Digital Technology

Digital Technology — page 1 — Counting Frame An abacus is a simple calculator It was invented at least 5,000 years ago but it is still used in some places today Long numbers are shown by ﬂ icking beads along columns arranged side by side The lower section of this one counts from 1 to 5 and the upper beads show 5 and 10 Each column adds up to 15 Introduction Computers and other digital technologies are machines controlled by a set of instructions called a program The instructions are written as a string of digits numbers that a computer can understand Today computers are in many things from toys to telephones but they started out as machines for doing calculations A DIFFERENT VIEW COUNTING STONES An ancient technique used by shepherds to count their flocks was to make a pile of pebbles one for every sheep The Latin word for pebble is calculus which is where we get the word calculate The stone piles were the world’s first calculators 4

Digital Technology — page 2 — The Pascaline The word computer was ﬁ rst used in 1613 It meant a person who did complicated calculations In 1642 Frenchman Blaise Pascal invented the Pascaline a clockwork calculator to help these human computers It could add up to 999,999 Punched Card Loom In 1801 the French weaver Joseph Marie Jacquard invented the ﬁ rst programmable machine a loom for weaving patterned cloth The program was a pattern of holes punched into a set of cards The punched cards ran through the loom telling it when to add each color of thread to the cloth Designing the pattern Punching the cards Weaving the cloth 5

Digital Technology — page 3 — Difference Engine The ﬁ rst computers were invented by Englishman Charles Babbage Like today’s computers his devices followed a program They had a memory for storing numbers and a processor for doing calculations Gear The number wheels were all ﬁ tted with a gear The number being displayed depended on how fast each gear turned A HANDLE was turned to perform the calculation Babbage designed the Difference Engine in 1822 It was a mechanical calculator for producing tables of polynomial functions These complex numbers are used by engineers and scientists and Babbage’s machine could calculate them more quickly than human computers The Difference Engine shown right could only do this one thing So in 1837 Babbage designed the Analytical Engine This could be programmed to perform any calculation This second device is regarded as the ﬁ rst true computer However Babbage could not afford to build either machine TIMELINE 1620s Slide Rule A calculator is designed by English math genius William Oughtred The slide rule has a numbered ruler that moves inside another 6 186B Writing Ball The Hansen Writing Ball invented in Denmark is the ﬁ rst typewriter The letter keys are arranged on a dome above a sheet of paper

Digital Technology — page 4 — THE FIRST COLUMN could be set to any number up to 16 digits long POWER PEOPLE ADA LOVELACE The first programmer was Ada Lovelace She was the daughter of the poet Lord Byron Lovelace wrote a plan for how to program Babbage’s Analytical Engine using punched cards THE ANSWERS are displayed on columns and read from top to bottom THIS DIFFERENCE ENGINE was constructed by a museum in the 1990s It has 25,000 parts 1872 Tide Predictor The Scottish scientist Lord Kelvin invents a mechanical computer It uses gears to calculate the time of tides around the world 1890 Tabulator The U S government buys an electrical machine for handling its population data The makers go on to start IBM which becomes the ﬁ rst big computer company 7

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