all calculators
RU
1975
Bystritsa-2
Bystritsa-2 is a small (maximum size — 270✕220✕120 mm, maximum weight — 3.5 kg) 10-key electric calculating machine. Bystritsa-2 is the smallest personal electromechanical arithmometer developed for calculation mechanisation purposes. Unlike Bystritsa-1, Bystritsa-2 has a key to move the carriage to the leftmost position (located to the right from key 0). The arithmometer was developed as a copy of the German electromechanical calculator Contex 20.

The machine performs the four arithmetic operations, with multiplication and division being carried out semi-automatically (multiplication by way of iterative addition and division by way of serial subtraction). The calculator’s speed is at least 300 cycles per minute.

The revolution counter’s cylinder simultaneously displays two numbers: the black one is the number of operations for additions and multiplications (the number of additions exceeding that of subtractions) and the red one is for divisions (predominantly subtractions).

The machine’s calculation unit leverages sector gears of the setting plate, which are rotated at an angle pro rata to the input digits (identical to the mechanical arithmometer, one digit is equivalent to a rotation of 36 degrees).

To increase the calculation performance it is recommended that the operator use his/her left hand to enter numbers and run the machine, and his/her right hand to record the results. For the purposes of touch typing, key 5 features a hump rim.
03