115
8175 N/B MAINTENANCE
8175 N/B MAINTENANCE
5.1 Pentium 4(Willamette/Northwood) mFC-PGA2 478 pin
Name Type
Description
LINT[1:0]
Input
LINT[1:0] (Local APIC Interrupt) must connect the appropriate
pins of all APIC Bus agents. When the APIC is disabled, the
LINT0 signal becomes INTR, a maskable interrupt request
signal, and LINT1 becomes NMI, a nonmaskable interrupt.
INTR and NMI are backward compatible with the signals of
those names on the Pentium processor. Both signals are
asynchronous.
Both of these signals must be software configured via BIOS
programming of the APIC register space to be used either as
NMI/INTR or LINT[1:0]. Because the APIC is enabled by
default after Reset, operation of these pins as LINT[1:0] is the
default configuration.
LOCK#
Input/
Output
LOCK# indicates to the system that a transaction must occur
atomically. This signal must connect the appropriate pins of all
processor system bus agents. For a locked sequence of
transactions, LOCK# is asserted from the beginning of the
first transaction to the end of the last transaction.
When the priority agent asserts BPRI# to arbitrate for ownership
of the processor system bus, it will wait until it observes
LOCK# deasserted. This enables symmetric agents to retain
ownership of the processor system bus throughout the bus
locked operation and ensure the atomicity of lock.
MCERR#
Input/
Output
MCERR# (Machine Check Error) is asserted to indicate an
unrecoverable error without a bus protocol violation. It may be
driven by all processor system bus agents.
MCERR# assertion conditions are configurable at a system
level. Assertion options are defined by the following options:
Enabled or disabled.
Asserted, if configured, for internal errors along with IERR#.
Asserted, if configured, by the request initiator of a bus
transaction after it observes an error.
Asserted by any bus agent when it observes an error in a bus
transaction.
For more details regarding machine check architecture, please
refer to the
IA-32 Software Developer’s Manual, Volume 3:
System Programming Guide
.
PROCHOT#
Output
PROCHOT# will go active when the processor temperature
monitoring sensor detects that the processor has reached its
maximum safe operating temperature.
This indicates that the processor Thermal Control Circuit has
been activated, if enabled.
Name Type
Description
PWRGOOD
Input
PWRGOOD (Power Good) is a processor input. The processor
requires this signal to be a clean indication that the clocks and
power supplies are stable and within their specifications.
‘Clean’ implies that the signal will remain low (capable of
sinking leakage current), without glitches, from the time that the
power supplies are turned on until they come within
specification. The signal must then transition monotonically to a
high illustrates the relationship of PWRGOOD to the RESET#
signal. PWRGOOD can be driven inactive at any time, but
clocks and power must again be stable before a subsequent
rising edge of PWRGOOD. It must also meet the minimum
pulse width and be followed by a 1 to 10 ms RESET# pulse.
The PWRGOOD signal must be supplied to the processor; it is
used to protect internal circuits against voltage sequencing
issues. It should be driven high
throughout boundary scan operation.
RESET#
Input
Asserting the RESET# signal resets the processor to a known
state and invalidates its internal caches without writing back any
of their contents. For a power-on Reset, RESET# must stay
active for at least one millisecond after VCC and BCLK have
reached their proper specifications. On observing active
RESET#, all system bus agents will deassert their outputs within
two clocks. RESET# must not be kept asserted for more than 10
ms while PWRGOOD is asserted.
A number of bus signals are sampled at the active-to-inactive
transition of RESET# for power-on configuration.
This signal does not have on-die termination and must be
terminated on the system board.
RS[2:0]#
Input
RS[2:0]# (Response Status) are driven by the response agent
(the agent responsible for completion of the current transaction),
and must connect the appropriate pins of all processor system
bus agents.
RSP#
Input
RSP# (Response Parity) is driven by the response agent (the
agent responsible for completion of the current transaction)
during assertion of RS[2:0]#, the signals for which RSP#
provides parity protection. It must connect to the appropriate
pins of all processor system bus agents.
A correct parity signal is high if an even number of covered
signals are low and low if an odd number of covered signals are
low. While RS[2:0]# = 000, RSP# is also high, since this
indicates it is not being driven by any agent guaranteeing
correct parity.
