133
P1DR is initialized to H'00 by a reset and in hardware standby mode. In software standby mode it
retains its previous setting.
7.2.3 Pin Functions in Each Mode
The pin functions of port 1 differ between mode 1, 3 (expanded mode with on-chip ROM
disabled) , modes 5 and 6 (expanded mode with on-chip ROM enabled), and mode 7 (single-chip
mode). The pin functions in each mode are described as follows.
Modes 1 and 3: Address output can be selected for each pin in port 1. Figure 7-2 shows the pin
functions in modes 1 and 3.
Port 1
A (output)
A (output)
A (output)
A (output)
A (output)
A (output)
A (output)
A (output)
7
6
5
4
3
2
1
0
Figure 7-2 Pin Functions in Modes 1 and 3 (Port 1)
Modes 5 and 6: Address output or generic input can be selected for each pin in port 1. A pin
becomes an address output pin if the corresponding P1DDR bit is set to 1, and a generic input pin
if this bit is cleared to 0. Following a reset, all pins are input pins. To use a pin for address output,
its P1DDR bit must be set to 1. Figure 7-3 shows the pin functions in modes 5 and 6.