1978 -
Elka 50
The Elka 50 arithmetic microcalculator was manufactured from 1978 at Orgtechnica (Silistra, Bulgaria), one of the few producers still around today, albeit as a manufacturer of cash register equipment.
The scale on the monitor: 1:1




The calculator rounds all numbers to integers by default. All calculations are made with a fixed point. Calculations with a set number of digits after the point could be made by first pressing the "DP" key and specifying the number of digits after the point (from zero to nine), while the "," key automatically sets ten digits after the point.

The microcalculator’s keyboard uses reed switches with no mechanical contacts, making it more efficient and durable. Hence the acronym "Hercon", which stands for "hermetically sealed contact". Pressing a key on Elektronika[A1] calculators causes a plastic key to close two thin metal contacts, while Elka 50 has permanent magnets attached to its keys to generate a magnetic field, which closes the hercons when they come into contact with the slots on the key matrix.

Another feature of the calculator is the combined prefix and postfix notation. Addition or subtraction requires the input of an operand followed by a plus or minus sign. Multiplication and division use the classic infix notation, wherein the operator (the multiplication or division sign) is placed in-between two operands, followed by the "=" sign. This means that an operation like "2 + 3 − 5" would require the following input: "2" "+" "3" "+" "5" "−".

The microcalculator is equipped with a twelve-digit vacuum fluorescent display. While the indicators are actually nine-digit, the diagonal segments are turned off, rendering it, in effect, seven-digit. The calculator has no special symbols for errors, positive/negative signs, or numbers in its memory. Instead, these are displayed on a separate left-side indicator, marking "C" for error, "-" for a negative number, and "." for a number in the memory.
The calculator is powered by a 220V mains supply.

Weight: 1 kg or less
Dimensions: 250×170×60 mm