A calculator is a device that can do arithmetic calculations with accuracy and speed. They are mainly of two types: mechanical and electronic. Electronic calculators have almost replaced the mechanical type due to their technological superiority, better speed and accuracy.
The working principle of calculators went through a continuous process of modification and improvisation. To trace its history, the abacus is considered to be the first calculating machine. It was an oblong frame holding wires on which beads were strung and calculation was done by sliding the beads along the wires. The first mechanical calculator was built in 1623 by Wilhelm Schickard in Germany. A better and more famous one was made by Blaise Pascal in 1642 and ‘Arithnometer’ was the first calculator to go on side, invented by Charles Thomas in 1820. Mechanical calculators had gearwheels inside them and to do the calculations, a handle connected to the gearwheels had to be wound many times. Their disadvantages were that they were large, heavy, slow and prone to breakdown after heavy use. They are no longer manufactured though still in use at a few places.
The advent of electronic calculators in 1963 was a result of the electronic revolution when the first electronic calculator was produced by the British Bell Punch Company. In fact a calculator developed by Charles Babbage in 1832 is considered to be the forerunner of computer. The electronic calculators use tiny electronic circuit to perform basic arithmetic calculations and some of them can even perform complex calculations involving trigonometry and calculus. The first electronic calculator used thousands of discrete transistors in its circuitry and brought an end of the era of mechanical calculators. The introduction of integrated circuits by Fairchild and Texas Instruments was another milestone in the history of calculators. An integrated circuit contains the equivalent of many thousands of transistors and their associated components and is built up from a single chip of silicon as small as 0.3 sq. cm. This helped in the manufacture of cheap and portable calculators. Most electronic calculators have a memory to store information.
Electronic calculators are of two types: Desktop and Portable. Desktop calculators are usually plugged into the mains and have a printer to get printed answers on a paper whereas portable calculators are small enough to fit in our pocket. The operation of a calculator is regulated by a clock circuit which, as its name implies, generates timing pulses that are used to synchronize the operations of other sections of the machine. In a simple calculator, the clock may operate at a rate of about 250,000 pulses per sec. that would enable it to perform 250,000 operations in one second.
The calculators use a form of binary arithmetic to perform their calculations, being based on the number 2, all binary numbers can be represented by combinations of 1’s and 0’s.
The form of binary arithmetic used by calculators is known as binary-coded decimal (BCD), and the calculator contains an encoder which translates the decimal information from the key-board into the BCD, and a decoder which translates the BCD into decimal form to derive the output display.
Some electronic calculators can be programmed to perform certain operations automatically. Electronic calculators are extremely accurate and easy to use.
