calculators
INTRODUCTION
Mechanical, electromechanical electronic devices that perform mathematical operations automatically are called calculators. Calculators perform calculations using the most basic arithmetic functions--addition, subtraction, division and multiplication. Some can also perform more intricate calculations, including corriqueiro and inverse trigonometric function ( see trigonometry). There are few inventions that have had such a profound effect on everyday life as the handheld or pocket electronic calculator. These calculators are used to cut down on time as well as to decrease the likelihood of making mistakes and are available everywhere that there are people who frequently deal with numbers - in offices, stores, banks as well as in laboratories, schools and in the homes of people.
The early calculators were mechanical: they carried out calculations using machine components, like disks, gears, and drums. These were powered via hand, and later electricity. By the mid-1950s many the mechanical calculators were being replaced by electronic calculators that contained integrated circuits - in some cases similar to the ones found in computers to provide mathematical functions. In actuality, the highly-technical electronic calculators nowadays are specifically designed, or even special-purpose computers. They contain built-in instructions on how to use certain functions.
As with other processing systems for data, calculators are of two types: digital and analog. Analog calculators operate with variable physical quantities--fluid flow or voltages, for example--and solve math-related problems through the creation of physical analogies to the issue. Slide rules, clocks, as well as utility meters, are all examples of analog calculators. Digital calculators are the ones most commonly thought of as calculators. They are directly based on numbers or digits , and operate by listing, counting as well as comparing the digits. Digital calculators include adding machines, cash registers as well as handheld or desktop electronic calculators.
PRINCIPLES OF MECHANICAL CALCULATORS
The primary component of mechanical calculators includes a set numeral-adding wheels. When a mechanical calculator is operated by a key (and for the vast majority of other types of calculators) the wheels can be viewed through the rows of small windows that are located on the front of the device. Each wheel is adorned with the numbers of 0 through 9 around its rim. Under each wheel is a column of keys marked with identical digits. The number 1 key in a column makes its numeral wheel one step. pressing the number 2 key spins the wheel two steps; and so on. When the keys 1 and 2 are pressed in succession then the wheel will advance one step and then two steps further, before finally indicating the number 3. So a column of numbers could be quickly added by simply entering the numbers on the keyboard and observing their sums on the screen. The locking mechanisms that connect the numeral wheels automatically ensure carryovers. Multiplication is accomplished by repeating addition, while subtraction is performed with an indirect method the division process is carried out by repeated subtraction.
PRINCIPLES OF ELECTRONIC CALCULATORS
Electronic calculators are carried out by integrated circuits, tiny arrays with thousands or even millions of transistors. These circuits contain permanent instructions for addition as well as subtraction, multiplication division as well as (in more advanced calculators) additional functions. The numbers entered by the operator are briefly stored in addresses or locations in the random-access memory (RAM) which is a storage space for the numbers used and created at any moment in the calculation process. The numbers stored in these locations are processed by circuits which carry instructions for mathematical operations.
HISTORY
The oldest method of calculation is the abacus. It has been in use for decades. It's comprised of moving counters placed on a marked board or strung over wires. The first version of the slide rule, often regarded as the first successful analog calculator, was created in 1620 in 1620 by English mathematician Edmund Gunter. This rule originally employed to multiply or divide numbers by adding or subtracting their logarithms. Then it was possible to use slide rules to extract square roots, and in some instances, to calculate trigonometric functions and logarithms.
MECHANICAL CALCULATORS
The first digital mechanical calculating machine, the precursor to the modern calculator--was an arithmetic machine invented by French mathematician Blaise Pascal in 1642 ( see Pascaline). In the 17th century, Gottfried Wilhelm Leibniz created a higher-tech design of Pascal's invention. It employed a shaft with increasing length of teeth, which were fixed to the shaft and a cogwheel that had 10 teeth. The cogwheel's end was displayed on a dial and was marked with the numbers 0-9. By placing the cogwheel certain directions along the shaft and then rotating the shaft in a certain direction, two numbers can be added. In order to multiply the two numbers, the shaft was rotated repeatedly. Subtraction was done via turning the shaft backward while division was done with subtraction that was repeated.
In 1878 W.T. Odhner in 1878, invented the pin-wheel. When the number was set on a machine that utilized this device, the corresponding number of pins would be moved up on wheels attached to the main shaft. When the shaft was turned, these pins joined with cogwheels whose movements provided the answer to the sum exactly the same way as did the cogwheels in Leibniz's machine. It was the development of the pin-wheel was what made it possible to make sleeker and easier to drive machines.
The first commercially successful key-driven calculatorthat was later named the Comptometer was developed by Dorr Eugene Felt in 1886. Key-driven calculators could be operated very quickly and were frequently used in offices. For a specific type of key-driven calculatorknown as a key-set machine, the number keys were first depressed or turned off. A second action, turning a crank or launching driving motors--transferred the information input into the keyboard and to the numeral wheels. The key-set principle was used for calculating machines that printed out results on paper tape as it was not possible to drive printers directly through the keys.
The first successful commercially-produced Rotary calculator was created by Frank S. Baldwin and Jay R. Monroe in 1912. The first rotary calculators incorporated a rotary mechanism that transferred numbers from the keyboard to the adding-wheel unit. Since the rotary drive lent itself to high-speed repetitive addition and subtraction they could multiply and divide very quickly as well as automatically.
Special-purpose mechanical calculators feature the cash register. The cash register was created 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 by William S. Burroughs, who was a bank clerk. Punch-card machines, initially used to regulate the operation of looms, were adapted to information processing during the 1880s, by Herman Hollerith of the United States Bureau of the Census. They read data from cards where patterns of holes were interpreted as numbers and letters.
ELECTRONIC CALCULATORS
The advancements in electronics during the 1940s and 1950s helped make possible the creation of the computer and the electronic calculator. Electronic desktop calculators which were introduced in 1960s, fulfilled the same function as mechanical calculators but had virtually no moving components. The development of miniature electronic devices with solid-state electronics brought a series of electronic calculators that could carry out many more functions and quicker operation than their mechanical counterparts. Nowadays, most mechanical calculators are replaced by electronic models.
Electronic handheld calculators can not only perform addition, subtraction, multiplication, and division but also can handle square roots percentages, and squaring when the appropriate key is press. The data being entered and the result are shown on a screen with either light-emitting diodes (LEDs) or liquid-crystal display (LCDs).
Special-purpose calculators have been developed for use in business, engineering, and other fields. Some of them are equipped to manage a variety of tasks similar to those done by larger computers. The most sophisticated electronic calculators can be programmed with complicated mathematical formulas. Some models employ interchangeable preprogrammed software modules with 5 or more program steps, but the required information must be entered manually. Many calculators have a built-in or accessory printer as well as some that can graph mathematical equations. Many calculators come with basic computer games that can be played on the calculator's display screen. In reality, the line between calculators as well as PDAs, personal digital assistants (PDAs) and portable computers has been blurred because all of these devices generally use microprocessors.
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