MiTAC 7521 PLUS/N service manual Sdclk, We#, Sras#, Scas#, Cke, Pciclk, Par, Frame#, Irdy#

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
		Plane	Attr
INIT#	1.5V~5V	MAIN	OD
A20M#	1.5V~5V	MAIN	OD

Description

Initialization : INIT is used to re-start the CPU without flushing its internal caches and registers. In Pentium II platform it is active high. This signal requires an external pull-up resistor tied to 3.3V.

Address 20 Mask : When A20M# is asserted, the CPU A20 signal will be forced to "0".

Speed Trap for PII : This pin will be forced to voltage level according to the input value of MD42 or APC0h.5 during system reset period.

Name	Tolerance	Power	Type	Description
		Plane	Attr
AD[31:0]	3.3V/5V	MAIN	I/O	PCI Address /Data Bus:
				In address phase:
				1.When the SiS Chip is a PCI bus master, AD[31:0]
				are output signals.
				2.When the SiS Chip is a PCI target, AD[31:0] are
				input signals.
				In data phase:
				1.When the SiS Chip is a target of a memory
				read/write cycle, AD[31:0] are floating.
				2.When the SiS Chip is a target of a configuration or

DRAM Controller

Name	Tolerance	Power	Type	Description
		Plane	Attr
SDCLK	3.3V/5V	MAIN	I	SDRAM Clock Input
MD[63:0]	3.3V	MAIN	I/O	System Memory Data Bus
MA[14:0]	3.3V	MAIN	O	System Memory Address Bus
CSA[5:0]#	3.3V	MAIN	O	SDRAM Chip Select
CSB[5:0]#	3.3V	MAIN	O	SDRAM Chip Select Signals
				(Duplicated Copy)
DQM[7:0]#	3.3V	MAIN	O	SDRAM Input/Output Data Mask
WE#	3.3V	MAIN	O	SDRAM Write Enable
SRAS#	3.3V	MAIN	O	SDRAM Row Address Strobe
SCAS#	3.3V	MAIN	O	SDRAM Column Address Strobe
CKE	3.3V	AUX	O	SDRAM Clock Enable
				During Suspend-to-DRAM mode
				(ACPI S2 or S3 state), SDRAM can
				be put into self-refresh mode by
				asserting CKE.

PCI Interface

Name	Tolerance	Power	Type	Description
		Plane	Attr
PCICLK	3.3V/5V	MAIN	I	PCI Clock : The PCICLK input provides the
				fundamental timing and the internal operating
				frequency for the SiS Chip. It runs at the same
				frequency and skew of the PCI local bus.
C/BE[3:0]#	3.3V/5V	MAIN	I/O	PCI Bus Command and Byte Enables: PCI Bus
				Command and Byte Enables define the PCI command
				during the address phase of a PCI cycle, and the PCI
				byte enables during the data phases. C/BE[3:0]#
				are outputs when the SiS Chip is a PCI bus master and
				inputs when it is a PCI slave.

				an I/O cycle, AD[31:0] are output signals in a
				read cycle, and input signals in a write cycle.
PAR	3.3V/5V	MAIN	I/O Parity : SiS630 drives out Even Parity covering AD[31:0] and C/BE[3:0]#. It
				does not check the input parity signal.
FRAME#	3.3V/5V	MAIN	I/O	Frame#: FRAME# is an output when the SiS Chip is a PCI bus master. The SiS
				Chip drives FRAME# to indicate the beginning and duration of an access.
				When the SiS Chip is a PCI slave device, FRAME# is an input signal.
IRDY#	3.3V/5V	MAIN	I/O	Initiator Ready : IRDY# is an output when the SiS
				Chip is a PCI bus master. The assertion of IRDY# indicates the current PCI bus
				master's ability to
				complete the current data phase of the transaction. For a read cycle, IRDY#
				indicates that the PCI bus
				master is prepared to accept the read data on the following rising edge of the
				PCI clock. For a write
				cycle, IRDY# indicates that the bus master has driven valid data on the PCI
				bus. When the SiS Chip is a
				PCI slave, IRDY# is an input pin.
TRDY#	3.3V/5V	MAIN	I/O	Target Ready : TRDY# is an output when the SiS
				Chip is a PCI slave. The assertion of TRDY# indicates the target agent's ability
				to complete the current data phase of the transaction. For a read cycle, TRDY#
				indicates that the target has driven valid data onto the PCI bus. For a write
				cycle, TRDY# indicates that the target is prepared to accept data from the PCI
				bus. When the SiS Chip is a PCI master, it is an input pin.

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