80C18xEB Unused Pin Connections

80C186EB (80C188EB) Minimum Circuit Configuration*
Pin Name	Connection	Pin Name	Connection
Vcc**	+5V +-10%	T0OUT	N.C.
Vss**	Ground	T1OUT	N.C.
CLKIN	2x CPU Clock	T0IN	pulled high
OSCOUT	N.C if using canned oscillator, connected to crystal otherwise	T1IN	pulled high
CLKOUT	N.C.	INT4,1,0	pulled low
RESIN#	reset circuit	INT2/ INTA0#	pulled low
RESOUT	N.C	INT3/ INTA1#	pulled low
PDTMR	N.C.	P2.6,7	pulled low
NMI	pulled low	CTS0#	pulled low
TEST#/Busy	pulled high	P2.4/CTS1#	pulled low
A19/S6/ONCE#	weekly pulled high	TXD0	N.C.
S2:0#	N.C.	P2.1/TXD1	N.C.
READY	pulled high	RXD0	pulled low
Lock#	N.C.	P2.0/RXD1	pulled low
Hold	pulled low	P2.5/BCLK0	pulled low
HLDA	N.C.	P2.2/BCLK1	pulled low
NCS#	N.C.	P2.3/SINT1	N.C.
ERROR#	strap to Vcc (if 80C187 is not present)	N.C.	No Connect
PEREQ	strap to Vss (if 80C187 is not present)
P1.0/GCS0#:P1.7/GCS7#	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.