Datasheet

Land Listing and Signal Descriptions
74 Datasheet
FERR#/PBE# Output
FERR#/PBE# (floating point error/pending break event) is a
multiplexed signal and its meaning is qualified by STPCLK#. When
STPCLK# is not asserted, FERR#/PBE# indicates a floating-point
error and will be asserted when the processor detects an unmasked
floating-point error. When STPCLK# is not asserted, FERR#/PBE# is
similar to the ERROR# signal on the Intel 387 coprocessor, and is
included for compatibility with systems using MS-DOS*-type
floating-point error reporting. When STPCLK# is asserted, an
assertion of FERR#/PBE# indicates that the processor has a
pending break event waiting for service. The assertion of FERR#/
PBE# indicates that the processor should be returned to the Normal
state. For additional information on the pending break event
functionality, including the identification of support of the feature
and enable/disable information, refer to volume 3 of the Intel
Architecture Software Developer's Manual and the Intel Processor
Identification and the CPUID Instruction application note.
FORCEPR# Input
The FORCEPR# input can be used by the platform to force the
processor (both cores) to activate the Thermal Control Circuit
(TCC). The TCC will remain active until the system deasserts
FORCEPR#.
GTLREF[1:0] Input
GTLREF[1:0] determine the signal reference level for GTL+ input
signals. GTLREF is used by the GTL+ receivers to determine if a
signal is a logical 0 or logical 1.
HIT#
HITM#
Input/
Output
Input/
Output
HIT# (Snoop Hit) and HITM# (Hit Modified) convey transaction
snoop operation results. Any FSB agent may assert both HIT# and
HITM# together to indicate that it requires a snoop stall, which can
be continued by reasserting HIT# and HITM# together.
IERR# Output
IERR# (Internal Error) is asserted by a processor as the result of an
internal error. Assertion of IERR# is usually accompanied by a
SHUTDOWN transaction on the processor FSB. This transaction may
optionally be converted to an external error signal (e.g., NMI) by
system core logic. The processor will keep IERR# asserted until the
assertion of RESET#.
This signal does not have on-die termination. Refer to Section 2.5.2
for termination requirements.
IGNNE# Input
IGNNE# (Ignore Numeric Error) is asserted to the processor to
ignore a numeric error and continue to execute noncontrol floating-
point instructions. If IGNNE# is de-asserted, the processor
generates an exception on a noncontrol floating-point instruction if
a previous floating-point instruction caused an error. IGNNE# has
no effect when the NE bit in control register 0 (CR0) is set.
IGNNE# is an asynchronous signal. However, to ensure recognition
of this signal following an Input/Output write instruction, it must be
valid along with the TRDY# assertion of the corresponding Input/
Output Write bus transaction.
IMPSEL Input
IMPSEL input will determine whether the processor uses a 50 Ω or
60
Ω buffer. This pin must be tied to GND on 50Ω platforms and left
as NC on 60 Ω platforms.
Table 25. Signal Description (Sheet 1 of 9)
Name Type Description