0:470h                   Timer Overflow flag

 Length: 1 byte

    Keeps track of whether midnight has passed since the machine was
    powered on. See the 4-byte integer counter at 0:46Ch for more details.

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       Notes:         Note that this byte is only a flag. It either has a
                      value of 0 or 1. Therefore, it won't reflect a day
                      change over a two-day period.

                      Use INT 1Ah, Service 00h, to obtain this overflow
                      value. Note that doing so clears this byte.