Once upon a time I saw a project where the guy said he was able to calibrate timings based on the internal oscillator in a 12C5xx chip, and that he was able to compensate for the typical RC drift you get with temperature change, voltage change, phase of the moon, etc. Is it actually possible to compensate for the RC drift in your code, or am I crazy? :-) 

Robert Powell
Programmer/Analyst
Hollywood Entertainment
Wilsonville, OR
(503)570-5307