Bit 7 of the seconds register in a 1307 is the "CH" bit, or "Clock Halt".

If that bit is set, you could easily get values of 90+ seconds.
Except that if that bit is set, the clock isn't running.

On initial power-up of a 1307 the internal registers are "undefined", so you actually have to set that bit to 0 to make sure the clock is running.

But if it's counting, and you get 90+ .... OMG.
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