Datasheet
97
Pentium
III Processor for the SC242 at 450 MHz to 1.0 GHz
EMI
I
EMI pins should be connected to baseboard ground and/or to chassis ground
through zero ohm (0
) resistors. The zero ohm resistors should be placed in close
proximity to the processor connector. The path to chassis ground should be short in
length and have a low impedance. These pins are used for EMI management
purposes.
FERR#
O
The FERR# (Floating-point Error) signal is asserted when the processor detects an
unmasked floating-point error. FERR# 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.
FLUSH#
I
When the FLUSH# input signal is asserted, processors write back all data in the
Modified state from their internal caches and invalidate all internal cache lines. At
the completion of this operation, the processor issues a Flush Acknowledge
transaction. The processor does not cache any new data while the FLUSH# signal
remains asserted.
FLUSH# is an asynchronous signal. However, to ensure recognition of this signal
following an I/O write instruction, it must be valid along with the TRDY# assertion of
the corresponding I/O Write bus transaction.
On the active-to-inactive transition of RESET#, each processor samples FLUSH#
to determine its power-on configuration. See the P6 Family of Processors
Hardware Developer’s Manual(Order Number 244001) for details.
HIT#
HITM#
I/O
I/O
The HIT# (Snoop Hit) and HITM# (Hit Modified) signals convey transaction snoop
operation results, and must connect the appropriate pins of all processor system
bus agents. Any such 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#
O
The IERR# (Internal Error) signal 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 system bus. 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#, BINIT#, or
INIT#.
IGNNE#
I
The IGNNE# (Ignore Numeric Error) signal is asserted to force the processor to
ignore a numeric error and continue to execute noncontrol floating-point
instructions. If IGNNE# is deasserted, 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 is set.
IGNNE# is an asynchronous signal. However, to ensure recognition of this signal
following an I/O write instruction, it must be valid along with the TRDY# assertion of
the corresponding I/O Write bus transaction.
INIT#
I
The INIT# (Initialization) signal, when asserted, resets integer registers inside all
processors without affecting their internal (L1 or L2) caches or floating-point
registers. Each processor then begins execution at the power-on Reset vector
configured during power-on configuration. The processor continues to handle
snoop requests during INIT# assertion. INIT# is an asynchronous signal and must
connect the appropriate pins of all processor system bus agents.
If INIT# is sampled active on the active to inactive transition of RESET#, then the
processor executes its Built-in Self-Test (BIST).
LINT[1:0]
I
The LINT[1:0] (Local APIC Interrupt) signals must connect the appropriate pins of
all APIC Bus agents, including all processors and the core logic or I/O APIC
component. 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.
Table 41. Signal Description
(Sheet 4 of 7)
Name
Type
Description