W79E804A/803A/802A
21.3 CPU Clock Rate select
The CPU clock of W79E804 series may be selected by the DIVM register. If DIVM = 00H, the CPU
clock is running at 4 CPU clock pre machine cycle, and without any division from source clock (Fosc).
When the DIVM register is set to N value, the CPU clock is divided by 2(DVIM+1), so CPU clock
frequency division is from 4 to 512. The user may use this feature to set CPU at a lower speed rate for
reducing power consumption. This is very similar to the situation when CPU has entered Idle mode. In
addition this frequency division function affect all peripheral timings as they are all sourcing from the
CPU clock(Fcpu).
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Publication Release Date: July 16, 2007
Revision A2
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