845GL datasheet(182/193 Pages) INTEL

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Intel® 82845G/82845GL/82845GV GMCH Datasheet

182

Intel® 82845GL/82845GV GMCH

9.2

No AGP Interface

The 82845GL and 82845GV do not have an AGP interface. References to AGP in this document

only apply to the 82845G component. For example, Chapter 2 describes how the 82845G DVO

signals are multiplexed with the AGP signals. For the 82845GL/82845GV, the DVO signals are

NOT multiplexed. In addition, AGP related registers are NOT in the 82845GL/82845GV

components (see Section 9.4).

9.3

Intel® 82845G and Intel® 82845GL/82845GV Signal

Differences

The 82845GL and 82845GV have the same signals. The following lists the signal differences

between the 82845G and the 82845GL/82845GV:

• ADD_DETECT signal functionality is slightly different between the 82845G and

the82845GL/82845GV. For the 82845GL/82845GV, replace the ADD_DETECT signal

description in Section 2.4.5 with the following:

• There are no AGP signals on the 82845GL/82845GV. The 82845GL/82845GV DVO signals

are not multiplexed. Section 2.5.1, Intel® DVO Signals Name to AGP Signal Name Pin

Mapping does not apply to the 82845GL/82845GV.

9.3.1

Functional Straps (82845GL only)

In Section 2.10, Functional Straps, the PSBSEL signal description is replaced by the following:

Signal Name

Type

Description

GPAR/

ADD_DETECT

I/O AGP

PAR:

Same as PCI. Not used on AGP transactions but used during PCI

transactions as defined by the PCI Local Bus Specification, Revision 2.1.

ADD_DETECT:

This signal acts as a strap and indicates whether the

interface is in DVO mode. The 82845GL/82845GV GMCH has an internal

pull-up on this signal that will naturally pull it high. If a DVO is utilized, the

signal should be pulled low and the DVO select bit in the GMCHCFG

DVO down scenario should have a pull-down resistor on ADD_DETECT.

Signal Name

Type

Description

PSBSEL

PSB Frequency Select:

The PSBSEL is tied to the external BSEL resistor-divider

circuitry. The value of the PSBSEL pin reflects the PSB frequency. The PSB runs at

400 MHz when PSBSEL is a 0. The 82845GL does not support PSB frequency of

533 MHz and a PSBSEL value of 1 would not allow the board to boot.

845GL Datasheet(PDF) 182 Page - Intel Corporation

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