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Chapter 1

The Big Picture

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Computing systems are dynamic entities used to solve problems and interact with their environment.

They consist of devices, programs, and data.

Computing Systems

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Hardware - The physical elements of a computing system (printer, circuit boards, wires, keyboard…).

Software - The programs that provide the instructions for a computer to execute.

Data - Information in a form a computer can use.

Computing Systems

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Communication

Application

Operating System

Programming

Hardware

Information

Layers of a Computing System

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Abstraction - A mental model that removes complex details.

This is a key concept. Abstraction will reappear throughout the course – be sure you

understand it!

Abstraction

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Abacus (2400 BC)An early device to record numeric values.

Blaise Pascal (1623-1662)Created a mechanical device to add, subtract, divide & multiply.

Gottfried Wilhelm von Leibniz (1646-1716)Created a mechanical device to perform all four whole number operations.

Joseph JacquardJacquard’s Loom (1801), the punched card

Early History of Computing

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Early History of Computing

Charles Babbage (1792-1871)Difference Engine, Analytical Engine

Augusta Ada Byron (Lovelace) Babage’s assistantConsidered to be the first Programmer,

Invented the concept of the loop

William Burroughs (1857-1898)Adding Machine

Herman Hollerith (1860-1929)Electro-mechanical Tabulator

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Alan Turing (1912-1954)Turing Machine - an abstract mathematical modelArtificial Intelligence Testing

Early computers launch new era in mathematics, physics, engineering and economics.

Harvard Mark I (1939)ENIAC - Electronic Numerical Integrator and CalculatorEDVAC - Electronic Discrete Variable Automatic Computer

first machine with a stored programUNIVAC I - Universal Automatic Computer (1951)

Early History of Computing

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Vacuum TubesLarge, not very reliable, generated a lot of heat

Magnetic Drum Memory device that rotated under a read/write head

Card Readers Magnetic Tape DrivesSequential auxiliary storage devices

First Generation Hardware (1951-1959)

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TransistorReplaced vacuum tubefast, small, durable, cheap

Magnetic CoresReplaced magnetic drumsinformation available instantly

Magnetic DisksReplaced magnetic tapedata can be accessed directly

Second Generation Hardware (1959-1965)

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Integrated CircuitsReplaced circuit boardssmaller, cheaper, faster, more reliable

TransistorsNow used for memory construction

Terminal An input/output device with a keyboard and screen

Third Generation Hardware (1965-1971)

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Large-scale IntegrationGreat advances in chip technology

PCs, the Commercial Market, WorkstationsPersonal Computers were developed as new companies like Apple and Atari came into being. Workstations emerged.

Fourth Generation Hardware (1971-?)

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Parallel ComputingComputers rely on interconnected central processing units that increase processing speed.

NetworkingWith the Ethernet small computers could be connected and share resources. A file server connected PCs in the late 1980s.

ARPANET and LANs Internet

Parallel Computing and Networking

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Machine LanguageComputer programs were written in binary (1s and 0s).

Assembly Languages and translatorsPrograms were written in artificial programming languages and were then translated into machine language.

Programmer ChangesProgrammers divide into application programmers and systems programmers.

First Generation Software (1951-1959)

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High Level LanguagesEnglish-like statements make programming easier. Fortran, COBOL, Lisp are examples.

High-LevelLanguages

Assembly LanguageMachine

Language

Second Generation Software (1959-1965)

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Third Generation Software (1965-1971) Systems Software

utility programs, language translators, and the operating system, which decides which

programs to run and when. Separation between Users and Hardware

Computer programmers began to write programs to be used by people who did not know how to program.

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Application Package

Systems Software

High-Level Languages

Assembly Language

Machine Language

Third Generation Software (1965-1971)

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Structured ProgrammingPascal, C, C++

New Application Software for Usersspreadsheetsword processorsdatabase management systems

Fourth Generation Software (1971-1989)

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MicrosoftThe Windows operating system, and other Microsoft application programs dominate the market.

Object-Oriented DesignBased on a hierarchy of data objects (i.e. Java).

World Wide WebAllows easy global communication through the Internet.

New UsersToday’s user needs no computer knowledge.

Fifth Generation Software (1990- present)

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Programmer / User

Applications Programmer(uses tools)

User with No Computer Background

Systems Programmer(builds tools)

Domain-Specific Programs

Computing as a Tool