casio fx-50f

a 10+2 c-power scientific model with rubber keys from 1987. i like this machine. it has quite a good set of features, easy to use, algebraic entry rather than formula and its even programmable.

it has a lot in common with the fx-992v. in fact i think it can do everything on the 992v and more. additional features include, 29 step blind programs, 23 built in formulae and physical constants. despite being programmable, there is no numerical integration, unlike the fx-3800pv

there are 23 built in scientific formula. they operate in the same manner as the fx-5000f, which has 128 of them. when recalled, the formula prompt for data values, then execute a preset calculation. the sort of things stored are simple text book formula for triangles, areas, quadratic equations and so on. ie nothing complicated that involves iteration or loops. nevertheless, this feature is still a bonus if you can remember the code numbers.

the c-power is a solar panel and also a gr927 battery. i dont know if the panel can charge the battery, but it is possible for the battery to be run down and replacement involves taking the machine apart. the solar panel is a bit small, but it can still power the machine under artificial light.

an easy to use arrangement for number bases here, especially if you use dec and hex a lot. all the operations and the A-F keys are on keyboard once in base mode and you can switch between bases easily.