MiTAC 7521 PLUS/N service manual Ghi#, Hit#, Hitm#, Ierr#, Ignne#, Init#, Intr, Lock#, Nmi

7521Plus / N N/B MAINTENANCE

5. Pin Descriptions Of Major Components

5.1 Pentium III/Celeron FC-PGA2 CPU

Alphabetical Signal Reference

Signal Name	I/O	Signal Description
GHI#	I	The GHI# signal controls which operating mode bus ratio is selected
	1.5V	in a mobile Pentium III processor featuring Intel SpeedStep
	Tolerant	technology. On the processor featuring Intel SpeedStep technology,
		this signal is latched when BCLK restarts in Deep Sleep state and
		determines which of two bus ratios is selected for operation. This
		signal is ignored when the processor is not in the Deep Sleep state.
		This signal is a "Don't Care" on processors that do not feature Intel
		SpeedStep technology. This signal has an on-die pull-up to VccT and
		should be driven with an Open-drain driver with no external pull-up.
HIT#, HITM#	I/O	The HIT# (Snoop Hit) and HITM# (Hit Modified) signals convey
	GTL+	transaction snoop operation results, and must be connected to the
		appropriate pins/balls on both agents on the system bus.
		Either bus agent can 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 the processor as the
	1.5V	result of an internal error.Assertion of IERR# is usually accompanied
	Tolerant	by a SHUTDOWN transaction on the system bus.
	Open-	This transaction may optionally be converted to an external error
	drain	signal (e.g., NMI) by system logic. The processor will keep IERR#
		asserted until it is handled in software or with the assertion of
		RESET#, BINIT, or INIT#.
IGNNE#	I	The IGNNE# (Ignore Numeric Error) signal is asserted to force the
	1.5V	processor to ignore a numeric error and continue to execute non-
	Tolerant	control floating-point instructions. If IGNNE# is deasserted, the
		processor freezes on a non-control floating-point instruction if a
		previous instruction caused an error. IGNNE# has no affect when the
		NE bit in control register 0 (CR0) is set.
INIT#	I	The INIT# (Initialization) signal is asserted to reset integer registers
	1.5V	inside the processor without affecting the internal (L1 or L2) caches
	Tolerant	or the floating-point registers. The processor 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 input.
		If INIT# is sampled active on RESET#'s active-to-inactive transition,
		then the processor executes its built-in self test (BIST).

Signal Name	I/O	Signal Description
INTR	I	The INTR (Interrupt) signal indicates that an external interrupt has
	1.5V	been generated. INTR becomes the LINT0 signal when the APIC is
	Tolerant	enabled. The interrupt is maskable using the IF bit in the EFLAGS
		register. If the IF bit is set, the processor vectors to the interrupt
		handler after completing the current instruction execution. Upon
		recognizing the interrupt request, the processor issues a single
		Interrupt Acknowledge (INTA) bus transaction. INTR must remain
		active until the INTA bus transaction to guarantee its recognition.
LINT[1:0]	I	The LINT[1:0] (Local APIC Interrupt) signals must be connected to
	1.5V	the appropriate pins/balls of all APIC bus agents, including the
	Tolerant	processor and the system logic or I/O APIC component. When APIC
		is disabled, the LINT0 signal becomes INTR, a maskable interrupt
		request signal, and LINT1 becomes NMI, a non-maskable interrupt.
		INTR and NMI are backward compatible with the same signals for
		the Pentium processor. Both signals are asynchronous inputs.
		Both of these signals must be software configured by programming
		the APIC register space to be used either as NMI/INTR or LINT[1:0]
		in the BIOS. If the APIC is enabled at reset, then LINT[1:0] is the
		default configuration.
LOCK#	I/O	The LOCK# (Lock) signal indicates to the system that a sequence of
	GTL+	transactions must occur atomically. This signal must be connected to
		the appropriate pins/balls on both agents on the system bus. For a
		locked sequence of transactions, LOCK# is asserted from the
		beginning of the first transaction through the end of the last
		transaction.
		When the priority agent asserts BPRI# to arbitrate for bus ownership,
		it waits until it observes LOCK# deasserted. This enables the
		processor to retain bus ownership throughout the bus locked operation
		and guarantee the atomicity of lock.
NMI	I	The NMI (Non-Maskable Interrupt) indicates that an external
	1.5V	interrupt has been generated. NMI becomes the LINT1 signal when
	Tolerant	the APIC is disabled. Asserting NMI causes an interrupt with an
		internally supplied vector value of 2. An external interrupt-
		acknowledge transaction is not generated. If NMI is asserted during
		the execution of an NMI service routine, it remains pending and is
		recognized after the IRET is executed by the NMI service routine. At
		most, one assertion of NMI is held pending. NMI is rising edge
		sensitive.

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