80C18xEA Unused Pin Connections

80C186EA (80C188EA) Minimum Circuit Configuration*
Pin Name	Connection	Pin Name	Connection
Vcc**	+5V +-10%	PCS6:0#	N.C.
Vss**	Ground	T0OUT	N.C.
CLKIN	2x CPU Clock	T1OUT	N.C.
OSCOUT	N.C if using canned oscillator, connected to crystal otherwise	T0IN	pulled high
CLKOUT	N.C.	T1IN	pulled high
RESIN#	reset circuit	INT3:0	Pulled Low
RESOUT	N.C	DRQ0	pulled low
PDTMR	N.C.	DRQ1	pulled low
NMI	pulled low	N.C.	No Connect
TEST#/Busy	pulled high
S2:0#	N.C.
ARDY	pulled high
SRDY	pulled high
Lock#	N.C.
Hold	pulled low
HLDA	N.C.
MCS3#/NCS#	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.