Agp Routing Ground Reference; Pull-Ups - Intel 852GME Design Manual

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8.2.6.

AGP Routing Ground Reference

Intel strongly recommends that at least the following critical signals be referenced to ground from the
MCH and GMCH to an AGP controller connector using a minimum number of vias on each net:
AD_STB0
AD_STB0#
AD_STB1
AD_STB1#
SB_STB
SB_STB#
G_TRDY#
G_IRDY#
G_GNT#
ST[2:0].
8.2.7.

Pull-ups

The AGP 2.0 Specification requires AGP control signals to have pull-up resistors to VDDQ to ensure
they contain stable values when no agent is actively driving the bus. Also, the AD_STB[1:0]# and
ST_STB# strobes require pull-down resistors to GND. The Intel 852GME/852GMV/852PMchipset
MCH/GMCH has integrated many of these pull-up/pull-down resistors on the AGP interface and a few
other signals not required by the AGP 2.0 Specification. Pull-ups are allowed on any signal except
AD_STB[1:0]# and SB_STB#.
The Intel chipset GMCH has no support for the PERR# and SERR# pins of an AGP graphics controller
that supports PERR# and SERR#. Pull-ups to a 1.5-V source are required down on the motherboard in
such cases.
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Intel 852GME, Intel 852GMV and Intel
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852PM Chipset Platforms Design Guide
AGP Port Design Guidelines
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