[AT]
Expects: AH    07H
                                                                  
Returns: AH    0
CF    NC (0) no error
CY (1) alarm already operating
                                                                  
Info: Cancels an alarm previously set via INT 1aH 06H.

If you cancel an alarm. you should also restore the original
vector for INT 4aH (it will normally point to an IRET in ROM-BIOS
when unused).

Note: Using fns INT 1aH 06H and 07H as described is quite unusual.  A
more common technique is to patch a TSR into INT 08H and keep an
eye on the system time.  That way you can set up multiple timers,
etc.

See Also: INT 1aH (BIOS Time I/O)
INT 15H 86H (wait; delay a specified number of milliseconds)
INT 15H 8300H (set interval for event wait)
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INT 1aH 07H: Cancel Real-Time Clock Alarm