calculators
INTRODUCTION
Electromechanical, mechanical electronic devices that can perform math-related calculations automatically are referred to as calculators. Calculators perform functions that perform the standard Arithmetic operations--subtraction, addition division and multiplication. Some are also capable of performing more complex calculations, such as costumeiro trigonometric functions as well as inverse trigonometric ( see trigonometry). The few innovations of the past decade have had as significant an influence on the daily routine like the handheld, or pocket electronic calculator. These calculators can be used to help save time and reduce the risk of making errors and are used wherever people deal frequently with numbers--in stores, offices, banks and schools, labs, as well as in private homes.
The earliest calculators were mechanical: they made calculations using machine components, like disks, drums, and gears that were powered via hand, and later electricity. In the late 1950s, a lot of these mechanical calculators were being replaced by electronic calculators with integrated circuits - in some cases similar to the circuits in computers--to perform mathematical functions. In reality, the modern electronic calculators of today are specially-purpose computers. They are equipped with instructions that tell you how to conduct certain functions.
Like other data-processing systems, calculators are of two types: digital and analog. Analog calculators utilize fluid flow or voltages, as an example. They solve mathematical problems by creating an analogy physical to the problem. Clocks, slide rules, along with utility meters comprise all examples that are analog calculators. Digital calculators are those that are often thought of as calculators. They deal directly with numbers or digits , and operate by counting, listing while comparing and then rearranging these numbers. A common set of digital calculators include adding machines, cash registers and desktop or handheld electronic calculators.
PRINCIPLES OF MECHANICAL CALCULATORS
The fundamental part of all mechanical calculators comprises a set of numeral-adding wheels. In a key-driven mechanical calculator (and in many other models) they are visible through a series of tiny windows on the front of the device. Each wheel is adorned with the numbers between 0 and 9 on the edges. Behind each wheel, there is a row of keys that have the same numerals. Pressing the key 1 in a column rotates its numeral wheel by one step. pressing the number 2 key turns the wheel two steps; and so on. When the keys 1 and 2 are repeatedly pressed then the wheel will advance one step, then two moresteps, finally signalling the number 3. Thus a column of numbers may be added rapidly by entering the numbers into the keyboard and reading their totals on the windows. Interlocking mechanisms between the numeral wheels automatically permit carryovers. Multiplication is carried out by repeating subtraction; addition is carried out through indirect methods the division process is carried out by repeated subtraction.
PRINCIPLES OF ELECTRONIC CALCULATORS
The electronic calculators are carried out by integrated circuits--tiny arrays consisting of thousands, even millions of transistors. These circuits are equipped with permanent instructions for addition, subtraction, multiplication, division, and (in more sophisticated calculators) additional functions. The numbers that the operator enters are briefly stored in addresses, or locations, in the memory known as random-access (RAM) that contains capacity for the numbers used and generated at any time when the computer calculates. The numbers stored in these addresses are then processed by circuits that carry the instructions for the mathematical operations.
HISTORY
The oldest calculator is the abacus, which has been used for many thousands of years. It's comprised of moving counters that were placed on a marking board or strung on wires. An early form of the slide rule, frequently referred to as the very first digital calculator that worked, was created in 1620 in 1620 by English mathematician Edmund Gunter. This rule initially used to divide or multiply numbers by adding or subtracting their logarithms. Later it became 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 algebraic machine developed by the French mathematician Blaise Pascal in 1642 ( see Pascaline). In the 17th century, Gottfried Wilhelm Leibniz created a more sophisticated variation of Pascal's machines. It employed a shaft with more and longer teeth fixed on the cogwheel, and 10 teeth. The cogwheel's edge could be seen on a dial, and was marked with the numbers 0-9. By putting the cogwheel a particular direction on the shaft and then turning the shaft in a certain direction, two numbers can be added. For the purpose of multiplying two numbers by turning the shaft multiple times. Subtraction was performed by turning the shaft backward while division was done through subtraction repeated.
In 1878 W.T. Odhner in 1878, invented the pin-wheel. When a specific number was entered on a machine with this device, the corresponding number of pins would be raised on wheels carried on the shaft. When the shaft rotated, the pins interlocked with the cogwheels, whose revolutions gave answers to the question similarly to the way they did those on Leibniz's machines. The invention of the pin-wheel has made it possible to create sleeker and easier to drive machines.
The first key-driven calculator, later dubbed the Comptometer was developed by Dorr Eugene Felt in 1886. Key-driven calculators were able to be operated swiftly and were extensively used in offices. For a specific type of key-driven calculator, also known as a key-set device, the number keys were first pressed, or they were cocked. A subsequent action -- turning a crank or starting driving motors--transferred the information put into the keyboard to the numeral wheels. Key-set was utilized to calculate machines that printed outputs on the paper tape, since it was impossible to control printers directly using the keys.
The first successful commercially-produced circular calculator was designed by Frank S. Baldwin and Jay R. Monroe in 1912. Rotary calculators included a rotary mechanism that transferred numbers from your keyboard to the add-wheel unit. Since the rotary drive lent itself to high-speed repetitive subtraction and addition the machines were able to be able to multiply and divide extremely quickly and also automatically.
Special-purpose mechanical calculators consist of the cash register. The cash register was invented in 1879 James Ritty, a storekeeper, to ensure the honesty of his staff. The first bookkeeping machine, an adding-printing device--was made in 1891 in 1891 by William S. Burroughs, who was a bank clerk. Punch-card machinesthat were originally designed to regulate the operation weaving machines, were upgraded to processing information through the 1880s 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
Developments in electronics in the 1940s, 1950s, and 1960s made possible the invention of the computer as well as the electronic calculator. Electronic desktop calculators made their debut in the 1960s, had the same functions as mechanical calculators but were essentially without moving components. The development of miniature electronic devices that used solid state technology brought a series of electronic calculators with much more functions and more efficient than their mechanical counterparts. Today most mechanical calculators have been replaced by electronic models.
These modern handheld electronic calculators can not only perform multiplication, subtraction and division, but can handle square roots, percentages, and squaring. This is when the appropriate keys are press. The input data and the result are displayed on screens using LEDs or either (LEDs) or liquid-crystal monitors (LCDs).
Special-purpose calculators were designed for use in business, engineering as well as in other fields. Certain of them are able to complete a range of work similar to the work of larger computers. Sophisticated electronic calculators can be programmed using complicated mathematical formulas. Some models employ interchangeable preprogrammed software modules with 5,000 or more program steps, though the necessary data must still be keyed manually. Many calculators have a built-in or an accessory printer and some even graph mathematical equations. Many calculators have basic computer games that can be played on the calculator's screen. In reality, the line between calculators and PDAs, personal digital assistants (PDAs), and portable computers has blurred because all of these devices nowadays typically utilize microprocessors.
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