64
Datasheet
Land Listing and Signal Descriptions
COMP[1:0]
Analog
COMP[1:0] must be terminated to VSS on the system board using precision
resistors.
COMP[3:2]
Analog
For future processor compatibility COMP[3:2] must be terminated to V
TT on
the system board using precision resistors.
COMP[5:4]
Analog
For future processor compatibility, COMP[5:4] must be terminated to VTT
on the system board using precision resistors.
D[63:0]#
Input/
Output
D[63:0]# (Data) are the data signals. These signals provide a 64-bit data
path between the processor FSB agents, and must connect the appropriate
pins/lands on all such agents. The data driver asserts DRDY# to indicate a
valid data transfer.
D[63:0]# are quad-pumped signals and will thus be driven four times in a
common clock period. D[63:0]# are latched off the falling edge of both
DSTBP[3:0]# and DSTBN[3:0]#. Each group of 16 data signals correspond
to a pair of one DSTBP# and one DSTBN#. The following table shows the
grouping of data signals to data strobes and DBI#.
Furthermore, the DBI# signals determine the polarity of the data signals.
Each group of 16 data signals corresponds to one DBI# signal. When the
DBI# signal is active, the corresponding data group is inverted and
therefore sampled active high.
DBI[3:0]#
Input/
Output
DBI[3:0]# (Data Bus Inversion) are source synchronous and indicate the
polarity of the D[63:0]# signals.The DBI[3:0]# signals are activated when
the data on the data bus is inverted. If more than half the data bits, within a
16-bit group, would have been asserted electrically low, the bus agent may
invert the data bus signals for that particular sub-phase for that 16-bit
group.
DBR#
Output
DBR# is used only in processor systems where no debug port is
implemented on the system board. DBR# is used by a debug port
interposer so that an in-target probe can drive system reset. If a debug port
is implemented in the system, DBR# is a no connect in the system. DBR#
is not a processor signal.
DBSY#
Input/
Output
DBSY# (Data Bus Busy) is asserted by the agent responsible for driving
data on the processor FSB to indicate that the data bus is in use. The data
bus is released after DBSY# is de-asserted. This signal must connect the
appropriate pins/lands on all processor FSB agents.
Table 4-3. Signal Description (Sheet 3 of 9)
Name
Type
Description
Quad-Pumped Signal Groups
Data Group
DSTBN#/
DSTBP#
DBI#
D[15:0]#
0
D[31:16]#
1
D[47:32]#
2
D[63:48]#
3
DBI[3:0] Assignment To Data Bus
Bus Signal
Data Bus Signals
DBI3#
D[63:48]#
DBI2#
D[47:32]#
DBI1#
D[31:16]#
DBI0#
D[15:0]#