Mobile Intel Pentium 4 Processor Supporting Hyper-Threading Technology on 90-nm Process Technology

68 Mobile Intel® Pentium® 4 Processor Supporting Hyper-Threading Technology on 90-nm Process Technology Datasheet
Features
6.2.2 AutoHALT Power-Down State—State 2
AutoHALT is a low-power state entered when the processor executes the HALT instruction. The
processor will transition to the Normal state upon the occurrence of SMI#, BINIT#, INIT#, or
LINT[1:0] (NMI, INTR). RESET# will cause the processor to immediately initialize itself.
The return from a System Management Interrupt (SMI) handler can be to either Normal mode or
the AutoHALT Power-Down state. See the Intel
®
Architecture Software Developer's Manual,
Volume III: System Programmer's Guide for more information.
The system can generate a STPCLK# while the processor is in the AutoHALT Power-Down state.
When the system deasserts the STPCLK# interrupt, the processor will return execution to the
HALT state.
While in AutoHALT Power-Down state, the processor will process front side bus snoops and
interrupts.
6.2.3 Stop-Grant State—State 3
When the STPCLK# pin is asserted, the Stop-Grant state of the processor is entered 20 bus clocks
after the response phase of the processor-issued Stop Grant Acknowledge special bus cycle.
Figure 6-1. Stop Clock State Machine
3. Stop Grant State
BCLK running.
Snoops and int errupt s allowed.
STPCLK#
De-asserted
SLP#
De-asserted
1. No rmal State
Normal execut ion.
5. Sl eep State
BCLK running.
No snoops or interrupts allowed.
2. Au to HALT Power Do wn State
BCLK running.
Snoops and int errupt s allowed.
4. HALT/Grant Snoop State
BCLK running.
Service snoops to caches.
STPCLK#
Asserted
SLP#
Asserted
Snoop
Event
Occurs
Snoop
Event
Serviced
HALT I nst ruct ion and
HALT Bus Cycle Generated
INIT#, BINIT#, INTR, NMI,
SMI#, RESET#
Snoop Event Serviced
Snoop Event O ccurs
S
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S
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6. Deep Sl eep State
DPSLP#
Asserted
DPSLP#
De-asserted
7. Deep er Sl eep State
Core Volt age lowered
Core Volt age raised