INT 1A - TIME - SET ALARM (AT,XT286,PS)
        AH = 06h
        CH = hour (BCD)
        CL = minutes (BCD)
        DH = seconds (BCD)
Return: CF set on error (alarm already set or clock stopped for update)
        CF clear if successful
Note:   the alarm occurs every 24 hours until turned off, invoking INT 4A each
          time
SeeAlso: INT 4A