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8575
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A N/B Maintenance
A N/B Maintenance
5.1 Intel Pentium 4 Processor mPGA478 Socket
Name Type
Description
REQ[4:0]#
Input/
Output
REQ[4:0]# (Request Command) must connect the appropriate
pins of all processor system bus agents. They are asserted by the
current bus owner to define the currently active transaction type.
These signals are source synchronous to ADSTB0#. Refer to the
AP[1:0]# signal description for a details on parity checking of
these signals.
SKTOCC#
Output
SKTOCC# (Socket Occupied) will be pulled to ground by the
processor. System board designers may use this pin to determine
if the processor is present.
SLP#
Input
SLP# (Sleep), when asserted in Stop-Grant state, causes the
processor to enter the Sleep state. During Sleep state, the
processor stops providing internal clock signals to all units,
leaving only the Phase-Locked Loop (PLL) still operating.
Processors in this state will not recognize snoops or interrupts.
The processor will recognize only assertion of the RESET#
signal, deassertion of SLP#, and removal of the BCLK input
while in Sleep state. If SLP# is deasserted, the processor exits
Sleep state and returns to Stop-Grant state, restarting its internal
clock signals to the bus and processor core units. If the BCLK
input is stopped while in the Sleep state the processor will exit
the Sleep state and transition to the Deep Sleep state.
SMI#
Input
SMI# (System Management Interrupt) is asserted
asynchronously by system logic. On accepting a System
Management Interrupt, the processor saves the current state and
enter System Management Mode (SMM). An SMI
Acknowledge transaction is issued, and the processor begins
program execution from the SMM handler.
If SMI# is asserted during the deassertion of RESET# the
processor will tristate its outputs.
STPCLK#
Input
STPCLK# (Stop Clock), when asserted, causes the processor to
enter a low power Stop-Grant state. The processor issues a
Stop-Grant Acknowledge transaction, and stops providing
internal clock signals to all processor core units except the
system bus and APIC units. The processor continues to snoop
bus transactions and service interrupts while in Stop-Grant state.
When STPCLK# is deasserted, the processor restarts its internal
clock to all units and resumes execution. The assertion of
STPCLK# has no effect on the bus clock; STPCLK# is an
asynchronous input.
TCK
Input
TCK (Test Clock) provides the clock input for the processor
Test Bus (also knownas the Test Access Port).
Name Type
Description
TDI
Input
TDI (Test Data In) transfers serial test data into the processor.
TDI provides the serial input needed for JTAG specification
support.
TDO
Output
TDO (Test Data Out) transfers serial test data out of the
processor. TDO provides the serial output needed for JTAG
specification support.
TESTHI[12:8]
TESTHI[5:0]
Input
TESTHI[12:8] and TESTHI[5:0] must be connected to a VCC
power source through a resistor for proper processor operation.
THERMDA
Other
Thermal Diode Anode.
THERMDC
Other
Thermal Diode Cathode.
THERMTRIP#
Output
Assertion of THERMTRIP# (Thermal Trip) indicates the
processor junction temperature has reached a level beyond
which permanent silicon damage may occur. Measurement of
the temperature is accomplished through an internal thermal
sensor which is configured to trip at approximately 135°C.Upon
assertion of THERMTRIP#, the processor will shut off its
internal clocks (thus halting program execution) in an attempt to
reduce the processor junction temperature. To protect the
processor, its core voltage (VCC) must be removed following
the assertion of THERMTRIP#. Once activated, THERMTRIP#
remains latched until RESET# is asserted. While the assertion of
the RESET# signal will de-assert THERMTRIP# , if the
processor’s junction
temperature remains at or above the trip level, THERMTRIP#
will again be asserted after RESET# is de-asserted.
TMS
Input
TMS (Test Mode Select) is a JTAG specification support signal
used by debug tools.
TRDY#
Input
TRDY# (Target Ready) is asserted by the target to indicate that
it is ready to receive a write or implicit writeback data transfer.
TRDY# must connect the appropriate pins of all system bus
agents.
TRST#
Input
TRST# (Test Reset) resets the Test Access Port (TAP) logic.
TRST# must be driven low during power on Reset. This can be
done with a 680 . pull-down resistor.
VCCA
Input
VCCA provides isolated power for the internal processor core
PLLs. Refer to the
Intel® Pentium® 4 Processor in the 478-pin
Package and Intel® 850 Chipset Platform Design Guide
for
complete implementation details.
