"This is I think where the "randomness" is generated - assuming the two counters run at different rates, the comparator would trigger the alarm when the two counters hit the same number at the same time."
I think the above probably isn't right...
The 4060 counters have a built-in oscillator. My guess is that it starts them at the same time and the alarm is when they don't have the same number...when there's drift as compared across the two oscillator sources. And that the clock dial probably changes the speed of one of the oscillators, so they match well enough to stay in sync for the rough desired period.
All that to say the random distribution is probably based on the variability between any two 4060 counters.
I think the above probably isn't right...
The 4060 counters have a built-in oscillator. My guess is that it starts them at the same time and the alarm is when they don't have the same number...when there's drift as compared across the two oscillator sources. And that the clock dial probably changes the speed of one of the oscillators, so they match well enough to stay in sync for the rough desired period.
All that to say the random distribution is probably based on the variability between any two 4060 counters.