MITSUBISHI MICROCOMPUTERS
3874 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
(1) Ports P0,P1,P3,P73,P74,P81
Direction register
Data bus
Port latch
(2) Port P2
Direction register
Data bus
Port latch
P2 pull-up
Key input interrupt input
(3) Port P40
Port XC switch bit
Direction register
Data bus
Port latch
(4) Port P41
Port XC switch bit
Direction register
Data bus
Port latch
Oscillator
Port P41
Port XC switch bit
Sub-clock generating circuit input
(5) Ports P42,P43,P51,P52,P53
Direction register
Data bus
Port latch
(6) Port P44
Serial I/O1 enable bit
Receive enable bit
Direction register
Data bus
Port latch
INT1–INT5 interrupt input
Fig. 12 Port block diagram (1)
Serial I/O1 input
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