The production of the Electronica B3-19M microcalculators commenced in 1976 in Svetlovodsk. To a large extent, B3-19M followed in the footsteps of its predecessor, B3-18. First, the developers produced a limited batch of prototype models, then they launched B3-19M, after which the production of B3-19 was discontinued. Electronica B3-19M is the first Soviet calculator with reverse Polish notation. Such calculators require that the user start by entering the first number, then press key “↑” to feed the number into the stack, then enter the second number, and finally choose the necessary operation (addition, subtraction, division or multiplication).

The stack consists of three registers (X, Y and Z). The use of three registers makes it possible to perform mixed calculations (perform more than one operation to solve one mathematical problem provided that the retrieved result will be used in the following operation). The use of stack also enables the users to perform calculations with parentheses. The contents of registers X and Y are interexchangeable.

B3-19M was the first calculator to allow the input of number positions and display numbers with a floating point (scientific notation), which made it possible to work with fairly large (for example, interstellar distances) or, vice versa, extremely small numbers (atom and electron sizes).

Клавиши имеют двойную маркировку: один символ нанесен непосредственно на клавише, второй — над клавишей. The operations designated by the symbols located above the key are only performed after pressing the combined function F key.

B3-19M was the first calculator to feature a 12-digit red LED display. Eight of the diodes are used to represent the number, while the other four display the number sign, the exponent sign and the number position.

For power supply the microcalculator can use both four AA batteries and a line adapter.

Size — 166.5×86times;41 mm. Weight — 400 g or less.