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Int 70h                 Real-Time Clock               XT-286, AT, Convertible

    Handles the alarm and periodic interrupts for the real-time clock.

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    This is a hardware interrupt (IRQ 8) activated by the CMOS timer
    1024 times per second.


    Note
    This interrupt is available only on the AT and XT-286. The
    real-time clock on the PC Convertible generates an Int 02h
    (Non-Maskable Interrupt) to handle the periodic and alarm
    functions.

    This interrupt provides two services. The first is the periodic
    interrupt that is generated when a time delay is specified. See
    Int 15h, Service 83h (Event Wait), and Service 86h (Wait), for
    more information. The second service is the Alarm Interrupt. When
    the CMOS alarm time matches the current CMOS time, then Int 4Ah
    (User Alarm) is executed.