MiTAC 7521 PLUS/N service manual Cpuclk, Hlock#, Hit#, Hitm#, Htrdy#, Cpurst#, Igne#, Cpuslp#

7521Plus / N N/B MAINTENANCE

5.Pin Descriptions Of Major Components

5.2SiS630S Slot 1/Socket 370 2D/3D Ultra-AGP™ Single Chipset

Host Bus Interface

Name	Tolerance	Power	Type		Description
		Plane	Attr
CPUCLK	3.3V/5V	MAIN	I	Host Clock :
ADS#	1.5V	MAIN	I/O	Address Strobe : Address Strobe is driven by CPU to
			GTL+	indicate the start of a CPU bus cycle.
HREQ[4:0]#	1.5V	MAIN	I/O	Request Command: HREQ[4:0]# are used to define
			GTL+	each transaction type during the clock when ADS# is
				asserted and the clock after ADS# is asserted.
BREQ0#	1.5V	MAIN	O	Symmetric Agent Bus Request: BREQ0# is driven
			GTL+	by the symmetric agent to request for the bus.
BNR#	1.5V	MAIN	I/O	Block Next Request: This signal can be driven
			GTL+	asserted by any bus agent to block further requests
				being pipelined.
HLOCK#	1.5V	MAIN	I	Host Lock : CPU asserts HLOCK# to indicate the
			GTL+	current bus cycle is locked.
HIT#	1.5V	MAIN	I/O	Keeping a Non-Modified Cache Line:
			GTL+
HITM#	1.5V	MAIN	I/O	Hits a Modified Cache Line: Hit Modified indicates
			GTL+	the snoop cycle hits a modified line in the L1 cache of
				CPU.
DEFER#	1.5V	MAIN	O	Defer Transaction Completion: SiS630 will use this
			GTL+	signal to indicate a retry response to host bus.
RS[2:0]#	1.5V	MAIN	O	Response Status: RS[2:0]# are driven by the response
			GTL+	agent to indicate the transaction response type. The
				following shows the response type.
				RS[2:0]	Response
				000	Idle State
				100	Reserved
				001	Retry
				101	No data
				010	Reserved
				110	Implicit Write-back
				011	Reserved
				111	Normal Data
HTRDY#	1.5V	MAIN	I/O	Target Ready: During write cycles, response agent
			GTL+	will drive TRDY# to indicate the agent is ready to
				accept data.
DRDY#	1.5V	MAIN	I/O	Data Ready: DRDY# is driven by the bus owner
			GTL+	whenever the data is valid on the bus.
DBSY#	1.5V	MAIN	I/O	Data Bus Busy: Whenever the data is not valid on the
			GTL+	bus with DRDY# is deserted, DBSY# is asserted to
				hold the bus.

Name	Tolerance	Power	Type		Description
		Plane	Attr
BPRI#	1.5V	MAIN	O		Priority Agent Bus Request: BPRI# is driven by the
			GTL+	priority agent that wants to request the bus.
					BPRI# has higher priority than BREQ0# to access a bus.
CPURST#	1.5V	MAIN	O		Host Bus Reset: CPURST# is used to keep all the bus
			GTL+		agents in the same initial state before valid cycles issued.
HA[31:3]#	1.5V	MAIN	I/O		Host Address Bus :
			GTL+
HD[63:0]#	1.5V	MAIN	I/O		Host Data Bus :
			GTL+
FERR#	1.5V~5V	MAIN	I		Floating Point Error : CPU will assert this signal upon a
					floating point error occurring.
IGNE#	1.5V~5V	MAIN	OD		Ignore Numeric Error : IGNE# is asserted to inform CPU
					to ignore a numeric error.
					Speed Trap for PII : This pin will be forced to voltage
					level according to the input value of MD41 or APC0h.4
					during system reset period.
NMI	1.5V~5V	MAIN	OD		Non-Maskable Interrupt : A rising edge on NMI will
					trigger a non-maskable interrupt to CPU. Speed Trap for
					PII : This pin will be forced to voltage level according to
					the input value of MD44 or APC0h.7 during system reset
					period.
INTR	1.5V~5V	MAIN	OD		Interrupt Request : High-level voltage of this signal
					indicates the CPU that there is outstanding interrupt(s)
					needed to be serviced.
					Speed Trap for PII : This pin will be forced to voltage
					level according to the input value of MD43 or APC0h.6
					during system reset period.
CPUSLP#	1.5V~5V	MAIN	OD		CPU Sleep : SiS630 can optionally assert CPUSLP# to
					force the CPU into deep sleep mode when going to S2 state.
STPCLK#	1.5V~5V	MAIN	OD		Stop Clock : STPCLK# will be asserted to inhibit or
					throttle CPU activities upon a pre-defined power
					management event occurs.
SMI#	1.5V~5V	MAIN	OD		System Management Interrupt : SMI# will be asserted
					when a pre-defined power management event occurs.

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