CASIO fx‑19


Brand: CASIO
Model: fx-19
Type: Scientific calculator
Picture: CASIO fx-19
Batteries: AA x 4
Lifetime: Introduced: ca. 1976
Terminated: unknown
Notes: A CASIO scientific calculator with a fluorescent display, a slider to switch between modes, and capable of calculating with fractions and statistical operations.

Quite similar to the Casio fx-29. As far as I can tell the main difference is the layout, the casing and the number of batteries.

The workings of the 'xy'-key might be puzzling to users of this calculator. When you enter a (positive) number and press the 'xy'-key an intermediate result is shown, being the natural log 'ln' of the number entered. To obtain its power enter the value for y and press the '='-key. My guess is that this calculator uses the formula xy = e(y · ln x). This works nicely for positive values of x but will result in an error when x is zero or less. Not a big problem because powers of negavive numbers behave counter intuitive anyway (producing non-complex results only for integer values of y or fractional values of y with an odd denominator).

This calculator has separate keys for the exponent and the constant π instead of the combined key of most other scientific calculators by CASIO (where the "EXP"-key will enable you to enter the numbers exponent when you first enter digits, and will otherwise enter the constant π).

There's also no "INV"-key, only an "arc"-key for the inverse trigonometric functions. Statistical functions are available when the mode selector slider is all the way to the right.


A power adapter.