Function 2Eh            Set/Reset Verify Flag

    Turns the write verify flag on or off.

        Entry   AH = 2Eh
                AL = 0 | 1   Turn VERIFY off | on
                DL = 0       (DOS 1.x/2.x only)

        Return  Nothing

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    When the verify flag is on, all disk writes are verified provided
    the device driver supports read-after-write verification.

    The verify flag is typically off, because disk errors are rare and
    verification slows writing.

    Note that the flag can be changed by DOS's VERIFY command.