hp 35

this was a breakthrough model in 1972; the first pocket sized scientific calculator.

at the time, a scientific calculator was a desktop machine and some doubted that a pocket-sized device had a place in the market. when it was announced, demand totally outstripped supply and the model, almost overnight, killed the 100 year old slide rule industry.

our object in developing the hp-35 was to give you a high precision portable electronic slide rule. we thought you'd like to have something only fictional heroes like james bond, walter mitty or dick tracy are supposed to own.

the hp-35 has far more computing power than previous pocket calculators. its ten digit accuracy exceeds the precision to which most of the physical constants of the universe are known. it will handle numbers as small as 10^-99 and up to 10^99, and automatically places the decimal point for you. it is the first pocket calculator to provide you with transcendental functions like logarithms and sines and cosines. the operational stack and the reverse "polish" (lukasiewicz) notation used in the hp-35 are the most efficient way known to computer science for evaluating mathematical expressions.

inside there are 3 rom chips each of 256, 10 bit codes, totalling only 768 instructions. programming this to perform the whole set of scientific functions was no easy task, plus it had to be quick enough.

the methods used are cordic (coordinate rotation digital computer) and were first described by volder in 1959. these methods use an iteration which can yield any of multiply, divide, sin, cos, arctan, log and square root depending on different inputs. see my cordic feature.

heres more on the hp35 and the simulator.