Panasonic MN103001G/F01K - Manual (Page 427)

I/O Ports
15-61
15.14 Port C
15.14.1 Block Diagram
Fig. 15-14-1 shows a block diagram for port C.
Fig. 15-14-1 Port C Block Diagram (PC3 to PC0)
Internal data bus
M
P
X PCn
(n=3,2,1,0)
PCOUT
PCnM
PCMD
PCnO
M
P
X
A23 to A16
Output enable
signal
A19 (n=3)
to A16(n=0)
P... Represents one bit of each register.