82801FB Datasheet, PDF (170/786 Pages) Intel Corporation – Intel I/O Controller Hub 6 (ICH6) Family

Functional Description
5.14.10.3 Read Only Registers with Write Paths in
ALT Access Mode
The registers described in Table 5-37 have write paths to them in ALT access mode. Software
restores these values after returning from a powered down state. These registers must be handled
special by software. When in normal mode, writing to the base address/count register also writes to
the current address/count register. Therefore, the base address/count must be written first, then the
part is put into ALT access mode and the current address/count register is written.
Table 5-37. Register Write Accesses in ALT Access Mode
I/O Address
Register Write Value
08h
DMA Status Register for channels 0–3.
D0h
DMA Status Register for channels 4–7.
5.14.11 System Power Supplies, Planes, and Signals
5.14.11.1 Power Plane Control with SLP_S3#, SLP_S4#
and SLP_S5#
5.14.11.1.1
The usage of SLP_S3# and SLP_S4# depends on whether the platform is configured for S3_HOT and
S3_COLD.
S3_HOT
The SLP_S3# output signal is used to cut power only to the processor and associated subsystems
and to optionally stop system clocks.
5.14.11.1.2
S3_COLD
The SLP_S3# output signal can be used to cut power to the system core supply, since it only goes
active for the STR state (typically mapped to ACPI S3). Power must be maintained to the ICH6
resume well, and to any other circuits that need to generate Wake signals from the STR state.
Cutting power to the core may be done via the power supply, or by external FETs to the
motherboard.
The SLP_S4# or SLP_S5# output signal can be used to cut power to the system core supply, as well
as power to the system memory, since the context of the system is saved on the disk. Cutting power
to the memory may be done via the power supply, or by external FETs to the motherboard.
The SLP_S4# output signal is used to remove power to additional subsystems that are powered
during SLP_S3#.
SLP_S5# output signal can be used to cut power to the system core supply, as well as power to the
system memory, since the context of the system is saved on the disk. Cutting power to the memory
may be done via the power supply, or by external FETs to the motherboard.
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Intel^® I/O Controller Hub 6 (ICH6) Family Datasheet