Datasheet 67
Land Listing and Signal Descriptions
BINIT#
Input/
Output
BINIT# (Bus Initialization) may be observed and driven by all processor FSB
agents and if used, must connect the appropriate pins/lands of all such agents.
If the BINIT# driver is enabled during power-on configuration, BINIT# is
asserted to signal any bus condition that prevents reliable future operation.
If BINIT# observation is enabled during power-on configuration, and BINIT# is
sampled asserted, symmetric agents reset their bus LOCK# activity and bus
request arbitration state machines. The bus agents do not reset their IOQ and
transaction tracking state machines upon observation of BINIT# activation.
Once the BINIT# assertion has been observed, the bus agents will re-arbitrate
for the FSB and attempt completion of their bus queue and IOQ entries.
If BINIT# observation is disabled during power-on configuration, a central agent
may handle an assertion of BINIT# as appropriate to the error handling
architecture of the system.
BNR#
Input/
Output
BNR# (Block Next Request) is used to assert a bus stall by any bus agent
unable to accept new bus transactions. During a bus stall, the current bus
owner cannot issue any new transactions.
BOOTSELECT Input
This input is required to determine whether the processor is installed in a
platform that supports the Pentium 4 processor in the 775-land package. The
processor will not operate if this signal is low. This input has a weak internal
pull-up to V
CC
.
BPM[5:0]#
Input/
Output
BPM[5:0]# (Breakpoint Monitor) are breakpoint and performance monitor
signals. They are outputs from the processor which indicate the status of
breakpoints and programmable counters used for monitoring processor
performance. BPM[5:0]# should connect the appropriate pins/lands of all
processor FSB agents.
BPM4# provides PRDY# (Probe Ready) functionality for the TAP port. PRDY#
is a processor output used by debug tools to determine processor debug
readiness.
BPM5# provides PREQ# (Probe Request) functionality for the TAP port.
PREQ# is used by debug tools to request debug operation of the processor.
These signals do not have on-die termination. Refer to Section 2.5 for
termination requirements.
BPRI# Input
BPRI# (Bus Priority Request) is used to arbitrate for ownership of the processor
FSB. It must connect the appropriate pins/lands of all processor FSB agents.
Observing BPRI# active (as asserted by the priority agent) causes all other
agents to stop issuing new requests, unless such requests are part of an
ongoing locked operation. The priority agent keeps BPRI# asserted until all of
its requests are completed, then releases the bus by de-asserting BPRI#.
BR0#
Input/
Output
BR0# drives the BREQ0# signal in the system and is used by the processor to
request the bus. During power-on configuration this signal is sampled to
determine the agent ID = 0.
This signal does not have on-die termination and must be terminated.
BSEL[2:0] Output
The BCLK[1:0] frequency select signals BSEL[2:0] are used to select the
processor input clock frequency. Table 2-6 defines the possible combinations of
the signals and the frequency associated with each combination. The required
frequency is determined by the processor, chipset and clock synthesizer. All
agents must operate at the same frequency. For more information about these
signals, including termination recommendations refer to Section 2.9.
COMP[1:0] Analog
COMP[1:0] must be terminated to V
SS
on the system board using precision
resistors.
Table 4-3. Signal Description (Sheet 2 of 8)
Name Type Description
To Next Page
Loading...
Need help?
General
