Casio fx-115WA

A scientific pocket-size calculator from the late nineties.
Like most newer Casio devices of this type, this calculator also has V.P.A.M. (Visually Perfect Algebraic Method), that is, a system of entering mathematical expressions, consistent with how it is written on paper.
Example:
To calculate the square root of 2, enter the square root symbol and then the number 2.
Entering the number 2 and then selecting the square root symbol, as on a typical basic pocket calculator, will be incomprehensible for this device and will result in displaying "Syn ERROR" (syntax error).

Of course, V.P.A.M. offers a lot more, but the above example shows the change in operation in the easiest way.
How does S-V.P.A.M. differ from V.P.A.M.? Actually, the only difference is that the screen is divided into two lines: one prepared for entering expressions (and displaying potential errors) and the other - dedicated to displaying the result.