Calculators Mechanical
The abacus (pl: abaci or abacuses), also called a counting frame, is a hand-operated calculating tool of unknown origin used since ancient times in the ancient Near East, Europe, China, and Russia, millennia before the adoption of the Hindu-Arabic numeral system.
The abacus consists of a two-dimensional array of slidable beads (or similar objects). In their earliest designs, the beads could be loose on a flat surface or sliding in grooves. Later the beads were made to slide on rods and built into a frame, allowing faster manipulation.
Each rod typically represents one digit of a multi-digit number laid out using a positional numeral system such as base ten (though some cultures used different numerical bases). Roman and East Asian abacuses use a system resembling bi-quinary coded decimal, with a top deck (containing one or two beads) representing fives and a bottom deck (containing four or five beads) representing ones. Natural numbers are normally used, but some allow simple fractional components (e.g. 1⁄2, 1⁄4, and 1⁄12 in Roman abacus), and a decimal point can be imagined for fixed-point arithmetic.
Any particular abacus design supports multiple methods to perform calculations, including addition, subtraction, multiplication, division, and square and cube roots. The beads are first arranged to represent a number, then are manipulated to perform a mathematical operation with another number, and their final position can be read as the result (or can be used as the starting number for subsequent operations).
In the ancient world, abacuses were a practical calculating tool. Although calculators and computers are commonly used today instead of abacuses, abacuses remain in everyday use in some countries. The abacus has an advantage of not requiring a writing implement and paper (needed for algorism) or an electric power source. Merchants, traders, and clerks in some parts of Eastern Europe, Russia, China, and Africa use abacuses. The abacus remains in common use as a scoring system in non-electronic table games. Others may use an abacus due to visual impairment that prevents the use of a calculator. The abacus is still used to teach the fundamentals of mathematics to children in most countries.
The Addiator is a mechanical adder produced by the Addiator Gesellschaft of Berlin from 1870 to 1982. It consists of a series of racks enclosed in a metal container and operated by a stylus. The Addiator, produced in dozens of models and millions of copies, was a great success, so much so that its name was often used as an antonomasia to indicate all rack adders.
The Addometer is a mechanical adder which in terms of use and external appearance resembles Blaise Pascal 's pascaline .
The adder looks like a heavy ruler, about 30 cm long. Circular slots allow you to operate numbered wheels placed inside, through special holes made on the wheel. Each hole corresponded to a number written in large characters on the inside of the slot and its complement to 9, written on the outside in smaller characters. To add, the tip of the stylus was placed in correspondence with the large numberand the disc was rotated clockwise. To subtract, on the other hand, the stylus was placed in correspondence with the external number and performed a counter-clockwise rotation. A much simplified mechanism compared to that of Pascalina allowed the carry over of the tens. The result appeared automatically and it was possible to reset it by pulling the tab on the right of the instrument.
It was produced from 1928 until the 1960s by Reliable Typewriter and Adding Machine Co .. The numbers were imprinted on perforated and toothed discs. These were very cheap and reliable instruments, so much so that they were covered by a one-year warranty, which was quite unusual for the time.
Technical Features
Manufacturer: Aristo
Model N ° 0868 ( Variation 3 ) Year 1973
Lenght (scales) 12.5 cm + 1. 2 cm ext
Material Wood / Celluloid Cursor Metal / Glass
Info: Aristo 868 Studio Pocket Slide Rules
A high end log log format pocket rule, shown with the factory box, leather case, and original manual. Has a slightly magnifying 6 line cursor, CF/C and B/C accent color stripes (faint). Self-documenting, two-color scales, including folded, log log, P (pythagorean) and decimal trig scales.
Technical Features
Manufacturer: Hans Sabielny Comptator Year:1922
Info: Hans Sabielnys Comptator Schubert & Salzer, Dresda from 1909 SN 2079 pice 1925 105 RM. Addition, 9 digits Ten's complement subtraction Pen operation Moving racks Counter Lever for clearing entries, lockable Knob for clearing results
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