Normal State-State 1; Autohalt Power Down State-State 2; Clock Control State Machine - Intel CELERON 1.10 GHZ Datasheet

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Intel Celeron Processor up to 1.10 GHz
2.2.1 Normal State—State 1
This is the normal operating state for the processor.
2.2.2 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 (Order Number 243192) for more information.
FLUSH# will be serviced during the AutoHALT state, and the processor will return to the
AutoHALT state.
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.
Figure 1. Clock Control State Machine
2. Auto HALT Power Down State
BCLK running.
Snoops and interrupts allowed.
4. Auto HALT Power Down State
BCLK running.
Snoops and interrupts allowed.
16
STPCLK# Deasserted
and Stop Grant entered
Snoop Snoop
from Auto HALT.
Event Event
Occurs Serviced
HALT Instruction and
HALT Bus Cycle generated
INIT#, BINIT#, INTR, SMI#,
RESET#
Snoop event occurs
Snoop event serviced
1. Normal State
Normal execution.
STPCLK# STPCLK#
asserted deasserted
3. Stop Grant State
BCLK running.
Snoops and interrupts allowed.
SLP# SLP#
asserted deasserted
5. Sleep State
BCLK running.
Snoops and interrupts allowed.
BCLK BCLK
input input
stopped restarted
6. Deep Sleep State
BCLK stopped.
No Snoops and interrupts allowed.
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