Table 75. Agp Pull-Up/Pull-Down Requirements And Straps; Table 76. Agp 2.0 Pull-Up Resistor Values - Intel 855GM Design Manual

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Table 75. AGP Pull-Up/Pull-Down Requirements and Straps

Signal
DEVSEL#
FRAME#
GNT#
INTA#
INTB#
IRDY#
PERR#
PIPE#
RBF#
REQ#
SERR#
ST[2:0]
STOP#
TRDY#
WBF#
AD_STB[1:0]
AD_STB[1:0]#
SB_STB
SB_STB#
SBA[7:0]
NOTES:
1. The Intel 855GME chipset GMCH has integrated pull-ups to ensure that these signals do not float when there is
no add-in card in the connector.
2. The Intel 855GME chipset GMCH does not implement the PERR# and SERR# signals. Pull-ups on the
motherboard are required for AGP graphics controllers that implement these signals.
3. The AGP graphics controller's INTA# and INTB# signals must but routed to the system PCI interrupt request
handler where the pull-up requirement should be met. For Intel 855GME chipset-based systems, they can be
routed to the ICH4-M's PIRQ signals that are open drain and require pull-ups on the motherboard.
4. ST[1:0] provide the strapping options for 100-MHz PSB operation and DDR memory, respectively.
5. INTA# and INTB# should be pulled to 3.3 V, not VDDQ.
The pull-up/pull-down resistor value requirements are shown in Table 76.

Table 76. AGP 2.0 Pull-up Resistor Values

The recommended AGP pull-up/pull-down resistor value is 8.2 kΩ.
®
Intel 855GM/855GME Chipset Platform Design Guide
AGP 2.0 Signal
Pull-Up/Pull-Down
Requirements
Pull-Up
Pull-Up
Pull-Up
Pull-Up
Rmin
4 k Ω
GMCH Integrated Notes
Pull-Up/Pull-Down
Pull-Up
Pull-Up
Pull-Up
3, 5
3, 5
Pull-Up
2
Pull-Up
Pull-Up
Pull-Up 1
2
Pull-Up 4
Pull-Up
Pull-Up
Pull-Up
Pull-Up
Pull-Down
Pull-Up
Pull-Down
Pull-Up 1
Rmax
16 k Ω
AGP Port Design Guidelines
185