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INT 1Ah,  08h (8)        Set Clock-Activated Power-On Mode        Convertible

    Sets the time at which the computer will automatically power on.

       On entry:      AH         08h
                      CH         Hours (BCD)
                      CL         Minutes (BCD)
                      DH         Seconds (BCD)

       Returns:       CF         Set if clock not operating or alarm already
                                 set; else cleared

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       Notes:         This service is available only for the PC
                      Convertible. Previous machines will report
                      unpredictable results (including the state of the
                      Carry Flag). ATs, XT-286s, and the PS/2 family will
                      set the Carry Flag, thus reporting an error state.

                      All dates are in Binary Coded Decimal (BCD). For
                      example, June 1, 1985 will be set as CX = 1985; DX =
                      0601.

                      The real-time clock is the clock that runs even when
                      the computer is turned off. A CMOS battery is used
                      so that, even while the computer is off, the date,
                      time, and alarm time are maintained.

                      After this service is executed, the machine will
                      automatically power on as soon as the hour, minute,
                      and second specified match the time on the real-time
                      clock date. If the system is already on, then INT
                      4Ah (User Alarm) will be executed.

                      If the system is on, the alarm interrupt (INT 4Ah)
                      will continue to occur every 24 hours at the
                      specified time until it is reset via Service 07h
                      (Reset Real-Time Clock Alarm). Only one alarm time
                      can be active at a time.