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5.2 Intel ICH6-M South Bridge(10)
Functional Strap Definitions 1
Signal Usage
When
Sampled
Description
GNT[6]#/
GPO[16]
Top-Block Swap
Override
Rising Edge of
PWROK
The signal has a weak internal pull-up. If the
signal is sampled low, this indicates that the
system is strapped to the “top-block swap” mode
(ICH6 inverts A16 for all cycles targeting FWH
BIOS space). The status of this strap is readable
via the Top Swap bit (Chipset Configuration
Registers:Offset 3414h:bit 0). Note that software
will not be able to clear the Top-Swap bit until
the system is rebooted without GNT6# being
pulled down.
LINKALERT
#
Reserved
This signal requires an external pull-up resistor.
SPKR
No Reboot
Rising Edge
ofPWROK
The signal has a weak internal pull-down. If the
signal is.sampled high, this indicates that the
system is strapped to.the “No Reboot” mode
(ICH6 will disable the TCO Timer. system
reboot feature). The status of this strap is
readable. via the NO REBOOT bit (Chipset
Configuration. Registers:Offset 3410h:bit 5).
INTVRMEN IntegratedVccSu
1_5VRM
Enable/Disable
Always
This signal enables integrated VccSus1_5 VRM
when.sampled high.
GPIO[25] Integrated
Vcc2_5 VRM
Enable/ Disable
Rising Edge of
RSMRST#
This signal enables integrated Vcc2_5 VRM
when sampled low. This signal has a weak
internal pull-up during RSMRST# and is
disabled within 100 ms after RSMRST#
de-asserts.
EE_CS
Reserved
This signal has a weak internal pull-down.
NOTE:
This signal should not be pulled high.
GNT[5]#/
GPO[17]
Boot BIOS
Destination
Selection
Rising Edge of
PWROK
This signal has a weak internal pull-up. Allows
for select memory ranges to be forwarded out the
PCI Interface as opposed to the Firmware Hub.
When sampled high, destination is LPC. Also
controllable via Boot BIOS Destination bit
(Chipset Configuration Registers:Offset
3410h:bit 3).
NOTE:
This functionality intended for
debug/testing only.
Functional Strap Definitions 1 (Continued)
Signal Usage
When
Sampled
Description
EE_DOUT
Reserved
This signal has a weak internal pull-up.
NOTE:
This signal should not be pulled low.
ACZ_SDOU
T
XOR Chain
Entrance / PCI
Express* Port
Configu-ration
bit 1
Rising Edge of
PWROK
Allows entrance to XOR Chain testing when
TP[3] pulled low at rising edge of PWROK. See
Chapter 24 for XOR Chain functionality
information.
When TP[3] not pulled low at rising edge of
PWROK, sets bit 1 of RPC.PC (Chipset
Configuration Registers:Offset 224h). See
Section 7.1.30 for details.
This signal has a weak internal pull-down.
ACZ_SYNC PCI Express Por
Configu-ration
bit 0
Rising Edge of
PWROK
This signal has a weak internal pull-down.
Sets bit 0 of RPC.PC (Chipset Configuration
Registers: Off set 224h). See Section 7.1.30 for
details.
TP[1]
Reserved
This signal has a weak internal pull-down.
NOTE:
This signal should not be pulled high.
SATALED#
Reserved
This signal has a weak internal pull-up enabled
only when PLTRST# is asserted.
NOTE:
This signal should not be pulled low.
REQ[4:1]# XOR
Chain
Selection
Rising Edge of
PWROK
See Chapter 24 for functionality information.
TP[3] XOR
Chain
Entrance
Rising Edge of
PWROK
See Chapter 24 for functionality information.
This signal has a weak internal pull-up.
NOTE:
This signal should not be pulled low
unless using XOR Chain testing.
Real Time Clock Interface
Name Type
Description
RTCX1
Special
Crystal Input 1:
This signal is connected to the 32.768 kHz crystal.
If no external crystal is used, then RTCX1 can be driven with the
desired clock rate.
RTCX2
Special
Crystal Input 2:
This signal is connected to the 32.768 kHz crystal.
If no external crystal is used, then RTCX2 should be left floating.
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