Specifications

I-44 EPSON S1C62N82 TECHNICAL HARDWARE
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (I/O Ports)
IOC I/O control register (0FCH D0)
The input or output I/O port mode can be set with this
register.
When 1 is written: Output mode
When 0 is written: Input mode
Reading: Valid
The input or output mode of the I/O port is set in units of
four bits. For instance, IOC sets the mode for P00–P03.
Writing 1 to the I/O control register makes the I/O port
enter the output mode, and writing 0, the input mode.
After an initial reset, the IOC register is set to 0, so the I/O
port is in the input mode.