Intel 80C196NU, 8XC196NP, Microcontroller manual Asserted only during external memory writes

8XC196NP, 80C196NU USER’S MANUAL

		Table B-3. Signal Descriptions (Continued)
Name	Type	Description
VCC	PWR	Digital Supply Voltage
		Connect each VCC pin to the digital supply voltage.
VSS	GND	Digital Circuit Ground
		Connect each VSS pin to ground through the lowest possible impedance path.
WR#	O	Write†
		This active-low output indicates that an external write is occurring. This signal is
		asserted only during external memory writes.
		WR# is multiplexed with WRL#.
		† The chip configuration register 0 (CCR0) determines whether this pin
		functions as WR# or WRL#. CCR0.2 = 1 selects WR#; CCR0.2 = 0 selects
		WRL#.
WRH#	O	Write High†
		During 16-bit bus cycles, this active-low output signal is asserted for high-byte
		writes and word writes to external memory. During 8-bit bus cycles, WRH# is
		asserted for all write operations.
		WRH# is multiplexed with BHE#.
		† The chip configuration register 0 (CCR0) determines whether this pin
		functions as BHE# or WRH#. CCR0.2 = 1 selects BHE#; CCR0.2 = 0 selects
		WRH#.
WRL#	O	Write Low†
		During 16-bit bus cycles, this active-low output signal is asserted for low-byte
		writes and word writes. During 8-bit bus cycles, WRL# is asserted for all write
		operations.
		WRL# is multiplexed with WR#.
		† The chip configuration register 0 (CCR0) determines whether this pin
		functions as WR# or WRL#. CCR0.2 = 1 selects WR#; CCR0.2 = 0 selects
		WRL#.
XTAL1	I	Input Crystal/Resonator or External Clock Input
		Input to the on-chip oscillator, internal phase-locked loop circuitry (80C196NU),
		and the internal clock generators. The internal clock generators provide the
		peripheral clocks, CPU clock, and CLKOUT signal. When using an external
		clock source instead of the on-chip oscillator, connect the clock input to XTAL1.
		The external clock signal must meet the VIH specification for XTAL1 (see
		datasheet).
XTAL2	O	Inverted Output for the Crystal/Resonator
		Output of the on-chip oscillator inverter. Leave XTAL2 floating when the design
		uses a external clock source instead of the on-chip oscillator.

B-12