HOW CALCULATORS WORK

The calculator has had a profound impact on the world, making computations quicker and more exact. In the classroom, calculators have given many students the ability to learn about and put complex formulas and concepts into practice more easily.
Before the invention of the modern calculator, people used some other tools for computation. The abacus, for example, is one ancestor of the calculator. Probably of Babylonian origin, early abaci are believed to have been boards on which the position of counters stood for numerical values. However, the modern abacus -- which some people still use today in China, Japan and the Middle East -- works by moving beads along wires that are strung on a frame.


HOW THE CALCULATOR CALCULATES

Most calculators depends on integrated circuits, commonly known as chips. These circuits use transistors to add and subtract, as well as to perform computations on logarithms in order to accomplish multiplication, division and more complicated operations such as using exponents and finding square roots. Basically, the more transistors an integrated circuit has, the more advanced its functions may be. Most standard pocket calculators have identical, or very similar, integrated circuitry.

Like any electronic device, the chips inside a calculator work by reducing any information you give it to its binary equivalent. Binary numbers translate our numbers in a base-two system, in which we represent each digit by a 1 or a 0, doubling each time we move up a digit. By "turning on" each of the positions -- in other words, by putting a 1 in it -- we can say that that digit is included in our overall number.

Microchips use binary logic by turning transistors on and off literally, with electricity. So, for example, if you wanted to add 2 + 2, your calculator would convert each "2" to binary (which looks like this: 10) and then add them together. Adding the "ones" column (the two 0s), gives you 0: The chip can see that there is nothing in the first position. When it adds the digits in the "tens" column, the chip gets 1+1. It sees that both are positive, and -- since there are no 2's in binary notation -- moves the positive reply one digit to the left, getting a sum of 100 -- which, in binary terms, equals 4 [source: Wright].

This sum is routed through the input/output chip in our integrated circuit, which applies the same logic to the display itself. Have you ever noticed the way the numbers on a calculator or alarm clock are made up of segmented lines? Each one of those parts of the numerals can be turned on or off using this same binary logic. So, the processor takes that "100" and translates it by lighting up or turning on certain segments of the lines in the display to create the numeral 4.

CALCULATOR COMPONENTS

Many modern calculators have a durable plastic casing, with simple openings in the front that allow rubber to push through, just like a television remote. By pressing a button, you complete a circuit underneath the rubber, which sends electrical impulses through a circuit board below. Those impulses are routed through the microprocessor, which interprets the information and sends a readout to the calculator's display screen.

The displays of most early electronic calculators were made up of LEDs( light-emitting diodes). Newer models that use less power incorporate the liquid crystal display, or LCD. Rather than producing light, LCDs rearrange light molecules to create a pattern on the display and ultimately don't require as much electricity.

Early calculators also had to be plugged in or used bulky battery power. But by the late 1970s, solar cell technology had become cheap and efficient enough to use in consumer electronics. A solar cell creates electricity when the photons of sunlight are absorbed by semiconductors, such as silicon, in the cell. This knocks loose electrons, and the electric field of the solar cell keeps them all traveling in the same direction, thus creating an electric current. (Something like an LCD calculator would only need a low-level current, which explains why their solar cells are so small.) By the 1980s, most manufacturers of simple calculators were taking advantage of solar cell technology. More powerful scientific and graphing calculators, however, still use battery power.