Intel Pentium 4 Processor Extreme Edition on 0.13 Micron Process in the 775-Land Package Datasheet

76 Datasheet
Features
6.2.2 AutoHALT Powerdown 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 de-asserts the STPCLK# interrupt, the processor will return execution to the
HALT state.
While in AutoHALT Power Down state, the processor will process FSB snoops and interrupts.
6.2.3 Stop-Grant State—State 3
When the STPCLK# signal 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.
Since the GTL+ signal receive power from the FSB, these signals should not be driven (allowing
the level to return to V
CC
) for minimum power drawn by the termination resistors in this state. In
addition, all other input signals on the FSB should be driven to the inactive state.
BINIT# will not be serviced while the processor is in Stop-Grant state. The event will be latched
and can be serviced by software upon exit from the Stop Grant state.
RESET# causes the processor to immediately initialize itself, but the processor stays in Stop-Grant
state. A transition back to the Normal state occurs with the de-assertion of the STPCLK# signal.
When re-entering the Stop Grant state from the Sleep state, STPCLK# should only be de-asserted
one or more bus clocks after the de-assertion of SLP#.
Figure 6-1. Stop Clock State Machine
STPCLK#
De-asserted
SLP#
De-asserted
1. Normal State
Normal execution.
3. Stop Grant State
BCLK running.
Snoops and interrupts allowed.
5. Sleep State
BCLK running.
No snoops or interrupts allowed.
2. Auto HALT Power Down State
BCLK running.
Snoops and interrupts allowed.
4. HALT/Grant Snoop State
BCLK running.
Service snoops to caches.
STPCLK#
Asserted
SLP#
Asserted
Snoop
Event
Occurs
Snoop
Event
Serviced
HALT Instruction and
HALT Bus Cycle Generated
INIT#, BINIT#, INTR, NMI,
SMI#, RESET#
Snoop Event Serviced
Snoop Event Occurs
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