remington 1259s

this is a rebranded casio fx-1, 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 fx-39.

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.