INT 1Ah,  02h (2)        Read Real-Time Clock Time                       many

    Reads the time from the computer's real-time clock.

       On entry:      AH         02h

       Returns:       CF         Set if clock not operating; else cleared
                      CH         Hours (BCD)
                      CL         Minutes (BCD)
                      DH         Seconds (BCD)
                      DL         1 if daylight saving time option; else 0

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       Notes:         All times are in Binary Coded Decimal (BCD). For
                      example, 9:04.12 am will be reported as CX = 0904;
                      DH = 12.

                      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.

                      This service is available only for ATs, XT-286s, and
                      PC Convertibles. Previous machines will report
                      unpredictable results (including the state of the
                      Carry Flag).

                      The daylight saving time option is not reported on
                      ATs with dates prior to 6/10/85.

                      The information returned from this service could
                      differ from the system time. This is because the
                      real-time clock is read once upon system startup,
                      updating the system timer. All other references to
                      time use the system timer. If either the real-time
                      clock is changed (via Service 03h) or the system
                      timer is changed (via Service 01h), the other clock
                      is not changed accordingly.

                      Even though the system uses the system timer for
                      timing information, both the real-time clock and the
                      system timer are updated continuously.