this is a rather good machine. one of the few 12+2 machines
made before formula entry became dominant. it has an extra 2 internal
digits making it operate internally to 14 digits of precision, more than
any other casio here. accuracy is good and it can handle a wide domain of
input (trigs over 1440, tanh of 1e10 etc). fractions are deluxe as well
with 10 net digits. a good set of functions; fractions, hyperbolics, 2d stats with linear
regression, hex and octal bases, 6 `k' memories and interestingly a rom
catalog of 128 physical constants. these are recalled using the const
key
prefixed by an index 1 through 128. to remember what that constants are,
their indices and units, there is a reference card that lives in the
accompanying wallet for the machine. other nice touches are twin power
(solar and GR927 battery), keys for eng display, delete and x^2. all keys
are rubber and positive to operate.
its not programmable, however, and this would have have made it
complete together with built in numerical integration like the fx3900pv.
there is a very similar, but programmable model to this, its the fx50f. 
