Model: SSR-16
Type: Scientific calculator
Batteries: AA x 4
Lifetime: Introduced: ca. 1976
Terminated: unknown
Notes: A scientific calculator with a fluorescent display, and a slider to switch between modes.

This calculator looks very much almost exactly like the CASIO fx-19. Not exactly because the CASIO fx-19 has 8-digit precision whilst this one has 10 digit precision. I do not know if CASIO also had a 10-digit version that this might be a clone of.

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 this 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.