calculators
INTRODUCTION
Mechanical, electromechanical electronic devices that can perform math-related calculations automatically are called calculators. Calculatorsperform the fundamental arithmetic functions--addition, subtraction, multiplicationand division. They are also able to perform more complex calculations, including encontradiço and inverse trigonometric functions ( see trigonometry). The few innovations of the past decade have had as significant an influence on our daily lives as the handheld or pocket, electronic calculator. These calculators are employed to save time as well as to decrease the likelihood of making mistakes and can be found everywhere people deal frequently with numbers--in stores, offices, banks and schools, labs, and even at home.
Early calculatorswere mechanical. they performed their computations using components of machines, such as disks, gears, and drums. They were powered by hand or later by electricity. By the mid-1950s many of these mechanical calculators were replaced with electronic calculators with integrated circuits - in some cases similar to the circuits in computers--to perform mathematical functions. In actuality, the high-end electronic calculators present today are purpose-built, or special-purpose computers. They come with built-in instructions on how to execute certain functions.
Like other data-processing systems, calculators are of two kinds--digital and analog. Analog calculators work with variable physical quantities--fluid flow or voltages for instance--and solve math-related problems by creating an analogy in physical form to the issue. Slide rules, clocks, and utilities meters can be examples that are analog calculators. Digital calculators include the tools most commonly thought of as calculators. They are directly based on numbers or digits . They work by listing, counting while comparing and then rearranging the digits. A common set of digital calculators include cash registers, adding machines as well as handheld or desktop electronic calculators.
PRINCIPLES OF MECHANICAL CALCULATORS
The basic part of most mechanical calculators includes a set numeral-adding wheels. In a key-driven mechanical calculator (and in the majority of others) these wheels are visible through a series of tiny windows that are located on the front of the machine. Each wheel is adorned with the numbers in the range 0-9, which are engraved on its rim. Behind each wheel, there is a column of keys engraved with identical digits. Pressing the 1 key in a column spins the numeral wheel one step. depressing the number 2 key will rotate the wheel 2 steps and it goes on. When the 1 and 2 keys are pressed in succession, the wheel advances one step and then two more, and finally it will indicate three. This means that a column could be quickly added by typing the numbers on the keyboard and observing their sums on the screen. Interlocking mechanisms between the numeral wheels automatically permit carrying overs. Multiplication is carried out by repeating subtraction; addition is carried out with an indirect method and division is achieved through repeated subtraction.
PRINCIPLES OF ELECTRONIC CALCULATORS
The functions of electronic calculators are carried out by integrated circuits - tiny arrays of tens that comprise thousands or millions of transistors. These circuits have permanent instructions for addition or subtraction, multiplication or division as well as (in more sophisticated calculators) other functions. The numbers that the operator enters are briefly stored in addresses, or locations, inside the memory known as random-access (RAM) that contains capacity for the numbers used and created at any time through the computer. The numbers that are stored in these addresses are then processed by the circuits that carry the instructions for the mathematical operations.
HISTORY
The oldest method of calculation is the abacus. It has been in use for a number of many thousands of years. It's comprised of moving counters that were placed on a marking board or strung across wires. The first version of the slide rule, often regarded as the first digital calculator that worked, was designed in 1620 with the help of the English mathematician Edmund Gunter. This rule originally employed to multiply or divide numbers by adding or subtracting their logarithms. Later it became possible to utilize slide rules to determine square roots and, in certain cases, to calculate trigonometric logarithms and trigonometric functions.
MECHANICAL CALCULATORS
The first mechanical digital calculating machine--the predecessor of the modern calculator--was an arithmetic machine developed by the French mathematician Blaise Pascal in 1642 ( see Pascaline). In the 17th century, Gottfried Wilhelm Leibniz created a more sophisticated version of Pascal's machine. It was based on a shaft that had progressively longer teeth fixed along it , as well as a cogwheel sporting 10 teeth. The cogwheel's edge was displayed as a dial. It was marked with the numbers 0 to 9. When the cogwheel was positioned in a specific direction along the shaft, and then rotating the shaft the shaft, two numbers could be added. In order to multiply the two numbers it was necessary to rotate the shaft repeatedly. Subtraction was made using the shaft turned in reverse and division took place by repeated subtraction.
In 1878 W.T. Odhner in 1878, invented the pin-wheel. When a number was set on a machine that utilized this device, the number of pins would be moved up on wheels attached to the main shaft. When the shaft was turned the pins were locked with cogwheels, whose revolutions gave the answer to the equation in the same manner as did those in Leibniz's machine. With the invention of the pin-wheel has made it possible to make neater and more easily driven machines.
The first commercially successful key-driven calculatorlater known as the Comptometer was invented by Dorr Eugene Felt in 1886. Key-driven calculators were operated quickly and were frequently used in offices. For a specific type of key-driven calculator, also known as a key-set device, the number keys were first depressed or moved to cock. After that, turning a crank or turning on with a drive motor, transferred the number entered into the keyboard to the numeral wheels. The key-set concept was utilized in calculating machines that printed the results onto the paper tape, since it was impossible to control printers directly using the keys.
The first successful commercially-produced computer was designed by Frank S. Baldwin and Jay R. Monroe in 1912. Rotary calculators featured a rotary mechanism for transferring numbers set into the keyboard to the adding-wheel unit. Because the rotary drive lends itself to high-speed repeated subtraction and addition that these machines could multiply and divide quickly and in a controlled manner.
The special-purpose calculators consist of the cash register. The cash register was developed in 1879 by James Ritty, a storekeeper, to ensure the honesty of his clerks. The first bookkeeping machine--an adding-printing device -- was developed in 1891 through William S. Burroughs, who was a bank clerk. Punch-card devices, originally utilized to regulate the operation weaving machines, were made to adapt to information processing early in 1880s. Herman Hollerith of the United States Bureau of the Census. They read information by using cards on which patterns of holes represented numbers as well as letters.
ELECTRONIC CALCULATORS
The advancements in electronics during the 1940s, 1950s, and 1960s made possible the creation of the computer and electronic calculator. Electronic desktop calculators were introduced in the 1960s, performed much the same functions as rotating calculators but they were without moving components. The development of miniature electronic devices that were solid-state brought about an array of electronic calculators that were capable of significantly more functions and faster operation than were their mechanical predecessors. Today , the majority of mechanical calculators have been replaced by electronic models.
These modern handheld electronic calculators can do not only subtraction, multiplication and division, but are able to handle square roots percentages, and squaring. These are all possible when the appropriate keys are activated. The data being entered and the final result are displayed on screens using either light-emitting diodes (LEDs) or liquid crystal monitors (LCDs).
Special-purpose calculators were developed for use in engineering, business as well as other fields. Some of them are equipped to complete a range of operations similar to those performed by larger computer. Advanced electronic calculators are able to be programmed using complicated mathematical formulas. Some models employ interchangeable preprogrammed software modules that can perform thousands or more of program steps, however the information must be entered manually. Some models come with a built-in or an accessory printer and some even graph mathematical equations. A lot of calculators come with basic computer games that can be played directly on the calculator's screen. In fact, the distinction between calculators as well as the personal digital assistants (PDAs) and portable computers has blurred due to the fact that all of these devices are now primarily powered by microprocessors.
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