calculators
INTRODUCTION
Mechanical, electromechanical electronic or electromechanical devices that perform mathematical operations automatically are called calculators. Calculators perform calculators perform essential mathematical functions like subtraction, addition, division, and multiplication. Many can also do more complicated calculations, like cotidiano and inverse trigonometric function ( see trigonometry). The few innovations of the past decade have had such a profound influence on daily life as the handheld, also known as a pocket, electronic calculator. These calculators are used to cut down on time and to reduce the likelihood of making mistakes and are used wherever people deal frequently with numbers--in office spaces, in banks, stores as well as in laboratories, schools as well as in private homes.
The earliest calculators were mechanical: they performed their computations using machine parts--such as disks, gears, and drums. These were powered by hand , or later, by electricity. By the mid-1950s many machines such as these calculators were replaced by electronic calculators which had integrated circuits--in some cases like the circuits found in computers--to provide mathematical functions. In fact, the sophisticated electronic calculators of today are actually specifically designed, or even special-purpose computers. They have built-in instructions for how to perform certain limited functions.
Like other data-processing systems, calculators are of two types: digital and analog. Analog calculators work with various physical quantities that are variable--fluid flow, or voltages, for instance. They solve mathematical problems by creating a physical analogy to the problem. Clocks, slide rules or utility meters are examples of analog calculators. Digital calculators comprise the gadgets most often considered calculators. They work directly with numbers or digits . They work by counting, listing the numbers, comparing and rearranging these digits. Digital calculators include adding machines, cash registers as well as desktop or handheld electronic calculators.
PRINCIPLES OF MECHANICAL CALCULATORS
The primary component of mechanical calculators comprises a set of numeral-adding wheels. In a mechanical calculator that is driven by keys (and in a majority of other) these wheels are visible through a series of tiny windows at the top part of the instrument. Each wheel is adorned with the numbers 0 through 9 marked around the rim. Beneath each wheel is a column of keys that are marked with identical digits. Pressing the 1 key in a column makes its numeral wheel by one step; pressing the number 2 key turns the wheel by two steps and then on. When the keys 1 and 2 are repeatedly pressed, the wheel advances one step and then two more, and finally it will indicate three. A column of numbers can be quickly added by entering the numbers on the keyboard and then reading their totals in the windows. Interlocking mechanisms between numeral wheels automatically ensure carryovers. Multiplication is accomplished by repeating addition, while subtraction is performed by an indirect method; the division process is carried out by repeated subtraction.
PRINCIPLES OF ELECTRONIC CALCULATORS
The operation of electronic calculators can be performed using integrated circuits, tiny arrays consisting of thousands, millions, of transistors. These circuits are equipped with permanent instructions for subtraction, subtraction, multiplication, division and (in more advanced calculators) other functions. The numbers that the operator enters are briefly stored in addresses or locations, inside the memory known as random access (RAM) which is a storage room for the numbers entered and produced at any given time using the calculator. The numbers stored in these addresses are then processed by circuits that contain the instructions for the mathematical operations.
HISTORY
The oldest calculator is the abacus, which has been used for decades. It is comprised of movable counters that are placed on a marked board or strung over wires. A earliest version of the slide rule often thought of as the first digital calculator that worked, was created in 1620 with the help of the English mathematician Edmund Gunter. A slide rule initially utilized to multiply or divide numbers by subtracting or adding their logarithms. Later , it was possible make use of slide rules in order to extract square roots as well as, in certain cases, to calculate trigonometric operations and logarithms.
MECHANICAL CALCULATORS
The first digital mechanical calculating machine--the predecessor of the modern calculator -- was an arithmetic machine devised by French mathematician Blaise Pascal in 1642 ( see Pascaline). Later in the 17th century Gottfried Wilhelm Leibniz created a higher-tech design of Pascal's invention. It had a shaft fitted with increasing length of teeth, which were fixed to the shaft and a cogwheel that had 10 teeth. The cogwheel's end was is shown on a dial. The cogwheel was marked with numbers 0 to 9. By putting the cogwheel an exact position along the shaft, and then turning the shaft in a certain direction, two numbers can be added. If you wanted to add two numbers by turning the shaft multiple times. Subtraction was performed using the shaft turned backward, and division was performed by repeated subtraction.
In 1878 W.T. Odhner created the pinwheel. When a specific number was entered in a machine equipped with this device, the corresponding number of pins would be moved up on wheels attached to the main shaft. When the shaft turned, these pins joined with cogwheels, and their movements gave the answer to the equation exactly the same way as did those of Leibniz's device. This invention of the pin-wheel has made it possible to build cleaner and more easily driven machines.
The first commercially successful key-driven calculator, later dubbed the Comptometer was invented by Dorr Eugene Felt in 1886. Key-driven calculators could be operated very quickly and were commonly employed in offices. For a specific type of key-driven calculatorknown as a key-set machine, the number keys first had to be depressed, or moved to cock. A second action, turning a crank or launching driving motors--transferred the information that was entered into the keyboard onto the numeral wheels. Key-set principles were used in the calculation of machines that printed results on paper tape since it was not possible to direct printers directly from 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 that transferred numbers from the keyboard onto the adding-wheel unit. Because the rotary drive lends itself to high-speed repeating addition and subtraction that these machines could multiply and divide quickly and in a controlled manner.
Specific-use mechanical calculators include the cash register. The cash register was invented in 1879 James Ritty, a storekeeper who wanted to ensure the honesty of his employees. The first bookkeeping device--an adding printing device--was invented in 1891 by William S. Burroughs, the bank clerk. Punch-card machines, originally used to regulate the operation of looms, were adapted 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 numbers and letters.
ELECTRONIC CALCULATORS
Developments in electronics in the 1940s, 1950s, and 1960s made possible the development of the computer as well as the electronic calculator. Electronic desktop calculators made their debut in the 1960s, served the same functions as the rotary calculators but they were without moving parts. The advent of tiny electronic devices with solid-state electronics brought the world a variety of electronic calculators that were capable of many more functions and more efficient than their mechanical counterparts. Nowadays, most mechanical calculators have been replaced by electronic models.
Modern handheld electronic calculators are capable of not only multiplication, subtraction, addition and division, but are able to handle square roots percentages, and squaring. This is by pressing the appropriate key. pressed. The input data and the end result are shown on a screen with the use of either light-emitting diodes (LEDs) or liquid crystal screens (LCDs).
Special-purpose calculators were developed for applications in engineering, business and other areas. Some of these are able to complete a range of tasks similar to those performed by larger computer. Advanced electronic calculators are able to be programmed using complex mathematical formulas. Certain models use interchangeable preprogrammed software modules capable of 5 or more program steps, however the information must be entered manually. There are many calculators that have a built-in or an accessory printer and some even graph mathematical equations. Many calculators contain basic computer games that are played on the calculator's display screen. In fact, the distinction between calculators as well as PDAs, personal digital assistants (PDAs), and portable computers is blurred because all of these devices now typically use microprocessors.
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