Electronic calculators

The electronic calculator is still very young, but in its 35 year old career, it has already made an enormous progress. The start of the electronic calculator has been made by IBM, designing a giant automatic calculator computer in 1939. The biggest of them all and first automatic, general-purpose digital calculator was the five-ton Mark I, using the system of binary numbers for calculating.It was created from a project involving IBM and Harvard University and delivered to Harvard in 1944 after a year of testing at the plant of Endicott, N.Y. This ‘Mark I’ was a programmable computer controlled by punched paper tape and using punched cards and was called ‘The Automatic Sequence Controlled Calculator’.

Binary numbers and binary counting
Each computer works with the binary system. The principle is simple, there are only two digits : 0 and 1.
Eg. : 5, 17, 20, 63 from the decimal system are written in binary form resp. as 101, 10001, 10100, 111111 

Addition with binary numbers.
If both numbers are 0, the solution will be 0. If one of the numbers is 0 and the other number is 1, the solution will be 1. But, if they’re both 1, it is written as 10.

0+0=0, 0+1=1, 1+0=1, 1+1=10

Those were computers, as big as a room, they weren’t the calculators we are familiar with nowadays. The small calculator, like we use up to this moment, was born in the USA. It was manufactured by the Bell Punch Company in 1963. The first widely available pocket calculator has been developed by Sinclair Clive, born in 1940.

The calculator made particularly development in its memory and display. The switches have been changed, but that wasn’t the most important.

The development of the display.

The first electronic display.

The first electronic screen contained Light-Emitting Diodes (LED). A LED is made of semiconductor material that glows when electricity is passed trough it. In 1993, chemists at the University of Cambridge, England, developed LEDs from polymen poly (p-phenylenevenyl) (PPV)that emit as much light as conventional LEDs and in various colours.

The present display

The present display is made of liquid-crystals (LCD). A liquid-crystal is produced by molecules of a substance in a semiliquid state with some crystalline properties. The display is a blank until the application of an electric field, which ‘twists’ the molecules so that they reflect or transmit light falling on them. The advantage of this system is that the energy consumption is much lower than with the LEDs.

The development of the memory.

Cathode-ray tubes.

The first useful devices were the cathode-ray tubes. A cathode-ray tube was a vacuum tube in which a beam of electrons is produced and focused onto a fluorescent screen. This system was invented at the end of the 19nd century. Those calculators were still as big as a room and were used by factories, armies etc.

Transistors.

Transistors are useful for two goals : amplifying and switching. The transistor, invented in 1947 in the Bell laboratoria by Bardeen and Brattain has a lot of advantages; they’re relative small, not heavy and dependable. And one of the most important things: they don’t cost very much. William Bradford Shockley made a better version of the transistor in 1949.

William Shockley(1910-1989) was born in the British capital London. He was 3 years old when his family moved to California because his father was American. He doctorated on the Massachusetts Institute of Technology. Immediately, he was offered a job in the Bell Laboratoria in New Jersey. He had already the idee for a transistor in 1939. He stopped working in 1942 because he had to fight in the army. But after Worldwar II, he finally finished his transistor. In 1956, he started a factory.  He wasn’t very popular, because of his extreme ideas. He hated women and black people. The same year, he, Bardeen and Brattain received the Nobelprize.

The integrated circuit, popularly called silicon chip.

The silicon chip made its entrance at the beginning of the sixties. An integrated circuit is a miniaturized electronic circuit produced on a single crystal of a semiconducting material, usually silicon. It may contain many millions of components and yet measures only 5mm/0.2 in square and 1 mm/0.04 in thickniss. A very important step forward in chemistry is the discovery of the semiconducting materials : germanium and silicon. Silicon is a nonmetallic element, symbol Si, atomic number 14. It’s the second-most abundant element (after oxygen) in the Earth’s crust and occurs in amorphous and crystalline forms. In nature it is found in combination with other elements, mainly with oxygen in silica (silicon dioxide, SiO2) and the silicates. These form the mineral quartz, which is the main substance of most sands, gravels and beaches. The element was isolated by the Swedish chemist Jöns Berzelius in 1823. The name silicon was given in 1817 by Scottish chemist Thomas Thomson on the analogy of boron and carbon because of its chemical resemblance to these elements.

The MPU : Micro Processing Unit

In 1969 Busicom was planning to sell high-performance calculators for scientific calculations and gave an order to Intel to produce 13 different types of semi-conductors. Just then, Mr. Ted Hoff, ex researcher from Stanford University, joined Intel and saw his chance to realise an idea he had had in his mind for some time. His thinking was an integrated circuit (I.C.) which would accommodate multiple instructions on to a single chip.

The power of the Intel's 4004 IC chip, generally acknowledged as the world's first "microcomputer on a chip" or "microprocessor", was incredible.Twenty five years before this (in 1946) engineers and scientists developed the ENIAC computer - equipped with 18.000 of vacuum tubes, weighing 30 tons and having 3000-cubic foot mass. In 1971 engineers placed the same amount of computing power on a piece of silicon no larger than 1/4" square and the price for that was now affordable!.

That was the moment when the electronic calculator took off. At this time Bill Hewlett (electrical engineer 1939 also from Stanford University) directed Hewlett-Packard engineers towards a project to develop a scientific calculator, using the new chips of INTEL, so small that would fit in a shirt pocket. When Hewlett-Packard came out with the world's first scientific model(the HP-35) in January 1972, it was backordered for 4 to 5 months because of the demand. Calculating tough sets of numbers was now easy and accurate. Trigonometric tables were unnecessary and quickly forgotten. The resolution of your answer was as fine as you wanted it to be and best of all it was very quick...slide rules were on their deathbed and the genie was out of the bottle. 

Marijke De Belder

Sources

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