casio fx-911m

another of many solar powered models. some of these glass fronted solar design were quite stylish.

the so-called c-power system here is assisted by an internal GR927 battery. it looks like users were not supposed to replace the battery, but this one has not lasted the time.

a straightforward 8 digit scientific, only hyperbolics seem more than usual. why was it that casio were fascinated by hyperbolic functions. these were not required as part of college curriculum in the 80's nor did other manufacturers like ti or hp put them on their standard models. ironically, it may be that early hp models could compute internally sinh and cosh for the purpose of calculating log and exp (see cordic methods) but i dont think casios algorithms were cordic derived.