參數(shù)資料
型號： 845GE
廠商： Intel Corp.
英文描述： 82845GE Graphics and Memory Controller Hub (GMCH) and 82845PE Memory Controller Hub (MCH)
中文描述： 82845GE圖形和內(nèi)存控制器中樞（GMCH）和82845PE內(nèi)存控制器中樞（MCH）
文件頁數(shù)： 40/176頁
文件大?。?/td> 2661K
代理商： 845GE
Register Description
40
Intel
82845GE/82845PE Datasheet
3.2
Platform Configuration
In some previous chipsets the MCH (or GMCH) component and the I/O Controller Hub component
were physically connected by PCI bus #0. From a configuration standpoint, both components
appeared to be on PCI bus #0 which was also the system’s primary PCI expansion bus. The north
bridge contained two PCI devices while the south bridge was considered one PCI device with
multiple functions.
In the 845GE/845PE chipset platforms the configuration structure is significantly different. The
(G)MCH and the ICH4 are physically connected by the hub interface; thus, from a configuration
standpoint, the hub interface is logically PCI bus #0. As a result, all devices internal to the
(G)MCH and ICH4 appear to be on PCI bus #0. The system’s primary PCI expansion bus is
physically attached to the ICH4 and, from a configuration perspective, appears to be a hierarchical
PCI bus behind a PCI-to-PCI bridge and therefore has a programmable PCI Bus number. The AGP
appears to system software to be a real PCI bus behind PCI-to-PCI bridge’s resident as devices on
PCI bus #0.
Note:
The primary PCI bus is referred to as PCI_A in this document and is not PCI bus #0 from a
configuration standpoint.
The (G)MCH contains the following PCI devices within a single physical component. The
configuration registers for the devices are mapped as devices residing on PCI bus #0.
Device 0:
Host-HI Bridge/DRAM controller. Logically this appears as a PCI device residing
on PCI bus #0. Physically Device 0 contains the standard PCI registers, DRAM registers, AGP
capabilities registers, the Graphics Aperture controller, and other (G)MCH specific registers.
Device 1:
Host-AGP Bridge. Logically this appears as a “virtual” PCI-to-PCI bridge residing
on PCI bus #0. Physically Device 1 contains the standard PCI-to-PCI bridge registers and the
standard AGP/PCI configuration registers (including the AGP I/O and memory address
mapping).
Device 2 (82845GE only):
Integrated Graphics controller. Logically this appears as a PCI
device residing on PCI bus #0. Physically Device 2 contains the configuration registers for 3D,
2D and display functions.
Device 6:
Intel Reserved.
Reserved
Bits
Some of the (G)MCH registers described in this chapter contain reserved bits. These bits are
labeled Reserved (Rsvd). Software must deal correctly with fields that are reserved. On reads,
software must use appropriate masks to extract the defined bits and not rely on reserved bits
being any particular value. On writes, software must ensure that the values of reserved bit
positions are preserved. That is, the values of reserved bit positions must first be read, merged
with the new values for other bit positions, and then written back. Note the software does not
need to perform read, merge, and write operations for the configuration address register.
Reserved
Registers
In addition to reserved bits within a register, the (G)MCH contains address locations in the
configuration space of the Host-Hub Interface Bridge entity that are marked either “Reserved” or
“Intel Reserved.” The (G)MCH responds to accesses to “Reserved” address locations by
completing the host cycle. When a “
Reserved
” register location is read, a zero value is returned.
(“Reserved” registers can be 8, 16, or 32 bits in size). Writes to “Reserved” registers have no
effect on the (G)MCH. Registers that are marked as “Intel Reserved” must not be modified by
system software. 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 Reset, the (G)MCH 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
(G)MCH registers accordingly.
Term
Description
相關(guān)PDF資料
PDF描述
845PE 82845GE Graphics and Memory Controller Hub (GMCH) and 82845PE Memory Controller Hub (MCH)
845G Intel 82845G/82845GL/82845GV Graphics and Memory Controller Hub (GMCH)
845GL Intel 82845G/82845GL/82845GV Graphics and Memory Controller Hub (GMCH)
845GV Intel 82845G/82845GL/82845GV Graphics and Memory Controller Hub (GMCH)
8460 LAN 10/100 Base-TX Dual Port Transformer Modules
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
845GE MAX-L 制造商:Micro-Star International 功能描述:845GE P4/CELERON 533FSB ATX - Bulk
845GEM-L 制造商:Micro-Star International 功能描述:845GEM-L P4 MATX HYPER-T - Bulk
845GL 制造商:INTEL 制造商全稱:Intel Corporation 功能描述:Intel 82845G/82845GL/82845GV Graphics and Memory Controller Hub (GMCH)
845GLMS-L 制造商:Micro-Star International 功能描述:845GL UATX P4/CEL 400FSB - Bulk
845GR 制造商:SPC 功能描述:New
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