here is a rather splendid ten digit scientific from 1975.
it has the early casio baroque style of the period, shared by the
older fx-10 and the briefcase models 103-mr
& 803-mr with a square-jaw case and square
the function set is similar but less complete than the later fx-19,
but this model has 10 digits. it also takes 4AA cells. the display is very
good with a spare digit for minus and the gap between a ten digit mantissa
and the two digit exponent.
conceptually this is a throwback to the fx-10,
but the function set is much improved and the calculation speed increased.
the right most digit flickers whilst calculating like the fx-20
and the small zero digit has gone and exponents of up to +/-99 are
a switch for degrees or radians has appeared, but no sign yet of
gradians or fractions. like earlier models a 10^x button is not
present, since x^y can be used for this, although conveniently this model
has a x^2 button which doesnt appear again until arc is replaced by
an inv button on later models like the fx-39.
the calculation algorithms appear very similar to the fx-19
and improved from the fx-20, but interestingly cos
stops at 1530, sin & tan at 1440 like the fx-20. later models all stop
at 1440 until much later.