Design Guide

Platform Design Checklist
R
Intel
®
855GM/855GME Chipset Platform Design Guide 301
16.7. ICH4-M Checklist
Note: All inputs to the ICH4-M must not be left floating. Many GPIO signals are fixed inputs that must be pulled up
to different sources.
16.7.1. PCI Interface and Interrupts
Pin Name System Pull-up /Pull-down Notes
9
PCI_DEVSEL#
8.2 k
Ω pull-up to Vcc3_3
PCI_FRAME#
8.2 k
Ω pull-up to Vcc3_3
PCI_GPIO0 / REQA#
PCI_GPIO1 / REQB_L/REQ5#
8.2 k
Ω pull-up to Vcc3_3
Each signal requires a pull-up resistor.
PCI_GPIO16 / GNTA# GNTA is also used as a strap for “top block swap”. It
is sampled on the rising edge of PWROK. By
default, this signal is HIGH (strap function
DISABLED). It can be enabled by a pull-down to gnd
through a 1-k
Ω resistor.
PCI_IRDY#
8.2 k
Ω pull-up to Vcc3_3
PCI_LOCK#
8.2 k
Ω pull-up to Vcc3_3
PCI_PERR#
8.2 k
Ω pull-up to Vcc3_3
PCI_SERR#
8.2 k
Ω pull-up to Vcc3_3
PCI_STOP#
8.2 k
Ω pull-up to Vcc3_3
PCI_TRDY#
8.2 k
Ω pull-up to Vcc3_3
PCI_REQ[4:0]#
8.2 k
Ω pull-up to Vcc3_3
Each signal requires a pull-up resistor.
PCI_PME#
ICH4-M has internal pull-up to VccSus3_3.
PCI_RST#, PAR, GNT[4:0]#,
GNTA#, GNTB#
None
APICCLK
0
Ω to gnd
Can also be connected directly to ground.
APICD[1:0]
10 k
Ω pull-down to gnd
If XOR chain testing is NOT used: Pull down the
signals through a shared 10 k
Ω resistor. If XOR
chain testing is used: Each signal requires a
separate 10-k
Ω pull-down resistor.
INT_IRQ[15:14]
8.2 k
Ω pull-up to Vcc3_3
Each signal requires a pull-up resistor.
INT_PIRQ#[A:D]
INT_PIRQE#/GPIO2
INT_PIRQF#/GPIO3
INT_PIRQG#/GPIO4
INT_PIRQH#/GPIO5
8.2 k
Ω pull-up to Vcc3_3
External pull up is required for INT_PIRQ#[A:D].
External pull up is required when muxed signal
(INT_PIRQ[E:H]#/ GPIO[2:5]) is implemented as
PIRQ.
INT_SERIRQ
8.2 k
Ω pull-up to Vcc3_3