calculators
INTRODUCTION
Electromechanical, mechanical electronic, or electronic devices that perform mathematical operations automatically are referred to as calculators. Calculators perform calculations using the fundamental mathematical functions like subtraction, addition, division, and multiplication. Many can also do more complicated calculations, like usual trigonometric functions as well as inverse trigonometric ( see trigonometry). There are few inventions that have had as significant an influence on our lives as the handheld or pocket, electronic calculator. These calculators can be used to help save time and decrease the likelihood of making mistakes and are found wherever you need to be able to use numbers frequently, in offices, retail stores, banks and laboratories, in schools, as well as in private homes.
The first calculatorswere mechanical. they made calculations using components of machines, such as disks, drums, and gears that were powered either by hand or later electricity. In the 1950s, many were mechanical calculators were replaced by electronic calculators that contained integrated circuits - in some cases similar to the circuits found in computers--to execute mathematical functions. In actuality, the highly-technical electronic calculators of today are actually dedicated, or special-purpose, computers. They contain built-in instructions on how to use certain functions.
Like other data-processing systems, calculators are of two types: analog and digital. Analog calculators are able to work with various physical quantities that are variable--fluid flow, or voltages for instance. They also solve mathematical problems through the creation of a physical analogy to the issue. Slide rules, clocks, or utility meters are examples of analog calculators. Digital calculators comprise the gadgets most often thought of as calculators. They work directly with numbers or digits , and operate by listing, counting or listing, comparing, and changing the arrangement of these digits. A common set of digital calculators include cash registers, adding machines and desktop or handheld electronic calculators.
PRINCIPLES OF MECHANICAL CALCULATORS
The basic part of most mechanical calculators is a set numeral-adding wheels. In a mechanical calculator that is driven by keys (and in the majority of others) these wheels are visible through a series of tiny windows on the front on the front of your machine. Each wheel is adorned with the numbers 0 through 9 marked around the rim. Beneath each wheel is a column of keys marked with identical digits. Depressing the number 1 key in a column turns its numeral wheel by one step. depressing the key number 2 turns the wheel by two steps and it goes on. When the 1 and 2 keys are pressed in succession then the wheel will advance one step forward, then two moresteps, finally signalling the number 3. So a column of numbers can be added quickly by simply entering the numbers in the keyboard and seeing their totals in the windows. Interlocking mechanisms within the numeral wheels automatically ensure carryovers. Multiplication is carried out by repeating addition; subtraction is done via indirect methods and division is done by repeated subtraction.
PRINCIPLES OF ELECTRONIC CALCULATORS
The operation of electronic calculators are carried out by integrated circuits, tiny arrays with thousands or even millions of transistors. These circuits are equipped with permanent instructions for addition to, subtraction, multiplication, division, and (in more sophisticated calculators) additional functions. The numbers that the operator enters are temporarily stored in addresses, or places, in the random-access memory (RAM) which contains enough space to store the numbers that are used and created at any time when the computer calculates. The numbers stored in these locations are then processed by the circuits that contain the instructions for mathematical operations.
HISTORY
The oldest calculator is the abacus, which has been in use for thousands of years. It consists of movable counters placed on a marked board or strung across wires. An early version of the slide rule often regarded as the first calculator to be successful in analog, was developed in 1620 by the English mathematician Edmund Gunter. This rule initially utilized to multiply or divide numbers by subtracting or adding their logarithms. Later it became possible to use slide rules to extract square roots, and in some cases, to calculate trigonometric operations and logarithms.
MECHANICAL CALCULATORS
The first mechanical digital calculating machine--the predecessor of the modern calculator was an algebraic machine invented by French mathematician Blaise Pascal in 1642 ( see Pascaline). In the 17th century, Gottfried Wilhelm Leibniz created a higher-tech model of the machine that Pascal had designed. It employed a shaft with more and longer teeth fixed on the shaft and a cogwheel that had 10 teeth. The cogwheel's edge was displayed as a dial. It was marked with numbers 0 to 9. By putting the cogwheel a specific direction along the shaft, and then turning the shaft to rotate it, two numbers could be added. If you wanted to add two numbers by turning the shaft several times. Subtraction was accomplished using the shaft turned in reverse while division was done through subtraction repeated.
In 1878 W.T. Odhner created the pinwheel. When a number was determined on a machine using this device, the corresponding number of pins would be placed on wheels mounted on the primary shaft. When the shaft was turned, the pins interlocked with the cogwheels, and their movements gave the result to the sum in the same manner as did those in Leibniz's machine. The invention of the pin-wheel was what made it possible to design simpler and more efficient machines.
The first successful commercially-produced key-driven computer, later referred to as the Comptometer was created by Dorr Eugene Felt in 1886. Key-driven calculators were able to be operated quickly and were commonly used in offices. In one kind of calculator that was driven by keys, referred to as key-set machines, the numbers keys were initially depressed or turned off. A subsequent action -- turning a crank or launching an electric motor -- transferred the number that was entered into the keyboard onto the wheels for numerals. The principle of key-set was employed in calculating machines that printed their results on paperstape because it was impossible to control printers directly using the keys.
The first commercially successful computer was designed by Frank S. Baldwin and Jay R. Monroe in 1912. The first rotary calculators included a rotary mechanism to transfer numbers that were set on the keyboard to the adding-wheel unit. Because the rotary drive lends itself to high-speed repetition of addition and subtraction that these machines could multiply and divide very quickly and automatically.
A special purpose mechanical calculators consist of the cash register. This was invented in 1879 by James Ritty, a storekeeper to ensure the honest conduct of his staff. The first bookkeeping machine--an adding-printing device was invented in 1891 from William S. Burroughs, the bank clerk. Punch-card machines, initially used to regulate the operation weaving machines, were upgraded to processing information in the 1880s by Herman Hollerith of the United States Bureau of the Census. They read information from the cards, and patterns of holes represented numbers and letters.
ELECTRONIC CALCULATORS
Advancements in electronics in the 1940s and 1950s led to possible the invention of the computer and electronic calculator. Electronic desktop calculators that were first introduced in the 1960s, had the similar functions to rotary calculators but they were without moving components. The development of miniature electronic devices that used solid state technology brought a series of electronic calculators which could perform far more functions and far faster operation than were their mechanical predecessors. Today , the majority of mechanical calculators are being replaced with electronic models.
Electronic handheld calculators are capable of not only subtraction, multiplication and division but can handle square root, percentages, and squaring when the appropriate key is press. The information entered and the result displayed on screens using the use of either light-emitting diodes (LEDs) or liquid crystal displays (LCDs).
Special-purpose calculators are designed for applications in engineering, business as well as other fields. Some of them are able to manage a variety of tasks that are similar to those handled by larger machines. Sophisticated electronic calculators are able to be programmed using complex mathematical formulas. Some models are equipped with interchangeable software modules that are capable of up to 5,000 or more steps, although the information has to be input manually. Many units have a built-in or accessory printer and some are able to graph mathematical equations. A lot of calculators come with basic computer games that are played on the calculator's display screen. The distinction between calculators and personal digital assistants (PDAs) and portable computers has blurred because all of them currently use microprocessors.
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