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CHAPTER 6 PORT FUNCTIONS
6.4.3 Operations on input/output port
(1) Output mode
An operation is performed on the output latch contents, and the result is written to the output latch. The output
latch contents are output from the pins.
Once data is written to the output latch, it is retained until data is written to the output latch again.
(2) Input mode
The output latch contents are undefined, but since the output buffer is OFF, the pin status does not change.
Caution In the case of 1-bit memory manipulation instruction, although a single bit is manipulated
the port is accessed as an 8-bit unit. Therefore, on a port with a mixture of input and output
pins, the output latch contents for pins specified as input are undefined, even for bits other
than the manipulated bit.
6.5 Selection of Mask Option
The following mask option is provided in mask ROM version. The PROM versions have no mask options.
Table 6-6. Comparison between Mask ROM Version and PROM Version
Pin Name Mask ROM Version PROM Version
Mask option for pins P60 to P63 Bit-wise-selectable on-chip pull-up resistors No on-chip pull-up resistor