INT 1aH 00H: Read System Clock (Ticks)

                                                              [PC] [XT] [AT]
 Expects: AH    00H
 Returns: AL    0 if timer has not overflowed past 24 hrs since reset
          CX,DX Ticks since last reset; CX is high, DX is low
    Info: Obtains the current tick-count.  The tick count is stored at
          0040:006E in the BIOS Data Area.  It is incremented about once
          every 55 ms by INT 08H:

            clock updates at 1193180/65536 (about 18.2) ticks per second.
            counts per second ≈ 18
            counts per minute ≈ 1092
            counts per hour   ≈ 65543
            counts per day    ≈ 1573040

See Also: INT 1aH (BIOS Time I/O)
          DOS fn 2cH (get system time)
          ROM-BIOS Functions