Intel BFCBASE Data Sheet - Page 89

Signal Definitions Table 5-1. Signal Definitions (Sheet 3 of 8) Name D[63:0]# Type I/O Description 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 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 strobes and DBI#. Notes Data Group D[15:0]# D[31:16]# D[47:32]# D[63:48]# DSTBN#/ DSTBP# 0 1 2 3 DBI# 0 1 2 3 DBI[3:0]# 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. I/O 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, within a 16-bit group, would have been asserted electronically low, the bus agent may invert the data bus signals for that particular sub-phase for that 16-bit group. DBI[3:0] Assignment to Data Bus Bus Signal Data Bus Signals DBI0# DBI1# DBI2# DBI3# D[15:0]# D[31:16]# D[47:32]# D[63:48]# DBSY# DEFER# DP[3:0]# DRDY# I/O 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 deasserted. This signal must connect the appropriate pins on all processor FSB agents. I DEFER# is asserted by an agent to indicate that a transaction cannot be guaranteed in-order completion. Assertion of DEFER# is normally the responsibility of the addressed memory or I/O agent. This signal must connect the appropriate pins of all processor FSB agents. I/O DP[3:0]# (Data Parity) provide parity protection for the D[63:0]# signals. They are driven by the agent responsible for driving D[63:0]#, and must connect the appropriate pins of all processor FSB agents. I/O DRDY# (Data Ready) is asserted by the data driver on each data transfer, indicating valid data on the data bus. In a multi-common clock data transfer, DRDY# may be deasserted to insert idle clocks. This signal must connect the appropriate pins of all processor FSB agents. Document Number: 318080-002 89