INT 1Ah,  0Ah (10)       Read System-Timer Day Counter               some XTs

    Returns the number of days since January 1, 1980 from the System
    Timer.

       On entry:      AH         0Ah

       Returns:       CF         Set if error; else cleared
                      CX         Number of days since January 1, 1980

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       Notes:         The system timer is the timer set when the system is
                      started. This date is temporary, lasting only as
                      long as the system is turned on.

                      This service is available only for XTs dated 1/10/86
                      and later. ATs and XT-286s will set the Carry Flag,
                      thus reporting an error state. Previous machines
                      will report unpredictable results (including the
                      state of the Carry Flag).