50
Datasheet
Signal Definitions
IERR#
O
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 front side 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#.
This signal does not have on-die termination and must be terminated
at the end agent.
3
IGNNE#
I
IGNNE# (Ignore Numeric Error) 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 (CR0) 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.
3
INIT#
I
INIT# (Initialization), when asserted, resets integer registers inside all
processors without affecting their internal 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 front side 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).
3
LINT[1:0]
I
LINT[1:0] (Local APIC Interrupt) must connect the appropriate pins of all
front side bus agents. When the APIC functionality is disabled, the LINT0/
INTR signal becomes INTR, a maskable interrupt request signal, and
LINT1/NMI 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.
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.
3
LOCK#
I/O
LOCK# indicates to the system that a transaction must occur atomically.
This signal must connect the appropriate pins of all processor front side
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 front side bus, it will wait until it observes LOCK# deasserted.
This enables symmetric agents to retain ownership of the processor front
side bus throughout the bus locked operation and ensure the atomicity of
lock.
4
Table 4-1. Signal Definitions (Sheet 6 of 10)
Name
Type
Description
Notes