Intel SL2YM User Manual
Pentium
®
II Processor at 350 MHz, 400 MHz, and 450 MHz
12
Datasheet
For the processor to fully realize the low current consumption of the Stop-Grant, Sleep, and Deep
Sleep states, a Model Specific Register (MSR) bit must be set. For the MSR at 02AH (Hex), bit 26
must be set to a ‘1’ (this is the power on default setting) for the processor to stop all internal clocks
during these modes. For more information, see the Pentium
Sleep states, a Model Specific Register (MSR) bit must be set. For the MSR at 02AH (Hex), bit 26
must be set to a ‘1’ (this is the power on default setting) for the processor to stop all internal clocks
during these modes. For more information, see the Pentium
®
II Processor Developer's Manual
(Order Number 243502).
Due to the inability of processors to recognize bus transactions during the Sleep and Deep Sleep
states, two-way MP systems are not allowed to have one processor in Sleep/Deep Sleep state and
the other processor in Normal or Stop-Grant state simultaneously.
states, two-way MP systems are not allowed to have one processor in Sleep/Deep Sleep state and
the other processor in Normal or Stop-Grant state simultaneously.
2.2.1
Normal State—State 1
This is the normal operating state for the processor.
2.2.2
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.
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.
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 procesor will return to the
AutoHALT state.
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.
When the system deasserts the STPCLK# interrupt, the processor will return execution to the
HALT state.
2.2.3
Stop-Grant State—State 3
The Stop-Grant state on the processor is entered when the STPCLK# signal is asserted.
Since the AGTL+ signal pins receive power from the system bus, these pins should not be driven
(allowing the level to return to V
(allowing the level to return to V
TT
) for minimum power drawn by the termination resistors in this
state. In addition, all other input pins on the system bus should be driven to the inactive state.
BINIT# will be recognized while the processor is in Stop-Grant state. If STPCLK# is still asserted
at the completion of the BINIT# bus initialization, the processor will remain in Stop-Grant mode. If
the STPCLK# is not asserted at the completion of the BINIT# bus initialization, the processor will
return to Normal state.
at the completion of the BINIT# bus initialization, the processor will remain in Stop-Grant mode. If
the STPCLK# is not asserted at the completion of the BINIT# bus initialization, the processor will
return to Normal state.
FLUSH# will not be serviced during Stop-Grant state.
RESET# will cause the processor to immediately initialize itself, but the processor will stay in
Stop-Grant state. A transition back to the Normal state will occur with the deassertion of the
STPCLK# signal.
Stop-Grant state. A transition back to the Normal state will occur with the deassertion of the
STPCLK# signal.
A transition to the HALT/Grant Snoop state will occur when the processor detects a snoop on the
system bus (see
system bus (see
Section 2.2.4
). A transition to the Sleep state (see
Section 2.2.5
) will occur with the
assertion of the SLP# signal.