This is a guide to the hidden diagnostic mode on Casio scientific calculators. Pressing ON at any time exits it.
1. Press SHIFT+7+ON or SHIFT+7+CATALOG+ON. If you see 'DIAGNOSTIC - Press AC', press 9* and complete all tests. If all pixels illuminate, your model has the LCD test only.
2. LCD test: Checks for dead pixels. Repeatedly press SHIFT to switch the display pattern.
3. Software test: Shows software version and checksum. Press AC when the test ends.
4. Contrast: Sets contrast using hexadecimal values. Press LEFT or RIGHT to set and AC to confirm.
5. Key test: Checks for broken keys. Press one at a time: SHIFT, ALPHA, UP, RIGHT, MODE, OPTN/Abs, x^3, LEFT, DOWN. Continue moving along keypad rows horizontally.
6. 'TEST OK' will appear. Press AC to finish.
*On some models, you can also press 6 for a test selection menu or 8 for a battery test.