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Table 25.
Signal Description (Sheet 1 of 9)
Name
MCERR#
MSID[1:0]
PROCHOT#
PWRGOOD
REQ[4:0]#
70
Type
MCERR# (Machine Check Error) is asserted to indicate an
unrecoverable error without a bus protocol violation. It may be
driven by all processor FSB agents.
MCERR# assertion conditions are configurable at a system level.
Assertion options are defined by the following options:
• Enabled or disabled.
Input/
• Asserted, if configured, for internal errors along with IERR#.
Output
• 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, refer to the
®
Intel
64 and IA-32 Architecture Software Developer's Manual,
Volume 3: System Programming Guide.
MSID[1:0] (input) MSID0 is used to indicate to the processor
whether the platform supports 775_VR_CONFIG_05B processors. A
775_VR_CONFIG_05B processor will only boot if it's MSID0 pin is
Input
electrically low. A 775_VR_CONFIG_05A processor will ignore this
input.
MSID1 must be electrically low for the processor to boot.
As an output, PROCHOT# (Processor Hot) will go active when the
processor temperature monitoring sensor detects that the
processor has reached its maximum safe operating temperature.
Input/
This indicates that the processor Thermal Control Circuit (TCC) has
Output
been activated, if enabled. As an input, assertion of PROCHOT# by
the system will activate the TCC, if enabled. The TCC will remain
active until the system de-asserts PROCHOT#. See
for more details.
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
Input
then transition monotonically to a high state. PWRGOOD can be
driven inactive at any time, but clocks and power must again be
stable before a subsequent rising edge of PWRGOOD.
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.
REQ[4:0]# (Request Command) must connect the appropriate
pins/lands of all processor FSB agents. They are asserted by the
Input/
current bus owner to define the currently active transaction type.
Output
These signals are source synchronous to ADSTB0#. Refer to the
AP[1:0]# signal description for a details on parity checking of these
signals.
Land Listing and Signal Descriptions
Description
Section 5.2.4
Datasheet
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