Intel 8XC251SP User Manual
12-3
SPECIAL OPERATING MODES
Figure 12-2. Idle and Powerdown Clock Control
Table 12-1. Pin Conditions in Various Modes
Mode
Program
Memory
ALE
Pin
PSEN#
Pin
Port 0
Pins
Port 1
Pins
Port 2
Pins
Port 3
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
A4160-01
XTAL2
XTAL1
C1
C2
OSC
PD#
Clock
Gen
IDL#
Interrupt,
Serial Port,
Timer Block
CPU