NEC PD78F9488 - Manual (Page 90)

CHAPTER 4 PORT FUNCTIONS
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User’s Manual U15331EJ4V1UD
4.2.8 Port 8
This is an 8-bit I/O port with an output latch. Only the bits for which the port function is selected can be used, by
using a mask option in the µPD789488 and 789489 or port function register 8 (PF8) in the µPD78F9488 and 78F9489.
Port 8 can be specified in the input or output mode in 1-bit units by using port mode register 8 (PM8).
RESET input sets this port to input mode.
Figure 4-14 shows a block diagram of port 8.
Figure 4-14. Block Diagram of P80 to P87
RD
WR PORT
WR PM
Output latch
(P80 to P87)
PM80 to PM87
P80 to P87
Internal bus
Selector
PM: Port mode register
RD:
Port 8 read signal
WR: Port 8 write signal