Datasheet

Intel
®
Pentium
®
4 Processor on 0.13 Micron Process Datasheet 63
Pin Lists and Signal Descriptions
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, refer to the
IA-32 Intel
®
Software Developer’s Manual, Volume 3: System Programming Guide
.
PROCHOT#
Input/
Output
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. This indicates that the processor Thermal
Control Circuit has 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 deasserts PROCHOT#. See Section 6.3 for more details.
NOTE: The PROCHOT# signal functionality has changed from output to
input/output on CPUID 0xF27 and beyond.
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 state.
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]#
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 details on
parity checking of these signals.
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 V
CC
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. These configuration options are described
in the Section 6.1.
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.
Table 4-3. Signal Descriptions (Sheet 6 of 8)
Name Type Description