Fujitsu F2MC-8FX Hardware Manual page 522

CHAPTER 27 REAL TIME CLOCK
For instance:
If the sub-clock is found to oscillate at 32.768KHz, the value in frequency fine-tuning register should be set
to 00H so as to generate one-second ticks.
If the sub-clock is found to osillate at 32.769 KHz, the value in frequency fine-tuning register should be set
to 01H so as to generate one-second ticks.
If the sub-clock is found to oscillate at 32.766 KHz, the value in frequency fine-tuning register should be
set to FEH so as to generate one-second ticks.
Notes:
Hardware writing can override software writing in FFTR.
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Figure 27.3-17 subclock of frequency 32768Hz
1 second with 32768 pulses (32768 Hz)
Figure 27.3-18 subclock of Frequency 32769Hz
1 second with 32769 pulses (32769 Hz)
Figure 27.3-19 subclock of Frequency 32766Hz
1 second with 32766 pulses (32766 Hz)