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Computer history.Thing that Changed the World

Computer history.

Introduction The Eras of Computers

First era [simple tools ] Second era [Mechanical

& Electro-mechanical Era (1623-1945)] Third era [Electronic Era (present)]

Generations

Who invented the computer ?

• It is not a question with a simple answer. The real answer is that many inventors contributed to the history of computers and that a computer is a complex piece of machinery made up of many parts, each of which can be considered a separate invention.

IntroductionThe first computers were people

• Computers were given this name because they performed the work that had previously been assigned to people. "Computer" was originally a job title.

• It was used to describe those human beings (predominantly women) whose job it was to perform the repetitive calculations required to compute.

Introduction

• So imagine you had a job where hour after hour, day after day, you were to do nothing but compute multiplications. Boredom would quickly set in, leading to carelessness, leading to mistakes. And even on your best days you wouldn't be producing answers very fast. Therefore, inventors have been searching for hundreds of years for a way to mechanize this task.

Introduction

This picture shows what were known as "counting tables"

Introduction

• The earliest counting devices known to man were his own hands and fingers. If that wasn't enough , things in nature were used like shells, stones.

First era [simple tools ]

• Man's invention of the computer resulted from man's need to quantify ,to do mathematic calculations ,man was inventing easier and faster ways of calculating.


• The most important One of this earlier invention was The abacus .

• The abacus is a simple counting aid, may have been invented in Babylonia (now Iraq) in the fourth century B.C.

• Its only value is that it aids the memory of the human performing the calculation.

A very old abacus

A more modern abacus


• The abacus is considered the first personal calculator

• So we can say that Computers have their beginnings back in pre-history, starting with the abacus.

• A century later, the Arabs invented the decimal numbering system — the basic language of mathematics .


• Arabic numerals are introduced to Europe in the 8 and 9 centuries A.D. Roman numerals remain in use in some parts of Europe until the 17 century. The Arabic system introduced the concepts of the 0 and fixed places for tens, hundreds, thousand, etc., and greatly simplified mathematical calculations.

• The model of the abacus integrated the knowledge of the decimal number system and evolved into a mechanical calculator.

• In the 17 century John Napier, invents logs in 1614. Logs allow multiplication and division to be reduced to addition and subtraction.

• where the logarithm values were carved on

ivory sticks which are now called Napier's Bones

An original setof Napier's Bones


A more modern set of Napier's Bones

The Mechanical Era (1623-1945)

• Wilhelm Schickard builds the first mechanical calculator in 1623. to actually be built was probably the calculating clock It can work with six digits, and carries digits across columns.

Schickard's Calculating Clock

The Mechanical Era (1623-1945)• In 1642 Blaise Pascal, at age 19, invented

the Pascaline as an aid for his father who was a tax collector It used addition to subtract, multiple and divide .

• Blaise Pascal builds a mechanical calculator. It has the capacity for eight digits, but has trouble carrying and its gears tend to jam.

• Although this machine could perform addition and subtraction on whole numbers, it was too expensive and only Pascal himself could repair it

Pascaline 6 digit model

A Pascaline opened up so you can observe the gears and cylinders which rotated to display the numerical result


• Joseph-Marie Jacquard invents an automatic loom controlled by punch cards.

The Mechanical Era (1623-1945)How the automated loom machine work

• automated loom machine operated by dropping needles through holes punched in cards. When the needle passed through the hole it lifted a weaving thread, if the needle did not drop through the hole the weaving thread lowered. When the weaving shuttle passed through the threads it developed a pattern.

A close-up of a Jacquard card

Jacquard's Loom showing the threads and the punched cards

automated loom machine

• Since the needles were up or down like on or off switches used in computers today the automated loom is considered the “true digital computer”.

• the punched card system later applied to the U.S. census and then to computers...


• By 1822 the English mathematician Charles Babbage was proposing a steam driven calculating machine the size of a [room], which he called the Difference Engine

• This machine would be able to compute tables of numbers, such as logarithm tables

• Ten years later the device was still nowhere near complete, acrimony abounded between all involved, and funding dried up. The device was never finished.

A small section of the type of mechanism employed in Babbage's Difference Engine


• Babbage was not deterred, and by then was on to his next brainstorm, which he called the Analytic Engine. This device, large as a house and powered by 6 steam engines

• Babbage who made an important intellectual leap regarding the punched, the presence or absence of each hole in the card physically allows a colored thread to pass or stops that thread cards In the Jacquard loom,

The Mechanical Era (1623-1945)• Babbage saw that the pattern of holes

could be used to represent an abstract idea such as a problem statement or the raw data required for that problem's solution.

• The Analytic Engine also had a key function that distinguishes computers from calculators (conditional statement)

• Furthermore, Babbage realized that punched paper could be employed as a storage mechanism, holding computed numbers for future reference


Ada Byron Though she was only 19, she was fascinated by Babbage's ideas and through letters and meetings with Babbage she learned enough about the design of the Analytic Engine to begin fashioning programs for the still unbuilt machine

Ada wrote a series of "Notes" wherein she detailed sequences of instructions she had prepared for the Analytic Engine


But Ada earned her spot in history as the first computer programmer. Ada invented the subroutine and was the first to recognize the importance of looping .


• Hollerith's invention, known as the Hollerith desk consisted of a card reader which sensed the holes in the cards .

An operator working at a Hollerith Desk like the one below

A few Hollerith desks still exist today


• The patterns on Jacquard's cards were determined when a tapestry was designed and then were not changed. Today, we would call this a read-only form of information storage. Hollerith had the insight to convert punched cards to what is today called a read/write technology.

• Hollerith's technique was successful and the 1890 census was completed in only 3 years at a savings of 5 million dollars.

Preparation of punched cards for the U.S. census

Incidentally, the Hollerith census machine was the first machine to ever be featured on a magazine cover.


• Hollerith built a company, the Tabulating Machine Company which, after a few buyouts, eventually became International Business Machines, known today as IBM.

• IBM grew rapidly and punched cards became ubiquitous .

The end of the Mechanical Era• As physics paved the way for electrical

innovation, scientists discovered in electrical charge a way to represent data. The beads of the abacus were replaced by bits in the modern computer – essentially a bit or ‘binary digit’ is a small electrical charge that represents a 1 or 0. The creation of the bit marked a transition from the decimal system for humans (10 primary numbers from zero to nine) to a binary system for computers (only two numbers, 0 and 1).

Electro-Mechanical Era (1920 - 1945)

• For the first time electricity was used in the operation of computers, but computers still had many mechanical components.

• Programming a computer did not involve software. Rather, the programmer actually rewired the paths of electricity through the machine in order to change its mode of operation

Third era [Electronic Era (present)]

• This era development is often referred to in reference to the different generations of computing devices. Each generation of computer is characterized by a major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more powerful and more efficient and reliable devices.

Computer Generations

• (Zero Generation -1920's Electro-mechanical) • First Generation - 1940-1956: Vacuum Tubes

• Second Generation - 1956-1963: Transistors

• Third Generation - 1964-1971: Integrated Circuits

• Fourth Generation - 1971-Present: Microprocessors

• Fifth Generation - Present and Beyond: Artificial Intelligence