Analysis of information sources in references of the Wikipedia article "Hacking of consumer electronics" in English language version.
[…] I own a modified Casio fx-180P with hyperbolic functions retrofitted. […] Comparing the functions of my fx-180P calculator with a friend's [fx-3500P or fx-3600P], I realized that although both calculators looked completely different and had a rather different keyboard arrangement, the functional assignments for each of the keys were the same. My fx-180P lacked a "hyp" key and the corresponding six functions […] This observation made me open the cases and […] reverse-engineer the PCB traces between the controller and the keyboard matrix, and add two wires to emulate the "missing" key […] I retrofitted a push button in a corner […] at the top of the case […]
[…] I own a modified Casio fx-180P with hyperbolic functions retrofitted. […] Comparing the functions of my fx-180P calculator with a friend's [fx-3500P or fx-3600P], I realized that although both calculators looked completely different and had a rather different keyboard arrangement, the functional assignments for each of the keys were the same. My fx-180P lacked a "hyp" key and the corresponding six functions […] This observation made me open the cases and […] reverse-engineer the PCB traces between the controller and the keyboard matrix, and add two wires to emulate the "missing" key […] I retrofitted a push button in a corner […] at the top of the case […]