There’s an article here exposing some of the subtler behaviour of the humble four function calculator.
Much of this doesn’t apply these days, although possibly experiments with an almost-free four-function might amuse - a calculator with no operator precedence is needed. (Back in the day TI calculators had some idea of operator precedence, and might have been the first to do so.) Having a memory, M+ and MR, even MC, doesn’t affect the findings much, I think, but having a K constant key, or even a K annunciator, might. The implicit constant is one of the nice little areas of calculator function, I think.
This is a favourite of mine - the final = may or may not be needed, depending on the model: .3x===/==
I have a Sharp Compet from 1969, and its notation is … weird. I’ve managed to make it do square roots (by tapping ÷ twice, I think) but it’s incredibly slow. Nice nixie display, though.
Then there’s this article - calculator-app - Chad Nauseam Home - about H-J Boehm’s attempt to make the Android Calculator do exactly what everyone might expect. It’s more difficult than it looks.
Yes, my first hands-on experience with a calculator was the National Semiconductor 600 that my parents bought in the early 1970s to balance their checkbook. That was about the limit of its capabilities, with its hard-wired fixed decimal point, but it did the job reliably for several years.
Sharp was at the forefront of calculator development and this machine was the start of a long line of hand-held calculators, which gradually became smaller; see the Sharp EL-8, EL-811, and EL-801.
Seems I was wrong about that for my 361M. Someone posted a manual for the very similar Sharp Compet 361R. You get square roots out by hitting the very logical ×= combination,
The keyboard has two= keys, the second (red) one for subtraction. Of course …
It has 16 lovely nixies for its display, and its memory is magnetic cores.
