Generally, manufacturers do not document the the means of accessing self-test functions that may be present in their calculators. These functions exist primarily for production testing and repair diagnostics. Hewlett Packard is the only exception, documenting the means of accessing the self-test functions, and encouraging users to execute the self-test functions before returning a calculator for service.
For the most part, these self-test functions can be accessed by pressing some unusual key sequence or pattern. However, I have found a few calculators manufactured by Casio (the fx-65, the fx-6300G, and the fx-6300G's clone, the Radio Shack EC-4033) where there is an internal pad which must be shorted/closed to access the self-test function.
I have been unable to determine how to access the self-test functions for the new Texas Instruments calculators with two line displays.
Last updated December 3, 2004