calculators
INTRODUCTION
Mechanical, electromechanical electronic or electromechanical devices that automatize mathematical calculations are referred to as calculators. Calculatorsperform functions that perform the standard Arithmetic functions, including subtraction, division and multiplication. Some can also perform more intricate calculations, such as regular and inverse trigonometric functions ( see trigonometry). Few technological innovations in recent years have had such a profound influence on our daily lives as the handheld or pocket, electronic calculator. These calculators are used to save time and to reduce the risk of making errors and are used wherever individuals are frequently in contact with numbers, such as banks, offices, shops, schools, laboratories, as well as in private homes.
The early calculatorswere mechanical: they carried out calculations using mechanical components such as disks gears, and drums. These were powered either by hand or later electricity. The mid-1950s saw a number machines such as these calculators were replaced with electronic calculators with integrated circuits--in certain cases, similar to the circuits in computers--to execute mathematical functions. In fact, the sophisticated electronic calculators that we have today are specially-purpose computers. They are equipped with instructions that tell you how to perform certain limited operations.
Like other data-processing systems, calculators are of two kinds--digital and analog. Analog calculators operate with fluid flow or voltages for instance--and solve math-related problems through the creation of an analogy physical to the issue. Slide rules, clocks along with utility meters comprise examples of analog calculators. Digital calculators include the tools most frequently thought of as calculators. They work directly with numbers or digits . They work by listing, counting or listing, comparing, and changing the arrangement of these digits. Digital calculators include adding machines, cash registers as well as desktop or handheld electronic calculators.
PRINCIPLES OF MECHANICAL CALCULATORS
The fundamental part of all mechanical calculators includes a set numeral-adding wheels. In a key-driven mechanical computer (and in a majority of other) these may be seen through a series of tiny windows on the front and back of the unit. Each wheel has the numerals of 0 through 9 around its rim. In between each wheel is an column of keys engraved with identical digits. The number 1 key within a column will turn its numeral wheel one step. depressing the key number 2 turns the wheel 2 steps and that goes on. When the keys 1 and 2 are simultaneously pressed it will move the wheel one step, and after that two moretimes, before finally showing three. So a column of numbers can be added quickly by typing the numbers into the keyboard and seeing their sum in the windows. Interlocking mechanisms between numeral wheels automatically provide for carryovers. Multiplication is done by repeated subtraction; addition is carried out through indirect methods and division is done by repeated subtraction.
PRINCIPLES OF ELECTRONIC CALCULATORS
The operations of electronic calculators are executed by integrated circuits, tiny arrays that comprise thousands or millions, of transistors. These circuits contain permanent instructions for subtraction or subtraction, multiplication or division, and (in more advanced calculators) other functions. The numbers that the operator enters are temporarily stored in addresses, or locations, in the memory known as random access (RAM) that contains capacity for the numbers used and produced at any given moment using the calculator. The numbers stored in these addresses are then processed by circuits, which contain the instructions for mathematical operations.
HISTORY
The oldest method of calculation is the abacus. It has been used for hundreds of years. It is composed of movable counters, which are either placed on a marked board or strung over wires. A earliest version of the slide rule often regarded as the first successful analog calculator, was created in 1620 with the help of the English mathematician Edmund Gunter. This rule originally employed to multiply or divide numbers by subtracting or adding their logarithms. Later it became possible to make use of slide rules to calculate square roots and, in certain instances, to calculate trigonometric function and logarithms.
MECHANICAL CALCULATORS
The first digital mechanical calculator, which was the predecessor to the modern calculator -- was an arithmetic machine devised by the French mathematician Blaise Pascal in 1642 ( see Pascaline). In the 17th century, Gottfried Wilhelm Leibniz created a more advanced design of Pascal's invention. It utilized a shaft with increasingly longer teeth welded to it and a cogwheel with 10 teeth. The edge of the cogwheel could be seen on a dial, and was marked with the numbers 0-9. By placing the cogwheel certain directions along the shaft and then turning the shaft the shaft, two numbers could be added. If you wanted to add two numbers, the shaft was rotated several times. Subtraction was done by turning the shaft backward and division was achieved through repeated subtraction.
In 1878 W.T. Odhner developed the pin-wheel. When a number was determined in a machine equipped with this device, the corresponding number of pins would be elevated on wheels that were carried by the main shaft. When the shaft turned, these pins joined with cogwheels, which turned their revolutions to give the result to the sum similar to how they were the cogwheels used in Leibniz's invention. It was the development of the pin-wheel made it possible to make cleaner and more easily driven machines.
The first key-driven calculatorlater known as the Comptometer was developed by Dorr Eugene Felt in 1886. Key-driven calculators were operated quickly and were frequently employed in offices. In one type of calculator that was driven by keys, referred to as key-set machines, the number keys were first depressed, or then cocked. Then , a second action--turning the crank or starting an electric motor -- transferred the number set into the keyboard to the wheels for numerals. Key-set principles were used in calculating machines that printed out results on paper tape because it was not possible to drive printers directly from the keys.
The first successful commercially-produced rotary calculator was developed by Frank S. Baldwin and Jay R. Monroe in 1912. The first rotary calculators incorporated a rotary mechanism to transfer numbers that were set on the keyboard into the adding-wheel unit. Because the rotary drive lends itself to high-speed repeating addition and subtraction that these machines could multiply and divide rapidly and in a controlled manner.
Special-purpose mechanical calculators comprise the cash register, which was invented in 1879 by James Ritty, a storekeeper in order to guarantee the honesty of his clerks. The first bookkeeping machine, an adding-printing device was invented in 1891 with the help of William S. Burroughs, a bank clerk. Punch-card machinesoriginally employed to regulate the operation weaving machines, were upgraded to processing information during the 1880s, by Herman Hollerith of the United States Bureau of the Census. They read data from cards whose patterns of holes represented both numbers and letters.
ELECTRONIC CALCULATORS
Electronics advancements during the 1940s and 1950s made possible the creation of the computer as well as the electronic calculator. Electronic desktop calculators that were first introduced in the 1960s, were able to perform the same function as mechanical calculators but with virtually no moving parts. The advent of miniaturized solid-state electronic devices brought the world a variety of electronic calculators with far more functions and far quicker operation than their mechanical predecessors. Nowadays, the majority of mechanical calculators are being replaced with electronic models.
Modern handheld electronic calculators can perform not only addition, subtraction, multiplication, and division but also are able to handle square roots percentages, and squaring. This is by pressing the appropriate key. pressed. The input data and the final result are displayed on a display using or light emitting diodes (LEDs) or liquid crystal display (LCDs).
Special-purpose calculators were designed for use in business, engineering as well as in other fields. Some of these are able to perform a series of operations similar to those performed by larger computer. Sophisticated electronic calculators can be programmed with complex mathematical formulas. Some models employ interchangeable preprogrammed software modules that can perform 5,000 or more program steps, however the data must still be keyed manually. Some models come with a built-in or an accessory printer with graphing capabilities, while some models can draw mathematical equations. Many calculators come with basic computer games that are played directly on the calculator's screen. The distinction between calculators as well as portable digital assistants (PDAs), and portable computers is blurred because all of these devices currently use microprocessors.
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