sinclair scientific

this model dates back to 1974 at a time when sinclair was introducing affordable pocket calculators. back then, if you wanted a scientific calculator, it costed!. from 1972 you could buy a hp35 for $395 (a fortune then) and it wasnt until 1974 that texas instruments introduced their scientific sr-50 for $169.95.

the scientific functions offered by this model are somewhat approximate. the machine is fixed at 5+2 digits and you are lucky to get 4 digits correct. furthermore, there are no input checks to bring trigs into computable range. you have to do this manually. there are no other functions, like powers, roots or even a memory. some handy constants are written on the face for reference.

despite these shortcomings, the machine was useful. at a time when other scientific models were prohibitively expensive it beat using a slide rule. its low cost and small size were possible because, the main component was not itself natively scientific. amazingly, sinclair managed to use parts of the main logic in new ways to implement scientific function approximations.

by comparison, the hp35 had a small processor with rom microcode to implement scientific functions through cordic methods.

this model is powered by 4 AAA cells, which gave a smoother profile than the later (pregnant) models and typically came in a hard plastic case that protected it. if you have one of these, ensure that the battery connectors are straight as they sometimes fall out of line and cause the infamous hot battery problem!