Casio College fx-80 : which IC hides inside ?

[matthiaspaul]

(06-02-2016 05:47 PM)jebem Wrote:  In those old times Casio used to release several different models sharing the same processor and firmware, only changing the keyboard labeling and sometimes using a different display.

I can confirm this. I own a modified Casio fx-180P with hyperbolic functions retrofitted.

Comparing the functions of my fx-180P calculator with a friend's Casio calculator of the same time (I don't recall the model number any more), 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, but otherwise the documented technical data and "programming" features were identical.
This observation made me open the cases and when both were found using the same processor, reverse-engineer the PCB traces between the controller and the keyboard matrix, and add two wires to emulate the "missing" key. Shorting these wires, my calculator actually performed the hyperbolic functions, so I retrofitted a push button in a corner of the inclined plane at the top of the case (the only place leaving enough room inside to add the button).

Greetings,

Matthias

[EDIT: http://mycalcdb.free.fr/main.php?l=0&id=390
Not my site, but it nicely shows the internals of a fx-180P including the keyboard, processor and the available space next to the battery case, where I retrofitted the button in my unit.]