INT 1A - TIME - GET SYSTEM TIME
        AH = 00h
Return: CX:DX = number of clock ticks since midnight
        AL = midnight flag, nonzero if midnight passed since time last read
Notes:  there are approximately 18.2 clock ticks per second, 1800B0h per 24 hrs
        IBM and many clone BIOSes set the flag for AL rather than incrementing
          it, leading to loss of a day if two consecutive midnights pass
          without a request for the time (e.g. if the system is on but idle)
SeeAlso: AH=02h,INT 21/AH=2Ch