Operating instructions of the pascaline

General remarks

The manuscript " usage de la machine " starts with an introduction describing in details how to enter numbers in the machine.

"I assume that one who uses the machine knows the characters of the digits 1, 2, 3, ... and that he knows than the digits of the first column to the right are the units or simple numbers, than the second column digits are for the tens [...] To calculate with the machine, one uses an ivory stylus we put in between the spokes in regard of the needed digits. The wheel is turned until the stylus is stopped by the needle at the bottom of the stared wheel she belongs. One must take care of setting the "deniers" on the wheel of the "deniers", the "sols" on the wheel of the "sols", the "livres" on the wheel of the "livres", ..."

This detailed explanation demonstrates that the user's manual was intended to everybody, including those with mediocre knowledge in mathematics. The hypothesis according to which it would be a manual given with the calculator has been advanced.

"The accomplishment of the machine is equal, and the operation is the same, either one begins to work with the stared wheels from the left to the right, or from the right to the left. But it is more convenient to go from the left to the right the same manner we would do to write."

The author of the manuscript states that it does not matter for a calculation to enter the numbers as usualy (from left to right) or in the contrary way (from right to left, starting with the less significant digit and ending with the most significant one).

"One has to remark than to use this machine, it is necessary to put it on a flat level because if it is leaned, the weights with which it works do not act."

This criticism is mentionned by a lot of people talking about the pascaline. It is obvious that if we lean the machine at 45 degrees, it does not work. Nevertheless if we place it on a table, it must work properly. This point is more detailed in the heading "I disagree" on this Web site.

Initializing the machine :

Preliminary remarks :

As the other calculators, the pascaline is equipped with an input device and an accumulator.

The input device consists of stared wheels revolving around their axis and surounded with a fixed crown engraved with digits (from 0 to 9 for the decimal ones). To input a number, the stylus is set in between the spokes at the engraved digit we want to enter. The wheel is turned until the needle stop (the same way we enter a phone number on an old telephone).

The accumulator consists of numeral drums whose axis are horizontal. These drums are connected to the stared wheels by crown types gears and revolve together from the same angular value (a full turn of the wheel forces a full turn of the drum)

The drums are printed with two numeral series in opposite direction (0 to 9 for the decimal ones). The two series are arranged in order that the sum of each pair of digits visible in the display windows gives 9 (for the decimal drums). A slide cover hides one or another of these series. By construction, the pascaline does not allow to turn the stared wheels counter clockwise. Depending of the slide cover position, when a drum revolves, the digits appear in an increasing order (addition) or in a decreasing order (substraction). When they appear in an increasing order, each time the drum has done a full turn, when the digits go from 9 to 0, an automatic carry happens on the drum immediatly at the left of the revolving one.

When the digits appear in a decreasing order, each time the drum has done a full turn, when the digits go from 0 to 9, an automatic carry happens on the drum immediatly at the left who decreases of one unit.

Before starting the pascaline must be initialized :

If you want to add (or multiply), you firstly set the slide cover toward the edge of the machine to uncover the bottom part of the windows (the increasing serie of digits is visible). If you want substract (or divide), the slide cover is pulled toward the operator to uncover the the upper part of the windows (the decreasing serie of digits is visible).