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Signal Description
R
22 Intel
®
82845 MCH for SDR Datasheet
Signal Name Type Description
HD[63:0]# I/O
AGTL+
Host Data: These signals are connected to the system data bus.
HD[63:0]# are transferred at a 4x rate. Note that the data signals are
inverted on the system bus.
HDSTBP[3:0]#
HDSTBN[3:0]#
I/O
AGTL+
Differential Host Data Strobes: The differential source synchronous
strobes used to transfer HD[63:0]# and DBI[3:0]# at the 4x transfer rate.
Strobe Data Bits
HDSTBP3#, HDSTBN3# HD[63:48]#, DBI3#
HDSTBP2#, HDSTBN2# HD[47:32]#, DBI2#
HDSTBP1#, HDSTBN1# HD[31:16]#, DBI1#
HDSTBP0#, HDSTBN0# HD[15:0]#, DBI0#
HIT# I/O
AGTL+
Hit: This signal indicates that a caching agent holds an unmodified version
of the requested line. HIT# is also driven in conjunction with HITM# by the
target to extend the snoop window.
HITM# I/O
AGTL+
Hit Modified: This signal indicates that a caching agent holds a modified
version of the requested line and that this agent assumes responsibility for
providing the line. HITM# is also driven in conjunction with HIT# to extend
the snoop window.
HLOCK# I
AGTL+
Host Lock: All system bus cycles sampled with the assertion of HLOCK#
and ADS#, until the negation of HLOCK# must be atomic (i.e., no hub
interface or AGP snoopable access to system memory are allowed when
HLOCK# is asserted by the processor).
HREQ[4:0]# I/O
AGTL+
Host Request Command: These signals define the attributes of the
request. In Enhanced Mode HREQ[4:0]# are transferred at 2x rate.
HREQ[4:0]# are asserted by the requesting agent during both halves of
Request Phase. In the first half the signals define the transaction type to a
level of detail that is sufficient to begin a snoop request. In the second half
the signals carry additional information to define the complete transaction
type.
The transactions supported by the MCH host bridge are defined in the
Section 5.1.
HTRDY# O
AGTL+
Host Target Ready: HTRDY# indicates that the target of the processor
transaction is able to enter the data transfer phase.
RS[2:0]# O
AGTL+
Response Status: RS[2:0]# indicates the type of response according to
the following the table:
RS[2:0] Response Type
000 Idle state
001 Retry response
010 Deferred response
011 Reserved (not driven by MCH)
100 Hard Failure (not driven by MCH)
101 No data response
110 Implicit Write back
111 Normal data response