Intel 8XC251SP Pin Conditions in Various Modes, Mode Program, Ale Psen#, Port Memory Pin Pins

SPECIAL OPERATING MODES

Table 12-1. Pin Conditions in Various Modes

Mode	Program	ALE	PSEN#	Port 0	Port 1	Port 2	Port 3
	Memory	Pin	Pin	Pins	Pins	Pins	Pins
Reset	Don’t Care	Weak High	Weak High	Floating	Weak High	Weak High	Weak High
Idle	Internal	1	1	Data	Data	Data	Data
Idle	External	1	1	Floating	Data	Data	Data
Powerdown	Internal	0	0	Data	Data	Data	Data
Powerdown	External	0	0	Floating	Data	Data	Data
ONCE	Don’t Care	Floating	Floating	Floating	Weak High	Weak High	Weak High

C1

C2

XTAL1

OSC

XTAL2

PD#

Clock

Gen

Interrupt,

Serial Port,

Timer Block

CPU

IDL#

A4160-01

Figure 12-2. Idle and Powerdown Clock Control

12-3