82845G Datasheet, PDF (15/193 Pages) Intel Corporation – Intel 82845G/82845GL/82845GV Graphics and Memory Controller Hub (GMCH)

Introduction
1.3
Intel^® 845G Chipset System Overview
Figure 1-1 shows an example block diagram of an 845G chipset-based platform. The 845G chipset
is designed for use in a desktop system based on an Intel^® Pentium^® 4 processor in a 478-pin
package. The 845G chipset supports the Pentium 4 processor with 256-KB L2 cache and the
Pentium 4 processor with 512-KB L2 cache on 0.13 micron process. The processor interface
supports the Pentium 4 processor subset of the Extended Mode of the Scalable Bus Protocol. In an
845G chipset-based platform, I/O functions are integrated onto the ICH4.
The chipset platform supports either the integrated graphics device (IGD) on the GMCH or an
external graphics device on AGP. The IGD has 3D, 2D, and video capabilities. The IGD also has
two multiplexed Intel DVO ports to support DVO devices. The GMCH’s AGP interface supports
1X/2X/4X AGP data transfers and 2X/4X AGP Fast Writes, as defined in the Accelerated Graphics
Port Interface Specification, Revision 2.0 for 1.5 V signaling.
In an 845G chipset, system memory can be either a single channel of SDR (Single Data Rate)
SDRAM or DDR (Double Data Rate) SDRAM, with a 64-bit wide data bus. The system memory
size can be up to 2 GB.
Section 1.4 provides an overview of the GMCH. The following sub-section provides an overview
of the ICH4.
Intel^® 82801DB I/O Controller Hub 4 (ICH4)
The ICH4 is a highly integrated multifunctional I/O Controller Hub that provides the interface to
the PCI Bus and integrates many of the functions needed in today’s PC platforms. The GMCH and
ICH4 communicate over a dedicated hub interface. The 82801DB ICH4 functions and capabilities
include:
• PCI Rev 2.2 compliant with support for 33 MHz PCI operations
• Supports up to 6 Request/Grant pairs (PCI slots)
• Power management logic support
• Enhanced DMA controller, interrupt controller, and timer functions
• Integrated IDE controller; Ultra ATA/100/66/33
• USB host interface; 3 host controllers and supports 6 USB ports; includes a EHCI high-speed
2.0 USB controller
• Integrated LAN controller
• System Management Bus (SMBus) compatible with most I²C devices; ICH4 has both bus
master and slave capability
• AC ’97 2.3 supported for audio and telephony codecs; up to 6 channels
• Low Pin Count (LPC) interface
• FWH Interface (FWH Flash BIOS support)
• Alert on LAN* (AOL and AOL2)
Intel^® 82845G/82845GL/82845GV GMCH Datasheet
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