80C18xXL Unused Pin Connections

80C186XL (80C188XL) Minimum Circuit Configuration*
Pin Name	Connection	Pin Name	Connection
Vcc**	+5V +-10%	TMR OUT0	N.C.
Vss**	Ground	TMR OUT1	N.C.
X1	2x CPU Clock	TMR IN0	pulled high
X2	N.C if using canned oscillator, connected to crystal otherwise	TMR IN1	pulled high
CLKOUT	N.C.	PCS6:0	N.C.
RES#	reset circuit	DRQ0	pulled low
RESET	N.C	DRQ1	pulled low
NMI	pulled low	INT0	pulled low
TEST#/Busy	pulled high	INT1/SELECT#	pulled low
S2:0#	N.C.	INT2/INTA0#	pulled low
ARDY	pulled high	INT3/INTA1#/IRQ	pulled low
SRDY	pulled high	N.C.	No Connect
Lock#	N.C.
Hold	pulled low
HLDA	N.C.
MCS3#/NPS#	N.C.
MCS1#/ERROR#	N.C.
MCS0#/PEREQ	N.C.
MCS2#	N.C.

"Minimum circuit" implies a very basic prototype which allows the boot-up of the processor for testing purposes. It is assumed that none of the internal peripherals are being used. If they are to be used, some of the above connections might need to be changed. Pins missing from the table are assumed to be used in the minimum circuit memory interface. Please see the most current data sheet and User's Manual for a full description of each pin.

Pins specified as "pulled high" or "pulled low" can be strapped instead. Using pull-up or pull-down resistors instead of strapping makes design changes easier and less costly. Typical pull-up or pull-down resistors are 10 Kohms in size. Weak pull-up or pull-down resistors are typically 50 Kohms in size.

All "N.C." pins must remain unconnected.

**All of the Vcc and Vss pins present on the processor package must be connected to +5V +-10% and Ground respectively.