NEC PD78078 用户手册

Port 5 is an 8-bit input/output port with output latch.  P50 to P57 pins can specify the input mode/output mode in

1-bit units with the port mode register 5 (PM5).  When P50 to P57 pins are used as input ports, an on-chip pull-up

resistor can be connected to them in 8-bit units with a pull-up resistor option register L (PUOL).

Port 5 can drive LEDs directly.

Dual-functions include address bus function in external memory expansion mode.

RESET input sets port 5 to input mode.

Figure 6-12 shows a block diagram of port 5.

PUO :  Pull-up resistor option register

PM

:  Port mode register

RD

:  Port 5 read signal

WR :  Port 5 write signal

P-ch

WR

PM

WR

PORT

RD

WR

PUO

V

DD

Selector

PUO5

Output Latch
(P50 to P57)

PM50 to PM57

Internal bus

P50/A8 to
P57/A15