Depending on your application, you might be able to use one of the timers, such as the Olympic timer, or the high resolution timer. All without a RTC chip. A few shown here:
http://www.picbasic.co.uk/forum/content.php?r=77
Or DT_INTS for 1/100 of a second http://darreltaylor.com/DT_INTS-18/elapsed.html
Walter
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