Chapter 01

Nell Dale & John Lewis

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Describe the layers of a computer system

Describe the concept of abstraction and its relationship to computing

Describe the history of computer hardware and software

Describe the changing role of the computer user

Distinguish between systems programmers and applications programmers

Distinguish between computing as a tool and computing as a discipline

Chapter One Goals

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Computing systems are dynamic!

What is the difference between hardware and software?

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

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Communication

Application

Operating System

Programming

Hardware

Information

Layers of a Computing System

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A mental model that removes complex details

This is a key concept. Abstraction will reappear throughout the text – be sure to understand it!

Abstraction

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Abacus An early device to record numeric values

Blaise Pascal Mechanical device to add, subtract, divide & multiply

Joseph Jacquard Jacquard’s Loom, the punched card

Charles BabbageAnalytical Engine

Early History of Computing

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Ada LovelaceFirst Programmer, the loop

Alan TuringTuring Machine, Artificial Intelligence Testing

Harvard Mark I, ENIAC, UNIVAC IEarly computers launch new era in mathematics, physics, engineering and economics

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 DrivesDevelopment of these sequential auxiliary storage devices

First Generation Hardware (1951-1959)

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TransistorReplaced vacuum tube, fast, small, durable, cheap

Magnetic CoresReplaced magnetic drums, information available instantly

Magnetic DisksReplaced magnetic tape, data can be accessed directly

Second Generation Hardware (1959-1965)

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Integrated CircuitsReplaced circuit boards, smaller, 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 LanguagesUse English-like statements and made programming easier: Fortran, COBOL, Lisp.

High-LevelLanguages

Assembly Language

MachineLanguage

Second Generation Software (1959-1965)

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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 now created programs to be used by people who did not know how to program

Third Generation Software (1965-1971)

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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 UsersSpreadsheets, word processors, database 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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How does the Internet affect your everyday life?

What social issues stem from the rise of the Internet and the World Wide Web?

What developments do you see for the future of the Internet?

Questions to Ponder

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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

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What Can be (efficiently) Automated?

Four Necessary Skills 1. Algorithmic Thinking 2. Representation 3. Programming 4. Design

Computing as a Discipline

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Is Computer Science a Mathematical, Scientific, or Engineering discipline?

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What do you think?

Computing as a Discipline

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Algorithms and Data Structures Programming Languages Architecture Operating Systems Software Methodology and Engineering Human-Computer Communication

Systems Areas of Computer Science

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Numerical and Symbolic Computation Databases and Information Retrieval Artificial Intelligence and Robotics Graphics Organizational Informatics Bioinformatics

Application Areas of Computer Science