No serial or code needed. Works with 83xx and 88xx, not sure about other models.
This is a hebrew/jewish calendar with many additional features listed below.

    * Quick-jump function to the current system date, a month or a year
    * Omer count
    * Configuration options
          o Diaspora/Israel
          o Begin of shabbat: minutes before sunset on Friday
          o End of shabbat: minutes after sunset on Saturday or degrees below horizon
          o Time format (12/24 hour)
          o Zmanim
                + Alot Hashachar (16.1 degrees below horizon, 72 minutes before sunrise, 90 minutes before sunrise)
                + Earliest Tallit (11 or 10.2 degrees below horizon)
                + Hanetz Hachama
                + Kriat Shema (GR"O or M"A)
                + Tefila (GR"O or M"A)
                + Chatzot (GR"O or M"A)
                + Mincha Gedola (GR"O or M"A)
                + Mincha K'tana (GR"O or M"A)
                + Plag Hamincha (GR"O or M"A)
                + Shkiat Hachama
                + Tzait Hakochavim (72 minutes after sunset; 5.95, 6.5, 7.0, 7.08, 7.5 or 8.5, 8.75, 10.0 degrees below horizon)
          o Daylight Savings Time
          o Location for times calculation - over 1000 locations predefined; own locations can be added easily