remington 1259s
this is a rebranded casio fx1, casio's first scientific
calculator originally released february 1972. the key layout and
electronics are identical but the case is slightly different.
this machine is fascinating to operate. the nixie tube display flickers
and dances throughout its calculations. the cube root operation takes up
to 16 seconds to complete.
for the most part, this machine operates as you would expect an early
desk calculator, but the top two rows of buttons provide a rather strange
set of scientific functions. you have sin, cos and tan, but only arctan.
you have ln(x), exp(x) and log10. you have hyperbolic cosh and sinh but no
inverses. there is square root and cube root. interestingly the cube root
function does not use the available log functions. internally it must use
its own converging formula instead. the result takes longer than using
ln(x) and exp(x) but is more accurate. there is no general x^y, but
instead a^n where `n' is only a single digit.


what is interesting is that all the scientific
functions appear to be rom macros of keyboard operations, just like some
huge calculation. i figure there must be some internal memories available
to the macros, not exposed on the keyboard.
despite this, the scientific functions provide slow but fairly accurate
results. more so than casio later machines like the fx39.
the a^n feature clearly uses repeated multiply and begins as soon as an
`n' digit is pressed. its a pity there is no way to enter a bigger integer
as a^n using logs is less accurate. 

