Datasheet

Dual-Core Intel
®
Itanium
®
Processor 9000 and 9100 Series Datasheet 97
Signals Reference
A.1.24 DEN# (I/O)
The Defer Enable (DEN#) signal is driven on the bus on the second clock of the Request
Phase on the Ab[4]# pin. DEN# is asserted to indicate that the transaction can be
deferred by the responding agent.
A.1.25 DEP[15:0]# (I/O)
The Data Bus ECC Protection (DEP[15:0]#) signals provide optional ECC protection for
Data Bus (D[127:0]#). They are driven by the agent responsible for driving
D[127:0]#. During power-on configuration, bus agents can be enabled for either ECC
checking or no checking.
The ECC error correcting code can detect and correct single-bit errors and detect
double-bit or nibble errors.
A.1.26 DHIT# (I)
The Deferred Hit (DHIT#) signal is driven during the Deferred Phase by the deferring
agent. For read transactions on the bus DHIT# returns the final cache status that would
have been indicated on HIT# for a transaction which was not deferred. DID[9:0]# (I/
O)
DID[9:0]# are Deferred Identifier signals. The requesting agent transfers these signals
by using A[25:16]#. They are transferred on Ab[25:16]# during the second clock of
the Request Phase on all transactions, but Ab[20:16]# is only defined for deferrable
transactions (DEN# asserted). DID[9:0]# is also transferred on Aa[25:16]# during the
first clock of the Request Phase for Deferred Reply transactions.
The Deferred Identifier defines the token supplied by the requesting agent. DID[9]#
and DID[8:5]# carry the agent identifiers of the requesting agents (always valid) and
DID[4:0]# carry a transaction identifier associated with the request (valid only with
DEN# asserted). This configuration limits the bus specification to 32 logical bus agents
with each one of the bus agents capable of making up to 32 requests. Table A-7 shows
the DID encodings.
DID[9]# indicates the agent type. Symmetric agents use 0. Priority agents use 1.
DID[8:5]# indicates the agent ID. Symmetric agents use their arbitration ID.
DID[4:0]# indicates the transaction ID for an agent. The transaction ID must be
unique for all deferrable transactions issued by an agent which have not reported their
snoop results.
The Deferred Reply agent transmits the DID[9:0]# (Ab[25:16]#) signals received
during the original transaction on the Aa[25:16]# signals during the Deferred Reply
transaction. This process enables the original requesting agent to make an identifier
match with the original request that is awaiting completion.
Table A-7. DID[9:0]# Encoding
DID[9]# DID[8:5]# DID[4:0]#
Agent Type Agent ID[3:0] Transaction ID[4:0]