....I wasn't specifically thinking about RPN when I typed that. Does'nt that explain the discrepancies? The notation is imprecise, thus the differing interpretations by operators the Deus Ex Machina who programmed the calculator. The more I think about it, the more "Syntax Error" seems the correct answer. I've rarely seen recommendations for other than explicit ex- pressions in pgming manuals - Other than C, of course... :) Jack --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .