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The response agent returns a Normal without data response for a write transaction with
•
HITM# and DEFER# deasserted in the Snoop Phase, when the addressed agent samples
TRDY# active and DBSY# inactive, and it is ready to complete the transaction.
The response agent must return an Implicit writeback response in the next clock for a read
•
transaction with HITM# asserted in the Snoop Phase, when the addressed agent samples
TRDY# active and DBSY# inactive.
The addressed agent must return an Implicit writeback response in the clock after the
•
following sequence is sampled for a write transaction with HITM# asserted:
— TRDY# active and DBSY# inactive
— followed by TRDY# inactive
— followed by TRDY# active and DBSY# inactive
The defer agent can return a Deferred, Retry, or Split response anytime for a read
•
transaction with HITM# deasserted and DEFER# asserted.
The defer agent can return a Deferred or Retry response when it samples TRDY# active
•
and DBSY# inactive for a write transaction with HITM# deasserted and DEFER# asserted.
A.1.46. RSP# (I)
The RSP# signal is the Response Parity signal. It is driven by the response agent during assertion
of RS[2:0]#. RSP# provides parity protection for RS[2:0]#.
A correct parity signal is high if an even number of covered signals are low and low if an odd
number of covered signals are low. During Idle state of RS[2:0]# (RS[2:0]#=000), RSP# is also
high since it is not driven by any agent guaranteeing correct parity.
Pentium Pro processor bus agents can check RSP# at all times and if a parity error is observed,
treat it as a protocol violation error. If the BINIT# driver is enabled during configuration, the
agent observing RSP# parity error can assert BINIT#.
A.1.47. SMI# (I)
System Management Interrupt is asserted asynchronously by system logic. On accepting a Sys-
tem Management Interrupt, the Pentium Pro processor saves the current state and enters SMM
mode. It issues an SMI Acknowledge Bus transaction and then begins program execution from
the SMM handler.
A.1.48. SMMEM# (I/O)
The SMMEM# signal is the System Management Mode Memory signal. It is driven on the sec-
ond clock of the Request Phase on the EXF4#/Ab7# signal. It is asserted by the Pentium Pro
processor to indicate that the processor is in System Management Mode and is executing out of
SMRAM space.
SIGNALS REFERENCE
A-21
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