
2.11
GMCH Sequencing Requirements.................................................................38
2.12
Reset States ..................................................................................................39
2.12.1 Full and Warm Reset States.............................................................39
Register Description
..........................................................................................41
3.1
Register Terminology.....................................................................................41
3.2
Platform Configuration...................................................................................42
3.3
Routing Configuration Accesses....................................................................43
3.3.1
Standard PCI Bus Configuration Mechanism ...................................44
3.3.2
PCI Bus #0 Configuration Mechanism..............................................44
3.3.3
Primary PCI and Downstream Configuration Mechanism.................44
3.3.4
AGP/PCI_B Bus Configuration Mechanism......................................44
3.4
I/O Mapped Registers....................................................................................46
3.4.1
CONFIG_ADDRESS—Configuration Address Register...................46
3.4.2
CONFIG_DATA—Configuration Data Register ................................47
3.5
Intel
GMCH Internal Device Registers.........................................................48
2
3